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Software Patent Abstract
Digital-imaging based code symbol reading system employing an event-driven
multi-tier modular software architecture and supporting automatic
operating system login and loading of a bar code symbol reading
application.
Software Patent Claims
1. A digital-imaging based code symbol reading system comprising:
a housing having a light transmission window; a digital image formation
and detection subsystem, disposed in said housing, and having (i)
image formation optics for projecting a field of view (FOV) through
said light transmission window and upon an object to be imaged in
said FOV, and (ii) an area-type image detecting array for detecting
imaged light reflected off the object during illumination operations
in an image capture mode in which rows of sensor elements in said
area-type image detecting array are enabled so as to detect one
or more 2D digital images of the object formed on said area-type
image detecting array; an illumination subsystem, disposed in said
housing, and having an illumination array for producing and projecting
a field of illumination through said light transmission window and
within said FOV during the image capture mode; an illumination control
subsystem disposed in said housing, for controlling the operation
of said illumination subsystem during said image capture mode; an
image capturing and buffering subsystem disposed in said housing,
for capturing and buffering said one or more 2D digital images detected
by said image formation and detection subsystem; a digital image
processing subsystem disposed in said housing, for processing said
one or more 2D digital images captured and buffered by said image
capturing and buffering subsystem, so as to read one or more 1D
and/or 2D code symbols graphically represented therein, and producing
symbol character data representative of said read one or more 1D
and/or 2D code symbols; an input/output subsystem for transmitting
said output data to an external host system or other information
receiving or responding device; a system control system for controlling
and/or coordinating the operation of said subsystems above; and
a computing platform for supporting the implementation of one or
more of said subsystems above, and including (i) memory for storing
at least one code symbol reading application, and (ii) a microprocessor
for running at least one code symbol reading application; and wherein
said memory comprises a memory architecture that supports a multi-tier
modular software architecture characterized by an Operating System
(OS) Layer having automatic login, and an Application Layer in which
at least one said code symbol reading application is automatically
run, and being responsive to the generation of a triggering event
within said digital-imaging based code symbol reading system.
2. The digital-imaging based code symbol reading system of claim
1, wherein said multi-tier modular software architecture is further
characterized a System CORE (SCORE) layer disposed between said
Application Layer and said OS Layer.
3. The digital-imaging based code symbol reading system of claim
2, wherein said computing platform further comprises Flash ROM for
storing at least one code symbol reading application, and RAM for
storing said one or more 2D digital images captured and buffered
by said image capturing and buffering subsystem.
4. The digital-imaging based code symbol reading system of claim
1, wherein said FOV is projected through said light transmission
window and upon an object to be imaged in said FOV.
5. The digital-imaging based code symbol reading system of claim
1, wherein said housing contains all of said subsystems.
6. The digital-imaging based code symbol reading system of claim
1, wherein said memory maintains system parameters used to configure
said functions of said digital image capture and processing system.
7. The digital-imaging based code symbol reading system of claim
1, wherein said computing platform implements said digital image
processing subsystem, said input/output subsystem and said system
control subsystem.
8. The digital-imaging based code symbol reading system of claim
2, wherein said OS Layer includes one or more software modules selected
from the group consisting of an OS kernal module, an OS file system
module, and device driver modules; wherein said SCORE Layer includes
one or more of software modules selected from the group consisting
of a tasks manager module, an events dispatcher module, an input/output
manager module, a user commands manager module, the timer subsystem
module, an input/output subsystem module and an memory control subsystem
module; wherein said Application Layer includes one or more software
modules selected from the group consisting of a code symbol decoding
module, a function programming module, an application events manager
module, a user commands table module, and a command handler module.
9. The digital-imaging based code symbol reading system of claim
2, wherein, prior to capturing one or more digital images of the
object, said microprocessor rapidly initializes said micro-computing
platform by performing the following operations: (1) accessing one
or more software modules from said OS layer and executing code contained
therein; (2) accessing one or more software modules from said SCORE
layer and executing code contained therein; and (3) accessing one
or more software modules from said Application Layer and executing
code contained therein.
10. The digital-imaging based code symbol reading system of claim
1, wherein said field illumination comprises narrow-band illumination
produced from an array of light emitting diodes (LEDs).
11. The digital-imaging based code symbol reading system of claim
1, wherein said digital image processing subsystem processes said
one or more digital images, so as to read one or more code symbols
graphically represented therein, and producing output data in the
form of symbol character data representative of said read one or
more code symbols.
12. The digital-imaging based code symbol reading system of claim
11, wherein each said code symbol is a bar code symbol selected
from the group consisting of a 1D bar code symbol, a 2D bar code
symbol, and a data matrix type code symbol structure.
13. The digital-imaging based code symbol reading system of claim
1, said computing platform implements said digital image processing
subsystem, said input/output subsystem and said system control subsystem,
and wherein said Application Layer includes said one or more libraries
and said one or more libraries include one or more software modules
selected from the group consisting of a code symbol decoding module,
a function programming module, an application events manager module,
a user commands table module, and a command handler module.
14. The digital-imaging based code symbol reading system of claim
1, which further comprises an automatic object detection subsystem
for automatically detecting the presence of the object in said FOV,
and in response thereto, generating a trigger signal indicative
of a triggering event.
15. The digital-imaging based code symbol reading system of claim
14, wherein an IR object detection software driver, located within
said OS Layer, is installed automatically.
16. The digital-imaging based code symbol reading system of claim
1, which further comprises a trigger manually actuatable by an operator
of said digital image capturing and processing system so as to generate
a trigger signal indicating a triggering event.
Software Patent Description
RELATED CASES
[0001] This application is a Continuation of U.S. application Ser.
No. 10/893,800 filed Jul. 16, 2004; which is a Continuation of U.S.
application Ser. No. 10/712,787 filed Nov. 13, 2003, now U.S. Pat.
No. 7,128,266 B2; each said application being assigned to Metrologic
Instruments, Inc. and incorporated herewith.
BACKGROUND OF INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to hand-supportable and portable
area-type digital bar code readers having diverse modes of digital
image processing for reading one-dimensional (1D) and two-dimensional
(2D) bar code symbols, as well as other forms of graphically-encoded
intelligence.
[0004] 2. Brief Description of the State of the Art
[0005] The state of the automatic-identification industry can be
understood in terms of (i) the different classes of bar code symbologies
that have been developed and adopted by the industry, and (ii) the
kinds of apparatus developed and used to read such bar code symbologies
in various user environments.
[0006] In general, there are currently three major classes of bar
code symbologies, namely: one dimensional (1D) bar code symbologies,
such as UPC/EAN, Code 39, etc.; 1D stacked bar code symbologies,
Code 49, PDF417, etc.; and two-dimensional (2D) data matrix symbologies.
[0007] One Dimensional optical bar code readers are well known
in the art. Examples of such readers include readers of the Metrologic
Voyager.RTM. Series Laser Scanner manufactured by Metrologic Instruments,
Inc. Such readers include processing circuits that are able to read
one dimensional (1D) linear bar code symbologies, such as the UPC/EAN
code, Code 39, etc., that are widely used in supermarkets. Such
1D linear symbologies are characterized by data that is encoded
along a single axis, in the widths of bars and spaces, so that such
symbols can be read from a single scan along that axis, provided
that the symbol is imaged with a sufficiently high resolution along
that axis.
[0008] In order to allow the encoding of larger amounts of data
in a single bar code symbol, a number of 1D stacked bar code symbologies
have been developed, including Code 49, as described in U.S. Pat.
No. 4,794,239 (Allais), and PDF417, as described in U.S. Pat. No.
5,340,786 (Pavlidis, et al.). Stacked symbols partition the encoded
data into multiple rows, each including a respective 1D bar code
pattern, all or most of all of which must be scanned and decoded,
then linked together to form a complete message. Scanning still
requires relatively high resolution in one dimension only, but multiple
linear scans are needed to read the whole symbol.
[0009] The third class of bar code symbologies, known as 2D matrix
symbologies offer orientation-free scanning and greater data densities
and capacities than their 1D counterparts. In 2D matrix codes, data
is encoded as dark or light data elements within a regular polygonal
matrix, accompanied by graphical finder, orientation and reference
structures. When scanning 2D matrix codes, the horizontal and vertical
relationships of the data elements are recorded with about equal
resolution.
[0010] In order to avoid having to use different types of optical
readers to read these different types of bar code symbols, it is
desirable to have an optical reader that is able to read symbols
of any of these types, including their various subtypes, interchangeably
and automatically. More particularly, it is desirable to have an
optical reader that is able to read all three of the above-mentioned
types of bar code symbols, without human intervention, i.e., automatically.
This is turn, requires that the reader have the ability to automatically
discriminate between and decode bar code symbols, based only on
information read from the symbol itself. Readers that have this
ability are referred to as "auto-discriminating" or having
an "auto-discrimination" capability.
[0011] If an auto-discriminating reader is able to read only 1D
bar code symbols (including their various subtypes), it may be said
to have a 1D auto-discrimination capability. Similarly, if it is
able to read only 2D bar code symbols, it may be said to have a
2D auto-discrimination capability. If it is able to read both 1D
and 2D bar code symbols interchangeably, it may be said to have
a 1D/2D auto-discrimination capability. Often, however, a reader
is said to have a 1D/2D auto-discrimination capability even if it
is unable to discriminate between and decode 1D stacked bar code
symbols.
[0012] Optical readers that are capable of 1D auto-discrimination
are well known in the art. An early example of such a reader is
Metrologic's VoyagerCG.RTM. Laser Scanner, manufactured by Metrologic
Instruments, Inc.
[0013] Optical readers, particularly hand held optical readers,
that are capable of 1D/2D auto-discrimination and based on the use
of an asynchronously moving 1D image sensor, are described in U.S.
Pat. Nos. 5,288,985 and 5,354,977, which applications are hereby
expressly incorporated herein by reference. Other examples of hand
held readers of this type, based on the use of a stationary 2D image
sensor, are described in U.S. Pat. Nos. 6,250,551; 5,932,862; 5,932,741;
5,942,741; 5,929,418; 5,914,476; 5,831,254; 5,825,006; 5,784,102,
which are also hereby expressly incorporated herein by reference.
[0014] Optical readers, whether of the stationary or movable type,
usually operate at a fixed scanning rate, which means that the readers
are designed to complete some fixed number of scans during a given
amount of time. This scanning rate generally has a value that is
between 30 and 200 scans/sec for 1D readers. In such readers, the
results the successive scans are decoded in the order of their occurrence.
[0015] Imaging-based bar code symbol readers have a number advantages
over laser scanning based bar code symbol readers, namely: they
are more capable of reading stacked 2D symbologies, such as the
PDF 417 symbology; more capable of reading matrix 2D symbologies,
such as the Data Matrix symbology; more capable of reading bar codes
regardless of their orientation; have lower manufacturing costs;
and have the potential for use in other applications, which may
or may not be related to bar code scanning, such as OCR, security
systems, etc
[0016] Prior art imaging-based bar code symbol readers suffer from
a number of additional shortcomings and drawbacks.
[0017] Most prior art hand held optical reading devices can be
reprogrammed by reading bar codes from a bar code programming menu
or with use of a local host processor as taught in U.S. Pat. No.
5,929,418. However, these devices are generally constrained to operate
within the modes in which they have been programmed to operate,
either in the field or on the bench, before deployment to end-user
application environments. Consequently, the statically-configured
nature of such prior art imaging-based bar code reading systems
has limited their performance.
[0018] Prior art imaging-based bar code symbol readers with integrated
illumination subsystems also support a relatively short range of
the optical depth of field. This limits the capabilities of such
systems from reading big or highly dense bar code labels.
[0019] Prior art imaging-based bar code symbol readers generally
require separate apparatus for producing a visible aiming beam to
help the user to aim the camera's field of view at the bar code
label on a particular target object.
[0020] Prior art imaging-based bar code symbol readers generally
require capturing multiple frames of image data of a bar code symbol,
and special apparatus for synchronizing the decoding process with
the image capture process within such readers, as required in U.S.
Pat. Nos. 5,932,862 and 5,942,741 assigned to Welch Allyn, Inc.
[0021] Prior art imaging-based bar code symbol readers generally
require large arrays of LEDs in order to flood the field of view
within which a bar code symbol might reside during image capture
operations, oftentimes wasting large amounts of electrical power
which can be significant in portable or mobile imaging-based readers.
[0022] Prior art imaging-based bar code symbol readers generally
require processing the entire pixel data set of capture images to
find and decode bar code symbols represented therein.
[0023] Many prior art Imaging-Based Bar Code Symbol Readers require
the use of decoding algorithms that seek to find the orientation
of bar code elements in a captured image by finding and analyzing
the code words of 2-D bar code symbologies represented therein.
[0024] Some prior art imaging-based bar code symbol readers generally
require the use of a manually-actuated trigger to actuate the image
capture and processing cycle thereof.
[0025] Prior art imaging-based bar code symbol readers generally
require separate sources of illumination for producing visible aiming
beams and for producing visible illumination beams used to flood
the field of view of the bar code reader.
[0026] Prior art imaging-based bar code symbol readers generally
utilize during a single image capture and processing cycle, and
a single decoding methodology for decoding bar code symbols represented
in captured images.
[0027] Some prior art imaging-based bar code symbol readers require
exposure control circuitry integrated with the image detection array
for measuring the light exposure levels on selected portions thereof.
[0028] Also, many imaging-based readers also require processing
portions of captured images to detect the image intensities thereof
and determine the reflected light levels at the image detection
component of the system, and thereafter to control the LED-based
illumination sources to achieve the desired image exposure levels
at the image detector.
[0029] Prior art imaging-based bar code symbol readers employing
integrated illumination mechanisms control image brightness and
contrast by controlling the time the image sensing device is exposed
to the light reflected from the imaged objects. While this method
has been proven for the CCD-based bar code scanners, it is not suitable,
however, for the CMOS-based image sensing devices, which require
a more sophisticated shuttering mechanism, leading to increased
complexity, less reliability and, ultimately, more expensive bar
code scanning systems.
[0030] Prior art imaging-based bar code symbol readers generally
require the use of tables and bar code menus to manage which decoding
algorithms are to be used within any particular mode of system operation
to be programmed by reading bar code symbols from a bar code menu.
[0031] Finally, as a result of limitations in the mechanical, electrical,
optical, and software design of prior art imaging-based bar code
symbol readers, such prior art readers generally (i) fail to enable
users to read high-density 1D bar codes with the ease and simplicity
of laser scanning based bar code symbol readers, and also 2D symbologies,
such as PDF 417 and Data Matrix, and (ii) are incapable of use in
OCR and OCV, security applications, etc.
[0032] Thus, there is a great need in the art for an improved method
of and apparatus for reading bar code symbols using image capture
and processing techniques which avoid the shortcomings and drawbacks
of prior art methods and apparatus.
OBJECTS AND SUMMARY OF THE PRESENT INVENTION
[0033] Accordingly, a primary object of the present invention is
to provide a novel method of and apparatus for enabling the reading
of 1D and 2D bar code symbologies using image capture and processing
based systems and devices, which avoid the shortcomings and drawbacks
of prior art methods and apparatus.
[0034] Another object of the present invention is to provide a
novel hand-supportable digital Imaging-Based Bar Code Symbol Reader
capable of automatically reading 1D and 2D bar code symbologies
using the state-of-the art imaging technology, and at the speed
and with the reliability achieved by conventional laser scanning
bar code symbol readers.
[0035] Another object of the present invention is to provide a
novel hand-supportable digital Imaging-Based Bar Code Symbol Reader
that is capable of reading stacked 2D symbologies such as PDF417,
as well as Data Matrix.
[0036] Another object of the present invention is to provide a
novel hand-supportable digital Imaging-Based Bar Code Symbol Reader
that is capable of reading bar codes independent of their orientation
with respect to the reader.
[0037] Another object of the present invention is to provide a
novel hand-supportable digital Imaging-Based Bar Code Symbol Reader
that utilizes an architecture that can be used in other applications,
which may or may not be related to bar code scanning, such as OCR,
OCV, security systems, etc.
[0038] Another object of the present invention is to provide a
novel hand-supportable digital Imaging-Based Bar Code Symbol Reader
that is capable of reading high-density bar codes, as simply and
effectively as "flying-spot" type laser scanners do.
[0039] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader capable of
reading 1D and 2D bar code symbologies in a manner as convenient
to the end users as when using a conventional laser scanning bar
code symbol reader.
[0040] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader having a Multi-Mode
Bar Code Symbol Reading Subsystem, which is dynamically reconfigured
in response to real-time processing operations carried out on captured
images.
[0041] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader having an
integrated LED-Based Multi-Mode Illumination Subsystem for generating
a visible narrow-area illumination beam for aiming on a target object
and illuminating a 1D bar code symbol aligned therewith during a
narrow-area image capture mode of the system, and thereafter illuminating
randomly-oriented 1D or 2D bar code symbols on the target object
during a wide-area image capture mode of the system.
[0042] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
an integrated Multi-Mode Illumination Subsystem which generates
a visible narrow-area illumination beam for aiming onto a target
object, then illuminates a 1D bar code symbol aligned therewith,
captures an image thereof, and thereafter generates a wide-area
illumination beam for illuminating 1D or 2D bar code symbols on
the object and capturing an image thereof and processing the same
to read the bar codes represented therein.
[0043] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
automatic object presence and range detection to control the generation
of near-field and far-field wide-area illumination beams during
bar code symbol imaging operations.
[0044] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
a CMOS-type image sensing array using global exposure control techniques.
[0045] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
a CMOS-type image sensing array with a band-pass optical filter
subsystem integrated within the hand-supportable housing thereof,
to allow only narrow-band illumination from the Multi-Mode Illumination
Subsystem to expose the CMOS image sensing array.
[0046] Another object of the present invention is to provide a
hand-supportable imaging-based auto-discriminating 1D/2D bar code
symbol reader employing a Multi-Mode Image-Processing Based Bar
Code Symbol Reading Subsystem dynamically reconfigurable in response
to real-time image analysis during bar code reading operations.
[0047] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
a continuously operating Automatic Light Exposure Measurement and
Illumination Control Subsystem.
[0048] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
a Multi-Mode LED-Based Illumination Subsystem.
[0049] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader having 1D/2D
auto-discrimination capabilities.
[0050] Another object of the present invention is to provide a
method of performing auto-discrimination of 1D/2D bar code symbologies
in an Imaging-Based Bar Code Symbol Reader having both narrow-area
and wide-area image capture modes of operation.
[0051] Another object of the present invention is to provide a
method of and apparatus for processing captured images within an
Imaging-Based Bar Code Symbol Reader in order to read (i.e. recognize)
bar code symbols graphically represented therein.
[0052] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
helically-sweeping feature-extraction analysis on captured 2D images
of objects, referenced from the center thereof.
[0053] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
simple image processing operations applied in an outwardly-directed
manner on captured narrow-area images of objects bearing 1D bar
code symbols.
[0054] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
an integrated LED-based Multi-Mode Illumination Subsystem with far-field
and near-field illumination arrays responsive to control signals
generated by an IR-based Object Presence and Range Detection Subsystem
during a first mode of system operation and a System Control Subsystem
during a second mode of system operation.
[0055] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reading System employing
an integrated LED-Based Multi-Mode Illumination Subsystem driven
by an Automatic Light Exposure Measurement and Illumination Control
Subsystem responsive to control activation signals generated by
a CMOS image sensing array and an IR-based Object Presence and Range
Detection Subsystem during object illumination and image capturing
operations.
[0056] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
a CMOS image sensing array which activates LED illumination driver
circuitry to expose a target object to narrowly-tuned LED-based
illumination when all of rows of pixels in said CMOS image sensing
array are in a state of integration, thereby capturing high quality
images independent of the relative motion between said bar code
reader and the target object.
[0057] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Reading System, wherein
the exposure time of narrow-band illumination onto its CMOS image
sensing array is managed by controlling the illumination time of
its LED-based illumination arrays using control signals generated
by an Automatic Light Exposure Measurement and Illumination Control
Subsystem and a CMOS image sensing array while controlling narrow-band
illumination thereto by way of a band-pass optical filter subsystem.
[0058] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Reading System employing
a mechanism of controlling the image brightness and contrast by
controlling the time the illumination subsystem illuminates the
target object, thus, avoiding the need for a complex shuttering
mechanism for CMOS-based image sensing arrays employed therein.
[0059] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader employing
a Multi-Mode Image-Processing Bar Code Symbol Reading Subsystem
that automatically switches its modes of reading during a single
bar code symbol reading cycle, and a plurality of different bar
code symbology decoding algorithms are applied within each mode
of reading.
[0060] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader, wherein the
Multi-Mode Image-Processing Symbol Reading Subsystem has a first
multi-read (e.g. Omniscan/ROI-Specific) mode of operation, for adaptively
processing and decoding a captured high-resolution image in a high-speed
manner, applying adaptive learning techniques.
[0061] Another object of the present invention is to provide such
a hand-supportable Imaging-Based Bar Code Symbol Reader with a Multi-Mode
Image-Processing Bar Code Symbol Reading Subsystem having a first
multi-read (e.g. Omniscan/ROI-Specific) mode of operation, wherein
if during the Omniscan Mode of operation, code fragments associated
with a PDF417 bar code symbol are detected within a ROI in a captured
(narrow or wide) area image, but processing thereof is unsuccessful,
then the Multi-Mode Image-Processing Symbol Reading Subsystem will
automatically (i) enter its ROI-Specific Mode of operation described
above, and then (ii) immediately commence processing of the captured
image at the ROI specified by ROI coordinates acquired by feature
vector analysis during the Omniscan Mode of operation.
[0062] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader with a Multi-Mode
Image-Processing Bar Code Symbol Reading Subsystem having a first
multi-read (e.g. Omniscan/ROI-Specific) mode of operation, which
offers an OmniScan Mode of operation to initially and rapidly read
1D bar code symbologies, and various kinds of 2D bar code symbologies
whenever present in the captured image, and whenever a PDF417 symbology
is detected (through its code fragments), the Multi-Mode Bar Code
Symbol Reading Subsystem of the present invention can automatically
switch (on-the-fly) to its ROI-specific Mode of operation to immediately
process high-resolution image data at a specific ROI (at which there
is a high likelihood of a bar code symbol present).
[0063] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader, wherein its
Multi-Mode Image-Processing Symbol Reading Subsystem has a second
multi-read (e.g. NoFinder/ROI-Specific) mode of operation, for adaptively
processing a captured high-resolution image in a high-speed manner,
applying adaptive learning techniques.
[0064] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader, wherein the
Multi-Mode Image-Processing Symbol Reading Subsystem has a second
multi-read (e.g. NoFinder/ROI-Specific) mode of operation, and wherein
if during the NoFinder Mode of operation, code fragments associated
with a PDF417 bar code symbol are detected within the captured wide-area
image, but decode processing thereof is unsuccessful, then the Multi-Mode
Image-Processing Symbol Reading Subsystem will automatically (i)
enter its ROI-specific mode of operation described above, and then
(ii) immediately commence processing of the captured wide-area image
at a ROI specified by y coordinates corresponding to the wide-area
image processed during the NoFinder Mode of operation.
[0065] Another object of the present invention is to provide such
a hand-supportable Imaging-Based Bar Code Symbol Reader, wherein
its Multi-Mode Image-Processing Symbol Reading Subsystem has a second
multi-read (e.g. NoFinder/ROI-Specific) mode of operation, and wherein
the No-Finder Mode can rapidly read 1D bar code symbologies whenever
they are presented to the bar code symbol reader, and then whenever
a 2D (e.g. PDF417) symbology is encountered, the bar code symbol
reader can automatically switch its method of reading to the ROI-specific
Mode and use features collected from a narrow (or wide) area image
processed during the No-Finder Mode, so as to immediately process
a specific ROI in a captured wide-area image frame, at which there
is a high likelihood of a bar code symbol present, and to do so
in a highly targeted manner.
[0066] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader, wherein the
Multi-Mode Image-Processing Bar Code Reading Subsystem has a third
multi-read (e.g. NoFinder/Omniscan/ROI-Specific) mode of operation,
for adaptively processing a captured high-resolution image in a
high-speed manner, applying adaptive learning techniques.
[0067] Another object of the present invention is to provide such
a hand-supportable Imaging-Based Bar Code Symbol Reader, wherein
the Multi-Mode Image-Processing Symbol Reading Subsystem has a third
multi-read (e.g. NoFinder/Omniscan/ROI-Specific) mode of operation,
and wherein if during the NoFinder Mode of operation, code fragments
associated with a PDF417 bar code symbol are detected within the
captured narrow-area image, but processing thereof is unsuccessful,
then the Image Formation and Detection Subsystem (i) automatically
captures a wide-area image, while the multi-mode image-processing
symbol reading subsystem (ii) automatically enters its Omniscan
Mode of operation described above, and then (iii) immediately commences
processing of the captured wide-area image at a plurality of parallel
spatially-separated (e.g. by 50 pixels) virtual scan lines, beginning
at a start pixel and start angle specified by x and/or y coordinates
of code fragments detected in the narrow-area image processed during
the NoFinder Mode of operation; and, if the Omniscan Mode does not
successfully read a bar code symbol within the ROI, then the Multi-Mode
Image-Processing Symbol Reading Subsystem (i) automatically enters
its ROI-specific mode of operation described above, and then (ii)
immediately commences processing of the captured wide-area image
at a ROI specified by the x,y coordinates corresponding to code
fragments detected in the wide-area image processed during the Omniscan
Mode of operation.
[0068] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader, wherein the
Multi-Mode Image-Processing Symbol Reading Subsystem has a third
multi-read (e.g. NoFinder/Omniscan/ROI-Specific) mode of operation,
and wherein the No-Finder Mode can rapidly acquire 1D bar code symbologies
whenever they are presented to the bar code symbol reader, and then
whenever a 2D symbology is encountered, the bar code symbol reader
can automatically switch its method of reading to the OmniScan Mode,
collected features on processed image data, and if this reading
method is not successful, then the bar code reader can automatically
switch its method of reading to the ROI-Specific Mode and use features
collected during the Omniscan Mode to immediately process a specific
ROI in a captured image frame, at which there is a high likelihood
of a bar code symbol present, and to do so in a highly targeted
manner.
[0069] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader having an
integrated Multi-Mode Illumination Subsystem that supports an optical
depth of field larger than conventional imaging-based bar code symbol
readers.
[0070] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader having a Depth
of Field (DOF) of about 0 mm to 200 mm (face to 8'') for 13.5 mil
bar code symbols, wherein the resolution varies as function of object
distance, it can decode 5 mil codes somewhere, its optics can resolve
4 mil codes somewhere, and it has a 45.degree. Field of View (FOV).
[0071] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which uses a set of features
and constructing a feature vector to determine a region of interest
that may contain a bar code.
[0072] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem which uses multiple, adaptive
thresholds to determine and mark regions of interest (ROIs).
[0073] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which uses several image
processing methods to determine bar code orientation in a hierarchical
scheme.
[0074] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having A Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which uses several different
scan-data filtering techniques to generate bar-space counts.
[0075] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having A Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem which uses bar and space
stitching for correcting perspective and projection transforms,
and also decoding damaged labels.
[0076] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which uses incremental
processing of image data while an image is being progressively acquired.
[0077] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which uses low-rise histogram
analysis to determine bright spots in captured images.
[0078] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which detects all 1D symbologies
and PDF417 omnidirectionally.
[0079] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having A Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem which decodes UPC/EAN, 1205,
C128, C39, C93, CBR omnidirectionally.
[0080] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which uses low incidence
of "false-positives"
[0081] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem, which works with images
stored in memory during a snap-shot mode of operation.
[0082] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem which works with images
acquired progressively during an incremental mode of operation.
[0083] Another object of the present invention is to provide an
Imaging-Based Bar Code Symbol Reader having a Multi-Mode Image-Processing
Based Bar Code Symbol Reading Subsystem which operates on captured
high-resolution images having an image size of 32768.times.32768
pixels.
[0084] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Symbol Reader which is simple
to use, is inexpensive to manufacture, requires as few elements
as possible, has a small as possible form factor, employs no moving
elements (i.e. no dynamic focus, and no zoom), and employs all spherical
surfaces and common glasses.
[0085] Another object of the present invention is to provide a
low-cost, high-resolution Imaging-Based Bar Code Symbol Reader for
omni-directional reading of regular 1D bar codes and two-dimensional
bar codes, such as the PDF417 symbology.
[0086] Another object of the present invention is to provide such
an Imaging-Based Bar Code Symbol Reader having target applications
at point of sales in convenience stores, gas stations, quick markets,
and liquor stores, where 2D bar code reading is required for age
verification and the like.
[0087] Another object of the present invention is to provide an
improved Imaging-Based Bar Code Symbol Reading Engine for integration
into diverse types of information capture and processing systems,
such as bar code driven portable data terminals (PDT) having wireless
interfaces with their base stations, reverse-vending machines, retail
bar code driven kiosks, and the like.
[0088] Another object of the present invention is to provide a
novel method of and apparatus for enabling global exposure control
in an Imaging-Based Bar Code Symbol Reader using a CMOS image sensing
array.
[0089] Another object of the present invention is to provide a
hand-supportable Imaging-Based Bar Code Reading System that employs
a novel method of illumination, which automatically reduces noise
in detected digital images caused by specular reflection during
illumination and imaging operations.
[0090] Another object of the present invention is to provide a
novel method of and system for producing a composite DOF plot that
completely theoretically characterizes the Depth of Field (DOF)
of the image formation optics employed in an Imaging-Based Bar Code
Symbol Reader.
[0091] These and other objects of the present invention will become
more apparently understood hereinafter and in the Claims to Invention
appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS OF PRESENT INVENTION
[0092] For a more complete understanding of how to practice the
Objects of the Present Invention, the following Detailed Description
of the Illustrative Embodiments can be read in conjunction with
the accompanying Drawings, briefly described below.
[0093] FIG. 1A is an rear perspective view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0094] FIG. 1B is an front perspective view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0095] FIG. 1C is an elevated left side view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0096] FIG. 1D is an elevated right side view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0097] FIG. 1E is an elevated rear view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0098] FIG. 1F is an elevated front view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention, showing components
associated with its illumination subsystem and its image capturing
subsystem;
[0099] FIG. 1G is a bottom view of the hand-supportable Digital
Imaging-Based Bar Code Symbol Reading Device of the first illustrative
embodiment of the present invention;
[0100] FIG. 1H is a top rear view of the hand-supportable Digital
Imaging-Based Bar Code Symbol Reading Device of the first illustrative
embodiment of the present invention;
[0101] FIG. 1I is a first perspective exploded view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0102] FIG. 1J is a second perspective exploded view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0103] FIG. 1K is a third perspective exploded view of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the first
illustrative embodiment of the present invention;
[0104] FIG. 2A1 is a schematic block diagram representative of
a system design for the hand-supportable Digital Imaging-Based Bar
Code Symbol Reading Device illustrated in FIGS. 1A through 1L, wherein
the system design is shown comprising (1) a Multi-Mode Area-Type
Image Formation and Detection (i.e. Camera) Subsystem having image
formation (camera) optics for producing a field of view (FOV) upon
an object to be imaged and a CMOS or like area-type image sensing
array for detecting imaged light reflected off the object during
illumination operations in either (i) a narrow-area image capture
mode in which a few central rows of pixels on the image sensing
array are enabled, or (ii) a wide-area image capture mode in which
all rows of the image sensing array are enabled, (2) a Multi-Mode
LED-Based Illumination Subsystem for producing narrow and wide area
fields of narrow-band illumination within the FOV of the Image Formation
And Detection Subsystem during narrow and wide area modes of image
capture, respectively, so that only light transmitted from the Multi-Mode
Illumination Subsystem and reflected from the illuminated object
and transmitted through a narrow-band transmission-type optical
filter realized within the hand-supportable housing (i.e. using
a red-wavelength high-pass reflecting window filter element disposed
at the light transmission aperture thereof and a low-pass filter
before the image sensor) is detected by the image sensor and all
other components of ambient light are substantially rejected, (3)
an IR-based object presence and range detection subsystem for producing
an IR-based object detection field within the FOV of the Image Formation
and Detection Subsystem, (4) an Automatic Light Exposure Measurement
and Illumination Control Subsystem for controlling the operation
of the LED-Based Multi-Mode Illumination Subsystem, (5) an Image
Capturing and Buffering Subsystem for capturing and buffering 2-D
images detected by the Image Formation and Detection Subsystem,
(6) a Multimode Image-Processing Based Bar Code Symbol Reading Subsystem
for processing images captured and buffered by the Image Capturing
and Buffering Subsystem and reading 1D and 2D bar code symbols represented,
and (7) an Input/Output Subsystem for outputting processed image
data and the like to an external host system or other information
receiving or responding device, in which each said subsystem component
is integrated about (8) a System Control Subsystem, as shown;
[0105] FIG. 2A2 is a schematic block representation of the multi-Mode
Image-Processing Based Bar Code Symbol Reading Subsystem, realized
using the three-tier computing platform illustrated in FIG. 2B;
[0106] FIG. 2B is schematic diagram representative of a system
implementation for the hand-supportable Digital Imaging-Based Bar
Code Symbol Reading Device illustrated in FIGS. 1A through 2A2,
wherein the system implementation is shown comprising (1) an illumination
board 33 carrying components realizing electronic functions performed
by the Multi-Mode LED-Based Illumination Subsystem and the Automatic
Light Exposure Measurement And Illumination Control Subsystem, (2)
a CMOS camera board carrying a high resolution (1280.times.1024
8-bit 6 micron pixel size) CMOS image sensor array running at 25
Mhz master clock, at 7 frames/second at 1280*1024 resolution with
randomly accessible region of interest (ROI) window capabilities,
realizing electronic functions performed by the multi-mode area-type
Image Formation and Detection Subsystem, (3) a CPU board (i.e. computing
platform) including (i) an Intel Sabinal 32-Bit Microprocessor PXA210
running at 200 Mhz 1.0 core voltage with a 16 bit 100 Mhz external
bus speed, (ii) an expandable (e.g. 8+ megabyte) Intel J3 Asynchronous
16-bit Flash memory, (iii) an 16 Megabytes of 100 MHz SDRAM, (iv)
an Xilinx Spartan II FPGA FIFO 39 running at 50 Mhz clock frequency
and 60 MB/Sec data rate, configured to control the camera timings
and drive an image acquisition process, (v) a multimedia card socket,
for realizing the other subsystems of the system, (vi) a power management
module for the MCU adjustable by the system bus, and (vii) a pair
of UARTs (one for an IRDA port and one for a JTAG port), (4) an
interface board for realizing the functions performed by the I/O
subsystem, and (5) an IR-based object presence and range detection
circuit for realizing the IR-based Object Presence And Range Detection
Subsystem;
[0107] FIG. 3A is a schematic representation showing the spatial
relationships between the near and far and narrow and wide area
fields of narrow-band illumination within the FOV of the Multi-Mode
Image Formation and Detection Subsystem during narrow and wide area
image capture modes of operation;
[0108] FIG. 3B is a perspective partially cut-away view of the
hand-supportable Digital Imaging-Based Bar Code Symbol Reading Device
of the first illustrative embodiment, showing the LED-Based Multi-Mode
Illumination Subsystem transmitting visible narrow-band illumination
through its narrow-band transmission-type optical filter system
and illuminating an object with such narrow-band illumination, and
also showing the image formation optics, including the low pass
filter before the image sensing array, for collecting and focusing
light rays reflected from the illuminated object, so that an image
of the object is formed and detected using only the optical components
of light contained within the narrow-band of illumination, while
all other components of ambient light are substantially rejected
before image detection at the image sensing array;
[0109] FIG. 3C is a schematic representation showing the geometrical
layout of the optical components used within the hand-supportable
Digital Imaging-Based Bar Code Reading Device of the first illustrative
embodiment, wherein the red-wavelength reflecting high-pass lens
element is positioned at the imaging window of the device before
the image formation lens elements, while the low-pass filter is
disposed before the image sensor of between the image formation
elements, so as to image the object at the image sensing array using
only optical components within the narrow-band of illumination,
while rejecting all other components of ambient light;
[0110] FIG. 3D is a schematic representation of the image formation
optical subsystem employed within the hand-supportable Digital Imaging-Based
Bar Code Reading Device of the first illustrative embodiment, wherein
all three lenses are made as small as possible (with a maximum diameter
of 12 mm), all have spherical surfaces, all are made from common
glass, e.g. LAK2 (.about.LaK9), ZF10 (=SF8), LAF2 (.about.LaF3);
[0111] FIG. 3E is a schematic representation of the lens holding
assembly employed in the image formation optical subsystem of the
hand-supportable Digital Imaging-Based Bar Code Reading Device of
the first illustrative embodiment, showing a two-piece barrel structure
which holds the lens elements, and a base structure which holds
the image sensing array, wherein the assembly is configured so that
the barrel structure slides within the base structure so as to focus
the assembly;
[0112] FIG. 3F1 is a first schematic representation showing, from
a side view, the physical position of the LEDs used in the Multi-Mode
Illumination Subsystem, in relation to the image formation lens
assembly, the image sensing array employed therein (e.g. a Motorola
MCM20027 or National Semiconductor LM9638 CMOS 2-D image sensing
array having a 1280.times.1024 pixel resolution (1/2'' format),
6 micron pixel size, 13.5 Mhz clock rate, with randomly accessible
region of interest (ROI) window capabilities);
[0113] FIG. 3F2 is a second schematic representation showing, from
an axial view, the physical layout of the LEDs used in the Multi-Mode
Illumination Subsystem of the Digital Imaging-Based Bar Code Reading
Device, shown in relation to the image formation lens assembly,
and the image sensing array employed therein;
[0114] FIG. 3G is a flow chart describing the steps involved in
determining the Depth of Field (DOF) of the image formation optics
assembly employed in the bar code reading system of the present
invention;
[0115] FIG. 4A is a schematic representation of the Depth of Field
Chart used in the design of the image formation optics in the Digital
Imaging-Based Bar Code Reading Device, wherein image formation lens
resolution characteristics are plotted against the pixel limits
of the image sensing array;
[0116] FIG. 4B is graphical chart illustrating the performance
of the image formation optics of the Digital Imaging-Based Bar Code
Reading Device of the present invention, plotting object distance
(centimeters) against MTF values of image formation optics;
[0117] FIG. 4C is a schematic representation illustrating the Depth
of Field of the image formation optics of the Digital Imaging-Based
Bar Code Reading Device of the present invention, measured in millimeters,
and showing the narrowest bar code element dimension that can be
measured over particular regions within its Depth of Field;
[0118] FIG. 4D shows a DOF chart that plots the resolution of the
image formation optics, indicating only the optical performance
of the subsystem;
[0119] FIG. 4E graphically illustrates how to read off the DOF
for a certain mil size code, considering only the optical performance
of the image formation optics of the Image Formation and Detection
Subsystem;
[0120] FIG. 4F shows the 1.4 and 1.6 pixel sampling limits plotted
on the same axes as the optical performance curve for a fixed focal
length reader (as they are functions of object distance);
[0121] FIG. 4G graphically illustrates how to determine the composite
DOF curve of the Image Formation and Detection Subsystem, considering
optical performance and sampling limit together, for the 1.6 pixel
case;
[0122] FIG. 4H graphically illustrates how to read off the DOF
for a certain mil size code, considering optical performance and
sampling limit together, for the 1.6 pixel case;
[0123] FIG. 4I1 through 4I3, taken together, show an exemplary
computer program written in ZPL (Zemax Programming Language) and
capable of generating the composite DOF chart;
[0124] FIG. 5A1 is a schematic representation specifying the range
of narrow-area illumination, near-field wide-area illumination,
and far-field wide-area illumination produced from the LED-Based
Multi-Mode Illumination Subsystem employed in the hand-supportable
Digital Imaging-Based Bar Code Reading Device of the present invention;
[0125] FIG. 5A2 is a table specifying the geometrical properties
and characteristics of each illumination mode supported by the LED-Based
Multi-Mode Illumination Subsystem employed in the hand-supportable
Digital Imaging-Based Bar Code Reading Device of the present invention;
[0126] FIG. 5B is a schematic representation illustrating the physical
arrangement of LED light sources associated with the narrow-area
illumination array and the near-field and far-field wide-area illumination
arrays employed in the Digital Imaging-Based Bar Code Reading Device
of the present invention, wherein the LEDs in the far-field wide-area
illuminating arrays are located behind spherical lenses, the LEDs
in the narrow-area illuminating array are disposed behind cylindrical
lenses, and the LEDs in the near-field wide-area illuminating array
are unlensed in the first illustrative embodiment of the Digital
Imaging-Based Bar Code Reading Device;
[0127] FIG. 5C1 is graphical representation showing the Lambertian
emittance versus wavelength characteristics of the LEDs used to
implement the narrow-area illumination array in the Multi-Mode Illumination
Subsystem of the present invention;
[0128] FIG. 5C2 is graphical representation showing the Lambertian
emittance versus polar angle characteristics of the LEDs used to
implement the narrow-area illumination array in the Multi-Mode Illumination
Subsystem of the present invention;
[0129] FIG. 5C3 is schematic representation of the cylindrical
lenses used before the LEDs in the narrow-area (linear) illumination
arrays in the Digital Imaging-Based Bar Code Reading Device of the
present invention, wherein the first surface of the cylindrical
lens is curved vertically to create a narrow-area (i.e. linear)
illumination pattern, and the second surface of the cylindrical
lens is curved horizontally to control the height of the of the
narrow-area illumination pattern to produce a narrow-area (i.e.
linear) illumination field;
[0130] FIG. 5C4 is a schematic representation of the layout of
the pairs of LEDs and two cylindrical lenses used to implement the
narrow-area (linear) illumination array employed in the Digital
Imaging-Based Bar Code Reading Device of the present invention;
[0131] FIG. 5C5 is a set of six illumination profiles for the narrow-area
(linear) illumination fields produced by the narrow-area (linear)
illumination array employed in the Digital Imaging-Based Bar Code
Reading Device of the illustrative embodiment, taken at 30, 40,
50, 80, 120, and 220 millimeters along the field away from the imaging
window (i.e. working distance) of the Digital Imaging-Based Bar
Code Reading Device, illustrating that the spatial intensity of
the narrow-area illumination field begins to become substantially
uniform at about 80 millimeters;
[0132] FIG. 5D1 is graphical representation showing the Lambertian
emittance versus wavelength characteristics of the LEDs used to
implement the wide area illumination arrays employed in the Digital
Imaging-Based Bar Code Reading Device of the present invention;
[0133] FIG. 5D2 is graphical representation showing the Lambertian
emittance versus polar angle characteristics of the LEDs used to
implement the far-field and near-field wide-area illumination arrays
employed in the Digital Imaging-Based Bar Code Reading Device of
the present invention;
[0134] FIG. 5D3 is schematic representation of the piano-convex
lenses used before the LEDs in the far-field wide-area illumination
arrays in the illumination subsystem of the present invention,
[0135] FIG. 5D4 is a schematic representation of the layout of
LEDs and plano-convex lenses used to implement the far and narrow
wide-area illumination array employed in the Digital Imaging-Based
Bar Code Reading Device of the present invention, wherein the illumination
beam produced therefrom is aimed by positioning the lenses at angles
before the LEDs in the near-field (and far-field) wide-area illumination
arrays employed therein;
[0136] FIG. 5D5 is a set of six illumination profiles for the near-field
wide-area illumination fields produced by the near-field wide-area
illumination arrays employed in the Digital Imaging-Based Bar Code
Reading Device of the illustrative embodiment, taken at 10, 20,
30, 40, 60, and 100 millimeters along the field away from the imaging
window (i.e. working distance) of the Digital Imaging-Based Bar
Code Reading Device, illustrating that the spatial intensity of
the near-field wide-area illumination field begins to become substantially
uniform at about 40 millimeters;
[0137] FIG. 5D6 is a set of three illumination profiles for the
far-field wide-area illumination fields produced by the far-field
wide-area illumination arrays employed in the Digital Imaging-Based
Bar Code Reading Device of the illustrative embodiment, taken at
100, 150 and 220 millimeters along the field away from the imaging
window (i.e. working distance) of the Digital Imaging-Based Bar
Code Reading Device, illustrating that the spatial intensity of
the far-field wide-area illumination field begins to become substantially
uniform at about 100 millimeters;
[0138] FIG. 5D7 is a table illustrating a preferred method of calculating
the pixel intensity value for the center of the far-field wide-area
illumination field produced from the Multi-Mode Illumination Subsystem
employed in the Digital Imaging-Based Bar Code Reading Device of
the present invention, showing a significant signal strength (greater
than 80 DN);
[0139] FIG. 6A1 is a schematic representation showing the red-wavelength
reflecting (high-pass) imaging window integrated within the hand-supportable
housing of the Digital Imaging-Based Bar Code Reading Device, and
the low-pass optical filter disposed before its CMOS image sensing
array therewithin, cooperate to form a narrow-band optical filter
subsystem for transmitting substantially only the very narrow band
of wavelengths (e.g. 620-700 nanometers) of visible illumination
produced from the Multi-Mode Illumination Subsystem employed in
the Digital Imaging-Based Bar Code Reading Device, and rejecting
all other optical wavelengths outside this narrow optical band however
generated (i.e. ambient light sources);
[0140] FIG. 6A2 is schematic representation of transmission characteristics
(energy versus wavelength) associated with the low-pass optical
filter element disposed after the red-wavelength reflecting high-pass
imaging window within the hand-supportable housing of the Digital
Imaging-Based Bar Code Reading Device, but before its CMOS image
sensing array, showing that optical wavelengths below 620 nanometers
are transmitted and wavelengths above 620 nm are substantially blocked
(e.g. absorbed or reflected);
[0141] FIG. 6A3 is schematic representation of transmission characteristics
(energy versus wavelength) associated with the red-wavelength reflecting
high-pass imaging window integrated within the hand-supportable
housing of the Digital Imaging-Based Bar Code Reading Device of
the present invention, showing that optical wavelengths above 700
nanometers are transmitted and wavelengths below 700 nm are substantially
blocked (e.g. absorbed or reflected);
[0142] FIG. 6A4 is a schematic representation of the transmission
characteristics of the narrow-based spectral filter subsystem integrated
within the hand-supportable Imaging-Based Bar Code Symbol Reading
Device of the present invention, plotted against the spectral characteristics
of the LED-emissions produced from the Multi-Mode Illumination Subsystem
of the illustrative embodiment of the present invention;
[0143] FIG. 7A is a schematic representation showing the geometrical
layout of the spherical/parabolic light reflecting/collecting mirror
and photodiode associated with the Automatic Light Exposure Measurement
and Illumination Control Subsystem, and arranged within the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the illustrative
embodiment, wherein incident illumination is collected from a selected
portion of the center of the FOV of the system using a spherical
light collecting mirror, and then focused upon a photodiode for
detection of the intensity of reflected illumination and subsequent
processing by the Automatic Light Exposure Measurement and Illumination
Control Subsystem, so as to then control the illumination produced
by the LED-based Multi-Mode Illumination Subsystem employed in the
Digital Imaging-Based Bar Code Reading Device of the present invention;
[0144] FIG. 7B is a schematic diagram of the Automatic Light Exposure
Measurement and Illumination Control Subsystem employed in the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the present
invention, wherein illumination is collected from the center of
the FOV of the system and automatically detected so as to generate
a control signal for driving, at the proper intensity, the narrow-area
illumination array as well as the far-field and narrow-field wide-area
illumination arrays of the Multi-Mode Illumination Subsystem, so
that the CMOS image sensing array produces digital images of illuminated
objects of sufficient brightness;
[0145] FIGS. 7C1 and 7C2 set forth a schematic diagram of a hybrid
analog/digital circuit designed to implement the Automatic Light
Exposure Measurement and Illumination Control Subsystem of FIG.
7B employed in the hand-supportable Digital Imaging-Based Bar Code
Symbol Reading Device of the present invention;
[0146] FIG. 7D is a schematic diagram showing that, in accordance
with the principles of the present invention, the CMOS image sensing
array employed in the Digital Imaging-Based Bar Code Reading Device
of the illustrative embodiment, once activated by the System Control
Subsystem (or directly by the trigger switch), and when all rows
in the image sensing array are in a state of integration operation,
automatically activates the Automatic Light Exposure Measurement
and Illumination Control Subsystem which, in response thereto, automatically
activates the LED illumination driver circuitry to automatically
drive the appropriate LED illumination arrays associated with the
Multi-Mode Illumination Subsystem in a precise manner and globally
expose the entire CMOS image detection array with narrowly tuned
LED-based illumination when all of its rows of pixels are in a state
of integration, and thus have a common integration time, thereby
capturing high quality images independent of the relative motion
between the bar code reader and the object;
[0147] FIGS. 7E1 and 7E2, taken together, set forth a flow chart
describing the steps involved in carrying out the global exposure
control method of the present invention, within the Digital Imaging-Based
Bar Code Reading Device of the illustrative embodiment;
[0148] FIG. 8 is a schematic block diagram of the IR-based automatic
Object Presence and Range Detection Subsystem employed in the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the present
invention, wherein a first range indication control signal is generated
upon detection of an object within the near-field region of the
Multi-Mode Illumination Subsystem, and wherein a second range indication
control signal is generated upon detection of an object within the
far-field region of the Multi-Mode Illumination Subsystem;
[0149] FIG. 9 is a schematic representation of the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the present
invention, showing that its CMOS image sensing array is operably
connected to its microprocessor through a FIFO (realized by way
of a FPGA) and a system bus, and that its SDRAM is also operably
connected to the microprocessor by way of the system bus, enabling
the mapping of pixel data captured by the imaging array into the
SDRAM under the control of the direct memory access (DMA) module
within the microprocessor;
[0150] FIG. 10 is a schematic representation showing how the bytes
of pixel data captured by the CMOS imaging array within the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the present
invention, are mapped into the addressable memory storage locations
of its SDRAM during each image capture cycle carried out within
the device;
[0151] FIG. 11 is a schematic representation showing the software
modules associated with the three-tier software architecture of
the hand-supportable Digital Imaging-Based Bar Code Symbol Reading
Device of the present invention, namely: the Main Task module, the
CodeGate Task module, the Metroset Task module, the Application
Events Manager module, the User Commands Table module, and the Command
Handler module residing with the Application layer of the software
architecture; the Tasks Manager module, the Events Dispatcher module,
the Input/Output Manager module, the User Commands Manager module,
the Timer Subsystem module, the Input/Output Subsystem module and
the Memory Control Subsystem module residing with the System Core
(SCORE) layer of the software architecture; and the Linux Kernal
module, the Linux File System module, and Device Drivers modules
residing within the Linux Operating System (OS) layer of the software
architecture;
[0152] FIG. 12A is a schematic representation of the Events Dispatcher
software module which provides a means of signaling and delivering
events to the Application Events Manager, including the starting
of a new task, stopping a currently running task, doing something,
or doing nothing and ignoring the event;
[0153] FIG. 12B is a Table listing examples of System-Defined Events
which can occur and be dispatched within the hand-supportable Digital
Imaging-Based Bar Code Symbol Reading Device of the present invention,
namely: SCORE_EVENT_POWER_UP which signals the completion of system
start-up and involves no parameters;_SCORE_EVENT_TIMEOUT which signals
the timeout of the logical timer, and involves the parameter "pointer
to timer id"; SCORE_EVENT_UNEXPECTED_INPUT which signals that
the unexpected input data is available and involves the parameter
"pointer to connection id"; SCORE_EVENT_TRIG_ON which
signals that the user pulled the trigger switch and involves no
parameters; SCORE_EVENT_TRIG_OFF which signals that the user released
the trigger switch and involves no parameters; SCORE_EVENT_OBJECT_DETECT_ON
which signals that the object is positioned under the bar code reader
and involves no parameters; SCORE_EVENT_OBJECT_DETECT_OFF which
signals that the object is removed from the field of view of the
bar code reader and involves no parameters; SCORE_EVENT_EXIT_TASK
which signals the end of the task execution and involves the pointer
UTID; and SCORE_EVENT_ABORT_TASK which signals the aborting of a
task during execution;
[0154] FIG. 12C is a schematic representation of the Tasks Manager
software module which provides a means for executing and stopping
application specific tasks (i.e. threads);
[0155] FIG. 12D is a schematic representation of the Input/Output
Manager software module (i.e Input/Output Subsystem), which runs
in the background and monitors activities of external devices and
user connections, and signals appropriate events to the Application
Layer, which such activities are detected;
[0156] FIGS. 12E1 and 12E2 set forth a schematic representation
of the Input/Output Subsystem software module which provides a means
for creating and deleting input/output connections, and communicating
with external systems and devices;
[0157] FIGS. 12F1 and 12F2 set forth a schematic representation
of the Timer Subsystem which provides a means for creating, deleting,
and utilizing logical timers;
[0158] FIGS. 12G1 and 12G2 set forth a schematic representation
of the Memory Control Subsystem which provides an interface for
managing the thread-level dynamic memory with the device, fully
compatible with standard dynamic memory management functions, as
well as a means for buffering collected data;
[0159] FIG. 12H is a schematic representation of the User Commands
Manager which provides a standard way of entering user commands,
and executing application modules responsible for handling the same;
[0160] FIG. 12I is a schematic representation of the Device Driver
software modules, which includes trigger switch drivers for establishing
a software connection with the hardware-based manually-actuated
trigger switch employed on the Digital Imaging-Based Bar Code Reading
Device, an image acquisition driver for implementing image acquisition
functionality aboard the Digital Imaging-Based Bar Code Reading
Device, and an IR driver for implementing object detection functionality
aboard the Imaging-Based Bar Code Symbol Reading Device;
[0161] FIG. 13A is an exemplary flow chart representation showing
how when the user points the bar code reader towards a bar code
symbol, the IR device drivers detect that object within the field,
and then wakes up the Input/Output Manager software module at the
System Core Layer;
[0162] FIG. 13B is an exemplary flow chart representation showing
how upon detecting an object, the Input/Output Manager posts the
SCORE_OBJECT_DETECT_ON event to the Events Dispatcher software module;
[0163] FIG. 13C is an exemplary flow chart representation showing
how, in response to detecting an object, the Events Dispatcher software
module passes the SCORE_OBJECT_DETECT_ON event to the Application
Layer;
[0164] FIG. 13D is an exemplary flow chart representation showing
how upon receiving the SCORE_OBJECT_DETECT_ON event at the Application
Layer, the Application Events Manager executes an event handling
routine which activates the narrow-area illumination array associated
with the Multi-Mode Illumination Subsystem, and executes the CodeGate
Task described in FIG. 13E;
[0165] FIG. 13E is an exemplary flow chart representation showing
how what operations are carried out when the CodeGate Task is executed
within the Application Layer;
[0166] FIG. 13F is an exemplary flow chart representation showing
how, when the user pulls the trigger switch on the bar code reader
while the Code Task is executing, the trigger device driver wakes
up the Input/Output Manager at the System Core Layer;
[0167] FIG. 13G is an exemplary flow chart representation showing
how, in response to waking up, the Input/Output Manager posts the
SCORE_TRIGGER_ON event to the Events Dispatcher;
[0168] FIG. 13H is an exemplary flow chart representation showing
how the Events Dispatcher passes on the SCORE_TRIGGER_ON event to
the Application Events Manager at the Application Layer;
[0169] FIG. 13I is an exemplary flow chart representation showing
how the Application Events Manager responds to the SCORE_TRIGGER_ON
event by invoking a handling routine within the Task Manager at
the System Core Layer which deactivates the narrow-area illumination
array associated with the Multi-Mode Illumination Subsystem, cancels
the CodeGate Task, and executes the Main Task;
[0170] FIG. 13J is an exemplary flow chart representation showing
what operations are carried out when the Main Task is executed within
the Application Layer;
[0171] FIG. 13K is an exemplary flow chart representation showing
what operations are carried out when the Data Output Procedure,
called in the Main Task, is executed within the Input/Output Subsystem
software module in the Application Layer;
[0172] FIG. 13L is an exemplary flow chart representation showing
decoded symbol character data being sent from the Input/Output Subsystem
to the Device Drivers within the Linux OS Layer of the system;
[0173] FIG. 13M is a flow chart describing a novel method of generating
wide-area illumination, for use during the Main Task routine so
as to illuminate objects with a wide-area illumination field in
a manner, which substantially reduces specular-type reflection at
the CMOS image sensing array in the Digital Imaging-Based Bar Code
Reading Device of the present invention;
[0174] FIG. 14 is a table listing various bar code symbologies
supported by the Multi-Mode Bar Code Symbol Reading Subsystem module
employed within the hand-supportable Digital Imaging-Based Bar Code
Symbol Reading Device of the present invention;
[0175] FIG. 15 is a table listing the four primary modes in which
the Multi-Mode Bar Code Symbol Reading Subsystem module can be programmed
to operate, namely: the Automatic Mode wherein the Multi-Mode Bar
Code Symbol Reading Subsystem is configured to automatically process
a captured frame of digital image data so as to search for one or
more bar codes represented therein in an incremental manner, and
to continue searching until the entire image is processed; the Manual
Mode wherein the Multi-Mode Bar Code Symbol Reading Subsystem is
configured to automatically process a captured frame of digital
image data, starting from the center or sweep spot of the image
at which the user would have aimed the bar code reader, so as to
search for (i.e. find) one or more bar code symbols represented
therein, by searching in a helical manner through frames or blocks
of extracted image feature data and marking the same and processing
the corresponding raw digital image data until a bar code symbol
is recognized/read within the captured frame of image data; the
ROI-Specific Mode wherein the Multi-Mode Bar Code Symbol Reading
Subsystem is configured to automatically process a specified "region
of interest" (ROI) in a captured frame of digital image data
so as to search for one or more bar codes represented therein, in
response to coordinate data specifying the location of the bar code
within the field of view of the multi-mode image formation and detection
system; the NoFinder Mode wherein the Multi-Mode Bar Code Symbol
Reading Subsystem is configured to automatically process a captured
narrow-area (linear) frame of digital image data, without feature
extraction and marking operations used in the Automatic and Manual
Modes, so as read one or more bar code symbols represented therein;
and the Omniscan Mode, wherein the Multi-Mode Bar Code Symbol Reading
Subsystem is configured to automatically process a captured frame
of digital image data along any one or more predetermined virtual
scan line orientations, without feature extraction and marking operations
used in the Automatic and Manual Modes, so as to read one or more
bar code symbols represented therein;
[0176] FIG. 16 is a exemplary flow chart representation showing
the steps involved in setting up and cleaning up the software sub-Application
entitled "Multi-Mode Image-Processing Based Bar Code Symbol
Reading Subsystem", once called from either (i) the CodeGate
Task software module at the Block entitled READ BAR CODE(S) IN CAPTURED
NARROW-AREA IMAGE indicated in FIG. 13E, or (ii) the Main Task software
module at the Block entitled "READ BAR CODE(S) IN CAPTURED
WIDE-AREA IMAGE" indicated in FIG. 13J;
[0177] FIG. 17A is a summary of the steps involved in the decode
process carrying out by the Multi-Mode Bar Code Symbol Reading Subsystem
of the present invention during its Automatic Mode of operation,
wherein (1) the first stage of processing involves searching for
(i.e. finding) regions of interest (ROIs) by processing a low resolution
image of a captured frame of high-resolution image data, partitioning
the low-resolution image into N.times.N blocks, and creating a feature
vector for each block using spatial-derivative based image processing
techniques, (2) the second stage of processing involves marking
ROIs by examining the feature vectors for regions of high-modulation,
calculating bar code orientation and marking the four corners of
a bar code as a ROI, and (3) the third stage of processing involves
reading any bar code symbols represented within the ROI by traversing
the bar code and updating the feature vectors, examining the zero-crossings
of filtered images, creating bar and space patterns, and decoding
the bar and space patterns using conventional decoding algorithms;
[0178] FIG. 17B is an exemplary flow chart representation of the
steps involved in the image-processing method carried out by the
Multi-Mode Bar Code Symbol Reading Subsystem during its Automatic
Mode of operation;
[0179] FIG. 18A is a graphical representation illustrating the
generation of a low-resolution image of a package label from an
original high-resolution image thereof during the first finding
stage of processing within the Multi-Mode Bar Code Symbol Reading
Subsystem configured in its Automatic Mode of operation;
[0180] FIG. 18B is a graphical representation illustrating the
partitioning of the low-resolution image of the package label, the
calculation of feature vectors using the same, and the analysis
of these feature vectors for parallel lines, during the first finding
stage of processing within the Multi-Mode Bar Code Symbol Reading
Subsystem during its Automatic Mode of operation;
[0181] FIG. 18C is a graphical representation showing that the
calculation of feature vectors within each block of low-resolution
image data, during the second marking stage of processing within
the Multi-Mode Bar Code Symbol Reading Subsystem, can involve the
use of gradient vectors, edge density measures, the number of parallel
edge vectors, centroids of edgels, intensity variance, and the histogram
of intensities captured from the low-resolution image;
[0182] FIG. 18D is a graphical representation of the examination
of feature vectors looking for high edge density, large number of
parallel edge vectors and large intensity variance, during the second
marking stage of processing within the Multi-Mode Bar Code Symbol
Reading Subsystem during its Automatic Mode of operation;
[0183] FIGS. 18E and 18F set forth graphical representations of
calculating bar code orientation during the second marking stage
of processing within the Multi-Mode Bar Code Symbol Reading Subsystem
operating in its Automatic Mode, wherein each feature vector block,
the bar code is traversed (i.e. sliced) at different angles, the
slices are matched with each other based on "least mean square
error", and the correct orientation is determined to be that
angle which matches the mean square error sense through every slice
of the bar code symbol represented within the captured image;
[0184] FIG. 18F is a graphical representation of calculating bar
code orientation, during the second marking stage of processing
within the Multi-Mode Bar Code Symbol Reading Subsystem operating
in its Automatic Mode;
[0185] FIG. 18G is a graphical representation of the marking of
the four corners of the detected bar code symbol during the second
marking stage of processing within the Multi-Mode Bar Code Symbol
Reading Subsystem operating in its Automatic Mode, wherein such
marking operations are performed on the full high-resolution image
of the parcel, the bar code is traversed in either direction starting
from the center of the block, the extent of modulation is detected
using the intensity variance, and the x,y coordinates (pixels) of
the four corners of the bar code are detected starting from 1 and
2 and moving perpendicular to the bar code orientation, and define
the ROI by the detected four corners of the bar code symbol within
the high-resolution image;
[0186] FIG. 18H is a graphical representation of updating the feature
vectors during the third stage of processing within the Multi-Mode
Bar Code Symbol Reading Subsystem operating in its Automatic Mode,
wherein the histogram component of the feature vector Fv is updated
while traversing the bar code symbol, the estimate of the black-to-white
transition is calculated, and an estimate of narrow and wide elements
of the bar code symbol are calculated;
[0187] FIG. 18I is a graphical representation of the search for
zero crossings during the third stage of processing within the Multi-Mode
Bar Code Symbol Reading Subsystem operating in its Automatic Mode,
wherein the high-resolution bar code image is median filtered in
a direction perpendicular to bar code orientation, the second derivative
zero crossings define edge crossings, the zero-crossing data is
used only for detecting edge transitions, and the black/white transition
estimates are used to put upper and lower bounds on the grey levels
of the bars and spaces of the bar code symbol represented within
the captured image;
[0188] FIG. 18J is a graphical representation of creating bar and
space pattern during the third stage of processing within the Multi-Mode
Bar Code Symbol Reading Subsystem operating in its Automatic Mode,
wherein the edge transition is modeled as a ramp function, the edge
transition is assumed to be 1 pixel wide, the edge transition location
is determined at the subpixel level, and the bar and space counts
are gathered using edge transition data;
[0189] FIG. 18K is a graphical representation of the decode bar
and space pattern during the third stage of processing within the
Multi-Mode Bar Code Symbol Reading Subsystem operating in its Automatic
Mode, wherein the bar and space data is framed with borders, and
the bar and space data is decoded using existing laser scanning
bar code decoding algorithms;
[0190] FIG. 19A is a summary of the steps involved in the image-processing
method carried out by the Multi-Mode Bar Code Symbol Reading Subsystem
during its Manual Mode of operation, wherein (1) the first stage
of processing involves searching for (i.e. finding) regions of interest
(ROIs) by processing a low resolution image of a captured frame
of high-resolution image data, partitioning the low-resolution image
into N.times.N blocks, and creating a feature vector for the middle
block using spatial-derivative based image processing techniques,
(2) the second stage of processing involves marking ROIs by examining
the feature vectors for regions of high-modulation and returning
to the first stage to create feature vectors for other blocks surrounding
the middle block (in a helical manner), calculating bar code orientation
and marking the four corners of a bar code as a ROI, and (3) the
third stage of processing involves reading any bar code symbols
represented within the ROI by traversing the bar code and updating
the feature vectors, examining the zero-crossings of filtered images,
creating bar and space patterns, and decoding the bar and space
patterns using conventional decoding algorithms;
[0191] FIG. 19B is an exemplary flow chart representation of the
steps involved in the image-processing method carrying out by the
Multi-Mode Bar Code Symbol Reading Subsystem during its Manual Mode
of operation;
[0192] FIG. 20A is a summary of the steps involved in the image
processing method carried out by the Multi-Mode Bar Code Symbol
Reading Subsystem during its NoFinder Mode of operation, wherein
the Decoder Module does not employ bar code element finding or marking
techniques (i.e. Finder Module and Marker Module) and directly processes
a narrow-area portion of a captured high-resolution image, starting
from the middle thereof, examines the zero-crossings of the filtered
image, creates bar and space patterns therefrom, and then decodes
the bar and space patterns using conventional decoding algorithms;
[0193] FIG. 20B is an exemplary flow chart representation of the
steps involved in the image-processing method carried out by the
Multi-Mode Bar Code Symbol Reading Subsystem during its NoFinder
Mode of operation;
[0194] FIG. 21A is a summary of the steps involved in the image-processing
method carried out by the Multi-Mode Bar Code Symbol Reading Subsystem
during its OmniScan Mode of operation, wherein the Decoder Module
does not employ bar code element finding or marking techniques (i.e.
Finder Module and Marker Module), assumes the imaged bar code symbol
resides at the center of the captured wide-area high-resolution
image with about a 1:1 aspect ratio, and directly processes the
high-resolution image along a set of parallel spaced-apart (e.g.
50 pixels) virtual scan lines, examines the zero-crossings along
the virtual scan lines, creates bar and space patterns therefrom,
and then decodes the bar and space patterns, with the option of
reprocessing the high-resolution image along a different set of
parallel spaced-apart virtual scan lines oriented at a different
angle from the previously processed set of virtual scan lines (e.g.
0, 30, 60, 90, 120 or 150 degrees);
[0195] FIG. 21B is an exemplary flow chart representation of the
steps involved in the image-processing method carried out by the
Multi-Mode Bar Code Symbol Reading Subsystem during its OmniScan
Mode of operation;
[0196] FIG. 22A is a summary of the steps involved in the image-processing
based bar code reading method carried out by the Multi-Mode Bar
Code Symbol Reading Subsystem of the present invention during its
"ROI-Specific" Mode of operation, designed for use in
combination with the Omniscan Mode of operation, wherein (1) the
first stage of processing involves receiving region of interest
(ROI) coordinates (x1, x2) obtained during the Omniscan Mode of
operation (after the occurrence of a failure to decode), re-partitioning
the captured low-resolution image (from the Omniscan Mode) into
N.times.N blocks, and creating a feature vector for the ROI-specified
block(s) using spatial-derivative based image processing techniques,
(2) the second stage of processing involves marking additional ROIs
by examining the feature vectors for regions of high-modulation
and returning to the first stage to create feature vectors for other
blocks surrounding the middle block (in a helical manner), calculating
bar code orientation and marking the four corners of a bar code
as a ROI, and (3) the third stage of processing involves reading
any bar code symbols represented within the ROI by traversing the
bar code symbol and updating the feature vectors, examining the
zero-crossings of filtered images, creating bar and space patterns,
and decoding the bar and space patterns using conventional decoding
algorithms;
[0197] FIG. 22B is an exemplary flow chart representation of the
steps involved in the image-processing method carried out by the
Multi-Mode Bar Code Symbol Reading Subsystem of the present invention
during its ROI-specific Mode of operation;
[0198] FIG. 23 is a specification of Multi-Mode Bar Code Symbol
Reading Subsystem operated during its first multi-read (Omniscan/ROI-Specific)
mode of operation;
[0199] FIG. 24 is a specification of Multi-Mode Bar Code Symbol
Reading Subsystem operated during its second multi-read (No-Finder/ROI-Specific)
mode of operation;
[0200] FIG. 25 is a specification of Multi-Mode Bar Code Symbol
Reading Subsystem operated during its third multi-read (No-Finder/Omniscan/ROI-Specific)
mode of operation; and
[0201] FIGS. 26A and 26B, taken together, provide a table listing
the primary Programmable Modes of Bar Code Reading Operation within
the hand-supportable Digital Imaging-Based Bar Code Symbol Reading
Device of the present invention, namely: Programmed Mode of System
Operation No. 1--Manually-Triggered Single-Attempt 1D Single-Read
Mode Employing the No-Finder Mode of the Multi-Mode Bar Code Reading
Subsystem; Programmed Mode Of System Operation No. 2--Manually-Triggered
Multiple-Attempt 1D Single-Read Mode Employing the No-Finder Mode
of the Multi-Mode Bar Code Reading Subsystem; Programmed Mode Of
System Operation No. 3--Manually-Triggered Single-Attempt 1D/2D
Single-Read Mode Employing the No-Finder Mode And The Automatic
Or Manual Modes of the Multi-Mode Bar Code Reading Subsystem; Programmed
Mode of System Operation No. 4--Manually-Triggered Multiple-Attempt
1D/2D Single-Read Mode Employing the No-Finder Mode And The Automatic
Or Manual Modes of the Multi-Mode Bar Code Reading Subsystem; Programmed
Mode of System Operation No. 5--Manually-Triggered Multiple-Attempt
1D/2D Multiple-Read Mode Employing the No-Finder Mode And The Automatic
Or Manual Modes of the Multi-Mode Bar Code Reading Subsystem; Programmed
Mode of System Operation No. 6--Automatically-Triggered Single-Attempt
1D Single-Read Mode Employing The No-Finder Mode Of the Multi-Mode
Bar Code Reading Subsystem Programmed Mode of System Operation No.
7--Automatically-Triggered Multi-Attempt 1D Single-Read Mode Employing
The No-Finder Mode Of the Multi-Mode Bar Code Reading Subsystem;
Programmed Mode of System Operation No. 8--Automatically-Triggered
Multi-Attempt 1D/2D Single-Read Mode Employing The No-Finder Mode
and Manual and/or Automatic Modes Of the Multi-Mode Bar Code Reading
Subsystem; Programmed Mode of System Operation No. 9--Automatically-Triggered
Multi-Attempt 1D/2D Multiple-Read Mode Employing The No-Finder Mode
and Manual and/or Automatic Modes Of the Multi-Mode Bar Code Reading
Subsystem; Programmable Mode of System Operation No. 10--Automatically-Triggered
Multiple-Attempt 1D/2D Single-Read Mode Employing The Manual, Automatic
or Omniscan Modes Of the Multi-Mode Bar Code Reading Subsystem;
Programmed Mode of System Operation No. 11--Semi-Automatic-Triggered
Single-Attempt 1D/2D Single-Read Mode Employing The No-Finder Mode
And The Automatic Or Manual Modes Of the Multi-Mode Bar Code Reading
Subsystem; Programmable Mode of System Operation No. 12--Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Single-Read Mode Employing The No-Finder
Mode And The Automatic Or Manual Modes Of the Multi-Mode Bar Code
Reading Subsystem; Programmable Mode of Operation No. 13--Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing The No-Finder
Mode And The Automatic Or Manual Modes Of the Multi-Mode Bar Code
Reading Subsystem; Programmable Mode of Operation No. 14--Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing The No-Finder
Mode And The Omniscan Modes Of the Multi-Mode Bar Code Reading Subsystem;
Programmable Mode of Operation No. 15--Continuously-Automatically-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing The Automatic,
Manual Or Omniscan Modes Of the Multi-Mode Bar Code Reading Subsystem;
Programmable Mode of System Operation No. 16--Diagnostic Mode Of
Imaging-Based Bar Code Reader Operation; and Programmable Mode of
System Operation No. 17--Live Video Mode Of Imaging-Based Bar Code
Reader Operation;
[0202] FIG. 27A is a schematic representation specifying the four
modes of illumination produced from the Multi-Mode Illumination
Subsystem employed in the second illustrative embodiment of the
Digital Imaging-Based Bar Code Symbol Reader of the present invention,
which supports both near and far fields of narrow-area illumination
generated during the narrow-area image capture mode of its Multi-Mode
Image Formation and Detection Subsystem;
[0203] FIG. 27B is a schematic representation specifying how the
cylindrical beam shaping optics employed within near-field and far-field
narrow-area illumination arrays can be easily tailored to generate
near and far narrow-area illumination fields having geometrical
characteristics that enables (i) simple reading of extended-length
bar code symbols within the far-field region of the FOV of the system,
and also (ii) simple reading of bar code menus with a great degree
of control within the near-field region of the FOV, preferably during
a "Semi-Automatic-Triggered" programmed mode of system
operation;
[0204] FIG. 28 is a schematic representation illustrating the physical
arrangement of LEDs and light focusing lenses associated with the
near and far field narrow-area and wide-area illumination arrays
employed in the Digital Imaging-Based Bar Code Symbol Reading Device
according to the second illustrative embodiment of the present invention;
[0205] FIG. 29A is a first perspective view of a second illustrative
embodiment of the portable POS Digital Imaging-Based Bar Code Symbol
Reading Device of the present invention, shown having a hand-supportable
housing of a different form factor than that of the first illustrative
embodiment, and configured for use in its hands-free/presentation
mode of operation, supporting primarily wide-area image capture;
[0206] FIG. 29B is a second perspective view of the second illustrative
embodiment of the portable POS Digital Imaging-Based Bar Code Reading
Device of the present invention, shown configured and operated in
its hands-free/presentation mode of operation, supporting primarily
wide-area image capture;
[0207] FIG. 29C is a third perspective view of the second illustrative
embodiment of the portable Digital Imaging-Based Bar Code Reading
Device of the present invention, showing configured and operated
in a hands-on type mode, supporting both narrow and wide area modes
of image capture;
[0208] FIG. 30 is a perspective view of a third illustrative embodiment
of the Digital Imaging-Based Bar Code Symbol Reading Device of the
present invention, realized in the form of a Multi-Mode Image Capture
And Processing Engine that can be readily integrated into various
kinds of information collection and processing systems, including
wireless portable data terminals (PDTs), reverse-vending machines,
retail product information kiosks and the like;
[0209] FIG. 31 is a schematic representation of a Wireless Bar
Code-Driven Portable Data Terminal embodying the Imaging-Based Bar
Code Symbol Reading Engine of the present invention, shown configured
and operated in a hands-on mode;
[0210] FIG. 32 is a perspective view of the Wireless Bar Code Driven
Portable Data Terminal of FIG. 31 shown configured and operated
in a hands-on mode, wherein the Imaging-Based Bar Code Symbol Reading
Engine embodied therein is used to read a bar code symbol on a package
and the symbol character data representative of the read bar code
is being automatically transmitted to its cradle-providing base
station by way of an RF-enabled 2-way data communication link;
[0211] FIG. 33 is a side view of the Wireless Bar Code Driven Portable
Data Terminal of FIGS. 31 and 32 shown configured and operated in
a hands-free mode, wherein the Imaging-Based Bar Code Symbol Reading
Engine is configured in a wide-area image capture mode of operation,
suitable for presentation-type bar code reading at point of sale
(POS) environments; and
[0212] FIG. 34 is a block schematic diagram showing the various
subsystem blocks associated with a design model for the Wireless
Hand-Supportable Bar Code Driven Portable Data Terminal System of
FIGS. 31, 32 and 33, shown interfaced with possible host systems
and/or networks.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENT
INVENTION
[0213] Referring to the figures in the accompanying Drawings, the
various illustrative embodiments of the hand-supportable imaging-based
bar code symbol reading system of the present invention will be
described in great detail, wherein like elements will be indicated
using like reference numerals.
Hand-Supportable Digital Imaging-Based Bar Code Reading Device
of the First Illustrative Embodiment of the Present Invention
[0214] Referring to FIGS. 1A through 1K, the hand-supportable Digital
Imaging-Based Bar Code Symbol Reading Device of the first illustrative
embodiment of the present invention 1 is shown in detail comprising
a hand-supportable housing 2 having a handle portion 2A and a head
portion 2B that is provided with a light transmission window 3 with
a high-pass (red-wavelength reflecting) optical filter element 4A
having light transmission characteristics set forth in FIG. 6A2,
in the illustrative embodiment. As will be described in greater
detail hereinafter, high-pass optical filter element 4A cooperates
within an interiorly mounted low-pass optical filter element 4B
characterized in FIG. 6A1, which cooperates with the high-pass optical
filter element 4A. These high and low pass filter elements 4A and
4B cooperate to provide a narrow-band optical filter system 4 that
integrates with the head portion of the housing and permits only
a narrow band of illumination (e.g. 633 nanometers) to exit and
enter the housing during imaging operations.
[0215] As best shown in FIGS. 1I, 1J, and 1K, the hand-supportable
housing 2 of the illustrative embodiment comprises: left and right
housing handle halves 2A1 and 2A2; a foot-like structure 2A3 which
is mounted between the handle halves 2A1 and 2A2; a trigger switch
structure 2C which snap fits within and pivots within a pair of
spaced apart apertures 2D1 and 2D2 provided in the housing halves;
a light transmission window panel 5 through which light transmission
window 3 is formed and supported within a recess formed by handle
halves 2A1 and 2A2 when they are brought together, and which supports
all LED illumination arrays provided by the system; an optical bench
6 for supporting electro-optical components and operably connected
an orthogonally-mounted PC board 7 which is mounted within the handle
housing halves; a top housing portion 2B1 for connection with the
housing handle halves 2A1 and 2A2 and enclosing the head portion
of the housing; light pipe lens element 8 for mounting over an array
of light emitting diodes (LEDs) 9 and light pipe structures 10 mounted
within the rear end of the head portion of the hand-supportable
housing; and a front bumper structure 2E for holding together the
top housing portion 2B1 and left and right handle halves 2A1 and
2A2 with the light transmission window panel 5 sandwiched therebetween,
while providing a level of shock protection thereto.
[0216] In other embodiments of the present invention shown in FIGS.
27 through 33 the form factor of the hand-supportable housing might
be different. In yet other applications, the housing need not even
be hand-supportable, but rather might be designed for stationary
support on a desktop or countertop surface, or for use in a commercial
or industrial application.
Schematic Block Functional Diagram as System Design Model for the
Hand-Supportable Digital Image-Based Bar Code Reading Device of
the Present Invention
[0217] As shown in the system design model of FIG. 2A1, the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device 1 of the illustrative
embodiment comprises: an IR-based Object Presence and Range Detection
Subsystem 12; a Multi-Mode Area-type Image Formation and Detection
(i.e. camera) Subsystem 13 having narrow-area mode of image capture,
near-field wide-area mode of image capture, and a far-field wide-area
mode of image capture; a Multi-Mode LED-Based Illumination Subsystem
14 having narrow-area mode of illumination, near-field wide-area
mode of illumination, and a far-field wide-area mode of illumination;
an Automatic Light Exposure Measurement and Illumination Control
Subsystem 15; an Image Capturing and Buffering Subsystem 16; a Multi-Mode
Image-Processing Bar Code Symbol Reading Subsystem 17 having five
modes of image-processing based bar code symbol reading indicated
in FIG. 2A2 and to be described in detail hereinabove; an Input/Output
Subsystem 18; a manually-actuatable trigger switch 2C for sending
user-originated control activation signals to the device; a System
Mode Configuration Parameter Table 70; and a System Control Subsystem
18 integrated with each of the above-described subsystems, as shown.
[0218] The primary function of the IR-based Object Presence and
Range Detection Subsystem 12 is to automatically produce an IR-based
object detection field 20 within the FOV of the Multi-Mode Image
Formation and Detection Subsystem 13, detect the presence of an
object within predetermined regions of the object detection field
(20A, 20B), and generate control activation signals A1 which are
supplied to the System Control Subsystem 19 for indicating when
and where an object is detected within the object detection field
of the system.
[0219] In the first illustrative embodiment, the Multi-Mode Image
Formation And Detection (I.E. Camera) Subsystem 13 has image formation
(camera) optics 21 for producing a field of view (FOV) 23 upon an
object to be imaged and a CMOS area-image sensing array 22 for detecting
imaged light reflected off the object during illumination and image
acquisition/capture operations.
[0220] In the first illustrative embodiment, the primary function
of the Multi-Mode LED-Based Illumination Subsystem 14 is to produce
a narrow-area illumination field 24, near-field wide-area illumination
field 25, and a far-field wide-area illumination field 25, each
having a narrow optical-bandwidth and confined within the FOV of
the Multi-Mode Image Formation And Detection Subsystem 13 during
narrow-area and wide-area modes of imaging, respectively. This arrangement
is designed to ensure that only light transmitted from the Multi-Mode
Illumination Subsystem 14 and reflected from the illuminated object
is ultimately transmitted through a narrow-band transmission-type
optical filter subsystem 4 realized by (1) high-pass (i.e. red-wavelength
reflecting) filter element 4A mounted at the light transmission
aperture 3 immediately in front of panel 5, and (2) low-pass filter
element 4B mounted either before the image sensing array 22 or anywhere
after panel 5 as shown in FIG. 3C. FIG. 6A4 sets forth the resulting
composite transmission characteristics of the narrow-band transmission
spectral filter subsystem 4, plotted against the spectral characteristics
of the emission from the LED illumination arrays employed in the
Multi-Mode Illumination Subsystem 14.
[0221] The primary function of the narrow-band integrated optical
filter subsystem 4 is to ensure that the CMOS image sensing array
22 only receives the narrow-band visible illumination transmitted
by the three sets of LED-based illumination arrays 27, 28 and 29
driven by LED driver circuitry 30 associated with the Multi-Mode
Illumination Subsystem 14, whereas all other components of ambient
light collected by the light collection optics are substantially
rejected at the image sensing array 22, thereby providing improved
SNR thereat, thus improving the performance of the system.
[0222] The primary function of the Automatic Light Exposure Measurement
and Illumination Control Subsystem 15 is to twofold: (1) to measure,
in real-time, the power density [joules/cm] of photonic energy (i.e.
light) collected by the optics of the system at about its image
sensing array 22, and generate Auto-Exposure Control Signals indicating
the amount of exposure required for good image formation and detection;
and (2) in combination with Illumination Array Selection Control
Signal provided by the System Control Subsystem 19, automatically
drive and control the output power of selected LED arrays 27, 28
and/or 29 in the Multi-Mode Illumination Subsystem, so that objects
within the FOV of the system are optimally exposed to LED-based
illumination and optimal images are formed and detected at the image
sensing array 22.
[0223] The primary function of the Image Capturing and Buffering
Subsystem 16 is to (1) detect the entire 2-D image focused onto
the 2D image sensing array 22 by the image formation optics 21 of
the system, (2) generate a frame of digital pixel data 31 for either
a selected region of interest of the captured image frame, or for
the entire detected image, and then (3) buffer each frame of image
data as it is captured. Notably, in the illustrative embodiment,
a single 2D image frame (31) is captured during each image capture
and processing cycle, or during a particular stage of a processing
cycle, so as to eliminate the problems associated with image frame
overwriting, and synchronization of image capture and decoding processes,
as addressed in U.S. Pat. Nos. 5,932,862 and 5,942,741 assigned
to Welch Allyn, and incorporated herein by reference.
[0224] The primary function of the Multi-Mode Imaging-Based Bar
Code Symbol Reading Subsystem 17 is to process images that have
been captured and buffered by the Image Capturing and Buffering
Subsystem 16, during both narrow-area and wide-area illumination
modes of system operation. Such image processing operation includes
image-based bar code decoding methods illustrated in FIGS. 14 through
25, and described in detail hereinafter.
[0225] The primary function of the Input/Output Subsystem 18 is
to support standard and/or proprietary communication interfaces
with external host systems and devices, and output processed image
data and the like to such external host systems or devices by way
of such interfaces. Examples of such interfaces, and technology
for implementing the same, are given in U.S. Pat. No. 6,619,549,
incorporated herein by reference in its entirety.
[0226] The primary function of the System Control Subsystem 19
is to provide some predetermined degree of control or management
signaling services to each subsystem component integrated, as shown.
While this subsystem can be implemented by a programmed microprocessor,
in the illustrative embodiment, it is implemented by the three-tier
software architecture supported on computing platform shown in FIG.
2B, and as represented in FIGS. 11A through 13L, and described in
detail hereinafter.
[0227] The primary function of the manually-activatable Trigger
Switch 2C integrated with the hand-supportable housing is to enable
the user to generate a control activation signal upon manually depressing
the Trigger Switch 2C, and to provide this control activation signal
to the System Control Subsystem 19 for use in carrying out its complex
system and subsystem control operations, described in detail herein.
[0228] The primary function of the System Mode Configuration Parameter
Table 70 is to store (in non-volatile/persistent memory) a set of
configuration parameters for each of the available Programmable
Modes of System Operation specified in the Programmable Mode of
Operation Table shown in FIGS. 26A and 26B, and which can be read
and used by the System Control Subsystem 19 as required during its
complex operations.
[0229] The detailed structure and function of each subsystem will
now be described in detail above.
Schematic Diagram as System Implementation Model for the Hand-Supportable
Digital Imaging-Based Bar Code Reading Device of the Present Invention
[0230] FIG. 2B shows a schematic diagram of a system implementation
for the hand-supportable Digital Imaging-Based Bar Code Symbol Reading
Device 1 illustrated in FIGS. 1A through 1L. As shown in this system
implementation, the bar code symbol reading device is realized using
a number of hardware component comprising: an illumination board
33 carrying components realizing electronic functions performed
by the LED-Based Multi-Mode Illumination Subsystem 14 and Automatic
Light Exposure Measurement And Illumination Control Subsystem 15;
a CMOS camera board 34 carrying high resolution (1280.times.1024
8-bit 6 micron pixel size) CMOS image sensing array 22 running at
25 Mhz master clock, at 7 frames/second at 1280*1024 resolution
with randomly accessible region of interest (ROI) window capabilities,
realizing electronic functions performed by the Multi-Mode Image
Formation and Detection Subsystem 13; a CPU board 35 (i.e. computing
platform) including (i) an Intel Sabinal 32-Bit Microprocessor PXA210
36 running at 200 mHz 1.0 core voltage with a 16 bit 100 Mhz external
bus speed, (ii) an expandable (e.g. 8+ megabyte) Intel J3 Asynchronous
16-bit Flash memory 37, (iii) an 16 Megabytes of 100 MHz SDRAM 38,
(iv) an Xilinx Spartan II FPGA FIFO 39 running at 50 Mhz clock frequency
and 60 MB/Sec data rate, configured to control the camera timings
and drive an image acquisition process, (v) a multimedia card socket
40, for realizing the other subsystems of the system, (vi) a power
management module 41 for the MCU adjustable by the I2C bus, and
(vii) a pair of UARTs 42A and 42B (one for an IRDA port and one
for a JTAG port); an interface board 43 for realizing the functions
performed by the I/O subsystem 18; and an IR-based object presence
and range detection circuit 44 for realizing Subsystem 12.
[0231] In the illustrative embodiment, the image formation optics
21 supported by the bar code reader provides a field of view of
103 mm at the nominal focal distance to the target, of approximately
70 mm from the edge of the bar code reader. The minimal size of
the field of view (FOV) is 62 mm at the nominal focal distance to
the target of approximately 10 mm. Preliminary tests of the parameters
of the optics are shown on FIG. 4B (the distance on FIG. 4B is given
from the position of the image sensing array 22, which is located
inside the bar code symbol reader approximately 80 mm from the edge).
As indicated in FIG. 4C, the depth of field of the image formation
optics varies from approximately 69 mm for the bar codes with resolution
of 5 mils per narrow module, to 181 mm for the bar codes with resolution
of 13 mils per narrow module.
[0232] The Multi-Mode Illumination Subsystem 14 is designed to
cover the optical field of view (FOV) 23 of the bar code symbol
reader with sufficient illumination to generate high-contrast images
of bar codes located at both short and long distances from the imaging
window. The illumination subsystem also provides a narrow-area (thin
height) targeting beam 24 having dual purposes: (a) to indicate
to the user where the optical view of the reader is; and (b) to
allow a quick scan of just a few lines of the image and attempt
a super-fast bar code decoding if the bar code is aligned properly.
If the bar code is not aligned for a linearly illuminated image
to decode, then the entire field of view is illuminated with a wide-area
illumination field 25 or 26 and the image of the entire field of
view is acquired by Image Capture and Buffering Subsystem 16 and
processed by Multi-Mode Bar Code Symbol Reading Subsystem 17, to
ensure reading of a bar code symbol presented therein regardless
of its orientation.
[0233] The interface board 43 employed within the bar code symbol
reader provides the hardware communication interfaces for the bar
code symbol reader to communicate with the outside world. The interfaces
implemented in system will typically include RS232, keyboard wedge,
and/or USB, or some combination of the above, as well as others
required or demanded by the particular application at hand.
Specification of the Area-Type Image Formation and Detection (i.e.
Camera) Subsystem During its Narrow-Area (Linear) and Wide-Area
Modes of Imaging, Supported by the Narrow and Wide Area Fields of
Narrow-Band Illumination, Respectively
[0234] As shown in FIGS. 3B through 3E, the Multi-Mode Image Formation
And Detection (IFD) Subsystem 13 has a narrow-area image capture
mode (i.e. where only a few central rows of pixels about the center
of the image sensing array are enabled) and a wide-area image capture
mode of operation (i.e. where all pixels in the image sensing array
are enabled). The CMOS image sensing array 22 in the Image Formation
and Detection Subsystem 13 has image formation optics 21 which provides
the image sensing array with a field of view (FOV) 23 on objects
to be illuminated and imaged. As shown, this FOV is illuminated
by the Multi-Mode Illumination Subsystem 14 integrated within the
bar code reader.
[0235] The Multi-Mode Illumination Subsystem 14 includes three
different LED-based illumination arrays 27, 28 and 29 mounted on
the light transmission window panel 5, and arranged about the light
transmission window 4A. Each illumination array is designed to illuminate
a different portion of the FOV of the bar code reader during different
modes of operation. During the narrow-area (linear) illumination
mode of the Multi-Mode Illumination Subsystem 14, the central narrow-wide
portion of the FOV indicated by 23 is illuminated by the narrow-area
illumination array 27, shown in FIG. 3A. During the near-field wide-area
illumination mode of the Multi-Mode Illumination Subsystem 14, which
is activated in response to the IR Object Presence and Range Detection
Subsystem 12 detecting an object within the near-field portion of
the FOV, the near-field wide-area portion of the FOV is illuminated
by the near-field wide-area illumination array 28, shown in FIG.
3A. During the far-field wide-area illumination mode of the Multi-Mode
Illumination Subsystem 14, which is activated in response to the
IR Object Presence and Range Detection Subsystem 12 detecting an
object within the far-field portion of the FOV, the far-field wide-area
portion of the FOV is illuminated by the far-field wide-area illumination
array 29, shown in FIG. 3A. In FIG. 3A, the spatial relationships
are shown between these fields of narrow-band illumination and the
far and near field portions the FOV of the Image Formation and Detection
Subsystem 13.
[0236] In FIG. 3B, the Multi-Mode LED-Based Illumination Subsystem
14 is shown transmitting visible narrow-band illumination through
its narrow-band transmission-type optical filter subsystem 4, shown
in FIG. 3C and integrated within the hand-supportable Digital Imaging-Based
Bar Code Symbol Reading Device. The narrow-band illumination from
the Multi-Mode Illumination Subsystem 14 illuminates an object with
the FOV of the image formation optics of the Image Formation and
Detection Subsystem 13, and light rays reflected and scattered therefrom
are transmitted through the high-pass and low-pass optical filters
4A and 4B and are ultimately focused onto image sensing array 22
to form of a focused detected image thereupon, while all other components
of ambient light are substantially rejected before reaching image
detection at the image sensing array 22. Notably, in the illustrative
embodiment, the red-wavelength reflecting high-pass optical filter
element 4A is positioned at the imaging window of the device before
the image formation optics 21, whereas the low-pass optical filter
element 4B is disposed before the image sensing array 22 between
the focusing lens elements of the image formation optics 21. This
forms narrow-band optical filter subsystem 4 which is integrated
within the bar code reader to ensure that the object within the
FOV is imaged at the image sensing array 22 using only spectral
components within the narrow-band of illumination produced from
Subsystem 14, while rejecting substantially all other components
of ambient light outside this narrow range (e.g. 15 nm).
[0237] As shown in FIG. 3D, the Image Formation And Detection Subsystem
14 employed within the hand-supportable image-based bar code reading
device comprising three lenses 21A, 21B and 21C, each made as small
as possible (with a maximum diameter of 12 mm), having spherical
surfaces, and made from common glass, e.g. LAK2 (.about.LaK9), ZF10
(=SF8), LAF2 (.about.LaF3). Collectively, these lenses are held
together within a lens holding assembly 45, as shown in FIG. 3E,
and form an image formation subsystem arranged along the optical
axis of the CMOS image sensing array 22 of the bar code reader.
[0238] As shown in FIG. 3E, the lens holding assembly 45 comprises:
a barrel structure 45A1, 45A2 for holding lens elements 21A, 21B
and 21C; and a base structure 45B for holding the image sensing
array 22; wherein the assembly is configured so that the barrel
structure 45A slides within the base structure 45B so as to focus
the fixed-focus lens assembly during manufacture.
[0239] In FIGS. 3F1 and 3F2, the lens holding assembly 45 and imaging
sensing array 22 are mounted along an optical path defined along
the central axis of the system. In the illustrative embodiment,
the image sensing array 22 has, for example, a 1280.times.1024 pixel
resolution (1/2'' format), 6 micron pixel size, with randomly accessible
region of interest (ROI) window capabilities. It is understood,
though, that many others kinds of imaging sensing devices (e.g.
CCD) can be used to practice the principles of the present invention
disclosed herein, without departing from the scope or spirit of
the present invention.
Method of Designing the Image Formation (i.e. Camera) Optics within
the Image-Based Bar Code Reader of the Present Invention Using the
Modulation Transfer Function (MTF)
[0240] The function of the image formation (i.e. camera) optics
in the Image Formation and Detection Subsystem 13 is to form and
project, as accurately as possible, an image of the object being
formed on the image sensing array 22. In practice, it is impossible
to get an absolutely perfect image reproduction of the object with
no loss of information, because the quality of the image is limited
by various effects. These effects include: (i) diffraction, always
present in even the very best lenses; (ii) aberrations which, if
present, can generally only be minimized, not eliminated; (iii)
variation of the distance to the object, especially if the lens
cannot dynamically adjust its focus; and so on. Before spending
time and money to produce a lens assembly, it is necessary to determine
that a given lens design for the bar code symbol reader of the present
invention will perform well enough to satisfy the requirements of
the application. Thus, it will be extremely helpful to (i) establish
one or more design criteria to quantify the lens performance, and
(ii) optimize the design around these criteria until the desired
performance is achieved.
[0241] The preferred criterion for designing the image formation
optics in the system hereof is the modulation transfer function,
or MTF. The MTF provides a measure of the contrast present in an
object or image. Qualitatively, contrast may be thought of as the
difference between light and dark regions in the object or image.
The greater the difference in "brightness" between two
regions of the object or image, the greater the contrast. Considering
the image, given the data from the image sensor, a quantitative
treatment is possible. On the common 8 bit scale, a pixel that is
totally black is assigned the value 0, while a pixel that is totally
saturated white is assigned the value 255. Also, the closer the
spacing of the object features, then the worse the reproduction
of that contrast in the image of the object. A mathematical expression
is required to quantify the amount of contrast present in an object
or image, so that its variation after imaging through the optics
may be assessed. A useful contrast measure can be defined as the
modulation M of a given region in the object, given as follows:
M = max .times. .times. value - min .times. .times. value max .times.
.times. value + min .times. .times. value The greater the contrast
in the object or image, the greater the value of M, up to a maximum
of 1. On the other hand, no contrast whatever in the object or image
(i.e. no distinguishable features in the region of the object in
question) yields a modulation of 0. To determine how well the image
formation optics preserves the modulation of the target object in
the image, it is only necessary to form a ratio of the image modulation
to the object modulation, which is the MTF: M .times. .times. T
.times. .times. F = image .times. .times. modulation object .times.
.times. modulation Perfect reproduction of the object contrast in
the image (impossible in practice) results in an MTF of 1. A total
loss of the object contrast in the image gives an MTF of 0.
[0242] The MTF is a useful concept in optical design because it
simultaneously accounts for the impact of any effect that degrades
the quality of the image, usually referred to as blurring. As described
previously, these effects include diffraction, aberrations (spherical,
chromatic, coma, astigmatism, field curvature) and deviation of
the object distance from its nominal value. It should be mentioned
for sake of completeness, however, that MTF is not a single perfect
or all-encompassing measure of image quality. One potential drawback
is that examining the MTF reveals only the total impact of all effects
simultaneously, and cannot distinguish between blurring caused by
one defect or another. If it is necessary to determine what effects
are degrading the MTF, and to what extent for each, then other methods
must be used, and other criteria examined. In addition, there are
potentially negative image characteristics, such as distortion,
that are not revealed at all by the MTF. If the optical designer
is not careful, then it is possible that an image with an MTF close
to the diffraction limit, which is as good as it is possible to
get, may have distortion so bad that it is unusable in the application
at hand.
[0243] In accordance with the design method of the present invention,
after calculating the MTF for a given optical design, an additional
criterion is necessary to specify what MTF is good enough for the
application in question. For bar code decoding applications, a useful
rule of thumb is that 0.3 MTF or better is needed for decoding software
to work reliably well in an Imaging-Based Bar Code Symbol Reader.
The design strategy employed on the Imaging-Based Bar Code Symbol
Reader of the present invention is to determine, as a function of
object distance, the code element size (in millimeters) at which
the MTF of the resulting image falls to 0.3. In other words, at
each object distance, the optical designer should determine what
is the smallest size of code element (in millimeters) that can be
imaged well enough to be read by the Multi-Mode Image-Processing
Bar Code Reading Subsystem 17 of the present invention. At one stage
of the design of the image formation optics employed in the illustrative
embodiment, the plot of minimum code element size against object
distance is generated, as shown in FIG. 4E. Given such a plot, the
optical design team needs to determine whether or not the resulting
bar code reader performance satisfies the requirements of the application
at hand. To help make this determination, an advanced optical design
method and tool described below can be used with excellent results.
Method of Theoretically Characterizing the DOF of the Image Formation
Optics Employed in the Imaging-Based Bar Code Reader of the Present
Invention
[0244] Referring to FIGS. 4D through 4I3, a novel software-enabled
design tool and method will now be described.
[0245] In general, the software-enabled optical design tool provides
a novel way of and means for completely theoretically characterizing,
and graphically viewing and interpreting the composite DOF of image
formation optics (e.g. such as 21 employed in the Imaging-Based
Bar Code Symbol Reader of the present invention) as well as other
imaging-based optical readers, while simultaneously accounting for
optical performance and image sensor limitations, over all desired
object distances and for all desired code mil sizes.
[0246] Given an arrangement of lens elements for the design of
the image formation optics 21, the optical design method of the
present invention involves using a software-based optical design
tool, as described in FIGS. 4I1 through 4I3, to generate the composite
DOF chart in accordance with the present invention. The functions
required by this optical design tool will be described below. The
software-based optical design tool (i.e. computer program) of the
illustrative embodiment, described in FIGS. 4I1 through 4I3, has
been developed using Zemax.RTM. optical modeling software, programmed
in ZPL (Zemax Programming Language) in accordance with the principles
of the present invention described in detail below.
[0247] The first function required by the optical design tool of
the present invention is that it must be able to calculate the modulation
transfer function (MTF) of the image resulting from image formation
optics 21, plotted as a function of object distance. The general
industry rule of thumb is that a 0.3 MTF is the minimum acceptable
for bar code decoding. Therefore, this software-based optical design
tool must be able to determine, as a function of object distance,
the object spatial-frequency at which the MTF of the image drops
to 0.3.
[0248] The second function required by the optical design tool
of the present invention is that it must be able to convert the
object spatial-frequency to code mil size, and then this data should
be plotted against object distance. A resulting plot is shown in
FIG. 4D, where the dotted-line curve shows the optical performance
of the image formation optics, in terms of the smallest mil size
code that can be decoded, at a given object distance. FIG. 4E demonstrates
how to read the DOF from this plot, by finding the intersections
of the mil size in question with the optical performance curve.
[0249] However, optical performance of the image formation optics
is not the only factor determining the capacity of an Imaging-Based
Bar Code Symbol Reader to read bar code symbols having bar code
elements of a given width. Image-processing based bar code symbol
decoding software requires a certain minimum number of sensor pixel
"fields of view" to be projected onto each minimum width
code element, within the field of the view of the image formation
optics. The general industry rule of thumb is that 1.6 pixels are
required per narrow element for acceptable decoding. In accordance
with the present invention, this rule has been expanded to the range
of 1.4 to 1.6 pixels per narrow element, and can be considered a
limit imposed by sampling theory that will restrict the ultimate
performance of the bar code symbol reader 1 regardless of the individual
performance of its image formation optics 21.
[0250] Therefore, the third function required by the optical design
tool of the present invention is that it must be able to calculate,
as a function of object distance, the size of the field of view
of a single sensor pixel when projected through the image formation
optics 21 and out into object space (that is, accounting for the
optical magnification of the image formation optics 21). These linear
functions, both for the 1.4 and 1.6 pixel rules, are preferably
plotted on the same axes as the optical performance curve, as shown
in FIG. 4F.
[0251] Having described the primary functionalities of the optical
design tool of the present invention, and how to generate a composite
DOF plot as shown in FIG. 4F for an Imaging-Based Bar Code Symbol
Reader, it is now appropriate to describe, with reference to FIG.
4G, how to determine the actual composite DOF curve, accounting
for both optical performance and sampling limit, for the 1.6 pixel
case. Other system information, such as lens focal length, lens
f-number, etc. may also be displayed on the composite DOF plot of
FIG. 4G, for instance in a title block.
[0252] As shown in FIG. 4G, the method involves following the optical
performance curve until it intersects the sampling limit line. Then,
the sampling limit line is followed until it re-intersects the optical
performance curve, at which point the optical performance curve
is again followed. Thus, the sampling limit line of choice represents
the lower limit of the decoding resolution of the system. Referring
to FIG. 4H, a simple technique is shown for reading the DOF from
the composite plot of FIG. 4G.
[0253] Preferably, the optical design tool of the present invention
will be provide with a simple graphical user interface (GUI) may
be useful, supporting pop-up windows to enable the user to easily
type numbers into the program. Also, the optical design tool will
preferably implement various methods to allow the user to specify
some of the required numbers while the program is running, as oppose
to having to change the numbers in the program file.
[0254] A less preferred alternative way of practicing the optical
design method of the present invention would be to manually construct
the composite DOF plot by examining MTF data and plotting the results
in Excel, for example. However, this approach is labor intensive
and does not offer any appreciable increase in accuracy, as does
the use of the software-enabled optical design tool described in
FIGS. 4I1 through 4I3.
Specification of Multi-Mode LED-Based Illumination Subsystem Employed
in the Hand-Supportable Image-Based Bar Code Reading System of the
Present Invention
[0255] In the illustrative embodiment, the LED-Based Multi-Mode
Illumination Subsystem 14 comprises: narrow-area illumination array
27; near-field wide-area illumination array 28; and far-field wide-area
illumination array 29. The three fields of narrow-band illumination
produced by the three illumination arrays of subsystem 14 are schematically
depicted in FIG. 5A1. As will be described hereinafter, with reference
to FIGS. 27 and 28, narrow-area illumination array 27 can be realized
as two independently operable arrays, namely: a near-field narrow-area
illumination array and a far-field narrow-area illumination array,
which are activated when the target object is detected within the
near and far fields, respectively, of the automatic IR-based Object
Presence and Range Detection Subsystem 12 during wide-area imaging
modes of operation. However, for purposes of illustration, the first
illustrative embodiment of the present invention employs only a
single field narrow-area (linear) illumination array which is designed
to illuminate over substantially entire working range of the system,
as shown in FIG. 5A1.
[0256] As shown in FIGS. 5B, 5C3 and 5C4, the narrow-area (linear)
illumination array 27 includes two pairs of LED light sources 27A1
and 27A2 provided with cylindrical lenses 27B1 and 27B2, respectively,
and mounted on left and right portions of the light transmission
window panel 5. During the narrow-area image capture mode of the
Image Formation and Detection Subsystem 13, the narrow-area (linear)
illumination array 27 produces narrow-area illumination field 24
of narrow optical-bandwidth within the FOV of the system. In the
illustrative embodiment, narrow-area illumination field 24 has a
height less than 10 mm at far field, creating the appearance of
substantially linear or rather planar illumination field.
[0257] The near-field wide-area illumination array 28 includes
two sets of (flattop) LED light sources 28A1-28A6 and 28A7-28A13
without any lenses mounted on the top and bottom portions of the
light transmission window panel 5, as shown in FIG. 5B. During the
near-field wide-area image capture mode of the Image Formation and
Detection Subsystem 13, the near-field wide-area illumination array
28 produces a near-field wide-area illumination field 25 of narrow
optical-bandwidth within the FOV of the system.
[0258] As shown in FIGS. 5B, 5D3 and 5D4, the far-field wide-area
illumination array 29 includes two sets of LED light sources 29A1-29A6
and 29A7-29A13 provided with spherical (i.e. plano-convex) lenses
29B1-29B6 and 29B7-29B13, respectively, and mounted on the top and
bottom portions of the light transmission window panel 5. During
the far-field wide-area image capture mode of the Image Formation
and Detection Subsystem 13, the far-field wide-area illumination
array 29 produces a far-field wide-area illumination beam of narrow
optical-bandwidth within the FOV of the system.
Narrow-Area (Linear) Illumination Arrays Employed in the Multi-Mode
Illumination Subsystem
[0259] As shown in FIG. 5A1, the narrow-area (linear) illumination
field 24 extends from about 30 mm to about 200 mm within the working
range of the system, and covers both the near and far fields of
the system. The near-field wide-area illumination field 25 extends
from about 0 mm to about 100 mm within the working range of the
system. The far-field wide-area illumination field 26 extends from
about 100 mm to about 200 mm within the working range of the system.
The Table shown in FIG. 5A2 specifies the geometrical properties
and characteristics of each illumination mode supported by the Multi-Mode
LED-based Illumination Subsystem 14 of the present invention.
[0260] The narrow-area illumination array 27 employed in the Multi-Mode
LED-Based Illumination Subsystem 14 is optically designed to illuminate
a thin area at the center of the field of view (FOV) of the Imaging-Based
Bar Code Symbol Reader, measured from the boundary of the left side
of the field of view to the boundary of its right side, as specified
in FIG. 5A1. As will be described in greater detail hereinafter,
the narrow-area illumination field 24 is automatically generated
by the Multi-Mode LED-Based Illumination Subsystem 14 in response
to the detection of an object within the object detection field
of the automatic IR-based Object Presence and Range Detection Subsystem
12. In general, the object detection field of the IR-based Object
Presence and Range Detection Subsystem 12 and the FOV of the Image
Formation and Detection Subsystem 13 are spatially co-extensive
and the object detection field spatially overlaps the FOV along
the entire working distance of the Imaging-Based Bar Code Symbol
Reader. The narrow-area illumination field 24, produced in response
to the detection of an object, serves a dual purpose: it provides
a visual indication to an operator about the location of the optical
field of view of the bar code symbol reader, thus, serves as a field
of view aiming instrument; and during its image acquisition mode,
the narrow-area illumination beam is used to illuminated a thin
area of the FOV within which an object resides, and a narrow 2-D
image of the object can be rapidly captured (by a small number of
rows of pixels in the image sensing array 22), buffered and processed
in order to read any linear bar code symbols that may be represented
therewithin.
[0261] FIG. 5C1 shows the Lambertian emittance versus wavelength
characteristics of the LEDs used to implement the narrow-area illumination
array 27 in the Multi-Mode Illumination Subsystem 14. FIG. 5C2 shows
the Lambertian emittance versus polar angle characteristics of the
same LEDs. FIG. 5C3 shows the cylindrical lenses used before the
LEDs (633 nm InGaAlP) in the narrow-area (linear) illumination arrays
in the illumination subsystem of the present invention. As shown,
the first surface of the cylindrical lens is curved vertically to
create a narrow-area (linear) illumination pattern, and the second
surface of the cylindrical lens is curved horizontally to control
the height of the of the linear illumination pattern to produce
a narrow-area illumination pattern. FIG. 5C4 shows the layout of
the pairs of LEDs and two cylindrical lenses used to implement the
narrow-area illumination array of the illumination subsystem of
the present invention. In the illustrative embodiment, each LED
produces about a total output power of about 11.7 mW under typical
conditions. FIG. 5C5 sets forth a set of six illumination profiles
for the narrow-area illumination fields produced by the narrow-area
illumination arrays of the illustrative embodiment, taken at 30,
40, 50, 80, 120, and 220 millimeters along the field away from the
imaging window (i.e. working distance) of the bar code reader of
the present invention, illustrating that the spatial intensity of
the area-area illumination field begins to become substantially
uniform at about 80 millimeters. As shown, the narrow-area illumination
beam is usable beginning 40 mm from the light transmission/imaging
window.
Near-Field Wide-Area Illumination Arrays Employed in the Multi-Mode
Illumination Subsystem
[0262] The near-field wide-area illumination array 28 employed
in the LED-Based Multi-Mode Illumination Subsystem 14 is optically
designed to illuminate a wide area over a near-field portion of
the field of view (FOV) of the Imaging-Based Bar Code Symbol Reader,
as defined in FIG. 5A1. As will be described in greater detail hereinafter,
the near-field wide-area illumination field 28 is automatically
generated by the LED-based Multi-Mode Illumination Subsystem 14
in response to: (1) the detection of any object within the near-field
of the system by the IR-based Object Presence and Range Detection
Subsystem 12; and (2) one or more of following events, including,
for example: (i) failure of the image processor to successfully
decode process a linear bar code symbol during the narrow-area illumination
mode; (ii) detection of code elements such as control words associated
with a 2-D bar code symbol; and/or (iii) detection of pixel data
in the image which indicates that object was captured in a state
of focus.
[0263] In general, the object detection field of the IR-based Object
Presence and Range Detection Subsystem 12 and the FOV of the Image
Formation And Detection Subsystem 13 are spatially co-extensive
and the object detection field spatially overlaps the FOV along
the entire working distance of the Imaging-Based Bar Code Symbol
Reader. The near-field wide-area illumination field 23, produced
in response to one or more of the events described above, illuminates
a wide area over a near-field portion of the field of view (FOV)
of the Imaging-Based Bar Code Symbol Reader, as defined in FIG.
5A, within which an object resides, and a 2-D image of the object
can be rapidly captured (by all rows of the image sensing array
22, buffered and decode-processed in order to read any 1D or 2-D
bar code symbols that may be represented therewithin, at any orientation,
and of virtually any bar code symbology. The intensity of the near-field
wide-area illumination field during object illumination and image
capture operations is determined by how the LEDs associated with
the near-field wide array illumination arrays 28 are electrically
driven by the Multi-Mode Illumination Subsystem 14. The degree to
which the LEDs are driven is determined by the intensity of reflected
light measured near the image formation plane by the automatic light
exposure and control subsystem 15. If the intensity of reflected
light at the photodetector of the Automatic Light Exposure Measurement
and Illumination Control Subsystem 15 is weak, indicative that the
object exhibits low light reflectivity characteristics and a more
intense amount of illumination will need to be produced by the LEDs
to ensure sufficient light exposure on the image sensing array 22,
then the Automatic Light Exposure Measurement and Illumination Control
Subsystem 15 will drive the LEDs more intensely (i.e. at higher
operating currents).
[0264] FIG. 5D1 shows the Lambertian emittance versus wavelength
characteristics of the LEDs used to implement the wide area illumination
arrays in the illumination subsystem of the present invention. FIG.
5D2 shows the Lambertian emittance versus polar angle characteristics
of the LEDs used to implement the near field wide-area illumination
arrays in the Multi-Mode Illumination Subsystem 14. FIG. 5D4 is
geometrical the layout of LEDs used to implement the narrow wide-area
illumination array of the Multi-Mode Illumination Subsystem 14,
wherein the illumination beam produced therefrom is aimed by angling
the lenses before the LEDs in the near-field wide-area illumination
arrays of the Multi-Mode Illumination Subsystem 14. FIG. 5D5 sets
forth a set of six illumination profiles for the near-field wide-area
illumination fields produced by the near-field wide-area illumination
arrays of the illustrative embodiment, taken at 10, 20, 30, 40,
60, and 100 millimeters along the field away from the imaging window
(i.e. working distance) of the Imaging-Based Bar Code Symbol Reader
1. These plots illustrate that the spatial intensity of the near-field
wide-area illumination field begins to become substantially uniform
at about 40 millimeters (i.e. center:edge=2:1 max).
Far-Field Wide-Area Illumination Arrays Employed in the Multi-Mode
Illumination Subsystem
[0265] The far-field wide-area illumination array 26 employed in
the Multi-Mode LED-based Illumination Subsystem 14 is optically
designed to illuminate a wide area over a far-field portion of the
field of view (FOV) of the Imaging-Based Bar Code Symbol Reader,
as defined in FIG. 5A1. As will be described in greater detail hereinafter,
the far-field wide-area illumination field 26 is automatically generated
by the LED-Based Multi-Mode Illumination Subsystem 14 in response
to: (1) the detection of any object within the near-field of the
system by the IR-based Object Presence and Range Detection Subsystem
12; and (2) one or more of following events, including, for example:
(i) failure of the image processor to successfully decode process
a linear bar code symbol during the narrow-area illumination mode;
(ii) detection of code elements such as control words associated
with a 2-D bar code symbol; and/or (iii) detection of pixel data
in the image which indicates that object was captured in a state
of focus. In general, the object detection field of the IR-based
Object Presence and Range Detection Subsystem 12 and the FOV 23
of the image detection and formation subsystem 13 are spatially
co-extensive and the object detection field 20 spatially overlaps
the FOV 23 along the entire working distance of the Imaging-Based
Bar Code Symbol Reader. The far-field wide-area illumination field
26, produced in response to one or more of the events described
above, illuminates a wide area over a far-field portion of the field
of view (FOV) of the Imaging-Based Bar Code Symbol Reader, as defined
in FIG. 5A, within which an object resides, and a 2-D image of the
object can be rapidly captured (by all rows of the image sensing
array 22), buffered and processed in order to read any 1D or 2-D
bar code symbols that may be represented therewithin, at any orientation,
and of virtually any bar code symbology. The intensity of the far-field
wide-area illumination field during object illumination and image
capture operations is determined by how the LEDs associated with
the far-field wide-area illumination array 29 are electrically driven
by the Multi-Mode Illumination Subsystem 14. The degree to which
the LEDs are driven (i.e. measured in terms of junction current)
is determined by the intensity of reflected light measured near
the image formation plane by the Automatic Light Exposure Measurement
And Illumination Control Subsystem 15. If the intensity of reflected
light at the photo-detector of the Automatic Light Exposure Measurement
and Illumination Control Subsystem 15 is weak, indicative that the
object exhibits low light reflectivity characteristics and a more
intense amount of illumination will need to be produced b the LEDs
to ensure sufficient light exposure on the image sensing array 22,
then the Automatic Light Exposure Measurement and Illumination Control
Subsystem 15 will drive the LEDs more intensely (i.e. at higher
operating currents).
[0266] During both near and far field wide-area illumination modes
of operation, the Automatic Light Exposure Measurement and Illumination
Control Subsystem (i.e. module) 15 measures and controls the time
duration which the Multi-Mode Illumination Subsystem 14 exposes
the image sensing array 22 to narrow-band illumination (e.g. 633
nanometers, with approximately 15 nm bandwidth) during the image
capturing/acquisition process, and automatically terminates the
generation of such illumination when such computed time duration
expires. In accordance with the principles of the present invention,
this global exposure control process ensures that each and every
acquired image has good contrast and is not saturated, two conditions
essential for consistent and reliable bar code reading
[0267] FIG. 5D1 shows the Lambertian emittance versus wavelength
characteristics of the LEDs used to implement the far-field wide-area
illumination arrays 29 in the Multi-Mode Illumination Subsystem
14 FIG. 5D2 shows the Lambertian emittance versus polar angle characteristics
of the LEDs used to implement the same. FIG. 5D3 shows the plano-convex
lenses used before the LEDs in the far-field wide-area illumination
arrays in the Multi-Mode Illumination Subsystem 14. FIG. 5D4 shows
a layout of LEDs and piano-convex lenses used to implement the far
wide-area illumination array 29 of the illumination subsystem, wherein
the illumination beam produced therefrom is aimed by angling the
lenses before the LEDs in the far-field wide-area illumination arrays
of the Multi-Mode Illumination Subsystem 14. FIG. 5D6 sets forth
a set of three illumination profiles for the far-field wide-area
illumination fields produced by the far-field wide-area illumination
arrays of the illustrative embodiment, taken at 100, 150 and 220
millimeters along the field away from the imaging window (i.e. working
distance) of the Imaging-Based Bar Code Symbol Reader 1, illustrating
that the spatial intensity of the far-field wide-area illumination
field begins to become substantially uniform at about 100 millimeters.
FIG. 5D7 shows a table illustrating a preferred method of calculating
the pixel intensity value for the center of the far field wide-area
illumination field produced from the Multi-Mode Illumination Subsystem
14, showing a significant signal strength (greater than 80 DN at
the far center field).
Specification of the Narrow-Band Optical Filter Subsystem Integrated
within the Hand-Supportable Housing of the Imager of the Present
Invention
[0268] As shown in FIG. 6A1, the hand-supportable housing of the
bar code reader of the present invention has integrated within its
housing, narrow-band optical filter subsystem 4 for transmitting
substantially only the very narrow band of wavelengths (e.g. 620-700
nanometers) of visible illumination produced from the narrow-band
Multi-Mode Illumination Subsystem 14, and rejecting all other optical
wavelengths outside this narrow optical band however generated (i.e.
ambient light sources). As shown, narrow-band optical filter subsystem
4 comprises: red-wavelength reflecting (high-pass) imaging window
filter 4A integrated within its light transmission aperture 3 formed
on the front face of the hand-supportable housing; and low pass
optical filter 4B disposed before the CMOS image sensing array 22.
These optical filters 4A and 4B cooperate to form the narrow-band
optical filter subsystem 4 for the purpose described above. As shown
in FIG. 6A2, the light transmission characteristics (energy versus
wavelength) associated with the low-pass optical filter element
4B indicate that optical wavelengths below 620 nanometers are transmitted
therethrough, whereas optical wavelengths above 620 nm are substantially
blocked (e.g. absorbed or reflected). As shown in FIG. 6A3, the
light transmission characteristics (energy versus wavelength) associated
with the high-pass imaging window filter 4A indicate that optical
wavelengths above 700 nanometers are transmitted therethrough, thereby
producing a red-color appearance to the user, whereas optical wavelengths
below 700 nm are substantially blocked (e.g. absorbed or reflected)
by optical filter 4A.
[0269] During system operation, spectral band-pass filter subsystem
4 greatly reduces the influence of the ambient light, which falls
upon the CMOS image sensing array 22 during the image capturing
operations. By virtue of the optical filter of the present invention,
a optical shutter mechanism is eliminated in the system. In practice,
the optical filter can reject more than 85% of incident ambient
light, and in typical environments, the intensity of LED illumination
is significantly more than the ambient light on the CMOS image sensing
array 22. Thus, while an optical shutter is required in nearly most
conventional CMOS imaging systems, the imaging-based bar code reading
system of the present invention effectively manages the exposure
time of narrow-band illumination onto its CMOS image sensing array
22 by simply controlling the illumination time of its LED-based
illumination arrays 27, 28 and 29 using control signals generated
by Automatic Light Exposure Measurement and Illumination Control
Subsystem 15 and the CMOS image sensing array 22 while controlling
illumination thereto by way of the band-pass optical filter subsystem
4 described above. The result is a simple system design, without
moving parts, and having a reduced manufacturing cost.
[0270] While the band-pass optical filter subsystem 4 is shown
comprising a high-pass filter element 4A and low-pass filter element
4B, separated spatially from each other by other optical components
along the optical path of the system, subsystem 4 may be realized
as an integrated multi-layer filter structure installed in front
of the Image Formation And Detection (IFD) Module 13, or before
its image sensing array 22, without the use of the high-pass window
filter 4A, or with the use thereof so as to obscure viewing within
the Imaging-Based Bar Code Symbol Reader while creating an attractive
red-colored protective window. Preferably, the red-color window
filter 4A will have substantially planar surface characteristics
to avoid focusing or defocusing of light transmitted therethrough
during imaging operations.
Specification of the Automatic Light Exposure Measurement and Illumination
Control Subsystem of the Present Invention
[0271] The primary function of the Automatic Light Exposure Measurement
and Illumination Control Subsystem 15 is to control the brightness
and contrast of acquired images by (i) measuring light exposure
at the image plane of the CMOS imaging sensing array 22 and (ii)
controlling the time duration that the Multi-Mode Illumination Subsystem
14 illuminates the target object with narrow-band illumination generated
from the activated LED illumination array. Thus, the Automatic Light
Exposure Measurement and Illumination Control Subsystem 15 eliminates
the need for a complex shuttering mechanism for CMOS-based image
sensing array 22. This novel mechanism ensures that the Imaging-Based
Bar Code Symbol Reader of the present invention generates non-saturated
images with enough brightness and contrast to guarantee fast and
reliable image-based bar code decoding in demanding end-user applications.
[0272] During object illumination, narrow-band LED-based light
is reflected from the target object (at which the hand-supportable
bar code reader is aimed) and is accumulated by the CMOS image sensing
array 22. Notably, the object illumination process must be carried
out for an optimal duration so that the acquired image frame has
good contrast and is not saturated. Such conditions are required
for the consistent and reliable bar code decoding operation and
performance. The Automatic Light Exposure Measurement and Illumination
Control Subsystem 15 measures the amount of light reflected from
the target object, calculates the maximum time that the CMOS image
sensing array 22 should be kept exposed to the actively-driven LED-based
illumination array associated with the Multi-Mode Illumination Subsystem
14, and then automatically deactivates the illumination array when
the calculated time to do so expires (i.e. lapses).
[0273] As shown in FIG. 7A of the illustrative embodiment, the
Automatic Light Exposure Measurement and Illumination Control Subsystem
15 comprises: a parabolic light-collecting mirror 55 mounted within
the head portion of the hand-supportable housing, for collecting
narrow-band LED-based light reflected from a central portion of
the FOV of the system, which is then transmitted through the narrow-band
optical filter subsystem 4 eliminating wide band spectral interference;
a light-sensing device (e.g. photo-diode) 56 mounted at the focal
point of the light collection mirror 55, for detecting the filtered
narrow-band optical signal focused therein by the light collecting
mirror 55; and an electronic circuitry 57 for processing electrical
signals produced by the photo-diode 56 indicative of the intensity
of detected light exposure levels within the focal plane of the
CMOS image sensing array 22. During light exposure measurement operations,
incident narrow-band LED-based illumination is gathered from the
center of the FOV of the system by the spherical light collecting
mirror 55 and narrow-band filtered by the narrow-band optical filter
subsystem 4 before being focused upon the photodiode 56 for intensity
detection. The photo-diode 56 converts the detected light signal
into an electrical signal having an amplitude which directly corresponds
to the intensity of the collected light signal.
[0274] As shown in FIG. 7B, the System Control Subsystem 19 generates
an Illumination Array Selection Control Signal which determines
which LED illumination array (i.e. the narrow-area illumination
array 27 or the far-field and narrow-field wide-area illumination
arrays 28 or 29) will be selectively driven at any instant in time
of system operation by LED Array Driver Circuitry 64 in the Automatic
Light Exposure Measurement and Illumination Control Subsystem 15.
As shown, electronic circuitry 57 processes the electrical signal
from photo-detector 56 and generates an Auto-Exposure Control Signal
for the selected LED illumination array. In term, this Auto-Exposure
Control Signal is provided to the LED Array Driver Circuitry 64,
along with an Illumination Array Selection Control Signal from the
System Control Subsystem 19, for selecting and driving (i.e. energizing)
one or more LED illumination array(s) so as to generate visible
illumination at a suitable intensity level and for suitable time
duration so that the CMOS image sensing array 22 automatically detects
digital high-resolution images of illuminated objects, with sufficient
contrast and brightness, while achieving Global Exposure Control
objectives of the present invention disclosed herein. As shown in
FIGS. 7B and 7C, the Illumination Array Selection Control Signal
is generated by the System Control Subsystem 19 in response to (i)
reading the System Mode Configuration Parameters from the System
Mode Configuration Parameter Table 70, shown in FIG. 2A1, for the
programmed mode of system operation at hand, and (ii) detecting
the output from the automatic IR-based Object Presence and Range
Detection Subsystem 12.
[0275] Notably, in the illustrative embodiment, there are three
possible LED-based illumination arrays 27, 28 and 29 which can be
selected for activation by the System Control Subsystem 19, and
the upper and/or lower LED subarrays in illumination arrays 28 and
29 can be selectively activated or deactivated on a subarray-by-subarray
basis, for various purposes taught herein, including automatic specular
reflection noise reduction during wide-area image capture modes
of operation.
[0276] Each one of these illumination arrays can be driven to different
states depending on the Auto-Exposure Control Signal generated by
electronic signal processing circuit 57, which will be generally
a function of object distance, object surface reflectivity and the
ambient light conditions sensed at photo-detector 56, and measured
by signal processing circuit 57. The operation of signal processing
circuitry 57 will now be detailed below.
[0277] As shown in FIG. 7B, the narrow-band filtered optical signal
that is produced by the parabolic light focusing mirror 55 is focused
onto the photo-detector D1 56 which generates an analog electrical
signal whose amplitude corresponds to the intensity of the detected
optical signal. This analog electrical signal is supplied to the
signal processing circuit 57 for various stages of processing. The
first step of processing involves converting the analog electrical
signal from a current-based signal to a voltage-based signal which
is achieved by passing it through a constant-current source buffer
circuit 58, realized by one half of transistor Q1 (58). This inverted
voltage signal is then buffered by the second half of the transistor
Q1 (58) and is supplied as a first input to a summing junction 59.
As shown in FIGS. 7C1 and 7C2, the CMOS image sensing array 22 produces,
as output, a digital Electronic Rolling Shutter (ERS) pulse signal
60, wherein the duration of this ERS pulse signal 60 is fixed to
a maximum exposure time allowed in the system. The ERS pulse signal
60 is buffered through transistor Q2 61 and forms the other side
of the summing junction 59. The outputs from transistors Q1 and
Q2 form an input to the summing junction 59. A capacitor C5 is provided
on the output of the summing junction 59 and provides a minimum
integration time sufficient to reduce any voltage overshoot in the
signal processing circuit 57. The output signal across the capacitor
C5 is further processed by a comparator U1 62. In the illustrative
embodiment, the comparator reference voltage signal is set to 1.7
volts. This reference voltage signal sets the minimum threshold
level for the light exposure measurement circuit 57. The output
signal from the comparator 62 is inverted by inverter U3 63 to provide
a positive logic pulse signal which is supplied, as Auto-Exposure
Control Signal, to the input of the LED array driver circuit 64
shown in FIGS. 7C1 and 7C2.
[0278] As will be explained in greater detail below, the LED Array
Driver Circuit 64 shown in FIGS. 7C1 and 7C2 automatically drives
an activated LED illuminated array, and the operation of LED Array
Driver Circuit 64 depends on the mode of operation in which the
Multi-Mode Illumination Subsystem 14 is configured. In turn, the
mode of operation in which the Multi-Mode Illumination Subsystem
14 is configured at any moment in time will typically depend on
(i) the state of operation of the Object Presence and Range Detection
Subsystem 12 and (ii) the programmed mode of operation in which
the entire Imaging-Based Bar Code Symbol Reading System is configured
using System Mode Configuration Parameters read from the Table 70
shown in FIG. 2A1.
[0279] As shown in FIGS. 7C1 and 7C2, the LED Array Driver Circuit
64 comprises analog and digital circuitry which receives two input
signals: (i) the Auto-Exposure Control Signal from signal processing
circuit 57; and (ii) the Illumination Array Selection Control Signal.
The LED Array Driver Circuit 64 generates, as output, digital pulse-width
modulated (PCM) drive signals provided to either the narrow-area
illumination array 27, the upper and/or lower LED subarray employed
in the near-field wide-area illumination array 28, and/or the upper
and/or lower LED subarrays employed in the far-field wide-area illumination
array 29. Depending on which Mode of System Operation the Imaging-Based
Bar Code Symbol Reader has been configured, the LED Array Driver
Circuit 64 will drive one or more of the above-described LED illumination
arrays during object illumination and imaging operations. As will
be described in greater detail below, when all rows of pixels in
the CMOS image sensing array 22 are in a state of integration (and
thus have a common integration time), such LED illumination array(s)
are automatically driven by the LED Array Driver Circuit 64 at an
intensity and for duration computed (in an analog manner) by the
Automatic Light Exposure and Illumination Control Subsystem 15 so
as to capture digital images having good contrast and brightness,
independent of the light intensity of the ambient environment and
the relative motion of target object with respect to the Imaging-Based
Bar Code Symbol Reader.
Global Exposure Control Method of the Present Invention Carried
Out Using the CMOS Image Sensing Array
[0280] In the illustrative embodiment, the CMOS image sensing array
22 is operated in its Single Frame Shutter Mode (i.e. rather than
its Continuous Frame Shutter Mode) as shown in FIG. 7D, and employs
a novel exposure control method which ensure that all rows of pixels
in the CMOS image sensing array 22 have a common integration time,
thereby capturing high quality images even when the object is in
a state of high speed motion. This novel exposure control technique
shall be referred to as "the global exposure control method"
of the present invention, and the flow chart of FIGS. 7E1 and 7E2
describes clearly and in great detail how this method is implemented
in the Imaging-Based Bar Code Symbol Reader of the illustrative
embodiment. The global exposure control method will now be described
in detail below
[0281] As indicated at Block A in FIG. 7E1, Step A in the global
exposure control method involves selecting the single frame shutter
mode of operation for the CMOS imaging sensing array provided within
an imaging-based bar code symbol reading system employing an automatic
light exposure measurement and illumination control subsystem, a
multi-mode illumination subsystem, and a system control subsystem
integrated therewith, and image formation optics providing the CMOS
image sensing array with a field of view into a region of space
where objects to be imaged are presented.
[0282] As indicated in Block B in FIG. 7E1, Step B in the global
exposure control method involves using the automatic light exposure
measurement and illumination control subsystem to continuously collect
illumination from a portion of the field of view, detect the intensity
of the collected illumination, and generate an electrical analog
signal corresponding to the detected intensity, for processing.
[0283] As indicated in Block C in FIG. 7E1, Step C in the global
exposure control method involves activating (e.g. by way of the
system control subsystem 19 or directly by way of trigger switch
2C) the CMOS image sensing array so that its rows of pixels begin
to integrate photonically generated electrical charge in response
to the formation of an image onto the CMOS image sensing array by
the image formation optics of the system.
[0284] As indicated in Block D in FIG. 7E1, Step D in the global
exposure control method involves the CMOS image sensing array 22
automatically (i) generating an Electronic Rolling Shutter (ERS)
digital pulse signal when all rows of pixels in the image sensing
array are operated in a state of integration, and providing this
ERS pulse signal to the Automatic Light Exposure Measurement And
Illumination Control Subsystem 15 so as to activate light exposure
measurement and illumination control functions/operations therewithin.
[0285] As indicated in Block E in FIG. 7E2, Step E in the global
exposure control method involves, upon activation of light exposure
measurement and illumination control functions within Subsystem
15, (i) processing the electrical analog signal being continuously
generated therewithin, (ii) measuring the light exposure level within
a central portion of the field of view 23 (determined by light collecting
optics 55 shown in FIG. 7A), and (iii) generating an Auto-Exposure
Control Signal for controlling the generation of visible field of
illumination from at least one LED-based illumination array (27,
28 and/or 29) in the Multi-Mode Illumination Subsystem 14 which
is selected by an Illumination Array Selection Control Signal produced
by the System Control Subsystem 19.
[0286] Finally, as indicated at Block F in FIG. 7E2, Step F in
the global exposure control method involves using (i) the Auto-Exposure
Control Signal and (ii) the Illumination Array Selection Control
Signal to drive the selected LED-based illumination array(s) and
illuminate the field of view of the CMOS image sensing array 22
in whatever image capture mode it may be configured, precisely when
all rows of pixels in the CMOS image sensing array are in a state
of integration, as illustrated in FIG. 7D, thereby ensuring that
all rows of pixels in the CMOS image sensing array have a common
integration time. By enabling all rows of pixels in the CMOS image
sensing array 22 to have a common integration time, high-speed "global
exposure control" is effectively achieved within the Imaging-Based
Bar Code Symbol Reader of the present invention, and consequently,
high quality images are captured independent of the relative motion
between the Bar Code Symbol Reader and the target object.
Specification of the IR-Based Automatic Object Presence and Range
Detection Subsystem Employed in the Hand-Supportable Digital Image-Based
Bar Code Reading Device of the Present Invention
[0287] As shown in FIG. 8A, IR-wavelength based Automatic Object
Presence and Range Detection Subsystem 12 is realized in the form
of a compact optics module 76 mounted on the front portion of optics
bench 6, as shown in FIG. 1J.
[0288] As shown in FIG. 8, the Object Presence and Range Detection
Module 12 of the illustrative embodiment comprises a number of subcomponents,
namely: an optical bench 77 having an ultra-small footprint for
supporting optical and electro-optical components used to implement
the subsystem 12; at least one IR laser diode 78 mounted on the
optical bench 77, for producing a low power IR laser beam 79; IR
beam shaping optics 80, supported on the optical bench for shaping
the IR laser beam (e.g. into a pencil-beam like geometry) and directing
the same into the central portion of the object detection field
20 defined by the field of view (FOV) of IR light collection/focusing
optics 81 supported on the optical bench 77; an amplitude modulation
(AM) circuit 82 supported on the optical bench 77, for modulating
the amplitude of the IR laser beam produced from the IR laser diode
at a frequency f.sub.0 (e.g. 75 Mhz) with up to 7.5 milliWatts of
optical power; optical detector (e.g. an avalanche-type IR photodetector)
83, mounted at the focal point of the IR light collection/focusing
optics 81, for receiving the IR optical signal reflected off an
object within the object detection field, and converting the received
optical signal 84 into an electrical signal 85; an amplifier and
filter circuit 86, mounted on the optical bench 77, for isolating
the f.sub.0 signal component and amplifying it; a limiting amplifier
87, mounted on the optical bench, for maintaining a stable signal
level; a phase detector 88, mounted on the optical bench 77, for
mixing the reference signal component f.sub.0 from the AM circuit
82 and the received signal component f.sub.0 reflected from the
packages and producing a resulting signal which is equal to a DC
voltage proportional to the Cosine of the phase difference between
the reference and the reflected f.sub.0 signals; an amplifier circuit
89, mounted on the optical bench 77, for amplifying the phase difference
signal; a received signal strength indicator (RSSI) 90, mounted
on the optical bench 77, for producing a voltage proportional to
a LOG of the signal reflected from the target object which can be
used to provide additional information; a reflectance level threshold
analog multiplexer 91 for rejecting information from the weak signals;
and a 12 bit A/D converter 92, mounted on the optical bench 77,
for converting the DC voltage signal from the RSSI circuit 90 into
sequence of time-based range data elements {R.sub.n,i}, taken along
nT discrete instances in time, where each range data element R.sub.n,i
provides a measure of the distance of the object referenced from
(i) the IR laser diode 78 to (ii) a point on the surface of the
object within the object detection field 20; and Range Analysis
Circuitry 93 described below.
[0289] In general, the function of Range Analysis Circuitry 93
is to analyze the digital range data from the A/D converter 90 and
generate two control activation signals, namely: (i) "an object
presence detection" type of control activation signal A.sub.1A
indicating simply whether an object is presence or absent from the
object detection field, regardless of the mode of operation in which
the Multi-Mode Illumination Subsystem 14 might be configured; and
(ii) "a near-field/far-field" range indication type of
control activation signal A.sub.1B indicating whether a detected
object is located in either the predefined near-field or far-field
portions of the object detection field, which correspond to the
near-field and far-field portions of the FOV of the Multi-Mode Image
Formation and Detection Subsystem 13.
[0290] Various kinds of analog and digital circuitry can be designed
to implement the IR-based Automatic Object Presence and Range Detection
Subsystem 12. Alternatively, this subsystem can be realized using
various kinds of range detection techniques as taught in U.S. Pat.
No. 6,637,659, incorporated herein by reference in its entirely.
[0291] In the illustrative embodiment, Automatic Object Presence
and Range Detection Subsystem 12 operates as follows. In System
Modes of Operation requiring automatic object presence and/or range
detection, Automatic Object Presence and Range Detection Subsystem
12 will be activated at system start-up and operational at all times
of system operation, typically continuously providing the System
Control Subsystem 19 with information about the state of objects
within both the far and near portions of the object detection field
20 of the Imaging-Based Symbol Reader. In general, this Subsystem
detects two basic states of presence and range, and therefore has
two basic states of operation. In its first state of operation,
the IR-based automatic Object Presence and Range Detection Subsystem
12 automatically detects an object within the near-field region
of the FOV 20, and in response thereto generates a first control
activation signal which is supplied to the System Control Subsystem
19 to indicate the occurrence of this first fact. In its second
state of operation, the IR-based automatic Object Presence and Range
Detection Subsystem 12 automatically detects an object within the
far-field region of the FOV 20, and in response thereto generates
a second control activation signal which is supplied to the System
Control Subsystem 19 to indicate the occurrence of this second fact.
As will be described in greater detail and throughout this Patent
Specification, these control activation signals are used by the
System Control Subsystem 19 during particular stages of the system
control process, such as determining (i) whether to activate either
the near-field and/or far-field LED illumination arrays, and (ii)
how strongly should these LED illumination arrays be driven to ensure
quality image exposure at the CMOS image sensing array 22.
Specification of the Mapping of Pixel Data Captured by the Imaging
Array into the SDRAM Under the Control of the Direct Memory Access
(DMA) Module within the Microprocessor
[0292] As shown in FIG. 9, the CMOS image sensing array 22 employed
in the Digital Imaging-Based Bar Code Symbol Reading Device hereof
is operably connected to its microprocessor 36 through FIFO 39 (realized
by way of a FPGA) and system bus shown in FIG. 2B. As shown, SDRAM
38 is also operably connected to the microprocessor 36 by way of
the system bus, thereby enabling the mapping of pixel data captured
by the CMOS image sensing array 22 into the SDRAM 38 under the control
of the direct memory access (DMA) module within the microprocessor
36.
[0293] Referring to FIG. 10, details will now be given on how the
bytes of pixel data captured by CMOS image sensing array 22 are
automatically mapped (i.e. captured and stored) into the addressable
memory storage locations of its SDRAM 38 during each image capture
cycle carried out within the hand-supportable imaging-based bar
code reading device of the present invention.
[0294] In the implementation of the illustrative embodiment, the
CMOS image sensing array 22 sends 8-bit gray-scale data bytes over
a parallel data connection to FPGA 39 which implements a FIFO using
its internal SRAM. The FIFO 39 stores the pixel data temporarily
and the microprocessor 36 initiates a DMA transfer from the FIFO
(which is mapped to address OXOCOOOOOO, chip select 3) to the SDRAM
38. In general, modern microprocessors have internal DMA modules,
and a preferred microprocessor design, the DMA module will contain
a 32-byte buffer. Without consuming any CPU cycles, the DMA module
can be programmed to read data from the FIFO 39, store read data
bytes in the DMA's buffer, and subsequently write the data to the
SDRAM 38. Alternatively, a DMA module can reside in FPGA 39 to directly
write the FIFO data into the SDRAM 38. This is done by sending a
bus request signal to the microprocessor 36, so that the microprocessor
36 releases control of the bus to the FPGA 39 which then takes over
the bus and writes data into the SDRAM 38.
[0295] Below, a brief description will be given on where pixel
data output from the CMOS image sensing array 22 is stored in the
SDRAM 38, and how the microprocessor (i.e. implementing a decode
algorithm) 36 accesses such stored pixel data bytes. FIG. 10 represents
the memory space of the SDRAM 38. A reserved memory space of 1.3
MB is used to store the output of the CMOS image sensing array 22.
This memory space is a 1:1 mapping of the pixel data from the CMOS
image sensing array 22. Each byte represents a pixel in the image
sensing array 22. Memory space is a mirror image of the pixel data
from the image sensing array 22. Thus, when the decode program (36)
accesses the memory, it is as if it is accessing the raw pixel image
of the image sensing array 22. No time code is needed to track the
data since the modes of operation of the bar code reader guarantee
that the microprocessor 36 is always accessing the up-to-date data,
and the pixel data sets are a true representation of the last optical
exposure. To prevent data corruption, i.e. new data coming in while
old data are still being processed, the reserved space is protected
by disabling further DMA access once a whole frame of pixel data
is written into memory. The DMA module is re-enabled until either
the microprocessor 36 has finished going through its memory, or
a timeout has occurred.
[0296] During image acquisition operations, the image pixels are
sequentially read out of the image sensing array 22. Although one
may choose to read and column-wise or row-wise for some CMOS image
sensors, without loss of generality, the row-by-row read out of
the data is preferred. The pixel image data set is arranged in the
SDRAM 38 sequentially, starting at address OXAOEC0000. To randomly
access any pixel in the SDRAM 38 is a straightforward matter: the
pixel at row y 1/4 column x located is at address (OXAOEC0000+y.times.1280+x).
[0297] As each image frame always has a frame start signal out
of the image sensing array 22, that signal can be used to start
the DMA process at address OXAOEC0000, and the address is continuously
incremented for the rest of the frame. But the reading of each image
frame is started at address OXAOEC0000 to avoid any misalignment
of data. Notably, however, if the microprocessor 36 has programmed
the CMOS image sensing array 22 to have a ROI window, then the starting
address will be modified to (OXAOEC0000+1280.times.R.sub.1), where
R.sub.1 is the row number of the top left corner of the ROI.
Specification of the Three-Tier Software Architecture of the Hand-Supportable
Digital Image-Based Bar Code Reading Device of the Present Invention
[0298] As shown in FIG. 11, the hand-supportable Digital Imaging-Based
Bar Code Symbol Reading Device of the present invention 1 is provided
with a three-tier software architecture comprising the following
software modules: (1) the Main Task module, the CodeGate Task module,
the Metroset Task module, the Application Events Manager module,
the User Commands Table module, and the Command Handler module,
each residing within the Application layer of the software architecture;
(2) the Tasks Manager module, the Events Dispatcher module, the
Input/Output Manager module, the User Commands Manager module, the
Timer Subsystem module, the Input/Output Subsystem module and the
Memory Control Subsystem module, each residing within the System
Core (SCORE) layer of the software architecture; and (3) the Linux
Kernal module, the Linux File System module, and Device Drivers
modules, each residing within the Linux Operating System (OS) layer
of the software architecture.
[0299] While the operating system layer of the Imaging-Based Bar
Code Symbol Reader is based upon the Linux operating system, it
is understood that other operating systems can be used (e.g. Microsoft
Windows, Max OXS, Unix, etc), and that the design preferably provides
for independence between the main Application Software Layer and
the Operating System Layer, and therefore, enables of the Application
Software Layer to be potentially transported to other platforms.
Moreover, the system design principles of the present invention
provides an extensibility of the system to other future products
with extensive usage of the common software components, which should
make the design of such products easier, decrease their development
time, and ensure their robustness.
[0300] In the illustrative embodiment, the above features are achieved
through the implementation of an event-driven multi-tasking, potentially
multi-user, Application layer running on top of the System Core
software layer, called SCORE. The SCORE layer is statically linked
with the product Application software, and therefore, runs in the
Application Level or layer of the system. The SCORE layer provides
a set of services to the Application in such a way that the Application
would not need to know the details of the underlying operating system,
although all operating system APIs are, of course, available to
the application as well. The SCORE software layer provides a real-time,
event-driven, OS-independent framework for the product Application
to operate. The event-driven architecture is achieved by creating
a means for detecting events (usually, but not necessarily, when
the hardware interrupts occur) and posting the events to the Application
for processing in real-time manner. The event detection and posting
is provided by the SCORE software layer. The SCORE layer also provides
the product Application with a means for starting and canceling
the software tasks, which can be running concurrently, hence, the
multi-tasking nature of the software system of the present invention.
Specification of Software Modules within the Score Layer of the
System Software Architecture Employed in Imaging-Based Bar Code
Reader of the Present Invention
[0301] The SCORE layer provides a number of services to the Application
layer.
[0302] The Tasks Manager provides a means for executing and canceling
specific application tasks (threads) at any time during the product
Application run.
[0303] The Events Dispatcher provides a means for signaling and
delivering all kinds of internal and external synchronous and asynchronous
events
[0304] When events occur, synchronously or asynchronously to the
Application, the Events Dispatcher dispatches them to the Application
Events Manager, which acts on the events accordingly as required
by the Application based on its current state. For example, based
on the particular event and current state of the application, the
Application Events Manager can decide to start a new task, or stop
currently running task, or do something else, or do nothing and
completely ignore the event.
[0305] The Input/Output Manager provides a means for monitoring
activities of input/output devices and signaling appropriate events
to the Application when such activities are detected.
[0306] The Input/Output Manager software module runs in the background
and monitors activities of external devices and user connections,
and signals appropriate events to the Application Layer, which such
activities are detected. The Input/Output Manager is a high-priority
thread that runs in parallel with the Application and reacts to
the input/output signals coming asynchronously from the hardware
devices, such as serial port, user trigger switch 2C, bar code reader,
network connections, etc. Based on these signals and optional input/output
requests (or lack thereof) from the Application, it generates appropriate
system events, which are delivered through the Events Dispatcher
to the Application Events Manager as quickly as possible as described
above.
[0307] The User Commands Manager provides a means for managing
user commands, and utilizes the User Commands Table provided by
the Application, and executes appropriate User Command Handler based
on the data entered by the user.
[0308] The Input/Output Subsystem software module provides a means
for creating and deleting input/output connections and communicating
with external systems and devices
[0309] The Timer Subsystem provides a means of creating, deleting,
and utilizing all kinds of logical timers.
[0310] The Memory Control Subsystem provides an interface for managing
the multi-level dynamic memory with the device, fully compatible
with standard dynamic memory management functions, as well as a
means for buffering collected data. The Memory Control Subsystem
provides a means for thread-level management of dynamic memory.
The interfaces of the Memory Control Subsystem are fully compatible
with standard C memory management functions. The system software
architecture is designed to provide connectivity of the device to
potentially multiple users, which may have different levels of authority
to operate with the device.
[0311] The User Commands Manager, which provides a standard way
of entering user commands, and executing application modules responsible
for handling the same. Each user command described in the User Commands
Table is a task that can be launched by the User Commands Manager
per user input, but only if the particular user's authority matches
the command's level of security.
[0312] The Events Dispatcher software module provides a means of
signaling and delivering events to the Application Events Manager,
including the starting of a new task, stopping a currently running
task, or doing something or nothing and simply ignoring the event.
[0313] FIG. 12B provides a Table listing examples of System-Defined
Events which can occur and be dispatched within the hand-supportable
Digital Imaging-Based Bar Code Symbol Reading Device of the present
invention, namely: SCORE_EVENT_POWER_UP which signals the completion
of system start-up and involves no parameters;_SCORE_EVENT_TIMEOUT
which signals the timeout of the logical timer, and involves the
parameter "pointer to timer id"; SCORE_EVENT_UNEXPECTED_INPUT
which signals that the unexpected input data is available and involves
the parameter "pointer to connection id"; SCORE_EVENT_TRIG_ON
which signals that the user pulled the trigger and involves no parameters;
SCORE_EVENT_TRIG_OFF which signals that the user released the trigger
and involves no parameters; SCORE_EVENT_OBJECT_DETECT_ON which signals
that the object is positioned under the bar code reader and involves
no parameters; SCORE_EVENT_OBJECT_DETECT_OFF which signals that
the object is removed from the field of view of the bar code reader
and involves no parameters; SCORE_EVENT_EXIT_TASK which signals
the end of the task execution and involves the pointer UTID; and
SCORE_EVENT_ABORT_TASK which signals the aborting of a task during
execution.
[0314] The Imaging-Based Bar Code Symbol Reader of the present
invention provides the user with a command-line interface (CLI),
which can work over the standard communication lines, such as RS232,
available in the Bar Code Reader. The CLI is used mostly for diagnostic
purposes, but can also be used for configuration purposes in addition
to the MetroSet.RTM. and MetroSelect.RTM. programming functionalities.
To send commands to the bar code reader utilizing the CLI, a user
must first enter the User Command Manager by typing in a special
character, which could actually be a combination of multiple and
simultaneous keystrokes, such Ctrl and S for example. Any standard
and widely available software communication tool, such as Windows
HyperTerminal, can be used to communicate with the Bar Code Reader.
The bar code reader acknowledges the readiness to accept commands
by sending the prompt, such as "MTLG>" back to the
user. The user can now type in any valid Application command. To
quit the User Command Manager and return the scanner back to its
normal operation, a user must enter another special character, which
could actually be a combination of multiple and simultaneous keystrokes,
such Ctrl and R for example.
[0315] An example of the valid command could be the "Save
Image" command, which is used to upload an image from the bar
code reader's memory to the host PC. This command has the following
CLI format:
[0316] save [ filename [ compr ] ]
where
[0317] (1) save is the command name.
[0318] (2) filename is the name of the file the image gets saved
in. If omitted, the default filename is "image.bmp".
[0319] (3) compr is the compression number, from 0 to 10. If omitted,
the default compression number is 0, meaning no compression. The
higher compression number, the higher image compression ratio, the
faster image transmission, but more distorted the image gets.
[0320] The Imaging-Based Bar Code Symbol Reader of the present
invention can have numerous commands. All commands are described
in a single table (User Commands Table shown in FIG. 11) contained
in the product Applications software layer. For each valid command,
the appropriate record in the table contains the command name, a
short description of the command, the command type, and the address
of the function that implements the command.
[0321] When a user enters a command, the User Command Manager looks
for the command in the table. If found, it executes the function
the address of which is provided in the record for the entered command.
Upon return from the function, the User Command Manager sends the
prompt to the user indicating that the command has been completed
and the User Command Manager is ready to accept a new command.
Specification of Software Modules within the Application Layer
of the System Software Architecture Employed in Imaging-Based Bar
Code Reader of the Present Invention
[0322] The image processing software employed within the system
hereof performs its bar code reading function by locating and recognizing
the bar codes within the frame of a captured image comprising pixel
data. The modular design of the image processing software provides
a rich set of image processing functions, which could be utilized
in the future for other potential applications, related or not related
to bar code symbol reading, such as: optical character recognition
(OCR) and verification (OCV); reading and verifying directly marked
symbols on various surfaces; facial recognition and other biometrics
identification; etc.
[0323] The CodeGate Task, in an infinite loop, performs the following
task. It illuminates a "thin" narrow horizontal area at
the center of the field-of-view (FOV) and acquires a digital image
of that area. It then attempts to read bar code symbols represented
in the captured frame of image data using the image processing software
facilities supported by the Image-Processing Bar Code Symbol Reading
Subsystem 17 of the present invention to be described in greater
detail hereinafter. If a bar code symbol is successfully read, then
Subsystem 17 saves the decoded data in the special CodeGate data
buffer. Otherwise, it clears the CodeGate data buffer. Then, it
continues the loop. The CodeGate Task never exits on its own. It
can be canceled by other modules in the system when reacting to
other events. For example, when a user pulls the trigger switch
2C, the event TRIGGER_ON is posted to the application. The Application
software responsible for processing this event, checks if the CodeGate
Task is running, and if so, it cancels it and then starts the Main
Task. The CodeGate Task can also be canceled upon OBJECT_DETECT_OFF
event, posted when the user moves the bar code reader away from
the object, or when the user moves the object away from the bar
code reader.
[0324] Depending the System Mode in which the Imaging-Based Bar
Code Symbol Reader is configured, Main Task will typically perform
differently. For example, when the Imaging-Based Bar Code Symbol
Reader is configured in the Programmable Mode of System Operation
No. 12 (i.e. Semi-Automatic-Triggered Multiple-Attempt 1D/2D Single-Read
Mode) to be described in greater detail hereinafter, the Main Task
first checks if the CodeGate Data Buffer contains data decoded by
the CodeGate Task. If so, then it immediately sends the data out
to the user by executing the Data Output procedure and exits. Otherwise,
in a loop, the Main Task does the following: it illuminates an entire
area of the field-of-view and acquires a full-frame image of that
area. It attempts to read a bar code symbol the captured image.
If it successfully reads a bar code symbol, then it immediately
sends the data out to the user by executing the Data Output procedure
and exits. Otherwise, it continues the loop. Notably, upon successful
read and prior to executing the Data Output procedure, the Main
Task analyzes the decoded data for a "reader programming"
command or a sequence of commands. If necessary, it executes the
MetroSelect functionality. The Main Task can be canceled by other
modules within the system when reacting to other events. For example,
the bar code reader of the present invention can be re-configured
using standard Metrologic configuration methods, such as MetroSelec.RTM.
and MetroSet.RTM.. The MetroSelect functionality is executed during
the Main Task.
[0325] The MetroSet functionality is executed by the special MetroSet
Task. When the Focus RS232 software driver detects a special NULL-signal
on its communication lines, it posts the METROSET_ON event to the
Application. The Application software responsible for processing
this event starts the MetroSet task. Once the MetroSet Task is completed,
the scanner returns to its normal operation.
Operating System Layer Software Modules within the Application
Layer of the System Software Architecture Employed in Imaging-Based
Bar Code Reader of the Present Invention
[0326] The Devices Drivers software modules, which includes trigger
drivers, provides a means for establishing a software connection
with the hardware-based manually-actuated trigger switch 2C employed
on the imaging-based device, an image acquisition driver for implementing
image acquisition functionality aboard the imaging-based device,
and an IR driver for implementing object detection functionality
aboard the imaging-based device.
[0327] As shown in FIG. 12I, the Device Drive software modules
include: trigger drivers for establishing a software connection
with the hardware-based manually-actuated trigger switch 2C employed
on the Imaging-Based Bar Code Symbol Reader of the present invention;
an image acquisition driver for implementing image acquisition functionality
aboard the Imaging-Based Bar Code Symbol Reader; and an IR driver
for implementing object detection functionality aboard the Imaging-Based
Bar Code Symbol Reader.
Basic System Operations Supported by the Three-Tier Software Architecture
of the Hand-Supportable Digital Imaging-Based Bar Code Reading Device
of the Present Invention
[0328] In FIGS. 13A through 13L, the basic systems operations supported
by the three-tier software architecture of the digital Imaging-Based
Bar Code Reading Device of the present invention are schematically
depicted. Notably, these basic operations represent functional modules
(or building blocks) with the system architecture of the present
invention, which can be combined in various combinations to implement
the numerous Programmable Modes of System Operation listed in FIG.
23 and described in detail below, using the image acquisition and
processing platform disclosed herein. For purposes of illustration,
and the avoidance of obfuscation of the present invention, these
basic system operations will be described below with reference to
Programmable Mode of System Operation No. 12: Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Single-Read Mode Employing The No-Finder
Mode And The Manual Or Automatic Modes Of the Multi-Mode Bar Code
Reading Subsystem 17.
[0329] FIG. 13A shows the basic operations carried out within the
System Core Layer of the system when the user points the bar code
reader towards a bar code symbol on an object. Such operations include
the by IR device drivers enabling automatic detection of the object
within the field, and waking up of the Input/Output Manager software
module. As shown in FIG. 13B, the Input/Output Manager then posts
the SCORE_OBJECT_DETECT_ON event to the Events Dispatcher software
module in response to detecting an object. Then as shown in FIG.
13C, the Events Dispatcher software module passes the SCORE_OBJECT_DETECT_ON
event to the Application Layer. FIG. 13D shows that, upon receiving
the SCORE_OBJECT_DETECT_ON event at the Application Layer, the Application
Events Manager executes an event handling routine (shown in FIG.
13D) which activates the narrow-area (linear) illumination array
27 (i.e. during narrow-area illumination and image capture modes),
and then executes the CodeGate Task described in FIG. 13E. As shown
in the flow chart of FIG. 13D, the system event handling routine
first involves determining whether the CodeGate Task has been enabled
and if not, then the system exits the event handling routine. If
the CodeGate Task has been enabled (as would be the case for Programmable
Mode of System Operation No. 12, in particular), then the routine
proceeds to determine whether the "Presentation Mode"
(i.e. Programmable Mode of System Operation No. 10) has been enabled,
and if so, then the Application Layer executes the Main Task shown
in FIG. 13J, and if not, then activates the narrow area illumination
mode of the Multi-Mode Illumination Subsystem 14, and then executes
the CodeGate Task shown in FIG. 13E.
[0330] As shown in FIG. 13E, the Application Layer executes the
CodeGate Task by first activating the narrow-area image capture
mode in the Multi-Mode Image Formation and Detection Subsystem 13
(i.e. by enabling a few middle rows of pixels in the CMOS sensor
array 22), and then acquiring/capturing a narrow image at the center
of the FOV of the Bar Code Reader. CodeGate Task then performs image
processing operations on the captured narrow-area image using No-Finder
Module which has been enabled by the selected Programmable Mode
of System Operation No. 12. If the image processing method results
in a successful read of a bar code symbol, then the Codegate Task
saves the decoded symbol character data in the Codegate Data Buffer;
and if not, then the task clears the Codegate Data Buffer, and then
returns to the main block of the Task where image acquisition reoccurs.
[0331] As shown in FIG. 13F, when the user pulls the trigger switch
2C on the bar code reader while the Code Task is executing, the
trigger switch driver in the OS Layer automatically wakes up the
Input/Output Manager at the System Core Layer. As shown in FIG.
13G, the Input/Output Manager, in response to being woken up by
the trigger device driver, posts the SCORE_TRIGGER_ON event to the
Events Dispatcher also in the System Core Layer. As shown in FIG.
13H, the Events Dispatcher then passes on the SCORE_TRIGGER_ON event
to the Application Events Manager at the Application Layer. As shown
in FIG. 13I, the Application Events Manager responds to the SCORE_TRIGGER_ON
event by invoking a handling routine (Trigger On Event) within the
Task Manager at the System Core Layer. As shown the flow chart of
FIG. 13I, the routine determines whether the Presentation Mode (i.e.
Programmed Mode of System Operation No. 10) has been enabled, and
if so, then the routine exits. If the routine determines that the
Presentation Mode (i.e. Programmed Mode of System Operation No.
10) has not been enabled, then it determines whether the CodeGate
Task is running, and if not, then, executes the Main Task described
in FIG. 13J. If the routine determines that the CodeGate Task is
running, then it first cancels the CodeGate Task and then deactivates
the narrow-area illumination array 27 associated with the Multi-Mode
Illumination Subsystem 14, and thereafter executes the Main Task.
[0332] As shown in FIG. 13J, the first step performed in the Main
Task by the Application Layer is to determine whether CodeGate Data
is currently available (i.e. stored in the CodeGate Data Buffer),
and if such data is available, then the Main Task directly executes
the Data Output Procedure described in FIG. 13K. However, if the
Main Task determines that no such data is currently available, then
it starts the Read TimeOut Timer, and then acquires a wide-area
image of the detected object, within the time frame permitted by
the Read Timeout Timer. Notably, this wide-area image acquisition
process involves carrying out the following operations, namely:
(i) first activating the wide-area illumination mode in the Multi-Mode
Illumination Subsystem 14 and the wide-area capture mode in the
CMOS image formation and detection module; (ii) determining whether
the object resides in the near-field or far-field portion of the
FOV (through object range measurement by the IR-based Object Presence
and Range Detection Subsystem 12); and (iii) then activating either
the near or far field wide-area illumination array to illuminate
either the object in either the near or far field portions of the
FOV using either the near-field illumination array 28 or the far-field
illumination array 29 (or possibly both 28 and 29 in special programmed
cases) at an intensity and duration determined by the automatic
light exposure measurement and control subsystem 15; while (iv)
sensing the spatial intensity of light imaged onto the CMOS image
sensing array 22 in accordance with the Global Exposure Control
Method of the present invention, described in detail hereinabove.
Then the Main Task performs image processing operations on the captured
image using either the Manual, ROI-Specific or Automatic Modes of
operation, although it is understood that other image-processing
based reading methods taught herein, such as Automatic or OmniScan,
can be used depending on which Programmed Mode of System Operation
has been selected by the end user for the Imaging-Based Bar Code
Symbol Reader of the present invention. Notably, in the illustrative
embodiment shown in FIG. 13J, the time duration of each image acquisition/processing
frame is set by the Start Read Timeout Timer and Stop Read Timeout
Timer blocks shown therein, and that within the Programmed Mode
of System Operation No. 12, the Main Task will support repeated
(i.e. multiple) attempts to read a single bar code symbol so long
as the trigger switch 2C is manually depressed by the operator and
a single bar code has not yet been read. Then upon successfully
reading a (single) bar code symbol, the Main Task will then execute
the Data Output Procedure. Notably, in other Programmed Modes of
System Operation, in which a single attempt at reading a bar code
symbol is enabled, the Main Task will be modified accordingly to
support such system behavior. In such a case, an alternatively named
Main Task (e.g. Main Task No. 2) would be executed to enable the
required system behavior during run-time.
[0333] It should also be pointed out at this juncture, that it
is possible to enable and utilize several of different kinds of
symbol reading methods during the Main Task, and to apply particular
reading methods based on the computational results obtained while
processing the narrow-area image during the CodeGate Task, and/or
while preprocessing of the captured wide-area image during one of
the image acquiring/processing frames or cycles running in the Main
Task. The main point to be made here is that the selection and application
of image-processing based bar code reading methods will preferably
occur through the selective activation of the different modes available
within the multi-mode image-processing based bar code symbol reading
Subsystem 17, in response to information learned about the graphical
intelligence represented within the structure of the captured image,
and that such dynamic should occur in accordance with principles
of dynamic adaptive learning commonly used in advanced image processing
systems, speech understanding systems, and alike. This general approach
is in marked contrast with the approaches used in prior art Imaging-Based
Bar Code Symbol Readers, wherein permitted methods of bar code reading
are pre-selected based on statically defined modes selected by the
end user, and not in response to detected conditions discovered
in captured images on a real-time basis.
[0334] As shown in FIG. 13K, the first step carried out by the
Data Output Procedure, called in the Main Task, involves determining
whether the symbol character data generated by the Main Task is
for programming the bar code reader or not. If the data is not for
programming the Bar Code Symbol Reader, then the Data Output Procedure
sends the data out according to the bar code reader system configuration,
and then generates the appropriate visual and audio indication to
the operator, and then exits the procedure. If the data is for programming
the Bar Code Symbol Reader, then the Data Output Procedure sets
the appropriate elements of the bar code reader configuration (file)
structure, and then saves the Bar Code Reader Configuration Parameters
in non-volatile RAM (i.e. NOVRAM). The Data Output Procedure then
reconfigures the Bar Code Symbol Reader and then generates the appropriate
visual and audio indication to the operator, and then exits the
procedure. As shown in FIG. 13L, decoded data is sent from the Input/Output
Module at the System Core Layer to the Device Drivers within the
Linux OS Layer of the system.
[0335] Wide-Area Illumination Control Method for Use During the
Main Task System Control Routine so as To Illuminate Objects with
Wide-Area Illumination in a Manner which Substantially Reduces Specular-Type
Reflection at the CMOS Image Sensing Array of the Bar Code Symbol
Reader
[0336] Referring to FIGS. 13M1 through 13M3, the method of illuminating
objects without specular reflection, according to the present invention,
will now be described in detail. This control routine can be called
during the acquisition of wide-area image step in the Main Task
routine, shown in FIG. 13J.
[0337] As indicated at Step A in FIG. 13M1, the first step of the
illumination control method involves using the Automatic Light Exposure
Measurement And Illumination Control Subsystem 15 to measure the
ambient light level to which the CMOS image sensing array 22 is
exposed prior to commencing each illumination and imaging cycle
within the Bar Code Symbol Reading System
[0338] As indicated at Step B, the illumination control method
involves using the Automatic IR-based Object Presence and Range
Detection Subsystem 12 to measure the presence and range of the
object in either the near or far field portion of the field of view
(FOV) of the System.
[0339] As indicated at Step C, the illumination control method
involves using the detected range and the measured light exposure
level to drive both the upper and lower LED illumination subarrays
associated with either the near-field wide-area illumination array
28 or far-field wide-area illumination array 29.
[0340] As indicated at Step D, the illumination control method
involves capturing a wide-area image at the CMOS image sensing array
22 using the illumination field produced during Step C.
[0341] As indicated at Step E, the illumination control method
involves rapidly processing the captured wide-area image during
Step D to detect the occurrence of high spatial-intensity levels
in the captured wide-area image, indicative of a specular reflection
condition.
[0342] As indicated at Step F, the illumination control method
involves determining if a specular reflection condition is detected
in the processed wide-area image, and if so then driving only the
upper LED illumination subarray associated with either the near-field
or far-field wide-area illumination array. Also, if a specular reflection
condition is not detected in the processed wide-area image, then
the detected range and the measured light exposure level is used
to drive both the upper and lower LED subarrays associated with
either the near-field or far-field wide-area illumination array.
[0343] As indicated at Step G, the illumination control method
involves capturing a wide-area image at the CMOS image sensing array
22 using the illumination field produced during Step F.
[0344] As indicated at Step H, the illumination control method
involves rapidly processing the captured wide-area image during
Step G to detect the occurrence of high spatial-intensity levels
in the captured wide-area image, indicative of a specular reflection
condition.
[0345] As indicated at Step I, the illumination control method
involves determining if a specular reflection condition is still
detected in the processed wide-area image, and if so, then drive
the other LED subarray associated with either the near-field or
far-field wide-area illumination array. If a specular reflection
condition is not detected in the processed wide-area image, then
the detected Range and the measured Light Exposure Level is used
to drive the same LED illumination subarray (as in Step C) associated
with either the near-field wide-area illumination array 28 or far
field wide-area illumination array 29.
[0346] As indicated at Step J, the illumination control method
involves capturing a wide-area image at the CMOS image sensing array
using the illumination field produced during Step I.
[0347] As indicated at Step K, the illumination control method
involves rapidly processing the captured wide-area image during
Step J to detect the absence of high spatial-intensity levels in
the captured wide-area image, confirming the elimination of the
earlier detected specular reflection condition.
[0348] As indicated at Step L, the illumination control method
involves determining if no specular reflection condition is detected
in the processed wide-area image at Step K, and if not, then the
wide-area image is processed using the mode(s) selected for the
Multi-Mode Image-Processing Bar Code Reading Subsystem 17. If a
specular reflection condition is still detected in the processed
wide-area image, then the control process returns to Step A repeats
Steps A through K, as described above.
Specification of Symbologies and Modes Supported by the Multi-Mode
Bar Code Symbol Reading Subsystem Module Employed within the Hand-Supportable
Digital Image-Based Bar Code Reading Device of the Present Invention
[0349] FIG. 14 lists the various bar code symbologies supported
by the Multi-Mode Bar Code Symbol Reading Subsystem 17 employed
within the hand-supportable Digital Imaging-Based Bar Code Symbol
Reading Device of the present invention. As shown therein, these
bar code symbologies include: Code 128; Code 39; I2of5; Code93;
Codabar; UPC/EAN; Telepen; UK-Plessey; Trioptic; Matrix 2of5; Airline
2of5; Straight 2of5; MSI-Plessey; Code11; and PDF417.
Specification of the Various Modes of Operation in the Multi-Mode
Bar Code Symbol Reading Subsystem of the Present Invention
[0350] As shown in FIG. 15, the Multi-Mode Image-Processing Based
Bar Code Symbol Reading Subsystem 17 of the illustrative embodiment
supports five primary modes of operation, namely: the Automatic
Mode of Operation; the Manual Mode of Operation; the ROI-Specific
Mode of Operation; the No-Finder Mode of Operation; and Omniscan
Mode of Operation. As will be described in greater detail herein,
various combinations of these modes of operation can be used during
the lifecycle of the image-processing based bar code reading process
of the present invention.
[0351] FIG. 16 is a exemplary flow chart representation showing
the steps involved in setting up and cleaning up the software sub-Application
entitled "Multi-Mode Image-Processing Based Bar Code Symbol
Reading Subsystem 17", once called from either (i) the CodeGate
Task software module at the Block entitled READ BAR CODE(S) IN CAPTURED
NARROW-AREA IMAGE indicated in FIG. 13E, or (ii) the Main Task software
module at the Block entitled "READ BAR CODE(S) IN CAPTURED
WIDE-AREA IMAGE" indicated in FIG. 13J.
The Automatic Mode of Multi-Mode Bar Code Symbol Reading Subsystem
[0352] In its Automatic Mode of Operation, the Multi-Mode Bar Code
Symbol Reading Subsystem 17 is configured to automatically start
processing a captured frame of digital image data, prior to the
complete buffering thereof, so as to search for one or more bar
codes represented therein in an incremental manner, and to continue
searching until the entire image is processed.
[0353] This mode of image-based processing enables bar code locating
and reading when no prior knowledge about the location of, or the
orientation of, or the number of bar codes that may be present within
an image, is available. In this mode of operation, the Multi-Mode
Bar Code Symbol Reading Subsystem 17 starts processing the image
from the top-left corner and continues until it reaches the bottom-right
corner, reading any potential bar codes as it encounters them.
The Manual Mode of the Multi-Mode Bar Code Symbol Reading Subsystem
[0354] In its Manual Mode of Operation, the Multi-Mode Bar Code
Symbol Reading Subsystem 17 is configured to automatically process
a captured frame of digital image data, starting from the center
or sweep spot of the image at which the user would have aimed the
bar code reader, so as to search for (i.e. find) a at least one
bar code symbol represented therein. Unlike the Automatic Mode,
this is done by searching in a helical manner through frames or
blocks of extracted image feature data, and then marking the same
and image-processing the corresponding raw digital image data until
a bar code symbol is recognized/read within the captured frame of
image data.
[0355] This mode of image processing enables bar code locating
and reading when the maximum number of bar codes that could be present
within the image is known a priori and when portions of the primary
bar code have a high probability of spatial location close to the
center of the image. The Multi-Mode Bar Code Symbol Reading Subsystem
17 starts processing the image from the center, along rectangular
strips progressively further from the center and continues until
either the entire image has been processed or the programmed maximum
number of bar codes has been read.
The ROI-Specific Mode of the Multi-Mode Bar Code Symbol Reading
Subsystem
[0356] In its ROI-Specific Mode of Operation, the Multi-Mode Bar
Code Symbol Reading Subsystem 17 is configured to automatically
process a captured frame of digital image data, starting from the
region of interest (ROI) in the captured image, specified by coordinates
acquired during a previous mode of operation within the Multi-Mode
Bar Code Symbol Reading Subsystem 17. Unlike the Manual Mode, this
is done by analyzing the received ROI-specified coordinates, derived
during either a previous NoFinder Mode, Automatic Mode, or Omniscan
Mode of operation, and then immediately begins processing image
feature data, and image-processing the corresponding raw digital
image data until a bar code symbol is recognized/read within the
captured frame of image data. Thus, typically, the ROI-Specific
Mode is used in conjunction with other modes of the Multi-Mode Bar
Code Symbol Reading Subsystem 17.
[0357] This mode of image processing enables bar code locating
and reading when the maximum number of bar codes that could be present
within the image is known a priori and when portions of the primary
bar code have a high probability of spatial location close to specified
ROI in the image. The Multi-Mode Bar Code Symbol Reading Subsystem
starts processing the image from these initially specified image
coordinates, and then progressively further in a helical manner
from the ROI-specified region, and continues until either the entire
image has been processed or the programmed maximum number of bar
codes have been read.
The No-Finder Mode of the Multi-Mode Bar Code Symbol Reading Subsystem
[0358] In its No-Finder Mode of Operation, the Multi-Mode Bar Code
Symbol Reading Subsystem 17 is configured to automatically process
a captured narrow-area (linear) frame of digital image data, without
the feature extraction and marking operations used in the Automatic,
Manual and ROI-Specific Modes, so as to read a one or more bar code
symbols represented therein.
[0359] This mode enables bar code reading when it is known, a priori,
that the image contains at most one (1-dimensional) bar code symbol,
portions of which have a high likelihood of spatial location close
to the center of the image and when the bar code is known to be
oriented at zero degrees relative to the horizontal axis. Notably,
this is typically the case when the bar code reader is used in a
hand-held mode of operation, where the Bar Code Symbol Reader is
manually pointed at the bar code symbol to be read. In this mode,
the Multi-Mode Bar Code Symbol Reading Subsystem 17 starts at the
center of the image, skips all bar code location steps, and filters
the image at zero (0) degrees and 180 degrees relative to the horizontal
axis. Using the "bar-and-space-count" data generated by
the filtration step, it reads the potential bar code symbol.
The Omni-Scan Mode of the Multi-Mode Bar Code Reading Subsystem
[0360] In its Omniscan Mode of Operation, the Multi-Mode Bar Code
Symbol Reading Subsystem 17 is configured to automatically process
a captured frame of digital image data along any one or more predetermined
virtual scan line orientations, without feature extraction and marking
operations used in the Automatic, Manual and ROI-Specific Modes,
so as to read a single bar code symbol represented in the processed
image.
[0361] This mode enables bar code reading when it is known, a priori,
that the image contains at most one (1-dimensional) bar code, portions
of which have a high likelihood of spatial location close to the
center of the image but which could be oriented in any direction.
Multi-Mode Bar Code Symbol Reading Subsystem 17 starts at the center
of the image, skips all bar code location steps, and filters the
image at different start-pixel positions and at different scan-angles.
Using the bar-and-space-count data generated by the filtration step,
the Omniscan Mode reads the potential bar code symbol.
Specification of Multi-Mode Bar Code Symbol Reading Subsystem of
the Present Invention Operated During its Automatic Mode of Operation
[0362] As shown in FIG. 17A, the image-processing method carried
out by the Multi-Mode Bar Code Symbol Reading Subsystem during its
Automatic Mode of operation, comprises the following primary steps
of operation, namely: (1) the first stage of processing involves
searching for (i.e. finding) regions of interest (ROIs) by processing
a low resolution image of a captured frame of high-resolution image
data, partitioning the low-resolution image into N.times.N blocks,
creating a feature vector (Fv) for each block using spatial-derivative
based image processing techniques, marking ROIs by examining the
feature vectors for regions of high-modulation, (2) the second stage
of processing involves calculating bar code orientation, and marking
the four corners of a bar code as a ROI, and (3) the third stage
of processing involves reading any bar code symbols represented
within the ROI by traversing the bar code image data, updating the
feature vectors, examining the zero-crossings of filtered image
data, creating bar and space patterns, and decoding the bar and
space patterns using conventional decoding algorithms.
[0363] As will be described hereinbelow, these three (3) stages
of image processing involved in the Automatic Mode of operation
can be sub-divided into four major processing blocks (i.e. modules),
namely: the Tracker Module 100, the Finder Module 101, the Marker
Module 102, and the Decoder Module 103, which are shown in FIG.
2A2 and described in detail below. When the Automatic Mode of the
Multi-Mode Bar Code Symbol Reading Subsystem 17 is invoked, these
four processing blocks (i.e. modules) are executed, sequentially,
and optionally incrementally so that a rectangular sub-region of
the entire image can be processed per invocation.
First Stage of Image-Based Processing within the Multi-Mode Bar
Code Symbol Reading Subsystem During its Automatic Mode of Operation
[0364] During its Automatic Mode of operation, the first stage
of processing in the Multi-Mode Bar Code Symbol Reading Subsystem
17 comprises: (i) searching for (i.e. finding) regions of interest
(ROIs) by processing a low resolution image of a captured frame
of high-resolution image data as shown in FIG. 18A; (ii) partitioning
the low-resolution image of the package label into N.times.N blocks
as shown in FIG. 18B; (iii) creating a feature vector for each block
of low-resolution image data as shown in FIG. 18C using gradient
vectors, edge density measures, the number of parallel edge vectors,
centroids of edgels, intensity variance, and the histogram of intensities
captured from the low-resolution image; (iv) examining the feature
vectors for regions for parallel lines by detection of high modulation,
high edge density, large number of parallel edge vectors and large
intensity variance (using spatial-derivative based image processing
techniques) as shown in FIG. 18D; and (v) marking ROIs. In general,
this stage of processing is started before all lines of the full
digital image data frame are buffered in memory, and typically only
requires the number of rows in a given (first) feature block to
be buffered in memory before the reading process can begin.
Detailed Specification of the Tracker Module
[0365] As indicated at Blocks A, B, C, C1 and XX in FIG. 17B, the
first invocation of the Tracker Module 100 resets the Finder Module
101, Marker Module 102, and Decoder Module 103 sub-components to
their initial state (as Block A); it resets the feature vector array
Fv (at Block D) and the number of Regions of Interest (ROI). All
subsequent invocations set the maximum processing line number of
each of the three blocks to the current y-dimension of the image.
The Tracker Module invokes an optional callback function (Pause
Checker) to facilitate aborting or pausing Multi-Mode Bar Code Symbol
Reading Subsystem 17 or to change parameters on the fly.
Detailed Specification of the Finder Module
[0366] As indicated at Blocks D through Y in FIG. 17B, the Finder
Module 101 (processing block) sub-divides the image into N.times.N
blocks, each of which has a feature vector array (Fv) element associated
with it. An Fv element contains a set of numbers that identify the
strong possibility of the presence of parallel lines within that
image block. As indicated at Blocks D through Y, the Finder Module
101 processes the image at a lower spatial resolution; it processes
every n.sup.th line and every n.sup.th pixel within each of the
selected lines thereby performing calculations on the original image
down-sampled-by-n. For each selected line it calculates: I y _ =
n .times. x = 1 N x .times. I .function. ( x , y ) N x ( 1 ) where
I(x, y)=gray value at pixel location (x, y) and
[0367] N.sub.x=x-dimension of the supplied (sub)image
[0368] If I.sub.y exceeds a programmable "background threshold",
the image line y is declared a foreground line and is processed
further by the Finder Module. A pixel is declared as a background
pixel if its gray value is below a certain threshold. The Finder
Module starts from the left-most pixel and traverses right on the
foreground line, finds at Block G the first pixel whose intensity
(gray value) exceeds the programmable background threshold and marks
it as the left-edge (x.sub.1) of the line. At Block H, the Finder
Module then starts from the right-most pixel and traversing leftward
on the foreground line determines the right-edge (x.sub.r) using
the same method. For foreground line y the Finder Module calculates
at Block I: I'.sub.1(x,y)=|I(x+1,y)-I(x-1,y)|+|I(x,y+1)-I(x,y-1)|,
where x.sub.1.ltoreq.x.ltoreq.x.sub.r (2) If I'.sub.1(x, y) exceeds
a threshold at Block J, the Finder Module marks pixel (x,y) as an
edge element or edgel.
[0369] In order to find the direction and magnitude of the edge-vector
corresponding to edgel (x,y), the Finder Module calculates at Block
K: I 0 ' .function. ( x , y ) = w 1 0 .times. I .function. ( x -
1 , y - 1 ) + w 2 0 .times. I .function. ( x , y - 1 ) + w 3 0 .times.
I .function. ( x + 1 , y - 1 ) + w 4 0 .times. I .function. ( x
- 1 , y ) + w 5 0 .times. I .function. ( x , y ) + w 6 0 .times.
I .function. ( x + 1 , y ) + w 7 0 .times. I .function. ( x - 1
, y + 2 ) + w 8 0 .times. I .function. ( x , y + 1 ) + w 9 0 .times.
I .function. ( x + 1 , y + 1 ) ( 3 ) I 45 ' .function. ( x , y )
= w 1 45 .times. I .function. ( x - 1 , y - 1 ) + w 2 45 .times.
I .function. ( x , y - 1 ) + w 3 45 .times. I .function. ( x + 1
, y - 1 ) + w 4 45 .times. I .function. ( x - 1 , y ) + w 5 45 .times.
I .function. ( x , y ) + w 6 45 .times. I .function. ( x + 1 , y
) + w 7 45 .times. I .function. ( x - 1 , y + 2 ) + w 8 45 .times.
I .function. ( x , y + 1 ) + w 9 45 .times. I .function. ( x + 1
, y + 1 ) ( 4 ) I 90 ' .function. ( x , y ) = w 1 90 .times. I .function.
( x - 1 , y - 1 ) + w 2 90 .times. I .function. ( x , y - 1 ) +
w 3 90 .times. I .function. ( x + 1 , y - 1 ) + w 4 90 .times. I
.function. ( x - 1 , y ) + w 5 90 .times. I .function. ( x , y )
+ w 6 90 .times. I .function. ( x + 1 , y ) + w 7 90 .times. I .function.
( x - 1 , y + 2 ) + w 8 90 .times. I .function. ( x , y + 1 ) +
w 9 90 .times. I .function. ( x + 1 , y + 1 ) ( 5 ) I 135 ' .function.
( x , y ) = w 1 135 .times. I .function. ( x - 1 , y - 1 ) + w 2
135 .times. I .function. ( x , y - 1 ) + w 3 135 .times. I .function.
( x + 1 , y - 1 ) + w 4 135 .times. I .function. ( x - 1 , y ) +
w 5 135 .times. I .function. ( x , y ) + w 6 135 .times. I .function.
( x + 1 , y ) + w 7 135 .times. I .function. ( x - 1 , y + 2 ) +
w 8 135 .times. I .function. ( x , y + 1 ) + w 9 135 .times. I .function.
( x + 1 , y + 1 ) ( 6 ) where the coefficients w.sub.i.sup.0, w.sub.i.sup.45,
w.sub.i.sup.90, w.sub.i.sup.135 are given by the operators: w 0
= - 1 0 1 - 2 0 2 - 1 0 1 .times. w 45 = - 2 - 1 0 - 1 0 1 0 1 2
.times. w 90 = - 1 - 2 - 1 0 0 0 1 2 1 .times. w 135 = 0 - 1 - 2
1 0 - 1 2 1 0 At Block M, the Finder Module updates the Fv block
that edgel (x,y) belongs to with: Edge strength: I fv i ' = j =
1 n .times. I ij ' ( 7 ) [0370] where I'.sub.ij=edge strength of
edgel j, and [0371] n=number of edgels inside Fv block i Edge direction:
A fv i .function. ( z ) = j = 1 n .times. A j , .times. where .times.
.times. A j = { 1 , j = k , k .di-elect cons. [ 0 , 3 ] 0 .times.
.times. I z 1 ' .gtoreq. I z 2 ' .gtoreq. I z 3 ' .gtoreq. I z 4
' , z i = 45 * ( k + i - 1 ) ( 8 ) Centroid of edgels: x _ fv i
= j = 1 n .times. x j n , y _ fv i = j = 1 n .times. y j n ( 9 )
[0372] where (x.sub.j, y.sub.j) are the coordinates of the edgels
Cumulative histogram: H fv i .function. ( z ) = j = 1 n .times.
H j , .times. where .times. .times. H j = { 1 , I .function. ( x
, y ) .ltoreq. z 0 ( 10 )
[0373] At Block N, the Finder Module goes through all the lines
of the current image section and populates the Fv array using the
above-mentioned features. At Blocks O through U, the Finder Module
checks to see if all lines have been processed.
[0374] At Block V, the Finder Module then examines each Fv array
element for features that strongly point to the presence of parallel
lines within the Fv block. At Block W, an interesting Fv is declared
as part of a Region of Interest (ROI) when the number of edgels
exceeds a threshold, at least one of the edgel direction array elements
exceeds a threshold value, and
m-n>C, where H.sub.fv.sub.i(m)>.alpha.N,H.sub.fv.sub.i(n)>(1-.alpha.)N,
C=Contrast-threshold (11) .alpha..epsilon.(0,1) N=total number of
pixels in image block corresponding to feature vector array Fv Notably,
at Blocks C, E, and T, the Finder Module invokes the Pause Checker
callback function to let the scanning application take control.
Second Stage of Image-Based Processing within the Multi-Mode Bar
Code Symbol Reading Subsystem During its Automatic Mode of Operation
[0375] During its Automatic Mode of Operation, the second stage
of processing in the Multi-Mode Bar Code Symbol Reading Subsystem
17 involves (ii) calculating bar code orientation by analyzing the
feature vectors for parallel lines, and (ii) marking the four corners
of a bar code as a ROI, in terms of x.y coordinates.
[0376] FIGS. 18E and 18F illustrate calculating bar code orientation,
during the second marking stage of processing within the Multi-Mode
Bar Code Symbol Reading Subsystem 17 during its Automatic Mode of
operation, wherein within each feature vector block, the scan line
data representing the bar code is traversed (i.e. sliced) at different
angles, the slices are matched with each other based on "least
mean square error", and the correct orientation is determined
to be that angle which matches the mean square error sense through
every slice of the bar code.
[0377] FIG. 18G illustrates the marking of the four corners of
the detected bar code symbol, during the second marking stage of
processing within the Multi-Mode Bar Code Symbol Reading Subsystem
17 during its Automatic Mode of operation. During this stage of
processing, such marking operations are performed on the full high-resolution
image of the parcel, the bar code is traversed in either direction
starting from the center of the block, the extent of modulation
is detected using the intensity variance, and the x,y coordinates
(pixels) of the four corners of the bar code are detected starting
from 1 and 2 and moving perpendicular to the bar code orientation,
so as to ultimately define the ROI by the detected four corners
of the bar code symbol within the high-resolution image.
Detailed Specification of the Marker Module
[0378] Within the Multi-Mode Bar Code Symbol Reading Subsystem
17 shown in FIG. 2A2, the Marker Module as indicated at Blocks Z
through KK, in FIG. 17B, takes over from the Finder Module and examines
each ROI to determine the complete extent of the ROI. The Finder
Module then checks the location of the centroid of the ROI and compares
it to the line number of the accumulated images in memory. y.sub.roi.sub.i+L>N.sub.y
(12) where
[0379] y.sub.roi.sub.i=y coordinate of the centroid of ROI.sub.i
[0380] L=Maximum length (in pixels) of any bar code presented to
Multi-Mode Bar Code Symbol Reading Subsystem
[0381] N.sub.y=y-dimension of cumulative image
[0382] If inequality (12) holds, then the Marker Module postpones
calculations for this ROI until the y-dimension of the image is
such that inequality does not hold. When the Marker Module continues
to process the ROI, it first determines the orientation of the parallel
lines that could potentially be part of a bar code, by calculating:
.theta. = .times. ( 225 - .times. tan - 1 ( .times. I 135 ' I 45
' ) ) .times. .times. mod ( .times. 180 ) , .times. I 0 ' .gtoreq.
.times. I 45 ' , .times. I 0 ' .gtoreq. .times. I 45 ' , .times.
I 0 ' .gtoreq. .times. I 135 ' .times. .times. .times. .theta. =
( tan - 1 .function. ( I 90 ' I 0 ' ) ) .times. mod .function. (
180 ) , I 45 ' .gtoreq. I 0 ' , I 45 ' .gtoreq. I 90 ' , I 45 '
.gtoreq. I 135 ' .times. .times. .theta. = ( 45 + tan - 1 .function.
( I 135 ' I 45 ' ) ) .times. mod .function. ( 180 ) , I 90 ' .gtoreq.
I 45 ' , I 90 ' .gtoreq. I 0 ' , I 90 ' .gtoreq. I 135 ' .times.
.times. .theta. = ( 180 - tan - 1 .function. ( I 90 ' I 0 ' ) )
.times. mod .function. ( 180 ) .times. I 135 ' .gtoreq. I 0 ' ,
I 135 ' .gtoreq. I 90 ' , I 135 ' .gtoreq. I 45 ' ( 13 ) .function.
[ x j + 1 y j + 1 ] = [ x j y j ] - [ cos .times. .times. .beta.
sin .times. .times. .beta. ] ( 14 ) .function. [ x j ' y j ' ] =
[ x j y j ] - n i .function. [ - sin .times. .times. .beta. cos
.times. .times. .beta. ] ( 15 )
[0383] The angle .theta. that yields the minimum E(.beta.), is
assumed to be a close approximation of the actual orientation angle
of the parallel lines.
[0384] Having calculated the correct orientation of the parallel
lines, the Marker Module calculates the narrowest and the widest
width of the parallel lines in the neighborhood of the ROI by traversing
(i.e. scanning) the image in the direction of orientation of the
lines as well as at 180 degrees to it (e.g. using a spot size window
of say N.times.N pixels (e.g. where 1<N<10). It should be
noted that all angle measurements are clockwise relative to the
horizontal axis. Equation (14) specifies the traversal equation
with .beta.=.theta.,.theta.+180. Details of the method used to calculate
the widths of the lines are explained at length in the Decoder Module
section.
[0385] The Marker Module uses the widths of the narrowest and widest
elements to determine a pixel count (n) that closely approximates
the minimum quiet-zone allowable for any bar code symbology. It
then traverses the image again using equation (14) and calculates:
m i = j = i i + n .times. I .function. ( x j , y j ) n .times. .times.
v i = j = i i + n .times. I .function. ( x j , y j ) - m i n - 1
.times. .times. IV i = v i m i 2 ( 16 ) where m.sub.i=mean of the
set of n pixels starting at pixel i
[0386] v.sub.i=variance of the set of n pixels starting at pixel
I
[0387] If IV.sub.i is less than a threshold, then the Marker Module
makes the assumption that the group of parallel lines end at pixel
i (similarly for the .theta.+180 direction). Starting from pixel
i and traversing the image using (15) and a spot size window of
say N.times.N pixels (e.g. where 1<N<10), and performing similar
calculations as in equation (16) the four corners that approximate
the quadrilateral bound of the potential bar code are determined.
A pictorial representation of the above-mentioned method can be
found in the figure entitled "Step 6: Mark ROIs: Mark four
corners of bar code.
[0388] The Marker Module then marks all the Fv blocks that encompass
the quadrilateral bound of the potential bar code, with the current
ROI identifier; if there already exists one or more ROIs with different
identifiers, the Marker Module picks that ROI that completely encompasses
the others. The old ROIs are kept only if they are not completely
enclosed within the current ROI.
[0389] The Marker Module also frequently invokes the Pause Checker
to let the bar code reading Application (running) take over control.
Third Stage of Image-Based Processing within the Multi-Mode Bar
Code Symbol Reading Subsystem During its Automatic Mode of Operation
[0390] The third stage of processing involves reading any bar code
symbols represented within the ROI by traversing the bar code and
updating the feature vectors, examining the zero-crossings of filtered
images, creating bar and space patterns, and decoding the bar and
space patterns
[0391] FIG. 18H shows updating the feature vectors during the third
stage of processing within the Multi-Mode Bar Code Symbol Reading
Subsystem during its Automatic Mode of operation. During this stage
of processing, the histogram component of the feature vector Fv
is updated while traversing the bar code (using a spot size window
of say N.times.N pixels (e.g. where 1<N<10), the estimate
of the black-to-white transition is calculated, and an estimate
of narrow and wide elements of the bar code are also calculated.
[0392] FIG. 18I illustrates the search for zero crossings during
the third stage of processing within the Multi-Mode Bar Code Symbol
Reading Subsystem 17 during its Automatic Mode of operation. During
this stage of processing, the high-resolution bar code image is
median filtered in a direction perpendicular to bar code orientation,
the second derivative zero crossings define edge crossings, the
zero-crossing data is used only for detecting edge transitions,
and the Black/White transition estimates are used to put upper and
lower bounds to bar and space grey levels, as graphically illustrated.
[0393] FIG. 18J illustrates creating a bar and space pattern during
the third stage of processing within the Multi-Mode Bar Code Symbol
Reading Subsystem during its Automatic Mode of operation. During
this stage of processing, the edge transition is modeled as a ramp
function, the edge transition is assumed to be 1 pixel wide, the
edge transition location is determined at the subpixel level, and
the bar and space counts are gathered using edge transition data;
[0394] FIG. 18K illustrates generating the decode bar and space
pattern during the third stage of processing within the Multi-Mode
Bar Code Symbol Reading Subsystem during its Automatic Mode of operation.
During this stage of operation, the bar and space data is framed
with borders, and the bar and space data is decoded using existing
laser scanning bar code decoding algorithms.
Detailed Specification of the Decoder Module
[0395] As indicated in at Blocks LL through AAA in 17B, the Decoder
Module takes over from the Marker Module and examines each ROI previously
defined by the Marker Module. For each ROI, the Decoder Module uses
the quadrilateral bound coordinates {x,y} to calculate the longer
(higher) extremity of the potential bar code (towards the possible
quiet-zones). The Decoder Module then computes the maximum number
of possible scan-lines as: T = D n ( 17 ) where D=length of the
longer extremity, and n=pixel-offset per scan-line.
[0396] Notably, the parameter n (i.e. pixel-offset per scan line)
represents how far the Decoder Module moves up its virtual scan
direction (parallel to the previous virtual scan direction) and
processes the image during each image processing cycle. As any captured
image will be corrupted by some degree of noise (and certainly greater
levels when a bar code symbol cannot be decoded), the Decoder Module
needs to perform its next processing cycle on a line of scan data
that is located as far away as possible from the previous line of
scan data which did not result in a successful decode, but at the
same time, the Decoder Module should exploit the inherent noise-immunity
features provided in many bar code symbologies. Thus, in accordance
with the present invention, the pixel-offset per scan line variable
n is not arbitrarily selected, as in most prior art systems, but
rather is determined by carefully (i) determining the maximum pixel
height (length) of the ROI under consideration, and (ii) dividing
this maximum pixel height of the ROI into a number of pixel-offset
distances proportional to the maximum pixel height of the ROI. In
the preferred embodiment, the number or sequence of scan lines into
which the ROI can be divided for subsequent cycles of image processing,
thus defining the pixel off-set per scan-line, is described by the
formula: f(m, n)=(2m-1)/2.sup.n-1, where n=1,2 . . . N. and 1>m>2.sup.n-1.
[0397] The Decoder Module traverses the potential bar code using
equation (14) and calculates approximations for the first and second
order derivatives: I i ' = j = - 1 1 .times. [ .times. w 1 .times.
I .function. ( x j - 1 , y j - 1 ) + w 2 .times. I .function. (
x j , y j - 1 ) + w 3 .times. I .function. ( x j + 1 , y j - 1 )
+ w 4 .times. I .function. ( x j - 1 , y j ) + w 5 .times. I .function.
( x j , y j ) + w 6 .times. I .function. ( x j + 1 , y j ) + w 7
.times. I .function. ( x j - 1 , y j + 1 ) + w 8 .times. I .function.
( x j , y j + 1 ) + w 9 .times. I .function. ( x j + 1 , y j + 1
) ] .times. .times. I i '' = I i + 1 ' - I i - 1 ' .times. .times.
where ( 18 ) w i = 0.776 0.000 - 0.776 1.000 0.000 - 1.000 .times.
.times. .times. .times. 0 < .theta. .ltoreq. 22 0.776 0.000 -
0.776 .times. .times. w i = 1.000 0.776 0.000 0.776 0.000 - 0.776
.times. .times. .times. .times. 0 < .theta. .ltoreq. 68 0.000
- 0.776 - 1.000 .times. .times. w i = 0.776 1.000 0.776 0.000 0.000
0.000 .times. .times. .times. .times. 0 < .theta. .ltoreq. 113
- 0.776 - 1.000 - 0.776 .times. .times. w i = 0.000 0.776 1.000
- 0.776 0.000 0.776 .times. .times. .times. .times. 0 < .theta.
.ltoreq. 158 - 1.000 - 0.776 0.000 .times. .times. w i = - 0.776
0.000 0.776 - 1.000 0.000 1.000 .times. .times. .times. .times.
158 < .theta. < 180 - 0.776 0.000 0.776 ( 19 ) and (x.sub.j,
y.sub.j) are related by equation (15). The Decoder Module examines
the zero crossings of I''.sub.i and if I''.sub.iI''.sub.i+1>0,
and I''.sub.i+1>0, and I'.sub.i<-T (20) where T=minimum derivative
magnitude threshold, then the Decoder Module concludes that a "space
to bar transition" has occurred. If: I''.sub.iI''.sub.i+1<0,
and I''.sub.i+1<0, and I'.sub.i>T (21) then, the Decoder Module
concludes that a "bar to space transition" has occurred.
[0398] The Decoder Module takes the difference in pixel position
of adjacent bar/space transitions and adds it to the interpolated
mid-point of the bar-space/space-bar transition (found using I''.sub.i)
to determine the width of each element of the potential bar code.
This is the same method used by the Marker Module to calculate the
widths of the narrowest and widest parallel lines.
[0399] Having calculated the "bar-and-space-count" data
for each scan-line, the Decoder Module invokes the different (and
separately enabled) symbology-decoders supported within the Imaging-Based
Bar Code Symbol Reader, as indicated at FIG. 18K. Each symbology
decoder, whether 1-dimensional or certain 2-dimensional symbologies
(like PDF417), detects the presence of the correct number of bars
and spaces and also the correct start/stop pattern before attempting
to decode the potential bar code symbol.
[0400] If the Decoder Module decodes using the current "scan-line
data", then it skips all other scan-lines. If the Decoder Module
detects a stacked symbology, then it continues to gather more scan-line-data.
If decoding fails, then the Decoder Module adjusts the scan-line
angles (bar code-orientation angle) progressively and repeats the
process. The Decoder Module, in the process of collecting scan-line-data,
also correlates the bar-and-space-data from one scan-line with that
of the adjacent scan-lines in order to read through damaged or poorly
presented bar codes. For every bar code that is decoded by the Decoder
Module, a callback function is invoked to save the decoded result.
The Decoder Module calls the Pause Checker callback function frequently
to let the scanning application take control.
[0401] In its Automatic Mode, the Multi-Mode Bar Code Symbol Reading
Subsystem 17 repeats this entire process for the entire image, and
optionally for progressively acquired images.
Specification of Multi-Mode Bar Code Symbol Reading Subsystem of
the Present Invention Operated During its Manual Mode of Operation
[0402] FIG. 19A illustrates the steps involved in the process carried
out by the Multi-Mode Bar Code Symbol Reading Subsystem during its
Manual Mode of operation. During this manual mode of operation,
the first stage of processing involves searching for and finding
regions of interest (ROIs) by processing a low resolution image
of a captured frame of high-resolution image data, partitioning
the low-resolution image into N.times.N blocks, and creating a feature
vector for the middle block using spatial-derivative based image
processing techniques. Then, the second stage of processing involves
marking ROIs by examining the feature vectors for regions of high-modulation
and returning to the first stage to create feature vectors for other
blocks surrounding the middle block (in a helical manner), calculating
bar code orientation and eventually marking the four corners of
a bar code as a ROI, and (3) the third stage of processing involves
reading any bar code symbols represented within the ROI by traversing
the bar code and updating the feature vectors, examining the zero-crossings
of filtered images, creating bar and space patterns, and decoding
the bar and space patterns.
[0403] Like in the Automatic Mode, these three (3) stages of image
processing in the manual mode of operation can be sub-divided into
four major processing blocks (i.e. modules), namely: the Tracker
Module, the Finder Module, the Marker Module, and the Decoder Module,
which have been described in great detail above. When the Manual
Mode of the Multi-Mode Bar Code Symbol Reading Subsystem 17 is invoked,
these four processing blocks (i.e. modules) are executed sequentially,
and optionally incrementally so that a rectangular sub-region of
the entire image can be processed per invocation.
[0404] FIG. 19B illustrates the steps involved in the decode process
carried out by the Multi-Mode Bar Code Symbol Reading Subsystem
17 during its Manual Mode of operation. As indicated at Block A,
the Main Task or CodeGate Task in Application Layer invokes the
Tracker Module to find the center coordinates of the center block
of captured image data, to which the center feature vector will
be associated. This central block of image data will be associated
with image pixels located along the central portion of the image
frame captured by the Imaging-Based Bar Code Symbol Reader. This
step involves the Tracker Module resetting the Finder Module, Marker
Module, and Decoder Module sub-components to their initial state;
it resets the feature vector array and the number of Regions of
Interest (ROI). While not indicated in the flow chart of FIG. 19B,
the Tracker Module invokes an optional callback function (Pause
Checker) at various location within the control flow to facilitate
aborting or pausing Multi-Mode Bar Code Symbol Reading Subsystem
17 or to change parameters on the fly.
[0405] As indicated at Block B in FIG. 19B, the Finder Module is
invoked and the captured image is subdivided into N.times.N blocks,
each of which has a feature vector (Fv) array element associated
with it. An Fv element contains a set of numbers that identify the
strong possibility of the presence of parallel lines within that
image block. As described hereinabove, the Finder Module processes
the image at a lower spatial resolution; namely, it processes every
n.sup.th line and every n.sup.th pixel within each of the selected
lines thereby performing calculations on the original image down-sampled-by-n.
For each selected line it calculates. At Block C, the Subsystem
17 determines if an ROI (bounding a complete bar code symbol) is
found, and if so, then invokes the Marker Module. Then at Block
E, the Subsystem 17 determines whether an ROI has been marked by
the Market Module, and if so, then the Decoder Module is invoked
and then the ROI processed. If a bar code symbol is read within
the ROI at Block G, then at Block H the Subsystem 17 determines
if the actual number of decode cycles equals the required number
of decode cycles. If so, then the Manual Mode of operation of the
Subsystem 17 is stopped, and the flow returns to the Application
Layer.
[0406] If at Block C in FIG. 19B the Subsystem 17 determines that
the ROI is not found, then the subsystem proceeds to Block I. If
the Subsystem determines that all feature vectors have not yet been
examined, then the Subsystem proceeds to Block J which advances
the analysis to the next feature vector closet to the center feature
vector, along the locus of a helical path through the image pixel
data set. Then, at Block B, the Subsystem reinvokes the Finder Module
to operate on this next feature vector.
[0407] If at Block G, the Subsystem determines that the Decoder
Module does not successfully decode a bar code symbol in the ROI,
then it advances to Block I and determines whether all feature vectors
have not been examined.
[0408] The Subsystem 17 operated in the mode of operation specified
by the flow chart of FIG. 19B until a single bar code symbol is
read within an ROI. Each instance of the Finder Module involves
the analysis of another block of pixel data (corresponding to another
feature vector) in effort to find an ROI containing a bar code symbol
which can be found at Block C and successfully decoded at Block
G. The sequential analysis of blocks of pixel data follows a helical
pattern about the center starting point, determined at Block A of
FIG. 19B. Notably, during the Manual Mode of Operation, the Subsystem
utilizes the image processing techniques described in connection
with the Automatic Mode of operation, above.
[0409] The primary advantage of the Manual Mode of operation over
the Automatic Mode of operation is that the Manual Mode is that,
when the user points the bar code reader at a bar code symbol to
be read, the bar code reader in the manual mode is more likely to
acquire an image and process the pixel data within a ROI containing
a bar code symbol is a very quick manner, in comparison with the
Automatic Mode which essentially scans and processes the entire
captured image starting to from upper left most block of captured
image data, ensuring a faster response time in hand-held bar code
reading applications, in particular.
Specification of the Multi-Mode Bar Code Symbol Reading Subsystem
of the Present Invention Operated During its NoFinder Mode of Operation
[0410] FIG. 20A illustrates that the image processing carried out
by the Multi-Mode Bar Code Symbol Reading Subsystem 17 during its
NoFinder Mode of operation involves essentially a single stage of
image processing, unlike the Automatic, Manual and ROI-Specific
Modes of operation. During this No-Finder Mode, Subsystem 17 does
not employ the Tracker Module, the Finder Module or the Marker Module
and instead only invokes the Decoder Module to (i) directly process
the narrow-area high-resolution image captured by the bar code reader,
one line of scan data at a time, starting from the middle thereof,
(ii) examine the zero-crossings of the filtered image, (iii) create
bar and space patterns therefrom, and then (iv) decode the bar and
space patterns using conventional decoding algorithms. If the reading
process is not successful, then the Subsystem 17 traverses another
line of scan data within the captured narrow-area image, starting
from a pixel offset n which is computed assuming a constant maximum
height of the ROI which is deemed to be the pixel height of the
captured narrow-area image.
[0411] FIG. 20B illustrates the steps involved in the image processing
method carried out by the Multi-Mode Bar Code Symbol Reading Subsystem
17 during its NoFinder Mode of operation. As indicated at Block
A in FIG. 20B, the Subsystem 17 first finds (i.e. calculates) the
center pixel in the captured narrow-area image. Then at Block B,
the Subsystem 17 invokes the Decode Module and configures the same
using the calculated center pixel. Within the Decode Module, sub-Blocks
B1 through B8 are then carried out as shown in FIG. 20A. As indicated
in Block B1, the Decoder Module, starting from the calculated center
point, scans the image horizontally and westward (using a spot-size
window of say N.times.N pixels (e.g. where 1<N<10), and then
processes the scanned image data to determine if a first border
in a bar code symbol is found. Notably, this virtual scanning process
is realized as a mathematical convolution of the spot-size window
and the pixel data in the image buffer. If a first border is found
at Block B2, then, once again starting from the calculated center
point, the Decoder Module at Block B3 scans the image horizontally
and eastward (using a spot size window of say N.times.N pixels (e.g.
where 1<N<10), and then at Block B4 processes the scanned
image data to determine if a second border in a bar code symbol
is found. If a second border is found at Block B4, then the Decoder
Module processes the captured image at Block B5. If, at Block B6,
the Decoder Module successfully reads a bar code symbol within the
scanned line of image data, then the Subsystem terminates the Decoder
Module and stops the NoFinder Mode of operation.
[0412] If at Block B2 in FIG. 20A the Decoder Module does not find
a first border of a bar code symbol, then it proceeds to Block B7
and determines if it has tried all possible scan lines within the
captured narrow-area image. If the Decoder Module has tried processing
all possible scan lines through the narrow-area image, then it proceeds
to the stop block and terminates the NoFinder Mode of operation.
If the Decoder Module has not tried processing all scan lines through
the captured narrow-area image, then it proceeds to Block B8, where
it advances to the next line of scan data in the captured narrow-area
image (i.e. by the offset pixel amount n), and then returns to Block
B1 where scanning and processing is resumed along the new scan line
(using a spot size window of say N.times.N pixels (e.g. where 1<N<10).
[0413] If at Block B4, the second bar code border is not found,
then the Decoder Module proceeds to Block B7 and determines whether
all scan lines through the captured image have been tried. If so,
then the Subsystem 17 terminates the Decoder Module and exits its
NoFinder Mode of operation. If all scan lines have not been tried
at this stage of the process, then the Decoder Module proceeds to
Block B8 and advances to the next line of scan data for processing,
as described hereinabove.
[0414] If at Block B6 in FIG. 20A the Decoder Module does not read
a bar code within the current line of scan data being processed,
then it proceeds to Block B7, where it determines if all lines of
scan data have been tried. If all lines of scan data have not been
tried, then at Block B8 the Decoder Module advances to the next
line of scan data in the captured narrow-area image (i.e. by the
offset pixel amount n), and then returns to Block B1 where scanning
and processing is resumed along the new scan line (using a spot
size window of say N.times.N pixels (e.g. where 1<N<10). If
at Block B7, the Decoder Module determines that all lines of scan
data have been tried, then the Decoder Module stops and terminates
its process. For every bar code that is decoded by the Decoder Module,
a callback function is invoked to save the decoded result. The Decoder
Module calls the Pause Checker callback function frequently to let
the car code symbol reading Application take control.
Specification of Multi-Mode Bar Code Symbol Reading Subsystem of
the Present Invention Operated During its OmniScan Mode of Operation
[0415] FIG. 21A illustrates that the image processing method carried
out by the Multi-Mode Bar Code Symbol Reading Subsystem during its
Omniscan Mode of operation involves essentially a single stage of
image processing, unlike the Automatic, Manual and ROI-Specific
Modes of operation. During this Omniscan Mode, the Decoder Module
does not employ the Tracker Module, the Finder Mode or the Marker
Module and instead directly processes the narrow-area high-resolution
image captured by the bar code reader, along a plurality of spaced
apart (e.g. 50 pixels) virtual scanning lines traversing through
the entire 2D frame of image data captured by the Subsystem 17.
During the OmniScan Mode of operation, the Decoder Module assumes
the imaged bar code symbol resides at the center of the captured
wide-area high-resolution image with about a 1:1 aspect ratio (e.g.
1'' tall.times.1'' wide). Based on these assumptions, the Subsystem
17 starts at first predetermined angular orientation (e.g. 0, 30,
60, 90, 120 or 150 degrees), and then: (i) directly processes the
high-resolution image along a set of parallel spaced-apart (e.g.
50 pixels) virtual scan lines line (using a spot size window of
say N.times.N pixels (e.g. where 1<N<10); (ii) examines the
zero-crossings along these virtual scan lines; (iii) creates bar
and space patterns therefrom; and then (iv) decode processes the
bar and space patterns. If image processing along the selected angular
orientation fails to read a bar code symbol, then the Subsystem
17 automatically reprocesses the high-resolution image along a different
set of parallel spaced-apart virtual scan lines oriented at a different
angle from the previously processed set of virtual scan lines (e.g.
0, 30, 60, 90, 120 or 150 degrees). This processing cycle continues
until a single bar code symbol is read within the processed image.
[0416] FIG. 21B illustrates the steps involved in the image processing
method carried out by the Multi-Mode Bar Code Symbol Subsystem 17
during its OmniScan Mode of operation. As indicated at Block A in
FIG. 21B, the Subsystem 17 first finds (i.e. calculates) the start
pixel and scan angle in the captured narrow-area image. Then at
Block B, the Subsystem 17 invokes the Decode Module and configures
the same using the calculated (i) start pixel and (ii) start scan
angle. Within the Decode Module, sub-Blocks B1 through B8 are then
carried out as shown in FIG. 21B. As indicated at Block B1, the
Decoder Module, starting from the calculated start point and start
angle, scans the image at the start angle and northwestwardly using
a spot-size window of say N.times.N pixels (e.g. where 1<N<10),
and then at Block B2 processes the scanned image data to determine
if a first border in a bar code symbol is found. Notably, this virtual
scanning process is realized as a mathematical convolution of the
spot-size window and the pixel data in the image buffer. If a first
border is found at Block B2, then, once again starting from the
calculated start point and start angle, the Decoder Module at Block
B3 scans the image at the start angle and southwestwardly using
a spot size window of say N.times.N pixels (e.g. where 1<N<10),
and then at Block B4 processes the scanned image data to determine
if a second border in a bar code symbol is found. If a second border
is found at Block B4, then the Decoder Module invokes the Decoder
Module described above at Block B5 and decode processes the scanned
image. If, at Block B6, the Decoder Module successfully reads a
bar code symbol within the scanned line of image data, then the
Subsystem 17 terminates the Decoder Module and stops the Omniscan
Mode of operation.
[0417] If at Block B2 in FIG. 21A the Decoder Module does not find
a first border of a bar code symbol, then it proceeds to Block B7
and determines if it has tried all possible scan lines at combinations
of start pixels and start angles within the captured narrow-area
image. If at Block B7 the Decoder Module has tried processing all
possible scan lines at start pixel and angle combinations through
the narrow-area image, then it proceeds to the "stop"
Block and terminates the Omniscan Mode of decoder operation. If
the Decoder Module has not tried processing all scan lines at all
start pixel and angle orientations through the captured narrow-area
image, then it proceeds to Block B8, where it advances to the next
line of scan data in the captured narrow-area image (i.e. by the
offset pixel amount n), and then returns to Block B1 where scanning
and processing is resumed along the new scan line (using a spot
size window of say N.times.N pixels (e.g. where 1<N<10).
[0418] If at Block B4, the second bar code border is not found,
then the Decoder Module proceeds to Block B7 and determines whether
all scan lines at all possible start pixels and angles (through
the captured image) have been tried. If so, then the Decode Module
terminates its process and exits the Omniscan Mode of operation.
If the scan lines at all start pixel and angle combinations have
not been tried at this stage of the process, then the Decoder Module
proceeds to Block B8 and advances the next start pixel and angle
for scan data image processing, and returns to Block B1 as described
hereinabove.
[0419] If at Block G in FIG. 21A the Decoder Module does not decode
a bar code within the current set of parallel lines of scan data
being processed, then it proceeds to Block I, where it advances
to the next set of parallel scan lines (at a different set of start
pixels and angle), and then returns to Block B where scanning and
processing is resumed along the new set of parallel scan lines (using
a spot size window of say N.times.N pixels (e.g. where 1<N<10).
For every bar code that is decoded by the Decoder Module, a callback
function is invoked to save the decoded result. The Decoder Module
calls the Pause Checker callback function frequently to let the
bar code reading Application take control.
Specification of Multi-Mode Bar Code Symbol Reading Subsystem of
the Present Invention Operated During its ROI-Specific Mode of Operation
[0420] FIG. 22A illustrates the steps involved in the image processing
method carried out by the Multi-Mode Bar Code Symbol Reading Subsystem
during its ROI-Specific Mode of operation. Notably, the ROI-Specific
Mode of operation is similar to the Manual Mode of operation, except
that it is used to automatically process a specified "region
of interest" (ROI) previously identified during the processing
of a captured image frame during a different mode of operation,
e.g. the NoFinder Mode of Operation or Omniscan Mode of Operation
[0421] As reflected in FIG. 22A, during this ROI-Specific Mode
of operation, the first stage of processing involves receiving region
of interest (ROI) coordinates {x,y} obtained during other modes
of operation (e.g. Omniscan Mode, Automatic Mode or NoFinder Mode--after
the occurrence of a failure to read), and re-partitioning the captured
low-resolution image (from the Omniscan Mode) into N.times.N blocks,
and instantiating a feature vector for the ROI-specified block(s)
using features imported from and collected during the Omniscan,
Automatic or No-Finder Module (and possibly utilizing additional
spatial-derivative based image processing techniques). The second
stage of processing involves marking additional ROIs by examining
the feature vectors for regions of high-modulation (about the originally
specified ROI) and returning to the first stage to create feature
vectors for other blocks surrounding the specified block (in a helical
manner), calculating bar code orientation and marking the four corners
of a bar code contained within a ROI to be decode processed. The
third stage of processing involves reading any bar code symbols
represented within the ROI by traversing the pixel data associated
with the bar code and updating the feature vectors, examining the
zero-crossings of filtered images, creating bar and space patterns,
and decoding the bar and space patterns using conventional bar code
decoding algorithms.
[0422] FIG. 22B illustrates the steps involved in the image processing
method carried out by the Multi-Mode Bar Code Symbol Reading Subsystem
during its ROI-Specific Mode of operation. As indicated at Block
A, the Decoder Module associated with either the Omniscan or NoFinder
Mode receives {x.y} coordinates for a specific ROI (in which at
least a portion of a bar code symbol is likely to exist) to which
an initial feature vector will be instantiated. Then at Block B,
the Finder Mode is invoked, and at Block C, the Finder Module determines
whether or not an ROI (containing a complete bar code symbol)) has
been found. If the Finder Module determines that a ROI-contained
bar code has been found, then the Finder Module invokes the Marker
Module, whereupon at Block E, the Marker Module determines whether
the ROI-contained bar code symbol has been marked by the Marker
Module. If so, then the Decoder Module is invoked and then the high-resolution
pixel data associated with the ROI is processed. If a bar code symbol
is read within the ROI at Block G, then at Block H the Decoder Module
determines if the actual number of decodes equals the required number
of decode cycles (i.e. set by the end user). If so, then the Manual
Mode of Operation is stopped, and the flow returns to the Application
Layer.
[0423] If at Block C in FIG. 22B the Finder Module determines that
an ROI (containing a complete bar code) is not found, then the Finder
Module proceeds to Block I. If the Finder Mode determines that all
feature vectors have not yet been examined, then the Finder Mode
proceeds to Block J which advances the analysis to the next feature
vector closet to the ROI-specified feature vector, along the locus
of a helical path through the image pixel data set. Then, at Block
B, the Finder Module reinvokes itself to operate on this next feature
vector.
[0424] If at Block G, the Decoder Module does not successfully
read a bar code symbol in the ROI, then it advances to Block I and
determines whether all feature vectors have not been examined. If
so, then the Decoder Module terminates the ROI-specific Mode of
operation. Typically, the Subsystem 17 continues in this mode of
operation until, for example, a single bar code symbol is read within
an ROI marked as containing a complete bar code symbol. Each instance
of the Finder Module involves the analysis of another block of pixel
data (corresponding to another feature vector) in effort to find
an ROI containing a complete bar code symbol, which can be found
at Block C and successfully read at Block G. The sequential analysis
of blocks of pixel data follows a helical pattern about the center
starting point, determined at Block A of FIG. 22B. Notably, during
the Manual Mode of Operation, the Subsystem utilizes the image processing
techniques described in connection with the Automatic Mode of Operation,
above.
Specification of Multi-Mode Bar Code Symbol Reading Subsystem of
the Present Invention Operated During its First Multi-Read (OmniScan/ROI-Specific)
Mode of Operation
[0425] FIG. 23 describes the operation of the Multi-Mode Bar Code
Symbol Reading Subsystem 17 when it is driven into its first multi-read
(e.g. Omniscan/ROI-Specific) mode of operation. In this first multi-read
mode of operation, the Subsystem 17 adaptively processes and reads
a captured high-resolution image in a high-speed manner, applying
adaptive learning techniques, taught herein.
[0426] For example, assume the multi-mode image-processing symbol
decoding subsystem is configured to operate in its first multi-read
(OmniScan/ROI-Specific) mode of operation, as shown in FIG. 23.
In this case, if during the Omniscan Mode of operation, code fragments
associated with a PDF417 bar code symbol are detected within a ROI
in a captured (narrow or wide) area image, but processing thereof
is unsuccessful, then the Multi-Mode Bar Code Symbol Reading Subsystem
17 will automatically (i) enter its ROI-Specific Mode of operation
described above, and then (ii) immediately commences processing
of the captured image at the ROI specified by ROI coordinates acquired
by feature vector analysis during the Omniscan Mode of operation.
In the illustrative embodiment, this switching of modes in the Subsystem
17 occurs within a single bar code symbol reading cycle, and involves
processing a captured image frame using at least two different modes
(i.e. methods) of image-processing based bar code reading, within
which potentially dozens of different bar code symbol decoding algorithms
are typically applied each decoding cycle.
[0427] One potential advantage of the Multi-Read (Omniscan/ROI-Specific)
Mode of operation, over the Manual Mode of operation, is that the
Multi-Read Mode offers an OmniScan Mode of operation to initially
and rapidly read 1D bar code symbologies, and various kinds of 2D
bar code symbologies whenever present in the captured image, and
whenever a PDF417 symbology is detected (through its code fragments),
the Multi-Mode Bar Code Symbol Reading Subsystem 17 can automatically
switch (on-the-fly) to its ROI-specific Mode of operation to immediately
process high-resolution image data at a specific ROI (at which there
is a high likelihood of a bar code symbol present).
Specification of Multi-Mode Bar Code Symbol Reading Subsystem of
the Present Invention Operated During its Second Multi-Read (No-Finder/ROI-Specific)
Mode of Operation
[0428] FIG. 24 illustrates the Multi-Mode Bar Code Symbol Reading
Subsystem 17 when it is driven into its second multi-read (No-Finder/ROI-Specific)
mode of operation so as to adaptively process and read a captured
high-resolution image, in a high-speed manner, by applying adaptive
learning techniques.
[0429] For example, assume the Multi-Mode Bar Code Symbol Reading
Subsystem 17 is configured to operate in its second multi-read (No-Finder/ROI-Specific)
mode when processing a wide-area image captured by the system, as
shown in FIG. 24. In this case, if during the NoFinder Mode of operation,
code fragments associated with a PDF417 bar code symbol are detected
within the captured wide-area image, but processing thereof is unsuccessful,
then the Subsystem 17 will automatically (i) enter its ROI-specific
mode of operation described above, and then (ii) immediately commence
processing of the captured wide-area image at a ROI specified by
y coordinates corresponding to the wide-area image processed during
the NoFinder Mode of operation. In the illustrative embodiment,
this switching of modes in the Image-Processing Bar Code Symbol
Reading Subsystem 17 occurs within a single bar code symbol reading
cycle, and involves processing a single captured image frame using
at least two different modes (i.e. methods) of image-processing
based bar code reading (i.e. NoFinder Mode and ROI-Specific), within
each of which potentially dozens of different bar code symbol decoding
algorithms are typically applied during each decoding cycle.
[0430] Alternatively, assume the subsystem 17 is configured to
operate in its "multi-read mode" when processing first
a narrow-area image and then a wide-area image captured by the system.
In this case, if during the NoFinder Mode of operation, code fragments
associated with a PDF417 bar code symbol are detected within the
captured narrow-area image, but decode processing thereof is unsuccessful,
then the Subsystem 17 will automatically (i) enter its ROI-specific
mode of operation described above, as a wide-area image is automatically
captured by the system, and then (ii) immediately commence processing
the captured wide-area image at a ROI specified by y coordinates
corresponding to the narrow-area image processed during the NoFinder
Mode of operation. In the illustrative embodiment, this switching
of modes in the Subsystem 17 occurs within a single bar code symbol
reading cycle, and involves processing two captured image frames
using at least two different modes (i.e. methods) of image-processing
based bar code reading (i.e. NoFinder Mode and ROI-Specific), within
each of which potentially dozens of different bar code symbol decoding
algorithms are typically applied during each decoding cycle.
[0431] One potential advantage of the "No-Finder/ROI-Specific"
Multi-Mode operation over the Manual Mode of operation, regardless
of its method of implementation, is that the No-Finder Mode can
rapidly read 1D bar code symbologies whenever they are presented
to the bar code symbol reader, and then whenever a 2D (e.g. PDF417)
symbology is encountered, the bar code symbol reader can automatically
switch its method of reading to the ROI-specific Mode use features
collected from a narrow (or wide) area image processed during the
No-Finder Mode, so as to immediately process a specific ROI in a
captured wide-area image frame, at which there is a high likelihood
of a bar code symbol present, and to do so in a highly targeted
manner.
Specification of Multi-Mode Bar Code Symbol Reading Subsystem of
the Present Invention Operated During its Third Multi-Read (No-Finder/OmniScan/ROI-Specific)
Mode of Operation
[0432] FIG. 25 illustrates the Multi-Mode Bar Code Symbol Reading
Subsystem 17 when it is driven into its third multi-read (No-Finder/OmniScan/ROI-Specific)
mode of operation so as to adaptively process and read a captured
high-resolution image, in a high-speed manner, by applying adaptive
learning techniques.
[0433] For example, assume the Subsystem 17 is configured to operate
in its "multi-read mode" when processing a wide-area image
captured by the system, as shown in FIG. 25. In this case, if during
the NoFinder Mode of operation, code fragments associated with a
PDF417 bar code symbol are detected within the captured narrow-area
image, but decode processing thereof is unsuccessful, then the Image
Formation and Detection Subsystem (i) automatically captures a wide-area
image, while the Subsystem 17 (ii) automatically enters its Omniscan
Mode of operation described above, and then (iii) immediately commences
processing of the captured wide-area image at a plurality of parallel
spatially-separated (e.g. by 50 pixels) virtual scan lines, beginning
at a start pixel and start angle specified by x and/or y coordinates
of code fragments detected in the narrow-area image processed during
the NoFinder Mode of operation. Then, if the Omniscan Mode does
not successfully read a bar code symbol within the ROI, then the
Subsystem 17 (ii) automatically enters its ROI-specific mode of
operation described above, and then (iii) immediately commences
processing of the captured wide-area image at a ROI specified by
the x,y coordinates corresponding to code fragments detected in
the wide-area image processed during the Omniscan Mode of operation.
In the illustrative embodiment, this switching of modes in the Subsystem
17 occurs within a single bar code symbol reading cycle, and involves
processing two captured image frames using at least three different
modes (i.e. methods) of image-processing based bar code reading
(i.e. NoFinder Mode, Omniscan Mode, and ROI-Specific Mode), within
each of which potentially dozens of different bar code symbol decoding
algorithms are typically applied during each decoding cycle.
[0434] One potential advantage of the "No-Finder/OmniScan/ROI-Specific"
Multi-Read Mode operation over the Manual Mode of operation, regardless
of its method of implementation, is that the No-Finder Mode can
rapidly acquire 1D bar code symbologies whenever they are presented
to the bar code symbol reader, and then whenever a 2D symbology
is encountered, the bar code symbol reader can automatically switch
its method of reading to the OmniScan Mode, collected features on
processed image data, and if this decoding method is not successful,
then the bar code reader can automatically switch its method of
reading to the ROI-Specific Mode and use features collected during
the Omniscan Mode to immediately process a specific ROI in a captured
image frame, at which there is a high likelihood of a bar code symbol
present, and to do so in a highly targeted manner.
Programmable Modes of Bar Code Reading Operation within the Hand-Supportable
Digital Image-Based Bar Code Reading Device of the Present Invention
[0435] As indicated in FIG. 26, the Imaging-Based Bar Code Symbol
Reader of the present invention has at least seventeen (17) Programmable
System Modes of Operation, namely: Programmed Mode of System Operation
No. 1--Manually-Triggered Single-Attempt 1D Single-Read Mode Employing
the No-Finder Mode of the Multi-Mode Bar Code Reading Subsystem;
Programmed Mode Of System Operation No. 2--Manually-Triggered Multiple-Attempt
1D Single-Read Mode Employing the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem; Programmed Mode Of System Operation
No. 3--Manually-Triggered Single-Attempt 1D/2D Single-Read Mode
Employing the No-Finder Mode And The Automatic Or Manual Modes of
the Multi-Mode Bar Code Reading Subsystem; Programmed Mode of System
Operation No. 4--Manually-Triggered Multiple-Attempt 1D/2D Single-Read
Mode Employing the No-Finder Mode And The Automatic Or Manual Modes
of the Multi-Mode Bar Code Reading Subsystem; Programmed Mode of
System Operation No. 5--Manually-Triggered Multiple-Attempt 1D/2D
Multiple-Read Mode Employing the No-Finder Mode And The Automatic
Or Manual Modes of the Multi-Mode Bar Code Reading Subsystem; Programmed
Mode of System Operation No. 6--Automatically-Triggered Single-Attempt
1D Single-Read Mode Employing The No-Finder Mode Of the Multi-Mode
Bar Code Reading Subsystem; Programmed Mode of System Operation
No. 7--Automatically-Triggered Multi-Attempt 1D Single-Read Mode
Employing The No-Finder Mode Of the Multi-Mode Bar Code Reading
Subsystem; Programmed Mode of System Operation No. 8--Automatically-Triggered
Multi-Attempt 1D/2D Single-Read Mode Employing The No-Finder Mode
and Manual and/or Automatic Modes Of the Multi-Mode Bar Code Reading
Subsystem; Programmed Mode of System Operation No. 9--Automatically-Triggered
Multi-Attempt 1D/2D Multiple-Read Mode Employing The No-Finder Mode
and Manual and/or Automatic Modes Of the Multi-Mode Bar Code Reading
Subsystem; Programmable Mode of System Operation No. 10--Automatically-Triggered
Multiple-Attempt 1D/2D Single-Read Mode Employing The Manual, Automatic
or Omniscan Modes Of the Multi-Mode Bar Code Reading Subsystem;
Programmed Mode of System Operation No. 11--Semi-Automatic-Triggered
Single-Attempt 1D/2D Single-Read Mode Employing The No-Finder Mode
And The Automatic Or Manual Modes Of the Multi-Mode Bar Code Reading
Subsystem; Programmable Mode of System Operation No. 12--Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Single-Read Mode Employing The No-Finder
Mode And The Automatic Or Manual Modes Of the Multi-Mode Bar Code
Reading Subsystem; Programmable Mode of Operation No. 13--Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing The No-Finder
Mode And The Automatic Or Manual Modes Of the Multi-Mode Bar Code
Reading Subsystem; Programmable Mode of Operation No. 14--Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing The No-Finder
Mode And The Omniscan Modes Of the Multi-Mode Bar Code Reading Subsystem;
Programmable Mode of Operation No. 15--Continuously-Automatically-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing The Automatic,
Manual Or Omniscan Modes Of the Multi-Mode Bar Code Reading Subsystem;
Programmable Mode of System Operation No. 16--Diagnostic Mode Of
Imaging-Based Bar Code Reader Operation; and Programmable Mode of
System Operation No. 17--Live Video Mode Of Imaging-Based Bar Code
Reader Operation.
[0436] Preferably, these Modes Of System Operation can programmed
by reading a sequence of bar code symbols from a programming menu
as taught, for example, in U.S. Pat. No. 6,565,005, which describes
a bar code scanner programming technology developed by Metrologic
Instruments, Inc., and marketed under the name MetroSelect.RTM.
Single Line Configuration Programming Method.
[0437] These Programmable System Modes of Operation will be described
in detail hereinbelow. Alternatively, the MetroSet.RTM. Graphical
User Interface (GUI) can be used to view and change configuration
parameters in the bar code symbol reader using a PC. Alternatively,
a Command Line Interface (CLI) may also be used to view and change
configuration parameters in the bar code symbol reader,
[0438] Each of these programmable modes of bar code reader operation
shall be now described in greater detail with reference to other
components of the system that are configured together to implement
the same in accordance with the principles of the present invention.
Overview of the Imaging-Based Bar Code Reader Start-Up Operations
[0439] When the bar code reader hereof boots up, its FPGA is programmed
automatically with 12.5/50/25 MHz clock firmware and all required
device drivers are also installed automatically. The login to the
Operating System is also done automatically for the user "root",
and the user is automatically directed to the /root/ directory.
For nearly all programmable modes of system operation employing
automatic object detection, the IR object detection software driver
is installed automatically. Also, for all Programmable System Modes
of operation employing the narrow-area illumination mode, the narrow-area
illumination software drivers are automatically installed, so that
a Pulse Width Modulator (PWM) is used to drive the narrow-area LED-based
illumination array 27. To start the bar code reader operation, the
operating system calls the/tmp/ directory first ("cd/tmp"),
and then the focusapp program, located in /root/ directory is run,
because the /root/ directory is located in Flash ROM, and to save
captured images, the directory /tmp/ should be the current directory
where the image is stored in transition to the host), which is located
in RAM.
Programmed Mode of System Operation No. 1: Manually-Triggered Single-Attempt
1D Single-Read Mode Employing the No-Finder Mode of the Multi-Mode
Bar Code Symbol Reading Subsystem
[0440] Programmed Mode of System Operation No. 1 involves configuration
of the system as follows: disabling the IR-based Object Presence
and Range Detection Subsystem 12; and enabling the use of manual-trigger
activation, the narrow-area illumination mode within the Multi-Mode
Illumination Subsystem 14, the narrow-area image capture mode in
the Image Formation and Detection Subsystem 13, and the No-Finder
Mode of the Multi-Mode Bar Code Reading Subsystem 17.
[0441] During this mode of system operation, when a user pulls
the trigger switch 2C, the system activates the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode of the Image Formation and Detection Subsystem
13, and the No-Finder Mode of the Multi-Mode Bar Code Symbol Reading
Subsystem 17. Then, the bar code reader illuminates the target object
using narrow-area illumination, captures a narrow-area image of
the target object, and launches the No-Finder Mode of the Multi-Mode
Bar Code Symbol Reading Subsystem 17. The captured image is then
processed using the No-Finder Mode. If a single cycle of programmed
image processing results in the successful reading of a 1D bar code
symbol, then the resulting symbol character data is sent to the
Input/Output Subsystem 18 for use by the host system. If single
cycle of programmed image processing is not result in a successful
reading of a 1D bar code symbol, then the cycle is terminated, all
subsystems are deactivated, and the bar code reader returns to its
sleep mode of operation, and wait for the next event (e.g. manually
pulling trigger switch 2C) which will trigger the system into active
operation.
Programmed Mode of System Operation No. 2: Manually-Triggered Multiple-Attempt
1D Single-Read Mode Employing the No-Finder Mode of the Multi-Mode
Bar Code Symbol Reading Subsystem
[0442] Programmed Mode of System Operation No. 2 involves configuration
of the system as follows: disabling the IR-based Object Presence
and Range Detection Subsystem 12; and enabling the use of manual-trigger
activation, the narrow-area illumination mode within the Multi-Mode
Illumination Subsystem 14, the narrow-area image capture mode in
the Image Formation and Detection Subsystem 13, and the No-Finder
Mode of the Multi-Mode Bar Code Symbol Reading Subsystem 17.
[0443] During this mode of system operation, when a user pulls
the trigger switch 2C, the system activates the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode of the Image Formation and Detection Subsystem
13, and the No-Finder Mode of the Multi-Mode Bar Code Reading Subsystem
17. Then, the bar code reader illuminates the target object using
narrow-area illumination, captures a narrow-area image of the target
object, and launches the No-Finder Mode of the Multi-Mode Bar Code
Reading Subsystem 17. The captured narrow-area image is then processed
using the No-Finder Mode. If the single cycle of programmed image
processing results in the successful reading of a 1D bar code symbol,
then the resulting symbol character data is sent to the Input/Output
Subsystem for use by the host system. If the cycle of programmed
image processing does not produce a successful read, then the system
automatically enables successive cycles of illumination/capture/processing
so long as the trigger switch 2C is being pulled, and then until
the system reads a bar code symbol within a captured image of the
target object; only thereafter, or when the user releases the trigger
switch 2C, will the bar code symbol reader return to its sleep mode
of operation, and wait for the next event that will trigger the
system into active operation. In the illustrative embodiment, the
default decode timeout is set to 500 ms which can be simply changed
by programming. This default decode timeout setting ensures that
while the trigger switch 2C is being pulled by the user, the Imaging-Based
Bar Code Symbol Reader will re-attempt reading every 500 ms (at
most) until it either succeeds or the trigger switch 2C is manually
released.
Programmed Mode of System Operation No. 3: Manually-Triggered Single-Attempt
1D/2D Single-Read Mode Employing the No-Finder Mode and the Automatic,
Manual or ROI-Specific Modes of the Multi-Mode Bar Code Symbol Reading
Subsystem
[0444] Programmed Mode of System Operation No. 3 involves configuration
of the system as follows: disabling the IR-based Object Presence
and Range Detection Subsystem 12; and enabling the use of manual-trigger
activation, the narrow-area and wide-area illumination modes within
the Multi-Mode Illumination Subsystem 14, the narrow-area and wide-area
image capture modes in the Image Formation and Detection Subsystem
13, and the No-Finder Mode and Manual, ROI-Specific and/or Automatic
Modes of the Multi-Mode Bar Code Reading Subsystem 17.
[0445] During this programmable mode of system operation, the bar
code reader is idle (in its sleep mode) until a user points the
bar code reader towards an object with a bar code label, and then
pulls the trigger switch 2C. When this event occurs, the system
activates the narrow-area illumination mode within the Multi-Mode
Illumination Subsystem 14 (i.e. drives the narrow-area illumination
array 27), the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17. Then, the bar code reader illuminates
the target object using narrow-area illumination, captures a narrow-area
image of the target object, and launches the No-Finder Mode of the
Multi-Mode Bar Code Reading Subsystem 17. The captured narrow-area
image is then processed using the No-Finder Mode. If this single
cycle of programmed image processing results in the successful reading
of a 1D bar code symbol, then the resulting symbol character data
is sent to the Input/Output Subsystem 18 for use by the host system.
If this cycle of programmed image processing does not produce a
successful read, then the system deactivates the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode of the Image Formation and Detection Subsystem
13, and the No-Finder Mode of the Multi-Mode Bar Code Reading Subsystem
17, and then activates the wide-area illumination mode within the
Multi-Mode Illumination Subsystem 14, the wide-area image capture
mode of the Image Formation and Detection Subsystem 13, and the
Manual, ROI-Specific and/or Automatic Modes of the Multi-Mode Bar
Code Reading Subsystem 17. Then the bar code reader illuminates
the target object using both near-field and far-field wide-area
illumination, captures a wide-area image of the target object, and
launches the Manual, ROI-Specific or Automatic Mode of the Multi-Mode
Bar Code Reading Subsystem 17. The captured wide-area image is then
processed using the Manual, ROI-Specific or Automatic Mode. If this
single cycle of programmed image processing results in the successful
reading of a 1D or 2D bar code symbol, then the resulting symbol
character data is sent to the Input/Output Subsystem 18 for use
by the host system. If this cycle of programmed image processing
does not produce a successful read, then the subsystem 19 deactivates
all subsystems and then returns to its sleep mode, and waits for
an event, which will cause it to re-enter its active mode of operation.
Programmed Mode of System Operation No. 4: Manually-Triggered Multiple-Attempt
1D/2D Single-Read Mode Employing the No-Finder Mode and the Automatic,
Manual or ROI-Specific Modes of the Multi-Mode Bar Code Symbol Reading
Subsystem
[0446] Programmed Mode of System Operation No. 4 involves configuration
of the system as follows: disabling the IR-based object detection
subsystem 12; and enabling the use of manual-trigger activation,
the narrow-area and wide-area illumination modes within the Multi-Mode
Illumination Subsystem 14, the narrow-area and wide-area image capture
modes of the Image Formation and Detection Subsystem 13, and the
No-Finder Mode and Manual, ROI-Specific and/or Automatic Modes of
the Multi-Mode Bar Code Reading Subsystem 17.
[0447] During this programmed mode of system operation, when a
user pulls the trigger switch 2C, the system activates the narrow-area
illumination mode within the Multi-Mode Illumination Subsystem 14,
the narrow-area image capture mode of the Image Formation and Detection
Subsystem 13, and the No-Finder Mode of the Multi-Mode Bar Code
Reading Subsystem 17. Then, the bar code reader illuminates the
target object using narrow-area illumination, captures a narrow-area
image of the target object, and launches the No-Finder Mode of the
Multi-Mode Bar Code Reading Subsystem 17. The captured narrow-area
image is then processed using the No-Finder Mode. If this single
cycle of programmed image processing results in the successful reading
of a 1D bar code symbol, then the resulting symbol character data
is sent to the Input/Output Subsystem for use by the host system.
If this cycle of programmed image processing does not produce a
successful read, then the system deactivates the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode of the Image Formation and Detection Subsystem
13, and the No-Finder Mode of the Multi-Mode Bar Code Reading Subsystem
17, and then activates the wide-area illumination mode within the
Multi-Mode Illumination Subsystem 14, the wide-area image capture
mode of the Image Formation and Detection Subsystem 13, and the
Manual and/or Automatic Mode of the Multi-Mode Bar Code Reading
Subsystem 17. Then, the bar code reader illuminates the target object
using both near-field and far-field wide-area illumination, captures
a wide-area image of the target object, and launches the Manual
(or Automatic) Mode of the Multi-Mode Bar Code Reading Subsystem.
The captured wide-area image is then processed using the Manual
Mode of bar code symbol reading. If this single cycle of programmed
processing results in the successful reading of a 1D or 2D bar code
symbol, then the resulting symbol character data is sent to the
Input/Output Subsystem 18 for use by the host system. If this cycle
of programmed image processing does not produce a successful read
of a single 1D or 2D bar code symbol, then the Subsystem 19 automatically
enables successive cycles of wide-area illumination/wide-area image
capture and processing so long as the trigger switch 2C is being
pulled, and then until the system reads a single 1D or 2D bar code
symbol within a captured image of the target object; only thereafter,
or when the user releases the trigger switch 2C, will the bar code
reader return to its sleep mode of operation, and wait for the next
event that will trigger the system into active operation. In the
illustrative embodiment, the default decode timeout is set to 500
ms which can be simply changed by programming. This default decode
timeout setting ensures that while the trigger switch is being pulled
by the user, the Imaging-Based Bar Code Symbol Reader will re-attempt
reading every 500 ms (at most) until it either succeeds or the trigger
switch 2C is manually released.
Programmed Mode of System Operation No. 5: Manually-Triggered Multiple-Attempt
1D/2D Multiple-Read Mode Employing the No-Finder Mode and the Automatic,
Manual or ROI-Specific Modes of the Multi-Mode Bar Code Reading
Symbol Subsystem
[0448] Programmed Mode of System Operation No. 5 involves configuration
of the system as follows: disabling the IR-based Object Presence
and Range Detection Subsystem 12; and enabling the use of manual-trigger
activation, the narrow-area and wide-area illumination modes within
the Multi-Mode Illumination Subsystem 14, the narrow-area and wide-area
image capture modes of the Image Formation and Detection Subsystem
13, and the No-Finder Mode and Manual, ROI-Specific and/or Automatic
Modes of the Multi-Mode Bar Code Reading Subsystem 17.
[0449] During this mode of system operation, when a user pulls
the trigger switch 2C, the system activates the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode of the Image Formation and Detection Subsystem
13, and the No-Finder Mode of the Multi-Mode Bar Code Reading Subsystem.
Then, the bar code reader illuminates the target object using narrow-area
illumination, captures a narrow-area image of the target object,
and launches the No-Finder Mode of the Multi-Mode Bar Code Reading
Subsystem. The captured narrow-area image is then processed using
the No-Finder Mode. If this single cycle of programmed processing
results in the successful decoding of a 1D bar code symbol, then
the resulting symbol character data is sent to the Input/Output
Subsystem 18 for use by the host system. If this cycle of programmed
decode image processing does not produce a successful read, then
the system deactivates the narrow-area illumination mode within
the Multi-Mode Illumination Subsystem 14, the narrow-area image
capture mode of the Image Formation and Detection Subsystem 13,
and the No-Finder Mode of the Multi-Mode Bar Code Reading Subsystem
17, and then activates the wide-area illumination mode within the
Multi-Mode Illumination Subsystem, the wide-area image capture mode
of the Image Formation and Detection Subsystem 13, and the Manual
and/or Automatic Mode of the Multi-Mode Bar Code Reading Subsystem
17. Then, the bar code reader illuminates the target object using
both near-field and far-field wide-area illumination, captures a
wide-area image of the target object, and launches the Manual (ROI-Specific
and/or Automatic) Mode of the Multi-Mode Bar Code Reading Subsystem
17. The captured wide-area image is then processed using the Manual
Mode of reading. If this single cycle of programmed processing results
in the successful reading of a 1D or 2D bar code symbol, then the
resulting symbol character data is sent to the Input/Output Subsystem
18 for use by the host system. If this cycle of programmed image
processing does not produce a successful reading of one or more
1D and/or 2D bar code symbols, then the system automatically enables
successive cycles of wide-area illumination/wide-area image capture/image
processing so long as the trigger switch is being pulled, and then
until the system reads one or more 1D and/or 2D bar code symbols
within a captured image of the target object; only thereafter, or
when the user releases the trigger switch 2C, will the bar code
reader return to its sleep mode of operation, and wait for the next
event that will trigger the system into active operation. In the
illustrative embodiment, the default decode timeout is set to 500
ms which can be simply changed by programming. This default decode
timeout setting ensures that while the trigger switch 2C is being
pulled by the user, the Imaging-Based Bar Code Symbol Reader will
re-attempt reading every 500 ms (at most) until it either succeeds
or the trigger switch 2C is manually released.
Programmed Mode of System Operation No. 6: Automatically-Triggered
Single-Attempt 1D Single-Read Mode Employing the No-Finder Mode
of the Multi-Mode Bar Code Symbol Reading Subsystem
[0450] Programmed Mode of System Operation No. 6 involves configuration
of the system as follows: disabling the use of manual-trigger activation;
and enabling IR-based Object Presence and Range Detection Subsystem
12, the narrow-area illumination mode only within the Multi-Mode
Illumination Subsystem 14, the narrow-area image capture mode only
in the Image Formation and Detection Subsystem 13, and the No-Finder
Mode of the Multi-Mode Bar Code Reading Subsystem 17.
[0451] During this programmed mode of system operation, the bar
code reader is idle until a user points the reader towards an object
with a bar code label. Once the object is under the field-of-view
of the bar code reader, and the object is automatically detected,
the bar code reader "wakes up" and the system activates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17. This causes the system to illuminate
a "narrow" horizontal area of the target object at the
center of the field-of-view (FOV) of the bar code reader, indicating
to the user where the area targeted by the bar code reader is, and
thus, enabling the user to position and align the narrow-area illumination
beam on the target bar code. Then, the system captures/acquires
a narrow-area image, which is then processed using the Bar Code
Symbol Reading Subsystem 17 configured in its No-Finder Mode of
operation. If this single cycle of programmed decode processing
results in the successful reading of a 1D bar code symbol, then
the resulting symbol character data is sent to the Input/Output
Subsystem 18 for use by the host system. If this cycle of programmed
image processing does not produce a successful read, then the system
deactivates all subsystems, causing the bar code reader return to
its sleep mode of operation, and wait for the next event that will
trigger the system into active operation.
Programmed Mode of System Operation No. 7: Automatically-Triggered
Multi-Attempt 1D Single-Read Mode Employing the No-Finder Mode of
the Multi-Mode Bar Code Symbol Reading Subsystem
[0452] Programmed Mode of System Operation No. 7 involves configuration
of the system as follows: disabling the use of manual-trigger activation;
and enabling IR-based Object Presence And Range Detection Subsystem
12, the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode in the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17.
[0453] During this programmed mode of system operation, the bar
code reader is idle until a user points the bar code reader towards
an object with a bar code label. Once the object is under the field-of-view
of the bar code reader, and the object is automatically detected,
the bar code reader "wakes up" and the system activates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17. This causes the system to illuminate
a "narrow" horizontal area of the target object at the
center of the field-of-view (FOV) of the bar code reader, indicating
to the user where the area targeted by the bar code reader is, and
thus, enabling the user to position and align the narrow-area illumination
beam on the target bar code. Then, the system captures/acquires
a narrow-area image, which is then processed using the No-Finder
Mode. If this single cycle of programmed image processing results
in the successful reading of a 1D bar code symbol, then the resulting
symbol character data is sent to the Input/Output Subsystem 18 for
use by the host system. If this cycle of programmed image processing
does not produce a successful decode, then the system automatically
enables successive cycles of narrow-area illumination/narrow-area
image capture/processing so long as the trigger switch 2C is being
pulled, and then until the system reads a single 1D bar code symbol
within a captured image of the target object; only thereafter, or
when the user releases the trigger switch 2C, will the bar code
reader return to its sleep mode of operation, and wait for the next
event that will trigger the system into active operation. In the
illustrative embodiment, the default decode timeout is set to 500
ms which can be simply changed by programming. This default decode
timeout setting ensures that while the trigger switch is being pulled
by the user, the Imaging-Based Bar Code Symbol Reader will re-attempt
reading every 500 ms (at most) until it either succeeds or the trigger
switch 2C is manually released.
Programmed Mode of System Operation No. 8: Automatically-Triggered
Multi-Attempt 1D/2D Single-Read Mode Employing the No-Finder Mode
and Manual, ROI-Specific and/or Automatic Modes of the Multi-Mode
Bar Code Symbol Reading Subsystem
[0454] Programmed Mode of System Operation No. 8 involves configuration
of the system as follows: disabling the use of manual-trigger activation
during all phase of system operation; and enabling IR-based Object
Presence and Range Detection Subsystem 12, the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode in the Image Formation and Detection Subsystem
13, and the No-Finder Mode and Manual, ROI-Specific and/or Automatic
Modes of the Multi-Mode Bar Code Reading Subsystem 17.
[0455] During this programmed mode of system operation, the bar
code reader is idle until a user points the reader towards an object
with a bar code label. Once the object is under the field-of-view
of the scanner, and the object is automatically detected, the bar
code reader "wakes up" and the system activates the narrow-area
illumination mode within the Multi-Mode Illumination Subsystem,
14 the narrow-area image capture mode of the Image Formation and
Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17. This causes the system to illuminate
a "narrow" horizontal area of the target object at the
center of the field-of-view (FOV) of the bar code reader, indicating
to the user where the area targeted by the bar code reader is, and
thus, enabling the user to position and align the narrow-area illumination
beam on the target bar code. Then, the system captures/acquires
a narrow-area image, which is then processed using the No-Finder
Mode of operation. If this single cycle of programmed image processing
results in the successful reading of a 1D bar code symbol, then
the resulting symbol character data is sent to the Input/Output
Subsystem 18 for use by the host system. If this cycle of programmed
image processing does not produce a successful read, then the system
deactivates the narrow-area illumination mode within the Multi-Mode
Illumination Subsystem 14, the narrow-area image capture mode of
the Image Formation and Detection Subsystem 13, and the No-Finder
Mode of the Multi-Mode Bar Code Reading Subsystem 17, and then activates
the wide-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the wide-area image capture mode in the Image Formation
and Detection Subsystem 13, and the Manual, ROI-Specific and/or
Automatic Modes of the Multi-Mode Bar Code Reading Subsystem 17.
Then, the Bar Code Symbol Reader illuminates the target object using
either near-field or far-field wide-area illumination (depending
on the detected range of the target object), captures a wide-area
image of the target object, and launches the Manual, ROI-Specific
or Automatic Mode of the Multi-Mode Bar Code Reading Subsystem 17.
The captured wide-area image is then processed using the Manual
Mode of reading. If this cycle of programmed image processing results
in the successful reading of a single 1D or 2D bar code symbol,
then the resulting symbol character data is sent to the Input/Output
Subsystem 18 for use by the host system. If this cycle of programmed
image processing does not produce a successful reading of a single
1D or 2D bar code symbol, then the system automatically enables
successive cycles of wide-area illumination/wide-area image capture/processing
so long as the target object is being detected, and then until the
system reads one or more 1D and/or 2D bar code symbols within a
captured image of the target object; only thereafter, or when the
user moves the object out of the FOV of the bar code reader, will
the bar code reader return to its sleep mode of operation, and wait
for the next event that will trigger the system into active operation.
In the illustrative embodiment, the default decode timeout is set
to 500 ms which can be simply changed by programming. This default
decode timeout setting ensures that while the object is being detected
by the bar code reader, the Bar Code Symbol Reader will re-attempt
reading every 500 ms (at most) until it either succeeds or the object
is moved away from the FOV of the bar code reader.
Programmed Mode of System Operation No. 9: Automatically-Triggered
Multi-Attempt 1D/2D Multiple-Read Mode Employing the No-Finder Mode
and Manual. ROI-Specific and/or Automatic Modes of the Multi-Mode
Bar Code Symbol Reading Subsystem
[0456] Programmed Mode of System Operation No. 9 involves configuration
of the system as follows: disabling the use of manual-trigger activation
during all phases of system operation; and enabling IR-based Object
Presence and Range Detection Subsystem 12, the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode in the Image Formation and Detection Subsystem
13, and the No Finder Mode and Manual or Automatic Modes of the
Multi-Mode Bar Code Symbol Reading Subsystem 17.
[0457] During this programmed mode of system operation, the bar
code reader is idle until a user points the reader towards an object
with a bar code label. Once the object is under the field-of-view
of the bar code reader, and the object is automatically detected,
the bar code reader "wakes up" and the system activates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17. This causes the system to illuminate
a "narrow" horizontal area of the target object at the
center of the field-of-view (FOV) of the bar code reader, indicating
to the user where the area targeted by the bar code reader is, and
thus, enabling the user to position and align the narrow-area illumination
beam on the target bar code. Then, the system captures/acquires
a narrow-area image, which is then processed using the No-Finder
Mode. If this single cycle of programmed processing results in the
successful reading of a 1D bar code symbol, then the resulting symbol
character data is sent to the Input/Output Subsystem 18 for use
by the host system. If this cycle of programmed image processing
does not produce a successful read, then the system deactivates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17, and then activates the wide-area
illumination mode within the Multi-Mode Illumination Subsystem 14,
the wide-area image capture mode in the Image Formation and Detection
Subsystem 13, and the Manual and/or Automatic Modes of the Multi-Mode
Bar Code Reading Subsystem 17. Then, the bar code reader illuminates
the target object using either near-field or far-field wide-area
illumination (depending on the detected range of the target object),
captures a wide-area image of the target object, and launches the
Manual (ROI-Specific or Automatic) Mode of the Multi-Mode Bar Code
Reading Subsystem 17. The captured wide-area image is then processed
using the Manual Method of decoding. If this cycle of programmed
image processing results in the successful reading of a single 1D
or 2D bar code symbol, then the resulting symbol character data
is sent to the Input/Output Subsystem 18 for use by the host system.
If this cycle of programmed image processing does not produce a
successful read of a single 1D or 2D bar code symbol, then the system
automatically enables successive cycles of wide-area-illumination/wide-area
image-capture/processing so long as the target object is being detected,
and then until the system reads one or more 1D and/or 2D bar code
symbols within a captured image of the target object; only thereafter,
or when the user moves the object out of the FOV of the bar code
symbol reader, will the bar code reader return to its sleep mode
of operation, and wait for the next event that will trigger the
system into active operation. In the illustrative embodiment, the
default decode timeout is set to 500 ms which can be simply changed
by programming. This default decode timeout setting ensures that
while the object is being detected by the bar code reader, the bar
code reader will re-attempt reading every 500 ms (at most) until
it either succeeds or the object is moved away from the FOV of the
bar code reader.
Programmable Mode of System Operation No. 10: Automatically-Triggered
Multiple-Attempt 1D/2D Single-Read Mode Employing the Manual, ROI-Specific,
Automatic or Omniscan Modes of the Multi-Mode Bar Code Symbol Reading
Subsystem
[0458] Programmed Mode of System Operation No. 10 involves configuration
of the system as follows: disabling the use of manual-trigger activation
during all phase of system operation; and enabling IR-based Object
Presence and Range Detection Subsystem 12, the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode in the Image Formation and Detection Subsystem
13, and the Manual, ROI-Specific, Automatic or OmniScan Modes of
the Multi-Mode Bar Code Reading Subsystem 17.
[0459] During this programmed mode of system operation, the bar
code reader is idle until a user present an object with a bar code
symbol under the field-of-view of the bar code reader, and the object
is automatically detected, the bar code reader "wakes up"
and the system activates the wide-area illumination mode within
the Multi-Mode Illumination Subsystem 14, the wide-area image capture
mode in the Image Formation and Detection Subsystem 13, and either
Manual, ROI-Specific, Automatic or Omniscan Mode of the Multi-Mode
Bar Code Reading Subsystem 17. This causes the system to illuminate
a wide area of the target object within the field-of-view (FOV)
of the bar code reader with far-field or near-field wide area illumination
(depending on the detected range of the target object), and capture/acquire
a wide-area image which is then processed using either the Manual,
ROI-Specific, Automatic or Omniscan Method of reading. If this single
cycle of programmed processing results in the successful reading
of a 1D or 2D bar code symbol (when the Manual, ROI-Specific and
Automatic Methods are used), then the resulting symbol character
data is sent to the Input/Output Subsystem for use by the host system.
If this cycle of programmed image processing does not produce a
successful read, then the system automatically enables successive
cycles of wide-area illumination/wide-area-image-capture/processing
so long as the target object is being detected, and then until the
system reads a single 1D and/or 2D bar code symbol within a captured
image of the target object; only thereafter, or when the user moves
the object out of the FOV of the bar code reader, will the bar code
reader return to its sleep mode of operation, and wait for the next
event that will trigger the system into active operation. In the
illustrative embodiment, the default decode timeout is set to 500
ms which can be simply changed by programming. This default decode
timeout setting ensures that while the object is being detected
by the bar code reader, the bar code reader will re-attempt reading
every 500 ms (at most) until it either succeeds or the object is
moved away from the FOV of the bar code reader.
Programmed Mode of System Operation No. 11: Semi-Automatic-Triggered
Single-Attempt 1D/2D Single-Read Mode Employing the No-Finder Mode
and the Automatic, ROI-Specific or Manual Modes of the Multi-Mode
Bar Code Symbol Reading Subsystem
[0460] Programmed Mode of System Operation No. 11 involves configuration
of the system as follows: disabling the use of the manual-trigger
activation during the system activation phase of operation; and
enabling the IR-based Object Presence and Range Detection Subsystem
12, the narrow-area and wide-area illumination modes within the
Multi-Mode Illumination Subsystem 14, the narrow-area and wide-area
image capture modes in the Image Formation and Detection Subsystem
13, and the No-Finder Mode and Manual, ROI-Specific and/or Automatic
Modes of the Multi-Mode Bar Code Reading Subsystem 17.
[0461] During this programmed mode of system operation, the bar
code reader is idle until a user points the reader towards an object
with a bar code label. Once the object is under the field-of-view
of the bar code reader, and the object is automatically detected,
the bar code reader "wakes up" and the system activates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17. This causes the system to illuminate
a "narrow" horizontal area of the target object at the
center of the field-of-view (FOV) of the bar code reader, indicating
to the user where the area targeted by the bar code reader is, and
thus, enabling the user to position and align the narrow-area illumination
beam on the target bar code. Then, the system captures/acquires
a narrow-area image, which is then processed using the No-Finder
Mode. If this single cycle of programmed image processing results
in the successful reading of a 1D bar code symbol, then the resulting
symbol character data is sent to the Input/Output Subsystem 18 for
use by the host system. If this cycle of programmed image processing
does not produce a successful read, then the system deactivates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17, and then activates the wide-area
illumination mode within the Multi-Mode Illumination Subsystem 14,
the wide-area image capture mode of the Image Formation and Detection
Subsystem 13, and the Manual, ROI-Specific and/or Automatic Mode
of the Multi-Mode Bar Code Reading Subsystem 17. Then, if the user
pulls the trigger switch 2C during narrow-area illumination and
image capture and continues to do so, the bar code reader will automatically
illuminate the target object using wide-area illumination, capture
a wide-area image of the target object, and launch the Manual, ROI-Specific
or Automatic Mode of the Multi-Mode Bar Code Symbol Reading Subsystem
17. The captured wide-area image is then processed using the Manual,
ROI-Specific or Automatic Mode/Method of bar code reading. If this
single cycle of programmed image processing results in the successful
reading of a single 1D or 2D bar code symbol, then the resulting
symbol character data is sent to the Input/Output Subsystem 18 for
use by the host system. If this cycle of programmed image processing
does not produce a successful reading of a single 1D or 2D bar code
symbol, then the subsystem 19 automatically deactivates all subsystems,
causing the bar code reader return to its sleep mode of operation,
and wait for the next event that will trigger the system into active
operation
Programmable Mode of System Operation No. 12: Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Single-Read Mode Employing the No-Finder
Mode and the Automatic, ROI-Specific or Manual Modes of the Multi-Mode
Bar Code Symbol Reading Subsystem;
[0462] Programmed Mode of System Operation No. 12 involves configuration
of the system as follows: disabling the use of manual-trigger activation
during the system activation phase of operation; and enabling the
IR-based Object Presence and Range Detection Subsystem 12, the narrow-area
and wide-area illumination modes within the Multi-Mode Illumination
Subsystem 14, the narrow-area and wide-area image capture modes
in the Image Formation and Detection Subsystem 13, and the No-Finder
Mode and Manual, ROI-Specific and/or Automatic Modes of the Multi-Mode
Bar Code Reading Subsystem 17.
[0463] During this programmed mode of system operation, the bar
code reader is idle until a user points the reader towards an object
with a bar code label. Once the object is under the field-of-view
of the bar code reader, and the object is automatically detected,
the bar code reader "wakes up" and the system activates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17. This causes the system to illuminate
a "narrow" horizontal area of the target object at the
center of the field-of-view (FOV) of the bar code reader, indicating
to the user where the area targeted by the bar code reader is, and
thus, enabling the user to position and align the narrow-area illumination
beam on the target bar code. Then, the system captures/acquires
a narrow-area image, which is then processed using the No-Finder
Mode. If this single cycle of programmed image processing results
in the successful reading of a 1D bar code symbol, then the resulting
symbol character data is sent to the Input/Output Subsystem 18 for
use by the host system. If this cycle of programmed image processing
does not produce a successful read, then the system deactivates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17, and then activates the wide-area
illumination mode within the Multi-Mode Illumination Subsystem,
the wide-area image capture mode of the Image Formation and Detection
Subsystem 13, and the Manual, ROI-Specific and/or Automatic Mode
of the Multi-Mode Bar Code Reading Subsystem 17. Then, if the user
pulls the trigger switch 2C during narrow-area illumination and
image capture and continues to do so, the bar code reader will automatically
illuminate the target object using wide-area illumination, capture
a wide-area image of the target object, and launches the Manual,
ROI-Specific or Automatic Mode of the Multi-Mode Bar Code Reading
Subsystem 17. The captured wide-area image is then processed using
the Manual Mode of reading. If this single cycle of programmed image
processing results in the successful reading of a single 1D or 2D
bar code symbol, then the resulting symbol character data is sent
to the Input/Output Subsystem 18 for use by the host system. If
this cycle of programmed image processing does not produce a successful
decode of a single 1D or 2D bar code symbol, then the system automatically
enables successive cycles of wide-area illumination/wide-area-image-capture/processing
so long as the trigger switch 2C is being pulled, and then until
the system reads one or more 1D and/or 2D bar code symbols within
a captured image of the target object; only thereafter, or when
the user releases the trigger switch 2C, will the bar code reader
return to its sleep mode of operation, and wait for the next event
that will trigger the system into active operation. In the illustrative
embodiment, the default decode timeout is set to 500 ms which can
be simply changed by programming. This default decode timeout setting
ensures that while the trigger switch 2C is being pulled by the
user, the Imaging-Based Bar Code Symbol Reader will re-attempt reading
every 500 ms (at most) until it either succeeds or the trigger switch
2C is manually released.
Implementation of Programmable Mode of System Operation No. 12
[0464] When the Focus IR module detects an object in front of object
detection field 20, it posts the OBJECT_DETECT_ON event to the Application
Layer. The Application Layer software responsible for processing
this event starts the CodeGate Task. When the user pulls the trigger
switch 2C, the TRIGGER_ON event is posted to the Application. The
Application Layer software responsible for processing this event
checks if the CodeGate Task is running, and if so, it cancels it
and then starts the Main Task. When the user releases the trigger
switch 2C, the TRIGGER_OFF event is posted to the Application. The
Application Layer software responsible for processing this event,
checks if the Main Task is running, and if so, it cancels it. If
the object is still within the object detection field 20, the Application
Layer starts the CodeGate Task again.
[0465] When the user moves the bar code reader away from the object
(or the object away from the bar code reader), the OBJECT_DETECT_OFF
event is posted to the Application Layer. The Application Layer
software responsible for processing this event checks if the CodeGate
Task is running, and if so, it cancels it. The CodeGate Task, in
an infinite loop, does the following. It activates the narrow-area
illumination array 27 which illuminates a "narrow" horizontal
area at the center of the field-of-view and then the Image Formation
and Detection Subsystem 13 acquires an image of that narrow-area
(i.e. few rows of pixels on the CMOS image sensing array 22), and
then attempts to read a bar code symbol represented in the image.
If the read is successful, it saves the decoded data in the special
CodeGate data buffer. Otherwise, it clears the CodeGate data buffer.
Then, it continues the loop. The CodeGate Task never exits on its
own; it can be canceled by other modules of the Focus software when
reacting to other events.
[0466] When a user pulls the trigger switch 2C, the event TRIGGER_ON
is posted to the Application Layer. The Application Layer software
responsible for processing this event, checks if the CodeGate Task
is running, and if so, it cancels it and then starts the Main Task.
The CodeGate Task can also be canceled upon OBJECT_DETECT_OFF event,
posted when the user moves the bar code reader away from the object,
or the object away from the bar code reader.
Programmable Mode of Operation No. 13: Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing the No-Finder
Mode and the Automatic, ROI-Specific or Manual Modes of the Multi-Mode
Bar Code Reading Subsystem
[0467] Programmed Mode of System Operation No. 13 involves configuration
of the system as follows: disabling the use of manual-trigger activation
during the system activation phase of operation; and enabling the
IR-based Object Presence and Range Detection Subsystem 12, the narrow-area
and wide-area illumination modes within the Multi-Mode Illumination
Subsystem 14, the narrow-area and wide-area image capture modes
in the Image Formation and Detection Subsystem 13, and the No-Finder
Mode and Manual, ROI-Specific and/or Automatic Modes of the Multi-Mode
Bar Code Reading Subsystem 17.
[0468] During this programmed mode of system operation, the bar
code reader is idle until a user points the reader towards an object
with a bar code label. Once the object is under the field-of-view
of the bar code reader, and the object is automatically detected
by the Object Presence and Range Detection Subsystem 12, the bar
code reader "wakes up" and the system activates the narrow-area
illumination mode in the Multi-Mode Illumination Subsystem 14, the
narrow-area image capture mode in the Image Formation and Detection
Subsystem 13, and the No-Finder Mode of the Multi-Mode Bar Code
Reading Subsystem 17. This causes the system to illuminate a "narrow"
horizontal area of the target object at the center of the field-of-view
(FOV) of the bar code reader, indicating to the user where the area
targeted by the bar code reader is, and thus, enabling the user
to position and align the narrow-area illumination beam on the target
bar code. Then, the system captures/acquires a narrow-area image
which is then processed using the No-Finder Mode. If this single
cycle of programmed image processing results in the successful reading
of a 1D bar code symbol, then the resulting symbol character data
is sent to the Input/Output Subsystem 18 for use by the host system.
If this cycle of programmed image processing does not produce a
successful read, then the system deactivates the narrow-area illumination
mode within the Multi-Mode Illumination Subsystem 14, the narrow-area
image capture mode of the Image Formation and Detection Subsystem
13, and the No-Finder Mode of the Multi-Mode Bar Code Reading Subsystem
17, and then activates the wide-area illumination mode within the
Multi-Mode Illumination Subsystem 14, the wide-area image capture
mode of the Image Formation and Detection Subsystem 13, and the
Manual and/or Automatic Mode of the Multi-Mode Bar Code Reading
Subsystem 17. Then, if the user pulls the trigger switch 2C during
narrow-area illumination and image capture and continues to do so,
the bar code reader will automatically illuminate the target object
using wide-area illumination, capture a wide-area image of the target
object, and invoke the Manual, ROI-Specific and/or Automatic Mode
of the Multi-Mode Bar Code Reading Subsystem 17. The captured wide-area
image is then processed using the Manual, ROI-Specific or Automatic
Mode of reading. If this single cycle of programmed image processing
results in the successful reading of one or more 1D and/or 2D bar
code symbols, then the resulting symbol character data is sent to
the Input/Output Subsystem 18 for use by the host system. If this
cycle of programmed decode image processing does not produce a successful
reading of one or more 1D and/or 2D bar code symbols then the system
automatically enables successive cycles of wide-area illumination/wide-area-image-capture/image-processing
so long as the trigger switch 2C is being pulled, and then until
the system reads one or more 1D and/or 2D bar code symbols within
a captured image of the target object; only thereafter, or when
the user releases the trigger switch 2C, will the bar code reader
return to its sleep mode of operation, and wait for the next event
that will trigger the system into active operation. In the illustrative
embodiment, the default decode timeout is set to 500 ms which can
be simply changed by programming. This default decode timeout setting
ensures that while the trigger switch 2C is being pulled by the
user, the Imaging-Based Bar Code Symbol Reader will re-attempt reading
every 500 ms (at most) until it either succeeds or the trigger switch
2C is manually released.
Programmable Mode of Operation No. 14: Semi-Automatic-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing the No-Finder
Mode and the Omniscan Modes of the Multi-Mode Bar Code Symbol Reading
Subsystem
[0469] Programmed Mode of System Operation No. 14 involves configuration
of the system as follows: disabling the use of manual-trigger activation
during the system activation phase of operation; and enabling the
IR-based Object Presence and Range Detection Subsystem 12, the narrow-area
and wide-area illumination modes within the Multi-Mode Illumination
Subsystem 14, the narrow-area and wide-area image capture modes
in the Image Formation and Detection Subsystem 13, and the No-Finder
Mode and OmniScan Mode of the Multi-Mode Bar Code Reading Subsystem
17.
[0470] During this programmed mode of system operation, the bar
code reader is idle until a user points the reader towards an object
with a bar code label. Once the object is under the field-of-view
of the bar code reader, and the object is automatically detected
by the Object Presence and Range Detection Subsystem 12, the bar
code reader "wakes up" and the system activates the narrow-area
illumination mode in the Multi-Mode Illumination Subsystem 14, the
narrow-area image capture mode in the Image Formation and Detection
Subsystem 13, and the No-Finder Mode of the Multi-Mode Bar Code
Reading Subsystem 17. This causes the narrow-area illumination array
27 to illuminate a "narrow" horizontal area of the target
object at the center of the field-of-view (FOV) of the bar code
reader, indicating to the user where the area targeted by the bar
code reader is, and thus, enabling the user to position and align
the narrow-area illumination beam on the target bar code. Then,
Subsystem 13 captures/acquires a narrow-area image which is then
processed by Subsystem 17 using its No-Finder Mode. If this single
cycle of programmed image processing results in the successful reading
of a 1D bar code symbol, then the resulting symbol character data
is sent to the Input/Output Subsystem 18 for use by the host system,
and then the system deactivates all subsystems and resumes its sleep
state of operation. If this cycle of programmed image processing
does not produce a successful read, it may nevertheless produce
one or more code fragments indicative of the symbology represented
in the image, (e.g. PDF 417). In this case, the system deactivates
the narrow-area illumination mode within the Multi-Mode Illumination
Subsystem 14, the narrow-area image capture mode of the Image Formation
and Detection Subsystem 13, and the No-Finder Mode of the Multi-Mode
Bar Code Reading Subsystem 17; and then, if the user is pulling
the trigger switch 2C at about this time, the system activates the
wide-area illumination mode within the Multi-Mode Illumination Subsystem
14, the wide-area image capture mode of the Image Formation and
Detection Subsystem, and either the Omniscan Mode of the Multi-Mode
Bar Code Reading Subsystem 17 if code fragments have been found
indicating a 2D code format (e.g. PDF format code) within the image
at perhaps a particular orientation. Then, the bar code reader proceeds
to automatically illuminate the target object using wide-area illumination,
capture a wide-area image of the target object, and invoke the Omniscan
Mode of the Multi-Mode Bar Code Reading Subsystem 17. The captured
wide-area image is then first processed using the Omniscan Mode,
using a first processing direction (e.g. at 0 degrees), and sequentially
advances the Omniscan Mode of reading at an different angular orientation
(e.g. 6 possible directions/orientations) until a single bar code
symbol is successfully read. If this single cycle of programmed
decode processing (using the Omniscan Mode) results in the successful
decoding of a single 1D and/or 2D bar code symbol, then the resulting
symbol character data is sent to the Input/Output Subsystem 18 for
use by the host system. If this cycle of programmed image processing
does not produce a successful reading of a single 1D and/or 2D bar
code symbol, then the system automatically enables successive cycles
of wide-area illumination/wide-area image capture/processing so
long as the trigger switch 2C is being pulled, and then until the
system reads a single 1D and/or 2D bar code symbol within a captured
image of the target object. Only thereafter, or when the user releases
the trigger switch 2C, the system will return to its sleep mode
of operation, and wait for the next event that will trigger the
system into active operation. In the illustrative embodiment, the
default decode timeout is set to 500 ms which can be simply changed
by programming. This default decode timeout setting ensures that
while the trigger switch 2C is being pulled by the user, the Imaging-Based
Bar Code Symbol Reader will re-attempt reading every 500 ms (at
most) until it either succeeds or the trigger switch is manually
released.
Programmable Mode of Operation No. 15: Continuously-Automatically-Triggered
Multiple-Attempt 1D/2D Multiple-Read Mode Employing the Automatic,
Manual, ROI-Specific or Omniscan Modes of the Multi-Mode Bar Code
Reading Subsystem
[0471] Programmed Mode of System Operation No. 15, typically used
for testing purposes, involves configuration of the system as follows:
disabling the use of manual-trigger activation during all phase
of system operation; and enabling IR-based Object Presence and Range
Detection Subsystem 12, the wide-area illumination mode in the Multi-Mode
Illumination Subsystem, 14 the wide-area image capture mode in the
Image Formation and Detection Subsystem 13, and the Manual, ROI-Specific,
Automatic or OmniScan Modes of the Multi-Mode Bar Code Reading Subsystem
17.
[0472] During this programmed mode of system operation, the bar
code reader continuously and sequentially illuminates a wide area
of the target object within the field-of-view (FOV) of the bar code
reader with both far-field and near-field wide-area illumination,
captures a wide-area image thereof, and then processes the same
using either the Manual, ROI-Specific, Automatic or Omniscan Modes
of operation. If any cycle of programmed image processing results
in the successful reading of a 1D or 2D bar code symbol (when the
Manual, ROI-Specific and Automatic Modes are used), then the resulting
symbol character data is sent to the Input/Output Subsystem 18 for
use by the host system (i.e. typically a test measurement system).
If when any cycle of programmed image processing does not produce
a successful read, the system automatically enables successive cycles
of wide-area illumination/wide-area image-capture/processing. In
the illustrative embodiment, the default decode timeout is set to
500 ms which can be simply changed by programming. This default
decode timeout setting ensures that while the object is being detected
by the bar code reader, the bar code reader will re-attempt reading
every 500 ms (at most) until it either succeeds or the object is
moved away from the FOV of the bar code reader.
Diagnostic Mode of Imaging-Based Bar Code Reader Operation: Programmable
Mode of System Operation No. 16
[0473] Programmed Mode of System Operation No. 16 is a Diagnostic
Mode. An authorized user can send a special command to the bar code
reader to launch a Command Line Interface (CLI) with the bar code
reader. When the bar code reader receives such request from the
user, it sends a prompt "MTLG>" back to the user as
a handshaking indication that the scanner is ready to accept the
user commands. The user then can enter any valid command to the
bar code reader and view the results of its execution. To communicate
with the reader in diagnostic mode over such communication line
as RS232, the user can use any standard communication program, such
as Windows HyperTerminal for example. This mode of operation can
be used to test/debug the newly introduced features or view/change
the bar code reader configuration parameters. It can also be used
to download images and/or a backlog of the previously decoded bar
code data from the reader memory to the host computer.
Live Video Mode of Imaging-Based Bar Code Reader Operation: Programmable
Mode of System Operation No. 17
[0474] Program Mode of System Operation No. 17 can be used in combination
with any other supported imaging modes. In this mode, the images
acquired by the bar code reader are transmitted to the host computer
in real-time along with the results of image-processing based bar
code symbol reading by Subsystem 17 (if such results are available).
Second Illustrative Embodiment of Digital Imaging-Based Bar Code
Symbol Reading Device of the Present Invention, Wherein Four Distinct
Modes of Illumination are Provided
[0475] In the first illustrative embodiment described above, the
Multi-mode Illumination Subsystem 14 had three primary modes of
illumination: (1) narrow-area illumination mode; (2) near-field
wide-area illumination mode; and (3) far-field wide-area illumination
mode.
[0476] In a second alternative embodiment of the Digital Imaging-Based
Bar Code Symbol Reading Device of the present invention shown in
FIGS. 27A, 27B and 28, the Multi-Mode Illumination Subsystem 14
is modified to support four primary modes of illumination: (1) near-field
narrow-area illumination mode; (2) far-field narrow-area illumination
mode; (3) near-field wide-area illumination mode; and (4) far-field
wide-area illumination mode. In general, these near-field and far-field
narrow-area illumination modes of operation are conducted during
the narrow-area image capture mode of the Multi-Mode Image Formation
and Detection Subsystem 13, and are supported by a near-field narrow-illumination
array 27A and a far field narrow-area illumination array 27B illustrated
in FIG. 28, and as shown in FIG. 2A1. In the second illustrative
embodiment, each of these illumination arrays 27A, 27B are realized
using at least a pair of LEDs, each having a cylindrical lens of
appropriate focal length to focus the resulting narrow-area (i.e.
linear) illumination beam into the near-field portion 24A and far-field
portion 24B of the field of view of the system, respectively.
[0477] One of advantages of using a pair of independent illumination
arrays to produce narrow-area illumination fields over near and
far field portions of the FOV is that it is possible to more tightly
control the production of a relatively "narrow" or "narrowly-tapered"
narrow-area illumination field along its widthwise dimension. For
example, as shown in FIG. 27B, during bar code menu reading applications,
the near-field narrow area illumination array 27A can be used to
generate (over the near-field portion of the FOV) an illumination
field 24A that is narrow along both its widthwise and height-wise
dimensions, to enable the user to easily align the illumination
field (beam) with a single bar code symbol to be read from a bar
code menu of one type or another, thereby avoiding inadvertent reads
of two or more bar code symbols or simply the wrong bar code symbol.
At the same time, the far-field narrow area illumination array 27B
can be used to generate (over the far-field portion of the FOV)
an illumination field 24B that is sufficient wide along its widthwise
dimension, to enable the user to easily read elongated bar code
symbols in the far-field portion of the field of view of the bar
code reader, by simply moving the object towards the far portion
of the field.
Third Illustrative Embodiment of Digital Imaging-Based Bar Code
Symbol Reading Device of the Present Invention
[0478] Alternatively, the Imaging-Based Bar Code Symbol Reading
Device of the present invention can have virtually any type of form
factor that would support the reading of bar code symbols at diverse
application environments. One alternative form factor for the bar
code symbol reading device of the present invention is shown in
FIGS. 29A through 29C, wherein a portable Digital Imaging-Based
Bar Code Reading Device of the present invention 1'' is shown from
various perspective views, while arranged in a Presentation Mode
(i.e. configured in Programmed System Mode No. 12).
The Digital Imaging-Based Bar Code Reading Device of the Present
Invention
[0479] As shown in FIG. 30, the Digital Imaging-Based Bar Code
Reading Device of the present invention 1', 1''can also be realized
in the form of a Digital Imaging-Based Bar Code Reading Engine 100
that can be readily integrated into various kinds of information
collection and processing systems. Notably, trigger switch 2C shown
in FIG. 30 is symbolically represented on the housing of the engine
design, and it is understood that this trigger switch 2C or functionally
equivalent device will be typically integrated with the housing
of the resultant system into which the engine is embedded so that
the user can interact with and actuate the same. Such Engines according
to the present invention can be realized in various shapes and sizes
and be embedded within various kinds of systems and devices requiring
diverse image capture and processing functions as taught herein.
Illustrative Embodiment of a Wireless Bar Code-Driven Portable
Data Terminal (PDT) System of the Present Invention
[0480] FIGS. 31, 32 and 33 show a Wireless Bar Code-Driven Portable
Data Terminal (PDT) System 140 according to the present invention
which comprises: a Bar Code Driven PDT 150 embodying the Digital
Imaging-Based Bar Code Symbol Reading Engine of the present invention
100, described herein; and a cradle-providing Base Station 155.
[0481] As shown in FIGS. 31 and 32, the Digital Imaging-Based Bar
Code Symbol Reading Engine 100 can be used to read bar code symbols
on packages and the symbol character data representative of the
read bar code can be automatically transmitted to the cradle-providing
Base Station 155 by way of an RF-enabled 2-way data communication
link 170. At the same time, robust data entry and display capabilities
are provided on the PDT 150 to support various information based
transactions that can be carried out using System 140 in diverse
retail, industrial, educational and other environments.
[0482] As shown in FIG. 32, the Wireless Bar Code Driven Portable
Data Terminal System 140 comprises: a hand-supportable housing 151;
Digital Imaging-Based Bar Code Symbol Reading Engine 100 as shown
in FIG. 30, and described herein above, mounted within the head
portion of the hand-supportable housing 151; a user control console
151A; a high-resolution color LCD display panel 152 and drivers
mounted below the user control console 151A and integrated with
the hand-supportable housing, for displaying, in a real-time manner,
captured images, data being entered into the system, and graphical
user interfaces (GUIs) generated by the end-user application running
on the virtual machine of the wireless PDT; and PDT computing subsystem
180 contained within the PDT housing, for carrying out system control
operations according to the requirements of the end-user application
to be implemented upon the hardware and software platforms of the
wireless PDT 2B of this illustrative embodiment.
[0483] As shown in block schematic diagram of FIG. 34, a design
model for the Wireless Hand-Supportable Bar Code Driven Portable
Data Terminal System 140 shown in FIGS. 31 and 32, and its cradle-supporting
Base Station 155 interfaced with possible host systems 173 and/or
networks 174, comprises a number of subsystems integrated about
a system bus, namely: a data transmission circuit 156 for realizing
the PDT side of the electromagnetic-based wireless 2-way data communication
link 170; program memory (e.g. DRAM) 158; non-volatile memory (e.g.
SRAM) 159; Digital Imaging-Based Bar Code Symbol Reading Engine
100 for optically capturing narrow and wide area images and reading
bar code symbols recognized therein; a manual data entry device
such as a membrane-switching type keypad 160; LCD panel 152; an
LCD controller 161; LCD backlight brightness control circuit 162;
and a system processor 163 integrated with a systems bus (e.g. data,
address and control buses). Also, a battery power supply circuit
164 is provided for supplying regulated power supplies to the various
subsystems, at particular voltages determined by the technology
used to implement the PDT device.
[0484] As shown in FIG. 34, the Base Station 155 also comprises
a number of integrated subsystems, namely: a data receiver circuit
165 for realizing the base side of the electromagnetic-based wireless
2-way data communication link 170; a data transmission subsystem
171 including a communication control module; a base station controller
172 (e.g. programmed microcontroller) for controlling the operations
of the Base Station 155. As shown, the data transmission subsystem
171 interfaces with the host system 173 or network 174 by way of
the USB or RS232 communication interfaces, TCP/IP, AppleTalk or
the like, well known in the art. Taken together, data transmission
and reception circuits 156 and 165 realize the wireless electromagnetic
2-way digital data communication link 170 employed by the wireless
PDT of the present invention.
[0485] Notably, Wireless Hand-Supportable Bar Code Driven Portable
Data Terminal System 140, as well as the POS Digital Imaging-Based
Bar Code Symbol Reader 1'' shown in FIGS. 29A through 29C, each
have two primary modes of operation: (1) a hands-on mode of operation,
in which the PDT 150 or POS Reader 1'' is removed from its cradle
and used as a bar code driven transaction terminal or simply bar
code symbol reader; and (2) a hands-free mode of operation, in which
the PDT 150 or POS Reader 1'' remains in its cradle-providing Base
Station 155, and is used a presentation type bar code symbol reader,
as required in most retail point-of-sale (POS) environments. Such
hands-on and hands-free modes of system operation are described
in greater detail in copending U.S. patent application Ser. No.
10/684,273 filed on Oct. 11, 2003, and incorporated herein by reference
in its entirety.
[0486] In such hands-on and hands-free kinds of applications, the
trigger switch 2C employed in the Digital Imaging Bar Code Symbol
Reading Device of the present invention can be readily modified,
and augmented with a suitable stand-detection mechanism, which is
designed to automatically configure and invoke the PDT 150 and its
Engine 100 into its Presentation Mode (i.e. System Mode of Operation
No. 12) or other suitable system mode when the PDT is placed in
its Base Station 155 as shown in FIG. 33. Then when the PDT 150
is picked up and removed from its cradling supporting Base Station
155 as shown in FIGS. 31 and 32, the trigger switch 2C and stand-detection
mechanism, arrangement can be arranged so as to automatically configure
and invoke the PDT 150 and its Engine 100 into a suitable hands-on
supporting mode of system operation (selected from the Table set
forth in FIGS. 26A and 26B), to enable hands-on mode of operation.
[0487] Similarly, the trigger switch 2C employed in the POS Digital
Imaging Bar Code Symbol Reading Device 1'' can be readily modified,
and augmented with stand-detection mechanism, which is designed
to automatically configure and invoke the POS Reader 1'' into its
Presentation Mode (i.e. System Mode of Operation No. 12) or other
suitable system mode, when the Reader 1'' is resting on a countertop
surface, as shown in FIGS. 29A and 29B. Then when the POS Reader
1'' is picked up off the countertop surface, for use in its hands-on
mode of operation, the trigger switch 2C and stand-detection mechanism,
arrangement will automatically configure and invoke Reader 1'' into
a suitable hands-on supporting mode of system operation, as shown
in FIG. 29C. In such embodiments, the stand-detection mechanism
can employ a physical contact switch, or IR object sensing switch,
which is actuated then the device is picked up off the countertop
surface. Such mechanisms will become apparent in view of the teachings
disclosed herein.
Modifications which Readily Come to Mind
[0488] In alternative embodiments of the present invention, illumination
arrays 27, 28 and 29 employed within the Multi-Mode Illumination
Subsystem 14 may be realized using solid-state light sources other
than LEDs, such as, for example, visible laser diode (VLDs) taught
in great detail in WIPO Publication No. WO 02/43195 A2, published
on May 30, 2002, assigned to Metrologic Instruments, Inc., and incorporated
herein by reference in its entirety as if set forth fully herein.
However, when using VLD-based illumination techniques in the Imaging-Based
Bar Code Symbol Reader of the present invention, great care must
be taken to eliminate or otherwise substantially reduce speckle-noise
generated at the image detection array 22 when using coherent illumination
source during object illumination and imaging operations. WIPO Publication
No. WO 02/43195 A2, supra, provides diverse methods of and apparatus
for eliminating or substantially reducing speckle-noise during image
formation and detection when using VLD-based illumination arrays.
[0489] While CMOS image sensing array technology was described
as being used in the preferred embodiments of the present invention,
it is understood that in alternative embodiments, CCD-type image
sensing array technology, as well as other kinds of image detection
technology, can be used.
[0490] The bar code reader design described in great detail hereinabove
can be readily adapted for use as an industrial or commercial fixed-position
bar code reader/imager, having the interfaces commonly used in the
industrial world, such as Ethernet TCP/IP for instance. By providing
the system with an Ethernet TCP/IP port, a number of useful features
will be enabled, such as, for example: multi-user access to such
bar code reading systems over the Internet; control of multiple
bar code reading system on the network from a single user application;
efficient use of such bar code reading systems in live video operations;
web-servicing of such bar code reading systems, i.e. controlling
the system or a network of systems from an Internet Browser; and
the like.
[0491] While the illustrative embodiments of the present invention
have been described in connection with various types of bar code
symbol reading applications involving 1-D and 2-D bar code structures,
it is understood that the present invention can be use to read (i.e.
recognize) any machine-readable indicia, dataform, or graphically-encoded
form of intelligence, including, but not limited to bar code symbol
structures, alphanumeric character recognition strings, handwriting,
and diverse dataforms currently known in the art or to be developed
in the future. Hereinafter, the term "code symbol" shall
be deemed to include all such information carrying structures and
other forms of graphically-encoded intelligence.
[0492] Also, Imaging-Based Bar Code Symbol Readers of the present
invention can also be used to capture and process various kinds
of graphical images including photos and marks printed on driver
licenses, permits, credit cards, debit cards, or the like, in diverse
user applications.
[0493] It is understood that the image capture and processing technology
employed in bar code symbol reading systems of the illustrative
embodiments may be modified in a variety of ways which will become
readily apparent to those skilled in the art of having the benefit
of the novel teachings disclosed herein. All such modifications
and variations of the illustrative embodiments thereof shall be
deemed to be within the scope and spirit of the present invention
as defined by the Claims to Invention appended hereto.
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