Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PATENT APPLICATION
IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
(Attorney Docket Nos. 10052US04; DN37955XC)
TITLE: CODE READER FOR COhv~n ING TWO-DIMENSIONAL
INFORMATION INTO A ONE-DIMENSIONAL FORMAT
CROSS-REFERENCE TO RELATED APPLICATION
The present application is a continuation-in-part of copending
U.S. Application Serial No. 08/284,883 (Attorney Docket Nos.
10052US03 and DN37955W) filed July 28, 1994, which is a
continuation of U.S. Applica~tion Serial No. 08/277,132 (Attorney
Docket Nos. 10052US02 and DN37955XB) filed July 19, l9g4 by Dennis
A. Durbin, which is itself a continuation of U.S. Application
Serial No. 07/919,488 (Attorney Docket Nos. 92P540 and DN37955XA),
filed July 27, 1992 by Dennis A. Durbin, which is a continuation-
in-part of (i) U.S. Application Serial No. 07/849,771 (Attorney
Docket No. 92P254), filed March 12, 1992, and (ii) U.S. Application
Serial No. 07/889,705 (Attorney Docket No. 92P402), filed May 26,
1992.
This application is also a continuation-in-part of U.S.
Application Serial No. 08/241,866 (Attorney Docket Nos. 10156US06
and DN38010C), filed May 11, 1994 by Vadim Laser, which is itself
a continuation-in-part of U.S. Application Serial No. 08/170,120,
filed December 17, 1993, which is continuation-in-part of U.S.
Application Serial No. 08/067,384, filed May 25, 1993, which in
turn is a continuation-in-part of U.S. Application Serial No.
08/060,404, filed May 11, 1993.
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INCORPORATION BY REFERENCE
Applicant hereby incorporates by reference the following
patent applications in their entirety:
(1) U.S. Application Serial No. 08/284,883 (Attorney Docket
Nos. 10052US03 and DN37955W) filed July 28, 1994.
(2) U.S. Application Serial No. 08/277,132 (Attorney Docket
Nos. 10052US02 and DN37955XB) filed July 19, 1994.
(3) U.S. Application Serial No. 07/919,488 (Attorney Docket
Nos. 92P540 and DN37955XA), filed July 27, 1992.
(4) U.S. Application S~rial No. 07/849,771 (Attorney Docket
No. 92P254), filed March 12, 1992.
(5) U.S. Application Serial No. 07/889,705 (Attorney Docket
No. 92P402), filed May 26, 1992.
(6) U.S. Application Serial No. 08/241,866 (Attorney Docket
Nos. 10156US06 and DN38010C), filed May 11, 1994.
(7) U.S. Application Serial No. 08/170,120, filed December
17, 1993.
(8) U.S. Application Serial No. 08/067,384, filed May 25,
1993.
(9) U.S. Application Serial No. 08/060,404, filed May 11,
1993.
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R~K~,ROUND OF THE l~.V~h-~ ION
1. Technical Field
The present invention is directed to optical information
readers and more particularly to readers which decode two-
dimensional optical information.
2. Description of the Prior Art
Conventional bar code symbols have small data storage
capacities. This reduces the utility of conventional bar code
scanner and reader systems. For example, the 11 digit Uniform
Pricing Code found on most supermarket items acts as an identifying
number which may be utilized to access information in a database.
Code readers and associated database terminals have been developed
to read and process such codes.
In particular, conventional code readers are used to read and
pre-process one-dimensional codes. Thereafter, the code readers
send the resultant pre-processed code information to associated
conventional terminals for further processing. Some conventional
code readers, such as wand readers, send undecoded signals
representing the one-dimensional code information to a first type
of associated terminal for decoding. Other conventional code
readers, such as laser scanning, LED or flash type one-dimensional
code readers, send decoded code information to a second type of
associated terminal that recognizes the information as being
decoded. Because of the availability of such conventional one-
dimensional bar code readers, conventional terminals of one type or
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the other have been built and installed in great numbers throughout
the retail sales and inventory environments.
More recently, two-dimensional bar code symbols or "portable
data files" and corresponding two-dimensional code readers have
been developed. In fact, several two-dimensional coding standards
have been proposed such as Code 49, 16K, Identicode MLC-2D, and
Code PDF417, for example. Two-dimensional codes are capable of
storing much more information than a one-dimensional code. For
example, a two-dimensional code may contain such information as
price, name of product, manufacturer, weight, expiration date,
inventory data, shipping information, and the like, while a one-
dimensional code may only contain an ASCII string which must be
cross-referenced into a database on a terminal to extract such
information. However, there are very few terminals available which
can receive and further process two-dimensional bar code
information. Thus, if a retailer, for example, decides to upgrade
to using two-dimensional code readers, the retailer is forced to
also purchase a two-dimensional code processing terminal and throw
out the currently used one-dimensional code processing terminal.
3. Ob~ects of the Invont~on
Therefore, it is a principal object of the present invention
to provide a two-dimensional code reader which can be used with any
type of terminal.
Another object of the present invention is to provide a code
reader which can be programmed for use with any type of terminal.
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Another object of the present invention is to provide a code
reader which automatically identifies the type of terminal attached
thereto and automatically configures itself to conform its output
to that which the terminal expects.
Other objects and advantages of the invention will become
apparent to those skilled in the art upon reading the following
specification and claims.
SUMMARY OF THE INV~h~ION
A two-dimensional code reader sytem converts two-dimensional
code information into a one-dimensional format usable by an
attached terminal. Specifically, a code reader unit reads and
decodes information from a two-dimensional code. The reader unit
contains autodetection circuitry which detects and identifies a
terminal which is communicatively coupled to the reader unit. The
reader unit also cotains communication control circuitry which, in
response to indications from the autodetection circuitry, converts
the two-dimensional information into a one-dimensional format
usable by the coupled terminal.
BRIEF DESCRIPTION OF T~E DRAWINGS
Figure 1 is a perspective view of a preferred embodiment of
the two-dimensional optical information reader showing a user being
assisted by the display of the reader in aiming;
Figure 2 is a partial top perspective view of the reader
illustrating the display wherein the display indicates to a user
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that a two-dimensional, decodable, bar code symbol may be read if
the user adjusts the aim of the reader to the left and above;
Figure 3 is a partial top perspective view of the reader
illustrating the display wherein the display indicates to a user
that a two-dimensional, decodable bar code symbol is centered in
view and available for reading;
Figure 4 is a highly diagrammatic perspective view of the
image capturing elements of a linear array exemplary embodiment of
the present invention;
Figure 5 is a highly diagrammatic perspective view of the
image capturing elements of a two-dimensional array exemplary
embodiment of the present inventiont
Figure 6 is a block diagram illustrating the various
components of the present invention; and
Figure 7 is a more detailed block diagram illustrating the
various components of the present invention.
Figure 8 illustrates an embodiment of the present invention
wherein two-dimensional code information is converted where
necessary into either a decoded or undecoded one-dimensional code
format.
Figure 9 illustrates an embodiment of the present invention
wherein the optics and code reading circuitry are attached to a
hand held data capture terminal in an alternate configuration.
Figures lOa and lOb illustrate three embodiments of the
autodetection functionality of the present invention.
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DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS
Exemplary two-dimensional bar code readers are illustrated in
two embodiments as illustrated in Figures 1 through 7.
Specifically, Figures 1, 4, 6, and 7 illustrate one type of two-
dimensional bar code reader, while Figures 1, 5, 6, and 7 represent
another. Both embodiments teach the construction and use of
readers capable of decoding "portable data files."
Each exemplary embodiment utilizes image capture means,
pattern recognition means, and a real time display for assisting a
user in aiming, recognizing, confirming decodability, and decoding
two-dimensional bar code symbols. The embodiments differ primarily
in the particular construction and operation of their image capture
means. A further image capture means is disclosed in U.S.
Application Serial No. 08/241,866 (Attorney Docket Nos. 10156US06
and DN38010C), filed May 11, 1994, which is incorporated herein by
reference in its entirety.
In particular, in a first exemplary embodiment lO the image
capture means 12 utilizes a one-dimensional photosensitive array 14
to read images in a horizontal (X) direction and mechanical means
16 to read images in a vertical direction. Conversely, in a second
exemplary embodiment 100 the image capture means 112 utilizes a
two-dimensional photosensitive array 114 to read images in
horizontal (X) and vertical (Y~ directions (Figure 5).
Turning to the first exemplary embodiment lO, having image
capture means 12, best illustrated in Figure 4, vertical components
16 of a two-dimensional bar code symbol 20 are read by rastering
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succeeding horizontal components 18 across a single line
photosensitive array 14. This is accomplished, in such an
exemplary embodiment, via a mirror 22 rotatably mounted about its
horizontal plane. The mirror 22 is rotatably connected and driven
by mirror control means 24. In a preferred exemplary embodiment an
extremely low mass mirror prism (22) may be utilized and driven by
solenoids, a piezo, or the like (24).
In this embodiment 10, an expanded 5,000 pixel single line
photosensitive array 14 may be utilized. However, a 2,048 pixel
one-dimensional line photosensitive array would also work with a
reduced range. A special photosensitive array might also be
designed with faster scan line times and reduced power
requirements.
Vertical raster (Y) is variable under microprocessor 26
control (Figure 6). Likewise, the readout speed of the
photosensitive array 14 is variable under microprocessor 26 control
wherein the readout is preferably based on analyzed data recovered
on each scan. Likewise, integration time and gain of sense
amplifiers and filters acting on the photosensitive array 14 data
may also be variable under microprocessor 26 control.
Additionally, an electronic option to read lower density bar
code symbols could also be incorporated wherein every other, every
third, or every fifth pixel might be read. Likewise, an electronic
option to read high density short strings might also be
incorporated wherein the left 1666, then center 1666, and then
right 1666 pixels are read.
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In another exemplary species of this embodiment lO the
photosensitive array shift register drives are built into the
array. Electronic control of each charge well might also be
provided such that wells not in use would not exist to the
microprocessor 26. Such a configuration prevents dark currents
from filling empty wells. Additionally, wells might also be
created by the microprocessor 26 just prior to use. Thus, no
special cleaning cycles will be necessary.
In another exemplary species of this embodiment lO the
interface could be more parâllel wherein multiple photosensitive
array 14 shift sections could each shift out their own output, for
example, five outputs (each shifting 1000 pixels), or ten at 500
pixels, etc. Such a design would also utilize square pixel
dimensions in order to maintain equal vertical and horizontal
density.
The image capture means 12 may also include autofocus means.
Autofocus could be accomplished via infrared or ultrasonic
independent means, or via the use of photosensitive array scans in
order to m~i mi ze transition sharpness of the received image, or
the like. Likewise, the image capture means 12 would also include
zoom controlled by the user.
Aiming of the reader 10 would be accomplished by physical
proximity for close range (contact to two inches). The use of
spotter beams is not desired because of their additional cost and
tendency to washout in lighted areas. Aiming of the reader 10 for
long range would be accomplished via a display 28 (< 1 to 20 plus
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feet). The display 28, in a preferred exemplary embodiment 10,
would be a one inch CAT, dedicated LCD graphics screen, or even a
terminal screen on an integrated scanner.
In such an embodiment 10 low resolution scanning may be
performed while aiming. Image processing techniques would then be
utilized to display lines and shadows with sufficient aiming detail
(Figures 1, 2, and 3). The microprocessor 26 would then utilize
pattern recognition techniques to locate rectangular shapes (or
other information encoded shapes). Where the microprocessor 26
locates rectangular shapes (or other information encoded shapes)
which might be decodable bar code symbols, the closest such shape
to the center of the reader 10 window 30 would then be displayed on
the display 28 in a highlighted manner, e.g., flashing, reverse
video, or the like. During this same time period the
microprocessor 26 may also make an attempt to decode the contents
within the highlighted area. Then, if the decode attempt is
successful, the highlighted area could return to normal, or the
like, in order to notify the user that the decode was successful
and that the user may either accept or reject the data. If the
data is from the wrong bar code symbol, or the wrong portion of a
correct bar code symbol, then the user may aim at a new area
without accepting the data.
The use of zoom during aim induces jitter, therefore, in order
to overcome this problem, more data may be scanned thàn is viewed
on the display 28. If 1,000 pixels are collected but only 700 are
viewed on the display 28, then the microprocessor 26 may compare
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general patterns of each scan to detect motion and adjust the data
sent to the display 28 to compensate for the motion. Additionally,
as the displayed portion of the collected pixel picture reaches a
boundary of the pixel picture, then the displayed picture would
start to move such that the center of the collected data is then
shown as the displayed picture. In another species of an exemplary
embodiment 10 all rectangular areas within the displayed area may
be highlighted to indicate to a user which areas are probable bar
codes, and may annunciate that bar code symbol, or portion thereof,
which the microprocessor 26 is currently attempting to decode.
Illumination might come from an internal source, LED's or
such, where the light 34 would be on continuously during the aiming
and decoding. The light 34 would be variable under processor
control in order to reduce power consumption. Additionally, local
illumination would only be necessary over a nominal distance.
Beyond this, ambient light would contribute more and more of the
actual bar code illumination. While indoors, flood lighting or
indoor overhead lights would be necessary. The intention of this
design is such that if the user can see the bar code, the reader 10
will also, and decoding is possible.
Neural network and fuzzy logic processor programming and
hardware design/architecture are both required. Digital signal
processing techniques may also be used to help improve the basic
data collected as far as signal level normalization within the bar
code rectangular areas, taking advantage of bar codes still being
printed in 2 colors only. Neural network concepts of weighted
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inputs and highly parallel processing would then be used during
aiming and during a search for potential bar code 20 rectangles.
The use of concise dedicated functional neural processor, each
with a single function, all reduced to silicon and all placed in a
single ASIC is preferred. In this manner, 20 microprocessors,
wherein one looks for a vertical line, another for a horizontal
line, and another for angles, and the like, could all examine the
same data base at the s~me time. Very high speed data (image)
evaluation will also be utilized in a preferred embodiment for both
aiming and decoding. The same microprocessors could also be
responsible for power control in the image capture means 12.
Additionally, it is preferred that not all processing functions be
powered at all times or at the same time. Also, illumination would
end and count (data) collection would cease after data was decoded.
A communication processor could also be provided and such
communication processor could be functional until data was
transferred.
A typical operation might be as follows: The user directs the
reader 10 toward the bar codes 20 to be read (Figure 1). The user
pulls a trigger means 40 to activate the aiming sequence. The user
views the display 28 to verify reader 10 aim. The reader 10 auto
focuses, starting with the focus setting of the previous read. The
user views the display 28 and moves the reader 10 and starts to
zoom as necessary as the desired bar code symbol 20 comes into view
(Figure 2). The reader 10 continues to show the viewed field in
the display 10 even as it decodes the bar code symbol 20. The
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2:1~7~54
reader 10 highlights the decoded bar code symbol 20 (Figure 3).
The user may accept the decoded data via the trigger means 40, or
the like. If the user does not want the data, he or she may move
the reader 10 such that another desired bar code symbol 20 is
centered and highlighted as decoded, or such that no bar code is
highlighted and no decode would occur.
This feature is very beneficial in that one bar code can be
selected on a page containing many adjacent codes without the
sometimes impossible requirement of ensuring the scan line (laser)
goes through only the desired code.
Figure 7 is a block diagram illustrating the functional block
organization of an exemplary two-dimensional bar code reader of
according to the present invention. The optic string 200 allows
for image focus and zoom. Both focus and zoom management are
provided by the control processor 202. The input switches 204,
such as the trigger 40, may be utilized to enable the scan
function, or the like. While in the scan mode, focusing may be
achieved according to at least two methods. As shown, there is a
focus block function 206 which may utilize a separate range
detection circuit (i.e., such as ultra-sonic or infra-red ranging
means). This is the first type of focusing method. This method
allows the control processor 202 to determine the range of an image
from the scanner and move the lens assembly 208 accordingly without
powering up, or at least without operating the image sensor 210
circuitry, data analyzing means 212, and display 214. In this
fashion battery power is conserved. The second type of focusing
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method utilizes the image sensor 210/processing means 212 to detect
a lack of focus by data frequency analysis, i.e., moving the lens
assembly 208 in order to m~;m;ze the high frequency content of the
image data. The second type of focusing requires fewer parts, but
more power and the initial corrective movement may be in an
incorrect direction. Using past direction history will improve
chances of correct initial direction choice. Also any optically
required focus adjustments due to zoom changes may be obtained from
a look-up table within the control means and included in the
control of focus during zoom changes.
The image sensor may be either a single line several thousand
pixel sensor (from at least 1000 to 5000 pixels depending on scan
requirements) or an array sensor with from at least 500 to 1500
pixels in both the X and Y axis. The preferred mode is to utilize
an array sensor since it is both faster and requires fewer moving
parts. However, cost and power requirements are greater with an
array sensor.
As previously discussed, a one dimensional array requires
motion in the orthogonal direction to the pixel layout in order to
obtain a 2-D image. The pixels in both sensors are square in
dimension in order to maintain relative dimensions in both X and Y
directions. One method of providing vertical dithering (back and
forth) is via a piezo element driven mirror within a folded optic
path. However, a rotating polygon cylinder may also be utilized.
In order to reduce power and gain speed in honing in on an
image, both image sensor methods allow partial reading of the
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sensor fields. This means that during a line scan of a one line
sensor, a programmably controlled number of pixels are skipped
within the sensor on a cyclic basis in order to obtain less dense
scan information more rapidly. For instance, reading only every
other, every third, or every fifth pixel means less taken to
process the data. A less detailed image is acquired, but speed,
not great detail is required for general aiming and setup. In the
vertical direction, the mirror is moved further between samples to
compensate for the partial pixel sample and in order to keep
spatial relationships constant. With a two-dimensional array, the
same partial pixel viewing is done in both directions at the same
rate. Both sensor types allow controlled exposure time independent
of cycle time.
The control processor means contains at least one
microprocessor. The control processor is responsible for
controlling focus, zoom, illumination (if necessary), sensor
timing, power management, and communication to other system blocks.
The control processor utilizes fuzzy logic decision structures to
quickly focus and to analyze the overall image pattern. It is also
responsible for controlling the sensor when retrieving high density
pixel strings from portions of the sensor. This is useful when a
low density pixel scan has enabled the processing function means to
recognize a potentially decodable shape. A m~;mum density scan is
then done over that portion of the sensor to try to determine if
decode is possible. These high density scan portions might consist
of the left, center, and right sections of the sensor. this may
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also be accomplished by programming start and stop points within
the sensor to control which section is retrieved.
Under zoom conditions, user movement will be more apparent and
objectionable. The processing function means controls the image
sent to the display for assisting the user in aiming the scanner
unit. The processing function means helps remove jitter caused by
user motion by modifying the image sent to the display. The image
sent to the display is a smaller portion of the actual scanned
image. Fuzzy logic structures are again used to quickly determine
patterns and shapes and track their movement. The smaller (or
subset) image that is displayed remains, positioned as is, in the
display until the displayed image bumps up against a border of the
true collected image. Then the display image starts to move to the
rate of user movement. The processor means is continually working
to reduce jitter while also trying to recognize and decode
potentially decodable images. It also enunciates potentially
decodable images in the display, for instance surrounding an image
with a solid outline, and marks fully decoded images in another
manner, such as reverse video.
Communication control means 220 communicates with the control
and processing means to provide interface to a host system. The
communication control means 220 may also have its own
microprocessor for handling protocol and data transfer. Further
detail regarding the communication control means 220 can be found
in reference to Figure lOa and lOb below.
Fig. 8 illustrates an embodiment of the present invention
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wherein two-dimensional code information is converted where
necessary into either a decoded or undecoded one-dimensional code
format. Specifically, a code reader 801 is shown which receives
reflected light from two-dimensional code information such as that
shown on a two-dimensional code 803. Boards 805 and 807 located
within the code reader 801 contain an optics assembly, sensor, and
processing circuitry operable for reading and decoding the
information represented by the received reflected light. The
components on boards 805 and 807 may also, of course, be on a
single board.
The code reader 801 may be used in conjunction with any of the
terminals 809, 811, or 813. The terminal 809, for example,
represents one which can only read a wand-type data stream, while
the terminals 811 and 813 represent ones which can only read one-
dimensional decoded data and one-dimensional undecoded data (such
as is generated by a wand), respectively.
In one embodiment, the code reader 801 can be appropriately
configured using a keyboard and display, such as that illustrated
in Figure 1. Specifically, the keyboard and display can be used to
program the code reader 801 to utilize the appropriate
communication protocol needed to communicate with the attached
terminal.
In an alternate embodiment, the code reader 801 contains
autodetect circuitry (described in more detail below) which
identifies which type of terminal is attached. For example, the
code reader 801 may be configured with three connectors for
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receiving three cables 815, 817 and 819 so as to permit
communication with the terminals 809, 811 and 813. In this
embodiment, the autodetect circuitry need only determine which
connector is in use. Further detail regarding such autodetection
of this embodiment can be found below in reference to Figure lOb.
In yet another embodiment, detailed below in reference to
Figure lOa, the code reader 801 can be configured with a single
connector and autodetect circuitry capable of identifying the
attached terminal type by evaluating the signal lines from the
cables. Further detail for such evaluation can be found in
reference to Figure lOb below.
Figure 9 illustrates an embodiment of the present invention
wherein the optics and code reading circuitry are attached to a
hand held data capture terminal in an alternate configuration.
Specifically, a portable data collection terminal 901, like any of
the terminals illustrated in Figure 8, can be of any type, i.e.,
may only be capable of receiving one dimensional code information
for example. A code reader 903 operates identically to that
discussed in the previous Figures by reading and decoding two-
dimensional bar codes such as a bar code 905, and converting the
two-dimensional code information into an appropriate one-
dimensional format if necessary. However, the code reader 903 is
of a modular construction which may be inserted directly into a
receiving slot in the terminal 901 or may attach to a connector
located on the top of the terminal 901. Such a communication
interconnection would functionally operate, from an electrical
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standpoint, identically to that of a cabling interconnect as shown
in Figure 8. The terminal 901 is also configured with a keypad
907, a display 909 and a pen input 911.
Figures lOa and lOb illustrate three embodiments of the
autodetection functionality of the present invention. Figure lOa
illustrates three embodiments of the autodetection circuitry
necessary to identify whether an attached terminal can read two-
dimensional codes or only one-dimensional codes which are either
decoded or undecoded. Specifically, in Figure lOa, a terminal of
any of the variety of types is connected to a communication bus
1001 via a connector 1003. Specific lines in the communication bus
1001 are monitored by an autodetect circuit 1005. If no terminal
is detected by the autodetect circuit 1005, the autodetect circuit
1005 via a control bus 1007 causes a communication control circuit
to disable communication output on the communication bus 1001.
However, upon detecting and identifying the type o~ terminal
connected, the autodetect circuit 1005 provides an indication to
the communication control circuit 1009 of the terminal type via the
control bus 1007. The communication control circuit 1009 responds
by converting the two-dimensional code information, if necessary,
to a one-dimensional form, and provides appropriate output signals
along the control bus 1001 to communicate with the terminal
attached to the connector 1003.
More particularly, the autodetect circuit 1005 identifies
which lines of the communication bus 1001 appear to be (i)
grounded, (ii) tied to a positive power source, and (iii) toggling
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between states. From this information, the autodetect circuit
1005, using simple conventional logic, automatically determines
which type of terminal is connected. Moreover, the connectors from
the terminals may be modified to aid this type of autodetect
process.
In a second embodiment, instead of analyzing the states of the
incoming lines of the communication bus 1001, the autodetect
circuit 1005 instead attempts to establish communication to any
attached terminal by first setting up the communication control
circuit 1009 to assume the attached terminal can read two-
dimensional code information. Thereafter, the autodetect circuit
1005 monitors the results of an attempted communication. If the
communication attempt fails, the autodetect circuit 1005 makes a
second assumption that decoded, one-dimensional code information
can be sent, and sets up the communication control circuit 1009 via
the control bus 1007 accordingly. Again, if this communication
attempt fails, the autodetect circuit 1005 configures the
communication control circuit 1009 to communicate using undecoded,
one-dimensional code information (e.g., wand type signal streams).
In a third embodiment, characteristics of the previous two
embodiments are combined so that the autodetect circuit lOOS
evaluates the logic states of the lines of the communication bus
1001 to make initial determinations which are incomplete, but then
utilizes the communication failure procedure to make a final
selection.
Figure lOb illustrates yet another embodiment of the
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autodetect circuit of the present invention. As shown, instead of
one connector, the present embodiment utllizes three separate
connectors, connectors 1003A, 1003B and 1003C. Each connector
corresponds to one type of connector. For example, the connector
1003A only connects to a wand type terminal, while the connector
1003B only connects to a terminal which can receive decoded one-
dimensional codes, and so on. In this situation, the autodetect
circuit 1005A, by sensing the signal states of the lines of
communication buses lOOlA, lOOlB and lOOlC determines which
terminal is attached. In rêsponse, the autodetect circuit 1005A
communicates the identity of the type of terminal attached to the
communication control circuit 1009 via the control bus 1007. The
communication control circuit 1009 thereafter selects the
appropriate communication bus and determines whether a two-
dimensional code conversion is necessary. If the conversion is
necessary, the communication control circuit 1009 converts the code
into the corresponding counterpart data signals for transmission to
the attached terminal via the appropriate communication bus.
Additionally, although autodetection among three types of
terminals is disclosed, it would be clear to those of ordinary
skill in the art that additional terminal types could also be
automatically detected, and other corresponding appropriate
conversion and communication configurations could be added.
Thus, there has been shown and described an improved two-
dimensional optical information reader which accomplishes at least
the stated objects. While the invention has been described with a
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2i57~4
certain degree of particularity, it is manifest that many changes
may be made in the details of construction and the arrangement of
components without departing from the spirit and scope of the
disclosure. It is understood that the invention is not limited to
the embodiments set forth herein for purposes of exemplification,
but is to be limited only by the scope of the appended claims
including the full range of equivalency to which each element
thereof is entitled.
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