Business methods using an optical reader having partial frame operating mode

[0001] This application claims priority to, and is a continuation-in-part of co-pending U.S. patent application Ser. No. 09/766,806, filed Jan. 22, 2001, which application is incorporated herein by reference in its entirety.

[0002] The invention relates to optical readers in general and in particular to methods for operating an optical reader having a 2D image sensor.

[0003] Optical readers having 2D image sensors commonly are used to read both 1D and 2D symbols. Some optical readers having a 2D image sensor read a 1D symbol by capturing a 2D image representation, or frame of image data corresponding to a target area which comprises a 1D symbol, and launching a scan line or lines in order to attempt to decode for 1D symbols which may be represented in the area. Other optical readers having 2D image sensors read 1D symbols by capturing a 2D image representation of an area containing the 1D symbol, preliminarily analyzing the image data represented in the area to determine that the image data comprises a representation of a 1D symbol, and then launching a scan line in an attempt to decode for the 1D symbol determined to be present. In either case, a full frame 2D image representation is captured in order to decode for a 1D symbol.

[0004] Capturing a 2D image representation requires a substantial amount of time, especially in applications wherein one or more test frames of image data must be captured prior to capture of a frame that is subjected to processing. Furthermore, assuming a constant processing speed, the time required for an optical reader to capture a 2D image representation increases with the resolution of the image sensor which is incorporated in the reader. Currently available CMOS mega pixel image sensors have low frame clock out rates of about 15 frames per second (FPS).

[0005] A user's satisfaction with an optical reader often varies directly with the decoding speed of the optical reader. Given that higher resolution, including mega pixel readers, are expected to grow in popularity, the frame capture time will become an increasingly important factor for consideration in performance of an optical reader.

[0006] The invention relates to a method for configuring an optical reader having a 2D image sensor so the reader captures and processes image data at higher speeds. Capturing a 2D image representation requires a substantial amount of time, especially in applications wherein one or more test frames of image data must be captured prior to capture of a frame that is subjected to processing as has been explained in commonly assigned U.S. patent application Ser. No. 09/766,922, entitled Optical Reader Having Reduced Parameter Determination Delay, filed Jan. 22, 2001, and incorporated herein by reference in its entirety. A 1D or 2D symbol that represents information and that is amenable to imaging and being recognized using a 2D image sensor is referred to generically herein as an encoded indicium. Objects carrying 1D or 2D symbols indicative of the object's identity or quality, of the contents of an object (such as a package), or that provide other information, are frequently used in performing business or commercial activities. Higher speed is useful in commercial or business settings. Higher speed permits greater productivity per unit of time, and concomitantly, allows reductions in cost through reductions in the number of imaging devices and or personnel required to accomplish a given repetitive task.

[0007] As will be understood by those of ordinary skill, the terms commercial transaction and business transaction as used herein include both transactions that involve an agreement or promise for which consideration is exchanged and the activities that may be conducted in preparation for or in completion of such agreements, as well as interactions that are unilateral, such as the making of a gift (a promise for which consideration is not exchanged), or internal activities within an organization, such as maintaining inventory records, maintaining personnel records or records of assets, or other activities that an be categorized as overhead in a business context. Activities performed in governmental or quasi-governmental settings are also contemplated, such as the use of encoded indicia by such organizations as the United States Postal Service and the military, as well as by State and local governmental agencies.

[0008] In some embodiments, the encoded indicium is a symbol that comprises a plurality of fields or regions. An example of such an encoded indicium is a check or bank draft, which represents a payment of money, and which is a two-dimensional document having a plurality of fields, such as a date, a payee, an amount, a signature of a maker, and information regarding a financial institution holding the funds represented by the check, and an account against which the funds are payable.

[0009] According to the invention, a control circuit of an optical reader equipped with a 2D image sensor is configured to operate in a partial frame operating mode. In a partial frame operating mode, the control circuit clocks out and captures less than a full frame of image data and processes that image data. The control circuit may process the image data of the partial frame, for example, by reading the image data from memory and outputting the image data to an output location such as a display device or a processor system in communication with the reader, by reading and attempting to decode decodable symbols which may be recorded in the partial frame, or by reading and performing optical character recognition on characters represented in the partial frame of image data.

[0010] In one embodiment, the partial frame operating mode is employed to clock out and capture image data corresponding to at least one linear pattern sufficient so that a 1 D symbol in the field of view of the image sensor may be decoded without clocking out and capturing an entire frame of image data. The partial frame of image data that is clocked out from the image sensor during the partial frame capture operating mode may be, for example, a row of symbols at or near the center of the image sensor or a limited number of lines of image data corresponding to pixel locations of the image sensor, possibly at varying angular orientations. The control circuit may be configured so that if the control circuit cannot decode a 1D symbol during the course of operating in the partial frame capture mode, or detects that a 2D symbol is represented in the captured image data, the control circuit switches operation to a full frame capture mode.

[0011] In another embodiment, the partial frame operating mode is employed to clock out and capture pixel values corresponding to a grouping of pixels at or near a center of an image sensor other than a linear pattern of pixels. This embodiment may be advantageously employed in cases where decodable symbols are expected to be concentrated proximate a center of an image sensor's field of view. A control circuit may be configured so that if the control circuit cannot decode a symbol represented in the partial frame, or determines that a symbol is represented partially or entirely outside the image data of the partial frame, the control circuit automatically switches operation to a full frame image capture mode.

[0012] In one aspect, the invention features a method of conducting a business transaction involving information recorded in an encoded indicium. The method comprises the steps of operating an optical reader having a 2D image sensor; capturing with the 2D image sensor a partial frame of image data from an encoded indicium; and processing image data of the partial frame of image data to extract information encoded by the encoded indicium whereby the purposes of the business transaction are advanced.

[0013] In one embodiment, the capturing step includes the step of capturing image data corresponding to a linear pattern of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a plurality of angularly offset linear patterns of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a plurality of vertically spaced apart horizontally oriented linear patterns of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a grouping of pixels about a center of the image sensor. In one embodiment, the processing step includes the step of reading the image data out of a memory device. In one embodiment, the processing step includes the steps of reading the image data out of a memory device and attempting to decode for a decodable symbol which may be represented in the image data.

[0014] In one embodiment, the method further includes the step of capturing a full frame of image data if the processing step reveals that a 2D symbol is likely partially represented in the partial frame of image data.

[0015] In one embodiment, the method further includes the step of capturing an adaptively positioned partial frame of image data if the processing step reveals that a 2D symbol is likely partially represented in the partial frame of image data.

[0016] In one embodiment, the processing step includes the step of attempting to decode for a decodable symbol represented in the image data, the method further including the step of capturing a full frame of image data if the processing step reveals that a 2D symbol is likely partially represented in the partial frame of image data.

[0017] In another aspect, the invention relates to a method of conducting a business transaction involving information recorded in an encoded indicium. The method comprises the steps of: (a) operating an optical reader having a 2D image sensor; (b) in a partial frame operating mode, capturing a partial frame of image data, the partial from of image data including at least a portion of the encoded indicium; (c) attempting to extract information encoded by the encoded indicium from the captured partial frame of image data; and (d) if in step (c) the reader fails to extract information encoded by the encoded indicium, switching operation of the reader to a full frame capture mode.

[0018] In one embodiment, the capturing step includes the step of capturing image data corresponding to a linear pattern of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a plurality of angularly offset linear patterns of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a plurality of vertically spaced apart horizontally oriented linear patterns of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a grouping of pixels about a center of the image sensor.

[0019] In still another aspect, the invention relates to a method of conducting a business transaction involving information recorded in an encoded indicium. The method comprises the steps of: (a) operating an optical reader having a 2D image sensor; (b) in a partial frame operating mode, capturing a partial frame of image data, the partial from of image data including at least a portion of the encoded indicium; (c) attempting to extract information encoded by the encoded indicium from the captured partial frame of image data; and (d) if in step (c) the reader fails to extract information encoded by the encoded indicium, switching operation of the reader to a second partial frame capture mode.

[0020] In one embodiment, the capturing step includes the step of capturing image data corresponding to a linear pattern of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a plurality of angularly offset linear patterns of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a plurality of vertically spaced apart horizontally oriented linear patterns of pixels. In one embodiment, the capturing step includes the step of capturing image data corresponding to a grouping of pixels about a center of the image sensor. In one embodiment, the method further comprises the step of switching operation of the reader to a full frame operating mode if the reader fails to extract information encoded by the encoded indicium from data captured using the second partial frame capture mode.

[0021] In yet another aspect, the invention features an apparatus for conducting a business transaction involving information recorded in an encoded indicium. The apparatus comprises an optical reader having a 2D image sensor configured to image an encoded indicium; a control module configured to operate the 2D image sensor to capture a partial frame of image data from the encoded indicium; and a processing module configured to process the partial frame of image data to extract therefrom information encoded by the encoded indicium, whereby the purposes of the business transaction are advanced.

[0022] In one embodiment, the apparatus further comprises an analysis module configured to deduce that a 2D encoded indicium is present in the partial frame of image data. In one embodiment, the apparatus further comprises a control module that configures the 2D sensor to operate in a full frame operating mode.

[0023] In one embodiment, the apparatus further comprises a sensor module configured to sense that a 2D encoded indicium is present in the partial frame of image data. In one embodiment, the apparatus further comprises a control module that configures the 2D sensor to operate in a second partial frame operating mode.

[0024] The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.

[0025] The objects and features of the invention can be better understood with reference to the drawings described below, and the claims. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views.

[0026] FIGS. 1a-1g illustrate various image data patterns that may be captured by an optical reader operating in a partial frame capture mode according to the invention;

[0027] FIG. 2a is a block diagram of an optical reader of a type in which the invention may be incorporated;

[0028] FIGS. 2b-2h show various types of optical reader housings in which the invention may be incorporated;

[0029] FIG. 3 is a flow diagram showing an illustrative process in which a partial frame of an image of an encoded indicium is processed extract encoded information, according to principles of the invention;

[0030] FIG. 4 is another flow diagram showing an illustrative process in which a partial frame of an image of an encoded indicium is processed to extract encoded information, according to principles of the invention; and

[0031] FIG. 5 is yet another flow diagram showing an illustrative process in which a partial frame of an image of an encoded indicium is processed to extract encoded information, according to principles of the invention.

[0032] Encoded indicia, including 1D and 2D symbols such as bar codes, stacked bar codes, and two dimensional encoded symbologies, are commonly used in many business settings. Some representative examples include the labeling of goods and/or packages containing the goods, the use of encoded indicia to identify documents (for example patient records in a hospital or managed health care facility), and the use of encoded indicia to reduce the possibility of fraud or the use of counterfeit documents (such as the addition of encoded indicia to drivers' licenses). As already alluded to, some commonly used adjuncts to business transactions, such as checks or bank drafts, can also be considered as encoded indicia having a plurality of fields or regions in which encoded information is present.

[0033] Referring to FIGS. 1a-1g, there is shown an optical reader equipped with a 2D image sensor that is configured to operate in a partial frame capture mode. In a partial frame clock out mode, a control circuit of an optical reader clocks out (or reads) electrical signals corresponding to less than all of the 2D image sensor's pixels, and captures image data corresponding to the pixel locations into memory. It should be understood that while the 2D image sensor can view, or image, the entire area from which illumination is provided to its pixels, in the partial frame mode contemplated, only a subset of such pixels are actually interrogated or caused to provide electrical signals that are then used for analysis. The partial frame mode is controlled by a control module, as will be explained in greater detail below. The partial frame of image data is processed using a processing module configured to extract information encoded by the encoded indicium, as will be explained in greater detail below.

[0034] Partial frames of image data which may be clocked out and captured by an optical reader control circuit (or control module) during a partial frame capture mode are illustrated in FIGS. 1a-1g in which valid zones 12 represent frame image data corresponding to image sensor pixel positions that are clocked out and invalid zones 14 represent potential image data positions corresponding to pixel positions that are not clocked out.

[0035] Border 10 defines the full field of view of an optical reader in the case the reader is operated in a full frame captured mode while symbols 16-1, 16-2, 16-3, 16-4, 16-6 and 16-7 are symbols entirely within the full field of view of an optical reader defined by border 10 but are only partially within certain valid zones shown. Valid zones 12-1, 12-3, 12-7, 12-8, 12-9, 12-10, and 12-13 are valid zones of image data that partially contain representations of a decodable symbol while valid zones 12-11 and 12-12 are valid zones of image data captured during a partial frame capture mode which contain representations of an entire decodable symbol.

[0036] In the examples illustrated with reference to FIGS. 1a-1d an optical reader operating in a partial frame clock out mode clocks out electrical signals corresponding to linear patterns of pixels. It is useful to cause a reader to clock out electrical signals corresponding to linear patterns as shown in FIGS. 1a-1d when a reader will be used to decode mainly 1D linear bar code symbols.

[0037] In the examples illustrated with reference to FIGS. 1e, 1f and 1g an optical reader operating in a partial frame clock out mode clocks out electrical signals corresponding to non-linear groupings of pixels. It is useful to cause a reader to clock out electrical signals corresponding to pixel groupings as shown in FIGS. 1e, 1f and 1g when a reader will be used to decode symbols which are expected to be within a certain position in an image sensor's field of view.

[0038] A reader may be configured so that the reader automatically switches out of partial frame capture mode on the sensing of a certain condition. For example a reader according to the invention may be made to switch out of partial frame capture operating mode and into a full frame capture mode on the sensing that a 2D symbol is partially represented in the partial frame of image data, or on the condition that processing of the partial frame of image data fails to result in image data being decoded. The control module can control the mode of operation of the reader based upon instructions provided in a computer program operating on an electronic processor, and can cause the reader to operate in either of the partial frame capture mode or the full frame capture mode, as appropriate.

[0039] An optical reading system in which the invention may be employed is described with reference to the block diagram of FIG. 2a.

[0040] Optical reader 110 includes an illumination assembly 120 for illuminating a target object T, such as a 1D or 2D bar code symbol, and an imaging assembly 130 for receiving an image of object T and generating an electrical output signal indicative of the data optically encoded therein. Illumination assembly 120 may, for example, include an illumination source assembly 122, together with an illuminating optics assembly 124, such as one or more lenses, diffusers, wedges, reflectors or a combination of such elements, for directing light from light source 122 in the direction of a target object T. Illumination assembly 120 may comprise, for example, laser or light emitting diodes (LEDs) such as white LEDs or red LEDs. Illumination assembly 120 may include target illumination and optics for projecting an aiming pattern 127 on target T. Illumination assembly 120 may be eliminated if ambient light levels are certain to be high enough to allow high quality images of object T to be taken. Imaging assembly 130 may include an image sensor 132, such as a 1D or 2D CCD, CMOS, NMOS, PMOS, CID OR CMD solid state image sensor, together with an imaging optics assembly 134 for receiving and focusing an image of object T onto image sensor 132. The array-based imaging assembly shown in FIG. 2a may be replaced by a laser array based imaging assembly comprising multiple laser sources, a scanning mechanism, emit and receive optics, at least one photodetector and accompanying signal processing circuitry.

[0041] The partial frame clock out mode is readily implemented utilizing an image sensor which can be commanded by a control module to clock out partial frames of image data or which is configured with pixels that can be individually addressed. Using CMOS fabrication techniques, image sensors are readily made so that electrical signals corresponding to certain pixels of a sensor can be selectively clocked out without clocking out electrical signals corresponding to remaining pixels of the sensor. CMOS image sensors are available from such manufacturers as Symagery, Pixel Cam, Omni Vision, Sharp, National Semiconductor, Toshiba, Hewlett-Packard and Mitsubishi. A partial frame clock out mode can also be carried out by selectively activating a frame discharge signal during the course of clocking out a frame of image data from a CCD image sensor, as is explained in U.S. patent application Ser. No. 09/766,922, entitled Optical Reader Having Reduced Parameter Determination Delay, previously incorporated herein by reference.

[0042] Optical reader 110 of FIG. 2a also includes programmable control circuit (or control module) 140 which preferably comprises an integrated circuit microprocessor 142 and an application specific integrated circuit (ASIC 144). The function of ASIC 144 could also be provided by a field programmable gate array (FPGA). Processor 142 and ASIC 144 are both programmable control devices which are able to receive, to output and to process data in accordance with a stored program stored in memory unit 145 which may comprise such memory elements as a read/write random access memory or RAM 146 and an erasable read only memory or EROM 147. Other memory units that can be used include EPROMs and EEPROMs. RAM 146 typically includes at least one volatile memory device but may include one or more long term non-volatile memory devices. Processor 142 and ASIC 144 are also both connected to a common bus 148 through which program data and working data, including address data, may be received and transmitted in either direction to any circuitry that is also connected thereto. Processor 142 and ASIC 144 differ from one another, however, in how they are made and how they are used. The processing module that is configured to extract information encoded by the encoded indicium employs some or all of the capabilities of processor 142 and ASIC 144, and comprises the hardware and as necessary, software and or firmware, required to accomplish the extraction task, including as necessary decoding tasks to convert the raw data of the image to the information encoded in the encoded indicium.

[0043] More particularly, processor 142 is preferably a general purpose, off-the-shelf VLSI integrated circuit microprocessor which has overall control of the circuitry of FIG. 2a, but which devotes most of its time to decoding image data stored in RAM 146 in accordance with program data stored in EROM 147. Processor 144, on the other hand, is preferably a special purpose VLSI integrated circuit, such as a programmable logic array or gate array that is programmed to devote its time to functions other than decoding image data, and thereby relieves processor 142 from the burden of performing these functions.

[0044] The actual division of labor between processors 142 and 144 will naturally depend on the type of off-the-shelf microprocessors that are available, the type of image sensor which is used, the rate at which image data is output by imaging assembly 130, etc. There is nothing in principle, however, that requires that any particular division of labor be made between processors 142 and 144, or even that such a division be made at all. This is because special purpose processor 144 may be eliminated entirely if general purpose processor 142 is fast enough and powerful enough to perform all of the functions contemplated by the present invention. It will, therefore, be understood that neither the number of processors used, nor the division of labor there between, is of any fundamental significance for purposes of the present invention.

[0045] With processor architectures of the type shown in FIG. 2a, a typical division of labor between processors 142 and 144 will be as follows. Processor 142 is preferably devoted primarily to such tasks as decoding image data, once such data has been stored in RAM 146, recognizing characters represented in stored image data according to an optical character recognition (OCR) scheme, handling menuing options and reprogramming functions, processing commands and data received from control/data input unit 139 which may comprise such elements as trigger 174 (see FIG. 2f) and keyboard 178 (see FIG. 2g) and providing overall system level coordination.

[0046] Processor 144 is preferably devoted primarily to controlling the image acquisition process, the A/D conversion process and the storage of image data, including the ability to access memories 146 and 147 via a DMA channel. The A/D conversion process can include converting analog signals to digital signals represented as 8-bit (or gray scale) quantities. As A/D converter technology improves, digital signals may be represented using more that 8 bits. Processor 144 may also perform many timing and communication operations. Processor 144 may, for example, control the illumination of LEDs 122, the timing of image sensor 132 and an analog-to-digital (A/D) converter 136, the transmission and reception of data to and from a processor external to reader 110, through an RS-232, a network such as an Ethernet or other packet-based communication technology, a serial bus such as USB, and/or a wireless communication link (or other) compatible I/O interface 137. Processor 144 may also control the outputting of user perceptible data via an output device 138, such as a beeper, a good read LED and/or a display monitor which may be provided by a liquid crystal display such as display 182 (see FIGS. 2e and 2g). Control of output, display and I/O functions may also be shared between processors 142 and 144, as suggested by bus driver I/O and output/display devices 137 and 138 or may be duplicated, as suggested by microprocessor serial I/O ports 142A and 142B and I/O and display devices 137 and 138. As explained earlier, the specifics of this division of labor is of no significance to the present invention.

[0047] Some or all of the above optical and electronic components may be incorporated in an imaging module as are described in commonly assigned U.S. patent application Ser. No. 09/411,936, incorporated herein by reference in its entirety.

[0048] FIGS. 2b-2g show examples of types of housings in which the 2D imager of the present invention may be incorporated. FIGS. 2b-2g show 1D/2D optical readers 110-1, 110-2 and 110-3. Housing 112 of each of the optical readers 110-1 through 110-3 is adapted to be graspable by a human hand and has incorporated therein at least one trigger switch 174 for activating image capture and decoding and/or image capture and character recognition operations. Readers 110-1 and 110-2 include hard-wired communication links 179 for communication with external devices such as other data collection devices or a host processor, while reader 110-3 includes an antenna 180 for providing wireless communication to an external device or a host processor.

[0049] In addition to the above elements, readers 110-2 and 110-3 each include a display 182 for displaying information to a user and a keyboard 178 for enabling a user to input commands and data into the reader. Control circuit 140 may cause a graphical user interface (GUI) to be displayed on display 182. A pointer on the GUI may be moved by an actuator or actuators protruding from housing 112.

[0050] Any one of the readers described with reference to FIGS. 2b-2g may be mounted in a stationary position as is illustrated in FIG. 2h showing a generic optical reader 110 docked in a scan stand 190. Scan stand 190 adapts portable optical reader 110 for presentation mode scanning. In a presentation mode, reader 110 is held in a stationary position and an indicium-bearing article is moved across the field of view of reader 110. By comparison, in a hand-held mode, the reader 110 is manually positioned so that the 2D imager can view an encoded indicium within a target area of the reader.

[0051] As will become clear from the ensuing description, the invention need not be incorporated in a portable optical reader. The invention may also be incorporated, for example, in association with a control circuit for controlling a non-portable fixed mount imaging assembly that captures image data representing image information formed on articles transported by an assembly line, or manually transported across a checkout counter at a retail point-of-sale location. Further, in portable embodiments of the invention, the reader need not be hand held. The reader may part or wholly hand worn, finger worn, waist worn or head worn for example.

[0052] Referring again to particular aspects of the invention, control circuit 140 in the example of FIG. 1a executes a partial frame capture mode in order to clock out and capture pixel data illustrated by valid zone 12-1. Reading the pixel values of valid zone 12-1 is effective to decode 1D symbol 16-1 in the reader's full field of view. Given that clocking out and capturing image data of valid zone 12-1 consumes less time than clocking out and capturing a full frame of image data, it is seen that execution of a partial frame capture mode decreases the decode time of the reader. In prior art 2D optical readers, electrical signals corresponding to full frame 10 are clocked out in order to decode a single 1D symbol 16-1. The pixels of valid zone 12-1 may comprise a single row of pixels (a scan line) or a plurality of rows.

[0053] In the example of FIG. 1b, control circuit 140 executes a partial frame capture mode in order to capture data defining valid zones 12-2, 12-3 and 12-4 of a full frame of image data corresponding to a full field of view of a 2D image sensor. Valid zones 12-2, 12-3 and 12-4 are line patterns of image data at various angular orientations. Reading of pixels of linear valid zones arranged at various angular orientations is effective to decode a 1D symbol which may be located at an oblique angle in a field of view. It is seen that reading of pixels of linear valid zone 12-3 will result in the successful decoding of 1 D bar code symbol 16-2. Zones 12-2, 12-3 and 12-4 may be one or more pixels wide.

[0054] In the example of FIG. 1c, control circuit 140 executes a partial frame capture mode in order to clock out and capture image data defining valid zones 12-5 through 12-9. Valid zones 12-5 to 12-9 form a plurality of horizontal parallel lines. The pattern of valid zones shown in FIG. 1c clocked out and captured in a partial frame capture mode is effective for decoding substantially horizontally oriented 1D symbols which are at an unknown height in a full field of view. It is seen that the reading of image data of valid zone 12-8 will not result in the decoding of symbol 16-3 because symbol 16-3 is not a 1D symbol. Nevertheless, because valid zone 12-8 intersects symbol bullseye 16b, reading of a image data of valid zone 12-8 may be effective to determine that a 2D symbol is likely present in the full field of view of image sensor 132. In one aspect of the invention, reader 110 may be configured to switch out of a partial frame capture mode and into a full frame capture mode when reading of image data captured in the partial frame capture mode reveals that a 2D symbol is likely to be represented in the image data corresponding to the image sensor's full field of view.

[0055] The states of operation of reader 110 operating in accordance with the invention are normally selected by actuating appropriate buttons of keyboard 178, or control of a GUI, or by the reading of menuing symbols, as are explained in commonly assigned U.S. Pat. No. 5,929,418 incorporated herein by reference. In alternative embodiments, software can be used to control which states of operation will be active at different times. For example, it is possible to program a computer to begin operation of the reader device in a default state, such as a partial frame capture mode of the 2D image sensor. It is possible to write computer code that will switch the operation to a second partial frame imaging mode if a sensor module senses the presence of one or more finder patterns. It is possible to write computer code that will switch the operation to a full frame imaging mode if an analysis module reveals the presence of a 2D encoded indicium.

[0056] It should be apparent that several operating states of the invention are possible. In a first operating state, reader 110 is made to operate only in a partial frame capture mode until the time the first operating state is deactivated.

[0057] In a second operating state, as is alluded to in the example of FIG. 1c, the reader operates in a partial frame capture mode until the time that reading of image data captured in the partial frame capture mode reveals that a 2D symbol is likely to be included in the full frame field of view of image sensor 132. The revelation that a 2D symbol is likely to be included in the full frame field of view of image sensor 132 is accomplished using an analysis module that analyses the features of the partial frame of image data. When reading of the partial frame of image data reveals that a 2D symbol is likely to be included in a full frame field of view, control circuit 140 captures at least one full frame of image data from sensor 132 and attempts to decode for the 2D symbol determined likely to be represented in the full frame of image data. A reader operating in the second operating state may also be made to switch to a full frame operating mode on the condition that a symbol is not successfully decoding during operation of the reader in the partial frame operating mode.

[0058] A third operating state of a reader operating in accordance with the invention is described with reference to FIGS. 1d and 1e. Operating in accordance with a third operating state, a reader operates in a partial frame capture mode to clock out and capture image data of valid zone 12-10 which corresponds to a predetermined pattern and position in field of view 10. It is seen that reading of image data of zone 12-10 will not be effective to decode symbol 16-4 because symbol 16-4 is of a type of 2D symbol known as a stacked linear bar code. Control circuit 140 may nevertheless detect that symbol is a 2D symbol given that valid zone 12-10 intersects a finder pattern 16f of symbol 16-4. Sensing with a sensing module that a 2D symbol is likely present in the field of view when reading the partial frame image data corresponding to valid zone 12-10, the reader operating in the third operating state then continues to operate in a partial frame mode to clock out and capture image data that defines a second valid zone 12-11 of pixel positions as seen in FIG. 1e. The second valid zone 12-11 is not of a predetermined size and position, but rather is of an adaptive position whose position, and possibly size, orientation and shape depends on the result of the reading of the image data corresponding to the first valid zone 12-10. Specifically, the second valid zone 12-11 is normally at least of a size and position that is likely to encompass the symbol 16-4 detected to be present when reading of the image data of first valid zone 12-10. It is seen that the third operating state is likely to be operative to further reduce the clocking out and capture of irrelevant image data, and therefore is likely to further increase decoding speed. In the third operating state, additional adaptive position valid zones may be clocked out and captured if the reading of image data of first adaptive valid zone 12-11 does not result in a symbol being decoded.

[0059] In the example of FIGS. 1f and 1g valid zones 12-12 and 12-13 correspond to nonlinear groupings of pixels. Capturing of the valid zone patterns 12-12 and 12-13 of FIGS. 1f and 1g is particularly useful for decoding symbol image data in the case that a symbol is likely to be at a certain position in relation to an image sensor's full frame field of view such as in the center of an image sensor's field of view as shown in FIG. 1f.

[0060] In the example of FIG. 1f control circuit 140 can successfully decode symbol 16-6 because symbol 16-6 is located entirely within valid zone 12-12.

[0061] In the example of FIG. 1g, control circuit 140 cannot decode symbol 16-7 if operating in the first operating state since symbol 16-7 is a 2D symbol and is not entirely located within valid zone 12-13. If operating in the second operating state, then a reader capturing image data within valid zone 12-13 may successfully decode symbol 16-7 by reading the image data of zone 12-13 to determine that a 2D symbol is present, switching operation to a full frame capture mode to capture a full frame 10 of image data, and processing the full frame of image data to decode symbol 16-7. A reader operating in the third operating state described hereinabove may decode symbol 16-7, in the example of FIG. 1g, by reading image data within valid zone 12-13, capturing image data within an adaptively defined valid zone (not shown) of sufficient size and position to encompass symbol 16-7, and then processing the image data within the adaptively defined valid zone to decode symbol 16-7.

[0062] FIG. 3 is a flow diagram 300 showing an illustrative process in which a partial frame of an image of an encoded indicium is processed to extract encoded information. The process begins as indicated in the oval 310 labeled START. The reader images an encoded indicium using the 2D image sensor operating in a partial frame mode, as indicated at box 320. The control module causes a partial frame of the image to be captured or clocked out, as indicated at box 330. The processing module processes the partial frame of image data to extract information encoded in the encoded indicium, as indicated at box 340. The result of the processing by the processing module is examined to determine whether information has indeed been extracted, and a test is performed as indicated by diamond 350. If the result of the test is positive, as indicated by the arrow labeled YES, the information is provided, as indicated by box 360. The process is then completed, as indicated by oval 370, labeled END. However, if the result of the test performed at step 350 is negative, as indicated by the arrow labeled NO, the control module switches to a full frame mode of operation, as indicated at box 355. The result of processing a full frame of the image is then provided at box 360, and the process ends at oval 370. The process 300 can be repeated as many times as required to extract information from a plurality of encoded indicia.

[0063] FIG. 4 is another flow diagram 400 showing an illustrative process in which a partial frame of an image of an encoded indicium is processed to extract encoded information. The process begins as indicated in the oval 410 labeled START. The reader images an encoded indicium using the 2D image sensor operating in a first partial frame mode, as indicated at box 420. The control module causes a first partial frame of the image to be captured or clocked out, as indicated at box 430. The processing module processes the first partial frame of image data to extract information encoded in the encoded indicium, as indicated at box 440. The result of the processing by the processing module is examined to determine whether information has indeed been extracted, and a test is performed as indicated by diamond 450. If the result of the test is positive, as indicated by the arrow labeled YES, the information is provided, as indicated by box 460. The process is then completed, as indicated by oval 470, labeled END. However, if the result of the test performed at step 450 is negative, as indicated by the arrow labeled NO, the control module switches to a second partial frame mode of operation, as indicated at box 455. The second partial frame is not necessarily of a predetermined size and position, but rather is of an adaptive position whose position, and possibly size, orientation and shape depends on the result of the reading of the image data corresponding to the first partial frame. For example, the second partial frame may be determined by the sensor module, using such information as one or more finder patterns, or one or more characteristics of known symbologies that suggest or define a size, an orientation, and/or a shape of a likely region to use as the second partial frame. The result of processing the second partial frame of the image is then provided at box 460, and the process ends at oval 470. The process 400 can be repeated as many times as required to extract information from a plurality of encoded indicia.

[0064] Yet another mode of operation is possible, in which the region that is examined is incrementally increased. In brief, in this operating mode, a first partial frame of image data is clocked out and analyzed. If the data provides information, the result is presented. However, if the first partial frame does not provide decoded information, the operation of the system can be switched to a second partial frame mode, and if that mode of operation also fails to provide information, the operation can be switched to a third mode, such a full frame operating mode. As many incrementally larger partial frames as appear useful can be successively clocked out and analyzed in an effort to search for decodable information. However, one must also consider as a limitation that if the total operating time to obtain and examine a succession of incrementally larger partial frames equals or exceeds the time required to clock out and analyze a full frame of data, there is no improvement in processing time to be gained. Accordingly, depending on partial frame clock out time, and depending on the processing speed of the analysis module, one or more sequences of incrementally increasing partial frame regions can be defined beyond which it is more efficient to simply examine the full frame of image data. An illustrative example is given in the flow chart depicted in FIG. 5, in which a second partial frame mode is used before the full frame mode is activated.

[0065] FIG. 5 is another flow diagram 500 showing an illustrative process in which a partial frame of an image of an encoded indicium is processed to extract encoded information. The process begins as indicated in the oval 510 labeled START. The reader images an encoded indicium using the 2D image sensor operating in a first partial frame mode, as indicated at box 520. The control module causes a first partial frame of the image to be captured or clocked out, as indicated at box 530. The processing module processes the first partial frame of image data to extract information encoded in the encoded indicium, as indicated at box 540. The result of the processing by the processing module is examined to determine whether information has indeed been extracted, and a test is performed as indicated by diamond 550. If the result of the test is positive, as indicated by the arrow labeled YES, the information is provided, as indicated by the path of arrows labeled YES from diamond 555 through diamond 560 to box 570, labeled PROVIDE INFORMATION. The process is then completed, as indicated by oval 580, labeled END. However, if the result of the test performed at step 550 is negative, as indicated by the arrow labeled NO, the control module switches to a second partial frame mode of operation, as indicated at box 555. The second partial frame is not necessarily of a predetermined size and position, but rather is of an adaptive position whose position, and possibly size, orientation and shape depends on the result of the reading of the image data corresponding to the first partial frame. For example, the second partial frame may be determined by the sensor module, using such information as one or more finder patterns, or one or more characteristics of known symbologies that suggest or define a size, an orientation, and/or a shape of a likely region to use as the second partial frame. In the second partial frame mode, additional information corresponding to the additional pixels that are to be interrogated is clocked out and the resulting partial frame of image data is analyzed. A test of the result of processing the second partial frame of the image is performed at diamond 560, labeled INFORMATION EXTRACTED If the result of the test is positive, as indicated by the arrow labeled YES, the information is provided, as indicated by box 570. The process is then completed, as indicated by oval 580, labeled END. However, if the result of the test performed at step 560 is negative, as indicated by the arrow labeled NO, the control module switches to a full frame mode of operation, as indicated at box 565. The result of processing a full frame of the image is then provided at box 570, and the process ends at oval 580. The process 500 can be repeated as many times as required to extract information from a plurality of encoded indicia.

[0066] Those of ordinary skill will recognize that many functions of electrical and electronic apparatus can be implemented in hardware (for example, hard-wired logic), in software (for example, logic encoded in a program operating on a general purpose processor), and in firmware (for example, logic encoded in a non-volatile memory that is invoked for operation on a processor as required). The present invention contemplates the substitution of one implementation of hardware, firmware and software for another implementation of the equivalent functionality using a different one of hardware, firmware and software. To the extent that an implementation can be represented mathematically by a transfer function, that is, a specified response is generated at an output terminal for a specific excitation applied to an input terminal of a black box exhibiting the transfer function, any implementation of the transfer function, including any combination of hardware, firmware and software implementations of portions or segments of the transfer function, is contemplated herein.

[0067] While the present invention has been explained with reference to the structure disclosed herein, it is not confined to the details set forth and this invention is intended to cover any modifications and changes as may come within the spirit and scope of the following claims.