Extended working range dataform reader including fuzzy logic image control circuitry

Extended working range data sheet reader including fuzzy logic image control circuit

Horizontal Reference of Related Applications This application is the following co-pending application, serial number US08/507,607, filed on June 25, 1996; serial number US08/494,435, filed on June 26, 1996; serial number US08/332,592 , Filed on October 31, 1994; serial number US08/280,489, filed on July 16, 1994, part of the continuation. Each application is integrated here with its own all.

Technical field

The present invention relates to a dataform reader and method for reading a dataform including one-dimensional and two-dimensional barcodes and matrix codes, and more specifically, to a dataform reader including a datasheet reader module for reading datasheets and In its method, the module uses a fuzzy logic image control circuit to reduce the time necessary to adjust the exposure control and signal processing parameters, so as to achieve acceptable gain adjustment and reasonable exposure of the composite video image suitable for decoding.

Background technique

A. Data sheet background The application of bar codes and matrix codes is well known and growing. Bar code and matrix code are the form of data table, corresponding to the current intention, it can be defined as a layout that includes all data fixed in some machine-readable copy table. Therefore, the data table includes one-dimensional (one-dimensional) and two-dimensional (two-dimensional) barcodes (such as UPC, C128, PDF417, etc.), matrix codes (such as MaxiCode, DataMatrix, Codel, etc.) and graphic codes , There are words and numbers and other symbols, they can be printed or etched on paper, plastic cards and metal or other things. The data sheet can be printed by the following methods, invisible ink, magnetic recording (via magnetic stripe or magnetic ink writing), electromagnetic recording (via RF tag), engraving, seal, tattoo (on the skin), by the form of ionic paint ( Used in semiconductor wafers) or biochemical compounds, etc.

In the application of the data table, the original encoded data is restored for further use in a variety of ways. For example, a printed bar code may be optically scanned to generate a reflection value, which is digitized, stored in a buffer and then decoded to restore the data encoded in the bar code. Ignoring the special type of data table, typically an image is acquired and stored as pixel values for further processing. The bar code or matrix code image that exists as a graphic image can be obtained by using a charge-coupled device (CCD) reader, laser scanner or other appropriate equipment, which can distinguish between the reflectance value of different light reflectance data units and the specific Data table, synchronized data unit format. Therefore, for example, a barcode typically includes black or dark bar-shaped elements printed on a white or light-colored background area, with white or light-colored spaces between the elements of the barcode. The interval is typically the same color as the background area, but in this example, it can also be a different light color. In other examples, the elements of the barcode or matrix code are white or light-colored, and are defined by black or dark spaces and background areas.

In other applications, such as laser engraving on silicon wafers, illumination may result in a relationship of dark to light in one direction, and a relationship of light to dark in the other direction. In addition to the pixel value representing the reflection value of light (for the current intent, "light" is defined as including the entire electromagnetic spectrum), in other layouts, the pixel value representing the reflection value may be based on sound waves or other reasonable configurations. The reflection of the media of the data sheet. In any layout, this reflection value can typically be stored as a pixel value in an image buffer or other bitmap storage media or other table. When the table represents the pixel value of the image, any reasonable value can be used. Data storage format.

B. The background of the data sheet reader. The current technology portable terminal with integrated laser barcode scanning module or one-dimensional CCD barcode reader module cannot be well adapted to read two-dimensional barcode data sheets. The laser barcode scanner operates by emitting a narrow laser beam, which forms a strong illuminating spot on the barcode. The oscillating mirror continuously transforms the light beam so that the dot moves in a sweeping pattern or raster pattern. Generally, the scanning mode means that the beam oscillates along the horizontal axis without any vertical oscillation. The raster mode refers to the rapid oscillation along the horizontal axis and the slow oscillation along the vertical axis, so the raster mode is similar to the scanning mode that moves up and down. A photodetector collects illumination from all target areas. When a moving or flying point is incident on the highly reflective area of the barcode, such as a white background, the light reflected from the point is incident on the photodetector. When a moving or flying point is incident on the weakly reflective area of the barcode, such as a black bar, the weaker light is reflected on the photodetector.

The laser scanner has no internal synchronization mechanism. The laser scanner calculates the relative horizontal position of the laser point based on the known self-synchronization pattern in the one-dimensional bar code. This can be considered as a code self-synchronization system. Raster mode laser scanners can read two-dimensional stacked bar codes (stackedbar) such as PDF-417. Because PDF-417 has a unique line indicator pattern, it can be recognized by the scanner and used for vertical synchronization. This system has a very small tolerance for the rotation angle, because the scanner cannot recognize line indicator patterns or other code patterns unless the dots pass through the entire pattern completely.

Laser scanners cannot read two-dimensional matrix codes, such as MaxiCode and Datamatrix codes, because these codes do not have a line indicator pattern for vertical synchronization.

The operation of the one-dimensional CCD reader is to image a long and narrow target area onto a one-dimensional photodetector array instead of scanning the illumination point through the bar code symbol. If the reader is placed relative to a one-dimensional bar code, this makes the imaged target area fall relatively to the opposite side of the bar code, so that the bar code can be decoded based on the gray level values of the run-length sequence, and these values are imaged with codes on it. The pixels of each bar and space are generated. Similar to laser scanners, one-dimensional CCDs have no vertical synchronization and must rely on the line indicator pattern for vertical synchronization.

Recently, the concept of CCD readers has been extended to two-dimensional CCD readers, such as the TEC contact reader manufactured by Tokyo Electric Company. The two-dimensional CCD reader images the target area onto a two-dimensional array of photodetectors or photoelectric sensors. This device can read matrix codes because the two-dimensional pixel array provides horizontal and vertical synchronization. This reader is too large and bulky for practical applications in portable terminals. Moreover, the device consumes too much power for battery-powered portable devices.

Current two-dimensional CCD readers have an image capture system that includes a board camera that continuously generates a composite image signal representing the target area. When the reading work starts, part of the signal is selected for decoding. Because the board camera continuously produces video signals, it consumes approximately 1-2 watts of electricity. This power consumption will run out of ordinary batteries in less than 1 hour of operation.

The state-of-the-art image capture configuration does not provide for closing the panel camera in the middle of two readings. Currently available on-board cameras require 600 milliseconds (ms) waiting time in order to generate a composite video signal with gain correction and reasonable exposure after power-up, that is, to reach an equilibrium state. The waiting time includes the time required to synchronize the readout of the photosensors, plus the time required to adjust the gain control and exposure cycle through the closed-loop analog feedback circuit. The latter time constitutes most of the waiting time. Therefore, if the board camera needs to be powered for each reading period, the reading period will have to be longer than 600 milliseconds. Because consumers expect fast waiting time, they strongly hope that the time period of this reading period should be less than 300 milliseconds. Therefore, with existing equipment, the board camera cannot be turned off between data sheet reading periods.

The current exposure control system uses an independent analog integrated circuit, which receives the analog video signal from the photoelectric sensor array, and generates an independent voltage signal to control the gain, exposure period and reference voltage. The closed-loop analog system provides linear adjustments to the exposure parameters (gain, exposure period, and reference voltage), and it is particularly desirable to use these parameters to eliminate any sudden changes in the composite video loop. However, this closed-loop analog system is not desirable in data table reading, because it is expected that the rapid change of the video signal can complete a decodable image as soon as possible.

Therefore, there is a need for a data table reader module based on two-dimensional images that can be closed between data table reading periods. Necessarily, this reader module must have a short waiting time, that is, a short waiting time between power-on and the generation of an exposed composite video image suitable for gain adjustment and suitable for decoding processing. For this kind of reader module, low power consumption when powered on is also required.

What is also needed is that this data sheet reader module includes an image control circuit that quickly adjusts the exposure period and gain settings of the board camera to achieve a decodable composite video image. In addition, there is a demand for such image control circuits to generate high and low reference voltages for adjusting gain and exposure period settings.

In addition, this image control circuit is required to provide linear adjustment of gain and exposure period to avoid undesirable sudden changes in the composite video signal.

Another need is to have a portable data acquisition system that includes such a data sheet reading module. It is expected that such a system is small, light weight, low power consumption, and overcomes other shortcomings of the prior art equipment.

Summary of the invention

According to the present invention, a portable CCD data sheet reader module whose size and shape are compatible with existing laser scanner modules is provided. The reader module of the present invention includes a control and decoding circuit, which is electrically connected to a camera assembly including a board camera. The control and decoder board includes a fuzzy logic control circuit, which is connected to the board camera in an open loop feedback structure.

The board camera produces a video image of the target area including the data table. The video image is composed of consecutive frames of the image. A frame consists of two interlaced fields. One field is generated by reading the charge accumulated in the two-dimensional array of photosensors. The exposure period of the plate camera is less than the time necessary to read the charge on the photosensor array. The board camera generates "raw" analog voltage signals in response to the video image. The "raw" analog voltage signal is amplified by the board camera gain circuit. The gain adjustment analog video signal is connected to the fuzzy logic image control circuit.

The image control circuit analyzes the gain adjustment video signal and generates a control signal, which is connected to the panel camera to control the gain setting and the exposure period of the panel camera, so that the camera produces a video image suitable for decoding.

Because the fuzzy logic image control circuit analyzes a video image capture frame and, if necessary, adjusts the gain of the board camera and/or the speed of the exposure cycle, the reader module of the present invention can be quickly adjusted to change the lighting environment. In addition, the reader module of the present invention can quickly adjust to a new lighting environment when the module is powered on. Because of the ability to quickly adjust the exposure parameters to the lighting conditions, it can turn off the reader module between data sheet reading periods. Compared with the existing CCD reader module, turning off the reader module between reading periods significantly reduces the power consumption of the module. As mentioned above, the characteristic of the existing CCD reader module is the unacceptably long waiting time (600ms) from power-on to obtaining a video image suitable for decoding and the resultantly, it cannot be switched off between reading periods. Electricity. Therefore, the reader module of the present invention has an increased effective working time between battery replacement and/or charging, relative to the existing CCD reader module that is maintained in the power-on state.

The fuzzy logic image control circuit of the present invention includes a fuzzy logic control unit, a signal processing circuit, a D/A converter and an A/D converter. The image control circuit receives the gain-adjusted video signal output through the on-board camera, and captures part of the signal for a period of time in response to a video image frame. This signal is input to the A/D converter along with a high voltage reference value and a low voltage reference value. The A/D converter digitizes the gain-adjusted video signal, and then converts the digitized voltage signal into a series of grayscale values. The gray scale used by the fuzzy logic image control circuit of the present invention has a range of 0 (black) to 255 (white).

The board camera includes a 752×582 photoelectric sensor array containing 437,664 photoelectric sensors. Therefore, the photosensor produces a video image containing 437,664 pixels. The captured video image frame therefore includes approximately 437,664 pixels that vary in intensity and brightness according to the captured video image. The portion of the gain-adjusted video signal corresponding to the captured frame represents the pixel density associated with that frame. The signal is converted to 437,664 corresponding series of gray scale values. The gray level value is input to the signal processing circuit, which generates three values based on the gray level value. The three values are: brightness value (I), dynamic range maximum (DRMAX) and dynamic range minimum (DRMIN). The values of I, DRMAX and DRMIN are input to the fuzzy logic control unit. The fuzzy logic control unit uses three empirical member function tables stored in the memory and the values of I, DRMAX and DRMIN to calculate the coefficient change value.

The fuzzy logic control unit adds the calculated coefficient change value to the current coefficient value to calculate the correction coefficient value. The fuzzy logic control unit then accesses an empirical lookup table stored in the memory to determine the "correct" value for the following values: a) the gain setting of the panel camera based on the correction coefficient value; b) the exposure period of the panel camera; c) high Reference voltage value; and d) Low reference voltage value. The "correct" settings of the gain setting and exposure period are empirically determined to cause the panel camera to produce values that are acceptable for data table decoding.

The fuzzy logic control unit compares the current coefficient value and the correction value. If the two coefficient values are "close", that is, the difference between the values is within a preset range, the captured video image frame is suitable for decoding, and is then decoded by the decoding circuit. If the two coefficient values are not "close", the fuzzy logic control unit generates a digital control signal corresponding to the correct setting of gain and exposure period. The digital control signal is converted into an analog signal by the D/A converter and connected to the gain circuit and exposure cycle circuit of the on-board camera to adjust the gain and exposure period of the on-board camera to adapt to the determined "correct" gain and exposure period settings. The predetermined "close" range varies with the coefficient value and is determined based on experience.

Conceptually, if the difference between the current and correction coefficient values exceeds the predetermined range associated with the current coefficient value, then the captured video image frame is not suitable for decoding, so another frame is captured and analyzed to determine the new capture Whether the frame is suitable for decoding. Before capturing a new frame, the fuzzy logic control unit generates a control signal, which is connected to the board camera to adjust the gain and exposure period according to the previously predetermined "correct" value. The analysis process repeats with the newly captured video image frame. The analysis of the newly captured video image frame uses the "correct" high and low reference voltage values.

The present invention also provides a low-power data table reader for reading data tables in a target area. The reader includes: a) a light source that directs illumination to the target area; b) a two-dimensional photoelectric sensor array A panel camera, the two-dimensional photosensor array includes a set of pixels that receive reflected illumination from a target area, the panel camera further includes a camera for generating a signal representing the accumulated illumination incident on each of the above-mentioned pixels during the exposure period Control circuit; c) lighting control circuit, when the exposure period exceeds the predetermined time, it provides working power to the light source during the exposure period; when the exposure period is less than or equal to the predetermined time, it does not provide working power to the light source.

In addition, according to the present invention, the reader module includes a large F# optical assembly, which provides a working range from about 2.5" to at least 8.5" in front of the reader while maintaining the on-board field of view. The reader module can capture images with a high signal-to-noise ratio in less than 0.01 seconds, so that the reader is more tolerant to the user's hand shake. In order to reconcile the large F# optical and short exposure period, the reader module is equipped with an effective high-density unified lighting module.

The high-intensity lighting module is fixed to the front of the reader module housing, thereby avoiding the problem of lighting loss and internal reflected lighting noise related to placing the lighting source after the window of the reader module housing. The lighting module includes a printed circuit board that includes a large number of surface-mounted LEDs fixed to the front end of the printed circuit board. The printed circuit board is glued into the hole in the back of the durable acrylic lens array. The lens array operates to direct uniform and high-intensity illumination to the target area in front of the reader module.

In a preferred embodiment, the lighting module has an aperture in the center, and the reader module is placed to collect the light emitted from the target area through the aperture. This structure ensures that the illumination guided from the lens array of the reader module is aligned with the field of view of the reader module.

In one aspect of the present invention, the reader module includes simulating the output of the laser scanning module so that it can be updated into a data table reading device containing the laser scanner.

In another aspect of the present invention, the reader module including the present invention is provided to a data collection system. The data sheet reading system is for completely portable use and includes a spread-spectrum radio device that operates to connect the reader to computers throughout the IEEE 802.11 compatible network. Spread-spectrum radios can be used to transmit decoded data table data, photographic image data in compressed format, or compressed data files representing voice messages.

According to the present invention, the portable data acquisition system including the data table reading module of the present invention additionally includes user interface devices such as keyboard, display, touch panel, microphone and speaker, which work with different circuits to improve the function of the reader module. .

In order to better understand the present invention and other and further purposes, the accompanying drawings will be described below.

Description of the drawings

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, which are briefly described as follows.

Figure 1 is a perspective view of the data sheet reader of the present invention including a control and decoder board, and a cross-sectional view of the camera assembly; Figure 2 is a block diagram of selected circuit components in the data sheet reader module of Figure 1; 3A is the member function table diagram of the gray level histogram value; Figure 3B is the member function table diagram of the maximum dynamic range;

Figure 3C is a member function table diagram of the minimum dynamic range; Figure 4 is used to determine the exposure period, gain, high reference voltage value and low reference voltage value based on the calculated coefficient value based on the experience-based query; Figure 5 is an explanatory diagram 1 The work flow chart of the fuzzy logic exposure control system of the data sheet reader module; Figure 6 is a top view diagram of the data sheet reader module of Figure 1; Figure 7 is the interior of the lighting module of the data sheet reader module of Figure 1 Perspective view; Fig. 8 is a side sectional view of the lighting module part of Fig. 7; Fig. 9 is a state diagram illustrating the operation of the power control circuit of the reader module of Fig. 1; Fig. 10 is a portable data acquisition system including the reader module of Fig. 1 Figure 11 is a partial cross-sectional and partially elevated side view of the portable data acquisition system of Figure 10; Figure 12 is a perspective view of another embodiment of the portable data acquisition system including the reader module of Figure 1; Figure 13 is Figure 12 is a partial cross-sectional and partially elevated side view of the portable data collection system; Figure 14 is a block diagram of the voice mail system of the present invention; and Figure 15 is a top elevated view of the wireless headset of the present invention.

detailed description

Turning to the drawings, the data sheet reader module of the present invention is shown at 10 in FIG. 1. The data sheet reader module 10 includes a camera assembly 12 and a control and decoder board 14. The control and decoder board 14 includes a microprocessor 16 and a fuzzy logic image control circuit 18. The fuzzy logic image control circuit 18 may be included in software that resides in one or more RAM or ROM storage chips 19 mounted on the board 14 and is run by the microprocessor 16. In addition, the image control circuit 18 may include a separate application specific integrated circuit (ASIC) mounted on the board.

As outlined in Figure 2, the image control circuit 18 installed on the control and decoder board 14 includes a fuzzy logic control unit 20, a digital-to-analog conversion circuit (D/A converter) 22, and an analog-to-digital conversion circuit (A /D converter) 24 and signal processing circuit 26. The board 14 also includes a power supply circuit 28. The power supply 30 provides power required by the circuits on the board 14. The power supply circuit 28 includes a wire 29, which in turn is connected to the input terminal 32 of the camera assembly to provide power to the assembly.

As shown in FIGS. 1 and 6, the camera assembly 12 includes a board camera including three printed circuit boards 41a, 41b, 41c arranged at intervals. Mounted on the top plate of the plate camera 40, 41a is a two-dimensional photoelectric sensor array and an optical component for focusing an image of an object or target area 166 (Figure 6) including a bar code data sheet (not shown) to the photoelectric sensor array 44. The photosensor array 42 includes a 752×582 photosensor array. When the reader module 10 is powered on, the photosensor array 42 generates a video image including 437,664 pixels. The optical assembly 44 is supported in a ring camera housing 46, which shields the photosensor array 42 to prevent ambient light from entering the photosensor. The optical component 44 is at a distance from the photosensor array 42, which corresponds to the image plane of the optical component.

Each photosensor of the photosensor array 42 stores the charge generated by photons hitting the photosensor during the exposure period. The exposure period is less than the time required to read a video image. Reading the charges accumulated on each photo sensor in the photo sensor array 42 constitutes a field of video image. Two interlaced fields constitute one frame of image. The charge amount of the photosensor at the end of the exposure period is proportional to the number of photons hitting the photosensor. The photons that hit the photosensor are related to the light emitted from the target or image area. The incident light hitting the target area or zone 166 is generated by the illumination module 47 (not shown in Fig. 1 but shown in Figs. 7 and 8). The intensity or brightness of each pixel corresponds to the charge of the related photosensor.

In the process of reading photoelectric sensors, the charge on each photoelectric sensor is transferred to a storage register. The length of the exposure period is controlled by the exposure control circuit 48 (schematically shown in FIG. 2) of the plate camera 40. The transferred charge is read from the storage register to generate an analog voltage signal 50 representing the video image. This "raw" video signal 50 is amplified by the output gain circuit 52 (schematically shown in FIG. 2) of the board camera 40 to generate a gain-adjusted composite video signal 54 suitable for decoding. The gain adjustment composite video signal 54 is an analog signal. The signal 54 corresponding in time to a period of exposure period partially constitutes the field of the video image and represents a series of charges associated with each of the 437,664 photosensors in the exposure period. As mentioned above, one frame of a video image consists of two interlaced fields.

If the exposure period of the panel camera 40 is too short, the charge on most of the photosensors in the photosensor array 42 is not high enough, and the resulting data sheet video image will be too dark. Therefore, the gain-adjusted video signal 54 will not be suitable for decoding. On the other hand, if the exposure period of the panel camera is too long, the photosensors in the photosensor array 42 will be overcharged, and the resulting video image will be too bright. Once again, the gain adjusted video signal 54 will not be suitable for decoding. If the "raw" video image voltage signal 50 experiences too much or too little gain, the resultant gain-adjusted composite video signal 54 will not be suitable for decoding.

When the reader module 10 is powered on, the board camera generates a video image of the target area. The fuzzy logic image control circuit 18 captures a part of the gain-adjusted video signal 54 corresponding to one frame, and then determines whether the captured frame is suitable for the image in the decoded frame. If the fuzzy logic image control circuit 18 determines that the captured frame is suitable for decoding, a representative of the frame is stored in the memory 19 to be subsequently decoded by the decoding circuit 92 (FIG. 2).

If the fuzzy logic image control circuit 18 determines that the captured frame is not suitable for decoding, one or more operating parameters of the panel camera are adjusted by the control signal generated by the image control circuit 18. Another image frame is captured by the image control circuit 18 and analyzed for decoding suitability. Therefore, the configuration of the reader module 10 provides open loop feedback between the fuzzy logic image control circuit 18 and the board camera 40.

The fuzzy logic image control circuit 18 performs an iterative process to obtain video image frames suitable for decoding. The iterative process includes the steps of capturing, analyzing and adjusting, that is, capturing video image frames, analyzing the suitability of the frames for decoding, and, if not suitable, adjusting one or more camera operating parameters on the board. The flowchart listed in Figure 5 illustrates this iterative process. Corresponding to most data table images, three or fewer iterations are required to obtain an image suitable for decoding, that is, three or fewer frames must be captured.

The fast execution of the iterative process by the fuzzy logic image control circuit results in a very short waiting period. The waiting period is corresponding to the time between powering on the reader module 10 and obtaining a video image suitable for decoding. The waiting period includes the time required to synchronize the reading of the photoelectric sensor, plus the time required to adjust the gain of the panel camera 40 and the exposure cycle parameters. With the reader module 10 of the present invention, the waiting period is 50 ms or less.

Returning to FIG. 2, the gain-adjusted video signal 54 produced by the board camera 40 is connected to the input terminal 56 of the control and decoder board 14. The video signal 54 is decoded and subjected to fuzzy logic analysis by the fuzzy logic image control circuit 18. Based on the fuzzy logic analysis, the control circuit 18 generates analog control signals 58, 60, which are connected to the input terminals 62 and 64 of the control and decoder board 14. The control signal 58 is input to the exposure cycle circuit 48 to control the exposure cycle of the panel camera 40, while the control signal 60 is input to the gain circuit 52 to control the gain setting of the panel camera.

The gain-adjusted composite video signal 54 is connected to the A/D converter 24. In addition, input to the A/D converter 24 are two analog reference voltage signals 66 and 68. The voltage signal 66 is a high reference voltage signal, and the voltage signal 68 is a low voltage reference signal. The fuzzy logic control unit generates coefficient values 70 and 72 corresponding to the high and low reference voltage signals 66 and 68. The coefficient values 70 and 72 are converted by the D/A converter 22 into independent analog reference signals 66 and 68. The A/D converter 24 uses the analog high and low reference voltage signals 66 and 68 to convert the gain adjusted composite video signal 54 into a series of gray scale values. The gray level is a series of achromatic gray tones with white and black endpoints. The gray scale used by the image control circuit of the present invention ranges from 0 (black) to 255 (white). For a given captured video image frame, there is a gray level for each point of 437,664 pixels. The gray level value of the corresponding pixel provides a relative measurement of the intensity or brightness of the pixel. The signal 74 representing the gray level value corresponding to the captured frame is connected to the signal processing circuit 26.

The gray level value signal 74 associated with the captured frame of the video image includes a series of 437,664 gray level values. The signal processing circuit 26 extracts the brightness histogram value (I) 76, the dynamic range maximum value (DRMAX) 78 and the dynamic range minimum value (DRMIN) 80 from the gray scale signal 74. I, DRMAX, DRMIN values 76, 78, 80 are input to the fuzzy logic control unit 20. The fuzzy logic control unit 20 uses these values to generate digital control signals 82 and 84, which are input to the D/A converter 22. The D/A converter 22 converts the digital gain control signal 82 and the digital exposure period control signal 84 into an analog gain control signal 58 and an analog exposure period control signal 60. The control signals 58 and 60 are input to the ports 62 and 64 to be suitable for adjusting the gain circuit 52 and the exposure period circuit 48 of the panel camera 40.

The signal processing circuit 26 determines I (luminance histogram value) for the captured frame. I represents the number of gray levels in a set of 437,664 gray level values whose number is greater than or equal to 128. The gray level value 128 was chosen as the cut-off point because 128 is just above the midpoint of the gray level range from 0 to 255.

The DRMAX and DRMIN values of the captured frame are also determined by the signal processing circuit 26. If the size of the gray level value is drawn linearly on the XY coordinate system, the size determines an irregular, wavy pattern with alternating "peaks" and "valleys". The DRMAX value represents the average of the "peaks" of the wave pattern of the number of gray levels associated with the captured video image frame (excluding those exceeding). The DRMI N value represents the average value of the "valley" of the wave pattern of the number of gray levels associated with the captured video image frame (excluding those exceeding).

The values of I, DRMAX and DRMIN are input to the fuzzy logic control unit 20. The fuzzy logic control unit 20 uses the I, DRMAX, and DRMIN values to calculate the coefficient correction value. The fuzzy logic control unit 20 accesses three membership function tables 110 (FIG. 3A), 112 (FIG. 3B), 114 (FIG. 3C) derived based on experience, and derives the weighting factor for calculating the coefficient correction value by using the coefficient correction value formula . Each member function table 110, 112, 114 is composed of three overlapping ramp functions.

The member function table 110 includes functions labeled h1(I), h2(I), and h3(I). The function h1(I) corresponds to an image frame that is too dark, h2(I) corresponds to an acceptable or normal image frame, and h3(I) corresponds to an image frame that is too bright.

The member function table 112 includes functions labeled ma1 (DRMAX), ma2 (DRMAX), ma3 (DRMAX). The maximum value of the dynamic range of the correctly exposed image should be in the range of 150 to 230 grayscale values. The ma1 (DRMAX) function represents the image frame with the maximum dynamic range of less than 150, which is too low; the ma3 (DRMAX) function represents the image frame with the maximum dynamic range of greater than 230, which is too high.

The member function table 114 includes functions labeled mn1 (DRMIN), mn2 (DRMIN), and mn3 (DRMIN). The minimum value of the dynamic range of a correctly exposed image should be in the range of 20 to 100 grayscale values. The mn1 (DRMIN) function represents the image frame with the minimum dynamic range lower than 20, which is too low; the mn3 (DRMIN) function represents the image frame with the minimum dynamic range greater than 100, which is too high.

The determined I value is used by the fuzzy logic control unit 20 to determine the weighting factor of each of the three functions h1(I), h2(I), and h3(I) that make up the member function table 110. The determined DRMAX value is used by the fuzzy logic control unit 20 to determine the weighting factor of each of the three functions ma1 (DRMAX), ma2 (DRMAX), and ma3 (DRMAX) constituting the member function table 112. The determined DRMIN value is used by the fuzzy logic control unit 20 to determine the weighting factor of each of the three functions mn1 (DRMIN), mn2 (DRMIN), and mn3 (DRMIN) constituting the member function table 114.

In the coefficient correction value formula, the functions h1(I), h2(I), h3(I), ma1(DRMAX), ma2(DRMAX), ma3(DRMAX), mn1(DRMIN), mn2(DRMIN), mn3( DRMIN) is used to calculate the member value. Each function assigns a weight to the following table.

Member function weight h1(I) -1h2(I) 0h3(I) +1ma1(DRMAX) -1ma2(DRMAX) 0ma3(DRMAX) +1mn1(DRMIN) -1mn2(DRMIN) 0mn3(DRMIN) +1

The coefficient correction value formula derived based on experience is: ΔIndex=[7×hi(I)W1i]+[1×mai(DRMAX)W2i]+[1×mni(DRMIN)W3i] where, ΔIndex= coefficient correction Value, hi = member value of h1(I), h2(I), h3(I) listed above, W1i = weighting factor W11 associated with h1(I), h2(I), h3(I) respectively, W12, W13mai = member values of ma1 (DRMAX), ma2 (DRMAX), ma3 (DRMAX) listed above, W2i = weighting factor W21 associated with ma1 (DRMAX), ma2 (DRMAX), ma3 (DRMAX) respectively, W22, W23, mni = the member values of mn1 (DRMIN), mn2 (DRMIN), and mn3 (DRMIN) as listed above, and W3i = the same as mn1 (DRMIN), mn2 (DRMIN), mn3 (DRMIN) separately related Weight factors W31, W32, W33.

After determining the coefficient correction value (ΔIndex), the fuzzy logic control unit 20 uses the following formula to calculate the corrected coefficient value based on the ΔIndex value: correction coefficient value = current coefficient value + ΔIndex. When the reader module 10 is powered on, in the previous reading period The correction coefficient value stored in the memory 19 at the end becomes the current coefficient value of the current reading period. If there is no value in the memory, the default value such as nine(9) is used as the current coefficient value.

The correction coefficient value is determined by using the look-up table 100 stored in the memory 19 to determine the appropriate gain setting, exposure period, and high and low reference voltage values. Figure 4 illustrates the lookup table 100, which is derived based on empirical data. The first column 102 of the lookup table 100 sets the correction coefficient value. The setting as a function of the correction coefficient value is the exposure period in milliseconds (column 2), the gain setting (column 3), the coefficient 70 for the reference high voltage corresponding to the volt value (column 4) and the coefficient 72 for the reference low voltage corresponding to the volt value (Column 5).

As an explanatory example, suppose that when the module 10 is powered on, the first captured frame is analyzed by the signal processing circuit 26 and the following value is generated: I 135,000 DRMAX 125

The above values of DRMIN 10 are displayed as X1, X2, and X3 in the member tables 110, 112, and 114, respectively. In addition, suppose that at the end of the last reading period, the correction coefficient value is 20, and the value is stored in the memory 19. As can be seen in the look-up table in Figure 4, corresponding to the correction coefficient value 20 at the end of the previous reading period, the exposure period of the panel camera 40 has been set to 4 milliseconds, the gain has been set to the maximum value, and the high reference voltage has been set to correspond to The coefficient value is 70, and the low reference voltage has been set to a value corresponding to 10.

Turning to the member table 110 (Figure 3), the I value of X1=135,000 (135K) leads to the member values of the functions h1(I), h2(I), and h3(I) respectively: H1=0.7H2=0.3H3=0.0 For the member table 112 (Figure 3B), the DRMAX value of X2=125 leads to the member values of the functions ma1(DRMAX), ma2(DRMAX), and ma3(DRMAX) respectively: MA1=1MA2=0 MA3=0 For the member table 114 (Figure 3C), the DRMIN value of X3=20 causes the member values of the functions mn1(DRMIN), mn2(DRMIN), and mn3(DRMIN) to be: MN1=.5MN2=.5MN3=0 to replace the determined member from the above process table Value and weighting factor, the fuzzy logic control unit 20 calculates the coefficient correction value as follows: Δindex=7×[(-1)(.7)+(0)(.3)+(+1)(0)]+1×[ (-1)(1)+(0)(0)+(+1)(0)]+1×[(-1)(.5)+(0)(.5)+(+1)(0 )]=7[-0.7]+1[-1.0]+1[-0.5]=-4.9+-1.0+-0.5=-6.4

Next, the fuzzy logic control unit 20 obtains the correction coefficient value of the previous reading period (ie, the coefficient value, 22) from the memory 19 and uses the coefficient value as the current coefficient value to calculate the correction coefficient value. Then, the fuzzy logic control unit 20 calculates the correction coefficient value using the following formula: correction coefficient value=current coefficient value+Δindex=20+-6.4=13.6=14 (the nearest integer), as can be seen in the look-up table in Fig. 4, Given a correction factor value of 14, the exposure period of the panel camera 40 will increase from 4 milliseconds to 10 milliseconds, the gain setting remains at the highest, and the reference high voltage increases from the current value corresponding to the coefficient value of 70 to the higher reference voltage corresponding to the coefficient value of 75 volts , The reference low voltage keeps the current value corresponding to the coefficient value 10. The actual reference voltage value corresponding to the coefficient value is determined based on experience. The fuzzy logic control unit 20 generates digital control signals 82, 84 (they are converted from the analog control signals 60, 58 by the D/A converter) to cause the exposure cycle circuit 48 to change the exposure cycle to 10 milliseconds, and cause the gain circuit 52 Maintain the maximum value. The fuzzy logic control unit 20 also generates coefficient reference voltage signals 70, 72, which are connected to the D/A converter. The coefficient reference voltage signals 70 and 72 are converted into high and low reference voltage signals 66 and 68 by the D/A converter. By overwriting the previous coefficient value 20, the correction coefficient value 14 will be stored in the memory 19 by the fuzzy logic control unit 20. By overwriting the previous value of 4 milliseconds and the coefficient value 70, the correction value of the exposure period (10 milliseconds) and the high reference voltage (voltage coefficient value 75) will be stored in the memory 19.

In another aspect of the present invention, the fuzzy logic image control circuit 18 generates a signal 90, which is connected to the lighting module 47, when the correction coefficient value corresponds to an exposure period of 4 ms or less, prohibiting the assembly of the lighting LED 346 of the module. That is, if the correction coefficient value is equal to or exceeds the value 16 (FIG. 4), the lighting LED 346 is disabled.

The iterative process of analyzing, adjusting and capturing the video image of the object or target area 166 suitable for decoding and used by the reading module 10 will be described below. Step 200 is an initialization step when the data table reading module 10 is powered on. When powered on, the image control circuit 18 extracts the gain setting, the exposure period, the high reference voltage and the low reference voltage, and the current coefficient value from the memory 19, as shown in step 202. These parameter values correspond to the last set of parameters used in the previous reading period. The extracted value becomes the initialization parameter value used by the reader module 10. The image control circuit 18 generates control signals 58, 60 which are connected to the input terminals 62 and 64 of the board camera, respectively. The control signal 58 is connected to the panel camera exposure control circuit 48, and changes the exposure period setting of the panel camera to the extracted exposure period value. Similarly, the control signal 60 is connected to the gain circuit 52 of the panel camera 40, and causes the gain setting of the panel camera 40 to become the extracted gain value.

The board camera 40 uses the extracted gain setting and the extracted exposure period to generate a gain-adjusted analog signal 54 representing the video image of the target data table (step 204). As shown in step 206, the fuzzy logic image control circuit 18 captures the portion of the gain-adjusted video signal 54 corresponding to a data table image frame. In addition, a field can be captured by the image control circuit 18 and used for analysis. As explained earlier, the captured frame is used by the image control circuit 18 to determine the correction set of parameter values for the gain setting of the panel camera 40 and the exposure period setting, and the two reference voltage values based on the corresponding voltage coefficient values, and the coefficient correction Value and correction coefficient value (step 208).

In step 218, the image control circuit 18 determines whether the difference between the correction coefficient value and the current coefficient value is within a predetermined range. If the difference is within a predetermined range, the captured image is suitable for decoding. If the difference exceeds the predetermined range, the image control circuit 18 generates signals 58 and 60 to adjust the gain setting and the exposure period setting to the corrected parameter value (step 218). In step 220, the correction coefficient value and the correction parameter value are stored in the memory 19 by overwriting the current coefficient and parameter value existing in the memory. The correction coefficient value then becomes the current coefficient value. Another video image frame is captured (step 206) and the analysis process is repeated (steps 208, 216).

If the difference between the correction coefficient value and the current coefficient value is within a predetermined value range, the correction coefficient value and the correction parameter value are stored in the memory 19 by overwriting the current value (step 222). In step 224, the reader module 10 uses the decoding circuit to decode the data table in the captured frame. Finally, the reader module 10 is powered off, as shown in step 226, to save power between reading periods.

In order to achieve correct exposure, the reader module 10 of the present invention usually needs to capture 1 to 3 image fields. However, the circuit capture and comparison steps are very fast, even if three image fields need to be captured, the waiting time to achieve balance is usually 50 milliseconds or less.

1, the control and decoder board 14 also includes a data table decoding circuit 92, the data table decoding circuit 92 includes a decoding system embodied in the code executable by the microprocessor 16, the decoding system can be used to target or image The data table in field 166 is decoded. A suitable decoding system is described in U.S. Patent Application No. 08/456,909 and U.S. Patent Application No. 08/456,113 filed on May 17, 1995, and the contents of these two patent applications are incorporated herein by reference. Other decoding systems known in the art are also considered by the present invention. The decoded result is provided to other processing circuits (discussed later) through the data transmission link 300 (FIGS. 1, 2 and 6).

The control and decoder board 14 further includes a laser module simulation circuit 94, which is embodied in code executable by the microprocessor 16. The simulation circuit 94 encodes the decoded result in a standard one-dimensional bar code format, such as code 39, and outputs a square wave signal, which simulates the square wave signal of the laser scanner module scanning the one-dimensional code. It can be understood that this function provides compatibility with the circuit of the laser scanner module, and at the same time provides the ability to read data table classifications including two-dimensional bar codes and matrix codes. When working in the laser simulation mode, a square wave signal is generated to provide further processing through the data transmission chain 300.

In another embodiment of the reader module 10, because the reader module captures an image of the target field or area 166, this module, in addition to capturing the image of the data table, can be used to photograph objects in the target area . For example, the operator can use the reader module 10 to take a photo of a damaged product and capture an image of the data sheet associated with the damaged product. When the photographic image is captured, the decoder board transmits the digital image of the image, such as a bitmap, through the data transmission chain 300.

Figure 6 shows a partial cross-sectional top view of the camera assembly 12, which includes a microprocessor 351, a data transmission chain 300, and functions for performing open-loop gain control, open-loop exposure control, decoding, and other functions integrated into the camera assembly. About the circuit.

The performance of the data sheet reader module 10 is enhanced by providing an optical system 302 that includes an optical assembly 44 with an extended operating range. According to the position between the optical component 44 and the photosensor array 42, there is a best focus position S2 in front of the optical component 44. At this position, the object or the object image in the target field 166 can be most clearly reflected on the photosensor Array 42. When the object moves toward the field closer or farther than the cut-off distance S1, the image gradually deteriorates. The image component 44 also has an angular field of view 168, which is wide enough to image the large data table in the far field S3, while providing a large image of the small data table in the near field S1. In a preferred embodiment, the optical assembly 44 has a working range from about 2.5 inches to at least 8.5 inches from the front surface of the optical assembly, and the optimal distance is 5.5 inches. The preferred field of view is 8.5 inches away from the front surface 186 of the furthest lens 182, corresponding to a target area or surface that is 5 inches long by 3.75 inches wide.

The required optical system 302 includes a symmetrical lens structure. Two substantially identical lenses 182 and 184 will be located at the mirror symmetrical position of the aperture 190. The surface 186 of the lens 182 is an aspheric surface with a size and shape as defined by an evenasphere. Its radius of curvature is 1,5298mm, the conic constant is -0.019890, and the sixth-order aspheric deformation coefficient is 0.0096mm. The deformation coefficient of the 8th order aspheric surface is 0.0057mm, and the deformation coefficient of the 10th order aspheric surface is 0.0023mm. The rear surface 182 of the lens 182 is a spherical surface having a radius of curvature of 1.6004 mm. The width of the aperture 190 between the lenses 182 and 184 that provide F#13 to the optical assembly 44 is 0.3606 mm. The diameter of the lenses 182 and 184 is not critical in the present invention. A more detailed discussion of the optical system 302 of the present invention can be found in U.S. Patent Application No. 08/494,435, which is assigned to the same assignee as the present invention. U.S. Patent Application No. 08/494,435 is incorporated herein by reference in its entirety.

Because the optical system 302 is used in the portable data acquisition system 400 (one embodiment of the portable data acquisition system of the present invention is illustrated in FIGS. 10 and 11, the second embodiment of the portable data acquisition system of the present invention is shown in FIGS. 12 and 13 Described in). Therefore, it is desirable that the reader module 10 is light in weight and resistant to impact. In a preferred embodiment, the optical material used to make the lenses 182, 184 is composed of plastic. Compared with the same glass components, the use of plastic reduces the weight of the optical system 302 by 60% and provides a system that is more resistant to impact. Another advantage of using plastic optical materials is that it avoids the cost of grinding aspherical surfaces on the glass lens. The elliptical surface is easily formed by injection-molded plastic lens. The optical system 302 described herein provides the desired characteristics, and those skilled in the art know other optical devices with similar performance characteristics.

Because the expected working range and field of view of the reader module 10 indicate that the optical system 302 has a large F# (F#5.6 or greater), during the exposure period, the illumination module 47 must provide sufficient illumination of the target field 166 for the photoelectric sensor 42 absorbs enough emitted light to produce a video image of appropriate brightness. However, the exposure period must be limited to 0.01 seconds or less (see Figure 4) in order to reduce the effect of operator hand shake during the reading period. The exposure period of 0.01 second or less is significantly shorter than current CCD readers. Therefore, the lighting module 47 of the reader module 10 must provide sufficient lighting to accommodate a large F# and a short exposure period.

Assuming an exposure period of 0.03 seconds and F#1.2, an appropriate exposure period of the photosensor array 42 requires an object field illumination of 0.31 ux. In order to determine the 0.01 second exposure period and the appropriate object field illumination of F#13, the following formula is used: (illumination intensity) (exposure period) = constant (F#) 2 Therefore, the minimum object field illumination required by the reader module 10 of the present invention is The far field cut-off distance S3 is 1061 ux at the far field.

Referring to FIG. 7, which is a perspective view of the lighting module 47, it can be seen that the module includes a lens array 324 and a printed circuit board assembly 340. The printed circuit board assembly 340 includes a large number of surface-mounted lighting LEDs 346 fixed on the printed circuit board 354. The printed circuit board assembly 354 includes printed wires and power cords for powering the lighting LED 346. Suitable surface mount lighting LEDs are produced by MarkTech Corporation of Latham, NY, as Part No. MTSM735K-UR or MTSM745KA-UR. Each illumination LED 346 provides 285 microcandles (mcd) of illumination in an angular area of approximately 68 degrees. The small footprint of the illuminating LED346 allows 12 illuminating LEDs346 to be placed in a row measurement of less than 1.5". The printed circuit board footprint 354 includes two rows of illuminating LEDs346, a total of 24 LEDs, providing 6840mcd in a 68-degree field Even lighting.

The lens array 324 includes a large number of illuminating lens units 330, each of which is aimed at a corresponding illuminating LED 346. The exposure illumination lens unit 330 directs a 68-degree illumination field from each illumination LED 346 to a smaller uniform illumination field corresponding to the field of view 168 of the optical assembly 44 (approximately 50 degrees).

Referring to FIG. 8, it shows a side cross-sectional view of the lighting module 47. It can be seen that each lighting lens unit 330 has an inner lens surface 342 and a focus point 380. By positioning the illumination LED 346 between the focal point 380 and the inner surface 342, the lens unit lens unit 330 acts as an illumination guide element instead of an imaging element, thus avoiding hot spots in the target field 166 and providing highly uniform illumination . The 68 degree illumination field from each illumination LED 346 is collected by each illumination lens unit 330 and guided to a field corresponding to the optical system field of view 168 less than 68 degrees. Further, because the field of view of the exposure illumination lens unit 330 overlaps, there is "crosstalk" between the illumination LEDs 346, so that the illumination from two or more illumination LEDs is directed to the same part of the target field 166. Beyond the optical assembly field of view 168, the 6840mcd illumination provided by the illumination LED346 will provide an illumination intensity exceeding 1061 ux at a cut-off distance of 8.5" in the far field (S3 of FIG. 6).

Referring back to FIG. 7, the two target lens assemblies 334 on the target LED 347 extend the two pencils (comprising hot spots) of the target illumination 307 to the target area at an angle corresponding to the field of view 168 (FIG. 6) of the optical system. The hot spot is visible to the operator and makes the portable data acquisition system 400 (FIGS. 10-13) easy to locate, so that the target data table (not shown) is within the field of view 168 of the optical system 302.

The lens array 324 constitutes the front surface of the lighting module 47, and they protect the printed circuit board 340 from physical compression and damage from dust, moisture, and other harmful elements that can be found in the environment. Therefore, the lens array 324 is preferably made of impact-resistant acrylic or other suitable materials. These materials have high transparency and strength and are suitable for the working environment of the portable data acquisition system of the present invention. In order to further protect the printed circuit board assembly 340 from harmful elements in the environment, a conformal coating is applied to the board assembly 340, and the assembly is bonded to the cynoacrolate lens array by UV curing or construction adhesives. 324 in the rear cavity.

1 and 7, the lighting module 47 can be fixed to the front of the camera housing 46 by inserting four screws through the four holes 357 in the lighting module and screwing them to the coaxially arranged holes 359 in the camera housing 46.

Because the reader module 10 is designed to be used in a portable data acquisition system 400, the module includes an energy-saving circuit designed to work in conjunction with the two-position manual trigger 416 (Figures 10-13). The trigger can be a two-way trigger (release or push up) or a three-way trigger (release, first position and second position). During the reading period, the circuit controls the operation of the board camera 40 and the lighting module 47. Figure 9 shows a flow chart representing the state of the power control circuit. When in the off state 228, the power supply does not supply power to the lighting module 47 and the board camera 40.

When the three-position trigger is pushed to the first position, the reader module turns to the target alignment state 230. In the aiming state, the microprocessor activates the aiming LED 347, and at the same time the board camera 40 and the illumination LED 346 are disconnected. When the three-digit flip-flop is pushed to the second position, the module 10 enters the data table reading state 232. The data table reading state has two sub-states, the exposure state 234 and the decoding state 236. In the exposure state 234, the aiming LED 347 is turned off, and the illumination LED 347 and the board camera are activated at the same time.

After the image is captured, the module 10 enters the decoding state 236, in which the illumination LED 346 and the panel camera 40 are disconnected, and the targeting LED 347 is turned on to help the operator keep the reader system 400 at the time when the image capture and decoding is unsuccessful. position. If the decoding is successful, the reader module returns to the disconnected state 228. If the trigger is released, the reader module returns to the target alignment state 230 and the disconnected state 228. The timeout may also cause the module 10 to return to the disconnected state without successful decoding.

If the data acquisition system 400 only has two flip-flops, the module 10 can operate in two embodiments. In the first embodiment, the trigger pushing up causes the module 10 to enter the target alignment state 230. Releasing the trigger causes the system to enter the data table reading state 234. The exposure sub-state 234 and the decoding sub-state 236 operate similarly to the three-bit flip-flop embodiment. The timeout will cause the module 10 to return to the disconnected state.

In addition, pushing the trigger up can cause the module 10 to enter the fully automatic reading state 238. The module 10 will automatically enter the target state 230 for a period of time, and then enter the data table reading state 232. The operation of the data table reading state is the same as the embodiment discussed above. The trigger release will cause the module 10 to enter the disconnected state 228.

Figures 10, 11 and 12 illustrate two embodiments of a portable data acquisition system 400 according to the present invention. The same number is used to distinguish similar parts in the two embodiments. In the portable data acquisition system 400 shown in FIGS. 10 and 11, the system includes a housing 410 that looks like a gun. The housing 410 includes an upper portion 412 constituting an upper frame, and a hand-held portion 414 extending downward from the upper portion 412. The housing 410 has an impact-resistant plastic structure, which provides robustness and lightness. A two-position flip-flop 416 is properly installed and used to provide a signal to initiate the data table reading phase. Through the upper part 412 facing the aperture of the operator, a large number of keyswitches 422 and a display screen 432 covering the touch panel 444 can be seen.

The portable data acquisition system 400 shown in FIGS. 12 and 13 includes a generally rectangular housing 410, which is designed to be held in the palm of an operator. A large number of key switches on the upper part 412 of the housing 410 are installed in positions convenient for operation by the same hand holding the collection system 400. Through the aperture of the upper part 412, a display screen 432 covering the touch panel 444 can be seen. In order to have robustness and lightness, the housing 410 is made of impact-resistant plastic. The multi-bit flip-flop 416 used to initialize the reading period of the data table is centrally placed on the surface of the upper part 412 to initiate the reading period by the operator's thumb.

Referring to Figures 11 and 13, which respectively show a cross-sectional view of the portable data acquisition system 400 of Figures 10 and 12, it can be seen that each system includes a reader module, which includes a camera assembly 426 and a control and electrical connection with it. The decoder board 456. The camera assembly is located in the housing 410 immediately behind the front 418 of the housing. The lighting module 428 is installed at the front 418, and the camera assembly housing 464 protrudes an aperture 417 on the front 418 and an alignment aperture in the lighting module 428. A seal (not shown) may be installed on the front of the camera assembly housing 464 to establish a tight seal between the housing and the system housing 410, thereby preventing dust and moisture from entering the system housing through the aperture 417.

In a preferred embodiment, the control and decoder board 456 is connected to the main control board 431, and the main control board includes a microprocessor 413 to further process the data transmitted from the control and decoder board 456 to the main control board through the data transmission link. .

The main control board 431 includes a serial output port connected to the connector on the housing, which transmits the decoded data or image data to the remote terminal through a cable connection (not shown). The connector may be a traditional pin connector with mating connectors installed. In addition, as shown in Figures 10 and 11, the connector may include a conductive contact surface 460 on the outside of the housing 410, which is side by side with the mating contact surface when the device is placed in a docking station.

Because the data acquisition system 400 is used for portable use purposes, a wired connection to the host is not practical in many situations. Therefore, the portable data acquisition system 400 includes a spread spectrum microwave device (FIGS. 11 and 13) mounted on the board 433, which provides a wireless connection (not shown) between the main control board 431 and the remote host. An external antenna 446 as shown in FIG. 10, or an internal antenna 447 as shown in FIG. 13, works to improve wireless communication reception. The spread spectrum radio device board 433 includes digital and analog circuits for transmitting and receiving data in a wireless network compatible with a direct series spread spectrum or a frequency hopping spread spectrum network, such as IEEE802.11.

The power supply unit 448 supplies power to the circuit of the system 400. Both the spread spectrum radio and the data sheet reader module draw a large amount of current from the power supply unit 448. Therefore, during the data sheet reading period, the radio should not work, and during the communication period, the data sheet reading period should not start to limit the maximum current draw. Therefore, the radio device circuit and the reader module provide blocking signals to each other, thereby ensuring that the two parties do not simultaneously draw current. The blocking signal from the radio to the reader module will limit the initialization of the reading period. The reading period will be postponed until the end of the signal. The blocking signal from the reader module to the radio will restrict the radio from sending or receiving data packets. Therefore, the network transmission protocol must be that when the radio device in the portable data meter reader transmits data packets and can receive data packets, the device has completed control. One such protocol is the reversepoll protocol, which is described in U.S. Patent No. 5,279,680 assigned to Telesystems S/W. The '680 patent is incorporated herein by reference in its entirety.

In a reverse selection protocol network, as long as the carrier frequency is free, the portable device radio device can transmit data packets to a network access point at any time. However, the access point can only send one packet to the portable device within one time window after receiving one packet from the portable device. To ensure that the access point has enough opportunities to transmit data packets to the portable device, the portable device sends the packet regularly, even if the packet does not contain any meaningful data.

When the spread spectrum radio device effectively transmits the decoded content of the data table, the limited bandwidth of the radio device cannot transmit the entire uncompressed image. The image compression algorithm used to reduce the size of digital images is two-dimensional wavelet transform, which is described in "A64kb/sVideoCodeUsingthe2-DWaveletTransform" (64kb/s video code using two-dimensional wavelet transform) written by AS Lewis and G. Description, the book is published by IEEEComputerSocietyPress, the serial number is 2202. For example, the HARC wavelet transform system provided by the Houston Advanced Research Center in Houston, Texas can compress a photographic image with the highest compression ratio of 400:1 before it is transmitted.

Because the portable data acquisition system 400 of the present invention is intended to be used remotely, when capturing and decoding data tables, equipment operators working in remote locations may need to request management instructions. Therefore, it is preferable that the data collection system 400 of the present invention may further include a voice mail circuit 438 (FIG. 14), so that the operator may be able to perform voice communication with other personnel through the spread spectrum network. Referring to FIG. 14, it shows a block diagram of the voice mail circuit 438, which may be included in the voice mail processing board 437 (FIGS. 11 and 13) on the microprocessor system (not shown) or the main control board 431. Turning to FIG. 14, the voice message is input through the audio input circuit 492, and the audio input circuit may include an internal microphone or a port connected to an external microphone, which will be discussed in detail later. The digitization/compression module 494 will create a digital data file representing the audio input.

Before transmitting the message, the message control unit 498 will prompt the operator to confirm the recipient. The prompt may be in a manner of sending an audio signal (discussed later) to the operator through the audio output circuit 500 or displaying a screen message.

In the time slot after the prompt, the operator must confirm the recipient. This can be done via keyboard 422 or touchpad 444 (shown in Figures 10-13). In addition, the recipient can also be confirmed by audio input. In this inventive solution, the voice recognition circuit 502 converts the audio signal into a digital address.

The message control unit 498 will add the address to the message and relay the message to the spread spectrum transceiver for broadcasting to the recipient. It is reasonable that the voice mail system may require the recipient's operator to confirm before or after the message is entered.

The message control unit 498 works to receive data files representing the received voice mail messages and store these messages in the memory 496. When a message is received, the control unit 498 reminds the operator through the audio output circuit 500, a display screen or a special illuminator.

When the operator prompts to output the voice mail message, the control unit 498 will retrieve the data file from the memory. The decompression module converts the data file into an analog signal, which may include a speaker or remote speaker port or an audio output circuit of a headset that will output the message. The operator can prompt to output a message through the keyboard 422, the touch panel 444 or the audio input circuit 492.

After outputting the message, the voice mail circuit 438 may choose to store the message for later echoing, or delete the message. Along with storage and erasure, messages can be forwarded or answered. The voice mail circuit 438 will prompt the operator to enter a different arrangement of these choices. If the message is stored, the data file will remain in the memory 496. If forwarded, the data file or copy will be appropriately addressed and transferred to the spread spectrum radio board 433.

If the response option is selected, the address identity of the response message is known, and then the message control unit 498 prompts the operator to input the response message. Digital data files representing these messages are transmitted by the spread spectrum radio device board 433.

Referring to FIG. 12, the speaker 450 and the microphone 452 are properly installed so that the portable data communication system 400 can be held on the face of the operator like a telephone for communication. In another embodiment of the portable data collection system illustrated in FIGS. 12 and 13, the wireless headset 550 is used where the speaker 450 and the microphone 452 are installed in the housing 410. In the embodiment illustrated in FIG. 15, the speaker 517 and the microphone 519 may be included in the wireless headset 550. The headset includes a headband 515 for fixing the device on the head. The speaker 517 is installed near the operator's ear, and the microphone 519 is installed near the operator's mouth. The microwave device module and the power supply are installed at a position attached to the housing 521 of the headset 500. Similarly, the system housing 410 will include a microwave device module (not shown) that is compatible with the headset for transceiving audio signals. The microwave device module operates in a narrow-band modulation mode, where the frequency band is arranged in an empty space in the spectrum of the spread spectrum radio device.

In addition to working with wireless headsets, microwave devices can have functions such as wireless peripheral ports, so that operators do not have to physically connect the data acquisition system to a printer to print data sheet labels. Printers or other peripherals similar to the microwave device board can be installed in the entire device where the data acquisition system works. When the operator uses the peripherals with the system, the handshake sequence is initiated and the wireless link is established. Then the data can be printed to the peripheral.

Because the data acquisition system 400 of the present invention is intended for portable use, it is desirable that the power supply or power source 30 (FIGS. 11 and 13) can be used for long-term operation without the need for charging. Although the power source 30 can be any rechargeable battery, the preferred power source is a large number of Lithium Polymer flexible battery cells. Each film is about .002" (2mils) thick and looks like a piece of plastic. To make this battery, LiMn204 is used as the cathode and carbon is used as the anode. This battery can be provided by Bellcore of RedBank, New Jersey. Lithium Polymerization One advantage of the bulk battery is that the film form factor allows the battery to be folded and installed inside the casing. This part of the space is not enough for the traditional cylindrical battery. In Figure 13, the polymer sheet battery of the power supply 30 is advantageously installed along the casing The internal surface of the polymer battery also has the function of reducing unwanted EMS. In addition to the form factor and EMS advantages, the lithium polymer battery can also be recharged, and provides about 3 times the energy density of the nickel-cadmium battery, and will not be affected Nickel-cadmium batteries cause the disadvantage of crystallization of degraded memory effect.

The above description has explained the presently preferred embodiments of the present invention. Those familiar with the technology will know that other modifications can be made without departing from the present invention. The following intends to claim all modifications and changes within the scope of the present invention.

In accordance with the law, the present invention has been described in terms of more or less details as structural and system features. However, it should be understood that the present invention is not limited to the specific functions that have been shown or described, because the methods disclosed herein include preferred solutions for implementing the present invention. Therefore, the present invention requires patent protection for any form or change within the reasonable scope of the additional claims that are reasonably interpreted in accordance with the principle of fairness.