JP4531294B2 - Symbol information reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a symbol information reading device that reads code information such as a barcode.
[0002]
[Prior art]
In general, a barcode is known as a symbol mark (notation) representing information in a certain predetermined pattern. This bar code is formed by alternately arranging a plurality of bars and spaces having different widths, and is widely used in, for example, point-of-sale (POS) systems. Yes. This barcode is standardized as JAN (Japan Articale Number), is used for general consumer goods, and is called a one-dimensional barcode. However, the amount of information that a one-dimensional barcode can have is about several tens of bytes, and the amount of information is not sufficient when actually used.
[0003]
A code system called a two-dimensional bar code, which is different from the one-dimensional bar code, is proposed in accordance with the demand for the information amount of the bar code, and has a feature that much more information can be coded. . For this two-dimensional barcode, a method for increasing the amount of information by stacking one-dimensional barcodes in two layers in the direction of the bar has been proposed. For example, there is a code system called “PDF-417”.
[0004]
As a barcode information reading device that reads such a two-dimensional barcode, a laser scanning type reading device that projects laser light so as to scan two-dimensionally and reads the reflected light to obtain information described, 2. Description of the Related Art An imager type reading device that uses a two-dimensional image sensor represented by a CCD to image a barcode and decodes the barcode information by image processing has been put into practical use. As this imager type reading device, a small-sized device premised on being incorporated into a handheld type or a data terminal has appeared and has become the mainstream of two-dimensional symbol information reading devices.
[0005]
Due to the rapid development of semiconductor device manufacturing technology in recent years, higher resolution, smaller size, lower power consumption, and the like have been realized in image sensors. In addition, in the reading apparatus, in addition to high performance (high-speed reading, high resolution, etc.) and miniaturization, there is a strong demand for low power consumption considering battery driving.
[0006]
In response to such demands, it has been proposed to employ a CMOS image sensor instead of a CCD image sensor. In general, CMOS image sensors are characterized by low voltage drive and low power consumption compared to CCD image sensors and can be integrated with peripheral circuits, making them suitable for portable reader applications. ing.
[0007]
[Problems to be solved by the invention]
However, since the above-described CMOS type image pickup device adopts an image pickup method as shown in FIG. 7, the image accumulated in the photoelectric conversion element in the image pickup device was taken using a so-called “focal plane shutter”. It looks like an image. That is, the exposure period is shifted by 1H (one horizontal scanning period) between the Nth raster and the (N + 1) th raster, and this is repeated to form one frame. Therefore, the exposure period is the first raster and the final raster. It is shifted by about one frame. Therefore, when a rectangular object moving at a speed v in the row direction of the image sensor as shown in FIG. 8A is photographed with a CMOS image sensor, a parallelogram as shown in FIG. 8B is obtained. Become. When such a CMOS image sensor is mounted on a bar code reader, there are the following problems.
[0008]
1. In a relatively dark environment, even if the exposure time is 1H (one horizontal scanning period), the illumination lighting period is one frame period (in a CCD image sensor capable of batch reading, the lighting time is 1H. Only period). For this reason, when the illumination is turned on, the illumination time is longer and the power consumption is larger than that of the CCD image sensor, and the advantage of low power consumption characteristics of the image sensor itself does not live.
[0009]
2. In the first raster and the final raster described above, the exposure period is shifted by about one frame. Therefore, when a barcode that moves relative to the apparatus is imaged, the imaging shape is likely to be distorted, and sufficient reading performance may not be obtained. There is. In the case of a hand-held type reading device, an influence is exerted on imaging of a moving object and camera shake.
[0010]
Conventionally, in order to obtain barcode information at high speed, for example, Japanese Patent Application Laid-Open No. 8-329185 discloses a method of reading with field information for the purpose of reading a barcode on a moving object. . However, this method inevitably sacrifices a certain amount of information, and has a bad influence on reading a high-density barcode. Alternatively, there is a method of increasing the clock frequency of the image pickup device, but there is a problem in measures against EMI and a large design change such as a process change for performing high-speed reading, which is difficult to introduce easily.
[0011]
Therefore, the present invention improves the reading performance for a moving object while maintaining relatively low power consumption even in a dark environment, and reliably reads information represented by a certain pattern mark. An object is to provide an apparatus.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a symbol information reading apparatus for capturing a two-dimensional image of a mark in which a plurality of bars and spaces having different widths are arranged, and reading information represented by the mark. Illuminating means for illuminating, illuminating means controlling means for controlling on / off of the illuminating means, photoelectric converting means including photoelectric conversion elements arranged in a matrix of rows and columns, and a plurality of rows of the photoelectric converting means (Raster) constitutes a plurality of groups, each row is selected in each group, and signals of each selected row are output in parallel during one horizontal period, and each group is output in the next one horizontal period. A photoelectric device that newly selects a row that has not yet been selected and outputs the signal of each newly selected row in parallel, and outputs the signal of the photoelectric conversion element by sequentially repeating this. And signal output means analyzes the photoelectric conversion signal and provides symbol information reading apparatus comprising a decode converting means for decoding the title represents information.
[0013]
Furthermore, the present invention provides a symbol information reading device in which the illumination control means turns on the illumination means from the start of the exposure period of the first row (raster) of the photoelectric conversion element to the end of the exposure period of the last row (raster). . Further, the present invention provides a symbol information reading device in which the illumination control means turns on the illumination means during a period in which the exposure period of the first row (raster) and the exposure period of the last row (raster) overlap. I will provide a.
[0014]
The symbol information reading apparatus configured as described above performs exposure and output for N rows (raster) collectively, reducing the time required for exposure and output of all rows to 1 / N, and as a result, for imaging. The lighting time required for lighting is also shortened. Further, if the lighting is turned on during the overlapping period in the exposure period of each row, the exposure of each row can be performed uniformly, and the illumination lighting time can be further shortened. Further, this symbol information reading apparatus divides a plurality of photoelectric conversion elements arranged in a matrix of photoelectric conversion means into groups (groups) in units of columns, and synchronizes each row (raster) for each group, By performing parallel processing, a plurality of rows are exposed and read at a time, and the imaging period is shortened and the illumination lighting period is shortened.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic outline of a symbol information reading apparatus according to the first embodiment. FIG. 1A is a perspective view of the symbol information reading apparatus 1 of the present embodiment, and FIG. 1B is a view of FIG. 1A viewed from the window side. Here, as a symbol mark to be read by the present embodiment, a barcode will be described as an example.
This symbol information reading device is generally a short gun type and has a portable shape, and the exterior is composed of a barrel part 11 and a handle part 12, a trigger 14 for starting barcode reading, and a transparent window 13 at the tip of the barrel part. Has been. A scan engine 15 incorporating an image sensor is arranged in the barrel portion 11 through the window 13. Therefore, when reading the barcode information, the window 13 is opposed to the barcode printed on the article, a sticker or the like, the trigger 14 is pulled, and the barcode is optically read and described. Bar code information can be obtained.
[0016]
First, the scan engine 15 and the decode board 26 incorporated in the barrel part 11 will be described with reference to FIGS.
The scan engine 15 includes a chassis 21, an imaging lens mounting portion 22, for example, 20 lighting LED mounting portions 23 (23 R and 23 L) and an engine board 24. Further, a CMOS image sensor 25 is mounted on the chassis 15 side of the engine substrate 24. The imaging lens mounting portion 22 has an opening on the window 13 side, and a lens (not shown) incorporated in the opening guides the light image from the imaging target to the light receiving surface of the CMOS image sensor 25. Has been placed. Moreover, the LED mounting part 23 for illumination is each opened, and one LED is each incorporated in these opening bottom parts.
[0017]
The decode board 26 is mounted with a processing / control unit 27 for reading information from the captured image data and driving control of each component described later, and is connected to the scan engine 15 by a flat cable 28. Further, it is connected to a host computer or the like via a connection cable (not shown) for outputting and transmitting the decoding result of the barcode information.
FIG. 3 shows and describes the block configuration of this symbol information reading apparatus.
The processing / control unit 27 mounted on the decode board 26 includes a CPU 31, a system clock generation circuit 32, a reset circuit 33, an ASIC 34, a memory unit 35 (SDRAM: 35A, 35B), a flash memory unit 36 (36A, 36B), and an I / F circuit 37 and the like, each connected by a bus or a signal line. Among these, the flash memory 36 stores the firmware of the CPU 31 in advance and is read out as necessary. The I / F circuit 37 acts to transmit the read barcode information to the host computer, and has an interface function such as RS232C or USB corresponding to the host for that purpose.
[0018]
The ASIC 34 mainly performs control signal interface with the scan engine 15, data packing of image signals (ODD and EVEN) (conversion from 8 bits to 32 bits), DMA to the memory unit 35, and the like. The scan engine 15 outputs an 8-bit odd (row) raster image signal (ODD) and an even (row) raster image signal (EVEN) to the ASIC 34 in synchronization with the image synchronization clock (PCLK). At the same time, the vertical synchronizing signal (VSYNC) and horizontal synchronizing signal (HSYNC) of the image are output to the ASIC 34. On the other hand, an exposure time setting signal (EXP) and an illumination lighting signal (ILLM) are input from the ASIC 34 to the scan engine 15.
[0019]
A main operation for reading by the symbol information reading apparatus configured as described above will be described.
First, when the power switch (not shown) provided in the reading device is turned on, it is activated and an initial state is set, and reading is enabled. When the operator pulls the trigger with the window 13 facing the barcode, the CPU 31 transmits an exposure time setting signal (EXP) and an illumination lighting signal (ILLM) for setting a predetermined exposure time to the scan engine 15 through the ASIC 34. . Based on these signals, the scan engine 15 is turned on, and an imaging operation by the CMOS image sensor 25 is started. The captured image is synchronized with the vertical synchronization signal (VSYNC), the horizontal synchronization signal (HSYNC), and the image synchronization clock (PCLK), and sent to the ASIC 34 as an odd raster image signal (ODD) and an even raster image signal (EVEN). Forward.
[0020]
The ASIC 34 converts the transferred odd raster image signal (ODD) and even raster image signal (EVEN) from 8 bits to 32 bits by a method to be described later, and temporarily stores the converted data as image data in the RAM 35.
[0021]
Next, the CPU 31 reads and analyzes the image data stored in the RAM 35. Here, when accurate information cannot be read from the captured image, that is, when it is determined that the brightness of the image is inappropriate, the exposure time setting signal (EXP) and / or the illumination lighting signal (ILLM) are corrected, The value is transmitted to the scan engine 15 through the ASIC 34, and the barcode is imaged in the same manner as the previous time, and is taken in as image data. On the other hand, if it is determined that image data having sufficient lightness for decoding the barcode information is stored in the RAM 35, the CPU 31 performs a decoding process and sends the result (barcode information) via the I / F circuit 37. To the bar code information to the host.
[0022]
Next, FIG. 4 illustrates an example of the configuration of a CMOS image sensor.
The CMOS image sensor 25 of the present embodiment includes a photoelectric conversion element group 41 in which a large number of photoelectric conversion elements 43 are arranged in a matrix of 480 rows × 640 columns, a photoelectric conversion element control unit 42 that drives these elements, and odd-numbered rows. The odd-number raster AD converter 44A for the image signal read out from the photoelectric conversion elements of the even number raster, and the even-number raster AD converter 44B for the image signal read out from the photoelectric conversion elements of the even-numbered rows.
[0023]
This photoelectric conversion element group 41 has a configuration in which two independent 240 x 640 photoelectric conversion element groups 41, which are divided into odd and even rows, are interleaved. That is, any one raster is selected from among even-numbered rasters, and any one raster from among odd-numbered rasters is selected at the same time, and each can be output through the odd-numbered raster AD converter 44A and the even-numbered raster AD converter 44B. ing. However, in the present embodiment, the first raster and the second raster, the third raster and the fourth raster,..., The 479 raster and the 480 raster are output at the same time for easy decoding. The photoelectric conversion element control unit 42 controls the exposure period and the reading order. The read data of each photoelectric conversion element 43 is converted into a digital value by the AD converters 44 </ b> A and 44 </ b> B and output to the ASIC 34.
[0024]
With reference to the timing chart shown in FIG. 5, a method for reading from the CMOS image sensor of this embodiment will be described.
Since this CMOS type image pickup device performs exposure and reading at a time by synchronizing two rasters, even if the reading clock (PCLK) and 1H (one horizontal scanning period) are not speeded up, FIG. Reading of all the photoelectric conversion elements can be completed in a period ½ of the period described in. In addition, since TΔ1 (the period from the start of exposure of the first raster to the start of exposure of the 480 raster) is also halved compared to FIG. 7, the image of the moving body illustrated in FIG. The deformation Δ of the image can be reduced to approximately half. Further, as shown in FIG. 5, the illumination lighting period (period from the start of exposure of the first raster to the completion of exposure of the 480th raster) TILM0 is ½ of the TILM shown in FIG. As a result, it is possible to halve the power consumption required for lighting.
[0025]
FIG. 6 illustrates a data packing method (a conversion method to 32 bits) for an 8-bit odd raster image signal (ODD) and an even raster image signal (EVEN) in the present embodiment.
First, the image signal ODD and the image signal EVEN are acquired in synchronization with the read clock (PCLK). The image signal ODD is packed into an odd packet, and the image signal EVEN is packed into an even packet. The Odd packet and the Even packet are sequentially transferred to 8 packet buffers, respectively.
[0026]
As soon as the data in the Odd buffer (OA to OH) for 8 packets is ready, the data is stored in the back packet (oa to oh) and sequentially transferred to the memory. Similarly, the same processing is performed for the even buffers (EA to EH).
The bar code information is obtained by analyzing the image data stored in the RAM by the above processing.
[0027]
Next, a second embodiment will be described.
The present embodiment has the same configuration as that of the first embodiment described above, but is different in lighting timing.
[0028]
If the illumination is turned on during the TILM1 shown in FIG. 5 (the period in which the exposure periods of the first raster and the 480th raster overlap), it is possible to provide illumination uniformly to all the rasters. Therefore, the overlap period TILM1 may be optimized by adjusting the exposure period of each raster so that sufficient brightness is given to the captured image. This also enables high-speed reading and power saving when the lighting is turned on, as in the first embodiment.
[0029]
In the above-described embodiment, since the information is read in the direction (row direction) that horizontally traverses the captured bar code string, for example, the bar code is pasted in a direction orthogonal to the horizontal direction of the imaging screen. If you are reading without knowing what was happening, reading will result in an error. As a measure to prevent this error, an image processing unit that converts the direction of the image is provided, and first, a certain amount of image signal is detected in the horizontal direction of the captured barcode image, that is, in the row direction to indicate the bar. If no signal is detected, the analysis process is interrupted, the bar code image is rotated 90 degrees, the image signal is analyzed again in the row direction, and error prevention is realized. it can. Further, a means for detecting the direction of the barcode image is provided so that the barcode direction is detected before imaging the barcode and analyzing the image signal. If necessary, the direction of the barcode image is appropriately set. You may perform the process to rotate.
As another method, since the image pickup elements of the CMOS type image pickup element are arranged in a matrix, when reading data from the image pickup element, switching means for switching the scanning direction between rows and columns, and a barcode Means for detecting the direction of the image may be provided, and when the barcode image is in a direction perpendicular to the horizontal direction, the data reading direction may be switched from the row direction to the column direction and the appropriate processing may be performed.
[0030]
Although the above embodiments have been described, the present invention includes the following inventions.
(1) A symbol information reading device that captures a mark in which a plurality of bars and spaces having different widths are arranged as a two-dimensional image and reads information represented by the mark,
Illumination means for illuminating the mark;
Illumination means control means for controlling lighting / extinguishing of the illumination means,
Imaging means including photoelectric conversion elements arranged in a matrix with rows and columns;
A plurality of groups equally divided for each of a plurality of rows of the image pickup means are formed, and image signals of one row of photoelectric conversion elements are output in parallel during one horizontal period for each group, and thereafter the rows are sequentially Imaging control means for outputting an image signal from the photoelectric conversion element in units;
Decode conversion means for analyzing the image signal and decoding the information represented by the mark;
A symbol information reading apparatus comprising:
(2) The symbol information reading device according to (1), wherein the equal division in the imaging unit is divided so that the rows are interleaved in the group order, and imaging and image signal reading are performed for each group of the rows.
[0031]
【The invention's effect】
As described above in detail, according to the present invention, the information represented by the mark of a certain pattern can be achieved while maintaining relatively low power consumption even in a dark environment and improving the reading performance for a moving object. Can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an external configuration of a symbol information reading apparatus as a first embodiment.
FIG. 2 is a diagram showing an external configuration of a scan engine and a decode board mounted on the symbol information reading apparatus of the first embodiment.
FIG. 3 is a diagram illustrating a block configuration of the symbol information reading apparatus according to the first embodiment;
FIG. 4 is a diagram illustrating a configuration example of a CMOS image sensor.
FIG. 5 is a timing chart for explaining reading of CMOS image sensor data.
FIG. 6 is a diagram for explaining a data pack method;
FIG. 7 is a timing chart for explaining conventional data reading from a CMOS image sensor.
FIG. 8 is a diagram for explaining image deformation at the time of moving object imaging in a conventional CMOS image sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Barrel part 12 ... Handle part 13 ... Window 14 ... Trigger 15 ... Scan engine 21 ... Chassis 22 ... Imaging lens mounting part 23, 23R, 23L ... LED mounting part 24 for illumination ... Engine board 25 ... CMOS type image pick-up element 26 ... Decode board 27 ... Processing / control unit 28 ... Flat cable 31 ... CPU
32 ... System clock generation circuit 33 ... Reset circuit 34 ... ASIC
35 ... DRAM
36 ... Flash memory 37 ... I / F circuit

Claims (5)

A symbol information reading device for imaging a mark in which a plurality of bars and spaces having different widths are arranged as a two-dimensional image and reading information represented by the mark, and lighting means for illuminating the mark, and lighting of the lighting means A lighting unit control unit that performs extinction control, a photoelectric conversion unit that includes photoelectric conversion elements arranged in a matrix of rows and columns, and a plurality of rows of the photoelectric conversion units constitute a plurality of groups, and each group And a photoelectric conversion signal of each selected row is output in parallel during one horizontal period, and a row not yet selected in each group is newly selected in the next horizontal period and Photoelectric conversion signal output means for outputting photoelectric conversion signals for each newly selected row in parallel and sequentially repeating this to output photoelectric conversion signals from the photoelectric conversion elements; Analyzing the photoelectric conversion signal, symbol information reading apparatus characterized by comprising a, a decoding transformation means for decoding the title represents information. 2. The symbol information reading apparatus according to claim 1, wherein the illumination control unit turns on the illumination unit from the start of the exposure period of the first row of the photoelectric conversion elements to the end of the exposure period of the last row. 2. The symbol information reading apparatus according to claim 1, wherein the illumination control unit turns on the illumination unit during a period in which an exposure period of a first row and an exposure period of a last row of the photoelectric conversion elements overlap. . A symbol information reading device for imaging a mark in which a plurality of bars and spaces having different widths are arranged as a two-dimensional image and reading information represented by the mark, and lighting means for illuminating the mark, and lighting of the lighting means Forming a plurality of groups equally divided for each of a plurality of rows of the imaging means, an illumination means control means for performing a light extinction control, an imaging means including photoelectric conversion elements arranged in a matrix with rows and columns, Imaging control means for outputting image signals of one row of photoelectric conversion elements in each group in parallel during one horizontal period, and sequentially outputting image signals from the photoelectric conversion elements in units of rows, and the image signals Decoding conversion means for analyzing and decoding the information represented by the mark. The symbol information reading apparatus according to claim 4, wherein the equal division in the imaging unit is divided so that the rows are interleaved one by one in the group order, and imaging and image signal reading are performed for each group of the rows.

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