JP2002366887A - Symbol information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a symbol information reader which improves the read performance even for a moving body while maintaining relatively low power consumption even in dark environment and securely reads information that the mark of some pattern represents. SOLUTION: The symbol information reader is characterized in that matrix- arrayed photoelectric converting elements of a CMOS type image pickup element 25 are divided into groups of rows and a plurality of rows are exposed and read at a time in synchronism with each row (raster) of each group to shorten an image pickup period and a lighting turn-on period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a symbol information reading device for reading code information such as a bar code.

[0002]

2. Description of the Related Art In general, a bar code is known as a symbol mark (notation) representing information in a predetermined pattern. This barcode is formed by alternately arranging a plurality of bars and spaces having different widths to form a barcode character, and is widely used in, for example, a point-of-sale (POS) system. I have. This barcode is used for JAN (Japan Articale Numbe
It is standardized as r) and 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.

In accordance with such a demand for the amount of information of a barcode, a code system called a two-dimensional barcode, which has a different code system from a one-dimensional barcode, has been proposed, and is characterized in that much more information can be encoded. have. As the two-dimensional barcode, a method of increasing the information amount by stacking one-dimensional barcodes in two layers in the bar direction has been proposed. For example, "PDF-41"
There is a coding scheme called "7".

[0004] As a bar code information reading apparatus for reading such a two-dimensional bar code, a laser scanning type reading device that projects a laser beam in a two-dimensional manner and reads the reflected light to obtain information to be described. Equipment and CC
2. Description of the Related Art An imager-type reading apparatus that captures a barcode using a two-dimensional imaging element represented by D and decodes the barcode information by image processing has been put to practical use. As this imager type reader, a handheld type or a small one presumed to be incorporated in a data terminal has appeared, and has become the mainstream of two-dimensional symbol information readers.

[0005] With 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 pickup devices. Further, in the reading apparatus, in addition to high performance (high-speed reading, high resolution, etc.) and downsizing, the need for low power consumption in consideration of battery driving is increasingly demanded.

In response to such demands, it has been proposed to use a CMOS type image pickup device instead of the CCD type image pickup device. In general, a CMOS image sensor has characteristics of lower voltage driving and lower power consumption than a CCD image sensor.
Since peripheral circuits can also be integrated, they are suitable for portable reader applications.

[0007]

However, the aforementioned CM
Since the OS-type imaging device employs an imaging method as shown in FIG. 7, an image stored in the photoelectric conversion device in the imaging device is
This is like an image captured using a so-called “focal plane shutter”. 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. It is shifted by almost one frame. Therefore, FIG.
When a rectangular object moving at a speed v in the row direction of the image sensor as shown in FIG. 8A is photographed by a CMOS image sensor, a parallelogram as shown in FIG. When such a CMOS image sensor is mounted on a barcode reading device, the following problems exist.

[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. Period only). 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, so that the advantage of the low power consumption characteristic of the image sensor itself cannot be realized.

[0009] 2. Since the exposure period of the first raster and the final raster described above is shifted by about one frame, when a barcode moving relative to the apparatus is imaged, the imaged 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 apparatus, an influence appears when capturing an image of a moving object or when the image is shaken.

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 barcodes on a moving object with field information for the purpose of reading barcodes. Have been. However, this method inevitably sacrifices a certain amount of information and has a bad effect on reading high-density barcodes. Alternatively, there is a method of increasing the clock frequency of the image sensor. However, there is a problem in EMI countermeasures and a large design change such as a process change for performing high-speed reading may be difficult, so that it is difficult to introduce the method easily.

Therefore, the present invention improves the reading performance of a moving body while maintaining relatively low power consumption even in a dark environment, and reliably reads information represented by a mark of a certain pattern. An object of the present invention is to provide a symbol information reading device.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, a symbol in which a plurality of bars and spaces having different widths are arranged is imaged as a two-dimensional image, and symbol information for reading information represented by the symbol is read. A reading device, an illuminating unit for illuminating the mark, an illuminating unit controlling unit for controlling turning on and off of the illuminating unit, and a photoelectric converting unit including photoelectric converting elements arranged in a matrix of rows and columns. A plurality of groups are formed by a plurality of rows (rasters) of the photoelectric conversion means, one row is selected in each group, and signals of the selected rows are output in parallel during one horizontal period; In the next one horizontal period, an unselected row of each group is newly selected, and the signals of the newly selected rows are output in parallel. And the photoelectric conversion signal output means for outputting a signal 換素Ko, analyzing the photoelectric conversion signal and provides symbol information reading apparatus comprising a decode converting means for decoding the title represents information.

Further, 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). I will provide a. Also, 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) of the photoelectric conversion element and the exposure period of the last row (raster) overlap. I will provide a.

The symbol information reading apparatus having the above-described configuration performs exposure and output for N rows (rasters) collectively, reducing the time required for exposure and output for all rows to 1 / N. The illumination lighting time required for imaging is also reduced. In addition, if the illumination is turned on during a common overlapping period among the exposure periods of each row, the exposure of each row can be performed uniformly, and the illumination lighting time can be further reduced. 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 column units, synchronizes each group in one row (raster), and performs parallel processing. , Exposure and reading of a plurality of rows are performed at once, and the imaging period is shortened and the illumination lighting period is shortened.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic outline of a symbol information reading apparatus according to a first embodiment. FIG. 1A is a perspective view of the symbol information reading device 1 of the present embodiment, and FIG. 1B is a diagram of FIG. 1A viewed from a window side. Here, a barcode will be described below as an example of the symbol mark read by the present embodiment. This symbol information reading device is generally a short gun type and has a portable shape, and has a barrel portion 11 and a handle portion 12, a trigger 14 for starting reading of a bar code, and a transparent window 13 at the tip of the barrel portion. Have been. A scan engine 15 incorporating an image sensor is disposed in the barrel section 11 through the window 13. Therefore, when reading the bar code information, the window 13 is opposed to the bar code printed on the article or the sticker or the like, the trigger 14 is pulled, and the bar code is optically read and written. Barcode information can be obtained.

First, referring to FIG. 2 and FIG.
The scan engine 15 and the decode board 26 incorporated in the inside 1 will be described. The scan engine 15 includes a chassis 21, an imaging lens mounting unit 22, for example, 20 illumination LED mounting units 23 (23R and 23R).
L) and the engine board 24. further,
A CMOS imaging device 25 is mounted on the chassis 15 side of the engine substrate 24. Note that the imaging lens mounting unit 22
Has an opening on the window 13 side, and a lens (not shown) incorporated in the opening is arranged so as to guide a light image from an imaging target to a light receiving surface of the CMOS type imaging device 25. The illumination LED mounting portions 23 are also opened, and one LED is incorporated into each of the bottoms of these openings.

The decode board 26 is mounted with a processing / control section 27 for reading information from photographed image data and for controlling driving of each component described later, and is connected to the scan engine 15 via a flat cable 28. I have. 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 a block configuration of the symbol information reading device. The processing / control unit 27 mounted on the decode board 26
U31, system clock generation circuit 32, reset circuit 33, ASIC 34, memory unit 35 (SDRAM: 35
A, 35B) and the flash memory unit 36 (36A, 36)
B) and an I / F circuit 37 and the like, and are connected by a bus and a signal line, respectively. Among these, the firmware of the CPU 31 is stored in the flash memory 36 in advance, and is read as needed. 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 according to the host.

The ASIC 34 mainly provides an interface for a control signal with the scan engine 15 and an image signal (O
Data packing of DD and EVEN) (conversion from 8 bits to 32 bits), DMA to the memory unit 35, and the like are performed. The scan engine 15 converts an 8-bit odd (row) raster image signal (ODD) and an even (row) raster image signal (EVEN) into an image synchronization clock (PCL).
Output to the ASIC 34 in synchronization with K). At the same time, a vertical synchronizing signal (VSYNC) and a horizontal synchronizing signal (H
SYNC) to the ASIC 34. On the other hand, ASIC
34 to the scan engine 15 from the exposure time setting signal (E
XP) and an illumination lighting signal (ILLM).

The main operation for reading by the symbol information reading apparatus thus configured will be described. First, by turning on a power switch (not shown) provided in the reading device, the reading device is started up, an initial state is set, and reading becomes possible. When the operator turns the window 13 toward the bar code and pulls the trigger, the CPU 31 causes the exposure time setting signal (EXP) for setting a predetermined exposure time.
And an illumination lighting signal (ILLM) are transmitted to the scan engine 15 through the ASIC 34. Scan engine 15
The lighting is turned on based on these signals, and the CMOS
The imaging operation by the type imaging device 25 is started. The captured image is a vertical synchronization signal (VSYNC), a horizontal synchronization signal (HSYNC), and an image synchronization clock (PCLK).
In synchronization with the ASIC 34 as an odd raster image signal (ODD) and an even raster image signal (EVEN).
Transfer to

The ASIC 34 receives the transferred odd raster image signal (ODD) and even raster image signal (EVE).
N) is converted from 8 bits to 32 bits by a method described later, and is temporarily stored in the RAM 35 as image data.

Next, the CPU 31 reads out the image data stored in the RAM 35 and analyzes it. Here, if accurate information cannot be read from the captured image, that is, if it is determined that the brightness of the image is inappropriate, the exposure time setting signal (EXP)
And / or corrects the illumination lighting signal (ILLM), transmits those values to the scan engine 15 through the ASIC 34, captures a barcode in the same manner as the previous time, and captures it as image data. On the other hand, if it is determined that image data having sufficient lightness for decoding in the barcode information is stored in the RAM 35, the CPU 31 performs a decoding process and outputs the result (barcode information) via the I / F circuit 37. hand,
Send the barcode information to the host.

Next, FIG. 4 shows an example of the configuration of a CMOS image sensor. CMOS image sensor 2 of the present embodiment
Reference numeral 5 denotes 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 an image read out from an odd-numbered row of photoelectric conversion elements. An odd raster AD converter 44A for the signal and an even raster AD converter 44B for the image signal read from the photoelectric conversion elements in the even rows are provided.

The photoelectric conversion element group 41 is divided into odd rows and even rows, ie, two independent 240 rows × 640 rows.
The configuration is such that the photoelectric conversion element groups 41 in a row are interleaved. That is, any one of the even rasters
Select a raster, and at the same time, select any one of the odd rasters, and specify each of them as an odd raster AD.
Output is possible through a converter 44A and an even raster AD converter 44B. However, in the present embodiment, the first processing is performed so as to facilitate the decoding process.
The photoelectric conversion element control unit 42 controls the exposure period and the reading order so that the raster and the second raster, the third raster and the fourth raster,..., The 479th raster and the 480th raster are simultaneously output. The read data of each photoelectric conversion element 43 is transmitted to the AD converter 4
4A and 44B, are converted to digital values,
Output to C34.

Referring to the timing chart shown in FIG. 5, a method for reading data from the CMOS type image pickup device of this embodiment will be described. Since this CMOS image sensor performs exposure and readout at once by synchronizing two rasters, the readout clock (PCLK) and 1H
Even if the speed of (one horizontal scanning period) is not increased, the reading of all the photoelectric conversion elements can be completed in a period that is 1/2 of the period illustrated in FIG. Further, TΔ1 (the period from the start of the exposure of the first raster to the start of the exposure of the 480th raster) is also halved as compared with FIG.
The deformation Δ of the image when the moving object illustrated in FIG. 8 is imaged can be reduced to approximately half. Further, as shown in FIG. 5, the illumination lighting period (480th from the start of the exposure of the first raster)
The period until the completion of the raster exposure) TILM0 is の of the TILM shown in FIG. This makes it possible to halve the power consumption required for lighting the lighting.

FIG. 6 shows a data packing method (32) for an 8-bit odd raster image signal (ODD) and an even raster image signal (EVEN) in this embodiment.
Conversion method to bits) will be described. First, the image signal ODD and the image signal EVEN are acquired in synchronization with the read clock (PCLK). Image signal OD
D is an Odd packet, and image signal EVEN is Even.
Each is packed into packets. The Odd packet and the Even packet are sequentially transferred to eight packet buffers, respectively.

Odd buffers (OA to O) for eight packets
As soon as the data of H) is prepared, it is stored in back packets (oa to oh) and sequentially transferred to the memory. Similarly, the same processing is performed on the Even buffers (EA to EH).
Through the above processing, the image data stored in the RAM is analyzed to obtain barcode information.

Next, a second embodiment will be described. This embodiment has the same configuration as the above-described first embodiment, but differs in the lighting timing of the illumination.

If the illumination is turned on during TILM1 shown in FIG. 5 (the period in which the exposure period of the first raster and the 480th raster overlap), it is possible to uniformly apply the illumination to all the rasters. . Therefore, by adjusting the exposure period of each raster so that sufficient brightness is given to the captured image,
What is necessary is just to optimize this overlap period TILM1. This also enables high-speed readout and power saving at the time of lighting the illumination as in the first embodiment.

In the above-described embodiment, since information is read in a direction (row direction) crossing the imaged barcode row horizontally, for example, the barcode is in a direction orthogonal to the horizontal direction of the imaged screen. If you read without noticing that it has been affixed to the scanner, the reading will result in an error. As a countermeasure for preventing this error, an image processing unit for changing the direction of the image is provided, and first, a certain amount of image signals are detected in the horizontal direction, that is, the row direction of the captured barcode image, to indicate a bar. If no signal is detected, the analysis processing is interrupted, the image processing is performed by rotating the barcode image by 90 degrees, and then the image signal is analyzed in the row direction again, thereby realizing error prevention. it can. Further, a means for detecting the direction of the barcode image is provided, and before the barcode is captured and the image signal is analyzed, the direction of the barcode is detected, and if necessary, the direction of the barcode image is appropriately adjusted. Rotation processing may be performed. Further, as another method, since the image sensors of the CMOS image sensor are arranged in a matrix, when reading data from the image sensor, switching means for switching the scanning direction between rows and columns; Means for detecting the direction of the image may be provided so that, when the barcode image is in a direction orthogonal to the horizontal direction, the data reading direction is switched from the row direction to the column direction, and the reading process may be performed appropriately.

Although the above embodiments have been described, the present invention includes the following inventions. (1) A symbol information reading device which 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, illuminating means for illuminating the mark, and the lighting Forming illumination means control means for controlling turning on / off of the means, imaging means including photoelectric conversion elements arranged in a matrix of rows and columns, and forming a plurality of groups equally divided for each of a plurality of rows of the imaging means And
Imaging control means for outputting image signals of one row of photoelectric conversion elements in each group in parallel during one horizontal period, and thereafter sequentially outputting image signals from the photoelectric conversion elements in row units;
Decoding means for analyzing the image signal and decoding the image signal into information represented by the mark. (2) The symbol information reading apparatus according to (1), wherein the equal division in the imaging unit is performed so that the lines are interleaved line by line in a group order, and image pickup and image signal reading are performed for each group of the lines.

[0031]

As described in detail above, according to the present invention, it is possible to maintain a relatively low power consumption even in a dark environment and to improve the reading performance of a moving object, And a symbol information reading device for reliably reading the information represented by the symbol.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an external configuration of a symbol information reading device according to a first embodiment.

FIG. 2 is a diagram illustrating an external configuration of a scan engine and a decode board mounted on the symbol information reading device according to the first embodiment.

FIG. 3 is a diagram illustrating a block configuration of a symbol information reading device 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 CMOS image sensor data reading.

FIG. 6 is a diagram for explaining a data packing 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 imaging a moving target 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 ... Illumination LED mounting part 24 ... Engine board 25 ... CMOS type imaging element 26 ... Decoding 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

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Daishihisa Ichiki 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term in Olympus Optical Industrial Co., Ltd. (reference) 5B072 AA02 AA06 CC21 CC24 DD02 DD21 LL11 LL16 LL18 MM01

Claims (3)

[Claims] 1. A symbol information reading device which 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, an illuminating means for illuminating the mark, An illuminating means controlling means for controlling turning on / off of the illuminating means; a photoelectric converting means including photoelectric converting elements arranged in a matrix of rows and columns; and a plurality of groups of the plurality of rows of the photoelectric converting means. ,
One row is selected in each of the groups, and the photoelectric conversion signals of the selected rows are output in parallel during one horizontal period, and the unselected rows of each group are newly selected in the next one horizontal period. A photoelectric conversion signal output unit that outputs a photoelectric conversion signal from the photoelectric conversion element by selecting and outputting the photoelectric conversion signal of each newly selected row in parallel and sequentially repeating the photoelectric conversion signal; A symbol information reading device, comprising: decoding conversion means for analyzing and decoding into information represented by the mark. 2. The lighting control unit according to claim 1, wherein the lighting unit turns on the lighting 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 device according to 1. 3. The illumination control unit 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 of the photoelectric conversion elements and an exposure period of a last row overlap. Symbol information reading device.