JP2013061999A - Symbol-recognizing device and control program for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a symbol-recognizing device which can illuminate a two-dimensional symbol with an optimum light quantity and efficiently recognize the two-dimensional symbol.SOLUTION: A light source 30 which divides an object 3, which is an object to be picked up, into a plurality of areas and partially illuminates the areas is provided in a symbol-recognizing device. An image of the object 3 which is illuminated by the light source 30 is picked up by an image sensor 32, and a decoder 33 decodes QR codes from the image which is result of image pickup. Then, when decoding by the decoder 33 fails, a gradation measurement part 23 measures average gradation of the plurality of areas in image data, and a control part 21 determines power-on time for respective LED light sources 101-104 which constitutes the light source 30, on the basis of result of measurement. A light source-drive circuit 22 controls the respective LED light sources 101-104 according to the power-on time which are thus determined, and illuminates the object 3 to try imaging and decoding again.

Description

  The present invention relates to a symbol recognition apparatus such as a scanner that captures a two-dimensional symbol such as a QR code (registered trademark) with an imaging unit and recognizes the two-dimensional symbol from the image, and a control program thereof.

  A laser recognition method for recognizing a symbol such as a barcode attached to an article, a card medium, a leaflet, or the like is mainly a laser system that scans a laser beam. However, on the other hand, in recent years, a so-called camera imaging method has been developed in which a two-dimensional image of an article with a symbol is taken by an imaging means and the symbol is recognized from this image. This type of symbol recognition device guides a symbol image to an image sensor through an imaging lens and converts it into an analog signal. The analog signal is converted into a binarized output by a binarization circuit and then decoded by a decoder. It is designed to output the numerical value.

  In a camera imaging type symbol recognition device, if an excessive or insufficient amount of light from the subject occurs, the symbol may not be read accurately. Various inventions have been made to solve such problems. For example, the barcode reader disclosed in Patent Document 1 partially controls the light distribution to the barcode according to the level of the video signal obtained by imaging the barcode and the reading rate.

JP-A-9-153106

  In recent years, two-dimensional symbols such as QR codes capable of expressing information larger in size than barcodes in which one-dimensional bar patterns are arranged are becoming widespread. A symbol recognition apparatus for recognizing a two-dimensional symbol generally employs the camera imaging method. Therefore, the above-described problem relating to excess or deficiency in the amount of light to the subject may occur. Since the two-dimensional symbol recognizes a large number of symbols arranged in a matrix at the same time, the technique for controlling the one-dimensional partial illumination as disclosed in Patent Document 1 is further improved. There is a need.

  The present invention has been made based on the above situation, and an object of the present invention is to provide a symbol recognition device that can illuminate a two-dimensional symbol with an optimum light amount and efficiently recognizes the two-dimensional symbol. is there.

  In order to achieve the above object, the present invention takes the following measures.

  According to a first aspect of the present invention, there is provided illumination means for partially illuminating a subject into a plurality of regions, imaging means for imaging the subject illuminated by the illumination means and generating image data, and the imaging Decoding means for decoding a two-dimensional symbol included in the image data generated by the means, and the plurality of lights illuminated by the illumination means from the image data generated by the imaging means when decoding by the decoding means fails Gradation measuring means for measuring gradation information for each area, and the illumination means illuminates each of the plurality of areas based on the gradation information for each of the plurality of areas measured by the gradation measuring means. A correction unit that corrects the light distribution to be performed, and the illumination unit is driven according to the light distribution corrected by the correction unit to illuminate each of the plurality of regions. It is a symbol recognition device including a light driving means.

  A second aspect of the present invention is a control program for the symbol recognition apparatus.

  According to the present invention in which such a measure is taken, it is possible to provide a symbol recognition device that can illuminate a two-dimensional symbol with an optimum light amount and efficiently recognizes the two-dimensional symbol.

The figure which shows the use condition of the symbol recognition apparatus in one Embodiment of this invention. The block diagram which shows the principal part structure of the symbol recognition apparatus. The figure which shows the example of a division | segmentation of the image data which the symbol recognition apparatus handles. Schematic which shows the AA cross section of the symbol recognition apparatus shown in FIG. Schematic which shows the BB cross section of the symbol recognition apparatus shown in FIG. The flowchart which shows the procedure in which the symbol recognition apparatus recognizes QR code. The figure for demonstrating the procedure in which the symbol recognition apparatus correct | amends the energization time of each LED light source. The figure for demonstrating the example of control of the LED light source by the symbol recognition apparatus. The figure for demonstrating the example of control of the LED light source by the symbol recognition apparatus. The figure for demonstrating the example of control of the LED light source by the symbol recognition apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
This embodiment is an example in which the present invention is applied to a symbol recognition apparatus that is a scanner that reads a QR code.

  FIG. 1 is a schematic diagram showing a usage state of the symbol recognition device 1. The symbol recognition device 1 is provided on the side surface of the information processing terminal 2. The information processing terminal 2 is, for example, a POS (Point Of Sales) terminal used for a checkout operation at a retail store or the like, or a product information registration device provided on a cash register counter connected to the POS terminal.

  The symbol recognition device 1 is formed by fitting a light-transmissive glass member 11 into a rectangular parallelepiped case 10. When the QR code 4 attached to the subject 3 is put on the glass member 11, the symbol recognition device 1 recognizes the QR code 4 and inputs information indicated by the QR code 4 to the control circuit of the information processing terminal 2. . The information processing terminal 2 performs predetermined information processing using information input from the symbol recognition device 1.

  FIG. 2 is a block diagram showing a main configuration of the symbol recognition apparatus 1. The symbol recognition device 1 includes a main control board 20, a light source 30, a lens 31, an image sensor 32, and a decoder 33.

  The light source 30 functions as an illuminating unit in the present embodiment, and is composed of four LED light sources 101 to 104 that partially illuminate the subject 3 covered with the glass member 11.

  The main control board 20 includes a control unit 21 including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, a light source driving circuit 22, a gradation measuring unit 23, And a light distribution storage unit 24.

  The light source driving circuit 22 functions as an illumination driving unit in the present embodiment, and controls lighting / extinguishing of the LED light sources 101 to 104 independently. In particular, in this embodiment, the light distribution to the subject is adjusted by selectively changing the energization time to each of the LED light sources 101-104.

  The lens 31 causes the image sensor 32 to form an image of the reflected light that is irradiated from the light source 30 and reflected back to the subject 3.

  The image sensor 32 functions as an image pickup unit in the present embodiment, and is configured by an image pickup device such as a charge coupled diode (CCD) or a complementary metal-oxide semiconductor (CMOS), and is an optical image formed by the lens 31. Multi-tone image data D is generated by photoelectrically converting the image. The generated image data D is output to the decoder 33 and the control unit 21.

  The decoder 33 functions as a decoding unit in the present embodiment, and decodes the QR code 4 included in the image data D input from the image sensor 32. Further, the decoder 33 outputs the decoded data to the information processing terminal 2 if the decoding of the QR code 4 is successful, and if the decoding of the QR code 4 fails, that effect and the cut-out symbol detected in the decoding process Is notified to the control unit 21.

The decoding of the QR code 4 by the decoder 33 is performed as follows using the characteristics of the QR code.
The QR code 4 is composed of black and white cells arranged vertically and horizontally, and has cutout symbols (M shown in FIG. 2) which are position determination symbols provided at three corners. When decoding the QR code 4, first, this cut-out symbol is detected. Each cut-out symbol is a pattern having a specific ratio (for example, black 1: white 1: black 3: white 1: black 1) independent of the scanning direction. Therefore, if this specific ratio is detected from the image data D, each cut-out symbol can be detected. When these cut-out symbols are detected, the position, size, and inclination of the QR code 4 are determined, and the QR code 4 portion is cut out from the background of the image data D. Then, the center position of each cell constituting the QR code 4 is obtained, and a bit matrix of the QR code 4 is obtained. The QR code 4 includes a bit pattern for error detection / correction using a Reed-Solomon code or the like. Error detection / correction can be performed by a known procedure using this bit pattern.

  The gradation measuring unit 23 functions as a gradation measuring unit in the present embodiment, and divides the image data D input from the image sensor 32 via the control unit 21 into a plurality of predetermined areas. The average gradation (gradation information) of each area is calculated. The calculated average gradation of each area is output to the control unit 21 and the light distribution storage unit 24. In the present embodiment, as shown in FIG. 3, the image data D is converted into an area 101a illuminated by the LED light source 101, an area 102a illuminated by the LED light source 102, an area 103a illuminated by the LED light source 103, and an LED light source. The gradation measurement unit 23 calculates the average gradation of each of the areas 101a to 104a.

  The light distribution storage unit 24 stores energization times of the LED light sources 101 to 104 output from the control unit 21.

  The control unit 21 controls each unit constituting the control circuit of the symbol recognition device 1. Moreover, the control part 21 implement | achieves the function as a correction | amendment means in this embodiment by the information processing using software. That is, based on the average gradation of the areas 101a to 104a measured by the gradation measuring unit 23, the light distribution that the light source 30 illuminates each of the areas 101a to 104a is corrected. At this time, the light distribution for illuminating each of the areas 101a to 104a is corrected so that the difference in average gradation of the areas 101a to 104a is small. The light distribution is corrected by adjusting the energization time to each of the LED light sources 101-104.

4 is a schematic diagram showing an AA section of the symbol recognition apparatus 1 shown in FIG. 1, and FIG. 5 is a schematic diagram showing a BB section of the symbol recognition apparatus 1 shown in FIG.
As shown in FIG. 4, the case 10 is formed by the top cover 12 and the bottom cover 13, and the main control board 20, the light source 30, the lens 31, the image sensor 32, and the decoder are formed in the case 10. 33 is stored.

  On the top surface 12a of the top cover 12, a bowl-shaped recess 12b having a rectangular edge is formed. The glass member 11 is fitted into the top cover 12 so as to close the recess 12b of the top surface 12a and be flush with the top surface 12a. The lens 31 is fixed to the image sensor 32 so that its central axis passes through the center of the recess 12 b of the top cover 12.

  The main control board 20 is provided between the glass member 11 and the lens 31. The main control board 20 is formed with a circular opening 20 a centered on an extension line of the central axis of the lens 31 so that the subject image reaches the lens 31.

  The LED light sources 101 to 104 are each composed of two LEDs in order to ensure a wide adjustable light amount width. The LED light source 101 is positioned on the upper left side of the opening 20a, the LED light source 102 is positioned on the lower left side of the opening 20a, the LED light source 103 is positioned on the upper right side of the opening 20a, and the LED light source 104 is positioned on the lower right side of the opening 20a. The main control board 20 is fixed.

Next, the operation of the symbol recognition device 1 will be described.
FIG. 6 is a flowchart illustrating a procedure in which the symbol recognition apparatus 1 recognizes a QR code.
When a command to start imaging is input from the information processing terminal 2 to the symbol recognition device 1, first, the control unit 21 defaults the energization time to each of the LED light sources 101 to 104 stored in the light distribution storage unit 24 (energization time t ms) (step S1). Further, the control unit 21 instructs the light source driving circuit 22 to start illumination, and instructs the image sensor 32 to image the subject.

  The light source drive circuit 22 that has received an instruction to start illumination from the control unit 21 drives the LED light sources 101 to 104 according to the energization times of the LED light sources 101 to 104 stored in the light distribution storage unit 24 to illuminate the subject. . In synchronization with the LED light sources 101 to 104 illuminating the subject, the image sensor 32 photoelectrically converts the reflected light of the illumination imaged by the lens 31 to generate image data D to generate the control unit 21 and the decoder 33. (Step S2). The decoder 33 tries to decode the QR code included in the image data D output from the image sensor 32 (step S3).

  When the decoder 33 successfully decodes the QR code, the decoder 33 outputs the decoded information to the information processing terminal 2 and notifies the control unit 21 of the decoding success. The information processing terminal 2 performs predetermined information processing using the information output from the symbol recognition device 1. When the control unit 21 is notified of the success of decoding (Yes in step S4), the control unit 21 resets the energization times of the LED light sources 101 to 104 stored in the light distribution storage unit 24 to default (step S1). ). Thereafter, the image picked up by the image sensor 32 of the subject next to be struck by the glass member 11 and the decoding by the decoder 33 of the QR code included in the picked up image are repeated (steps S2, S3, etc.).

  On the other hand, if the decoding of the QR code 4 fails (No in step S4), the decoder 33 notifies the control unit 21 of that fact and the number of cut-out symbols that have been successfully detected in the process of decoding the QR code. Upon receiving this notification, the control unit 21 determines the number of cut-out symbols detected based on the notification from the decoder 33 (step S5).

  If the decoder 33 has not detected any cutout symbols (“detection number 0” in step S5), it is assumed that the QR code has not been placed at the reading position. In such a case, there is little need to adjust the light quantity of the LED light sources 101-104. Therefore, the control part 21 sets all the energization time of each LED light source 101-104 memorize | stored in the light distribution memory | storage part 24 to default (step S1). Thereafter, the driving of the LED light sources 101 to 104 by the light source driving circuit 22, the imaging of the subject 3 by the image sensor 32, the decoding of the QR code by the decoder 33, etc. are repeated (steps S2, S3, etc.).

  On the other hand, if the decoder 33 has detected all three cut-out symbols (“detection number 3” in step S5), the QR code can be recognized with the current light amounts of the LED light sources 101 to 104. It is assumed that the entire QR code cannot be recognized because a part of the code is hidden by an operator's finger or extremely distorted. In such a case, there is little need to adjust the light quantity of each LED light source 101-104. Therefore, the control unit 21 does not change the energization time of the LED light sources 101 to 104 stored in the light distribution storage unit 24. Thereafter, the imaging of the subject by the image sensor 32 and the decoding of the QR code by the decoder 33 are repeated (steps S2, S3, etc.).

  On the other hand, if the decoder 33 detects one or two cutout symbols (“detection number 1 or 2” in step S5), the reason is that the subject is deceived while being tilted with respect to the glass member 11 or the like. Therefore, it is assumed that a part of the QR code is not sufficiently illuminated. In such a case, it is necessary to adjust the light quantity of each LED light source 101-104. Therefore, the control unit 21 outputs the image data D to the gradation measuring unit 23, and the average gradation G1 of the area 101a, the average gradation G2 of the area 102a, the average gradation G3 of the area 103a in the image data D, and The average gradation G4 of the area 104a is measured (step S6).

  Thereafter, the control unit 21 corrects the energization time to each of the LED light sources 101 to 104 based on the average gradations G1 to G4 measured by the gradation measuring unit 23 (step S7). The energization times of the LED light sources 101 to 104 corrected by the control unit 21 are stored in the light distribution storage unit 24. Thus, after a new energization time is set in the light distribution storage unit 24, the light source drive circuit 22 drives the LED light sources 101 to 104 with the energization time after the change. QR code decoding and the like are repeated (steps S2, S3, etc.).

Next, the procedure for correcting the light amount of each LED light source 101 to 104 in the process of step S7 will be described with reference to FIG.
A ROM or the like constituting the control unit 21 stores a proportional function F for calculating the energization time based on the difference amounts of the respective average gradations G1 to G4. This function is a linear function in which the energization time decreases as the gradation difference amount increases, for example, within the range of the maximum value Gmax to the minimum value Gmin of the difference amount.

  In determining the light intensity level of each of the LED light sources 101 to 104, first, one of the average gradations G1 to G4 that is closest to the intermediate value of the gradation range that can be normally decoded by the decoder 33 is selected as a reference value. Then, a difference amount between the selected reference value and another average gradation is calculated. Then, the energization time corresponding to each calculated difference amount is calculated based on the function F. The energization time calculated in this way is determined as the energization time of the LED light source that illuminates one area that is not the reference value among the average gradations used for calculating the difference amounts. Since there is little need to change the light amount of the area with respect to the average gradation selected as the reference value, the energization time of the LED light source that illuminates the area is determined as the energization time currently stored in the light distribution storage unit 24. . The energization times of the LED light sources 101 to 104 stored in the light distribution storage unit 24 are corrected based on the energization times of the LED light sources 101 to 104 thus determined. At this time, the difference amount between the average gradation selected as the reference value and the other average gradation is reduced.

  Usually, the light quantity of the light source is insufficient in the area where the average gradation is low, and the light quantity of the light source is excessive in the area where the average gradation is high. If the light quantity of each of the LED light sources 101 to 104 is determined so that the difference amount of the average gradation becomes small as described above, a long energization time is set for an area whose gradation is lower than the average gradation as the reference value. In addition, since a short energization time is set for an area whose gradation is higher than the average gradation as the reference value, the shortage or excess of the light amount is resolved.

Control examples of the respective LED light sources 101 to 104 when the energization time is corrected by the method as described above are shown in FIG. 8, FIG. 9 and FIG.
In the example of FIG. 8, the read surface of the subject is inclined with the areas 101 a and 102 a side close to the glass member 11 and the areas 103 a and 104 a side being separated from the glass member 11. As a result, the amount of light that illuminates the areas 101a and 102a is moderate, but the amount of light that illuminates the areas 103a and 104a is insufficient. In this state, as a result of correcting the energization time by the procedure as described above, the energization time of the LED light sources 101 and 102 that illuminate the areas 101a and 102a is corrected to the default t ms, and the LED light source 103 that illuminates the areas 103a and 104a. , 104 is corrected to t1 ms (t1> t), which is longer than the default.

  In this case, the light source driving circuit 22 starts energizing each of the LED light sources 101 to 104 during imaging of the subject, and then continues energizing the LED light sources 101 and 102 until the time t ms elapses. For, energization is continued until time t1 ms elapses. Thus, by increasing the energization time to the LED light sources 103 and 104, the areas 103a and 104a can be illuminated more brightly.

  In the example of FIG. 9, the surface to be read of the subject is inclined with the area 103 a side closest to the glass member 11 and the area 102 a side being the farthest away from the glass member 11. As a result, the amount of light that illuminates the area 103a is moderate, but the amount of light that illuminates the areas 101a and 104a is slightly insufficient, and the amount of light that illuminates the area 102a is insufficient to exceed the amount of light that illuminates the areas 101a and 104a. Yes. In this state, as a result of correcting the light amount level by the procedure as described above, the energization time of the LED light source 103 that illuminates the area 103a is corrected to the default t ms, and the energization of the LED light sources 101 and 104 that illuminate the areas 101a and 104a. It is assumed that the time is corrected to t2 ms (t2> t) longer than the default, and the energization time of the LED light source 102 that illuminates the area 102a is corrected to t3 ms (t3> t2) longer than t2 ms.

  In this case, the light source driving circuit 22 starts energizing the LED light sources 101 to 104 during imaging of the subject, and then continues energizing the LED light sources 101 and 104 until time t2 ms elapses. The energization is continued until time t3 ms elapses, and the LED light source 103 is energized until time t ms elapses. Thus, by increasing the energization time to the LED light sources 101, 102, 104, the areas 101a, 102a, 104a can be illuminated more brightly.

  In the example of FIG. 10, the read surface of the subject is inclined with the areas 101 a and 102 a side close to the glass member 11 and the areas 103 a and 104 a side being separated from the glass member 11. And the area 103a vicinity is excessively illuminated under the influence of external light. As a result, the amount of light that illuminates the area 102a is moderate, but the amount of light that illuminates the areas 101a and 104a is slightly excessive, and the amount of light that illuminates the area 103a is more than the amount of light that illuminates the areas 101a and 104a. In this state, as a result of correcting the energization time by the procedure as described above, the energization time of the LED light source 102 that illuminates the area 102a is corrected to the default tms, and the energization of the LED light sources 101 and 104 that illuminate the areas 101a and 104a. It is assumed that the time is corrected to t4 ms (t4 <t) shorter than the default, and the energization time of the LED light source 103 that illuminates the area 103a is corrected to t5 ms (t5 <t4), which is shorter than the energization time t4 ms.

  In this case, the light source driving circuit 22 starts energizing each of the LED light sources 101 to 104 during imaging of the subject, and then continues energizing the LED light source 102 until time t ms elapses, and the LED light sources 101 and 104 are energized. The energization is continued until time t4 ms elapses, and the LED light source 103 is energized until time t5 ms elapses. Thus, by shortening the energization time to the LED light sources 101, 103, 104, the areas 101a, 103a, 104a can be illuminated more darkly.

  As described above, the symbol recognition device 1 according to the present embodiment illuminates a subject by dividing the subject into a plurality of areas. When the decoder 33 cannot decode the QR code, the light distribution amount (energization time) of each area is adjusted based on the average gradation of each area in the image data D. In this way, the subject can be illuminated with the optimum amount of light, and the QR code can be recognized efficiently.

  Moreover, the symbol recognition apparatus 1 according to the present embodiment determines whether or not to change the energization time of each of the LED light sources 101 to 104 using the number of detections by the decoder 33 of the cut-out symbol included in the QR code. By controlling in this way, it is possible to determine the optimal light distribution based on the characteristics of the QR code.

  Note that the present invention is not limited to the contents disclosed in the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage.

  For example, in the above embodiment, the case where the present invention is applied to a symbol recognition apparatus specialized for QR code recognition has been described. However, the present invention may be applied to a symbol recognition apparatus that recognizes other types of two-dimensional symbols such as a data matrix, PDF 417, and maxi code. In that case, what is necessary is just to change the process of step S5 etc. according to the characteristic of each two-dimensional symbol.

  Moreover, in the said embodiment, the case where the four light sources 101-104 illuminate the four areas set to the vertical and horizontal two dimensions was demonstrated. However, a subject may be illuminated using a smaller or larger number of LED light sources, and the energization time of each LED light source may be controlled. Moreover, you may control the light distribution amount of each area by employ | adopting light sources other than LED and adjusting the voltage etc. which are supplied to a light source instead of energization time.

  Moreover, in the said embodiment, the light distribution amount (energization time) of each LED light source 101-104 was demonstrated using the difference amount of the average gradation G1-G4 of each area 101a-104a, and the function F. However, instead of the function F, by using a table in which the energization time to the LED light source is associated with each difference amount of the average gradation, the LED light sources 101 to 104 that are proportional to the difference amount of the average gradations G1 to G4 are used. The energization time may be calculated.

  In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, you may delete some components from all the components shown by the said embodiment. Furthermore, a well-known technique and a common technique may be combined with all the constituent elements shown in the above-described embodiment without departing from the gist.

  DESCRIPTION OF SYMBOLS 1 ... Symbol recognition apparatus, 2 ... Information processing terminal, 3 ... Subject, 4 ... QR code, 10 ... Case, 11 ... Glass member, 20 ... Main control board, 21 ... Control part, 22 ... Light source drive circuit, 23 ... Floor Adjustment measuring unit, 24 ... Light distribution storage unit, 30 ... Light source, 31 ... Lens, 32 ... Image sensor, 33 ... Decoder, 101-104 ... LED light source

The first aspect of the present invention includes an imaging unit that captures a plurality of light sources for illumination by region dividing a two-dimensional symbols included in the subject in a plurality of regions, the object illuminated by said light source, said imaging unit A decoding unit that decodes a two-dimensional symbol included in the captured image data, a light distribution storage unit that stores an energization time of the light source, and the decoding unit that is divided into the plurality of regions when decoding by the decoding unit fails Among the two-dimensional symbols, the number of symbols successfully detected in the decoding process is determined, and the light source is energized for re-decoding of the two-dimensional symbol that has failed to be decoded based on the determined number of symbols. determination means for determining whether it is necessary to time the correction, when the correction of the energizing time is determined to be necessary in the determination unit, the imaging unit is shooting From image data, a gradation measurement means for measuring the gradation information of each of the plurality of areas illuminated by the light source, based on the gradation information of each of the plurality of areas measured by the gradation measurement means is a symbol recognition device and a correction means for correcting the current time stored in the light distribution storage unit.

In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, you may delete some components from all the components shown by the said embodiment. Furthermore, a well-known technique and a common technique may be combined with all the constituent elements shown in the above-described embodiment without departing from the gist.
The invention described in the scope of claims at the beginning of the filing of the present application is appended below.
[1] Illuminating means for partially illuminating the subject into a plurality of regions, imaging means for imaging the subject illuminated by the illuminating means and generating image data, and an image generated by the imaging means Decoding means for decoding a two-dimensional symbol included in the data, and gradation for each of the plurality of areas illuminated by the illumination means from the image data generated by the imaging means when decoding by the decoding means fails Based on gradation information for measuring information and gradation information for each of the plurality of areas measured by the gradation measuring means, the illumination means corrects the light distribution that illuminates each of the plurality of areas. A correction unit; an illumination driving unit configured to drive the illumination unit according to the light distribution corrected by the correction unit and illuminate each of the plurality of regions; Symbol recognition apparatus, characterized in that it comprises.
[2] The correction unit according to [1], wherein the correction unit corrects a light distribution amount that illuminates each of the plurality of regions so that a difference amount of an average gradation for each of the plurality of regions is small. Symbol recognition device.
[3] The above-mentioned [1], wherein the illuminating means is composed of a plurality of light sources that illuminate a subject by dividing the subject into a plurality of vertical and horizontal two-dimensional areas. Symbol recognition device.
[4] The correction unit corrects the light distribution by changing energization time to the plurality of light sources, and the illumination driving unit energizes the plurality of light sources according to the energization time corrected by the correction unit. The symbol recognizing device according to [3] above, wherein:
[5] The symbol recognition apparatus according to [1], wherein the two-dimensional symbol is a QR code.
[6] An illumination unit that illuminates a subject by dividing the subject into a plurality of areas, an imaging unit that captures the subject illuminated by the illumination unit and generates image data, and an image generated by the imaging unit A control program for a symbol recognition device comprising a decoding unit that decodes a two-dimensional symbol included in data, and when the decoding by the decoding unit fails, from the image data generated by the imaging unit, the illumination unit A gradation measurement function for measuring gradation information for each of the plurality of areas illuminated by the plurality of areas, and the illumination unit includes the plurality of illumination units based on the gradation information for each of the plurality of areas measured by the gradation measurement function A correction function for correcting the light distribution for illuminating each of the regions, and the illumination unit is driven according to the light distribution corrected by the correction function, and each of the plurality of regions A control program for realizing the illumination driving function of illuminated, the.

Claims (6)

Illumination means for partially illuminating the subject into a plurality of areas;
Imaging means for imaging the subject illuminated by the illumination means and generating image data;
Decoding means for decoding a two-dimensional symbol included in the image data generated by the imaging means;
A gradation measuring means for measuring gradation information for each of the plurality of regions illuminated by the illumination means from the image data generated by the imaging means when decoding by the decoding means fails;
Based on the gradation information for each of the plurality of areas measured by the gradation measuring means, the correction means for correcting the light distribution that illuminates each of the plurality of areas;
Driving the illumination unit according to the light distribution corrected by the correction unit, and illuminating each of the plurality of regions;
A symbol recognition apparatus comprising:   The symbol recognition apparatus according to claim 1, wherein the correction unit corrects a light distribution amount that illuminates each of the plurality of regions so that a difference amount of an average gradation for each of the plurality of regions is small. .   2. The symbol recognition apparatus according to claim 1, wherein the illuminating unit includes a plurality of light sources that partially illuminate the subject by dividing the subject into a plurality of vertical and horizontal two-dimensional areas. The correction means corrects the light distribution by changing energization time to the plurality of light sources,
4. The symbol recognition apparatus according to claim 3, wherein the illumination driving unit energizes the plurality of light sources according to the energization time corrected by the correction unit.   The symbol recognition apparatus according to claim 1, wherein the two-dimensional symbol is a QR code. Included in the illumination unit that divides the subject into a plurality of regions and partially illuminates, the imaging unit that images the subject illuminated by the illumination unit and generates image data, and the image data generated by the imaging unit A control program for a symbol recognition device comprising a decoding unit for decoding a two-dimensional symbol,
A gradation measuring function for measuring gradation information for each of the plurality of regions illuminated by the illumination unit from image data generated by the imaging unit when decoding by the decoding unit fails;
Based on the gradation information for each of the plurality of areas measured by the gradation measurement function, a correction function for correcting the light distribution by which the illumination unit illuminates each of the plurality of areas;
Driving the illumination unit according to the light distribution corrected by the correction function, and illuminating each of the plurality of regions; and
Control program to realize.

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