JP2012074025A - Imaging device, reading device, and light quantity adjustment method - Google Patents

Abstract

Code information can be stably read from a code symbol.
According to one embodiment, a code reading apparatus includes an imaging device, a light source, a detection unit, and an adjustment unit. The imaging element captures an image. The light source irradiates light to an image capturing region of an image by the image sensor. The detection means detects a predetermined area from an image captured by the image sensor. The adjustment unit adjusts the amount of light emitted from the light source to the imaging region when a predetermined region is detected by the detection unit.
[Selection] Figure 1

Description

  Embodiments described herein relate generally to an imaging device, a reading device, and a light amount adjustment method.

  There is a code reading device that optically captures an image of a code symbol such as a barcode attached to a product, and acquires code information (product code, etc.) by decoding the code symbol included in the captured image (Patent Document) 1). Specifically, such a code reading device captures an image of a barcode attached to a product with an imaging device such as a CCD (Charge Coupled Device) sensor, decodes the output of the imaging device, and decodes the barcode code. Information is being acquired.

  In this type of code reader, it is necessary to illuminate the image pickup area of the image sensor (the read area for reading code information from a code symbol such as a barcode) with an illumination device in order to capture a clear image with the image sensor. For this reason, in the code reading device, a light source such as an LED (Light Emitting Diode) used as an illumination device is disposed so as to surround the imaging device so as to illuminate the imaging region of the imaging device.

  However, in the conventional code reader, the light from the light source is a code such as a barcode depending on the material of the product with a code symbol such as a barcode or the angle of the product when it is held over the imaging area of the image sensor. There is a problem in that an image captured by the imaging device after being specularly reflected by the symbol is lost, and code information cannot be read from a code symbol such as a barcode included in the image captured by the imaging device.

  The code reading apparatus according to the embodiment includes an image sensor, a light source, a detection unit, and an adjustment unit. The imaging element captures an image. The light source irradiates light to an image capturing region of an image by the image sensor. The detection means detects a predetermined area from an image captured by the image sensor. The adjustment unit adjusts the amount of light emitted from the light source to the imaging region when the predetermined region is detected by the detection unit.

FIG. 1 is a perspective view of the overall configuration of a POS system using a code reading device. FIG. 2 is a diagram illustrating a schematic configuration of an imaging device provided in the code reading device. FIG. 3 is a block diagram illustrating a configuration of the imaging device included in the code reading device. FIG. 4 is a diagram for explaining an operation of reading code information from image data. FIG. 5 is a block diagram illustrating a functional configuration of the control unit. FIG. 6 is a flowchart showing a flow of processing for adjusting the amount of light irradiated to the imaging region of the imaging device. FIG. 7 is a block diagram illustrating a functional configuration of the control unit. FIG. 8 shows the arrangement of pixels in the arrangement direction of the bars constituting the barcode (shown by the chain line in FIG. 4), the brightness level of each pixel when image data is lost due to specular reflection light, It is a figure which shows the relationship. FIG. 9 is a flowchart showing a flow of processing for adjusting the amount of light irradiated to the imaging region of the imaging device.

(First embodiment)
Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the overall configuration of a POS system using a code reading device. FIG. 2 is a diagram illustrating a schematic configuration of an imaging device provided in the code reading device. A code reading device 11 serving as a scanner is erected at the center on the soccer base 10. Further, a POS terminal 12 including an electronic cash register constituting a POS (Point Of Sales) system is installed inside the soccer stand 10. The code reader 11 and the POS terminal 12 are connected to each other via a transmission path (not shown) so that they can communicate with each other. The code reading device 11 and the POS terminal 12 constitute a POS terminal unit.

  The POS terminal 12 is provided with a keyboard 13, a cashier display 14, a shopper display 15, a printer 16 that performs receipt printing and the like. The keyboard 13 is provided with a fastening key or the like necessary for settlement of the commodity price. Such a POS terminal 12 is typically used in this type of checkout lane system.

  The code reader 11 is for reading various information from the captured image. For example, the code reading device 11 reads code information specifying a product such as a product code from a code symbol such as a barcode BC or a QR code (registered trademark) attached to the product. Further, the code reading device 11 reads service specifying information for specifying a service such as a discount to be given for purchase of a product from a service label such as a discount label attached to the product.

  In the present embodiment, the code reader 11 includes an imaging device 17 that captures an image including a code symbol such as a barcode BC or QR code (registered trademark) and a service label such as a discount label, and a barcode BC or QR code. A keyboard 18 provided with various keys and the like for inputting various information such as code information of a product without a code symbol such as (registered trademark) or service identification information of a product without a service label; And a display 19 for displaying various information such as product information such as product names and prices of registered products and service information such as discounts given to purchases of registered products for shoppers. Is provided.

  Among these, as shown in FIG. 2, the imaging device 17 includes an imaging element 201, a plurality of light sources 202 and 203, a lens 204, and the like. The image sensor 201 captures an image, such as a CCD (Charge Coupled Device) image sensor. Then, the image sensor 201 outputs image data of the captured image to the control unit 30.

  The light sources 202 and 203 irradiate light to the imaging region RA of the imaging device 201 such as a white LED (Light Emitting Diode). In the present embodiment, the imaging device 17 uses the two light sources 202 and 203, but two or more light sources such as LEDs may be arranged so as to surround the lens 204.

  The lens 204 captures light reflected by a subject such as a code symbol such as a barcode BC or QR code (registered trademark) located in the imaging region RA of the image sensor 201, and makes the captured light incident on the image sensor 201. An imaging optical system that forms an image of a subject on the imaging element 201. In other words, in the present embodiment, the image sensor 201 images a subject through the lens 204 and outputs the image data.

  For example, a shopping basket 22 containing a plurality of products 21 to be purchased by a shopper is placed upstream of the code reader 11 on the soccer table 10. Further, on the downstream side of the code reading device 11 on the soccer table 10, the code information is read by the code reading device 11, and another shopping basket 23 for putting the commodity 21 registered in accordance with the read code information. It has been placed.

  A POS server 25 as a POS processing device is connected to the POS terminal 12 via, for example, a LAN (Local Area Network) 24 in the store. The POS server 25 exchanges information regarding the settlement process of the product 21 with the POS terminal 12 and records the settlement process result of the product 21. This POS server 25 is, for example, data (product information) indicating the product 21 such as product codes, prices, product names, product images, etc. of all products 21 sold in the store, and further discounts given to the purchase of the product 21 And a product database that stores data (service information) indicating services such as these in advance. The POS server 25 refers to the product database for a data code (for example, code information read by the code reading device 11) transmitted from the POS terminal 12 via the LAN 24, and stores the product 21 corresponding to the data code. Data such as prices and product names (product information) is read out, the prices of all the products 21 are summed up to obtain the settlement amount data, and this settlement amount data is returned to the POS terminal 12 via the LAN 24. Further, the POS server 25 refers to the product database for a data code (for example, service identification information read by the code reader 11) transmitted from the POS terminal 12 via the LAN 24, and a product corresponding to the data code. The discounted value (service information) 21 is read out, and processing that takes this discounted value into account is performed to calculate the settlement amount data, and this settlement amount data is returned to the POS terminal 12 via the LAN 24. In the present embodiment, the case has been described where the POS server 25 has the product database, but the present invention is not limited to this. For example, the POS terminal 12 or the code reading device 11 may hold a product database and configure data processing.

  FIG. 3 is a block diagram illustrating a configuration of the imaging device included in the code reading device. The control unit 30 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 30 controls the operation of the imaging device 17 by the CPU executing a program stored in the ROM. The control unit 30 is connected to an image sensor 201, a light source driving circuit 31 that emits light from the light sources 202 and 203, a decoder 32, and an interface 33.

  The light source driving circuit 31 is controlled by the control unit 30 to irradiate light from the light sources 202 and 203 to the imaging region RA of the imaging element 201. The interface 33 is connected to the POS server 25 via the LAN 24.

  The decoder 32 is an image of an image picked up by the image pickup element 201 into which reflected light from the product 21 with a service symbol such as a barcode symbol or a barcode label such as a barcode BC or QR code (registered trademark) is applied. It is a reading unit that receives data and reads information from the input image data. In the present embodiment, the decoder 32 decodes code information and service specifying information from code symbols such as barcode BC and QR code included in the input image data, and service labels such as discount labels. Read information such as information and service specific information. Then, the decoder 32 transmits the read information to the POS terminal 12 via the interface 33.

  Here, the operation of reading the code information from the image data will be described with reference to FIG. FIG. 4 is a diagram for explaining an operation of reading code information from image data. The decoder 32 scans the bar code BC included in the image data 500 input from the image sensor 201 in the vertical direction with respect to the bar 502 constituting the bar code BC (indicated by a chain line), and thereby arranges the bar 502. Get the data. The decoder 32 repeats scanning of the barcode BC at a different position a predetermined number of times, and acquires array data of a predetermined number of bars 502. Next, the decoder 32 reads code information from the obtained array data of each bar 502.

  In the present embodiment, the decoder 32 reads code information from code symbols included in the input image data, but the present invention is not limited to this. For example, the decoder 32 refers to a product image stored in the product database stored in the POS server 25 and reads a specific state by reading a surface state such as a hue or a surface roughness as a feature amount from the input image data. Recognize goods as objects. The decoder 32 can also read the code information of the product by reading the product code of the recognized product from the product database. Note that the decoder 32 does not consider the outline or size of the product in order to shorten the processing time.

  Next, an operation for reading service specifying information from image data will be described. The decoder 32 is a character string detected from a predetermined area in the image data by pattern recognition or OCR character recognition, mark features such as pictures and symbols, and a label feature file (stored in the ROM of the control unit 30 in advance). It is determined that a service label has been detected in the area when the matching degree is equal to or greater than a predetermined value. Then, when the decoder 32 detects the service label, the decoder 32 reads the service specifying information associated with the label feature data of the service label from the label feature file. It is assumed that an arbitrary value such as 90% can be set as the threshold value for determining the degree of coincidence.

  Returning to FIG. 3, the decoder 32 also functions as a detection unit that detects an information reading error from the information reading result. In other words, the decoder 32 detects the specular reflection light from the image data of the image captured by the image sensor 201.

  In the present embodiment, the decoder 32 reads a code information read result (or service label) from a code symbol such as a barcode BC or QR code (registered trademark) included in the image data 500 of an image captured by the image sensor 201. The reading error of the code information and the service specific information is detected from the read result of the service specific information from). Then, the decoder 32 notifies the control unit 30 that an error in reading the code information or service specific information has been detected.

  Here, a method for detecting a reading error according to the reading result of the code information from the barcode BC will be described with reference to FIG. When the specular reflection light is generated, the image data 500 output from the image sensor 201 has an image loss (for example, whiteout) 501 as shown in FIG. Therefore, the decoder 32 determines that a code information reading error has occurred when the code information read from the array data of each bar 502 does not match by the above-described processing.

  Specifically, as described above, the decoder 32 scans each bar 502 constituting the barcode BC included in the image data 500 output from the image sensor 201 in the vertical direction a predetermined number of times at different positions. The array data of a predetermined number of bars 502 is acquired repeatedly. Next, the decoder 32 reads the code information from the acquired array data of each bar 502. Then, the decoder 32 determines whether or not the read predetermined number of pieces of code information match. Note that the predetermined number of times can be arbitrarily set by the user from the keyboard 18 or the like provided in the code reading device 11. The decoder 32 determines that a code information reading error has occurred if the code information read by repeating scanning of the barcode BC a predetermined number of times at different positions does not match.

  When the code information is read using the general object recognition described above, the decoder 32 determines that an error has occurred in reading the code information when a plurality of products are recognized from the input image data. It shall be.

  Next, a method for detecting a reading error according to the reading result of the service specific information from the service label will be described. The decoder 32 is a character string detected from a predetermined area in the image data by pattern recognition or OCR character recognition, mark features such as pictures and symbols, and a label feature file (stored in the ROM of the control unit 30 in advance). It is determined that an error has occurred in reading the service specific information when the matching degree is lower than a predetermined value.

  FIG. 5 is a block diagram illustrating a functional configuration of the control unit. The control unit 30 has a function as the adjustment unit 401 or the like when the CPU sequentially executes programs stored in the ROM.

  The adjustment unit 401 controls the light source drive circuit 31 to detect at least one of the light sources 202 and 203 when an information reading error is detected by the decoder 32 (that is, when specular reflection light is detected). Is adjusted to adjust the amount of light emitted to the imaging region RA of the image sensor 201. In the present embodiment, the adjustment unit 401 controls the light source drive circuit 31 to reduce the amount of light emitted from at least one of the light sources 202 and 203 when the specular reflection light is detected by the decoder 32. Shall. As a result, the amount of reflected light that is reflected from the code symbol, service label, etc. and incident on the image sensor 201 can be suppressed, and image loss 501 due to specular reflected light can be reduced, and thus specular reflected light is generated. However, it is possible to stably read information such as code information and service specific information from the code symbol and service label. Note that the adjustment unit 401 may stop the irradiation of light from the light source 202 or the light source 203 by controlling the light source driving circuit 31 when the specular reflection light is detected by the decoder 32. If the irradiation from both light sources 202 and 203 is stopped, an image cannot be picked up by the image sensor 201. Therefore, even if the adjustment unit 401 stops light emission from one light source, the other light source emits light. Irradiation shall continue.

  In the present embodiment, the adjustment unit 401 adjusts the amount of light emitted from the light sources 202 and 203 to adjust the amount of light emitted to the imaging region RA of the imaging element 201. It is not limited to. For example, when the imaging device 17 has a mechanical mechanism such as a diaphragm for adjusting the light irradiated to the imaging region RA, the adjustment unit 401 uses a mechanical mechanism such as a diaphragm. The amount of light applied to the imaging area RA of the imaging element 201 may be adjusted.

  Next, the flow of processing for adjusting the amount of light applied to the imaging region RA of the imaging element 201 will be described with reference to FIG. FIG. 6 is a flowchart showing a flow of processing for adjusting the amount of light irradiated to the imaging region of the imaging device.

  When image data is input from the image sensor 21, the decoder 32 scans a predetermined number of times at different positions in the vertical direction with respect to the bar 502 constituting the barcode BC included in the input image data (image) ( In step S601), array data of a predetermined number of bars 502 is acquired (step S602).

  Next, the decoder 32 reads code information from each of the obtained array data of the predetermined number of bars 502 (step S603).

  Then, the decoder 32 determines whether or not an error has occurred in reading the code information based on whether or not the code information read from the array data of the predetermined number of bars 502 matches (step S604). If the code information read from the array data of each bar 502 matches, it is determined that no error has occurred in reading the code information (step S604: No), and the code reader 11 irradiates the imaging area RA. The read code information is transmitted to the POS terminal 12 via the interface 33 without adjusting the amount of light to be transmitted (step S605).

  On the other hand, if the code information read from the array data of each bar 502 does not match, it is determined that an error has occurred in reading the code information (step S604: Yes), and the decoder 32 has an information reading error. The adjustment unit 401 is notified of the detection. The adjustment unit 401 controls the light source driving circuit 31 to adjust the amount of light emitted from at least one of the light sources 202 and 203 to thereby irradiate the imaging region RA of the imaging element 201. Is adjusted (step S606). In addition, the code reading device 11 outputs a display and voice guidance for instructing the user to re-read the barcode BC.

  As described above, according to the code reading apparatus 11 according to the first embodiment, the image sensor 201 that captures an image, the light sources 202 and 203 that irradiate the image capturing area RA of the image by the image sensor 201, and the image sensor 201. The information is read from the image picked up by the decoder 32, and the amount of light emitted to the image pickup area RA when the information reading error is detected from the decoder 32 for detecting the information reading error from the information reading result. By adjusting the adjustment unit 401 for adjustment, the amount of reflected light that is reflected from the code symbol, the service label, and the like and is incident on the image sensor 201 can be suppressed, and image loss 501 due to specular reflection light can be reduced. Therefore, the reading accuracy of information can be improved.

(Second Embodiment)
In the present embodiment, a predetermined area where an information reading error occurs is detected from an image captured by the image sensor, and the amount of light emitted to the imaging area of the image sensor when the predetermined area is detected Is to adjust. In the following description, description of the same configuration as that of the first embodiment will be omitted, and a configuration different from that of the first embodiment will be described.

  FIG. 7 is a block diagram illustrating a functional configuration of the control unit. The control unit 30 according to the present embodiment includes functions as an acquisition unit 701, a detection unit 702, an adjustment unit 703, and the like by causing the CPU to sequentially execute programs stored in the ROM. In the first embodiment, the decoder 32 has a function as a detection unit that detects an error in reading information. However, in the present embodiment, the decoder 32 uses image data input from the image sensor 201. It is assumed that only a function as a reading unit for reading information is provided.

  The capturing unit 701 captures image data of an image captured by the image sensor 201 when an image is captured by the image sensor 201.

  The detection unit 702 detects a predetermined area from the captured image data. Here, the predetermined area is an area where an error in reading information from the image data occurs due to generation of specular reflection light or the like. More specifically, the predetermined area is an area that is greater than or equal to a preset brightness in the captured image data, or a white area that is greater than or equal to a preset size in the captured image data.

  Here, a process for detecting a predetermined area from the captured image data will be described with reference to FIG. FIG. 8 shows the arrangement of pixels in the arrangement direction of the bars constituting the barcode (shown by the chain line in FIG. 4), the brightness level of each pixel when image data is lost due to specular reflection light, It is a figure which shows the relationship. When the missing 501 occurs in the image data 500 due to the specular reflection light, the brightness level of the pixel corresponding to the location where the missing 501 occurs sharply rises. Therefore, the detection unit 702 determines that specular reflection light has been generated in the pixel corresponding to the location where the brightness level shows a sharp rise, and detects the pixel as a predetermined region. More specifically, the detection unit 702 has a brightness level higher than the brightness level (for example, 100) of surrounding pixels in which the missing 501 is not generated and a preset brightness level (for example, 200). ) The above pixels are detected as a predetermined area.

  Further, the detection unit 702 has a predetermined number (for example, two or more) of white pixels in the arrangement of pixels in the arrangement direction of the bars 502 constituting the barcode BC (that is, preset in image data). A white area larger than the size) may be detected as a predetermined area. Alternatively, the detection unit 702 may detect a place where a predetermined number of black pixels are continuous as a predetermined area instead of the white pixel.

  The adjustment unit 703 controls the light source driving circuit 31 and adjusts the amount of light emitted from at least one of the light sources 202 and 203 when a predetermined region is detected by the detection unit 702. The amount of light applied to the imaging area RA of the imaging element 201 is adjusted. Note that a specific method for adjusting the amount of light applied to the imaging region RA of the imaging device 201 is the same as that in the first embodiment, and thus the description thereof is omitted here.

  Next, a flow of processing for adjusting the amount of light irradiated to the imaging region RA of the imaging element 201 will be described with reference to FIG. FIG. 9 is a flowchart showing a flow of processing for adjusting the amount of light irradiated to the imaging region of the imaging device.

  The capturing unit 701 waits for an image to be captured by the image sensor 201 (step S901: No). When an image is captured by the image sensor 201 (step S901: Yes), the capturing unit 701 captures image data of the image captured by the image sensor 201 (step S902).

  Next, the detection unit 702 detects, from the captured image data, a predetermined region where specular reflection light is generated and an information reading error occurs (step S903). When the predetermined area is not detected by the detection unit 702 (step S903: No), the control unit 30 ends the process of adjusting the amount of light irradiated to the imaging area RA. On the other hand, when a predetermined area is detected by the detection unit 702 (step S903: Yes), the adjustment unit 703 controls the light source driving circuit 31 to emit light from at least one of the light source 202 and the light source 203. The amount of light is reduced to adjust the amount of light emitted to the imaging area RA of the image sensor 201 (step S904).

  As described above, according to the code reading apparatus 11 according to the second embodiment, the image sensor 201 that captures an image, the light sources 202 and 203 that irradiate the image capturing area RA of the image by the image sensor 201, and the image sensor 201. When the detection unit 702 detects a predetermined region where an information reading error occurs due to the generation of specular reflection light, and the detection unit 702 detects the predetermined region, the light sources 202 and 203 An adjustment unit 703 that adjusts the amount of light emitted from at least one light source and adjusts the amount of light emitted to the imaging region RA of the image sensor 201, so that the code symbol, the service label, and the like can be used. The amount of reflected light that is reflected and incident on the image sensor 201 is suppressed, and image loss 501 due to specular reflected light can be reduced. It can be from an image containing Doshinboru and services such as labels to improve the reading accuracy of the information such as code information and service identification information.

  As described above, according to the first and second embodiments, information reading accuracy can be improved.

  Note that the program executed by the code reading device 11 and the POS terminal 12 of the present embodiment is provided by being incorporated in advance in a ROM or the like.

  The program executed by the code reading device 11 and the POS terminal 12 of the present embodiment is a file in an installable format or an executable format, and is a CD-ROM, flexible disk (FD), CD-R, DVD (Digital It may be configured to be recorded on a computer-readable recording medium such as Versatile Disk).

  Further, the program executed by the code reading device 11 and the POS terminal 12 according to the present embodiment may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. good. Further, the program executed by the code reading device 11 and the POS terminal 12 according to the present embodiment may be provided or distributed via a network such as the Internet.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11 Code reader 17 Imaging device 30 Control part 31 Light source drive circuit 32 Decoder 201 Image pick-up element 202,203 Light source 401,703 Adjustment part 702 Detection part BC Barcode RA Imaging area

JP 2009-129266 A

Claims (6)

An image sensor for capturing an image;
A light source that irradiates light to an imaging region of an image by the imaging element;
Detection means for detecting a predetermined area from an image captured by the image sensor;
An adjustment unit that adjusts the amount of light emitted from the light source to the imaging region when the predetermined region is detected by the detection unit;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the detection unit detects, as the predetermined area, an area having a predetermined brightness or more from an image captured by the imaging element.   The imaging device according to claim 1, wherein the detection unit detects, as the predetermined region, a white region having a predetermined size or more from an image captured by the image sensor. An image sensor for capturing an image;
A light source that irradiates light to an imaging region of an image by the imaging element;
Reading means for reading information from an image captured by the image sensor;
Detection means for detecting an error in reading the information from a result of reading the information by the reading means;
An adjusting means for adjusting the amount of light emitted from the light source to the imaging region when an error in reading the information is detected;
A reading apparatus comprising:   The detecting means acquires a plurality of bar array data in a direction perpendicular to a bar constituting a barcode included in an image captured by the image sensor, and reads information from the acquired array data of each bar. The reading apparatus according to claim 4, wherein an error in reading the information is detected when the read information does not match. A light amount adjustment method for an imaging apparatus, comprising: an imaging element that captures an image; and a light source that irradiates light to an imaging region that captures an image by the imaging element,
The imaging apparatus includes a control unit,
The controller is
A step of detecting a predetermined region in which an information reading error occurs from an image captured by the image sensor;
A step of adjusting an amount of light emitted from the light source to the imaging area when the predetermined area is detected;
A method for adjusting the amount of light.

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