JP5556684B2 - Information code reader - Google Patents

Description

  The present invention relates to an information code reading device that reads information from a two-dimensional information code, and more particularly to an information code reading device that reads information from a two-dimensional information code having a position detection pattern.

  As the two-dimensional information code, one having a position detection pattern that is a pattern used for detecting the position of the two-dimensional information code is known. For example, QR code (registered trademark) includes a cut-out symbol as a position detection pattern. When reading information from a two-dimensional information code having a position detection pattern, an image including the two-dimensional information code is captured in a state where light is irradiated on the two-dimensional information code, and the position detection pattern is searched from the captured image. Then, the entire position of the two-dimensional information code is determined based on the position of the position detection pattern. Therefore, if the position detection pattern is unclear due to a defect or the like and the position detection pattern cannot be detected, information cannot be read from the two-dimensional information code.

  Here, as a technique corresponding to a case where a part of the captured image is unclear, for example, the technique of Patent Document 1 is known. In the technique of Patent Document 1, in order to solve the problem that, when an image of a glossy surface is captured, the contrast of a part of the image may decrease due to reflection, a plurality of cameras are provided, and the same position from different angles is provided. The image of is taken. Then, the two images are synthesized. When images are taken from different angles, even if there is a position where the contrast is reduced due to reflection in a part of the image, there is a high possibility that the positions are different from each other. Therefore, by combining a plurality of images, it is possible to reduce the portion where the contrast is lowered.

  As an information code reading device, there is known a type of device that searches for a position detection pattern at the same time when an image including a two-dimensional information code is captured. Since this type of apparatus searches for a position detection pattern at the same time when an image is captured, information can be read at high speed.

Japanese Patent Laid-Open No. 2-98789

  By the way, the image capture is performed from a certain direction determined by the mounting position of the image capture means. For this reason, in the type of apparatus that searches for a position detection pattern at the same time when an image is captured, if the position detection pattern is missing in the capture direction of the image capture means, the position detection pattern can be recognized from another direction. Even in such a case, the position detection pattern could not be detected, and as a result, information could not be read from the two-dimensional information code.

  Here, even if a plurality of images are synthesized as in the technique of Patent Document 1, if the position detection pattern itself has a defect, the position detection pattern in the synthesized image also has a defect. In addition, since a plurality of images must be combined, the technique of Patent Document 1 cannot be applied to an information code reading device that searches for a position detection pattern at the same time when an image is captured.

  The present invention has been made based on this situation, and an object of the present invention is to provide an information code reader that reduces the inability to read information from a two-dimensional information code.

In order to achieve the object, the invention according to claim 1 is an image showing a captured image including a light source that emits light to the two-dimensional information code and an image including the two-dimensional information code irradiated with light from the light source Image capturing means for outputting a signal, storage means for storing an image signal output from the image capturing means, and a position detection pattern of a two-dimensional information code using the image signal when storing the image signal in the storage means Information that reads the information from the two-dimensional information code by determining the position of the two-dimensional information code based on the position detection pattern searched by the searching means from the image signal stored in the storage means An information code reading device comprising reading means,
As the image capturing means, a plurality of image capturing means having different image scanning directions are provided, and the search means can search the position detection pattern from the image signals output from the plurality of image capturing means. The information reading means determines the position of the two-dimensional information code using an image for which the position detection pattern has been searched, and reads information from the two-dimensional information code.

  According to the present invention, it is provided with a plurality of image capturing means whose image scanning directions are different from each other, and the search means can search the position detection pattern from the image signals output from the plurality of image capturing means. It can be done. For this reason, even if the position detection pattern cannot be detected by using a part of the position detection pattern, or if the position detection pattern cannot be detected by using an image signal output from one image capturing unit, the present invention is different in the scanning direction of the image. The position detection pattern can be searched using the image signal of the image capturing means. Therefore, since it is reduced that the position detection pattern cannot be detected, information that cannot be read from the two-dimensional information code is reduced.

  According to the second aspect of the present invention, the search means searches the position detection patterns from the image signals output from all the image capture means, and the information reading means can search the position detection patterns by the search means. Is used to determine the position of the two-dimensional information code based on the position detection pattern, and information is read from the two-dimensional information code.

  As described above, the position detection pattern may be searched using the image signals output from all the image capturing units, and the information may be read by using one image for which the position detection pattern has been searched. In contrast to this, as in claim 3, the search means searches for the position detection pattern by sequentially using the image signals output from the plurality of image capturing means in a predetermined order. If the position detection pattern cannot be searched, the position detection pattern may be searched using the image signal of the next image capturing means.

  In the invention according to claim 4, the information reading means uses an image for which the position detection pattern can be searched. However, when the information cannot be read from the two-dimensional information code of the image, the position detection pattern is searched. The information is read from the two-dimensional information code using another created image. In this way, the fact that information cannot be read from the two-dimensional information code is reduced.

  The invention according to claim 5 is provided with two image capturing means, and the two image capturing means are characterized in that the scanning directions of the images are different from each other by 90 degrees. In this way, when the number of image capturing means is two, the number of cases where information cannot be read from the information code is particularly reduced. Further, since there are only two image capturing means, the apparatus can be reduced in size.

  The invention described in claim 6 is characterized in that the information code reader is of a fixed type. In the case of the fixed type, unlike the portable type, the operator cannot change the reading direction by changing the posture of the apparatus. Significantly having a capturing means.

  As the image capturing means, for example, an area sensor can be used as in the seventh aspect.

It is a fragmentary longitudinal cross-section which shows the structure outline | summary of the housing etc. of an information code reader. It is an A arrow directional view of the optical system in the information code reading apparatus shown in FIG. It is a block diagram which shows the structure outline | summary of the circuit part of an information code reader. It is a figure which shows the overlap of the imaging area of two light reception sensors 23A and 23B. (A) is a figure which shows arrangement | positioning of the light-receiving surface 24A, 24B of two light-receiving sensor 23A, 23B, (B) is a figure which illustrates the image operation direction of light-receiving sensor 23A, 23B. It is a figure which shows the search direction of the cut-out symbol of QR Code. It is a flowchart which shows the principal part of the process which a microcomputer system performs.

  Hereinafter, an embodiment in which an information code reading device of the present invention is applied to a portable information code reading device for QR code will be described with reference to the drawings. First, an outline of the configuration of the information code reading device 10 according to the present embodiment will be described with reference to FIGS. FIG. 1 is a partial longitudinal sectional view showing an outline of the configuration of the housing and the like of the information code reader 10, and FIG. 2 is a view taken along the arrow A of the optical system in the information code reader shown in FIG. FIG. 3 is a block diagram showing an outline of the configuration of the circuit unit 20 of the information code reading device 10.

  As shown in FIG. 1, an information code reader 10 that reads a QR code Q includes a housing 11 that has a vertically long, substantially rectangular box shape. The housing 11 is a molded part made of a synthetic resin such as ABS resin, and has a reading port 11a on one end side thereof. The reading port 11a is an opening through which incident light incident on the two light receiving sensors 23A and 23B shown in FIG. 2 can be introduced. As shown in FIG. 1, a secondary battery 49 is accommodated on the other end side of the housing 11. An opening to which the liquid crystal display 46 can be attached is also formed on the surface side of the housing 11 so that the user of the information code reading device 10 can visually grasp the display contents displayed on the liquid crystal display 46. It is. A circuit unit 20 described later is accommodated in the housing 11. In FIG. 1, printed wiring boards 15 and 16 constituting the circuit unit 20 are illustrated.

  As shown in FIG. 3, the circuit unit 20 mainly includes an optical system such as a pair of red light emitting diodes 21 and a condensing lens 52, light receiving sensors 23A and 23B, imaging lenses 27A and 27B, and an FPGA (Field Programmable Gate). Array) 34, memory 35, control circuit 40, operation switches 12, 14, and liquid crystal display 46, etc., and a microcomputer system (hereinafter referred to as "microcomputer"). Mounted or housed inside the housing 11.

  An outline of the configuration of the microcomputer system will be described. The microcomputer system includes amplification circuits 31A and 31B, A / D conversion circuits 33A and 33B, FPGA 34, memory 35, address generation circuits 36A and 36B, synchronization signal generation circuits 38A and 38B, control circuit 40, operation switches 12 and 14, and LED 43. , A buzzer 44, a liquid crystal display 46, a communication interface 48, and the like. As the name suggests, this microcomputer system is composed mainly of a control circuit 40 and a memory 35 that can function as a microcomputer (information processing device). Image signals such as code images captured by the optical system described above are obtained. It can perform signal processing in terms of hardware and software. The control circuit 40 also performs control related to the entire system of the information code reader 10.

  Image signals (analog signals) output from the light receiving sensors 23A and 23B of the optical system are respectively input to the amplifier circuits 31A and 31B and amplified by a predetermined gain, and then input to the A / D conversion circuits 33A and 33B. Then, the analog signal is converted into a digital signal. The digitized image signal is input to the FPGAs 34A and 34B. The FPGAs 34A and 34B analyze the input image signal and search for a cutout symbol. Therefore, in the present embodiment, the cut-out symbol search is performed by hardware. When the position of the cutout symbol can be detected, the FPGAs 34 </ b> A and 34 </ b> B store the position of the cutout symbol in the memory 35. The FPGAs 34 </ b> A and 34 </ b> B also perform processing for storing the image signal in the memory 35. Note that the memory 35 functions as storage means in claims.

  The synchronization signal generation circuits 38A and 38B are configured to be able to generate synchronization signals for the light receiving sensors 23A and 23B and the address generation circuits 36A and 36B, and the address generation circuits 36A and 36B are output from the synchronization signal generation circuits 38A and 38B. Based on the supplied synchronization signal, a storage address of the image signal in the memory 35 is generated, and the storage address is output to the FPGAs 34A and 34B.

  The control circuit 40 is a microcomputer capable of controlling the entire information code reading device 10 and includes a CPU, a system bus, an input / output interface, and the like, and can constitute an information processing device together with the FPGA 34 and the memory 35 and has an information processing function. Have. The control circuit 40 is configured to be connectable to various input / output devices (peripheral devices) via a built-in input / output interface. In this embodiment, the power switch 41, the operation switches 12, 14, the LED 43, A buzzer 44, a liquid crystal display 46, a communication interface 48, and the like are connected.

  The red light emitting diode 21 constituting the optical system is a light irradiator capable of irradiating the illumination light Lf, and functions as a light source in the claims. The illumination light Lf from the red light emitting diode 21 is condensed by a condenser lens 52 that is a combination of a diffusion lens and a convex lens. In the present embodiment, the red light emitting diodes 21 are provided on both sides of the light receiving sensors 23A and 23B, and the illumination light Lf can be irradiated toward the reading object R through the reading port 11a of the housing 11. It is configured. A QR code Q that is a two-dimensional information code is affixed to the reading object R.

  The light receiving sensors 23A and 23B are configured to receive the reflected light Lr irradiated and reflected on the reading object R and the QR code Q through the imaging lenses 27A and 27B. It is comprised by the two-dimensional image sensor (namely, area sensor) which consists of solid-state image sensors, such as. The light receiving sensors 23A and 23B correspond to image capturing means in claims. Hereinafter, when the two light receiving sensors 23A and 23B are distinguished, they are referred to as a first light receiving sensor 23A and a second light receiving sensor 23B.

  The imaging lenses 27A and 27B function as an imaging optical system capable of condensing incident light incident from the outside through the reading port 11a and forming an image on the light receiving surfaces 24A and 24B of the light receiving sensors 23A and 23B. For example, it is composed of a lens barrel and a plurality of condensing lenses housed in the lens barrel.

  As shown in FIG. 2, in the two light receiving sensors 23A and 23B, the central axes XA and XB of the respective imaging areas are parallel to each other. The two light receiving sensors 23A and 23B are on the same virtual plane (a virtual plane upright from the drawing along the line segment VP) including the common line segment VP orthogonal to the two central axes XA and XB. It is arranged in. The two light receiving sensors 23A and 23B are mounted on the printed wiring board 15 so that the center axes XA and XB of the imaging area are separated by a distance d1. Further, the center axes XA and XB of the imaging areas of the two light receiving sensors 23A and 23B and the center axes Xa and Xb of the imaging lenses 27A and 27B are assembled in a shifted manner. By assembling in this way, the imaging areas of the two light receiving sensors 23A and 23B overlap each other at a constant distance D1, as shown in FIG.

  FIG. 5A is a diagram showing the arrangement of the light receiving surfaces 24A and 24B of the two light receiving sensors 23A and 23B. The two light receiving sensors 23A and 23B have the same configuration, and the light receiving surfaces 24A and 24B of each of the light receiving sensors 23A and 23B have a rectangular shape. However, the first light receiving sensor 23A and the second light receiving sensor 23B are different from each other in the directions of the light receiving surfaces 24A and 24B. Specifically, although the light receiving surface 24A of the first light receiving sensor 23A and the light receiving surface 24B of the second light receiving sensor 23B are both parallel to the virtual plane including the line segment VP, the longitudinal direction The sides are offset by 90 degrees from each other.

  These two light receiving sensors 23A and 23B are area sensors as described above, and output image signals one by one in order as in the known area sensors (in other words, pixels are scanned one by one in units of columns). To capture images). The direction in which the image signal is output (that is, the scanning direction of the image) is determined by the hardware configuration. In this embodiment, each of the light receiving sensors 23A and 23B is in a direction parallel to the longitudinal direction of the light receiving surfaces 24A and 24B. is there. FIG. 5B is a diagram illustrating the image scanning direction of the light receiving sensors 23A and 23B. As shown in FIG. 5B, the image scanning direction depends on the arrangement of the light receiving sensors 23A and 23B. The directions are shifted from each other by 90 degrees. Image signals output for each column from the light receiving sensors 23A and 23B are output to the amplifier circuits 31A and 31B one column at a time by the transfer means (horizontal transfer element or horizontal shift register) in the light receiving sensors 23A and 23B. The signals are sequentially input from the amplifier circuits 31A and 31B to the FPGAs 34A and 34B via the A / D conversion circuits 33A and 33B. Then, in the FPGAs 34A and 34B, as described above, retrieval of cutout symbols and storage of image signals in the memory 35 are performed.

  As is well known, the cut-out symbol in the QR code Q has a ratio of black cells to white cells of 1: 1: 3: 1: 1 from any of vertical, horizontal, and diagonal directions. Therefore, the retrieval of the cutout symbol is performed by searching for a portion where the ratio of black cells to white cells is 1: 1: 3: 1: 1.

  By the way, as shown in FIG. 6, it is conceivable that a part of the cutout symbol is missing. In this case, if the arrow direction in FIG. 6A is the cut-out symbol search direction, that is, the image scanning direction, the above-described 1: 1: 3: 1: 1 pattern does not exist. Therefore, when the arrow direction shown in FIG. 6A is the cut-out symbol search direction, the cut-out symbol cannot be detected. Therefore, if the search direction of the cutout symbol is only one direction and the search is performed from the direction of FIG. 6A, the cutout symbol cannot be detected, and as a result, the QR code Q cannot be read. End up.

  However, in this embodiment, since the image scanning directions of the light receiving sensors 23A and 23B are shifted from each other by 90 degrees, the cut-out symbols can be searched from two directions that are different from each other by 90 degrees. That is, when one search direction is the direction shown in FIG. 6A, the other search direction is the direction shown in FIG. If the arrow direction in FIG. 6B is the search direction of the cutout symbol, a 1: 1: 3: 1: 1 pattern exists, so that the cutout symbol can be detected. Therefore, as in this embodiment, by setting the search direction of the cutout symbol to two directions, the case where the cutout symbol cannot be detected is reduced.

  FIG. 7 is a flowchart showing a main part of processing performed by the microcomputer system (FPGA 34 and control circuit 40) in the present embodiment. The microcomputer system executes the processing shown in FIG. 7 following exposure. Note that the exposure is performed based on the trigger signal input by operating the operation switches 12 and 14, and the two light receiving sensors 23A and 23B are exposed simultaneously by the exposure. Further, among the steps shown in FIG. 7, the steps S <b> 1 and S <b> 5 are performed by the FPGA 34, and the other steps are performed by the control circuit 40.

  First, in step S1, an image signal is obtained from the first light receiving sensor 23A one column at a time and stored in the memory 35, and a cut-out symbol is searched using the image signal. In subsequent step S2, it is determined whether or not a cut-out symbol has been detected as a result of the search in step S1. If a cutout symbol can be detected, an affirmative determination is made in step S2 and the process proceeds to step S3. If a cutout symbol cannot be detected, a negative determination is made in step S2 and the process proceeds to step S5.

  In step S3, the image signal of the first light receiving sensor 23A is read from the memory 35, and the decoding range (range of QR code Q) is determined based on the position of the cutout symbol detected in step S2 in the image signal. The decoding is performed for the decoding range. In step S4, it is determined whether or not the decoding is successful. If the decoding is successful, it is determined that the decoding is successful, and the processing shown in FIG. Thereafter, a predetermined process is performed when decoding is successful. On the other hand, if the decoding fails, a negative determination is made in step S4 and the process proceeds to step S5.

  In step S5, an image signal is acquired from the second light receiving sensor 23B and a cut symbol is searched. This step S5 and the above-described step S1 are processes corresponding to the search means in the claims. In the subsequent step S6, it is determined whether or not a cut-out symbol has been detected as a result of the search in step S5. If a cut-out symbol can be detected, an affirmative decision is made in step S6 and the process proceeds to step S7. On the other hand, if a cut-out symbol cannot be detected from the image signal of the second light receiving sensor 23B, a negative determination is made in step S6 to determine decoding failure, and the processing shown in FIG. In the case of decoding failure, a predetermined process such as displaying a predetermined error message on the liquid crystal display 46 is performed.

  In step S7, the image signal of the second light receiving sensor 23B is read from the memory 35, and a decoding range is determined based on the position of the cut-out symbol detected in step S5 in the image signal. Perform decoding. This step S7 and the above-mentioned step S3 are processes corresponding to the information reading means in the claims.

  In a succeeding step S8, it is determined whether or not the decoding is successful. If the decoding is successful, it is determined that the decoding is successful, and the processing shown in FIG. On the other hand, if the decoding has failed, the processing shown in FIG.

  As described above, according to the present embodiment described above, the two light receiving sensors 23A and 23B whose image scanning directions are shifted from each other by 90 degrees are provided. From the image signals output from the two light receiving sensors 23A and 23B, respectively. The cut-out symbol can be searched. Therefore, even if a part of the cutout symbol is missing or the cutout symbol cannot be detected using the image signal output from one light receiving sensor 23, in this embodiment, the image of another light receiving sensor 23 is used. A cut-out symbol is searched using a signal. This reduces the inability to detect cutout symbols, thereby reducing the inability to read information from the QR code Q.

  Further, in the present embodiment, not only when the cutout symbol cannot be detected from the image signal of the first light receiving sensor 23A, but also the cutout symbol can be detected from the image signal of the first light receiving sensor 23A, and the image signal is used. However, even when decoding fails (No in step S4 in FIG. 7), the cut-out symbol is searched and decoded using the image signal of the second light receiving sensor 23B. Therefore, it is more difficult to read information from the QR code Q.

  In the present embodiment, the two light receiving sensors 23A and 23B are arranged so that the image scanning directions of the two light receiving sensors 23A and 23B are shifted from each other by 90 degrees. Therefore, when the number of light receiving sensors 23 is two, the number of cases where information cannot be read from the QR code Q is particularly reduced. Further, since only two light receiving sensors 23 are provided, the apparatus can be reduced in size.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following embodiment is also contained in the technical scope of this invention, and also the summary other than the following is also included. Various modifications can be made without departing from the scope.

  For example, in the above-described embodiment, first, a cutout symbol is searched using the image signal of the first light receiving sensor 23A (step S1 in FIG. 7), and when the cutout symbol cannot be detected (step S2 is No). The cut-out symbol is searched using the image signal of the second light receiving sensor 23B (step S5). However, the present invention is not limited to this, and when the control circuit 40 is configured to be capable of simultaneous processing, the cut-out symbol is searched using the image signal of the first light receiving sensor 23A, and at the same time regardless of the search result. In parallel, the cut-out symbol may be searched using the image signal of the second light receiving sensor 23B. In this case, when a cut-out symbol can be searched from both image signals, decoding is performed using a preset image signal.

  Further, although the information code reading device 10 of the above-described embodiment is a portable type, the present invention can also be applied to a fixed information code reading device fixed at a predetermined position (for example, around the belt conveyor).

  In the above-described embodiment, the image scanning directions of the two light receiving sensors 23A and 23B are shifted from each other by 90 degrees. However, the difference between the image scanning directions may not be 90 degrees. Further, three or more light receiving sensors may be provided.

  Further, instead of the FPGA 34, another device such as an ASIC that can search for a cut-out symbol by hardware may be used.

10: Information code reading device, 11: Housing, 11a: Reading port, 12: Operation switch, 14: Operation switch, 15: Printed wiring board, 16: Printed wiring board, 20: Circuit part, 21: Red light emitting diode (light source) ), 23: light receiving sensor (image capturing means), 24: light receiving surface, 27: imaging lens, 31: amplification circuit, 33: A / D conversion circuit, 34: FPGA, 35: memory (storage means), 36: Address generation circuit, 38: synchronization signal generation circuit, 40: control circuit, 41: power switch, 43: LED, 44: buzzer, 46: liquid crystal display, 48: communication interface, 49: secondary battery, 52: light collection Lens, Lf: Illumination light, Lr: Shako, Q: QR Code, VP: segment, XA, XB :( imaging area) central axis, Xa, the Xb :( receiving lens) center axis, S1, S5: search means, S3, S7: information reading means

Claims (7)

A light source for irradiating the two-dimensional information code with light;
Image capturing means for capturing an image including a two-dimensional information code irradiated with light from the light source, and outputting an image signal indicating the captured image;
Storage means for storing an image signal output from the image capturing means;
Search means for searching for a position detection pattern of the two-dimensional information code using the image signal when storing the image signal in the storage means;
Information reading means for determining the position of the two-dimensional information code based on the position detection pattern searched by the search means from the image signal stored in the storage means, and reading information from the two-dimensional information code; An information code reading device comprising:
The image capturing means includes a plurality of image capturing means whose image scanning directions are different from each other,
The search means can search the position detection patterns from image signals output from the plurality of image capture means,
The information reading means determines the position of a two-dimensional information code using an image from which a position detection pattern has been searched, and reads information from the two-dimensional information code. In claim 1,
The search means searches for the position detection pattern from image signals output from all the image capture means,
The information reading means determines the position of the two-dimensional information code based on the position detection pattern using one image whose position detection pattern has been searched by the search means, and obtains information from the two-dimensional information code. An information code reading device characterized by reading. In claim 1,
The search means searches for a position detection pattern using image signals output from the plurality of image capture means in order in a predetermined order, and when the position detection pattern cannot be searched. An information code reading apparatus for searching a position detection pattern using an image signal of a next image capturing means. In claim 2 or 3,
The information reading unit uses an image for which the position detection pattern can be searched, but uses another image for which the position detection pattern can be searched when information cannot be read from the two-dimensional information code of the image. An information code reader characterized by reading information from a two-dimensional information code. In any one of Claims 1-4,
An information code reading apparatus comprising two image capturing means, wherein the two image capturing means are different from each other in the scanning direction of the image by 90 degrees. 6. The information code reading device according to claim 1, wherein the information code reading device is a fixed type. In any one of Claims 1-6,
An information code reading apparatus comprising an area sensor as the image capturing means.