JP2021149603A - Optical reading device - Google Patents

Abstract

To speedily output a result of decode of codes when a plurality of code candidate areas are extracted.SOLUTION: A processing part performs extraction processing that extracts from a read image generated by an imaging part a code candidate area. The processing part executes decode processing in order with respect to the plurality of extracted code candidate areas when a plurality of code candidate areas are extracted, and when it succeeds in decode processing in any code candidate area, excludes from an object to be decoded a code candidate area positioned away from the successful code candidate area.SELECTED DRAWING: Figure 12

Description

The present invention relates to an optical reader that reads information contained in a scanned image generated by imaging a workpiece.

Generally, a code reader captures a code such as a bar code or a two-dimensional code attached to a work with a camera, cuts out the code contained in the obtained image by image processing, binarizes it, and decodes it. It is configured so that information can be read (see, for example, Patent Documents 1 and 2).

The optical reader of Patent Document 1 determines an upper limit of the exposure time for reading the code based on the moving speed of the work and the cell size constituting the code, and acquires a plurality of images including the code. By analyzing, the exposure time is automatically set within the above upper limit value.

The optical reader of Patent Document 2 has a first core that causes an image pickup unit to execute an image pickup process and transfers the acquired image data to a shared memory, and a shared memory based on a decoding process request from the first core. It has a second core that reads image data from the inside and executes decoding processing.

JP-A-2018-136860 Japanese Unexamined Patent Publication No. 2012-64178

By the way, in the reading process in the optical reading device as in Patent Documents 1 and 2, there is a high possibility that the code exists by scanning the entire image after the preprocessing and the preprocessing that performs various filter processing and the like. It generally consists of three processes: a code search process for searching the (code candidate area) and a decoding process for decoding using the image data of the code candidate area specified in the code search process.

However, if the range imaged by the imaging unit is wide, the number of code candidate regions in the scanned image may increase. For example, the code candidate area can be extracted based on the feature amount indicating the code-likeness, but in addition to the code candidate area that actually contains the code, the code candidate area that does not contain the code is extracted. There are times. The reason is that even if the code is not included, if a character string or pattern similar to the code is attached to the work, the feature amount of that part becomes large and it is extracted as a code candidate area. ..

If the code is included in all of the extracted plurality of code candidate areas, it is necessary to execute the decoding process for all the code candidate areas, but as described above, the code is included in all of the plurality of code candidate areas. In some cases, it is not included, in which case it is useless to execute the decoding process on the code candidate area that does not contain the code, and the result is that the time until the decoding process is completed is prolonged. .. In particular, when a plurality of codes exist in the scanned image and the codes are individually decoded, there is a problem that the output of the decoding result is significantly slowed down.

The present invention has been made in view of this point, and an object of the present invention is to enable high-speed output of a code decoding result when a plurality of code candidate regions are extracted.

In order to achieve the above object, the present disclosure can presuppose a stationary optical reader that reads a cord attached to a workpiece being conveyed on a line. The optical reading device receives the illumination unit for irradiating the area through which the work passes and the light emitted from the illumination unit and reflected from the area through which the work passes, and passes through the work. When a plurality of code candidate regions are extracted as a result of executing an imaging unit that generates a scanned image that captures the region to be imaged and an extraction process that extracts a code candidate region from the scanned image generated by the imaging unit, extraction is performed. When the decoding process is executed in order for the plurality of code candidate areas and the decoding process of any of the code candidate areas is successful, the decoding result is generated and the position is separated from the successful code candidate area. It includes a processing unit that excludes the code candidate area from the decoding processing target, and an output unit that outputs the decoding result generated by the processing unit.

According to this configuration, when the work transported on the line is irradiated with light from the illumination unit, the light reflected by the work is received by the imaging unit, and the read image including the work and the code attached to the work is received. Is generated. The processing unit executes an extraction process on the read image and extracts a code candidate area. As a result of the extraction process, a plurality of code candidate areas may be extracted, and in addition to the code candidate area containing the code, a code candidate area not containing the code may be extracted.

When a plurality of code candidate areas are extracted, the processing unit executes decoding processing in order for the extracted plurality of code candidate areas. If the decoding process of any of the code candidate areas is successful, the code candidate area at a position separated from the code candidate area is excluded from the decoding target.

That is, it is assumed that a plurality of codes are attached to the work, for example, when a plurality of codes are printed on one label and they are attached to the work, or when the periphery of the work is attached. The case where a plurality of codes are printed in a place close to the above can be mentioned. In any of these cases, multiple codes are often close to each other. Therefore, it is unlikely that the code exists in a place away from the code candidate area where the decoding process was successful, and the code candidate area in the place where this code is unlikely to exist is excluded from the decoding process. Therefore, the decoding process can be preferentially executed for the code candidate area where the code is likely to exist.

In the second disclosure, the processing unit determines the decoding processing area based on the position of the code candidate area that succeeded in the decoding processing and the preset area limitation parameter, and the code located in the decoding processing area. The candidate area can be targeted for decoding processing.

According to this configuration, when the decoding process of a certain code candidate area is successful, the decoding processing area is determined based on the position of the code candidate area and the preset area limitation parameter, and the position is located in this decoding processing area. Decoding processing is executed for the code candidate area. For example, when a circle centered on the central portion of the code candidate area that has been successfully decoded is drawn, the area within this circle can be used as the decoding processing area. In this case, the region-limited parameter can be the radius of the circle. This method is an example, and the decoding processing area may be determined by another method. For example, various figures such as an ellipse, an oval, and a polygon centered on the center of the code candidate area are drawn, and the method is used. The area in the figure can be used as the decoding processing area.

In the third disclosure, the processing unit can target the code candidate area that overlaps with the decoding processing area for decoding processing.

That is, the code candidate area that overlaps with the decoding processing area is located near the code candidate area that succeeded in the decoding processing, and the code exists in such a code candidate area. Probability is high. In this case, it can be a decoding process target.

In the fourth disclosure, the processing unit can exclude the code candidate area located outside the decoding processing area from the decoding processing target.

According to this configuration, the code candidate area located outside the decoding processing area is separated from the code candidate area where the decoding processing is successful, and the code exists in such a code candidate area. It is unlikely and can be excluded from the decoding process.

In the fifth disclosure, at the time of setting the optical reading device, a scanned image including a plurality of codes is acquired from the imaging unit, and the processing unit executes a decoding process for a plurality of code candidate regions of the acquired scanned image. However, it is provided with a tuning execution unit that automatically sets the area-limited parameters so that a plurality of code candidate areas for which decoding processing has succeeded are included in the decoding processing area.

According to this configuration, the area limitation parameter can be automatically set to the optimum value based on the scanned image.

In the sixth disclosure, a reception unit that accepts the setting of the area-limited parameter by the user is provided.

According to this configuration, the area-limited parameter can be set by the user, so that the area-limited parameter can be set so as to include a plurality of codes attached to the actual work. It is also possible for the user to adjust the area-limited parameters after the area-limited parameters are automatically set by the tuning execution unit. In this case, the reception unit can also be called an adjusting unit. s
In the seventh disclosure, when the processing unit succeeds in decoding the other code candidate area located in the decoding processing area after determining the decoding processing area, the position of the other code candidate area and the above-mentioned A decoding processing area is newly determined based on the area limitation parameter, and a code candidate area located in the newly determined decoding processing area is targeted for decoding processing.

For example, when three codes, a first code, a second code, and a third code are attached to the work side by side, if the decoding process for the first code candidate area in which the first code exists is successful, the first code is used. The first decoding processing area is determined based on the position of the code candidate area 1 and the area limitation parameter. Within this first decoding processing area, a second code candidate area in which the second code exists and a third code candidate area in which the third code exists are located. After that, the processing unit executes the decoding process for the second code candidate area, and when the decoding process is successful, determines a new decoding processing area based on the position of the second code candidate area and the area limitation parameter. do. In this new decoding processing area, a third code candidate area in which the third code exists will be located. In this way, the decoding processing area can be narrowed down step by step according to the success of the decoding processing, so that higher-speed decoding processing becomes possible.

In the eighth disclosure, the processing unit can change the region limitation parameter according to the size of the code on the scanned image.

Even when imaging a work with a code of the same size, for example, if the distance between the work and the imaging unit is short, the code will be large on the scanned image, and the distance between the work and the imaging unit will be large. The farther the code is, the smaller the code will be on the scanned image. Therefore, when the area limitation parameter is a fixed value, even if the size of the decoding processing area is suitable for a large code on the scanned image, the decoding processing area is large for a small code on the scanned image. It is conceivable that the code candidate area, which is unlikely to contain the code, will enter the decoding processing area. According to this configuration, the area limitation parameter can be changed according to the size of the code on the scanned image, so that an appropriate decoding processing area can be determined regardless of the size of the code on the scanned image. can.

In the ninth disclosure, the processing unit changes the region limiting parameter so that the smaller the size of the code on the scanned image, the smaller the decoding processing region. Further, in the tenth disclosure, the processing unit changes the region limiting parameter so that the larger the size of the code on the read image, the larger the decoding processing region.

As a result, the size of the decoding processing area can be determined so as to correspond to the size of the code on the actual scanned image. Examples of the code size on the scanned image include the area of the code candidate area, the size of the minimum module of the code, and the like.

In the eleventh disclosure, the processing unit calculates an estimated value of the number of modules or the number of elements for each of the extracted plurality of code candidate areas, and determines the code candidate area for executing the decoding process according to the calculated estimated value. select.

That is, the number of modules or elements constituting the code is a feature amount that does not depend on the area of the code occupied in the read image, and by using such a feature amount, the code candidate area can be extracted at high speed.

As described above, according to the present disclosure, when a plurality of code candidate areas are extracted and the decoding process of any of the code candidate areas is successful, the code candidate area located at a position separated from the code candidate area. Is excluded from the decoding processing target, so that the decoding processing can be preferentially executed for the code candidate area where the code is likely to exist, and the decoding result can be output at high speed.

FIG. 1 is a diagram illustrating an operation of the optical reader according to the embodiment of the present invention. FIG. 2 is a diagram showing an example of a work to which a plurality of codes are attached. FIG. 3 is a block diagram of the optical reader. FIG. 4 is a front view of the optical reader. FIG. 5 is a view of the optical reader as viewed from the operation button side. FIG. 6 is a view of the optical reader as viewed from the terminal side. FIG. 7 is a flowchart showing an example of the procedure of the decoding process by the processing unit. FIG. 8 is a diagram showing an example of a scanned image generated by imaging the work. FIG. 9 is a flowchart showing an example of the procedure of the code search data generation process. FIG. 10 is a diagram showing the extracted code candidate regions. FIG. 11 is a diagram showing a determined code processing area. FIG. 12 is a diagram showing a case where a code candidate area located at a position separated from the successful code candidate area is excluded from the decoding processing target. FIG. 13 is a diagram showing a case where the code processing area is gradually narrowed. FIG. 14 is a diagram showing a case where the code becomes large on the read image. FIG. 15 is a diagram showing a case where the code becomes smaller on the scanned image. FIG. 16 is a diagram showing a state in which the size of the decoding processing region is changed so as to correspond to the case where the code on the scanned image is small. FIG. 17 is a diagram showing a state in which the size of the decoding processing region is changed so as to correspond to the case where the code on the read image is large.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is essentially merely an example and is not intended to limit the present invention, its application or its use.

FIG. 1 is a diagram schematically showing an operation time of the optical reading device 1 according to the embodiment of the present invention. In this example, a plurality of work Ws are transported in the direction of the arrow Y in FIG. 1 in a state of being placed on the upper surface of the transport belt conveyor B, and the work W is placed at a position away from the work W in the embodiment. The optical reading device 1 is installed. The work W may flow not only in the central portion of the upper surface of the transport belt conveyor B in the width direction but also on one side and the other side in a state of being offset in the width direction, and the work W does not always pass through a fixed position. No.

The optical reader 1 can be used, for example, in a distribution center or the like. Conveyed objects (work W) of various sizes and shapes are transported at high speed on the transport belt conveyor B installed in the distribution center. Further, the distance between the workpieces W in the transport direction is also set narrow.

As shown in FIG. 2, a plurality of codes CD1, CD2, CD3, CD4, and CD5 may be attached to a surface of the work W, but only one may be attached. The first code CD1, the second code CD2, and the third code CD3 attached to the upper left of the work W are the codes to be read, and the fourth code CD4 and the third code CD3 attached to the upper right of the work W are the codes to be read. Code 5 CD5 is a code that is not to be read. The first to fifth cords CDs 1 to 5 may be the side surface of the work W, the upper surface, the front surface, or the back surface.

Further, on the same surface of the work W to which the first to fifth codes CD1 to 5 are attached, in addition to the first to fifth codes CD1 to CD5, the first to eighth character strings L1 ~ L8 is also attached. The first to third character strings L1 to L3 are arranged close to the first to third codes CD1 to CD3 to be read, while the fourth to eighth character strings L4 to L8 are It is located far from the first to third codes CD1 to CD3. Further, the work W may be provided with a pattern or the like in addition to the character strings L1 to L8 or in place of the character strings L1 to L8.

The work W shown in FIG. 2 is an example, and the number and arrangement of codes, the presence or absence of character strings and patterns, and the like are various. While lining up in the direction, the fourth and fifth codes CD4, CD5 and the first to eighth character strings L1 to L8 are separated from the first to third codes CD1 to CD3. That is, the distance S1 between the first code CD1 and the second code CD2 and the distance S2 between the second code CD2 and the third code CD3 are among the third code CD3 and the character strings L1 to L18. The distance from the first character string L1 closest to the third code CD3 is set to be shorter than the distance S3. Further, the interval S4 between the first to third codes CD1 to CD3 and the fourth and fifth codes CD4 and CD5 is set longer than the intervals S1 and S2. Therefore, among the first to fifth codes CD1 to CD5 and the first to eighth character strings L1 to L8, the first to third codes CD1 to CD3 form one group.

Although the details will be described later, the regions where the first to fifth codes CD1 to CD5 exist on the scanned image obtained by capturing the work W are regions that can be code candidate regions. Further, even if the character strings L1 to L8 are not codes, the frequency may be as high as the code depending on the character type, the character spacing, and the like. In this case, the character strings L1 to L8 are also code candidate areas. May be.

In this example, the case where the first to fifth codes CD1 to CD5 are one-dimensional codes will be described, but they may be two-dimensional codes. Further, among the first to third codes CD1 to CD3 to be read, some codes may be one-dimensional codes and the remaining codes may be two-dimensional codes. A typical example of a one-dimensional code is a barcode, and examples thereof include a JAN code, an ITF code, and a GS1-128. Typical examples of two-dimensional codes are QR code (registered trademark), micro QR code, data matrix (Data matrix), Veri code, Aztec code, PDF417, Maxi code (Maxi). code) and so on. There are a stack type and a matrix type in the two-dimensional code, and the present invention can be applied to any two-dimensional code. The first to fifth codes CD1 to CD5 may be attached by directly printing or engraving on the work W, or may be attached by attaching to the work W after printing on a label or the like, and the means thereof. , The method does not matter.

As shown in FIG. 1, the optical reading device 1 is a device that optically reads the first to third codes CD1 to CD3 (shown in FIG. 2) attached to the work W, and specifically, the work. The first to third codes CD1 to CD3 attached to W are imaged to generate a read image, and the first to third codes CD1 to CD3 included in the generated read image are decoded and decoded. It is a code reader configured to be able to output the results.

The optical reader 1 can be configured as a stationary optical reader that is fixed to a bracket or the like (not shown) so as not to move during its operation, but can be a robot (not shown) or a user. Etc. may be operated while grasping and moving. Further, the optical reading device 1 may read the first to third codes CD1 to CD3 of the work W in the stationary state. The operation time is a time when the operation of reading the first to third codes CD1 to CD3 of the work W sequentially transported by the transport belt conveyor B is being performed. The optical reading device 1 of this embodiment is suitable for a scene in which it is desired to read the first to third codes CD1 to CD3 attached to the work W whose position changes, but the work is not limited to this and the position does not change. It can also be used when reading the first to third codes CD1 to CD3 attached to W.

As shown in FIG. 1, the optical reading device 1 is wiredly connected to a computer 100 as an external control device and a programmable logic controller (PLC) 101 by signal lines 101a and 101a, respectively, but the present invention is not limited to this. A communication module may be built in the optical reader 1, the computer 100, and the PLC 101, and the optical reader 1 and the computer 100 and the PLC 101 may be wirelessly connected. The PLC 101 is a control device for sequence control of the transport belt conveyor B and the optical reading device 1, and a general-purpose PLC can be used.

The computer 100 can use a general-purpose or dedicated electronic computer, a portable terminal, or the like. In this example, a so-called personal computer is used, and includes a control unit 40, a storage device 41, a display unit 42, an input unit 43, and a communication unit 44. By downsizing the optical reading device 1, it becomes difficult to make all the settings of the optical reading device 1 only by the display unit 7, the buttons 8, 9 and the like of the optical reading device 1. A computer 100 may be prepared separately, and the computer 100 may make various settings for the optical reading device 1 and transfer the setting information to the optical reading device 1.

Further, since the computer 100 includes the communication unit 44, the computer 100 and the optical reading device 1 are connected so as to be capable of bidirectional communication, and a part of the processing of the optical reading device 1 described above is performed by the computer 100. You may. In this case, a part of the computer 100 becomes a part of the components of the optical reading device 1.

The control unit 40 is a unit that controls each unit included in the computer 100 based on a program stored in the storage device 41. The storage device 41 is composed of various memories, a hard disk, an SSD (Solid State Drive), and the like. The display unit 42 is composed of, for example, a liquid crystal display or the like. The input unit 43 is composed of a keyboard, a mouse, a touch sensor, and the like. The communication unit 44 is a part that communicates with the optical reader 1. The communication unit 44 may have an I / O unit connected to the optical reader 1, a serial communication unit such as RS232C, and a network communication unit such as a wireless LAN or a wired LAN.

The control unit 40 obtains a user interface image for setting the imaging conditions of the imaging unit 5 of the optical reading device 1 and the image processing conditions of the processing unit 23, the decoding result output from the optical reading device 1, the image data, and the like. A user interface image or the like for display is generated and displayed on the display unit 42. The display unit 42 may form a part of the optical reading device 1. The storage device 41 is a portion that stores the decoding result, which is the result of the decoding process being executed by the processing unit 23, the image captured by the imaging unit 5, various setting information, and the like.

Further, the optical reading device 1 receives a reading start trigger signal that defines the reading start timing of the first to third codes CD1 to CD3 from the PLC 101 via the signal line 101a during its operation. Then, the optical reading device 1 performs imaging and decoding processing of the work W based on the reading start trigger signal. After that, the decoding result obtained by the decoding process is transmitted to the PLC 101 via the signal line 101a. As described above, during the operation of the optical reading device 1, the input of the reading start trigger signal and the output of the decoding result are repeatedly performed between the optical reading device 1 and the external control device such as the PLC 101 via the signal line 101a. As described above, the input of the reading start trigger signal and the output of the decoding result may be performed via the signal line 101a between the optical reading device 1 and the PLC 101, or other signal lines (not shown) may be used. You may go through. For example, a sensor for detecting that the work W has arrived at a predetermined position and the optical reading device 1 may be directly connected, and a reading start trigger signal may be input from the sensor to the optical reading device 1. .. Further, the decoding result, the image, and various setting information can be output to a device other than the PLC 101, for example, the computer 100.

[Overall configuration of optical reader 1]
As shown in FIGS. 4 to 6, the optical reading device 1 includes a housing 2 and a front cover 3. As shown in FIG. 4, an illumination unit 4, an image pickup unit 5, and an aimer 6 are provided on the front surface of the housing 2. The configuration of the illumination unit 4 and the imaging unit 5 will be described later. The aimer 6 is composed of a light emitting body such as a light emitting diode (Light Emitting Diode). The aimer 6 is for irradiating light toward the front of the optical reader 1 to indicate an image pickup range by the image pickup unit 5 and a guideline for the optical axis of the illumination unit 4. The user can also install the optical reader 1 with reference to the light emitted from the aimer 6.

Further, as shown in FIG. 5, a display unit 7, a select button 8, an enter button 9, and an indicator 10 are provided on one end surface of the housing 2. The configuration of the display unit 7 will be described later. The select button 8 and the enter button 9 are buttons used for setting the optical reading device 1 and the like, and are connected to the control unit 20. The control unit 20 can detect the operating states of the select button 8 and the enter button 9. The select button 8 is a button operated when selecting one from a plurality of options displayed on the display unit 7. The enter button 9 is a button operated when confirming the result selected by the select button 8. The indicator 10 is connected to the control unit 20 and can be composed of a light emitting body such as a light emitting diode. The operating state of the optical reading device 1 can be notified to the outside by the lighting state of the indicator 10.

Further, as shown in FIG. 6, a power connector 11, a network connector 12, a serial connector 13, and a USB connector 14 are provided on the other end surface of the housing 2. Further, a heat sink 15 serving as a rear case is provided on the back surface of the housing 2. A power wiring for supplying power to the optical reader 1 is connected to the power connector 11. The serial connector 13 is a signal line 100a, 101a connected to the computer 100 and the PLC 101, and the network connector 12 is an Ethernet connector. The Ethernet standard is an example, and signal lines of standards other than the Ethernet standard can be used.

Further, a control unit 20, a storage device 50, an output unit 60, and the like shown in FIG. 3 are provided inside the housing 2. These will be described later.

In the description of this embodiment, the front surface and the back surface of the optical reading device 1 are defined as described above, but this is for convenience of explanation only and does not limit the orientation when the optical reading device 1 is used. No. That is, as shown in FIG. 1, the optical reading device 1 may be installed and used so that the front surface of the optical reading device 1 faces downward, or the optical reading device 1 may be installed and used so that the front surface faces upward. It is possible to install and use the optical reading device 1 so that the front surface faces downward and is inclined, or to install and use the optical reading device 1 so that the front surface faces the vertical plane.

[Structure of lighting unit 4]
As shown by a broken line in FIG. 4, the illumination unit 4 is a member for irradiating light toward a region through which the work W transported by the transport belt conveyor B passes. The light emitted from the illumination unit 4 illuminates at least a predetermined range in the transport direction by the transport belt conveyor B. This predetermined range is wider than the dimension of the largest work W that is expected to be transported during operation in the same direction. The illumination unit 4 illuminates the first to third codes CD1 to CD3 attached to the work W transported by the transport belt conveyor B.

The illumination unit 4 includes, for example, a light emitting body 4a made of a light emitting diode or the like, and the light emitting body 4a may be one or a plurality of light emitting bodies 4a. In this example, a plurality of light emitting bodies 4a are provided, and the imaging unit 5 faces the outside from between the light emitting bodies 4a. Further, the light of the aimer 6 is irradiated from between the light emitting bodies 4a. The illumination unit 4 is electrically connected to the image pickup control unit 22 of the control unit 20 and is controlled by the control unit 20 so that it can be turned on and off at an arbitrary timing.

In this example, the illumination unit 4 and the image pickup unit 5 are mounted on one housing 2 and integrated, but the illumination unit 4 and the image pickup unit 5 may be configured separately. In this case, the lighting unit 4 and the imaging unit 5 can be connected by wire or wirelessly. Further, the control unit 20 described later may be built in the illumination unit 4 or may be built in the image pickup unit 5. The lighting unit 4 mounted on the housing 2 is referred to as internal lighting, and the lighting unit 4 separated from the housing 2 is referred to as external lighting. It is also possible to illuminate the work W using both internal and external lighting.

[Structure of imaging unit 5]
FIG. 3 is a block diagram showing the configuration of the optical reader 1. The image pickup unit 5 is a member for receiving the light emitted from the illumination unit 4 and reflected from the region through which the work W passes, and generating a scanned image of the region through which the work W passes. As the image pickup unit 5, an area camera in which pixels are arranged vertically and horizontally (X direction and Y direction) can be used, whereby it is possible to read a two-dimensional code and to perform one work W being conveyed a plurality of times. It becomes possible to take an image.

As shown in FIG. 3, the image pickup unit 5 includes an image pickup element 5a capable of imaging at least a portion of the work W to which the first to third codes CD1 to CD3 are attached, an optical system 5b having a lens or the like, and an auto. It is equipped with a focus mechanism (AF mechanism) 5c. Light reflected from at least the portions of the work W to which the first to third codes CD1 to CD3 are attached is incident on the optical system 5b. The image sensor 5a is a light receiving element such as a CCD (charge-coupled device) or CMOS (complementary metal oxide semiconductor) that converts an image including the first to third codes CD1 to CD3 obtained through the optical system 5b into an electric signal. It is an image sensor consisting of.

The AF mechanism 5c is a mechanism for focusing by changing the position and the refractive index of the focusing lens among the lenses constituting the optical system 5b. The AF mechanism 5c is connected to the control unit 20 and is controlled by the AF control unit 21 of the control unit 20.

The image pickup device 5a is connected to the image pickup control unit 22 of the control unit 20. The image sensor 5a is controlled by the image pickup control unit 22 to take an image of a region through which the work W passes at predetermined fixed time intervals, or the work W passes at an arbitrary timing in which the time interval is changed. It is configured so that the area can be imaged. The imaging unit 5 is configured to be capable of executing so-called infinite burst imaging, which continuously generates scanned images. As a result, the first to third codes CD1 to CD3 of the work W moving at high speed can be captured in the read image without escaping, and one work W being transported can be imaged a plurality of times to obtain a plurality of images. It becomes possible to generate a scanned image. The image pickup control unit 22 may be built in the image pickup unit 5.

The intensity of the light received by the light receiving surface of the image sensor 5a is converted into an electric signal by the image sensor 5a, and the electric signal converted by the image sensor 5a is used as image data constituting the read image in the processing unit of the control unit 20. Transferred to 23.

[Structure of display unit 7]
The display unit 7 is made of, for example, an organic EL display, a liquid crystal display, or the like. The display unit 7 is connected to the control unit 20 as shown in FIG. On the display unit 7, for example, a character string which is a decoding result of the first to third code CD1 to CD3 and the first to third code CD1 to CD3 imaged by the imaging unit 5, a reading success rate, and a matching level ( Reading margin) etc. can be displayed. The read success rate is the average read success rate when the read process is executed a plurality of times. The matching level is a reading margin that indicates the ease of reading the first to third codes CD1 to CD3 that have been successfully decoded. This can be obtained from the number of error corrections that occurred during decoding, and can be expressed numerically, for example. The smaller the error correction, the higher the matching level (reading margin), while the more error correction, the lower the matching level (reading margin).

[Configuration of storage device 50]
The storage device 50 is composed of various memories, a hard disk, an SSD, and the like. The storage device 35 is provided with a decoding result storage unit 51, an image data storage unit 52, and a parameter set storage unit 53. The decoding result storage unit 51 is a portion that stores the decoding result, which is the result of the decoding process being executed by the processing unit 23. The image data storage unit 52 is a unit that stores an image captured by the image pickup unit 5. The parameter set storage unit 53 includes setting information set by a setting device such as a computer 100, setting information set by the select button 8 and the enter button 9, and setting information obtained as a result of tuning by the tuning execution unit 24. It is a part that memorizes such things. The parameter set storage unit 53 includes a plurality of imaging conditions (gain, light intensity of the illumination unit 4, exposure time, etc.) of the imaging unit 5 and image processing conditions (type of image processing filter, etc.) in the processing unit 23. A plurality of parameter sets including the parameters of can be stored.

[Structure of output unit 60]
The optical reader 1 has an output unit 60. The output unit 60 is a unit that outputs a decoding result that has been decoded by the processing unit 23, which will be described later. Specifically, when the decoding process is completed, the processing unit 23 transmits the decoding result to the output unit 60. The output unit 60 can be composed of a communication unit that transmits data related to the decoding result received from the processing unit 23 to, for example, the computer 100 and the PLC 101. The output unit 60 may have an I / O unit connected to the computer 100 and the PLC 101, a serial communication unit such as RS232C, and a network communication unit such as a wireless LAN or a wired LAN.

[Configuration of control unit 20]
The control unit 20 shown in FIG. 3 is a unit for controlling each part of the optical reading device 1, and can be configured by a CPU, an MPU, a system LSI, a DSP, dedicated hardware, or the like. The control unit 20 is equipped with various functions as described later, and these may be realized by a logic circuit or may be realized by executing software.

The control unit 20 includes an AF control unit 21, an imaging control unit 22, a processing unit 23, a tuning execution unit 24, and a UI management unit 25. The AF control unit 21 is a portion that focuses the optical system 5b by a conventionally known contrast AF or phase difference AF. The AF control unit 21 may be included in the image pickup unit 5.

[Structure of Imaging Control Unit 22]
The image pickup control unit 22 is a part that controls not only the image pickup unit 5 but also the illumination unit 4. That is, the image pickup control unit 22 is composed of a unit that adjusts the gain of the image pickup element 5a, controls the amount of light of the illumination unit 4, and controls the exposure time (shutter speed) of the image pickup element 5a. The gain, the amount of light of the illumination unit 4, the exposure time, and the like are included in the imaging conditions of the imaging unit 5.

[Structure of processing unit 23]
The processing unit 23 executes decoding processing on the code candidate area extracted from the read image, and when the decoding processing is successful, the processing unit 23 is a part that generates a decoding result and transmits it to the output unit 60. Hereinafter, details of each process executed by the processing unit 23 will be described with reference to the flowchart of FIG. 7.

This flowchart starts at the timing when the optical reading device 1 receives the reading start trigger signal, and ends at the timing when the operation stop operation is performed. After the start, in step SA1, the processing unit 23 acquires the scanned image 200 (shown in FIG. 8) generated by the imaging unit 5 from the imaging unit 5. The scanned image 200 shown in FIG. 8 is an image generated by capturing the work W shown in FIG. 2 from one side. The read image 200 includes the first to fifth codes CD1 to CD5 and the first to eighth character strings L1 to L8 attached to the work W.

After acquiring the scanned image in step SA1, the process proceeds to step SA2 to execute the code search data generation process. The details of the code search data generation process are shown in FIG. In step SB1 after the start, edge detection processing is executed on the scanned image 200 to generate edge data. The edge detection process can be executed by using, for example, a Sobel filter or the like. For example, in the case of a one-dimensional code, if the rotation angle of the barcode is 0 °, it is an X-direction sobel, if it is 90 °, it is a Y-direction sobel, and if there is no premise for the rotation angle of the barcode, it is an X-direction sobel or a Y-direction sobel. A composite image may be generated by adding them to the image.

In step SB1, for example, an edge intensity image, an edge angle image, or the like can be generated as an image after the edge detection process, and an image obtained by performing a common convolution process or an arithmetic process may be generated. Further, not only the first-order differential processing but also the second-order differential processing and the like can be used as the edge detection processing.

In step SB2, the edge image data generated in step SB1 is acquired. After that, the process proceeds to step SB3, and an edge image data integration process for integrating edge image data of a certain pixel and its vicinity is executed. For example, in the edge image data, there is a high possibility that the code exists in a region where pixels having a large luminance value are gathered, so that region can be estimated as a code candidate region. By integrating a certain pixel constituting the edge image data and the edge image data existing in the vicinity thereof, it is possible to express an area in which pixels having a large brightness value are gathered. In this example, a product-sum calculation process or a pixel integration process for generating data for measuring the degree of aggregation of edge image data within a certain area can be executed. For example, a smoothing process that has the effect of adding pixel values within a specific window size can be used. Further, the reduction process may be used, and when the reduction process is used, the amount of data is small, so that there is an advantage that the scanning amount can be small.

By going through steps SB1 to SB3, it is possible to calculate a feature amount indicating code-likeness for each region in the image data. Since the code candidate area can be searched and extracted based on the feature amount, the calculated feature amount is acquired as code search data (step SB4). It is also possible to generate a feature amount image to which a brightness value corresponding to the calculated feature amount is assigned. The feature amount image can display a region having a large feature amount brighter or darker than a region having a small feature amount, and can be a so-called heat map image. The feature amount itself may be used as code search data without generating a heat map image.

It is also possible to generate code search data for a one-dimensional code and a two-dimensional code. That is, in the edge image data integration process for the one-dimensional code, the features of the shape of the one-dimensional code are used to integrate the edges having the same edge direction. For example, an edge angle image is generated, those with close edge angles are added together, and those with far edge angles are subtracted. Further, within a certain range of the edge image data, a process of adding image data having close edge directions and subtracting image data having different edge directions may be executed. Further, in the edge image data integration process for a two-dimensional code, edges having irregular edge directions are integrated by utilizing the characteristics of the shape of the two-dimensional code. For example, an edge angle image is generated and those with close edge angles are averaged. Further, a process of adding image data having different edge directions may be executed within a certain range of the edge image data. As described above, the process of step SA2 of the flowchart shown in FIG. 7 is completed.

After that, the process proceeds to step SA3, and the processing unit 23 extracts the code candidate area using the code search data. The code candidate area is an area including a portion having a large feature amount indicating code-likeness, and the processing unit 23 extracts an area including a portion having a feature amount equal to or more than a predetermined threshold value from the scanned image 200. The code candidate area may be extracted by 1 or 2 or more depending on the number of codes included in the scanned image 200, and may be further increased by the character string included in the scanned image 200. Further, the position of the code candidate area is a position corresponding to the position of the code or the character string included in the scanned image 200. Further, the size and shape of the code candidate area correspond to the size and shape of the code and the character string included in the scanned image 200.

FIG. 10 is a diagram showing a code candidate region extracted in step SA3. This is an example in which a total of 13 code candidate regions of reference numerals 501 to 513 are extracted. The regions where the first to third codes CD1 to CD3 in FIG. 8 are located are extracted as code candidate regions 501 to 503 in FIG. The regions where the fourth code CD4 and the fifth code CD5 in FIG. 8 are located are extracted as code candidate regions 504 and 505 in FIG. The regions where the first to eighth character strings L1 to L8 are located are extracted as code candidate regions 506 to 513 in FIG. The first to eighth character strings L1 to L8 in FIG. 8 are not codes, but are extracted as code candidate regions 506 to 513 on the read image 200 because they have a high frequency like the code. Sometimes. Since the black-painted quadrangle in FIG. 8 is clearly not a code, the feature amount indicating the code-likeness is less than the threshold value, and the quadrangle is not extracted as a code candidate area in FIG.

After extracting the code candidate area in step SA3, the process proceeds to step SA4. In the first step SA4, the code candidate area for which the decoding process is first executed is selected from the plurality of code candidate areas extracted in step SA3. Specifically, the processing unit 23 calculates an estimated value of the number of modules or the number of elements for each of the extracted plurality of code candidate areas 501 to 013, and calculates an estimated value of the code candidate area for executing the decoding process. According to, first select the code candidate area to execute the decoding process. For example, the processing unit 23 executes a process of selecting one code candidate area whose estimated value is closest to the value of the code to be read. That is, the number of modules or elements constituting the code is a feature amount that does not depend on the area of the code occupied in the scanned image 200, and by using such a feature amount, the code candidate area can be extracted at high speed. ..

Then, the process proceeds to step SA5. In step SA5, the processing unit 23 executes decoding processing on one code candidate area selected in step SA4. After the decoding process, the process proceeds to step SA6, and the processing unit 23 determines whether or not the decoding process in step SA5 is successful. If NO is determined in step SA6 and the decoding process is not successful, the process returns to step SA4, a code candidate area other than the code candidate area selected first is selected, and then the process proceeds to step SA5 to execute the decoding process. Then, it is determined again in step SA6 whether or not the decoding process is successful. Steps SA4 to SA6 are repeated until the decoding process is successful, whereby the decoding process can be sequentially executed for the plurality of extracted code candidate areas.

If the decoding process of any of the code candidate areas is successful, the process proceeds to step SA7. In step SA7, the processing unit 23 determines whether or not the specified number of decoding processes are successful. In this example, since the first to third codes CD1 to CD3 are the codes to be read, the designated number is 3, so in the first step SA7, NO is determined and the process proceeds to step SA9. In step SA9, the processing unit 23 executes a process of limiting the reading area.

At this time, in step SA9, the area limitation parameter is used. The area limitation parameter is a parameter for excluding the code candidate area located at a position distant from the code candidate area succeeded in step SA5 from the decoding processing target, and is set in advance. Area-limited parameters can be set by the user. When set by the user, the input unit 43 can be used as a reception unit that accepts the setting of the area-limited parameter by the user. The area-limited parameters received via the input unit 43 can be stored in the storage device 50, and can be read from the storage device 50 and used when step SA9 is executed.

A specific example of the process in step SA9 will be described in detail. First, the processing unit 23 acquires the position of the code candidate region that has succeeded in the decoding process in step SA5. The position of the code candidate region that has succeeded in the decoding process can be obtained, for example, by the X coordinate and the Y coordinate on the scanned image 200. This coordinate may be the central portion of the code candidate region, a part of the peripheral portion, or the position of the center of gravity.

The processing unit 23 acquires the position of the code candidate region that has succeeded in the decoding process, and also acquires the region limitation parameter. After that, the processing unit 23 determines the decoding processing area (indicated by reference numeral 550 in FIG. 11) based on the position of the code candidate area and the area limitation parameter. FIG. 11 shows an example in which the code candidate area 503 is first selected as the reading target and the decoding process for the code candidate area 503 is successful. The position of the code candidate area 503 that has succeeded in the decoding process is acquired by the coordinates of the central portion 551 of the code candidate area 503. R1 is a region-limited parameter, and the region-limited parameter may be a predetermined coefficient. In this example, a circle having a radius R1 centered on the central portion 551 of the code candidate region 503 is determined as the decoding processing region 550. That is, since the radius of the decoding processing area 550 is used as the area limiting parameter, the decoding processing area 550 becomes wider as the area limiting parameter becomes larger, and conversely, the decoding processing area 550 becomes narrower as the area limiting parameter becomes smaller. The region-limited parameter may be the diameter of the circle. Further, the decoding processing area 550 may be an ellipse or an ellipse, or may be various figures such as a polygon, and even when these figures are used, the size of each figure and the area of each drawing A numerical value that defines the size can be used as an area-limited parameter, and depending on the figure, two or more area-limited parameters can be included. When the user sets or adjusts the area limitation parameter, it may be set or adjusted steplessly, or it may be set or adjusted stepwise.

The area-limited parameters can also be automatically set when the optical reader 1 is set. The tuning execution unit 24 acquires a scanned image 200 (shown in FIG. 8) including a plurality of codes from the imaging unit 5 at the time of setting the optical reading device 1, and a plurality of code candidate regions 501 to 513 of the acquired scanned image 200. The processing unit 23 executes the decoding process for (shown in FIG. 10), and the area-limited parameters so that the plurality of code candidate areas 501 to 503 for which the decoding process is successful are included in the decoding processing area 550 (shown in FIG. 11). Is set automatically. In this example, since the code candidate areas 501 to 503 are read targets, the decoding process for these code candidate areas 501 to 503 succeeds at the time of tuning, and the decoding process for other code candidate areas 504 to 513 does not succeed. .. When the decoding process succeeds in any one of the code candidate areas 501 to 503, the tuning execution unit 24 limits the area so that the decoding processing area 550 has a size including the other two code candidate areas. The parameters can be calculated and stored in the storage device 50.

When the process proceeds to step SA8 through step SA9 in the flowchart shown in FIG. 7, the processing unit 23 limits the code candidate area. When the decoding processing area 550 is determined as shown in FIG. 11, the code candidate areas 504, 505, 508 to 513 located outside the decoding processing area 550 are excluded from the decoding processing target. In FIG. 12, the code candidate areas excluded from the decoding processing target are erased, and only the code candidate areas 501 to 503, 506, and 507 to be decoded are shown. In other words, the processing unit 23 targets only the code candidate areas 501 to 503, 506, and 507 that overlap with the decoding processing area 550 for decoding processing. Further, the processing unit 23 does not have to set the code candidate areas 501 to 503 located in the decoding processing area 550 as the decoding processing target and the code candidate areas 504 to 513 located outside the decoding processing area 550 as the decoding processing target. .. Therefore, when the processing unit 23 succeeds in decoding any of the code candidate areas 501 to 503, the processing unit 23 generates a decoding result, and the code candidate area 504 at a position separated from the successful code candidate areas 501 to 503, 505, 508 to 513 are excluded from the decoding process.

After passing through step SA8, the process proceeds to step SA4. In step SA4 after passing through step SA8, any one of the code candidate areas 501, 502, 506, and 507 whose decoding process has not yet been executed from the code candidate areas 501 to 503, 506, and 507 limited in step SA8. Select one. At this time, the code candidate area can be selected based on the number of modules or the number of elements described above.

Assuming that the code candidate area 502 is selected in step SA4, the decoding process is executed for the code candidate area 502 in step SA5. After that, the process proceeds to step SA6, and if the decoding process is successful, the process proceeds to step SA7. In step SA7, it is determined whether or not the specified number of decoding processes are successful, but at this stage, only two decoding processes, the code candidate area 503 and the code candidate area 502, are successful, which is less than 3. , Step SA9.

In the second step SA9, the reading area is limited again. That is, since the decoding process of the code candidate area 502 was successful, the processing unit 23 acquires the position of the code candidate area 502 that has succeeded in the decoding process, and also acquires the area limitation parameter, and obtains the position and area of the code candidate area 502. The decoding processing region (indicated by reference numeral 552 in FIG. 13) is determined based on the limiting parameters. The position of the code candidate area 502 can be obtained by the coordinates of the central portion 553 of the code candidate area 502. A circle having a radius R2 centered on the central portion 553 of the code candidate region 502 can be determined as the decoding processing region 552. The radius R2 is a region-limited parameter and may be different from or the same as R1. After that, the process proceeds to step SA8, and the code candidate areas 501 to 503 in the decoding processing area 552 are targeted for decoding processing.

That is, when the processing unit 23 determines the decoding processing area 550 (shown in FIG. 11) in the first step SA9 and then succeeds in decoding the other code candidate area 502 located in the decoding processing area 550, the processing unit 23 said. A decoding processing area 552 (shown in FIG. 13) is newly determined based on the position of another code candidate area 502 and the area limiting parameter (R2), and is located within the newly determined decoding processing area 552. The code candidate areas 501 to 503 are targeted for decoding.

After that, the process proceeds to step SA4, and the reading area is limited for the third time. Since the decoding processing of the code candidate area 503 and the code candidate area 502 has been successful so far, the code candidate area 501 that has not yet been decoded in the decoding processing area 552 is selected as the decoding processing target. Then, the process proceeds to step SA5 to execute the decoding process on the code candidate region 501. If it is determined in step SA6 that the decoding process of the code candidate region 501 is successful, the process proceeds to step SA7. Since the decoding processing for the three code candidate areas 501 to 503 has been successful, it is determined as YES in step SA7, and the process proceeds to step SA10. In step SA10, the output unit 60 outputs the decoding result.

[Changes in area-limited parameters]
The region-limited parameter may be a fixed value, but it may be changed. For example, even when the work W to which the codes CD1 to CD3 of the same size are attached is imaged, if the work W and the imaging unit 5 are close to each other, the scanned image 200 is displayed as shown in FIG. When the codes CD1 to CD3 become large and the distance between the work W and the imaging unit 5 is long, the codes CD1 to CD3 become small on the read image 200 as shown in FIG. Therefore, when the area limitation parameter R is a fixed value, the size of the decoding processing area 550 may be too small in the case of the large codes CD1 to CD3 (shown in FIG. 14) on the scanned image 200, and the reading is performed. In the case of small codes CD1 to CD3 (shown in FIG. 15) on the image 200, the decoding processing area 550 is too large, and the code candidate area in which the code CD1 to CD3 is unlikely to exist is the decoding processing area 550. It is possible that it will enter.

On the other hand, in this example, since the area limitation parameter R can be changed according to the size of the codes CD1 to CD3 on the read image 200, it is related to the size of the codes CD1 to CD3 on the read image 200. It is possible to determine an appropriate decoding processing area. For example, as shown in FIG. 16, the processing unit 23 changes the region limitation parameter R so that the smaller the size of the codes CD1 to CD3 on the read image 200, the smaller the decoding processing region 550. Further, as shown in FIG. 17, the processing unit 23 changes the region limitation parameter R so that the larger the size of the codes CD1 to CD3 on the read image 200, the larger the decoding processing region 550.

More specifically, as the size of the code CD1 to CD3 on the read image 200, for example, the area of the code area, the size of the minimum module of the code, and the like can be mentioned, and obtained from these. The area limitation parameter R can be changed based on the size of the codes CD1 to CD3. The region-limited parameter R can also be calculated, for example, by multiplying the size of the codes CD1 to CD3 on the read image 200 by a coefficient. The coefficient may be determined in advance.

[Action and effect of the embodiment]
As described above, according to this embodiment, when the work W conveyed on the line is irradiated with light from the illumination unit 4, the light reflected by the work W is emitted by the imaging unit 5. Is received by. As a result, as shown in FIG. 8, the read image 200 including the work W and the codes CD1 to CD5 and the character strings L1 to L8 attached to the work W is generated. The processing unit 23 executes an extraction process on the scanned image 200, and extracts code candidate regions 501 to 513 as shown in FIG. As in this example, a plurality of code candidate areas 501 to 513 may be extracted, and in addition to the code candidate areas 501 to 505 containing the codes CD1 to CD5, the code not containing the codes CD1 to CD5 is included. Candidate regions 506 to 513 may be extracted.

When a plurality of code candidate areas 501 to 513 are extracted, the processing unit 23 sequentially executes decoding processing on the extracted plurality of code candidate areas 501 to 513. When the decoding process of the code candidate area 503 is successful as shown in FIG. 11, the code candidate areas 504, 505, 508 to 513 located at positions separated from the code candidate area 503 are excluded from the decoding target as shown in FIG. ..

That is, it is assumed that a plurality of codes CD1 to CD3 to be decoded are attached to the work W, for example, a plurality of codes CD1 to CD3 are printed on one label, which is the work W. A case where a plurality of codes CD1 to CD3 are printed near the peripheral edge of the work W, and the like can be mentioned. In any of these cases, there are many cases where a plurality of codes CD1 to CD3 are close to each other. Therefore, it is unlikely that the codes CD1 and CD2 to be decoded are present in a place separated from the code candidate area 503 in which the decoding process is successful, and it is unlikely that the codes CD1 and CD2 are present in the place. By excluding certain code candidate areas 504, 505, 508 to 513 from the decoding processing target, decoding processing is performed only for the code candidate areas 501 and 502 in which the coding processing target codes CD1 and CD2 are likely to exist. Can be executed.

The above embodiments are merely exemplary in all respects and should not be construed in a limited way. Furthermore, all modifications and modifications that fall within the equivalent scope of the claims are within the scope of the present invention.

As described above, the optical reading device according to the present invention can be used, for example, when reading a code such as a bar code or a two-dimensional code attached to a work.

1 Optical reader 4 Illumination unit 5 Imaging unit 23 Processing unit 24 Tuning execution unit 550 Decoding processing area CD1 to CD3 Codes to be decoded CD4, CD5 Codes not subject to decoding L1 to L8 Character strings

Claims (11)

It is a stationary optical reader that reads the code attached to the workpiece being conveyed on the line.
An illuminating unit for irradiating light toward the area through which the work passes,
An imaging unit that receives light emitted from the illumination unit and reflected from a region through which the work passes, and generates a scanned image of the region through which the work passes.
When a plurality of code candidate areas are extracted as a result of executing an extraction process for extracting a code candidate area from the read image generated by the imaging unit, the extracted plurality of code candidate areas are sequentially decoded. Is executed, and when the decoding process of any of the code candidate areas is successful, the decoding result is generated, and the code candidate area located at a position distant from the successful code candidate area is excluded from the decoding processing target.
An optical reader including an output unit that outputs the decoding result generated by the processing unit. In the optical reader according to claim 1,
The processing unit determines the decoding processing area based on the position of the code candidate area that has succeeded in the decoding processing and the preset area limitation parameter, and decodes the code candidate area located in the decoding processing area. Optical reader. In the optical reader according to claim 2,
The processing unit is an optical reading device that decodes the code candidate region that overlaps with the decoding processing region. In the optical reader according to claim 2 or 3.
The processing unit is an optical reading device that excludes the code candidate region located outside the decoding processing region from the decoding processing target. In the optical reading device according to any one of claims 2 to 4.
At the time of setting the optical reading device, a scanned image including a plurality of codes is acquired from the imaging unit, and the processing unit executes a decoding process on a plurality of code candidate regions of the acquired scanned image, and the decoding process is successful. An optical reading device including a tuning execution unit that automatically sets the area-limited parameters so that a plurality of code candidate areas are included in the decoding processing area. In the optical reading device according to any one of claims 2 to 5.
An optical reader provided with a reception unit that accepts user settings for the area-limited parameters. In the optical reading device according to any one of claims 2 to 6.
After the decoding processing area is determined, when the processing unit succeeds in decoding the other code candidate area located in the decoding processing area, the processing unit is based on the position of the other code candidate area and the area-limited parameter. An optical reader that newly determines a decoding processing area and targets a code candidate area located in the newly determined decoding processing area as a decoding processing target. In the optical reader according to any one of claims 2 to 7.
The processing unit is an optical reading device that changes the region-limited parameters according to the size of the code on the scanned image. In the optical reader according to claim 8,
The processing unit is an optical reading device that changes the region-limited parameters so that the smaller the size of the code on the scanned image, the smaller the decoding processing region. In the optical reader according to claim 8 or 9.
The processing unit is an optical reading device that changes the region-limited parameters so that the larger the size of the code on the scanned image, the larger the decoding processing region. In the optical reader according to any one of claims 1 to 10.
The processing unit is an optical reading device that calculates an estimated value of the number of modules or the number of elements for each of a plurality of extracted code candidate areas, and selects a code candidate area for executing decoding processing according to the calculated estimated value.

Images