JP2018136854A - Optical information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information reader that can read codes in a short time and enhances reading accuracy of the codes even if a photographic image includes low-resolution codes.SOLUTION: An optical information reader determines whether the size of a code corresponds to an extended interpolation processing object on the basis of information on the size of the code detected by a detection unit and a prestored determination reference value. If it is determined that the size of the code corresponds to an extended interpolation processing object, the optical information reader carries out extended interpolation processing of a partial image of the code of an image taken with an imaging unit.SELECTED DRAWING: Figure 18

Description

  The present invention relates to an optical information reader that optically reads information.

  In recent years, for example, so-called traceability that enables tracing of the distribution channel of goods from the manufacturing stage to the consumption stage or the disposal stage has been regarded as important, and code readers aimed at this traceability have become widespread. In addition to traceability, code readers are used in various fields.

  In general, 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 a code included in the obtained image by image processing, binarizes it, and performs decoding processing. It is configured to be able to read information and is also called an optical information reading device because it is a device that optically reads information.

  For example, the reading device disclosed in Patent Document 1 displays a rectangular frame at the center of the finder window on the screen when the user presses the shutter button when reading a two-dimensional code, and the frame is within this frame. When the user moves the two-dimensional code while looking at the finder window so that the two-dimensional code is positioned, the area within the frame is automatically enlarged and displayed.

JP 2000-322509 A

  By the way, it is considered that the reading accuracy can be improved by enlarging the two-dimensional code as described above. However, in Patent Document 1, two users are displayed so that the two-dimensional code is displayed in the frame of the finder window. Since the dimension code has to be moved, there is a problem that it takes time and is not easy to use. In addition, for example, it is difficult to use in applications such as reading a code attached to a workpiece that is continuously conveyed.

  Also, if the relative distance between the camera and the 2D code changes, the code size displayed on the screen will change, so each time the relative distance between the camera and the 2D code changes, specify the area to be enlarged. This has to be fixed, and this is also a factor that deteriorates usability.

  Therefore, a method of improving the resolution by enlarging and interpolating the entire image captured by the camera is conceivable. However, since the area to be enlarged becomes larger, it takes time to process, and as a result, the code reading time becomes longer. become.

  The present invention has been made in view of the above points, and an object of the present invention is to be able to read a code in a short time even when a low-resolution code is included in a captured image. And improving the code reading accuracy.

  In order to achieve the above object, in the present invention, an image pickup unit having an image pickup device for picking up an image of a code attached to a work, and information relating to the size of a code included in an image picked up by the image pickup unit are detected. And a size determination reference value that serves as a reference for determining whether or not the code is an object for enlargement interpolation processing based on information on the size of the code included in the image captured by the imaging unit. The code size is enlarged and interpolated based on the determination reference value storage unit, the information on the code size detected by the detection unit, and the size determination reference value stored in the determination reference value storage unit. It is determined whether or not the image is to be processed, and if it is determined that the size of the code is an object for enlargement interpolation processing, an enlargement of a partial image including the code among images captured by the imaging unit If the code size is determined not to be subject to enlargement interpolation processing, the enlargement interpolation processing unit configured not to perform enlargement interpolation processing of the partial image including the code, and the enlargement processing described above A decoding unit that decodes a code included in either the partial image that has been subjected to the expansion interpolation process by the interpolation processing unit or the partial image that has not been subjected to the expansion interpolation process by the expansion interpolation processing unit; be able to.

  According to this structure, the information regarding the magnitude | size of the code contained in the image imaged by the imaging part can be detected by the detection part. Information on the size of the code includes, for example, the dimensions of each part of the code, and, when the code is a two-dimensional code, the cell size, the size of the position detection pattern (finder pattern, alignment pattern), etc. Among them, the size of the code can be obtained by detecting any one or more by the detection unit.

  The enlargement interpolation processing unit determines that the code size is the object of enlargement interpolation processing based on the information related to the code size detected by the detection unit and the size determination reference value stored in the reference value storage unit. It can be determined whether or not there is. When it is determined that the size of the code is subject to enlargement interpolation processing, enlargement interpolation processing is performed on the partial image including the code among the images captured by the imaging unit. Compared to this, the processing time is short. Since the decoding unit can decode the code included in the partial image after the enlargement interpolation process, the code reading accuracy can be improved. On the other hand, when the size of the code is not the target for the enlargement interpolation process, the enlargement interpolation process for the partial image including the code is not performed, and thus unnecessary processing is not performed.

  In addition, the image captured by the imaging unit may include a code that is an object of enlargement interpolation processing and a code that is not an object of enlargement interpolation processing.

  In addition, the partial image on which the enlargement interpolation process is performed can be an image including a code area indicating a code and a peripheral area of the code area.

  Further, the code is a two-dimensional code, and the information related to the size of the code is arranged at a predetermined position of the two-dimensional code and may be a size of a position detection pattern for detecting the position of the two-dimensional code. it can.

  Further, the code is a two-dimensional code, and the information regarding the size of the code may be a cell size of the two-dimensional code or a pixel size constituting one cell of the two-dimensional code.

  Further, the image processing apparatus includes a blur correction unit that performs correction processing for correcting the blur of the code of the partial image that has been subjected to the magnification interpolation processing by the magnification interpolation processing unit, and the decoding unit performs correction processing by the blur correction unit. It can be configured to decode after it has been executed.

  Further, prior to decoding, the decoding unit can be configured to perform cell position estimation processing for estimating a cell position of a code based on a partial image that has been subjected to expansion interpolation processing by the expansion interpolation processing unit. .

  According to the present invention, a code can be read in a short time even when a low resolution code is included in a captured image, and the code reading accuracy can be increased.

It is a figure explaining the time of operation of an optical information reading device. It is a perspective view of an optical information reader. It is the figure which looked at the optical information reader from the illumination part side. It is a side view of an optical information reader. It is the figure which looked at the optical information reader from the display part side. It is a perspective view which shows the state which removed the polarizing filter attachment from the main body. It is a perspective view of a reflector. It is a front view of a reflector. It is a perspective view of a translucent panel. It is a front view of a translucent panel. It is a block diagram of an optical information reader. It is a block diagram of a computer. It is a user interface for displaying the storage contents of the parameter set storage unit. It is an interface for tuning during monitoring. This is a tuning interface in a state where focusing has been completed. It is an interface for tuning during brightness adjustment. It is a tuning interface that displays matching levels. It is a flowchart which shows the control content at the time of operation. It is a figure which shows typically the flow until it performs an expansion interpolation process from the imaged image. It is a figure which shows the alignment pattern of a 1st code | cord | chord. It is a determination flowchart of expansion interpolation processing. It is a flowchart which shows the control content at the time of operation | movement, and shows the case where Lanczos method is used for expansion interpolation processing.

  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 merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a diagram schematically showing the operation of the optical information reading apparatus 1 according to the embodiment of the present invention. In this example, a plurality of workpieces W are transported in the direction of arrow Y in FIG. 1 in a state where they are placed on the upper surface of the conveyor belt B for transport, and in the embodiment away from the workpieces W in the embodiment. Such an optical information reader 1 is installed. The optical information reading device 1 is a code reader configured to take an image of a code attached to a work W and decode information on the code included in the taken image to read information. The optical information reader 1 may be used by being fixed to a bracket or the like (not shown) so as not to move during its operation, or operated while being held and moved by a robot (not shown) or a user. May be. Further, the code of the workpiece W in a stationary state may be read by the optical information reading device 1. The time of operation is the time when the operation of sequentially reading the codes of the workpiece W conveyed by the conveyor belt conveyor B is performed.

  A code is attached to the upper surface of each workpiece W. The code includes both a barcode and a two-dimensional code. Examples of the two-dimensional code include a QR code (registered trademark), a micro QR code, a data matrix (Data matrix), a Veri code, an Aztec code, a PDF417, and a Maxi code. and so on. The two-dimensional code includes a stack type and a matrix type, but the present invention can be applied to any two-dimensional code. The code may be attached by printing or stamping directly on the workpiece W, or may be attached by printing on a label and then affixing to the workpiece W, and the means and method thereof are not limited.

  The optical information reader 1 is wired to the computer 100 and the programmable logic controller (PLC) 101 through signal lines 100a and 101a, respectively. However, the optical information reader 1 is not limited to this, and the optical information reader 1, the computer 100, and The PLC 101 may include a communication module so that the optical information reading apparatus 1 and the computer 100 and the PLC 101 are wirelessly connected. The PLC 101 is a control device for controlling the conveyor belt conveyor B and the optical information reading device 1 in sequence, 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.

  Further, the optical information reading apparatus 1 receives a reading start trigger signal that defines the code reading start timing from the PLC 101 via the signal line 101a during operation. Then, the optical information reading device 1 performs code imaging and decoding based on the reading start trigger signal. Thereafter, the decoded result is transmitted to the PLC 101 via the signal line 101a. As described above, when the optical information reader 1 is operated, the reading start trigger signal and the decoding result are output between the optical information reader 1 and the external control device such as the PLC 101 via the signal line 101a. Repeatedly. 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 information reading apparatus 1 and the PLC 101, or other signals (not shown). It may be done via a line. For example, a sensor for detecting the arrival of a workpiece and the optical information reader 1 may be directly connected, and a reading start trigger signal may be input from the sensor to the optical information reader 1.

[Overall Configuration of Optical Information Reading Apparatus 1]
As shown in FIGS. 2 to 6, the optical information reading device 1 includes a device main body 2 and a polarization filter attachment 3. The polarizing filter attachment 3 may be omitted. The apparatus main body 2 is provided with an illumination unit 4, an imaging unit 5, a display unit 6, a power connector 7, and a signal line connector 8. Further, the apparatus main body 2 is provided with an indicator 9 shown in FIG. 5, an aimer 10 shown in FIG. 3, a select button 11 shown in FIG. 5, and an enter button 12.

  In the description of this embodiment, the front, rear, upper, lower, left, and right surfaces of the optical information reader 1 are defined as shown in FIGS. 2 to 6, but this is only for convenience of description. The direction of use of the optical information reading device 1 is not limited. That is, as shown in FIG. 1, the optical information reader 1 is installed and used with its front face facing down, or the optical information reader 1 is placed and used with its front face facing up. Alternatively, it can be installed and used such that the front surface of the optical information reader 1 is inclined. Further, the left-right direction of the optical information reading apparatus 1 can also be referred to as the width direction.

  The apparatus main body 2 includes a casing 2a having a substantially rectangular box shape that is long in the vertical direction. Inside the casing 2a, a control unit 29, a decoding unit 31 and the like shown in FIG. 11 are provided. As shown in FIGS. 2 and 6, the polarizing filter attachment 3 is detachably attached to the front surface of the casing 2a. In addition, the front surface of the casing 2 a is illuminated with light toward the front of the optical information reader 1 to illuminate at least the code of the workpiece W, and the workpiece in front of the optical information reader 1. An imaging unit 5 that images at least a code of W is provided. Furthermore, the aimer 10 comprised with light-emitting bodies, such as a light emitting diode (LED), is provided in the front surface of the casing 2a. The aimer 10 is intended to indicate a standard of the imaging range by the imaging unit 5 and the optical axis of the illumination unit 4 by irradiating light toward the front of the optical information reader 1. The user can also install the optical information reader 1 with reference to the light emitted from the aimer 10.

  A display unit 6 is provided on the upper surface of the casing 2a. Further, a select button 11 and an enter button 12 are provided on the upper surface of the casing 2a and used when the optical information reader 1 is set. The select button 11 and the enter button 12 are connected to the control unit 29, and the control unit 29 can detect the operation state of the select button 11 and the enter button 12. The select button 11 is a button that is operated when selecting one of a plurality of options displayed on the display unit 6. The enter button 12 is a button operated when confirming the result selected by the select button 11.

  Further, indicators 9 are provided on both the left and right sides of the upper surface of the casing 2a. The indicator 9 is connected to the control unit 29 and can be formed of a light emitter such as a light emitting diode. The operating state of the optical information reader 1 can be notified to the outside by the lighting state of the indicator 9.

  On the lower surface of the casing 2a, a power connector 7 to which power wiring for supplying power to the optical information reader 1 is connected, and an Ethernet connector 8 for the signal lines 100a and 101a connected to the computer 100 and the PLC 101, and Is provided. Note that the Ethernet standard is an example, and a signal line of a standard other than the Ethernet standard can also be used.

[Configuration of Illumination Unit 4]
The illumination unit 4 includes a reflector 15 shown in FIGS. 7 and 8, and a plurality of first light emitting diodes 16 and a plurality of second light emitting diodes 17 shown in FIG. The first light-emitting diode 16 and the second light-emitting diode 17 are electrically connected to the control unit 29 and are individually controlled by the control unit 29 so that they can be turned on and off separately.

  As shown in FIGS. 7 and 8, the reflector 15 has a plate shape extending from the upper part to the lower part of the front surface of the optical information reader 1. Seven first light emitting diodes 16 and two second light emitting diodes 17 are provided, but the number of the first light emitting diodes 16 and the second light emitting diodes 17 is not limited thereto. The first light-emitting diode 16 and the second light-emitting diode 17 are arranged on the rear side of the reflector 15 and the optical axes are set so as to irradiate light forward. An imaging opening 15 a for allowing the imaging unit 5 to be exposed to the outside is formed at the intermediate portion in the vertical direction of the reflector 15. Aimer openings 15b for allowing the light of the aimer 10 to pass through are formed on the left and right sides of the imaging opening 15a in the reflector 15, respectively.

  In the lower portion of the reflector 15 than the imaging opening 15a, there are as many first holes 15c as the number of the first light emitting diodes 16 for allowing the light of the first light emitting diodes 16 to pass through and condensing the light forward. Only, that is, seven are formed. These first holes 15c have the same shape, and have a cone shape that gradually increases in diameter toward the front side. The inner surface of the first hole 15c is subjected to a plating process such as gold plating in order to increase the light reflectance.

  Of the seven first holes 15c, the four first holes 15c are arranged in the left-right direction (width direction) of the optical information reader 1. The remaining three first holes 15c have their centers positioned below the centers of the four first holes 15c, and of the four first holes 15c, the adjacent first holes 15c, It arrange | positions so that it may each be located between the centers of 15c. Accordingly, the seven first holes 15c can be arranged densely. The first light emitting diode 16 is disposed at the center of each first hole 15c.

  In the upper part of the reflector 15 above the imaging opening 15a, there are as many second holes 15d as the number of the second light-emitting diodes 17 for allowing the light of the second light-emitting diodes 17 to pass through and condensing the light forward. That is, seven are formed. The second holes 15d have the same shape as the first holes 15c, and the inner surface of the second holes 15d is subjected to the same plating treatment as the first holes 15c.

  Of the seven second holes 15d, four second holes 15d are arranged in the left-right direction (width direction) of the optical information reader 1. The remaining three second holes 15d have their centers positioned above the centers of the four second holes 15d, and of the four second holes 15d, adjacent second holes 15d, It arrange | positions so that it may each be located between the centers of 15d. Thereby, the seven second holes 15d can be arranged densely. The second light emitting diode 17 is disposed at the center of each second hole 15d.

  The illumination unit 4 may be configured separately from the imaging unit 5. In this case, the illumination unit 4 and the imaging unit 5 can be connected by wire or wirelessly. Further, the control unit 29 described later may be built in the illumination unit 4 or may be built in the imaging unit 5.

[Configuration of Polarizing Filter Attachment 3]
As shown in FIG. 6, the polarizing filter attachment 3 includes a frame member 20 and a translucent panel 21. The frame member 20 has an outer shape that substantially matches the outer shape of the front surface of the optical information reader 1. A translucent panel 21 is provided inside the frame member 20. The translucent panel 21 is formed so as to cover the first light emitting diode 16 and the second light emitting diode 17 of the illuminating unit 4 from the front and the imaging unit 5 from the front. As shown in FIGS. 9 and 10, the portion of the translucent panel 21 that covers the first light emitting diode 16, that is, the lower portion 21a is a portion that emits light from the first light emitting diode 16, and the lower portion 21a is This is a portion that is colorless and transparent and does not have a polarizing filter. On the other hand, the portion of the translucent panel 21 that covers the second light emitting diode 17, that is, the upper portion 21b is a portion that emits the light of the second light emitting diode 17, and the upper portion 21b is a portion provided with a polarizing filter. . Further, an intermediate portion 21 c between the lower portion 21 a and the upper portion 21 b in the light transmitting panel 21 is a portion that covers the imaging unit 5, and is a portion through which light incident on the imaging unit 5 is transmitted. The intermediate portion 21c is also a portion where a polarizing filter is provided. The polarization direction of the polarization filter of the upper portion 21b and the polarization direction of the polarization filter of the intermediate portion 21c are different from each other by 90 degrees, for example. 9 and 10, the portion where the polarizing filter is provided is shown lightly colored. 2, 3, and 6, the portion where the polarizing filter is provided is uncolored, but actually, it is lightly colored as in FIGS. 9 and 10.

  That is, the light emitted from the first light emitting diode 16 reaches the work W without passing through the polarizing filter, while the light emitted from the second light emitting diode 17 reaches the work W through the polarizing filter. Then, the reflected light from the workpiece W passes through the polarizing filter and enters the imaging unit 5.

  Therefore, even if the user does not remove the polarizing filter attachment 3, various works can be performed by electrically switching which of the first light-emitting diode 16 and the second light-emitting diode 17 the optical information reader 1 turns on. It is possible to easily cope with W. Specifically, for a work W (for example, a casting or the like) that is more advantageous without a polarizing filter, the first light emitting diode 16 is turned on and the second light emitting diode 17 is turned off. On the other hand, for a work W (for example, when a two-dimensional code is attached to a printed board, a milled surface, a black resin, etc.) that is more advantageous to have a polarizing filter, the first light emitting diode 16 is turned off and the second light emission The diode 17 is turned on.

[Configuration of Imaging Unit 5]
FIG. 11 is a block diagram showing a configuration of the optical information reading apparatus 1. As shown in FIG. 11, the imaging unit 5 includes an imaging element 5 a that images the code attached to the work W and illuminated by the illumination unit 4, an optical system 5 b that includes a lens and the like, and an autofocus mechanism ( AF mechanism) 5c. The light reflected from the portion of the workpiece W to which the code is attached enters the optical system 5b. The image sensor 5a is an image sensor composed of a light receiving element such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) that converts an image of a code obtained through the optical system 5b into an electrical signal. The image sensor 5 a is connected to the control unit 29, and the electric signal converted by the image sensor 5 a is input to the control unit 29. The AF mechanism 5c is a mechanism that performs focusing by changing the position and refractive index of the focusing lens among the lenses constituting the optical system 5b. The AF mechanism 5 c is also connected to the control unit 29 and controlled by the AF control unit 29 a of the control unit 29.

[Configuration of Display Unit 6]
The display part 6 consists of an organic EL display, a liquid crystal display, etc., for example. The display unit 6 is connected to the control unit 29 and can display, for example, a code imaged by the imaging unit 5, a character string that is a decoding result of the code, a reading success rate, a matching level, and the like. The read success rate is an average read success rate when the read process is executed a plurality of times. The matching level is a reading margin indicating the ease of reading a code that has been successfully decoded. This can be obtained from the number of error corrections generated at the time of decoding, and can be represented by a numerical value, 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 Detection Unit 30]
The optical information reading apparatus 1 includes a detection unit 30. The detection unit 30 is connected to the control unit 29. The detection unit 30 is a part for detecting information related to the size of the code included in the image captured by the image sensor 5a. The detection unit 30 may be configured to be able to detect the position on the image of the code included in the image captured by the image sensor 5a.

  For example, in the case of a two-dimensional code, information on the size of the code can be the size of a position detection pattern that is arranged at a predetermined position of the two-dimensional code and detects the position of the two-dimensional code. The position detection pattern can also be called a finder pattern or an alignment pattern. For example, in the case of a data matrix, an alignment pattern close to an L shape connecting the lower side of the code and one side can be used as information about the size of the code. In this case, when the detection unit 30 detects the length of one side of the alignment pattern, the size of the two-dimensional code can be estimated and obtained.

  In the case of a QR code, a finder pattern in which a small black square is arranged in a square frame, an alignment pattern having a similar shape arranged in the code, or the like is used as information about the size of the code. Can do. In this case, the detection unit 30 detects the size of the finder pattern and the alignment pattern, so that the size of the two-dimensional code can be estimated and obtained. The size of the finder pattern and the size of the alignment pattern can be obtained based on the outer dimensions (width, height, etc.), diagonal dimensions, area where the pattern is displayed, and the like. In the case of a QR code, since there are a plurality of finder patterns, the interval of the finder patterns can be used as information regarding the size of the code.

  Further, the information related to the code size can be, for example, the cell size of the two-dimensional code. The cell is the smallest white square (white cell) or black square (black cell) constituting the two-dimensional code. When obtaining information related to the size of the code, a white cell or a black cell may be used. In this case, the size of the two-dimensional code is estimated based on the size of the cell by estimating the size of the cell by the detection unit 30 detecting the length of one side of the cell, the diagonal size, and the area where the cell is displayed. It can be obtained by estimating the thickness.

  Further, the information regarding the code size may be the size (size) of the pixel on the image data constituting one cell of the two-dimensional code. That is, one cell is composed of a plurality of pixels arranged vertically and horizontally, and the size of the cell can be estimated by detecting the size of the pixels constituting one cell. The size of the two-dimensional code can be estimated and obtained based on the size of the cell.

  The information on the size of the code may be, for example, the outer dimensions (width, height, etc.) of the two-dimensional code, the diagonal dimension, the area where the two-dimensional code is displayed, and the like. As a result, the size of the code can be directly estimated and obtained.

  As for the position of the code, for example, the central portion of the code is estimated in the image picked up by the image pickup device 5a, and the X and Y coordinates of the central portion are obtained to identify the position of the code in the image. be able to.

[Configuration of Decoding Unit 31]
The optical information reading apparatus 1 includes a decoding unit 31 that decodes black and white binarized data. For the decoding, a table showing the contrast of the encoded data can be used. Further, the decoding unit 31 checks whether or not the decoded result is correct according to a predetermined check method. When an error is found in the data, correct data is calculated using an error correction function. The error correction function varies depending on the type of code.

  The decoding unit 31 is configured to decode the code included in the partial image that has been subjected to the enlargement interpolation process by the later-described enlargement interpolation processing unit 29d, and also to decode the code included in the image that has not been subjected to the enlargement interpolation process. Has been. That is, the decoding unit 31 decodes the code included in the partial image after the enlargement interpolation process when the enlargement interpolation processing unit 29d performs the enlargement interpolation process, and if the enlargement interpolation processing unit 29d does not perform the enlargement interpolation process, the enlargement processing is performed. A code included in a partial image that has not been interpolated is decoded. The decoding unit 31 writes the decoding result obtained by decoding the code in the storage device 35. The decoding unit 31 performs image processing such as various image processing filters on the image before decoding.

[Configuration of Communication Unit 32]
The optical information reading apparatus 1 has a communication unit 32. The communication unit 32 is a part that communicates with the computer 100 and the PLC 101. The communication unit 32 may include 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 and a wired LAN.

[Configuration of Control Unit 29]
A control unit 29 shown in FIG. 11 is a unit for controlling each part of the optical information reading apparatus 1, and can be constituted by a CPU, MPU, system LSI, DSP, dedicated hardware, or the like. The control unit 29 is equipped with various functions as will be described later, but these may be realized by a logic circuit or by executing software.

  The control unit 29 includes an AF control unit 29a, an imaging control unit 29b, a tuning unit 29c, an enlargement interpolation processing unit 29d, a UI management unit 29e, and a blur correction unit 29f. The AF control unit 29a is a unit that controls the AF mechanism 5c, and is configured so that the optical system 5b can be focused by conventionally known contrast AF and phase difference AF.

  The imaging control unit 29b is a unit that adjusts the gain, controls the light amount of the illumination unit 4, and controls the exposure time (shutter speed) of the imaging device 5a. Here, the gain is an amplification factor (also referred to as magnification) when the brightness of the image output from the image sensor 5a is amplified by digital image processing. About the light quantity of the illumination part 4, the 1st light emitting diode 16 and the 2nd light emitting diode 17 can be controlled separately, and can be changed. The gain, the light amount of the illumination unit 4 and the exposure time are the imaging conditions of the imaging unit 5.

  The tuning unit 29c is a unit that changes the imaging conditions such as the gain, the light amount of the illumination unit 4 and the exposure time, and the image processing conditions in the decoding unit 31. The image processing conditions in the decoding unit 31 include image processing filter coefficients (filter strength), switching of image processing filters when there are a plurality of image processing filters, combinations of different types of image processing filters, and the like. Appropriate imaging conditions and image processing conditions differ depending on the influence of external light on the workpiece W during conveyance and the color and material of the surface to which the code is attached. Therefore, the tuning unit 29c searches for more appropriate imaging conditions and image processing conditions, and sets processing by the AF control unit 29a, the imaging control unit 29b, and the decoding unit 31. Various conventionally known filters can be used as the image processing filter.

  The enlargement interpolation processing unit 29d determines that the code size is subject to enlargement interpolation processing based on the information on the code size detected by the detection unit 30 and the size determination reference value for determining the code size. If the code size is determined to be an object for enlargement interpolation processing, enlargement interpolation processing is performed on a partial image including the code among the images picked up by the image pickup unit 5. On the other hand, when it is determined that the size of the code is not an object for the enlargement interpolation process, the enlargement interpolation process is not performed. The magnitude determination reference value is stored in advance in a determination reference value storage unit 35 d provided in the storage device 35. Further, the enlargement interpolation process is an image enlargement process for improving resolution by interpolating pixels constituting an image, and examples thereof include a bilinear method, a bicubic method, and a Lanczos method. By appropriately performing the enlargement interpolation process, it is possible to improve the resolution of a small code included in the image captured by the imaging unit 5 and read it.

  The processing procedure by the enlargement interpolation processing unit 29d will be described in detail based on a flowchart described later, but the outline is as follows. First, the enlarged interpolation processing unit 29d estimates and obtains the code size based on the information related to the code size detected by the detection unit 30. The method for obtaining the code size is as described above. For example, the code size is estimated based on the size of the position detection pattern, finder pattern, etc. of the two-dimensional code, the cell size, the code size, and the like. The code size thus obtained is compared with the size determination reference value. If the code size is equal to or larger than the size determination reference value, the resolution can be decoded without performing the enlargement interpolation process. Therefore, it is determined that it is not a target for the enlargement interpolation process, and the enlargement interpolation process is not performed. On the other hand, if the size of the obtained code is compared with the size criterion value and the code size is below the size criterion value, there is a high possibility that decoding will fail at the same resolution. Enlargement interpolation processing is performed.

  The UI management unit 29e shown in FIG. 11 causes the display unit 6 to display various interfaces, codes captured by the imaging unit 5, a character string that is a decoding result of the code, a reading success rate, a matching level, and the like. 11 and the unit for receiving input from the enter button 12 and controlling the lighting of the indicator 9.

  The blur correction unit 29f is a part that executes a correction process for correcting the blur of the code of the partial image subjected to the expansion interpolation process by the expansion interpolation processing unit 29d. The processing by the blur correction unit 29f may be image processing that has been conventionally used to correct out-of-focus blur, or may be a method that substantially corrects blur by processing based on a dedicated algorithm. . In the case of image processing, for example, processing (filter processing) by applying a low-pass filter (LPF) can be mentioned. Further, as processing based on the algorithm, for example, when performing averaging processing of a plurality of pixels as preprocessing when performing binarization of an image at the time of decoding, if the image is not blurred, the pixel to be averaged On the other hand, when the image is blurred, there can be mentioned processing for deliberately reducing the number of pixels to be averaged. Thereby, it is possible to prevent blur information from being mixed and to substantially correct blur. A plurality of correction processes for correcting the correction may be executed in combination.

  The blur correction is effective when the Lanczos method is used as the enlargement interpolation process. This is because when the Lanczos method is used, the image after enlargement becomes an image similar to out-of-focus.

[Configuration of Storage Device 35]
The storage device 35 includes a memory, a hard disk, and the like. The storage device 35 is provided with a decoding result storage unit 35a, an image data storage unit 35b, a parameter set storage unit 35c, and a determination reference value storage unit 35d. The decoding result storage unit 35 a is a part that stores a decoding result that is a result of decoding by the decoding unit 31. The image data storage unit 35b is a part that stores an image captured by the image sensor 5a.

  The determination reference value storage unit 35d is a size determination criterion that serves as a reference for determining whether or not the code is an object for enlargement interpolation processing based on information regarding the size of the code included in the image captured by the image sensor 5a. This is the part that stores the value. For example, if the code is a data matrix, the shorter the length of one side of the alignment pattern, the smaller the code size in the captured image, so that decoding by the decoding unit 31 becomes difficult. Therefore, a lower limit value of the length of one side of the alignment pattern that can be decoded with high accuracy by the decoding unit 31 is obtained in advance by experiments or the like, and this length is used as a size determination reference value as a determination reference value storage unit. 35d can be stored. Therefore, if the length of one side of the alignment pattern is equal to or larger than the size determination reference value, the decoding unit 31 can perform decoding with high accuracy, while the length of one side of the alignment pattern is the size determination reference value. If it is less, it becomes difficult to perform the decoding by the decoding unit 31 with high accuracy.

  Based on such a concept, size determination reference values for various codes can be obtained and stored in the determination reference value storage unit 35d. For example, in the case of a QR code, the smaller the size (outer dimensions, displayed area, etc.) of the finder pattern, alignment pattern, etc., the smaller the code size in the captured image, and the decoding unit Therefore, the lower limit value of the size of a finder pattern, alignment pattern, or the like that can be decoded by the decoding unit 31 with high accuracy is obtained in advance through experiments or the like. It can memorize | store in the determination reference value memory | storage part 35d as a magnitude | size determination reference value.

  The same applies to the cell size and the pixel size. The smaller the cell size and the pixel size, the smaller the code size in the captured image, and the decoding by the decoding unit 31 becomes difficult. A lower limit value of a cell size and a pixel size that can be decoded with high accuracy by the decoding unit 31 is obtained in advance by experiments or the like, and this size is stored in the determination reference value storage unit 35d as a size determination reference value. be able to.

  In addition, the size determination reference value is similarly obtained for the outer dimensions (width, height, etc.) of the two-dimensional code, the diagonal dimension, the area where the two-dimensional code is displayed, etc., and stored in the determination reference value storage unit 35d. can do.

  The parameter set storage unit 35c shown in FIG. 11 is a part that stores setting information set by a setting device such as the computer 100, setting information set by the select button 11 and the enter button 12, and the like. In the parameter set storage unit 35c, at least one of the imaging conditions of the imaging unit 5 (gain, light amount of the illumination unit 4 and exposure time, etc.) and image processing conditions (type of image processing filter, etc.) of the decoding unit 31 is stored. A parameter set including a plurality of parameters to be configured can be stored. In this embodiment, the parameters constituting the imaging conditions of the imaging unit 5 and the parameters constituting the image processing conditions in the decoding unit 31 so as to be displayed as the banks 1 to 5 in the parameter set display format 46 shown in FIG. Can be stored in a plurality of parameter sets. Different parameter sets can be stored in the banks 1 to 5, for example, when the work W is different. The number of banks can be set arbitrarily.

  The optical information reading apparatus 1 is configured to be able to switch from one parameter set to another parameter set among a plurality of parameter sets stored in the parameter set storage unit 35c. Switching between parameter sets can be performed by the user or can be configured to be performed by the PLC 101. When the user switches the parameter set, the parameter set switching unit 46b incorporated in the user interface shown in FIG. 13 may be operated. By setting the parameter set switching unit 46b to “valid”, the parameter set of the bank is used during the operation of the optical information reading apparatus 1, and by setting the parameter set switching unit 46b to “invalid” Are not used when the optical information reader 1 is operated. That is, the parameter set switching unit 46b is for switching from one parameter set to another parameter set. The form of the parameter set switching unit 46b is not limited to the form shown in the figure, and various forms such as buttons can be used.

  Here, the parameter set 46 shown in FIG. 13 will be supplementarily described. In FIG. 13, as “common” parameters, “alternate” (a function to try imaging / decoding while automatically switching a plurality of registered parameter sets) and “in-bank retry count” (imaging / decoding performed before alternate) are performed. Frequency). The “code” parameter includes “detailed code setting” (code type to be read), “digit-limited output function” (function to limit the output digits of read data), and the like. As the “illumination” parameters, “use of internal illumination” (whether or not illumination used in the optical information reader 1 is used), “use of external illumination” (externally attached to the optical information reader 1) And “polarization filter” (whether or not to enable a polarization mode to be described later). As the “imaging” parameters, “exposure time” (exposure time μs during imaging), “gain” (gain during imaging), and “contrast adjustment method” (the above-mentioned “HDR”, “super HDR”, “standard characteristics”) And “contrast enhancement characteristics”). Further, as the “image processing filter” parameter, “first image processing filter” (the type of image filter to be executed first), “first image processing filter number” (number of times to execute the first image filter), and the like. include.

  In FIG. 13, in the banks 1 to 5, the above-mentioned “contrast adjustment method” is set to “HDR”, “contrast enhancement”, “standard”, “super HDR”, and “HDR”, respectively. In the “alternate” described above, only bank 1 and bank 2 are “valid”. Therefore, the optical information reading device 1 first attempts decoding using the contrast adjustment method “HDR” which is the setting content of the bank 1. If the decoding fails, the setting contents of the bank 1 are switched to the setting contents of the bank 2, and the decoding is attempted using the contrast adjustment method “contrast enhancement” which is the setting contents of the bank 2. In short, by trying to decode while automatically switching a plurality of registered parameter sets, it is possible to try decoding while automatically switching the contrast adjustment method, and thus the reading accuracy can be improved.

  Various methods can be considered for the order of the “alternate” described above. For example, as described above, decoding may be attempted by switching banks sequentially from the first. In addition, for example, priority may be given to banks that have been successfully read. Specifically, the bank that has been successfully read may be preferentially set at the next reading. Thereby, for example, when the printing state changes in lot units, the reading tact can be shortened.

[Configuration of Computer 100]
As shown in a block diagram in FIG. 12, the computer 100 includes a CPU 40, a storage device 41, a display unit 42, an input unit 43, and a communication unit 44. By downsizing the optical information reader 1, it becomes difficult to perform all settings of the optical information reader 1 with only the display unit 6 and the buttons 11, 12 of the optical information reader 1. Alternatively, a computer 100 may be prepared separately from the optical information reader 1, and various settings of the optical information reader 1 may be performed by the computer 100 to transfer the setting information to the optical information reader 1.

  Alternatively, the computer 100 and the optical information reading device 1 may be connected so as to be capable of bidirectional communication, and the computer 100 may perform a part of the processing of the optical information reading device 1 described above. In this case, a part of the computer 100 becomes a part of the components of the optical information reading apparatus 1.

  The CPU 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 includes a memory, a hard disk, and the like. The display unit 42 is composed of, for example, a liquid crystal display. The input unit 43 includes a keyboard, a mouse, a touch sensor, and the like. The communication unit 44 is a part that communicates with the optical information reading apparatus 1. The communication unit 44 may include an I / O unit connected to the optical information reading device 1, a serial communication unit such as RS232C, and a network communication unit such as a wireless LAN or a wired LAN.

  The CPU 40 includes a calculation unit 40a that performs various calculations. The calculation unit 40a is provided with a UI control unit 40b and a setting unit 40c. The UI control unit 40b includes a user interface for setting the imaging conditions of the imaging unit 5 of the optical information reading device 1, the image processing conditions in the decoding unit 31, the decoding result output from the optical information reading device 1, A user interface for displaying image data and the like is generated and displayed on the display unit 42. The display unit 42 may constitute a part of the optical information reading device 1. The setting unit 40 c sets the imaging conditions of the imaging unit 5 and the image processing conditions in the decoding unit 31. The UI control unit 40b and the setting unit 40c may be provided in the optical information reading device 1. Further, the UI control unit 40b or the setting unit 40c may be responsible for all or part of the functions (bank setting, etc.) of the processing unit 29d.

  The storage device 41 includes a decoding result storage unit 41a, an image data storage unit 41b, a parameter set storage unit 41c, and a determination reference value storage unit 41d. The storage units 41a to 41d store the same information as the decoding result storage unit 35a, the image data storage unit 35b, the parameter set storage unit 35c, and the determination reference value storage unit 35d of the optical information reader 1. It is.

[Processes executed at the time of setting]
Next, the setting of the optical information reading apparatus 1 performed as an operation preparation stage before operating the optical information reading apparatus 1 configured as described above will be described. During this setting, a tuning process is performed by the tuning unit 29c. The steps described below may be executed by the control unit 29 of the optical information reader 1 or may be executed while the CPU 40 of the computer 100 controls each part of the optical information reader 1. In this embodiment, since the tuning unit 29c is provided in the control unit 29 of the optical information reader 1, first, the control unit 29 executes the tuning process, and after the tuning process is completed, the optical information reading is performed. Move to operation of device 1.

  In the tuning process, the UI control unit 40b of the computer 100 causes the display unit 42 of the computer 100 to display a user interface 45 as shown in FIG. A user interface 45 shown in FIG. 14 is a tuning interface. The tuning interface 45 incorporates a monitor button 45a, an autofocus button 45b, a tuning button 45c, and an image display area 45d.

  When the user operates the input unit 43 of the computer 100 and clicks the monitor button 45a, an image currently captured by the imaging unit 5 of the optical information reader 1 is displayed in the image display region 45d. This image display region The image displayed in 45d is updated almost in real time. The user moves the workpiece W so that the code C of the workpiece W is displayed in the image display area 45d while viewing the image of the tuning interface 45.

  Thereafter, when the user clicks the autofocus button 45b of the tuning interface 45, the AF mechanism 5c of the imaging unit 5 is controlled by the AF control unit 29a to focus on the code C as shown in FIG. Thereby, it can be confirmed that the code C is in the image display area 45d.

  When the user clicks the tuning button 45c of the tuning interface 45, the tuning process is executed. The tuning process can also be executed by operating the select button 11 and the enter button 12 of the optical information reader 1. In the tuning process, first, the tuning unit 29c executes a code search. For example, the tuning unit 29c causes the imaging control unit 29b to perform imaging to acquire image data, and causes the decoding unit 31 to search for a two-dimensional code based on the image data. The imaging control unit 29b reads from the parameter set storage unit 35c reading conditions that are valid at that time (imaging conditions for the imaging device 5a, illumination conditions for the illumination unit 4, image processing conditions for the decoding unit 31, etc.), Each part, such as the illumination part 4, the image pick-up element 5a, and the decoding part 31, is set. The decoding unit 31 searches for the two-dimensional code from the image data acquired by the image sensor 5a and stored in the image data storage unit 35b, and outputs the search result to the tuning unit 29c. The illumination condition includes information indicating whether the polarization mode is enabled or the non-polarization mode is enabled. The polarization mode is a mode in which the first light emitting diode 16 is turned off and the second light emitting diode 17 is turned on, and the non-polarization mode is a mode in which the first light emitting diode 16 is turned on and the second light emitting diode 17 is turned off. .

  Then, the tuning unit 29 c performs rough adjustment on the brightness of the illumination unit 4. In the present embodiment, coarse adjustment is performed on the brightness of the illumination unit 4, a better reading result is selected from the polarization mode and the non-polarization mode, and the brightness is finely adjusted for the selected illumination mode. And When the brightness is adjusted, a tuning interface 45 as shown in FIG. 16 is displayed.

  Thereafter, the tuning unit 29c switches to an illumination mode different from the illumination mode set in the illumination unit 4 at that time. In other words, the tuning unit 29c switches to the non-polarization mode if the polarization mode is set in the illumination unit 4, and switches to the polarization mode if the non-polarization mode is set.

  Thereafter, the tuning unit 29c performs a two-dimensional code reading test. For example, the tuning unit 29c causes the imaging control unit 29b to perform imaging to acquire image data, and causes the decoding unit 31 to search for a two-dimensional code. Here, only the illumination mode is changed among the reading conditions that are valid at that time. The decoding unit 31 searches the two-dimensional code for the image data acquired by the image sensor 5a and stored in the image data storage unit 35b, and outputs the search result to the tuning unit 29c.

  The tuning unit 29c determines whether the reading test is successful based on the search result of the decoding unit 31. When the reading test is executed a plurality of times while changing the reading conditions, it is determined whether or not the reading is successful even once.

  If the reading is successful, the tuning unit 29c assumes that there are a total of N (eg, 256) brightness levels for each illumination mode, and n (eg, 27) brightnesses out of the N brightness levels. Run a read test for each level. As a result, a reading result for each of the 27 brightness levels is obtained for the polarization mode, and a reading result for each of the 27 brightness levels is obtained for the non-polarization mode. The brightness level to be tuned may be different between the polarization mode and the non-polarization mode.

  By passing through the polarizing filter, the brightness of the polarization mode is about half that of the non-polarization mode. Therefore, N / 2 levels or more out of N may be assigned to the brightness level in the polarization mode, and less than N / 2 levels out of N may be assigned to the brightness level in the non-polarization mode. As a result, the time required for the reading test can be reduced by half compared to a case where all N levels are searched exhaustively. Of course, if there is no request for time reduction, all N levels may be exhaustively searched in each illumination mode.

  Then, the tuning unit 29c determines an illumination mode with a better decoding result among the plurality of illumination modes. For example, the tuning unit 29c compares the number of successful reading tests in each illumination mode, and determines a more successful illumination mode. For example, if 27 reading tests are successful in the polarization mode and 10 reading tests are successful in the non-polarization mode, the polarization mode is selected. If the number of successful polarization modes is the same as the number of successful non-polarization modes, or if there is no significant difference between the two, the tuning unit 29c may select the non-polarization mode. This is because the non-polarization mode is more advantageous in terms of power consumption and heat when realizing the same brightness. However, in an environment where disturbance light or the like is likely to be generated, the polarization mode can cut a part of the disturbance light with the deflection filter, so that the reading success rate is increased. Therefore, in such a case, the polarization mode may be preferentially adopted. Here, the number of successes of the reading test is compared, but the tuning unit 29c may compare the reading success rate or may calculate and compare the matching level indicating the readability.

  The matching level can be displayed, for example, in a matching level display area 45e incorporated in the tuning interface 45 as shown in FIG. In the matching level display area 45e, the matching level is displayed in a graph format. The horizontal axis indicates the brightness. The vertical axis indicates the matching level at a specific brightness. The matching level can be indicated by a value from 0 to 100, for example, and the higher the numerical value, the higher the matching level.

  Further, the tuning unit 29c determines a result of coarse brightness adjustment. For example, assume that the brightness level can be changed from 0 to 255. A reading test is performed for n brightness levels. Then, the tuning unit 29c calculates the brightness (eg, average value) that is the center of the m brightness levels that have been successfully read. In this way, rough brightness adjustment is performed.

  By the way, if the reading test is not successful in the other illumination mode, the tuning unit 29c omits or cancels the reading condition search process in the other illumination mode, selects the original illumination mode, and performs tuning. The unit 29c performs a reading test for each of n (e.g., 27) brightness levels for the original illumination mode. As a result, a reading result for each of the 27 brightnesses is obtained for the polarization mode or the non-polarization mode which is the original illumination mode. Thereafter, the tuning unit 29c calculates a brightness level (eg, average value) that is the center of the m levels that have been successfully read.

  When the coarse brightness adjustment is completed, fine brightness adjustment is executed. The tuning unit 29c varies the brightness around the brightness level determined by the coarse adjustment, and searches and determines the brightness level at which the reading success rate or the matching level becomes the highest.

  Thereafter, the tuning unit 29c executes the reading test again. The tuning unit 29c determines whether the reading success rate or the number of successes exceeds a threshold value. If the reading success rate or the number of successes exceeds the threshold value, the tuning unit 29c ends the tuning process. On the other hand, if the reading success rate or the number of successes does not exceed the threshold value, the tuning unit 29c again changes the reading conditions other than the brightness (eg, exposure time, gain, image processing filter coefficient, etc.) and reads the reading value. It is determined whether the success rate or the number of successes exceeds a threshold value.

  The exposure time, gain, coefficient of the image processing filter, etc., that is, the parameters constituting the imaging conditions of the imaging unit 5 and the parameters constituting the image processing conditions in the decoding unit 31 are set in the user interface shown in FIG. This parameter set is stored in the parameter set storage unit 35c.

[Processes executed during operation]
When the setting of the optical information reader 1 is completed as described above and the preparation for operation of the optical information reader 1 is completed, the optical information reader 1 can be operated. When the optical information reading apparatus 1 is operated, control is basically performed according to the flowchart shown in FIG.

  In step SA1 in the flowchart of FIG. 18, the control unit 29 causes the imaging unit 5 to image the workpiece W. The image A obtained at this time is schematically shown in FIG. The largest rectangle displayed in the image A indicates the outer shape of the imaged work W. A first mark M1 and a second mark M2 that are not codes are attached to the surface of the workpiece W. The first mark M1 and the second mark M2 have a shape close to a square, and the first mark M1 is attached smaller than the second mark M2.

  A first code C1 and a second code C2 are also attached to the surface of the workpiece W. This example shows a case where the first code C1 and the second code C2 are data matrices. The data matrix has an L-shaped alignment pattern connecting the lower side of the code and one side, and in the case of the first code C1, the data matrix has an alignment pattern AP1 as shown by a thick line in FIG. ing. Similarly, the second code C2 has an alignment pattern AP2 (shown in FIG. 19).

  After acquiring an image in step SA1 in the flowchart of FIG. 18, the process proceeds to step SA2 to extract code area candidates. The code area candidate is an area where it is estimated that a code (C1, C2) to be read exists in the image acquired in step SA1. 19 schematically, in this example, since the first code C1 and the second code C2 to be read are data matrices, in step SA2, the substantially L-shape similar to the alignment pattern and the alignment pattern is obtained. Is searched for in the image acquired in step SA1.

  As shown in the upper right diagram in FIG. 19, since the first mark M1 and the second mark M2 are square, there are two shapes E1 (indicated by bold lines) similar to the alignment pattern at the periphery of the first mark M1. There are two shapes E2 (indicated by bold lines) that exist and are similar to the alignment pattern at the periphery of the second mark M2. Therefore, in the step SA2, the area where the first mark M1 and the second mark M2 exist is also extracted as a code area candidate. In addition, the outer shape of the workpiece W may be extracted as a code area candidate.

  Further, as shown in the upper right diagram in FIG. 19, since the alignment patterns AP1 and AP2 of the first code C1 and the second code C2 exist in the image acquired in step SA1, the first code C1 and An area where the second code C2 exists is extracted as a code area candidate. The searched alignment patterns AP1 and AP2 are indicated by bold lines.

  Thereafter, the process proceeds to step SA3 in the flowchart of FIG. 18 to select an undecoded area. The undecoded area is an area that has not been decoded in step SA6, which will be described later, in the area extracted as the code area candidate in step SA3. In the first flow, since the decoding process is not executed for all the code area candidates, the process proceeds to step SA4 as it is. If a plurality of code area candidates are extracted, the order of decoding processing is determined in step SA3. When determining the order of performing the decoding process, the decoding process may be performed in ascending order of the contrast of the code area candidates, or the decoding process may be performed in the order of increasing the contrast of the code area candidates. Further, the decoding process may be performed in descending order of the alignment pattern (or similar shape of the alignment pattern) in the code area candidate, or the decoding process may be performed in ascending order of the alignment pattern (or similar shape of the alignment pattern) in the code area candidate. Good to do.

  In step SA4, it is determined whether or not the code area extracted in step SA2 needs to be subjected to enlargement interpolation. Specifically, first, the detection unit 30 recognizes the alignment patterns AP1 and AP2 in the code region candidates and the similar shapes E1 and E2 of the alignment pattern as information on the size of the code, and based on the information, As described above, the code size is estimated and obtained. Here, since the first mark M1 and the second mark M2 have similar shapes E1 and E2 of the alignment pattern, the size is estimated on the assumption that the first mark M1 and the second mark M2 are also codes. And get. In step SA4, the size determination reference value stored in advance in the determination reference value storage unit 35d is obtained. Then, based on the information on the size of the code detected by the detection unit 30 and the size determination reference value, it is determined whether or not the size of the code is an object for enlargement interpolation processing.

  FIG. 21 shows a flowchart for determining whether or not an object is an enlargement interpolation process target. In step SB1, the positions of alignment patterns AP1 and AP2 and similar shapes E1 and E2 of the alignment pattern in the code area candidate are specified. This is performed by the detection unit 30. In the subsequent step SB2, the length (x) of one side of the alignment patterns AP1 and AP2 in the code area candidate and the similar shapes E1 and E2 of the alignment pattern is measured. The length (x) can also be displayed by the number of pixels.

  In step SB3, it is determined whether or not the length (x) is shorter than the size determination reference value. If the length (x) is shorter than the size determination reference value, the process proceeds to step SB4, that is, step SA5 of the flowchart shown in FIG. On the other hand, if the length (x) is greater than or equal to the size determination reference value, the process proceeds to step SB5, that is, step SA6 of the flowchart shown in FIG.

  Referring to the upper right diagram in FIG. 19, the first code C1 is larger than the second code C2, and one side of the alignment pattern AP1 is sufficiently long, so that it can be decoded without performing an enlargement interpolation process. Advances to step SA6. Further, in the same figure, since the second mark M2 is larger than the first mark M1 and the second code C2 and the alignment pattern similar shape E2 is large, it is determined that one side is long and the enlargement interpolation process is not required. The process proceeds to step SA6.

  On the other hand, in the figure, since the similar shape E1 of the alignment pattern of the first mark M1 and the alignment pattern AP2 of the second code C2 are short, it is estimated that the decoding is difficult unless the enlargement interpolation process is performed. Proceed to SA5. The estimation of whether or not decoding is difficult can also be performed based on, for example, the similar shape E1 of the alignment pattern or the line width of the alignment pattern AP2.

  In step SA5 of the flowchart shown in FIG. As shown in the lower left diagram of FIG. 19, the code region D in which the second code C2 exists, that is, the interpolation process of the partial image including the second code C2 among the images captured by the imaging unit 5 is performed. Since it can be performed, the processing time can be shortened compared with the case where the entire image is subjected to enlargement interpolation. The code area for performing the expansion interpolation process, that is, the partial image for performing the expansion interpolation process may be an image including a code area indicating a code and a peripheral area of the code area. For example, the partial image to be subjected to the enlargement interpolation process may be a rectangle whose length and width are four times the code length. In this way, by setting a wide partial image to be subjected to the enlargement interpolation process, the detection of the code position by the detection unit 30 can be coarse, so that the processing time can be shortened.

  Next, the process proceeds to step SA6, the code included in the code area D subjected to the enlargement interpolation process is decoded, and then the process proceeds to step SA7 to determine whether or not the reading is successful. If the reading is successful in step SA7, this flow is temporarily terminated.

  On the other hand, if the reading is not successful in step SA7, the process returns to step SA3 to select an area that has not been decoded yet. For example, when the area where the first mark M1 is present is decoded, the first mark M1 is not a code, so reading fails in step SA6, NO is determined in step SA7, and the process returns to step SA3. It will be. Further, even when the second mark M2 is decoded, reading fails, so that NO is determined in step SA7 and the process returns to step SA3. Further, the first code C1 is successfully read without performing the enlargement interpolation process.

  When performing decoding processing in step SA6, the decoding unit 31 performs cell position estimation processing prior to decoding. As schematically shown in FIG. 20, the cell position estimation process defines the cell boundaries by drawing the virtual lines L1 and L2 vertically and horizontally so as to form a grid with reference to the alignment pattern AP1. . After the white cell or black cell exists at the estimated cell position, or after binarization, the decoding unit 31 can determine the pattern and perform the decoding process. Since the cell position can be estimated based on the alignment pattern AP1, the estimation result becomes accurate. In FIG. 20, the cell position estimation process is performed using the alignment pattern AP1 that is not subjected to the expansion interpolation process. However, the present invention is not limited to this. For example, the cell position estimation process is performed using the expanded alignment pattern AP2. May be performed.

  In the case of a QR code or the like, basically, after determining whether or not enlargement interpolation processing is necessary based on the above-described control content, only necessary partial images can be subjected to enlargement interpolation processing and then decoding processing can be performed.

[Process when Lanczos method is used]
The Lanczos method can be used for the enlargement interpolation process. The case where the Lanczos method is used will be described based on the flowchart shown in FIG. When the Lanczos method is used for the enlargement interpolation process, the enlarged image becomes an image similar to the out-of-focus image, so that the blur correction process is performed.

  Steps SC1 to SC4 in the flowchart shown in FIG. 22 are the same as steps SA1 to SA4 in the flowchart shown in FIG. If it is determined in step SC4 in the flowchart shown in FIG. 22 that the enlargement interpolation process is necessary, the process proceeds to step SC5, and the same process as step SA5 in the flowchart shown in FIG. 18 is performed. Then, the process proceeds to step SC6 and decoding with blur correction is performed. In step SC6, the blur of the image subjected to the enlargement interpolation process in step SC5 is reduced by the blur correction process, and then the same decoding process as in step SA6 of the flowchart shown in FIG. 18 is performed. On the other hand, if it is determined in step SC4 that the enlargement interpolation process is unnecessary, the process proceeds to step SC8, and the same decoding process as in step SA6 in the flowchart shown in FIG. 18 is performed. Step SC7 is the same as step SA7 in the flowchart shown in FIG.

[Polarization filter attachment presence / absence detection method]
As a method for automatically detecting whether or not a detachable member such as the polarizing filter attachment 3 is attached to the main body, a method using, for example, a mechanical switch or an electrical contact is generally known. However, in these cases, there is a demerit that the structure becomes complicated.

  In this embodiment, it is configured such that the presence or absence of the polarizing filter attachment 3 can be automatically detected without using a mechanical switch or an electrical contact. Specifically, the amount of light applied is reduced by half when light passes through the polarizing filter, and the amount of light is reduced by half when transmitted through the polarizing filter when receiving light. The presence or absence of the polarizing filter attachment 3 is automatically detected by the wear.

  That is, first, the imaging unit 5 is caused to image in a state where the first light emitting diode 16 is turned on and the second light emitting diode 17 is turned off. Thereafter, the first light emitting diode 16 is turned off and the second light emitting diode 17 is turned on to cause the imaging unit 5 to pick up an image. Either may be the first in this order. Thereafter, if the brightness of the two images is compared and approximately the same, it is determined that the polarizing filter attachment 3 is not attached. On the other hand, if the brightness of one image is about twice (or about half) the brightness of the other image, it is determined that the polarizing filter attachment 3 is attached.

  That is, an image obtained by emitting light from a light emitting body arranged so as to pass through the polarizing filter of the polarizing filter attachment 3 and making a light emitting body arranged so as not to pass through the polarizing filter not emit light, Comparison of brightness with an image obtained by emitting light from a light emitter arranged so as to pass through the polarization filter of the polarization filter attachment 3 and emitting light from a light emitter arranged so as not to pass through the polarization filter A comparison unit is provided. And the presence or absence of the polarization filter attachment 3 can be automatically detected based on the comparison result of two images by this comparison part.

[Effects of Embodiment]
As described above, according to the optical information reading device 1 according to this embodiment, the detection unit 30 can detect information related to the size of the code included in the image captured by the image sensor 5a. Thereby, the size of the code can be estimated and obtained.

  Then, the enlargement interpolation processing unit 29d expands the code size based on the information on the code size detected by the detection unit 30 and the size determination reference value stored in the reference value storage unit 35d. It can be determined whether or not it is a processing target. When it is determined that the size of the code is subject to enlargement interpolation processing, the enlargement interpolation processing is performed on the partial image including the code among the images captured by the image sensor 5a, and thus the entire image is subjected to enlargement interpolation. Compared with, processing time is short. Since the decoding unit can decode the code included in the partial image after the enlargement interpolation process, the code reading accuracy can be improved. On the other hand, when the size of the code is not the target for the enlargement interpolation process, the enlargement interpolation process is not performed, and therefore unnecessary processing is not performed.

  Therefore, even when a low resolution code is included in the captured image, the code can be read in a short time and the code reading accuracy can be improved.

  In the above embodiment, it is determined whether or not enlargement interpolation is necessary when the optical information reader 1 is operated. However, the present invention is not limited to this, and a tuning process at the time of setting the optical information reader 1 is performed. When performing, it may be determined whether or not enlargement interpolation is necessary.

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

DESCRIPTION OF SYMBOLS 1 Optical information reader 4 Illumination part 5 Image pick-up part 5a Image pick-up element 29 Control unit 29d Enlargement interpolation process part 30 Detection part 31 Decoding part 35 Memory | storage device 35d Determination reference value memory | storage part C1, C2 Code W Work

Claims (7)

An imaging unit having an imaging element for imaging a code attached to a workpiece;
A detection unit for detecting information on the size of a code included in an image captured by the imaging unit;
A determination reference value storage that stores a size determination reference value that serves as a reference for determining whether or not the code is an object for enlargement interpolation processing based on information about the size of the code included in the image captured by the imaging unit. And
Whether or not the code size is subject to enlargement interpolation processing is determined based on the information related to the code size detected by the detection unit and the size determination reference value stored in the determination reference value storage unit. If it is determined and the code size is determined to be an object of enlargement interpolation processing, an enlargement interpolation process is performed on a partial image including the code among the images captured by the imaging unit, while the code size is determined. Is determined not to be subject to enlargement interpolation processing, an enlargement interpolation processing unit configured not to perform enlargement interpolation processing of a partial image including a code;
A decoding unit that decodes a code included in either the partial image that has been subjected to the expansion interpolation processing by the expansion interpolation processing unit or the partial image that has not been subjected to the expansion interpolation processing by the expansion interpolation processing unit; An optical information reader. The optical information reader according to claim 1.
An optical information reading apparatus characterized in that an image picked up by the image pickup unit includes a code that is an object of enlargement interpolation processing and a code that is not an object of enlargement interpolation processing. The optical information reader according to claim 1 or 2,
The optical information reading apparatus, wherein the partial image to be subjected to the enlargement interpolation process is an image including a code area indicating a code and a peripheral area of the code area. In the optical information reader according to any one of claims 1 to 3,
The code is a two-dimensional code, and the information regarding the code size is arranged at a predetermined position of the two-dimensional code, and is a size of a position detection pattern for detecting the position of the two-dimensional code. An optical information reader. In the optical information reader according to any one of claims 1 to 3,
2. The optical information reader according to claim 1, wherein the code is a two-dimensional code, and the information regarding the size of the code is a cell size of the two-dimensional code or a pixel size constituting one cell of the two-dimensional code. In the optical information reader according to any one of claims 1 to 5,
A blur correction unit that performs a correction process for correcting the blur of the code of the partial image subjected to the magnification interpolation process by the magnification interpolation processing unit;
The optical information reading apparatus, wherein the decoding unit is configured to decode after the correction processing by the blur correction unit is executed. In the optical information reading device according to any one of claims 1 to 6,
Prior to decoding, the decoding unit is configured to perform cell position estimation processing for estimating a cell position of a code based on a partial image that has been subjected to expansion interpolation processing by the expansion interpolation processing unit. An optical information reader.