Optical reader apparatus

Abstract

To provide a technique for reading information from a target from which information is read, with proper settings.SOLUTION: An optical reader apparatus according to the present invention has an imaging unit for capturing a reading target to generate image data of the reading target, an output unit for outputting the information ready from the image data, and a first determination unit for, if a distance between the optical reader apparatus and the reading target falls within a first range, determining an imaging speed for imaging the reading target by the imaging unit as a first value and for, if the distance between the optical reader apparatus and the reading target falls within a second range closer as compared with the first range, determining the imaging speed as a second value faster than the first value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an optical reading device that optically reads information from a reading target. [Background technology]

[0002] Patent Document 1 discloses an optical reading device that reads information from image data obtained by capturing an image of a reading target such as a barcode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-055005 Summary of the Invention [Problem to be solved by the invention]

[0004] This specification provides a technique for reading information from a reading target in an appropriate setting. [Means for solving the problem]

[0005] The optical reading device disclosed in this specification comprises an imaging unit that photographs an object to be read and generates image data of the object to be read, an output unit that outputs information read from the image data, and a first determination unit that determines the imaging speed at which the imaging unit photographs the object to be read to a first value when the distance between the optical reading device and the object to be read is within a first range, and determines the imaging speed to a second value faster than the first value when the distance between the optical reading device and the object to be read is within a second range closer than the first range.

[0006] When reading information from a target object within a second range that is closer to the optical reading device, image data with sufficient accuracy for reading information from the target object can be obtained even if the imaging speed is fast. On the other hand, when reading information from a target object within a first range that is farther from the optical reading device, image data with sufficient accuracy for reading information from the target object can be obtained by slowing down the imaging speed. In other words, an appropriate imaging speed can be determined by utilizing the distance between the optical reading device and the target object. In particular, the processing speed for reading information from the target object depends on the imaging speed for photographing the target object. An appropriate imaging speed allows information to be read from the target object at an appropriate processing speed.

[0007] The shooting speed may be set to the second value as a default, and the first determination unit may determine to maintain the shooting speed at the second value when the distance is within the second range, and may determine to change the shooting speed from the second value to the first value when the distance is within the first range.

[0008] According to the above configuration, the processing speed can be increased in the initial stage.

[0009] The optical reading device may store a cropping setting value indicating either a first cropping value indicating that the object to be read is to be photographed without cropping, or a second cropping value indicating that the object to be read is to be photographed with cropping, and the cropping setting value is set to the second cropping value as a default.The optical reading device may further include a first change unit that changes the cropping setting value from the second cropping value to the first cropping value when reading of information from the image data generated by the photographing unit fails after the photographing speed is determined to be either the first value or the second value.

[0010] According to the above configuration, by cropping by default, it is possible to increase the processing speed in the initial stage of the series of processes for reading information from the reading target. Furthermore, by canceling cropping when reading fails, it is possible to promote successful reading of information from the reading target.

[0011] The optical reading device may store a sampling setting value indicating one of a plurality of sampling values including a first sampling value indicating that the object to be read is to be photographed at a first sampling interval and a second sampling value indicating that the object to be read is to be photographed at a second sampling interval that is coarser than the first sampling interval, and the sampling setting value is set to the second sampling value as a default.The optical reading device may further include a second change unit that changes the sampling setting value from the second sampling value to the first sampling value when reading of information from the image data generated by the photographing unit fails after the photographing speed is determined to be either the first value or the second value.

[0012] According to the above configuration, by making the sampling interval large by default, it is possible to increase the processing speed in the initial stage of the series of processes for reading information from the reading target. Furthermore, by shortening the sampling interval when reading fails, it is possible to promote successful reading of information from the reading target.

[0013] The photographing unit may include a lens, an image sensor that converts the light focused by the lens into the image data, and a lens moving unit that moves the lens along the optical axis of the lens, and the optical reading device may further include a second determination unit that determines the distance between the optical reading device and the object to be read based on information obtained from the lens moving unit that moves the lens.

[0014] The information obtained from the lens moving unit may be a position of the lens to which the lens moving unit has moved so that the lens is focused on the object to be read.

[0015] According to the above configuration, the distance between the optical reader and the object to be read can be determined by utilizing the lens moving unit that adjusts the focus of the lens on the object to be read.

[0016] This specification further discloses another optical reading device, which includes an imaging unit that images an information code and generates image data of the information code, an output unit that outputs information read from the image data, a memory that stores a cropping setting value and a sampling setting value, and a change unit that changes the cropping setting value and the sampling setting value, wherein the cropping setting value indicates either a first cropping value that indicates that the information code is to be imaged without cropping or a second cropping value that indicates that the information code is to be imaged with cropping, and the sampling setting value indicates either a first sampling value that indicates that the information code is to be imaged at a first sampling interval or a second sampling interval that is longer than the first sampling interval. and a second sampling value indicating

[0017] According to the above configuration, by cropping by default and setting a coarse sampling interval, it is possible to increase the processing speed in the initial stage of a series of processes for reading information from a reading target. Furthermore, if the entire information code is not included within the angle of view and reading fails, it is presumed that one cause is that a portion of the information code is cut off due to cropping. In this case, by canceling cropping, it is possible to promote successful reading of information from the information code. Furthermore, if reading fails even though the entire information code is included within the angle of view, it is presumed that one cause is that the sampling interval is too coarse. In this case, by setting a finer sampling interval, it is possible to promote successful reading of information from the information code.

[0018] This specification further discloses another optical reading device, which may include a photographing unit that photographs an information code and generates image data of the information code, an output unit that outputs information read from the image data, and a determination unit that, when specifying that information is to be read from a first type of information code, determines a photographing speed at which the photographing unit photographs the information code to a third value, and, when specifying that information is to be read from a second type of information code different from the first type of information code, determines the photographing speed to a fourth value slower than the third value.

[0019] When reading information from a first type of information code, a sufficient angle of view for capturing an image of the information code can be obtained even if the shooting speed is fast. On the other hand, when reading information from a second type of information code, a fast shooting speed does not allow a sufficient angle of view for capturing an image of the information code. For this reason, when reading information from a second type of information code, the shooting speed is slowed down. In other words, an appropriate shooting speed can be determined based on the type of information code.

[0020] This specification further discloses another optical reading device, which may include an imaging unit that images an information code and generates image data of the information code, an output unit that outputs information read from the image data, a measurement unit that measures the distance between the optical reading device and the information code, and a determination unit that determines a speed at which the imaging unit images the information code based on information indicating at least one of the number of digits and the format of the information code and the distance measured by the measurement unit.

[0021] For example, when reading an information code with a small number of digits from close range, a sufficient angle of view for capturing an image of the information code can be obtained even at a fast imaging speed. On the other hand, when reading an information code with a large number of digits from close range, a fast imaging speed does not provide a sufficient angle of view for capturing an image of the information code. Furthermore, when reading an information code with a small number of digits from a distance, a fast imaging speed does not provide image data with sufficient accuracy for reading information from the information code. Similarly, there is an appropriate imaging speed depending on the distance from the information code, even for different information code standards. With the above configuration, an appropriate imaging speed can be determined based on the distance between the information code and information indicating at least one of the number of digits and the standard of the information code. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is a block diagram of an optical reader. [Figure 2] FIG. 3 is a flowchart showing the processing of the optical reading device according to the first embodiment. [Figure 3] FIG. 10 is a sequence diagram of processing from the start of imaging to the output of the reading result in a comparative example. [Figure 4] FIG. 10 is a sequence diagram of processing from the start of imaging to the output of the reading result in case C1 where the reading target is at a short distance. [Figure 5] FIG. 10 is a sequence diagram of processing from the start of imaging to the output of the reading result in case C2 where the reading target is at a long distance. [Figure 6]FIG. 10 is a flowchart showing the processing of the optical reading device according to the second embodiment. [Figure 7] FIG. 10 is a sequence diagram of processing from the start of imaging to the output of the reading result in case C3 where the reading target is at a short distance. [Figure 8] FIG. 11 is a flowchart showing the processing of the optical reading device according to the third embodiment. [Figure 9] FIG. 10 is a sequence diagram of processing from the start of imaging to the output of the reading result in case C4 where the reading target is at a long distance. [Figure 10] FIG. 10 is a flowchart showing the processing of the optical reading device according to the fourth embodiment. [Figure 11] FIG. 11 is a flowchart showing the processing of the optical reading device according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] (Usage of the optical reader 10; Figure 1) The optical reading device 10 (hereinafter referred to as "reading device 10") of this embodiment is a device that photographs an information code (e.g., a barcode, a two-dimensional code) and optically reads information from the photographed information code. The reading device 10 may be portable or stationary. The reading device 10 may photograph an information code 100 that is located near the reading device 10, or may photograph an information code 200 that is located far from the reading device 10.

[0024] (Configuration of the reader 10; Figure 2) The reading device 10 includes an imaging unit 12, a marker projection unit 22, a display unit 24, an operation unit 26, and a control unit 30. The imaging unit 12 is a device for capturing an image of an information code, and includes a lens 14, an image sensor 16, a lens movement mechanism 18, and an illumination unit 20. The lens 14 collects light from a subject. The image sensor 16 converts the light collected by the lens 14 into image data.

[0025] The lens movement mechanism 18 moves the lens 14 along its optical axis. The lens movement mechanism 18 is an actuator for a so-called autofocus function. The autofocus function may be, for example, a contrast method or a phase difference method. The illumination 20 is, for example, an LED, and illuminates the information code. The marker illumination unit 22 illuminates a marker that indicates the information code to be read.

[0026] The display unit 24 is a display that displays various information, such as a liquid crystal display or organic EL display. The operation unit 26 is an input device that accepts various instructions, such as a mechanical switch or a touch panel exposed on the housing of the reading device 10. The control unit 30 includes a CPU 32 and a memory 34. The CPU 32 executes various processes in accordance with a program 40 stored in the memory 34. The memory 34 is a volatile memory or a non-volatile memory.

[0027] The memory 34 further stores default setting values 42. The default setting values 42 indicate default values for each setting value of the image capture unit 12. The setting values of the image capture unit 12 are, for example, an exposure time and a shooting speed. The exposure time is the duration for which the light source 20 illuminates the information code per unit frame. The shooting speed indicates the number of times images can be captured per unit time, and the unit of the shooting speed is, for example, the frame rate (fps). Generally, a high shooting speed results in a low-resolution image, and a low shooting speed results in a high-resolution image. In this embodiment, the exposure time of the default setting value 42 is a relatively short value E0 (for example, 2 milliseconds), and the shooting speed of the default setting value 42 is a relatively fast value F0 (for example, 120 fps).

[0028] (Processing of the reader 10; Figure 2) The process executed by the CPU 32 in accordance with the program 40 will be described with reference to Fig. 2. The process in Fig. 2 is started, for example, when the power of the reading device 10 is turned on.

[0029] In S10, the CPU 32 monitors whether or not an instruction to read the information code has been input to the operation unit 26. If an instruction to read the information code has been input to the operation unit 26 (YES in S10), the CPU 32 proceeds to S20.

[0030] In S20, the CPU 32 acquires the default setting values 42 from the memory 34. In S22, the CPU 32 activates the photographing unit 12 and starts photographing by the photographing unit 12. The CPU 32 photographs a plurality of frames of images while adjusting the position of the lens 14 with the lens moving mechanism 18 and changing each setting value of the photographing unit 12.

[0031] In S24, the CPU 32 determines whether the information code (e.g., 100) to be read is located in a far distance range from the reader 10 (hereinafter referred to as the "far point"). In this embodiment, the CPU 32 determines the distance between the reader 10 and the read target from the position of the lens 14 to which the lens moving mechanism 18 has moved the lens 14 so that the lens 14 is focused on the read target. For example, if the autofocus function moves the lens 14 to a position corresponding to the far point, the CPU 32 determines that the read target is located at the far point. On the other hand, if the position of the lens 14 moved by the lens moving mechanism 18 is located in a near distance range from the reader 10 (hereinafter referred to as the "near point"), the CPU 32 determines that the read target is located at the near point. Note that if the autofocus function of the lens moving mechanism 18 is a phase difference type, the position of the lens 14 is determined from phase difference data obtained according to the phase difference type. In a modified example, the CPU 32 may use the phase difference data to determine the distance between the reader 10 and the read target. Since the phase difference data is obtained before the lens moving mechanism 18 actually moves the lens 14, the distance to the target can be determined more quickly than in the embodiment where the distance is determined from the position of the lens 14. In other modified examples, the distance between the reader 10 and the target may be measured using other methods such as laser or ultrasonic waves.

[0032] When the CPU 32 determines that the reading target is present at a far point (YES in S24), in S26, the CPU 32 changes the shooting speed from the value F0 in the default setting value 42 to a value slower than the value F0 (for example, 30 fps). When the processing of S26 ends, the CPU 32 proceeds to S30.

[0033] On the other hand, if the CPU 32 determines that the reading target is present at the near point (NO in S24), it skips the process of S26 and proceeds to S30, where the shooting speed is maintained at the default value F0.

[0034] In S30, the CPU 32 executes decoding on the image data of the information code photographed by the photographing unit 12. If the decoding fails (NO in S30), the CPU 32 proceeds to S32.

[0035] In S32, the CPU 32 changes the exposure time from the current value to a value longer than the current value. For example, if the current value is value E0 in the default setting value 42, the CPU 32 changes the value from E0 to a value longer than E0 (for example, 4 milliseconds). When the process of S32 ends, the CPU 32 returns to S30.

[0036] Furthermore, if the decoding is successful (YES in S30), the CPU 32 skips the process of S32 and proceeds to S40. In S40, the CPU 32 outputs the result of the decoding, i.e., the information read from the information code. For example, the CPU 32 displays the information read from the information code on the display unit 24. In a modified example, the CPU 32 may transmit the information read from the information code to an external device (e.g., a server). When the process of S40 ends, the CPU 32 ends the process of FIG. 2.

[0037] (Case C1; Figure 4) In this case, the reading device 10 reads information from the information code 100 at the near point. At T10, the reading device 10 starts capturing an image in response to a reading instruction (S22 in FIG. 2). In this case, the default setting values 42 include an exposure time E0 and a capturing speed F0.

[0038] The reading device 10 captures the first frame (N=1) with an exposure time E0 and a shooting speed F0. At the shooting speed F0, one frame is captured at time p2. For example, if F0 is 120 fps, p2 is 8.3 milliseconds. In this case, the reading device 10 causes the lens movement mechanism 18 to move the lens 14 based on the two captured frames, and focuses on the information code 100. At T12, the reading device 10 determines that the position of the lens 14 corresponds to the near point (NO in S24 of FIG. 2), and maintains the default shooting speed F0.

[0039] At the next time T14, the reading device 10 determines that decoding of the image data for the second frame (N=2) has failed (NO in S30), and changes the exposure time from the default value E0 to a value E1 (S32). The value E1 is longer than the value E0.

[0040] The reading device 10 uses exposure time E1 to capture the third and fourth frames (N=3, 4), and based on the third and fourth frames, focuses on the information code 100. In this case, the reading device 10 successfully decodes the image data in the fourth frame at T16 (YES in S30), and outputs the information read from the information code 100 (S40).

[0041] (Case C2; Figure 5) In this case, the reader 10 reads information from the information code 200 at the far point. T20 is the same as T10 in FIG. 4. In this case, the reader 10 also focuses on the information code 200 based on two captured frames. In T22, the reader 10 determines that the position of the lens 14 corresponds to the far point (YES in S24 in FIG. 2), and changes the default shooting speed F0 to shooting speed F1 (S26). The shooting speed F1 is slower than the shooting speed F0, and images captured at the shooting speed F1 have higher resolution than images captured at the shooting speed F0. At the shooting speed F1, one frame is captured at time p1. For example, if F1 is 30 fps, p1 is 33.3 milliseconds. The following T24 and T26 are the same as T14 and T16 in FIG. 3.

[0042] (Effects of this embodiment) For example, consider the comparative example of Fig. 3, which uses the shooting speed F1 as the default setting value 42. In this comparative example, the reading device does not determine whether to change the default shooting speed F1, i.e., does not execute the determination of S24 in Fig. 2.

[0043] At Y1, the reading device starts capturing images and focuses on the information code (100 or 200) based on the two captured frames (N=1, 2). At Y2, it determines that decoding of the image data in the second frame (N=2) has failed, and changes the exposure time from the default value E0 to a value E1 that is longer than E0. At Y3, the reading device successfully decodes the image data in the fourth frame (N=4), and outputs the information read from the information code.

[0044] In the comparative example of FIG. 3 , the time from the start of imaging to the output of the decoded result is t1 = p1 × 4. In contrast, in case C1 of this embodiment, the time from the start of imaging to the output of the decoded result is t2 = p2 × 4, and in case C2, the time from the start of imaging to the output of the decoded result is t3 = p2 × 2 + p1 × 2. That is, in this embodiment, information can be read in a shorter time than in the comparative example for both the information code 100 at the near point and the information code 200 at the far point. When reading information from the information code 100 at the near point, the image of the information code 100 becomes relatively large. Therefore, information can be read even from low-resolution image data obtained at a high imaging speed. On the other hand, when reading information from the information code 200 at the far point, the image of the information code 100 becomes relatively small. Therefore, it may be impossible to read information from low-resolution image data obtained at a high imaging speed. In case C2, the shooting speed is changed from value F0 to value F1, which is slower than value F0, and the third and subsequent frames are obtained at high resolution, facilitating the reading of information from the far-point information code 200. In case C2, the shooting speed is set to the relatively fast F0 at the default stage, so even if the shooting speed is changed to value F1 midway, the decoded result is output faster than in the comparative example.

[0045] In the comparative example, the default shooting speed is relatively slow, but high-resolution images are obtained by default.While it is possible to handle both near-point and far-point information codes, the processing speed for reading information from the information code is relatively slow.In contrast, in the embodiment, the default shooting speed is relatively fast, and an appropriate shooting speed is determined depending on the distance to the information code.The processing speed of the embodiment is faster than that of the comparative example.

[0046] (Correspondence) The information codes 100 and 200 are examples of a "reading target." The reading device 10, the photographing unit 12, and the display unit 24 are examples of an "optical reading device," "photographing unit," and "output unit," respectively. The lens 14, the image sensor 16, and the lens moving mechanism 18 are examples of a "lens," "image sensor," and "lens moving mechanism," respectively. The far point and the photographing speed F1 are examples of a "first range" and a "first value," respectively. The near point and the photographing speed F0 are examples of a "second range" and a "second value," respectively. The control unit 30 that executes the processing of S24 in FIG. 2 is an example of a "first determination unit."

[0047] (Second Example) In this embodiment, the default setting value 42 further includes a cropping setting value "cropping ON." The cropping setting value indicates whether or not cropping is used. Cropping is a method of capturing an image by cutting out a portion of the maximum angle of view that the image sensor 16 can capture. When the cropping setting value is "cropping ON," it indicates that the information code is captured with cropping. On the other hand, when the cropping setting value is "cropping OFF," it indicates that the object to be read is captured without cropping. In this embodiment, the object to be read is an information code (e.g., a barcode or a two-dimensional code).

[0048] (Processing of the reader 10; Figure 6) The processing of this embodiment is the same as that of the first embodiment, except that the content of the default setting value 42 acquired in S20 is different and that the processing of S100 and S120 is added.

[0049] In S20, the CPU 32 acquires the exposure time, the shooting speed, and the cropping setting value as the default setting value 42. The default cropping setting value is "cropping ON."

[0050] If the CPU 32 fails to decode the image data of the information code photographed by the photographing unit 12 (NO in S30), the CPU 32 proceeds to S100. In S100, the CPU 32 selects either the exposure time or the cropping setting value as the setting value to be changed. For example, the CPU 32 changes the exposure time at the first failure, and changes the cropping setting value at the next failure.

[0051] In the next step S120, the CPU 32 changes the setting value selected in step S100. If the exposure time is selected as the setting value to be changed, the CPU 32 changes the exposure time from its current value to a value longer than the current value. If the cropping setting value is selected as the setting value to be changed, the CPU 32 changes the cropping setting value from the default "cropping ON" to "cropping OFF." When step S120 ends, the CPU 32 returns to step S30.

[0052] (Case C3; Figure 7) In this case, the reading device 10 reads information from the information code 300 at the near point. T30 to T34 are the same as T10 to T14 in FIG. 4. For example, if the information code 300 is too close to the reading device 10 in the "cropping ON" state, the entire information code 300 may not fit within the angle of view, as shown in FIG. 7. In this case, decoding of the fourth frame fails at T35 because the entire information code 300 does not fit within the fourth frame (NO in S30 in FIG. 6). Then, the reading device 10 changes the cropping setting value from "cropping ON" to "cropping OFF" (S120).

[0053] In the "cropping OFF" state, cropping of the angle of view is not performed. Therefore, as shown in Fig. 7, in the "cropping OFF" state, the entire information code 300 can fit within the angle of view. In this case, the entire information code 300 fits within the fifth frame, and therefore decoding of the fifth frame is successful at T36 (YES in S30 in Fig. 7).

[0054] The shooting speed when cropping is ON is faster than the shooting speed when cropping is OFF. According to this embodiment, cropping by default can increase the processing speed in the initial stage of a series of processes for reading information from the information code 300. The increased processing speed in the initial stage can increase the processing speed compared to the comparative example in FIG. 3. Furthermore, by canceling cropping when reading fails, it is possible to encourage successful reading of information from the information code 300.

[0055] Furthermore, even when reading information from an information code 300 at a distant point, there are cases where the entire information code 300 does not fit within the angle of view. For example, this occurs when the information code 300 is too large for the cropped angle of view. Even when reading information from an information code 300 at a distant point, the reading device 10 changes the cropping setting value from "cropping ON" to "cropping OFF" if reading fails (YES in S20, NO in S30, S120). This can encourage successful reading of information from the information code 300 at a distant point.

[0056] (Correspondence) The value "cropping OFF" and the value "cropping ON" are examples of a "first cropping value" and a "second cropping value", respectively.

[0057] (Third Example) In this embodiment, the default setting value 42 includes a sampling interval R0 in addition to the cropping setting value "cropping ON." The sampling interval indicates one of multiple sampling values, and each sampling value indicates the proportion of pixels to be thinned out from the maximum number of pixels of the image sensor 16. Each sampling value is, for example, the number and direction of pixels to be averaged into one pixel by binning. In addition, the reading target in this embodiment is an information code. The sampling interval R0 is a relatively coarse value, and when the sampling interval R0 is set, a relatively low-resolution image is captured.

[0058] (Processing of the reader 10; Figure 8) The processing of this embodiment is the same as that of the first embodiment, except that the content of the default setting value 42 acquired in S20 is different and that the processing of S100 to S108 and S120 is added.

[0059] In S20, the CPU 32 acquires the exposure time, shooting speed, cropping setting value, and sampling interval as default setting values 42. The default cropping setting value is "cropping ON," and the default sampling interval is R0.

[0060] In S100 of this embodiment, the CPU 32 determines which of the exposure time, cropping setting value, and sampling interval should be changed. For example, the CPU 32 changes the exposure time at the first failure, and changes either the cropping setting value or sampling interval at the next failure.

[0061] In the next S102, the CPU 32 determines whether the setting value to be changed determined in S100 is a setting value other than the cropping setting value and the sampling interval. If the CPU 32 determines that the setting value to be changed determined in S100 is a setting value other than the cropping setting value and the sampling interval (YES in S102), the CPU 32 skips the processes of S104 to S108, which will be described later, and proceeds to S120. On the other hand, if the CPU 32 determines that the setting value to be changed determined in S100 is either the cropping setting value or the sampling interval (NO in S102), the CPU 32 proceeds to S104.

[0062] In S104, the CPU 32 determines whether the entire image of the information code is included within the angle of view. Conditions for the entire image of the information code to be included within the angle of view include, for example, the presence of a rectangle with four corners within the angle of view, the image within the angle of view not reaching the edge of the angle of view, the presence of a rectangle with a certain area or more within the angle of view, and the image within the angle of view not being a concave rectangle. This is because the outer shape of the information code is generally rectangular.

[0063] If the CPU 32 determines that the entire image of the information code within the angle of view is included (YES in S104), the process proceeds to S106. In S106, the CPU 32 determines the sampling interval as the setting value to be changed.

[0064] If the CPU 32 determines that the entire image of the two-dimensional code is included within the angle of view (YES in S104), the process proceeds to S 108. In S 108, the CPU 32 determines the cropping setting value as the setting value to be changed.

[0065] In S120 of this embodiment, the CPU 32 changes the setting value determined in any one of S100, S106, and S108. When the exposure time and cropping setting value are determined as the setting value to be changed, the process is the same as in the second embodiment. When the sampling interval is determined as the setting value to be changed, the CPU 32 changes the sampling interval from its current value to a value with a higher resolution than the current value. When S120 ends, the CPU 32 returns to S30.

[0066] (Case C4; Figure 9) In this case, the reading device 10 reads information from the information code at the far point. T40 to T44 are the same as T20 to T24 in FIG. 5. For example, if the information code is too far from the reading device 10 when the sampling interval is R0, the image of the information code within the angle of view may become unclear. In this case, the decoding of the fourth frame fails at T45 due to the blurred image of the information code in the fourth frame (NO in S30 in FIG. 8). Then, the reading device 10 determines that the entire image of the information code is included within the angle of view (YES in S104), and changes the sampling interval from the default value R0 to a value R1 with a higher resolution than the value R0 (S120).

[0067] The sampling interval R1 is a value with a higher resolution than the sampling interval R0. With the sampling interval R1, a high-resolution image is captured, and the image of the information code within the angle of view can be clear. In this case, the image of the information code in the fifth frame is clear, and therefore decoding of the fifth frame is successful at T46 (YES in S30 of FIG. 8).

[0068] The imaging speed when the sampling interval is R0 is faster than the imaging speed when the sampling interval is R1. According to this embodiment, by setting the sampling interval to a large value by default, it is possible to increase the processing speed in the initial stage of the series of processes for reading information from the information code. By increasing the processing speed in the initial stage, it is possible to increase the processing speed compared to the comparative example of FIG. 3. Furthermore, by shortening the sampling interval when reading fails, it is possible to encourage successful reading of information from the information code.

[0069] Furthermore, even when reading information from an information code at a near point, the image of the information code within the angle of view may be unclear. For example, this may occur when the information code is too small for the angle of view. Even when reading information from an information code at a near point, the reader 10 changes the sampling interval from R0 to R1 if reading fails (NO in S24, NO in S30, YES in S104, S106). This can facilitate successful reading of information from an information code at a near point.

[0070] (Correspondence) The sampling intervals R1 and R0 are examples of the "first sampling value" and the "second sampling value", respectively.

[0071] (Fourth Example) (Processing of the reader 10; Figure 10) This embodiment is similar to the third embodiment except that the processes of S24 and S26 are not executed. According to the configuration of this embodiment, cropping is performed by default and the sampling interval is made coarse, thereby increasing the processing speed in the initial stage of the series of processes for reading information from an information code. Furthermore, if the entire information code is not included within the angle of view and reading fails, it is presumed that one cause is that a portion of the information code is cut off by cropping. In this case, by canceling cropping (S108 in FIG. 10), successful reading of information from the information code can be promoted. Furthermore, if reading fails even though the entire information code is included within the angle of view, it is presumed that one cause is that the sampling interval is too coarse. In this case, by shortening the sampling interval (S106 in FIG. 10), successful reading of information from the information code can be promoted.

[0072] (Correspondence) The memory 34 is an example of a "memory." The control unit 30 that executes the processes of S106, S108, and S120 in Fig. 10 is an example of a "change unit."

[0073] (Fifth Example) (Each table; Figure 11) In this embodiment, the memory 34 of the reading device 10 stores a setting table 400 and a selection matrix 402. The setting table 400 stores a plurality of setting information related to imaging. Each setting information in the setting table 400 includes a setting name, a resolution, an imaging speed, and other setting values. The other setting values include filter setting values such as cropping.

[0074] For example, the setting information for setting name SN1 includes a resolution of 4208 x 3120, an image capture speed of 30 fps, and another setting value V1. Furthermore, for example, the setting information for setting name SN3 includes a resolution of 2104 x 1560, an image capture speed of 60 fps, and another setting value V2. Generally, the higher the resolution, the slower the image capture speed. Furthermore, the higher the resolution, the wider the image capture angle.

[0075] The selection matrix 402 is a matrix for selecting one piece of setting information from the multiple pieces of setting information in the setting table 400. The rows of the selection matrix 402 indicate the distance d from the information code to be read, and the columns of the selection matrix 402 indicate the use of the reading device 10.

[0076] For example, different standards are used for different applications. For example, the standard for barcodes attached to products is JAN, while the standard for barcodes attached to collective packaging is ITF. Generally, the width of ITF attached to collective packaging is larger than the width of JAN attached to products. Therefore, when the distance d from the barcode is the same, the angle of view sufficient to read an ITF is wider than the angle of view sufficient to read a JAN. Even within the same JAN code, there are two types: JAN13 (13 digits) and JAN8 (8 digits). Because the width of JAN13 is larger than the width of JAN8, the angle of view sufficient to read information differs between JAN13 and JAN8. In addition, there are standards other than JAN and ITF, such as Code39 and NW-7. Furthermore, when the distance d from the barcode is the same, the resolution sufficient to read information from a JAN differs from the resolution sufficient to read information from an ITF. This is because the element widths of JAN and ITF are different. Such differences in resolution also exist in standards other than JAN and ITF.

[0077] Selection matrix 402 stores the setting name of the appropriate setting information determined from the purpose and distance d. Since the purpose determines at least one of the number of digits and the standard to be used, the appropriate setting information is also determined by specifying the purpose. In a modified example, the columns of selection matrix 402 may indicate the names of barcode standards.

[0078] The contents of the selection matrix 402 are determined in advance by the vendor of the reading device 10. The contents of the selection matrix 402 may be customized by the user of the reading device 10. The reading device 10 displays a designation screen for designating one use from among a plurality of uses. The user designates one use on the designation screen.

[0079] (Processing of the reader 10; Figure 6) S210 to S222 are the same as S10 to S22 in FIG. 2. In S224, CPU 32 determines the distance to the barcode using the autofocus function, as in the first embodiment. In S226, CPU 32 identifies, from selection matrix 402, the setting name corresponding to the purpose specified by the user and the distance determined in S224. Then, CPU 32 changes the setting value of the imaging unit 12 to the setting value in the setting information corresponding to the identified setting name. S230 to S240 are the same as S30 to S40 in FIG. 2.

[0080] For example, if the user specifies the use "store" and the distance between distances d1 and d2 is determined in S224, the setting name SN3 is identified from the selection matrix 402 (S226). The resolution corresponding to the setting name SN3 is 2104 x 1560, and the imaging speed is 60 fps. Based on the distance between the use "store" and distances d1 and d2, the imaging speed is changed from 120 fps to 60 fps. An appropriate imaging speed means an appropriate angle of view and resolution, and although the imaging speed is slower, it makes it easier to successfully decode the barcode, resulting in a shorter time until the barcode reading is completed. Note that in this embodiment, the initial imaging speed is set to 120 fps, and the time until focusing is short, which can contribute to shortening the time until the processing of FIG. 11 is completed.

[0081] Furthermore, for example, if a user changes the use from "store" to "logistics," the appropriate setting information also changes. A wide ITF is used for the use "logistics." If the capture speed is too fast, an image sufficient for capturing a barcode cannot be obtained. Therefore, a slower capture speed is determined for the use "logistics" than for the use "store." For example, in a situation where the distance to the barcode is between distance d1 and distance d2, an capture speed of 60 fps corresponding to setting name SN3 is determined for the use "store," while an capture speed of 30 fps corresponding to setting name SN2 is determined for the use "logistics." The configuration of this embodiment makes it possible to obtain an image sufficient for capturing a barcode. In other words, an appropriate capture speed can be determined based on the type of barcode.

[0082] (Correspondence) JAN and ITF are examples of a “first type of information code” and a “second type of information code”, respectively. An imaging speed of 60 fps corresponding to the setting name SN3 and an imaging speed of 30 fps corresponding to the setting name SN2 are examples of a “third value” and a “fourth value”, respectively.

[0083] Although specific examples of the technology disclosed in this specification have been described above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. For example, the following modifications may be adopted.

[0084] (Variation 1) The "read object" is not limited to an information code, but may be, for example, a character string displayed on a medium. In this case, character recognition technology may be used to read information from the character string.

[0085] (Variation 2) The default imaging speed may be a relatively slow imaging speed. In this case, when the reading device 10 determines in S24 that the reading target is at a near point, the reading device 10 may change the imaging speed from the default value to a value faster than the default value.

[0086] (Variation 3) When the autofocus function is a phase difference type, the "lens moving unit" may include an actuator that actually moves the lens 14 and a sensor for acquiring phase difference data. In this case, the "information obtained from the lens moving unit" may be phase difference data.

[0087] The technical elements described in this specification or drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings simultaneously achieve multiple objectives, and achieving one of those objectives is itself technically useful. [Explanation of symbols]

[0088] 10: Reading device 12: Photography Department 14: Lens 16: Image sensor 18: Lens movement mechanism 20: Lighting 22: Marker irradiation unit 24:Display section 26:Operation section 30: Control section 32 :CPU 34: Memory 40: Program 42: Default setting value 100, 200, 300: Information code 400: Setting table 400 402: Selection Matrix 402 E0, E1: Exposure time F0, F1: Shooting speed R0, R1: Sampling interval p1, p2: time SN1~SN5: Setting name

Claims

1. An optical reader, an imaging unit that captures an image of an object to be read and generates image data of the object to be read; an output unit that outputs information read from the image data; a first determination unit that determines a photographing speed at which the photographing unit photographs the object to be read to a first value when the distance between the optical reader and the object to be read is within a first range, and that determines the photographing speed to a second value faster than the first value when the distance between the optical reader and the object to be read is within a second range that is closer than the first range; An optical reading device comprising:

2. the shooting speed is set to the second value as a default; The first determination unit determining to maintain the image capture speed at the second value when the distance is within the second range; The optical reading device according to claim 1 , wherein when the distance is included in the first range, it is determined that the photographing speed is changed from the second value to the first value.

3. the optical reading device stores a cropping setting value indicating either a first cropping value indicating that the object to be read is to be photographed without cropping, or a second cropping value indicating that the object to be read is to be photographed with cropping; the cropping setting value is set to the second cropping value as a default; The optical reader further comprises:

2. The optical reading device of claim 1, further comprising a first change unit that changes the cropping setting value from the second cropping value to the first cropping value when reading of information from the image data generated by the photographing unit fails after the photographing speed is determined to be either the first value or the second value.

4. the optical reading device stores a sampling setting value indicating one of a plurality of sampling values including a first sampling value indicating that the object to be read is to be photographed at a first sampling interval and a second sampling value indicating that the object to be read is to be photographed at a second sampling interval that is longer than the first sampling interval; the sampling setting value is set to the second sampling value as a default; The optical reader further comprises:

2. The optical reading device of claim 1, further comprising a second change unit that changes the sampling setting value from the second sampling value to the first sampling value when reading of information from the image data generated by the photographing unit fails after the photographing speed is determined to be either the first value or the second value.

5. The imaging unit is Lenses and an image sensor that converts the light collected by the lens into image data; a lens moving unit that moves the lens along an optical axis of the lens; Equipped with The optical reader further comprises:

5. The optical reading device according to claim 1, further comprising a second determination unit that determines the distance between the optical reading device and the object to be read based on information obtained from the lens movement unit that moves the lens.

6. 6. The optical reading device according to claim 5, wherein the information obtained from the lens moving unit is a position of the lens to which the lens moving unit has moved so that the lens is focused on the object to be read.

7. An optical reader, an imaging unit that images an information code and generates image data of the information code; an output unit that outputs information read from the image data; a memory for storing cropping setting values and sampling setting values; a change unit that changes the cropping setting value and the sampling setting value; Equipped with the cropping setting value indicates either a first cropping value indicating that the information code is to be photographed without being cropped, or a second cropping value indicating that the information code is to be photographed with being cropped; the sampling setting value indicates one of a plurality of sampling values including a first sampling value indicating that the information code is to be photographed at a first sampling interval and a second sampling value indicating that the information code is to be photographed at a second sampling interval that is longer than the first sampling interval; the cropping setting value is set to the second cropping value as a default; the sampling setting value is set to the second sampling value as a default; The change unit changing the cropping setting value from the second cropping value to the first cropping value when reading of the information from the image data fails and the entire information code is not included within the angle of view of the image data; an optical reading device that changes the sampling setting value from the second sampling value to the first sampling value when reading of information from the image data fails and the entire information code is contained within the angle of view of the image data.

8. An optical reader, an imaging unit that images an information code and generates image data of the information code; an output unit that outputs information read from the image data; a determination unit that, when it is specified to read information from a first type of information code, determines a photographing speed at which the photographing unit photographs the information code to a third value, and, when it is specified to read information from a second type of information code different from the first type of information code, determines the photographing speed to a fourth value slower than the third value; An optical reading device comprising:

9. An optical reader, an imaging unit that images an information code and generates image data of the information code; an output unit that outputs information read from the image data; a measuring unit that measures the distance between the optical reader and the information code; a determination unit that determines an imaging speed at which the imaging unit images the information code based on information indicating at least one of the number of digits and the standard of the information code and the distance measured by the measurement unit; An optical reading device comprising:

Images