JP6065719B2 - Optical information reader - Google Patents

Description

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

  Currently, various types of information codes such as barcodes and two-dimensional codes are provided. This type of information code has different specifications and the environment in which it is read depending on the type of information code. Therefore, in order to smoothly read all the information codes with a single reading device, it is necessary to read the brightness of the illumination. It is desirable to change the control condition regarding the reading work environment.

  As an optical information reading device that changes the control conditions regarding this reading, for example, an information code reading device disclosed in Patent Document 1 below is known. In this information code reading device, it is assumed that the inclination of the information code reading device at the time when reading is started is related to what information code is read and in what state. When reading is started, the barcode reading state is estimated based on the tilt angle of the device detected by the tilt sensor, and the barcode reading control conditions are switched according to the estimated reading state. Set. Thereby, the setting according to the reading state of the information code reading apparatus actually performed is automatically performed.

JP 2006-309212 A

  By the way, in the configuration disclosed in the above-mentioned Patent Document 1, even if the tilt state of the optical information reading apparatus during the reading operation can be reflected in the control condition, the code state such as a dirty barcode is reflected in the control condition. Can not do it. For this reason, in order to reflect the control conditions relating to reading in consideration of the code state, it is necessary to manually change the control conditions each time, and there is a problem that convenience is poor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical information reader capable of automatically changing control conditions relating to reading of an information code. .

In order to achieve the above object, the invention described in claim 1 is an optical information reader (10) for optically reading an information code, wherein the information code can be optically read. 28), relative position detection means (50) for detecting the relative position of the optical information reading device with respect to the information code, and detection of the relative position detection means because reading of the information code by the reading means has failed. From the result, determination means (40) for determining whether or not the reading trial state in which the optical information reading apparatus is located within a predetermined range continues for a predetermined time (Δt), and the determination means determines whether the reading trial state is Control condition changing means (40) for changing a control condition related to reading by the reading means when it is determined that the predetermined time has continued.
In addition, the code | symbol in each said parenthesis shows the correspondence with the specific means as described in each embodiment mentioned later.

  In the first aspect of the invention, reading of the information code by the reading means has failed, and the reading trial state in which the optical information reading device is located within a predetermined range from the detection result of the relative position detecting means continues for a predetermined time. When the determination means determines, the control condition relating to reading by the reading means is changed by the control condition changing means.

  When it is determined that the reading trial state has continued for a predetermined time, for example, the optical information reading device is held at a position where the information code is read in order to read the information code that is dirty and difficult to read. A case is assumed. In this case, for example, the information code can be changed by changing the control conditions related to reading such as the threshold when binarizing the signal waveform corresponding to the reflected light from the information code and the brightness of the illumination irradiated to the information code. Sometimes it can be read.

  Therefore, when it is determined that the reading trial state has continued for a predetermined time, the control condition relating to reading by the reading unit is automatically changed. Thereby, the reading of the information code that could not be read under the control condition before the change may be successful. Therefore, the control condition regarding the reading of the information code is automatically changed, and the success rate of reading the information code can be increased.

  In the invention of claim 2, the predetermined range is set based on the position of the optical information reader when the start information is input by the input means. Since it can be set, it is possible to improve the determination accuracy of the state where the information code is being read (reading attempt state).

  In the invention of claim 3, the determination means determines the actual reading start time in order to determine whether or not the time in the reading trial state after the start information is input by the input means continues for the predetermined time. Since it can be compared with a predetermined time as a reference, it is possible to improve the determination accuracy of a state where the information code is being read (reading trial state).

  In the invention of claim 4, the control conditions relating to reading include threshold values when binarizing the signal waveform corresponding to the reflected light from the information code, amplification factor of the signal waveform, and exposure conditions when imaging the information code And at least one of a plurality of control conditions of the focal length of the optical system used for imaging, the brightness of illumination applied to the information code, and the code type of the information code to be read. Thus, even if at least one of the plurality of control conditions is automatically changed, the success rate of reading the information code that cannot be read under the control condition before the change can be increased.

  In the fifth aspect of the present invention, when the determination means determines that the reading trial state continues for a predetermined time even if any one of the plurality of control conditions is changed, the control condition changing means Any one of the other control conditions is changed. Thereby, since various types of control conditions are changed in order to read one information code, the success rate of reading information codes that could not be read under the control conditions before the change can be further increased.

  In the invention of claim 6, the threshold value for binarizing the signal waveform corresponding to the reflected light from the information code among the plurality of control conditions is preferentially changed by the control condition changing means. When the threshold value is changed in this way, a captured image of the information code that has failed to be read before the threshold value change can be used. Therefore, when the information code is successfully read due to the change of the threshold value, the information code Re-imaging can be made unnecessary.

  In the invention of claim 7, when the change frequency by the control condition changing means becomes higher than a predetermined specified value, the predetermined time is adjusted by the time adjusting means to be shorter than when the change frequency is equal to or lower than the predetermined specified value. The Normally, the information code that is difficult to read due to dirt or the like has a higher frequency of change by the control condition changing means. Therefore, when the frequency of change by the control condition changing means is higher than a predetermined specified value, it is assumed that the reading work environment has many information codes that are difficult to read, and the predetermined frequency is set to the predetermined frequency. By adjusting the control condition related to reading in a short time by adjusting it to be shorter than the case where the value is less than or equal to the value, it is possible to shorten the time until the reading is successful.

  In the invention of claim 8, if the frequency of change by the control condition changing means is higher than a predetermined specified value from the result of counting the number of times the information code has been successfully read by the counting means and the number of changes by the control condition changing means. When the determination is made, the predetermined time is adjusted to be shorter by the time adjusting means than when the change frequency is equal to or lower than a predetermined specified value. Thus, by considering the number of times the information code has been successfully read and the number of changes by the control condition changing means, the change frequency corresponding to the reading work environment can be determined appropriately.

1 is a perspective view schematically showing an optical information reading device according to a first embodiment. It is a block diagram which shows the electrical structure of the optical information reader of FIG. It is explanatory drawing explaining the measurement direction of a 3-axis motion sensor. 4 is a flowchart illustrating a flow of a reading process in the first embodiment. It is explanatory drawing explaining a motion of the optical information reader at the time of reading the information code which is difficult to read. It is explanatory drawing explaining the relationship between the threshold value for binarization, and the success or failure of decoding. It is a flowchart which illustrates the flow of the reading process in 2nd Embodiment. It is a flowchart which illustrates the flow of the determination time adjustment process in 2nd Embodiment. It is explanatory drawing explaining the relationship between the brightness of an illumination light source, and the success or failure of decoding.

[First Embodiment]
Hereinafter, a first embodiment of an optical information reading apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing an optical information reading apparatus 10 according to the first embodiment. FIG. 2 is a block diagram showing an electrical configuration of the optical information reading apparatus 10 of FIG.

  An optical information reader 10 shown in FIG. 1 includes an information code configured by arranging a plurality of bright and dark patterns, for example, a one-dimensional code such as a bar code or a two-dimensional code such as a QR code (registered trademark). Is configured as an optical reading device. The optical information reading apparatus 10 is configured such that a circuit unit 20 is accommodated in a case 11 constituting an outer shell. The circuit unit 20 mainly includes an illumination light source 21, a light receiving sensor 28, and an imaging lens 27. And an optical system such as a memory 35 and a control system 40 such as a control circuit 40 (hereinafter referred to as “microcomputer”).

  The optical system is divided into a light projecting optical system and a light receiving optical system. The illumination light source 21 constituting the light projecting optical system is controlled by the control circuit 40 and functions as an illumination light source that emits illumination light Lf and whose brightness can be adjusted. And a lens provided on the exit side. 1 and 2 conceptually show an example in which the illumination light Lf is irradiated toward the article R to which the information code C is attached.

  The light receiving optical system includes a light receiving sensor 28, an imaging lens 27, a reflecting mirror (not shown), and the like. The light receiving sensor 28 is configured, for example, as a line sensor in which light receiving elements that are solid-state imaging elements such as C-MOS and CCD are arranged one-dimensionally or as an area sensor arranged in two dimensions. An electric signal corresponding to the intensity of the reflected light Lr is output for each pattern. The light receiving sensor 28 is mounted on a printed wiring board (not shown) so as to be able to receive incident light incident through the imaging lens 27.

  The imaging lens 27 functions as an imaging optical system capable of condensing incident light incident from the outside through the reading port 13 and forming an image on the light receiving surface 28a of the light receiving sensor 28. In the present embodiment, after the illumination light Lf emitted from the illumination light source 21 is reflected by the information code, the reflected light Lr is condensed by the imaging lens 27 and a code image is formed on the light receiving surface 28a of the light receiving sensor 28. I am letting you image.

  The microcomputer system includes an amplification circuit 31, an A / D conversion circuit 33, a memory 35, an address generation circuit 36, a synchronization signal generation circuit 38, a control circuit 40, a trigger switch 41, a key operation unit 42, a light emitting unit 43, a buzzer 44, and a vibrator. 45, a liquid crystal display 46, a communication interface 48, and the like. As its name suggests, this microcomputer system is composed mainly of a control circuit 40 and a memory 35 that can function as a microcomputer (information processing device), and the image signal of the information code imaged by the optical system described above is hard-coded. It can perform signal processing in terms of hardware and software.

  The image signal (analog signal) output from the light receiving sensor 28 of the optical system is input to the amplifier circuit 31 and amplified with a predetermined amplification factor, and then input to the A / D conversion circuit 33. The signal is converted to a digital signal. When the digitized image signal, that is, image data (image information) is input to the memory 35, it is stored in the image data storage area. The synchronization signal generation circuit 38 is configured to generate a synchronization signal for the light receiving sensor 28 and the address generation circuit 36, and the address generation circuit 36 is based on the synchronization signal supplied from the synchronization signal generation circuit 38. Thus, the storage address of the image data stored in the memory 35 can be generated.

  The memory 35 is a semiconductor memory device, and corresponds to, for example, a RAM (DRAM, SRAM, etc.) or a ROM (EPROM, EEPROM, etc.). In addition to the above-described image data storage area, the RAM of the memory 35 is configured to be able to secure a work area and a reading condition table used by the control circuit 40 in each processing such as arithmetic operation and logical operation. . The ROM stores in advance a predetermined program that can execute reading processing, analysis processing, and the like, which will be described later, and a system program that can control each hardware such as the illumination light source 21 and the light receiving sensor 28.

  The control circuit 40 is constituted by a microcomputer capable of controlling the entire optical information reading device 10, has a CPU, a system bus, an input / output interface, and the like, and can constitute an information processing device together with the memory 35. It has a function. The control circuit 40 is configured to be connectable to various input / output devices (peripheral devices) via a built-in input / output interface. In the case of the present embodiment, the trigger switch 41, the key operation unit 42, and the light emitting unit. 43, a buzzer 44, a vibrator 45, a liquid crystal display 46, a communication interface 48, and the like are connected.

  As a result, the control circuit 40, for example, monitors and manages the trigger switch 41 that is pressed down when inputting start information for starting reading, and an operation signal that is input according to the operation of the key operation unit 42. Various controls corresponding to the above, turning on / off of the light emitting unit 43 functioning as an indicator for notifying information on reading of the information code, turning on / off of the buzzer 44 capable of generating a beep sound and an alarm sound, and the optical information reading device 10 Drive control of the vibrator 45 capable of generating vibration that can be transmitted to the reading operator, display control of the liquid crystal display 46, communication control of the communication interface 48 enabling serial communication with an external device, and the like are enabled. The trigger switch 41 may correspond to an example of “input means”.

  Further, the control circuit 40 is connected with a three-axis motion sensor 50 as a three-axis acceleration sensor that detects acceleration in the three-axis direction. As shown in FIG. 3, the three-axis motion sensor 50 is configured such that the short side direction (vertical direction in FIG. 3) of the reading port 13 is the x direction and the long direction (in FIG. 3). The acceleration in each direction is detected and the acceleration signal corresponding to the detection result is output to the control circuit 40, with the y direction as the left and right directions and the z direction as the direction orthogonal to the opening surface. . The triaxial motion sensor 50 detects the acceleration in the triaxial direction (x direction, y direction, z direction), and thereby calculates the movement distance and relative position of the optical information reader 10 in the triaxial direction. can do.

  The triaxial motion sensor 50 is a triaxial acceleration sensor that is generally mounted on a mobile device, and outputs a signal for executing an emergency backup by detecting, for example, the fall of the mounted mobile device. In the device provided with the three-axis acceleration sensor, the three-axis acceleration sensor can be used as the three-axis motion sensor 50. The three-axis motion sensor 50 can correspond to an example of “relative position detecting means”.

Next, the characteristic configuration of the present invention will be described below.
During the reading operation, there is a case where the information code to be read is dirty and it is difficult to read. In this case, a control condition (hereinafter also referred to as a reading control condition) related to reading of the information code at this time is present. Since it is not appropriate, decoding of the captured information code may fail. In this case, since a user who cannot recognize an appropriate reading control condition keeps holding the optical information reading device 10 at a reading position where the reading port 13 is directed to the information code, decoding failure is repeated. .

  As the reading control condition, for example, a threshold for binarizing a signal waveform corresponding to reflected light from an information code (hereinafter also referred to as a threshold for binarization), an information code to be read, etc. There are conditions related to image signal processing such as code type. Further, as other reading control conditions, for example, the brightness of the illumination light source 21 irradiated on the information code, the amplification factor of the signal waveform, the exposure condition (exposure time, etc.) when imaging the information code, and the imaging code are used for imaging. There are conditions regarding image signal capture control such as the focal length of the optical system.

  Then, when the failure of the decoding is repeated as described above when the position of the optical information reading device 10 when the trigger switch 41 is pressed to read the information code is set as the reference position, the optical information reading is performed. The apparatus 10 is held in a gripped state (hereinafter also referred to as a reading trial state) so as to be positioned within a predetermined movement range (hereinafter also simply referred to as a predetermined range) with respect to the reference position. On the other hand, by appropriately changing the reading control conditions, decoding may be successful even for information codes that are difficult to read as described above.

  Therefore, in this embodiment, the position of the optical information reader 10 after the trigger switch 41 is pressed is sequentially measured by the reading process executed by the control circuit 40, and the reading trial state continues for a predetermined time. If it is determined that the reading control condition is determined, the reading control condition is automatically changed.

  Hereinafter, the reading process executed by the control circuit 40 in the first embodiment will be described in detail with reference to FIGS. FIG. 4 is a flowchart illustrating the flow of the reading process performed in the first embodiment. FIG. 5 is an explanatory diagram for explaining the movement of the optical information reader 10 when reading an information code that is difficult to read. FIG. 5A shows the optical information reader 10 immediately after the trigger switch 41 is pressed. FIG. 5B shows the position of the optical information reader 10 that is determined to be in the reading trial state even after the determination time Δt has elapsed. FIG. 6 is an explanatory diagram for explaining the relationship between the binarization threshold value and the success or failure of decoding. FIG. 6A shows a signal waveform in which decoding fails due to the initially set binarization threshold value S1. FIG. 6B shows a signal waveform that is successfully decoded by the changed binarization threshold S2.

  The reading process is started when the trigger switch 41 is pressed while the optical information reader 10 can read the information code. First, the initialization process shown in step S101 of FIG. 4 is performed. In this process, the setting described later, specifically, for example, the reading control condition (reading control parameter) is initialized to a preset state, and the reading control condition change count N is initialized to 0 and set. The set reference position is deleted and initialized.

  Next, the reference position setting process shown in step S103 is performed, and the measurement position (for example, the installation position of the three-axis motion sensor 50) of the optical information reading device 10 when the trigger switch 41 is pressed is set as the reference position. Information regarding this reference position is set and stored in the memory 35. Subsequently, the time measurement process shown in step S105 is performed, and the time elapsed t after the trigger switch 41 is pressed is started.

  If the pressing operation of the trigger switch 41 is maintained (Yes in S107), the light receiving process shown in step S109 is performed. In this process, when the illumination light Lf is emitted from the illumination light source 21 and the reflected light Lr from the information code or the like is received by the light reception sensor 28, a light reception signal is input from the light reception sensor 28.

  Next, the binarization process shown in step S111 is performed. In this processing, the signal waveform of the received light signal output from the light receiving sensor 28 is compared with the threshold for binarization, and based on the comparison, the signal waveform is divided into a light color region and a dark color region having a predetermined width value. To do. Subsequently, the decoding process shown in step S113 is performed, and the array data in which the plurality of bright color areas and dark color areas divided as described above are arranged to have a predetermined width value is based on a known decoding method. Decoded. When this decoding process is successful (Yes in S115), predetermined processes such as an output process according to the decoding result are performed, and the reading process is terminated. The control circuit 40 and the light receiving sensor 28 that perform the processes shown in steps S109 to S113 may correspond to an example of “reading unit”.

  On the other hand, since an information code that is difficult to read due to adhesion of dirt or the like is targeted for reading, if the decoding process fails (No in S115), the determination process shown in step S117 is performed, and the optical information reading apparatus 10 It is determined whether or not it is a reading trial state located within a predetermined range. Here, with respect to the reference position, the predetermined range is set such that the movement distance in the x direction is within Δx, the movement distance in the y direction is within Δy, and the movement distance in the z direction is within Δz. Then, the relative distance between the measurement position of the optical information reading apparatus 10 at the time of decoding failure obtained from the detection result of the three-axis motion sensor 50 and the reference position stored in the memory 35 is within Δx, Δy, and Δz. If all of the above are satisfied, it is determined that the optical information reading apparatus 10 is in a reading trial state, and “Yes” is determined in step S117.

  Subsequently, in the determination process shown in step S119, it is determined whether or not the elapsed time t has passed the determination time Δt. The determination time Δt corresponds to an example of “predetermined time”, and is set to 3 to 4 seconds, for example. If the elapsed time t has not passed the determination time Δt (No in S119), step S107 described above is performed. Is processed. Then, the pressing operation of the trigger switch 41 is maintained (Yes in S107), the decoding fails (No in S115), the optical information reader 10 is in the reading trial state (Yes in S117), and the elapsed time t If the determination time Δt has not elapsed (No in S119), the processing from step S107 to step S119 is repeated. The control circuit 40 that performs the process shown in step S119 may correspond to an example of a “determination unit”.

  During the repetition process, when the pressing operation of the trigger switch 41 is released (No in S107) or the optical information reader 10 is carried out of the predetermined range (No in S117), the reading port 13 has been used so far. The processing from step S103 is performed assuming that an information code different from the information code that is directed to is to be read.

  On the other hand, if the elapsed time t has passed the determination time Δt during the repetition process, it is determined Yes in step S119. For example, as illustrated in FIG. 5A, when the measurement position of the optical information reading device 10 when the trigger switch 41 is pressed to read the information code C is set as the reference position (see FIG. 5A). 5), the measurement position of the optical information reading apparatus 10 where the failure of the decoding process is repeated even when the elapsed time t has passed the determination time Δt is illustrated in FIG. 5B. If it is within the predetermined range (see symbol P2 in FIG. 5B), it is determined as Yes in step S119. In FIG. 5, for the sake of convenience, the movement in the xy plane is illustrated, and the predetermined range is illustrated by a region surrounded by a broken line.

  Subsequently, in the determination process shown in step S121, it is determined whether or not the read control condition change count N exceeds the limit count Nth. If the read control condition change count N does not exceed the limit count Nth (in S121). No), the reading control condition changing process shown in step S123 is performed. In this process, the reading control condition is changed based on a predetermined change rule. In the present embodiment, for example, the reading control condition is changed so that the binarization threshold increases or decreases from the initial value by a predetermined value Δθ. Specifically, the binarization threshold is set to an initial value + predetermined value Δθ when N = 1, is set to an initial value−predetermined value Δθ when N = 2, and is set to an initial value + predetermined value Δθ when N = 3. Is set to x2, and N = 4 is set to an initial value−predetermined value Δθ × 2. The control circuit 40 that performs the process shown in step S123 may correspond to an example of “control condition changing means”.

  When the reading control condition is changed as described above, the reading control condition change count N is incremented (N = N + 1) and stored in the memory 35 (S125), and the processing from step S103 is performed. For this reason, the decoding process is performed on the information code received (imaged) with the reading control condition changed. For this reason, for example, in the binarization threshold S1 that is initially set as shown in FIG. 6A, the decoding has failed due to noise (see reference sign D in FIG. 6) due to dirt or the like. However, as shown in FIG. 6B, with the binarization threshold S2 that is changed so as to increase by a predetermined value Δθ with respect to the binarization threshold S1, the influence of noise is removed, and decoding is successful. To do. In addition, as noise caused by dirt or the like, for example, an area originally converted as a black (dark color) area may be partially converted into a white (light color) area due to dirt or the like. This is a case where decoding fails.

  On the other hand, when the elapsed time t has passed the determination time Δt in the reading trial state (Yes in S119), the reading control condition is changed again as long as the reading control condition change count N does not exceed the limit count Nth. The processing from S103 is performed. When the read control condition change count N exceeds the limit count Nth (Yes in S121), it is determined that there is a low possibility of successful decoding even if the read control condition is changed, and this read processing ends.

  As described above, in the optical information reading apparatus 10 according to the present embodiment, reading of the information code has failed, and the optical information reading apparatus 10 falls within the predetermined range from the detection result of the three-axis motion sensor 50. When it is determined that the reading trial state being positioned continues for the determination time Δt (Yes in S119), the reading control condition is automatically changed (S123).

  Thereby, the reading of the information code that could not be read under the reading control condition before the change may be successful. Therefore, the control condition (reading control condition) regarding the reading of the information code is automatically changed, and the reading success rate of the information code can be increased.

  Further, since the predetermined range is set based on the measurement position of the optical information reading apparatus 10 when the trigger switch 41 is pressed, the predetermined range is set based on the actual reading start position. Therefore, it is possible to improve the determination accuracy of the state where the information code is being read (reading attempt state).

  Further, in the determination process in step S119, since it is determined whether or not the elapsed time t in the reading trial state after the start information is input by pressing the trigger switch 41 is continued for the determination time Δt. Therefore, it is possible to increase the determination accuracy of the state where the information code is being read (reading trial state).

  In addition, not only the trigger switch 41 but also having an input means for inputting start information for starting reading of the information code, the optical information reading when the start information is input by the input means. The predetermined range may be set based on the measurement position of the apparatus 10. Further, it is also possible to determine whether or not the elapsed time t in the reading trial state after the start information is input by this input means continues for the determination time Δt, and to determine the predetermined time based on the actual reading start time. Since the comparison is possible, the determination accuracy of the reading trial state can be improved.

[Second Embodiment]
Next, an optical information reading apparatus according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a flowchart illustrating the flow of the reading process in the second embodiment. FIG. 8 is a flowchart illustrating the flow of determination time adjustment processing in the second embodiment.

  In the optical information reading apparatus 10 according to the second embodiment, the reading process described above is shown in FIG. 7 instead of the flowchart shown in FIG. 4 in order to shorten the time until reading success when the reading control condition is changed. The main difference from the optical information reading apparatus according to the first embodiment is that the calculation process is performed based on the flowchart and the determination time adjustment process is separately performed based on the flowchart shown in FIG. Therefore, substantially the same components as those of the optical information reading apparatus of the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  Normally, an information code that is difficult to read due to dirt or the like has a higher number N of read control condition changes by the control condition change process (S123) (the change frequency becomes higher). Then, when the reading control condition change count N increases, it is considered that the reading work environment has many information codes that are difficult to read.

  Therefore, in the present embodiment, in a reading work environment in which the number N of reading control condition changes is relatively large, the reading control condition is shortened by separately performing the determination time adjustment process and adjusting the determination time Δt to be short. Change with time. Thus, even when the reading control condition is changed, the time until the reading control condition is changed to an appropriate reading control condition is shortened, and the time until the reading is successful can be shortened. In the present embodiment, the determination time Δt is initialized to a predetermined set value every time the determination time adjustment process is started.

Hereinafter, the reading process and the determination time adjustment process executed by the control circuit 40 in the second embodiment will be described in detail with reference to FIGS. 7 and 8.
When the reading process is started by pressing the trigger switch 41, an initialization process shown in step S101a of FIG. 7 is performed, and settings such as a reading control condition and a reference position other than the reading control condition change count N are initialized. . Then, if the processing after step S103 is performed and decoding is successful (Yes in S115), the number of successful readings N0 indicating the number of times the information code has been successfully read is incremented (N0 = N0 + 1) and stored in the memory 35 ( S127).

  That is, in the present embodiment, even when the above-described reading process is completed, the reading control condition change count N and the reading success count N0 that are sequentially increased are stored in the memory 35 for a certain period of time. In the reading process according to the present embodiment, the process except that the determination time Δt is adjusted as described later is basically the same as the reading process according to the first embodiment. The control circuit 40 that performs the processes shown in steps S127 and S125 may correspond to an example of “counting unit”.

Next, the determination time adjustment process executed by the control circuit 40 will be described.
The determination time adjustment process is started at the start of the reading process, and after waiting for a predetermined time in the process shown in step S201 of FIG. 8, the determination process shown in step S203 is performed, and the change frequency by the control condition change process is a predetermined frequency. It is determined whether or not the value is higher than a specified value, specifically, whether or not a value obtained by subtracting the number N of reading control condition changes from the number N0 of successful readings is larger than a predetermined number of times threshold value ΔN0. Here, the predetermined number of times threshold value ΔN0 is set to 0 (zero), for example, and when decoding is successful with high probability in a state where the frequency of changing the reading control condition is low, reading from the number of successful readings N0 is performed. The value obtained by subtracting the control condition change count N is larger than the predetermined threshold value ΔN0, and it is determined No in step S203, assuming that the change frequency by the control condition change process is equal to or less than the predetermined specified value. Then, after the number of successful readings N0 and the number N of reading control condition changes are cleared to be equal to 0 in the process shown in step S205, the processes from step S201 are performed.

  On the other hand, after waiting for a certain time, when the read control condition is frequently changed and the success rate of decoding is low even when the change frequency is high, the number of successful readings N0 after waiting for a certain time is, for example, 5. If the reading control condition change count N is 10, it is determined Yes in step S203. In this case, in the process shown in step S207, the determination time Δt is adjusted by using a predetermined value α (for example, 2) larger than 1 so as to be shortened. The control circuit 40 that performs the process shown in step S207 can correspond to an example of a “time adjusting unit”.

  When the determination time Δt is adjusted to be shortened in this way, in the reading process, it is easy to determine Yes in the determination process shown in step S119, and as a result, the reading control condition is changed in a short time. It becomes.

  When the determination time Δt is adjusted to be short as described above, the processing time Δto is adjusted as described above when the processing time required for decoding is Δto in the determination processing shown in step S209. It is determined whether it is longer than the determination time Δt. Here, when the processing time Δto is equal to or shorter than the determination time Δt (No in S209), the number of successful readings N0 and the number of times N of changing the reading control conditions are cleared in the process shown in step S205.

  On the other hand, when the processing time Δto is larger than the determination time Δt (Yes in S209), the determination time Δt is processed in the processing shown in step S211 in order to prevent the determination time Δt from being less than the processing time Δto. It is set to be equal to the time Δto. Then, the number of successful readings N0 and the number N of reading control condition changes are cleared in the process shown in step S205.

  As described above, in the optical information reading apparatus 10 according to the present embodiment, when the change frequency by the control condition changing process is higher than a predetermined specified value, the determination time Δt is set to be equal to or lower than the predetermined specified value. Is adjusted to be shorter than In this way, when the change frequency by the control condition change process is higher than a predetermined specified value, the determination time Δt is set to a predetermined change frequency because it is a reading work environment in which there are many information codes that are difficult to read. By adjusting the reading control condition in a short time by adjusting it to be shorter than the case where the value is less than or equal to the prescribed value, it is possible to shorten the time until the reading is successful.

  In particular, it is determined whether or not the change frequency by the control condition change process is higher than a predetermined specified value by considering the count result of the successful reading number N0 and the read control condition change number N. The change frequency according to the environment can be obtained appropriately.

  The determination as to whether or not the change frequency is higher than a predetermined specified value is not based on the counting results of the number of successful readings N0 and the number of times of changing the reading control condition N, for example, per predetermined reading work time. The determination may be made by comparing the reading control condition change count N with a predetermined specified value.

In addition, this invention is not limited to said each embodiment, For example, you may actualize as follows.
(1) The reading control condition changing process in step S123 is not limited to changing the binarization threshold, but the exposure condition (exposure time) when imaging the signal waveform gain from the light receiving sensor 28 and the information code. Etc.), any one of the focal length of the optical system used for imaging, the brightness of the illumination light source 21 irradiated to the information code, and the code type of the information code to be read may be changed as the reading control condition. . Thus, even if any one of the plurality of control conditions is automatically changed, the success rate of reading the information code that cannot be read under the control condition before the change can be increased.

  FIG. 9 is an explanatory diagram for explaining the relationship between the brightness of the illumination light source 21 and the success or failure of the decoding. FIG. 9A shows a signal waveform in which decoding fails at the initial brightness, and FIG. B) shows a signal waveform that is successfully decoded with the changed brightness. In FIG. 9B, a signal waveform when light is received with the initial brightness is indicated by a wavy line, and a signal waveform when light is received with reduced brightness is indicated by a thick solid line.

  For example, as shown in FIG. 9A, with the default brightness of the illumination light source 21, decoding may fail due to noise (see reference numeral D in FIG. 9) due to dirt or the like. This is because, in some cases, an area converted as a black (dark color) area is partially converted into a white (bright color) area due to dirt or the like, which causes decoding to fail. On the other hand, when the brightness of the illumination light source 21 is lowered as shown in FIG. 9B, the noise portion is also converted into the original black (dark color) region, so that the decoding is successful, and as a result, the information code is successfully read. The rate can be increased.

(2) If it is determined that the reading trial state continues for a predetermined time even if one reading control condition is changed, any one of the plurality of reading control conditions may be changed. . For example, the brightness of the illumination light source 21 can be changed when it is determined that the reading trial state continues for a predetermined time even if the binarization threshold is changed once or a plurality of times. Thereby, since various types of control conditions are changed in order to read one information code, the success rate of reading information codes that could not be read under the control conditions before the change can be further increased.

  In particular, the binarization threshold may be preferentially changed among a plurality of reading control conditions. When the binarization threshold is changed in this way, the processing of steps S109 and S111 can be stopped, and the captured image of the information code that has failed to be read before the binarization threshold is changed can be used. When the information code is successfully read by changing the threshold value, it is possible to eliminate the need for re-imaging (re-light reception) of the information code.

(3) Instead of the three-axis motion sensor 50, the relative position of the optical information reader 10 relative to the reference position may be detected by a relative position detector such as a sensor capable of detecting the movement state of the optical information reader 10. Good.

DESCRIPTION OF SYMBOLS 10 ... Optical information reader 21 ... Illumination light source 28 ... Light receiving sensor (reading means)
40... Control circuit (reading means, determination means, control condition changing means, time adjusting means, counting means)
41 ... Trigger switch (input means)
50 ... 3-axis motion sensor (relative position detecting means)
S1, S2 ... Binarization threshold Δt ... Determination time (predetermined time)

Claims (8)

An optical information reader for optically reading an information code,
Reading means capable of optically reading the information code;
A relative position detecting means for detecting a relative position of the optical information reader with respect to the information code;
It is determined whether or not reading of the information code by the reading unit has failed and a reading trial state in which the optical information reading device is located within a predetermined range continues for a predetermined time from the detection result of the relative position detecting unit. Determination means to perform,
Control condition changing means for changing a control condition related to reading by the reading means when the determination means determines that the reading trial state continues for the predetermined time;
An optical information reading apparatus comprising: Input means for inputting start information for starting reading of the information code by the reading means;
2. The optical information reading apparatus according to claim 1, wherein the predetermined range is set based on a position of the optical information reading apparatus when the start information is input by the input unit.   3. The determination unit according to claim 2, wherein the determination unit determines whether or not a period of time in which the reading is in a trial state continues for the predetermined time after the start information is input by the input unit. Optical information reader.   The control conditions relating to the reading include a threshold value when binarizing a signal waveform corresponding to reflected light from the information code, an amplification factor of the signal waveform, an exposure condition when imaging the information code, It is at least one of a plurality of control conditions of the focal length of the optical system used for imaging, the brightness of the illumination irradiated to the information code, and the code type of the information code to be read. The optical information reading device according to claim 1, wherein the optical information reading device is a device.   The control condition changing unit is configured to change the plurality of control conditions when the determination unit determines that the reading trial state continues for the predetermined time even if any one of the plurality of control conditions is changed. 5. The optical information reading apparatus according to claim 4, wherein any one of the control conditions is changed.   6. The control condition changing means preferentially changes a threshold value when binarizing a signal waveform corresponding to reflected light from the information code among the plurality of control conditions. An optical information reading device described in 1.   When the change frequency by the control condition changing means is higher than a predetermined specified value, the time adjustment means is provided for adjusting the predetermined time to be shorter than when the change frequency is equal to or less than the predetermined specified value. The optical information reader according to any one of claims 1 to 6. A counting means for counting the number of times the information code has been successfully read and the number of changes by the control condition changing means;
The time adjusting means determines that the predetermined frequency is the predetermined frequency when the change frequency by the control condition changing means is determined to be higher than the predetermined specified value from the counting result of the counting means. The optical information reading apparatus according to claim 7, wherein the optical information reading apparatus is adjusted to be shorter than a case where the value is equal to or less than a predetermined value.

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