JP2018055397A - Optical information reader - Google Patents

Abstract

A configuration capable of improving the reading accuracy of optical information without separately providing a device for measuring the distance to the optical information is provided.
A numerical value related to a specific portion of an area occupied by the information code C is acquired in a captured image obtained by imaging the information code C, and a numerical value acquired from the captured image obtained by imaging the information code C and the previous information code C are captured. The amount of change L from the numerical value acquired from the captured image is calculated. When the calculated change amount L is equal to or less than the predetermined value Lth, the decoding result of the information code C is output.
[Selection] Figure 3

Description

  The present invention relates to an optical information reader.

  An optical information reader that optically reads optical information such as information codes (barcodes, two-dimensional codes, etc.) and character information is not only used when the information code is held up in a stationary state, but is also carried around. In some cases, the reading port is directed to the information code or the like. Thus, when the optical information reader is carried and used, if the information code or the like is imaged and decoded while the reading port is close to the information code or the like, the information captured in a blurred state There is a possibility that a problem such as misreading may occur because the code is decoded. This problem may occur not only when the information is carried but also when the information code or the like is captured and decoded while the information code or the like is brought close to the stationary reading port.

  For this reason, it is necessary to prevent reading of an information code or the like that is moving relative to the optical information reader. To solve such a problem, for example, a barcode scanner disclosed in Patent Document 1 below It has been known. This barcode scanner has a high frequency when the barcode label is at the proper focal position because the white / black boundary changes sharply in the captured image, and the one that is far from the appropriate focal position is white / black. The distance to the barcode label is estimated using the tendency to become low frequency because the boundary is unclear and changes gently.

JP 2014-228345 A

  By the way, in the configuration like the barcode scanner disclosed in Patent Document 1, the relationship between the frequency deviation by the frequency analysis of the image and the distance from the barcode scanner of the barcode label is examined in advance for each distance. It is necessary to store it in the storage unit as a distance / normalization correspondence table. Since it is necessary to grasp the distance in advance and create a database in this way, if the reading target changes frequently, it is necessary to prepare a database accordingly, which not only complicates the reading work but also general-purpose There is a problem that the nature is low. On the other hand, a distance sensor or the like for measuring the distance from the optical information reader to the information code or the like can be provided separately. However, the number of parts increases and the manufacturing cost increases. Will occur.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to improve the reading accuracy of the optical information without separately providing a device for measuring the distance to the optical information. To provide a configuration.

In order to achieve the above object, an optical information reading device (10) according to claim 1 of the claims includes:
An imaging unit (23) for imaging optical information (C, M);
A decoding unit (40) for decoding the optical information imaged by the imaging unit;
An output unit (40, 48) for outputting a result of decoding by the decoding unit;
An acquisition unit (40) for acquiring a numerical value relating to a specific portion of a region occupied by the optical information in a captured image obtained by imaging the optical information by the imaging unit;
A numerical value acquired by the acquisition unit from a captured image obtained by imaging the optical information by the imaging unit, and a numerical value acquired by the acquisition unit from a captured image obtained by imaging the optical information by the imaging unit before the previous time. A change amount calculation unit (40) for calculating a change amount (L, ΔS) of
With
The output unit outputs a decoding result by the decoding unit when the change amount calculated by the change amount calculation unit is a predetermined value (Lth, ΔSth) or less.
In addition, the code | symbol in each said parenthesis shows the correspondence with the specific means as described in embodiment mentioned later.

  In the invention of claim 1, a numerical value related to a specific portion of a region occupied by the optical information in a captured image obtained by imaging optical information by the imaging unit is acquired by the acquisition unit, and from the captured image obtained by imaging the optical information by the imaging unit. The amount of change between the numerical value acquired by the acquisition unit and the numerical value acquired by the acquisition unit from the captured image obtained by imaging the optical information by the imaging unit before the previous time is calculated by the change amount calculation unit. Then, when the change amount calculated by the change amount calculation unit is equal to or less than a predetermined value, the decoding result by the decoding unit is output by the output unit.

  The numerical values (for example, the coordinates of each corner and the length of one side) relating to the specific portion of the area occupied by the optical information in the captured image obtained by imaging the optical information at a position relatively close to the imaging unit are relatively It differs from the value at a distant position. That is, when optical information that is relatively moving is continuously imaged by the imaging unit, a numerical value related to a specific portion of a region occupied by the optical information in each captured image changes, and the moving speed increases as the change in the numerical value increases. growing. For this reason, when the amount of change calculated by the amount-of-change calculating unit is equal to or less than a predetermined value, that is, when the optical information is not relatively moved or the relative movement is small, the decoding result by the decoding unit is output. Thus, when the relative movement of the optical information is large, the decoding result obtained by imaging and decoding is not output. Therefore, the reading accuracy of the optical information can be improved without separately providing a device for measuring the distance to the optical information.

  In the invention of claim 2, from the numerical value acquired by the acquisition unit from the captured image obtained by imaging the optical information by the imaging unit and the captured image obtained by imaging the optical information by the imaging unit a predetermined number of times before the second time. The amount of change from the numerical value acquired by the acquisition unit is calculated by the change amount calculation unit. As a result, the amount of change is easily calculated larger than when the amount of change from the previous value is calculated, so the relative movement amount allowed when the decoding result by the decoding unit is output can be easily reduced. It is possible to improve the reading accuracy of the optical information.

  In the invention of claim 3, the number of times that the amount of change calculated by the amount of change calculator is less than or equal to a predetermined value is counted by the counter, and when the number of times counted by the counter is greater than or equal to the predetermined number, The decryption result is output by the output unit. As a result, even if the amount of change calculated by the amount of change calculation unit falls below a predetermined value only once, the decoding result by the decoding unit is not output, and the optical information is not relatively moved or its relative movement is small. Since the decoding result by the decoding unit is output when the frequency of the state is high, the reading accuracy of the optical information can be further improved.

  In the invention of claim 4, when the amount of change calculated by the amount of change calculator exceeds a predetermined value, the number of times counted by the counter is reset. Thereby, since the state in which the optical information is not relatively moved or the state in which the relative movement is small continues, when the amount of change calculated by the amount-of-change calculating unit is continuously below a predetermined value, Since the decoding result by the decoding unit is output, the reading accuracy of the optical information can be improved more reliably.

  According to a fifth aspect of the present invention, the predetermined value is set so as to decrease as the area occupied by the optical information in the captured image captured by the imaging unit decreases. The area occupied by the optical information in the captured image obtained by imaging the optical information at a position relatively far from the imaging unit is smaller than the area of the captured image obtained by imaging the optical information at a relatively close position. . That is, even if the same distance is moved, the change amount calculated by the change amount calculation unit when moving at a relatively far position is larger than the change amount when moving at a relatively close position. Get smaller. For this reason, the relative value with respect to the optical information is taken into consideration by setting the predetermined value, which is a criterion for determining whether or not output is possible, as the area occupied by the optical information in the captured image captured by the imaging unit decreases. Thus, it can be determined whether or not the decryption result can be output.

  In the invention of claim 6, the optical information is an information code having a specific pattern, and a numerical value related to the specific pattern is acquired by the acquisition unit as a numerical value related to the specific portion in the captured image obtained by imaging the information code by the imaging unit. . As a result, even if the optical information is an information code, a numerical value can be acquired by the acquisition unit without decoding the information code for each captured image, and the amount of change can be calculated by the amount of change calculation unit. Further, since the numerical value is not acquired by the acquisition unit, the time from imaging of the information code to the output of the decoding result can be shortened.

  In the invention of claim 7, the optical information is a plurality of character information, and relates to a specific portion of a region occupied by a plurality of character information including an unread character region in a captured image obtained by capturing a plurality of character information by an imaging unit. A numerical value is acquired by the acquisition unit. Therefore, even when a character that was previously undecipherable is decoded this time when a plurality of character information is sequentially captured and decoded, the area occupied by the plurality of character information with respect to a display medium or the like on which the plurality of character information is displayed Can be in the same range as the previous time and this time. Thereby, the dispersion | variation in the numerical value acquired in an acquisition part resulting from an unread character area | region can be eliminated.

  In the invention of claim 8, when the amount of change calculated by the amount of change calculator becomes equal to or less than a predetermined value, the decoding results by the decoding unit of all the optical information whose numerical values are acquired by the acquisition unit match. The result of decoding by the decoding unit is output by the output unit. As a result, even if the optical information is not relatively moved or the relative movement is small, if the respective decoding results do not match, the decoding results will not be output. Can be prevented, and the reading accuracy of optical information can be further improved.

1 is a perspective view schematically showing an optical information reading apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram schematically showing an electrical configuration of the optical information reading device in FIG. 1. It is explanatory drawing for demonstrating the calculation method of variation | change_quantity regarding the information code imaged this time in 1st Embodiment, and the information code imaged last time. 4 is a flowchart illustrating a flow of reading processing performed by the optical information reading device in the first embodiment. It is explanatory drawing explaining the relative distance of an optical information reader and an information code. FIGS. 6A and 6B are explanatory diagrams for explaining the relationship between the optical information reading device and the relative distance between the information codes and the captured image. FIG. 6A shows the captured image at T1 in FIG. 5 and FIG. 6C shows a captured image at T2, FIG. 6C shows a captured image at T3 in FIG. 5, and FIG. 6D shows a captured image at T4 in FIG. It is explanatory drawing explaining the relationship between the time change of the variation | change_quantity L calculated in 1st Embodiment, and the predetermined value Lth. It is a flowchart which illustrates the flow of the reading process performed with the optical information reader in 2nd Embodiment. It is explanatory drawing explaining the relationship between the time change of the variation | change_quantity L calculated in 2nd Embodiment, and the predetermined value Lth. It is a flowchart which illustrates the flow of the reading process performed with the optical information reader in 3rd Embodiment. It is explanatory drawing explaining the length of the upper edge of the square area which the some character information imaged last time occupies, and the length of the upper edge of the square area which the some character information imaged this time occupies. Explanatory drawing explaining the length of the upper edge of the rectangular area occupied by the plurality of character information captured last time and the length of the upper edge of the rectangular area occupied by the plurality of character information captured this time when there is an unread character area It is.

[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.
The optical information reader 10 shown in FIGS. 1 and 2 is configured as a portable reader that optically reads optical information such as information codes (bar codes, two-dimensional codes, etc.) and character information. There is an appearance as a so-called gun type, and a circuit unit 20 made of various electric parts and the like is housed in a case 11 made of a synthetic resin such as ABS resin.

  The optical information reader 10 has a main body portion 12 formed with a reading port 13 that allows illumination light and reflected light to pass through at an end thereof, and a portion different from a portion of the main body portion 12 where the reading port 13 is formed. And a grip portion 15 that is connected and gripped by a user. An extension portion 14 is provided below the reading port 13 in the main body portion 12, and this extension portion 14 can be moved even if the extension end portion 14 a is brought into contact with a reading target to which an information code or the like is attached. The upper portion is formed in a substantially U shape so that the information code and the like can be viewed from above. The grip portion 15 extends downward from the lower wall portion of the main body portion 12, a trigger switch 42 that can be pressed is disposed near the upper end portion of the grip portion 15, and an interface is disposed near the lower end portion of the grip portion 15. Cable (not shown) is assembled.

Next, the electrical configuration of the optical information reader 10 will be described with reference to the drawings.
As shown in FIG. 2, the circuit unit 20 accommodated in the case 11 mainly includes an optical system such as an illumination light source 21, a light receiving sensor 23, and an imaging lens 25, and a microcomputer (such as a memory 35 and 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 functions as illumination means capable of emitting the illumination light Lf, and is composed of, for example, a red LED and a lens provided on the emission side of the LED.

  The light receiving optical system includes a light receiving sensor 23, an imaging lens 25, and the like. The light receiving sensor 23 is configured as an area sensor in which light receiving elements that are solid-state imaging elements such as C-MOS and CCD are two-dimensionally arranged, and has a light receiving surface 23a as a rectangular light receiving area. It is configured. The light receiving sensor 23 is mounted on a printed wiring board (not shown) so that incident light incident through the imaging lens 25 can be received by the light receiving surface 23a. The light receiving sensor 23 may correspond to an example of an “imaging unit”.

  The imaging lens 25 functions as an imaging optical system capable of condensing incident light incident from the outside via the reading port 13 and forming an image on the light receiving surface 23 a of the light receiving sensor 23. In the present embodiment, the illumination light Lf emitted from the illumination light source 21 is reflected by the information code C or the reading object R to which the information code C is attached, and the reflected light Lr is reflected by the imaging lens 25. And a code image is formed on the light receiving surface 23 a of the light receiving sensor 23.

  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 42, a light emitting unit 43, a buzzer 44, a vibrator 45, and a communication interface 48. Etc.

  An image signal (analog signal) output from the light receiving sensor 23 of the optical system is input to the amplifier circuit 31 to be amplified with a predetermined gain, and then input to the A / D conversion circuit 33 to be converted into a digital signal from the analog signal. Is converted to The digitized image signal, that is, image data (image information) is input to a memory 35 constituted by a known storage medium such as a ROM or a RAM, and is accumulated in a predetermined storage area. The synchronization signal generation circuit 38 is configured to generate a synchronization signal for the light receiving sensor 23 and the address generation circuit 36. 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 control circuit 40 is a microcomputer capable of controlling the entire optical information reading device 10 and includes a CPU, a system bus, an input / output interface, and the like, and can constitute an information processing device together with the memory 35 and has an information processing function. . The control circuit 40 is configured to be connectable to various input / output devices via a built-in input / output interface. In the case of this embodiment, the trigger switch 42, the light emitting unit 43, the buzzer 44, the vibrator 45, A communication interface 48 or the like is connected. Thereby, for example, monitoring and management of the trigger switch 42, lighting and non-lighting of the light emitting unit 43, turning on / off of the buzzer 44 capable of generating a beep sound and an alarm sound, driving control of the vibrator 45, control of the communication interface 48, etc. Is possible.

Next, a reading process performed by the control circuit 40 of the optical information reading apparatus 10 will be described.
In the reading process in the present embodiment, a numerical value related to a specific portion of the area occupied by the information code in the captured image obtained by capturing the information code is acquired, and the amount of change between the numerical value and the numerical value acquired in the same manner as the previous time is equal to or less than a predetermined value. In this case, the decoding result of the information code is output.

  A numerical value related to a specific portion of a region occupied by the information code in the captured image obtained by imaging the information code at a position relatively close to the optical information reader 10 (light receiving sensor 23), specifically, for example, each corner Are different from the coordinates (numerical values) of the corners at relatively distant positions. That is, when the information code that is relatively moving is continuously imaged by the light receiving sensor 23, the numerical value (for example, the coordinates of each corner) regarding the specific portion of the area occupied by the information code in each captured image changes. The greater the change, the greater the moving speed. In this way, an information code captured with a high moving speed is likely to be blurred, and even if decoding is successful, it may be misread due to blurring. In the present embodiment, it is assumed that captured images are generated by the light receiving sensor 23 at intervals of 200 ms, for example.

  Therefore, in the present embodiment, the coordinates of each corner are adopted as numerical values related to the specific portion of the area occupied by the information code, and the total value of the differences from the coordinates of each corner acquired last time is calculated as the amount of change. For example, as shown in FIG. 3, the coordinates (X1a, Y1a) (X1b, Y1b) (X1c, Y1c) (X1d, Y1d) of each corner acquired this time and the coordinates (X0a, Y0a) of each corner acquired last time ) (X0b, Y0b) (X0c, Y0c) The sum of the differences La, Lb, Lc, and Ld from (X0d, Y0d) is calculated as a change amount L (= La + Lb + Lc + Ld). The difference La corresponds to the distance between (X1a, Y1a) and (X0a, Y0a), the difference Lb corresponds to the distance between (X1b, Y1b) and (X0b, Y0b), and the difference Lc is This corresponds to the distance between (X1c, Y1c) and (X0c, Y0c), and the difference Ld corresponds to the distance between (X1d, Y1d) and (X0d, Y0d).

  When the calculated change amount L is equal to or less than the predetermined value Lth, that is, when the information code is not relatively moved or when the relative movement is small, the decoding result of the information code is output. When the relative movement (moving speed) of the information code is large, the output of the decoded result that is imaged and decoded is prevented. The predetermined value Lth is set to a value corresponding to the amount of change L when the relative movement of the information code is small according to the reading work environment or the like. Further, FIG. 3 shows a state in which the information code (refer to the solid line frame C1) captured this time and the information code (refer to the two-dot chain line frame C0) captured last time are included in one captured image P for convenience.

  Hereinafter, the reading process executed by the control circuit 40 in the present embodiment will be described in detail with reference to the flowchart shown in FIG. Hereinafter, a case where a barcode is employed as the information code C will be described.

  A reading process is started by the control circuit 40 when the trigger switch 42 is pressed while moving the optical information reading device 10 so that the reading port 13 (extending end portion 14a) approaches the information code C. First, the imaging process shown in step S101 of FIG. 4 is performed. In this process, the illumination light Lf is emitted from the illumination light source 21 and the reflected light Lr from the information code C or the like is received by the light receiving sensor 23 to generate a captured image. Subsequently, in the decoding process shown in step S103, a known decoding process for decoding the information code C is performed on the captured image. For example, if the decoding process fails because the distance to the information code C is too far ( No in S105), the processing from step S101 is repeated. The control circuit 40 that performs the process of step S103 may correspond to an example of a “decoding unit”.

  When the captured information code C is successfully decoded (Yes in S105), the numerical value acquisition process shown in step S107 is performed. In this process, as shown in FIG. 3, in the captured image generated in step S101, the coordinates (X1a, Y1a) (X1b, Y1b) of each corner are used as numerical values related to the specific portion of the area occupied by the information code C. ) (X1c, Y1c) (X1d, Y1d) is acquired. Note that the control circuit 40 that performs the process of step S107 may correspond to an example of an “acquisition unit”.

  Subsequently, in the determination process shown in step S <b> 109, it is determined whether or not the previous coordinates of each corner acquired for the information code C are stored in the memory 35. Here, when the coordinates of each corner are acquired for the first time, it is determined No in step S109, and the coordinates of each corner acquired in step S107 are the previous coordinates of each corner. It is stored in the memory 35 (S111). Then, the processing from step S101 is repeated.

  Then, the information code C captured next is successfully decoded (Yes in S105), the coordinates of each corner are acquired from the captured image (S107), and the previous coordinates of each corner are stored in the memory 35. (Yes in S109), the change amount calculation process shown in step S113 is performed. In this process, as illustrated in FIG. 3, the total value of the differences between the coordinates of each corner acquired this time and the coordinates of each corner acquired last time is calculated as the change amount L. If the amount of change L exceeds the predetermined value Lth (No in S115), the processing after step S111 is performed assuming that the information code C having a large moving speed (relative movement) is being imaged. That is, since the reading port 13 is in the process of approaching the information code C, the decoding result is not output while the change amount L calculated in step S113 exceeds the predetermined value Lth. The control circuit 40 that performs the process of step S113 may correspond to an example of a “change amount calculation unit”.

  On the other hand, if the information code C has not moved relative to the information code C because the reading port 13 has been brought close to the information code C, or the relative movement is small, the change amount L calculated in step S113 is small. When the amount of change L thus reduced becomes equal to or smaller than the predetermined value Lth (Yes in S115), the output process shown in step S117 is performed. In this process, the decoding result (decoding result) decoded in step S103 for the current captured image is output to an external device or the like via the communication interface 48 and the cable. Note that the control circuit 40 and the communication interface 48 that perform the process of step S117 may correspond to an example of an “output unit”.

  Here, with reference to FIGS. 5 to 7, a process in which the change amount L exceeds the predetermined value Lth and below the predetermined value Lth will be described including the movement of the optical information reader 10. In FIG. 5, the positions of the extended end portions 14 a when the optical information reader 10 is brought close to the information code C are shown as T1 to T4 in order. 6A shows a captured image at T1 in FIG. 5, FIG. 6B shows a captured image at T2 in FIG. 5, and FIG. 6C shows T3 in FIG. FIG. 6D shows a captured image at T4 in FIG.

  When the optical information reader 10 is brought close to the information code C, when the information code C is successfully decoded for the first time for the captured image taken at the point T1 in FIG. 5, the coordinates of the previous corners are stored in the memory 35. Since it is not performed (No in S109), the change amount L is not calculated, and the coordinates of each corner shown in FIG. 6A are stored in the memory 35 (S111). Then, when the same information code C is successfully decoded for the captured image captured at the next point T2, and the coordinates of each corner are acquired (Yes in S109), FIG. 6 (B) acquired and acquired this time. The total value of the difference between the coordinates of each corner shown in FIG. 6 and the previous coordinates of each corner (see FIG. 6A) stored in the memory 35 is calculated as the change amount L (S113). In this case, as shown in FIGS. 6 (A) and 6 (B), the difference becomes large, and therefore, as indicated by T2 in FIG. 7, the change amount L exceeds the predetermined value Lth ( No in S115), the decoding result is not output.

  Then, the coordinates of each corner shown in FIG. 6C acquired from the captured image taken at the next point T3 and the previous coordinates of each corner stored in the memory 35 (see FIG. 6B). Is calculated as the change amount L (S113). In this case, as shown in FIGS. 6 (B) and 6 (C), the state in which the difference is large continues, and the change amount L exceeds the predetermined value Lth as indicated by T3 in FIG. Therefore, the decoding result is not output even in this imaging state.

  Then, the coordinates of each corner shown in FIG. 6D acquired from the captured image taken at the next point T4 and the previous coordinates of each corner stored in the memory 35 (see FIG. 6C). Is calculated as the change amount L (S113). In this case, as can be seen from FIGS. 6C and 6D, the difference is small, and the change amount L is not more than the predetermined value Lth as indicated by T4 in FIG. 7 (Yes in S115). The decoding result is output assuming that the optical information reader 10 is sufficiently close to the information code C and the information code C is not relatively moved or its relative movement is small (S117).

  As described above, in the optical information reading apparatus 10 according to the present embodiment, numerical values (coordinates of each corner) regarding a specific portion of the area occupied by the information code C in the captured image obtained by capturing the information code C are acquired. (S107) The amount of change L between the numerical value acquired from the captured image obtained by capturing the information code C and the numerical value acquired from the captured image obtained by capturing the previous information code C is calculated (S113). When the calculated change amount L is equal to or less than the predetermined value Lth, the decoding result (decoding result) of the information code C is output.

  As described above, when the calculated change amount L is equal to or smaller than the predetermined value Lth, that is, when the information code C is not relatively moved or when the relative movement is small, the decoding result is output, whereby the information code C When the relative movement of is large, a decoded result that is imaged and decoded is not output. Therefore, the reading accuracy of the information code C can be improved without separately providing a device for measuring the distance to the information code C.

  In the change amount calculation process in step S113, the total value of the differences between the coordinates of each corner acquired this time and the coordinates of each corner acquired last time is not limited to being calculated as the change amount L. The total value of the differences from the coordinates of each corner acquired two or more times before a predetermined number of times (for example, two times before or three times before) may be calculated as the change amount L. The coordinates (numerical value) of each corner acquired before the previous time are the coordinates (numerical value) of each corner acquired last time and the coordinates (numerical value) of each corner acquired a predetermined number of times before two or more times. And include.

  This makes it easier to calculate the amount of change L compared to the case of calculating the amount of change L from the previous numerical value as described above, so the relative movement amount allowed when the decoding result is output can be set. It can be easily reduced, and the reading accuracy of the information code C can be further 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.
The second embodiment is mainly different from the first embodiment in that the decoding result (decoding result) of the information code C is output when the state where the change amount L is equal to or less than the predetermined value Lth continues. For this reason, substantially the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  When outputting the decoding result (decoding result) of the information code C because the calculated change amount L is equal to or less than the predetermined value Lth as in the first embodiment, for example, the optical information reading device 10 receives the information Since the movement of the optical information reader 10 is temporarily reduced in a state where it is not sufficiently close to the code C, if the change amount L is equal to or smaller than the predetermined value Lth, a decoding result that may be misread may be output. is there.

Therefore, in the present embodiment, the decoding result of the information code C is output when the calculated change amount L is continuously equal to or less than the predetermined value Lth.
Hereinafter, the reading process executed by the control circuit 40 in the present embodiment will be described in detail with reference to the flowchart shown in FIG.

  As in the first embodiment, when the information code C is successfully decoded for the first time (Yes in S105 in FIG. 8) and the coordinates of each corner are acquired (S107), the previous coordinates of each corner are changed. Since it is not stored in the memory 35 (No in S109), in step S119, N indicating the number of times the change amount L is continuously equal to or less than the predetermined value Lth is reset to 0 (zero). Then, when the processing after step S111 is performed and the change amount L calculated by successfully decoding the same information code C and acquiring the coordinates of each corner becomes equal to or less than the predetermined value Lth (Yes in S115) In step S121, the count N is incremented (N = N + 1). The control circuit 40 that performs the process of step S121 may correspond to an example of a “counter”.

  Then, in the determination process of step S123, it is determined whether or not the incremented number N is equal to or greater than the predetermined number Nth. Here, in this embodiment, the predetermined number of times Nth is set to, for example, three times, and it is determined No in step S123 until the number of times N becomes equal to or greater than the predetermined number of times Nth. Made.

  As shown in FIG. 9, when the change amount L exceeds the predetermined value Lth in the second and third imaging (T2, T3) (No in S115), the number of times N is reset to zero. (S119) When the amount of change L is equal to or smaller than the predetermined value Lth in the next imaging (T4) (Yes in S115), the number of times N is counted so as to be incremented to 1 (S121). If the state in which the amount of change L remains the predetermined value Lth continues in the next imaging (T5) (Yes in S115), the number N is counted so as to be incremented to 2 (S121). After that, since the movement of the optical information reader 10 with respect to the information code C is temporarily accelerated, if the amount of change L exceeds the predetermined value Lth in the subsequent imaging (T6) (No in S115), the number N = It is reset to 0 (S119).

  Thereafter, when the optical information reader 10 is sufficiently close to the information code C and the information code C is not relatively moved or its relative movement is small, the change amount L continues at T7, T8, and T9. The number is counted so as to be equal to or less than the predetermined value Lth and incremented to N = 3 (S121). As a result, the number N is equal to or greater than the predetermined number Nth (Yes in S123), and the decoding result (decoding result) decoded in step S103 is output to an external device or the like (S117).

  As described above, in the optical information reading apparatus 10 according to the present embodiment, the number N of times when the calculated change amount L is equal to or less than the predetermined value Lth is counted (S121), and the counted number N is the predetermined number Nth. If this is the case (Yes in S123), the decoding result (decoding result) of the information code C is output (S117). Thereby, even when the calculated change amount L is less than the predetermined value Lth only once, the decoding result is not output, and the information code C is not relatively moved or the relative movement is small. Since the decoding result is output, the reading accuracy of the information code C can be further improved.

  In particular, when the calculated change amount L exceeds the predetermined value Lth, the counted number N is reset (S119). As a result, since the information code C is not relatively moved or the relative movement is small, the information code C is determined when the calculated change amount L is continuously equal to or less than the predetermined value Lth. Therefore, the reading accuracy of the information code C can be improved more reliably.

  In the reading process of the present embodiment, when the information code C is successfully decoded, not only the coordinates of each corner are acquired, but also when the specific pattern of the information code is read, the numerical value related to this specific pattern is You may get it. For example, if the information code C is a QR code (registered trademark) having a specific pattern such as a position detection pattern (FP pattern), numerical values related to the positions and sizes of the three position detection patterns may be acquired. The same applies to the reading process of the first embodiment.

  Thereby, the numerical value can be obtained without decoding the information code C for each captured image, and the amount of change L can be calculated. Since the decoding of the information code C has failed, the numerical value is not acquired. The time from imaging to output of decoding results can be shortened.

  Further, in the reading process of the present embodiment, after the counted number N becomes equal to or greater than the predetermined number Nth (Yes in S123), if the decoding results of all the information codes C from which the numerical values are acquired match, The matching decoding result may be output in step S117. Further, also in the reading process of the first embodiment, after the calculated change amount L becomes equal to or less than the predetermined value Lth (Yes in S115 in FIG. 4), the decoding results of all the information codes C from which numerical values are acquired. May match, the matching decoding result may be output in step S117.

  As a result, even if the information code C is not relatively moved or the relative movement is small, the decoding result is not output if the respective decoding results do not match. Can be prevented, and the reading accuracy of the information code C can be further improved.

[Third Embodiment]
Next, an optical information reading apparatus according to a third embodiment of the present invention will be described with reference to the drawings.
The third embodiment is mainly different from the first embodiment in that not only the information code but also a plurality of character information is optically read as optical information. For this reason, substantially the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The optical information reader 10 according to this embodiment not only optically reads an information code as in the first embodiment but also a plurality of characters captured using a known character recognition process (OCR process). It functions to read information optically.

  At that time, in the reading process performed by the optical information reading apparatus 10, when at least a part of the plurality of character information M is read from the captured image (S103a in FIG. 10), as shown in FIGS. In addition, in a captured image obtained by capturing a plurality of character information M, the length Su1 of the upper edge of the rectangular region S occupied by the plurality of character information M (FIG. 11) is used as a numerical value regarding a specific portion of the region occupied by the plurality of character information M. (See (B)) is obtained (S107a), and the difference from the length Su0 (see FIG. 11A) of the upper edge of the rectangular region S obtained last time is calculated as the change amount ΔS (S113a). When the calculated change amount ΔS is equal to or smaller than the predetermined value ΔSth (Yes in S115a), that is, when the plurality of character information M is not relatively moved or when the relative movement is small, By outputting the decryption result of the character information M, the output of the decryption result captured and decrypted when the relative movement (movement speed) of the plurality of character information M is large is prevented. The predetermined value ΔSth is set to a value corresponding to the change amount ΔS when the relative movement of the plurality of character information M is small according to the reading work environment or the like.

  In particular, in the reading process according to the present embodiment, when there is an undecipherable character among a plurality of imaged character information M, the area occupied by this character is set as an unread character area M0 (see FIG. 12A). The length Su1 of the upper edge of the rectangular area S occupied by a plurality of pieces of character information M including the character area M0 is acquired (S107a). For example, the captured images in FIGS. 12A and 12B are the same as the plurality of character information M included in the captured images in FIGS. 11A and 11B, and are illustrated in FIG. As described above, the unread character area M0 is set according to the recognition that there is a character that cannot be decoded even if the leftmost character cannot be decoded. Then, the length of the upper edge of the rectangular region S occupied by the plurality of character information M including the unread character region M0 is acquired.

  Thus, in the present embodiment, the optical information is a plurality of character information M, and a square shape occupied by the plurality of character information M including the unread character region M0 in the captured image obtained by capturing the plurality of character information M. The length of the upper edge of the region is obtained. Therefore, when a plurality of character information M is sequentially imaged and decoded, a plurality of character information M is displayed for a display medium or the like on which the plurality of character information M is displayed even if a character that could not be decoded previously is decoded this time. The rectangular region S occupied by can be made the same range in the previous time and this time. Thereby, the dispersion | variation in the numerical value acquired resulting from the unread character area | region M0 can be eliminated.

  Also in the present embodiment, as in the second embodiment, when a state in which the change amount ΔS is equal to or less than the predetermined value ΔSth continues, decoding results of a plurality of character information M may be output. . In addition, after the calculated change amount ΔS becomes equal to or less than the predetermined value ΔSth, when the decoding results of all the plurality of character information M for which the numerical values are obtained match except for the unread character area M0, the matching decoding is performed. The result may be output.

In addition, this invention is not limited to said each embodiment and modification, For example, you may actualize as follows.
(1) In the reading process, the predetermined value Lth may be set to be smaller as the area occupied by the information code is smaller in the captured image. The area occupied by the information code in the captured image obtained by imaging the information code at a position relatively far from the optical information reader 10 (light receiving sensor 23) is a captured image obtained by imaging the information code at a relatively close position. It becomes smaller than the area. That is, even if the same distance is moved, the change amount L calculated when moving at a relatively far position is larger than the change amount L calculated when moving at a relatively close position. Get smaller. For this reason, by setting the predetermined value Lth, which is a criterion for determining whether or not output is possible, to be smaller as the area occupied by the information code in the captured image becomes smaller, whether or not the decoding result can be output in consideration of the relative distance to the information code. Can be judged. The same effect can be obtained even if the predetermined value ΔSth is set to be smaller as the area occupied by a plurality of character information in the captured image is smaller.

(2) In the reading process, the numerical values related to the specific portion of the area occupied by optical information such as an information code and a plurality of character information are the coordinates of each corner as in the first and second embodiments, and the third embodiment. The length is not limited to the length of the upper edge of the rectangular region such as the form, and may be, for example, the length of the periphery of the region occupied by the optical information, the length of the diagonal, or the coordinates of a specific portion. In particular, when the amount of change is calculated by acquiring the coordinates of a specific part such as the coordinates of each corner, even if the optical information moves relatively parallel to the reading port, it corresponds to the movement. Since the amount of change can be calculated, the reading accuracy of optical information can be further improved.

(3) In the above reading process, the decoding result of the optical information (information code, plural character information, etc.) is not limited to being output to an external device or the like. For example, an optical information reading device having a display screen If there is, it may be output to be displayed on the display screen.

(4) The present invention is not limited to being applied to a portable optical information reader, but may be applied to a stationary optical information reader.

DESCRIPTION OF SYMBOLS 10 ... Optical information reader 23 ... Light receiving sensor (imaging part)
40 ... Control circuit (decoding unit, acquisition unit, change amount calculation unit, output unit, count unit)
48 ... Communication interface (output unit)
C ... Information code (optical information)
L, ΔS: Change amount Lth, ΔSth: Predetermined value M: Plural character information (optical information)
M0 ... Unread character area N ... Number of times Nth ... Predetermined number of times

Claims (8)

An imaging unit for imaging optical information;
A decoding unit for decoding the optical information imaged by the imaging unit;
An output unit for outputting a decoding result by the decoding unit;
An acquisition unit that acquires a numerical value related to a specific portion of a region occupied by the optical information in a captured image obtained by imaging the optical information by the imaging unit;
A numerical value acquired by the acquisition unit from a captured image obtained by imaging the optical information by the imaging unit, and a numerical value acquired by the acquisition unit from a captured image obtained by imaging the optical information by the imaging unit before the previous time. A change amount calculation unit for calculating a change amount of
With
The output unit outputs the decoding result by the decoding unit when the change amount calculated by the change amount calculation unit is a predetermined value or less.   The change amount calculation unit is configured to obtain the optical information by the imaging unit at a predetermined number of times before the numerical value acquired by the acquisition unit from the captured image obtained by imaging the optical information by the imaging unit and two or more times before. The optical information reading device according to claim 1, wherein an amount of change from a numerical value acquired by the acquisition unit is calculated from a captured image. A counting unit that counts the number of times the amount of change calculated by the amount of change calculating unit is equal to or less than the predetermined value;
3. The optical information reader according to claim 1, wherein the output unit outputs a decoding result by the decoding unit when the number of times counted by the counting unit is equal to or greater than a predetermined number.   The optical information reading apparatus according to claim 3, wherein the count unit resets the number of times when the change amount calculated by the change amount calculation unit exceeds the predetermined value.   The said predetermined value is set so that it may become so small that the area | region which the said optical information occupies becomes small in the picked-up image imaged by the said image pick-up part. Optical information reader. The optical information is an information code having a specific pattern,
The said acquisition part acquires the numerical value regarding the said specific pattern as a numerical value regarding the said specific part in the captured image which imaged the said information code with the said imaging part, The Claim 1 characterized by the above-mentioned. Optical information reader. The optical information is a plurality of character information,
When the area occupied by characters unreadable by the decoding unit among the plurality of character information imaged by the imaging unit is an unread character region,
The said acquisition part acquires the numerical value regarding the specific part of the area | region which the said several character information occupies including the said unread character area | region in the captured image which imaged the said several character information with the said imaging part. The optical information reading device according to any one of 1 to 5.   The output unit outputs the decoding results by the decoding unit of all the optical information whose numerical values are acquired by the acquisition unit when the change amount calculated by the change amount calculation unit is equal to or less than the predetermined value. The optical information reading device according to any one of claims 1 to 7, wherein in the case of coincidence, a decoding result by the decoding unit is output.

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