JP5724771B2 - Optical information reader - Google Patents

Description

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

  2. Description of the Related Art Conventionally, a handy terminal disclosed in Patent Document 1 below is known as an optical information reading device that optically reads an information code (optical information). In this handy terminal, an opening as a data intake is formed on the front surface, and an opening continuous from the data intake is formed on a side surface of the handy terminal. These openings are closed by a transparent plate appropriately coated to prevent reflection of light from the outside. In the handy terminal, an irradiation device that mainly irradiates a data symbol (information code) with a predetermined amount of light and an information capture device that captures the read information are provided. In this handy terminal, the data intake is blocked by a non-reflective coating transparent plate, so that the irradiation device is not exposed to the outside, so that the amount of irradiation light is significantly lost due to scratches and dirt. This suppresses malfunctions that occur.

  Further, in the barcode reader disclosed in Patent Document 2 below, when the brightness of reflected light from the barcode is captured by the CCD, the information is quantized by the A / D converter at a gray scale having a predetermined number of gradations. Is done. The quantized information is binarized by calculating a gray scale distribution, analyzing the calculated distribution, and setting a threshold value. When the barcode arrangement pattern is identified from the binarized data by the identification unit, the barcode conversion is completed by converting the arrangement pattern into code data such as alphanumeric characters by the data conversion unit. . In this way, even if the barcode itself has become faint, the captured reflected light is not immediately binarized, but is once captured in gray scale and binarized in consideration of the tendency. Thus, the information indicated by the barcode is read more accurately.

JP-A-10-228518 JP 09-297807 A

  By the way, in a stationary optical information reader that optically reads an information code such as a barcode or a two-dimensional code installed in a store or an entrance, the reading opening is often arranged upward, and the inside of the housing In order to protect the light receiving means and the like that are arranged in the light receiving light reflected from the information code through the reading port, a light-proof dust-proof plate is disposed in the opening.

  However, if dirt is attached or damaged to a protective member such as a dust-proof plate that protects the reading port, reading will not only fail, but it will be misread by judging the imaged dirt and damage as dark areas. May end up. Such misreading is a problem that may occur not only in a stationary reader, but also in a portable reader, a handy terminal disclosed in Patent Document 1, and the like. In addition, the barcode reader disclosed in Patent Document 2 has a problem that even if the barcode itself can be corrected for blurring, it cannot prevent misreading due to dirt or damage generated on the protective member. is there.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide an optical reading that can prevent misreading caused by dirt or damage generated on a protective member that protects a reading port. To provide an apparatus.

To achieve the above object, the optical information reader according to claim 1 picks up the QR code by receiving the reflected light (Lr) from the QR code (C) through the reading port (13). An optical information reader (10) comprising: an imaging means (28) for performing decoding; and a decoding means (40) for decoding the QR code based on a code image of the QR code imaged by the imaging means. The protective member (14) that covers the reading port so that the reflected light can be transmitted and protects the reading port, and the captured images (P1, P2) captured by the imaging unit are sequentially stored. If there is a dark color system area whose shape and brightness do not change in common between the storage means (35) and the captured image captured by the imaging means and the captured image stored in the storage means, this dark color Detection means (40) for detecting the system area (S) as an invariant area, and the decoding means includes the invariant area when the invariant area detected by the detection means is included in the code image. The code image is decoded only when the ratio of the code image to the code image does not affect the decoding.

The invention described in claim 2 is the optical information reading apparatus according to claim 1, wherein the detecting means includes a plurality of captured images stored in the storage means and the captured image captured by the imaging means If there is a dark color region that does not change in shape and brightness in common, the dark color region is detected as the invariant region.

According to a third aspect of the present invention, in the optical information reading device according to the first or second aspect, when the invariable region is detected by the detection means, a notification for informing maintenance information that prompts maintenance of the protection member. Means (43) are provided.

According to a fourth aspect of the present invention, in the optical information reading device according to the third aspect , the informing means detects the invariable area detected by the detection means with respect to the captured image captured by the imaging means. The maintenance information is notified when the ratio (Sr) occupies is such that it affects decoding.

According to a fifth aspect of the present invention, in the optical information reading apparatus according to the third or fourth aspect , the notifying unit is configured to capture the captured image captured by the imaging unit when the power is turned on and the storage only when the power is turned on. When there is a dark color region where the shape and brightness do not change in common with the captured image stored in the means, the maintenance information is notified when the dark color region is detected as the invariable region by the detection means It is characterized by that.
In addition, the code | symbol in each said parenthesis shows the correspondence with the specific means as described in embodiment mentioned later.

According to the first aspect of the present invention, when there is a dark color region where the shape and the luminance do not change in common between the captured image captured by the image capturing unit and the captured image stored in the storage unit, the dark color region is detected by the detection unit. Is detected as an invariant region. When the invariant area detected by the detecting means is included in the code image, the code image is only included in the code image only when the ratio of the invariant area to the code image does not affect the decoding. Decoding is done.

As a result, dirt adheres to or damages the protective member that covers and protects the reading port. Therefore, even when the dirt or damage is imaged as a dark color area, the dark color area is defined as the invariant area. If it is detected and the proportion of the invariant area to the code image is such that the decoding is affected, the decoding is not performed, so that the protective member causing the invariant area is contaminated or damaged. It is possible to reliably prevent misreading caused by.
Accordingly, it is possible to prevent erroneous reading due to dirt or damage generated on the protective member that protects the reading port.

In the invention of claim 2 , when there is a dark color region in which the shape and brightness do not change in common between the captured image captured by the image capturing unit and the plurality of captured images stored in the storage unit, the dark color region is It is detected as the invariant region by the detecting means. Thus, the comparison accuracy using the plurality of captured images can improve the detection accuracy of the invariant region.

In the invention of claim 3 , when the invariable area is detected by the detecting means, that is, when dirt adheres to the protective member or damage occurs, the maintenance information is notified by the notifying means, The user is prompted to maintain the protective member. The protection member is cleaned or replaced in accordance with the notification of the maintenance information, so that the invariant region is not imaged at the time of imaging by the imaging means, and this is caused by dirt, damage or the like generated on the protection member. Misreading can be reliably prevented.

In the invention of claim 4 , when the ratio of the invariant area detected by the detection unit to the captured image captured by the imaging unit affects the decoding, for example, exceeds 3%, Maintenance information is notified by the notification means. That is, when the proportion of the invariant area does not affect the decoding, for example, about 3% or less, the maintenance information is not notified by the notification means. For this reason, when the protective member is contaminated or damaged so as not to affect the decoding, the maintenance information is not notified. Therefore, the maintenance information is notified at an appropriate time by avoiding excessive maintenance information. Can be implemented.

In the invention of claim 5, only when power is turned on when the constant region is discovered by the detection means, since the maintenance information is notified by the notification means can be used safely everyday start-up inspection can be self-check .

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. 4 is a flowchart illustrating a flow of a reading process in the first embodiment. FIG. 4A is an explanatory diagram illustrating a captured image captured by the imaging process, and FIG. 4B is an explanatory diagram illustrating a captured image stored in the memory. It is a flowchart which illustrates the flow of the reading process in 2nd Embodiment.

[First Embodiment]
Hereinafter, an optical information reading apparatus according to a first embodiment of 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.
As shown in FIG. 1, an optical information reader 10 is a stationary reader, and an outer case is formed by a case 11 made of a synthetic resin such as ABS resin. And a circuit 20 (described later) for reading an information code such as a two-dimensional code. FIG. 1 illustrates a state where the optical information reader 10 reads an information code displayed on the display screen of the mobile terminal T.

  The upper surface 12 of the case 11 is formed in a substantially flat shape, and a reading port 13 formed in a rectangular shape is formed at the center of the upper surface 12, and the reading port 13 is protected so as to protect the inside. A reading window (dust-proof plate) 14 is provided as a protective member that covers the reading port 13. The reading window 14 is formed of a transparent acrylic resin or glass that can transmit illumination light emitted from the reading device 10 and reflected light from the information code C. In addition, by providing the reading window 14 in the case 11, foreign matter such as dust and dirt can be prevented from entering the case 11.

Next, the electrical configuration of the circuit 20 of the optical information reader 10 will be described.
As shown in FIG. 2, the circuit 20 mainly includes an optical system such as an illumination light source 21, a light receiving sensor 28, and an imaging lens 27, and a microcomputer (hereinafter referred to as “microcomputer”) system such as a memory 35 and a control circuit 40. And is composed of.

  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 an illumination light source capable of emitting the illumination light Lf, and includes, for example, a red LED and a lens provided on the emission side of the LED. In addition, in FIG. 2, the example which irradiates the illumination light Lf toward the portable terminal T with which the information code C was displayed on the display screen is shown notionally. The illumination light Lf is emitted outside the case 11 through the reading window 14 as described above.

  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 as a CCD area sensor, and is configured to receive the reflected light Lr irradiated and reflected on the information code C or the portable terminal T. 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 light receiving sensor 28 may correspond to an example of an “imaging unit” recited in the claims.

  The imaging lens 27 functions as an imaging optical system that collects incident light incident from the outside through the reading window 14 and forms 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 C, the reflected light Lr is condensed by the imaging lens 27, and the information code C is applied to the light receiving surface 28 a of the light receiving sensor 28. This image is formed.

  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, and the like. This microcomputer system is configured around a control circuit 40 and a memory 35 that can function as a microcomputer (information processing apparatus), and the image signal of the information code C imaged by the optical system described above is signaled in hardware and software. It can be processed.

  The image signal (analog signal) output from the light receiving sensor 28 of the optical system is input to the amplification circuit 31 and amplified with a predetermined gain, and then input to the A / D conversion circuit 33. Converted. 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 memory 35 may correspond to an example of a “storage unit” described in the claims.

  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 (peripheral devices) via a built-in input / output interface. In the case of the present embodiment, the control circuit 40 includes a light emitting device such as an LED. The unit 43, an operation unit 47 including various operation keys, a communication interface 48, and the like are connected.

  Thereby, the control circuit 40, for example, turns on / off the light emitting unit 43 that functions as an indicator for notifying information on reading of information codes and maintenance, and optical information reading in accordance with an operation signal input from the operation unit 47. Control of the operation of the device 10, communication control of the communication interface 48 enabling serial communication with an external device, and the like are enabled. The light emitting unit 43 may correspond to an example of “notification unit” described in the claims.

  Next, a reading process executed by the control circuit 40 of the optical information reading apparatus 10 configured as described above will be described with reference to the drawings. FIG. 3 is a flowchart illustrating the flow of the reading process in the first embodiment. 4A is an explanatory diagram illustrating the captured image P1 captured by the imaging process, and FIG. 4B is an explanatory diagram illustrating the captured image P2 stored in the memory 35. As illustrated in FIG.

  In the stationary optical information reading apparatus 10 in which the reading port 13 is arranged upward as in the present embodiment, not only the dirt is likely to adhere to the reading window 14 that protects the reading port 13, but also the reading port 13. The reading window 14 may be damaged by contact with a mobile phone or the like that is held over. In this case, when the information code held over the reading port 13 is imaged, dirt or damage is captured as a dark color region because the reflected light is blocked, and the information code captured for the dark color region is misread. May end up. Such misreading is a problem that occurs not only in a stationary reader but also in a portable reader.

Therefore, in the reading processing according to the present embodiment, even when dirt is attached or damaged to the reading window 14 that protects the reading port 13, even when the dirt or damage is imaged as a dark color system region. A process for preventing misreading due to the dark color region is performed.
Hereinafter, the reading process executed by the control circuit 40 will be described in detail with reference to the flowchart shown in FIG.

  When the optical information reader 10 is activated and reading processing is started by the control circuit 40, it is determined whether or not the imaging is possible in the determination processing shown in step S101 of FIG. Then, when a predetermined operation on the operation unit 47, for example, a trigger switch is operated and the optical information reading apparatus 10 is ready for imaging (Yes in S101), an imaging process shown in step S103 is performed. In this process, the illumination light Lf is irradiated upward from the illumination light source 21 through the reading window 14. Then, when the reflected light Lr reflected by the information code or the like held over the reading port 13 is received by the light receiving sensor 28, a captured image is acquired based on the signal output from the light receiving sensor 28. .

  When the captured image is acquired in this way, the code position detection process shown in step S105 is performed. In this process, when an information code is included in the acquired captured image, a code position occupied by the information code in the captured image is detected. For example, when a QR code (registered trademark) is included in the acquired captured image, a code position occupied by the QR code in the captured image is detected by extracting a QR code position detection pattern (finder pattern). be able to.

  Here, when the information code is not included in the captured image (No in S107), the processing from the imaging processing shown in step S103 described above is repeated. When the information code to be read is held over the reading port 13 and the captured image includes the information code and the code position is detected (Yes in S107), the dark color system shown in step S109 is displayed. Region extraction is performed.

  In this process, there is a process for extracting a dark color region in which the shape and brightness do not change in common for the captured image captured in step S103 and the captured image stored in the memory 35 as will be described later. Made. Whether or not the ratio (hereinafter referred to as invariant ratio Sr) of the dark color region extracted as described above to the captured image in the all-image ratio determination process shown in step S111 is larger than the first threshold value Sa. Is determined. Here, the first threshold value Sa is a value that does not affect the decoding, and is set to 3%, for example.

  Here, if the invariable ratio Sr of the extracted dark color region is equal to or less than the first threshold value Sa or the dark color region is not extracted in the first place (No in S111), the reading window 14 is affected by the decoding. Decoding processing shown in step S115 is performed on the assumption that no dirt adheres or damages to such an extent as to cause the problem. In this process, a known decoding process is performed on the code image corresponding to the information code among the captured images. The control circuit 40 that executes the decoding process shown in step S115 can correspond to an example of a “decoding unit” recited in the claims.

  When the decoding by the decoding process is successful and character data encoded as an information code is acquired (Yes in S117), the data transmission process shown in step S119 is performed, and the character data acquired by the decoding process is performed. Are transmitted (output) to the host system such as an external device via the communication interface 48.

  When the character data or the like acquired in this way is transmitted or the decoding process shown in step S115 fails (No in S117), in the entire image ratio determination process shown in step S121, the dark color region extraction process is performed. It is determined whether or not the invariable ratio Sr of the extracted dark color region is larger than the second threshold value Sb. Here, the second threshold value Sb is a value that does not affect the decoding, and is set to 3%, for example. In the present embodiment, the first threshold value Sa and the second threshold value Sb are both set to 3%. However, the present invention is not limited to this, and may be set to different values.

  Here, when the invariable ratio Sr of the extracted dark color region is equal to or smaller than the second threshold value Sb or the dark color region is not extracted in the first place (No in S121), the reading window 14 is affected by the decoding. The image storage process shown in step S123 is performed on the assumption that no dirt adheres or damages to such an extent as to cause the damage. In this process, the captured image captured in the imaging process is stored in the memory 35. As described above, the captured images captured by the imaging process are sequentially stored in the memory 35. And the process from the determination process shown to said step S101 is repeated. The captured image stored in the memory 35 may be stored so as to limit the storage capacity by being overwritten and saved on an old captured image in a ring buffer format, for example, or stored only within a predetermined period. May be.

  On the other hand, the reading window 14 is contaminated or damaged to the extent that the decoding is affected, and the captured image P1 including the information code C1 in the imaging process as shown in FIG. When the captured image P2 including the information code C2 is stored in the memory 35 as illustrated in FIG. 4B, the dark color region extraction process performs both of FIGS. 4A and 4B. A dark color region S1 and a dark color region S2 that are common to each other are extracted. When the invariable ratio Sr of the dark color region S1 out of the two dark color region S1 and dark color region S2 thus extracted becomes larger than the first threshold value Sa (Yes in S111), the process is shown in step S113. Invariant area exclusion processing is performed.

  In this process, the dark color system area S1 extracted as described above is detected as an invariant area, and an image in which the invariant area is excluded from the captured image P1 captured in the imaging process is generated. Then, the decoding process shown in step S115 is performed on the image from which the invariant area is excluded. As a result, it is possible to prevent the decoding result from being affected by dirt, damage, or the like generated in the reading window 14 that causes the invariable area. The control circuit 40 that executes the determination process shown in step S111 may correspond to an example of a “detection unit” recited in the claims.

  Here, the dark color region common to both is only the dark color region S2 illustrated in FIGS. 4A and 4B, and the invariable ratio Sr of the dark color region S2 is equal to or less than the first threshold value Sa. (No in S111), the captured image captured by the imaging process is decoded by the decoding process without excluding the dark color region S2 from the captured image.

In the determination process shown in step 111, when the invariable ratio Sr of the dark color region extracted as described above is larger than the first threshold value Sa, it is not limited to detecting this dark color region as an invariant region. Instead, the invariant area may be detected as follows.
That is, the captured image is divided into a plurality of divided areas (for example, 128 divided areas), and a dark color region common to both is detected so as to extend over N or more adjacent divided areas (for example, four divided areas). In this case, the dark color region may be detected as an invariant region. Thereby, since it is not necessary to calculate the invariant ratio Sr, the invariant region can be easily detected.

  Further, since the dirt or the like that has an influence on the decoding has been attached to the reading window 14, the dark color region extraction processing is performed as shown in FIGS. 4A and 4B. When the invariable ratio Sr of the dark color region S1 extracted in this way becomes larger than the second threshold value Sb (Yes in S121), the notification process shown in step S125 is performed.

  In this process, the light emitting unit 43 emits light in a predetermined color to notify maintenance information that prompts maintenance such as cleaning, repair, and replacement of the reading window 14 under the control of the control circuit 40. The user who visually recognizes the light emitting portion 43 that emits light in this way recognizes that the reading window 14 has been contaminated or damaged to the extent that affects the decoding, and therefore is appropriate for the user. Maintenance of the reading window 14 can be urged at a proper time.

  In the determination process shown in step 121 as well, as in the determination process shown in step S111, the captured image is divided into a plurality of divided areas, and dark-colored areas common to both of the divided areas extend over N or more divided areas. The maintenance information may be notified when detected as described above.

  As described above, in the optical information reading apparatus 10 according to the present embodiment, the dark color region in which the shape and brightness do not change in common with the captured image captured by the imaging process and the captured image stored in the memory 35. If there is an invariable ratio Sr of the dark color area larger than the first threshold value Sa (Yes in S111), the dark color area is detected as an invariant area. When the invariant area is detected, an image obtained by removing the invariant area from the captured image captured by the imaging process is decoded by the decoding process.

As a result, dirt adheres to or damages the reading window 14 that covers and protects the reading port 13, so that even when the dirt or damage is imaged as the dark color area S, the dark color area S is detected. The image is detected as the invariant area, and the image excluding the invariant area is decoded. For this reason, stains, damage, or the like generated in the reading window 14 that causes the invariant area does not affect the decoding result.
Therefore, it is possible to prevent erroneous reading due to dirt or damage generated in the reading window 14 that protects the reading port 13.

  In particular, when the invariable ratio Sr occupied by the dark-colored region whose shape and brightness do not change with respect to the captured image captured by the imaging process is larger than the first threshold value Sa that is set to an extent that does not affect the decoding. In addition, this dark color region is detected as the invariant region. In other words, when the proportion of the dark color region in which the shape and luminance do not change with respect to the captured image is such that the decoding is not affected, the decoding is performed without detecting the invariant region. For this reason, when the reading window 14 is contaminated, damaged, or the like that does not affect the decoding, the invariant area is not detected, and image processing for removing the invariant area from the captured image is performed. Therefore, unnecessary processing for image processing can be eliminated.

  Further, when the invariable ratio Sr occupied by the dark color system region extracted with respect to the picked-up image picked up by the image pick-up processing is larger than the second threshold value Sb, that is, dirt is attached to the reading window 14. When damage or the like occurs, the maintenance information is notified by the light emission of the light emitting unit 43, and the user is encouraged to maintain the reading window 14. Since the reading window 14 is cleaned or replaced in accordance with the notification of the maintenance information, the invariant area is not imaged during imaging by the imaging process. The resulting misreading can be reliably prevented.

  In particular, when the invariable ratio Sr occupied by the dark color region extracted with respect to the captured image captured by the imaging process is larger than the second threshold value Sb set to an extent that affects the decoding, the maintenance is performed. Information is notified by light emission of the light emitting unit 43. That is, when the invariable ratio Sr occupied by the invariant area is such that the decoding is not affected, the maintenance information is not notified by the light emission of the light emitting unit 43. For this reason, when the reading window 14 is contaminated or damaged to the extent that does not affect the decoding, the maintenance information is not notified. Notification can be implemented.

  Note that the notifying means for notifying the maintenance information is not limited to using the light emission state of the light emitting unit 43. For example, maintenance information for prompting maintenance may be displayed on a liquid crystal display or the like capable of displaying predetermined information. .

  As a first modification of the first embodiment, in the dark color region extraction process shown in step S109, the shape is common to the captured image captured by the imaging process and the plurality of captured images stored in the memory 35. If there is a dark color region where the luminance does not change, this dark color region may be extracted. In this case, when the invariable ratio Sr of the extracted dark color region is larger than the first threshold value Sa (Yes in S111), the extracted dark color region is detected as an invariant region. Thus, the comparison accuracy using the plurality of captured images can improve the detection accuracy of the invariant region.

  As a second modification of the first embodiment, the determination process shown in step S121 and the notification process shown in step S125 may be performed only when the power is turned on. As a result, only when the power is turned on, when the invariable area is detected and the invariable ratio Sr becomes larger than the second threshold value Sb (S121), the maintenance information is informed in the informing process. Self-check and safe to use.

[Second Embodiment]
Next, an optical information reading apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flowchart illustrating the flow of the reading process in the second embodiment.
In the optical information reading apparatus 10 according to the second embodiment, the reading process described above is replaced with a flowchart shown in FIG. 3 in order to reliably prevent misreading due to dirt or damage generated in the reading window 14. 5 is mainly different from the optical information reading apparatus according to the first embodiment in that arithmetic processing is performed based on the flowchart shown in FIG.

In the second embodiment, when the detected invariant area is included in the code image that is the area occupied by the information code in the captured image, the ratio of the invariant area to the code image (hereinafter referred to as the second invariant). The code image is decoded only when the ratio (referred to as ratio S2r) is equal to or less than the third threshold value Sc set to a value that does not affect decoding .

  That is, like the reading process shown in FIG. 5, after it is determined Yes in step S <b> 111, in the code image ratio determination process shown in step S <b> 112, the second invariant ratio S <b> 2 r of the invariable area is greater than the third threshold value Sc. Is also determined as to whether or not is greater. If the second invariant ratio S2r is equal to or less than the third threshold value Sc (No in S112), the processes after the invariant area exclusion process are performed, and the decoding process is performed. On the other hand, when the second invariant ratio S2r is larger than the third threshold value Sc (Yes in S112), the process after the determination process shown in step S121 is performed without performing the decoding process.

  As described above, when the second invariant ratio S2r becomes larger than the third threshold value Sc, that is, when the ratio of the invariant area to the code image has an influence on the decoding, the decoding is not performed. Therefore, it is possible to reliably prevent misreading due to dirt, damage, or the like generated in the reading window 14 that causes the above-described unchanged region. Further, in this case, since the invariant region exclusion process is not performed, the processing load on the control circuit 40 can be reduced.

In addition, this invention is not limited to said each embodiment and modification, You may actualize as follows.
(1) In each of the above-described embodiments, the optical information reading device according to the present invention has been described as applied to a stationary reading device in which the reading port 13 is provided on the upper side. The present invention may be applied to a stationary reading device in which the reading port 13 is provided in the direction, or may be applied to a portable reading device.

(2) In each of the above-described embodiments, a display surface that is displayed such that a plurality of light-colored cells and dark-colored cells are arranged at a predetermined position, for example, a calibration board composed of a plurality of white and black images is captured. When there is a dark color region in which the shape and brightness do not change in common with the captured image obtained by the imaging and the captured image stored in the memory 35, this dark color region is detected as an invariant region. May be. Thereby, since the dark-colored area | region in the position different from the said prescription | regulation position becomes the said invariable area, the said invariable area can be detected easily and reliably.

In addition, a dark color region in which the shape and brightness are not changed in common between the captured image obtained by the imaging and the captured image stored in the memory 35 is captured by the imaging process on the display surface including only the bright cell. In some cases, this dark color region may be detected as an invariant region.
Further, when a display surface consisting only of light-colored cells is picked up by image pick-up processing, and the picked-up image obtained by this pick-up has a dark-colored region, this dark-colored region may be detected as an invariant region.
In addition, the above-described processing for imaging the display surface and detecting the invariant region may be performed only when the power is turned on.

(3) The optical information reading apparatus 10 described above is not limited to being in an imageable state in response to a predetermined operation on the operation unit 47. For example, the optical information reading device 10 may be configured to be always in an imageable state. Good. In such a configuration, the determination process in step S101 is abolished.

DESCRIPTION OF SYMBOLS 10 ... Optical information reader 13 ... Reading port 14 ... Reading window (protection member)
28: Light receiving sensor (imaging means)
35 ... Memory (storage means)
40. Control circuit (decoding means, detection means)
43 ... Light emitting section (notification means)
C, C1, C2 ... Information code P1, P2 ... Captured image S ... Dark color region Sr ... Invariant ratio Sa ... First threshold Sb ... Second threshold

Claims (5)

Imaging means for imaging the QR code by receiving reflected light from the QR code through the reading port;
Decoding means for decoding the QR code based on the code image of the QR code imaged by the imaging means;
An optical information reader comprising:
A protective member that can transmit the reflected light and covers the reading port so as to protect the inside of the reading port;
Storage means for sequentially storing picked-up images picked up by the image pickup means;
When there is a dark color region where the shape and brightness do not change in common between the captured image captured by the image capturing unit and the captured image stored in the storage unit, the dark color region is detected as an invariant region. Detecting means,
The decoding means, when the invariant area detected by the detection means is included in the code image, only when the proportion of the invariant area to the code image is such that the decoding is not affected. An optical information reader which decodes the code image. The detection unit includes the dark color region when there is a dark color region where the shape and the luminance do not change in common between the captured image captured by the imaging unit and the plurality of captured images stored in the storage unit. The optical information reader according to claim 1, wherein the optical information reader is detected as the invariant region . Wherein when the constant regions by the detection means is detected, reading optical information according to claim 1 or 2, characterized in Rukoto provided with informing means for informing the maintenance information prompting maintenance of the protective member device. The notifying means notifies the maintenance information when the ratio of the invariant area detected by the detecting means to the captured image captured by the imaging means is such that it affects decoding. The optical information reader according to claim 3 . The notifying means has a dark color region in which the shape and brightness do not change in common with the captured image captured by the imaging means when the power is turned on and the captured image stored in the storage means only when the power is turned on. , when the dark colored area detected by the detecting means as the constant regions, an optical information reading apparatus according to claim 3 or 4, wherein that you notify the maintenance information.

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