JP5402587B2 - Optical information reader - Google Patents

Description

  The present invention relates to an optical information reader having an automatic focus adjustment function.

  Conventionally, as a technique related to an optical information reading apparatus having an automatic focus adjustment function, an automatic focus adjustment apparatus shown in Patent Document 1 below is known. This automatic focusing device automatically performs focusing on a specimen such as blood, and a marker is placed on the surface (reference plane) of a slide glass on which the specimen is placed. A focus evaluation curve is created and stored in advance by calculating the number of pixels (focus evaluation value) in the marker area at each reference plane-lens distance while changing the distance between the two. Then, based on the number of pixels of the marker included in the image data photographed at the time of focusing, the current reference plane—the distance between the lenses is obtained by the focus evaluation curve, and this distance and the reference plane when focusing on the marker— The amount of difference with the distance between the lenses is obtained, and the slide glass is moved according to the amount of difference, thereby focusing.

  In addition, the camera-equipped mobile terminal shown in Patent Document 2 below includes a display screen that displays a captured image, and a distance measurement unit such as an infrared sensor or an ultrasonic sensor that measures the distance to the subject. Then, based on the distance measured by the distance measuring unit, the image displayed on the display screen is an image in the opposite direction of the display screen, and is an image centered on the approximate center of the display screen. The acquired image data is corrected.

JP 2009-109682 A JP 2006-109075 A

  By the way, recently, in order to smoothly read a nearby two-dimensional code displayed on a slip or a remote two-dimensional code displayed on a forklift or a product on a shelf with a single reading device, There is an increasing need for a reading apparatus equipped with a focus adjustment function (autofocus function). A contrast detection method is mainly used as a method of focusing by autofocus, and since a photographing CCD is used as an advantage, the mechanism can be simplified, and the size and cost can be reduced.

  However, the disadvantages of the contrast detection method are that it is not possible to focus on an object with no contrast, and that it is not possible to focus when it is dark, and that it takes time to focus. The reason why it takes a long time to focus is that the distance to the subject cannot be obtained instantaneously with this method. This is in order to search for the position, and since the lens is frequently moved, the durability of the lens driving mechanism also becomes a problem.

  In the optical information reader, as in Patent Document 1, when the distance to the reading target is obtained based on the focus evaluation curve and the condenser lens is moved according to this distance, a marker is placed near the reading target. Not only does it always have to be arranged, but it is also necessary to create a new focus evaluation curve depending on the work situation. For this reason, it is difficult to shorten the focusing time, and it is also difficult to reduce the moving frequency of the condenser lens. In addition, as in Patent Document 2, when the condenser lens is moved according to the distance to the reading target measured by an infrared sensor, an ultrasonic sensor, or the like, a distance measurement sensor with respect to the conventional configuration. There is a problem that the apparatus configuration becomes large and complicated.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to read optical information that can favorably focus reflected light from an information code via a condenser lens on a light receiving means. To provide an apparatus.

In order to achieve the above object, the optical information reader of claim 1 according to claim 1 is an optical information reader for optically reading an information code, and is reflected from the information code and condensed. Based on light receiving means for receiving reflected light collected by the lens, marker light irradiating means for irradiating marker light in a direction inclined by a predetermined angle with respect to the optical axis of the light receiving means, and a light reception result by the light receiving means Generating means for generating image data, distance measuring means for measuring a distance to the information code based on a position of the marker light in the image data including the information code and the marker light, and the distance measuring means A lens moving means for moving the condenser lens in the direction of the optical axis so as to be focused according to the measurement distance measured by, and a state in which the condenser lens is focused according to the measurement distance. A decoding means for decoding the information code based on image data generated according to a light reception result from the light receiving means that has received the reflected light of the information code, and an allowable circle of confusion determined from a resolution that can be decoded. A depth-of-field calculating means for calculating a depth of field of the light receiving means based on the decoding means, wherein the decoding means calculates the measured distance measured by the distance measuring means by the depth-of-field calculating means. An image generated in accordance with the light reception result from the light receiving means that has received the reflected light of the information code at the time of measurement by the distance measuring means without being focused, It decodes the information code based on the data, wherein the information code includes the error correction area for error correction, the image data smell Wherein in a region in which the marker light occupies in the information coding region occupied characterized Rukoto provided with error correction means for performing error correction on the basis of the error correction region as an error.

  According to a second aspect of the present invention, in the optical information reading apparatus according to the first aspect, the distance measuring unit measures the measurement distance based on a deviation amount of the marker light with respect to a reference position in the image data. Features.

  According to a third aspect of the present invention, in the optical information reading apparatus according to the second aspect, the reference position is a center position in the image data.

  According to a fourth aspect of the present invention, in the optical information reading device according to any one of the first to third aspects, the marker light irradiating means is inclined at the predetermined angle along a wide angle of view of the light receiving means. It is arranged to irradiate the marker light.

  According to a fifth aspect of the present invention, in the optical information reading apparatus according to any one of the first to fourth aspects, the marker light irradiating means is configured such that the predetermined angle is half of the angle of view of the light receiving means in the inclination direction. It is arranged to be set as follows.

  A sixth aspect of the present invention is the optical information reading device according to any one of the first to fifth aspects, wherein the amount of the marker light emitted from the marker light irradiation means can be controlled, and the image In the case where the marker light is not included in the data, marker light control means for increasing the amount of the marker light is provided.

  A seventh aspect of the present invention is the optical information reader according to any one of the first to sixth aspects, wherein the marker light irradiating means irradiates the marker light in parallel with the optical axis. To do.

  According to an eighth aspect of the present invention, in the optical information reading apparatus according to the seventh aspect, a plurality of the marker light irradiation means are provided.

  In the first aspect of the present invention, the marker light irradiating means irradiates the marker light in a direction inclined by a predetermined angle with respect to the optical axis of the light receiving means, and the marker light in the image data including the marker light and the information code Based on the position, the distance to the information code is measured. Then, in a state where the condenser lens is moved in the optical axis direction by the lens moving means so as to be focused according to the measurement distance, the information code is based on the image data generated to include the information code. Decoded.

Since the marker light is irradiated in a direction inclined by a predetermined angle with respect to the optical axis of the light receiving means, the position of the marker light is shifted in a predetermined direction as the image data is separated from the distance. Therefore, the distance to the information code can be measured based on the position of the marker light in the image data including the marker light and the information code without using a special sensor. Then, the focusing lens is moved in the optical axis direction so as to be focused according to the distance measured in this way, so that the focusing position is compared with the case where the focusing position is searched while moving the focusing lens. It is possible to reduce the frequency of movement of the condensing lens for this purpose.
Therefore, the reflected light from the information code via the condenser lens can be suitably focused on the light receiving means.
In particular, when the measurement distance measured by the distance measuring means is within the depth of field of the light receiving means calculated by the depth of field calculating means based on the allowable circle of confusion determined from the resolution that can be decoded. The information code is decoded based on the image data generated according to the light reception result from the light receiving means that has received the reflected light of the information code without focusing. In this way, when the measurement distance is within the depth of field of the light receiving means, the information code is imaged with good focus without moving the condenser lens for accurate focusing. The moving frequency of the condenser lens can be further reduced.
The information code includes an error correction area for performing error correction, and it is assumed that the area occupied by the marker light in the area occupied by the information code in the image data has an error based on the error correction area. Error correction is performed. Of the area occupied by the information code, the area occupied by the marker light is highly likely to be an error. Therefore, by performing error correction on the assumption that this area is an error, the accuracy of error correction should be improved. Can do.

  In the invention of claim 2, since the distance measuring unit measures the measurement distance based on the amount of deviation of the marker light with respect to the reference position in the image data, by calculating the amount of deviation using the number of pixels of the image data, The distance to the information code can be measured more accurately.

  According to a third aspect of the present invention, the reference position is set at the center position in the image data. Since the operator usually takes an image so that the information code is positioned at the center position of the image data, the distance to the information code can be measured more accurately by setting the center position of the image data as the reference position. it can.

  In the invention of claim 4, the marker light irradiating means is arranged so as to irradiate the marker light at a predetermined angle along the wide direction of the angle of view of the light receiving means. Therefore, in order to improve the measurement accuracy, the marker light irradiation means Even if the inclination angle is increased, the marker light does not easily protrude outside the image data. For this reason, the measurement accuracy of the distance to the information code can be improved as compared with the case where the angle of view is arranged along the narrow direction.

  In the invention of claim 5, since the marker light irradiating means is arranged so that the predetermined angle is set to be less than or equal to half of the angle of view of the light receiving means in the inclination direction, the marker light is emitted even when imaging a distant information code. Is always irradiated to the area corresponding to the image data. Thereby, even a distant information code can measure the distance to the information code.

  In the invention of claim 6, when the marker light is not included in the image data, the amount of the marker light emitted from the marker light irradiation means is increased. It is possible to prevent the distance from becoming unmeasurable.

  According to the seventh aspect of the present invention, the marker light is irradiated in parallel with the optical axis of the light receiving means by the marker light irradiation means. Since the operator usually images the information code so as to be positioned at the center position of the image data, the marker light is irradiated in parallel with the optical axis of the light receiving means, so that the information code can be displayed even if the information code is far away. The code and the marker light are close to each other and are included in the image data. Thereby, even a distant information code can measure the distance to the information code.

  In the invention of claim 8, since a plurality of marker light irradiation means for irradiating the marker light in parallel with the optical axis are provided, the effect of the invention of claim 7 can be further enhanced.

1 is a block diagram showing an electrical configuration of an optical information reading apparatus 10 according to a first embodiment. It is a conceptual diagram which shows the positional relationship of the marker light irradiation part 50 and the light reception sensor 28 in 1st Embodiment. It is explanatory drawing which shows the irradiation state of each marker light irradiated from the marker light irradiation part. 4A shows the irradiation direction of the marker light Mc when the angle of view is wide in the horizontal direction, and FIG. 4B is a conceptual diagram showing the irradiation direction of the marker light Mc when the angle of view is wide in the vertical direction. is there. 4 is a flowchart illustrating a flow of a reading process performed by a control circuit 40. It is a conceptual diagram which shows the positional relationship of the marker light irradiation parts 50a and 50b and the light reception sensor 28 in 2nd Embodiment.

[First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment in which an optical information reading device of the invention is embodied will be described with reference to the drawings.
As shown in FIG. 1, the optical information reader 10 optically receives an information code such as a one-dimensional code such as a barcode attached to a reading object such as a packing box or a two-dimensional code such as a QR code (registered trademark). It is configured as a portable reader that reads automatically. The optical information reading apparatus 10 includes a circuit unit 20 housed in a housing (not shown). The circuit unit 20 mainly includes 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.

  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. FIG. 1 conceptually illustrates an example in which the illumination light Lf is irradiated toward the reading target R on which the QR code Q is displayed.

  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 having a number of pixels of 640 × 480 (VGA), and is configured to receive the reflected light Lr irradiated and reflected on the QR code Q or the reading target R. . 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 “light receiving means” recited in the claims.

  The imaging lens 27 functions as a condensing lens capable of condensing incident light incident from the outside through the reading port 13 and forming an image on the light receiving surface 28 a of the light receiving sensor 28. In the first embodiment, the illumination light Lf emitted from the illumination light source 21 is reflected by the QR code Q, and then the reflected light Lr is collected by the imaging lens 27 and is applied to the light receiving surface 28a of the light receiving sensor 28. An image is formed.

  The imaging lens 27 is supported by a lens moving mechanism 29 so as to be movable along the optical axis L of the light receiving sensor 28. The lens moving mechanism 29 is configured by a motor (not shown) or the like, and has a function of moving the imaging lens 27 in the optical axis direction by a predetermined amount in accordance with a drive signal from the control circuit 40. The imaging lens 27 and the lens moving mechanism 29 can correspond to an example of “condensing lens” and “lens moving means” recited in the claims.

  The microcomputer system described above includes an amplifier 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 light emitting unit 43, a buzzer 44, a vibrator 45, and a liquid crystal display. 46, a communication interface 48, and the like.

  The image signal (analog signal) output from the light receiving sensor 28 of the optical system is input to the amplifier circuit 31 and amplified with a predetermined amplification factor, and then input to the A / D conversion circuit 33. The signal is converted to a digital signal. When the digitized image signal, that is, image data (image information) is generated and input to the memory 35, it is stored in a predetermined code image information 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 the RAM of the memory 35, in addition to the image data storage area described above, a work area and a reading condition table used by the control circuit 40 in each processing such as arithmetic operation and logical operation are secured. ing. The ROM stores in advance a predetermined program that can execute a reading process and the like that will be described later, a system program that can control each piece of hardware such as the illumination light source 21 and the light receiving sensor 28, and the like.

  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 the first embodiment, the light emitting unit 43, the buzzer 44, the vibrator 45, and the liquid crystal display. 46, a communication interface 48, and the like are connected.

  Thereby, for example, the control circuit 40 turns on / off the light emitting unit 43 that functions as an indicator for notifying information relating to reading of the QR code Q, on / off of the sound of the buzzer 44 that can generate a beep sound and an alarm sound, Drive control of the vibrator 45 capable of generating vibration that can be transmitted to the operator of the information reading device 10, display control of the liquid crystal display 46, communication control of the communication interface 48 enabling serial communication with an external device, and the like are possible I have to. The external device connected to the communication interface 48 includes a host computer or the like corresponding to the host system of the optical information reading device 10.

In the first embodiment, a marker light irradiation unit 50 is provided. As shown in FIG. 2, the marker light irradiation unit 50 includes four L-shaped marker lights M _{1 to} M ₄ indicating the vicinity of the four corners of the reading field S and one indicating the vicinity of the center position of the reading field S. It has a function of irradiating circular marker light Mc. The marker light irradiation unit 50 includes a laser diode that emits laser light as marker light, a lens that collects laser light from the laser diode, and a drive circuit that drives the laser diode. Yes. The drive circuit is connected to the control circuit 40 and drives the laser diode in accordance with a signal from the control circuit 40. A known laser diode drive circuit can be used as the drive circuit that drives the laser diode in response to a command from the control circuit 40. The lens functions to collect the marker light (laser light) emitted from the laser diode and display each marker light as a mark of the reading position on the surface of the reading object R.

FIG. 3 is a conceptual diagram showing a positional relationship when the marker light irradiation unit 50 and the light receiving sensor 28 are viewed from above.
In the first embodiment, the marker light irradiation unit 50, as shown in FIG. 3, with displaced by a predetermined distance A ₁ in the horizontal direction (in FIG. 3 vertical direction) with respect to the optical axis L of the light receiving sensor 28, the reading The irradiation direction of the marker light Mc indicating the vicinity of the center position of the visual field S is arranged so as to be inclined with respect to the optical axis L by an angle α. Thereby, in the image data imaged by the light receiving sensor 28, the position of the marker light Mc is shifted in a predetermined direction (vertical direction in FIG. 3) according to the distance to the object from which the marker light Mc is reflected. . In particular, as shown in FIG. 4A, the light receiving sensor 28 has a wide angle of view in the horizontal direction (vertical direction in FIG. 3). Therefore, the laser diode has a marker for increasing the angle α. The irradiation direction of the light Mc is arranged so as to incline along the wide angle of view (the left-right direction in FIG. 4A). Thereby, in the image data imaged by the light receiving sensor 28, the position of the marker light Mc is shifted in the horizontal direction (vertical direction in FIG. 3) according to the imaging distance. When the light receiving sensor 28 has a wide angle of view in the vertical direction as shown in FIG. 4B, the laser diode is used in the direction in which the marker light Mc is irradiated in the wide angle of view, that is, in the vertical direction. You may arrange | position so that it may incline along.

  Next, a reading process performed by the control circuit 40 in the optical information reading apparatus 10 configured as described above will be described with reference to a flowchart shown in FIG. It is assumed that the QR code Q to be read includes an error correction area for performing error correction described later.

  First, when the power is turned on and a predetermined initial setting or the like is performed, a marker light irradiation process is performed in step S101 of FIG. 5, and each marker light is irradiated from the marker light irradiation unit 50 in a predetermined direction. . Next, image data generation processing is performed in step S103, and the operator directs each marker light to the QR code Q to be read, so that the illumination light Lf from the illumination light source 21 is reflected by the QR code Q. Thereafter, when the reflected light Lr and the reflected light of the marker light are received by the light receiving sensor 28, image data is generated based on the light reception result. Subsequently, in step S105, it is determined whether or not the marker light Mc is included in the image data generated as described above. Here, for example, since the far-off QR code Q is a reading target, the light amount of the marker light M is insufficient, and therefore it is determined that the marker light Mc is not included in the image data (in S105). No), a light quantity increase process is performed in step S107. Thereby, the light quantity of each marker light from the marker light irradiation part 50 is increased, and the process from said step S101 is made. The control circuit 40 that executes step S107 may correspond to an example of “marker light control means” recited in the claims.

On the other hand, since the marker light Mc is included in the image data, if it is determined Yes in step S105, a deviation amount measurement process is performed in step S109. In this process, the deviation amount N ₁ marker light Mc with respect to the center position is the reference position in the image data is measured. Specifically, the number of pixels between the center position of the center position and the marker light Mc of the image data is determined as the displacement amount N _1. The deviation amount N ₁ may correspond to an example of “deviation amount” described in the claims.

Next, in step S111, distance calculation processing is performed using the size of the region occupied by the QR code Q in the image data. As described above, since the position of the marker light Mc is shifted in a predetermined direction (vertical direction in FIG. 3) according to the imaging distance, the distance to the reading target R irradiated with the marker light Mc, that is, up to the QR code Q. And the actual deviation amount of the marker light Mc with respect to the optical axis L (hereinafter referred to as the actual deviation amount Y) at the distance X, the relationship of the following formula 1 is established.
Y = X × tan α + A ₁ (1)
The distance A _1, since the image is shifted (lower side in FIG. 3) opposite to the inclination direction of the marker light Mc, is calculated as a negative value.

In addition, since half of the number of pixels in the horizontal direction of the light receiving sensor 28 is 320, when the actual length corresponding to 320 pixels is Ya, the following relations 2 and 3 are established. As illustrated in FIG. 3, β is an angle of view of the light receiving sensor 28, and is set to 30 °, for example.
Ya: Y = 320: N ₁ (2)
Ya = X × tan (β / 2) (3)
Therefore, by eliminating Ya and Y from the relationship of the above equations 1 to 3, the following equation 4 regarding the distance X is established.
X = (320 × A ₁ ) / (N ₁ × tan (β / 2) −320 × tan α) (4)
Therefore, in the distance calculation process, the above equation 4, based on the shift amount N ₁ measured in step S109, the distance X to the QR code Q is calculated. The distance X can correspond to an example of “measurement distance” recited in the claims.

Subsequently, in step S113, depth-of-field calculation processing is performed. In this process, the depth of field at the far point (hereinafter, also referred to as the far point depth of field Df) and the depth of field at the near point (hereinafter referred to as the depth of field) are calculated based on Formulas 5 and 6 which are known relational expressions. Hereinafter, the near point depth of field Dn) is calculated.
Df = X × (H−f) / (H + X−2 × f) (5)
Dn = X × (H−f) / (H−X) (6)
Here, H is a coefficient represented by f ² / (F × d), f is a focal length of the lens, and F is a stop. Further, d is an allowable circle of confusion (amount of blur), and is determined from the minimum resolvable resolution (the minimum allocated pixel of the cell necessary for reading).

  Next, in step S115, it is determined whether or not there is a QR code Q within the depth of field. Here, since the distance X calculated in step S111 exceeds the far point depth of field Df or less than the near point depth of field Dn, it is determined that the QR code Q is not within the depth of field. If NO, it is determined No in step S115. Then, lens movement processing is performed in step S117, and a drive signal is output to the lens movement mechanism 29 so as to be focused according to the distance X calculated in step S111. As a result, the lens moving mechanism 29 moves the imaging lens 27 along the optical axis L of the light receiving sensor 28 based on the drive signal from the control circuit 40 to bring it into focus. Then, after image data generation processing is performed in step S119 to generate new focused image data, decoding processing is performed by a known decoding method in step S121. In the image data generation process in step S119, image data is generated in a state where irradiation of each marker light is stopped. However, image data may be generated without stopping irradiation of each marker light.

  On the other hand, when the distance X calculated in step S113 is not less than the near point depth of field Dn and not more than the far point depth of field Df, it is determined that the QR code Q is within the depth of field. Is determined as Yes in step S115. In this case, since the QR code Q is imaged with good focus without moving the imaging lens 27 in order to focus accurately, the steps in steps S117 and S119 are not performed. In S121, the image data generated in step S103 is decoded by a known decoding method.

  Then, error correction processing is performed in step S123, and error correction processing is performed on the information area that could not be decoded in step S121 by a known error correction method. In particular, when there is an area occupied by the marker light Mc in the area occupied by the QR code Q in the image data, the error correction process is performed on the assumption that the information of the area occupied by the marker light Mc is incorrect. The correction accuracy of the process can be improved. The control circuit 40 that executes step S123 may correspond to an example of “error correction means” recited in the claims.

  If the decoding process is successful (Yes in S125), the reading process is terminated. If the decoding process is unsuccessful (No in S125), the processes from Step S101 are repeated.

  As described above, in the optical information reading apparatus 10 according to the first embodiment, the marker light Mc is irradiated in the direction inclined by the angle α with respect to the optical axis L of the light receiving sensor 28 by the marker light irradiation unit 50. The distance X to the QR code Q is calculated based on the position of the marker light Mc in the image data including the marker light Mc and the QR code Q. Then, when the QR code Q is not within the depth of field, the QR code is moved in the optical axis direction by the lens moving mechanism 29 so that the imaging lens 27 is focused according to the distance X. The QR code Q is decoded based on the image data generated to include Q.

Thereby, the distance to the QR code Q can be measured based on the position of the marker light Mc in the image data including the marker light Mc and the QR code Q without using a special sensor. And, in order to move the imaging lens 27 in the optical axis direction so as to be focused according to the distance measured in this way, compared with the case of searching the focusing position while moving the imaging lens 27, The moving frequency of the imaging lens 27 for focusing can be reduced.
Therefore, the light reflected from the QR code Q via the imaging lens 27 can be suitably focused on the light receiving sensor 28.

Use also, in the optical information reading apparatus 10 according to the first embodiment, the distance X on the basis of the shift amount N ₁ marker light Mc with respect to the reference position in the image data is determined, the number of pixels of the image data or the like by calculating the displacement amount N ₁ which had, it is possible to measure the distance to the QR code Q more accurately.

Further, the optical information reading apparatus 10 according to the first embodiment, the reference position when measuring the shift amount N ₁ marker light Mc is set to the center position in the image data. Since an operator usually captures an image so that the QR code Q is positioned at the center position of the image data, the distance to the QR code Q is more accurately measured by setting the center position of the image data as the reference position. be able to.

  Furthermore, in the optical information reading apparatus 10 according to the first embodiment, the marker light irradiation unit 50 irradiates the marker light Mc at an angle α along the wide angle of view of the light receiving sensor 28. Therefore, even if the inclination angle of the marker light Mc is increased in order to improve the measurement accuracy, the marker light Mc does not easily protrude from the image data. For this reason, the measurement accuracy of the distance to the QR code Q can be improved as compared with the case where the angle of view is arranged along a narrow direction.

  Further, in the optical information reading device 10 according to the first embodiment, when the marker light Mc is not included in the image data, the amount of the marker light Mc emitted from the marker light irradiation unit 50 is increased. Therefore, it is possible to prevent the distance to the QR code Q from becoming unmeasurable due to insufficient light quantity of the marker light Mc.

  Furthermore, in the optical information reading apparatus 10 according to the first embodiment, when the distance X to the QR code Q is within the depth of field of the light receiving sensor 28, the reflection of the QR code Q is not performed. The QR code Q is decoded based on the image data generated according to the light reception result from the light receiving sensor 28 that has received the light. Thus, when the distance X is within the depth of field of the light receiving sensor 28, the QR code Q is imaged with good focus without moving the imaging lens 27 in order to focus accurately. Therefore, the moving frequency of the imaging lens 27 can be further reduced.

  Furthermore, in the optical information reading apparatus 10 according to the first embodiment, the QR code Q includes an error correction area for performing error correction, and among the areas occupied by the QR code Q in the image data Assuming that there is an error in the area occupied by the marker light Mc, error correction is performed based on the error correction area. Of the area occupied by the QR code Q, the area occupied by the marker light Mc is highly likely to be an error. By performing error correction on the assumption that this area is an error, the accuracy of error correction is improved. Can be made.

  As a modification of the first embodiment, the marker light irradiation unit 50 may be arranged such that the angle α with respect to the optical axis L is set to be equal to or less than half the angle of view of the light receiving sensor 28 in the tilt direction. In this case, even when the far QR code Q is imaged, the marker light Mc is always applied to the area corresponding to the image data. Therefore, even if the QR code Q is far, the distance X to the QR code Q is Can be measured.

[Second Embodiment]
Next, a second embodiment that embodies the optical information reader of the present invention will be described with reference to FIG.
In the optical information reading apparatus 10 according to the second embodiment, the two marker light irradiation units 50a and 50b are employed instead of the marker light irradiation unit 50, and the optical information according to the first embodiment is used. Different from the reader. Therefore, substantially the same components as those of the optical information reading apparatus according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 6, the marker light irradiation units 50 a and 50 b are configured such that each marker light Mc is parallel to the optical axis L of the light receiving sensor 28 and is shifted by a distance A ₂ around the optical axis L. are arranged to, in the second embodiment, by measuring the displacement amount N ₂ between both marker light Mc in step S109 described above, the distance X to the QR code Q is measured at step S111 .

Specifically, since the number of pixels in the horizontal direction of the light receiving sensor 28 is 640, when the actual length corresponding to the 640 pixels is Yb, the following expressions 7 and 8 are satisfied.
Yb: A ₂ = 640: N ₂ (7)
Yb / 2 = X × tan (β / 2) (8)
Therefore, by deleting Yb from the relationship of the above equations 7 and 8, the following equation 9 regarding the distance X is established.
X = 320 × A ₂ / (N ₂ × tan (β / 2)) (9)
Accordingly, the distance calculation processing in step S111, the above equation 9, based on the shift amount _{N 2} measured in step S109, the distance X to the QR code Q is calculated.

  As described above, in the optical information reading apparatus 10 according to the second embodiment, the marker light Mc is irradiated in parallel with the optical axis L of the light receiving sensor 28 by the two marker light irradiation units 50a and 50b. Since the operator usually images the QR code Q so as to be positioned at the center position of the image data, the marker light Mc is irradiated in parallel with the optical axis L of the light receiving sensor 28, so that the QR code Q is distant. Even so, the QR code Q and the marker light Mc are close to each other and are included in the image data. Thereby, the distance X to the QR code Q can be measured even if the QR code Q is far away.

  In the second embodiment, two marker light irradiators are provided in parallel with the optical axis L. However, one marker light irradiating unit may be provided in parallel with the optical axis L depending on the work environment. Three or more may be provided in parallel with the axis L.

The present invention is not limited to the above embodiments, and may be embodied as follows. Even in this case, the same operations and effects as those of the above embodiments can be obtained.
(1) The light receiving sensor 28 is not limited to a sensor having a number of pixels of 640 × 480 (VGA), but may be a light receiving sensor having a specification different from the number of pixels. In this case, in the distance calculation process in step S111, the distance X is calculated based on the number of pixels of the light receiving sensor.

(2) In the shift amount measurement process in step S109, the reference position is not limited to the center position in the image data, and may be set to a suitable position as a reference according to the work situation or the like.

(3) Steps S117 and S119 are always performed without determining whether or not the QR code Q is within the depth of field in step S115, and new focused image data is generated. May be.

DESCRIPTION OF SYMBOLS 10 ... Optical information reader 27 ... Imaging lens (condensing lens)
28. Light receiving sensor (light receiving means)
29 ... Lens moving mechanism (lens moving means)
40. Control circuit (generating means, distance measuring means, decoding means, marker light control means)
50, 50a, 50b ... Marker light irradiation unit (marker light irradiation means)
Df ... far point the depth of field Dn ... near point the depth of field L ... optical axis Lr ... reflected light Mc ... marker light N _1, N 2 _... shift amount X ... distance (measured distance)
Q ... QR code (information code)
α ... Inclination angle β ... Field angle

Claims (8)

An optical information reader for optically reading an information code,
A light receiving means for receiving reflected light reflected from the information code and collected by a condenser lens;
Marker light irradiating means for irradiating marker light in a direction inclined by a predetermined angle with respect to the optical axis of the light receiving means;
Generating means for generating image data based on a light reception result by the light receiving means;
Distance measuring means for measuring a distance to the information code based on a position of the marker light in the image data including the information code and the marker light;
Lens moving means for moving the condenser lens in the optical axis direction so as to be focused according to the measurement distance measured by the distance measuring means;
Decoding means for decoding the information code based on image data generated according to a light reception result from the light receiving means that has received the reflected light of the information code in a focused state according to the measurement distance;
A depth-of-field calculating means for calculating the depth of field of the light receiving means based on an allowable circle of confusion determined from a resolution that can be decoded;
With
When the measurement distance measured by the distance measurement means is within the depth of field calculated by the depth of field calculation means, the decoding means does not focus the distance measurement means. based on the image data generated in accordance with the light reception result from the light receiving means receives the reflected light of the information code at the time of measurement by decoding the information code,
The information code includes an error correction area for error correction,
Reading optical information, characterized in Rukoto provided with error correction means for performing error correction on the basis of the error correction region as the in the area occupied by the marker light among areas in the image data the information code occupies an error apparatus.   The optical information reading apparatus according to claim 1, wherein the distance measuring unit measures the measurement distance based on a deviation amount of the marker light with respect to a reference position in the image data.   The optical information reading apparatus according to claim 2, wherein the reference position is a center position in the image data.   The marker light irradiating means is arranged so as to irradiate the marker light at a predetermined angle along a wide angle of view of the light receiving means. An optical information reading device described in 1.   The said marker light irradiation means is arrange | positioned so that the said predetermined angle may be set to the half or less of the angle of view of the said light-receiving means in the inclination direction, The any one of Claims 1-4 characterized by the above-mentioned. Optical information reader.   Marker light control means is provided that can control the amount of the marker light emitted from the marker light irradiation means, and increases the amount of the marker light when the marker light is not included in the image data. The optical information reading apparatus according to claim 1, wherein the optical information reading apparatus is an optical information reading apparatus.   The optical information reading apparatus according to claim 1, wherein the marker light irradiation unit irradiates the marker light in parallel with the optical axis.   The optical information reading apparatus according to claim 7, wherein a plurality of the marker light irradiation units are provided.

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