JP2012181757A - Optical information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information reader having improved reading speed.SOLUTION: An optical information reader measures a distance between the reader and plural points of an object to be imaged (step S1), and divides an image obtained by a light-receiving sensor into plural areas on the basis of the measured distances (step S2). Then, the reader selects a reading area from the divided areas (step S3). Since the image is divided into the plural areas on the basis of the distances, there is no effect of various intensity changes of the object to be imaged other than an intensity change due to a QR code(R), as distinct from the case where intensity changes and edges are used for division into areas. This enables accurate selection of an area including a QR code and reduces the possibility of re-performing reading processing after the selection, thereby improves reading speed. The improvement of the area selection accuracy increases information reading accuracy.

Description

  The present invention relates to an optical information reader that optically reads an information code, and more particularly to a technique for improving the reading speed of the optical information reader.

  As a technique for improving the reading speed of the optical information reading apparatus, for example, techniques described in Patent Documents 1 and 2 are known. In Patent Document 1, the luminance of a two-dimensional code image is binarized, an envelope is created by connecting a plurality of black cells existing on the outer periphery of the binarized image, and an inspection region is limited based on the envelope By doing so, the reading speed is improved.

  In Patent Document 2, the luminance of an image is binarized, a portion where two or more white pixels continue is set as a blank portion, and a two-dimensional code candidate region is determined based on the blank portion. The subsequent processing is limited to the two-dimensional code candidate region, thereby improving the reading speed.

Japanese Patent Laid-Open No. 2004-362053 International Publication No. 2005/086074

  The techniques disclosed in Patent Documents 1 and 2 determine the range of the captured image by detecting the code features and the features around the code from the luminance change of the image, This is a technique for limiting the image range for subsequent processing. Therefore, unless the feature of the code and the surrounding features of the code can be detected from the image, the image range for the subsequent processing cannot be limited.

  However, depending on the object to be imaged, a luminance change may occur at a place other than the information code. For example, when the object to be imaged is a substrate, there are various patterns and various irregularities in addition to the information code on the substrate, and the luminance changes due to these various patterns and irregularities. In many cases, it is difficult to detect the features and the features around the code. Therefore, in the prior art, the area including the information code cannot be appropriately narrowed down, and as a result, it may take time to read.

  The present invention has been made based on this situation, and an object of the present invention is to provide an optical information reading apparatus capable of improving the reading speed.

  In order to achieve the object, the invention according to claim 1 is characterized in that an image pickup unit for picking up an image pickup object indicated by an information code, a reading area from the image picked up by the image pickup means, An optical information reading device that reads information from an information code by the reading processing, and estimates distances from the optical information reading device to a plurality of points of the imaging object. Based on the distance estimation means, the image estimated by the distance estimation means, an image area dividing means for dividing the image captured by the imaging means into a plurality of areas, and a plurality of areas divided by the image area dividing means, And an area selection means for selecting the reading area.

  As described above, according to the present invention, the distance from the optical information reading device to a plurality of points of the imaging target is estimated, and the image captured by the imaging unit is divided into a plurality of regions based on the estimated distance. Since the image is divided into a plurality of regions according to the distance, unlike the case where the region is divided based on the luminance change, even if various luminance changes other than the luminance change caused by the information code are present on the imaging object, the influence is affected. I do not receive it. Therefore, the area including the information code can be narrowed down with high accuracy, and the case where the subsequent reading process is performed again is reduced, so that the reading speed is improved. In addition, since the accuracy of narrowing down the area is improved, the information reading accuracy is also improved.

  According to the second aspect of the present invention, based on the distances to a plurality of points in the reading area estimated by the distance estimating means, the image of the reading area is a plane perpendicular to the optical axis of the imaging means. And an image correcting unit that corrects the image in the case where the image is corrected, and the reading unit performs a reading process using the image corrected by the image correcting unit.

  The invention according to claim 2 corrects the image in the reading region by utilizing the fact that the distance can be estimated by the distance estimating means. The reading area of the imaging object is not necessarily a flat surface. When the reading area is not flat (that is, when the reading area is curved), distortion occurs in the image of the information code shown in the reading area. In addition, the imaging angle of the imaging target with respect to the optical information reading device may change every time the imaging is performed, and the information code image is also distorted by the change in the imaging angle.

  However, in the present invention, since the image of the reading area is corrected to an image when the reading area is a plane perpendicular to the optical axis of the imaging means, the reading area is inclined or the reading area Even if is curved, the inclination and curvature are corrected. Therefore, since the distortion of the information code included in the image of the reading area is also corrected, the reading accuracy of the information code is improved.

  The invention according to claim 3 is based on the distance to a plurality of points in the reading area estimated by the distance estimating means and the depth of field of the imaging means stored in advance, and the amount of blur of the image in the reading area And a blur correction unit that corrects the blur of the image in the reading area based on the blur amount estimated by the blur amount estimation unit. The reading unit is corrected by the blur correction unit. Read processing is performed using the image.

  As described above, if the blur of the image in the reading area is corrected based on the estimated blur amount, the blur can be corrected with high accuracy. Therefore, the reading accuracy of the information code is improved. It should be noted that both the image correction means of claim 2 and the blur correction means of claim 3 can be performed on the image in the reading area. In that case, the other correction means is performed on the image in the reading area corrected by one of the correction means.

  Here, the distance estimation means can estimate distances to a plurality of points of the imaging object as described in claims 4 to 6. According to a fourth aspect of the present invention, a plurality of imaging units having different optical axes and known mutual distances are provided, and the distance estimation unit includes a plurality of imaging targets by a stereo method based on images captured by the plurality of imaging units. Estimate the distance to the point. According to a fifth aspect of the present invention, the optical information reading device is movable, and is provided with position detecting means for detecting the position of the optical information reading device. Then, the distance estimation means uses a stereo method based on the image of the object to be imaged captured by the imaging means at a plurality of different positions and the position of the optical information reading device detected by the position detection means when the image is captured. The distances to a plurality of points on the imaging target are estimated. According to a sixth aspect of the present invention, the laser light transmitting / receiving means for irradiating the laser light while controlling the irradiation direction and receiving the reflected light reflected by the external object is provided. Based on the time difference from the irradiation of the light to the reception of the reflected light and the irradiation direction of the laser light, the distance to a plurality of points on the imaging object is estimated.

It is a fragmentary longitudinal cross-section which shows the structure outline | summary of the housing etc. of an optical information reader. It is an A arrow view of the optical system in the optical information reading apparatus shown in FIG. It is a block diagram which shows the structure outline | summary of the circuit part of an optical information reader. It is a figure which shows the overlap of the imaging area of two light reception sensors 23A and 23B. 3 is a flowchart showing processing executed by a control circuit 40. It is a figure which illustrates a part of image which the image signal of light receiving sensor 23A, 23B shows. It is the figure which divided | segmented the image containing the cylinder 60 of FIG. 6 into the several surface. It is a figure which shows that the cylinder 60 and the background 70 were set as an area | region. This is an example of a part of an image captured by the light receiving sensors 23A and 23B in a state where the cylinder 60 is inclined with respect to the central axis XC of the optical information reading device 10. It is a figure which shows the surface obtained by performing the process of step S1, S2 based on the image of FIG. It is a figure which shows that the cylinder 60 and the background 70 were set as an area | region also when the cylinder 60 inclines. FIG. 6 is a diagram for explaining the processing in step S <b> 8 in FIG. 5, and is an example when the imaging target R is a cylinder 60. FIG. 6 is a diagram for explaining the processing in step S8 in FIG. 5, and is an example in the case where the imaging target R is a rectangular parallelepiped 62.

  Hereinafter, an embodiment in which the optical information reading device of the present invention is applied to a portable optical information reading device for QR code (registered trademark) will be described with reference to the drawings. First, an outline of the configuration of the optical information reading apparatus 10 according to the present embodiment will be described with reference to FIGS. 1 is a partial longitudinal sectional view showing an outline of the configuration of a housing and the like of the optical information reading device 10, and FIG. 2 is a view taken along the arrow A of the optical system in the optical information reading device shown in FIG. FIG. 2 is a block diagram illustrating a schematic configuration of a circuit unit 20 of the optical information reading apparatus 10.

  As shown in FIG. 1, an optical information reading apparatus 10 that reads a QR code Q includes a housing 11 that is a vertically long, substantially rectangular box. The housing 11 is a molded part made of a synthetic resin such as ABS resin, and has a reading port 11a on one end side thereof. The reading port 11a is an opening through which incident light incident on the two light receiving sensors 23A and 23B shown in FIG. 2 can be introduced. As shown in FIG. 1, a secondary battery 49 is accommodated on the other end side of the housing 11. An opening to which the liquid crystal display 46 can be attached is also formed on the surface side of the housing 11 so that the user of the optical information reading apparatus 10 can visually grasp the display contents displayed on the liquid crystal display 46. It is. A circuit unit 20 described later is accommodated in the housing 11. In FIG. 1, printed wiring boards 15 and 16 constituting the circuit unit 20 are illustrated.

  As shown in FIG. 3, the circuit unit 20 mainly includes an optical system such as a pair of red light emitting diodes 21 and a condensing lens 52, light receiving sensors 23A and 23B, and imaging lenses 27A and 27B, a memory 35, and a control circuit. 40, operation switches 12 and 14, and a microcomputer (hereinafter referred to as “microcomputer”) system such as a liquid crystal display 46, which are mounted on the above-described printed wiring boards 15 and 16 or housed in the housing 11. Yes.

  An outline of the configuration of the microcomputer system will be described. The microcomputer system includes amplification circuits 31A, 31B, A / D conversion circuits 33A, 33B, memory 35, address generation circuits 36A, 36B, synchronization signal generation circuits 38A, 38B, control circuit 40, operation switches 12, 14, LED 43, buzzer. 44, a liquid crystal display 46, a communication interface 48, and the like. As the name suggests, this microcomputer system is composed mainly of a control circuit 40 and a memory 35 that can function as a microcomputer (information processing device). Image signals such as code images captured by the optical system described above are obtained. It can perform signal processing in terms of hardware and software. The control circuit 40 also performs control related to the entire system of the optical information reading apparatus 10.

  Image signals (analog signals) output from the light receiving sensors 23A and 23B of the optical system are respectively input to the amplifier circuits 31A and 31B and amplified by a predetermined gain, and then input to the A / D conversion circuits 33A and 33B. Then, the analog signal is converted into a digital signal. The digitized image signal is input to the memory 35 and stored. The synchronization signal generation circuits 38A and 38B are configured to be able to generate synchronization signals for the light receiving sensors 23A and 23B and the address generation circuits 36A and 36B. The address generation circuits 36A and 36B include the synchronization signal generation circuit 38A, The storage address of the image signal in the memory 35 is generated based on the synchronization signal supplied from 38B.

  The control circuit 40 is a microcomputer that can control the entire optical information reading apparatus 10 and includes a CPU, a system bus, an input / output interface, and the like. A specific information processing function of the control circuit 40 in this embodiment will be described later. In addition, the control circuit 40 is configured to be connectable to various input / output devices (peripheral devices) via a built-in input / output interface. In this embodiment, the power switch 41, the operation switches 12, 14, An LED 43, a buzzer 44, a liquid crystal display 46, a communication interface 48, and the like are connected.

  The red light emitting diode 21 constituting the optical system is a light irradiator capable of irradiating the illumination light Lf. The illumination light Lf from the red light emitting diode 21 is condensed by a condenser lens 52 that is a combination of a diffusion lens and a convex lens. In the present embodiment, the red light emitting diodes 21 are provided on both sides of the light receiving sensors 23A and 23B, and the illumination light Lf can be irradiated toward the imaging target R through the reading port 11a of the housing 11. It is configured. The imaging object R is shown with a QR code Q that is a two-dimensional information code. The QR code Q may be affixed to the imaging target R, but in the following description, it is assumed that the QR code Q is formed by engraving.

  The light receiving sensors 23A and 23B are configured to be able to receive the reflected light Lr irradiated and reflected by the imaging object R and the QR code Q via the imaging lenses 27A and 27B. It is comprised by the two-dimensional image sensor (namely, area sensor) which consists of solid-state image sensors, such as. The light receiving sensors 23A and 23B correspond to image capturing means in claims.

  The imaging lenses 27A and 27B function as an imaging optical system capable of condensing incident light incident from the outside through the reading port 11a and forming an image on the light receiving surfaces 24A and 24B of the light receiving sensors 23A and 23B. For example, it is composed of a lens barrel and a plurality of condensing lenses housed in the lens barrel.

  As shown in FIG. 2, in the two light receiving sensors 23A and 23B, the central axes XA and XB of the respective imaging areas are parallel to each other. The two light receiving sensors 23A and 23B are on the same virtual plane (a virtual plane upright from the drawing along the line segment VP) including the common line segment VP orthogonal to the two central axes XA and XB. It is arranged in. The two light receiving sensors 23A and 23B are mounted on the printed wiring board 15 so that the center axes XA and XB of the imaging area are separated by a distance d1. Further, the center axes XA and XB of the imaging areas of the two light receiving sensors 23A and 23B and the center axes Xa and Xb of the imaging lenses 27A and 27B are assembled in a shifted manner. By assembling in this way, the imaging areas of the two light receiving sensors 23A and 23B overlap each other at a constant distance D1, as shown in FIG. The distance d1 is stored in the memory 35 as the distance between the two light receiving sensors 23A and 23B.

  FIG. 5 is a flowchart showing a process executed by the control circuit 40. Next, processing performed by the control circuit 40 will be described with reference to FIG. The processing shown in FIG. 5 is executed following exposure and image capture. The exposure is executed based on the input of the trigger signal by the operation of the operation switches 12 and 14, and the two light receiving sensors 23A and 23B are exposed simultaneously by the exposure, and then the light receiving sensor 23A. , 23B are stored in the memory 35 via the amplifier circuit 31 and the A / D conversion circuit 33. Thereafter, Step S1 is executed.

  Step S1 is a process corresponding to the distance estimation means in the claims. The image signals of all the pixels of the two light receiving sensors 23A and 23B are respectively acquired from the memory 35, and the stereo method is used based on the acquired image signals. Then, the distance from the optical information reader 10 to the imaging object R is calculated.

  More specifically, the feature is detected from the image signal of the light receiving sensor 23A based on edge detection processing and luminance. Similarly, the feature is detected from the image signal of the light receiving sensor 23B. FIG. 6 illustrates a part of an image indicated by the image signals of the light receiving sensors 23A and 23B. FIG. 6A is a part of an image indicated by the image signal of the light receiving sensor 23A, and is an image in which a QR code Q is indicated by marking at the center of a cylinder 60 that is the imaging target R. FIG. 6B is a part of an image indicated by the image signal of the light receiving sensor 23B, and is an image of the same member as that in FIG. In step S1, edge detection processing or the like is performed on the images illustrated in FIGS. 6A and 6B in order to detect features. Subsequently, the features detected from both image signals are made to correspond to each other by a stereo matching method such as an area correlation method based on the edge and luminance. Then, the angles to the features of the imaging lenses 27A and 27B with respect to the optical axes Xa and Xb are determined based on the positions of the corresponding features on the image. Subsequently, the distance from the optical information reading device 10 to the imaging target R is calculated from these angles and the distance d1 between the light receiving sensors 23A and 23B by the principle of triangulation. Note that two distances from the respective light receiving sensors 23A and 23B to the imaging target R can be calculated as the distance here. Of these two distances, the distance on the same side as the image used for the reading process is used below.

  The subsequent step S2 corresponds to the image region dividing means in the claims, and the imaging object R is divided into a plurality of regions using the distance obtained by the processing of step S1, the luminance of the image, and the edge. Specifically, first, the imaging target R is divided into a plurality of surfaces, with a boundary where the change in distance is discontinuous and a point where the edge or luminance change is large as a boundary. Therefore, if there is no edge, the luminance change is small, and the distance change is gentle, the surfaces are the same. And the area | region is set by classifying the surface further into a group by distance. FIG. 7 is a diagram in which an image including the cylinder 60 of FIG. 6 is divided into a plurality of surfaces. When a surface is set as shown in FIG. 7, a cylinder 60 and a background 70 are set as regions (see FIG. 8). It should be noted that the distance is used both when setting the surface and when setting the region, but when setting the region, the region is set as a separate region when the difference in the distance is larger than when dividing the surface.

  FIG. 9 shows a state in which the column 60 is inclined with respect to the central axis XC (see FIG. 2) of the optical information reader 10 (meaning that it is not perpendicular to the central axis XC). FIG. 10 shows an example of a part of a captured image, and FIG. 10 is a diagram illustrating a surface obtained by performing the processing of steps S1 and S2 based on the image of FIG. Since the column 60 is inclined, the column 60 is divided into different planes from one end toward the other end as indicated by arrows in FIG. However, since the change in the distance between the adjacent surfaces is small, even when the cylinder 60 is inclined as described above, two regions of the cylinder 60 and the background 70 are set as shown in FIG. .

  The subsequent step S3 corresponds to the area selection means in the claims, and selects the area to be read from the plurality of areas divided in step S2. The area is selected based on the following three area selection conditions. These three area selection conditions are (1) existing in the vicinity of the center of the image, (2) located in the front, and (3) an area having a certain size. These three area selection conditions are that when a code is imaged, it is usually considered that the code is imaged near the center of the image, it is considered that the image is not imaged when the code is hidden by something, and the code is not very narrow. Is a condition that is set because it is considered that it is not arranged. Under the condition (3), even if the element on the substrate satisfies (1) and (2), the element is not selected as the reading region. Further, in the examples of FIGS. 8 and 11, the area of the cylinder 60 satisfies all the conditions (1) to (3), so that it is selected as an area to be read.

  In a succeeding step S4, it is determined whether or not an area to be read can be determined, that is, whether or not an area can be selected in step S3. If the area cannot be divided properly or there is no area that meets the area selection condition, the area cannot be selected in step S3. In this case, the determination in step S4 is negative.

  If the determination in step S4 is negative, the process proceeds to step S12 to read the entire range. The whole range reading is to acquire an image signal of a preset whole range of the light receiving sensor 23, perform binarization processing, decoding processing, etc. on the image signal of the whole range and obtain information from the QR code Q. Read processing. Here, the entire range may be all pixels, or in the case where a range marker is irradiated, may be a pixel in a range defined by the range marker. In the present embodiment, the two light receiving sensors 23A and 23B are provided. However, which light receiving sensor 23A and 23B is used is preset.

  If step S4 is affirmative, step S5 and subsequent steps are executed. In step S5, distortion of the image in the reading area is determined. For determination of image distortion, the distance obtained in the process of step S1 is used for the reading area selected in step S3. Specifically, first, a reference point (for example, the image center) is determined from the points where the distance can be determined in the reading area. Then, assuming that the reading area is a plane that includes the reference point and is perpendicular to the central axis XC of the optical information reading device 10, the distance of another point in the reading area (referred to as a plane assumed distance) is calculated. Then, the assumed plane distance is compared with the distance obtained in the process of step S1, and at each point, it is determined that there is no distortion if the difference between both distances is equal to or less than a predetermined value. If there is a point where the difference is greater than a predetermined value, it is determined that there is distortion. Note that the distortion of the image determined in this way is due to the imaging object R being tilted or the reading area being not flat (curved).

The subsequent step S6 corresponds to the blur amount estimation means in the claims. In step S6, the blur of the image in the reading area is determined. The blur is determined based on whether the distance to the reading area is within the depth of field. Here, as the distance to the reading area, the distance between the center of the reading area or the point closest to the center of the reading area among the points capable of determining the distance in the reading area and the optical information reading apparatus 10 is used. . As is well known, the depth of field includes a front depth of field Lf and a rear depth of field Lr. The forward depth of field Lf and the backward depth of field Lr are each expressed by the following equations.

  In the equation, δ represents an allowable circle of confusion, F represents an F value, f represents a focal length, and L represents a best focus.

  When the distance to the reading area is within the depth of field, it is determined that there is no blur. On the other hand, if the distance to the reading area is outside the range of the depth of field, the length deviating from the depth of field is calculated as the amount of blur.

  In subsequent step S7, it is determined whether or not it is determined in step S5 that there is distortion. If this determination is affirmative, the process proceeds to step S8, and if negative, the process proceeds to step S9 without passing through step S8.

  Step S8 corresponds to the image correction means in the claims, and performs distortion correction on the image in the reading area. In this correction, the image in the reading area is corrected to an image when it is a plane perpendicular to the optical axis X of the imaging lens 27 on the side where the image in the reading area is captured. Step S8 will be specifically described with reference to FIGS. FIG. 12 is an example in the case where the imaging target R is a cylinder 60, and conceptually shows a pre-correction image 80 and a post-correction image 82 in a cross section perpendicular to the axis of the cylinder 60. Since FIG. 12 is a cross section perpendicular to the axis of the cylinder 60, the uncorrected image 80 and the corrected image 82 are line segments in FIG. The pre-correction image 80 is an image obtained by projecting the cylinder 60 onto the virtual plane P. Therefore, the post-correction image 82 can be created, for example, by performing inverse transformation of projection conversion on the pre-correction image 80. The corrected image 82 created in this way is an image in which a curved reading area is developed on the virtual plane P.

  FIG. 13 is an example in the case where the imaging target R is a rectangular parallelepiped 62, and conceptually shows an uncorrected image 90 and a corrected image 92 in a cross section obtained by cutting the rectangular parallelepiped 62 along a plane including the optical axis X of the imaging lens 27. Is shown. In the example of FIG. 13, the surface of the cuboid 62 facing the imaging lens 27 is not perpendicular to the optical axis X of the imaging lens 27. More specifically, in the example of FIG. 13, if a point on the optical axis X in the reading area is a reference point, and a plane that passes through the reference point and is perpendicular to the optical axis X is a virtual plane P, it is more illustrated than the reference point. The upper side is closer to the imaging lens 27 than the virtual plane P, and the lower side of the drawing is closer to the imaging lens 27 than the virtual plane P than the reference point. In this case, when the post-correction image 92 is compared with the pre-correction image 90, the post-correction image 92 has a length lower than the reference point in the figure before the correction 90, and is higher in the figure than the reference point. The length is shorter than the pre-correction image 90. Also in the case of FIG. 13, the corrected image 92 is obtained by converting the pre-correction image 90 by inverse conversion of projection conversion or the like.

  Returning to FIG. In step S9, it is determined whether or not it is determined in step S6 that there is a blur. If this determination is affirmative, the process proceeds to step S10, and if negative, the process proceeds to step S11 without passing through step S10.

  Step S10 corresponds to the blur correction unit in the claims, and corrects the blur of the image in the reading area based on the blur amount calculated in step S6. Specifically, a sharpening filter with a coefficient set according to the amount of blur is applied, or an edge detection process with a coefficient or threshold set according to the amount of blur is performed.

  In step S11, an area reading process is performed. In the area reading process, the reading process is performed using an image of a reading area that has been subjected to distortion correction or blur correction according to the determination results of distortion determination (step S5) and blur determination (step S6). Except for the difference, the processing is the same as the reading processing in step S12.

  As described above, according to the present embodiment described above, the distance from the optical information reading device 10 to a plurality of points of the imaging target R is measured (step S1), and the image captured by the light receiving sensor 23 based on the measured distance. Is divided into a plurality of regions (step S2). Since the image is divided into a plurality of regions according to the distance, unlike the case where the region is divided based on the luminance change or the edge, various luminance changes other than the luminance change caused by the QR code Q are present in the imaging target R. Is not affected. Therefore, it is possible to narrow down to a region including the QR code Q with high accuracy, and the case where the subsequent reading process is performed again is reduced, so that the reading speed is improved. In addition, since the accuracy of narrowing down the area is improved, the information reading accuracy is also improved.

  Further, according to the present embodiment, utilizing the fact that the distance from the optical information reading device 10 to the imaging target R is measured, the image of the reading area is displayed as the light of the imaging lens 27. It is corrected to an image when it is a plane perpendicular to the axis X (step S8). Therefore, even if the reading area is inclined or the reading area is curved, the inclination and the curvature are corrected. As a result, the distortion of the QR code Q included in the image of the reading area is also corrected. This also improves the reading accuracy of the QR code Q.

  Furthermore, according to the present embodiment, the amount of blur in the reading area is estimated using the measurement of the distance from the optical information reading device 10 to the imaging target R (step S6). Since the blur of the image in the reading area is corrected based on the estimated blur amount, the blur can be corrected with high accuracy. This also improves the reading accuracy of the QR code Q.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following embodiment is also contained in the technical scope of this invention, and also the summary other than the following is also included. Various modifications can be made without departing from the scope.

  For example, in the above-described embodiment, two sets of the light receiving sensor 23 and the corresponding optical system are provided, and the stereo method calculation is performed based on the image signals from the two light receiving sensors 23. However, if a position detecting means for detecting the relative or absolute position of the optical information reading device 10 is provided, the light receiving sensor 23 and the corresponding optical system can be made into one set. As this position detecting means, for example, a speed sensor that detects the moving speed together with the moving direction, a time measuring means that measures the time difference between the imaging time point and the next imaging time point, a moving direction obtained by the speed sensor and the time measuring means The position calculating means can detect a change in position by calculation from the moving speed and the time difference.

  In the case of a configuration including position detection means, the imaging object R is imaged at a plurality of different positions (for example, two locations), and the imaging position is detected by the position detection means. Further, a relative change in the orientation of the optical information reading device 10 is also detected. For example, a triaxial acceleration sensor or a gyro sensor is used to detect the orientation of the optical information reader 10. Moreover, you may obtain | require speed using the sensor which detects these directions. If the imaging position and the orientation at the time of imaging can be detected in this way, the stereo method can be applied as in the above-described embodiment.

  The distance to the imaging object R may be measured by a laser without being limited to the stereo method. In this case, the optical information reading device 10 is provided with a laser beam transmitting / receiving unit that irradiates the laser beam while controlling the irradiation direction and receives the reflected light reflected by the external object. Then, the distance to a plurality of points on the imaging target is estimated based on the time difference from the irradiation of the laser light to the reception of the reflected light of the laser light and the irradiation direction of the laser light.

  In the above-described embodiment, when a region is divided, a luminance change and an edge are used in addition to a change in distance. However, a region may be divided only by a change in distance. In the above-described embodiment, a reading area is selected from a plurality of areas using three area selection conditions. However, only one or two of the three conditions may be used. Alternatively, other conditions may be used instead of the conditions (1) to (3), and other conditions may be added in addition to the conditions (1) to (3). .

  Moreover, although the optical information reader 10 of the above-mentioned embodiment was a portable type, the present invention can also be applied to a fixed type. The optical information reading device may be movable along the rail. Further, in that case, a sensor for detecting the position of the optical information reading device may be provided on the rail as the position detecting means.

10: Optical information reading device, 11: Housing, 11a: Reading port, 12: Operation switch, 14: Operation switch, 15: Printed wiring board, 16: Printed wiring board, 20: Circuit section, 21: Red light emitting diode, 23 : Light receiving sensor, 24: light receiving surface, 27: imaging lens, 31: amplifier circuit. 33: A / D conversion circuit, 35: Memory, 36: Address generation circuit, 38: Synchronization signal generation circuit, 40: Control circuit, 41: Power switch, 43: LED, 44: Buzzer, 46: Liquid crystal display, 48 : Communication interface, 49: Secondary battery, 52: Condensing lens, 60: Cylinder, 62: Rectangular parallelepiped, 70: Background, 80: Image before correction, 82: Image after correction, 90: Image before correction, 92: After correction Image, P: Virtual plane, Q: QR code R: Imaging object, Lf: Illumination light, Lr: Reflected light, VP: Line segment, XA, XB: Central axis (of imaging area), Xa, Xb: Optical axis XC: central axis (of the optical information reading device 10), S1: distance estimation means, S2: image area division means, S3: area selection means, S6: blur amount estimation means, S10: blur correction means

Claims (6)

An image capturing unit that captures an image of the imaging target indicated by the information code; and a reading processing unit that narrows down a reading area from the image captured by the imaging unit and performs a reading process on the image in the reading area. An optical information reading device for reading information from an information code,
Distance estimating means for estimating the distance from the optical information reader to a plurality of points of the imaging object;
An image region dividing unit that divides the image captured by the imaging unit into a plurality of regions based on the distance estimated by the distance estimating unit;
An optical information reading apparatus comprising: an area selecting unit that selects the reading area from a plurality of areas divided by the image area dividing unit. In claim 1,
Based on the distances to a plurality of points in the reading area estimated by the distance estimating means, an image of the reading area is assumed to be a plane perpendicular to the optical axis of the imaging means. Image correction means for correcting the image,
The optical information reading apparatus, wherein the reading unit performs a reading process using the image corrected by the image correcting unit. In claim 1 or 2,
Based on the distances to a plurality of points in the reading area estimated by the distance estimation means and the depth of field of the imaging means stored in advance, the blur for estimating the blur amount of the image in the reading area A quantity estimation means;
A blur correction unit that corrects the blur of the image in the reading area based on the blur amount estimated by the blur amount estimation unit;
The optical information reading apparatus, wherein the reading unit performs a reading process using the image corrected by the blur correction unit. In any one of Claims 1-3,
A plurality of imaging means having different optical axes and known distances from each other;
The optical information reading apparatus, wherein the distance estimation unit estimates a distance to a plurality of points of the imaging target object by a stereo method based on images captured by the plurality of imaging units. In any one of Claims 1-3,
The optical information reader is movable,
A position detecting means for detecting the position of the optical information reader;
The distance estimation means is a stereo based on the image of the imaging object captured by the imaging means at a plurality of different positions and the position of the optical information reader detected by the position detection means when the image is captured. An optical information reading apparatus, wherein distances to a plurality of points of the imaging object are estimated by a method. In any one of Claims 1-3,
While irradiating the laser beam while controlling the irradiation direction, the laser beam transmitting and receiving means for receiving the reflected light reflected from the external object,
The distance estimating means calculates distances to a plurality of points of the imaging object based on a time difference between the laser light transmitting / receiving means irradiating laser light and receiving reflected light and a laser light irradiation direction. An optical information reading apparatus characterized by estimating.