Image acquisition device, inspection device, and image acquisition method

Abstract

An image acquisition device (1) is provided with: an illumination device (2) that irradiates an object (S) with light from the range of a light irradiation unit (2a); and an imaging device (7) that detects, via the imaging lens (7a), light that has been positively reflected by the object (S), and in which a straight line connecting the center of the light irradiation unit (2a) and the point of intersection between the optical axis and the object (S) is set so as to be inclined at 2-120 degrees with respect to the optical axis of the imaging lens (7a). The solid angle of the light irradiation part (2a) observed from the intersection point is set to be more than 0 degree of sphericity and less than 0.15 degree of sphericity.

Description

Technical Field

[0001] One aspect of the embodiment relates to an image acquisition device, an inspection device, and an image acquisition method. Background Art

[0002] Conventionally, a device for inspecting an object by detecting light irradiated on the object has been known. For example, the device described in Patent Document 1 below detects transmitted light that has passed through the object and reflected light that has been reflected by the object by a imaging unit, and inspects the object based on detection data output from the imaging unit.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-189071 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] Based on the detection data obtained by the existing device as described above, it is difficult to detect an object having the property of reflected light in the object to be inspected. Therefore, it is required to obtain data capable of efficiently detecting an object having the property of reflected light on the object to be inspected.

[0008] Therefore, one aspect of the embodiment has been completed in view of the above technical problems, and the technical problem thereof is to provide an image acquisition device, an inspection device, and an image acquisition method capable of acquiring image data capable of efficiently detecting an object having the property of reflected light on an object to be inspected.

[0009] Technical Means for Solving the Problem

[0010] The image acquisition device according to the first aspect of the embodiment includes: a light irradiation device that irradiates light from the range of a light irradiation unit onto an object; and an imaging device that detects light that has been specularly reflected by the object via an imaging lens, a straight line connecting the center of the light irradiation unit and the intersection of the optical axis and the object is set to be inclined at 2 degrees or more and 120 degrees or less with respect to the optical axis of the imaging lens, and the solid angle of the light irradiation unit as observed from the intersection is set to be 0 steradians or more and 0.15 steradians or less.

[0011] Alternatively, the image acquisition method according to the second aspect of the embodiment includes: a light irradiation step of irradiating an object with light from the range of the light irradiation unit using a light irradiation device; and an imaging step of detecting, using an imaging device via an imaging lens, the light that has been specularly reflected by the object. A straight line connecting the center of the light irradiation unit and the intersection point of the optical axis and the object is set to be inclined at 2 degrees or more and 120 degrees or less with respect to the optical axis of the imaging lens, and the solid angle of the light irradiation unit observed from the intersection point is set to be 0 steradians or more and 0.15 steradians or less.

[0012] According to the above first aspect or the above second aspect, when there is an object having the property of reflecting light on the object, specular light from the object can be efficiently incident on the imaging device via the imaging lens, and at the same time, the intensity of the specular light incident from the object can be made sufficiently greater than the intensity of the diffused light incident from the object. In particular, by setting the solid angle of the light irradiation unit observed from the intersection point of the optical axis of the imaging lens and the object to be 0 steradians or more and 0.15 steradians or less, the ratio of the intensity of the specular light to the intensity of the diffused light can be increased non-linearly. As a result, image data capable of efficiently detecting an object having the property of reflecting light on the object can be obtained.

[0013] Alternatively, the inspection device according to the third aspect of the embodiment includes: the image acquisition device according to the first aspect; a conveying device that conveys the object in a predetermined direction; and an inspection processing unit that inspects the object based on data output from the image acquisition device.

[0014] According to the above third aspect, while conveying a plurality of objects, it is possible to efficiently detect objects having the property of reflecting light on the plurality of objects.

[0015] Effects of the Invention

[0016] According to any aspect of the present invention, image data capable of efficiently detecting an object having the property of reflecting light on the object can be obtained. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the image acquisition device 1 according to the embodiment.

[0018] Figure 2 is a diagram showing Figure 1 the image of the reflected light generated in the object S when using the

[0019] Figure 3 image acquisition device 1.

[0020] Figure 4It is a graph showing the relationship between the solid angle ω in the image acquisition device 1 and the signal ratio representing the detection accuracy.

[0021] Figure 5 It is a graph showing the relationship between the solid angle ω in the image acquisition device 1 and the signal ratio representing the detection accuracy.

[0022] Figure 6 It is a schematic configuration diagram of the inspection system 100 of the embodiment.

[0023] Figure 7 It is a flowchart showing the sequence of the inspection method of the object S using the inspection system 100.

[0024] Figure 8 It is a schematic configuration diagram of the image acquisition device 1A of the modification.

[0025] Figure 9 It is a schematic configuration diagram of the image acquisition device 1B of the modification.

[0026] Figure 10 It is a schematic configuration diagram of the image acquisition device 1C of the modification.

[0027] Figure 11 It is a diagram showing the image data acquired by the image acquisition device 1B of the modification.

[0028] Figure 12 It is a diagram showing the image data acquired by the image acquisition device of the comparative example. Detailed Embodiment

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same functions, and duplicate descriptions are omitted.

[0030] Figure 1 It is a schematic configuration diagram of the image acquisition device 1 of the embodiment. The image acquisition device 1 is a device that acquires image data of an object for the purpose of inspecting for foreign substances on an object such as food. However, the object to be inspected by the image acquisition device 1 may be other items such as electronic components in addition to foods represented by beef, pork, chicken, mutton, processed foods, etc.

[0031] The image acquisition device 1 includes an illumination device (light irradiation device) 2, an imaging device 7, and an image processing device 8. Hereinafter, the details of each component of the image acquisition device 1 will be described.

[0032] The lighting device 2 is composed of a light irradiation unit 2a that irradiates light and a main body unit 2b that houses a lighting circuit for lighting the light-emitting elements in the light irradiation unit 2a, and irradiates light by diffusing the light toward the object S. Examples of the light-emitting elements built in the light irradiation unit 2a include LEDs, SLDs (Superluminescent diodes), lasers, halogen lamps, and the like. The light irradiation unit 2a houses one or more point light sources, i.e., light-emitting elements, and has a structure capable of diffusing and irradiating light from the light-emitting range of the dot-like light irradiation unit 2a via a lens, a diffusion plate, or the like. The shape of the light-emitting range of the light irradiation unit 2a may be planar or curved such as a spherical surface.

[0033] The imaging device 7 is a device that is arranged to detect the position of the reflected light generated by the object S reflecting the light irradiated from the lighting device 2, and detects a two-dimensional image of the light including the reflected light to obtain image data. As the imaging device 7, a CMOS (Complementary Metal Oxide Semiconductor) camera, a CCD (Charge Coupled Device) camera, or the like is used. In the case where the object S is conveyed in a predetermined direction by a conveying device, a line sensor camera or a TDI (Time Delay Integration) sensor camera may also be used as the imaging device 7.

[0034] The imaging device 7 includes an imaging lens 7a. The imaging lens 7a forms a two-dimensional image of the light including the reflected light from the object S on the light-receiving surface (not shown) of the imaging element inside the imaging device 7. The imaging device 7 detects the light including the reflected light from the object S via the imaging lens.

[0035] The image processing device 8 is a device that detects foreign matter on the object S by receiving the image data acquired by the imaging device 7. Physically, the image processing device 8 is an arithmetic device (such as a computer) incorporating a CPU (Central Processing Unit), which is a processor, or a GPU (Graphics Processing Unit), a RAM (Random Access Memory) or a ROM (Read Only Memory) as a recording medium, a communication module, an input / output module, etc. In addition, the image processing device 8 may be composed of an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The image processing device 8 can acquire image data from the imaging device 7 via a cable or by wireless communication.

[0036] Here, with reference to Figure 2 , the detection mechanism of the reflected light from the object S in the image acquisition device 1 will be described. Figure 2 is a diagram showing an image of the reflected light generated in the object S when the image acquisition device 1 is used.

[0037] Each light ray L0 of the light diffused and irradiated by the lighting device 2 widely reaches the surface of the object S. The object S such as food has the property of generating specularly reflected light L1 and diffusely reflected light L2 when light is incident. In addition, when there is a foreign object FS such as a plastic film, which is an object having the property of transmitting light, on the surface of the object S, specularly reflected light L3 that is specularly reflected on the surface of the foreign object FS, specularly reflected light L4 that is specularly reflected on the back surface of the foreign object FS after passing through the foreign object FS, and diffusely reflected light L5 that is diffusely reflected by the foreign object FS are generated by the light ray L0 of the light incident on the foreign object FS. In this case, the intensities of the specularly reflected lights L3 and L4 are higher than that of the specularly reflected light L1, and since the foreign object FS has the property of transmitting light, their intensities are higher than that of the diffusely reflected light L5.

[0038] In order to two-dimensionally detect the reflectance of the reflected light from the object S by using the properties of the above-mentioned reflected light, the image processing device 8 of the image acquisition device 1 acquires and stores the image data of the object S from the imaging device 7. Based on the image data stored in the image processing device 8, the brightness distribution of the image data is analyzed to search for the part where the intensity of the specularly reflected light is relatively high, thereby enabling the inspection of the presence or absence of the foreign object FS.

[0039] Next, with reference toFigure 3 , the structures of the illumination device 2 and the imaging device 7 in the image acquisition device 1 will be described in detail. Figure 3 It is a diagram showing the arrangement of the illumination device 2 relative to the imaging device 7 in the image acquisition device 1 and the light emission range of the illumination device 2.

[0040] The imaging device 7 is arranged at a position and orientation such that the optical axis A1 of the imaging lens 7a intersects the object S when inspecting the object S. In contrast, the illumination device 2 is set such that, with respect to the light emission range R1 of its light irradiation unit 2a, the solid angle ω observed from the intersection point P1 of the optical axis A1 and the object S falls within a specified range, and the straight line A2 connecting the center C1 of the light emission range R1 and the intersection point P1 is inclined at an angle θ within a specified angular range with respect to the optical axis A1. Here, the solid angle ω refers to the spread size of the light emission range R1 observed from the intersection point P1, and corresponds to the area of the portion R2 cut on a sphere with a radius of 1 by a half-line within the light emission range R1 having the intersection point P1 as an end point. Specifically, in the image acquisition device 1 of the present embodiment, the solid angle ω of the light emission range R1 is set to be 0 sr (steradian) or more and 0.15 sr or less, and the angle θ of the straight line A2 with respect to the optical axis A1 is set to be 2 degrees or more and 120 degrees or less.

[0041] The following shows the experimental results related to the detection accuracy of the image acquisition device 1 having the above structure. In the experiment, an object S with a foreign object FS of known position was used as the object, and the detection accuracy was evaluated while changing the reflectivity of the foreign object FS, the solid angle ω, and the parameters of the imaging lens 7a.

[0042] Figure 4 It is a graph showing the relationship between the solid angle ω and the signal ratio indicating the detection accuracy when the solid angle ω is set relatively small and the F value of the imaging lens 7a is changed to 1.6, 2, 4, and 8 in the experiment. The signal ratio is a value calculated by dividing the maximum brightness at the position of the foreign object FS by the average brightness at the positions of the surrounding objects, and indicates the level of detection accuracy of the foreign object FS. According to the experimental results, in any case of the F value, as the solid angle ω decreases from 0.004 sr to 0 sr, the signal ratio increases. In addition, in the range where the solid angle ω is 0.002 sr or less, the signal ratio increases when the F value is large, but even when the F value changes from around when the solid angle ω exceeds 0.002 sr, the change in the signal ratio with respect to the change in the solid angle ω has substantially the same characteristics. This means that in the range where the solid angle ω exceeds 0.002 sr, the detection accuracy does not depend on the observation conditions of the imaging device 7.

[0043] Here, a theoretical model is used to estimate the above signal ratio related to the image data acquired by the image acquisition device 1 through calculation. Assume the object-side solid angle of the imaging lens 7a calculated based on the F value and magnification of the imaging lens 7a as Cam_sr [sr], the solid angle of the light-emitting range R1 of the illumination device 2 as LS_sr [sr], and the reflectivity of the foreign object FS as Rs. The intensity of the direct reflected light from the foreign object FS in the image data is estimated by a relative value calculated by Rs × Cam_sr. On the other hand, the intensity of the scattered light from the object S around the foreign object FS is estimated by a relative value calculated by LS_sr × Cam_sr / 2π. Therefore, according to this theoretical model, the signal ratio SNr is calculated by the following formula

[0044] SNr = 2π × Rs / LS_sr + 1

[0045] to calculate.

[0046] Figure 5 is a graph showing the relationship between the solid angle ω and the signal ratio representing the detection accuracy when the reflectivity of the foreign object FS is set between 2% and 10% and the solid angle ω is varied within the range of 0 sr to 0.4 sr and calculated by the above theoretical model. According to this calculation result, in any case of the reflectivity, as the solid angle ω becomes smaller, the signal ratio becomes higher. If the reflectivity is set higher, the overall signal ratio characteristic also shifts in the direction of a higher signal ratio. Especially in the range where the solid angle ω exceeds about 0.15 sr, the signal ratio changes linearly with respect to the solid angle ω. In the range where the solid angle ω is 0 sr or more and less than about 0.15 sr, the signal ratio changes non-linearly with respect to the solid angle ω, and the increase rate of the signal ratio corresponding to the decrease of the solid angle ω increases significantly. That is, the signal ratio SNr is determined only by the reflectivity Rs and the solid angle LS_sr, which is very consistent with the Figure 4 measurement results of the characteristics of the signal ratio shown. Considering such characteristics of the detection accuracy, in the image acquisition device 1 of the present embodiment, the solid angle ω is set in the range of 0 sr or more and less than about 0.15 sr. By such a setting, in the image data acquired by the image acquisition device 1, the image of the foreign object FS can be embossed.

[0047] Next, the structure of the inspection system 100 as an inspection device of the embodiment will be described. Figure 6 is a schematic structure of the inspection system 100 of the embodiment.

[0048] The inspection system 100 includes the image acquisition device 1 having the above structure, a conveying device 11 such as a belt conveyor that conveys the object S in a specified direction, and a computer (inspection processing unit) 12 that performs operations on the image data output from the image acquisition device 1. The image acquisition device 1 acquires image data with the object S conveyed by the conveying device 11 as the object, and outputs the acquired image data to the computer 12. In the inspection system 100, it can be controlled to acquire image data by imaging the object S through the image acquisition device 1 while the object S is being conveyed by the conveying device 11. In the inspection system 100, it can also be controlled to acquire image data by imaging the object S through the image acquisition device 1 while the conveyance of the object S by the conveying device 11 is stopped. When imaging is performed while the object S is being conveyed, it is preferable to use a line sensor as the imaging device 7, and when imaging is performed while the conveyance of the object S is stopped, it is preferable to use an area sensor as the imaging device 7. When imaging is performed while the object S is being conveyed, it is also possible to perform imaging using an area sensor as the imaging device 7 while intermittently lighting the lighting device 2.

[0049] The computer 12 has the same hardware structure as the image processing device 8. That is, the computer 12 is an arithmetic device that physically incorporates a CPU or GPU as a processor, a RAM or ROM as a recording medium, a communication module, an input / output module, etc. The computer 12 can acquire image data from the image processing device 8 via a cable, or can also acquire image data from the image processing device 8 through wireless communication.

[0050] Functionally, the computer 12 performs an inspection process on the object S based on the image data. That is, the computer 12 refers to a plurality of image data obtained with the object S as the object, determines the brightness difference, and determines the range of the foreign matter FS in the object S based on the determined brightness difference. Then, the computer 12 outputs an inspection result image indicating the range of the foreign matter FS determined for one object S to an output device such as a display. In addition, the computer 12 can also output the inspection result image to an external device via a network, a recording medium, etc.

[0051] Next, a method for inspecting the object S using the inspection system 100 will be described, and the image acquisition method of the present embodiment will be described in detail. Figure 7 It is a flowchart showing the sequence of the method for inspecting the object S.

[0052] First, when the inspection process of the object S starts, the conveyance of the object S by the conveyance device 11 starts (step S1). After that, when the object S is conveyed by the conveyance device 11 into the irradiation range of the light from the lighting device 2, light is irradiated from the lighting device 2 to the object S (step S2).

[0053] Accordingly, the reflected light generated on the surface of the object S is incident on the imaging device 7 via the imaging lens 7a, and the imaging device 7 detects a two-dimensional image of the reflected light, thereby outputting image data (S3).

[0054] After the image data acquired by the imaging device 7 is acquired and stored by the image processing device 8, it is output to the computer 12 and processed in the computer 12. That is, the computer 12 determines the range of the foreign matter FS on the object S based on the brightness of each pixel of the image data (step S4). Finally, the computer 12 outputs the inspection result image of the object S to the output device as an image detecting the foreign matter FS existing on the object S (step S5), and ends the inspection process of the object S.

[0055] The effects of this embodiment will be described.

[0056] According to the image acquisition device 1 of this embodiment, when there is a foreign matter FS having the property of reflected light on the object S, the direct reflected light from the foreign matter FS can be efficiently incident on the imaging device 7 via the imaging lens 7a, and at the same time, the intensity of the direct reflected light incident from the foreign matter FS can be made sufficiently greater than the intensity of the diffused light incident from the object S. In particular, by setting the solid angle ω of the light emitting range R1 of the light irradiating unit 2a observed from the intersection point P1 of the optical axis A1 of the imaging lens 7a and the object S to be not less than 0 steradian and not more than 0.15 steradian, the ratio of the intensity of the above-mentioned direct reflected light to the intensity of the above-mentioned diffused light can be increased non-linearly. As a result, image data capable of efficiently detecting the foreign matter FS having the property of reflected light on the object S can be obtained.

[0057] In addition, in the image acquisition device 1, the illumination device 2 has a light emitting range of the dot-shaped light irradiating unit 2a. In this case, the intensity of the direct reflected light incident from the foreign matter FS can be made sufficiently greater than the intensity of the diffused light incident from the object S by a simple structure. As a result, image data capable of efficiently detecting the foreign matter FS having the property of reflected light on the object S can be obtained by a simple structure. In addition, when the illumination device 2 has a structure in which light emitting elements serving as a plurality of point light sources are built in the light irradiating unit 2a, image data capable of efficiently detecting the foreign matter FS in a wide range of the object S can be obtained.

[0058] Alternatively, according to the inspection system 100 of this embodiment, while conveying a plurality of objects S, the foreign matter FS having the property of reflected light on the plurality of objects S can be effectively detected.

[0059] As described above, various embodiments of the present invention have been explained. However, the present invention is not limited to the above-described embodiments, and can also be modified within the scope of the gist described in the claims, or applied to other embodiments.

[0060] The foreign matter FS to be inspected by the inspection system 100 of the present embodiment widely includes substances having the property of reflecting light, and includes not only transparent bodies such as plastic films but also colored translucent objects.

[0061] In addition, as in Figure 8 the image acquisition device 1A of the modified example shown, an illumination device 102 having a linear light irradiation unit 103 can be used. The illumination device 102 is provided with a plurality of light emitting elements 104 as point light sources along the long strip-shaped light emitting range of the light irradiation unit 103. According to such a structure, it is possible to obtain image data capable of efficiently detecting foreign matter FS having the property of reflecting light in a wide range of the object S. In the case of such a structure, the numerical range of the solid angle ω of the light emitting range R1 and the range of the angle θ of the straight line A2 with respect to the optical axis A1 ( Figure 3 ) are also set to the same range as in the above-described embodiment. In particular, when the image acquisition device 1A performs imaging in a state where the object S is being conveyed by the conveying device 11, it is preferably used in combination with the imaging device 7 as a line sensor.

[0062] In addition, as in Figure 9 the image acquisition device 1B of the modified example shown, an illumination device 202 having an annular light irradiation unit 203 arranged so as to surround the optical axis A1 of the imaging lens 7a can be used. The illumination device 202 is provided with a plurality of light emitting elements 104 as point light sources along the annular light emitting range of the light irradiation unit 203. In the case of such a structure, the numerical range of the solid angle ω of the light emitting range R1 and the range of the angle θ of the straight line A2 with respect to the optical axis A1 ( Figure 3 ) are also set to the same range as in the above-described embodiment. In particular, when the image acquisition device 1B performs imaging in a state where the conveyance of the object S is stopped, it is preferably used in combination with the imaging device 7 as an area sensor.

[0063] In addition, as in Figure 10As in the image acquisition device 1C of the illustrated modification example, as the illumination device 302, it may also be configured to include a laser light source 304 and a light scanning unit 303 that scans the object S with the light emitted from the laser light source 304. The light irradiation unit is formed by this light scanning unit 303. As the light scanning unit 303, for example, a movable mirror or the like is used. The image acquisition device 1C may also have a structure that can change the light irradiation direction of the laser light source 304 itself instead of the light scanning unit 303. In this case, as the imaging device 7, a laser scanning optical system that reconstructs an image based on detection signals at each scanning position of light may also be used. In the case of such a structure, the numerical range of the solid angle ω of the light emission range R1 and the range of the angle θ of the straight line A2 with respect to the optical axis A1 ( Figure 2 ) are also set to the same ranges as those in the above-described embodiment. According to such a structure, it is possible to acquire image data that can efficiently detect foreign matter FS having the property of reflected light within a wide range of the object S.

[0064] In addition, the illumination devices 2, 102, 202, 302 of the above-described embodiment and each modification example may also combinatorially include various optical components such as slits as components that limit the light irradiation range to the light emission range R1 of the light irradiation unit and limit the light irradiation angle. In this case, it is possible to set the range of the light irradiation unit with a simple structure, and it is possible to acquire image data that can efficiently detect foreign matter FS having the property of reflected light on the object S with a simple structure.

[0065] In addition, the illumination devices 2, 102, 202 of the above-described embodiment and each modification example form the light emission range R1 into a dot shape, a linear shape, or a ring shape by a plurality of light emitting elements, but this shape may be any curved shape or any shape such as an angular shape. The plurality of light emitting elements may be arranged continuously or discretely. In addition, the illumination devices 2, 102, 202 may be controlled to turn on a plurality of light emitting elements simultaneously, may be controlled to turn on partially, or may be controlled to turn on sequentially.

[0066] Here, Figure 11 shows an example of the image data acquired by the image acquisition device 1B of the modification example. This image data is acquired under the conditions that the diameter of the light irradiation unit 203 of the illumination device 202 is set to 65 mm, the distance between the light irradiation unit 203 and the object S is set to 330 mm, the solid angle ω of the light emission range R1 is set to 0.015 steradians, and the angle θ of the straight line A2 with respect to the optical axis A1 is set to 5.7 degrees. In this way, through the image acquisition device 1B, it is possible to acquire image data in which the portion of the foreign matter FS is more embossed than the portion of the object S.

[0067] In addition, Figure 12This shows an example of the image data obtained by the image acquisition device of the comparative example. In this comparative example, the diameter of the light irradiation unit 203 of the illumination device 202 was set to 65 mm, the distance from the light irradiation unit 203 to the object S was set to 70 mm, the solid angle ω of the light emission range R1 was set to 0.29 steradians, and the angle θ between the straight line A2 and the optical axis A1 was set to 25 degrees. In the image data obtained in such a modified example, the difference in brightness between the part of the foreign object FS and the part of the object S disappeared. As a result, it is difficult to detect the presence of the foreign object FS based on the image data.

[0068] In addition, in the above-described image acquisition devices 1, 1A, 1B, and 1C, the angle θ between the straight line A2 and the optical axis A1 can also be set to be 2 degrees or more and 90 degrees or less. By setting it in this way, when the planar object S is the inspection object, the specular reflection light from the foreign object FS on the object S generated by the light from the light irradiation units of the illumination devices 2, 102, 202, and 302 can be made to enter the imaging device 7 more efficiently, and thus the ratio of the intensity of the specular reflection light incident from the foreign object FS to the intensity of the diffused light incident from the object S can be further increased. As a result, image data capable of efficiently detecting the foreign object FS on the planar object S can be obtained.

[0069] In the above-described embodiment, it is preferably set that the straight line connecting the center of the light irradiation unit and the intersection point is inclined with respect to the optical axis of the imaging lens by 2 degrees or more and 90 degrees or less. By setting it in this way, the specular reflection light from the object on the planar object generated by the light from the light irradiation unit can be made to enter the imaging device more efficiently, and the ratio of the intensity of the specular reflection light incident from the object to the intensity of the diffused light incident from the object can be further increased. As a result, image data capable of efficiently detecting an object having the property of reflecting light on a planar object can be obtained.

[0070] In addition, in the above-described embodiment, it is preferable that the light irradiation device has a point light source. In this case, the intensity of the specular reflection light incident from the object can be made sufficiently greater than the intensity of the diffused light incident from the object with a simple structure. As a result, image data capable of efficiently detecting an object having the property of reflecting light on the object can be obtained with a simple structure.

[0071] Furthermore, in the above-described embodiment, it is preferable that the light irradiation device has a light irradiation unit in which a plurality of point light sources are arranged. In this way, image data capable of efficiently detecting an object having the property of reflecting light in a wide range of the object can be obtained.

[0072] In addition, in the above-described embodiment, it is preferable that the light irradiation device has a light scanning unit that scans light on the object. In this way, it is possible to obtain image data capable of efficiently detecting an object having the property of reflected light over a wide range of the object.

[0073] In addition, in the above-described embodiment, it is preferable that the light irradiation device has a component that limits the light irradiation range to the range of the light irradiation unit. In this case, it is possible to set the range of the light irradiation unit with a simple structure, and it is possible to obtain image data capable of efficiently detecting an object having the property of reflected light on the object with a simple structure.

[0074] The image acquisition device of the embodiment is [1] "An image acquisition device, comprising: a light irradiation device that irradiates light on an object from the range of a light irradiation unit; and an imaging device that detects the light that has been specularly reflected by the object via an imaging lens, and a straight line connecting the center of the light irradiation unit and the intersection of the optical axis and the object is set to be inclined at 2 degrees or more and 120 degrees or less with respect to the optical axis of the imaging lens, and the solid angle of the light irradiation unit observed from the intersection is set to be 0 steradians or more and 0.15 steradians or less".

[0075] The image acquisition device of the embodiment may also be [2] "The image acquisition device according to [1] above, wherein the straight line connecting the center of the light irradiation unit and the intersection is set to be inclined at 2 degrees or more and 90 degrees or less with respect to the optical axis of the imaging lens".

[0076] The image acquisition device of the embodiment may also be [3] "The image acquisition device according to [1] or [2] above, wherein the light irradiation device has a point light source".

[0077] The image acquisition device of the embodiment may also be [4] "The image acquisition device according to [3] above, wherein the light irradiation device has a light irradiation unit in which a plurality of point light sources are arranged".

[0078] The image acquisition device of the embodiment may also be [5] "The image acquisition device according to any one of [1] to [4] above, wherein the light irradiation device has a light scanning unit that scans light on the object".

[0079] The image acquisition device of the embodiment may also be [6] "The image acquisition device according to any one of [1] to [5] above, wherein the light irradiation device has a component that limits the light irradiation range to the range of the light irradiation unit".

[0080] The inspection device of the embodiment is [7] "An inspection device, comprising: the image acquisition device according to any one of [1] to [6] above; a conveying device that conveys the object in a predetermined direction; and an inspection processing unit that inspects the object based on the data output from the image acquisition device".

[0081] The image acquisition method of the embodiment is [8] "An image acquisition method, comprising: a light irradiation step of irradiating an object with light from the range of a light irradiation unit using a light irradiation device; and an imaging step of detecting the light that has been specularly reflected by the object using an imaging device via an imaging lens, setting a straight line connecting the center of the light irradiation unit and the intersection point of the optical axis and the object to be inclined at 2 degrees or more and 120 degrees or less with respect to the optical axis of the imaging lens, and setting the solid angle of the light irradiation unit observed from the intersection point to be 0 steradians or more and 0.15 steradians or less".

[0082] Explanation of symbols

[0083] 1, 1A, 1B, 1C... Image acquisition device, 2, 102, 202, 302... Lighting device (light irradiation device), 2a, 103, 203... Light irradiation unit, 303... Light scanning unit (light irradiation unit), 104... Light emitting element (point light source), 7... Imaging device, 7a... Imaging lens, 11... Conveyor device, 12... Computer (inspection processing unit), 100... Inspection system (inspection device), A1... Optical axis, A2... Straight line, C1... Center, P1... Intersection point, θ... Angle, S... Object, FS... Foreign matter.

Claims

1. An image acquisition device, characterized in that: It includes: A light irradiation device that irradiates light from the range of the light irradiation unit to the object; and An imaging device that detects the light after being directly reflected by the object through an imaging lens, The straight line connecting the center of the light irradiation unit and the intersection of the optical axis and the object is set to be inclined at an angle of 2 degrees or more and 120 degrees or less with respect to the optical axis of the imaging lens, The solid angle of the light irradiation unit observed from the intersection is set to be 0 steradians or more and 0.15 steradians or less.

2. The image acquisition device according to claim 1, characterized in that: The straight line connecting the center of the light irradiation unit and the intersection is set to be inclined at an angle of 2 degrees or more and 90 degrees or less with respect to the optical axis of the imaging lens.

3. The image acquisition device according to claim 1 or 2, characterized in that: The light irradiation device has a point light source.

4. The image acquisition device according to claim 3, characterized in that: The light irradiation device has a light irradiation unit provided with a plurality of point light sources.

5. The image acquisition device according to any one of claims 1 to 4, characterized in that: The light irradiation device has a light scanning unit that scans the light on the object.

6. The image acquisition device according to any one of claims 1 to 5, characterized in that: The light irradiation device has a component that limits the irradiation range of the light to the range of the light irradiation unit.

7. An inspection device, characterized in that: It includes: The image acquisition device according to any one of claims 1 to 6; A conveying device that conveys the object in a specified direction; and An inspection processing unit that inspects the object based on the data output from the image acquisition device.

8. An image acquisition method, characterized in that: It includes: A light irradiation step of irradiating light from the range of the light irradiation unit to the object using a light irradiation device; and An imaging step of detecting the light after being directly reflected by the object through an imaging lens using an imaging device, The straight line connecting the center of the light irradiation unit and the intersection of the optical axis and the object is set to be inclined at an angle of 2 degrees or more and 120 degrees or less with respect to the optical axis of the imaging lens, The solid angle of the light irradiation unit observed from the intersection is set to be 0 steradians or more and 0.15 steradians or less.

9. The image acquisition method according to claim 8, characterized in that: The straight line connecting the center of the light irradiation unit and the intersection is set to be inclined at an angle of 2 degrees or more and 90 degrees or less with respect to the optical axis of the imaging lens.

10. The image acquisition method according to claim 8 or 9, characterized in that: The light irradiation device has a point light source.

11. The image acquisition method according to claim 10, characterized in that: The light irradiation device has a light irradiation unit provided with a plurality of point light sources.

12. The image acquisition method according to any one of claims 8 to 11, characterized in that: The light irradiation device has a light scanning unit that scans the light on the object.

13. The image acquisition method according to any one of claims 8 to 12, characterized in that: The light irradiation device has a component that limits the irradiation range of the light to the range of the light irradiation unit.

Images