Image acquisition device, inspection device, and image acquisition method

Abstract

An image acquisition device 1 comprises: an illumination device 2 that irradiates a subject S with light from the range of a light irradiation unit 2a; and an imaging device 7 that detects, through an imaging lens 7a, light that has been specularly reflected by the subject S. A straight line that connects the center of the light irradiation unit 2a with a point of intersection between the optical axis of the imaging lens 7a and the subject S is set to be inclined 2-120 degrees with respect to the optical axis. The solid angle of the light irradiation unit 2a as viewed from said point of intersection is set to be 0-0.15 steradians.

Description

Image acquisition device, inspection device, and image acquisition method

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

[0002] Conventionally, there have been known devices that inspect an object by detecting light irradiated onto the object. For example, a device described in Patent Document 1 below uses an imaging unit to detect transmitted light that has passed through the object and reflected light that has been reflected from the object, and inspects the object based on detection data output from the imaging unit.

[0003] Japanese Patent Application Laid-Open No. 2021-189071

[0004] The detection data acquired by the above-described conventional devices tends to make it difficult to detect objects that reflect light on the inspection object. Therefore, it is required to acquire data that can efficiently detect objects that reflect light on the inspection object.

[0005] Therefore, one aspect of the embodiment has been made in consideration of such problems, and aims to provide an image acquisition device, an inspection device, and an image acquisition method that are capable of acquiring image data that can efficiently detect objects on a target object that have the property of reflecting light.

[0006] An image acquisition device according to a first aspect of the embodiment includes a light irradiation device that irradiates light onto an object from within the range of a light irradiation unit, and an imaging device that detects light that is specularly reflected by the object via an imaging lens, wherein a straight line connecting the center of the light irradiation unit and the intersection point between 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, and the solid angle of the light irradiation unit as seen from the intersection point is set to be 0 steradians or more and 0.15 steradians or less.

[0007] Alternatively, an image acquisition method according to a second aspect of the embodiment includes a light irradiation step of irradiating light onto an object from the range of a light irradiation unit using a light irradiation device, and an imaging step of detecting light that is specularly reflected by the object via an imaging lens using an imaging device, wherein a straight line connecting the center of the light irradiation unit and the intersection point between 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, and the solid angle of the light irradiation unit as seen from the intersection point is set to be 0 steradians or more and 0.15 steradians or less.

[0008] According to the first or second aspect, when an object having a light-reflecting property is present on the target, specularly reflected light from the object can be efficiently incident on the imaging device via the imaging lens, while the intensity of the specularly reflected light incident from the object can be made sufficiently greater than the intensity of the diffused light incident from the target. In particular, by setting the solid angle of the light irradiation unit as viewed from the intersection of the optical axis of the imaging lens and the target to be between 0 and 0.15 steradians, the ratio between the intensity of the specularly reflected light and the intensity of the diffused light can be increased nonlinearly. As a result, image data that can efficiently detect the light-reflecting object on the target can be obtained.

[0009] Alternatively, an inspection device according to a third aspect of the embodiment includes an image acquisition device according to the first aspect, a conveying device that conveys an object in a predetermined direction, and an inspection processing unit that inspects the object based on data output from the image acquisition device.

[0010] According to the third aspect, it is possible to efficiently detect objects that have the property of reflecting light on a plurality of objects while transporting the plurality of objects.

[0011] According to any one of the aspects of the present invention, it is possible to acquire image data that can efficiently detect an object on a target object that has the property of reflecting light.

[0012] 1 is a schematic configuration diagram of an image acquisition device 1 according to an embodiment. FIG. 2 is a diagram showing an image of reflected light generated at an object S when the image acquisition device 1 of FIG. 1 is used. FIG. 3 is a diagram showing the arrangement of an illumination device 2 relative to an imaging device 7 in the image acquisition device 1, and the light emission range of the illumination device 2. FIG. 4 is a graph showing the relationship between a solid angle ω in the image acquisition device 1 and a signal ratio representing detection accuracy. FIG. 5 is a graph showing the relationship between a solid angle ω in the image acquisition device 1 and a signal ratio representing detection accuracy. FIG. 6 is a schematic configuration diagram of an inspection system 100 according to an embodiment. FIG. 7 is a flowchart showing the procedure of an inspection method for an object S using the inspection system 100. FIG. 8 is a schematic configuration diagram of an image acquisition device 1A according to a modified example. FIG. 9 is a schematic configuration diagram of an image acquisition device 1B according to a modified example. FIG. 10 is a schematic configuration diagram of an image acquisition device 1C according to a modified example. FIG. 11 is a diagram showing image data acquired by an image acquisition device according to a comparative example.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0014] 1 is a schematic diagram of an image acquisition device 1 according to an embodiment. The image acquisition device 1 is a device that acquires image data of an object, such as food, for the purpose of inspecting the object for the presence or absence of foreign matter. However, the object to be inspected by the image acquisition device 1 may be other items such as electronic components in addition to food, such as beef, pork, chicken, lamb, and processed foods.

[0015] The image acquisition device 1 includes an illumination device (light irradiation device) 2, an imaging device 7, and an image processing device 8. Each component of the image acquisition device 1 will be described in detail below.

[0016] The lighting device 2 is composed of a light irradiation unit 2a that irradiates light and a main body 2b that has a built-in lighting circuit for lighting the light-emitting elements in the light irradiation unit 2a, and irradiates the light in a diffused manner toward the target S. Examples of light-emitting elements built into the light irradiation unit 2a include an LED, an SLD (Superluminescent Diode), a laser, and a halogen lamp. The light irradiation unit 2a has one or more built-in light-emitting elements that are point light sources, and is configured to be able to irradiate light in a diffused manner from the point-like light-emitting range of the light irradiation unit 2a via a lens, a diffuser, or the like. The shape of the light-emitting range of the light irradiation unit 2a may be flat or may be curved, such as spherical.

[0017] The imaging device 7 is disposed at a position where it can detect reflected light generated when light emitted from the lighting device 2 is specularly reflected by the object S, and is a device that detects a two-dimensional image of 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. When the object S is transported in a predetermined direction by a transport device, a line sensor camera or a TDI (Time Delay Integration) sensor camera may also be used as the imaging device 7.

[0018] The imaging device 7 includes an imaging lens 7a. The imaging lens 7a forms a two-dimensional image of light including reflected light from the object S on a light receiving surface (not shown) of an imaging element inside the imaging device 7. The imaging device 7 detects the light including reflected light from the object S via the imaging lens.

[0019] The image processing device 8 is a device that detects foreign matter on the target object S by receiving image data acquired by the imaging device 7. The image processing device 8 is physically an arithmetic device (such as a computer) that incorporates a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), a recording medium such as a RAM (Random Access Memory) or a ROM (Read Only Memory), a communication module, and an input / output module. The image processing device 8 may also be configured with an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The image processing device 8 may acquire image data from the imaging device 7 via a cable, or may acquire image data from the imaging device 7 via wireless communication.

[0020] Here, a mechanism for detecting reflected light from the object S in the image acquisition device 1 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an image of reflected light occurring at the object S when the image acquisition device 1 is used.

[0021] Each light ray L0 of the light diffused and irradiated by the lighting device 2 reaches a wide area on the surface of the object S. The object S, such as food, has the property of producing specularly reflected light L1 and diffusely reflected light L2 when light is incident on it. Furthermore, if a foreign object FS, such as a plastic film, which is an object that has the property of transmitting light, is present on the surface of the object S, the light ray L0 incident on the foreign object FS produces specularly reflected light L3 that is specularly reflected by the surface of the foreign object FS, specularly reflected light L4 that passes through the foreign object FS and then specularly reflected by the rear surface of the foreign object FS, and diffusely reflected light L5 that is diffusely reflected by the foreign object FS. In this case, the specularly reflected light L3 and L4 have a relatively higher intensity than the specularly reflected light L1, and because the foreign object FS has the property of transmitting light, their intensity is also relatively higher than the diffusely reflected light L5.

[0022] The image processing device 8 of the image acquisition device 1 acquires and stores image data of the object S from the imaging device 7 in order to two-dimensionally detect the reflectance of the light reflected from the object S by utilizing the above-mentioned properties of reflected light. Based on the image data stored in the image processing device 8, the luminance distribution of the image data is analyzed to search for areas where the intensity of the specularly reflected light is relatively high, thereby making it possible to inspect for the presence or absence of a foreign substance FS.

[0023] Next, the configuration of the illumination device 2 and the imaging device 7 in the image acquisition device 1 will be described in detail with reference to Fig. 3. Fig. 3 is a diagram showing the arrangement of the illumination device 2 relative to the imaging device 7 and the light emission range of the illumination device 2 in the image acquisition device 1.

[0024] When inspecting the object S, the imaging device 7 has an optical axis A of the imaging lens 7a. １ The illumination device 2 is disposed at a position and in a direction such that the light emitting range R of the light emitting unit 2 a intersects with the object S. １ Regarding the optical axis A １ and the intersection point P of the object S １ The solid angle ω seen from the optical axis A is within a predetermined range. １ For the light emitting range R １ Center C １ and intersection point P １ Line A connecting ２ is set to be inclined at an angle θ within a predetermined angle range. Here, the solid angle ω is １ Light emission range R as seen from １ The intersection point P １ The light emission range R １ The part R that a half-line passing through the inside cuts out on the sphere of radius 1 ２ Specifically, in the image acquisition device 1 of this embodiment, the light emission range R １ The solid angle ω is set to be equal to or greater than 0 sr (steradian) and equal to or less than 0.15 sr, and the optical axis A １ Line A for ２ The angle θ is set to be equal to or greater than 2 degrees and equal to or less than 120 degrees.

[0025] The following describes experimental results regarding the detection accuracy of the image acquisition device 1 having the above configuration. In the experiment, the target object S on which a foreign object FS with a known position was placed was used, and the detection accuracy was evaluated while changing the reflectance of the foreign object FS, the solid angle ω, and the parameters of the imaging lens 7a.

[0026] FIG. 4 is a graph showing the relationship between the solid angle ω and the signal ratio, which indicates detection accuracy, when an experiment was conducted with the solid angle ω set to a relatively small value and the F-number of the imaging lens 7a varied between 1.6, 2, 4, and 8. The signal ratio is calculated by dividing the maximum luminance at the position of the foreign object FS by the average luminance at the positions of the surrounding objects, and indicates the level of detection accuracy for the foreign object FS. The experimental results show that, for all F-numbers, the signal ratio increases as the solid angle ω decreases from 0.004 sr to 0 sr. Furthermore, within the range of solid angle ω of 0.002 sr or less, the signal ratio increases with increasing F-number. However, once the solid angle ω exceeds 0.002 sr, the change in the signal ratio with respect to the solid angle ω remains almost constant even when the F-number is changed. This means that the detection accuracy is not dependent on the observation conditions of the imaging device 7 when the solid angle ω exceeds 0.002 sr.

[0027] Here, the signal ratio for the image data acquired by the image acquisition device 1 is estimated by calculation using a theoretical model. The object-side solid angle of the imaging lens 7a calculated from the F-number and magnification of the imaging lens 7a is assumed to be Cam_sr[sr], and the light-emitting range R of the illumination device 2 is assumed to be １ Assume that the solid angle of the foreign substance FS is LS_sr[sr], and the reflectance of the foreign substance FS is Rs. The intensity of the specularly reflected light from the foreign substance 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 target S around the foreign substance 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: SNr = 2π × Rs / LS_sr + 1.

[0028] Figure 5 is a graph showing the relationship between the solid angle ω and the signal ratio, which represents detection accuracy, calculated using the theoretical model with the reflectivity of the foreign matter FS set between 2% and 10% and the solid angle ω varied between 0 sr and 0.4 sr. The calculation results show that, for all reflectivities, the signal ratio increases as the solid angle ω decreases, and the overall signal ratio characteristics shift toward a higher signal ratio when the reflectivity is set higher. In particular, when the solid angle ω exceeds approximately 0.15 sr, the signal ratio changes linearly with the solid angle ω. However, when the solid angle ω is between 0 sr and approximately 0.15 sr, the signal ratio changes nonlinearly with the solid angle ω, with the rate of increase in the signal ratio significantly increasing with decreasing solid angle ω. In other words, the signal ratio SNr is determined solely by the reflectivity Rs and the solid angle LS_sr, which closely matches the measurement results of the signal ratio characteristics shown in Figure 4. Taking into consideration such characteristics of detection accuracy, the solid angle ω is set to a range of 0 sr to approximately 0.15 sr in the image acquisition device 1 of this embodiment. With this setting, the image of the foreign matter FS can be clearly seen in the image data acquired by the image acquisition device 1.

[0029] Next, a description will be given of the configuration of an inspection system 100, which is an inspection apparatus according to an embodiment. Fig. 6 shows a schematic configuration of the inspection system 100 according to an embodiment.

[0030] The inspection system 100 includes the image acquisition device 1 having the above-described configuration, a conveying device 11 such as a belt conveyor that conveys the object S in a predetermined direction, and a computer (inspection processing unit) 12 that calculates image data output from the image acquisition device 1. The image acquisition device 1 acquires image data of the object S conveyed by the conveying device 11 and outputs the acquired image data to the computer 12. The inspection system 100 may be controlled so that the image acquisition device 1 captures an image of the object S while the object S is being conveyed by the conveying device 11, thereby acquiring the image data. The inspection system 100 may also be controlled so that the image acquisition device 1 captures an image of the object S while the conveying device 11 stops conveying the object S, thereby acquiring the image data. When imaging the object S while it is being conveyed, it is preferable to use a line sensor as the imaging device 7. When imaging the object S while it is being conveyed, it is preferable to use an area sensor as the imaging device 7. When imaging the object S while it is being conveyed, it is also possible to use an area sensor as the imaging device 7 while the lighting device 2 is intermittently turned on.

[0031] The computer 12 has the same hardware configuration as the image processing device 8. That is, the computer 12 is physically an arithmetic device incorporating a CPU or GPU as a processor, RAM or ROM as a recording medium, a communication module, an input / output module, etc. The computer 12 may acquire image data from the image processing device 8 via a cable, or may acquire image data from the image processing device 8 via wireless communication.

[0032] Functionally, the computer 12 executes an inspection process for the object S based on image data. That is, the computer 12 refers to multiple image data obtained for the object S, identifies a brightness difference, and determines the range of a foreign substance FS in the object S based on the identified brightness difference. The computer 12 then outputs an inspection result image indicating the range of a foreign substance FS determined for one object S to an output device such as a display. The computer 12 may also output the inspection result image to an external device via a network, a recording medium, etc.

[0033] Next, a method for inspecting the object S using the inspection system 100 will be described, and an image acquisition method according to this embodiment will be described in detail. Fig. 7 is a flowchart showing the steps of the method for inspecting the object S.

[0034] First, when the inspection process of the object S is started, the conveyance device 11 starts conveying the object S (step S1). After that, when the object S is conveyed by the conveyance device 11 into the light irradiation range of the lighting device 2, the lighting device 2 irradiates the object S with light (step S2).

[0035] In response, reflected light generated on the surface of the object S is incident on the imaging device 7 through the imaging lens 7a, and the imaging device 7 detects a two-dimensional image of the reflected light, thereby outputting image data (S3).

[0036] The image data acquired by the imaging device 7 is acquired and stored by the image processing device 8, and then output to the computer 12, where it is processed. That is, the computer 12 determines the range of the foreign substance FS on the object S based on the brightness of each pixel of the image data (step S4). Finally, the computer 12 outputs an inspection result image of the object S to an output device as an image in which the foreign substance FS present on the object S is detected (step S5), and the inspection process for the object S is completed.

[0037] The effects of this embodiment will be described.

[0038] According to the image acquisition device 1 of this embodiment, when a foreign object FS having a property of reflecting light is present on the object S, specularly reflected light from the foreign object FS can be efficiently incident on the image acquisition device 7 via the imaging lens 7a, and at the same time, the intensity of the specularly reflected light incident from the foreign object FS can be made sufficiently greater than the intensity of the diffused light incident from the object S. In particular, the optical axis A of the imaging lens 7a １ and the intersection point P of the object S １ The light emitting range R of the light emitting unit 2a as seen from １By setting the solid angle ω to be equal to or greater than 0 steradians and equal to or less than 0.15 steradians, the ratio between the intensity of the specularly reflected light and the intensity of the diffused light can be increased nonlinearly, and as a result, image data can be acquired that can efficiently detect foreign matter FS on the object S that has the property of reflecting light.

[0039] Furthermore, in the image acquisition device 1, the illumination device 2 has a point-like light emission range of the light irradiation unit 2a. In this case, with a simple configuration, the intensity of specularly reflected light incident from the foreign matter FS can be made sufficiently greater than the intensity of diffused light incident from the target S. As a result, with a simple configuration, image data can be acquired that can efficiently detect foreign matter FS that has the property of reflecting light on the target S. Furthermore, if the illumination device 2 is configured to have multiple light-emitting elements that are point light sources built into the light irradiation unit 2a, image data can be acquired that can efficiently detect foreign matter FS over a wide range of the target S.

[0040] Alternatively, the inspection system 100 according to this embodiment can efficiently detect foreign substances FS that have the property of reflecting light on a plurality of objects S while transporting the plurality of objects S.

[0041] Various embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and may be modified or applied to other things within the scope that does not change the gist of the claims.

[0042] The foreign matter FS to be inspected by the inspection system 100 of this embodiment includes a wide range of objects that have the property of reflecting light, including not only transparent objects such as plastic films but also colored translucent objects.

[0043] 8, an illumination device 102 having a linear light irradiation unit 103 may be used. In this illumination device 102, a plurality of light emitting elements 104, which are point light sources, are arranged along the elongated light emission range of the light irradiation unit 103. With this configuration, it is possible to acquire image data that can efficiently detect foreign matter FS, which has the property of reflecting light, over a wide range of the object S. Even in the case of such a configuration, the light emission range R１ The numerical range of the solid angle ω, the optical axis A １ Line A for ２ The range of the angle θ (FIG. 3) is set to the same range as in the above-described embodiment. In particular, when the image acquisition device 1A captures an image of the object S while it is being transported by the transport device 11, it is preferable to use the image acquisition device 1A in combination with the imaging device 7, which is a line sensor.

[0044] In addition, as in the image acquisition device 1B according to the modified example shown in FIG. 9, the optical axis A of the imaging lens 7a １ Alternatively, an illumination device 202 having a ring-shaped light emitting unit 203 arranged to surround the light emitting area R may be used. In this illumination device 202, a plurality of light emitting elements 104, which are point light sources, are arranged along the ring-shaped light emitting area R of the light emitting unit 203. Even in such a configuration, the light emitting area R １ The numerical range of the solid angle ω, the optical axis A １ Line A for ２ The range of the angle θ (FIG. 3) is set to the same range as in the above-described embodiment. In particular, the image acquisition device 1B is preferably used in combination with the imaging device 7, which is an area sensor, when capturing an image of the target object S while the transport of the target object S is stopped.

[0045] 10, the illumination device 302 may be configured to include a laser light source 304 and a light scanning unit 303 that scans the object S with light emitted from the laser light source 304. The light scanning unit 303 forms a light irradiation unit. For example, a movable mirror or the like is used as the light scanning unit 303. The image acquisition device 1C may have a configuration that allows the light irradiation direction of the laser light source 304 itself to be changed, instead of the light scanning unit 303. In this case, the imaging device 7 may be a laser scanning optical system that reconstructs an image based on a detection signal for each light scanning position. Even in such a configuration, the light emission range R １ The numerical range of the solid angle ω, the optical axis A １ Line A for ２The range of the angle θ (FIG. 2) is set to the same range as in the above-described embodiment. With this configuration, it is possible to acquire image data that can efficiently detect foreign matter FS that has the property of reflecting light over a wide range of the target object S.

[0046] Furthermore, the illumination devices 2, 102, 202, and 302 according to the above-described embodiment and modifications each have a light irradiation range of a light emitting range R of a light emitting unit. １ The light source S may include a combination of various optical members such as slits as a member for limiting the light irradiation angle, and in this case, the range of the light irradiation unit can be set with a simple configuration, and image data that can efficiently detect foreign matter FS on the target object S that has the property of reflecting light can be obtained with a simple configuration.

[0047] Furthermore, the lighting devices 2, 102, and 202 according to the above-described embodiment and each of the modifications have a light-emitting range R １ Although the light emitting elements are formed in a dotted, linear, or ring shape, they may be in any curved or rectangular shape. The light emitting elements may be arranged continuously or discretely. The lighting devices 2, 102, and 202 may be controlled so that the light emitting elements are simultaneously lit, partially lit, or sequentially lit.

[0048] 11 shows an example of image data acquired by the image acquisition device 1B according to the modified example. This image data is acquired when the diameter of the light emitting unit 203 of the illumination device 202 is set to 65 mm, the distance of the light emitting unit 203 from the target object S is set to 330 mm, and the light emission range R １ The solid angle ω of (0.015 steradians, optical axis A １ Line A for ２ The image data was acquired when the angle θ was set to 5.7 degrees. In this way, the image acquisition device 1B can acquire image data in which the foreign substance FS is highlighted more than the target object S.

[0049] 12 shows an example of image data acquired by an image acquisition device according to a comparative example. In this comparative example, the diameter of the light emitting unit 203 of the illumination device 202 is set to 65 mm, the distance of the light emitting unit 203 from the object S is set to 70 mm, and the light emission range R １ The solid angle ω is 0.29 steradians, and the optical axis A １ Line A for ２ The image data was acquired when the angle θ was set to 25 degrees. In the image data acquired in this modified example, there is no difference in brightness between the portion of the foreign substance FS and the portion of the target object S. As a result, it is difficult to detect the presence of the foreign substance FS from the image data.

[0050] In the image acquisition devices 1, 1A, 1B, and 1C described above, the optical axis A １ Line A for ２ The angle θ may be set to be equal to or greater than 2 degrees and equal to or less than 90 degrees. By setting the angle θ in this manner, when a planar object S is to be inspected, specular reflection light from a foreign substance FS on the object S, which is generated based on light from the light irradiation unit of the illumination device 2, 102, 202, 302, can be made incident on the imaging device 7 more efficiently, thereby further increasing the ratio of the intensity of specular reflection light incident from the foreign substance FS to the intensity of diffuse light incident from the object S. As a result, image data that can efficiently detect a foreign substance FS on the planar object S can be acquired.

[0051] In the above embodiment, it is preferable that the line connecting the center of the light emitting unit and the intersection point is inclined at an angle of 2 degrees to 90 degrees with respect to the optical axis of the imaging lens. This allows specular reflection light from an object on a planar target, which is generated based on light from the light emitting unit, to be more efficiently incident on the imaging device, further increasing the ratio of the intensity of specular reflection light incident from the object to the intensity of diffuse light incident from the object. As a result, image data that can efficiently detect an object on a planar target that has the property of reflecting light can be acquired.

[0052] In the above embodiment, it is also preferable that the light irradiation device has a point light source. In this case, the intensity of specularly reflected light incident from the object can be made sufficiently greater than the intensity of diffused light incident from the target object with a simple configuration. As a result, image data that can efficiently detect objects on the target object that have the property of reflecting light can be obtained with a simple configuration.

[0053] Furthermore, in the above embodiment, it is also preferable that the light irradiation device has a light irradiation unit in which a plurality of point light sources are arranged, thereby making it possible to acquire image data that can efficiently detect objects that have the property of reflecting light over a wide range of the target object.

[0054] Furthermore, in the above embodiment, it is also preferable that the light irradiation device has a light scanning unit that scans the object with light, thereby making it possible to acquire image data that can efficiently detect objects that have the property of reflecting light over a wide range of the object.

[0055] In the above embodiment, it is preferable that the light irradiation device has a member that limits the light irradiation range to the range of the light irradiation unit. In this case, the range of the light irradiation unit can be set with a simple configuration, and image data that can efficiently detect objects on the target that have the property of reflecting light can be obtained with a simple configuration.

[0056] The image acquisition device of the embodiment is [1] "an image acquisition device comprising a light irradiation device that irradiates light onto an object from the range of a light irradiation unit, and an imaging device that detects light that is specularly reflected by the object via an imaging lens, wherein a straight line connecting the center of the light irradiation unit and the intersection point between 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, and the solid angle of the light irradiation unit as seen from the intersection point is set to be 0 steradians or more and 0.15 steradians or less."

[0057] The image acquisition device of the embodiment may be [2] "the image acquisition device described in [1] above, in which the straight line connecting the center of the light irradiation unit and the intersection point 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."

[0058] The image acquisition device of the embodiment may be [3] "the image acquisition device according to the above [1] or [2], wherein the light irradiation device has a point light source."

[0059] The image acquisition device of the embodiment may be [4] "the image acquisition device according to the above [3], in which the light irradiation device has a light irradiation section in which a plurality of point light sources are arranged."

[0060] The image acquisition device of the embodiment may be [5] "the image acquisition device according to any one of [1] to [4] above, in which the light irradiation device has a light scanning unit that scans light onto the object."

[0061] The image acquisition device of the embodiment may be [6] "an image acquisition device according to any one of [1] to [5] above, in which the light irradiation device has a member that limits the light irradiation range to the range of the light irradiation unit."

[0062] The inspection device of the embodiment is [7] "an inspection device comprising an image acquisition device described in any one of [1] to [6] above, a conveying device that conveys an object in a predetermined direction, and an inspection processing unit that inspects the object based on data output from the image acquisition device."

[0063] The image acquisition method of the embodiment is [8] "an image acquisition method comprising a light irradiation step of irradiating light onto an object from the range of a light irradiation unit using a light irradiation device, and an imaging step of detecting light that is specularly reflected by the object via an imaging lens using an imaging device, wherein a straight line connecting the center of the light irradiation unit and the intersection point between 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, and the solid angle of the light irradiation unit as seen from the intersection point is set to be 0 steradians or more and 0.15 steradians or less."

[0064] 1, 1A, 1B, 1C... Image acquisition device, 2, 102, 202, 302... Illumination 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... Conveyance device, 12... Computer (inspection processing unit), 100... Inspection system (inspection device), A １ ...Optical axis, A ２ ...straight line, C １ ...Center, P１ ...intersection point, θ...angle, S...object, FS...foreign object.

Claims

1. A light irradiation device that irradiates light onto an object from within the range of a light irradiation unit; an imaging device that detects light that is specularly reflected by the object through an imaging lens; Equipped with a straight line connecting a center of the light irradiation unit and an intersection point between 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 an optical axis of the imaging lens, The solid angle of the light irradiation unit as viewed from the intersection point is set to 0 steradians or more and 0.15 steradians or less. Image acquisition device.

2. a straight line connecting the center of the light irradiation unit and the intersection point is inclined at an angle of 2 degrees or more and 90 degrees or less with respect to the optical axis of the imaging lens; The image acquisition device of claim 1 .

3. The light irradiation device has a point light source.

3. An image acquisition device according to claim 1 or 2.

4. The light irradiation device has a light irradiation unit in which a plurality of point light sources are arranged.

4. The image acquisition device of claim 3.

5. The light irradiation device has a light scanning unit that scans the object with the light.

3. An image acquisition device according to claim 1 or 2.

6. The light irradiation device has a member that limits the irradiation range of the light to the range of the light irradiation unit.

3. An image acquisition device according to claim 1 or 2.

7. An image acquisition device according to claim 1 or 2; A conveying device that conveys the object in a predetermined direction; an inspection processing unit that inspects the object based on data output from the image acquisition device; An inspection device comprising:

8. a light irradiation step of irradiating the object with light from a range of a light irradiation unit using a light irradiation device; an imaging step of detecting light specularly reflected by the object through an imaging lens using an imaging device; Equipped with a straight line connecting a center of the light irradiation unit and an intersection point between 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 an optical axis of the imaging lens, The solid angle of the light irradiation unit as viewed from the intersection point is set to 0 steradians or more and 0.15 steradians or less. Image acquisition method.

9. a straight line connecting the center of the light irradiation unit and the intersection point is inclined at an angle of 2 degrees or more and 90 degrees or less with respect to the optical axis of the imaging lens; The image acquisition method according to claim 8.

10. The light irradiation device has a point light source.

10. The image acquisition method according to claim 8 or 9.

11. The light irradiation device has a light irradiation unit in which a plurality of point light sources are arranged. The image acquisition method according to claim 10.

12. The light irradiation device has a light scanning unit that scans the object with the light.

10. The image acquisition method according to claim 8 or 9.

13. The light irradiation device has a member that limits the irradiation range of the light to the range of the light irradiation unit.

10. The image acquisition method according to claim 8 or 9.