Visual inspection device, robot system, and visual inspection method

Abstract

To suppress a change in lighting conditions in a visual inspection device capable of moving an imaging part and an illumination part as one unit.SOLUTION: A visual inspection device 20 includes an imaging part 21 for imaging an inspection object 102, and a first illumination part 22 and a second illumination part 23 for illuminating the inspection object 102. The imaging part 21, the first illumination part 22, and the second illumination part 23 are integrally configured to be movable. The first illumination part 22 and the second illumination part 23 are configured to be capable of changing an optical axis angle with respect to a photodetection surface 21a of the imaging part 21.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for performing visual inspection of an object to be inspected. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known an apparatus that has an imaging unit mounted on the tip of a robot arm and performs visual inspection of an object to be inspected based on images of the object to be inspected taken from various angles (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-313225 Summary of the Invention [Problem to be solved by the invention]

[0004] Some visual inspection devices are equipped with an illumination unit that illuminates the object to be inspected in addition to an imaging unit, and the imaging unit and illumination unit are configured to be movable as a single unit. For example, if the plane of the object to be inspected is scratched or dirty, the image captured will differ due to the fine three-dimensional appearance of the scratch, and if the dirt is stained, the appearance will often change depending on the imaging position due to light reflection or light absorption, etc., so changing the imaging angle and acquiring multiple images contributes to improving the inspection accuracy. However, when trying to image the object to be inspected at a different imaging angle with such an appearance inspection device, the incident angle of the illumination light on the object to be inspected will also change. As a result, there is a risk of the inspection accuracy decreasing due to changes in the illumination conditions, such as changing from bright field illumination to dark field illumination, changing the Brewster angle, and changing the color and reflection brightness of the pseudo-metallic part that has illumination angle dependency.

[0005] The present invention has been made in view of the above circumstances, and has an object to suppress changes in lighting conditions in a visual inspection apparatus in which an imaging section and a lighting section can be moved integrally. [Means for solving the problem]

[0006] In order to solve the above problems, an appearance inspection device according to an embodiment of the present invention includes an imaging unit that images an object to be inspected, and an illumination unit that illuminates the object to be inspected. The imaging unit and the illumination unit are configured to be movable together. The illumination unit is configured to change an optical axis angle with respect to a light receiving surface of the imaging unit.

[0007] Another aspect of the present invention is a robot system including a robot arm having the above-described appearance inspection device mounted thereon, and a control unit that controls the angle of the optical axis of the illumination unit and the operation of the robot arm.

[0008] Another aspect of the present invention is a visual inspection method comprising the steps of moving an imaging unit and an illumination unit together, changing an optical axis angle of the illumination unit with respect to a light receiving surface of the imaging unit in accordance with the movement, illuminating an object to be inspected with the illumination unit, and capturing an image of the object to be inspected with the imaging unit.

[0009] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, devices, systems, etc. are also valid aspects of the present invention. Effect of the Invention

[0010] According to the present invention, in a visual inspection apparatus in which the imaging section and the illumination section can be moved integrally, changes in illumination conditions can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating a robot system according to an embodiment. [Diagram 2] 2(a) and 2(b) are diagrams for explaining the configuration and operation of a visual inspection device according to a comparative example. [Diagram 3]3(a) and 3(b) are diagrams for explaining how differences in illumination conditions affect captured images. [Figure 4] 4(a) and 4(b) are diagrams for explaining how differences in illumination conditions affect captured images. [Diagram 5] 5(a) and 5(b) are diagrams for explaining the configuration and operation of the appearance inspection apparatus according to the embodiment. [Figure 6] 6(a) and 6(b) are diagrams for explaining images captured by the appearance inspection apparatus according to the embodiment when a small protrusion is present on the surface of an object to be inspected. [Figure 7] 4 is a flowchart showing a series of processes in the robot system according to the embodiment. [Figure 8] 8(a) and 8(b) are diagrams for explaining adjustment of the distance between the illumination unit and the object to be inspected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described below based on preferred embodiments with reference to the drawings. The following configurations are for illustrative purposes to help understand the present disclosure, and the scope of the present disclosure is defined only by the appended claims. The same or equivalent components and members shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the dimensions of the members in each drawing are enlarged or reduced as appropriate to facilitate understanding. In addition, some of the members that are not important for explaining the embodiments in each drawing are omitted.

[0013] Fig. 1 is a schematic diagram showing a robot system 100 according to an embodiment. This robot system 100 is a system for inspecting an object 102 to be inspected for appearance defects such as scratches including cracks on the surface, foreign matter, dirt, color difference, and distortion. As shown in Fig. 1, the robot system 100 includes a robot arm 10, an appearance inspection device 20 mounted on the tip of the robot arm 10, a control unit 30 that controls the robot arm 10 and the appearance inspection device 20, and an image processing unit 40 that processes images acquired by the appearance inspection device 20 and determines the presence or absence of defects.

[0014] The robot arm 10 is a multi-joint robot. The robot arm 10 includes a support base 11 fixed on a stand provided on a floor surface (not shown), a first link 12, a second link 14, a third link 16, and a fourth link 18. The support base 11 is configured to be rotatable around a vertical rotation axis. The first link 12 is connected to the support base 11 via a first joint 9, and configured to be movable relative to the support base 11. The second link 14 is connected to the first link 12 via a second joint 13, and configured to be movable relative to the first link 12. The third link 16 is connected to the second link 14 via a third joint 15, and configured to be movable relative to the second link 14. The fourth link 18 is connected to the third link 16 via a fourth joint 17, and configured to be movable relative to the third link 16. The number of links and the number of joints are not limited to these.

[0015] The appearance inspection device 20 is provided at the tip of the fourth link 18 of the robot arm 10. The appearance inspection device 20 includes an imaging unit 21 that images an object 102 to be inspected, a first illumination unit 22 and a second illumination unit 23 that illuminate the object 102 to be inspected, and a holding unit 24 that integrally holds the imaging unit 21, the first illumination unit 22, and the second illumination unit 23. The imaging unit 21, the first illumination unit 22, and the second illumination unit 23 can be moved integrally by driving the robot arm 10. The robot arm 10 is driven to move the appearance inspection device 20, and the object 102 to be inspected is imaged from various angles while illuminating the object 102 to be inspected by the first illumination unit 22 and the second illumination unit 23. A plurality of images captured by the appearance inspection device 20 are sent to an image processing unit 40. The image processing unit 40 judges the presence or absence of a defect or scores the defectiveness (non-defectiveness). The robot system 100 may be configured so that the image processing unit 40 recognizes the object to be inspected 102 and acquires its representative coordinates, and the control unit 30 specifies the position coordinates of the robot arm 10 .

[0016] Before describing the appearance inspection apparatus 20 according to the embodiment, a comparative example will be described. FIG. 2(a) and FIG. 2(b) are diagrams for explaining the configuration and operation of an appearance inspection apparatus 220 according to the comparative example. Here, it is assumed that a defect portion 104 exists on the surface 102a of the inspected object 102. The defect portion may be, for example, a scratch, a foreign body, dirt, or distortion. Alternatively, the inspected object 102 may be transparent or semi-transparent, and the optical characteristics (refractive index, surface roughness, etc.) of the surface boundary of the defect portion 104 may be different. Alternatively, the inspected object 102 may have a specular or reflective property, and the optical characteristics (including surface roughness that affects specular reflection, diffuse reflection, etc.) of the surface boundary of the defect portion 104 may be different.

[0017] The appearance inspection device 220 includes an imaging section 221, a first illumination section 222 and a second illumination section 223 provided on both sides of the imaging section 221, and a holder 224 that holds the imaging section 221, the first illumination section 222, and the second illumination section 223. The imaging section 221 may be connected to an optical system that forms an image on an image sensor such as a C-MOS sensor or a CCD. The first illumination section 222 and the second illumination section 223 may each be an LED light source to which a light-guiding optical member (e.g., a SELFOC (registered trademark) lens array, a cylindrical lens, a diffusion plate, etc.) is attached.

[0018] In the comparative example, the relative positional relationship between the imaging section 221, the first illumination section 222, and the second illumination section 223 is fixed. In other words, in the comparative example, the angle of the optical axis Ax1 of the first illumination section 222 with respect to the light receiving surface 221a of the imaging section 221 and the angle of the optical axis Ax1 of the first illumination section 222 with respect to the light receiving surface 221a of the imaging section 221 are fixed. The optical axis Ac of the imaging section 221 is perpendicular to the light receiving surface 221a of the imaging section 221. The optical axis Ax1 of the first illumination section 222 is perpendicular to the irradiation surface 222a of the first illumination section 222. The optical axis Ax2 of the second illumination section 223 is perpendicular to the irradiation surface 223a of the second illumination section 223.

[0019] 2(a), the appearance inspection device 220 is disposed so that the optical axis Ac of the imaging unit 221 is perpendicular to the surface 102a of the object 102 to be inspected. The first illumination unit 222 and the second illumination unit 223 obliquely illuminate the defective portion 104. That is, the optical axis Ax1 of the first illumination unit 222 and the optical axis Ax2 of the second illumination unit 223 are inclined with respect to the surface 102a of the object 102 to be inspected.

[0020] In Fig. 2(a), illumination light from the first illumination unit 222 and the second illumination unit 223 is indicated by solid arrows, and reflected light from the surface 102a of the object 102 to be inspected that has received the illumination light is indicated by dashed arrows. Most of the illumination light from the first illumination unit 222 and the second illumination unit 223 is specularly reflected from the surface 102a of the object 102 to be inspected. Meanwhile, illumination light that has entered the defect 104 is diffusely reflected (including the case where the light penetrates into the object and is scattered) from the defect 104, and a part of the diffusely reflected light is incident on the light receiving surface 221a of the imaging unit 221. In Fig. 2(a), the diffusely reflected light that is incident on the light receiving surface 221a of the imaging unit 221 is indicated by thick arrows.

[0021] Such illumination conditions are a dark field illumination system because the light reflected specularly from the surface 102a does not reach the imaging unit 221, resulting in total darkness or reduced brightness (brightness). However, if the defect 104 emits diffuse light without specular reflection, the imaging unit 221 can capture that light and recognize an image of the defect 104. The defect 104 is equally irradiated from both the first illumination unit 222 and the second illumination unit 223. Therefore, as an epi-illumination dark field illumination system, this illumination balance is close to ideal. Incidentally, if the defect 104 has minute projections or other irregularities, the imaging unit 221 can be moved left and right relative to the drawing to grasp the ridges, discolored areas, and differences in reflection characteristics, thereby improving the inspection accuracy.

[0022] FIG. 2(b) shows a state in which the robot arm 10 (see FIG. 1) is driven to move the appearance inspection device 220 so that the optical axis Ac of the imaging unit 221 is inclined with respect to the surface 102a of the object 102 to be inspected. Since the first illumination unit 222 and the second illumination unit 223 also move together with the imaging unit 221, the angle of incidence of the illumination light with respect to the surface 102a of the object 102 to be inspected is also different from that in FIG. 2(a). Under the condition shown in FIG. 2(b), the left and right balance is poor, and the angle of incidence with respect to the object 102 to be inspected is also significantly different, and not only is the illumination contrast with respect to the object 102 to be inspected and the left and right balance with respect to the drawing different, but the illumination conditions with respect to the defective portion 104 are also different, which may cause a significant change in the captured image. For example, the ridge of a small protrusion, which should be visible due to the inclination of the imaging unit, may become dark, discolored, or difficult to see, and the difference in various illumination conditions may affect the captured image.

[0023] Hereinafter, the influence of differences in illumination conditions on captured images will be described with reference to Figures 3(a) and 3(b) and Figures 4(a) and 4(b). Here, it is assumed that a small protrusion 105 exists on the surface 102a of the object 102 to be inspected.

[0024] Fig. 3(a) shows a state in which the appearance inspection device 220 is disposed so that the optical axis Ac of the imaging unit 221 is perpendicular to the surface 102a of the inspected object 102. In Fig. 3(a), the first illumination unit 222, the holding unit 224, and the like are omitted for the sake of simplicity. As shown by the solid arrow in Fig. 3(a), illumination light is obliquely irradiated onto the surface 102a of the inspected object 102, including the small protrusions 105. The irradiated illumination light is reflected by the surface 102a and the small protrusions 105. Also, in Fig. 3(a), the diffuse reflected light that is diffusely reflected by the small protrusions 105 and enters the imaging unit 221 is shown by the thick arrow.

[0025] FIG. 3(b) is a schematic diagram of an image captured by the imaging unit 221 in the state shown in FIG. 3(a). Since the illumination system shown in FIG. 3(a) is a dark-field illumination system, the field of view 230 is dark and the image 232 of the small protrusion 105 is brightly captured. In the state shown in FIG. 3(a), the optical axis Ac of the imaging unit 221 is perpendicular to the surface 102a of the object 102 to be inspected, and the small protrusion 105 is illuminated evenly from both the left and right sides of the imaging unit 221. Therefore, as shown in FIG. 3(b), the image 232 of the small protrusion 105 is captured in a planar manner, and it is difficult to observe the ridge of the small protrusion 105. In other words, it is difficult to observe a three-dimensional foreign object in the optical system shown in FIG. 3(a).

[0026] When a three-dimensional object is to be visualized, the imaging unit 221 is usually tilted. FIG. 4(a) shows a state in which the appearance inspection device 220 is moved so that the optical axis Ac of the imaging unit 221 is inclined with respect to the surface 102a of the object 102 to be inspected. FIG. 4(b) is a schematic diagram of an image captured by the imaging unit 221 in the state shown in FIG. 4(a). Since the illumination unit also moves together with the imaging unit 221, the angle of incidence of the illumination light on the small protrusion 105 is also different from that in the state shown in FIG. 3(a). For example, as shown in FIG. 4(a), when the illumination light is reflected by the slope of the small protrusion 105 and returns directly to the first illumination unit 22, as shown in the image 234 in FIG. 4(b), the image of the slope on one side of the small protrusion 105 becomes completely dark, and only about half of the small protrusion 105 can be visualized.

[0027] Next, the appearance inspection device 20 according to the present embodiment will be described. Figures 5(a) and 5(b) are diagrams for explaining the configuration and operation of the appearance inspection device 20 according to the present embodiment. The appearance inspection device 20 according to the present embodiment differs from the appearance inspection device 220 according to the comparative example in that the optical axis angles of the first illumination unit 22 and the second illumination unit 23 with respect to the light receiving surface 21a of the imaging unit 21 can be changed according to the angle at which the inspected object 102 is imaged.

[0028] 5(a) and 5(b), it is also assumed here that a defect 104 exists on the surface 102a of the inspection object 102. The defect may be, for example, a scratch, a foreign object, a stain, a distortion, or the like.

[0029] The appearance inspection device 20 includes an imaging unit 21, a first illumination unit 22 and a second illumination unit 23 provided on both sides of the imaging unit 21, and a holding unit 24 that holds the imaging unit 21, the first illumination unit 22, and the second illumination unit 23. The imaging unit 21 may be an optical system that forms an image on an image sensor such as a C-MOS sensor or a CCD. The first illumination unit 22 and the second illumination unit 23 may each be an LED light source to which a light-guiding optical member (e.g., a SELFOC (registered trademark) lens array, a cylindrical lens, a diffusion plate, etc.) is attached. In this embodiment, illumination units are arranged on two sides of the imaging unit 21, but illumination units may be arranged on four sides around the imaging unit 21.

[0030] The appearance inspection device 20 according to this embodiment further includes a first moving mechanism 25 configured to be able to move the first illumination unit 22, and a second moving mechanism 26 configured to be able to move the second illumination unit 23. The first moving mechanism 25 is configured to be able to change the optical axis Ax1 of the first illumination unit 22 relative to the light receiving surface 21a of the imaging unit 21. The second moving mechanism 26 is configured to be able to change the optical axis Ax2 of the second illumination unit 23 relative to the light receiving surface 21a of the imaging unit 21. The first moving mechanism 25 and the second moving mechanism 26 can be configured by combining a power source such as a motor and a mechanical element such as an arc-shaped rack and pinion. The operations of the first moving mechanism 25 and the second moving mechanism 26 are controlled by the control unit 30 (see FIG. 1).

[0031] 5(a), the appearance inspection device 20 is disposed so that the optical axis Ac of the imaging unit 21 is perpendicular to the surface 102a of the inspected object 102. The first illumination unit 22 and the second illumination unit 23 are disposed so as to illuminate the defective portion 104 obliquely.

[0032] In Fig. 5(a), illumination light from the first illumination unit 22 and the second illumination unit 23 is illustrated by solid arrows, and reflected light from the surface 102a of the object 102 to be inspected that has received the illumination light is illustrated by dashed arrows. As shown in Fig. 5(a), most of the illumination light from the first illumination unit 22 and the second illumination unit 23 is specularly reflected from the surface 102a of the object 102 to be inspected. Meanwhile, illumination light that has entered the defect 104 is diffusely reflected (including the case where the light penetrates into the object and is scattered) from the defect 104, and a part of the diffusely reflected light is incident on the light receiving surface 21a of the imaging unit 21. In Fig. 5(a), the diffusely reflected light that is incident on the light receiving surface 21a of the imaging unit 221 is illustrated by thick arrows.

[0033] Fig. 5(b) shows a state in which the robot arm 10 (see Fig. 1) is driven to move the appearance inspection device 20 so that the optical axis Ac of the imaging unit 21 is inclined with respect to the surface 102a of the inspected object 102. In the appearance inspection device 20 according to this embodiment, the first illumination unit 22 and the second illumination unit 23 also move integrally with the imaging unit 21, and therefore the positions of the first illumination unit 22 and the second illumination unit 23 are displaced from the state shown in Fig. 5(a).

[0034] In the appearance inspection device 20 according to the present embodiment, when the appearance inspection device 20 is moved, the optical axis angles of the first illumination unit 22 and the second illumination unit 23 can be individually adjusted using the first movement mechanism 25 and the second movement mechanism 26 so that the diffuse reflected light from the inspection object 102 is appropriately incident on the light receiving surface 21a of the imaging unit 21. In FIG. 5(b), the first illumination unit 22' before being moved by the first movement mechanism 25 and the second illumination unit 23' before being moved by the second movement mechanism 26 are illustrated by dashed lines. According to the appearance inspection device 20 according to the present embodiment, the optical axis angles of the first illumination unit 22 and the second illumination unit 23 are adjusted so that the change in the angle of incidence on the inspection object 102 before and after the movement of the appearance inspection device 20 falls within a predetermined range, thereby preventing the illumination conditions from changing significantly. The predetermined range may be, for example, ±10°, or, for example, ±15°, or, for example, ±20°.

[0035] The illumination shown in FIG. 5(b) does not vary so much in terms of the angle of incidence of the inspection object 102 to the inspection object 102 compared to the illumination shown in FIG. 5(a). The balance of the illumination to the defective portion 104 is also close to that shown in FIG. 5(a), and is significantly improved compared to the illumination of FIG. 2(b). Thus, according to the appearance inspection device 20 according to this embodiment, the optical axis angles of the first illumination unit 22 and the second illumination unit 23 can be adjusted individually, so that even if the first illumination unit 22 and the second illumination unit 23 and the imaging unit 21 are moved together, the change in the illumination conditions can be suppressed. Since it is possible to image the inspection object 102 at different imaging angles while illuminating the inspection object 102 under substantially the same illumination conditions, the inspection accuracy of the defect portion 104 can be improved.

[0036] In addition, non-coherent light other than laser light does not become parallel light and diverges. In order to achieve a higher inspection accuracy more precisely, a mechanism for adjusting the working distance between the first illumination unit 22 and the second illumination unit 23 and the defective portion 104 may be further provided. In this case, such a mechanism can be easily realized by providing a one-axis fine movement actuator in each of the first illumination unit 22 and the second illumination unit 23.

[0037] 6(a) and 6(b) are diagrams for explaining an image captured by the appearance inspection apparatus 20 according to this embodiment when a small protrusion 105 is present on the surface 102a of the inspected object 102. Note that, in FIG. 6(a), the first illumination unit 22, the holder 24, and the like are omitted from illustration, as in FIG. 3(a) and FIG. 4(a).

[0038] Fig. 6(a) shows a state in which the appearance inspection device 20 is moved so that the optical axis Ac of the imaging unit 21 is inclined with respect to the surface 102a of the object to be inspected 102 (see Fig. 3(a) for the state before the appearance inspection device 20 is moved). In the state shown in Fig. 6(a), the illumination angle of the second illumination unit 23 is adjusted, and the change in the angle of incidence to the object to be inspected 102 is within a predetermined range (about 10° in this case) compared to the state shown in Fig. 3(a).

[0039] Fig. 6(b) is a schematic diagram of an image captured by the imaging unit 21 in the state shown in Fig. 6(a). The illumination conditions in the state shown in Fig. 6(a) have not changed significantly from the illumination conditions shown in Fig. 3(a) due to the adjustment of the optical axis angle of the second illumination unit 23. Therefore, the imaging angle of the imaging unit 21 can be tilted without significantly changing the illumination conditions. By tilting the imaging angle, it becomes possible to visualize the ridge of the small protrusion 105, which was difficult when the imaging angle was perpendicular to the object 102 to be inspected, as shown in Fig. 6(b).

[0040] 1, the angles of the optical axis Ax1 of the first illumination unit 22 and the optical axis Ax2 of the second illumination unit 23 relative to the light receiving surface 21a are controlled by the control unit 30. When the robot arm 10 is controlled to change the imaging angle relative to the inspected object 102, how the angles of the optical axis Ax1 of the first illumination unit 22 and the optical axis Ax2 of the second illumination unit 23 should be changed to suppress changes in the illumination conditions can be appropriately found by simulation or experiment.

[0041] In an embodiment, the angle of the optical axis Ax1 of the first illumination unit 22 and the optical axis Ax2 of the second illumination unit 23 is controlled in a direction that minimizes the change in angle of the reflected light from the inspection object 102 that is input to the light receiving surface 21a of the imaging unit 21. By controlling in this manner, it is possible to suppress the change in the illumination conditions.

[0042] In the above embodiment, the angles of the optical axis Ax1 of the first illumination unit 22 and the optical axis Ax2 of the second illumination unit 23 are changed, but in addition to this, the illumination light amount may be changed according to the change of the optical axis Ax1 and the optical axis Ax2. The illumination light amount may be, for example, an integrated light amount or a maximum illuminance. By changing the illumination light amount according to the change of the optical axis, the change of the illumination condition can be further suppressed.

[0043] In an embodiment, the angle between the optical axis Ax1 of the first illumination unit 22 and the optical axis Ax2 of the second illumination unit 23 may be controlled so that the amount of reflected light incident on the light receiving surface 21a of the imaging unit 21 is substantially constant. By controlling in this manner, it is possible to further suppress changes in the illumination conditions.

[0044] In a robot system as shown in Fig. 1, an inspection recipe for an object 102 to be inspected is created, and a control unit 30 controls a robot arm 10 according to the inspection recipe. When the control unit 30 creates the inspection recipe, the control unit 30 may automatically generate a control task for the robot arm 10 that moves the appearance inspection device 20, and a drive program for the first movement mechanism 25 and the second movement mechanism 26 that finely move the optical axis Ax1 of the first illumination unit 22 and the optical axis Ax2 of the second illumination unit 23. The control unit 30 can simultaneously control the first movement mechanism 25, the second movement mechanism 26, and the robot arm 10 so as to reduce changes in the optical axis Ax1 of the first illumination unit 22 and the optical axis Ax2 of the second illumination unit 23.

[0045] 7 is a flowchart showing a series of processes in the robot system 100 according to the embodiment. A series of processes in the robot system 100 will be described according to the flowchart shown in FIG.

[0046] Here, it is assumed that the appearance inspection device 20 at the tip of the robot system 100 is disposed so that the optical axis Ac of the imaging unit 21 is perpendicular to the surface of the inspected object 102. First, the control unit 30 drives the robot arm 10 to move the imaging unit 21, the first illumination unit 22, and the second illumination unit 23 together as a unit so that the optical axis Ac of the imaging unit 21 is inclined with respect to the surface of the inspected object 102 (S10).

[0047] Next, the control unit 30 drives the first movement mechanism 25 and the second movement mechanism 26 to change the optical axis angles of the first illumination unit 22 and the second illumination unit 23 with respect to the light receiving surface 21a of the imaging unit 21 in accordance with the movement in S10 (S12). For example, the optical axis angles of the first illumination unit 22 and the second illumination unit 23 are adjusted so that the change in the angle of incidence on the inspection object 102 before and after the movement in S10 falls within a predetermined range.

[0048] Next, the control unit 30 drives the robot arm 10 to adjust the distance between the first illumination unit 22, the second illumination unit 23, and the object 102 to be inspected (S14). FIG. 8(a) and FIG. 8(b) are diagrams for explaining the adjustment of the distance between the illumination unit and the object to be inspected. FIG. 8(a) shows a state in which the distance between the first illumination unit 22, the second illumination unit 23, and the object to be inspected 102 is increased. In such a case, the divergence of the illumination increases. On the other hand, FIG. 8(b) shows a state in which the distance between the first illumination unit 22, the second illumination unit 23, and the object to be inspected 102 is decreased. In such a case, the divergence of the illumination decreases.

[0049] Returning to the flowchart of Fig. 7, next, the first illumination unit 22 and the second illumination unit 23 illuminate the inspection object 102 (S16). Since the optical axis angles of the first illumination unit 22 and the second illumination unit 23 have been adjusted, it is possible to illuminate the inspection object 102 under illumination conditions that are not significantly different from those before the movement of the appearance inspection device 20.

[0050] Next, the inspection object 102 is imaged by the imaging unit 21 (S18). The image thus captured is sent to the image processing unit 40, where the presence or absence of defects in the inspection object 102 is determined.

[0051] The present invention has been described above based on the embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0052] 10 robot arm, 20 appearance inspection device, 21 imaging section, 22 first illumination section, 23 second illumination section, 24 holding section, 25 first movement mechanism, 26 second movement mechanism, 30 control section, 40 image processing section, 100 robot system, 102 object to be inspected, 104 defective section.

Claims

1. an imaging unit that images an object to be inspected; an illumination unit that illuminates the object to be inspected; A visual inspection apparatus comprising: The imaging unit and the illumination unit are configured to be movable as a unit, The illumination unit is configured to be able to change an optical axis angle with respect to a light receiving surface of the imaging unit.

2. 2. The visual inspection apparatus according to claim 1, wherein an optical axis angle of the illumination unit is controlled in a direction that minimizes a change in an angle of the reflected light from the inspected object that is input to the imaging unit.

3. 2. The visual inspection apparatus according to claim 1, wherein the illumination unit is configured to be capable of changing an amount of illumination light in response to a change in an optical axis angle.

4. A robot arm equipped with the visual inspection device according to claim 1; A control unit that controls an angle of the optical axis of the illumination unit and an operation of the robot arm; A robot system comprising:

5. moving the imaging unit and the illumination unit as one unit; changing an optical axis angle of the illumination unit with respect to a light receiving surface of the imaging unit in response to the movement; Illuminating an object to be inspected with the illumination unit; capturing an image of the inspection object with the imaging unit; A visual inspection method comprising:

6. 6. The visual inspection method according to claim 5, further comprising a step of adjusting a distance between the illumination unit and the object to be inspected.

Images