Appearance inspection device

Abstract

To provide a technology with which, even when the surface of an object includes regions differing in inclination, it is possible to inspect these regions differing in inclination at the same time.SOLUTION: Provided is an appearance inspection device for inspecting the appearance of an object. The visual inspection device comprises: a plurality of light sources for irradiating the object with light; a plurality of wall parts that enclose each of the light sources in a concentric circular form; an irradiation change part for changing the irradiation angle of the light with which the object is irradiated, by controlling an outside illumination diameter defined by the light emitted from each of the light sources; an imaging part for capturing an image of the light reflected from the object when light is emitted with different illumination outer diameters so as to acquire images of the object when light is emitted with respective illumination outer diameters; and a determination unit for determining the presence / absence of an abnormality in the appearance of the object by using an integral luminance value derived by integrating the luminance values of pixels in the plurality of images for each object position.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an appearance inspection apparatus.

Background Art

[0002] Conventionally, a technique for inspecting the appearance of an object by imaging reflected light from the object irradiated with light has been known. For example, Patent Document 1 discloses an inspection system including an inspection illumination device and an imaging device in which a first light shielding mask, a second light shielding mask, a lens, and a half mirror are arranged along the direction in which light irradiated from a surface light source travels.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When inspecting the appearance of an object, it is necessary to perform alignment of the object with high accuracy so that the imaging device can receive the reflected light from the surface of the object. However, when the object to be inspected includes portions with different inclinations on the surface to be inspected, sufficient consideration has not been given to simultaneously inspecting these portions with different inclinations accurately. For this reason, a technique capable of simultaneously inspecting portions with different inclinations has been desired. Note that Patent Document 1 does not consider at all inspecting an object including portions with different inclinations on the surface.

[0005] The present invention has been made to solve at least a part of the above-described problems, and an object thereof is to provide a technique capable of simultaneously inspecting portions with different inclinations when inspecting an object including portions with different inclinations on the surface.

Means for Solving the Problems

[0006] The present invention has been made to solve at least a part of the above-described problems and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, there is provided an appearance inspection apparatus for inspecting the appearance of an object. The appearance inspection apparatus includes a plurality of light sources that irradiate the object with light, a plurality of wall portions that concentrically surround each of the light sources, and an irradiation change unit that changes an irradiation angle of the light irradiated onto the object by controlling an illumination outer diameter defined by the light irradiated from each of the light sources, and an imaging unit that acquires an image of the object when the object is irradiated with light at each of the illumination outer diameters by imaging light reflected from the object when the object is irradiated with light at different illumination outer diameters, and a determination unit that determines whether there is an abnormality in the appearance of the object using a luminance integration value obtained by integrating luminance values of each pixel in the plurality of images for each position of the object.

[0008] According to this configuration, the light irradiated from each of the light sources concentrically surrounded by the wall portions is multiply reflected by the wall portions sandwiching the light source and then emitted outside the wall portions. Therefore, these light sources can be regarded as forming a circular surface light source. That is, according to this configuration, circular uniform light can be irradiated from the circular surface light source. Further, according to this configuration, a plurality of images of the object are acquired when the illumination outer diameter of the circular surface light source is changed and the irradiation angle of the light irradiated onto the object is changed, and the luminance integration value of each pixel calculated from these images is used to determine whether there is an abnormality in the appearance of the object. Therefore, even for an object including portions having different inclinations on the surface to be inspected, these portions having different inclinations can be inspected simultaneously.

[0009] (2) In the appearance inspection apparatus according to the above aspect, the luminance integration value may be a value obtained by normalizing the luminance values of each pixel in the plurality of images and then integrating the normalized luminance values for each position of the object. When an object is covered with a processing oil, the intensity of the light reflected from the object decreases, and thus the luminance value of the pixels constituting the object also tends to decrease in the image of the object captured. According to this configuration, the luminance integration value obtained by integrating the luminance values of the normalized pixels for each position of the object is used for determining the appearance abnormality of the object. Therefore, since the luminance values of the pixels constituting the object covered with the processing oil or partially adhered with the processing oil in the captured image are corrected by normalization, the appearance of the object can be inspected while reducing the influence of the processing oil.

[0010] Note that the present invention can be realized in various aspects, for example, in the form of an appearance inspection device, an appearance inspection system, an appearance inspection method, a control method for an appearance inspection operation, a computer program for executing these devices and methods, a server device for distributing this computer program, a non-transitory storage medium storing the computer program, and the like.

Brief Description of the Drawings

[0011]

Figure 1

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Embodiments for Carrying Out the Invention

[0012] <First Embodiment> FIG. 1 is an explanatory diagram illustrating the configuration of an appearance inspection apparatus 1 as a first embodiment of the present invention. In FIG. 1, XYZ axes orthogonal to each other are illustrated. The X-axis corresponds to the direction in which the light irradiated from a light source unit 5 described later travels, and the Y-axis and Z-axis correspond to directions orthogonal to the X-axis. These XYZ axes are common to each figure after FIG. 1. The appearance inspection apparatus 1 is an apparatus for inspecting the appearance of an object OB. In other words, the appearance inspection apparatus 1 is an apparatus for determining the presence or absence of abnormalities such as chips, dents, and indentations in the appearance of the object OB. The appearance inspection apparatus 1 includes a light source unit 5, a plano-convex lens 40, a half mirror 50, a camera 60, and a control unit 70. In FIG. 1, an optical axis AX indicates the optical axis of the light source unit 5.

[0013] FIG. 2(A) shows a cross section of the light source unit 5 along the line F2A - F2A in FIG. 1. FIG. 2(B) shows a cross section of the light source unit 5 along the line F2B - F2B in FIG. 2(A). As shown in FIG. 1, the light source unit 5 is a unit in which a plate-like member 10, a wall member 20, and a diffusion member 30 are laminated in the X-axis direction. As shown in FIG. 2(B), on the surface of the plate-like member 10 facing the +X-axis direction side, light sources 11 to 15 for irradiating the object OB with light are arranged. Specifically, as shown in FIG. 2(A), when viewed from the +X-axis direction side, one light source 11 is arranged at the center, and a plurality of light sources 12 are arranged in a circular shape so as to surround the light source 11. Further, a plurality of light sources 13 are arranged in a circular shape so as to surround the plurality of light sources 12. Similarly, a plurality of light sources 14 are arranged in a circular shape so as to surround the plurality of light sources 13, and a plurality of light sources 15 are arranged in a circular shape so as to surround the plurality of light sources 14. That is, the light sources 12 to 15 are arranged in concentric circles on the surface of the plate-like member 10 facing the +X-axis direction side. In the present embodiment, the light sources 11 to 15 are LEDs.

[0014] As shown in Fig. 2(A), the wall member 20 includes wall portions 21 to 25 that concentrically surround each of the light sources 11 to 15 when viewed from the +X-axis direction side. Each of the wall portions 21 to 25 is formed so as to surround the light sources 11 to 15 when viewed from the +X-axis direction side and extends along the X-axis direction (see Fig. 2(B)). Specifically, each of the wall portions 21 to 24 is formed in a circular shape when viewed from the +X-axis direction side and is arranged so as to surround the light sources 11 to 14. The wall portion 25 is formed in a rectangular parallelepiped shape having a cylindrical through-hole (the space in which the light sources 11 to 15 and the wall portions 21 to 24 are arranged) in the central portion when viewed from the +X-axis direction side and is arranged so as to surround the light source 15. The diffusion member 30 diffuses the light emitted from the light sources 11 to 15. In Figs. 2(A) and 2(B), since the wall portions 21 to 24 are cross-sections, they should originally be shown with hatching, but the hatching is omitted for the sake of illustration.

[0015] As shown in Fig. 1, the plano-convex lens 40 is arranged between the light source unit 5 and a half mirror 50 described later in the X-axis direction. The plano-convex lens 40 condenses the light emitted from the light sources 11 to 15 through the diffusion member 30. The half mirror 50 is arranged between the plano-convex lens 40 and the position where the object OB is arranged in the X-axis direction. The half mirror 50 transmits a part of the light emitted from the light sources 11 to 15 through the diffusion member 30 toward the object OB and reflects a part of the light reflected from the object OB toward a camera 60 described later.

[0016] The camera 60 is an imaging unit that images the light reflected from the object OB. The telecentric lens 62 attached to the camera 60 transmits only the light parallel to the optical axis of the telecentric lens 62 to the camera 60. The control unit 70 is a computer including a ROM, a RAM, and a CPU, and performs various controls of the appearance inspection device 1.

[0017] FIG. 3 is an explanatory diagram showing an example of an object OB to be inspected by the appearance inspection apparatus 1. The object OB shown in FIG. 3 includes portions on the surface with different inclinations. Specifically, the surface of the object OB facing the -X axis direction side includes surfaces S0 to S3. Surface S1 is an inclined surface inclined at an angle of 1° with respect to surface S0. Surfaces S2 and S3 are inclined surfaces inclined at angles of 2° and 3° with respect to surface S0, respectively. That is, these surfaces S0 to S3 correspond to portions on the surface of the object OB with different inclinations.

[0018] FIGS. 4(A) to 4(C) are explanatory diagrams for explaining the advantages of the light source unit 5 including the wall portions 21 to 25. The configurations of the plate-like member 10, light sources 11 to 13, wall portions 21 to 23, and diffusion member 30 used in the description of FIGS. 4(A) to 4(C) are the same as the configurations with the same reference numerals described above. On the left side of FIGS. 4(A) to 4(C), the plate-like member 10 and the diffusion member 30 as viewed from the -Y axis direction side (the same viewpoint as in FIG. 1) are shown. On the right side of FIGS. 4(A) to 4(C), the diffusion member 30 as viewed from the +X axis direction side is shown. In FIGS. 4(A) and 4(B), the light sources 11 to 13 are arranged on the plate-like member 10, but the wall portions 21 to 23 are not arranged. When light is irradiated from the light sources 11 and 12 arranged in this way, as shown on the right side of FIG. 4(A), the outer shape of the light irradiated from the diffusion member 30 is a shape in which a plurality of circles overlap. In such a shape, there is a difference in brightness between the portion where the circles overlap and the portion where the circles do not overlap, so there is unevenness in brightness. Further, when light is also irradiated from the light source 13 in addition to the state shown in FIG. 4(A), as shown on the right side of FIG. 4(B), the outer shape of the light irradiated from the diffusion member 30 approaches a circular shape. However, even when the irradiation of light from the light source 13 is added, the outer edge of the light irradiated from the diffusion member 30 does not become smooth, and the outer shape of the light irradiated from the diffusion member 30 is still a shape in which a plurality of circles overlap, and there is unevenness in brightness.

[0019] On the one hand, in FIG. 4(C), like the above-described appearance inspection apparatus 1, light sources 11 to 13 are arranged on the plate-like member 10, and each of these light sources 11 to 13 is covered by the wall portions 21 to 23. When light is irradiated from such light sources 11 to 13, as shown on the right side of FIG. 4(C), the outer shape of the light irradiated from the diffusion member 30 becomes circular. This is because the light irradiated from each of the light sources 11 to 13 surrounded concentrically by the wall portions 21 to 23 is multiply reflected by the wall portions 21 to 23 and then emitted outside the wall portions 21 to 23. That is, the light sources 11 to 13 can be regarded as forming a circular surface light source due to the arrangement of the wall portions 21 to 23. Similar to the configuration described with reference to FIG. 4(C), in the above-described appearance inspection apparatus 1, since each of the light sources 11 to 15 is surrounded concentrically by the wall portions 21 to 25, the light sources 11 to 15 can be regarded as forming a circular surface light source. And from such a surface light source, circular and uniform light is irradiated.

[0020] FIGS. 5 to 7 are explanatory diagrams showing a state in which light is irradiated from the light source unit 5 to the object OB. On the left side of FIGS. 5 to 7, the light source unit 5 viewed from the +X-axis direction side (the same viewpoint as the right side of FIGS. 4(A) to (C)) is shown. From the center to the right side of FIGS. 5 to 7, the appearance inspection apparatus 1 viewed from the -Y-axis direction side (the same viewpoint as FIG. 1) is shown. In FIGS. 5 to 7, among the light source unit 5 viewed from the +X-axis direction side, the wall portions 21 to 25 are hidden by the diffusion member 30 and are thus indicated by wavy lines.

[0021] Figure 5 shows a state where light is irradiated only from the inside of the wall portion 21. In other words, it shows a state where light is irradiated only from a light source 11 (not shown in FIG. 5) surrounded by the wall portion 21. FIG. 6 shows a state where light is irradiated from between each of the wall portions 21 to 23. In other words, it shows a state where light is irradiated from light sources 11 to 13 (not shown in FIG. 5) surrounded by each of the wall portions 21 to 23. FIG. 7 shows a state where light is irradiated from between each of the wall portions 21 to 25. In other words, it shows a state where light is irradiated from light sources 11 to 15 (not shown in FIG. 5) surrounded by each of the wall portions 21 to 25. The illumination outer diameters D1, D3, D5 shown in each of FIGS. 5 to 7 are the outer diameters of the light irradiated from the light source unit 5 in each state.

[0022] By functioning as an irradiation change unit, the control unit 70 controls the illumination outer diameter (see the illumination outer diameters D1, D3, D5 in FIGS. 5 to 7) defined by the light irradiated from each of the light sources 11 to 15, thereby changing the irradiation angle θ of the light irradiated onto the object OB (see FIGS. 5 to 7). That is, the control unit 70 changes the illumination angle defined by the light irradiated onto the object OB by controlling the irradiation for each of the light sources 11 to 15 arranged concentrically. As shown in FIGS. 5 to 7, the larger the illumination outer diameter, the larger the irradiation angle θ. Then, the camera 60, which is an imaging unit, acquires an image of the object OB when light is irradiated with different illumination outer diameters by imaging the light reflected from the object OB when irradiated with light. When acquiring a plurality of images of the object OB by changing the illumination outer diameter, it is assumed that the positional relationship between the camera 60 and the object OB is fixed. Even if the surface of the object OB, like the object OB shown in FIG. 3, includes portions with different inclinations, the larger the irradiation angle θ of the light irradiated onto the object OB, the easier it is for each of the lights reflected from those portions to be captured by the camera 60. In other words, the larger the illumination outer diameter when the object OB is irradiated with light, the lower the contrast of each pixel constituting the object OB in the image.

[0023] FIG. 8 is an explanatory diagram of a method for determining the presence or absence of an abnormality in the appearance of the object OB. In the appearance inspection apparatus 1, the control unit 70 functions as a determination unit, and uses the luminance integration value obtained by integrating the luminance values of each pixel in a plurality of images captured by the camera 60 for each position of the object OB to determine the presence or absence of an abnormality in the appearance of the object OB. The details of the method will be described below. First, the control unit 70 creates a luminance integration image IN using the image group IG (the image group of the object OB when irradiated with light at each illumination outer diameter) captured by the camera 60. Specifically, the control unit 70 calculates the luminance integration value by integrating the luminance values of the pixels constituting each position of the object OB in each of the images for each same position, and then creates the luminance integration image IN by arranging each of the calculated luminance integration values corresponding to each position of the object OB. Next, the control unit 70 creates a difference image DF between the reference image ST (to be described later) and the luminance integration image IN. The reference image ST is a luminance integration image created from the image group IG that captures the object OB without an abnormality in appearance. The difference image DF is created by taking the difference in luminance values between the pixels constituting the same position of the object OB in each of the reference image ST and the luminance integration image IN.

[0024] Next, the control unit 70 calculates the average value of the luminance integration values of the pixels constituting the difference image DF, and then, as shown in the graph GR in FIG. 8, determines the pixels in which the luminance integration values included in the average value ± kσ (k is an arbitrary constant) are arranged as the normal part NM, and the pixels in which the luminance integration values not included in the average value ± kσ are arranged as the provisional abnormal part AB. The graph GR is a histogram regarding the luminance integration values of the pixels constituting the difference image DF. Next, the control unit 70 creates an extraction image EX by extracting only the pixels determined as the provisional abnormal part AB among the pixels constituting the difference image DF. Next, the control unit 70 draws a rectangle circumscribing the part (two parts are shown in FIG. 8) constituted by the pixels determined as the provisional abnormal part AB in the extraction image EX. Then, when the short side SS of this rectangle is equal to or longer than a preset length, the control unit 70 determines that there is an abnormality in the appearance of the object OB. On the other hand, when the short side SS of this rectangle is shorter than the preset length, the control unit 70 determines that there is no abnormality in the appearance of the object OB.

[0025] As described above, according to the appearance inspection apparatus 1 of the first embodiment, the light emitted from each of the light sources 11 to 15 surrounded concentrically by the wall portions 21 to 25 is multiply reflected by the wall portions 21 to 25 sandwiching the light sources 11 to 15 and then emitted outside the wall portions 21 to 25. Therefore, these light sources 11 to 15 can be regarded as forming a circular surface light source. That is, according to the appearance inspection apparatus 1 of the first embodiment, the object OB can be irradiated with light from a circular surface light source. Further, according to the appearance inspection apparatus 1 of the first embodiment, a plurality of images of the object OB are acquired when the illumination outer diameter of the circular surface light source is changed and the irradiation angle θ of the light irradiated to the object OB is changed, and the luminance integrated value of each pixel calculated from these images is used to determine the presence or absence of an appearance abnormality of the object OB. Therefore, even for the object OB including portions with different slopes on the surface to be inspected, these portions with different slopes can be inspected simultaneously. Specifically, as the irradiation angle θ of the light irradiated to the object OB increases, even if the surface of the object OB includes portions with different slopes (see FIG. 3), each of the lights reflected from these portions is more likely to be captured by the camera 60, and since the luminance integrated value calculated from a plurality of images including such images is used for the determination, it means that portions with different slopes can be inspected simultaneously.

[0026] In a conventional appearance inspection apparatus, a display capable of emitting light from all or part of a screen may be used as a light source for irradiating an object with light. In such a display, the outer diameter of illumination can be changed by designating a light-emitting region, and the irradiation angle θ of the light irradiated onto the object can be changed. However, since the amount of light generally irradiated from a display is small, the time for irradiating the object with light tends to be long for imaging in appearance inspection. In order to increase the amount of light, it is conceivable to use LEDs arranged in an array as a light source instead of a display. However, since light rays are irradiated from each of the LEDs arranged in an array, gaps may occur between the respective light rays, resulting in a difference in brightness between the gaps and the light rays, causing uneven brightness. In order to use such an array of LEDs as a surface light source, it is also conceivable to arrange a diffusion plate on the irradiation direction side of the LEDs. However, also in this case, as described with reference to FIGS. 4(A) and 4(B), the outer shape of the light irradiated from those LEDs has a shape in which a plurality of circles overlap, resulting in uneven brightness. In this regard, in the appearance inspection apparatus 1 of the first embodiment, since each of the light sources 11 to 15 is concentrically surrounded by the wall portions 21 to 25, the light sources 11 to 15 can be regarded as forming a circular surface light source, and a circular and uniform light can be irradiated from such a surface light source.

[0027] <Second Embodiment> The appearance inspection apparatus of the second embodiment differs in the method of determining the presence or absence of an abnormality in the appearance of the object OB as compared with the appearance inspection apparatus 1 of the first embodiment. In the second embodiment, the luminance integrated value is a value obtained by normalizing the luminance values of each pixel in a plurality of images (image group IG in FIG. 8) for each position and then integrating the normalized luminance values for each position of the object OB. Specifically, in the second embodiment, the control unit 70 creates a luminance integrated image INa (not shown) by arranging each of the luminance integrated values corresponding to each position of the object OB. After creating the luminance integrated image INa, the processes after the creation of the difference image DF described in FIG. 8 are not performed.

[0028] Normalization will be described. Normalization is a process of dividing the difference between the luminance value of each pixel constituting the same position of the object OB in a plurality of images and the minimum luminance value of the pixels constituting the same position by the difference between the maximum luminance value and the minimum luminance value of the pixels constituting the same position. Through this normalization, the luminance value of each pixel constituting the same position is converted into a value within the range of 0 to 1.

[0029] FIG. 9 is an explanatory diagram of the object OB inspected by the appearance inspection apparatus according to the second embodiment. FIG. 9(A) shows one of the image groups IG (see FIG. 8) of the object OB captured by the camera 60 in the appearance inspection apparatus according to the second embodiment. At this time, it is assumed that the object OB has processing oil attached thereto. When the object OB is covered with processing oil or the processing oil is partially attached to the object OB, the intensity of the light reflected from the object OB decreases, and thus the luminance value of the pixels constituting the object also tends to decrease in the image of the object OB captured. The horizontal axis in FIG. 9(A) indicates the distance from the left end of the image.

[0030] FIG. 9(B) shows the luminance integration values at each position of the luminance integration image IN created without normalization from the image group IG. The horizontal axis in FIG. 9(B) indicates the distance from the left end among the positions indicated by the wavy line in FIG. 9(A), and the vertical axis indicates the luminance integration value at each position. FIG. 9(C) shows the luminance integration values at each position of the luminance integration image INa created after normalization from the image group IG. The horizontal axis and the vertical axis in FIG. 9(C) are the same as those in FIG. 9(B).

[0031] As shown in FIG. 9(A), there is a recess D at a position 1 to 2 mm from the left end of the image. In FIG. 9(B), it seems that the luminance integration value changes relatively greatly at the position of 1 to 2 mm due to the presence of the recess D, but it is difficult to discriminate due to the influence of the processing oil. On the other hand, in FIG. 9(C), since the influence of the processing oil is reduced by normalization, it is possible to clearly discriminate that the luminance integration value changes relatively greatly at the position of 1 to 2 mm due to the presence of the recess D. Specifically, a significant decrease in the luminance integration value due to the left end and the right end of the recess D can be clearly discriminated as protruding portions in the lower direction of the two drawings. In the appearance inspection apparatus of the second embodiment, the presence or absence of an abnormality in the appearance of the object OB is determined using the result shown in FIG. 9(C). For example, the determination may be executed based on the inclination of the luminance integration value and the length of the inclination. Specifically, when the inclination below the set inclination continues for a set length or more in the inclination where the luminance integration value decreases, or when the inclination above the set inclination continues for a set length or more in the inclination where the luminance integration value increases, it may be determined that there is an abnormality.

[0032] Also with the appearance inspection apparatus of the second embodiment as described above, it is possible to simultaneously inspect portions of the object OB having different inclinations. Further, according to the appearance inspection apparatus of the second embodiment, the luminance integration value obtained by integrating the luminance values of the normalized respective pixels for each position of the object OB is used for determining an appearance abnormality of the object OB. Therefore, since the luminance values of the pixels constituting the object OB covered with the processing oil or partially adhered with the processing oil in the captured image are corrected by normalization, it is possible to inspect the appearance of the object OB while reducing the influence of the processing oil.

[0033] As an example where the object OB is covered with processing oil or the processing oil is partially attached to the object OB, the case where the object OB is a part immediately after press working can be cited. A part immediately after press working is a part immediately after being press worked in a state of being covered with processing oil for lubrication in a press die. Since parts after press working are continuously produced by a press die, if problems such as adhesion of foreign matter occur in the press die, there is a risk that defects, dents, indentations, etc. may occur in the appearance of a large number of the same parts. However, conventionally, since it was difficult to inspect parts in a state covered with processing oil, in order to detect such abnormalities, it was necessary to remove the processing oil from the parts in advance before inspection. Therefore, the time required for inspection tends to become long, and if parts with abnormal appearance are continuously produced during that time, it becomes a factor in reducing the yield. In this regard, according to the appearance inspection apparatus of the second embodiment, since it is possible to inspect parts immediately after press working without removing the processing oil, it is possible to early detect the presence or absence of abnormalities in the appearance of parts immediately after press working. Therefore, since an operator can early recognize problems such as adhesion of foreign matter to the press die, the yield can be improved.

[0034] <Third Embodiment> The appearance inspection apparatus of the third embodiment is the same as the first embodiment in that the presence or absence of abnormalities in the appearance of the object OB is determined by the method shown in FIG. 8, but in this method, similarly to the second embodiment, it is different in that the luminance integrated image INa created through normalization from the image group IG is used. Also, the appearance inspection apparatus of the third embodiment is different from the first embodiment in that a reference image STa different from the reference image ST is used for creating the difference image DF. The reference image STa is a luminance integrated image created through normalization from an image group IG that images an object OB without appearance abnormalities.

[0035] Also by the appearance inspection apparatus of the third embodiment as described above, it is possible to simultaneously inspect parts with different inclinations included in the object OB. Further, it is possible to inspect the appearance of the object OB while reducing the influence of the processing oil.

[0036] <Modification Example of this Embodiment> The present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the gist thereof. For example, the following modifications are possible.

[0037] In the above-described embodiments, the light sources 11 to 15 were LEDs, but the present invention is not limited thereto. The light sources 11 to 15 may be another point light source different from the LEDs (for example, a halogen lamp or the like).

[0038] In the above-described embodiments, one light source 11 was surrounded by the wall portion 21, but the present invention is not limited thereto. Inside the wall portion 21, a plurality of light sources 11 may be arranged in a circular shape. Further, in the above-described embodiments, the light sources 12 to 15 surrounded by each of the wall portions 22 to 25 were arranged in a single circular shape, but they may be arranged in a double or more circular shape. That is, the light sources 11 to 15 may be arbitrarily arranged as long as they are surrounded by the wall portions 21 to 25 in a concentric circular shape.

[0039] In the above-described embodiments, the diffusion member 30 was used as a member for diffusing the light emitted from the light sources 11 to 15, but the present invention is not limited thereto. For example, instead of the diffusion member 30, a resin material in which a diffusing material or a phosphor is dispersed may be filled between each of the wall portions 21 to 25.

[0040] In the above-described embodiments, the object OB to be inspected was an object including portions having different slopes on the surface, but the present invention is not limited thereto. The object OB to be inspected in the above-described embodiments may be an object not including portions having different slopes on the surface. That is, the object OB to be inspected in the above-described embodiments may be an object having a flat surface.

[0041] In the above-described second embodiment, it was assumed that after normalization, the luminance values of the pixels constituting the same position of the object OB in a plurality of images are converted into values within the range of 0 to 1, but this is not limiting. After normalization, a numerical value different from 1 may be newly assigned to the maximum value of the range of luminance values, or a numerical value different from 0 may be newly assigned to the minimum value. For example, after normalization, 100 may be newly assigned to the maximum value and -100 may be newly assigned to the minimum value. Also, the minimum value may remain 0 and only 255 may be newly assigned to the maximum value. That is, as long as the distribution of the luminance values of the pixels included in the range from the minimum value to the maximum value does not change compared to before normalization, any value may be newly assigned to the maximum value and the minimum value.

[0042] As described above, the present aspect has been described based on the embodiments and modified examples. However, the embodiments of the above-described aspects are for facilitating the understanding of the present aspect and do not limit the present aspect. The present aspect can be changed and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in the present aspect. Also, if its technical features are not described as essential in this specification, they can be deleted as appropriate.

Description of Reference Numerals

[0043] 1…Appearance inspection device 5…Light source unit 10…Plate-like member 11~15…Light source 20…Wall member 21~25…Wall portion 30…Diffusion member 40…Plano-convex lens 50…Half mirror 60…Camera 62…Telecentric lens 70…Control unit

Claims

1. An appearance inspection device for inspecting the appearance of an object, comprising: a plurality of light sources for irradiating the object with light; a plurality of wall portions surrounding the plurality of light sources concentrically; an irradiation change unit for changing the irradiation angle of the light irradiated on the object by controlling the illumination outer diameter defined by the light irradiated from each of the light sources; an imaging unit for obtaining an image of the object when the object is irradiated with light at each of the illumination outer diameters by imaging the light reflected from the object when the object is irradiated with light at different illumination outer diameters; a determination unit for determining the presence or absence of an abnormality in the appearance of the object using a luminance integration value obtained by integrating the luminance values of each pixel in the plurality of images for each position of the object. An appearance inspection device.

2. The appearance inspection device according to claim 1, wherein the luminance integration value is a value obtained by normalizing the luminance values of each pixel in the plurality of images and then integrating the normalized luminance values for each position of the object. An appearance inspection device.

Images