Imaging apparatus and imaging method

Abstract

To properly inspect the surface of a workpiece.SOLUTION: An imaging apparatus 10 includes a camera 11 which captures a workpiece 20 having a curved surface shape, an illumination device 12 which irradiates the workpiece 20 with light, and a control device 14 which relatively changes the attitude of the workpiece 20 with respect to the camera 11 and the illumination device 12 by relatively rotating the workpiece 20 around a rotation axis A2 crossing an optical axis A1 of the camera 11 with respect to the camera 11 and the illumination device 12, acquires a plurality of captured images obtained by capturing the workpiece 20 in each of a plurality of attitudes different from each other by the camera 11, and synthesizes the plurality of captured images, to generate a synthetic image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an imaging device and an imaging method. [Background technology]

[0002] Inspection of the surfaces of workpieces is carried out at production sites. For example, as disclosed in Patent Document 1, a technology has been proposed in which the workpiece is photographed by a camera while being irradiated with light, and the obtained image is used to inspect the surface of the workpiece for scratches, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-038215 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a workpiece has a curved shape, the direction of light reflection on the surface of the workpiece varies depending on the position on the surface. As a result, the image of the workpiece may contain areas with excessively high brightness or areas with excessively low brightness. For example, a phenomenon called halation may occur in which part of the light irradiated to the workpiece is reflected toward the camera, causing part of the obtained image to be blown out. When halation occurs, it may be difficult to properly inspect the surface of the workpiece.

[0005] An object of the present disclosure is to provide an imaging device and an imaging method capable of appropriately inspecting the surface of a workpiece. [Means for solving the problem]

[0006] In order to solve the above problems, the imaging device disclosed herein includes a camera that images a workpiece having a curved shape, a lighting device that irradiates light onto the workpiece, and a control device that changes the posture of the workpiece relative to the camera and the lighting device by rotating the workpiece relative to the camera and the lighting device around a rotation axis that intersects with the optical axis of the camera, obtains multiple captured images of the workpiece in each of multiple different postures by the camera, and combines the multiple captured images to generate a composite image.

[0007] Before generating a composite image, the control device may correct at least a portion of the multiple captured images so that the dimensions of the area in which the workpiece is displayed in each of the multiple captured images match the dimensions of the area in which the workpiece is displayed in an image obtained when the workpiece is captured by a camera in a specific posture among multiple different postures.

[0008] The control device may generate a composite image by excluding a first region, the first region having a luminance higher than a first threshold, from each of the plurality of captured images.

[0009] The control device may generate a composite image by excluding a second region, in which the luminance is lower than a second threshold, from each of the plurality of captured images.

[0010] The control device may detect scratches formed on the surface of the workpiece based on the composite image.

[0011] The control device may change the posture of the workpiece by rotating the workpiece about a rotation axis without rotating the camera and the lighting device.

[0012] In order to solve the above problems, the imaging method disclosed herein includes a camera that images a workpiece having a curved shape, and a lighting device that irradiates light onto the workpiece, thereby changing the posture of the workpiece relative to the camera and the lighting device by rotating the workpiece about a rotation axis that intersects with the optical axis of the camera relative to the camera, a computer acquiring a plurality of captured images of the workpiece in each of a plurality of different postures captured by the camera, and a computer combining the plurality of captured images to generate a composite image. Effect of the Invention

[0013] According to the present disclosure, the surface of a workpiece can be properly inspected. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of an imaging device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a block diagram illustrating an example of a functional configuration of the control device according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is a flowchart illustrating an example of a flow of processing performed by the control device according to the embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram illustrating a first attitude of a workpiece according to an embodiment of the present disclosure. [Diagram 5] FIG. 5 is a diagram illustrating a second attitude of the workpiece according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram illustrating a third posture of the workpiece according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram showing a captured image showing a workpiece in a first posture according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram showing a captured image showing a workpiece in a second posture according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing a captured image showing a workpiece in a third posture according to an embodiment of the present disclosure. [Figure 10]FIG. 10 is a diagram showing a captured image showing a workpiece in a first attitude and a corresponding corrected image according to an embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram showing a captured image showing a workpiece in a third attitude according to an embodiment of the present disclosure and a corresponding corrected image. [Figure 12] FIG. 12 is a diagram illustrating a composite image showing a workpiece according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present disclosure are not illustrated.

[0016] Fig. 1 is a schematic diagram showing the configuration of an imaging device 10 according to this embodiment. The imaging device 10 is a device for obtaining an image of a workpiece 20 as a subject for inspecting the surface of the workpiece 20. As shown in Fig. 1, the imaging device 10 includes a camera 11, a lighting device 12, a positioning device 13, and a control device 14. The upward direction in Fig. 1 coincides with the vertical upward direction, and the downward direction in Fig. 1 coincides with the vertical downward direction. However, the orientation of each component relative to the vertical direction is not limited to the example in Fig. 1.

[0017] The camera 11 captures a visible light image. Specifically, the camera 11 has a plurality of imaging elements that detect visible light. The visible light is detected by the imaging elements, thereby obtaining a visible light image. As will be described later, the camera 11 captures an image with the workpiece 20 positioned on the optical axis A1 of the camera 11. This allows the camera 11 to capture an image of the workpiece 20.

[0018] In the example of Fig. 1, the camera 11 extends in the vertical direction. Therefore, the optical axis A1 of the camera 11 extends in the vertical direction. An imaging element is located at the lower end of the camera 11. The imaging range of the camera 11 extends radially downward from the lower end of the camera 11. The camera 11 is disposed above the workpiece 20. The position of the camera 11 may be adjustable.

[0019] The lighting device 12 irradiates light onto the workpiece 20. In the example of FIG. 1, the lighting device 12 has a circular ring shape. When the lighting device 12 has a circular ring shape, a shadow is less likely to be formed on the surface of the workpiece 20. However, the shape of the lighting device 12 is not limited to a circular ring shape, and may be, for example, a rod shape. In the example of FIG. 1, the lighting device 12 is arranged coaxially with the optical axis A1 of the camera 11. The lighting device 12 is located below the lower end of the camera 11. The lighting device 12 is arranged above the workpiece 20. The position of the lighting device 12 may be adjustable.

[0020] The positioning device 13 positions the workpiece 20. The positioning device 13 includes a mounting portion 13a to which the workpiece 20 is attached. For example, the positioning device 13 has a substantially rectangular parallelepiped shape. The mounting portion 13a is provided on a side of the positioning device 13. For example, the mounting portion 13a has a substantially cylindrical shape. The mounting portion 13a is disposed coaxially with a rotation axis A2 perpendicular to the optical axis A1. In other words, the central axis of the mounting portion 13a coincides with the rotation axis A2. The mounting portion 13a is rotatable around the rotation axis A2. However, the rotation axis A2 only needs to intersect with the optical axis A1, and does not need to be perpendicular to the optical axis A1.

[0021] The mounting portion 13a can grip the workpiece 20 using a gripping mechanism such as a three-jaw chuck (not shown). When the mounting portion 13a rotates with the workpiece 20 attached to it, the workpiece 20 rotates around the rotation axis A2. This changes the posture of the workpiece 20.

[0022] The positioning device 13 may be movable in the horizontal direction. By moving the positioning device 13 in the horizontal direction, the workpiece 20 can be moved in the horizontal direction.

[0023] The control device 14 controls each device of the imaging device 10 and performs image processing. The control device 14 includes, for example, a central processing unit (CPU), a ROM in which programs and the like are stored, and a RAM as a work area.

[0024] Fig. 2 is a block diagram showing an example of a functional configuration of the control device 14. As shown in Fig. 2, the control device 14 includes an acquisition unit 14a, a control unit 14b, and a processing unit 14c.

[0025] The acquiring unit 14a acquires various kinds of information. For example, the acquiring unit 14a acquires an image captured by the camera 11 from the camera 11.

[0026] The control unit 14b controls the operation of each device of the imaging device 10. For example, the control unit 14b controls the operation of the camera 11. Also, for example, the control unit 14b controls the operation of the lighting device 12. Also, for example, the control unit 14b controls the operation of the positioning device 13.

[0027] The processing unit 14c performs various types of image processing. The image processing performed by the processing unit 14c will be described in detail later.

[0028] However, the functions of the control device 14 may be realized by one device or may be shared among multiple devices. In addition, as described below, some of the processes performed by the control device 14 may be replaced by processes performed manually by an operator.

[0029] As described above, the imaging device 10 is used for inspecting the surface of the workpiece 20. In inspecting the surface of the workpiece 20, as described below, the workpiece 20 is imaged by the camera 11 while the workpiece 20 is irradiated with light from the lighting device 12. Then, using the obtained image, for example, detection of scratches formed on the surface of the workpiece 20 is performed.

[0030] As shown in FIG. 4 and other figures, the workpiece 20 has a curved shape. That is, at least a part of the surface of the workpiece 20 is curved. Therefore, the reflection direction of light on the surface of the workpiece 20 varies depending on the position on the surface. In particular, the workpiece 20 is formed of, for example, a metal material. Therefore, the surface of the workpiece 20 has a high tendency to reflect light. Due to the curved shape of the workpiece 20, an image showing the workpiece 20 may include an area with excessively high brightness or an area with excessively low brightness. For example, a phenomenon called halation may occur in which a part of the light irradiated to the workpiece 20 is reflected toward the camera 11, causing a part of the obtained image to be blown out. When halation or the like occurs, it may be difficult to properly inspect the surface of the workpiece 20. Hereinafter, the invention of this embodiment for properly inspecting the surface of the workpiece 20 will be described.

[0031] Fig. 3 is a flow chart showing an example of the flow of processing performed by the control device 14. The processing flow shown in Fig. 3 is executed when inspecting the surface of the workpiece 20.

[0032] When the process flow shown in FIG. 3 starts, the control unit 14b starts irradiating the workpiece 20 with light in step S101.

[0033] In step S101, the control unit 14b starts emitting light from the lighting device 12. As a result, the lighting device 12 irradiates the workpiece 20 with light.

[0034] After step S101, the control unit 14b changes the posture of the workpiece 20 in step S102.

[0035] In step S102, the control unit 14b rotates the mounting unit 13a of the positioning device 13 about the rotation axis A2. This causes the workpiece 20 to rotate about the rotation axis A2, changing the posture of the workpiece 20. After the change in posture of the workpiece 20 is completed, the control unit 14b stops the rotation of the mounting unit 13a of the positioning device 13.

[0036] After step S102, the control unit 14b captures an image of the workpiece 20 in step S103.

[0037] In step S103, the control unit 14b captures an image of the workpiece 20 in the posture changed in the immediately preceding step S102, using the camera 11. This allows the acquisition unit 14a to acquire a captured image in which the workpiece 20 appears.

[0038] After step S103, in step S104, the control unit 14b determines whether or not imaging of the workpiece 20 in all postures has been completed. If it is determined that imaging of the workpiece 20 in all postures has not been completed (step S104 / NO), the process returns to step S102, and steps S102 and S103 are performed again. On the other hand, if it is determined that imaging of the workpiece 20 in all postures has been completed (step S104 / YES), the process proceeds to step S105.

[0039] As described above, in the imaging method using the imaging device 10, the posture of the workpiece 20 is changed to a plurality of postures, and the workpiece 20 in each posture is imaged by the camera 11. In the following, an example in which the posture of the workpiece 20 is changed to each of the first posture, the second posture, and the third posture will be described. In this example, steps S102 and S103 are repeated three times each. However, as will be described later, the postures that the workpiece 20 can take in the imaging method using the imaging device 10 are not limited to the following examples.

[0040] Fig. 4 is a diagram showing a first posture of the workpiece 20. Fig. 5 is a diagram showing a second posture of the workpiece 20. Fig. 6 is a diagram showing a third posture of the workpiece 20. Figs. 4 to 6 are views of the workpiece 20 viewed in the direction of the rotation axis A2. The upward direction in Figs. 4 to 6 coincides with the vertically upward direction, and the downward direction in Figs. 4 to 6 coincides with the vertically downward direction.

[0041] As shown in Figs. 4 to 6, the workpiece 20 has a generally flat plate shape. The thickness of the workpiece 20 is generally constant regardless of position. The workpiece 20 is curved in a cross section perpendicular to the rotation axis A2. The workpiece 20 extends in a direction along the rotation axis A2. The cross-sectional shape of the workpiece 20 in a cross section perpendicular to the rotation axis A2 is generally consistent at each position in the axial direction of the rotation axis A2. However, the shape of the workpiece 20 is not limited to the examples in Figs. 4 to 6.

[0042] For example, in the first step S102, the control unit 14b rotates the mounting unit 13a of the positioning device 13 to set the posture of the workpiece 20 to the first posture shown in Fig. 4. As shown in Fig. 4, in the first posture, in a region R11 at the center of the workpiece 20, the normal direction of the workpiece 20 tends to coincide with the direction of the optical axis A1 of the camera 11. The region R11 is a region that extends in the direction along the rotation axis A2.

[0043] In addition, in the second step S102, the control unit 14b rotates the mounting unit 13a of the positioning device 13 to change the posture of the workpiece 20 from the first posture in FIG. 4 to the second posture in FIG. 5. Specifically, the control unit 14b rotates the workpiece 20 in the clockwise direction in FIG. 4 in the state of FIG. 4 to change the posture of the workpiece 20 to the second posture in FIG. 5. As shown in FIG. 5, in the second posture, the normal direction of the workpiece 20 is likely to coincide with the direction of the optical axis A1 of the camera 11 in a region R21 between the left end and the center of the workpiece 20 when the workpiece 20 is viewed in the direction along the rotation axis A2 from the opposite side to the mounting unit 13a, and in a region R22 between the right end and the center of the workpiece 20 in the above case. The regions R21 and R22 are regions extending in the direction along the rotation axis A2.

[0044] In addition, in the third step S102, the control unit 14b rotates the mounting unit 13a of the positioning device 13 to change the posture of the workpiece 20 from the second posture in FIG. 5 to the third posture in FIG. 6. Specifically, the control unit 14b rotates the workpiece 20 clockwise in FIG. 5 in the state of FIG. 5 to change the posture of the workpiece 20 to the third posture in FIG. 6. As shown in FIG. 6, in the third posture, the normal direction of the workpiece 20 is likely to coincide with the direction of the optical axis A1 of the camera 11 in a region R31 at the left end of the workpiece 20 when the workpiece 20 is viewed in a direction along the rotation axis A2 from the opposite side to the mounting unit 13a, and in a region R32 at the right end of the workpiece 20 in the above case. The regions R31 and R32 are regions extending in a direction along the rotation axis A2.

[0045] Then, as described above, after each execution of step S102, an image of the workpiece 20 is captured in step S103.

[0046] Fig. 7 is a diagram showing a captured image P1 in which the workpiece 20 is in a first posture. Fig. 8 is a diagram showing a captured image P2 in which the workpiece 20 is in a second posture. Fig. 9 is a diagram showing a captured image P3 in which the workpiece 20 is in a third posture. In Figs. 7 to 9, the area in which halation occurs is indicated by hatching in each image.

[0047] As described above, in the first step S102, the posture of the workpiece 20 becomes the first posture in FIG. 4. Then, in step S103 following the first step S102, the control unit 14b captures the workpiece 20 in the first posture by the camera 11. As a result, the acquisition unit 14a can acquire the captured image P1 in FIG. 7 in which the workpiece 20 in the first posture is captured by the camera 11. As described above, in the first posture, the normal direction of the workpiece 20 is likely to coincide with the direction of the optical axis A1 of the camera 11 in the region R11 at the center of the workpiece 20. Therefore, the light irradiated to the region R11 of the workpiece 20 is reflected toward the camera 11. As a result, in the captured image P1 in FIG. 7, halation occurs in the region R11 of the workpiece 20.

[0048] As described above, in the second step S102, the posture of the workpiece 20 becomes the second posture of FIG. 5. Then, in step S103 following step S102, the control unit 14b captures the workpiece 20 in the second posture by the camera 11. As a result, the acquisition unit 14a can acquire the captured image P2 of FIG. 8 in which the workpiece 20 in the second posture is captured by the camera 11. As described above, in the second posture, in the region R21 between the left end and center of the workpiece 20 when the workpiece 20 is viewed in the direction along the rotation axis A2 from the opposite side to the mounting unit 13a, and in the region R22 between the right end and center of the workpiece 20 in the above case, the normal direction of the workpiece 20 is likely to coincide with the direction of the optical axis A1 of the camera 11. Therefore, the light irradiated to the region R21 and the region R22 of the workpiece 20 is reflected toward the camera 11. As a result, halation occurs in the region R21 and the region R22 of the workpiece 20 in the captured image P2 of FIG.

[0049] As described above, in the third step S102, the posture of the workpiece 20 becomes the third posture in FIG. 6. Then, in step S103 following the third step S102, the control unit 14b captures the workpiece 20 in the third posture by the camera 11. As a result, the acquisition unit 14a can acquire the captured image P3 in FIG. 9 in which the workpiece 20 in the third posture is captured by the camera 11. As described above, in the third posture, in the region R31 at the left end of the workpiece 20 when the workpiece 20 is viewed in the direction along the rotation axis A2 from the opposite side to the mounting portion 13a, and in the region R32 at the right end of the workpiece 20 in the above case, the normal direction of the workpiece 20 tends to coincide with the direction of the optical axis A1 of the camera 11. Therefore, the light irradiated to the regions R31 and R32 of the workpiece 20 is reflected toward the camera 11. As a result, in the captured image P3 in FIG. 9, halation occurs in the regions R31 and R32 of the workpiece 20.

[0050] When the imaging of the workpiece 20 in all of the first, second and third attitudes has been completed, a YES determination is made in step S104 in FIG. 3, and in step S105, the processing unit 14c corrects the captured image.

[0051] In step S105, the processing unit 14c corrects at least some of the captured images so that the dimensions of the area in which the workpiece 20 is displayed in each captured image match the dimensions of the area in which the workpiece 20 is displayed in an image obtained when the workpiece 20 in a specific posture is captured by the camera 11. The correction of the captured images in step S105 corresponds to pre-processing for appropriately generating a composite image in step S108 described later.

[0052] For example, the processing unit 14c corrects at least some of the captured images so that the dimensions of the area in which the workpiece 20 is displayed in each captured image match the dimensions of the area in which the workpiece 20 is displayed in the captured image P2 captured by the camera 11 of the workpiece 20 in the second posture. In this case, the processing unit 14c performs the above-mentioned correction on the captured image P1 in which the workpiece 20 in the first posture is displayed and the captured image P3 in which the workpiece 20 in the third posture is displayed. On the other hand, the processing unit 14c does not perform the correction on the captured image P2 in which the workpiece 20 in the second posture is displayed. In this way, the above-mentioned specific posture is, for example, one posture among a plurality of different postures that the workpiece 20 can take in steps S102 and S103.

[0053] Fig. 10 is a diagram showing a captured image P1 showing the workpiece 20 in the first attitude and a corresponding corrected image PC1. Fig. 11 is a diagram showing a captured image P3 showing the workpiece 20 in the third attitude and a corresponding corrected image PC3.

[0054] The dimensions of the area in which the workpiece 20 is displayed are different between the captured image P1 in Fig. 7 and the captured image P2 in Fig. 8. Therefore, the processing unit 14c corrects the captured image P1 so that the dimensions of the area in which the workpiece 20 is displayed in the captured image P1 match the dimensions of the area in which the workpiece 20 is displayed in the captured image P2. The image obtained by such correction is the corrected image PC1 in Fig. 10.

[0055] Specifically, the processing unit 14c performs a linear transformation on the coordinates of each pixel in the area where the workpiece 20 is displayed in the captured image P1, thereby matching the dimensions of the area where the workpiece 20 is displayed in the captured image P1 with the dimensions of the area where the workpiece 20 is displayed in the captured image P2. More specifically, the processing unit 14c changes the display position of each pixel in the area where the workpiece 20 is displayed in the captured image P1 to the coordinates after the above-mentioned linear transformation. For example, a transformation matrix used in the above-mentioned linear transformation is set in advance according to the rotation angle of the workpiece 20 when the attitude of the workpiece 20 is changed from the first attitude to the second attitude. Then, the processing unit 14c performs the above-mentioned linear transformation using a transformation matrix corresponding to the rotation angle of the workpiece 20 when the attitude of the workpiece 20 is changed from the first attitude to the second attitude, thereby obtaining the corrected image PC1 of FIG. 10.

[0056] The dimensions of the area in which the workpiece 20 is displayed are different between the captured image P2 in Fig. 8 and the captured image P3 in Fig. 9. Therefore, the processing unit 14c corrects the captured image P3 so that the dimensions of the area in which the workpiece 20 is displayed in the captured image P3 match the dimensions of the area in which the workpiece 20 is displayed in the captured image P2. The image obtained by such correction is the corrected image PC3 in Fig. 11.

[0057] Specifically, the processing unit 14c performs a linear transformation on the coordinates of each pixel in the area where the workpiece 20 is displayed in the captured image P3, thereby matching the dimensions of the area where the workpiece 20 is displayed in the captured image P1 with the dimensions of the area where the workpiece 20 is displayed in the captured image P2. More specifically, the processing unit 14c changes the display position of each pixel in the area where the workpiece 20 is displayed in the captured image P3 to the coordinates after the above-mentioned linear transformation. For example, a transformation matrix used in the above-mentioned linear transformation is set in advance according to the rotation angle of the workpiece 20 when the posture of the workpiece 20 is changed from the second posture to the third posture. Then, the processing unit 14c performs the above-mentioned linear transformation using a transformation matrix corresponding to the rotation angle of the workpiece 20 when the posture of the workpiece 20 is changed from the second posture to the third posture, thereby obtaining the corrected image PC3 of FIG. 11.

[0058] After step S105 in FIG. 3, in step S106, the processing unit 14c specifies a first region of each captured image corresponding to each orientation of the workpiece 20.

[0059] The first region is a region where the luminance exceeds a first threshold. The first threshold is a value large enough to determine that halation is occurring. Therefore, the processing unit 14c can determine that a region where the luminance exceeds the first threshold is a region where halation is occurring.

[0060] As described above, in step S105, the captured image P1 in FIG. 7 is corrected to the corrected image PC1 in FIG. 10, and the captured image P3 in FIG. 9 is corrected to the corrected image PC3 in FIG. 11. Therefore, in step S106, the processing unit 14c specifies the first region for each of the corrected image PC1 in FIG. 10, the captured image P2 in FIG. 8, and the corrected image PC3 in FIG. 11. For example, the processing unit 14c specifies the region R11 in the corrected image PC1 in FIG. 10 as the first region. For example, the processing unit 14c specifies the region R21 and the region R22 in the captured image P2 in FIG. 8 as the first region. For example, the processing unit 14c specifies the region R31 and the region R32 in the corrected image PC3 in FIG. 11 as the first region.

[0061] Following step S106 in FIG. 3, in step S107, the processing unit 14c specifies second regions of the captured images corresponding to each orientation of the workpiece 20.

[0062] The second region is a region where the luminance is below a second threshold. The second threshold is a value smaller than the first threshold and small enough to determine that the region is not illuminated by light. Therefore, the processing unit 14c can determine that a region where the luminance is below the second threshold is a region where light is not illuminated.

[0063] As described above, in step S105, the captured image P1 in Fig. 7 is corrected to the corrected image PC1 in Fig. 10, and the captured image P3 in Fig. 9 is corrected to the corrected image PC3 in Fig. 11. Therefore, in step S107, the processing unit 14c specifies the second region for each of the corrected image PC1 in Fig. 10, the captured image P2 in Fig. 8, and the corrected image PC3 in Fig. 11.

[0064] After step S107 in FIG. 3, in step S108, the processing unit 14c generates a composite image.

[0065] In step S108, the processing unit 14c generates a composite image using a plurality of captured images each corresponding to each posture of the workpiece 20. As described above, in step S105, the captured image P1 in Fig. 7 is corrected to the corrected image PC1 in Fig. 10, and the captured image P3 in Fig. 9 is corrected to the corrected image PC3 in Fig. 11. Therefore, in step S108, the processing unit 14c generates a composite image using each of the corrected image PC1 in Fig. 10, the captured image P2 in Fig. 8, and the corrected image PC3 in Fig. 11.

[0066] FIG. 12 is a diagram showing a composite image PS in which the workpiece 20 is reflected. In step S108, the processing unit 14c generates a composite image PS by excluding the first region specified in step S106 and the second region specified in step S107 from each captured image. For example, the processing unit 14c synthesizes an image obtained by excluding image data of the region R11 from the corrected image PC1 in FIG. 10, an image obtained by excluding image data of the region R21 and the region R22 from the captured image P2 in FIG. 8, and an image obtained by excluding image data of the region R31 and the region R32 from the corrected image PC3 in FIG. 11. Thereby, the composite image PS in FIG. 12 is obtained. Therefore, there is no region in which halation occurs in the composite image PS in FIG. 12. The processing unit 14c may generate the composite image PS by using, for example, an existing algorithm. In generating the composite image PS, the processing unit 14c may average image data for regions overlapping between the captured images, or may preferentially use pixels with the maximum brightness.

[0067] After step S108 in FIG. 3, in step S109, the processing unit 14c detects scratches formed on the surface of the workpiece 20 based on the composite image PS, and the processing flow shown in FIG. 3 ends.

[0068] In step S109, the processing unit 14c detects scratches in the composite image PS, for example, using a learning model constructed by machine learning. For example, the learning model is constructed by preparing a plurality of images showing pseudo scratches in advance and performing supervised learning using the plurality of images as teacher data. By using such a learning model, the processing unit 14c can detect, as a scratch, an area in the composite image PS that is highly likely to be a scratch.

[0069] As described above, in the imaging device 10 according to this embodiment, the control device 14 rotates the workpiece 20 around the rotation axis A2 intersecting the optical axis A1 of the camera 11 relative to the camera 11 and the lighting device 12, thereby changing the posture of the workpiece 20 relative to the camera 11 and the lighting device 12, and obtains a plurality of captured images P1, P2, and P3 of the workpiece 20 in each of a plurality of different postures, respectively, by the camera 11, and generates a composite image PS by combining the plurality of captured images P1, P2, and P3. As a result, a composite image PS in which at least one of an area with excessively high brightness and an area with excessively low brightness is removed can be obtained as an image in which the workpiece 20 is reflected. For example, in the above example, a composite image PS in FIG. 12 in which there is no area in which halation occurs can be obtained. Therefore, the surface of the workpiece 20 can be appropriately inspected.

[0070] In the above, an example has been described in which the control device 14 changes the posture of the workpiece 20 relative to the camera 11 and the lighting device 12 by rotating the workpiece 20 around the rotation axis A2 without rotating the camera 11 and the lighting device 12. However, the control device 14 may change the posture of the workpiece 20 relative to the camera 11 and the lighting device 12 by rotating the camera 11 and the lighting device 12 around the rotation axis A2 without rotating the workpiece 20. In addition, the control device 14 may change the posture of the workpiece 20 relative to the camera 11 and the lighting device 12 by rotating both the workpiece 20, the camera 11, and the lighting device 12 around the rotation axis A2. However, from the viewpoint of preventing the mechanism of the imaging device 10 from becoming complicated or large, it is preferable to change the posture of the workpiece 20 by rotating the workpiece 20 around the rotation axis A2 without rotating the camera 11 and the lighting device 12.

[0071] In the above, an example has been described in which the posture of the workpiece 20 changes to each of the first posture, the second posture, and the third posture. However, the postures that the workpiece 20 can take are not limited to the above example. For example, the control device 14 may change the posture of the workpiece 20 to two or four or more postures, and the camera 11 may capture an image of the workpiece 20 in each posture. In addition, the rotation angle of the workpiece 20 between each posture may be different from the examples of FIG. 4 to FIG. 6. The posture of the workpiece 20 may be changed manually.

[0072] In particular, in the imaging device 10, the control device 14 corrects at least a part of the multiple captured images P1, P2, P3 (the captured images P1, P3 in the above example) before generating the composite image PS so that the dimensions of the area in which the workpiece 20 is displayed in each of the multiple captured images P1, P2, P3 match the dimensions of the area in which the workpiece 20 is displayed in an image (the captured image P2 in the above example) obtained when the workpiece 20 is captured by the camera 11 in a specific posture among the multiple postures that are different from each other. This makes it possible to generate the composite image PS after matching the dimensions of the area in which the workpiece 20 is displayed between the captured images P1, P2, P3 corresponding to each posture. Therefore, the composite image PS can be generated appropriately.

[0073] In the above, an example has been described in which the specific posture is the second posture. However, the specific posture may be a posture other than the second posture. For example, the specific posture may be the first posture or the third posture. For example, the specific posture may be a posture different from any of the first posture, the second posture, and the third posture.

[0074] However, the control device 14 does not need to perform the above correction before generating the composite image PS. For example, when the rotation angle of the workpiece 20 between each posture is small, the composite image PS can be generated without performing the above correction.

[0075] In particular, in the imaging device 10, the control device 14 generates a composite image PS by excluding a first region whose luminance exceeds a first threshold from each of the multiple captured images P1, P2, and P3. This makes it possible to obtain a composite image PS in which the first region, which has excessively high luminance and causes halation, has been removed as an image showing the workpiece 20. In particular, the control device 14 automatically performs the process of excluding the first region from each captured image, thereby reducing the workload of the operator.

[0076] In particular, in the imaging device 10, the control device 14 generates a composite image PS by excluding the second region, whose luminance is below the second threshold, from each of the multiple captured images P1, P2, and P3. This makes it possible to obtain a composite image PS in which the second region, whose luminance is excessively low and not illuminated by light, is removed as an image showing the workpiece 20. In particular, the control device 14 automatically performs the process of excluding the second region from each captured image, thereby reducing the workload of the operator.

[0077] In the above, an example has been described in which the control device 14 generates a composite image PS by removing both the first region and the second region from each captured image. However, the control device 14 may perform a process of removing the first region from each captured image, but may not perform a process of removing the second region from each captured image. In this case, for example, before the generation process of the composite image PS, an operator may manually perform a process of removing the second region from each captured image. Also, the control device 14 may perform a process of removing the second region from each captured image, but may not perform a process of removing the first region from each captured image. In this case, for example, before the generation process of the composite image PS, an operator may manually perform a process of removing the first region from each captured image. Also, the control device 14 may not perform both the process of removing the first region from each captured image and the process of removing the second region from each captured image. In this case, for example, before the generation process of the composite image PS, an operator may manually perform both the process of removing the first region from each captured image and the process of removing the second region from each captured image.

[0078] In particular, in the imaging device 10, the control device 14 detects scratches formed on the surface of the workpiece 20 based on the composite image PS. This allows the control device 14 to automatically perform the process of detecting scratches, thereby reducing the workload of the worker.

[0079] However, the control device 14 does not have to perform a process for detecting scratches formed on the surface of the workpiece 20. In this case, for example, a worker may detect scratches by visually checking the composite image PS.

[0080] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure.

[0081] This disclosure can, for example, contribute to Goal 12 of the Sustainable Development Goals (SDGs), "Ensure sustainable consumption and production patterns." [Explanation of symbols]

[0082] 10. Imaging device 11 Camera 12 Lighting equipment 14 Control device 20 Work A1 Optical axis A2 rotation axis P1 Captured image P2 Captured image P3 Captured image PS composite image

Claims

1. A camera that captures an image of a workpiece having a curved surface; An illumination device that irradiates light onto the workpiece; a control device that changes the posture of the workpiece relative to the camera and the lighting device by rotating the workpiece relative to the camera and the lighting device around a rotation axis that intersects with the optical axis of the camera, acquires a plurality of captured images of the workpiece in each of a plurality of different postures by the camera, and synthesizes the plurality of captured images to generate a composite image; Equipped with Imaging device.

2. Before generating the composite image, the control device corrects at least a portion of the plurality of captured images so that a dimension of an area in which the workpiece is displayed in each of the plurality of captured images matches a dimension of an area in which the workpiece is displayed in an image obtained when the workpiece is captured by the camera in a specific posture among the plurality of postures different from each other. The imaging device according to claim 1 .

3. the control device generates the composite image by excluding a first region, the first region having a luminance higher than a first threshold, from each of the plurality of captured images. The imaging device according to claim 1 .

4. the control device generates the composite image by excluding a second region, in which a luminance is lower than a second threshold, from each of the plurality of captured images. The imaging device according to claim 1 .

5. The control device detects scratches formed on the surface of the workpiece based on the composite image. The imaging device according to claim 1 .

6. The control device changes the posture of the work by rotating the work around the rotation axis without rotating the camera and the lighting device. The imaging device according to any one of claims 1 to 5.

7. A camera that captures an image of a workpiece having a curved surface shape and a lighting device that irradiates light onto the workpiece are rotated around a rotation axis that intersects with an optical axis of the camera, thereby changing the posture of the workpiece relative to the camera and the lighting device; The computer acquires a plurality of captured images obtained by capturing images of the workpiece in each of a plurality of postures different from each other with the camera; The computer synthesizes the plurality of captured images to generate a composite image; Including, Imaging method.

Images