JP6402082B2 - Surface imaging apparatus, surface inspection apparatus, and surface imaging method - Google Patents

Description

  The present invention relates to a surface imaging device, a surface inspection device, and a surface imaging method for imaging a surface of an inspection object having slopes facing each other like a seat surface against which engine intake and exhaust valves abut.

  2. Description of the Related Art A surface inspection apparatus that irradiates light, detects the amount of reflected light from an object to be inspected, and detects scratches or defects on the surface of the object to be inspected based on the detected amount of light is known.

  For example, in Patent Document 1, a light beam from a light source is irradiated to an outer peripheral surface that is an inspection surface of an object to be inspected through a light irradiating means, and reflected light from the inspection surface is received and received by a light receiving means. An apparatus for detecting a defect existing on a surface to be inspected based on the amount of reflected light is described. Specifically, the light irradiation means includes a hollow rotary shaft, a first flat mirror provided on the central axis of the hollow rotary shaft end, and a synchronous rotation with the first flat mirror provided at a position away from the central axis. And a truncated cone mirror disposed along the circumferential direction coaxially with the hollow rotation axis. Then, the light beam from the light source is reflected by the first plane mirror, the second plane mirror, and the truncated cone mirror through the inside of the hollow rotating shaft, and moves at a constant incident angle while moving in the circumferential direction. The surface to be inspected is configured to be irradiated.

JP 2012-036223 A

  However, in Patent Document 1, since irradiation of light and reception of reflected light are performed by an optical system arranged at the same position, in order to receive reflected light from the inspection surface and obtain a clear image, inspection on the inspection surface is performed. There is room for improvement because it is necessary to accurately position the optical system. In addition, when an actuator for realizing and maintaining this positioning accuracy is used, it is costly, and it is necessary to keep the moving speed of the actuator low in order to perform positioning accurately. There are increasing drawbacks.

  The present invention has been made in consideration of the above facts, and an object of the present invention is to obtain a captured image in which the surface of the inspection object is clearer than other portions.

In order to achieve the above object, a surface imaging device according to the present invention includes a light source that irradiates light to an object to be inspected having opposing slopes capable of entering a part of light reflected on one slope and entering the other slope, A lens that converts light emitted from the light source into diffused light having a predetermined divergence angle and irradiates the object to be inspected, and reflected light that is emitted from the light source and first reflected by the opposing slopes and imaging the inspection object by receiving the each of the illuminated by said further reflecting the reflected light by the other of the inclined surface from the one inclined surface is reflected on the other inclined surface of the object from the light source An imaging unit.

In the surface imaging method according to the present invention, the light irradiated from the light source is determined in advance with respect to an object to be inspected having an opposing slope that allows a part of the light reflected on one slope to be incident on the other slope. The light from the light source is converted into a predetermined diffused light by a lens that irradiates the object to be inspected after being converted to diffused light having a widening angle, and is first irradiated on each of the opposed slopes irradiated from the light source. Each of the reflected light reflected by the light source and the reflected light irradiated from the light source and reflected from the one inclined surface of the inspection object to the other inclined surface and further reflected by the other inclined surface is detected. Is picked up by the image pickup unit that picks up an image of the object to be inspected.

  According to the present invention, light is irradiated by a light source onto an object to be inspected having an opposing slope that allows a part of light reflected on one slope to be incident on the other slope.

Then, in the imaging unit, the reflected light that is irradiated from the light source and first reflected on each of the opposing slopes, and the reflected light that is emitted from the light source, reflected from one slope to the other slope, and further reflected on the other slope the object to be inspected is imaged by receiving each of the reflected light. Thereby, the picked-up image where the surface of the slope of a to-be-inspected object is clear compared with another part can be obtained.

The reflected light that was irradiated from the light source and reflected first on each opposing slope, and the light that was emitted from the light source and reflected from one slope of the object to the other slope and further reflected on the other slope. light guide section for guiding each of the reflected light to the image pickup unit may further comprise a.

Further, by converting the light diffusion angle of a predetermined divergence angle of light emitted from the light source Bei the lens for irradiating the object to be inspected Ete, by irradiating the diffused light to the inspection object, sharper imaging An image can be obtained.

  In addition, by applying a 45 degree slope to the slope of the inspection object, light reflected on one of the inclination faces of the inspection object can be reliably reflected to the other inclination surface, so that a clear captured image is obtained. be able to.

  Further, as the object to be inspected, an annular seat surface with which the intake and exhaust valves of the engine abut can be applied.

  In addition, the shaft portion to be inserted into the stem guide and the shaft portion is arranged so as to be the same distance as the distance between the seat surface and the imaging portion with the shaft portion being inserted into the stem guide, and the imaging surface side of the imaging portion The imaging unit can be easily focused by using a jig having an umbrella part provided with a marking pattern on the imaging unit.

  In order to achieve the above object, a surface inspection apparatus according to the present invention performs image processing for detecting defects on the surface of the object to be inspected based on the surface imaging apparatus and the imaging result of the imaging unit. An image processing unit.

  According to the present invention, the image processing unit performs image processing for detecting defects on the surface of the inspection object based on the imaging result of the imaging unit of the surface imaging device. That is, it is possible to reliably detect defects on the surface of the inspection object by performing image processing by the image processing unit using a captured image that is clearer than the other portions.

  The object to be inspected is an annular seat surface against which the intake and exhaust valves of the engine come into contact, and the image processing unit converts the image of the annular object to be inspected captured by the imaging unit into a rectangular image. Conversion processing to be performed, removal processing to remove noise of the image converted by the conversion processing, and correction processing to perform shading correction on the image from which noise has been removed by the removal processing may be performed. Thus, by converting an annular image into a rectangular image, it becomes possible to remove cutting marks as noise and to narrow down the target of image processing.

  As described above, according to the present invention, there is an effect that a captured image can be obtained with a clearer surface of the inspection object than other portions.

It is a figure which shows schematic structure of the surface inspection apparatus containing the surface imaging device which concerns on this embodiment. (A) is a side view which shows a mode that the light from a light source is each reflected by the two sheet surfaces which oppose, (B) is a figure which shows the mode of reflection when parallel light injects into a sheet surface. FIG. 6C is a diagram showing a state of reflection when wide-angle light is incident on the sheet surface. (A) is a perspective view which shows an example of the jig | tool for valve seat surface imaging, (B) is a perspective view which shows a mode that the jig | tool for valve seat surface imaging was inserted in the engine cylinder head. (A) is a figure which shows a mode that the jig | tool for valve seat surface imaging is inserted in a stem guide, (B) is a figure which shows the state which completed insertion of the jig | tool for valve seat surface imaging in a stem guide. It is a block diagram which shows schematic structure of the control part of the surface inspection apparatus which concerns on this embodiment. (A) shows an example of a picked-up image of a pinhole on the sheet surface, (B) is an enlarged view of (A), (C) shows an example of a picked-up image of a crack on the sheet surface, and (D) shows It is an enlarged view of (C). It is a flowchart which shows an example of the flow of the process performed in the control part of the surface inspection apparatus which concerns on this embodiment. (A) is a side view for explaining how light from a light source is reflected by two opposing sheet surfaces to increase the brightness of the sheet surface, and (B) is a side view showing regular reflection. (C) is a side view showing diffuse reflection in the case of a rough surface (smooth), (D) is a side view showing diffuse reflection in the case of a rough surface (coarse), and (E) is a sheet surface. It is a side view which shows a mode that it is diffusely reflected in the case of a rough surface (smooth), (F) is a side view which shows a mode that it is diffusely reflected when a sheet | seat surface is a rough surface (rough), (G) FIG. 4 is a diagram showing the luminance of a defective portion when the sheet surface is a rough surface (smooth), and (H) is a diagram showing the luminance of the defective portion when the sheet surface is a rough surface (rough). (A) shows an example of a captured image of the sheet surface, (B) shows an example of converting the image of the sheet surface into a rectangular shape, (C) is an enlarged view of the rectangular region of (B), (D) shows an example of a picked-up image obtained by removing noise using a moving average filter, (E) shows an example of a shading image, and (F) shows an example of an image obtained by subtracting a shading image from an original image. . (A) shows an example in which an image subjected to shading correction is converted into an annular image, and (B) is an enlarged view of a defective portion. (A) An arrangement of a camera and a light source in the case where the reflected light from the sheet surface is directly imaged when the inclined surface of the sheet surface is 30 degrees, and (B) is a reflected light from the sheet surface when the inclined surface of the sheet surface is 30 degrees. The arrangement of a camera, a light source, and a half mirror in the case of direct imaging is shown, and (C) is a diagram showing a state in which the camera needs to be close to the sheet surface. (A) shows the case where the angle of the sheet surface is 60 degrees, (B) shows the case where the angle of the sheet surface 22 is 50 degrees, and (C) shows the sheet surface. It is a figure which shows the case where the angle of 22 is 45 degree | times. Applying a ring-shaped light source arranged so that the camera is at the center, reflected light from each facing sheet surface, reflected from one sheet surface to the other sheet surface, and then reflected on the other sheet surface It is a figure which shows the structure which images each reflected light of reflected light with a camera. It is a figure which shows the example which further arrange | positioned the conical mirror so that it might oppose a sheet | seat surface. It is a figure for demonstrating the case where shading correction is performed by the difference, and the case where it performs by division.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a surface inspection apparatus including a surface imaging apparatus according to the present embodiment. In the present embodiment, an example will be described in which a seat surface with which a valve provided in an engine cylinder head into which an engine intake and exhaust valve (hereinafter simply referred to as a valve) is inserted is inspected is used. Further, the sheet surface 22 is conical and will be described as an example of a shape having opposed slopes.

  The surface inspection apparatus 10 includes a surface imaging device 20 having a camera 12 as an imaging unit, a light source 14, a lens 16, and a half mirror 18 as a light guide unit, and a control unit 24 that controls the surface imaging device 20. ing.

  The camera 12 images the sheet surface 22 with which the engine intake and exhaust valves come into contact as an object to be inspected. The sheet surface 22 is a surface formed in a conical shape whose diameter gradually decreases from one to the other, and the camera 12 captures an image from one side of the sheet surface 22. The camera 12 may be provided with a lens for condensing light on the imaging surface side as necessary.

  In the present embodiment, an example in which the seat surface 22 as an object to be inspected has an inclined surface of 45 degrees with respect to a surface orthogonal to the moving direction of the valve will be described. In the following description, the moving direction of the valve will be described as a vertical direction, and a plane orthogonal to the moving direction of the valve will be described as a horizontal plane.

  A half mirror 18 is provided between the camera 12 and the sheet surface 22. As shown in FIG. 1, the light irradiated from the light source 14 is irradiated to the half mirror 18 through the lens 16, and the half mirror 18. Is reflected on the sheet surface 22 of the object to be inspected. At this time, the lens 16 condenses the light so as to irradiate diffused light having an irradiation angle of a predetermined spread angle with respect to the sheet surface 22.

  The light emitted from the light source 14 to the sheet surface 22 is reflected by the sheet surface 22 in the vertical direction and is incident on the camera 12 through the half mirror 18, whereby the camera 12 images the sheet surface.

  In the present embodiment, by irradiating light from the light source 14, the light that has been diffused by the lens 16 is reflected by the half mirror 18 and applied to the sheet surface 22. In addition, since the light irradiated on the sheet surface 22 is diffused by the lens 16, it is reflected in each direction, and part of the light is reflected in the direction of the half mirror 18 and passes through the half mirror 18 to the camera 12. Directly incident. Further, in the present embodiment, since the sheet surface 22 is a 45-degree slope, a part of the sheet surface 22 is reflected in the horizontal direction and incident on the opposite sheet surface 22, as shown in FIG. The light is further reflected in the vertical direction by the facing sheet surface 22 and is incident on the camera 12 via the half mirror 18. That is, the camera 12 reflects the reflected light that is first reflected on each inclined surface of the facing sheet surface 22, and is reflected from the facing one sheet surface 22 to the other sheet surface 22 and further reflected by the other sheet surface 22. The inspected object is imaged by receiving each reflected light of the reflected light.

  In this embodiment, the diffused light is incident on the sheet surface 22, and as shown in FIG. 2B, compared to the case where the parallel light is incident on the sheet surface 22, FIG. As shown in FIG. 2, the minute unevenness on the surface of the object to be inspected is canceled, and the influence (noise) of the unevenness can be reduced.

  Here, the valve seat surface imaging jig used when imaging the surface of the seat surface by the surface inspection apparatus 10 according to the present embodiment will be described. FIG. 3A is a perspective view showing an example of a valve seat surface imaging jig, and FIG. 3B is a perspective view showing a state in which the valve seat surface imaging jig is inserted into the engine cylinder head. 4A is a view showing a state where the valve seat surface imaging jig 30 is inserted into the stem guide 38, and FIG. 4B is a diagram illustrating the insertion of the valve seat surface imaging jig into the stem guide 38. It is a figure which shows the state which carried out.

  The valve seat surface imaging jig 30 is inserted into a stem guide 38 into which a valve is inserted, and is used for focusing of the surface imaging device 20, parameter setting of the camera 12, and the like.

  The valve seat surface imaging jig 30 has a shape similar to a valve, and includes an umbrella portion 32 and a shaft portion 34. The umbrella portion 32 is painted on the imaging surface side to suppress reflection of light such as black. In addition, a marking pattern is provided on the imaging surface side of the umbrella part 32. As the marking pattern, for example, as shown in FIGS. 3A and 3B, a grid-shaped marking pattern can be applied, and focusing can be performed using the imaging result of the marking pattern camera 12. ing. Note that the marking pattern is not limited to a lattice pattern, and marking patterns of other shapes may be applied.

  Further, the umbrella portion 32 has a diameter smaller than the diameter of the seat surface 22, and has a size that allows the entire surface of the seat surface 22 to be imaged when the camera 12 captures an image.

  The shaft portion 34 is provided with a stepped portion 36, and has shafts with different diameters such that the diameter near the umbrella portion 32 is thick and the diameter far from the umbrella portion 32 is thin. In this embodiment, when the valve seat surface imaging jig 30 is inserted into the stem guide 38, the stepped portion 36 is the end of the stem guide 38 (the end of the circular boss processed into the engine cylinder head into which the stem seal is driven). Part) 40. Further, in a state where the stepped portion 36 of the shaft portion 34 is in contact with the end portion 40 of the stem guide 38, the imaging surface side of the umbrella portion 32 and the center position of the seat surface 22 (the dashed line in FIG. 4B). The height is matched. In other words, the valve seat surface imaging jig 30 is configured such that the shaft portion 34 is inserted into the stem guide 38 and the stepped portion 36 is in contact with the end portion 40 of the stem guide 38. The distance between 12 and the distance between the center position of the sheet surface 22 and the camera 12 are the same distance. Accordingly, it is possible to easily focus on the seat surface 22 by focusing using the marking pattern provided on the umbrella portion 32.

  In the present embodiment, when the valve seat surface imaging jig 30 is inserted into the stem guide 38, the stepped portion 36 comes into contact with the end portion 40 of the stem guide 38, and the imaging surface side of the umbrella 32 and the seat Although the height with the center position of the surface 22 is set to coincide, it is not limited to this. For example, by setting the diameter at which the umbrella part 32 abuts on the center position of the sheet surface 22 and abutting the umbrella part 32 and the sheet surface 22, the imaging part side of the umbrella part 32 can be provided without providing the step part 36. You may make the height with the center position of the sheet | seat surface 22 correspond.

  Next, the control unit 24 will be described. FIG. 5 is a block diagram illustrating a schematic configuration of a control unit of the surface inspection apparatus 10 according to the present embodiment.

  As shown in FIG. 5, the control unit 24 is composed of a computer in which a CPU 24A, a ROM 24B, a RAM 24C, and an I / O (input / output interface) 24D are connected to a bus 24E.

  The camera 12 and the light source 14 are connected to the I / O 24D, and the light source 14 emits light under the control of the control unit 24, and the camera 12 is imaged and the surface of the sheet surface 22 is used by using the imaging result of the camera 12. Detect defects. The detection of the defect on the sheet surface detects the defect on the sheet surface 22 by performing various kinds of image processing on the captured image of the camera 12.

  The ROM 24B stores a program for imaging the sheet surface 22 and detecting defects on the surface of the sheet surface based on the imaging result. That is, the CPU 24A develops the program stored in the ROM 24B on the RAM 24C and executes it, whereby the surface defect detection process for the sheet surface 22 is performed. In the present embodiment, by performing surface defect detection processing on the sheet surface 22, pinholes as shown in FIGS. 6A and 6B and cracks as shown in FIGS. 6C and 6D are generated. To detect. 6A shows an example of a captured image of a pinhole on the sheet surface 22, and FIG. 6B is an enlarged view of FIG. FIG. 6C shows an example of a captured image of a crack on the sheet surface 22, and FIG. 6D is an enlarged view of FIG.

  Next, a specific example of the surface defect detection process for the sheet surface 22 performed by the CPU 24A executing the program stored in the ROM 24B of the control unit 24 will be described. FIG. 7 is a flowchart illustrating an example of a flow of processing performed by the control unit 24 of the surface inspection apparatus 10 according to the present embodiment.

  In step 100, the control unit 24 controls the light source 14 and the camera 12 to image the sheet surface 22, and the process proceeds to step 102. That is, by irradiating light from the light source 14, the light that has been diffused by the lens 16 is reflected by the half mirror 18 and is applied to the sheet surface 22. Further, since the light applied to the sheet surface 22 is diffused by the lens 16, it is reflected in each direction as shown in FIG. 1 and FIG. And is directly incident on the camera 12 via the half mirror 18. Strictly speaking, since it is not a mirror surface as shown in FIG. 8B, there are fine irregularities as shown in FIGS. 8C and 8D, and as shown in FIGS. 8E and 8F. The sheet surface 22 is diffusely reflected, and the light directly reflected by the sheet surface 22 is directly incident on the camera 12 by the diffuse reflection. In the present embodiment, since the sheet surface 22 is a 45-degree inclined surface, as shown in FIGS. 1 and 8A, the other part of the sheet surface is reflected and opposed in the horizontal direction. Then, the light is incident on the opposite sheet surface 22 in the vertical direction and is incident on the camera 12 via the half mirror 18. Thereby, the captured image of the sheet surface 22 as shown in FIG. 9A can be acquired. Since the acquired image includes light reflected twice on the sheet surface 22 in addition to the reflected light directly reflected on the sheet surface 22, the sheet surface 22 is brighter and clearer than other portions, and the defect Can be easily detected. That is, with respect to a defect portion such as a scratch on the sheet surface 22, the diffuse reflection component increases as shown in the rough surface (smooth) in FIG. 8E and the rough surface (rough) in FIG. As shown in 8 (G) and (H), the luminance of the image is reduced and the detection of the defect becomes easy.

  In step 102, the control unit 24 converts the captured image into an image and proceeds to step 104. In the image conversion, the image of the annular sheet surface 22 is converted into a rectangular image. For example, FIG. 9B shows an example in which the image of the sheet surface 22 in FIG. 9A is converted into a rectangular shape. Cutting traces at the time of processing the sheet surface 22 are generated in a direction along the circumference of the sheet surface. By making the image of the sheet surface 22 rectangular, the cutting traces are converted into straight lines and removed as noise. Can be made easier. In addition, by using a rectangular shape, it is possible to narrow down a target portion for subsequent image processing.

  In step 104, the control unit 24 removes noise from the converted image and proceeds to step 106. The noise removal uses, for example, a vertically long 1 × 5 moving average filter (a moving average filter that is long in a direction orthogonal to the circumferential direction of the sheet surface 22) to remove the influence of the cutting trace as noise. The image shown in FIG. 9D is obtained by performing noise removal with a moving average filter on the image after the image conversion shown in FIG. 9C (enlarged view of the rectangular region in FIG. 9B). be able to. A known technique can be applied to the image processing for removing noise, and noise may be removed by image processing other than the moving average filter.

  In step 106, the control unit 24 performs shading correction on the image from which noise has been removed, and proceeds to step 108. Thereby, luminance unevenness in the circumferential direction of the sheet surface 22 is corrected. For example, the shading correction is performed using a 211 × 9 (super-long landscape) median filter (a median filter long in the circumferential direction of the sheet surface 22). The shading image shown in FIG. 9E is created by performing processing using a median filter on the image of FIG. 9D, and the shading image (FIG. 9E) is generated from the original image (FIG. 9D). )) Is removed by the difference, the image shown in FIG. 9F can be obtained. Thereby, it becomes possible to make a defect part, such as a pinhole and a crack, clear on an image. For shading correction, a well-known technique can be applied, and image processing using other filters or the like may be applied instead of image processing using a median filter.

  In step 108, the control unit 24 performs image conversion on the shading-corrected image and proceeds to step 110. In the image conversion, a rectangular image is converted into an image of the original annular sheet surface 22. FIG. 10A shows an example of conversion to an annular image. FIG. 10B shows an enlarged view of the defective portion. Note that step 108 is a process performed so that a defect can be easily found visually, and may be omitted.

  In step 110, the control unit 24 measures the defect area using the image that has been subjected to various image processes as described above, and ends the series of processes. In the measurement of the defective area, for example, the presence / absence or size of the defective area is determined using a predetermined threshold value with respect to the pixel value of the image information to detect whether there is a defect. In this embodiment, since the image is reflected on the opposite surface of the sheet surface and the image is captured, if the defect is large, the image may be an image in which the defect is reflected on both of the opposite sheet surfaces 22. Therefore, it can function as a surface inspection device without any problem.

  By the way, in the present embodiment, an example in which the seat surface 22 is a 45-degree inclined surface with respect to a surface (horizontal plane) orthogonal to the valve movement direction has been described. There may be an arrangement in which only the specularly reflected light is imaged without being reflected and the entire sheet surface 22 is observed.

  For example, as shown in FIG. 11A, when the slope of the seat surface 22 is 30 degrees, the camera 12 and the light source 14 are provided on the central axis of the valve insertion hole, and the light emitted from the light source 14 is irradiated. It becomes possible to enter the camera 12 with regular reflection on the sheet surface 22. Further, as shown in FIG. 11B, also when the camera 12, the half mirror 18, and the light source 14 are used, the light irradiated from the light source 14 is reflected by the half mirror 18 to irradiate the sheet surface 22, and the sheet surface The light specularly reflected at 22 can enter the camera 12. However, when the angle of the sheet surface 22 is increased to 45 degrees in the present embodiment, the camera 12 needs to be close to the sheet surface 22 as shown in FIG. End up. Further, there is no space for arranging the beam splitter such as the half mirror 18. The positions of the camera 12 and the light source 14 shown in FIGS. 11A and 11C may be reversed, but the wiring of the light source 14 and the auxiliary jig are reflected in the captured image, and the circular shape of the sheet surface 22 is obtained. This is not preferable because it results in an image with missing parts.

  On the other hand, in this embodiment, the diffused light is incident on the sheet surface 22 so that the light reflected by the facing sheet surface 22 is captured by the camera 12 without being limited to 45 degrees. Thus, the sheet surface 22 can be imaged more clearly than other portions.

  Further, in the present embodiment, when the angle of the sheet surface is 45 degrees or more, if the reflection on the opposite sheet surface 22 is used, the entire periphery of the sheet surface 22 can be imaged at once even with the sheet surface 22 having a tighter angle. It becomes. For example, FIG. 12A shows a case where the angle of the sheet surface 22 is 60 degrees, FIG. 12B shows a case where the angle of the sheet surface 22 is 50 degrees, and FIG. The case where the angle is 45 degrees is shown. In these cases, since the incident light and the reflected light to the camera 12 are in a symmetrical relationship, a beam splitter such as the half mirror 18 is required. However, the beam splitter can be omitted by utilizing diffusion on the reflecting surface. The camera 12 and the light source 14 can be disposed at a position away from the sheet surface 22 when the angle of the sheet surface 22 is close to 45 degrees. However, when the angle of the sheet surface 22 becomes tight, it is necessary to be disposed close to the sheet surface 22. , It will no longer be physically valid. That is, as in the present embodiment, when the sheet surface 22 is 45 degrees, it is necessary to dispose the camera 12 and the light source 14 at infinity when only specular reflection light is considered. However, in reality, if the reflecting surface is not a perfect mirror surface, the reflected light has a certain amount of scattered light components while having a peak in the direction of specular reflection. By doing so, the sheet surface 22 can be observed.

  In the above embodiment, the sheet surface 22 provided on the engine cylinder head is described as an example of the inspection object, but the inspection object is not limited thereto. The object to be inspected may be any object as long as the opposing surface is inclined and the light reflected by one inclined surface has an inclined surface that can enter the other inclined surface.

  In the above embodiment, the same operation as in the above embodiment can be obtained even if a position opposite to the position of the camera 12 and the position of the light source 14 is applied.

  In the above embodiment, the half mirror 18 is provided. However, the present invention is not limited to this. For example, a beam splitter may be applied instead of the half mirror 18. Alternatively, the half mirror 18 is omitted and, as shown in FIG. 13, the reflection first reflected from the respective sheet surfaces 22 facing each other by applying the ring-shaped light source 14 arranged so that the camera 12 is at the center. The camera 12 may be configured to capture light and reflected light reflected from the one sheet surface 22 to the other sheet surface 22 and then reflected from the other sheet surface 22.

  In the above embodiment, the light irradiated from the light source 14 is converted into diffused light having a predetermined divergence angle by the lens 16 to irradiate the object to be inspected. However, the present invention is not limited to this. Although the sharpness of the image is inferior to that of the diffused light, for example, the sheet surface 22 may be imaged by irradiating the inspection object with parallel light. Alternatively, as shown in FIG. 14, a conical mirror 50 may be further provided. In FIG. 14, the conical mirror 50 is disposed so as to face the sheet surface 22, and the light from the light source 14 is uniformly irradiated onto the sheet surface 22. Thereby, the reflected light in which the light from the light source 14 is directly reflected by the sheet surface 22 and the reflected light reflected twice by the sheet surface 22 and the conical mirror 50 are incident on the camera 12. Even with this configuration, the captured image on the sheet surface 22 becomes clearer than the other portions, as in the above-described embodiment.

  In the above embodiment, when shading correction is performed in step 106, the shading image is subtracted from the original image, but the original image may be divided by the shading image instead of the difference. For example, as shown in FIG. 15A, when there is a defect or a spot on the substrate, the luminance changes depending on the brightness of the surroundings, as shown in FIG. 15B. When shading correction is performed with a difference as in the above embodiment, the darkness of defects and blots varies depending on the ambient brightness, so that defects and blots cannot be distinguished with a single threshold. For example, as shown in FIG. 15 (B), if the ratio of the captured brightness is base: stain: defect = 5: 3: 1, when shading correction is performed with a difference, FIG. 15 (C) As shown, the brightness of defects and spots varies depending on the ambient brightness. On the other hand, in the case of division, as shown in FIG. 15D, since the darkness of defects and blots is constant regardless of the surrounding brightness, the defects and blots can be distinguished by a single threshold value. become.

  Moreover, although the process of FIG. 7 performed by the control part 24 in each said embodiment was demonstrated as a software process performed when a computer runs a program, it is good also as a process performed by hardware. Alternatively, the processing may be a combination of both software and hardware. Further, a program for processing performed by software may be stored in various storage media and distributed.

  Furthermore, the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Surface inspection apparatus 12 Camera 14 Light source 16 Lens 18 Half mirror 20 Surface imaging device 22 Sheet surface 30 Valve seat surface imaging jig 32 Umbrella part 34 Shaft part 36 Step part 40 End part

Claims (8)

A light source that irradiates a test object having an opposing slope that allows a part of the light reflected on one slope to be incident on the other slope;
A lens that converts the light emitted from the light source into diffused light having a predetermined spread angle and irradiates the inspection object;
Reflected light that is irradiated from the light source and first reflected on the opposing slopes, and the other slope that is irradiated from the light source and reflected from the one slope to the other slope. An imaging unit for imaging the inspection object by receiving each of the reflected light further reflected by
A surface imaging device comprising:   Reflected light that is irradiated from the light source and first reflected on the opposing slopes, and the other slope that is irradiated from the light source and reflected from the one slope to the other slope. The surface imaging device according to claim 1, further comprising a light guide unit configured to guide each of the reflected light further reflected by the imaging unit to the imaging unit.   The surface imaging apparatus according to claim 1, wherein the slope of the inspection object is a 45-degree slope.   The surface imaging device according to any one of claims 1 to 3, wherein the object to be inspected is an annular seat surface with which engine intake and exhaust valves abut.   A shaft portion that is inserted into the stem guide, and is disposed on the shaft portion so as to be the same distance as the distance between the sheet surface and the imaging portion in a state in which the shaft portion is inserted into the stem guide, and the imaging of the imaging portion The surface imaging apparatus according to claim 4, wherein the imaging unit is focused using a jig having an umbrella part provided with a marking pattern on the surface side. A part of the light reflected by one slope is converted into diffused light having a predetermined spread angle by converting the light emitted from the light source to an inspection object having an opposing slope that can enter the other slope. By irradiating by converting the light from the light source into a predetermined diffused light by a lens that irradiates the inspection object,
  Reflected light that is irradiated from the light source and first reflected on the opposing slopes, and the other slope that is irradiated from the light source and reflected from the one slope to the other slope. A surface imaging method in which each of the reflected light further reflected in step (b) is received by an imaging unit that images the inspection object, and the inspection object is imaged.   The surface imaging device according to any one of claims 1 to 5,
  An image processing unit that performs image processing for detecting defects on the surface of the inspection object based on the imaging result of the imaging unit;
  Surface inspection device with The object to be inspected is an annular seat surface with which the engine intake and exhaust valves abut,
A conversion process in which the image processing unit converts an annular image of the inspection object imaged by the imaging unit into a rectangular image; a removal process to remove noise in the image converted by the conversion process; and The surface inspection apparatus according to claim 7, wherein correction processing is performed to perform shading correction on an image from which noise has been removed by the removal processing .