Outer periphery inspection device

Abstract

To provide an outer periphery inspection device that can perform inspection by using an image obtained by correcting luminance unevenness in a circumferential direction of a columnar analyte.SOLUTION: An outer periphery inspection device comprises: an illumination device 4 that irradiates an outer peripheral surface of an analyte; an imaging apparatus 50 that picks up an image of the outer peripheral surface of the analyte 8 divided into four segments; a first mirror set 10 that provides the imaging apparatus 50 with reflected light from a first divided outer peripheral surface of the outer peripheral surface of the analyte 8 divided into four segments; a second mirror set 20 that provides the imaging apparatus 50 with reflected light from a second divided outer peripheral surface of the outer peripheral surface of the analyte 8 divided into four segments; a third mirror set 30 that provides the imaging apparatus 50 with reflected light from a third divided outer peripheral surface of the outer peripheral surface of the analyte 8 divided into four segments; a fourth mirror set 40 that provides the imaging apparatus 50 with reflected light from a fourth divided outer peripheral surface of the outer peripheral surface of the analyte 8 divided into four segments; and a control unit 60 that performs image processing on a photographed image from the imaging apparatus 50. The control unit 60 corrects image information picked up by the imaging apparatus 50 with luminance information in an axial direction and a direction perpendicular to an axis on the basis of predetermined luminance value correction information.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an outer periphery inspection device. More specifically, the present invention relates to an outer periphery inspection device for inspecting the outer periphery of a long cylindrical object to be inspected.

Background Art

[0002] Conventionally, an outer periphery inspection device for inspecting the appearance of the outer peripheral surface of a cylindrical object to be inspected is known (see, for example, Patent Document 1). This outer periphery inspection device includes a plurality of transmission paths each having an incident mirror, a reflection optical system, and an exit mirror, and a single camera that generates an image corresponding to the optical image transmitted through these transmission paths. The plurality of incident mirrors are arranged along the circumferential direction of a first line segment, and the plurality of exit mirrors reflect the optical image toward different regions of the imaging element of the camera, and a configuration is disclosed in which the distances of the plurality of transmission paths are equal. Then, the image generated by the camera is subjected to image plane curvature correction and flattening processing by an image processing unit, and a development view of the cylindrical outer peripheral surface of the object to be inspected is displayed on a display.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the device described in Patent Document 1 above, a plane mirror is used for the incident mirror, the reflection optical system, and the exit mirror. However, when inspecting a cylindrical object using a plane mirror, the amount of light reflected from the surface of the object to be inspected by the lighting device and reaching the imaging element of the camera varies in brightness in the circumferential direction of the cylindrical object to be inspected, and the defect detection accuracy is not uniform. In the device described in Patent Document 1 above, the image processing unit performs image plane curvature correction and flattening processing, but no measures are taken for brightness unevenness.

[0005] The present invention provides an outer periphery inspection apparatus capable of inspecting an image obtained by correcting luminance unevenness in the circumferential direction of a long cylindrical object to be inspected.

Means for Solving the Problem

[0006] The present invention is an outer periphery inspection apparatus for inspecting the outer peripheral surface of a long cylindrical object to be inspected, comprising: an illumination device for irradiating the outer peripheral surface of the object to be inspected; an imaging device for imaging the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to be inspected; a first mirror set for providing reflected light from a first divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to be inspected to the imaging device; a second mirror set for providing reflected light from a second divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to be inspected to the imaging device; a third mirror set for providing reflected light from a third divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to be inspected to the imaging device; a fourth mirror set for providing reflected light from a fourth divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to be inspected to the imaging device; and a control device for performing image processing on a captured image from the imaging device. The control device corrects luminance information in the axial direction and the direction perpendicular to the axis based on predetermined luminance value correction information in the image information captured by the imaging device.

[0007] Further, in the present invention, it is preferable that the illumination device is configured to have at least one of a planar light source having an emission surface arranged in parallel in the axial direction of the object to be inspected and a ring-shaped light source surrounding the outer peripheral surface of the object to be inspected.

[0008] Further, in the present invention, it is preferable that the control device is configured to include an image storage unit for storing the image information, a correction information storage unit for storing the luminance value correction information, and a corrected image information storage unit for storing corrected image information with corrected luminance information.

[0009] In addition, in the present invention, the luminance value correction information is composed of vertical direction luminance value correction information in a direction perpendicular to the axis and axial direction luminance value correction information, the vertical direction luminance value correction information is calculated based on the luminance information in the direction perpendicular to the axis of the photographed image of a good specimen, and the axial direction luminance value correction information is preferably calculated based on the luminance information in the axial direction of the photographed image of a good specimen.

[0010] Also, the luminance value correction information is luminance value correction information for each coordinate (n, m) of the photographed image.

[0011] Further, the cylindrical specimen is a round bar or a steel pipe, and the entire outer circumference can be inspected while the specimen moves.

Advantages of the Invention

[0012] According to the present invention, it is possible to inspect the outer circumference of a long cylindrical specimen without luminance unevenness without depending on the length in the axial length direction of the specimen.

Brief Description of the Drawings

[0013]

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Embodiments for Carrying Out the Invention

[0014] Next, an outer peripheral inspection apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the outer peripheral inspection apparatus according to the present invention is not limited to that shown in the following embodiments, and can be appropriately modified and implemented without changing the gist thereof.

[0015] A first embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic configuration diagram of an outer peripheral inspection apparatus according to a first embodiment of the present invention. As shown in Figure 1, an outer peripheral inspection apparatus 100 for inspecting the outer periphery of a long cylindrical object to be inspected 8 inspects the outer peripheral surface of the long cylindrical object to be inspected 8 conveyed in the axial direction by a conveying means (not shown). The outer peripheral inspection apparatus 100 images the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to be inspected 8 by an imaging device 50. The captured image captured by the imaging device 50 is given to a control device 60, processed by the control device 60, and a developed view of the cylindrical outer peripheral surface of the object to be inspected 8 is displayed on a display device 70. Here, the object to be inspected 8 is a cylindrical long member such as a round bar or a steel pipe material.

[0016] The outer peripheral inspection apparatus according to the first embodiment of the present invention includes four mirror sets: a first mirror set 10, a second mirror set 20, a third mirror set 30, and a fourth mirror set 40, in order to give an optical image of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to be inspected 8 to the imaging device 50. The mirrors of each mirror set are composed of plane mirrors. An optical image of the object to be inspected 8 as seen from the incident mirror side of each mirror set is given to the imaging device 50. The imaging device 50 has an imaging lens and an image sensor, and the optical image of the object to be inspected 8 is given to the image sensor in the imaging device 50.

[0017] The outer peripheral surface of the object to be inspected 8 is irradiated by a plurality of lighting devices 4. In the first embodiment of the present invention, a planar light source composed of white LEDs is used as the lighting device 4. In order to irradiate the outer peripheral surface of the object to be inspected 8 as uniformly as possible, a plurality of lighting devices 4 are arranged so as to cover the periphery of the object to be inspected 8. In each lighting device 4, the light emitting surface of the planar light source is arranged parallel to the axial direction. The arrangement location and number of the lighting devices 4 are appropriately selected according to the outer diameter of the object to be inspected 8 and the like. In the first embodiment shown in Figure 1, six lighting devices 4 composed of planar light sources are arranged so as to cover the periphery of the object to be inspected 8.

[0018] By increasing the number and changing the arrangement of the lighting devices 4, the luminance unevenness on the outer peripheral surface of the object 8 can be improved to some extent, but it is difficult to make the luminance uniform. When the lighting device 4 is a planar light source, even if the number is increased, luminance unevenness will occur on the peripheral surface of the object 8. FIGS. 2 and 3 show a configuration in which ring-shaped light sources 4c are arranged on both axial sides as lighting devices in view of the demerits of planar light sources. When the ring-shaped light sources 4c are used, the luminance unevenness on the outer peripheral surface of the object 8 where the ring-shaped light sources 4c are arranged is eliminated. However, the luminance decreases as the distance from the ring-shaped light source 4c in the axial direction increases, resulting in luminance unevenness.

[0019] Also, when only the ring-shaped light sources 4c are used, if there are defects such as scratches along the axial direction on the object 8, it is difficult to distinguish the light and dark of the reflected light due to the scratches, and it is difficult to discriminate the scratches with the imaging device 50. For this reason, it is preferable to arrange the lighting device 4 composed of a planar light source so as to cover the periphery of the object 8. By arranging it so as to cover the periphery of the object 8, if there are defects such as scratches along the axial direction, the luminance of the defective part becomes low, and it becomes easy to discriminate the defect with the imaging device 50.

[0020] The modification of the first embodiment shown in FIGS. 2 and 3 uses the lighting device 4 composed of a planar light source arranged perpendicular to the axial direction and the ring-shaped light sources 4c to facilitate the discrimination of defects such as scratches and eliminate luminance unevenness. However, even in this modification, it is difficult to eliminate luminance unevenness and make the luminance uniform. For this reason, as will be described later, the present invention performs luminance correction by the control device 60 to eliminate the luminance unevenness of the images of the four-divided outer peripheral surface and display it on the display device 70.

[0021] In the present embodiment, the first mirror set 10 is configured to project the first divided outer peripheral surface (1) of the outer peripheral surface divided into four in the direction orthogonal to the axial direction of the object 8. The first mirror set 10 includes an incident mirror 11 facing the object 8, an exit mirror 15 facing the imaging device 50, and relay mirrors 12, 13, 14 that guide the optical image from the incident mirror 11 to the exit mirror 15.

[0022] The second mirror set 20 is configured to project the second divided outer peripheral surface (2) among the outer peripheral surfaces divided into four in a direction orthogonal to the axial direction of the subject 8. The second mirror set 20 includes an incident mirror 21 facing the subject 8, an exit mirror 25 facing the imaging device 50, and relay mirrors 22, 23, 24 that guide the optical image from the incident mirror 21 to the exit mirror 25.

[0023] The third mirror set 30 is configured to project the third divided outer peripheral surface (3) among the outer peripheral surfaces divided into four in a direction orthogonal to the axial direction of the subject 8. The third mirror set 30 includes an incident mirror 31 facing the subject 8, an exit mirror 15 facing the imaging device 50, and relay mirrors 22, 33, 14 that guide the optical image from the incident mirror 31 to the exit mirror 15. The third mirror set 30 uses the relay mirror 22 as a mirror common to the second mirror set 20 and the exit mirror 15 as a mirror common to the first mirror set 10.

[0024] The fourth mirror set 40 is configured to project the fourth divided outer peripheral surface (4) among the outer peripheral surfaces divided into four in a direction orthogonal to the axial direction of the subject 8. The fourth mirror set 40 includes an incident mirror 41 facing the subject 8, an exit mirror 25 facing the imaging device 50, and relay mirrors 42, 43, 24 that guide the optical image from the incident mirror 41 to the exit mirror 25. The fourth mirror set 40 uses the relay mirror 24 as a mirror common to the second mirror set 20 and the exit mirror 25 as a mirror common to the second mirror set 20.

[0025] The first mirror set 10, the second mirror set 20, the third mirror set 30, and the fourth mirror set 40 are arranged so that the optical path lengths due to the respective mirror arrangements are equal.

[0026] Imaging image information of the outer peripheral surface of the subject 8 divided into four is provided to the control device 60 from the imaging device 50. The control device 60 is configured by, for example, a personal computer (PC) and includes an arithmetic unit 60a and a storage unit 63. The operation of the image processing unit 62 is controlled by a program developed in the program memory 61 in the arithmetic unit 60a.

[0027] The captured image information provided by the imaging device 50 is provided to the storage unit 63. The storage unit 63 includes an image storage unit 63a for storing the captured image information, a correction value information storage unit 63b for storing the luminance value correction information, and a corrected image storage unit 63c for storing the image information obtained by correcting the luminance information. Information stored in the correction value information storage unit 63b and the corrected image storage unit 63c for storing the corrected image information obtained by correcting the luminance information will be described later.

[0028] The image processing unit 62 performs image plane curvature correction and flattening processing on the provided image information. As shown in FIG. 11, the image is developed in the order of the first divided plane image (1), the second divided plane image (2), the third divided plane image (3), and the fourth divided plane image (4) from the top, and is stored in the corrected image storage unit 63c for storing the data after image processing in the storage unit 63. The information is provided to the display device 70, and the developed image is displayed on the display device 70.

[0029] As shown in FIGS. 4 and 10(a), in the image where only the image plane curvature correction and the flattening processing are performed, luminance unevenness occurs in the captured image due to the luminance unevenness on the outer peripheral surface of the subject 8. In this state, it becomes difficult to discriminate defects and the like. Therefore, in the present embodiment, the image processing unit 62 corrects the luminance information of the captured image in order to eliminate the luminance unevenness, and is configured to output a captured image without luminance unevenness to the display device 70.

[0030] Next, the luminance unevenness correction will be described. For the luminance unevenness correction, the luminance information (luminance value) is obtained by the outer peripheral inspection device 100 used for the inspection. The luminance value correction information is calculated based on the obtained luminance information. The luminance information of the captured image is corrected by the calculated luminance value correction information so as to eliminate the luminance unevenness. Hereinafter, an example of the luminance unevenness correction will be described.

[0031] When the peripheral inspection device to be used is configured as the peripheral inspection device 100 shown in FIG. 1, luminance information (luminance value) for correction is obtained using the peripheral inspection device 100 shown in FIG. 1. Further, when the peripheral inspection device to be used is configured as the peripheral inspection device 100 in FIGS. 2 and 3, luminance values for correction are obtained using the peripheral inspection device 100 shown in FIGS. 2 and 3. That is, luminance information (luminance value) for correction is obtained using the configuration of the peripheral inspection device 100 to be used.

[0032] A good product specimen 8 with a uniform surface reflectance is imaged by the imaging device 50 of the peripheral inspection device 100 to obtain a captured image of the outer peripheral surface of the specimen 8. FIG. 4 is a captured image of the outer peripheral surface of a good product. Let the position information in the circumferential direction, which is the direction perpendicular to the axis, be y, and the position information in the axial direction be x. In the present embodiment, the imaging device 50 uses an image sensor with 1280×960 pixels. The axial direction has 1280 pixels, the circumferential direction has 960 pixels, the position information x in the axial direction ranges from 0 to 1280, and the position information y in the circumferential direction ranges from 0 to 960. The luminance value of each pixel is 8 bits and has a luminance value ranging from 0 to 255. Here, a luminance value of 0 is pure black, and a luminance value of 255 is pure white.

[0033] The specimen 8 is irradiated by the illumination device 4 composed of a planar light source with its emission surface arranged in parallel in the axial direction of the specimen 8. Among the reflected light reflected from the surface of the specimen 8, the light with an angle close to specular reflection has the highest luminance. Therefore, as shown in FIG. 4, luminance unevenness occurs. Luminance value correction information, which is a correction coefficient, is obtained to eliminate this luminance unevenness.

[0034] The image processing unit 62 extracts the luminance value of each pixel according to the position information x and y from the captured image data. In the present embodiment, the luminance value used for correction is obtained from the luminance values of each column of the position information x.

[0035] In the present embodiment, a histogram of luminance values is obtained for each column, and the luminance value with the maximum frequency in the histogram is set as the representative luminance value of that column. In this way, the luminance values of each column with respect to the position information y are obtained, and for example, luminance information Fa(y) in the y direction as shown in FIG. 5 is obtained. Here, a represents the x coordinate.

[0036] Subsequently, as shown in FIG. 6, a correction function fa(y) for making Fa(y) a straight line is obtained. fa(y) is calculated by the following formula.

[0037] Fa(y) × fa(y) = B Here, B is a luminance value selected from among luminances (0 to 255). This luminance value is usually a constant value selected within the range of 120 to 150. When the luminance value is about 120 to 150, the defective part appears white or black, so it becomes easy to discriminate the defect.

[0038] The calculated correction function fa(y) is stored in the correction value information storage unit 63b.

[0039] Next, a correction function based on the position information x is calculated.

[0040] The above-described fa(y) is obtained by a function calculated based on the luminance value at which the frequency of the histogram is the maximum value. Since the luminance value of each pixel of the position information x is different from the luminance value at which the frequency is the maximum value, when corrected by the function of fa(y), luminance unevenness occurs in the luminance in the axial direction as shown in FIG. 7.

[0041] The relationship of the luminance information with respect to the position information x is obtained. The luminance information function F(x) in the axial direction (position information x) when corrected by the correction function by the above-described fa(y) is obtained. The function calculated in this way is as shown in FIG. 8. As shown in FIG. 8, there is also luminance unevenness in the axial direction. A correction function f(x) as axial direction luminance value correction information such that the luminance information as shown in FIG. 9 becomes the same is calculated from the luminance information data shown in FIG. 8, and the correction function is stored in the correction value information storage unit 63b.

[0042] The control device 60 stores in advance the correction function f(y) based on the position information y calculated by the above processing and the correction function f(x) based on the position information x in the correction value information storage unit 63b of the storage unit 63.

[0043] In the correction value information storage unit 63b of the outer peripheral inspection device 100, luminance value correction information is stored in advance. The outer peripheral inspection device 100 corrects the luminance information in the axial direction and the direction perpendicular to the axis of the captured image data obtained by performing the image plane curvature correction and the planarization process on the captured image of the subject 8, using the correction function f(x) and the correction function f(y), and causes the display device 70 to display a captured image without luminance unevenness.

[0044] By this correction process, an image without luminance unevenness shown in Fig. 10(b) is obtained from the image with luminance unevenness shown in Fig. 10(a). Thus, discrimination of the outer periphery of the subject 8 becomes easy with the image data without luminance unevenness.

[0045] As described above, the image information captured by the imaging device 50 is stored in the image storage unit 63a of the storage unit 63 in the control device 60 in a time series manner. The image processing unit 62 reads out the image information stored in the image storage unit 63a and corrects the luminance information in the axial direction and the direction perpendicular to the axis with the luminance value correction information stored in the correction value information storage unit 63b. The corrected corrected image information is stored in the corrected image storage unit 63c, and the image information is sent from the corrected image storage unit 63c to the display device 70, and a captured image without luminance unevenness is displayed on the display device 70.

[0046] The control device 60 can determine which position of the subject 8 the image information stored in the storage unit 63 is based on the relative movement speed between the outer peripheral inspection device 100 and the subject 8. Thereby, an inspection result corresponding to the position of the outer periphery of the subject 8 can be obtained.

[0047] Another method of luminance unevenness correction will be described with reference to Figs. 11 to 13. To perform luminance unevenness correction, a captured image of the outer peripheral surface of a good product with a uniform surface reflectance is obtained. Fig. 11 is a captured image of the outer peripheral surface of a good product.

[0048] In this embodiment, the imaging device 50 uses an image sensor with a pixel count of 1280×960. The axial direction has 1280 pixels, and the circumferential direction has 960 pixels. The x-coordinate in the axial direction ranges from 0 to 1280, and the y-coordinate in the circumferential direction ranges from 0 to 960. The luminance value of each pixel is 8 bits and has a luminance value range of 0 to 255. Here, a luminance value of 0 represents pure black, and a luminance value of 255 represents pure white.

[0049] For each pixel from (0,0) to (1280,960) on the image coordinates in FIG. 12, correction image information is obtained, and the luminance value correction information for each obtained pixel is stored in the correction value information storage unit 63b.

[0050] For the good specimen 8, correction image information is selected so that each luminance of each pixel in the captured image becomes the same luminance value. This luminance value is usually a fixed value selected within the range of 120 to 150.

[0051] When the corrected luminance value is about 120 to 150, the defective part appears white or black, making it easier to discriminate defects.

[0052] As shown in FIG. 12, the luminance value correction information for each coordinate (n,m) of the captured image is calculated and stored in the correction value information storage unit 63b. The correction value is calculated for each captured pixel to obtain the corrected image shown in FIG. 13.

[0053] Next, the outer periphery inspection device according to the second embodiment of the present invention will be described with reference to FIG. 14. The outer periphery inspection device 100a according to the second embodiment of the present invention differs from the outer periphery inspection device 100 according to the first embodiment in the mirror configuration, the number of lighting devices, and their arrangement. Since the imaging device 50, the control device 60, and the display device 70 have the same configuration, the description thereof will be omitted here.

[0054] The outer periphery inspection device 100a according to the second embodiment is configured with a mirror set as a two - split reflection optical system. The first mirror set 10a and the second mirror set 20a use the same optical system, and the third mirror set 30a and the fourth mirror set 40a use the same optical system.

[0055] The lighting device has a pair of planar light sources 4a and 4b arranged to face each other with the subject 8 therebetween.

[0056] In the present embodiment, the first mirror set 10a is configured to reflect the first divided outer peripheral surface (1) among the outer peripheral surfaces divided into four in a direction orthogonal to the axial direction of the subject 8. The first mirror set 10a includes an incident mirror 11a facing the subject 8, an exit mirror 13a facing the imaging device 50, and a relay mirror 12a that guides the optical image from the incident mirror 11a to the exit mirror 13a.

[0057] In the present embodiment, the second mirror set 20a is configured to reflect the second divided outer peripheral surface (2) among the outer peripheral surfaces divided into four in a direction orthogonal to the axial direction of the subject 8. The second mirror set 20a uses the same mirror set as the first mirror set 10a.

[0058] In the present embodiment, the third mirror set 30a is configured to reflect the third divided outer peripheral surface (3) among the outer peripheral surfaces divided into four in a direction orthogonal to the axial direction of the subject 8. The third mirror set 30a includes an incident mirror 31a facing the subject 8, an exit mirror 33a facing the imaging device 50, and a relay mirror 32a that guides the optical image from the incident mirror 31a to the exit mirror 13a.

[0059] In the present embodiment, the fourth mirror set 40a is configured to reflect the fourth divided outer peripheral surface (4) among the outer peripheral surfaces divided into four in a direction orthogonal to the axial direction of the subject 8. The fourth mirror set 40a uses the same mirror set as the third mirror set 30a.

[0060] The first mirror set 10a, the second mirror set 20a, the third mirror set 30a, and the fourth mirror set 40a are arranged such that the optical path lengths due to the respective mirror arrangements are equal.

[0061] Image information of the outer peripheral surface of the subject 8 divided into four parts from the imaging device 50 is stored in the image storage unit 63a of the storage unit 63 in the control device 60. The image information stored in the image storage unit 63a is given to the image processing unit 62.

[0062] Based on the given image information, the image processing unit 62 performs image plane curvature correction, flattening processing, and further luminance unevenness correction, and an image without luminance unevenness is displayed on the display device 70. Since the luminance unevenness correction is the same process as in the first embodiment, the explanation is omitted here. In this way, discrimination of the outer periphery of the subject 8 becomes easy with image data without luminance unevenness.

[0063] Similar to the first embodiment, when the illumination device 4 is a planar light source, even if the number is increased, luminance unevenness occurs on the peripheral surface of the subject 8. FIGS. 15 and 16 show a case where a ring-shaped light source 4c is arranged on both sides in the axial direction as the illumination device in view of the demerits of the planar light source. When the ring-shaped light source 4c is used, the luminance unevenness on the outer peripheral surface of the subject 8 where the ring-shaped light source 4c is arranged is eliminated. As the distance from the ring-shaped light source 4c in the axial direction increases, the luminance decreases and luminance unevenness occurs.

[0064] A modification of the second embodiment shown in FIGS. 15 and 16 uses an illumination device 4 composed of a planar light source arranged perpendicular to the axial direction and a ring-shaped light source 4c to facilitate discrimination of defects such as scratches and eliminate luminance unevenness. However, even in this modification, it is difficult to eliminate luminance unevenness and make the luminance uniform. For this reason, as will be described later, in the present invention, the control device 60 performs luminance correction to eliminate the luminance unevenness of the images of the outer peripheral surfaces divided into four parts and display them on the display device 70.

[0065] In this way, based on the image data captured by the imaging device 50, the outer periphery of the long cylindrical subject 8 can be inspected.

Explanation of Signs

[0066] 4: Illumination device 4a, 4b: Planar light source 4c: Ring-shaped light source 8: Subject 10: First mirror set 11: Incident mirror 12: Relay mirror 13: Relay mirror 14: Relay mirror 15: Exit mirror 20: Second mirror set 21: Incident mirror 22: Relay mirror 23: Relay mirror 24: Relay mirror 25: Exit mirror 30: Third mirror set 31: Incident mirror 33: Relay mirror 40: Fourth mirror set 41: Incident mirror 42: Relay mirror 43: Relay mirror 50: Imaging device 60: Control device 61: Image memory 62: Image processing unit 70: Display device 100: Peripheral inspection device

Claims

1. An outer periphery inspection device for inspecting the outer peripheral surface of a long cylindrical object, comprising: an illumination device for irradiating the outer peripheral surface of the object; an imaging device for imaging the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object; a first mirror set for providing reflected light from a first divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to the imaging device; a second mirror set for providing reflected light from a second divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to the imaging device; a third mirror set for providing reflected light from a third divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to the imaging device; a fourth mirror set for providing reflected light from a fourth divided outer peripheral surface of the outer peripheral surface divided into four parts in a direction orthogonal to the axial direction of the object to the imaging device; and a control device for performing image processing on a photographed image from the imaging device, wherein the control device corrects luminance information in the axial direction and the direction perpendicular to the axis based on predetermined luminance value correction information in the image information imaged by the imaging device. The outer periphery inspection device.

2. The outer periphery inspection device according to Claim 1, wherein the illumination device has at least one of a planar light source with an emission surface arranged in parallel in the axial direction of the object and a ring-shaped light source surrounding the outer peripheral surface of the object. The outer periphery inspection device.

3. The outer periphery inspection device according to Claim 1 or 2, wherein the control device includes an image storage unit for storing the image information, a correction information storage unit for storing luminance value correction information, and a corrected image information storage unit for storing corrected image information with corrected luminance information. The outer periphery inspection device.

4. The outer periphery inspection device according to Claim 3, wherein the luminance value correction information consists of vertical direction luminance value correction information in a direction perpendicular to the axis and axial direction luminance value correction information. The vertical direction luminance value correction information is calculated based on luminance information in a direction perpendicular to the axis of a photographed image of a good object, and the axial direction luminance value correction information is calculated based on luminance information in the axial direction of a photographed image of a good object. The outer periphery inspection device.

5. The outer periphery inspection device according to Claim 3, wherein the luminance value correction information is luminance value correction information for each coordinate (n, m) of the photographed image. The outer periphery inspection device.

6. The outer periphery inspection device according to Claim 1 or 2, wherein the cylindrical object is a round bar or a steel pipe, and the outer periphery inspection device inspects the entire circumference of the outer periphery while the object moves.

Images