JP2016212060A - Mirror surface inspecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mirror surface inspection device capable of easily performing the discrimination of a kind of the flaw of the mirror for an object to be inspected whose convex protrusion is a mirror surface and capable of reducing an inspection time and a cost more than ever before.SOLUTION: A mirror surface inspection device 10 projects light of mutually different colors to an inspection object area of a metal rod 40, and includes an illumination part 20 arranged at mutually different arrangement angle and including a first light source 21 and a second light source 22. The mirror surface inspection device 10 includes an imaging part 30 for acquiring a color image by imaging the inspection object area. The mirror surface inspection device 10 includes a flaw type discriminating part 65 for acquiring a difference image based on an original image made from a color image and a background image, and performing a type discrimination of a recess flaw and a scratch type discrimination on the basis of a luminance value on different colors in a pixel value of the pixel belonging to the inspection object area of this different image.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mirror surface inspection apparatus.

  Metal rods used in hydraulic cylinders may have defects such as scratches and dents on the surface, and it is necessary to inspect them before shipping to remove defective products. Conventionally, as a method for inspecting the surface of a metal rod, an inspection method by visual inspection or palpation, or automatic inspection by a computer has been performed. Since the surface of the metal rod is a mirror surface, the inspection method by visual inspection or palpation takes time and labor costs. On the other hand, automatic inspection by a computer can solve these problems.

  In the automatic inspection, a contact method and a non-contact method are known. Since the contact method cannot inspect a wide area at a time, there is a possibility that inspection time may be required and the inspection object may be damaged by contact. On the other hand, the non-contact method is a method of inspecting with light or sound (Non-Patent Document 1 to Non-Patent Document 6).

Saburo Okada, "Development of a free-form surface measurement system using laser image sensing", Kyushu Institute of Technology, 2002 Doctoral Dissertation, 2002 Osamu Hirose, Akira Ishii, “Detection of film surface irregularities using pattern illumination”, Journal of Japan Society for Precision Engineering 66 (7), pp. 1098-1102, 2000. Ihara Yasuyuki, Nakai Koshiro, “Surface Observation with a Halation Microscope”, Proceedings of Society Conference of IEICE 2008 Basics / Boundaries, “51,”-“52,”, 2014. Kazuhiro Kanno, "Study on Automatic Inspection of Used Car Body Parts Using Image Measurement Technology", Intelligent Technology Systems Engineering, Graduate School of Engineering, Fukuoka Institute of Technology, 2013 Doctoral Dissertation, 2014. Mitsuwa Frontech Co., Ltd., “Laser type defect detection device”, https: // www. mitsuwa. co. jp / goods / goods / ld01 / ld01. html, (November 27, 2014) Ryuji Miyagawa, Kiyoshi Shigemori, Kenji Ishimatsu, Masuo Sonoda, Masanori Kaede, Tokunao Takato, Kiichi Okita, Toshihiko Miyashita, Toshiyuki Sasaki, Hiroshi Kubota, Akiyoshi Nakata, "Scratch Detection System for Subaru Astronomical Telescope -", Kumamoto Prefectural Industrial Technology Center research report, No43. 2005.

  In the conventional non-contact method using light, when identifying the type of defect from a single image, a large-scale equipment is required, which is expensive, and the inspection time is long due to the size of the inspection object. Thus, there is a problem that complicated processing and knowledge are required for the image processing for obtaining the result. In addition, the conventional non-contact method using light has a problem that the object surface to be inspected is a curved surface and a mirror surface, so that it is easily affected by reflected light. Further, in the conventional non-contact method using light, since illumination with a single color is performed on the inspection object, it is complicated to determine the unevenness of the defective part.

  The object of the present invention is to solve the above-mentioned problems, and to easily determine the type of the scratch on the mirror surface of the inspection object whose convex curved surface is a mirror surface. An object of the present invention is to provide a specular inspection device that can be reduced.

  In order to solve the above-described problems, the mirror surface inspection apparatus of the present invention projects light of different colors on the inspection target area of the inspection target having a convex curved surface and is arranged at different arrangement angles. An illumination unit including a plurality of illumination light sources, an imaging unit that captures the inspection target region of the inspection object and obtains a color image, and a difference image based on the original image or the background image composed of the color image And obtaining at least one kind of flaws or scratches based on the luminance values of the different colors in the pixel values of the pixels belonging to the inspection target area of the original image or the difference image. And a wound type discriminating unit that performs discrimination.

Further, the illumination unit may have two illumination light sources.
Further, the illumination unit has three illumination light sources, and among the three illumination light sources, an area of the inspection object in which light is regularly reflected by projection from an intermediate illumination light source located in the middle is the inspection object area. And the said imaging part may be arrange | positioned in the space area | region where the light by the projection of the said intermediate illumination light source is specularly reflected from the said test object area | region.

Moreover, it is preferable that the said imaging part is arrange | positioned so that the said test target object may be imaged through between the illumination light sources of the said illumination part.
The inspection object may be a metal rod.

  Advantageous Effects of Invention According to the present invention, it is possible to easily determine the type of scratches on a mirror surface of an inspection object whose convex curved surface is a mirror surface, and it is possible to reduce the detection time and cost compared to the conventional technique. Play.

(A) is a schematic block diagram of the mirror surface inspection apparatus of 1st Embodiment, (b) is explanatory drawing of a test object area | region. Explanatory drawing of the diffuse reflected light of an abrasion. Explanatory drawing of the reflected light of a dent flaw. (A) is explanatory drawing of the original image which image | photographed the test | inspection area | region which has an abrasion and a dent wound, (b) is explanatory drawing of a difference image. Explanatory drawing of arrangement | positioning with respect to the test object of an imaging part. Explanatory drawing of arrangement | positioning with respect to the test object of an illumination part. (A) is a schematic block diagram of the mirror surface inspection apparatus of 2nd Embodiment, (b) is explanatory drawing of a test object area | region. The schematic block diagram of 3rd Embodiment. Explanatory drawing of the reflected light of the dent flaw in the test object area | region of 3rd Embodiment. Explanatory drawing of the original image which imaged the test object area | region which has a dent flaw of 3rd Embodiment. Explanatory drawing of the test object area | region of the modification of 3rd Embodiment.

(First embodiment)
A specular surface inspection apparatus according to a first embodiment embodying the present invention will be described below with reference to FIGS.

As shown in FIG. 1A, the specular inspection apparatus 10 includes an illumination unit 20, an imaging unit 30, a driving unit 50 that rotationally drives the metal rod 40, and an image processing device 60.
The image processing device 60 includes a computer, and includes an interface 61, an original image input unit 62, a background image generation unit 63, a difference image generation unit 64, a wound type determination unit 65, an original image storage unit 66, a background image storage unit 67, and a difference. An image storage unit 68 and a discrimination result storage unit 69 are provided, and a display 70 is connected.

  The metal rod 40 is formed in a cylindrical shape, and its peripheral surface (that is, the surface) is a convex curved surface and is subjected to chrome plating or the like to be a mirror surface. In FIG. 1A and FIG. 2, the metal rod 40 is extended in a direction orthogonal to the paper surface. The metal rod 40 is used for a cylinder such as a hydraulic cylinder and corresponds to an inspection object.

  The illumination unit 20 includes a first light source 21 and a second light source 22 that emit different colors in order to give two colors of illumination to the metal rod (inspection object) 40. In addition, it is preferable to arrange | position the illumination part 20, the imaging part 30, and a test target object in a dark box so that external lights other than the illumination part 20, external lights, such as sunlight, may not be inserted. The first light source 21 and the second light source 22 correspond to illumination light sources. In the present embodiment, the first light source 21 and the second light source 22 are linear light sources, but are not limited to linear light sources, and may be surface light sources or point light sources. In the case of a point light source, it is preferable to arrange a plurality of the light sources in parallel with the axis O of the metal rod 40.

  Further, the first light source 21 and the second light source 22 extend in the same direction as the direction in which the axis O of the metal rod 40 extends, and are arranged so as to be parallel to the metal rod 40. In the present embodiment, the color emitted by the first light source 21 and the second light source 22 is a combination of red and blue, but is not limited to the combination of these colors. For example, red and green or green Or a combination of blue and the like. The first light source 21 and the second light source 22 may be light sources such as LED lights, or the various colors described above by covering the white light source with the above-described gelatin films with various colors or illumination filters. You may perform illumination of. In addition, it is preferable that the light source of each color is sufficiently wider than various scratches of the metal rod 40.

  As shown in FIG. 1B, the projection range of the first light source 21 is set so as to cover the entire surface toward the first light source 21 on the peripheral surface of the metal rod 40. Similarly, the projection range of the second light source 22 is set so as to cover the entire surface toward the first light source 21 on the peripheral surface of the metal rod 40. Therefore, as will be described later, there is a region where incident light from both the first light source 21 and the second light source 22 is projected in an overlapping manner on the peripheral surface of the metal rod 40.

  The projection range of the first light source 21 and the second light source 22 with respect to the metal rod 40 may be such that a region where the incident light from both light sources described above is projected on the circumferential surface of the metal rod 40 exists. What is necessary is just to necessarily project on the whole surface which goes to the light source in the surrounding surface of the metal rod 40.

  The imaging unit 30 is connected to an interface 61 of the image processing device 60, receives a reflected light from an inspection object by illumination of the illumination unit 20, acquires a captured image, and outputs the captured image to the image processing device 60. The imaging unit 30 may be any unit that can capture a color image, and may be, for example, an area image sensor or a line sensor composed of a CCD or a CMOS.

  When the imaging unit 30 is a line sensor, the line sensor is arranged in parallel with the axis O of the metal rod 40. In this case, the length of the line sensor (that is, the length extending in the axial direction of the metal rod 40) does not need to coincide with the entire length of the metal rod 40. / 3 etc. may be sufficient. In this case, a color image may be acquired by sequentially moving the line sensor in the axial direction of the metal rod.

  The arrangement of the imaging unit 30 with respect to the metal rod 40 that is the inspection object is based on a color image obtained in advance from a metal rod that is known to have a dent and an abrasion, as shown in FIG. That is, it is set so that a part having an arrangement angle θ suitable for discrimination of the inspection object) can be imaged. A method for determining the arrangement angle θ will be described later.

  The drive unit 50 is composed of, for example, an electric motor, and rotates the metal rod 40 installed on a bearing or the like (not shown) around the axis O through a speed reduction mechanism (not shown) at a predetermined angle. The entire peripheral surface in the circumferential direction of the metal rod is imaged in total.

  When the imaging unit 30 is a line sensor, the drive unit 50 includes a rotary encoder 52 that detects the rotation speed of the rotating metal rod 40. The rotary encoder 52 may directly detect the rotation speed of the metal rod 40, or may detect the rotation speed of the output shaft of the electric motor and be provided between the rotation speed, the electric motor and the metal rod 40, and the motor. The actual rotation speed of the metal rod 40 may be calculated based on the reduction ratio of the speed reduction mechanism that reduces the rotation speed of the metal rod 40.

  Then, the length in the direction orthogonal to the length direction of the line sensor is determined based on the rotation speed of the metal rod 40 obtained as described above and the scanning speed of the imaging unit 30, thereby obtaining the imaging unit. 30 determines the size of an image of one frame obtained. Note that the captured image (color image) may be either a still image or a moving image.

(Operation of the first embodiment)
Next, the operation of the mirror surface inspection apparatus 10 will be described.
An original image input unit 62 of the image processing apparatus 60 uses an image after performing known preprocessing in image processing on a captured image input from the imaging unit 30 as an original image (color image), and an original image storage unit 66.

The background image generation unit 63 creates a background image (color image) based on the original image stored in the original image storage unit 66, and stores the created background image in the background image storage unit 67.
The creation of the background image does not use the original image obtained from the metal rod 40 of the inspection object, but the background image based on the original image obtained by imaging the metal rod of the same size without scratches and dents. An image (color image) may be created and stored in the background image storage unit 67.

  The difference image generation unit 64 obtains a background difference from the original image stored in the original image storage unit 66 and the background image obtained in advance. This difference image generation is for obtaining a difference image (that is, an inspection object image) in the metal rod 40 in order to obtain an inspection object area except for an area other than the inspection object area. This difference image is a color image.

  The generation of the difference image is not limited to the background difference but may be a known method such as interframe difference. In the background subtraction method described above, a plurality of images as a background are captured in advance by the imaging unit 30, and a background image is prepared by averaging processing. The original image input at that time, the background image, This is a method for obtaining the difference.

  Further, the inter-frame difference is the difference image S1 between the two previous images (a frame and b frame) on the time axis among the original images of three consecutive frames (a, b, and c frames in the imaging order). In this method, after obtaining a difference image S2 between two subsequent images (b frame and c frame) on the time axis, a difference image S3 between the difference images S1 and S2 is obtained. The obtained difference image S3 is stored in the background image storage unit 67.

  Since the circumferential surface (convex curved surface) of the metal rod 40 has a circular cross section, the pair of original images along the X axis with the inspection target region Z0 interposed therebetween as shown in the original image of FIG. The reflection regions ZR and ZB (that is, the peripheral region) having a belt-like shape are generated. Among these, one reflection region ZR is mainly reflected light of the light emission color (for example, red) of the first light source 21, and the other one reflection region ZB is the second light source 22 (for example, blue). The reflected light is the main one. These band-like reflection regions are representative of regions that have not changed other than the inspection target region Z0.

  Note that the reflection region ZR illustrated in FIG. 4A is a portion obtained by imaging the region 40a on the peripheral surface of the metal rod 40 close to the first light source 21 on the metal rod 40 illustrated in FIG. Moreover, the reflective area ZB shown in FIG. 4A is a portion obtained by imaging the area 40b on the circumferential surface of the metal rod 40 close to the second light source 22 on the metal rod 40 shown in FIG. Further, the inspection target area Z0 shown in FIG. 4A is a portion obtained by imaging the area 40c between the areas 40a and 40b on the metal rod 40 shown in FIG. The region 40c is a part of a region where incident light from both the first light source 21 and the second light source 22 is projected in an overlapping manner.

  Further, as shown in the original image of FIG. 4A, when the region 40c of the metal rod 40 has a scratch m or a dent scratch n, a region due to reflected light peculiar to the scratch is present in the inspection target region Z0. appear. In the difference image of FIG. 4B, the images of the reflection areas ZR and ZB disappear, and an image due to the scratch m or the dent flaw remains in the inspection target area Z0.

The reflected light by the scratch m and the dent n will be described.
FIG. 2 is an explanatory diagram in which diffusely reflected light is generated in the case of the scratch m, and FIG. 3 is an explanatory diagram of the reflected light in the case of the concave n. For convenience of explanation, in FIGS. 2 and 3, m and n attached to the scratches and dents in the original image and the difference image are also attached to the scratches and dents formed on the peripheral surface of the metal rod 40. . 2 and 3 both show the peripheral surface of the metal rod 40 as a flat surface instead of a curved surface, and between the region immediately below the first light source 21 and the region directly below the second light source 22. In FIG. 2, the scratch m and the dent flaw n exist and extend in the direction orthogonal to the paper surface (that is, the axial direction of the metal rod 40).

  As shown in FIG. 2, the peripheral surface of the metal rod 40 is finished to be a mirror surface, whereas in the case of the scratch m, it is a semi-mirror surface and is incident from the first light source 21 and the second light source 22. Light is diffusely reflected. Therefore, in the original image and the difference image, the pixel value (that is, the luminance value of the color of each reflected light of the first light source 21 and the second light source 22) of the region (image) where the scratch m exists is not diffusely reflected. It becomes lower than that.

  In this embodiment, the original image and the difference image are color images, and the pixel values have luminance values of RGB, that is, red, green, and blue components. In the present embodiment, the luminance value is a value from 0 to 255. Note that the numerical value range of the luminance value is not limited to 0 to 255, and the number of gradations may be determined according to the amount of information given to the pixel.

Further, as shown in FIG. 3, the surface of the dent flaw n has a portion of a surface having a certain inclination, and light from the first light source 21 and the second light source 22 is reflected on this surface.
In this case, when the dent n extends in the axial direction of the metal rod 40, the incident light from the first light source 21 is not reflected by the one side surface na of the dent n and is reflected on the other side. Reflected on one surface nb. On the other hand, incident light from the second light source 22 is not reflected in the shadow nb on one side surface nb of the dent flaw n, but is reflected on the other side surface na.

In addition, the case where the above-mentioned dent flaw n is extended in the axial direction of the metal rod 40 includes the case where it is parallel to the axis and the case where it is not parallel but oblique.
In such a case, in the region (image) having the dent flaw n, the pixel value in the image in which the reflected light from the surface nb is reflected, the red luminance value of the first light source 21 is higher than the blue luminance value. Get higher. On the other hand, as for the pixel value in the image reflecting the reflected light from the surface na, the blue luminance value of the second light source 22 is higher than the red luminance value.

  FIG. 4A and FIG. 4B are examples of images in the case where the scratch on the upper side is a dent scratch n and the scratch on the lower side is a scratch m. In the figure, the diffusely reflected light due to the scratch m on the lower side is a color in which the red color of the first light source 21 and the blue color of the second light source 22 are mixed together. Show.

  Further, in FIGS. 4A and 4B, the recess n having the surfaces na and nb extends in the axial direction of the metal rod 40. For this reason, it is shown that the red reflected light from the first light source 21 appears on the surface na by the leftward hatching from the top toward the diagonally lower left, and the blue reflected light from the second light source 22 appears on the surface nb. This is indicated by hatching to the right from the top to the lower right.

  Incidentally, the reflection area ZR of FIG. 4A shows that the red reflected light from the first light source 21 appears in the same way by leftward hatching, and the reflection area ZB is the blue reflected light from the second light source 22. In the same way, the right-hand hatching shows that the symbol appears.

Next, the scratch type discriminating unit 65 shown in FIG. 1A includes a red luminance value in a pixel value of a pixel in the difference image (inspection target image) and a first red threshold value set for red. Compare.
Further, the wound type determination unit 65 compares the blue luminance value of the pixel value of the pixel in the difference image (inspection target image) with the first blue threshold value set for blue. A case where at least one of the red luminance value of the first light source 21 and the blue luminance value of the second light source 22 is higher than the threshold is determined as a dent.

  Further, the wound type determination unit 65 compares the red luminance value of the pixel value of the pixel in the difference image (inspection target image) with a preset second red threshold value (<first red threshold value). At the same time, the blue luminance value in the pixel value of the pixel is compared with a preset second blue threshold (<first blue threshold). Then, a region where both the red luminance value of the first light source 21 and the blue luminance value of the second light source 22 are lower than the threshold is determined as an abrasion.

  The second red threshold value and the second blue threshold value are threshold values for determining diffuse reflection, and the brightness value when the reflected light is diffused and when the reflected light is not diffused is obtained by a test or the like, The size of the threshold is set.

  Note that the wound type discriminating unit 65 discriminates the type of the flaw in the inspection target region Z0 of the metal rod 40 from the difference image (inspection target image) image using the determination boundary obtained in advance by linear discriminant analysis. May be. The wound type determination unit 65 displays the determination result of the wound type on the display 70 or stores the determination result in the determination result storage unit 69.

(Determination of the arrangement angle θ of the inspection target area)
Next, a preferred method for determining the arrangement angle θ when arranging the inspection target region in the metal rod 40 will be described with reference to FIGS. 5 and 6.

  When the axis O of the metal rod 40 coincides with the X axis and the direction orthogonal to the X axis is defined as the Y axis so as to be included in the virtual plane H including the X axis, from the Z axis orthogonal to the X axis and the Y axis The imaging unit 30 (for example, an area image sensor) is disposed at a position displaced to the light source side (left side in FIGS. 5 and 6, that is, the −Y direction). In this case, the distance between the imaging unit 30 and the central portion P of the inspection target region of the metal rod 40 is L. Note that the central portion P of the inspection target region is on the optical axis K of the imaging unit 30.

  As shown in FIG. 6, the angle between the axis O of the metal rod 40 and the first light source 21 (the angle between the virtual plane H, hereinafter referred to as the arrangement angle) is θr, and the axis O of the metal rod 40 and the first light source 21 are The angle between the two light sources 22 is defined as θb (arrangement angle).

  As shown in FIG. 5, the position of the inspection target region (that is, the position of the central portion P of the inspection target region of the metal rod 40) on the peripheral surface of the metal rod 40 is an imaginary plane H including the axis O. It is expressed by an arrangement angle θ from

In the state where the imaging unit 30 and the illumination unit 20 are arranged as described above, a metal rod known to have both a dent and a scratch is imaged by the imaging unit.
Next, images of the inspection target region on the peripheral surface of the metal rod are arranged and imaged so as to have a known angle of A to E (θr <A <B <C <D <E <θb). Each time the metal rod 40 is sequentially rotated so that a dent and a scratch (hereinafter simply referred to as a scratch) are positioned at angles A to E with the first light source 21 and the second light source 22 illuminated. A color image captured by the imaging unit 30 including the scratch area is obtained.

Note that the relative positional relationship between the imaging unit 30 and the central portion P of the inspection target region is the same as that when the original image is obtained.
And the 1st light source dent scratch image (namely, image of surface nb) which mainly has the color of the 1st light source 21 in the picked-up image obtained by image pick-up part 30 when a crack is arranged at the angle of A-E, 2nd light source color dent image (namely, image of surface na) mainly having the color of the 2nd light source 22, and the scratch image which has the area | region of the color where the color of the 1st light source 21 and the 2nd light source color intermingled are included. There is something.

  As shown in FIG. 6, the first light source 21 is disposed lower than the second light source 22 when the dent is formed so as to be parallel or intersecting with the X axis (axis O). Since it is located at an angle, it is often reflected on the upper surface side of the groove of the dent scar, and conversely, the lower surface side tends to become a shadow. For this reason, a 1st light source color dent flaw image becomes what has many 1st light source colors attached to the upper surface side of the dent flaw.

  On the other hand, since the second light source 22 has a higher arrangement angle than the first light source 21, the second light source 22 is often reflected on the lower surface side of the groove of the dent and the upper surface side tends to be a shadow. For this reason, in a 2nd light source color dent image, many 2nd light source colors attach to the lower surface side of a dent flaw.

On the other hand, the scratch image has an image in which the emission color of the first light source and the emission color of the second light source are mixed since the scratch is a semi-mirror surface as described above.
In this way, the discrimination boundary is obtained by performing linear discriminant analysis using the background image, the first light source color dent image, the second light source color dent image, and the scratch image for each angle of A to E as training data. .

  In addition, a metal rod having an unknown scratch (that is, a dent scratch, an abrasion) is similarly imaged, and a misclassification rate and a discrimination boundary are obtained with respect to an image obtained using the obtained discrimination boundary. , An angle with a low misclassification rate is set as an appropriate arrangement angle θ. If there is a central portion of the inspection target area having a scratch at this arrangement angle θ, the erroneous determination is minimized, so that it is preferable to take an image when there is a scratch on the metal rod at this arrangement angle.

This embodiment has the following features.
(1) The mirror surface inspection apparatus 10 mutually applies to the inspection object area Z0 of the metal rod 40 (inspection object) having a convex curved surface and the reflection areas ZR and ZB (peripheral areas) adjacent to the inspection object area. The illumination unit 20 includes a first light source 21 and a second light source 22 (a plurality of illumination light sources) that project light of different colors and are arranged at different arrangement angles. Further, the mirror surface inspection apparatus 10 includes an imaging unit 30 that captures the inspection target area Z0 and the reflection areas ZR and ZB (peripheral areas) of the metal rod (inspection target) 40 and acquires a color image. Further, the specular inspection apparatus 10 obtains a difference image based on the original image and the background image that are color images, and based on the luminance values for the different colors in the pixel values of the pixels belonging to the inspection target area Z0 of the difference image. Thus, it has a wound type discriminating section 65 for discriminating the type of dents and scratches.

  As a result, according to the present embodiment, it is possible to easily determine the type of the scratch on the mirror surface of the inspection target object having a convex curved surface, and to reduce the detection time and cost compared to the conventional case. Can do.

  (2) In the mirror surface inspection apparatus 10, the illumination light source of the illumination unit 20 has two light sources, a first light source 21 and a second light source 22. As a result, according to the present embodiment, it is possible to easily determine the type of specular flaws on the inspection object according to the color of light projected by each of the two illumination units, and the detection time and cost can be easily determined. The effect that can be reduced compared to the conventional is exhibited.

  (3) The mirror surface inspection apparatus 10 performs a mirror surface inspection of a metal rod that is an inspection object. As a result, according to the present embodiment, it is possible to easily determine the type of scratch on the peripheral surface (mirror surface) of the metal rod, and it is possible to reduce the detection time and cost as compared with the conventional case.

(Second Embodiment)
Next, the mirror surface inspection apparatus 10 of 2nd Embodiment is demonstrated with reference to Fig.7 (a) and FIG.7 (b). In the following embodiments including this embodiment, the same or corresponding configuration as the first embodiment is applied to the configuration of the mirror inspection device 10 of the first embodiment among the configurations of the mirror inspection device 10. The same reference numerals are assigned to the reference numerals, detailed description thereof is omitted, and different configurations will be described.

  In the first embodiment, as illustrated in FIG. 5, the imaging unit 30 is disposed at a position displaced in the −Y direction from the Z axis, and the first light source 21 and the second light source 22 of the illumination unit 20 are provided. It was further displaced in the same direction. On the other hand, in the second embodiment, as shown in FIGS. 7A and 7B, the optical axis is included in the virtual vertical plane V that passes through the axis O of the metal rod 40 in the imaging unit 30. The first embodiment differs from the first embodiment in that the first light source 21 and the second light source 22 are disposed so as to be disposed and sandwich the imaging unit 30 therebetween. Further, the first light source 21 and the second light source 22 are surface light sources, which is different from the first embodiment. Other configurations are the same as those of the first embodiment.

This embodiment has the following features.
(1) The imaging unit 30 of the mirror surface inspection apparatus 10 is disposed so as to image the metal rod (inspection object) 40 through between the first light source 21 and the second light source 22 of the illumination unit 20. Even if comprised in this way, the mirror surface inspection apparatus 10 of 2nd Embodiment can have an effect similar to 1st Embodiment.

(Third embodiment)
Next, the mirror surface inspection apparatus 10 of 3rd Embodiment is demonstrated with reference to FIGS.
As shown in FIG. 8, in the specular inspection apparatus 10 of the present embodiment, the illumination unit 20 includes a first light source 21, a second light source 22, and a third light source 23 positioned between the two light sources as illumination light sources. ing. In the present embodiment, the colors emitted by the first light source 21, the second light source 22, and the third light source 23 are red, blue, and green, respectively, but are not limited to combinations of these colors. A combination of colors may be used. The third light source 23 corresponds to an intermediate illumination light source.

  The first light source 21, the second light source 22, and the imaging unit 30 are arranged in the same manner as in the second embodiment, and the third light source 23 is an optical axis K of the imaging unit 30 within a range where no vignetting occurs in the imaging unit 30. The third light source 23 is disposed toward the metal rod 40 so that its optical axis is parallel or substantially parallel to the optical axis K of the imaging unit 30.

  As shown in FIG. 8, incident light from the third light source 23 is incident on a region where the incident light of both the first light source 21 and the second light source 22 overlaps and is projected on the peripheral surface of the metal rod 40. Furthermore, the optical axis of each light source is set so as to face the metal rod 40 so as to be projected in an overlapping manner.

  By setting the direction of the optical axis of each light source as described above, a region 40d is set on the peripheral surface of the metal rod 40, and the region 40d is whitened by additive color mixing using the projection light of the three light sources. It is set to be. When the region 40d is set to be white by the projection light from the three light sources, the incident light from the three light sources is wound in a state where white paper is wound around the peripheral surface of the metal rod 40. And the paper on the upper surface of the region 40d may be set so as to be white by three light sources. Further, the region 40d is a region where the incident light projected from the third light source 23 is regularly reflected when the peripheral surface of the metal rod 40 is not damaged. A part of the reflected light that is regularly reflected by the region 40 d is incident on the imaging unit 30. In other words, the imaging unit 30 is disposed in a spatial region in which light generated by the projection of the third light source 23 (intermediate illumination light source) is regularly reflected. In the present embodiment, the image processing apparatus 60 is different in that the difference image generation unit 64 and the difference image storage unit 68 are omitted in the configuration of the first embodiment.

(Operation of the third embodiment)
The operation of the mirror surface inspection apparatus 10 configured as described above will be described.
An original image input unit 62 of the image processing apparatus 60 uses an image after performing known preprocessing in image processing on a captured image input from the imaging unit 30 as an original image (color image), and an original image storage unit 66.

  Since the peripheral surface (convex curved surface) of the metal rod 40 has a circular cross section, the original image has a belt-like shape in the inspection target region Z0 (that is, the portion where the region 40d in FIG. 8 is imaged) as shown in FIG. And two reflective regions ZR and ZB having a band shape with the portion in between.

  Among these, one reflection region ZR is mainly reflected light of the light emission color (for example, red) of the first light source 21, and the other one reflection region ZB is the second light source 22 (for example, blue). The reflected light is the main one. In addition, the inspection target area Z0 is an area that becomes white due to the emission colors of the first light source 21, the second light source 22, and the third light source 23.

  The reflection region ZR is a portion obtained by imaging the region 40a on the peripheral surface of the metal rod 40 close to the first light source 21 on the metal rod 40 shown in FIG. Further, the reflection region ZB is a portion obtained by imaging the region 40b on the peripheral surface of the metal rod 40 close to the second light source 22 on the metal rod 40.

  Further, as shown in the original image of FIG. 10, when the region 40c of the metal rod 40 has a scratch m or a dent scratch n, a region due to reflected light peculiar to the scratch appears in the inspection target region Z0. In the original image of FIG. 10, a reflection area due to the scratch m or the dent flaw appears in the inspection target area Z0.

The reflected light of the reflection area of the dent scratch n and the scratch m will be described.
FIG. 9 is an explanatory diagram of reflected light in the case of a dent flaw. For convenience of explanation, in FIG. 9, n attached to the scratches and dents in the original image is also attached to the dents n formed on the peripheral surface of the metal rod 40. For convenience of explanation, FIG. 9 shows an area 40d immediately below the third light source 23, where the scratch m and the dent flaw exist, and extend in a direction perpendicular to the paper surface (that is, the axial center direction of the metal rod 40). It shall be.

As shown in FIG. 9, the surface of the dent flaw n has a portion of a surface having a certain inclination, and light from the first light source 21 and the second light source 22 is reflected on this surface.
In this case, the incident light from the first light source 21 is not reflected on the surface na on one side of the dent flaw n but reflected on the surface nb on the other side. On the other hand, incident light from the second light source 22 is not reflected in the shadow nb on one side surface nb of the dent flaw n, but is reflected on the other side surface na.

  In such a case, the pixel value in the image in which the reflected light from the surface nb is reflected in the region having the dent flaw n, the red luminance value of the first light source 21 is higher than the blue luminance value. On the other hand, in the pixel value in the image reflecting the reflected light from the surface na, the blue luminance value of the second light source 22 is higher than the red luminance value. Further, since the green regular reflection of the third light source 23 from the surfaces na and nb is little or absent, the green luminance value is low.

  Although not shown, in the case of the scratch m, the peripheral surface of the metal rod 40 is a mirror surface, whereas it is a semi-mirror surface, and the first light source 21, the second light source 22, and the third light source Incident light is diffusely reflected. Therefore, the pixel value of the area where the scratch m is in the original image (that is, the luminance value of the color of each reflected light of the first light source 21, the second light source 22, and the third light source 23) is not diffusely reflected, This is lower than in the case of a white area.

  Next, the wound type determination unit 65 shown in FIG. 8 compares the red luminance value of the pixel value of the pixel in the original image (inspection target image) with the first red threshold value set for red. Further, the wound type determination unit 65 compares the blue luminance value of the pixel value of the pixel in the original image (inspection target image) with the first blue threshold value set for blue. Further, the wound type determination unit 65 compares the green luminance value of the pixel value of the pixel in the original image (inspection target image) with the first green threshold value set for green. For example, when the luminance value range is 0 to 255, the first green threshold is less than 10. Note that the value of the first green threshold is not limited to this value, and may be set as appropriate in order to determine that the green luminance value is small.

  Then, at least one of the red luminance value of the first light source 21 and the blue luminance value of the second light source 22 is higher than the threshold value, and the green color of the third light source 23 is If it is smaller than the first green threshold value, it is determined as a dent flaw. Further, the wound type determination unit 65 compares the red luminance value of the pixel value of the pixel in the original image (inspection target image) with a preset second red threshold value (<first red threshold value). At the same time, the blue luminance value in the pixel value of the pixel is compared with a preset second blue threshold (<first blue threshold). Further, the wound type determination unit 65 compares the green luminance value in the pixel value of the pixel with a preset second green threshold (> first green threshold).

  Note that the second red threshold value, the second blue threshold value, and the second green threshold value in the third embodiment are threshold values for discriminating diffuse reflection, and are luminance values when diffused and not diffused. Is obtained by a test or the like, and the threshold value is set.

  Then, the scratch type discriminating unit 65, when the red luminance value of the first light source 21, the blue luminance value of the second light source 22, and the green luminance value of the third light source 23 are both lower than the threshold value, Assuming that incident light from each light source is scattered, the pixel region is determined as a scratch.

The wound type determination unit 65 displays the determination result of the wound type on the display 70 or stores the determination result in the determination result storage unit 69.
This embodiment has the following features.

  (1) In the mirror surface inspection apparatus 10 of the present embodiment, the illumination unit 20 has three light sources: a first light source 21, a second light source 22, and a third light source 23 as illumination light sources. The third light source 23 is an intermediate illumination light source located between the first light source 21 and the second light source.

  An area of the metal rod (inspection object) 40 in which light is regularly reflected by projection from the three illumination light sources is set as an inspection object area Z0, and the imaging unit 30 starts from the inspection object area Z0 to the third light source 23 (intermediate). (Illumination light source) is arranged in a spatial region where the light reflected by the projection is regularly reflected.

  As a result, according to the present embodiment, in the inspection target area where the light projected by the intermediate illumination light source is specularly reflected, it is possible to easily determine the type of specular scratch on the inspection target, The detection time and cost can be reduced more than before.

In addition, embodiment of this invention is not limited to the said embodiment, You may change as follows.
-In 1st Embodiment and 2nd Embodiment, based on the luminance value about a different color in the pixel value of the pixel which belongs to the inspection object area | region of the difference image by acquiring a difference image in the difference image generation part 64. The dent and scratch are discriminated, but the background image generation unit 63, the difference image generation unit 64, the background image storage unit 67, and the difference image storage unit 68 may be omitted.

  In this case, dents and scratches are discriminated based on the luminance values for different colors in the pixel values of the pixels belonging to the inspection target area of the original image. Even if it does in this way, although the precision falls, the kind classification of a crack can be performed.

  In the embodiment, the inspection object having a convex curved surface is a metal rod, but the inspection object is not limited to a metal rod. Any inspection object having a convex curved surface other than a metal rod may be used as long as the convex curved surface is a mirror surface. For example, it may be an inspection object having a spherical surface.

  The configuration of the third embodiment may be modified as shown in FIG. This modification differs from the third embodiment in that the illumination configuration for the metal rod 40 by the third light source 23 of the illumination unit 20 is epi-illumination.

  In the epi-illumination, the light emitted from the third light source 23 is reflected by a half mirror (semi-transparent mirror) 24 disposed at an angle of 45 degrees with respect to the optical axis of the third light source 23 to irradiate the metal rod 40. The light reflected by the metal rod 40 passes through the half mirror 24 again and enters the imaging unit 30.

Thus, the effect similar to 3rd Embodiment can be show | played also by making the 3rd light source 23 into epi-illumination.
In the embodiment described above, the wound type determination unit 65 of the specular inspection apparatus 10 performs the type determination of the dent and scratches, but may perform only one of the scratches.

DESCRIPTION OF SYMBOLS 10 ... Mirror surface inspection apparatus, 20 ... Illumination part, 1 ... 1st light source (illumination light source),
22 ... 2nd light source (illumination light source),
23. Third light source 23 (illumination light source, intermediate illumination light source),
24 ... Half mirror, 30 ... Imaging unit, 40 ... Metal rod, 50 ... Drive unit,
52 ... Rotary encoder, 60 ... Image processing device,
61 ... Interface, 62 ... Original image input unit, 63 ... Background image generation unit,
64 ... difference image generation unit, 65 ... wound type determination unit, 66 ... original image storage unit,
67 ... Background image storage unit, 68 ... Difference image generation unit, 69 ... Discrimination result storage unit,
70 ... Display,
P: central portion of inspection target region, K: optical axis,
Z0 ... inspection object area, ZR, ZB ... reflection area (peripheral area),
θ, θr, θb: arrangement angles.

Claims (5)

An illumination unit including a plurality of illumination light sources, which projects light of different colors and is arranged at different arrangement angles with respect to the inspection target region of the inspection target having a convex curved surface,
An imaging unit that captures a color image by imaging the inspection target region of the inspection target;
A difference image based on an original image or a background image composed of the color image is obtained, and a dent is formed based on a luminance value for the different color in a pixel value of a pixel belonging to the inspection target area of the original image or the difference image. A specular surface inspection apparatus comprising: a wound type discriminating unit that discriminates at least one of wounds and scratches.   The specular inspection apparatus according to claim 1, wherein the illumination unit includes two illumination light sources. The illumination unit has three illumination light sources,
Of the three illumination light sources, the region of the inspection object in which light is regularly reflected by projection from an intermediate illumination light source located in the middle is defined as the inspection region.
The specular inspection apparatus according to claim 1, wherein the imaging unit is disposed in a spatial region in which light generated by the projection of the intermediate illumination light source is regularly reflected from the inspection target region.   4. The specular inspection apparatus according to claim 1, wherein the imaging unit is disposed so as to image the inspection object through an illumination light source of the illumination unit. 5.   The mirror surface inspection apparatus according to claim 1, wherein the inspection object is a metal rod.