JP2008249397A - Surface inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems having the tendency wherein, in a conventional surface inspection device, an inspection visual field of the surface inspection device is required to be miniaturized greatly when a painted surface is a curved surface, and inspection of a wide range on the painted surface requires a long time, and a heavy load is required in an image processing part of the surface inspection device, to thereby elongate a processing time. <P>SOLUTION: The surface inspection device 1 includes an irradiation part 12 on which a light/dark pattern is formed, for irradiating the painted surface 90 with diffused light having gradation of lightness on a boundary part between a light part and a dark part in the light/dark pattern; a camera 11 for imaging reflected light reflected by the painted surface 90; and an image processing device 50 for detecting a defect 91 on the painted surface 90 by performing image processing of a taken image 80 imaged by an imaging part. The image processing device 50 includes a differential processing part 52 for performing differential processing of the taken image 80, and a binarization processing part 53 for performing binarization processing of the taken image 80 after differential processing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface inspection apparatus for detecting defects on a surface to be inspected, such as a collision occurring on a painted surface.

Conventionally, as a device for inspecting defects such as "bumps" that occur on the painted surface of the body of an automobile, by illuminating the painted surface, imaging the reflected light of the irradiated light, and processing the captured image, An apparatus for detecting a change in brightness occurring in a defective part such as a bump is known.
In this way, when detecting a defective part such as a bump by irradiating the coating surface with light, as the light irradiating the coating surface, diffused light having a uniform brightness within the irradiation range (hereinafter referred to as “diffusion flat light”). Are used) or parallel light is used.
In addition, as shown in Patent Document 1, in order to detect a defective portion such as a bump by irradiating light on the coating surface, a light / dark pattern is also given to the light irradiated on the coating surface.
Japanese Patent Laid-Open No. 11-63959

As described above, for example, when the collision of the coating surface is detected using the diffuse flat light, as shown in FIG. The light applied to the inclined surface of the bump 191 formed on the surface is scattered outward and does not return to the camera 110 disposed above (the locus shown by the dotted line in FIG. 16 is scattered outward). When the painted surface 190 of the portion where the bump 191 is present is imaged by the camera 110, an image can be obtained in which the portion of the bump 191 becomes a dark portion and the other painted surface 190 becomes a bright portion. it can. This
The bump 191 can be detected separately from the other painted surface 190.
However, it is only in the case where the light irradiation range is narrow (that is, the width dimension Wa of the light source 120) that the diffused flat light is irradiated onto the coating surface 190 in this manner, and the collision 191 is appropriately detected. As shown, when the width dimension Wa of the light source 120 is increased to increase the light irradiation range, the detection capability of the hit 191 is reduced.

For example, as shown in FIG. 17, when the light irradiation range is increased by extending the width dimension Wa of the light source 120, the light irradiated from a position away from the bump 191 is reflected by the slope of the bump 191. Is reflected substantially perpendicularly and is incident on the camera 110, that is, the light wraps around the portion where the bump 191 is present from all directions, and the coating surface 190 including the portion of the bump 191 is generally regarded as a bright portion. This makes it difficult to detect the hit 191 as a feature point.
Therefore, when detecting the collision of the paint surface using diffuse flat light, it is necessary to narrow the light irradiation range to make the inspection visual field of the surface inspection device very small, for example, as wide as the paint surface of the body of an automobile. When it is necessary to inspect the range, it takes a long time to inspect the entire range, and it is difficult to complete the inspection within the line conveyor tact of the manufacturing process.

In addition, when detecting a collision on the paint surface using parallel light, it is possible to suppress the light from entering the collision part, so that it is not difficult to detect the collision as in the case of using the flat light described above. However, when the coating surface to be inspected is a curved surface, there is a problem that the inspection visual field of the surface inspection apparatus becomes very small.
That is, as shown in FIG. 18, in the central portion in the light irradiation range by the light source 120, the light irradiated on the coating surface 190 is reflected substantially vertically and enters the camera 110, but is slightly separated from the central portion. The light reflected at the position escapes to the outside (when the coating surface 190 is a convex curved surface) and does not enter the camera 110, so that the specularly reflected reflected light is incident on the camera 110. The range (viewing field) becomes very small.
Thus, when detecting a collision using parallel light, it is necessary to make the inspection field of view of the surface inspection device very small if the coating surface is a curved surface. When inspecting a painted surface with a curved surface over a wide range, it takes a lot of time to inspect the entire range, and it is difficult to finish the inspection within the line conveyor tact of the manufacturing process. It becomes.

Further, in the case of detecting an impact by irradiating the paint surface with light having a bright and dark pattern, for example, when irradiating the paint surface with light having a slit-like light and dark pattern, a stripe shape as shown in FIG. Since the captured image is obtained, the following image processing is performed to detect the collision.
That is, in the case shown in FIG. 19, the bright portions 170a having high brightness and the dark portions 170b having low brightness appear alternately in a line shape, and the bump 191 exists in the region of the bright portion 170a, and the shape of the bump 191. Appears as a dark part 170c.
In this case, the brightness changes abruptly at the boundary between the bright part 170a, the dark part 170b, and the dark part 170c, and image processing is performed so as to detect the hit 191 using the change in brightness.

The image shown in FIG. 20A is an image in which noise is reduced by performing smoothing processing on the captured image obtained by capturing the reflected light of the light having the light and dark pattern irradiated on the painted surface 190 with the camera 110. The bright portion 170a and the dark portion 170b form a line-shaped light / dark pattern, and the shape of the bump 191 exists as the dark portion 170c on the bright portion 170a.
The reflected light on the coating surface 190 is imaged by the camera 110 to obtain the image shown in FIG. 20A, and then the image shown in FIG. 20B is obtained by differentiating the image.
The image after differentiation shown in FIG. 20B is brighter (higher brightness) in the image shown in FIG. 20A where the lightness change is smaller, and darker (lightness is lower in lightness) where the lightness change is larger. )
Specifically, since there is no change in brightness in the bright part 170a, dark part 170b, and dark part 170c in FIG. 20A, the portions corresponding to these parts in FIG. It has been. In addition, the boundary between the bright part 170a and the dark part 170b and the boundary between the bright part 170a and the dark part 170c are shown in white because the change in brightness is abrupt.
The white portion corresponding to the boundary portion between the bright portion 170a and the dark portion 170b is formed in a line shape, and the white portion corresponding to the boundary portion between the bright portion 170a and the dark portion 170c is formed in an annular shape.

In this manner, the image shown in FIG. 20B includes a line-shaped white portion due to the light brightness / darkness pattern and an annular white color portion due to the presence of the bump 191, so The line-shaped white portion is removed by image processing.
The removal of the line-shaped white part is performed based on the difference in shape and size between the line-shaped white part and the annular white part. For example, the line-shaped white part extending in the vertical direction is removed. Then, a process is performed such as removing a white part in which the vertical dimension or the horizontal dimension of the white part exceeds the maximum range of the size of the normally conceivable size.
After that, binarization processing is performed on the image from which the line-shaped white portion has been removed to remove noise remaining on the image, and the white portion appears only in the portion corresponding to the hit 191. An image as shown in FIG. 20C is obtained, and the hit 191 is detected based on the image shown in FIG.

  Thus, conventionally, when detecting defects such as bumps on the coating surface by irradiating light having a light and dark pattern, after performing differential processing on the captured image, a line-like pattern with light light and dark patterns having equivalent lightness is used. Since the white portion and the annular white portion due to the presence of the bump 191 are mixed (the state shown in FIG. 20B), the line-shaped white portion is removed to detect the presence of the bump 191. Therefore, the image processing unit in the surface inspection apparatus has a large burden, and the image processing unit is required to have high image processing capability and the processing time tends to be long. .

  Therefore, in the present invention, it is possible to inspect with high accuracy in a wide inspection visual field even when the surface to be inspected is a curved surface while reducing the burden of image processing in the image processing unit, and a wide range of inspection object surfaces The surface inspection apparatus which can test | inspect in a short time is provided.

The surface inspection apparatus that solves the above problems has the following characteristics.
That is, an irradiation unit that irradiates a surface to be inspected with diffused light having a lightness gradation at a boundary portion between a bright part and a dark part in the light-dark pattern, wherein the light-dark pattern is formed, and the inspection target An image capturing unit that captures reflected light reflected by the surface; and an image processing device that performs image processing on the captured image captured by the image capturing unit to detect a defect on the surface to be inspected. A differentiation processing unit that performs differential processing on the captured image, and a binarization processing unit that performs binarization processing on the captured image after differentiation processing.
In this way, by irradiating the surface to be inspected with diffused light with a bright and dark pattern, the light irradiation range (inspection visual field) is ensured regardless of whether the surface to be inspected is a flat surface or a curved surface. However, it is possible to detect defects such as bumps on the surface to be inspected with high accuracy.
Further, in this surface inspection apparatus, it is not necessary to separate and remove the white portion corresponding to the boundary portion of the light and dark pattern appearing after the differentiation process from the annular white portion due to the presence of the collision, immediately after the differentiation process. By performing the binarization process, the hit 91 can be detected. As a result, the burden of image processing can be reduced as compared with the conventional case, and the inspection processing time can be shortened while suppressing the image processing capability of the image processing apparatus.

According to a second aspect of the present invention, the irradiation unit includes a light source that emits light, a diffusion plate that diffuses the light, and a slit that imparts a gradation pattern with gradation to the diffused light that has passed through the diffusion plate. .
Thereby, it becomes possible to obtain diffused light having a gradation pattern with light and dark with a simple and inexpensive configuration.

Further, as described in claim 3, an irradiation unit that irradiates the surface to be inspected with diffused light that forms a bright and dark pattern;
An imaging unit that images reflected light reflected by the inspection target surface; and an image processing device that detects a defect on the inspection target surface by performing image processing on the captured image captured by the imaging unit, Can image reflected light from the surface to be inspected from a plurality of locations, and the image processing device binarizes the differential processing unit that differentially processes the captured image and the captured image after the differential processing 2 A value processing unit.
Thereby, even if the dark part based on a defective part is located in the boundary part of the bright part and dark part of a light-and-dark pattern among the picked-up images imaged from several places, for example in other captured images The dark part based on the defective part can be expected to be located in the bright part of the light / dark pattern (in the case of the bright part based on the defective part, the dark part of the light / dark pattern), and it is possible to appropriately detect the presence or absence of defects such as bumps. .

According to a fourth aspect of the present invention, the distance between the plurality of imaging positions in the imaging unit is a position where a defect present in an image captured at at least one of the imaging positions does not cover the boundary portion of the light / dark pattern. Set to
Thereby, the dark part based on the defective part in at least one picked-up image is always located in the bright part of the light / dark pattern (in the case of the bright part based on the defective part, the dark part of the light / dark pattern) among the picked-up images picked up from a plurality of locations. Therefore, it is possible to reliably detect the presence or absence of defects such as bumps.

Further, as described in claim 5, an irradiation unit that irradiates the surface to be inspected with diffused light that forms a bright and dark pattern;
An imaging unit that captures reflected light reflected by the surface of the inspection target; and an image processing device that detects a defect on the surface of the inspection target by performing image processing on the captured image captured by the imaging unit; Stroboscopically emits the diffused light, and the imaging unit captures reflected light in synchronization with the stroboscopic light emission of the irradiation unit.
In this way, by configuring the irradiating unit to perform strobe emission that instantaneously emits diffused light and performing imaging by the imaging unit, the duty ratio of energization in the irradiating unit can be reduced, and the irradiation is performed. It is possible to brighten the light emitted by flowing a large current when the portion is caused to emit light. By brightening the light emitted from the irradiating unit, the aperture of the lens of the imaging unit can be reduced, and the subject depth can be increased.
As a result, it is possible for the imaging unit to capture more clearly the light and dark pattern located at a different focus position from the surface to be inspected together with the surface to be inspected. It is possible to detect the portion where the defect exists with high accuracy.

According to another aspect of the present invention, an irradiation unit that irradiates light onto the surface to be inspected, an imaging unit that images reflected light reflected by the surface of the inspection target, and a captured image captured by the imaging unit is subjected to image processing. And an image processing device that detects a defect on the surface to be inspected, and the imaging unit is configured to be able to adjust a focal position at the time of imaging, and the focal position at the time of imaging is shifted from the inspection target surface. Adjust.
This makes it possible to remove from the captured image noise components having a large contrast, such as dust adhering to the surface to be inspected, metallic or mica contained in the paint on the painted surface serving as the surface to be inspected.

According to a seventh aspect of the present invention, the surface to be inspected is a painted surface to which a paint is applied.
Thereby, the presence or absence of defects such as bumps on the painted surface can be detected, and the inspection accuracy of the painted surface can be improved.

According to the present invention, it is possible to detect defects such as bumps on the inspection target surface with high accuracy while ensuring a light irradiation range (inspection visual field) regardless of whether the inspection target surface is a flat surface or a curved surface. It is possible.
In addition, it is possible to reduce the burden of image processing as compared with the conventional case, and it is possible to reduce the inspection processing time while suppressing the image processing capability of the image processing apparatus.

  Next, modes for carrying out the present invention will be described with reference to the accompanying drawings.

The surface inspection apparatus 1 shown in FIG. 1 irradiates a coating surface 90 that is an inspection symmetric surface with light, captures reflected light of the irradiated light, and performs image processing on the captured image, thereby causing defects such as bumps. The inspection head 10 of the surface inspection apparatus 1 is a partial detection device. The inspection head 10 includes an irradiation unit 12 that irradiates light on the coating surface 90, a camera 11 that functions as an imaging unit that images reflected light from the coating surface 90, and a half And a mirror 16.
The irradiation unit 12 includes a light source 13 that is a light emitting unit such as an LED, a diffusion plate 14 that uses light generated by the light source 13 as diffusion light, and a light and dark pattern with gradation on the diffusion light that has passed through the diffusion plate 14. The slit 15 to provide is provided.

  The surface inspection apparatus 1 controls a light source control device 20 that controls light emission of the light source 13 of the irradiation unit 12, a camera controller 30 that controls imaging of the camera 11, and a diaphragm of the lens 18 of the camera 11. A lens aperture control device 40, an image processing device 50 that performs image processing of a captured image captured by the camera 11, a mobile robot 60 that moves the inspection head 10, and the like, and controls the movement of the mobile robot 60. And a robot control panel 61.

The light emitted from the light source 13 of the irradiating unit 12 is diffused by passing through the diffuser plate 14 to become diffused light, and then passes through the slit 15 to thereby diffuse light having a gradation pattern with gradation. Become.
From the irradiating unit 12, diffused light having a gradation pattern with gradation is irradiated in a substantially horizontal direction, and the irradiated light is reflected substantially vertically downward by the half mirror 16, and the coating is performed. The surface 90 is irradiated.
The light applied to the painted surface 90 is reflected substantially vertically upward by the painted surface 90 and is imaged by the camera 11.

As shown in FIG. 2, the captured image 80 of the reflected light of the light irradiated on the coating surface 90 is a vertically striped image in which line-shaped bright portions 80 a and line-shaped dark portions 80 b are alternately arranged. It is light having a light and dark pattern, and the boundary portion 80c between the light portion 80a and the dark portion 80b has a gradation in which the lightness gradually changes from the light portion 80a to the dark portion 80b (or from the dark portion 80b to the light portion 80a). Is formed.
Further, in the center bright portion 80a in the captured image 80, there is a substantially circular defect dark portion 80d caused by the bump 91 existing on the painted surface 90.

Since gradation is formed at the boundary 80c, the lightness gradually changes in the direction from the bright part 80a to the dark part 80b (or from the dark part 80b to the bright part 80a) of the boundary part 80c. In the graph shown in FIG. 2, the curve indicating the change in brightness at the boundary portion 80c between the dark portion 80b and the bright portion 80a is inclined.
On the other hand, the change in brightness at the boundary between the defective dark portion 80d caused by the bump 91 and the surrounding bright portion 80a is abrupt. In the graph shown in FIG. 2, the boundary portion between the defective dark portion 80d and the bright portion 80a is changed. The curve indicating the change in brightness changes almost vertically.

In this way, the captured image 80 captured by the camera 11 is input to the image processing device 50, and the image processing device 50 performs image processing to detect the presence or absence of the hit 91.
The image processing device 50 includes a smoothing processing unit 51 that smoothes the captured image 80, a differential processing unit 52 that performs differential processing on the captured image 80, and a binarization processing unit that performs binarization processing on the captured image 80. 53.

Here, as shown in FIG. 3, when the coating surface 90 is a curved surface, the light irradiated from the irradiation unit 12 is configured as diffused light, so that the inspection visual field in the surface inspection apparatus 1 is configured to be large. Can do.
In other words, for example, when diffuse light is irradiated onto a convex curved surface, each irradiation point in the light irradiation range includes light that wraps around from the outside, so only the light irradiated to the central portion in the light irradiation range In addition, the light radiated to the position away from the center portion is also reflected directly above, so that it can be imaged by the camera 11 and the inspection visual field can be enlarged.

Moreover, as shown in FIG. 4, since the light irradiated to the coating surface 90 is comprised by diffused light and the light and dark pattern is provided, even if it enlarges the irradiation range (inspection visual field) of light The bump 91 can be detected with high accuracy.
That is, for example, when the bump 91 exists in the bright part of the irradiation light, the dark part pattern located on both sides of the bright part is imprinted on the inclined surface of the bump 91 and captured by the camera 11. Since the irradiation light is reflected immediately above the painted surface 90 around the image 91 and is captured by the camera 11, the hitting 91 can be characteristically captured in the captured image 80 (in this example, the bright portion 80 a It can be understood as a defect dark portion 80d existing in the inside).
In FIG. 4, a straight line indicates a path of light emitted from the irradiation unit 12, and a dotted line indicates a path of the dark part 80 b by the slit 15.

  As described above, in the surface inspection apparatus 1, the coating surface 90 is irradiated with diffused light to which a bright and dark pattern is applied. Therefore, regardless of whether the coating surface 90 is a flat surface or a curved surface, It is possible to detect defects such as the bump 91 with high accuracy while securing the irradiation range (inspection visual field).

In the surface inspection apparatus 1 configured as described above, the collision 91 is detected as follows.
First, the irradiation unit 12 irradiates the paint surface 90 with diffused light having a gradation pattern with gradation, and the camera 11 captures the reflected light on the paint surface 90.
FIG. 5 shows a captured image 80 that has not yet undergone image processing. In the captured image 80 of FIG. 5, noise 80e is present in addition to the bright portion 80a, the dark portion 80b, the boundary portion 80c, and the defective dark portion 80d due to the hit 91.

The noise 80e is caused by dust adhering to the painted surface 90, metallic or mica contained in the paint applied to the painted surface 90, and darkness occurs in the bright part 80a and the dark part 80b of the captured image 80. Therefore, the noise 80e appears as a dark part in the bright part 80a, and the noise 80e appears as a bright part in the dark part 80b.
Therefore, in the surface inspection apparatus 1, the captured image 80 captured by the camera 11 is input to the image processing apparatus 50, and the captured image 80 is smoothed by the smoothing processing unit 51 of the image processing apparatus 50. , Noise 80e is removed.
FIG. 6 shows a captured image 80 from which the noise 80e has been removed by performing the smoothing process.

Next, differential processing is performed by the differential processing unit 52 of the image processing device 50 on the captured image 80 on which the smoothing processing shown in FIG. 6 has been performed.
The captured image 80 that has been subjected to the differentiation process appears blacker as the brightness change is smaller in the captured image 80 before the differentiation process, and appears whiter as the brightness change increases.
Therefore, in the case of this example, since the brightness portion 80a and the dark portion 80b before performing the differentiation process do not change in brightness, as shown in FIG. 7, in the captured image 80 after the differentiation process, the light portion 80a. And the part corresponding to the dark part 80b appears in black.

Further, since the boundary portion 80c has a gradual change in brightness, a portion corresponding to the boundary portion 80c appears in an intermediate color (gray) between black and white.
Furthermore, since the defect dark portion 80d based on the bump 91 has no change in brightness, the portion corresponding to the defect dark portion 80d appears black, and the boundary between the defect dark portion 80d and the bright portion 80a has a sharp change in brightness. Therefore, a portion corresponding to the boundary portion appears white.
In this way, in the captured image 80 that has been subjected to the differentiation process, the portion corresponding to the boundary portion 80c appears in gray, and the portion corresponding to the boundary portion between the defect dark portion 80d and the bright portion 80a based on the bump 91 appears in white. Other than that, it appears black.

Next, the binarization processing unit 53 of the image processing device 50 performs binarization processing on the captured image 80 subjected to the differentiation processing, in which each part of the captured image 80 is expressed by either white or black.
In this case, the threshold value of white and black is higher than the brightness of the portion corresponding to the boundary portion 80c (the gray portion in the captured image 80 after the differentiation process), and the defect dark portion 80d based on the bump 91 is obtained. Is set to a value smaller than the brightness of the portion corresponding to the boundary between the light portion 80a and the bright portion 80a (white portion in the captured image 80 after the differentiation process).

  When the binarization process is performed on the captured image 80 that has been subjected to the differentiation process, as shown in FIG. 8, a portion corresponding to the boundary between the defect dark part 80d and the bright part 80a based on the bump 91 appears in white. The other parts (the parts corresponding to the bright part 80a, the dark part 80b, the boundary part 80c, and the dark part 80d) appear black, and correspond to the boundary part between the defective dark part 80d and the bright part 80a appearing white. The presence of the hit 91 can be detected depending on the location.

  As described above, in the surface inspection apparatus 1, the coating surface 90 is irradiated with diffused light having a gradation pattern with gradation, and differential processing is performed on the captured image 80 of the coating surface 90 captured by the camera 11. By performing the binarization process, the hit 91 can be detected.

  Here, when the paint surface is irradiated with light of a light / dark pattern that does not have gradation at the boundary between the bright and dark areas as in the past, the brightness change at the boundary between the light and dark areas of the light / dark pattern is abrupt. In addition, when the captured image is differentiated, a portion corresponding to the boundary portion of the light and dark pattern appears in white, so that a white portion due to the boundary portion of the light and dark pattern and an annular white portion due to the presence of a collision are mixed. Since the white portion due to the boundary portion of the light and dark pattern has the same brightness as the white portion due to the collision and cannot be removed by the binarization processing, the white portion due to the boundary portion of the light and dark pattern is removed before performing the binarization processing. Processing to be removed is required.

However, the surface inspection apparatus 1 can detect the collision 91 by performing the binarization process immediately after the differentiation process as described above, and can reduce the burden of image processing compared to the conventional case. Thus, the inspection processing time can be shortened while suppressing the image processing capability of the image processing apparatus 50.
The surface inspection apparatus 1 can detect the presence or absence of defects such as bumps on the painted surface by making the painted surface of the vehicle body in an automobile an inspection symmetrical surface, and can improve the inspection accuracy of the painted surface.

  Further, the diffused light having a gradation pattern with light and darkness that is applied to the coating surface 90 includes a light source 13 composed of LEDs and the like, a diffuser plate 14 that uses the light generated by the light source 13 as diffused light, Since it is configured to be generated by the irradiating unit 12 including the slit 15 for imparting a light-and-dark pattern with gradation to the diffused light that has passed through the diffusion plate 14, a light-and-dark pattern with gradation can be formed with a simple and inexpensive structure. It is possible to obtain diffused light.

  In the surface inspection apparatus 1 of the present example, the light / dark pattern of the slit 15 is configured as a slit-like pattern in which line-shaped bright portions 80a and dark portions 80b are alternately arranged. A pattern in which the dark parts 80b are arranged in a lattice pattern, a pattern in which the polka dots 80b are dispersed in the ground pattern of the bright parts 80a (or the polka dots of the bright parts 80a are dispersed in the ground pattern of the dark parts 80b), etc. Other patterns may be used, and the pattern shape is not particularly limited.

  Further, in the surface inspection apparatus 1, when the painted surface 90 irradiated with light from the irradiation unit 12 is imaged by the camera 11, the depth of the subject is increased as follows to detect the collision 91. Improvement and stabilization.

  That is, the surface inspection apparatus 1 is configured to irradiate the coating surface 90 with light from the irradiation unit 12 using the half mirror 16, and reaches the camera 11 from the irradiation unit 12 via the coating surface 90. The light path (path indicated by a dotted line in FIG. 1) is longer than the light path (path indicated by a one-dot chain line in FIG. 1) between the camera 11 and the coating surface 90. ing.

Thus, when the distance from the camera 11 to the coating surface 90 is different from the distance to the irradiation unit, and the camera 11 is focused on the coating surface 90, if the subject depth of the camera 11 is shallow, the irradiation unit The 12 slits 15 are not in focus, and the light / dark pattern of the slits 15 cannot be transferred to the camera 11.
In such a state, only the image of the painted surface 90 affected by the diffuse reflection component can be captured, and it is difficult to obtain contrast with other portions of the defective portion such as the bump 91. The defective portion cannot be detected with high accuracy.
On the other hand, when the subject depth of the camera 11 is deep, focusing on the painting surface 90 can bring the subject into focus from the painting surface 90 to the slit 15. As a result, the brightness / darkness pattern of the slit 15 is clearly reflected in the camera 11 and sufficient contrast can be obtained with respect to other portions of the defective portion such as the bump 91. Detection can be performed.

Therefore, in the surface inspection apparatus 1, in order to increase the subject depth, imaging by the camera 11 is performed as follows.
Under the control of the robot control panel 61, the mobile robot 60 moves the inspection head 10 to a location to be imaged on the painted surface 90.
When the mobile robot 60 reaches a place to be imaged, the robot control panel 61 outputs a trigger signal to the light source control device 20.
The light source control device 20 to which the trigger signal is input outputs a light emission command to the light source 13 and simultaneously outputs a trigger signal to the camera controller 30.
The camera controller 30 to which the trigger signal is input outputs an imaging command to the camera 11.

The light source 13 to which the light emission command from the light source control device 20 is input emits light, and the camera 11 to which the imaging command from the camera controller 30 is input operates the shutter to image the reflected light from the coating surface 90.
In this case, the light source 13 emits strobe light that is emitted for a short time with a large amount of light, and the camera 11 performs an imaging operation in synchronization with the light emission operation of the light source 13.
Further, the lens aperture of the lens 11 of the camera 11 is appropriately adjusted by the camera lens aperture device 40 according to the light emission conditions of the light source 13 and the like before the camera 11 starts the imaging operation.
Furthermore, the exposure time of the camera 11 at the time of imaging is appropriately adjusted by the camera controller 30 according to the color of the painted surface 90 and the like.
The captured image captured by the camera 11 is transferred to the image processing apparatus 50, and the image processing is performed on the captured image as described above.

In this way, by configuring the light source 13 to emit light instantaneously and perform imaging by the camera 11, the duty ratio of energization in the light source 13 can be reduced, and a large current is generated when the light source 13 emits light. It is possible to brighten the light emitted by flowing.
By brightening the light emitted from the light source 13, the aperture of the lens 18 of the camera 11 can be reduced, and the depth of the subject can be increased.
Thus, the camera 11 can more clearly capture the bright and dark pattern of the slit 15 together with the paint surface 90, and when the captured image is image-processed, the portion where the bump 91 exists can be detected with high accuracy. Is possible.

  In this example, the case where the light emitted from the irradiating unit 12 with strobe light is diffused light having a gradation with a light and dark pattern with gradation, but the light emitted from the irradiation unit 12 with a light and dark pattern without gradation is described. Even when the diffused light is used, the illuminating unit 12 emits strobe light, and the camera 11 captures reflected light in synchronization with the strobe light emitted from the irradiating unit 12, so that the subject depth of the camera 11 is reduced. It is possible to deepen.

Moreover, in this surface inspection apparatus 1, when the coating surface 90 irradiated with the light from the irradiation part 12 is imaged with the camera 11, when the camera 11 is focused on the coating surface, as shown in FIG. , Noise 80e, 80e,... Caused by dust attached to the paint surface 90, metallic or mica contained in the paint, and the like appear.
If the noise 80e, 80e,... Described above occurs in the captured image, the bright portion 80a and the dark portion 80b of the captured image 80 may be shaded and may be mistaken as a defective portion such as the bump 90. 80e is preferably removed.
Therefore, in the above-described example, the noise 80e is removed by smoothing the captured image. However, the noise 80e can be more reliably removed by configuring the surface inspection apparatus 1 as follows.

That is, as shown in FIG. 9, dust and paint adhered to the painting surface 90 are obtained by shifting the focus of the camera 11 from the painting surface 90 toward the camera 11 by a predetermined distance and imaging the painting surface 90 with the camera 11. It is possible to remove noise 80e components having large contrast such as metallic and mica contained in the captured image.
In this case, the distance for shifting the focus of the camera 11 from the painting surface 11 to the camera 11 side is set to, for example, about 10% to 20% of the distance between the camera 11 and the painting surface 90.

  In addition, the smoothing processing unit 51 of the image processing device 50 performs the smoothing process on the captured image 80 that is captured with the focus shifted from the coating surface 90, so that the noise 80e can be more reliably removed. The accuracy of detecting defects such as the bump 91 can be improved.

  The removal of the noise 80e by shifting the focus of the camera 11 from the coating surface 90 and imaging is applied when imaging the reflected light of the diffused light having a gradation pattern with gradation on the coating surface 90. Needless to say, the present invention can also be applied to imaging diffused light of a bright / dark pattern that does not have gradation, diffused light that does not have a bright / dark pattern, or reflected light of the parallel light on the coating surface 90.

Further, when an image of the coating surface 90 is taken by the surface inspection apparatus 1 shown in FIG. 1, for example, as shown in FIG. 10, the defect dark part 80d based on the bump 91 is a bright part 80a and a dark part 80b of a light / dark pattern. It is difficult to detect the presence of the hit 91 when it is present on the border 90c.
Therefore, the surface inspection apparatus 1 is configured so that the defective dark part 80d existing on the bright part 80a or the dark part 80b of the bright / dark pattern and not on the boundary part 90c can be detected without fail. You can also

That is, the surface inspection apparatus 1 shown in FIG. 11 is provided with a plurality of first cameras 11a and second cameras 11b as cameras 11 that capture an image of the painted surface 90.
The first camera 11a and the second camera 11b are arranged at a predetermined interval in the repetitive direction of the bright part 80a and the dark part 80b of the bright and dark pattern of the irradiation light on the coating surface 90.

  As shown in FIG. 12, the distance W between the first camera 11a and the second camera 11b is obtained when the point of interest N on the paint surface 90 is captured by the first and second cameras 11a and 11b. Either one of the reflected positions N1 and N2 on the slit 15 of the point of interest N is always in the bright portion 15a and dark portion 15b of the slit 15 (that is, the position corresponding to the bright portion 80a of the captured image 80 or the dark portion 80b). The dimension is set to exist at a corresponding position).

  For example, as shown in FIG. 13, the first Po is such that the interval Po between the reflection positions N1 and N2 is the same as the repetition pitch P between the bright portions 15a and the dark portions 15b of the slits 15 arranged alternately. When the interval W between the camera 11a and the second camera 11b is set, both the reflection positions N1 and N2 are located at the boundary portion 15c between the bright portion 15a and the dark portion 15b of the slit 15 (that is, at the boundary portion 80c of the captured image 80). (Corresponding position).

Further, as shown in FIG. 14, the first camera 11a is configured so that the interval Po between the reflection positions N1 and N2 is the same as the width dimension Pa of the bright part 15a or the width part Pb of the dark part 15b in the slit 15. When the interval W between the second camera 11b and the second camera 11b is set, both the reflection positions N1 and N2 correspond to the boundary portion 15c between the bright portion 15a and the dark portion 15b of the slit 15 (that is, the boundary portion 80c of the captured image 80). (The position Po is the same as the width Pa of the bright portion 15a).
In addition, when the width dimension Pa of the bright part 15a of the slit 15 and the width dimension Pb of the dark part 15b are formed to be the same, the width dimension Pa of the bright part 15a and the width dimension Pb of the dark part 15b are respectively the repetitive pitch P. The half dimension (1 / 2P).

Therefore, in the surface inspection apparatus 1 of this example, as described above, the interval Po between the reflection positions N1 and N2 is the same as the repetition pitch P, the width dimension Pa of the bright part 15a, and the width of the dark part 15b. The first camera 11a and the second camera 11b are disposed so as to avoid an interval W that is the same as the dimension Pb.
The first camera 11a and the second camera 11b are arranged so as to avoid the interval W where the interval Po between the reflection positions N1 and N2 is K times the repetition pitch P (K is an integer).

  That is, in the first camera 11a and the second camera 11b, both the reflection positions N1 and N2 correspond to the boundary portion 15c of the bright portion 15a and the dark portion 15b of the slit 15 (that is, the boundary portion 80c of the captured image 80). Is located so as to avoid the interval W that is present at any position, and either one of the reflected positions N1 and N2 is always the bright portion 15a and the dark portion 15b of the slit 15 (that is, the bright portion 80a of the captured image 80). Or a position corresponding to the dark portion 80b).

When the distance from the camera 11 to the coating surface 90 is L1, and the distance from the coating surface 90 to the slit 15 is L2, the interval Po is
Po = (L2 × W) / L1
The distance L1, the distance L2, and the interval W can be obtained by the following equation: the interval Po is the repetition pitch P and K times the repetition pitch P (K is an integer), and the width dimension of the bright portion 15a. It is set not to be the same as Pa and the width dimension Pb of the dark part 15b.

For example, when the width dimension Pa of the bright portion 15a and the width dimension Pb of the dark portion 15b are formed to be the same as each other, the interval Po between the reflection positions N1 and N2 is equal to the repetition pitch P. The size is set to 1/4 or 3/4 (that is, Po = (1/4) P or Po = (3/4) P).
By setting in this way, both the reflection positions N1 and N2 are not located at the boundary 15c between the bright portion 15a and the dark portion 15b of the slit 15, and for example, as shown in FIG. When the defect dark part 80d based on the hit 91 is located at the boundary 80c between the bright part 80a and the dark part 80b in the picked-up image 80 of one camera 11a, the hit 91 in the picked-up image 80 of the other second camera 11b. The defect dark part 80d (or defective bright part) based on the above is located in the bright part 80a (or dark part 80b) (contrast generated on the captured image 80 based on the presence of defects such as the bump 91 is located in the dark part 80b. It ’s bright when you ’re doing).

  In the surface inspection apparatus 1 of this example, the picked-up images 80 and 80 of the painted surface 90 simultaneously picked up by the first camera 11a and the second camera 11b are respectively input to the image processing apparatus 50. In the image processing apparatus 50, After appropriately selecting the captured image 80 on the side where the defective dark portion 80d (or defective bright portion) is located in the bright portion 80a (or dark portion 80b), smoothing processing, differentiation processing, and binarization as described above Image processing such as processing is performed to detect defects such as the bump 91.

In this example, a plurality of first cameras 11 a and second cameras 11 b are used as the camera 11 so as to obtain captured images 80 and 80 captured from a plurality of locations. After imaging the coating surface 90 from a certain location using only the camera, the position of the camera 11 is moved by the mobile robot 60, and the same location on the painting surface 90 is imaged from the location after the movement. It is also possible to obtain the picked-up images 80 and 80 picked up from the points.
In addition, the imaging by the camera 11 is not limited to being performed from two places, and it may be configured to input captured images of the painted surface 90 captured from three or more places to the image processing apparatus 50.

  Thus, in the surface inspection apparatus 1 of this example, since the reflected light from the coating surface 90 is configured to be imaged from a plurality of locations, for example, in one captured image 80, the defect dark part 80d is the bright part 80a. Even if it is located at the boundary 80c between the dark portion 80b and the dark portion 80b, it can be expected that the defective dark portion 80d in the other captured image 80 is located in the bright portion 80a (in the case of a defective bright portion, the dark portion 80b). It is possible to appropriately detect the presence or absence of defects such as.

  In particular, in the surface inspection apparatus 1, the value of the interval W is set so that the defective dark portion 80d existing in the captured image captured at at least one of the imaging positions is located at a location that does not cover the boundary portion 80c of the light / dark pattern. Therefore, the defect dark part 80d in at least one captured image 80 is always located in the bright part 80a (in the case of a defective bright part, the dark part 80b), and the presence or absence of a defect such as the bump 91 is reliably detected. It is possible to do.

It is a block diagram which shows a surface inspection apparatus. It is a figure which shows the picked-up image of the diffused light which has the light and dark pattern with the gradation irradiated from an irradiation part. It is side surface sectional drawing which shows a test | inspection visual field at the time of irradiating a diffused light to the curved coating surface. It is side surface sectional drawing which shows the imaging state with a camera at the time of irradiating the coating surface in the large range with the diffused light to which the pattern of light and dark was provided. It is a figure which shows the picked-up image in which image processing is not yet performed. It is a figure which shows the captured image in which the smoothing process was performed. It is a figure which shows the captured image in which the differentiation process was performed. It is a figure which shows the captured image in which the differentiation process was performed. It is side surface sectional drawing which shows the test | inspection head of the state which shifted the focus of the camera by the predetermined distance from the coating surface to the camera side. It is a figure which shows the picked-up image which exists in the state where the dark part based on the hit | hung was applied to the boundary part of the bright part and dark part of a light-dark pattern. It is a block diagram which shows the surface inspection apparatus of the structure which provided multiple cameras. It is a side view which shows the positional relationship of a 1st camera and a 2nd camera. The first and second cameras are arranged in such a manner that the interval between the reflection positions on the slit of the target point on the paint surface of the first and second cameras is the same as the repetition pitch of the bright and dark portions of the alternately arranged slits. It is a side view which shows the state which set the space | interval of a camera and a 2nd camera. The first camera and the second camera are arranged so that the distance between the reflected positions on the slits of the points of interest on the paint surfaces of the first and second cameras is the same as the width of the bright portion of the alternately arranged slits. It is a side view which shows the state which set the space | interval with 2 cameras. It is a figure which shows the captured image by a 1st camera, and the captured image by a 2nd camera. It is side surface sectional drawing which shows the reflection path | route of the light in the case of detecting the collision of the coating surface using diffuse flat light. It is side surface sectional drawing which shows the light reflection path | route in the case of detecting the collision of the coating surface using the diffused flat light which enlarged the irradiation range. It is side surface sectional drawing which shows the reflection path | route of the light in the case of detecting the collision of the coating surface comprised by a curved surface using parallel light. It is a figure which shows the picked-up image at the time of irradiating the coating surface with the light which has a slit-like light-dark pattern. (A) is the figure which shows the state which performed the smoothing process to the picked-up image obtained by imaging the reflected light of the light which has the light-dark pattern irradiated to the coating surface with a camera, (b) is the imaging of (a) The figure which shows the state which performed the differentiation process with respect to an image, (c) is the figure which shows the state which performed the image process and the binarization process which remove the line-shaped white part with respect to the captured image of (b) It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface inspection apparatus 10 Inspection head 11 Camera 11a Lens 12 Irradiation part 13 Light source 14 Diffusion plate 15 Slit 16 Half mirror 20 Light source control apparatus 30 Camera controller 40 Lens aperture control apparatus 50 Image processing apparatus 51 Smoothing process part 52 Differentiation process part 53 Binarization processing unit 60 Mobile robot 61 Robot control panel 80 Captured image 80a Bright part 80b (bright / dark pattern) Dark part 80c (Bright / dark pattern) Boundary part 80d (bright and dark pattern) Based on) dark part 90 painted surface 91 bump

Claims (7)

A light / dark pattern is formed, and an irradiation unit that irradiates a surface to be inspected with diffused light having a gradation of lightness at a boundary between a light part and a dark part in the light / dark pattern;
An imaging unit that images reflected light reflected by the surface of the inspection object;
An image processing device that detects a defect on the inspection target surface by performing image processing on a captured image captured by the imaging unit;
The image processing apparatus includes a differentiation processing unit that performs differentiation processing on the captured image, and a binarization processing unit that performs binarization processing on the captured image after differentiation processing.
A surface inspection apparatus characterized by that. The irradiation unit includes a light source that emits light, a diffusion plate that diffuses the light, and a slit that imparts a gradation pattern with gradation to the diffused light that has passed through the diffusion plate.
The surface inspection apparatus according to claim 1. An irradiation unit that irradiates the surface to be inspected with diffused light that forms a bright and dark pattern, and
An imaging unit that images reflected light reflected by the surface of the inspection object;
An image processing device that detects a defect on the inspection target surface by performing image processing on a captured image captured by the imaging unit;
The imaging unit can capture reflected light from the surface to be inspected from a plurality of locations,
The image processing apparatus includes a differentiation processing unit that performs differentiation processing on the captured image, and a binarization processing unit that performs binarization processing on the captured image after differentiation processing.
A surface inspection apparatus characterized by that. The distance between a plurality of imaging positions in the imaging unit is
Set so that the defect present in the image captured at at least one of the imaging positions is located in a place that does not cover the boundary of the light and dark pattern.
The surface inspection apparatus according to claim 3. An irradiation unit that irradiates the surface to be inspected with diffused light that forms a bright and dark pattern, and
An imaging unit that images reflected light reflected by the surface of the inspection object;
An image processing device that detects a defect on the inspection target surface by performing image processing on a captured image captured by the imaging unit;
The irradiation unit strobes the diffused light,
The imaging unit performs imaging of reflected light in synchronization with strobe emission in the irradiation unit,
A surface inspection apparatus characterized by that. An irradiation unit for irradiating light on the surface to be inspected;
An imaging unit that images reflected light reflected by the surface of the inspection object;
An image processing device that detects a defect on the inspection target surface by performing image processing on a captured image captured by the imaging unit;
The imaging unit is configured to be capable of adjusting a focal position at the time of imaging, and adjusts the focal position at the time of imaging to a position shifted from the inspection target surface.
A surface inspection apparatus characterized by that. The surface to be inspected is a painted surface to which a paint is applied,
The surface inspection apparatus according to any one of claims 1 to 6, wherein:

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