JP3271549B2 - Surface inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface inspection apparatus for inspecting a surface of an object to be inspected, for example, a surface defect such as unevenness on a painted surface of an automobile body.

[0002]

2. Description of the Related Art As a conventional surface inspection apparatus, for example,
There is one disclosed in JP-A-64-38638.

The surface inspection apparatus disclosed in the above publication forms a band of light on the surface to be inspected, moves the band of light on the surface to be inspected, records the reflected image continuously and stepwise, and makes a final image. Specifically, the recording of these partial images is edited into an entire image, and a defect on the surface to be inspected and coordinate information of the defect are output.

[0004]

However, the conventional surface inspection apparatus as described above has the following problems.

For example, in a defect inspection of a painted surface of an automobile body (body), a reflection direction of a light band (light band) changes in accordance with a curvature in a curved surface region of the body, so that the reflected image is always displayed on a video camera. It is necessary to perform control such that the image is displayed on an image center, and since the curved surface of the vehicle body differs for each part or vehicle type, the above-described control becomes more complicated.

The detection of a defect utilizes the fact that it appears as a change in the contour of an image in a dark part or a light band in a reflection image of a light band. However, there is no method or apparatus for automatically detecting the defect. Not established.

In addition, the types of coating defects that occur in the current automatic coating line include not only general irregularities such as dust spot defects (defects with a relatively high angle) but also irregular defects with a gentle angle. At present, it is very difficult to detect these defects simultaneously.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to automatically and accurately detect a surface defect even when a surface to be inspected is a complicated curved surface. A surface inspection apparatus capable of detecting not only general irregularities such as dust spot defects (defects having a relatively high angle) but also irregularities having a gentle angle such as cissing at the same time. It is in.

[0009]

A surface inspection apparatus according to a first aspect of the present invention irradiates a surface to be inspected of an object to be inspected with light,
A surface inspection apparatus that forms a light-receiving image based on light reflected from a surface to be inspected and detects a defect existing on the surface to be inspected based on the light-receiving image. An illumination means including a light source disposed on the surface to be inspected and forming a predetermined light and dark pattern on the surface to be inspected; and a plurality of illumination units arranged and fixed in a gate shape surrounding the object to be inspected and based on the reflected light from the surface to be inspected. Imaging means for forming a light-receiving image of the object, a conveying means for conveying the object to be inspected at a predetermined speed, and an imaging means for obtaining the object to be inspected when the object to be inspected passes through a region surrounded by the illumination means and the imaging means. Inspection processing means for detecting a defect on the surface to be inspected based on the received light image and outputting the detection information, wherein the inspection processing means is configured to detect a spatial frequency component in the image information of the received light image obtained by the imaging means. Of which Image processing means for extracting only the above high frequency components, and the moving amount and moving direction of the object to be inspected and predetermined conditions based on temporally different image information processed by the image processing means and imaged by the same imaging means. Tracing processing means for tracing and detecting matching image information in the image processing means, wherein the image processing means performs an edge detection process on the image information having a light and dark pattern obtained by the imaging means and has a predetermined luminance level or more. Threshold value calculating means for performing a predetermined calculation based on a physical quantity related to an edge luminance level in the processed image information subjected to the edge detection processing to calculate a threshold value in order to extract only the component of the edge detection processing; A second calculation of performing a predetermined calculation based on a physical quantity related to noise generated in the image information to calculate a threshold value;
Threshold value calculating means, and a binarizing processing means for performing a binarizing process based on each of the threshold values calculated by the first and second threshold value calculating means. I have. Further, the surface inspection apparatus according to claim 2 of the present invention irradiates light to the surface to be inspected of the object to be inspected, forms a light receiving image based on the reflected light from the surface to be inspected, and forms the light receiving image based on the light receiving image. What is claimed is: 1. A surface inspection apparatus for detecting a defect present on a surface to be inspected, comprising: a light source arranged in a gate shape surrounding an object to be inspected; and an illumination means for forming a predetermined light and dark pattern on the surface to be inspected. Imaging means for forming a plurality of light-receiving images based on reflected light from the surface to be inspected, fixedly arranged in a portal shape surrounding the object to be inspected, and conveying means for conveying the object to be inspected at a predetermined speed And an inspection process for detecting a defect on a surface to be inspected based on a received light image obtained by the imaging unit and outputting detection information when the inspection object passes through an area surrounded by the illumination unit and the imaging unit. Means, and the inspection processing means comprises: Image processing means for simultaneously extracting high frequency components of a predetermined level or more corresponding to a plurality of types of light and dark patterns among spatial frequency components in image information of a received light image obtained by an imaging means; and processing by the image processing means. Tracking processing means for tracking and detecting image information that coincides with the movement amount and movement direction of the inspected object under predetermined conditions from temporally different image information captured by the same imaging means, and The image processing means performs edge detection processing on the image information having the light and dark pattern obtained by the imaging means, and extracts an edge luminance level in the processed image information subjected to the edge detection processing so as to extract only a component having a predetermined luminance level or more. First threshold value calculating means for performing a predetermined calculation based on the physical quantity to calculate a threshold value; A second threshold value calculating means for performing a predetermined operation based on a physical quantity relating to noise generated in the image information to calculate a threshold value; and a respective threshold value calculated by the first and second threshold value calculating means. And a binarization processing means for performing a binarization process based on the threshold value.

[0010] The surface inspection apparatus according to claim 3 of the present invention comprises:
The image pickup means is constituted by a plurality of CCDD cameras.

[0011]

[0012]

[0013]

A surface inspection apparatus according to a fourth aspect of the present invention comprises:
In the image information having a plurality of types of light and dark pattern areas obtained by the imaging means,
Calculating the pitch width of the light and dark pattern, comparing it with a predetermined value, and a binarized region determining means for determining which region of the plurality of types of light and dark patterns is included in the light and dark pattern,
A divided binary type in which each of the threshold values calculated by the first and second threshold value calculating means is applied to the divided area determined by the binarized area determining means and the binarization processing is performed simultaneously. And a conversion processing means.

[0015] The surface inspection apparatus according to claim 5 of the present invention comprises:
The binarization processing unit calculates a pitch width of the light and dark pattern in image information having a plurality of types of light and dark patterns and a non-inspection surface area obtained by the imaging unit, compares the pitch width with a plurality of predetermined values, and A binarized region determining unit that determines which region the pattern is included in, and the first and second threshold value calculating units calculate the divided regions determined by the binarized region determining unit. Each of the threshold values and the predetermined threshold value for the non-inspection surface area are applied to perform a binarization process at the same time.

A surface inspection apparatus according to a sixth aspect of the present invention comprises:
An inspection start / end determination unit configured to start the inspection when the object to be inspected starts passing through an area surrounded by the illumination unit and the imaging unit and to end the inspection when the inspection object has passed the inspection unit; And a movement amount measuring means for measuring a movement amount of the object to be inspected based on the inspection start time determined by the inspection start / end determination means, and obtained by the inspection start / end determination means and the movement amount measuring means. The position of the image information detected by the tracking processing means on the surface to be inspected is calculated based on the information, and the calculation result is displayed on a developed view of the object to be inspected.

A surface inspection apparatus according to a seventh aspect of the present invention comprises:
The developed view of the object to be inspected is drawn based on the mounting angle and the angle of view of the imaging unit with respect to the object to be inspected.

The surface inspection apparatus according to claim 8 of the present invention comprises:
A light diffusion sheet having a predetermined light / dark pattern is provided between the light source and the object to be inspected such that light from the light source of the illuminating means is irradiated on the surface to be inspected as surface illumination by diffused light of a light / dark pattern. It has a configuration.

According to a ninth aspect of the present invention, there is provided a surface inspection apparatus comprising:
The light-dark pattern formed on the light diffusion sheet is a composite light-dark stripe pattern having a narrow light-dark stripe pattern and a wide light-dark stripe pattern.

The surface inspection apparatus according to a tenth aspect of the present invention is configured such that the light-dark pattern formed on the light diffusion sheet is a continuously changing pitch type light-dark stripe pattern in which the pitch width changes continuously. .

According to an eleventh aspect of the present invention, there is provided a surface inspection apparatus having a plurality of light and dark patterns having a predetermined light and dark pattern for irradiating light from a light source of the illuminating means as surface illumination by diffused light of a light and dark pattern. A light diffusion sheet is provided between the light source and the object to be inspected, and the plurality of light diffusion sheets have a light diffusion sheet having a light and dark stripe pattern having a small pitch width and a light diffusion sheet having a light and dark stripe pattern having a wide pitch width. It is configured to include a sheet.

According to a twelfth aspect of the present invention, in the surface inspection apparatus, the light diffusion sheet has a portal shape surrounding the object to be inspected and is movable relative to the light source of the illumination means. It is configured to be stretched over the guide.

According to a thirteenth aspect of the present invention, in the surface inspection apparatus, the plurality of CCD cameras arranged in a direction orthogonal to the moving direction of the object to be inspected have a continuous field of view along a cross-sectional contour of the surface to be inspected. It has a band shape, and the horizontal or vertical direction in the received light image of the CCD camera coincides with the moving direction of the inspection object.

A surface inspection apparatus according to a fourteenth aspect of the present invention has a configuration in which the visual fields of adjacent CCD cameras overlap each other by a predetermined area.

According to a fifteenth aspect of the present invention, in the surface inspection apparatus, the adjustment of the CCD camera is performed so as to substantially conform to the cross-sectional contour of the object to be inspected, and points, lines, and lines are formed on the surface at predetermined intervals. The configuration is performed using a reference model in which at least one reference pattern among the grid lines is drawn.

A surface inspection apparatus according to a sixteenth aspect of the present invention is configured such that the reference model has a shape substantially adapted to the largest cross-sectional profile of the object to be inspected.

A surface inspection apparatus according to a seventeenth aspect of the present invention is configured such that the color of the surface ground of the reference model is the same as the paint color having the highest reflectance on the surface to be inspected.

In the surface inspection apparatus according to claim 18 of the present invention, the adjustment of the CCD camera is performed by using a test piece which is painted in the same color as the paint color having the highest reflectance on the surface to be inspected and which is larger than the field of view of the camera. The arrangement is such that it is arranged on the surface of the reference model.

[0029]

According to the surface inspection apparatus according to the first aspect of the present invention, a light and dark pattern is formed by irradiating the surface of the moving object to be inspected, and the inspection surface on which the light and dark pattern is projected is imaged. Defects on the inspection surface can be automatically and accurately detected based on the obtained light reception image. Further, even if the surface to be inspected is a complicated curved surface, it is possible to automatically and accurately detect a defect on the surface. In particular, the surface inspection apparatus can detect defects on the surface of the object to be inspected more quickly and more accurately, and obtain the defect information and the signal on the surface of the object to be inspected in the obtained image information. The noise generated in the processing can be clearly identified, and the defect can be detected with high accuracy. Further, according to the surface inspection apparatus according to claim 2 of the present invention, a light-dark pattern is formed by irradiating the surface of the moving object to be inspected,
Take an image of the surface to be inspected on which this light and dark pattern is projected,
Defects on the inspection surface can be automatically and accurately detected based on the obtained light reception image. Further, even if the surface to be inspected is a complicated curved surface, it is possible to automatically and accurately detect a defect on the surface. In particular, the surface inspection apparatus can detect various types of defects on the surface of the object to be inspected more quickly and more accurately, and obtain the image information obtained on the surface of the object to be inspected. Defect information and noise generated in signal processing can be clearly identified, and a defect can be detected with high accuracy.

According to the surface inspection apparatus of the third aspect of the present invention, in addition to the effects of the first and second aspects, the entire apparatus can be made compact by using a CCD camera as the image pickup means. In addition, a highly accurate captured image can be obtained.

[0031]

[0032]

[0033]

According to the surface inspection apparatus of the fourth aspect of the present invention, in addition to the effects of the first to third aspects, the efficiency of the detection processing when detecting the defect by processing the obtained image information is improved. This is achieved and the defect can be detected in a shorter time.

According to the surface inspection apparatus of claim 5 of the present invention, in addition to the effects of claims 1 to 3, erroneous detection can be prevented and a defect can be detected with higher accuracy.

According to the surface inspection apparatus of the sixth aspect of the present invention, in addition to the effects of the first to third aspects, surface defects can be quickly and accurately detected by the minimum necessary inspection processing. The surface defect can be easily recognized on the developed view of the inspection object.

According to the surface inspection apparatus of the seventh aspect of the present invention, in addition to the effect of the sixth aspect, the position of the surface defect on the developed view of the inspected object can be displayed with higher accuracy.

According to the surface inspection apparatus of the eighth aspect of the present invention, in addition to the effects of the first to third aspects, it is possible to accurately form a light and dark pattern on the surface to be inspected of the object to be inspected. Defects can be easily and accurately detected.

According to the surface inspection apparatus of the ninth to eleventh aspects of the present invention, in addition to the effects of the first to third and eighth aspects, in addition to the relatively high-angle unevenness defects such as dust spots,
Even irregularities with a gentle angle can be detected with high accuracy.

According to the surface inspection apparatus of the twelfth aspect of the present invention, in addition to the effects of the eighth to eleventh aspects, by moving the sheet guide to a position away from the illumination means, for example, the light source of the illumination means can be changed. At the time of replacement, the replacement operation can be easily performed.

According to the surface inspection apparatus of the thirteenth and fourteenth aspects of the present invention, in addition to the effects of the third to twelfth aspects, the inspection accuracy can be further improved, and the entire inspection surface can be inspected without gaps. can do.

According to the surface inspection apparatus according to the fifteenth aspect of the present invention, in addition to the effects of the third to fourteenth aspects, the use of the reference model makes it possible to adjust the imaging means more easily and quickly. .

According to the surface inspection apparatus of the sixteenth aspect of the present invention, in addition to the effect of the fifteenth aspect, the inspection accuracy can be further improved.

According to the surface inspection apparatus of the seventeenth aspect of the present invention, in addition to the effects of the fifteenth and sixteenth aspects, it is possible to achieve more efficient adjustment of the imaging means.

According to the surface inspection apparatus of the eighteenth aspect of the present invention, in addition to the effects of the fifteenth and sixteenth aspects, when the surface of the reference model cannot be painted, the adjustment of the imaging means can be efficiently performed. Can do well.

[0046]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing one embodiment of a surface inspection apparatus according to the present invention, and shows a case where a defect inspection of a painted surface of an automobile is taken as an example. As shown in FIG.
An arch (gate) type illumination device 1 as illumination means formed in an arc shape so as to substantially conform to the cross-sectional profile of the body 5.
Are configured to project a predetermined light-dark pattern on the surface to be inspected. The light-dark pattern is a composite light-dark pattern having a narrow light-dark pattern for detecting a loose defect (low angle) and a wide light-dark pattern for detecting a general irregularity defect (high-angle defect). It is formed as a pattern. Further, a plurality of CCD cameras 3 as imaging means are fixed to the fixing means 2 which is provided in substantially the same shape as the lighting means and is provided so as to image the surface to be inspected on which the light / dark pattern is projected. Each CCD camera 3 is arranged at a predetermined position (one CCD camera 3 is shown in FIG. 1). Further, these CCD cameras 3 detect a defect on a surface to be inspected based on a received light image obtained by the CCD camera 3, and detect the defect. It is connected to an inspection processing means 4 for outputting a result. The inspection processing means 4 includes an image processing (enhancing) unit 41,
A tracking processing unit 42 and a host computer 43 are provided. Further, as shown in FIG. 2, the image processing unit 41 performs a predetermined calculation based on the edge detector 13 and a physical quantity related to an edge luminance level of a stripe pattern boundary portion in an image whose edge has been detected and processed. A first threshold value calculation unit 14 for calculating a threshold value, a first binarization processing unit 16 for performing a binarization process based on the threshold value, and a noise (bright and dark stripe) generated in the image subjected to the edge detection process. A second threshold value calculating unit 15 that performs a predetermined calculation based on a physical quantity related to the pattern edge (excluding the edge of the pattern) to calculate a predetermined threshold value, and a second binary value that performs a binarization process based on the threshold value Processing section 17 calculates the width of the light and dark stripe pattern having a high luminance level, and determines whether the stripe pitch width is a narrow area, a wide area, or a non-inspection surface area by comparing with a plurality of predetermined values. It is constituted by the region determining unit 18 or the like.

Further, the result of the defect detection detected by the inspection processing means 4 is output by the printer 10 as shown in FIG.

On the other hand, the body 5 placed on the carriage 6 is illuminated by the illuminating means 1 and C by the conveyor 8 on the rail 7.
After moving in the fixing means 2 for fixing the CD camera, predetermined processing is performed by the inspection processing means 4 at that time, and a defect detection inspection of the painted surface of the body 5 which is the inspection target surface is performed.

FIG. 3 is a schematic plan view of the present apparatus. FIG.
As shown in the figure, the positional relationship between the illuminating means 1 and the fixing means 2 is set perpendicular to the transport direction of the body 5 (the direction of the arrow in the figure) and forms an arch shape. CC
The D camera 3 is fixed to a fixing means 2 (hereinafter referred to as a camera stand) via an adjustment fixing jig 3 ′ having a structure (not shown) capable of freely adjusting the camera mounting position and angle. Position and angle are fixed.

FIG. 4 is a schematic side view of the present apparatus. FIG.
As shown in FIG. 5, the body 5 is placed on a carriage 6 having wheels 6 ′, and moves in the illumination means 1 and the camera stand 2 by a conveyor 8 (not shown) on a rail 7.

Here, the illuminating means 1 constituting a part of the surface inspection apparatus according to the present invention will be described.

As shown in FIG. 1, the shape of the illuminating means 1 is a shape substantially conforming to the cross-sectional profile in a direction perpendicular to the transport direction of the object to be inspected (the body 5 in this embodiment).
With such a shape, the distance from the light irradiation surface of the illuminating means 1 to the surface of the object to be inspected is substantially constant irrespective of the region, and thus the light from the illuminating means 1 is spotted on the surface of the object to be inspected. Irradiation is almost uniform.

Next, the structure of the illumination means will be described.

In order to irradiate the light of the light source to the surface to be inspected without waste and without unevenness, the illuminating means 1 has a back plate which is white or has been subjected to a surface treatment so as to diffusely reflect the light. It has a structure in which a plurality of light sources are attached to the face plate at substantially equal intervals. 5 and 6 show one embodiment.

As shown in FIG. 5, U-tube fluorescent lamps 101 are mounted on the back plate 102 at substantially equal intervals. Also, four fluorescent lamps 101 are mounted on one back plate 102 on the side of the object to be inspected in a total of four rows, and a power source 107 for high-frequency lighting of the fluorescent lamps 101 is provided on the back side (see FIG. 8).
Are attached to form the lighting unit 104.
The above-mentioned lighting means 1 can be realized by attaching such a lighting unit 104 to an arch-shaped support 103 having no gap as shown in FIG.

Next, a method of forming a light and dark pattern by the illumination means will be described.

FIG. 7 is a perspective view showing the structure of the light / dark pattern sheet 105 and the sheet guide 106 as a light diffusion sheet, and FIG. 8 is a schematic sectional view for explaining the positional relationship of components constituting the illuminating means. FIG.

As shown in FIG. 7, the light and dark pattern sheet 1
05 has a function of diffusing light, and can be easily deformed so as to follow the cross-sectional contour shape of the inspected object.
For example, a sheet-like material is provided with a predetermined light / dark pattern using, for example, a matte black masking tape. The reason for diffusing the light is to suppress the influence of the metallic glittering material when the body 5 is coated with metallic paint. Further, the light-dark pattern sheet (diffusion sheet) 105 is formed as a composite light-dark stripe pattern having a narrow light-dark stripe pattern and a wide light-dark stripe pattern.

When the diffusion sheet 105 is made of a material which is likely to be wrinkled, and the wrinkles cause shading or illumination spots, as shown in FIG. 7, the diffusion sheet 105 is supported from below, and The use of the sheet guide 106 for stretching the cross-sectional contour shape can suppress the occurrence of the wrinkles. The sheet guide 106 is painted in matte black, and the columns of the sheet guide are spaced so as to overlap the dark portions of the light and dark pattern of the diffusion sheet 105. Diffusion sheet 105 and sheet guide 106
Is fixed by using matte black bolts, nuts, washers, and the like at the column (not shown).

Further, as shown in FIG. 7, a caster 106 'is attached to the sheet guide 106 so that the sheet guide 106 can be moved with the diffusion sheet 105 stretched. Therefore, as shown in FIG. 6, if it is movable with respect to the illumination means 1, the sheet guide 106 (dotted line in the figure) can be moved independently and independently of the illumination means 1, as shown in FIG. (The arrow in the figure) For example, when replacing the fluorescent lamp 101 of the illumination means 1, the replacement operation can be easily performed. The configuration of the illumination means is not limited to the present embodiment.

As another embodiment of the light and dark pattern, FIG.
As shown in FIG. 0, a light diffusion sheet 205 that forms a continuously changing pitch type light-dark stripe pattern that continuously changes from a light-dark stripe pattern having a small pitch width to a light-dark stripe pattern having a large pitch width can be employed.

Next, the fixing means for fixing the image pickup means will be described in detail.

FIG. 11 is a schematic view of the camera stand 2 as a fixing means, and FIG. 12 is a view for explaining the field of view of the camera.

As shown in FIG. 11, the camera stand 2
Is a shape substantially along the cross-sectional contour shape of the body 5. This is to make the distance from the camera 3 to the surface of the body 5 substantially constant for all cameras.
The size of the field of view of all cameras is almost the same. When the above-described fine adjustment of the distance or the adjustment of the direction of the camera is performed according to the shape of the body 5, the adjustment is performed by adjusting an adjustment fixture 3 ′ fixed to a predetermined position of the camera stand 2. If the adjustment fixture 3 'cannot be adjusted,
For example, on the surface of the hood portion 5h (bonnet) and the roof portion 5r (ceiling) of the body 5 that have greatly different heights,
The size of the camera field of view may be adjusted by changing the focal length of the lens.

Further, as shown in FIG. 12, the fields of view of the cameras 3 adjacent to each other are adjusted so as to form an overlapping strip having a predetermined size or more. As described above, the heights of the hood portion 5h and the roof portion 5r are greatly different from each other. However, as is clear from the drawing, these portions are not inspected by the same camera 3 at the same time.
As shown in (1), cameras for the hood (cameras 3 in the upper row) and those for the roof (cameras 3 in the lower row) may be switched and adjusted. The switching positions Lf and Lr of the camera 3 are
The front and rear window portions 5wf and 5wr which do not require inspection as shown in FIG. 12 are appropriate. At this time, the field of view of the roof camera is band-like at the roof portion, like the other side cameras and hood cameras.

The overlap of the camera field of view is an area like the shaded portion 301 in FIG. 12, but the number of cameras increases as the amount of overlap increases. Therefore, the resolution of the image, that is, the size of the visual field per camera is determined from the minimum size of the defect to be detected, and the approximate camera size necessary to inspect the entire inspection surface is determined from the size of the visual field. The number may be determined, and finally the overlap amount may be determined.

As shown in FIG. 12, each camera field of view 302 represented by a rectangle is fixed in a direction such that the body 5 moves in the horizontal or vertical direction in the image received by the camera without being oblique.

Next, the transporting means for transporting the detected object will be described.

FIG. 13 is a schematic side view for explaining the conveying means. As shown in FIG.
Is composed of a chain 8a, a driving sprocket 8b, a pulse generator 8c, hooks 8d and 8e, and the like.
The pulse generator 8c detects rotation amount information of the driving sprocket 8b, and the information obtained here is sent to the host computer 43. Hooks 8d and 8e are hooked on the lower claws 6a of the carriage 6, and the drive sprocket 8b rotates in the direction of the arrow,
The chain 8a is driven and the body 5 is transported. Therefore,
If there is no gap between the pawl 6a and the hooks 8d and 8e, the movement amount of the chain 8a and the drive sprocket 8b and the movement amount of the body 5 substantially match.

Therefore, the body 5 placed on the carriage 6
By the conveyor 8, the illumination means 1 installed and fixed at the above position in the direction along the rail 7 and the camera stand 2 to which the CCD camera 3 is attached are smoothly moved at a low speed and without vibration. At the same time, the inspection processing means 4 automatically detects a defect on the painted body surface according to the procedure described below.

Next, the inspection processing means for detecting a defect on the surface to be inspected based on the received light image obtained by the imaging means and outputting the result will be described. FIG. 14 and FIG.
3 shows an example of an image processing and an example of a processing flow in an image processing unit 4 for detecting a general unevenness defect (relatively high angle) on a painted surface.

When an image of the surface to be inspected on which the light and dark pattern is projected by the illumination means is taken by the CCD camera 3, FIG.
4 (a) is obtained. In the original image, light is irregularly reflected at the uneven defect portion, and therefore appears as a dark portion 143 in the bright pattern 141 as shown in the figure. Similarly, when a defect exists in the dark pattern 142, it appears as a bright portion.

When an edge detection process such as differentiation is performed on this original image and binarized by a predetermined threshold value, FIG.
As shown in (b), a binary image is obtained in which the area where the luminance has changed in the image, that is, the area 144 having a high spatial frequency is white and the other parts 146 are black.

Next, labeling (numbering) and area / centroid calculation are performed on the white pixels of the binary image. Defects appear as isolated points in the white pixels of the binary image, and the boundary 144 of the light and dark pattern is a large object that crosses the top and bottom of the screen. Is extracted as shown in FIG.
An image as shown in FIG.

Here, if there are irregularities on the painted surface that do not cause defects such as yuzu skin, as shown in FIG.
It may be extracted as an isolated point 145 (hereinafter referred to as noise) together with the defect 143.

FIG. 16 shows image processing (enhancement) for detecting general irregularities (relatively high angle) on the painted surface shown in FIGS. 14 and 15 and also detecting loose irregularities. 3) shows an example of the flow.

Here, the detection of general unevenness defects (defects at a relatively high angle) is the same as that shown in FIGS. FIG. 17A shows an image of the surface to be inspected on which the light and dark pattern is projected by the illuminating means, taken by the CCD camera 3. In the original image, since the irregular reflection (angle) of light is small at the defect portion having the loose unevenness, it is difficult to detect the defect portion having the loose unevenness at the center of the light and dark pattern.

On the other hand, at the boundary between light and dark patterns as shown in FIG. 17 (a), the stripe pattern on the opposite side can be reflected due to the positional relationship between the light and dark stripes. Is a high luminance point as shown in FIG. When the binarization process is performed on the differential screen using the threshold value of the luminance average + a at the boundary between the light and dark patterns obtained by the calculation, as shown in FIG.
Area with large luminance change, that is, area with high spatial frequency (defect)
Is obtained, and the other part including the light-dark pattern boundary is black, thereby obtaining a binary image. Labeling (numbering) and area / centroid calculation are performed on the white pixels of the binary image. Since the defect is an isolated point in the white pixel of the binary image, if an area is determined using a predetermined determination value and only an isolated point having a small area is extracted, an image as shown in FIG. 17D is obtained.

Here, an example of the binarized area determination section and the divided binarization processing section of the image processing (enhancing) means shown in FIGS. 16 and 17 will be described.

As shown in FIGS. 18 and 19, the binarized area judging section judges the light-dark stripe original image into a narrow area (small pitch) and a wide area (large pitch) of the bright or dark area. The area is divided, and the narrow area is the threshold value 2 calculated above, and the wide area is the threshold value 1 calculated similarly.
Is used to perform a binarization process. Thereby, the efficiency of the detection process is improved. When there is a non-inspection surface such as a background in the original image of the light and dark stripes, the pitch width L of the light and dark stripes is set to a predetermined value L _{0 as} shown in FIG.
The, by applying a predetermined threshold value 3 to determine the unwanted areas, in the case of less than the predetermined value L ₁ is applied a threshold 2 calculated above determines that a narrow area not less than And L ₀ > L
> For L _1, it is determined that a wide area by applying the threshold 1 calculated by the binarization processing. Thereby, erroneous detection can be prevented.

[0082] Here, the X-axis coordinate X ₀ for dividing light and dark stripes in the narrow region and the wide region of pitch, coordinate Y ₁ of the n-number of _Y-axis, Y 2, _..., in Yn, pitch coordinates X on the n X-axis width L becomes L ₀ or more
_{10, X} 20, seeking ... Xn _0, applying the average value _{X 0} obtained by substituting the following equation (1).

[0083] A tracking process 42 for extracting only a defect from the processing data obtained as described above will be described with reference to FIGS. In the image emphasizing means as described above, if the process of extracting isolated points is performed continuously in time, the resulting area determination images are as shown in FIGS. 21 (a) to 21 (f), which are superimposed. FIG. 21 (g).

That is, the camera and the illuminating means are fixed, while the body 5, which is the object to be inspected, moves.
Moves in the direction of the arrow in FIG. 21G according to the movement of the body, but the noise 212 is generated randomly regardless of the movement of the body 5.

Thus, from the continuous area determination images that differ in time, an image that matches the movement amount and the movement direction of the body 5 under predetermined conditions can be finally determined to be the defect 211.
Since the moving direction of the defect 211 in the image is determined by the direction in which the body 5 passes through the camera 3, the position of the camera 3 is fixed and the transport direction of the body 5 as in the present embodiment. Can always be determined for each camera.

Further, if the field of view of the camera 3 is set parallel to the transport direction of the body 5, the defect moves in the horizontal or vertical direction in the image. In the present embodiment, as shown in FIG. 21 (g), it is assumed that the camera 3 is fixed in such a direction that the defect 211 moves rightward (arrow) in the image.

In the continuous images obtained in this manner, which are temporally different from each other, first, the barycentric coordinates of the white pixels of each image in the Y direction (vertical method of the screen) are compared. As described above, the defect 211 moves right and left in the image. Therefore, if there is a white pixel having substantially the same barycentric coordinate in the Y direction between the two images, it is determined that the white pixel is likely to be the defect 211. it can. Therefore, this white pixel is stored in the memory as a defect candidate.

Next, in the white pixels in the defect candidates,
The difference between the coordinates of the center of gravity in the X direction between the two images represents the number of moving pixels in the image, and the arrangement direction thereof represents the moving direction. By comparing the moving direction with the moving direction, if the difference is within a predetermined range (within a range considered to be coincident), it can be determined that the white pixel is more likely to be defective. Therefore, the temporally new coordinates of the X and Y centroids of the white pixel are stored in the memory.

A series of processes as described above is repeatedly performed.
If the number of matches of one white pixel is equal to or greater than a predetermined number as a result of the comparison, the white pixel is determined as a defect (defect determination in FIG. 15), and the final barycentric coordinates and area are added to the defect list. Is written and stored.

The tracking processing means 42 continuously performs the above-mentioned processing while the body 5 is in the field of view of the camera, and sends the defect list to the host computer 43 after the body 5 has passed.

The actual moving pixel number N can be calculated by the following equation (2).

N = (t × V × L) / A (2) where t is the time between images, and the time difference between two temporally different images to be compared (for example, 0.1 second) In this embodiment, this corresponds to the processing time of the image enhancement processing. this is,
Measurement is possible by counting the interval at which the tracking processing unit 42 receives data (area / center-of-gravity coordinate data after area determination) from the image enhancement unit 41.

V is the moving speed of the body 5 (for example, 10
0 mm / sec), which is calculated by the host computer 43 based on the rotation amount information of the driving sprocket 8 b sent from the pulse generator 8,
Sent to 2 at any time.

L is the image size, that is, the number of pixels in the moving direction of the body 5 in the image.
If the body 5 moves in the X direction in an image of pixels of = 512 × 480, L = 512.

A is the field of view of the camera, and specifically,
This is the dimension of the field of view of the camera on the surface to be inspected in the body movement direction. For example, on the surface to be inspected, one camera field of view 302 (see FIG. 12) has X × Y = 120 mm × 100.
mm, if the body 5 moves in the X direction, A = 12
0 mm.

Here, the relationship between the inter-image time t, the body moving speed V, and the camera visual field A will be described. In the present embodiment, t corresponds to the image enhancement processing time. However, if the speed V is too fast to pass through the camera field of view A during the time t, the same defect is detected in the image when there is a defect. To 2
It does not appear more than once, and the above tracking process is not established. So, so that the defect appears at least twice in the image,
It is necessary to set the inter-image time t, the body moving speed V, and the camera visual field A.

Further, if the above-described image enhancement processing is executed by interrupting the timer at predetermined time intervals, the inter-image time t becomes constant, so that the above-described various adjustments and calculations become easy. The image enhancement means 41 and the tracking processing means 42
Is not limited to the present embodiment.

When the inspection of one body is completed by the inspection processing as described above, based on the defect inspection result,
A mark, for example, a circle is displayed at a position on the body development view corresponding to the defect position on the body surface. This procedure will be described below.

First, a description will be given of an examination start / end determination means for judging a start time and an end time of the inspection when the object to be inspected moves in a region surrounded by the illumination means and the imaging means.

The inspection start / end determination means detects the movement of the body 5 and determines the start and end timings of various inspection processes (in FIG. 22, line Ls indicates the inspection start position, and line Le indicates the inspection end position). For example, the transmission-type photoelectric switch is placed in a direction perpendicular to the transport direction of the body 5 and at a height such that the front and rear ends of the body 5 block the light of the photoelectric switch, and furthermore, in the camera view. It can be realized by mounting the body 5 at a position where the body 5 blocks the photoelectric switch just before the tip of the body 5 is reflected.

If the relative positional relationship between the body 5 and the carriage 6 is known, the photoelectric switch may be mounted in accordance with the carriage 6.

As another embodiment, the difference in image brightness between the case where the body 5 is included in the camera field of view and the body 5 is shown in the camera image and the case where the background is shown without the body 5 is used. The start and end timings of the inspection may be determined. Note that the inspection start / end determination means is not limited to the present embodiment.

Next, a description will be given of a movement amount measuring means for measuring the movement amount of the object to be inspected based on the inspection start time detected by the above-described method. In the present embodiment, the moving amount of the object to be inspected, that is, the body 5 is determined by the pulse generator 8.
The moving distance can be calculated from the rotation information of the driving sprocket 8b obtained from c and time information such as the internal clock of the host computer 43.

That is, the inspection processing means 4 (see FIG. 1) can always grasp the inspection position of the body 5, and thereby, the position of the defect detected by the tracking processing means 42 on the body can be calculated. . Therefore, the host computer 4
3 stores the area / center-of-gravity coordinates of the defect and the position information on the body in the list.

The above series of processing is performed on each camera image, and based on the detected defect list information, for example, the display position in the developed view of the inspected object (body 5) as shown in FIG. Is calculated and marked.
As for the defect display position in the Y-axis direction in FIG. 22, the size of the camera field of view and the camera position are known, and
As described above, since the coordinates of the center of gravity of the defect moving in the image in the Y-axis direction hardly change, it can be easily calculated if the contraction scale of the developed view is determined. Similarly, the defect display position in the X-axis direction can be calculated from the movement amount of the body 5 with reference to the inspection start position Ls in FIG. In this way, the developed view in which the mark is displayed at the defect position is output to an output device such as a monitor or a printer.

Next, a plurality (two in this embodiment) of light diffusion sheets having light and dark stripe patterns of different pitches are provided.
An example in which the device is provided will be described with reference to FIGS. In this embodiment, as shown in FIG. 23, since the places where the image of the inspected surface is taken are different, two cameras 3 are provided to view the same position of the inspected surface, and two inspections are performed in response to the input. It has processing units 4a and 4b. The inspection processing units 4a and 4b mainly include image processing units 41a and 41b, tracking processing units 42a and 42b, and a host computer 43, respectively.

Here, as shown in FIG. 24, the image processing units 41a and 41b extract components having respective predetermined values or more in parallel. That is, a narrow light and dark stripe pattern 2
In the inspection processing unit 4a on the third side, a binarization process is performed based on the threshold value calculated by (stripe edge portion luminance level average + a). Also, a wide light and dark stripe pattern 2
In the inspection processing unit 4b on the 32 side, the binarization processing is performed based on the threshold value calculated based on (the noise average + a) generated in the image subjected to the edge detection processing. The image obtained by the above processing is as shown in FIG.

FIG. 26 is a schematic plan view of a line showing another embodiment.

In this embodiment, the illuminating means 1a, 1b and the camera stands 2a, 2b each have an arch shape, and are arranged in the direction of transport of the body 5 (the direction of the arrow in the figure). Here, the illuminating means 1a and 1b are provided with sheets having light and dark stripe patterns of different pitches. The CCD cameras 3a, 3b are fixed at predetermined positions on the camera stands 2a, 2b by adjusting fixtures 3a ', 3b' having a structure (not shown) capable of freely adjusting the mounting position and the mounting angle of the cameras. Fixed at an angle. Note that the defect detection method is the same as in the above-described embodiment.

Next, an embodiment in the case of having a continuously changing pitch type bright / dark stripe pattern in which the pitch width continuously changes will be described with reference to FIGS. 27 to 29. FIG.
This embodiment employs the same configuration and defect detection method as the first embodiment, but differs in the light and dark stripe pattern 271 (see FIG. 28) and the tracking processing conditions of the tracking processing unit (see FIG. 29). . Specifically, as shown in FIG. 29, the tracking condition is changed depending on the size (size) of the defect. In this case, since the number of detections is reduced due to a change in the pitch width, it is necessary to increase the processing speed of the image processing device 272 several times in order to secure the detection accuracy. FIG.
The image processing device 272 in 7 has an image processing and tracking processing unit as in the above-described embodiment.

Next, a method of adjusting the reference model and various cameras will be described. FIG. 30 is a schematic view showing a front view (a), a plan view (b), and a side view (c) of the reference model 91 for adjusting the door surface 5d and the hood / trunk surface 5ht. FIG. 31 shows the pillar surface 5p and the roof surface 5
It is the schematic which shows the front view (a), the top view (b), and the side view (c) of the reference model 92 for r adjustment, respectively.

As is clear from the drawings, the shapes of these reference models 91 and 92 substantially match the cross-sectional contours of the inspected object. In this embodiment, since the height difference between the hood surface 5h and the roof surface 5r of the vehicle body 5 is large, two types of reference models 9 are required to be inspected by separate cameras.
1, 92 are prepared, and the type of the reference model may be prepared as appropriate according to the shape of the inspected object.

Also, grid lines at predetermined intervals as a reference pattern are drawn on the surface of the reference model as shown in the figure, and the camera field of view is shown in FIG. Adjust as follows. In other words, the grid lines need only be able to confirm the size of the camera's field of view. Therefore, points at predetermined intervals as shown in FIG.
A figure such as a quadrangle, which is substantially the same as the size of the predetermined visual field as shown in FIG. At this time, focus adjustment is also performed while looking at the figure of the reference model displayed on the monitor.

FIG. 33 shows the illumination means 1 at the time of the above adjustment.
FIG. 4 is a schematic plan view showing a positional relationship between a camera 3 and reference models 91 and 92. Since the body 5 to be inspected is moved along the rails 7 by the conveyor 8, the reference models 91 and 92 are located at the same position as the body 5 at the time of movement, that is, at 90 ° to the rails 7. The camera 92 is set at a position where both ends of the
Make adjustments.

FIG. 34 shows the hood / trunk surface 5 ht
FIG. 9 is a schematic front view showing a positional relationship between the illumination unit 1, the camera 3, and the reference model 91 when adjusting the door surface 5d;
FIG. 35 is a schematic front view showing the positional relationship between the illumination means 1, the camera 3, and the reference model 92 when adjusting the roof surface 5r and the pillar surface 5p. As shown in FIGS. 34 and 35, the height position of the body 5 at the time of conveyance and the reference models 91 and 9
In order to make the height position coincide with the height position of the second adjustment table 93, 9
4, various adjustments of the camera 3 are performed by mounting the reference models 91 and 92 respectively.

Next, the shape of the reference model will be described.

As shown in FIGS. 30 and 31, the shapes of the reference models 91 and 92 are substantially adapted to the cross-sectional contour of the body 5 as the object to be inspected.
Of the outermost or largest cross-section of the To conform to the largest cross-sectional profile means that the distance from the camera 3 to the contour surface is the shortest. If the field of view of the camera 3 is adjusted in this state, the camera 3 will not move from the camera 3 in other parts. The distance increases. Therefore, the camera fields of view of the adjacent cameras 3 always overlap.

That is, if the amount of overlap is adjusted in a state where the cross-sectional profile is not maximum, the cross section of the camera field of view forms a diverging triangle as shown in FIG. 12, so that the distance between the camera 3 and the subject (body 5) is increased. Is smaller, the field of view becomes smaller, and a predetermined overlapping amount cannot be secured at a portion having a larger cross-sectional profile than at the time of adjustment.

Therefore, in order to ensure a predetermined amount of overlap, the reference model only needs to have a shape conforming to the largest cross-sectional profile of the object to be inspected. Part 5d, roof part 5
The reference model may be formed so as to conform to the central part at r and the highest part at the hood / trunk part 5ht.

FIG. 36 explains a method of determining a reference model when there are a plurality of types of bodies having different shapes. As shown in FIG. 36A, the body A and the body B
In the case where there are two types, since the cross-sectional contour of the body A is larger in all parts, the reference models 91 and 92 are shaped like thick lines in the figure. Further, as shown in FIG. 36 (b), when the size of the cross-sectional contour of the body A and the body B is different in each part, the larger one of the cross-sectional contours of the body A and the body B is smoothly connected. In the shape of a bold line.

Next, a method of adjusting the camera 3 will be described.

Since the distance from the camera 3 to the surface to be inspected, ie, the photographing distance, varies depending on the shape and type of the object to be inspected, the depth of field of the camera 3 must be adjusted in order to focus on all areas. It is necessary to make the (focusing range) sufficiently large with respect to the change in the photographing distance. Since the depth of field can be calculated from the lens aperture value, the lens focal length, and the shooting distance, if the lens specifications, the shooting distance, and the necessary depth of field are determined in advance from the size of the camera field of view, An approximate lens aperture value can be determined.

Further, when the object to be inspected is moving as in this embodiment, the shutter speed of the camera 3 is
The value needs to be such that the received light image of the camera does not fluctuate, and the aperture and shutter speed may be finely adjusted and determined in consideration of the moving speed.

The specific method of adjusting the aperture and shutter speed will be described below. The aperture and shutter speed of the lens are adjusted using an oscilloscope or the like so that the output signal level of the camera does not saturate when the reflectance is the highest in the light reflection characteristics of the surface to be inspected. For example, when the object to be inspected is painted like an automobile body, the adjustment may be made with the paint color having the highest brightness such as white or silver metallic. In addition, the shorter the distance between the illumination 1 and the camera 3 and the surface to be inspected, the greater the amount of reflection of the light. Therefore, if the positions of the illumination 1 and the camera 3 are fixed as in the present embodiment, for example, The adjustment may be performed on the surface of the reference model created from the maximum cross-sectional profile of the object.

As a guide for the above adjustment, brightness (brightness)
In order to use the dynamic range in the direction without waste, it is sufficient that the output signal level of the camera 3 is slightly before the white level is exceeded. Further, if the background portion other than the surface on which the field-of-view adjusting graphic (reference pattern) of the reference model is drawn has the highest reflectance such as white or silver metallic as described above, the camera The adjustment of the aperture and the shutter speed of the lens can be performed together with the adjustment of the field of view of the camera 3, whereby the camera 3 can be adjusted efficiently.

When it is difficult to paint the adjustment surface of the reference model as described above, prepare a test piece larger than the camera field of view painted white or silver metallic as described above, and prepare a test piece corresponding to the camera field to be adjusted. In this case, the adjustment may be performed while the camera 3 is placed in contact with the surface of the reference model to be imaged.

Next, the light / dark pattern will be described.

When edge detection by differentiation is used in the image processing (enhancing) means, a change in luminance in the image is extracted. Therefore, as shown in FIG. Lines are also extracted as white pixels 144. Therefore, if the defect 143 is near the boundary 144 of the light and dark pattern, the defect 143 and the boundary 144 may be integrated, and the defect 143 may not appear as an isolated point. Furthermore, as the number of boundary lines reflected per screen increases, the frequency at which the defect disappears increases, so that the defect detection accuracy deteriorates. For example, since the front end of the front fender of the body 5 has a convex curved surface and acts as a convex lens, if the pitch of the light and dark pattern is constant regardless of the region, the camera image will have more than the flat surface. A boundary line appears, and the accuracy of defect detection deteriorates.

FIGS. 37 and 38 are diagrams for explaining a method for solving the above-described problem.

In FIG. 37 and FIG.
Reference numeral 381 denotes the position of the light and dark pattern sheet 105 reflected on the surface of the body 5 and reflected in the field of view of the camera 3, and image examples at that time are as shown in (a), (b), and (c) in the figure. Become. For example, in order to make four boundary lines of the light and dark pattern appear in the image, the pitch of the light and dark pattern may be designed in consideration of the shape of the body 5. Here, the number of boundary lines of the light-dark pattern is a problem, and there is no limitation since the way of displaying the light-dark pattern in the image, that is, the order of light / dark is not related to the detection principle using diffuse reflection at a defect.

As shown in the figure, when the pitch of the light and dark pattern on the side surface (see FIG. 37) of the body 5 is different from the pitch of the light and dark pattern on the horizontal surface (see FIG. 38), for example, If a matte black tape is applied so that the light and dark pattern does not become discontinuous in the R portion of the arch shape, the light and dark pattern is projected without extreme distortion even in the R portion between the front and rear fenders and the hood / trunk surface.

In the embodiment shown in FIGS. 37 and 38, the number of boundaries is four in the image, but the number of boundaries does not need to be the same for each camera. In addition, the frequency of defects appearing on the screen increases as the number of boundaries decreases, but if the pitch of the light and dark patterns is too wide in order to reduce the boundaries, the defect is detected using irregular reflection due to unevenness in the defects. Since the accuracy of detecting small defects decreases, it is sufficient to experimentally design the light and dark patterns taking these factors into consideration.

Next, a development view of the inspected object will be described.

In this embodiment, regardless of the shape of the body 5,
The lighting device 1 is configured to form a light and dark pattern on the body surface reflected in the field of view of the CCD camera 3. That is, as shown in FIG. 39, the CCD camera 3 is configured to capture an image from the oblique front with respect to the body 5, and the camera mounting angle at this time is θ ₂ and the angle of view of the camera is θ ₁ . When the above inspection process is performed at such a camera position and the defect position is displayed in a normal development view as shown in FIG. 22, the position may not match the position of the defect present on the actual body. This is because, as shown in FIG. 39, the camera 3 captures an image from a viewpoint obliquely from the front, whereas the developed view shows the viewpoint from the side (side view) and the top (horizontal plane) of the body. Because they have different viewpoints. In order to prevent such a display shift of the defect, as shown in FIG. 40B, a development view in which the body 5 is viewed obliquely from the front like the camera 3 may be used. The rotation angle of the developed view at this time is the angle θ ₁ ,
What is necessary is just to apply (theta) ₂ or to determine experimentally.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing one embodiment of a surface inspection apparatus according to the present invention.

FIG. 2 is a block diagram illustrating an image processing unit that forms a part of the surface inspection apparatus according to the present invention.

FIG. 3 is a schematic plan view showing one embodiment of the surface inspection apparatus according to the present invention.

FIG. 4 is a schematic side view showing one embodiment of the surface inspection apparatus according to the present invention.

FIG. 5 is a schematic side view showing an illuminating means constituting a part of the surface inspection apparatus according to the present invention.

FIG. 6 is a schematic front view showing an illuminating unit constituting a part of the surface inspection apparatus according to the present invention.

FIG. 7 is a schematic perspective view showing a light-dark pattern light diffusion sheet and a sheet guide which constitute a part of the surface inspection apparatus according to the present invention.

FIG. 8 is a schematic plan view showing a positional relationship between an illumination unit, an imaging unit, an object to be inspected, and the like according to the present invention.

FIG. 9 is a plan view for explaining movement of the light-dark pattern light diffusion sheet according to the present invention.

FIG. 10 is a schematic perspective view showing a continuously changing pitch type light-dark pattern light diffusion sheet and a sheet guide according to the present invention.

FIG. 11 is a front view showing an arrangement relationship between a camera stand and a camera according to the present invention.

FIG. 12 is a diagram for explaining a state of a camera field of view between cameras according to the present invention.

FIG. 13 is a schematic side view showing a transporting means of the inspection object according to the present invention.

FIG. 14 is a diagram illustrating an example of image processing by an image processing unit according to the present invention.

FIG. 15 is a flowchart showing a surface inspection process according to the present invention.

FIG. 16 is a flowchart showing another embodiment of the surface inspection processing according to the present invention.

FIG. 17 is a diagram showing another embodiment of the image processing by the image processing means according to the present invention.

FIG. 18 is a diagram for explaining a binarization process according to the present invention.

FIG. 19 is a diagram for explaining a binarization process according to the present invention.

FIG. 20 is a diagram for explaining the binarization processing when there is a non-inspection surface such as a background in the binarization processing according to the present invention.

FIG. 21 is a diagram showing an image for which area determination has been performed by the image processing means according to the present invention.

FIG. 22 is a diagram for explaining display of a defect in a developed view of the inspection object according to the present invention.

FIG. 23 is a diagram illustrating an example in which a plurality of light and dark stripe patterns having different pitches are provided as the light and dark stripe patterns according to the present invention.

FIG. 24 is a flowchart showing an inspection procedure in the embodiment shown in FIG.

25 is a diagram showing an example of image processing in the embodiment shown in FIG.

FIG. 26 is a plan view showing another embodiment of the arrangement of the illumination means, the camera, and the like according to the present invention.

FIG. 27 is a diagram illustrating an example in which a continuously varying pitch type light / dark stripe pattern is provided as the light / dark stripe pattern according to the present invention.

FIG. 28 is a diagram illustrating an example in which a continuously varying pitch type light / dark stripe pattern is provided as the light / dark stripe pattern according to the present invention.

FIG. 29 is a flowchart showing an inspection process in the embodiment shown in FIG. 27;

FIG. 30 is a diagram showing a reference model according to the present invention.

FIG. 31 is a diagram showing a reference model according to the present invention.

FIG. 32 is a diagram showing another embodiment of the mark provided on the surface of the reference model according to the present invention.

FIG. 33 is a plan view showing a positional relationship between an illumination unit, a camera, a reference model, and the like when adjusting the camera according to the present invention.

FIG. 34 is a front view showing a positional relationship of a lighting unit, a camera, a reference model, and the like at the time of camera adjustment with respect to a hood surface, a trunk surface, and a door surface of an automobile body as an object to be inspected according to the present invention.

FIG. 35 is a front view showing a positional relationship of a lighting unit, a camera, a reference model, and the like at the time of camera adjustment with respect to a roof surface and a pillar surface of an automobile body as an object to be inspected according to the present invention.

FIG. 36 is a diagram for explaining a method of determining a contour of a reference model according to the present invention.

FIG. 37 is a diagram for explaining a light and dark stripe pattern according to the present invention.

FIG. 38 is a diagram for explaining a light and dark stripe pattern according to the present invention.

FIG. 39 is a plan view for explaining a mounting direction of the camera according to the present invention.

40 is a diagram illustrating a method of creating a development view of the body corresponding to the mounting state of the camera illustrated in FIG. 39.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Illumination means 2 Camera stand (fixing means) 3 CCD camera (imaging means) 4 Inspection processing means 5 Body (object to be inspected) 6 Truck 7 Rail 8 Conveyor (conveying means) 8a Chain 8b Drive sprocket 8c Pulse generator 8d, 8e Hook 10 Printer 13 Edge detection unit 14, 15 Threshold value calculation unit 16, 17 Binarization processing unit 18 Area determination unit 41 Image processing unit 42 Tracking processing unit 43 Host computer 91, 92 Reference model 93, 94 Adjustment stand DESCRIPTION OF SYMBOLS 101 Fluorescent lamp 102 Back plate 103 Prop 104 Lighting unit 105 Light / dark stripe pattern light diffusion sheet 106 Sheet guide 205 Continuously changing pitch type light / dark stripe pattern light diffusion sheet

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-86634 (JP, A) JP-A-8-86633 (JP, A) JP-A-8-285557 (JP, A) JP-A-8-866 145906 (JP, A) JP-A-8-285559 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/84-21/958

Claims (18)

(57) [Claims] An object to be inspected is irradiated with light on a surface to be inspected, a light receiving image is formed based on light reflected from the surface to be inspected, and a defect existing on the surface to be inspected is detected based on the light receiving image. A lighting device that includes a light source arranged in a gate shape surrounding the object to be inspected and forms a predetermined light and dark pattern on the surface to be inspected; and a gate that surrounds the object to be inspected. An imaging unit that is arranged and fixed in a mold shape and forms a plurality of light-receiving images based on reflected light from the surface to be inspected, a conveying unit that conveys the object to be inspected at a predetermined speed, and the illumination unit includes the object to be inspected. Inspection processing means for detecting a defect on a surface to be inspected based on a light reception image obtained by the imaging means and outputting detection information when passing through an area surrounded by the imaging means; Is the light receiving image obtained by the imaging means. Image processing means for extracting only high-frequency components of a predetermined level or more from spatial frequency components in the image information of the image information to be inspected from temporally different image information processed by the image processing means and captured by the same imaging means. A tracking processing unit that tracks and detects image information that matches the moving amount and the moving direction of the object under predetermined conditions, wherein the image processing unit performs image processing on the image information having a light and dark pattern obtained by the imaging unit. A first method for performing a predetermined calculation based on a physical quantity related to an edge luminance level in the processed image information subjected to the edge detection processing to calculate a threshold value so as to perform edge detection processing and extract only a component having a predetermined luminance level or more. A threshold value calculating means for performing a predetermined calculation based on a physical quantity relating to noise generated in the processed image information subjected to the edge detection processing; A second threshold value calculating means for calculating; and a binarizing processing means for performing a binarizing process based on each of the threshold values calculated by the first and second threshold value calculating means. Surface inspection device characterized by the following: 2. A method for irradiating a surface to be inspected of an object to be inspected with light, forming a light-receiving image based on light reflected from the surface to be inspected, and detecting a defect present on the surface to be inspected based on the light-receiving image. A lighting device that includes a light source arranged in a gate shape surrounding the object to be inspected and forms a predetermined light and dark pattern on the surface to be inspected; and a gate that surrounds the object to be inspected. An imaging unit that is arranged and fixed in a mold shape and forms a plurality of light-receiving images based on reflected light from the surface to be inspected, a conveying unit that conveys the object to be inspected at a predetermined speed, and the illumination unit includes the object to be inspected. Inspection processing means for detecting a defect on a surface to be inspected based on a light reception image obtained by the imaging means and outputting detection information when passing through an area surrounded by the imaging means; Is the light receiving image obtained by the imaging means. Image processing means for simultaneously extracting high frequency components of a predetermined level or more corresponding to a plurality of types of light and dark patterns among the spatial frequency components in the image information, and image processing by the image processing means and imaging by the same imaging means Tracking processing means for tracking and detecting image information that matches the moving amount and moving direction of the inspected object under predetermined conditions from the obtained temporally different image information, wherein the image processing means In order to perform an edge detection process on the obtained image information having a light and dark pattern and extract only a component having a predetermined brightness level or more, a predetermined calculation is performed based on a physical quantity related to an edge brightness level in the processed image information subjected to the edge detection process. A first threshold value calculating means for calculating a threshold value, and noise relating to noise generated in the processed image information subjected to the edge detection processing. Second threshold value calculating means for performing a predetermined calculation based on the physical quantity to calculate a threshold value, and based on each threshold value calculated by the first and second threshold value calculating means. A surface inspection apparatus comprising: a binarization processing unit that performs a binarization process. 3. The surface inspection apparatus according to claim 1, wherein the imaging unit includes a plurality of CCD cameras. 4. The binarization processing means calculates a pitch width of a light and dark pattern in image information having a plurality of types of light and dark pattern areas obtained by an image pickup means and compares the calculated pitch width with a predetermined value. Region determination means for determining which region of a plurality of types of light and dark patterns is included, and the first and second thresholds for the divided regions determined by the binary region determination device The surface inspection according to any one of claims 1 to 3, further comprising: a division type binarization processing unit that applies each threshold value calculated by the value calculation unit and performs a binarization process at the same time. apparatus. 5. The image processing apparatus according to claim 1, wherein the binarization processing means calculates a pitch width of the light and dark pattern in the image information having a plurality of types of light and dark patterns and a non-inspection surface area obtained by the imaging means, and calculates a plurality of predetermined values. A binarized area determining means for comparing and determining which area the light / dark pattern is included in, and the first and second thresholds for the divided area determined by the binarized area determining means 4. The apparatus according to claim 1, further comprising divided binarization processing means for applying each of the threshold values calculated by the calculation means and a predetermined threshold value for the non-inspection surface area to simultaneously perform the binarization processing. A surface inspection apparatus according to any one of the above. 6. The inspection processing means determines that the inspection starts when the object to be inspected starts passing through an area surrounded by the illumination means and the imaging means and ends when the object has passed. An inspection start / end determination unit; and a movement amount measurement unit for determining a movement amount of the object to be inspected based on the inspection start time determined by the inspection start / end determination unit. And calculating a position of the image information detected by said tracking processing means on a surface to be inspected based on the information obtained by said means, and displaying the calculation result on a developed view of the object to be inspected. 4. The surface inspection apparatus according to any one of 1 to 3. 7. The surface inspection apparatus according to claim 6, wherein the development view of the inspection object is drawn based on an attachment angle and an angle of view of the imaging unit with respect to the inspection object. 8. A light diffusion sheet having a predetermined light and dark pattern for irradiating light from a light source of the illuminating means to a surface to be inspected as surface illumination by diffused light of a light and dark pattern is provided between the light source and the object to be inspected. The surface inspection apparatus according to any one of claims 1 to 3, wherein the surface inspection apparatus is provided on a surface. 9. The surface inspection according to claim 8, wherein the light-dark pattern formed on the light diffusion sheet is a composite light-dark stripe pattern having a narrow light-dark stripe pattern and a wide light-dark stripe pattern. apparatus. 10. The surface inspection apparatus according to claim 8, wherein the light / dark pattern formed on the light diffusion sheet is a continuously changing pitch type light / dark stripe pattern in which a pitch width changes continuously. 11. A plurality of light diffusion sheets having a predetermined light and dark pattern for irradiating a surface to be inspected with light from a light source of the illuminating means as surface illumination by diffused light of a light and dark pattern are provided between the light source and the object to be inspected. And a light diffusion sheet having a light and dark stripe pattern having a narrow pitch width and a light diffusion sheet having a light and dark stripe pattern having a wide pitch width. 4. The surface inspection apparatus according to any one of 1 to 3. 12. The light-diffusing sheet has a portal shape surrounding an object to be inspected, and is stretched over a sheet guide movable relative to a light source of the illumination means. The surface inspection apparatus according to any one of claims 8 to 11, which performs the inspection. 13. A field of view of said plurality of CCD cameras arranged in a direction orthogonal to a moving direction of an object to be inspected has a continuous band shape along a cross-sectional contour of a surface to be inspected.
The surface inspection apparatus according to any one of claims 3 to 12, wherein a horizontal or vertical direction in a received light image of the camera coincides with a moving direction of the inspection object. 14. The field of view between adjacent CCD cameras is
14. The surface inspection apparatus according to claim 13, wherein the surface inspection apparatus overlaps each other by a predetermined area. 15. The adjustment of the CCD camera is performed so as to substantially conform to the cross-sectional contour of the object to be inspected and at least one of a reference pattern, a point, a line, and a grid line at predetermined intervals on the surface. The surface inspection apparatus according to any one of claims 3 to 14, wherein the surface inspection is performed using a reference model in which is drawn. 16. The surface inspection apparatus according to claim 15, wherein the reference model has a shape substantially adapted to the largest cross-sectional profile of the object to be inspected. 17. The surface inspection apparatus according to claim 15, wherein the color of the surface of the reference model is the same as the paint color having the highest reflectance of the surface to be inspected. 18. The adjustment of the CCD camera is performed by arranging a test piece, which is painted in the same color as the paint color having the highest reflectance on the surface to be inspected and is larger than the field of view of the camera, on the surface of the reference model. 17. The surface inspection apparatus according to claim 15, wherein: