JPH0545144A - Surface condition inspection method - Google Patents

Abstract

(57) [Abstract] [Purpose] Irradiate the surface to be inspected with bright and dark light and capture the reflected light to create a light-receiving image, as well as the light-dark data indicating the lightness change in the light-receiving image and the lightness in the light-receiving image. An object of the present invention is to obtain a differential value of a change, and combine the differential value with the light / dark data to emphasize the change of the light / dark to improve the inspection accuracy in the case of inspecting the surface state of the surface to be inspected. [Structure] The coating film surface 1a is irradiated with light / dark light 5a from a light irradiation means 5, a reflected light from the coating film surface 1a is captured to create a received light image 15, and a change in brightness in the received light image 15 is shown. Brightness data is created, and the received light image 15 is scanned in a direction orthogonal to the brightness change direction Y to obtain a differential value of the brightness change, and the brightness value is emphasized by combining the differential value with the brightness data. Then, the coating defects 16 and 17 on the coating film surface 1a are detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a surface condition, and more particularly to irradiating a surface to be inspected with light by means of light irradiating means, capturing reflected light from the surface to be inspected to create a light-receiving image, The present invention relates to a surface state inspection method for inspecting the surface state of a surface to be inspected based on the change in brightness inside.

[0002]

2. Description of the Related Art In vehicles such as automobiles, after the painting of the vehicle body is completed, the surface condition of the painted surface is inspected, that is, the presence or absence of coating defects on the painted surface is detected.
As a technique for inspecting the surface state of the coated surface, for example, Japanese Patent Laid-Open No. 62-233710 discloses that a surface to be inspected of an inspection object is irradiated with light and the reflected light is projected on a screen. , A technique for automatically detecting a surface defect of a surface to be inspected from the sharpness of the projected image is disclosed.

[0003]

By the way, as an example of a technique for detecting a surface defect by irradiating the surface to be inspected with light, capturing the reflected light and performing image processing as described above, it is possible to detect a surface defect. Light and dark light whose luminous intensity gradually changes at a suitable predetermined brightness gradient, or light and dark light in which light and dark changes are repeated is irradiated on the surface to be inspected, and the reflected light is captured to create a received light image. It has been considered to detect surface defects based on the change in brightness. That is,
As shown in FIG. 10, an original image a having a waveform showing the lightness change in the light-receiving image is created, and as shown in FIG. 11, the light-receiving image is scanned in the lightness changing direction to differentiate the lightness change. It is considered that an image b showing the differentiated value is created, and an enhanced image c is created by synthesizing the image b and the original image a. As a result, by adding the differential value corresponding to the defective portion shown in FIG. 11B to the signal of the defective portion shown in FIG.
As shown in (c), the defect portion is emphasized, and the defect inspection accuracy is improved. in this case,
By adding the differential value of the image b to the original image a, the lightness level of the emphasized image c is increased as a whole,
The maximum lightness portion is in a state of exceeding the lightness change calculation processing limit. Therefore, as shown in FIG. 12, the waveform showing the lightness change in the emphasized image c becomes a waveform with its top cut, and Becomes difficult to detect. In order to solve this problem, if the brightness of the light to be radiated on the surface to be inspected is reduced so that the light and dark gradient of the original image a becomes gentle, the overall brightness will decrease, and A new problem will occur that the accuracy will decrease.

Therefore, the present invention irradiates the surface to be inspected with bright and dark light and captures the reflected light to create a received light image, and
Brightness / darkness data indicating a change in lightness in the light-receiving image is created, and a light-receiving image is scanned to obtain a differential value of the lightness change. By combining the differential value and the light / dark data, the change in light / darkness is emphasized. An object of the present invention is to provide a surface state inspection method capable of eliminating the above-mentioned problems in the case of inspecting the surface state of an inspection surface and accurately detecting a surface defect.

[0005]

In order to solve the above problems, the present invention is characterized in that it is configured as follows.

That is, the surface to be inspected is created by irradiating the surface to be inspected with light from the light irradiating means, capturing the reflected light from the surface to be inspected, and creating a light-receiving image based on the change in brightness in the light-receiving image. In a surface state inspection method for inspecting a state, while irradiating the surface to be inspected with light and dark light that changes from light to dark from the light irradiation means, creating light and dark data indicating a lightness change in the received light image, and Scan the light-receiving image in the direction orthogonal to the method of changing the brightness and obtain the differential value of the brightness change, and combine the differential value and the brightness data to emphasize the change of the brightness and enhance the surface condition of the surface to be inspected. Characterized by an inspection.

[0007]

According to the above construction, the light-receiving image is scanned in the direction orthogonal to the light-dark change direction to calculate the differential value of the lightness change, and when there is no defect on the scanning line,
The differential value is always 0. As a result, even when the above-mentioned differential value is added to the light-dark data obtained from the light-receiving image, it is possible to reliably prevent the situation where the overall lightness level rises and the maximum lightness part exceeds the calculation processing limit. As a result, the surface condition of the entire surface of the surface to be inspected irradiated with the bright and dark light can be detected, and the change in the brightness of the defect portion is emphasized, so that the inspection accuracy is improved. ..

[0008]

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

First, a surface condition inspection apparatus configured to inspect a vehicle body painted surface by the surface condition inspection method according to the present invention will be described. As shown in FIG.
In the vicinity of the vehicle body 1 transported to the coating inspection station S, a surface state inspection device 2 for inspecting the coating surface 1a of the vehicle body 1 to detect the presence or absence of a coating defect portion is arranged. Has a robot device 4 mounted on the pedestal 3, and a light irradiation means 5 is attached to a tip arm 4 a of the robot device 4.
And a CCD camera 6 are attached via a support metal 7, and the light irradiation means 5 and the CCD camera 6 are the surface of the vehicle body 1 carried into the coating station S, that is, the coating surface of the vehicle body 1. 1a is traced, and at this time, the light emitted by the light emitting means 5 is reflected by the coating surface 1a of the vehicle body 1 and received by the CCD camera 6.

Further, the light irradiation means 5 and the CCD as described above are used.
In the coating defect inspection with the camera 6, the robot controller 9 is controlled by a command given by the host computer 8, the signal of the robot controller 9 is sent to the robot device 4, and a predetermined actuator built in the robot device 4 is sent. (Not shown) is driven, whereby the robot apparatus 4 moves the light irradiation means 5 and the CCD camera 6 so as to trace the coating surface 1a of the vehicle body 1 and receives the light received by the CCD camera 6. The image is sent to the image processor 10. Then, the image processor 10 amplifies the video signal from the CCD camera 6 and then differentiates it, and transmits the data of the differentiated signal to the host computer 8 for analysis, whereby the film surface 1a of the vehicle body 1 is analyzed. The presence / absence of the coating defect, the coordinates of the defective portion, the shape of the coating defect, and the size thereof are detected.

Next, the structure of the above-mentioned light irradiating means 5 will be explained. As shown in FIG.
A plurality of fluorescent lamps (not limited to fluorescent lamps) 12 ... 12 as light sources provided in the box 11 with one side open, and the box 11 provided in front of these fluorescent lamps 12. Filter 13 for blocking one side surface
And a diffusing screen 14. Then, the optical filter 13 changes the light transmittance depending on the transmitting place so that the light emitted by each fluorescent lamp 12 can be converted into bright and dark light or bright and dark light in which the change from dark to bright is repeated. It is configured differently. That is, in this embodiment, the transmittance is repeatedly changed from a small value to a large value only in the Y direction of the X and Y directions orthogonal to each other shown in FIG. As shown in FIG. 3, light and dark light in which the change from dark to light is repeated at a predetermined light and dark gradient along the Y direction is formed, and this light and dark light is applied to the coating surface 1a of the vehicle body 1. It has become.

The diffusing screen 14 diffuses the light transmitted through the optical filter 13 to diffuse the light on the coating surface 1a of the vehicle body 1.
It is for evenly irradiating bright and dark light.

In the surface condition inspection device 2 constructed as described above, the defect inspection work is started as the painted vehicle body 1 is carried into the coating station S. That is, the robot device 4 is controlled by the robot controller 9 so that the light irradiating means 5 and the CCD camera 6 are kept at a constant interval, and these are secured at an appropriate distance from the coating surface 1a. In this state, it is moved along the coating surface 1a. Then, at that time, by the light irradiation means 5,
As shown in FIG. 4, a relatively wide coating surface 1a covering the field of view F of the CCD camera 6 is irradiated with bright / dark light 5a in which the change from dark to bright is repeated continuously in the Y direction.
Therefore, a light irradiation area having a change in brightness in which the change from dark to light is repeated is formed on the coating film surface 1a, and the CCD camera 6 that receives the reflected light from the light irradiation area has a structure shown in FIG. As shown in, a light-receiving image 15 with light and dark that changes from dark to bright in the direction indicated by arrow Y1 corresponding to the direction Y of change of the dark-light 5a is created.

In FIG. 5, reference numeral 1 indicates a dark-to-bright transition region in the bright-dark light 5a in which the transition from dark to bright is repeated, and the line density in each region l is The coarser the color, the higher the lightness, and the denser the line, the lower the lightness.

Therefore, if there is a defect in the light irradiation region of the coating surface 1a of the vehicle body 1, the brightness of the defect portion will be changed according to the shape of the defect by the bright / dark light 5a from the change region corresponding to the defect. For example, in the case of the convex defect 16 as shown in FIG. 4, as shown in FIG. 5, in the one change region 1 in the light-receiving image 15 where dark changes to bright, the dark portion 16 is formed on one side.
A convex defect portion 16 'in which a' changes from dark to bright in which the bright portion 16b 'is adjacent to the other side is recognized,
Further, in the case of the concave defect 17 as shown in FIG. 4, as shown in FIG. 5, a bright portion 17a ′ is provided on one side in one change region 1 in the light-receiving image 15 where light changes from dark to bright. A concave defect portion 17 'in which the dark portion 17b' is adjacent to the other side portion and changes from light to dark is recognized.

Then, the CCD camera 6 outputs to the image processor 10 a video signal which changes in accordance with the change in the brightness of the received light image. This image processor 1
In No. 0, the image processing is performed to detect the position coordinates, the shape and the size of the coating defect, and these are stored in the memory in the host computer 8. Then, at the time of repairing the coating defect, the stored contents in the memory are taken out, and a predetermined repair operation according to the type of the defect is executed.

Next, the coating defect detection operation by the image processor 10 will be described in more detail with reference to the flow chart shown in FIG. 6. First, in step S1, the received light image 15 created by the CCD camera 15 is captured. Along with the original image A having a waveform showing the lightness change in the light-receiving image 15 shown in FIG. 7, the light-receiving image 15 shown in FIG. 8 is scanned in the X direction orthogonal to the light-dark change direction Y to obtain a degree of light-dark change. The image B in which the differential value indicating is displayed is created. Then, in step S2, the original image A and the image B are combined to create an emphasized image C in which the defective portions indicated by (d) and (e) are emphasized in each image, and the defective portion is created. (F) is emphasized and step S3
In step S4, the coordinates of the defect position, the defect type, and the size are calculated from the emphasized image C, and then step S4 is performed.
Then, when the coating defect is detected by outputting the defect data to the host computer 8, the light-receiving image 15 is scanned in the direction X orthogonal to the light-dark change direction Y, and the differential value of the lightness change is calculated. If there is no defect on the scanning line, the differential value is always 0. As a result, even when the above-mentioned differential value is added to the light-dark data obtained from the light-receiving image 15, it is possible to surely prevent the situation in which the entire lightness level rises and the maximum lightness portion exceeds the calculation processing limit. Therefore, the surface condition can be detected for the entire area of the surface to be inspected, which is illuminated with the bright and dark light 15a, and the change in the brightness of the defective portion is emphasized, so that the inspection accuracy is improved. become.

[0018]

As described above, according to the present invention, the light-receiving image is scanned in the direction orthogonal to the light-dark change direction to calculate the differential value of the lightness change, and the defect is present on the scanning line. If there is no differential value, the differential value is always 0, and even when the differential value is added to the light-dark data obtained from the light-receiving image, the overall brightness level rises and the maximum brightness part reaches the calculation processing limit. As a result, it is possible to surely prevent the situation where the light intensity is exceeded, so that it is possible to accurately detect the surface condition of the entire area of the surface to be inspected irradiated with the bright and dark light and to emphasize the change in the brightness of the defective portion. As a result, the inspection accuracy is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a surface state inspection device.

FIG. 2 is an exploded perspective view of a light irradiation unit.

FIG. 3 is a graph showing a pattern of light and dark gradients.

FIG. 4 is an enlarged view showing an irradiation state and a light receiving state.

FIG. 5 is a partially enlarged view of a received light image.

FIG. 6 is a flowchart showing a defect inspection operation.

FIG. 7 is a diagram of an original image showing a state of brightness change.

FIG. 8 is a diagram of an image showing a differential value.

FIG. 9 is a diagram showing an emphasized image.

FIG. 10 is a diagram of an original image showing a conventional state of brightness change.

FIG. 11 is a diagram of an image showing a conventional differential value.

FIG. 12 is a diagram showing a conventional emphasized image.

[Explanation of symbols]

 1 vehicle body 1a coating film surface 2 surface condition inspection device 5 light irradiation means 5a bright and dark light 6 CCD camera 8 host computer 10 image processor 15 light receiving image 16 and 17 coating defects

Claims (1)

[Claims] 1. A surface to be inspected is irradiated with light from a light irradiation means,
A surface condition inspection method for capturing a reflected light from the surface to be inspected to create a received light image, and inspecting a surface condition of the surface to be inspected based on a change in brightness in the received light image, the method comprising: Irradiate the inspection surface with light and dark light that changes from dark to light, create light and dark data indicating the lightness change in the light-receiving image, and scan the light-receiving image in a direction orthogonal to the light-dark change method. A surface state inspecting method, wherein a differential value of a change in brightness is obtained, and the differential value is combined with the brightness data to emphasize the change in brightness and inspect the surface state of the surface to be inspected.