JPH04109153A - Surface defect inspecting device - Google Patents

Abstract

PURPOSE:To simply and correctly detect a defect section difficult to detect by changing at least one of the luminosity and wavelength of the light outgoing from a light source in at least two directions, and detecting the information of the defect section via the reflected light from the inspected face in each direction. CONSTITUTION:A light radiating means 23 and a CCD camera 24 serving as a video signal generating means are fitted to the tip arm 22 of a robot device 21. The means 23 is switched to the first position and the second position rotat ed by 90 deg. with respect to the first position, for example, by a light radiating means controller 34. The inspection of a defect section 28 is performed at the first position of the means 23. The illuminance on the light radiation region is gradually changed when the means 23 is located at the first position, and it is photographed by the camera 24. The change of the illuminance on the light radiation region when the means 23 is located at the second position is photographed by the camera 24. The image photographed by the camera 24 is converted into a video signal and outputted to an image processor 33. The processor 33 sends the processed data to a host computer 31 for analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface defect inspection device that irradiates a surface to be inspected with light and detects the presence or absence of surface defects such as paint defects from the reflected light.

(Prior Art) In a manufacturing line for vehicles such as automobiles, painting of vehicle bodies is generally performed at a painting station provided in the manufacturing line.

By the way, inspection for paint defects after painting a vehicle body has conventionally been carried out by human visual inspection. In this inspection, the inspector must find minute defects on the paint surface, which places a heavy burden on the inspector's nerves and also forces them to perform physically demanding work.

In view of these circumstances in inspection of paint defects, we have developed a system that irradiates light onto the surface of an object to be inspected, projects the reflected light onto a screen, and automatically detects surface defects on the surface to be inspected based on the sharpness of the projected image. A surface inspection device has been proposed that detects the surface of the surface (see, for example, Japanese Patent Laid-Open No. 62-233710).

If this surface inspection device is applied to the detection of paint defects on vehicle bodies, the above-mentioned paint defects can be automatically detected, and the inspector can be freed from the conventional visual inspection work.

(Problems to be Solved by the Invention) By the way, when applying the above-mentioned surface inspection technology using light irradiation to automatic inspection of car body coatings, as shown in FIG. This coating surface 1 is irradiated with linear (or spot-shaped) light from the light source 2 to create a light irradiation area on the coating surface 1 that is sufficiently smaller than the camera field of view F of the video camera 3. A device that receives reflected light from the cervical region using a video camera 3 may be considered.

In this device, as shown in Fig. 5, the light-receiving image created by the video camera 3 is reflected from the light irradiation area of the coating surface 1 and enters the camera field of view F (see Fig. 4).
The light-irradiated area of the coating surface 1 is captured as a bright line image 6 in the light-receiving image 5 which is dark as a whole. If there is a paint defect 7 (see Figure 4) in this light irradiation area, the direction of specular reflection of the light changes at this paint defect 7, and if there is no defect 7, the light will be reflected normally. As a result, the light that should have entered the camera field of view F no longer enters the camera field of view F. Therefore, a black defective portion 7 (see FIG. 5) appears in the above-mentioned bright line image 6.

Therefore, the defective part 7 can be detected by identifying the defective part 7 that appears in black (image processing technology).Furthermore, according to this device, since the coating surface 1 is irradiated narrowly in a linear manner, the irradiation The amount of light is small, and the direction of specular reflection changes due to the light incident on the light irradiation area due to the defect 7, and the video camera 3
The amount of light entering can be clearly differentiated between the defective portion 7 and the non-defected portion, and even minute defects can be detected.

However, with narrow light irradiation as in the above device, the light irradiation area is too small with respect to the camera field of view F, and on the other hand, the defect 7 that can be captured by the video camera 3 is the light irradiation area (i.e., the light reception image Since there is no image inside or near the line image 6) in 5, it is always possible to perform surface inspection using only a part of the camera field of view F, resulting in a problem of a lack of inspection efficiency.

In addition, if the defect 7 is not a spot-like one as described above, but the coating surface 1 is gently raised and continuous over a certain length, the longitudinal line image 6 If the direction matches the length direction of the defective part 7, the defective part 7 is only gently raised, so
Even if a change occurs in the direction of specular reflection of light due to the defective portion 7, it is difficult to clearly differentiate the amount of light entering the video camera 3 between the defective portion 7 and the non-defective portion, making it difficult to detect the defective portion 7.

Furthermore, when the surface to be inspected is the body of a vehicle such as an automobile, the inspection is performed while moving the light source 2 and video camera 3 shown in FIG. 4 along the surface of the vehicle using a Rohonoto device (not shown). . However, in this case, since the car body consists of many curved surfaces, if the inspection point moves to these curved surfaces, the linear illumination shape formed on the car body surface by the light source 2 will be distorted. The line image 6 in the received light image 5 of No. 3 is also distorted as shown in FIG. 6, and in severe cases it will deviate from the camera field of view F.

For this reason, it is difficult to properly inspect the coating surface 1 on the body of a vehicle such as an automobile, and the control of the Rohonoto device is complicated in order to ensure that the line image 6 always falls within the camera field of view F. There was a problem.

In order to solve the above-mentioned difficulties, as shown in Fig. 7, the coating surface L is irradiated over a wide range (equivalent to or larger than the camera field of view F) by the light source 2', and this wide light irradiation is carried out. It is conceivable that the area is captured by a video camera 3.

However, when the coating surface 1 is irradiated widely in this way, the amount of irradiated light increases significantly, which causes light halation at the defective areas 7, making it impossible for the video camera 3 to clearly capture the minute defective areas 7. .

For example, the lights L+ and Lx from the light [2' are reflected by the coating surface I, and the reflected light enters the light-receiving surface of the video camera 3, or if there is no defect 7 in the light irradiation area, it enters the light-receiving surface. Since the amount of light is the same in both parts, the light-receiving image is entirely bright.

On the other hand, if there is a defect 7 in the light irradiation area, the direction of specular reflection of the light incident on the light irradiation area changes at this defect 7, and the amount of incident light on the light receiving surface portion corresponding to the defect 7 changes. It should decrease and appear as a black dot in the received light image.

However, since the light #2' widely irradiates the coating surface 1 as described above, the light L3. L
, the light is reflected by the defective parts 7, 7 and enters the light-receiving surface where the amount of light is supposed to decrease.

Therefore, the brightness in the received light image does not decrease significantly,
Therefore, if the defect 7.7 is minute or if the coating surface 1 is gently raised and continuous over a certain length, the defect 7.7 will cause a change in the direction of specular reflection. Also, a difference in brightness between the defective portions 7, 7 and the non-defective portions becomes less likely to occur, and the defective portions 7, 7 cannot be identified even by image processing.

An object of the present invention is to provide a surface defect inspection device that can easily and accurately detect defects that are difficult to detect, such as defects that exist on a surface to be inspected, including curved surfaces, and defects that have a gentle bulge. That's true.

(Means for Solving the Problems) Therefore, the present invention provides a light irradiation means for irradiating a surface to be inspected by disposing a plurality of light sources on a planar light emission surface;
a light irradiation control means for changing at least one of the luminous intensity or the wavelength of the light emitted from the light emitting surface in any direction of the light emitting surface of the light emitting means; a video signal generating means for converting a light-receiving image captured by the light-receiving screen in the light irradiation area into a video signal; The light irradiation means is changed in at least two directions, information on the defective portion existing on the surface to be inspected is detected from the video signals output from the video signal generating means in each direction, and information on the defective portions detected for each video signal is detected. The present invention is characterized by comprising an image information processing means that integrates the detection information and detects the defective portion.

(Function) The light irradiation control means changes at least one of the luminous intensity of the light source or the wavelength of the light emitted from the light source in any direction of the light emission surface of the light irradiation means.

The image information processing means outputs each signal from the video signal generation means when at least one of the luminous intensity or the wavelength of the light emitted from the light source is changed in at least two directions of the light output surface of the light irradiation means. Information about defects present on the surface to be inspected is detected from the video signal. Then, the image information processing means integrates this detection information and detects a defective portion.

(Effects of the Invention) According to the present invention, at least one of the luminous intensity or the wavelength of the light emitted from the light source is changed in at least two directions, and information on the defective portion is detected from the light reflected from the surface to be inspected in each direction. However, the results are integrated to detect the defective part, so even if the defective part cannot be detected by reflected light in one direction, it is possible to detect the defective part by reflected light in other directions. Even defects that are difficult to detect can be detected easily and reliably.

(Hereinafter, blank spaces) (Example) The present invention will be described in detail below with reference to the accompanying drawings.

First, FIG. 1 shows the overall configuration of one embodiment in which the surface defect inspection apparatus according to the present invention is applied to inspection of paint defects on the body of an automobile.

As shown in Figure 1, a car body paint inspection station 20
is equipped with a robot device 21 mounted on a pedestal B.

A light irradiation means 23, a CCD camera 24 as a video signal generation means, and a support metal fitting 25 are attached to the robot device 21 at its tip arm 22. These light irradiation means 23 and CCD camera 2 of the robot device 21
4 is the vehicle body 2 brought into the paint inspection station 720.
The coating surface 27 of No. 6 is traced, and at that time, the light irradiation means 23
The coating surface 27 on the surface of the vehicle body 26
The light is reflected and enters the CCD camera 24.

In addition, in such a coating defect inspection using the light irradiation means 23 and the CCD camera 24, the host computer 31
The controller 32 is driven by the command given by the controller 32. The resulting signal from the controller 32 is sent to the robot device 21.

The above robot device! Reference numeral 21 operates a built-in actuator (not shown), and thereby the robot device 2
1 is a light irradiation means 23 and a CCD camera 24 or a vehicle body 26
These light irradiation means 23 and C
Move the CD camera 24.

As shown in FIG. 2(a), the light irradiation means 23 includes a plurality of fluorescent lamps 42 (particularly fluorescent lamps 42) inside the hook 41.
It is not limited to 2. ) is installed.

An optical filter 43, which will be described next, is installed on the entire surface of these fluorescent lamps 42, and a diffusion screen 44 is also attached to cover the entire surface of this optical filter 43. This diffusion screen 44 is used to diffuse the light transmitted from the optical filter 43, and to prevent the fluorescent lamps 42 from appearing in areas with low luminous intensity due to the arrangement of the fluorescent lamps 42 at intervals. .

The optical filter 43 includes a light output surface 1 of the light irradiation means 23.
Regarding 3a, for example, as shown in Fig. 2(a), for all y coordinate values of the preset reference xyX coordinates, the transmittance of light at points having the same Gradually changes the degree of light transmission.

The light irradiation means 23 is a light irradiation means] controller 34 (
(see Figure 1), there is a first position that has the relationship shown in Figure 2 (a) above with respect to the reference XV coordinate, and a second position that is rotated, for example, by 90 degrees with respect to this first position. and the position.

Then, at the first position of the light irradiation means 23, light is irradiated onto the coating surface 27 of the car body 26 of the automobile shown in FIG.
As shown in Figure (a), the defective portion 28 is inspected.

That is, when the light irradiation means 23 is in the first position, the luminous intensity of the light emitted from the light emission surface 13a of the light irradiation means 23 changes in the xyX coordinate X-axis direction. In (a), the illuminance on the light irradiation area S of the light irradiation means 23 gradually changes in the direction shown by arrow A1. This is imaged by the CCD camera 24.

Similarly, when the light irradiation means 23 is in the second position, the luminous intensity of the light emitted from the light emission surface 13a of the light irradiation means 23 changes in the xyX coordinate X-axis direction.
In FIG. 3(b), the illuminance on the light irradiation area S of the light irradiation means 23 gradually changes in the direction indicated by arrow A. This is imaged by the CCD camera 24.

The image captured by the CCD camera 24 is converted into a video signal by the CCD camera 24, and this video signal is output to the image processing processor 33 shown in FIG.

The image processor 33 performs image processing and transmits the processed take to the host computer 31 for analysis.

The image processing and analysis thereof by the image processing processor 33 and the host computer 31 are performed, for example, as follows.

Now, if there is a defect 28 existing on the coating surface 27 of the car body 26 of FIG. 1, or if the coating surface 27 is gently raised,
It is assumed to be continuous over a certain length. and,
As shown in FIG. 3(a), it is assumed that the defective portion 28 extends in the direction in which the illuminance does not change in the light irradiation area S at the first position of the light irradiation means 23.

When this video signal is input to the image processing processor 33 when the light irradiation means is in the first position, the image processing processor 33 detects the CCD camera 24 due to the presence of the defective part 11.
A scanning line of the video signal in which the processed signal, for example, a differential signal exceeds a preset value, the timing at which the differential signal exceeds the threshold value 1 on this scanning line, and the timing near this timing. A change in sign of the differential signal is detected. As a result, the received light image 12
Identification information such as the position and shape of the defective portion 28 within the interior is obtained.

However, in this case, as described above, the defective portion 28 is located at the light irradiation area S at the first position of the light irradiation means 23.
Since it extends in the direction where there is no change in illumination, even if there is a change in the direction of specular reflection of light by the defective part 28, the defective part 2
It is difficult to see a difference in brightness between 8 and the other parts. Therefore, the reliability of the information such as the position and shape of the defective portion 28 obtained above is somewhat low.

Next, the light irradiation means 23 is rotated to the second position. At this time, when the video signal of the image captured by the CCD camera 24 is input to the image processing processor 33, the image processing processor 33 detects that the differential signal of the video signal output from the CCD camera 24 is A scanning line of the video signal exceeding a set value, a timing at which the differential signal exceeds the threshold value on this scanning line, and a change in the sign of the differential signal near this timing are detected. Thereby, identification information such as the position and shape of the defective portion 28 within the received light image 12 is detected.

At this time, the defective portion 28 is exposed to the light irradiation means 23 or the first
Since the light irradiation area S extends in the direction where the illuminance changes at the position, if there is a change in the direction of specular reflection of light due to the defective part 28, there will be a difference in brightness between the defective part 28 and the other part. clearly occurs.

Therefore, the reliability of the information such as the position and shape of the defective portion 28 obtained above is high.

' The image processing processor 33 uses information such as the position and shape of the defective part 28 obtained when the light irradiation means 23 is in the first position, and information obtained when the light irradiation means 23 is in the second position. The defective portion 28 is comprehensively detected by, for example, logically performing “OR” processing on information such as the position and shape of the defective portion 28.

The data of this detection result and the position of the tip arm 22 of the robot device 21 are stored in a memory.

At the time of repair, the repair is performed according to the contents of this memory. This repair can be carried out manually, but it is carried out daily using the robot device 21 or a separate repair robot device (not shown).

From the above, it can be seen that not only normal point or spot-like defects, but also the coating surface 2 of the automobile body 26 as shown in FIG.
Even in the case of a defective portion 28 that is only a gradual bulge, the defective portion 28 extending in any direction can be reliably treated by changing the direction of change in the luminous intensity of the light irradiation from the light irradiation means 23. Can be detected.

In the above embodiment, in order to change the direction of change in the luminous intensity of light irradiation from the light irradiation means 23 in two stages, the entire light irradiation means is
For example, as shown in Figure 2(b),
The hook 41 of the light irradiation means 23 is provided with a large number of light sources 45, 45, such as tungsten lamps, etc. ... are arranged in a matrix, and these light sources 45, 45 . The reference xy coordinates of the light irradiation means 23 may be changed in two directions, for example, the X-axis direction and the y-axis direction, by the controller 34 of the light irradiation means shown in FIG.

Furthermore, the direction of change in the luminous intensity of the light irradiation from the light irradiation means 23 is as follows:
If the defective part 28 is detected comprehensively based on the detection information of the defective part 28 in each stage, instead of being limited to two stages, the detection accuracy of the defective part 28 can be further improved.

The above has described an embodiment in which the luminous intensity of the light irradiation of the light irradiation means 23 is changed, or the color (wavelength) of the light emitted from the light irradiation means 23 is
Any multiple directions of the y-coordinate, such as the X-axis direction and
Even if the light is changed in the axial direction, the defective portion 28 can be detected more reliably without being affected by ambient light by changing the order of the colors of the light at the defective portion 28. In this case, the luminous intensity of each color of light may also be changed at the same time.

The present invention is not limited to an inspection device for coating defects on automobile bodies, but can be widely applied to surface defect inspection.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the surface defect inspection device, FIGS. 2(a) and 2(b) are explanatory diagrams showing the configuration of the light irradiation means, and FIG. 3(a) and FIG. 3(b) is an explanatory diagram of defect detection, FIG. 4 is an explanatory diagram of a conventional surface defect inspection device, and FIG. 5 is an explanation of an image obtained by the camera of the surface defect inspection device of FIG. 4. FIG. 6 is an explanatory diagram of an image obtained by a camera when the surface to be inspected is a curved surface, and FIG. 7 is an explanatory diagram of another conventional surface defect inspection apparatus. 20...Paint inspection station. 21... Robot device, 23... Light irradiation means. 24... CCD camera, 25... Support metal fittings, 26.
・Vehicle body. 27. Paint film surface, 28. Defect area. 31...Host computer. 32... Robot controller 2 33... Image processing processor. 34...Light irradiation means] Controller 41...Box, 42...Fluorescent lamp. 43... Light filter, 44... Diffusion screen. 45...Light source. Fig. 2 Fig. 2 (b) [ Fig. 3 (a) Fig. 3 (b) Fig. 4 Fig. 5 Fig. 6 Fig. 6''X/'6 Fig. 7≠---E-1

Claims (1)

[Claims] (1) A light irradiation means in which a plurality of light sources are arranged with respect to a planar light emission surface and irradiates the surface to be inspected, and light is emitted from the light emission surface in any direction of the light emission surface of the light irradiation means. a light irradiation control means for changing at least one of the luminous intensity or the wavelength of the light to be inspected; and a light receiving screen that captures the reflected light from the light irradiated area of the surface to be inspected; a video signal generating means for converting a received light image of the light into a video signal, and a video signal generating means for changing at least one of the luminous intensity or the wavelength of the light emitted from the light emitting surface in at least two directions of the light emitting means, and for each direction. image information processing means for detecting information on defective parts present on the surface to be inspected for each video signal outputted from the video signal, and for detecting the defective part by integrating the detection information on the detected defective parts for each video signal. A surface defect inspection device characterized by: