JPH04109106A - Surface defect inspecting device - Google Patents

Abstract

PURPOSE:To detect a defect existing on an inspected face including a curved face efficiently and correctly with no breakaway of the camera visual field by feeding only the reflected light from the inspected face of the light sent from the light source of a light radiating means in the region corresponding to the camera visual field of a video signal generating means. CONSTITUTION:In the painting defect inspection by a light radiating means 23 and a CCD camera 24, a robot controller 32 is driven by the command given by a host computer 31. The signal of the controller 32 is sent to a robot device 21. An actuator stored in the device 21 is operated, and the device 21 moves the means 23 and camera 25 so that the means 23 and camera 24 trace the surface of a vehicle body 26. The luminous intensity of the light sent from light sources of the means 23 can be controlled to be gradually changed in optional directions of X, Y-coordinates by a light radiating means controller 34 when it receives the control signal from the computer 31.

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 had to find minute defects on the paint surface, which placed a heavy burden on the inspector's nerves and forced him to perform physically demanding work.

In view of these circumstances in inspection of paint defects, light is superimposed onto the surface to be inspected of an object, the reflected light is projected onto a screen, and surface defects on the surface to be inspected can be detected from the sharpness of the projected image. A surface inspection device for automatic detection has been proposed (see, for example, Japanese Patent Laid-Open No. 62-233710).

If this surface inspection device is applied to detect 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.

(Problem to be Solved by the Invention) By the way, when applying the above-mentioned surface inspection technique using light irradiation to automatic inspection of car body coating, as shown in FIG. Light source 2 is applied to this coating surface 1.
A linear (or spot-like) light is irradiated from the T-film surface to the camera view 1Ili' of the video camera 3, which will be described next.
Create a light-resolving area that is sufficiently smaller than F, and proceed from here]
It is conceivable that the device is a device in which the video camera 3 receives the t-light emitted from the irradiation area.

In this device, the light-receiving image created by the video camera 3 is as shown in FIG. The irradiated area is captured as a bright line image 6. If there is a paint defect 7 (see Figure 7) in this light irradiation area, the direction of specular reflection of the light changes at the defect 7 of the coating, and if there is no defect 7, the light will be reflected normally. The light that should have entered the camera field of view F is now in the camera field of view F.
I can't get into it. Therefore, a black defective portion 7 (see FIG. 8) appears in the bright line image 6 described above.

Therefore, the defective portion 7 can be detected by identifying the defective portion 7 that appears black using image processing technology. Further, according to this device, since the coating surface 1 is irradiated narrowly in a linear manner, the amount of irradiated light is small, and the direction of specular reflection of the light incident on the light irradiation area changes 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, making it possible to detect even minute defects.

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 defective part 7 that can be captured by the video camera 3 is the light irradiation area (i.e., the light reception image Since it is only inside or near the line image 6) in 5, it is not 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.

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. 7 along the surface of the vehicle body using a robot device (not shown). .

However, in this case, since the vehicle body consists of many curved surfaces, if the inspection point moves to these curved surfaces, the linear irradiation shape formed on the vehicle body surface by the light source 2 will be distorted. Therefore, the line image 6 in the light-receiving image 5 of the video camera 3 is also
As shown in the figure, there will be distortion, and in extreme cases, the camera will deviate from the field of view F.

In order to solve the above-mentioned difficulties, as shown in Fig. 10, the coating surface 1 is illuminated widely by a light source 2' in an area equal to or larger than the camera field of view F, and this wide light irradiation area is It is conceivable to capture the image using video camera 3.

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

For example, the light L2 from the light source 2' is reflected by the coating surface 1, and the reflected light enters the light receiving surface of the video camera 3. Assuming that there is no defect 7 in the light irradiation area, the amount of light entering the light receiving surface is The same is true for the portion , so the received light 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 source 2' widely irradiates the coating surface 1 as described above, the light L3 from other parts of the light source 2'. 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, when the defective parts 7, 7 are minute, it becomes difficult to see a difference in brightness between the defective parts 7, 7 and the other parts, and it is difficult to identify the defective parts 7, 7 even with image processing. become unable.

An object of the present invention is to provide a surface defect inspection device that can efficiently and accurately detect defects existing on a surface to be inspected including a curved surface without deviation of the camera field of view from the light irradiation area of the surface to be inspected. It is.

(Means for Solving the Problems) Therefore, the present invention irradiates the surface to be inspected with light emitted from a light irradiation means, and receives the reflected light from the surface to be inspected by a video signal generating means. In a surface defect inspection apparatus that converts a light-receiving image of a light irradiated area of a surface into a video signal and detects defects existing on the surface to be inspected from the video signal, the video signal generating means has a camera field of view that is A light irradiation means having a large light irradiation area and irradiating the surface to be inspected with a large number of light sources arranged in a Mad Nox shape with respect to the light emitting surface, and a light irradiation means receiving a control signal from the outside and emitting light from each of the light sources. a light irradiation control means for individually changing at least one of the luminous intensity or wavelength of the light; and a predetermined
A control signal for gradually changing at least one of the luminous intensity or the wavelength of the light emitted from the light source of the light irradiation means in at least two directions of drifting is output to the light irradiation control means, and the camera is controlled in each of the two directions. Detecting at least one of the brightness or wavelength of light incident on at least two different points whose positions are known in the field of view, and detecting the position on the xy coordinates of the light source corresponding to each of these points from the data. , image information processing means for calculating the area of the light source of the light irradiation means that matches the camera field of view from the positions of these light sources, and detecting the surface defect by causing the light source in this area to emit light. .

(Function) The image information processing means corresponds to at least two points whose positions are known within the field of view of the camera on the xy coordinates set in advance on the light exit surface of the light irradiation means when inspecting for surface defects. The position of the light source of the light irradiation means is detected. From the positions of these light sources on the xy coordinates, the image information processing means
A light source in an area that matches the camera field of view is detected, and a control signal for causing the light source in this area to emit light is output to the light irradiation control means. Therefore, only the light reflected from the surface to be inspected from the light source in the area corresponding to the field of view of the camera always enters the video signal generating means.

(Effects of the Invention) According to the present invention, only the reflected light from the inspected surface of the light emitted from the light source of the light irradiation means in the area corresponding to the field of view of the camera always enters the video signal generation means. In addition, the camera field of view does not deviate from the light irradiation area of the surface to be inspected, and no light from other sources enters the video signal generation means, so that the surface to be inspected, including curved surfaces, is It is possible to efficiently and accurately detect defects existing in the camera using the entire field of view of the camera.

(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, the car body painting inspection stage 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 on 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 light irradiated by the coating film surface 27 on the surface of the vehicle body 26
The light is reflected by the beam 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 lohosoto controller 32 is driven by the command given by the controller. Then, the resulting signal from the Rohonoto controller 32 is sent to the robot device 21.

The robot device 21 operates a built-in actuator (not shown), and thereby the robot device 21
The light irradiation means 23 and the CCD camera 24 are arranged so that the light irradiation means 23 and the CCD camera 24 trace the surface of the vehicle body 26.
Move the D camera 24.

As shown in FIG. 2, the light irradiation means 23 includes a large number of light sources 42 such as tungsten lamps inside a box 41.
42. ...or a matrix-like device. This light irradiation means 23 includes a large number of light sources 42, 42.
．． For example, as shown in FIG. 2, xyX coordinates are set in advance, with the y-axis and the y-axis set in the row and column directions of the array of light sources 42° 42, . . . has been done.

In response to a control signal from the host computer 31 shown in FIG. It can be controlled to gradually change in the direction of .

All the light sources 42, 42 of the light irradiation means 23. The light irradiation area S (see FIGS. 3(a) and 3(b)) of the coating surface 27 of the vehicle body 26 that is irradiated by the light is larger than the camera field of view F of the CCD camera 24.

When inspecting surface defects, the light irradiation means] controller 34 receives a control signal from the host computer 31 and, as shown in FIG. 3(a), for example, as shown in FIG. With respect to the X-coordinate of the light sources 42.42., which have the same X-coordinate value. The luminous intensity of each light source 42 (see FIG. 2) of the light irradiation means 23 is controlled so that the luminous intensity at points having different X coordinate values gradually changes. In this state, the image of the light irradiation area S is CC
The image is captured by the D camera 24.

At this time, each luminance data of at least two points whose positions are known in the camera field of view F shown in FIG. are input to the host computer 31 from the light sources 42 (second
(see figure) each X coordinate (row of light sources 42, 42, . . . arranged in a matrix) is calculated.

Then, the light irradiation means] controller 34, in response to a control signal from the host computer 31, activates its light sources 42, 42 .・The light and dark direction of 90
The light intensities of the light sources 42, 42°, etc., which have the same X coordinate value for all the X coordinates set on the light exit surface 43 by rotating the phase of the light source 42, 42°, etc.
The luminous intensity of each light source 42 (see FIG. 2) of the light irradiation means 23 is controlled so that the luminous intensity at a point having a coordinate value changes gradually. In this state, an image of the light irradiation area S is captured by the CCD camera 24.

At this time, each luminance data of the vertices P1 and P on the semidiagonal line of the camera field of view F shown in FIG. 4(b) is inputted to the host computer 31 from the image processing processor 33 shown in FIG. Light 14 corresponding to
2 (see FIG. 2) (column of light sources 42, 42, . . . arranged in a matrix) is calculated.

As a result, the positions of the light sources 42 and 42 corresponding to the vertices P, , P, of the semi-diagonal line, which are known points on the camera field of view F, are determined on the Xl' coordinates.

Based on this positional information and the known positional information in the camera field of view F of the vertices P, P2 of the semi-diagonal line, the host computer 31 selects a camera within the light irradiation area S to be irradiated by the light irradiation means 23. Light source 42 in the area matching field of view F. 42. Calculate the position of...

The light sources 4242, . Detected.

5(a) and 6(a) show the case where the coating surface 27 has a convex defect 11, and FIG. 5(b) and FIG. 6(b) show the case where the coating surface 27 has a convex defect 11. A case with a concave defect portion 11 is shown.

The light irradiation means 23 is the light irradiation means shown in FIG.
4, the luminous intensity of the light emitted from the light emitting surface 43 of the light emitting means 23 (represented by the length of line m) or the arrow A of this emitting surface 43 is determined. At this time, the luminous intensity is changed from strong to weak in the direction indicated by arrow A2 along one side of the square camera field of view F of the CCD camera 24.
The luminous intensity of each light source 42 of the light irradiation means 23 shown in the figure is controlled.

As a result, the coating surface 27 has a
A light irradiation area S having a change in illuminance is generated in the direction corresponding to the arrow A1. As already mentioned, this light irradiation area S matches the camera field of view F of the CCD camera 24.

In such a state, if a defective portion 11 occurs on the coating surface 27, the direction in which the light from the light irradiation means 23 is regularly reflected by the defective portion 11 changes. Due to the change in the direction of specular reflection of this light, the light reception image 12 of the CCD camera 24 shows the defective part 1 with the illuminance uniformly changing in the direction indicated by arrow A.
Unlike the other parts, the screen does not change as shown in the brightness change state of 1.

As shown in FIG. 5(a), the defective portion 11 is
In the case of a convex shape, the light from the position 13 of the output surface 43 of the light irradiation means 23' with high luminous intensity mainly hits the surface 11a of the defective part 11 facing the output surface 43, and the direction of regular reflection changes. Then, a part of it enters the CCD camera 24. However, the defective portion 11 regarding the exit surface 43
Only the light from the position 14 where the luminous intensity of the output surface 43 is relatively low enters the rear surface 11b of the CCD camera 24.
, almost no reflected light from the rear surface 11b of the defective portion 11 enters.

Therefore, the light-receiving image 12 of the CCD camera 24 is
As shown in Figure (a), if the defective part 11 is convex,
In the direction indicated by the arrow A from the bright part to the dark part of the received light image 12 of the CCD camera 24, the defective part 11 first becomes brighter than other parts, and after passing this bright part, it becomes darker than the other parts.

When the defective part 11 is concave, the light from the position 13 of the light emitting surface 43 of the light irradiating means 23 having a high luminous intensity mainly hits the surface 11c of the defective part 11 on the side opposite to the emitting surface 43. The direction of specular reflection changes, and a part of it enters the CCD camera 24. However, only the light from the position 14 where the luminous intensity of the exit surface 43 is relatively low enters the surface lid of the defective portion 11 opposite to the surface lie, and C
The CD camera 24 has the surface 11 on the opposite side of the defective part 11.
Almost no light enters from d.

Therefore, the light-receiving image 12 of the CCD camera 24 is
As shown in Figure (b), if the defective part 11 is concave,
In the direction indicated by arrow A from a bright area to a dark area in the received light image 12 of the CCD camera 24, the defective part 11 first becomes darker than other parts, and after passing this dark part, it becomes brighter than other parts.

The video camera 15 outputs a video signal that changes in accordance with changes in the brightness of the received light image 12 to the image processor 33 shown in FIG.

When this video signal is input to the image processing processor 33, the image processing processor 33 detects C due to the presence of the defective portion 11.
A scanning line of the video signal in which the video signal output from the CD camera 24 is processed and its value, for example, a differential signal of this video signal exceeds a preset value, a timing at which the differential signal exceeds the threshold value on this scanning line, Then, a change in the sign of the differential signal near this timing is detected.

As a result, the position of the defective portion 11 within the light-receiving image 12 and the uneven state of the defective portion 11 are detected. This detection take 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 carried out according to the unevenness of the paint defect 11 existing on the painted surface 27 of the vehicle body 26, and as described below, when the defect 11 is convex, the protruding portion is If the defective portion 11 is a concave shape, the paint film is scraped off over a relatively wide area including the defective portion.

This repair can be performed manually or automatically by the robot device 21 or a repair robot device (not shown) provided separately.

From the above, even if the coating surface 27 is illuminated in a planar manner, it is possible to eliminate light halation and capture the defective portion 11 as a clear image with a difference in brightness from the surrounding area.

In addition, as described above, the value obtained by processing the video signal output from the CCD camera 24 due to the presence of the defective portion 11, for example, the scanning line of the video signal where the differential signal of this video signal exceeds a preset value, and the differential signal on this scanning line. By detecting the timing at which the signal exceeds the threshold value and the change in the sign of the differential signal near this timing, the position of the defective part 11 in the received light image 12 and the defective part 1 can be determined.
1 can be detected, and even if the defective part 11 is minute, it can be reliably recognized as the defective part 11.

In the above, the light irradiation means 23 has its light sources 42°42, .
An embodiment has been described in which the defective portion 11 is detected by gradually changing the luminous intensity of the light sources 42, 42, . Even if the color (wavelength) of the light emitted from the light source in a column is the same, even if the color (wavelength) of the light source in a different row or column changes gradually, the color (wavelength) of the light emitted from the light source in the column will change due to the change in the order of the color of the light at the defective part 11. , the defective portion 11 can also be detected.

In addition, although the above example describes the embodiment in which the defective portion 11 is detected by the image processing processor 33, the CC
It is also possible to detect the defective portion 11 and record it in the recording device by having the inspector monitor the video signal from the D camera 24 on a monitor television.

The present invention can be widely applied not only to an inspection device for coating defects on an automobile body but also to a surface defect inspection device.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an embodiment of the surface defect inspection device, Fig. 2 is a perspective view of the light irradiation means, and Figs. 3(a) and 3(b) are explanations of detection of the camera field of view position, respectively. Figure 4(a) and Figure 4(b) are respectively similar to Figure 3(a).
) and an explanatory diagram of the camera field of view in Fig. 3(b), Fig. 5(
Figures a) and 5(b) are explanatory diagrams of surface defect detection, respectively, and Figures 6(a) and 6(b) are illustrations of the camera when there are convex and concave defects on the surface to be inspected, respectively. An explanatory diagram of the screen, Fig. 7 is an explanatory diagram of a conventional surface defect inspection device, Fig. 8 is an explanatory diagram of an image obtained by the camera of the surface defect inspection device of Fig. 7, and Fig. 9 is an explanatory diagram of the surface to be inspected which is a curved surface. FIG. 10 is an explanatory diagram of another conventional surface defect inspection device. S...Light irradiation area, F Camera field of view 11...Defect area, 12 - Light receiving screen 13...Position with high luminous intensity. 14...Position with low luminosity. 20...Paint inspection station. 21... Robot device, 23... Light irradiation means. 24... CCD camera, 25... Support metal fittings, 26.
...Vehicle body. 27... is a membrane surface, 31... is a host computer. 32. Robot controller. 33... Image processing processor. 34...Light irradiation means] controller, 42...Light source. 43...Light exit surface. Patent Applicant Mazda Motor Corporation Agent Patent Attorney Haka Aoyama 1 person @2 Figure 3 + al t'2 Figure 4 Figure 5 Figure 6 (al!3 (bl Figure 41'!1) (bl Figure 5 Figure 6 + bl Doro Figure 8 Figure 7 Figure 9 Figure 10

Claims (1)

[Claims] (1) Irradiating the surface to be inspected with light emitted from the light irradiation means,
The reflected light reflected from the surface to be inspected is received by a video signal generating means, the light-receiving image of the light irradiation area of the surface to be inspected is converted into a video signal, and the defects present on the surface to be inspected are detected from this video signal. The defect inspection device has a light irradiation area larger than the camera field of view of the video signal generating means, and a large number of light sources are arranged in a matrix on the light exit surface to illuminate the surface to be inspected. a light irradiation means; a light irradiation control means for individually changing at least one of the luminous intensity or wavelength of the light emitted from each of the light sources in response to a control signal from the outside; and light emission from the light irradiation means when inspecting a surface defect. outputting a control signal to the light irradiation control means to gradually change at least one of the luminous intensity or the wavelength of the light emitted from the light source of the light irradiation means in at least two directions of xy coordinates predetermined on the surface; detect at least one of the brightness or the wavelength of light incident on at least two different points whose positions are known within the field of view of the camera for each direction, and from the data, detect on the xy coordinates of the light source corresponding to each of these points; image information processing means for detecting the positions of the light sources, calculating from the positions of these light sources a region of the light source of the light irradiation means that matches the camera field of view, and detecting the surface defect by emitting light from the light source in this region. A surface defect inspection device characterized by: