JP2892464B2 - Surface defect inspection apparatus and surface defect inspection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a surface defect inspection apparatus that irradiates a surface to be inspected with light and detects the presence or absence of a surface defect such as a coating defect from the reflected light.

2. Description of the Related Art In a production line of a vehicle such as an automobile, painting of a vehicle body is generally performed in a painting station provided in the production line.

By the way, inspection of paint defects after painting of a vehicle body has been conventionally performed by visual inspection by a human. In this inspection, the inspector must find a minute defect from the surface of the coating film, so that the inspector has a great nervous burden and has to perform physically demanding work.

In light of such circumstances in inspection of paint defects, light is irradiated to the surface to be inspected of an object, the reflected light is projected on a screen, and surface defects on the surface to be inspected are automatically determined from the sharpness of the projected image. There has been proposed a surface inspection apparatus capable of performing automatic detection (for example, see JP-A-62-233710).

If this surface inspection apparatus is applied to the detection of a paint defect on a vehicle body, the above-described paint defect can be automatically detected, and the inspector can be released from the conventional visual inspection work.

(Problems to be Solved by the Invention) When the above-described surface inspection technology by light irradiation is applied to an automatic inspection of vehicle body coating, as shown in FIG. The coating film surface 1 is irradiated with linear (or spot-like) light from the light source 2 to form a light irradiation area on the coating film surface 1 that is sufficiently smaller than the camera field of view F of the video camera 3 described below. An apparatus that receives the reflected light from the light irradiation area by the video camera 3 is conceivable.

In this device, the received light image created by the video camera 3 is as shown in FIG. 8, and the coating surface 1 is included in the overall dark received image 5 covering the camera field of view F (see FIG. 7).
Are illuminated as bright line images 6.
When there is a paint defect 7 (see FIG. 7) in the light irradiation area, the specular reflection direction of the light changes at the paint defect 7, and if the defect 7 does not exist, the light is reflected normally. As a result, light that should have entered the camera field of view F does not enter the camera field of view F. As a result, a black defective portion 7 (see FIG. 8) appears in the bright line image 6.

Therefore, the defective portion 7 can be detected by identifying the black defective portion 7 by the image processing technique. Further, according to this apparatus, since the coating film surface 1 is irradiated narrowly in a linear manner, the irradiation light amount is small, and the light incident on the light irradiation area changes the regular reflection direction at the defect portion 7, and the video camera 3 The amount of incident light is clearly different between the defective portion 7 and the other portion, so that a minute defect can be detected.

However, according to the narrow light irradiation as in the above-described apparatus, the light irradiation area is too small with respect to the camera field of view F, while the defective portion 7 that can be captured by the video camera 3 has a light irradiation area (that is, Since there is only the inside or near the line image 6) in the received light image 5, only the surface inspection using only a part of the camera field of view F can be always performed, and there is a problem that the inspection efficiency is lacking.

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 the video camera 3 of FIG. 7 along the surface of the vehicle with a robot device (not shown). .

However, in this case, since the vehicle body has many curved surfaces, when the inspection location moves to these curved surface portions, the linear irradiation shape formed on the vehicle body surface by the light source 2 is distorted. Therefore, the line image 6 in the light-receiving image 5 of the video camera 3 is also distorted as shown in FIG.

In order to solve the above-mentioned difficulties, as shown in FIG. 10, the coating surface 1 is illuminated widely by the light source 2 ′ in a range equal to or larger than the camera field of view F, and this wide light irradiation area is set. Can be captured by the video camera 3.

However, when the coating film surface 1 is irradiated widely as described above, the irradiation light amount is greatly increased, so that halation of light at the defective portion 7 occurs, and the video camera 3 cannot clearly detect the minute defective portion 7. .

For example, the lights L ₁ and L ₂ from the light source 2 ′ are reflected by the coating film surface 1, and the reflected light enters the light receiving surface of the video camera 3. Since the amount of incident light is the same in any part, the received light image is brighter on one side.

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

However, the light source 2 ', as described above, since the irradiated widely Nurimakumen 1, a light source 2' light L ₃ from the other parts of, L ₄
Is reflected by the defective portions 7, 7 and enters the light receiving surface portion where the amount of light should decrease.

Therefore, the brightness in the received image does not significantly decrease, and therefore, when the defective portions 7, 7 are minute, a difference in brightness between the defective portions 7, 7 and the other portions is less likely to occur, Defects 7, 7 cannot be identified even by image processing.

An object of the present invention is to provide a surface defect inspection apparatus capable of efficiently and accurately detecting a defect present on a surface to be inspected including a curved surface without deviation of a field of view of a camera from a light irradiation area of the surface to be inspected. It is.

(Means for Solving the Problems) For this reason, the present invention illuminates a surface to be inspected with light emitted from a light irradiating unit, and receives reflected light reflected from the surface to be inspected by a video signal generating unit to be inspected. In a surface defect inspection device that converts a received light image of a light irradiation area on a surface into a video signal and detects a defect existing on the inspection target surface from the video signal, A light irradiating unit having a large light irradiation area, and a plurality of light sources arranged in a matrix on a light emitting surface to irradiate the surface to be inspected; and light emitted from each of the above light sources upon receiving a control signal from the outside Light irradiation control means for individually changing at least one of the luminous intensity or wavelength of the light irradiation means, and the light irradiation means in at least two directions of xy coordinates predetermined on the light emitting surface of the light irradiation means at the time of surface defect inspection A control signal for gradually changing at least one of the luminous intensity or the wavelength of light emitted from the light source is output to the light irradiation control means, and at least two different points whose positions are known in the camera field of view in each of the two directions. Detects at least one of the brightness or wavelength of light incident on the light source, detects the positions on the xy coordinates of the light sources corresponding to these points from the data, and matches the camera view from the positions of these light sources. Image processing means for calculating the area of the light source of the light irradiation means and causing the light source in this area to emit light to detect the surface defect.

In the above-mentioned surface defect inspection apparatus, the light irradiation control means sets the same luminous intensity or wavelength of light emitted from the same row or column of light sources, and gradually changes the luminous intensity or wavelength of light emitted from different row or column of light sources. Preferably, it is adapted to be

According to another aspect of the present invention, a surface to be inspected is illuminated with light emitted from a light irradiating unit, and reflected light reflected from the surface to be inspected is received by a video signal generating unit, and the light on the surface to be inspected is received. In a surface defect inspection method in which a light reception image of an irradiation area is converted into a video signal and a defect existing on the inspection surface is detected from the video signal, the surface defect inspection method is larger than a camera field of view of a video signal generation unit. A light irradiating area, and irradiating the surface to be inspected with light irradiating means in which a large number of light sources are arranged in a matrix on a light emitting surface; At least one of the luminous intensity or wavelength of light emitted from the light irradiating means is individually changed in at least two directions of predetermined xy coordinates on the light emitting surface of the light irradiating means at the time of inspecting a surface defect. At least one of the luminous intensity or the wavelength of the light emitted from the light source is gradually changed, and at least one of the brightness and the wavelength of the light incident on at least two different points whose positions are known in the camera field of view in each of the two directions. From the data, the positions of the light sources corresponding to these points on the xy coordinates are detected, and from the positions of the light sources, the area of the light source of the light irradiation means that matches the camera field of view is calculated. The surface defect is detected by causing the light source in the region to emit light.

In the above surface defect inspection method, it is preferable that the luminous intensity or the wavelength of the light emitted from the light source in the same row or column is the same, and the luminous intensity or the wavelength of the light emitted from the light source in a different row or column is gradually changed.

(Operation) The image information processing means, at the time of inspecting a surface defect, detects light corresponding to at least two points whose positions are known in the camera field of view on the xy coordinate set in advance on the light emission surface of the light irradiation means. The position of the light source of the irradiation means is detected. From the positions of these light sources on the xy coordinates, the image information processing means detects a light source in an area that matches the field of view of the camera, and outputs a control signal for causing the light source in this area to emit light to the light irradiation control means. Therefore, the video signal generating means always includes
Only the reflected light from the inspection surface of the light of the light source in the area corresponding to the camera field of view is incident.

In the above-described surface defect inspection apparatus, the light irradiation control unit includes:
If the luminous intensity or wavelength of the light emitted from the light source in the same row or column is the same and the luminous intensity or wavelength of the light emitted from the light source in a different row or column is gradually changed, the luminous intensity at the defective portion Alternatively, a defective portion is detected by a change in the order of light colors.

In the above-described surface defect inspection method, as in the case of the above-described surface defect inspection apparatus, the video signal generating means always receives only the reflected light from the inspection surface of the light of the light source in the area corresponding to the camera field of view. Will be incident.

Further, in the surface defect inspection method, when the light intensity or wavelength of light emitted from the same row or column of light sources is the same, and the light intensity or wavelength of light emitted from a different row or column of light sources is gradually changed. In the method, a defective portion is detected by a change in the luminous intensity or the color order of light at the defective portion.

(Effects of the Invention) According to the present invention, only the reflected light from the surface to be inspected of the light emitted from the light source of the light irradiation means in the area corresponding to the camera field of view is always incident on the video signal generation means. ,
There is no deviation of the camera's field of view from the light irradiation area of the inspection surface, and no light is incident on the video signal generation means. The part can be efficiently and accurately detected using the entire camera field of view.

In the above-described surface defect inspection apparatus, the light irradiation control means may make the light intensity or wavelength of light emitted from the same row or column of light sources the same, and gradually change the light intensity or wavelength of light emitted from different row or column light sources. In the case of, since the defective portion is detected by a change in the luminous intensity or the order of the light color at the defective portion, the detection accuracy of the defective portion is improved.

In the above-described surface defect inspection method, similarly to the case of the above-mentioned surface defect inspection apparatus, it is possible to efficiently and accurately detect a defect existing on a surface to be inspected including a curved surface using the entire camera field of view. it can.

Further, in the surface defect inspection method, when the light intensity or wavelength of light emitted from the same row or column of light sources is the same, and the light intensity or wavelength of light emitted from a different row or column of light sources is gradually changed. Since the defective portion is detected by the change in the luminous intensity or the order of the light color at the defective portion, the detection accuracy of the defective portion is improved.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

First, FIG. 1 shows an overall configuration of one embodiment in which a surface defect inspection apparatus according to the present invention is applied to inspection of a coating defect of a car body.

As shown in FIG.
Is equipped with a robot device 21 on a pedestal B.

In the robot device 21, a light irradiating means 23 and a CCD camera 24 as a video signal generating means are attached to a tip arm 22 thereof via a support fitting 25. Robot equipment 21
The light irradiating means 23 and the CCD camera 24 trace the coating film surface 27 of the vehicle body 26 carried into the coating inspection station 20, and the light radiated by the light irradiating means 23 The light is reflected by the coating film surface 27 and enters the CCD camera 24.

In the coating defect inspection by the light irradiation unit 23 and the CCD camera 24, the robot controller 32 is driven by a command given by the host computer 31. And by that the robot controller
32 signals are sent to the robot device 21.

The robot device 21 operates a built-in actuator (not shown), whereby the robot device 21 causes the light irradiating means 23 and the CCD camera 24 to trace the surface of the vehicle body 26. Move 24.

The light irradiating means 23 includes a box as shown in FIG.
Numerous light sources 42, 42, ...
Are arranged in a matrix. The light irradiating means 23 has a light emitting surface 43 formed by a large number of light sources 42, 42,..., For example, as shown in FIG.
Xy with x and y axes set in row and column directions of array
The coordinates are set in advance.

The luminous intensity of the light emitted from each light source 42 of the light irradiating means 23 receives a control signal from the host computer 31 shown in FIG.
With 34, the xy coordinates can be controlled so as to gradually change in any direction.

The light irradiation area S of the coating surface 27 of the vehicle body 26 which is irradiated by all the light sources 42, 42,.
3 (b) 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, for example, as shown in FIG. 3 (a), assigns the same y-coordinate value to all the x-coordinates of the xy coordinates set on the light exit surface 43. The light intensity of each light source 42 (see FIG. 2) of the light irradiation means 23 is controlled such that the light intensity of the light sources 42, 42,. In this state, an image of the light irradiation area S is captured by the CCD camera 24.

At this time, at least two points whose positions are known in the camera field of view F shown in FIG.
Light source 42 to the luminance data of the vertices P ₁ and P ₂ is inputted from the image processing Purossessa 33 shown in FIG. 1 to the host computer 31, corresponding respectively to the position (see FIG. 2)
Y coordinates (light sources 42, 42, ... arranged in a matrix)
Is calculated.

Then, the light irradiation means controller 34 rotates the light and dark directions of the light sources 42, 42,... By 90 degrees by a control signal from the host computer 31 as shown in FIG. Light sources 42, 42, having the same x-coordinate value for all y-coordinates of the xy-coordinates set on the emission surface 43
Are equal, and the light intensity of each light source 42 (see FIG. 2) of the light irradiation means 23 is controlled so that the light intensity at points having different x-coordinate values gradually changes. In this state, an image of the light irradiation area S is captured by the CCD camera 24.

Each luminance data of FIG. 4 above the apex of the strip diagonals h of the camera field of view F shown in (b) P ₁ and P ₂ at this time, the host computer 31 from the image processing Purossessa 33 shown in Figure 1
And the light sources 42 (second
Light source 4 arranged in an x-coordinate (see matrix)
2,42, ...) are calculated.

As a result, the positions on the xy coordinates of the light sources 42 and 42 corresponding to the vertices P ₁ and P ₂ of the one-diagonal line h, whose positions are known points in the camera field of view F, are determined.

Based on this position information and the known position information of the vertices P ₁ and P ₂ of the one-diagonal h in the camera field of view F, the host computer 31 detects the light irradiation area S in the light irradiation area S irradiated by the light irradiation means 23. Light source in the area that matches the camera field of view F
The positions of 42, 42, ... are calculated.

The light sources 42, 42,... Shown in FIG. 2 in the area corresponding to the camera field of view F in the light irradiation area S obtained by this calculation cause the defect existing on the coating film surface 27 to be explained as follows. Is detected.

FIGS. 5 (a) and 6 (a) show a case where the coating film surface 27 has a convex defect portion 11, and FIGS.
FIG. 2B shows a case where the coating film surface 27 has a concave defect portion 11.

The light irradiation means 23 is a light irradiation means controller 34 shown in FIG.
Receives a control signal from, (represented by the length of the line m.) Light intensity to be emitted from the emission surface 43 of the light of the light irradiation means 23, indicated by arrow A ₁ in the exit surface 43 varied Tsuyokara weak in one direction, the first such light intensity changes Tsuyokara weak in the direction indicated in this case by the arrow a ₂ along the one side of the rectangular camera view F of the CCD camera 24 Light irradiation means as shown
The light intensity of each of the 23 light sources 42 is controlled.

Thereby, the coating film surface 27 corresponding to the luminous intensity change,
In a direction corresponding to the arrow A _1, the light irradiation area S having a change in illuminance occurs. This light irradiation area S matches the camera field of view F of the CCD camera 24 as described above.

In such a state, if the defective portion 11 occurs on the coating film surface 27, the regular reflection direction of the light from the light irradiation means 23 changes at the defective portion 11. Due to the change in the specular direction of this light,
Receiving image 12 of the CCD camera 24, in a state in which the illuminance is changed uniformly in the direction indicated by arrow A _2, unlike the brightness change state rest of the defect portion 11 uniformly invariant screen Becomes

Then, as shown in FIG. 5 (a),
In the case of a convex shape, the emission surface of the light irradiation means 23
The light from the position 13 with a high luminous intensity of 43 is mainly the above-mentioned exit surface
The specular reflection direction changes on the surface 11a of the defective portion 11 facing the surface 43, and a part of the light enters the CCD camera 24. But,
On the surface 11b behind the defect portion 11 with respect to the emission surface 43,
Only the light from the position 14 where the luminous intensity of the emission surface 43 is relatively small enters, and the CCD camera 24 has the above-described rear surface 11b of the defect portion 11.
The reflected light from is hardly incident.

Therefore, as shown in FIG. 6A, the received light image 12 of the CCD camera 24 has a CCD
In the direction indicated by the arrow A ₂ toward the dark from where bright light image 12 of the camera 24, becomes brighter by the other part at the beginning is the defect portion 11 becomes darker than the other portions After this bright part.

When the defect portion 11 is concave, light from the position 13 having a large luminous intensity of the emission surface 43 of the light irradiation means 23 mainly hits the surface 11c on the side facing the emission surface 43 of the defect portion 11. The specular reflection direction changes, and a part of it changes
Incident on. However, on the surface 11d of the defect portion 11 opposite to the surface 11c, a position 14 where the luminous intensity of the emission surface 43 is relatively small.
From the surface 11d of the defect portion 11 on the opposite side.

Therefore, as shown in FIG. 6 (b), the received image 12 of the CCD camera 24 has a CCD
In the direction indicated by the arrow A ₂ toward the dark from where bright light image 12 of the camera 24, become darker than other portions Introduction defective portion 11 becomes brighter than other portions After this dark portion.

The video camera 15 outputs a video signal that changes in accordance with the change 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 processor 33, the image processor 33
A video signal output from the camera 24 is processed, and its value, for example, a scanning line of a video signal in which a differential signal of the video signal exceeds a predetermined value, a timing on the scanning line where the differential signal exceeds the threshold value, and A change in the sign of the differential signal near this timing is detected. Thereby, the position of the defective portion 11 in the received light image 12 and the defective portion 11
And the like. This detection data and the position of the tip arm 22 of the robot device 21 are stored in the memory.

Then, at the time of repair, repair is performed according to the unevenness of the paint defect portion 11 present on the paint surface 27 of the vehicle body 26, and as described below, when the defect portion 11 is convex, the protruding portion is When it is scraped small and the defective part 11 is concave,
The coating film is scraped off in a relatively wide range including the defect portion 11.

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

As described above, even when the coating film surface 27 is irradiated in a plane, halation of light is eliminated and the defective portion 11 can be regarded as a clear image having a difference in brightness from the surroundings.

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

In the above, the light irradiating means 23 has described the embodiment in which the luminous intensity of the light sources 42, 42,... Is gradually changed to detect the defective portion 11, but instead of changing the luminous intensity of the light sources 42, 42,. In addition, at least one of the luminous intensity and the wavelength, for example, the color (wavelength) of light emitted from the light source in the same row or column is the same, and the color (wavelength) of the light source in a different row or column gradually changes. The defect 11 can also be detected by a change in the order of the light colors at the defect 11.

Further, in the above, the embodiment in which the detection of the defective portion 11 is performed by the image processor 33 has been described, but the video signal from the CCD camera 24 is monitored by the inspector on the monitor television, so that the detection of the defective portion 11 is performed. It is also possible to perform recording on the recording device.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to not only an inspection apparatus for a paint defect of a vehicle body but also a surface defect inspection apparatus.

[Brief description of the drawings]

1 is an overall configuration diagram of an embodiment of a surface defect inspection apparatus, FIG. 2 is a perspective view of a light irradiation unit, and FIGS. 3 (a) and 3 (b) each explain detection of a camera visual field position. FIGS. 4 (a) and 4 (b) are explanatory views of the camera field of view of FIGS. 3 (a) and 3 (b), respectively. FIGS. 5 (a) and 5 (b) 6 (a) and 6 (b) are explanatory views of a camera screen when a surface to be inspected has convex and concave defects, respectively. FIG. 8 is an explanatory view of a conventional surface defect inspection apparatus, FIG. 8 is an explanatory view of an image obtained by a camera of the surface defect inspection apparatus of FIG. 7, and FIG. 9 is an image of an image obtained by the camera when the surface to be inspected is a curved surface. FIG. 10 is an explanatory view of another conventional surface defect inspection apparatus. S: Light irradiation area, F: Camera field of view, 11: Defect part, 12: Light receiving screen, 13: High light intensity position, 14: Low light intensity position, 20: Painting inspection station, 21 ... ... Robot device, 23 ... Light irradiation means, 24 ... CCD camera, 25 ... Support bracket, 26 ... Car body, 27 ... Coating surface, 31 ... Host computer, 32 ... Robot controller, 33 ... Image processing processor, 34: Light irradiation means controller, 42: Light source, 43: Light emission surface.

Continuation of front page (72) Inventor Akinori Utsunomiya 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A 1-210806 (JP, A) JP-A 62-233710 ( JP, A) JP-A-64-79685 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30 G01N 21/84-21/91

Claims (4)

(57) [Claims] An object to be inspected is illuminated with light emitted from light irradiating means, and reflected light reflected from the surface to be inspected is received by a video signal generating means, and a light-receiving image of a light irradiation area of the surface to be inspected is converted into a video signal. In the surface defect inspection apparatus for detecting a defect present on the surface to be inspected from the video signal, the surface defect inspection apparatus has a light irradiation area larger than a camera field of view of the video signal generation means, and emits light. A large number of light sources are arranged on the surface in a matrix to irradiate the surface to be inspected, and at least one of the luminous intensity or the wavelength of the light emitted from each of the light sources is individually changed by receiving a control signal from the outside. Light irradiation control means for causing a light intensity or a wave of light emitted from a light source of the light irradiation means in at least two directions of predetermined xy coordinates on a light emission surface of the light irradiation means at the time of inspecting a surface defect. Is output to the light irradiation control means, and the brightness or wavelength of light incident on at least two different points at known positions in the camera field of view in each of the two directions is output. At least one is detected, the position of the light source corresponding to each of these points on the xy coordinate is detected from the data, and the light source area of the light irradiation unit that matches the camera field of view is calculated from the position of the light source. A surface defect inspection apparatus, comprising: an image information processing unit that emits a light source in this area to detect the surface defect. 2. The light irradiation control means according to claim 1, wherein light intensity or wavelength of light emitted from the same row or column of light sources is the same, and light intensity or wavelength of light emitted from different row or column of light sources is gradually changed. The surface defect inspection apparatus according to claim 1, wherein: 3. A surface to be inspected is illuminated with light emitted from a light irradiating means, and reflected light reflected from the surface to be inspected is received by a video signal generating means, and a light receiving image of a light irradiation area of the surface to be inspected is converted into a video signal. In the surface defect inspection method for detecting a defect present on the surface to be inspected from the video signal, the surface defect inspection method has a light irradiation area larger than a camera field of view of the video signal generation means, A plurality of light sources are illuminated on the surface to be inspected using a light irradiating means in which a plurality of light sources are arranged in a matrix with respect to the emission surface of the light source. Based on a control signal received from the outside, the luminous intensity or wavelength of the light emitted from each of the light sources At least one of them is individually changed, and the light intensity of the light emitted from the light source of the light irradiating unit in at least two directions of the predetermined xy coordinate on the light emitting surface of the light irradiating unit at the time of inspecting the surface defect is also changed. Or at least one of the wavelengths is gradually changed, and in each of the two directions, at least one of the brightness or the wavelength of light incident on at least two different points whose positions are known in the camera field of view is detected, and the data is detected. From the positions of the light sources corresponding to these points on the xy coordinates are detected, and the light source area of the light irradiation unit that matches the camera field of view is calculated from the positions of the light sources, and the light sources in this area are caused to emit light. A surface defect inspection method, wherein the surface defect is detected. 4. The light intensity or wavelength of light emitted from light sources in the same row or column is made equal, and the light intensity or wavelength of light emitted from light sources in different rows or columns is gradually changed. A surface defect inspection method according to claim 3.