JP5323320B2 - Surface inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface inspection apparatus having a suitable LED lighting system for inspection of the glossy surface of a large object. <P>SOLUTION: The surface inspection apparatus comprises the lighting system 11 using LED, a camera 12 for photographing the light emitting surface of the lighting system 11 reflected on the surface of the object, a robot arm 10 capable of moving the camera 12 to an arbitrary position and direction, a sequencer for moving the robot arm along a predetermined route and repeating the command of photographing by the camera, and a controller for capturing an image photographed by the camera, detecting a flaw, and displaying its position. By using the LED for lighting, the area of the light emitting surface is large, a large area has little unevenness and is uniform, and lighting with a small amount of excessive diffuse light is allowed. Therefore, the detection accuracy is improved and the inspection time can be shortened. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a surface inspection apparatus, and more particularly to a surface inspection apparatus provided with an LED (light emitting diode) illumination device suitable for inspection of a glossy surface.

2. Description of the Related Art Conventionally, there has been proposed an apparatus that inspects a surface of a product by taking a product image with a digital camera. The following Patent Document 1 discloses a mirror surface inspection apparatus that inspects abnormalities such as scratches that are mirror surface defects and adhesion of foreign matter. In this mirror surface inspection apparatus, the camera is disposed toward the mirror surface of the workpiece to be inspected, and the first diffused surface illumination is disposed in a region that becomes the object field of the camera due to regular reflection on the normal mirror surface. The second diffusing surface illumination is arranged in a region that does not become a camera field due to regular reflection on a specular surface. Then, an image of light incident on the camera by specular reflection at a normal mirror surface with light from the first diffusion surface illumination, and incident on the camera by regular reflection at a defective portion with light from the second diffusion surface illumination. Mirror surface defects are detected from the light image by image processing.
Japanese Patent Laid-Open No. 2000-028545

  In the conventional surface inspection apparatus as described above, when the glossy surface is inspected, the light irradiated from the illumination device is regularly reflected and input to the camera, and an image of the illumination device reflected on the glossy surface is taken. Will do. When this method is applied to a large object such as an inspection of a painted surface of a car body of an automobile, for example, the following function is required as a lighting device.

  (1) The area of the light emitting surface is large in order to photograph as large an area as possible. (2) Since the reflection of the light emitting surface is photographed, the luminance is uniform over the entire light emitting surface and there is little unevenness. (3) Since the contrast between the normal surface and the scratch increases, the amount of unnecessary diffused light radiated in a direction other than the irradiation direction that reaches the camera by regular reflection is as small as possible. (4) Since it is necessary to move an illuminating device, it must be small and light. (5) The illumination color and brightness can be changed according to the color of the object in order to make the amount of reflected light as constant as possible regardless of the color of the vehicle body.

  However, in the conventional surface inspection apparatus as described above, there is a problem that if the light emitting surface is enlarged, unevenness is increased, excessive scattered light is increased, and it is difficult to reduce the size and weight. The detection accuracy is low, and it takes time to shoot the entire vehicle and check for scratches. An object of the present invention is to solve the above-described problems and to provide a surface inspection apparatus including an LED (light emitting diode) illumination device suitable for inspecting a glossy surface of a large object.

  The surface inspection apparatus according to the present invention includes an image photographing unit for photographing an image of an illumination device reflected on the surface of an object, and an illumination unit using an LED fixed to the image photographing unit in a predetermined positional relationship. An image of the object is obtained by repeating the robot arm means capable of moving the image photographing means in an arbitrary position and direction, the operation of moving the robot arm means according to a predetermined route, and photographing by the image photographing means. Control means for acquiring data, flaw detection means for detecting the position of a flaw from the photographed image, position information of the image photographing means from the robot arm means, and flaw position information in the image from the flaw detection means And a flaw position display means for calculating and displaying the flaw position on the object.

  In the surface inspection apparatus, the image photographing unit is a line sensor camera, and the illuminating unit is a linear illuminating device arranged in parallel to the photodetecting element array axis of the line sensor camera. The control means repeats the operation of moving the robot arm means by a predetermined distance in a predetermined direction in a direction perpendicular to the light detection element array axis of the line sensor camera and photographing with the line sensor camera. It is also characterized in that dimensional image data is acquired.

  Further, in the surface inspection apparatus described above, the illuminating means has a configuration in which a plurality of color LEDs are equally arranged on the wiring board, a light diffusion plate is arranged on the front surface of the LEDs, and a plurality of color LEDs are arranged. It is connected to a variable constant current power supply circuit that can control the drive current every time, and the control means controls the variable constant current power supply circuit for each color, thereby switching the illumination color according to the color of the object. There is also a feature.

  In the surface inspection apparatus described above, the object is a car body of the automobile, and the control means controls the robot arm means so that the image photographing means and the illumination means are arranged vertically. Another characteristic is that the surface of the vehicle body is scanned in the vertical direction. Further, the surface inspection apparatus described above is characterized in that a plurality of the image photographing means are provided in order to photograph the image of the illumination apparatus reflected on the surface of the object from different angles.

In the surface inspection apparatus described above, the light emitting surface of the illumination unit is characterized in that it includes at least one of a plurality of planes or curved surfaces facing different directions. In the surface inspection apparatus described above, the light emitting surface of the illuminating unit is characterized in that a portion far from the image capturing unit is extended outward.
In the surface inspection apparatus described above, the flaw detection unit is a binarization unit that binarizes a luminance value of a photographed image, and a region having no object in the image has the same luminance value as that of the object surface without a flaw. There is also a feature in that it is provided with a non-inspection area filling means for filling in, and an abnormal area detecting means for judging an area having a luminance value different from the surrounding luminance value having a predetermined size as an abnormal area.

The surface inspection apparatus further includes a laser light source unit that is fixed in a predetermined positional relationship with the image capturing unit and irradiates a laser beam that passes through a focal position of the image capturing unit. .
In the surface inspection apparatus described above, four laser light source means are provided, and further, the laser light source means is turned on to analyze an image photographed by the image photographing means, and an object, the image photographing means, There is also a feature in that position information detecting means for obtaining at least one of the distance information and the angle information is provided.

The surface inspection apparatus of the present invention has the following effects due to the above-described features.
(1) By using the LED, the area of the light emitting surface is wide, and the illumination is uniform with little unevenness over a wide area, so that the illumination with little extra diffused light is possible, so that the detection accuracy is improved and the inspection time is improved. Can be shortened.
(2) The lighting device can be configured in a thin plate shape and can be reduced in weight, so that it can be easily mounted on the tip of the robot arm and the robot arm can be moved at high speed.
(3) By using the LED in the lighting device, the color and brightness can be freely adjusted according to the target color.

(4) By using the line sensor, it is possible to further reduce the size and weight of the illumination device for photographing the same area. Further, the line sensor can shoot with higher accuracy than a normal two-dimensional image pickup device, and can improve the flaw detection accuracy or shoot a wider range with the same accuracy.
(5) By configuring the illumination device with a plurality of planes or curved surfaces, and changing the shape of the illumination means so that the image of the illumination means reflected on the convex surface of the object is the same rectangle as the field of view of the camera An object consisting of various curved surfaces, such as a car body, can be efficiently photographed.
(6) By providing means for detecting the position and angle of the object using the laser light source, the teaching process for setting the imaging position and imaging angle of the entire surface of the object can be automated.

  In the embodiment, an example of inspecting a painted surface of a car body of an automobile, for example, as an object to be inspected (hereinafter also referred to as a workpiece) will be described. However, the present invention is an arbitrary gloss painted surface, a cutting surface of a metal product, a resin molding. It can be applied to surface inspection of products. Embodiments will be described below with reference to the drawings.

  FIG. 1 is a front view showing the configuration of an embodiment of the surface inspection apparatus of the present invention. The surface inspection apparatus according to the present invention is broadly divided into a robot arm 10 provided with an imaging unit 13, a sequencer 25 for controlling the entire surface inspection process including control of the robot arm 10, image capturing, and inspection processing for scratches. It consists of a controller 20.

  The photographing unit 13 is fixed to the tip of the robot arm 10, and an illumination device 11 using an LED and a camera 12 for photographing the object 15 are mounted so that the angle can be adjusted. The robot arm 10 is a device that can move the photographing unit 13 to an arbitrary position and direction. If the necessary conditions are satisfied, the robot arm 10 is a known arbitrary commercially available robot such as a multi-joint robot or a robot combined with a linear drive device. A robot arm device can be adopted.

  The sequencer 25, which is a part of the control means, is a computer device that controls the entire inspection process including the control of the robot arm 10, and inputs a program for executing a process to be described later to a well-known sequencer device that is commercially available. Can be realized. The controller 20, which is also a part of the control means, is a computer device that performs image capturing and inspection processing for the presence or absence of scratches. For example, by installing a program for executing processing to be described later on a known personal computer commercially available. It is feasible. Note that the sequencer 25 and the controller 20 can be realized by a single computer device.

  The illumination power supply device 21 is a power supply device that drives an LED of a desired color of the illumination device 11 with a desired current value under the control of the controller 20. The display device 22 is a display device such as a liquid crystal display device for displaying a target scratch position, for example.

  FIG. 2 is a front view showing the configuration of the imaging unit 13 of the surface inspection apparatus of the present invention. FIG. 2A shows a case where a camera using a CCD monochrome image pickup device capable of taking a two-dimensional image is used as the camera 12. In this case, since the light emitting surface of the illuminating device 11 reflected on the surface of the object is photographed by the camera 12, the shape of the light emitting surface of the illuminating device 11 should be substantially equal to the shape of the field of view of the camera 12 (rectangle). Is preferred.

  FIG. 2B shows a case where a camera using a CCD line sensor imaging device capable of taking a one-dimensional image is used as the camera 31. In this case, the shape of the light emitting surface of the illumination device 30 is an elongated rectangular shape having a predetermined width. The width is determined according to the surface shape of the object so that the light emitting surface of the illumination device 30 is reflected in the line sensor camera 31, but the width may be narrower as the object is closer to a plane.

The array axis of the light detection elements of the line sensor camera 31 and the long axis of the illumination device are arranged in parallel. As the CCD line sensor, for example, a commercially available CCD monochrome line sensor with 4096 pixels can be used, and the line sensor can capture a higher-accuracy image than the currently available two-dimensional image pickup device.
Note that the focus of the camera is adjusted by, for example, manual adjustment so that the surface of the object separated by a predetermined distance is in focus.

  If the surface of the object is curved, the image of the illuminating device reflected is distorted. In particular, when a line sensor camera is used, normal imaging cannot be performed if the illuminating device is narrow. When the target is a car body, the surface is not curved in the horizontal direction, but is curved in the vertical direction. Therefore, the illumination devices 11 and 30 and the cameras 12 and 31 are arranged vertically, and the image of the illumination device 11 that is captured when the photographing unit 13 is scanned (moved) in the vertical direction is less distorted and has a wider range. Can be taken.

  FIG. 3 is a cross-sectional view showing the configuration of the illumination device 11 of the surface inspection apparatus of the present invention. An illuminating device 11 that is an illuminating means using LEDs is an illuminating device in which a large number of LEDs 17 are arranged with a uniform surface density (interval) on a wiring board housed in a thin rectangular parallelepiped case (11). The LED 17 uses a bullet-shaped element with a convex lens at the tip and a narrow light irradiation angle to reduce diffused light in unnecessary directions, and to reduce unevenness by making the density as dense as possible. Increase uniformity.

  As the LED 17, for example, LEDs of three kinds of colors of red (R), green (G), and blue (B) are arranged at an equal density, and each color LED is independently driven at a desired current value. The circuit is configured so that it can. In addition, although irradiation angle is wide as LED17, a small and light chip-type LED element may be employ | adopted. A chip-type LED element can make a surface density higher than a bullet-type LED element.

  A light diffusing plate 18 is mounted on the front surface of the LED 17 at a predetermined distance. The light diffusing plate 18 reduces unevenness of the light emitting surface and increases uniformity. Note that the uniformity increases as the distance between the LED 17 and the light diffusion plate 18 increases, so that the LED 17 and the light diffusion plate 18 are separated as much as possible. The light diffusing plate 18 is a translucent plastic plate that diffuses light, and a plate having an arbitrary diffusibility is available. As the diffusive material is used, the uniformity increases, but the amount of light is attenuated and unnecessary diffused light is increased, so that the contrast of the scratch is maximized.

  FIG. 4 is an explanatory diagram showing an arrangement at the time of photographing of the photographing unit 13 of the surface inspection apparatus of the present invention. In the surface inspection apparatus of the present invention, since the reflection of the light emitting surface of the illuminating device 11 that has been specularly reflected is photographed by the camera 12 (31), an illuminating device having an area several times larger than at least the photographing range (photographing region). Necessary. Even if the angle θ between the optical axis of the camera and the perpendicular to the surface of the object is 0 degree, it is possible to photograph the reflection, and if θ is large, the photographing area becomes narrow and the reflected image is distorted in the case of a curved surface. The optimum angle is determined through experiments and the like.

  FIG. 5 is an explanatory view showing another arrangement example of the imaging units 13 of the surface inspection apparatus of the present invention. In this example, cameras 12 for taking a two-dimensional image are arranged on both sides of the illumination device 11. In this case, the illumination device 11 is arranged in parallel with the target surface. It is possible to simultaneously photograph two photographing areas centering on a point where a perpendicular bisector of a line connecting the center of the illumination device 11 and each camera 12 intersects the surface of the object.

  FIG. 6 is a plan view showing a configuration of a modification of the photographing unit of the present invention. FIG. 6A shows the same basic arrangement as FIG. 2A when a two-dimensional image capturing camera is used. FIG. 6B is an example in which cameras 12 for capturing a two-dimensional image are arranged on both sides of the illumination device 11 as in FIG. FIG. 6C shows an example in which the cameras 12 are arranged at four locations around the illumination device 11, and four imaging regions can be imaged simultaneously.

  FIG. 6D shows the same basic arrangement as FIG. 2B when the line sensor camera 31 is used. FIG. 6E shows an example in which line sensor cameras 31 are arranged on both sides of the lighting device 30. In this case, the illumination device 30 is arranged in parallel with the target surface. Two linear regions around the point where the perpendicular bisector of the line connecting the center of the illumination device 30 and each camera 31 intersects the surface of the object can be photographed simultaneously, and the configuration of (d) is provided. The same area can be photographed in half the time.

  FIG. 6F shows an example in which the cameras 31 are arranged at four places around the illumination device 30 having a double length. Since four linear photographing areas can be photographed simultaneously, the configuration of FIG. The same area can be photographed in 1/4 of the time. The FIG. 6G shows an example in which cameras 31 are arranged on both sides of the lighting device in the longitudinal direction. Also in this case, the arrangement axis of the light detection elements of the line sensor camera 31 and the long axis of the illumination device are arranged in parallel. Again, the same area can be photographed in half the time of the configuration of (d).

  FIG. 7 is a block diagram showing the configuration of the illumination power supply device 21 of the surface inspection apparatus of the present invention. A predetermined number (three in the figure) of LEDs 31 connected in series for each color of RGB is connected in parallel to form a circuit. A variable constant current power supply circuit 42 in the illumination power supply device 21 is connected for each color. Each variable constant current power supply circuit 42 has its current value controlled by the controller 20 via the control circuit 40 to control on / off and brightness. Therefore, the lighting device 11 can illuminate with any color and illuminance.

  FIG. 9 is a flowchart showing processing contents in the sequencer 25. This process is an example in the case of using a camera 12 that captures a two-dimensional image as shown in FIG. In S10, the robot arm 10 is controlled to move the photographing unit 13 to a predetermined initial position. In S11, the photographing unit 13 is moved at a predetermined speed according to a preset route and photographing direction.

  In S12, it is determined whether or not the current position has reached a preset photographing position. If the determination result is negative, the process proceeds to S14, but if the determination is affirmative, the process proceeds to S13. In S <b> 13, the position information of the photographing unit 13 and the photographing instruction are output to the controller 20. In S14, it is determined whether or not the inspection is completed (moved to the inspection end position). If the determination result is negative, the process proceeds to S11, but if the determination is affirmative, the process proceeds to S15. In S15, an end instruction is transmitted to the controller.

  When the line sensor camera 31 is used, the photographing unit 13 is moved in a certain direction at a predetermined constant speed, and a photographing start instruction and a photographing end instruction are transmitted to the controller 20. . And a line image is taken in from the line sensor camera 31 with a fixed period.

  FIG. 10 is a flowchart showing the processing contents in the controller 20. This process is also an example in the case of using a camera 12 that captures a two-dimensional image as shown in FIG. In S20, it is determined whether or not a shooting instruction is received from the sequencer 25. If the determination result is negative, the process proceeds to S21, but if the determination is affirmative, the process proceeds to S22.

  In S21, it is determined whether or not an end instruction has been received from the sequencer 25. If the determination result is negative, the process proceeds to S20, but if the determination is affirmative, the process ends. In S22, the photographing unit position information received from the sequencer 25 is stored. In S23, illumination is turned on with a color and luminance (current value) corresponding to the target color. The target color information is previously stored manually or stored from a production line control system (not shown).

  In the case of an automobile body, there are a large number of paint colors. When illuminated with the same white light, the brightness value of the photographed image varies greatly depending on the paint color even if it is specularly reflected light, and the detection accuracy of the scratches is reduced. Therefore, when the paint color is red, for example, illumination with red light increases the amount of reflected light and decreases the difference in luminance value.

  When shooting with the robot arm 10 while scanning, if the shooting unit 13 is stationary at every shooting, it takes time to scan, so shooting is performed while moving. For this purpose, it is necessary to increase the shutter speed of the cameras 12 and 31. For this purpose, the illuminance of the illumination device 11 is preferably as bright as possible.

  On the other hand, although the brightness of the LED depends on the current that flows, most of the current that flows in the LED becomes heat, so the input power of the entire lighting device 11 must be kept below a certain value in order to keep the temperature of the element below a certain value. is there. In addition, an LED can emit light with high brightness by passing a large current for a short time.

  Therefore, when the paint color is white, the same current is supplied to each of RGB to illuminate with white light. When the paint color is red, only the red (R) LED is white 3 Driven with double current, only red light with higher reflectivity is emitted with high brightness. Even in this case, the power consumption (heat generation) of the lighting device 11 as a whole is the same as in the case of white.

  In S24, the camera 12 is controlled to capture and save the captured image. FIG. 8 is an explanatory view showing a display example of a photographed image and scratches in the surface inspection apparatus of the present invention. FIG. 8A shows an example of an image captured by the camera 12. The body portion 50 becomes white (high brightness) because the light emitting surface of the lighting device 11 is reflected, and there are scratches, foreign objects, etc., and the region 52 that is not a smooth glossy surface appears black. The background portion 51 without the vehicle body that is a non-inspection area is also darkened.

  In S25, the illumination is turned off. In S26, a flaw detection process to be described later is performed, and only a flaw area in the image is extracted. In S27, it is determined whether or not a flaw has been detected. If the determination result is negative, the process proceeds to S20, but if the determination is affirmative, the process proceeds to S28.

  In S28, the scratch position on the object is calculated from the photographing unit position information and the scratch position information in the image. The vehicle body as the object is installed at a predetermined position with respect to the robot arm 10. Therefore, the position of the shooting area on the surface of the vehicle body is calculated based on the position and direction information of the shooting unit 13. Next, the position of the scratch in the imaging region on the surface of the vehicle body is calculated and stored from the position information of the scratch in the image.

  In S 29, the scratch position (and scratch image) on the object is converted into a position on the figure of the vehicle body displayed on the display device 22 and displayed on the display device 22. FIG. 8B is an explanatory diagram showing a display example of scratches. A cross mark 56 indicating the position of the flaw is displayed in the figure showing the side of the vehicle body. Further, an enlarged image of the wound may be displayed simultaneously or based on the user's operation.

  When the line sensor 31 is used, image information for one line is sequentially taken from the line sensor 31 at a predetermined time interval between the photographing start instruction and the photographing end instruction, and the flaw detection processing is sequentially performed on the captured image information. Execute. The position of the flaw is calculated from the scanning start position of the robot arm 10, the scanning direction, the scanning speed, the shooting timing of the line image where the flaw is detected, and the flaw position information in the line.

  FIG. 11 is a flowchart showing the content of the flaw detection process in S26 of FIG. In S30, for example, the luminance value is binarized into white (high luminance: 1) and black (low luminance: 0) depending on whether the luminance value is larger than a predetermined threshold. Thereafter, a black point having a size smaller than a predetermined value in the white region or a white point having a size smaller than a predetermined value in the black region may be regarded as noise, and a filter process may be performed in which the black color is filled with surrounding colors.

  In S31, scanning is performed until a black (0) pixel appears. In scanning, for example, the image is scanned from the upper left in the horizontal direction, and when it reaches the right end, it moves to the left end of the next line and scans to the lower right of the image. In S32, the number of black pixels adjacent to the detected black pixel is counted.

  In S33, it is determined whether or not the number of adjacent black pixels is equal to or greater than a predetermined value, max. If the determination result is negative, the process proceeds to S35, but if the determination is affirmative, the process proceeds to S34. In this determination, if a predetermined number, for example, several or less white pixels exist in the black pixel row, it is determined that the noise is present, and the white pixel is also processed as a black pixel.

  In S34, it is determined that the maximum number of black pixel columns is outside the inspection area where there is no object, and is all painted white. In S35, it is determined whether or not the scanning is completed. If the determination result is negative, the process proceeds to S31, but if the determination is affirmative, the process proceeds to S36. By the above processing, the entire outside of the inspection area is painted white, and only an abnormal area such as a scratch remains.

  In S36, the image is scanned again, for example, from the upper left until a black pixel appears. In S37, the number of black pixels adjacent to the detected black pixel is counted. In S38, it is determined whether or not the number of adjacent black pixels is equal to or less than a predetermined value, min. If the determination result is negative, the process proceeds to S40, but if the determination is affirmative, the process proceeds to S39.

  In S39, it is determined that min or less pixel columns are noise. In S40, it is determined that the pixel row larger than min is a flaw, and the pixel position in the image is recorded. In S41, it is determined whether or not scanning is completed. If the determination result is negative, the process proceeds to S36, but if the determination is affirmative, the process ends. Through the processing as described above, the scratch position of the vehicle body is automatically detected and displayed on the display device.

  FIG. 12: is sectional drawing which shows the structure of Example 2 of the illuminating device of the surface inspection apparatus of this invention. In the first embodiment, a configuration in which a large number of small LEDs are arranged as LEDs has been disclosed, but in recent years, large and high-brightness LED elements have become available. When a large LED is used, the number of LED elements is small, but unevenness is likely to occur. Therefore, by disposing the convex lens 62 on the front surface of the large LED 61 and further disposing the light diffusion plate 63 separated by a predetermined distance, unnecessary diffused light and unevenness are reduced.

  FIG. 12A shows an example in which a large LED 61 containing, for example, three LEDs R, G, and B is used. A convex lens 62 is arranged on the front surface of the large LED 61 to narrow the light emission angle. Further, by disposing the light diffusion plate 63 at a predetermined distance, unevenness is reduced and uniformity is increased.

  FIG. 12B shows, for example, a white large LED 61, a first lens 62, a first light diffusion plate 67, a second lens 66, a second light diffusion plate 68, and a third light diffusion plate 69 in order. This is an example. A convex lens 62 is disposed in front of the large LED 61, a first light diffusion plate 67 and a convex lens 66 are disposed in the vicinity of the convex lens 62 on the opposite side of the LED 61, and a second light diffusion plate from which the emitted light is separated by a predetermined distance. 68 is arranged to illuminate the whole. The lens may be a normal convex lens or a flat Fresnel lens. Furthermore, by arranging the third light diffusion plate 69 on the front surface of the second light diffusion plate 68, unevenness is reduced and uniformity is increased.

FIG. 13: is the front view and side view which show the structure of Example 3 of the illuminating device of the surface inspection apparatus of this invention. The lighting devices 11 and 30 of the first embodiment shown in FIG. 2 have a rectangular light emitting surface shape, but are reflected when the surface is composed of various convex curved surfaces such as a car body of an automobile. The shape of the light emitting surface of the lighting device is distorted and does not become a rectangle. Therefore, it is necessary to increase the size of the lighting device by taking the distortion into consideration.
Therefore, in the illumination device of the third embodiment, the issuance surface is composed of a plurality of planes or curved surfaces, and the illumination unit image is reflected on the convex surface of the object so that the image of the illumination unit is the same rectangle as the field of view of the camera. By deforming the shape, an object composed of various curved surfaces such as a car body of an automobile can be efficiently photographed.

  In FIG. 13A, the light emitting surface of the illumination device means is composed of three planes, and the left and right light emitting surfaces 70, 71 face the inner side with respect to the central light emitting surface 70. Further, portions 73 of the left and right light emitting surfaces far from the camera 12 are extended outward (opposite the camera). In FIG. 13A, a light emitting surface facing inward similar to the left and right light emitting surfaces 70 and 71 may be provided above the central light emitting surface 70.

  FIG. 13B shows an example in which the three light emitting surfaces in FIG. 13A are configured by separate illumination devices 80, 81, and 82, respectively. With such a structure, manufacturing is facilitated. FIG. 13C shows an example in which the orientations of the illumination devices 85 and 86 on both sides can be automatically or manually changed according to the type of object and the photographing position in the configuration of FIG. When the direction is automatically changed, the left and right can be controlled separately according to the object to be photographed. With such a configuration, a curved surface having a large curvature such as an end of a vehicle body can be efficiently photographed.

  FIG. 13D shows an example in which the same function as the configuration of FIG. For example, a cylindrical side surface shape can be used as the curved surface. A portion 75 of the light emitting surface far from the camera 12 is extended outward, and the edge is curved. Only the central portion of the lighting device may be a flat surface. Such a structure reduces unevenness because there is no joint between the light emitting surfaces.

FIG. 13E shows an example in which the same function as the configuration of FIG. 13D is configured by a curved surface having a surface shape that is a part of one sphere or an elliptic sphere. If comprised in this way, since it curves also in the vertical direction with the horizontal direction in FIG.13 (e), it is suitable for illumination of the curved corner | angular part of a target object.
FIG. 13F shows an example in which two cameras are arranged on both sides of a lighting device similar to the curved surface configuration of FIG. In this case, the edge far from both cameras is curved. Furthermore, the edge in the vertical direction in FIG.

Even when a line sensor camera is used as the camera, the same configuration can be applied only by shortening the width in the vertical direction in the drawing of the illumination device in FIG.
With the configuration and operation as described above, the surface inspection apparatus of the present invention improves the accuracy of surface inspection of products and shortens the inspection time.

  In order to execute the shooting process in the above-described embodiment, a teaching process for setting the shooting position and angle of the camera for the entire vehicle body in advance is required. Traditionally, the teaching process has been done by manually setting the camera position and angle so that the camera can sequentially capture a range that completely includes each grid by writing grid lines on the vehicle body. Had decided. However, there is a problem that this work is very time-consuming. In the fourth embodiment, this teaching process is automated.

  FIG. 14 is a front view showing the configuration of Embodiment 4 of the surface inspection apparatus of the present invention. FIG. 15 is a front view showing the configuration of the photographing unit of Example 4 of the surface inspection apparatus of the present invention. In the fourth embodiment, five laser light sources 90 and 91 are added to the photographing unit 13 of the first embodiment shown in FIG. The laser light sources 90 and 91 have a built-in semiconductor laser element that emits, for example, a red thin laser beam, and are turned on / off under the control of the controller 20.

  A laser light source 90 provided adjacent to the camera 12 emits laser light substantially parallel to the optical axis of the camera 12 so that the optical axis of the camera 12 and the optical axis of the laser light source 90 intersect at the focal position of the camera 12. Is arranged. This laser light source 90 is provided so that the user can confirm the position of the optical axis of the camera with the naked eye and can confirm the normality of the process, and is not used for the automatic teaching process described later.

  The four laser light sources 91 are attached to the four corners of the photographing unit 13 by support members 92 fixed to the photographing unit 13 as shown in the figure. The positions of the four laser light sources 91 are such that when the photographing unit 13 is directed toward the object so that the optical axis of the camera 12 is substantially horizontal, the four laser light sources 91 are located one on the left and one on the upper side. Are arranged with the beam direction directed to the focal position on the optical axis of the camera 12, one on each of the right and left sides. The angle at which the optical axis of the camera 12 and the optical axis of the laser light source 91 intersect may be within a range of 30 degrees to 60 degrees, for example.

  Accordingly, on the image taken by the camera 12 from the vertical direction, the four light spots from the four laser light sources are on the diagonal line of the substantially rectangular image. Then, the distance between the four points increases as the focal length shifts, but overlaps with one point when the focus is achieved. In addition, if the target surface is inclined with respect to the optical axis of the camera 12, the distance between the four points is different up and down or left and right, so that the optical axis can be corrected using the difference in distance. It is.

  FIG. 16 is a flowchart illustrating the contents of the teaching process according to the fourth embodiment. This process is executed by the controller 20. In S50, the robot arm 10 is controlled so as to move the photographing unit 13 to a predetermined initial position, for example, a position away from the planned position of the object by a focal length. For example, the vehicle body as the object is conveyed to a predetermined position with a position error of about 10 mm. In S51, the four laser light sources 91 are turned on.

  In S52, the robot arm 10 is controlled so that the photographing unit 13 is separated from the focal distance by a predetermined distance. This process intentionally shifts the focal point so that four light spots appear in the captured image. In S53, the camera 12 captures an image. In S54, the number and position of light spots are detected from the captured image by known image processing.

  FIG. 17 is an explanatory diagram illustrating an example of a captured image in the teaching process according to the fourth embodiment. In S52, for example, an image as shown in FIG. Each of the four light spots P1 to P4 is a light spot obtained by the camera 12 capturing light that is irregularly reflected when the laser light emitted from the four laser light sources 91 hits the object.

  For example, if the surface of the object is a plane and the optical axis of the camera 12 is substantially perpendicular to the surface of the object, the distances Lu, Ld, Ll, and Lr between the four light spots shown in FIG. All are equal. As shown in FIG. 17E, for example, if the angle φ between the optical axis of the camera 12 and the optical axis of the laser light source 91 is 45 degrees, the distance error Lg = Lu / 2, and the light spot on the image is The distance error Lg is determined from the distance.

  Therefore, for example, by repeating the process of moving the photographing unit (camera) by a distance proportional to the distance error, the camera can be focused on the surface of the object. The image example of FIG. 17C is an image example when the focus is closer to that of FIG. 17A, and FIG. 17D is an image example when the distance substantially matches the focal length.

  When the surface of the object is a curved surface or the optical axis of the camera 12 is not perpendicular to the surface of the object, as shown in FIG. 17B, the distances Lu, Ld, Ll and Lr are not equal. Then, a rough angle error is found by the difference in distance between the points. Accordingly, as shown in FIG. 17 (f), for example, the camera 12 is rotated to the position of the camera 95 indicated by the dotted line in the direction of a shorter distance with the focal point as the center, so that the optical axis of the camera 12 is targeted. It can be close to the normal of the surface.

  In S55 of FIG. 16, it is determined whether or not there is one light spot. If the determination result is negative, the process proceeds to S56, but if the determination is affirmative, the process proceeds to S60. In S56, horizontal and vertical distances Lu, Ld, Ll, and Lr between the points are calculated. In S57, the distance error between the target surface and the camera and the angle between the target surface and the optical axis are calculated.

  In S58, as described above, the camera is rotated around the focal position so that the optical axis of the camera 12 approaches the perpendicular of the target surface. In S59, the camera is brought closer by a predetermined distance, and the process returns to S53. The distance may be 4/3 of the distance error described above, or may be a fixed value. With the above processing, the distance between the object and the photographing unit and the rough angle are determined, and then the angle is checked and corrected.

  In S60, the laser light source is turned off and the surface light source 11 is turned on. In S61, it is checked whether or not the luminance corresponding to the pixel in the entire image is a predetermined value or more. In S62, it is determined whether or not the luminance of all the pixels is equal to or higher than a predetermined threshold value. If the determination result is negative, the process proceeds to S63, but if the determination result is affirmative, the process proceeds to S66. In S63, it is determined whether or not the number of brightness checks exceeds a predetermined number. If the determination result is negative, the process proceeds to S64, but if the determination is affirmative, the process proceeds to S65.

  In S64, the camera is rotated so that the lowest luminance portion becomes brighter. For example, as shown in FIG. 17G, when the lower part of the image is dark and the luminance is less than a predetermined value, the photographing unit 13 is rotated downward about the focal position of the camera 12.

  In S65, the camera is rotated so that the central portion of the image is brightest. In this case, for example, as shown in FIG. 17 (h), dark portions may remain on the top and bottom. In such a case, if the photographing range is divided into two parts in the upper and lower directions, it is possible to photograph the entire photographing range with a luminance equal to or higher than a predetermined value.

  In S66, the current position information of the photographing unit (camera) is recorded, and the surface light source 11 is turned off. In S67, the camera is moved to the next position. Note that the shooting positions are predetermined in a lattice shape so as to always overlap adjacent shooting ranges. In S68, it is determined whether or not the process is completed up to the end position. If the determination result is negative, the process proceeds to S51, but if the determination is affirmative, the process ends.

In the fourth embodiment, an example in which four laser light sources 91 are simultaneously turned on to capture an image and recognize each light spot has been disclosed. However, each laser light source is turned on one by one to capture an image, and the position of the light spot. May be detected one by one.
In the fourth embodiment, if only the focal length is adjusted, it is possible to obtain the distance error with one or two. In the case of one, the distance error can be detected depending on how far the light spot position is from the center of the image.

It is a front view which shows the structure of the Example of the surface inspection apparatus of this invention. It is a front view which shows the structure of the imaging | photography unit of the surface inspection apparatus of this invention. It is sectional drawing which shows the structure of the illuminating device of the surface inspection apparatus of this invention. It is explanatory drawing which shows arrangement | positioning at the time of imaging | photography of the imaging | photography unit of the surface inspection apparatus of this invention. It is explanatory drawing which shows another example of arrangement | positioning of the imaging | photography unit of the surface inspection apparatus of this invention. It is a top view which shows the structure of the modification of the imaging | photography unit of this invention. It is a block diagram which shows the structure of the power supply device for illumination of the surface inspection apparatus of this invention. It is explanatory drawing which shows the example of a picked-up image and the display of a damage | wound in the surface inspection apparatus of this invention. 3 is a flowchart showing processing contents in a sequencer 25; 3 is a flowchart showing processing contents in a controller 20. It is a flowchart which shows the content of the flaw detection process of S26 of FIG. It is sectional drawing which shows the structure of Example 2 of the illuminating device of the surface inspection apparatus of this invention. It is the front view and side view which show the structure of Example 3 of the illuminating device of the surface inspection apparatus of this invention. It is a front view which shows the structure of Example 4 of the surface inspection apparatus of this invention. It is a front view which shows the structure of the imaging | photography unit of Example 4 of the surface inspection apparatus of this invention. It is a flowchart which shows the content of the teaching process of Example 4. FIG. 10 is an explanatory diagram illustrating an example of a captured image in the teaching process according to the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Robot arm 11 ... Illuminating device 12 ... Camera 13 ... Imaging | photography unit 15 ... Test object 20 ... Controller 21 ... Illumination power supply device 22 ... Display device 25 ... Sequencer

Claims (1)

A plurality of color LEDs are evenly arranged on the wiring board so that the luminance of the light emitting surface is uniform, a light diffusion plate is arranged in front of the LEDs, and a driving current is applied to each of the plurality of color LEDs. Lighting means connected to a controllable variable constant current power supply circuit;
Image photographing means for photographing a two-dimensional image of the light emitting surface of the illumination means fixed in a predetermined positional relationship with the illumination means and reflected on the surface of the object by regular reflection;
Robot arm means capable of moving the photographing unit to which the illumination means and the image photographing means are attached to any position and direction;
The illumination color of the illumination means is switched in accordance with the color of the object, and the image data of the object is obtained by repeating the operation of moving the robot arm means according to a predetermined route and the photographing by the image photographing means. Control means to obtain;
Binarizing means for binarizing the luminance value of the image photographed by the image photographing means, non-inspection area filling means for painting an area without an object in the image with the same luminance value as the surface of the object without a flaw, predetermined A defect detection unit that detects an area of a brightness value different from the surrounding brightness value having a size of the range as an abnormal area, and detects a position of the wound in the image from the captured image;
The position information of the image photographing means is obtained from the robot arm means, the position information of the wound in the image is obtained from the wound detection means, and the wound position display means for calculating and displaying the wound position on the object;
Four laser light source means that are respectively fixed to four corners of the photographing unit and irradiate laser light that passes through the focal position of the image photographing means, so that four light spots appear in the captured image, The robot arm means is controlled so that the image photographing means is separated from the focal length, the laser light source means is turned on, the image photographed by the image photographing means is analyzed, and the distance from the distance between two light spots on the image is analyzed. The error is calculated, and the difference between the horizontal distance between the upper two light spots and the lower two light spots, or the vertical distance between the two left light spots and the vertical distance between the two right light spots. A position information detecting means for obtaining distance information and angle information between the object and the image photographing means by calculating an angle error based on a difference in distance;
The control means determines a photographing position and a photographing direction based on distance information between the object obtained from the position information detecting means and the image photographing means and angle information between the object surface and the photographed image. A surface inspection apparatus in which the photographing unit is rotated so that a portion having the lowest luminance is brighter when there is a portion where the luminance is less than a predetermined value.

Images