JP2016118518A - Appearance inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an appearance inspection device that can perform, quickly at a low cost, inspection as to whether a defect is present on a surface of a stereoscopic inspection target having a curved surface.SOLUTION: An appearance inspection device 1 comprises: a plurality of irradiation parts 10 that irradiate a surface of a stereoscopic inspection target with light; an imaging part 20 that photographs light emitted from the plurality of irradiation parts and reflected on the surface; a display part 30 that displays the light photographed by the imaging part as an image; and a light source control part 40 that controls luminance of the plurality of irradiation parts. The light source control part controls the luminance of each of the irradiation parts so that gradation of a stereoscopic surface in the image displayed by the display part becomes uniform.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an appearance inspection apparatus for an inspection object, and more particularly to an apparatus for inspecting an appearance of a three-dimensional inspection object.

  2. Description of the Related Art Conventionally, an apparatus that captures an appearance of a planar object such as a printed circuit board, generates an image, and inspects the inspection object for good or bad from the image is known. For example, Patent Document 1 discloses an image recognition apparatus for the purpose of determining whether a mounted product is good or defective from an image when a chip component is mounted. This image recognition apparatus sets a window for image data obtained by imaging both electrode portions of a chip component, and obtains four intervals from the frame of the window to the outer edge of the bright spot. Are equal to each other, it is determined that the chip component is not mounted, and the chip component is determined to be defective. If the intervals are not equal, the chip component is determined to be non-defective.

  Patent Document 2 discloses an illumination device for visual inspection aimed at reducing labor and cost required for visual inspection while supporting a plurality of types of visual inspection using three-dimensional images and two-dimensional images. The illumination device for appearance inspection includes a transmissive reflector, a cover, a frame, and first to fourth light source units. The light emitted from the first to third light source sections passes through the transmissive reflector and crosses the virtual plane passing through the inspection object at the first to third angles and irradiates the inspection object. And the light emitted from the 4th light source part is diffused and reflected by the lower surface of a transmissive reflecting plate, and irradiates a to-be-inspected object.

  Further, Patent Document 3 discloses a mounting board inspection apparatus for the purpose of reliably extracting a solder portion provided on a mounting board and determining the arrangement state of cream solder. This mounting board inspection device irradiates infrared light and visible light at a small incident angle to a mounting board on which cream solder is disposed, and images infrared light and regular reflection light of visible light from the mounting board. The arrangement state of the cream solder is determined based on the imaging result.

JP-A-8-219739 JP 2010-237034 A JP 2007-103665 A

However, there is no apparatus capable of inspecting a three-dimensional inspection object for the presence or absence of defects such as scratches on the surface thereof.
Accordingly, the present invention provides an appearance inspection apparatus that can inspect the presence or absence of defects on the surface of an inspection target that is three-dimensional and has a curved surface at high speed and at low cost.

In order to solve the above-described problems, a plurality of irradiation units that irradiate light on the surface of a three-dimensional inspection object, an imaging unit that images light reflected from the surface by the light irradiated by the plurality of irradiation units, and the imaging A display unit that displays light captured by the unit as an image, and a light source control unit that controls the luminance of the plurality of irradiation units, and the light source control unit is a three-dimensional surface gradation in an image displayed by the display unit There is provided an appearance inspection apparatus that controls the brightness of each irradiation unit so that the light intensity becomes uniform.
According to this, by displaying an image so that the gradation of the inspection object surface of the inspection object is uniform, the gradation difference in the uneven portion such as a scratch is conspicuous, and the inspection object is three-dimensional and has a curved surface An appearance inspection apparatus for inspecting the presence or absence of defects on the surface of an object can be provided.

Further, the imaging unit images the light reflected from the same surface a plurality of times, and the light source control unit applies a virtual first straight line connecting the surface and the imaging unit when the imaging unit images the same surface a plurality of times. The brightness of the irradiating unit may be controlled so that a virtual second straight line connecting the surface and the irradiating unit is imaged at different angles.
According to this, various uneven portions on a three-dimensional curved surface can be obtained by imaging a plurality of reflected light irradiated from different directions, such as scratches that cannot be found with reflected light of light irradiated from one direction. Even so, it will be possible to discover the presence or absence. In addition, since only the brightness of a plurality of irradiation units arranged at different positions is controlled without moving the inspection object, inspection can be performed at high speed.

Furthermore, it may further include a substantially hemispherical dome portion, and the plurality of irradiation portions may be arranged on an inner surface of the dome portion.
According to this, the external appearance of the three-dimensional inspection object can be inspected by disposing the inspection object at the center of the dome where the plurality of irradiation parts are disposed.

Further, the imaging unit may include a plurality of units, and the light source control unit may control the three-dimensional surface gradation in an image captured by each imaging unit to be uniform.
According to this, by displaying each image so that the gradation of the surface to be inspected of the inspection object is uniform, the gradation difference in the uneven portion such as a scratch stands out, and from a plurality of directions at once, It is possible to inspect the presence or absence of a defect on the surface of the inspection object that is three-dimensional and has a curved surface.

Further, the plurality of imaging units may be arranged in the dome unit, and may image other than the bottom surface of the three-dimensional inspection object without moving the inspection object and the imaging unit.
According to this, it is possible to inspect the three-dimensional inspection object at a high speed and at low cost by capturing images other than the bottom surface of the three-dimensional inspection object at a time without moving the inspection object and the imaging unit.

  As described above, according to the present invention, it is possible to provide an appearance inspection apparatus that can inspect the presence or absence of defects on the surface of an inspection object that is three-dimensional and has a curved surface at high speed and at low cost. .

1 is a block diagram of an appearance inspection apparatus according to a first embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The external view of the external appearance inspection apparatus of 1st Example which concerns on this invention (The figure which notched 1/4 of the dome part). The layout of the irradiation part and imaging part in the appearance inspection apparatus of the first embodiment according to the present invention (when viewed from the bottom side). FIG. 3 is a layout diagram of an imaging unit in the appearance inspection apparatus according to the first embodiment of the present invention. (A) In the II cross section of FIG. (B) In the II-II cross section of FIG. Explanatory drawing which shows the brightness | luminance of each irradiation part in the case of irradiating uniform light from several irradiation part. Explanatory drawing which shows the brightness | luminance of the surface of a test subject at the time of irradiating uniform light from several irradiation parts. Explanatory drawing which shows the brightness | luminance of each irradiation part in the external appearance inspection apparatus of 1st Example which concerns on this invention. Explanatory drawing which shows the brightness | luminance of the surface of a test target object in the external appearance inspection apparatus of 1st Example which concerns on this invention. It is explanatory drawing explaining the method to discover a crack | wound from several imaging from which reflected light angle differs in the external appearance inspection apparatus of 1st Example which concerns on this invention, Comprising: (A) The virtual surface which connects the surface and imaging part to image When the angle formed by the virtual second straight line connecting the surface and the irradiation unit with respect to the first straight line is the largest, (B) the surface and the virtual first straight line connecting the imaging surface and the imaging unit When the angle formed by the virtual second straight line connecting the irradiation unit is intermediate, (C) the virtual second straight line connecting the surface and the irradiation unit is compared with the virtual first straight line connecting the imaging surface and the imaging unit. When the angle to make is the smallest. Explanatory drawing explaining the bright field imaging in the external appearance inspection apparatus of 1st Example which concerns on this invention. Explanatory drawing explaining the dark field imaging in the external appearance inspection apparatus of 1st Example which concerns on this invention. The example of a display of the display part in the external appearance inspection apparatus of 1st Example which concerns on this invention. Example of inspection object (vehicle window lift switch). (A) Front, (B) Top, (C) Back, (D) Right side, (E) Left side.

Embodiments according to the present invention will be described below with reference to the drawings.
<First Example>
With reference to FIG. 1 thru | or FIG. 4, the external appearance inspection apparatus 1 in a present Example is demonstrated. The appearance inspection apparatus 1 is activated on a personal computer, an irradiation unit 10 configured by LEDs, an imaging unit 20 configured by a digital camera, a display unit 30 configured by a display of a personal computer (PC). The light source control unit 40 and the imaging control unit 60 configured by software, and the dome unit 50 in which the irradiation unit 10 and the imaging unit 20 are arranged are provided.

  The irradiation unit 10 is composed of 64 panels each having eight LEDs mounted on one panel. The irradiation unit 10 is arranged almost uniformly on the inner surface of the hemispherical dome unit 50 above and to the side of the inspection object. The object is irradiated with light at different incident angles. Thereby, the irradiation part 10 can irradiate light with respect to all surfaces other than the bottom face of the three-dimensional test object placed in the center of the dome part 50, and inspects the external appearance of the three-dimensional test object. be able to. Needless to say, the irradiation unit 10 is disposed on the inner surface of the dome-shaped dome unit 50, and is not limited to this. The surface of the three-dimensional inspection object can be uniformly irradiated with light. Anything can be used.

  The imaging unit 20 is composed of seven cameras, is arranged so as to be able to image all surfaces of the inspection object arranged at the center of the hemispherical dome unit 50, and irradiates light from the irradiation unit 10. Is disposed at a position where the reflected light from the inspection object can enter. One (camera 3 / CAM3) is at the zenith of the dome 50, and four (camera 2 / CAM2, camera 4 / CAM4, camera 5 / CAM5, camera 6 / CAM6) are approximately halfway between the zenith and the horizon (from the horizon). One (camera 7 / CAM7) is arranged near the horizon of the dome 50, and one (camera 1 / CAM1) is arranged at a position 30 ° below the horizon.

  Of course, the number of the imaging units 20 and the arrangement of the imaging units 20 as described above are merely examples, and the present invention is not limited to this. The light emitted by the irradiation unit 10 is reflected from the surface of the inspection object. What is necessary is just to be arrange | positioned so that it can image without leaking light. The camera constituting the imaging unit 20 has an autofocus function and corresponds to various inspection objects. By providing a sufficient amount of light from the irradiation unit 10 arranged in a dome shape to the inspection target surface of the inspection target, it is possible to provide a wide focus depth by narrowing the aperture of the lens.

  The irradiation unit 10 is connected to an illumination power source connected to a light source control unit 40 operating on a PC. The illumination unit 10 receives power controlled by the light source control unit 40 from the illumination power source, and has various luminances, for example, 256 levels. The test object is irradiated with brightness. The light source control unit 40 controls the brightness of each LED, in this embodiment, 512 LEDs, or the brightness of each panel. The imaging unit 20 is connected to an imaging control unit 60 operating on the PC via a LAN hub.

  The imaging control unit 60 acquires an image of the surface of the inspection object from the imaging unit 20 at an appropriate timing in synchronization with the light source control unit 40. The display unit 30 displays an image of the surface of the inspection object acquired by the imaging control unit 60. That is, the display unit 30 displays the light reflected by the surface of the inspection object imaged by the imaging unit 20 as an image.

  The light source control unit 40 controls the luminance of the light source of the irradiation unit 10 so that the gradation of the surface of the three-dimensional inspection object in the image displayed by the display unit 30 is uniform. This control will be described later.

  When light is irradiated onto the surface of an inspection object that is three-dimensional and has a curved surface, and the reflected light is imaged, a portion (out-of-focus or underexposure) exceeding the dynamic range of the camera may occur. If there is a defect such as a scratch in such a portion, the defect cannot be distinguished, resulting in an inspection failure of a defective product. Therefore, by changing the brightness of the light irradiating the surface of the object to be inspected and the irradiation angle with respect to the surface so as not to cause such a portion that becomes overexposed or underexposed, a portion exceeding the dynamic range is not generated. By doing so, or by moving a part that exceeds the dynamic range of the camera, it is possible to inspect all surfaces (including curved surfaces) of the inspection object.

  5 and 6 show a case where the camera 4 images the vehicle window lift switch T as an example of the inspection object shown in FIG. As shown in FIGS. 3 and 4, the camera 4 is a camera that captures an image of the inspection object from behind the inspection object and obliquely above 45 degrees. When the vehicle window elevating switch T is imaged from the camera 4, both the rear surface (FIG. 11C) and the upper surface (FIG. 11B) of the vehicle window elevating switch T are imaged. This imaging surface is a curved surface having no curvature in the left-right direction and having a curvature in the vertical direction in the captured image. The curvature in the vertical direction mainly has a convex curvature, but there is also a part having a concave curvature in part as shown in FIG. 6B.

  FIG. 5A shows that the luminance of the light source of the irradiating unit 10 is set to the same luminance (in this example, the luminance of 32 in 100 steps) when the image is taken by the camera 4. FIG. 5B shows an image captured by the camera 4 when the light source has such luminance. FIG. 5B shows the luminance distribution in the vertical direction (solid line) and the luminance distribution in the horizontal direction (dotted line) in this image. For example, since there is no curvature in the left-right direction of the vehicle window lift switch T, the luminance distribution in the left-right direction is almost constant (dotted line) in the concave curvature portion even when all the light sources of the irradiation unit 10 have the same luminance. ).

  On the other hand, in the vertical direction of the vehicle window lift switch T, there are various curvatures such as convex shape (convex curvature), concave shape (concave curvature), convex shape (convex curvature) from top to bottom, When the camera 4 captures images with all the light sources of the irradiating unit 10 having the same luminance, the vertical luminance distribution (solid line) is greatly different. In other words, the upper part of the image captures the specularly reflected light from the irradiating part around the zenith, so it appears as a very bright luminance, and conversely, the concave part receives too much light from the irradiating part. Therefore, it is reflected as dark luminance, and the luminance distribution changes according to the change in curvature. In this way, especially when imaging a three-dimensional object with a curved surface, if you do not consider the light to irradiate, you will be able to obtain whiteout, blackout and similar images, and discover even if there are scratches etc. I can't.

  In contrast, in FIG. 6A, the light source control unit 40 controls the luminance of the light source of the irradiation unit 10 so that the gradation of the surface of the vehicle window lift switch T in the image displayed on the display unit 30 is uniform. Show things. The luminance of the illumination unit around the camera 4 is set to a medium level (40, 56, 63 in 100 steps), and the regular reflection light is secured, while the luminance of the illumination unit near the zenith is suppressed and the luminance of the eyes (100 steps). In order to avoid overexposure and improve the brightness of the recesses, the brightness of the irradiated area around the rear horizon is increased (95 in 100 steps). As described above, the light source control unit 40 controls the luminance of the light source of the irradiation unit 10, and as shown in FIG. 6B, the convex shape (convex curvature), the concave shape (concave curvature), and the convex shape (convex curvature). Thus, even if there are various curvatures, a substantially constant vertical luminance distribution (solid line) is realized.

  In this way, if the image is displayed so that the luminance distribution on the entire imaging surface is almost constant and the gradation of the inspection target surface of the inspection target is uniform, a slight gradation on the uneven part such as a scratch or a foreign object The difference becomes conspicuous, and it is possible to provide an appearance inspection apparatus that inspects for the presence or absence of defects on the surface of an inspection object that is three-dimensional and has a curved surface.

  FIG. 7 shows that, as described above, when the camera 4 images the vehicle window lift switch T, that is, when one imaging unit 20 captures the same surface multiple times, the light source control unit 40 determines the luminance of the irradiation unit 10. Each of the images is changed, and an image captured by controlling the gradation of the surface to be uniform in each image is shown. FIG. 7A shows the entire imaging surface by suppressing the irradiation from the irradiation unit around the camera 4 to reduce the regular reflection and increasing the irradiation from the irradiation unit far away from the camera 4 instead. It is the image imaged by controlling so that the general luminance becomes the darkest. That is, this figure shows a case where the angle formed by the virtual straight line connecting the surface and the irradiation unit 10 is the largest with respect to the virtual straight line connecting the imaging surface of the inspection object and the imaging unit 20. In addition, when there exists a breadth with an irradiation part, it may be said that it is an average position in the breadth. FIG. 7A shows that a small but remarkable gradation difference part has scratches or irregularities as foreign matters, and this figure shows three fine scratches (AS1, AS2, AS3) is displayed.

  FIG. 7 (B) will be described later with reference to FIG. 7 (A), with more irradiation from the irradiation unit at the intermediate position between the irradiation unit around the camera 4 and the irradiation unit far from the camera 4. It is the image imaged by controlling to perform intermediate irradiation of irradiation of C). That is, this figure shows a case where an angle formed by a virtual straight line connecting the surface and the irradiation unit 10 is intermediate to a virtual straight line connecting the imaging surface of the inspection object and the imaging unit 20. In FIG. 7B, two irregularities as scratches or foreign matters are displayed as AS3 and AS4 in a portion where a remarkable gradation difference occurs.

  Further, FIG. 7C was picked up and imaged in such a manner that the specular reflection was maximized as compared with FIGS. 7A and 7B, with more irradiation from the irradiation unit around the camera 4. It is an image. That is, this figure shows a case where the angle formed by the virtual straight line connecting the surface and the irradiation unit 10 is the smallest with respect to the virtual straight line connecting the imaging surface of the inspection object and the imaging unit 20. In FIG. 7C, two uneven portions as AS2 and AS3 are displayed as a scratch or a foreign substance in a portion where a remarkable gradation difference occurs.

  As understood from the above, even if the same surface is imaged from the same camera so that the gradation of the surface to be inspected is uniform, unevenness such as scratches is displayed as a remarkable gradation difference depending on the irradiation angle. There are things that can and cannot be done. For example, the unevenness of AS3 is displayed in all images, but the unevenness of AS1 is displayed only in (A), and the unevenness in AS4 is displayed only in (B). In this way, if multiple images are obtained under light irradiated at different irradiation angles, a plurality of images are obtained, and OR of irregularities such as scratches captured in each image is taken (if a union is made), Less likely to miss a scratch.

  That is, when the imaging unit 20 captures the same inspection target surface a plurality of times, the light source control unit 40 is configured to connect the surface and the irradiation unit 10 to a virtual first straight line connecting the surface and the imaging unit 20. If the brightness of the irradiating unit 10 is controlled so that the second straight line is imaged at different angles, the uneven portions such as scratches that cannot be found by the reflected light of the light irradiated from one direction are irradiated from different directions. By imaging a plurality of reflected lights, the presence or absence of various uneven portions on a three-dimensional curved surface can be found. In addition, since the brightness of a plurality of irradiation units arranged at different positions is controlled without physically moving the object to be inspected, such as changing the angle of the inspection object, high-speed inspection can be performed.

  Below, the case where light irradiation to the inspection object surface of the inspection object by the light source control unit 40 is performed by two irradiation patterns will be described. One is to irradiate light at an angle that causes regular reflection on the camera so that the gradation of the three-dimensional surface to be inspected in the image displayed on the display unit 30 is uniform. In this illumination pattern (hereinafter referred to as the bright field method), the entire image displayed by the display unit 30 becomes bright, and the unevenness (scratches) on the surface to be inspected appear dark (the luminance decreases).

  The other is to irradiate light on the surface to be inspected from an angle of more than 0 degree and not more than 40 degrees so that the gradation of the three-dimensional surface to be inspected in the image displayed on the display unit 30 is uniform. It is. In this illumination pattern (hereinafter referred to as the dark field method), the entire image displayed by the display unit 30 becomes dark, and the unevenness (scratches) on the surface to be inspected appear bright (the luminance increases).

  More specifically, FIGS. 8 and 9 show irradiation patterns for irradiating the vehicle window raising / lowering switch T of the example of the inspection object shown in FIG. 11 by the bright field method and the dark field method. FIG. 8A shows a method of irradiating the right side surface of the inspection object by the bright field method. The light source control unit 40 illuminates the light source of the irradiation unit 10 in the vicinity of the CAM 5 and between the CAM 5 and the horizon of the dome so that the CAM 5 of the imaging unit 20 images the right side surface of the inspection target T. Light up (LED). These light sources exist at a position where the light that is irradiated toward the surface to be inspected and reflected therefrom reaches the lens of the CAM 5 camera.

  Further, the light source control unit 40 is configured so that the luminance of the entire surface to be inspected with respect to the CAM 5 is an average luminance (in the case of 256 gradation levels, the luminance is in the vicinity of 128 which is an intermediate value). The brightness of these light sources is controlled. The light source control unit 40 controls the light source in this way, so that the gradation of the inspection target surface of the three-dimensional inspection target in the image displayed by the display unit 30 becomes uniform. The closer the gradation of this image is to the center of 128, the greater the deviation from the abnormal value indicated by a scratch or the like. For example, when the surface to be inspected has an average brightness as a whole, unevenness such as a flaw shows a brightness value that is significantly different from the brightness.

  FIG. 8B shows a method of irradiating the front of the inspection object by the bright field method. The light source control unit 40 illuminates the light source from the light source of the irradiation unit 10 immediately above the CAM 1 to the vicinity of the zenith in order to image the front of the inspection target T by the CAM 1 of the imaging unit 20. These light sources exist at a position where the light that is irradiated toward the surface to be inspected and reflected therefrom reaches the lens of the CAM1 camera. Since the surface to be inspected is a curved surface having no curvature in the horizontal direction and having a curvature in the vertical direction, it is only necessary to illuminate the light source in this region.

  The light source control unit 40 controls the luminance of these light sources so that the luminance of the entire surface to be inspected becomes an average luminance with respect to the CAM 1. The light emitted from the light source immediately above the CAM 1 is reflected from the surface to be inspected in a form close to regular reflection, so that the luminance is usually increased. On the other hand, the brightness of light emitted from a light source near the zenith and reflected from the surface to be inspected is usually small. Therefore, in order to make the luminance of the entire surface to be inspected become an average luminance, the luminance of the light emitted from the light source immediately above the CAM 1 is changed to the luminance of the light emitted from the light source near the zenith. Make it relatively small. The light source control unit 40 controls the light source in this way, so that the gradation of the surface of the three-dimensional inspection object in the image displayed by the display unit 30 becomes uniform.

  FIG. 8C shows a method of irradiating the upper surface of the inspection object by the bright field method. The light source control unit 40 illuminates the light source of the irradiation unit 10 in the front-rear direction of the CAM 3 in order to image the upper surface of the inspection target T by the CAM 3 of the imaging unit 20. These light sources exist at a position where light that is irradiated toward and reflected from the surface to be inspected reaches the lens of the CAM 3 camera. Since the surface to be inspected is a curved surface having no curvature in the horizontal direction and having a curvature in the vertical direction, it is only necessary to illuminate the light source in this region.

  The light source controller 40 controls the luminance of these light sources so that the luminance of the entire surface to be inspected becomes an average luminance with respect to the CAM 3. Since the light emitted from the light source closest to the CAM 3 is reflected from the surface to be inspected in a form close to regular reflection, the luminance is usually increased. On the other hand, the brightness of light emitted from a light source located at a position away from the CAM 3 and reflected from the surface of the inspection object is usually small. Therefore, in order to make the luminance of the entire surface to be inspected become an average luminance, the luminance of light emitted from the light source near the CAM 3 is set to the luminance of light emitted from the light source located at a position away from the CAM 3. Make it relatively small compared to. The light source control unit 40 controls the light source in this way, so that the gradation of the surface of the three-dimensional inspection object in the image displayed by the display unit 30 becomes uniform.

  FIG. 8D shows a method of irradiating the back surface of the inspection object by the bright field method. The light source control unit 40 captures the light source of the irradiation unit 10 in the vicinity of the CAM 7 and between the CAM 7 and the horizon of the dome so that the back surface of the inspection target T is captured by the CAM 7 of the imaging unit 20. Shine. These light sources exist at a position where the light that is irradiated toward the surface to be inspected and reflected therefrom reaches the lens of the CAM 7 camera.

  The light source control unit 40 controls the luminance of these light sources so that the luminance of the entire surface to be inspected becomes an average luminance with respect to the CAM 7. The light source control unit 40 controls the light source in this way, so that the gradation of the surface of the three-dimensional inspection object in the image displayed by the display unit 30 becomes uniform.

  The inspection object used for the explanation is a curved surface composed of curvatures in the directions of CAMs 1, 3, and 7 (one direction). Therefore, the luminance of the inspection object surface is made uniform by using the light source on the line of these cameras. It was made to become. When whiteout occurs, it occurs linearly on the front / top / back side between the left and right sides. In this illumination method, it is not necessary to use light in an oblique lateral direction. However, in the case of a curved surface having a curvature in two directions instead of a curvature in one direction, the light source control unit 40 also appropriately uses light sources at other positions to each imaging unit 20 (CAM1 to CAM7). The brightness of these light sources is controlled so that the brightness of the entire surface to be inspected becomes an average brightness.

  In addition, the above-described bright field imaging using a total of four cameras can irradiate four surfaces separately to capture one surface at a time, or simultaneously irradiate four surfaces and image four surfaces at a time. You can also

  FIG. 9A shows a method of irradiating the front of the inspection object by the dark field method. The light source control unit 40 does not use the light source of the irradiation unit 10 immediately above CAM 1 or the light source near the zenith (vertical LED in the drawing) in order to image the front of the inspection target T by the CAM 1 of the imaging unit 20. The light source in the vicinity of the horizon is lit up in the left-right direction as viewed from CAM1. That is, a light source (side LED in the figure) that is positioned so as to sandwich the surface to be inspected as viewed from the camera to be imaged is illuminated. For example, a light source located at a position near 60 ° to 90 ° on both sides with respect to the camera is used. If it is inside, the surface to be inspected will shine and the contrast of the defective part will be lowered. The light emitted from these light sources and reflected from the surface of the inspection object slightly reaches the lens of the CAM1 camera.

  Further, the light source control unit 40 is configured such that the average luminance value of the inspection target surface is about 20 in the case where there are 256 levels of gradations, for example, so that the luminance of the entire inspection target surface is small with respect to CAM1. In addition, the brightness of these light sources is controlled. The light source control unit 40 controls the light source in this way, so that the gradation of the surface of the three-dimensional inspection object in the image displayed by the display unit 30 becomes uniform where the luminance is low. The more uniform the gradation of the image is, the lower the luminance, the greater the deviation from the abnormal value indicated by scratches and the like, and thus the higher the sensitivity, which is preferable.

  FIGS. 9B to 9D show a method of irradiating the left side / right side / back side of the inspection object by the dark field method. The light source control unit 40 does not use the light source in the vicinity of the CAM 6 / CAM 5 / CAM 7 in order to image the left side / right side / back side of the inspection target T by the CAM 6 / CAM 5 / CAM 7 of the imaging unit 20, and uses the CAM 6 / CAM 5 / Lit in the left and right direction as seen from CAM7 and illuminate a light source near the horizon. That is, the light source located at a position where the surface to be inspected is sandwiched as viewed from the camera to be imaged is illuminated. A small amount of the light emitted from these light sources and reflected from the surface of the inspection object reaches the lens of the CAM6 / CAM5 / CAM7 camera.

  Further, the light source control unit 40 has an average luminance value of the inspection target surface of about 20 when there are 256 gradations so that the luminance of the entire inspection target surface is smaller than that of the CAM6 / CAM5 / CAM7. The luminance of these light sources is controlled so that the luminance is obtained. The light source control unit 40 controls the light source in this way, so that the gradation of the surface of the three-dimensional inspection object in the image displayed by the display unit 30 becomes uniform.

  In the dark field imaging described above, the bright field imaging using a total of four cameras can irradiate four surfaces separately to capture one surface at a time. It is also possible to image four sides at a time. However, it cannot be performed simultaneously with bright field imaging.

  As described above, the light source control unit 40 is three-dimensional by controlling the luminance of each irradiation unit so that the gradation of the three-dimensional inspection target surface in the image displayed on the display unit 30 is uniform. The presence or absence of defects on the surface of the inspection object having a curved surface can be inspected. In addition, the light source control unit 40 irradiates light at an angle close to a right angle to the inspection target surface so that the camera to be imaged is regularly reflected, and the gradation of the three-dimensional inspection target surface in the image displayed on the display unit 30 is uniform. In addition, the surface of the inspection target is irradiated with light from an angle of about 30 degrees, and the gradation of the three-dimensional inspection target surface in the image displayed on the display unit 30 is controlled to be uniform. According to this, it is possible to provide an appearance inspection apparatus that can inspect the presence or absence of defects on the surface of an inspection object that is three-dimensional and has a curved surface with higher accuracy.

  Inspecting the presence or absence of defects such as scratches on the surface of the inspection object, the inspector may determine the presence or absence of defects by visually observing the surface of the inspection object displayed on the display unit 30, or uniform. When the deviation from a certain gradation becomes larger than a predetermined value, it may be automatically determined as a defect.

  Moreover, it is preferable that the light source control part 40 controls so that the gradation of the three-dimensional inspection object surface in the image which each camera of the imaging part 20 images becomes uniform. According to this, by displaying each image so that the gradation of the surface of the inspection object is uniform, the surface of the inspection object having a three-dimensional and curved surface can be viewed from a plurality of directions at a time. The presence or absence of defects can be inspected.

  Further, the appearance inspection apparatus 1 captures images other than the bottom surface of the three-dimensional inspection target T without moving the inspection target T and the imaging unit 20. According to this, it is possible to inspect the three-dimensional inspection object at high speed and at low cost by imaging other than the bottom surface of the three-dimensional inspection object at a time without moving the inspection object T and the imaging unit 20. .

  The appearance inspection apparatus 1 according to the present invention includes an irradiation unit 10 arranged in a 360-degree hemisphere on an inspection object and an imaging unit 20 (camera) from seven directions, and adjusts the position and luminance of the light source for each camera. For example, high-speed inspection of about 1 second per inspection object can be performed by continuously imaging without moving the inspection object. The appearance inspection apparatus 1 changes the angle of light irradiated to the inspection object by switching the irradiation unit 10 arranged in all directions, and changes the angle of light irradiation even with the same camera, so that each curved surface is changed. The amount of reflected light can be adjusted. As a result, the appearance inspection apparatus 1 can capture images with an inexpensive camera with a low dynamic range by narrowing the range of gradations to be received, thereby enabling an inexpensive inspection.

  FIG. 10 shows a display example of the display unit 30 in the appearance inspection apparatus 1. In this display example, one display unit 30 integrally displays images acquired from seven cameras, automatically determines the presence / absence of a defect, and displays the determination result in characters or the like.

  The inspection object to be inspected by the appearance inspection apparatus according to the present invention is not limited in shape, size, or the like as long as it is composed of a surface that can be directly irradiated with light from the surroundings.

  In addition, this invention is not limited to the illustrated Example, The implementation by the structure of the range which does not deviate from the content described in each item of a claim is possible. That is, although the present invention has been particularly illustrated and described with respect to particular embodiments, it should be understood that the present invention has been described in terms of quantity, quantity, and amount without departing from the scope and spirit of the present invention. In other detailed configurations, various modifications can be made by those skilled in the art.

DESCRIPTION OF SYMBOLS 1 Appearance inspection apparatus 10 Irradiation part 20 Imaging part 30 Display part 40 Light source control part 50 Dome part 60 Imaging control part T Inspection object

Claims (5)

A plurality of irradiation units for irradiating light on the surface of the three-dimensional inspection object;
An imaging unit that images light reflected from the surface by the light irradiated by the plurality of irradiation units;
A display unit that displays light captured by the imaging unit as an image;
A light source control unit for controlling the luminance of the plurality of irradiation units;
With
The light source control unit controls the luminance of each irradiation unit so that the three-dimensional gradation of the surface in the image displayed by the display unit is uniform.
Appearance inspection device. The imaging unit images light reflected from the same surface multiple times,
The light source control unit, when the imaging unit images the same surface a plurality of times, is a virtual second line connecting the surface and the irradiation unit with respect to a virtual first straight line connecting the surface and the imaging unit. The appearance inspection apparatus according to claim 1, wherein the brightness of the irradiating unit is controlled so that the straight lines are imaged at different angles. It further includes a substantially hemispherical dome,
The visual inspection apparatus according to claim 2, wherein the plurality of irradiation units are disposed on an inner surface of the dome unit. The imaging unit consists of a plurality of
The appearance inspection apparatus according to claim 3, wherein the light source control unit controls the three-dimensional gradation of the surface in an image captured by each of the imaging units to be uniform.   The plurality of imaging units are arranged in the dome unit, and images other than the bottom surface of the three-dimensional inspection object without moving the inspection object and the imaging unit. Appearance inspection device.