JP2020041800A - Visual inspection device and inspection system - Google Patents

Abstract

To provide a visual inspection device capable of quickly and accurately detecting a defect on a surface of a test specimen.SOLUTION: A visual inspection device 10 includes: a holder 11 for placing a test specimen; a dome-shaped reflector 12 having a concave surface facing an observation surface side of the test specimen; a light source unit 13 that emits light for illuminating the concave surface with substantially uniform illuminance, which is located on the opposite side of the observation surface of the test specimen; and a rotation mechanism 14. The reflector 12 has: a transmission section 122 that transmits incident light emitted from the light source unit 13 and reaching the concave surface; a bright section 124 that reflects the incident light so as to fall on a surface to be observed; and a dark section 126 that has a lower reflectance than the bright section 124 and creates a shadow on the surface to be observed. The rotation mechanism 14 performs a rotating operation of switching at least a part of the observation surface between a dark state having a shadow formed by the dark section 126 and a bright state having no shadow, by changing the relative posture of the test specimen with respect to the dark section 126 by rotating at least one of the holder 11 and the dark section 126.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for inspecting the appearance of a surface of a test object in a quality inspection, and a system including the apparatus.

  A test object having a smooth surface reflects illumination light emitted from one direction only in one direction without diffusely reflecting the illumination light. Therefore, in the appearance inspection of the surface of the test object, it is necessary to adjust the direction of the light source so that the illumination light reflected on the surface, that is, the reflected light is directed toward a certain position of the eye or camera lens to be observed. .

  The direction in which the reflected light travels is determined by the angle of the surface on which the illumination light is incident with respect to the incident light. Therefore, in the case where the illumination light is only from one direction, if the surface of the test object is a curved surface, all of the objects do not appear to have uniform brightness. When the brightness of the surface is not uniform, the reflection of the light source becomes an extreme highlight, and the range where the reflected illumination light does not reach the eyes becomes dark and difficult to see. Such appearance significantly lowers the accuracy of the visual inspection. Such an appearance inspection of the test object can be appropriately performed by observing the entire surface while changing the positional relationship between the light source, the test object, and the observation position. However, in such a method, a certain length of inspection time is required, or when inspector's hand is involved in the inspection process, the inspector's skill is required to minimize the inspection time and to secure the accuracy. Is required.

  For example, the dome-shaped lighting device disclosed in Non-Patent Document 1 irradiates the test object with light from all directions except the top, thereby suppressing the occurrence of highlights and minimizing the occurrence of shadows. Enables observation of a wide range of the observation surface.

  Further, in the invention described in Patent Document 1, the diffused light emitted from behind the test object is reflected by the entire concave surface of the hemisphere composed of the half mirror to irradiate the test object with illumination light from all directions at once, The test object is observed through the half mirror.

  As a result, even if the object is a three-dimensional object including a curved surface on the surface to be observed, such as a lens, no highlight or shadow is generated, and the entire surface to be observed including the top is almost uniformly illuminated. It is possible to observe at a glance.

JP-A-2006-125871

"HPD2 series", [online], CCS Inc., [Searched September 5, 2018], Internet, <URL: https://www.ccs-inc.co.jp/products/series/169>

  The device according to the prior art, if there is a defect such as spots, uneven color, or foreign matter adhered to the surface of the test object, the difference in appearance due to the difference in the reflectance or color tone between the defect and other parts. Based on this, the defect can be detected with high accuracy. However, irregularities such as scratches on the surface, that is, there is a change in the shape, but the reflectance or color tone has little difference from other parts, shadows are less likely to occur by falling illumination light from multiple directions Above, there is a problem that it is difficult to perform highly accurate detection with the device according to the related art because it looks the same as the other parts.

  According to the present invention, there is provided a device or the like capable of performing a visual inspection for detecting a defect having a small change in color or reflectance, such as a scratch on the surface of a test object, quickly and accurately.

  An appearance inspection apparatus according to one embodiment of the present invention provided to solve the above-described problem is an appearance inspection apparatus that inspects the appearance of the object using a reflected light image formed by light reflected by the object. A holding table for holding the test object, a dome-shaped reflector positioned on the observation surface side of the test object and having a concave surface facing the observation surface, and a test object of the test object. A light source unit that is located on the opposite side of the observation surface and emits light for illuminating the concave surface with substantially uniform illuminance; and a rotating mechanism, wherein the reflector is configured to emit the light source unit and reach the concave surface. A transmitting portion that transmits the incident light, a bright portion that reflects the incident light and falls on the surface to be observed, and a dark portion that has a lower reflectance than the bright portion and forms a shadow on the surface to be observed. The rotating mechanism rotates at least one of the holding table and the dark portion to rotate the dark portion. Wherein by changing the relative position of the test object to, perform at least a portion of said observation target surface, and a dark state in which there is a shadow made of the dark portion, the rotating operation of switching between a bright state is not the shadow.

  Further, the appearance inspection system according to one embodiment of the present invention further receives the incident light reflected by the concave surface and once falling on the surface to be observed, and reflected by the surface to be observed and transmitted through the transmitting portion. An appearance inspection device including an imaging unit that captures an image of the surface to be observed, and an image processing device, wherein the image processing device is configured to perform the rotation operation to change the rotation mechanism. An input unit that receives an input of a plurality of images of the observation surface photographed by the imaging unit, of the test object in a relative posture, and analyzes the plurality of input images to obtain an image of the observation surface. An image analysis unit for detecting a defect and an output unit for outputting data of information indicating the detected defect are provided.

  Note that these comprehensive or specific aspects may be realized by a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM in which the computer program is recorded. , A method, an integrated circuit, a computer program, and a recording medium.

  The appearance inspection and appearance inspection system according to the present invention can quickly and accurately detect a defect such as a flaw on the surface of the test object, which has a small change in color or reflectance.

FIG. 1 is a schematic diagram for explaining the outline and configuration of a visual inspection system including a visual inspection device according to an embodiment. FIG. 2 is a diagram for explaining the outline of the above-described visual inspection apparatus. FIG. 3A is a perspective view illustrating an appearance of an example of a reflector included in the appearance inspection apparatus. FIG. 3B is a bottom view showing the appearance of an example of the reflector included in the above-described appearance inspection device. FIG. 4A is a schematic diagram for explaining the principle of the appearance inspection using the above-described appearance inspection device. FIG. 4B is a schematic diagram for explaining the principle of the appearance inspection using the above-described appearance inspection device. FIG. 5A is a schematic diagram for explaining the principle of the appearance inspection using the above-described appearance inspection device. FIG. 5B is a schematic diagram for explaining the principle of the appearance inspection using the above-described appearance inspection device. FIG. 6 is an example of an image of a test object taken by the above-described visual inspection apparatus. FIG. 7 is a block diagram illustrating an example of a functional configuration of a camera and an image processing device included in the appearance inspection apparatus. FIG. 8 is a diagram illustrating a hardware configuration example of the image processing apparatus. FIG. 9A is a schematic diagram for explaining an image of a test object acquired by the above-described image processing system. FIG. 9B is a schematic diagram for explaining an image including a defect detected by the above-described image processing system. FIG. 9C is a schematic diagram for explaining a state in which an image including a defect image is superimposed on the image of the test object. FIG. 10 is a diagram illustrating another configuration example of the reflector. FIG. 11 is a diagram showing another configuration example of the above reflector. FIG. 12 is a diagram illustrating another configuration example of the above-described reflector. FIG. 13 is a diagram illustrating another configuration example of the above-described reflector. FIG. 14 is a diagram illustrating another configuration example of the above-described reflector.

  Hereinafter, a visual inspection system according to an embodiment will be described with reference to the drawings.

  The following embodiment shows a comprehensive or specific example of the present invention. Therefore, the numerical values, shapes, materials, constituent elements, arrangement and connection forms of the constituent elements, the steps (processes), the order of the steps, and the like shown in the following embodiments are examples and limit the present invention. is not. Among the components in the following embodiments, components not described in the independent claims are components that can be arbitrarily added. In addition, each drawing is a schematic diagram, and is not necessarily strictly illustrated.

(Embodiment)
The visual inspection system according to the present embodiment is used for inspection by dark-field observation (hereinafter also referred to as epi-illumination-type dark-field inspection) performed while emitting illumination light from multiple directions over the entire observation surface of a test object. Can be Hereinafter, the appearance inspection system 1 according to the present embodiment will be described.

[Outline of configuration of visual inspection system]
FIG. 1 is a schematic diagram for explaining the outline and configuration of a visual inspection system 1 including a visual inspection device 10 in the present embodiment. FIG. 2 is a diagram for explaining the outline of the visual inspection device 10. FIG. 3A is a perspective view illustrating the appearance of an example of a reflector included in the appearance inspection device 10, and FIG. 3B is a bottom view illustrating the appearance of an example of the reflector included in the appearance inspection device 10.

  The visual inspection system 1 includes a holding table 11, a reflector 12, a light source 13, a rotation mechanism 14, a camera 15, and an image processing device 20.

  The holding table 11 holds the test object such that a surface to be inspected by the appearance inspection of the test object (hereinafter, referred to as an observation surface) is exposed.

  The reflector 12 is a dome-shaped object having a concave surface facing the observation surface of the test object, in the illustrated example, and facing the observation surface of the test object, and emits light emitted by the light source unit 13. The light is reflected and falls on the surface to be observed. Further, the reflector 12 has a transmitting portion 122 that transmits incident light that reaches the concave surface. The reflector 12 is made by molding a transparent resin such as polycarbonate into a dome shape. In addition, a portion other than the transmission portion 122 of the reflector 12 is provided with an optical characteristic of reflecting the incident light on the concave surface with a different reflectance depending on the location by using a vapor deposition film, a paint, or a film. According to the bottom view of FIG. 3B, the concave surface of the reflector 12 has a bright portion 124 and a dark portion 126 that are not seen in the convex surface shown in FIG. 3A. The bright part 124 reflects the incident light and causes the incident light to fall on the observation surface of the test object. Further, the dark part 126 has a lower reflectance than the bright part 124 and forms a shadow on the surface to be observed of the test object. Hereinafter, an area of the observation surface having a shadow created by the dark portion 126 is referred to as a dark area, and a state of the dark area having the shadow is also referred to as a dark state. Further, an area of the observation surface having no shadow created by the dark portion 126 is referred to as a bright area, and a state of the bright area having no shadow is also referred to as a bright state. The detailed configuration of the reflector 12 will be described later using a specific example.

The light source unit 13 is a surface illumination (flat illumination) that is located on the opposite side of the observation surface of the test object and faces the concave surface of the reflector 12, and illuminates the concave surface with substantially uniform illuminance. Emit diffused light. The arrows in FIG. 1 schematically show how light emitted by the light source unit 13 travels in a space surrounded by the concave surface of the reflector 12. As indicated by these arrows, the light reflected by the concave surface of the reflector 12 falls on the test object held by the holding table 11 from multiple directions.
The rotation mechanism 14 includes a motor and rollers connected to a shaft of the motor. The roller is in contact with the reflector 12, and the motor operates to rotate the roller, thereby rotating the reflector 12.

  The camera 15 is, for example, a digital camera that captures and acquires an image of the observation surface of the test object surrounded by the reflector 12 through the transmission unit 122. 1 and 2 show the optical axis of the optical system of the camera 15.

  The appearance inspection apparatus 10 includes the above-described holding table 11, reflector 12, light source unit 13, rotation mechanism 14, and camera 15, and has an appearance as shown in FIG. 2, for example. In FIG. 2, the illustration of the reflector 12 and various wirings for transmitting drive power, control signals, imaging data, and the like is omitted. The reflector 12 is provided with a brim at the edge as shown in FIG. 3A, and is placed so that the brim is supported by three rollers. As the roller rotates, the reflector 12 rotates about the y-axis. The axis of rotation substantially coincides with the optical axis of the camera 15. The camera 15 receives the reflected light of the test object, which is transmitted through the transmission part 122 of the reflector 12 placed as described above, and receives the reflected light by an image sensor (not shown) to capture an image. The image sensor constitutes a photographing unit in the present embodiment.

  The image processing device 20 receives an input of an image captured by the camera 15 and performs an appearance inspection of the test object using the image. The image processing device 20 is realized by, for example, a personal computer as illustrated. The detailed configuration of the image processing device 20 will be described later using an example.

[Configuration of reflector]
The configuration of the reflector 12 will be described with reference to FIGS. 3A and 3B again.

  In the example shown in FIGS. 3A and 3B, the reflector 12 is opaque except for the transmission part 122.

  As described above, the bright portion 124 is a region that reflects the incident light that is emitted from the light source unit 13 and reaches the concave surface of the reflector 12 and is incident on the observation surface of the test object held by the holding table 11. . The light portion 124 is, for example, white (including an approximate color such as gray white or milky white), silver, or a mirror surface due to the material of the reflector 12 or a coating agent or a film covering the concave surface thereof. The color and reflectivity of the light portion 124 may be any value as long as the contrast between light and dark on the surface to be observed can be obtained with the strength necessary for the inspection described later by using the dark portion 126 together with the color. Are the items that can be changed for reasons such as the surface color or reflectance, the intensity or color temperature of the light emitted from the light source unit 13, or the necessity or convenience in image processing in a subsequent process.

  The dark part 126 is an area for forming a shadow on the surface to be observed, and has a lower reflectance than the bright part 124. The dark portion 126 is, for example, a dark color such as black or brown which absorbs substantially all or most of incident light due to the material of the reflector 12 or a coating agent or a film covering the concave surface. The color and the reflectance of the dark portion 126 may be used in combination with the bright portion 124 so long as the contrast of light and dark on the surface to be observed can be obtained with the strength required for the inspection described later. However, in the figures after FIG. 3B, the dark area is shown as a shaded area, but the density of the shade does not limit the color or the reflectance of the dark area or their difference from the light area.

  When the reflector 12 rotates, the relative posture of the test object with respect to the dark part 126 changes, and the dark area formed on the observation surface of the test object moves. The size, shape, and arrangement of the dark portion 126 on the concave surface of the reflector 12 are such that the shadow of the dark portion 126 passes at least once at every point on the surface to be observed while the reflector 12 makes one round by the rotating mechanism 14. Adjusted in advance. In other words, while the reflector 12 makes one round by the rotation mechanism 14, the entire surface of the surface to be observed becomes a bright region and a dark region at least once, or at least once in the dark state and the bright state. Switch.

  In the example illustrated in FIG. 3B, the plurality of dark portions 126 having a circular contour are spirally arranged from a position near the center of the concave surface to the edge. The size and interval of these dark portions 126 (which are also the shape and size of the bright portions 124) are assuming meridians on a concave surface. 126 are adjusted so as to overlap with both of them at one or more locations. As a result, the shadow of the dark part 126 passes at least once at every point on the surface to be observed while the reflector 12 makes one round.

  Next, with the appearance inspection apparatus 10 configured as described above, a defect due to a change in the shape (irregularity) of the surface of the test object, which has been difficult to detect by the appearance inspection using the conventional technology, is more accurately detected. The principle of realizing the inspection will be described.

[Principles underlying inspection]
4A, 4B, 5A, and 5B are schematic views for explaining the principle of the appearance inspection using the appearance inspection device 10. FIG. More specifically, FIG. 4A shows a state in which the specular surface of the test object has irregularities, and FIG. 4B shows a state in which a part of the specular surface of the test object has irregularities. FIG. 5A shows a part of the situation of FIG. 4A, and FIG. 5B shows a part of the situation of FIG. 4B in an enlarged and emphasized manner for convenience of explanation. Also, in these figures, only one dark part 126 is shown for illustration.

  In this example, when a dark area on the surface of the test object is captured in an image captured by the camera 15, the angle formed by the dark area 126, the dark area, and the camera that provides the dark area is determined by the angle of the object where the dark area is located. It is bisected by the normal line of the specimen surface (the dashed line in the figure). In other words, the incident angle (the angle between the solid line arrow starting from the dark part 126 and the normal line in the figure) and the reflection angle (in the figure, the solid line starting from the surface of the test object). The angle between the arrow and the normal) is equal according to the law of reflection.

  In addition, light incident on the surface of the test object after being reflected outside the dark portion 126, that is, the light portion 124, also obeys the law of reflection, so that the incident angle and the reflection angle are equal.

  FIG. 4A illustrates the relationship between the incident angle and the reflection angle described above. As shown in FIG. 4A, the light reflected by the bright part 124 and falling into the dark area viewed from the position of the camera 15 (in the figure, a dotted arrow starting from the outside of the dark part 126) is reflected by the camera 15. Does not enter the optical system (in the figure, a dotted arrow starting from the surface of the test object). In FIG. 5A, incident light to the test object indicated by an arrow A and its reflected light indicated by an arrow rA, incident light indicated by an arrow B, reflected light indicated by an arrow rB, and indicated by an arrow C The incident light and the arrow rC exemplify the light traveling in this manner.

  As described above, in the test object having a mirror-like surface, the dark region provided by the dark portion 126 entirely reflects the color of the dark portion 126.

  On the other hand, in the case of a test object having irregularities due to scratches or the like on the painted surface, incident light is scattered at the irregularities. Therefore, as shown in FIG. 4B, light reflected from the dark portion 126, that is, the light reflected by the bright portion 124 and falling into the dark area viewed from the position of the camera 15 also enters the optical system of the camera 15. FIG. 5B illustrates the light traveling in this manner. There are fine irregularities in the dark area provided by the dark part 126. Light reflected outside the dark area 126 and falling into this dark area can enter the optical system of the camera 15 as shown in FIG. 5B when reflected according to the law of reflection on the surface of the test object at the falling position. In FIG. 5B, the light incident on the test object indicated by the arrow C and the reflected light indicated by the arrow rC exemplify the light traveling in this manner. The arrow C in FIG. 5A and the arrow C in FIG. 5B indicate incident light from the same position of the reflector 12. In reality, the irregularities on the surface of the test object have a more complicated shape, and scatter incident light on the irregularities. The light that has proceeded in this way is observed as a brighter portion reflecting the shape of the unevenness in the dark region.

  FIG. 6 is an example of an image of a test object (part) by the visual inspection device 10. In FIG. 6, a brighter line, which is indicated by a white arrow and extends left and right in the oval-shaped dark area, indicates a flaw on the surface of the test object. Comparing the portion of the flaw in the dark region with the portion in the bright region near the right end, the difference in visibility is remarkable.

  In the appearance inspection apparatus 10, such a dark state is established once at every point on the observation surface of the test object by changing the relative posture of the test object with respect to the dark part 126. Then, the camera 15 acquires an image of the observation surface in the dark state. The image processing device 20 that acquires the image thus acquired from the camera 15 detects a flaw on the surface of the test object based on, for example, a luminance difference between the periphery of each pixel and the image.

  In addition, when the transmissive part 122 is in a position where the transmissive part 122 appears on the observation surface when viewed from the observation position, a dark area due to the dark part 126 cannot be formed. Therefore, the inspection is performed by changing the relative posture of the test object with respect to the dark part 126 by, for example, tilting the test object. Further, even when the surface to be observed includes a portion parallel or substantially parallel to the optical axis of the camera 15, the camera 15 cannot capture an image of the portion. Therefore, in this case as well, the relative posture of the test object with respect to the dark portion 126 is changed by, for example, tilting the test object, and the image is further photographed for inspection.

  In addition, the law of reflection is valid everywhere on a specular surface. In the bright region, light that should enter the optical system of the camera 15 without irregularities on the surface of the test object does not enter the optical system due to the irregularities. A method of detecting a flaw can also be used.

[Configuration of Camera and Image Processing Device]
FIG. 7 is a block diagram illustrating a functional configuration example of the camera and the image processing device 20 included in the appearance inspection device 10. FIG. 8 is a diagram illustrating an example of a hardware configuration of the image processing apparatus 20.

  As shown in FIG. 7, the camera 15 includes a photographing unit 151 and a communication unit 152.

  The imaging unit 151 once falls on the surface to be observed from the reflector 12, receives light that has been reflected by the surface to be observed and transmitted through the transmission unit 122, and photographs an image of the surface to be observed. The optical system includes one or more lenses, and forms an image suitable for inspection of a surface to be observed on an image sensor. The image sensor converts the received light into an electric signal and outputs the electric signal. The image data based on the electric signal is transmitted to the image processing device 20 by the communication unit 152.

  The image processing device 20 includes an input unit 202, an image analysis unit 204, an image integration unit 206, and an output unit 208.

  The input unit 202 receives, from the camera 15, input of image data of a plurality of images of a surface to be observed of a test object. These images include those taken when the relative posture of the test object with respect to the dark part 126 is different.

  The image analysis unit 204 analyzes image data of a plurality of images received by the input unit 202 and detects defects on the surface to be observed. The defect here is, for example, a flaw on the surface of the test object detected based on the luminance difference as described above. Further, the defects detectable in the light area may include spots, uneven color, adhesion of foreign matter, and the like. Note that a flaw having a certain size or depth may be detectable even in a bright area. In the analysis of an image for detecting a defect, the image analysis unit 204 includes, for example, segmentation (division into small areas), calculation of a difference based on pixels or pixel values between small areas, edge detection, and edge detection. Threshold processing of the size (area, length, or number of pixels) of continuous pixels having pixel values or various numerical values is executed.

  The image integration unit 206 generates one image indicating the defect of the subject detected by the above analysis, and superimposes and integrates the image with the image of the subject.

  The output unit 208 outputs data of information indicating the detected defect. The output here is, for example, an output of image data to a display for presenting an image obtained as a result of the integration by the image integration unit 206 to a user. Further, for example, it is output of inspection result data for accumulation in a storage device inside or outside the appearance inspection device 10. Also, for example, the output of data to a program for another process, for example, a statistical process of test results.

  Each of the above-described components of the image processing apparatus 20 is provided by executing a predetermined program in a personal computer or the like that implements the appearance inspection apparatus 10.

  As shown in FIG. 8, for example, a personal computer that implements the visual inspection device 10 includes a CPU (Central Processing Unit) 201, a main storage device 203, an auxiliary storage device 205, a display 207, and an input I / F (Interface). 209) and a communication I / F 211.

  The CPU 201 is a processor that executes a control program stored in the auxiliary storage device 205 or the like.

  The main storage device 203 is a volatile storage area used as a work area used when the CPU 201 executes a program.

  The auxiliary storage device 205 is a non-volatile storage area that stores a control program and a predetermined program for realizing each of the above-described components of the image processing device 20.

  The display 207 is a display device that displays a video including an image. For example, the display 207 is a liquid crystal display, an organic EL display, or the like.

  The input I / F 209 is an interface for receiving an input from a user. The input I / F 209 may be a pointing device such as a mouse, a touch pad, a touch panel, or a trackball, or may be a keyboard.

  The communication I / F 211 is a communication interface for communicating with the camera 15 via a communication network. Communication I / F 211 may be a wired communication interface or a wireless communication interface.

[Overview of the operation of the visual inspection system]
Next, an operation for a visual inspection by the visual inspection system 1 including the image processing device 20 including such components will be described using an example.

  The operation for appearance inspection by the appearance inspection system 1 is as follows. The test object is placed on the holding base 11 with the surface to be observed facing the camera 15, and the reflector 12 is placed on the rotating mechanism 14 in an appropriate posture. And then start.

  With the light source unit 13 emitting diffused light toward the concave surface of the reflector 12, the camera 15 is moved over the reflector 12 (transmission unit 122) every time the rotating mechanism 14 rotates the reflector 12 by a fixed amount. Take an image of the inspection object. The amount of one rotation is determined in advance based on the size of the dark part 126 or the light part 124 of the reflector 12. The rotation and the photographing are continued at least once on the entire surface to be observed until the dark state and the bright state are switched. During this imaging, the relative position and orientation of the subject and the camera 15 do not change, and the relative positions and orientations of the subject and the camera 15 and the dark part 126 and the bright part 124 change. Therefore, the plurality of images captured in this manner are all images of the same spatial region, and the position and orientation of the test object in the image are constant, and the dark portion 126 reflected on the test object is included. , There is a difference in the position, size and shape of the dark area.

  In the image processing apparatus 20, the input unit 202 accepts input of data of the plurality of images. FIG. 9A is a schematic diagram for explaining an image of the test object captured by the camera 15 when the input unit 202 receives data input. In this image, the observation surface of the test object is shown with the top surface of the holding table 11 as a background. The shaded portion of the observed surface is a dark region, and the other portions are bright regions. The test object shown as an example in FIG. 9A is a substantially parallelogram frame material in a plan view, has a cross-sectional shape of a middle and high bow, and has a complicated surface angle as a whole. Due to such a shape of the test object, even when the dark portion 126 has a circular shape as shown in FIG. 3B, the dark region has various shapes different from the circular shape when viewed from the observation position.

  The image analysis unit 204 analyzes this data and detects a defect on the observed surface in each image. FIG. 9B is a schematic diagram for explaining an image including a defect detected by the image analysis unit 204. The image analysis unit 204 detects the defect by executing the above-described processing, and specifies the pixel on which the detected defect appears. For example, the image analysis unit 204 extracts a lighter part (pixel) in a dark area or a darker part (pixel) in a light area by threshold processing, and furthermore, a size of a continuous group of such pixels. It is determined based on (area, length, or number of pixels) whether or not the pixel has a defect. After that, the image analysis unit 204 generates data of one image in which the pixel showing the defect specified in each image is changed to a predetermined color. FIG. 9B is an example of an image represented by this data. In FIG. 9B, the pixels with the detected defects appear as black portions scattered in the image indicated by the frame.

  The image integration unit 206 superimposes the defect image detected by the image analysis unit 204 on any one of the plurality of images. FIG. 9C is a schematic diagram for explaining an image generated by the image integration unit 206 in this manner. The image shown in FIG. 9C is generated by superimposing the defect image in the image shown in FIG. 9B on the image shown in FIG. 9A.

  The data of the image generated by the image integration unit 206 is output from the output unit 208, and is displayed on a screen or printed on paper, presented to a user, or stored in a storage device.

[Modification of reflector]
The reflector 12 configured as described above is an example of a reflector that the visual inspection device 10 should have to detect a defect as described above. Various modifications are possible as long as the concave portion of the reflector to be included in the visual inspection device 10 includes a bright portion and a dark portion, which are two types of regions having different reflectances. Hereinafter, description will be made with reference to a modification.

  First, the dark part illustrated in FIG. 3B is an example of a shape suitable for detecting scratches in various directions. The flaw in the dark area is easily detected when the falling light hits at right angles to the direction in which the flaw extends, and is hard to detect when it hits in parallel. Since light enters from all directions around the dark area formed by the dark part illustrated in FIG. 3B, the possibility of detecting a scratch is increased, and the accuracy of the inspection is improved.

  The shape of the dark portion is not limited to a circle, but may be a polygon such as a rectangle. However, in the inspection by the visual inspection device 10, the presence or absence of a flaw in the dark area is determined based on whether or not the light falling obliquely to the dark area is reflected irregularly. In other words, the light falling from the oblique direction to the dark area is the inspection light in the epi-illumination dark field inspection, and it is desirable that the light falls from all directions in one dark area under the same conditions as much as possible. In this respect, the shape of the dark part is most preferably circular, but an effect similar to a circular dark part can be obtained even with a polygon such as a rectangle.

  FIGS. 10 and 11 show other examples of the shape of the dark portion suitable for detecting a flaw.

  In the example shown in FIG. 10, two dark portions 126A extending between the periphery of the transmission portion 122A of the reflector 12A and the end of the reflector 12A have a latitude of 10 which is assumed assuming the reflector 12A as a hemisphere. At every degree, it bends +45 degrees or -45 degrees when viewed in the normal direction of the concave surface. In the example shown in FIG. 11, the contour of the dark portion 126B of the reflector 12B has a trapezoidal waveform in which a +45 degree portion and a -45 degree portion appear alternately with respect to the meridian (or latitude line) on the concave surface. In addition, the parallels located at any positions on the concave surface of the reflector 12B outside the range of the transmission part 122A or 122B are arranged vertically in the figure so as to intersect both the +45 degree part and the −45 degree part of the contour. The period in the meridian direction of the contour is shifted between the dark portions 126B. As described above, even in a dark area where a contour intersects with a latitude line having the same latitude at a plurality of locations and an intersection angle varies depending on the intersection, a light incident condition that is disadvantageous for detecting a flaw on the surface of the test object is used. Direction is reduced.

  Note that the shapes of the dark portions shown using the angles (10 degrees, +45 degrees, and -45 degrees) included in the above description of FIGS. 10 and 11 are examples, and the shape of the dark portions of the reflector is not limited thereto. Not done. For example, as a modified example of the dark portion as shown in FIG. 10, the contour may be finer and bend in small increments, or a continuous curve is also suitable. The shape of the dark part shown in FIG. 10 and FIG. 11 corresponds to the direction in which a plurality of boundaries between the dark part and the light part run on an arbitrary point on the test object due to the rotation of the reflector (the normal to the concave surface of the reflector). This is an example of the detection that can be performed with higher accuracy while suppressing the influence of the running direction of the flaw including the point by having variations in the angle viewed in the direction. That is, by using a reflector having a dark portion having such a shape, the same effect can be obtained without being limited to the examples shown in FIGS.

  The size of the dark part is appropriately determined according to the depth of the flaw to be detected and the degree of change in the size, height, and curved surface of the entire test object. For example, when the flaw is shallow, that is, when the angle at which the flaw enters the surface of the test object is small, the change width of the reflection angle is small. Therefore, the smaller the incident angle of the light falling from the bright part on the surface of the test object, the easier the detection of the flaw. However, if the dark part is small, the dark area becomes thin (bright). However, depending on the darkness of the dark area, the contrast with the bright part is low due to diffuse reflection due to the scratches, making it difficult to detect the scratches. Therefore, in order to maintain the accuracy, the dark portions need to have a certain size. In addition, when the test object is large, the detection of the flaw is easier in the larger dark part. In addition, when a change in the curved surface of the surface of the test object is large, a dark region on the observation surface is greatly distorted. Therefore, the size of the dark part is determined so that the distorted dark area has a size suitable for the flaw to be detected.

  As described above, the arrangement of the dark part is adjusted in advance so that the shadow of the dark part passes at least once at every point on the observation surface while the reflector makes one round. FIG. 3B shows an example in which the adjustment is performed in such a manner. However, the number of dark portions may be smaller. FIG. 12 and FIG. 13 are examples of the arrangement of fewer dark portions on the concave surface of the reflector.

  In the example of FIG. 12, the circular dark part 126C is arranged only in a substantially half area of the reflector 12C. However, if the reflector 12C makes a round around the y-axis, the shadow of the dark part passes at least once through every part of the observation surface of the test object held by the holding table 11 and surrounded by the reflector 12C. The position of the dark part on the concave surface in the latitude direction is adjusted in advance. In such an arrangement, defects such as spots and color unevenness can be easily detected by using the upper half area of the figure without dark portions.

  In the example of FIG. 13, a circular dark portion 126D is arranged along four latitude lines on the concave surface of the reflector 12D. Also in this example, if the reflector 12D makes a round around the y-axis, the shadow of the dark part passes at least once through any part of the observation surface of the test object held by the holding table 11 and surrounded by the reflector 12C. The position of the dark part on the concave surface in the latitude direction is adjusted in advance. For example, when each dark portion 126D is a circle having a diameter of 30 mm, the dark portions 126D are arranged at a pitch of 57 mm on each latitude line. Further, between the dark portions 126D on the adjacent latitude lines, the centers of the dark portions 126 are not on the same meridian, but are shifted by 28.5 mm in the latitude direction. In addition to the example of FIG. 13, at any position in the dark region of the observation surface, in order to secure light reflected by the bright portion of the reflector and obliquely incident, a space between adjacent dark portions separated by the bright portion is secured. Requires some distance.

  In the example of FIG. 13, when the reflector 12D is actually rotated by 180 degrees around the y-axis, the shadow of the dark portion passes through the entire surface of the test object once. For example, in the case where the dark portion is shifted in the latitude direction along only two opposing latitude lines on the concave surface of the reflector 12D, in order to pass the shadow of the dark portion once over the entire surface of the test object. Needs to rotate the reflector 12D 360 degrees around the y-axis. That is, the inspection time can be shortened by arranging a large number of dark portions so as not to be overcrowded.

  Further, the dark part and the light part in each of the above-mentioned reflectors may be exchanged. The reflector in which the dark part and the bright part are exchanged will be described using a specific example. FIG. 14 shows a reflector in which the dark part and the bright part in the example of FIG. 13 are interchanged. In the example of FIG. 13, in the concave surface of the reflector 12D, the dark portion 126D is a plurality of regions having a circular contour, and the bright portion 124D is located outside the circular contour of the dark portion 126D. On the other hand, in the example of FIG. 14, in the concave surface of the reflector 12E, the bright portion 124E is a plurality of regions having a circular contour, and the dark portion 126E is located in a region outside the circular contour of the bright portion 124E. is there. The reflector 12E having the larger dark portion 126E is suitable for an inspection for detecting a deeper flaw as compared with the reflector 12D.

  As described above, various types of reflectors having different shapes, sizes, and arrangements of the dark portion and the bright portion may be appropriately used depending on the shape of the test object, the nature of the defect to be detected, and the like.

  Although the reflectors exemplified so far have different areas between the dark part and the bright part, the dark part and the bright part may have the same area.

[Other Modifications]
As described above, the appearance inspection system according to one or more aspects of the present invention has been described based on the embodiment, but the present invention is not limited to this embodiment. Unless departing from the gist of the present invention, various other modifications conceived by those skilled in the art may be applied to the above-described embodiment, and a form constructed by combining the configurations of the embodiment and each of the modifications may be implemented by the present invention. May be included in one or more embodiments.

  Further, the following modifications are also included in one or more aspects of the present invention.

  For example, the present invention can be implemented not only as a visual inspection system but also as a visual inspection device for acquiring an inspection image. Further, the present invention can also be implemented as a visual inspection device not including a camera, and can be used, for example, by visual inspection by an inspector or in combination with an external camera.

  Further, the light source unit is not limited to the surface illumination, and may be any light source that can illuminate the entire concave surface of the reflector substantially uniformly.

  When the reflector is a transparent body, the position where the film or the like for providing the dark portion or the bright portion is attached is not limited to the concave side of the dome-shaped reflector, and may be the convex side. Further, the dark portion or the bright portion is not fixed to the concave surface of the reflector, but may be realized by a plate-shaped member provided on or near the concave surface.

  What is attached to the concave surface of the reflector to give desired optical characteristics is not limited to the above-mentioned film. For example, metal such as paper, cloth, or foil may be attached.

  Further, the rotating mechanism only needs to be able to change the relative posture of the test object with respect to the dark part, and may rotate, for example, the holding stand or both the holding stand and the dark part. The rotation of the dark part may be the rotation of the reflector to which the dark part is fixed, or the rotation of the plate-like member that realizes the dark part or the bright part as described above. Further, a function of changing the relative posture of the test object with respect to the dark portion may be provided by further tilting the rotation mechanism that supports the holding table or the reflector. As a result, the position of the observation surface and the transmission portion as described above, that is, the positional relationship between the observation surface and the observation position changes, and a portion of the observation surface having a complicated shape, which is parallel or nearly parallel to the optical axis of the camera. Can be easily performed without, for example, once removing the dome and tilting the test object.

  The material of the reflector 12 is not limited to the transparent resin described above, but may be a resin that does not transmit light, a metal or paper molded into a dome shape, and the concave surface is processed to give optical characteristics as necessary. It may be something. Further, the transmission portion may be a hole penetrating the dome, or a transparent member such as resin, glass, or cellophane attached to close the hole.

  In addition, a part of the reflector may be a half mirror, and the transmissive part and the bright part may overlap each other in the area of the half mirror. In this case, the area of the half mirror reflects the light incident on the concave surface, and the camera or the inspector may capture the light transmitted through the area to obtain an image of the test object. In the appearance inspection apparatus including the reflector including the half mirror, the degree of freedom of the observation position can be obtained as long as a dark portion can be prevented from entering the optical path of the camera. For example, a wider range of a test object having a complicated shape can be inspected by changing the position of the camera without tilting the holding mechanism or the rotating mechanism supporting the reflector as described above.

  In addition, regardless of whether the reflector is a half mirror or not, the boundary between the transmitting portion and the bright portion may not be clear as shown in each drawing of the present application.

  The dark portion of the reflector may be transparent or a through hole of the reflector, and may be provided by darkening a space on the convex surface side of the reflector. In this case, it is desirable that the appearance inspection device be configured so that light from the light source unit does not leak to the space on the convex surface side of the reflector as much as possible from below the transmission unit or the reflector.

  Further, in the image analysis by the image processing device, a process of detecting a defect based on a brighter portion in a range where a dark region appears in the image, and a process of detecting a defect based on a darker portion within a range where a bright region appears in the image Only one of the processes may be performed, or both may be performed.

  Further, the dark area and the bright area in the above description are recognized using a predetermined threshold regarding luminance in the image processing, but the third area of intermediate luminance located between the dark area and the bright area May also be used. In this case, the defect detection is performed based on a darker portion or a brighter portion in the third area.

  Further, the darker portion or the brighter portion in the image used for detecting a defect as described above is not limited to a portion which is displayed in a continuous pixel. For example, even if the image is a minute scratch or a stain and is not included in the image alone and is not determined as a defect, the image may be included in a target detected as a defect based on the number and arrangement of the images. As a specific example, a product in which a plurality of minute flaws are densely formed or a product in which a plurality of fine flaws are arranged in a line having a certain length or more with a short interval therebetween are easily recognized by humans and relate to the quality of the product. Individual images of such flaws are non-continuous on the image, but may be recognized as defects based on their spacing, or extents that extend or extend.

  Further, the image on which the image integration unit superimposes the defect image is not limited to the image in which the dark area and the bright area are shown as shown in FIG. 9A. For example, the image of the test object may be an image of the test object taken under a reflector having a uniform concave reflectance, or may be an image of the test object taken without a reflector. . Alternatively, a processed image of the test object photographed with the reflector placed, for example, an image of the test object that does not include a dark area, obtained by integrating bright areas extracted from a plurality of images. Good.

  Further, the image integration processing by the image integration unit is not essential. For example, the image analysis unit performs processing for adding information (coloring, enclosing, arrow, etc.) indicating the position of the defect to the image itself in which the defect has been detected by the analysis, and outputs the processed image data to the output unit. May be output. The output is not limited to image data. For example, the data may include a number specifying a defect, coordinates indicating the position of the defect or its outline in the image, and the like. When a plurality of types of defects can be detected, the manner of presentation may be changed for each type of defect.

  Further, the camera and the image processing device are not individual devices such as the camera 15 and the image processing device 20 shown in FIG. 2, but are a camera, an arithmetic processing device, a storage device, and the like such as a notebook computer, a tablet computer, and a smartphone. May be realized by a single general-purpose device or a dedicated device.

  Further, a device that realizes the image processing apparatus may execute a predetermined program to control the operation of the rotation mechanism, the light source unit, or the camera. That is, the image processing apparatus controls the entire appearance inspection system, and may be an interface for the user.

  Further, although the embodiment has been described using an example of a test object whose surface is a mirror surface or close to a mirror surface, a test object that can be subjected to a visual inspection using the visual inspection system or the visual inspection device according to the present invention is not limited thereto. Not limited. For example, it can also be used for the appearance inspection of a test object on which a hairline or satin finish has been subjected to surface treatment.

[Effect of the present invention]
According to the appearance inspection system or the appearance inspection apparatus of the present invention, even for a test object having a complicated surface angle, a wide range can be quickly inspected for spots and color unevenness, and conventionally, the same defect as these defects is detected. Scratches on a mirror surface or a surface close to a mirror surface, which were difficult to detect by inspection, can be detected with high accuracy.

  INDUSTRIAL APPLICABILITY The present invention can be used as an apparatus or a system for visual inspection of an article.

Reference Signs List 1 appearance inspection system 10 appearance inspection device 11 holding table 12, 12A, 12B, 12C, 12D, 12E reflector 13 light source unit 14 rotation mechanism 15 camera 20 image processing device 122, 122A, 122B, 122C, 122D, 122E transmission unit 124 , 124A, 124B, 124C, 124D, 124E Light section 126, 126A, 126B, 126C, 126D, 126E Dark section 151 Imaging section 152 Communication section 201 CPU
202 input unit 203 main storage device 204 image analysis unit 205 auxiliary storage device 206 image integration unit 207 display 208 output unit 209 input I / F
211 Communication I / F

Claims (10)

An appearance inspection device that inspects the appearance of the test object by a reflected light image formed by light reflected by the test object,
A holding table for holding the test object,
A dome-shaped reflector that is located on the observation surface side of the test object and has a concave surface facing the observation surface,
A light source unit that is located on the opposite side of the observation surface of the test object and emits light that illuminates the concave surface with substantially uniform illuminance,
With a rotation mechanism,
The reflector is a transmitting portion that transmits the incident light that is emitted from the light source portion and reaches the concave surface, a bright portion that reflects the incident light and falls on the surface to be observed, and more reflective than the bright portion. Having a dark area that creates a shadow on the surface to be observed with a low rate,
The rotation mechanism changes at least one of the holding table and the dark portion to change a relative posture of the test object with respect to the dark portion, thereby forming at least a part of the observation surface by the dark portion. Performing a rotating operation to switch between a dark state with a shadow and a bright state without the shadow,
Appearance inspection device. The rotation mechanism switches the observation surface between the dark state and the bright state at least once on the entire surface by changing a relative posture of the test object with respect to the dark part.
The visual inspection device according to claim 1. A part of the reflector is a half mirror, and the transmission part and the bright part overlap in a region of the half mirror;
The appearance inspection device according to claim 1. In the reflector, the transmitting portion is transparent or a through hole of the reflector, and the bright portion is a white surface or a mirror surface,
The appearance inspection device according to claim 1. One of the bright portion and the dark portion is a region having a circular contour on the concave surface, and the other is in a region outside the contour.
The visual inspection device according to claim 1. One of the bright part and the dark part is a contour that intersects at a plurality of locations with one latitude line assumed for the reflector on the concave surface, and the intersection angles of the latitude lines at the multiple locations are different from each other. A region having a contour, the other being in a region outside the contour,
The visual inspection device according to claim 1. One of the bright portion and the dark portion is a plurality of regions separated by the other in the concave surface,
An appearance inspection apparatus according to claim 5. Furthermore, an imaging unit that receives the incident light that has been reflected by the concave surface and once falls on the surface to be observed and that has been reflected by the surface to be observed and then transmitted through the transmission unit to capture an image of the surface to be observed. Comprising,
The appearance inspection device according to claim 1. An appearance inspection device according to claim 8,
With an image processing device,
The image processing device,
An input unit that receives input of a plurality of images of the observation surface photographed by the photographing unit, of the test object having different relative postures caused by the rotation mechanism changing by performing the rotation operation,
An image analysis unit that analyzes the plurality of input images and detects a defect of the observed surface,
An output unit that outputs data of information indicating the detected defect,
Visual inspection system. The image analysis unit detects the defect based on a brighter portion in a range where the dark region is reflected in the image or a darker portion in a range where the bright region is reflected in the image.
The visual inspection system according to claim 9.