JP6482710B1 - Appearance inspection apparatus and inspection system - Google Patents

Abstract

A visual inspection apparatus capable of quickly and accurately detecting wrinkles on the surface of a test object.
An appearance inspection apparatus 10 includes a holding table 11 on which a test object is placed, a dome-shaped reflector 12 having a concave surface facing the observation surface side of the test object, and a test object. A light source unit 13 that emits light that illuminates the concave surface with substantially uniform illuminance, and a rotation mechanism 14 are provided on the opposite side of the surface to be observed. The reflector 12 includes a transmission part 122 that transmits incident light that is emitted from the light source part 13 and reaches the concave surface, a bright part 124 that reflects incident light and falls on the surface to be observed, and a reflectance higher than that of the bright part 124. And a dark portion 126 that makes a shadow on the surface to be observed. The rotation mechanism 14 changes the relative posture of the test object with respect to the dark part 126 by rotating at least one of the holding table 11 and the dark part 126, so that the shadow created by the dark part 126 forms at least a part of the observation surface. A rotation operation is performed to switch between a certain dark state and a bright state without a shadow.
[Selection] Figure 1

Description

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

  A test object having a smooth surface reflects the illumination light irradiated from one direction only in one direction without diffuse reflection. Therefore, in the appearance inspection of the surface of the object to be inspected, 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 in the direction of the position where the eye or camera lens is 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, the entire surface does not appear to have uniform brightness. If the surface brightness is not uniform, the reflection of the light source becomes an extreme highlight, and the range in which the reflected illumination light does not come into the eye becomes dark and difficult to see. Such an appearance significantly reduces the accuracy of the appearance inspection. Such appearance inspection of the test object can be appropriately executed by observing the entire surface while changing the positional relationship between the light source, the test object, and the observation position. However, such a method requires a certain length of inspection time, or if the inspector is manually involved in the inspection process, the inspector's skill is required to minimize the inspection time and ensure accuracy. Is required.

  For example, the dome-shaped luminaire found in Non-Patent Document 1 irradiates the test object from all directions except the top to suppress the occurrence of highlights and minimize the occurrence of shadows at a time. Enables observation of a wide range of the observation surface.

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

  As a result, for example, a three-dimensional test object having a curved surface on the surface to be observed, such as a lens, does not cause highlights or shadows, and the entire surface to be observed is included with almost uniform brightness. It is possible to observe at a glance.

JP, 2006-128771, A

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

  In the case of an apparatus according to the prior art, if there is a flaw such as a stain, uneven color, or adhesion of foreign matter on the surface of the test object, the difference in appearance due to the difference in reflectance or color tone between the wrinkle and other parts. Based on this, this wrinkle can be detected with high accuracy. However, in the case of irregularities such as scratches on the surface, that is, there is a change in shape, but there is almost no difference in reflectance or color tone from other parts, shadows are less likely to occur by falling illumination light from multiple directions Moreover, since it looks the same as other parts, there is a problem that it is difficult to detect with high accuracy by the apparatus according to the prior art.

  The present invention provides an apparatus and the like capable of quickly and accurately performing an appearance inspection for detecting wrinkles with small changes in color or reflectance, such as scratches on the surface of an object.

  An appearance inspection apparatus according to one aspect of the present invention provided to solve the above-described problem is an appearance inspection apparatus that inspects the appearance of a test object using a reflected light image formed by light reflected by the test object. A holding table for holding the test object, a dome-shaped reflector located 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 emits light that illuminates the concave surface with a substantially uniform illuminance, and a rotation mechanism, which is located on the opposite side of the observation surface, and a rotating mechanism, the reflector emits the light source unit and reaches the concave surface A transmissive portion that transmits the incident light, a bright portion that reflects the incident light and is incident on the surface to be observed, and a dark portion that has a lower reflectance than the bright portion and creates a shadow on the surface to be observed. The rotating mechanism rotates the at least one of the holding table and the dark part to the dark part. 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.

  In addition, the visual inspection system according to an aspect of the present invention further receives the incident light that is reflected by the concave surface and once falls on the surface to be observed, is reflected by the surface to be observed, and passes through the transmission unit. And an image inspection device including an imaging unit that captures an image of the surface to be observed, and the image processing device differs depending on whether the rotation mechanism is changed by performing the rotation operation. An input unit that receives input of a plurality of images of the observation surface captured by the imaging unit of the test object in a relative posture, and a plurality of the input images are analyzed, An image analysis unit that detects wrinkles and an output unit that outputs data of information indicating the detected wrinkles.

  Note that these comprehensive or specific modes may be realized by a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM on which the computer program is recorded. The present invention may be realized by any combination of a method, an integrated circuit, a computer program, and a recording medium.

  With the appearance inspection and the appearance inspection system according to the present invention, it is possible to quickly and accurately detect wrinkles with small changes in color or reflectance, such as scratches on the surface of the test object.

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

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

  Note that the following embodiments show a comprehensive or specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component arrangement and connection forms, steps (steps) and order of steps, and the like shown in the following embodiments are examples and limit the present invention. is not. Among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims can be arbitrarily added. Each figure is a mimetic diagram and is not necessarily illustrated strictly.

(Embodiment)
The appearance inspection system in the present embodiment is used for inspection by dark field observation (hereinafter, also referred to as epi-illumination type dark field inspection) performed while reflecting illumination light from multiple directions over the entire surface to be observed of the object to be inspected. It is done. Hereinafter, the appearance inspection system 1 in the present embodiment will be described.

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

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

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

  The reflector 12 is a dome-shaped object that is located on the side to be observed of the test object, in the illustrated example, and has a concave surface that faces the surface to be observed of the test object, and reflects the light emitted from the light source unit 13. Reflect and reflect on the surface to be observed. In addition, the reflector 12 includes a transmission part 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. Moreover, in the part other than the transmission part 122 of the reflector 12, the optical characteristic which reflects the incident light to the concave surface with different reflectance depending on the location is given 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 on the convex surface shown in FIG. 3A. The bright part 124 reflects incident light and makes it fall on the observation surface of the test object. Further, the dark portion 126 has a lower reflectance than the bright portion 124, and creates a shadow on the observation surface of the test object. Hereinafter, the region of the surface to be observed having a shadow created by the dark portion 126 is referred to as a dark region, and the state of the dark region having the shadow is also referred to as a dark state. Further, the area of the observed surface that is not shadowed by the dark portion 126 is referred to as a bright area, and the bright area without the 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 surface to be observed of the test object and faces the concave surface of the reflector 12, and is used to illuminate the concave surface with a substantially uniform illuminance. Diffuse light is emitted. The arrows in FIG. 1 schematically show how the light emitted from the light source unit 13 travels in the 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 on the holding base 11 from multiple directions.
The rotation mechanism 14 includes a motor and a roller connected to the motor shaft. The roller is in contact with the reflector 12, and the reflector 12 is rotated by rotating the roller by operating the motor.

  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 indicate the optical axis of the optical system of the camera 15.

  The appearance inspection apparatus 10 includes the above-described holding base 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 reflector 12 and various wirings for transmitting drive power, control signals, imaging data, and the like are omitted. As shown in FIG. 3A, the reflector 12 is provided with a ridge at its edge, and the ridge is placed so as to be supported by three rollers. When the roller rotates, the reflector 12 rotates around the y axis. The axis of rotation substantially coincides with the optical axis of the camera 15. The camera 15 receives and captures the reflected light of the test object that is transmitted through the transmitting portion 122 of the reflector 12 placed in this manner and received by an image sensor (not shown). The image sensor constitutes a photographing unit in the present embodiment.

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

[Structure 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 part 124 is an area that reflects the incident light emitted from the light source part 13 and reaches the concave surface of the reflector 12 to be reflected on the observation surface of the test object held on the holding table 11. . The bright portion 124 is, for example, white (including approximate colors such as grayish white and milky white), silver, or a mirror surface due to the material of the reflector 12 or the coating agent or film that covers the concave surface thereof. Note that the color and reflectance of the bright portion 124 may be any one that can be used in combination with the dark portion 126 so that the contrast of light and dark on the surface to be observed can be obtained with the intensity required for the inspection described later. The color or reflectance of the surface of the light source, the intensity or color temperature of the light emitted from the light source unit 13, or the necessity or convenience in the image processing in the subsequent process may be changed.

  The dark part 126 is an area for making a shadow on the surface to be observed, and is an area having a lower reflectance than the bright part 124. The dark portion 126 has a dark color such as black or brown that absorbs almost all or most of incident light due to the material of the reflector 12 or the coating agent or film covering the concave surface thereof. Note that the color and reflectance of the dark portion 126 may be any one that can be used in combination with the bright portion 124 so that the contrast of light and dark on the surface to be observed can be obtained with the intensity required for an inspection described later. However, in the drawings after FIG. 3B, the dark portion is shown as a shaded region, but the shaded density does not limit the color or reflectance of the dark portion or the difference between these dark portions.

  When the reflector 12 rotates, the relative posture of the test object with respect to the dark part 126 changes, and the dark region 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 through every part of the surface to be observed at least once while the reflector 12 goes around by the rotating mechanism 14. Pre-adjusted. In other words, while the reflector 12 makes a round by the rotation mechanism 14, it becomes a bright region and a dark region at least once over the entire surface to be observed, or at least once in a dark state and a bright state. Switch.

  In the example illustrated in FIG. 3B, the plurality of dark portions 126 having a circular outline are arranged in a spiral shape from the position near the center of the concave surface to the edge. The size and interval of these dark portions 126 (also the shape and size of the bright portion 124) are assumed to be meridians on the concave surface, and the meridians at any position other than the transmissive portion 122 can be the bright portions 124 and dark portions. Each of 126 is adjusted so as to overlap at one or more places. Thereby, the shadow of the dark part 126 passes through every part of the surface to be observed at least once while the reflector 12 goes around.

  Next, with the appearance inspection apparatus 10 configured as described above, wrinkles due to a change (unevenness) in the shape of the surface of the test object, which was difficult to detect in the appearance inspection using the conventional technique, are detected with higher accuracy. The principle for realizing the inspection will be described.

[Principle underlying inspection]
4A, 4B, 5A, and 5B are schematic diagrams for explaining the principle of appearance inspection using the appearance inspection apparatus 10. FIG. More specifically, FIG. 4A shows a state in which the specular surface of the test object is uneven, and FIG. 4B shows a state in which a part of the specular surface of the test object is uneven. 5A shows a part of the situation of FIG. 4A, and FIG. 5B shows an enlarged and emphasized part of the situation of FIG. 4B for convenience of explanation. In these drawings, only one dark portion 126 is shown for illustration.

  In this example, when a dark region on the surface of the test object is captured in the image taken by the camera 15, the angle formed by the dark portion 126-dark region-camera that causes the dark region is the object in which the dark region exists. It is divided into two equal parts by the normal line of the surface of the inspection object (the chain line in the figure). That is, the incident angle (in the figure, the angle formed by the solid line arrow starting from the dark portion 126 and the normal line) 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, since the light reflected from the dark portion 126, that is, the bright portion 124 and reflected on the surface of the test object also follows the law of reflection, 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 incident on the dark region viewed from the position of the camera 15 (in the figure, a dotted arrow starting from the outside of the dark part 126) It does not enter the optical system (in the figure, a dotted arrow starting from the surface of the test object). 5A, the incident light to the test object indicated by the arrow A and the reflected light indicated by the arrow rA, the incident light indicated by the arrow B and the reflected light indicated by the arrow rB, and the arrow C are indicated. Incident light and arrow rC illustrate light traveling in this way.

  Thus, in the test object having a specular surface, the dark region caused by the dark portion 126 reflects the color of the dark portion 126 entirely.

  On the other hand, for example, 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, the light reflected outside the dark portion 126, that is, in the dark region viewed from the position of the camera 15 reflected by the bright portion 124 also enters the optical system of the camera 15. FIG. 5B illustrates light traveling in this way. There are fine irregularities in the dark region caused by the dark portion 126. The light reflected outside the dark portion 126 and falling into the dark region can enter the optical system of the camera 15 as shown in FIG. 5B when reflected on the surface of the test object at the falling position according to the law of reflection. In FIG. 5B, the incident light to the test object indicated by the arrow C and the reflected light indicated by the arrow rC illustrate the light traveling in this way. Note that an arrow C in FIG. 5A and an arrow C in FIG. 5B indicate incident light from the same position of the reflector 12. Actually, the unevenness of the surface of the test object has a more complicated shape, and the incident light on the unevenness is scattered. And the light which advanced in this way is observed as a brighter part reflecting the uneven | corrugated shape in a dark area | region.

  FIG. 6 is an example of an image of a test object (part) by the appearance inspection apparatus 10. In FIG. 6, a brighter line extending to the left and right within the oval dark region indicated by a white arrow indicates a scratch on the surface of the test object. The difference in visibility is noticeable when comparing the part in the dark area with the part in the bright area near the right end.

  In the appearance inspection apparatus 10, by changing the relative posture of the test object with respect to the dark part 126, such a dark state is made once in every part of the observation surface of the test object. And the image of the to-be-observed surface in a dark state with the camera 15 is acquired. The image processing apparatus 20 that has acquired the image acquired in this way from the camera 15 detects a scratch on the surface of the test object based on, for example, a luminance difference from the periphery of each pixel.

  Note that when the transmissive part 122 is seen from the observation position on the surface to be observed, a dark region by the dark part 126 cannot be formed. Therefore, for example, the test object is inspected by tilting the test object and changing the relative posture of the test object with respect to the dark portion 126. Even when the surface to be observed includes a part parallel or substantially parallel to the optical axis of the camera 15, the camera 15 cannot capture an image of the part. Therefore, also in this case, for example, the test object is tilted and the relative posture of the test object with respect to the dark portion 126 is changed, and further imaging is performed for inspection.

  In addition, the law of reflection is valid throughout the specular surface. In the bright region, light that should enter the optical system of the camera 15 does not enter the optical system due to the unevenness unless there is unevenness on the surface of the test object. A method of detecting scratches can also be taken.

[Configuration of camera and image processing apparatus]
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 a hardware configuration example of the image processing apparatus 20.

  As illustrated 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 the light reflected by the surface to be observed and then transmitted through the transmission unit 122, and images the image of the surface to be observed. The optical system includes one or more lenses and forms an image suitable for inspection of the surface to be observed on the image sensor. The image sensor converts the received light into an electrical signal and outputs it. Image data based on the electrical signal is transmitted to the image processing apparatus 20 by the communication unit 152.

  The image processing apparatus 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 input of image data of a plurality of images of the observation surface of the test object from the camera 15. These images include images taken when the relative posture of the test object with respect to the dark portion 126 is different.

  The image analysis unit 204 analyzes image data of a plurality of images received by the input unit 202 and detects wrinkles on the surface to be observed. Here, the wrinkles are scratches on the surface of the test object that are detected based on the luminance difference, for example, as described above. In addition, wrinkles that can be detected in a bright region may include spots, uneven color, or foreign matter adhesion. Note that a scratch having a size or depth of a certain degree or more may be detectable even in a bright region. In analysis of an image for detection of wrinkles, the image analysis unit 204, for example, performs segmentation (division into small areas), calculation of differences based on pixels or pixel values between small areas, edge detection, and detection within a predetermined range. Threshold processing is performed on the size (area, length, or number of pixels) of continuous pixels having pixel values, or various numerical values.

  The image integration unit 206 generates one image indicating the wrinkles of the test object detected by the above analysis, and superimposes and integrates the image on the test object.

  The output unit 208 outputs data of information indicating the detected wrinkles. The output here is, for example, 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 the user. Also, for example, it is an output of inspection result data for accumulation in a storage device inside or outside the appearance inspection apparatus 10. Also, for example, 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 appearance inspection apparatus 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 holds a predetermined program for realizing the control program and the above-described components of the image processing device 20.

  The display 207 is a display device that displays video including images. 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 accepting input from the 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 that communicates with the camera 15 via a communication network. The communication I / F 211 may be a wired communication interface or a wireless communication interface.

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

  The operation for appearance inspection by the appearance inspection system 1 is performed by placing the object to be examined on the holding table 11 with the surface to be observed facing the camera 15 and placing the reflector 12 on the rotating mechanism 14 in a proper posture. Then start.

  When the light source unit 13 emits diffused light toward the concave surface of the reflector 12, the camera 15 covers the reflector 12 (transmission unit 122) each time the rotating mechanism 14 rotates the reflector 12 by a certain amount. Take an image of the inspection. The amount of rotation once is determined in advance based on the size of the dark portion 126 or the bright portion 124 of the reflector 12. The rotation and photographing are continued until the dark state and the bright state are switched once over the entire surface to be observed. During this imaging, the relative position and posture of the subject and the camera 15 do not change, and the relative position and posture of the subject and the camera 15, the dark portion 126, and the bright portion 124 change. Therefore, the plurality of images taken in this way are all images of the same spatial region, and the position and posture of the test object in the image are constant, and the dark portion 126 shown in the test object There is a difference in the shadow, that is, the position, size and shape of the dark region.

  In the image processing apparatus 20, the input unit 202 receives input of data of these multiple images. FIG. 9A is a schematic diagram for explaining an image of an object photographed by the camera 15 when the input unit 202 receives data. In this image, the observation surface of the test object is shown against the top surface of the holding table 11. The shaded portion of the surface to be observed 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-shaped frame member in plan view, and has a cross-sectional shape of a medium 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 is circular as shown in FIG. 3B, the dark region exhibits various shapes different from the circular shape when viewed from the observation position.

  The image analysis unit 204 analyzes this data and detects wrinkles on the observed surface appearing in each image. FIG. 9B is a schematic diagram for explaining an image including wrinkles detected by the image analysis unit 204. The image analysis unit 204 performs the processing exemplified above to detect wrinkles, and identifies pixels in which the detected wrinkles are captured. For example, the image analysis unit 204 extracts a brighter portion (pixel) in the dark region or a darker portion (pixel) in the bright region by threshold processing, and further, the size of such a continuous collection of pixels. Based on (area, length, or number of pixels), it is determined whether or not the pixel has a wrinkle. Thereafter, the image analysis unit 204 generates data of one image in which the pixels in which the wrinkles identified in each image are reflected are changed to a predetermined color. FIG. 9B is an example of an image indicated by this data. In FIG. 9B, the pixels with the detected wrinkles are represented as black portions scattered in the image indicated by the frame.

  The image integration unit 206 superimposes the wrinkle 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 way. The image shown in FIG. 9C is generated by superimposing the wrinkle image in the image shown in FIG. 9B on the image shown in FIG. 9A.

  The image data generated by the image integration unit 206 is output from the output unit 208, and is displayed on a screen or printed on paper, for example, and 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 appearance inspection apparatus 10 should include in order to detect wrinkles as described above. Various modifications are possible as long as the concave surface of the reflector that should be included in the appearance inspection apparatus 10 includes a bright portion and a dark portion, which are two types of regions having different reflectivities. Hereinafter, the modification will be described.

  First, the dark part illustrated in FIG. 3B is an example of a shape suitable for detecting scratches in various directions. Scratches in the dark region are easy to detect when the incident light hits at right angles to the extending direction of the scratch, and are difficult to detect when the light hits in parallel. Since light enters the dark area formed by the dark part illustrated in FIG. 3B from all the surrounding directions, the possibility of detecting scratches is increased and the accuracy of the inspection is improved.

  The shape of the dark part is not limited to a circle, and may be a polygon such as a rectangle. However, in the inspection by the appearance inspection apparatus 10, the presence / absence of a flaw in the dark region is determined based on whether or not the light incident on the dark region from the oblique direction is irregularly reflected. That is, the light incident on the dark region from the oblique direction is inspection light in the incident-type dark field inspection, and it is desirable that the light is incident on the same dark region from all directions under the same conditions as much as possible. In this respect, the shape of the dark part is most preferably a circle, but even a polygon such as a rectangle can obtain an effect close to a circular dark part.

  Examples of other dark part shapes suitable for detecting scratches are shown in FIGS.

  In the example shown in FIG. 10, the two dark portions 126A extending between the periphery of the transmissive portion 122A of the reflector 12A and the end of the reflector 12A have the latitude 10 assuming that the reflector 12A is a hemisphere. Every 45 degrees, 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 outline of the dark portion 126B of the reflector 12B has a trapezoidal wave shape in which +45 degree portions and −45 degree portions appear alternately with respect to the meridian (or latitude line) on the concave surface. Further, the concave line of the reflector 12B, which is at any position outside the range of the transmissive part 122A or 122B, is lined up and down in the figure so that it intersects both the +45 degree portion and the −45 degree portion of the outline. The period in the meridian direction of the contour is shifted between the dark portions 126B. Like these, even in dark areas where the contour intersects with the latitude line of the same latitude at multiple places and the dark area where the crossing angle differs depending on the location of the intersection, the incident light condition is unfavorable for detecting scratches on the surface of the test object There are few directions to become.

  In addition, the shape of the dark part shown using the angle (10 degree | times, +45 degree | times, -45 degree | times) included in the said description about FIG.10 and FIG.11 is an example, and the shape of the dark part which a reflector has is limited to these. Not. For example, as a modification of the dark part as shown in FIG. 10, the contour may be denser and bend in small increments, or may be a continuous curve. The shape of the dark part shown in FIG. 10 and FIG. 11 is the direction in which a plurality of boundaries between the dark part and the bright part run through one arbitrary point of the test object due to the rotation of the reflector (normal line of the concave surface of the reflector). This is an example of enabling detection with higher accuracy while suppressing the influence of the direction in which the scratches including the point run due to variations in the angle (viewed in the direction). That is, by using a reflector having a dark part having such a shape, the same effect can be obtained without being limited to the examples shown in FIGS.

  Further, the size of the dark part is appropriately determined according to the depth of the scratch to be detected and the size, height, and degree of change of the curved surface of the entire test object. For example, when the scratch is shallow, that is, when the angle at which the scratch enters the surface of the test object is small, the change width of the reflection angle is small. Therefore, it is easier to detect scratches when the incident angle of light incident on the surface of the object from the bright part is reduced. However, if the dark part is small, the dark region becomes thin (bright). However, depending on the darkness of the dark region, the contrast with the bright part is low due to irregular reflection due to the scratch, and it is difficult to detect the scratch. Therefore, in order to maintain accuracy, the dark portion needs to have a certain size. Further, when the test object is large, it is easier to detect scratches in the larger dark part. Further, when the change in the curved surface of the surface of the test object is large, the dark region on the observation surface is greatly distorted. Therefore, the size of the dark portion is determined so that the dark region resulting from the distortion has a size suitable for the scratch to be detected.

  Further, the arrangement of the dark part is adjusted in advance so that the shadow of the dark part passes through every part of the surface to be observed at least once while the reflector goes around as described above. Although FIG. 3B shows an example adjusted in this way, fewer dark areas may be used. 12 and 13 are arrangement examples of fewer dark portions on the concave surface of the reflector.

  In the example of FIG. 12, a circular dark portion 126C is arranged only in a substantially half region of the reflector 12C. However, if the reflector 12C makes a round around the y-axis, the shadow of the dark part passes through at least one portion of the observation surface of the test object held by the holding base 11 and surrounded by the reflector 12C. The position of the dark portion on the concave surface in the latitude direction is adjusted in advance. In such an arrangement, it is easy to detect wrinkles such as spots and color unevenness by using the upper half area of the figure without dark portions.

  In the example of FIG. 13, circular dark portions 126D are arranged along the four parallels 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 portion passes at least once through every portion of the observation surface of the test object held by the holding base 11 and surrounded by the reflector 12C. Thus, the position of the dark portion on the concave surface in the latitude direction is adjusted in advance. For example, when each dark portion 126D is a circle with a diameter of 30 mm, it is arranged at a pitch of 57 mm on each latitude line. Further, in 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. It should be noted that the present invention is not limited to the example of FIG. 13, and at any position in the dark region of the observation surface, in order to secure light that is reflected by the bright portion of the reflector and is incident obliquely, between the adjacent dark portions separated by the bright portion. Requires a certain distance.

  In the example of FIG. 13, in practice, if the reflector 12D is rotated 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 part is arranged by shifting the position in the latitudinal direction along only two parallels facing each other on the concave surface of the reflector 12D, in order to pass the shadow of the dark part once over the entire surface of the test object Needs to rotate the reflector 12D 360 degrees around the y-axis. In other words, the inspection time can be shortened by arranging a large number of dark portions so as not to be overcrowded.

  Moreover, you may replace the dark part and the bright part in each above-mentioned reflector. A 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 in a region outside the circular contour of the dark portion 126D. On the other hand, in the example of FIG. 14, on the concave surface of the reflector 12E, the bright part 124E is a plurality of areas having a circular outline, and the dark part 126E is located in an area outside the circular outline of the bright part 124E. is there. The reflector 12E having a larger dark portion 126E is suitable for inspection in which a deeper scratch is detected as compared with the reflector 12D.

  As described above, various reflectors having different shapes, sizes, and arrangements of the dark part and the bright part may be appropriately used depending on the shape of the test object or the properties of the eyelid to be detected.

  In addition, although all the reflectors illustrated so far have a difference in area between the dark part and the bright part, the dark part and the bright part may have the same area.

[Other variations]
As described above, the appearance inspection system according to one or more aspects of the present invention has been described based on the embodiment. However, the present invention is not limited to this embodiment. Without departing from the spirit of the present invention, other various modifications conceived by those skilled in the art are applied to the above-described embodiments, and the embodiments constructed by combining the configurations of the embodiments and the modifications are also included in the present invention. It may be included in one or a plurality of embodiments.

  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 an appearance inspection system but also as an appearance inspection apparatus for acquiring an inspection image. Further, it can be implemented as an appearance inspection apparatus that does not include 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 surface illumination, and it is sufficient that the entire concave surface of the reflector can be illuminated substantially uniformly.

  Moreover, when a reflector is a transparent body, the sticking position of the film etc. for providing a dark part or a bright part is not limited to the concave surface side of the reflector which is dome shape, The convex surface side may be sufficient. Further, the dark part or the bright part is not fixed to the concave surface of the reflector, but may be realized by a plate-like member provided on or near the concave surface.

  Moreover, what is affixed in order to give a desired optical characteristic to the concave surface of a reflector is not limited to said film. For example, paper, cloth, foil-like metal, or the like may be attached.

  Moreover, the rotation mechanism should just change the relative attitude | position of the test object with respect to a dark part, for example, may rotate both a holding stand or a holding stand and a dark part. The rotation of the dark part may be the rotation of the reflector to which the dark part is fixed, or may be the rotation of a plate-like member that realizes the dark part or the bright part as described above. In addition, the rotation mechanism that supports the holding table or the reflector may be further inclined to provide a function of changing the relative posture of the test object with respect to the dark part. As a result, the positional relationship between the surface to be observed and the transmission portion, that is, the surface to be observed and the observation position as described above also changes, and a portion of the observation surface having a complicated shape that is parallel or nearly parallel to the optical axis of the camera This inspection can be easily performed without removing the dome once and tilting the test object, for example.

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

  Moreover, a part of the reflector may be a half mirror, and the transmission part and the bright part may overlap in the area of the half mirror. In this case, the region of the half mirror may reflect the light incident on the concave surface, and the camera or the inspector may acquire the image of the test object by capturing the light transmitted through the region. In an appearance inspection apparatus including such a reflector made of a half mirror, the degree of freedom of the observation position can be obtained as long as a dark part can be prevented from entering the optical path of the camera. For example, as described above, it is possible to inspect a wider range of the object having a complicated shape by changing the position of the camera without tilting the rotation mechanism that supports the holding table or the reflector.

  Regardless of whether the reflector is a half mirror, the boundary between the transmissive portion and the bright portion may not be clear as shown in the drawings of the present application.

  Moreover, the dark part of a reflector is transparent or it is a through-hole of a reflector, Comprising: You may be provided by darkening the space by the side of the convex surface of a reflector. In this case, it is desirable that the appearance inspection apparatus is configured so that light originating from the light source unit does not leak into the space on the convex surface side of the reflector as much as possible from below the transmissive part or the reflector.

  Further, in the image analysis by the image processing apparatus, a process for detecting wrinkles based on a brighter part in a range where a dark area is captured in an image and a process for detecting wrinkles based on a darker part within a range where a bright area is captured. Only one of the processes may be executed, or both may be executed.

  In addition, the dark area and the bright area in the above description are recognized using a predetermined threshold relating to luminance in image processing, but a third area having an intermediate luminance located between the dark area and the bright area. May also be used. In this case, wrinkle detection is performed based on a darker or brighter portion in the third region.

  Further, as described above, the darker or brighter portion in the image that is used for the detection of wrinkles is not limited to the one that appears in continuous pixels. For example, even if it is a minute flaw or a stain and is not determined as a wrinkle in an image that appears alone in an image, it may be included in a target that is detected as a wrinkle based on its number and arrangement. As a specific example, a thing in which a plurality of minute scratches are densely arranged or a line having a certain length or more across a short interval is easily recognized by a person and relates to the quality of the product. Individual images of such scratches are non-continuous on the image, but may be recognized as wrinkles based on their spacing or extent that extends or extends.

  Further, the image on which the image integration unit superimposes the image of the eyelid is not limited to an image in which a dark area and a bright area are shown as shown in FIG. 9A. For example, it may be an image of an object photographed under a reflector having a uniform reflectivity over the entire concave surface, or may be an image of an object photographed in a situation where no reflector is placed. . Or, it may be a processed image of a specimen imaged with a reflector, for example, an image of a specimen 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, an image analysis unit performs processing for attaching information (coloring, enclosing, arrows, etc.) indicating the position of the wrinkle to the image itself in which wrinkles are detected by the analysis, and the processed image data is output to the output unit May be output from. The output is not limited to image data. For example, it may be data including a number for identifying the eyelid, coordinates indicating the position of the eyelid or its outline in the image, and the like. When a plurality of types of wrinkles can be detected, the presentation mode may be changed for each type of wrinkles.

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

  In addition, a device that implements 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.

  In addition, the embodiment has been described by using a specimen whose surface is a mirror surface or a mirror surface as an example, but this is a specimen that can be visually inspected using the appearance inspection system or the appearance inspection apparatus according to the present invention. It is not limited. For example, it can also be used for appearance inspection of a test object that has been subjected to surface treatment of hairline or satin.

[Effect of the present invention]
According to the appearance inspection system or the appearance inspection apparatus of the present invention, even a test object having a complicated surface angle can be quickly and widely inspected for stains, color unevenness, and the same as those wrinkles. It is also possible to detect a flaw on the mirror surface or a surface close to the mirror surface, which is difficult to detect in the inspection, with high accuracy.

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

DESCRIPTION OF SYMBOLS 1 Appearance inspection system 10 Appearance inspection apparatus 11 Holding stand 12, 12A, 12B, 12C, 12D, 12E Reflector 13 Light source part 14 Rotating mechanism 15 Camera 20 Image processing apparatus 122, 122A, 122B, 122C, 122D, 122E Transmission part 124 , 124A, 124B, 124C, 124D, 124E Bright part 126, 126A, 126B, 126C, 126D, 126E Dark part 151 Imaging part 152 Communication part 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 apparatus for inspecting 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-like reflector having a concave surface located on the side of the surface to be observed of the test object and facing the surface to be observed;
A light source unit that is located on the opposite side of the surface to be observed of the test object and emits light that illuminates the concave surface with a substantially uniform illuminance;
A rotation mechanism,
The reflector includes a transmissive portion that transmits incident light emitted from the light source unit and reaching the concave surface, a bright portion that reflects the incident light and falls on the surface to be observed, and is more reflective than the bright portion. A dark portion having a low rate and creating a shadow on the surface to be observed;
The rotating mechanism changes at least one of the holding table and the dark part to change a relative posture of the test object with respect to the dark part, thereby forming at least a part of the observation surface of the dark part. Rotating operation to switch between dark state with shadow and bright state without shadow,
Appearance inspection device. The rotating mechanism switches the observation surface at least once between the dark state and the bright state by changing the relative posture of the test object with respect to the dark part.
The appearance inspection apparatus according to claim 1. The reflector is partly a half mirror, and the transmission part and the bright part overlap in the region of the half mirror.
The appearance inspection apparatus according to claim 1 or 2. In the reflector, the transmissive part is transparent or a through-hole of the reflector, and the bright part is a white surface or a mirror surface.
The appearance inspection apparatus according to claim 1 or 2. One of the bright part and the dark part is a region having a circular contour on the concave surface, and the other is in a region outside the contour.
The appearance inspection apparatus according to any one of claims 1 to 4. One of the bright part and the dark part is an outline that intersects with one latitude line assumed for the reflector at a plurality of locations on the concave surface, and intersecting angles with the latitude lines at the plurality of locations are different from each other. A region having a contour, the other being in a region outside the contour,
The appearance inspection apparatus according to any one of claims 1 to 4. One of the bright part and the dark part is a plurality of regions separated by the other in the concave surface,
The appearance inspection apparatus according to claim 5 or 6. Further, an imaging unit that captures an image of the observed surface by receiving the incident light that is reflected by the concave surface and once falls on the observed surface, then reflected by the observed surface and then transmitted through the transmitting portion. Comprising
The appearance inspection apparatus according to any one of claims 1 to 7. An appearance inspection apparatus according to claim 8;
An image processing apparatus,
The image processing apparatus includes:
An input unit that receives input of a plurality of images of the surface to be observed imaged by the imaging unit of the test object in a different relative posture due to the rotation mechanism performing the rotation operation; and
Analyzing the plurality of input images, an image analysis unit for detecting wrinkles on the observed surface;
An output unit that outputs data of information indicating the detected wrinkles,
Appearance inspection system. The image analysis unit detects the wrinkle based on a brighter part in the range where the dark state area is reflected in the image or a darker part in the range where the bright state area is reflected.
The appearance inspection system according to claim 9.