JP2020193890A - Visual inspection apparatus - Google Patents

Abstract

To provide a visual inspection apparatus capable of simultaneously inspecting defects exposed to the surface and the inside of an inspection object, with which it is made possible to recognize a larger number of defects while suppressing an increase in the size of the apparatus structure.SOLUTION: A visual inspection apparatus 10 comprises: lights 11R, 11G, 11B for irradiating an inspection object W at respectively different angles with red, green and blue rays of light having the same linear polarization characteristic; a polarization beam splitter 13 for separating reflected light 30 into reflected light 31 having a prescribed linear polarization characteristic and reflected light 32 having the prescribed linear polarization characteristic removed; a color camera 15 for simultaneously photographing parallel beams 31, 32 of reflected light; and an image processing device 16 for extracting red, green and blue color components from the image of the color camera 15. Thus, it is made possible to actualize a greater number of defects by optimizing the irradiation angle of each illumination in accordance with the inspection object. Moreover, as the beams of reflected light 31, 32 enter the same color camera 15, it is possible to suppress an increase in the size of the apparatus structure.SELECTED DRAWING: Figure 1

Description

The present invention relates to a visual inspection apparatus, and more particularly to a visual inspection apparatus capable of simultaneously inspecting both a defect exposed on the surface of an inspection object and a defect existing inside the inspection object.

As a visual inspection apparatus for visually inspecting an inspection object such as a chip part, the visual inspection apparatus described in Patent Documents 1 and 2 is known. In the visual inspection apparatus described in Patent Documents 1 and 2, the angle formed by the red light illumination irradiation axis and the optical axis is set large, while the angle formed by the blue light illumination irradiation axis and the optical axis is small. , A dark field optical system and a bright field optical system are realized. In dark-field optics, since the reflection from the surface of the inspection object (specular reflection) does not enter the camera, only the reflection of the light that has entered the inside of the inspection object (diffuse reflection) is incident on the camera. On the other hand, in the bright-field optical system, both specular reflection and diffuse reflection are incident on the camera, but since the reflectance of specular reflection is high, the reflection from the target surface is dominant in the obtained image. As described above, in the visual inspection apparatus described in Patent Documents 1 and 2, the internal defects and surface defects of the inspection object are visualized by fixing the illumination irradiation angle to a predetermined angle in advance.

However, in the visual inspection devices described in Patent Documents 1 and 2, since the illumination irradiation angle is fixed to a predetermined angle in advance, there is a problem that defects that do not become apparent at the irradiation angle cannot be found. there were.

On the other hand, in Patent Documents 3 to 5, the reflected light from the inspection object is separated into an S-polarized wave and a P-polarized wave by using a polarizing beam splitter, and an image composed of the S-polarized wave and an image composed of the P-polarized wave are separated from each other. Methods of shooting with different cameras are disclosed. According to this method, it is possible to recognize both the defects existing on the surface of the inspection object and the defects existing inside the inspection object without using illumination of a plurality of wavelengths.

Japanese Patent No. 471279 Japanese Patent No. 4493048 Japanese Unexamined Patent Publication No. 10-2276223 Japanese Patent No. 3358099 Japanese Patent No. 4716827

However, even in the visual inspection apparatus described in Patent Documents 3 to 5, it is difficult to find a defect that does not become apparent at the irradiation angle. Moreover, since two cameras, one for which the S-polarized wave is incident and the other for which the P-polarized wave is incident, are required, there is also a problem that the apparatus configuration becomes large.

Therefore, the present invention is a visual inspection apparatus capable of simultaneously inspecting both the defects exposed on the surface of the inspection object and the defects existing inside the inspection object, while suppressing the increase in size of the apparatus configuration. The purpose is to make the defect recognizable.

The visual inspection apparatus according to the present invention irradiates the inspection object with a stage on which the inspection object is placed and a first polarization having a first wavelength and a predetermined linear polarization characteristic at a first angle. A first illumination and a second polarization having a second wavelength different from the first wavelength and having the same linear polarization characteristic as a predetermined linear polarization characteristic are applied at a second angle different from the first angle. The second illumination that irradiates the inspection object, the first reflected light that receives the reflected light from the inspection object and has a predetermined linear polarization characteristic, and the second reflected light from which the predetermined linear polarization characteristic is removed. The first polarized beam splitter to be separated, the first mirror in which the optical axis of the first reflected light and the optical axis of the second reflected light are parallel to each other, and the parallel first and second reflected light are simultaneously received. , A first color camera that produces a first image based on the first reflected light, a second image based on the second reflected light, and a first wavelength component and a second wavelength from the first image. It is characterized by comprising an image processing apparatus that extracts a first wavelength component and a second wavelength component from a second image while extracting the components.

According to the present invention, since a plurality of illuminations having different wavelengths and irradiation angles are used and separated into two reflected lights having different linear polarization characteristics for each wavelength, irradiation of each illumination is performed according to the inspection object. By optimizing the angle, it becomes possible to expose more defects. Moreover, since the two reflected lights separated by the polarizing beam splitter are parallelized by the mirror and incident on the same color camera, it is possible to suppress the increase in size of the apparatus configuration.

FIG. 1 is a schematic view for explaining the configuration of the visual inspection apparatus 10 according to the first embodiment of the present invention. FIG. 2 is a schematic view showing an example in which the ND filter 42 and the glass plate 41 are arranged on the optical paths of the reflected lights 31 and 32, respectively. FIG. 3 is an image obtained by extracting red light from the reflected lights 31 and 32, the left side is an image based on the reflected light 31, and the right side is an image based on the reflected light 32. FIG. 4 is an image obtained by extracting green light from the reflected lights 31 and 32, the left side is an image based on the reflected light 31, and the right side is an image based on the reflected light 32. FIG. 5 is an image obtained by extracting blue light from the reflected lights 31 and 32, the left side is an image based on the reflected light 31, and the right side is an image based on the reflected light 32. FIG. 6 is a schematic view for explaining the configuration of the visual inspection apparatus 20 according to the second embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a schematic view for explaining the configuration of the visual inspection apparatus 10 according to the first embodiment of the present invention.

As shown in FIG. 1, the visual inspection apparatus 10 according to the first embodiment includes a transparent stage S on which an inspection object (work) W is placed, and illuminations 11R and 11G that irradiate the inspection object W with light. , 11B, 11RGB. The type of the inspection target W is not particularly limited, but a small chip component such as a multilayer ceramic capacitor can be targeted. A small chip component such as a multilayer ceramic capacitor may have a defect on its surface and may have a defect inside (surface layer portion). Therefore, the visual inspection apparatus 10 according to the present embodiment has an inspection object W. It is possible to simultaneously inspect both the defects exposed on the surface of the ceramic surface and the defects existing inside the inspection object W.

The illuminations 11R, 11G, and 11B irradiate the inspection object W with light having different wavelengths and irradiation angles from each other. Here, the illumination 11R irradiates red light, the illumination 11G irradiates green light, and the illumination 11B irradiates blue light. Further, the illumination 11RGB is an auxiliary illumination for supplementing the brightness by irradiating white light in which red light, green light and blue light are mixed. Here, the reason why the inspection object W is irradiated with three types of light having different irradiation angles is that the types of defects that become apparent differ depending on the irradiation angle. For example, when the inspection object W is a multilayer ceramic capacitor, the illumination 11R is used for inspecting scratches, stains and foreign substances on the surface of the ceramic portion, stains and foreign substances inside the ceramic portion, and the size and shape of the terminal electrode portion. Is suitable. Further, the illumination 11G is suitable for inspecting a chip on the ridgeline of the ceramic portion. Further, the illumination 11B is suitable for inspecting metal foreign matter on the surface of the ceramic portion, chipping on the ridgeline of the ceramic portion, and cracks inside the ceramic portion. By separating the wavelengths of each of these illumination lights and then taking an image with a color camera, it is possible to obtain three types of images having different irradiation angles in one image.

Here, the contrast of the defects that become apparent by each illumination changes greatly depending on the irradiation angle. For example, the defect that becomes apparent by the illumination 11R is enhanced in contrast by irradiating the irradiation light as parallel to the optical axis as possible. In consideration of this point, in the present embodiment, the irradiation angle of the illumination 11R is tilted by 90 ° with respect to the optical axis, and the half mirror 12 is used to guide the illumination 11R coaxially with the optical axis. On the other hand, the defect that becomes apparent by the illumination 11B is enhanced in contrast by irradiating the irradiation light at a certain angle with respect to the optical axis. In consideration of this point, in the present embodiment, the irradiation angle of the illumination 11B is tilted to a predetermined angle with respect to the optical axis. Further, the defect that becomes apparent by the illumination 11G is enhanced in contrast by irradiating it from the back surface side of the inspection object W. In consideration of this point, in the present embodiment, the illumination 11G is irradiated from the back surface S2 side of the stage S. On the other hand, the illuminations 11R and 11B are arranged on the mounting surface S1 side of the stage S on which the inspection object W is mounted.

As described above, the visual inspection apparatus 10 according to the present embodiment irradiates the inspection object W with light having different wavelengths at different angles. Further, the irradiation angles of the illuminations 11R, 11G, and 11B are not fixed, and can be appropriately adjusted so that the highest contrast can be obtained.

Each of the illuminations 11R, 11G, 11B includes a polarizing filter (not shown), and the light emitted from each of the illuminations 11R, 11G, 11B has the same linear polarization characteristics. For example, the light emitted from each of the illuminations 11R, 11G, and 11B may be an S-polarized wave. In this case, since the light emitted to the inspection object W is an S-polarized wave for each wavelength component, the specularly reflected light from the inspection object W is also an S-polarized wave. On the other hand, the diffusely reflected light obtained by diffusing the irradiated light on the surface layer of the inspection object W loses its polarization characteristics and becomes an unpolarized wave. Therefore, the reflected light 30 passing through the half mirror 12 contains a mixture of S-polarized waves due to specular reflection and unpolarized waves due to diffuse reflection.

The reflected light 30 is incident on the polarizing beam splitter 13 and is separated into the first reflected light 31 and the second reflected light 32 by the polarizing beam splitter 13. The first reflected light 31 is light containing a linearly polarized light component of the light emitted from each of the illuminations 11R, 11G, and 11B, and the reflected light 30 may be passed through as it is, or the linearly polarized light component may be used. It may be light that has passed through a polarizing filter that selectively passes through. That is, when the light emitted from each of the illuminations 11R, 11G, 11B is an S-polarized wave, the first reflected light 31 is light including the S-polarized wave. Therefore, the main component of the first reflected light 31 is the specularly reflected light from the inspection object W.

On the other hand, the second reflected light 32 is light from which the linearly polarized light component of the light emitted from each of the illuminations 11R, 11G, 11B is removed, and passes through a polarizing filter that selectively cuts the linearly polarized light component. It is the light that made me. For example, when the light emitted from each of the illuminations 11R, 11G, 11B is an S-polarized wave, the S-polarized wave is removed by using a polarizing filter that selectively passes the P-polarized wave. Therefore, the main component of the second reflected light 32 is the diffuse reflected light from the inspection object W. However, it is not essential to completely remove the S-polarized wave from the second reflected light 32, and it is sufficient if at least a part of the S-polarized wave is removed.

The second reflected light 32 is incident on the prism 14, and the traveling direction is bent by 90 ° by the mirror 14 m included in the prism 14, so that the second reflected light 32 is parallel to the first reflected light 31. The parallel first and second reflected lights 31, 32 are incident on the color camera 15. As a result, an image based on the first reflected light 31 and an image based on the second reflected light 32 can be obtained at the same time. The image obtained by the color camera 15 is supplied to the image processing device 16.

Here, as shown in FIG. 2, a glass plate 41 that matches the optical path length of the first reflected light 31 and the optical path length of the second reflected light 32 is arranged on the optical path of the second reflected light 32. Is preferable. In this way, if the optical path length of the first reflected light 31 and the optical path length of the second reflected light 32 are matched by using the glass plate 41, the color camera 15 has an image composed of the first reflected light 31 and a second. It is possible to correctly focus on both of the images composed of the reflected light 32 of 2. Further, as shown in FIG. 2, it is preferable to arrange an ND filter 42 for reducing the amount of light of the first reflected light 31 on the optical path of the first reflected light 31. In this way, if the amount of light of the first reflected light 31 is reduced by using the ND filter 42, it is possible to reduce the difference between the amount of light of the first reflected light 31 and the amount of light of the second reflected light 32. Become.

The image processing device 16 generates three images by extracting the wavelength components of the illuminations 11R, 11G, and 11B from the image obtained by the color camera 15. That is, an image obtained by extracting red light from the reflected light 31 and 32, an image obtained by extracting green light from the reflected light 31 and 32, and an image obtained by extracting blue light from the reflected light 31 and 32 can be obtained. Each image can be confirmed by the operator via the monitor 17.

3 to 5 are images obtained by extracting red light, green light, and blue light from the reflected light 31 and 32, respectively. The left side is an image based on the reflected light 31, and the right side is an image based on the reflected light 32. As shown in FIGS. 3 to 5, the visual inspection apparatus 10 according to the present embodiment can simultaneously acquire six images from one inspection object W. The six images are, that is, an image obtained by specular reflection of red light, green light and blue light, and an image obtained by diffuse reflection of red light, green light and blue light. As shown in FIGS. 3 to 5, the state of the surface and the ridge line of the inspection object W can be grasped from the images obtained by specular reflection, and the inside of the inspection object W can be grasped from the images obtained by diffuse reflection. It can be seen that the state of the ridge and the ridge can be grasped.

As described above, according to the visual inspection apparatus 10 according to the present embodiment, six images can be simultaneously acquired from one inspection object W. Further, since the irradiation angles of the illuminations 11R, 11G, and 11B can be arbitrarily changed so as to have the highest contrast, more defects can be made apparent. Moreover, since the two reflected lights 31 and 32 separated by the polarizing beam splitter 13 are parallelized and incident on the same color camera 15, it is possible to suppress the increase in size of the apparatus configuration.

<Second embodiment>
FIG. 6 is a schematic view for explaining the configuration of the visual inspection apparatus 20 according to the second embodiment of the present invention.

As shown in FIG. 6, the visual inspection device 20 according to the second embodiment uses two color cameras 26U and 26L to inspect an object (work) mounted on the mounting surface S1 of the transparent stage S. ) W is photographed from both the upper and lower sides at the same time. Lighting 21R, 21B, 21RGB, half mirror 23U, polarization beam splitter 24U, prism 25U and color camera 26U are arranged on the mounting surface S1 side of the stage S, and lighting 22R, 22G on the back surface S2 side of the stage S. , 22RGB, half mirror 23L, polarization beam splitter 24L, prism 25L and color camera 26L are arranged. Here, since the stage S is transparent, the light from the illuminations 22R and 22G arranged on the back surface S2 side is also irradiated to the inspection object W.

The illuminations 21R and 21B irradiate red light and blue light, respectively, and both illuminate the inspection object W from four directions, front, back, left, and right. Here, since the positions of the illumination 21R and the illumination 21B are different from each other from the stage S, the irradiation angle of the red light by the illumination 21R and the irradiation angle of the blue light by the illumination 21B are different from each other. In the example shown in FIG. 6, the illumination 21R constitutes high-angle illumination and the illumination 21B constitutes low-angle illumination. The illumination 21RGB is an auxiliary illumination for supplementing the brightness by irradiating white light in which red light, green light, and blue light are mixed, and is irradiated coaxially with the optical axis of the color camera 26U by the half mirror 23U.

The illuminations 22R and 22G irradiate red light and green light, respectively, and both illuminate the inspection object W from four directions, front, back, left, and right. Here, since the positions of the illumination 22R and the illumination 22G are different from each other from the stage S, the irradiation angle of the red light by the illumination 22R and the irradiation angle of the green light by the illumination 22G are different from each other. In the example shown in FIG. 6, the illumination 22R constitutes high-angle illumination and the illumination 22G constitutes low-angle illumination. The illumination 22RGB is an auxiliary illumination for supplementing the brightness by irradiating white light in which red light, green light, and blue light are mixed, and is irradiated coaxially with the optical axis of the color camera 26L by the half mirror 23L.

Similar to the first embodiment, each of the illuminations 21R, 21B, 22R, 22G includes a polarizing filter (not shown), and the light emitted from each of the illuminations 21R, 21B, 22R, 22G has the same linear polarization characteristics (for example,). S polarized wave). The polarized beam splitters 24U and 24L are irradiated from light containing a linearly polarized light component of light emitted from each of the illuminations 21R, 21B, 22R and 22G, that is, specularly reflected light and each illumination 21R, 21B, 22R and 22G. The linearly polarized light component of the light is removed, that is, it is separated into diffusely reflected light. The specular reflected light and the diffuse reflected light are parallelized by the mirrors 25Um and 25Lm included in the prisms 25U and 25L, and are incident on the color cameras 26U and 26L.

With such a configuration, the color camera 26U can photograph the inspection object W from the upper surface side, and the color camera 26L can photograph the inspection object W from the lower surface side. Then, the image processing device 27 extracts a red component, a green component, and a blue component from the images obtained by the color cameras 26U and 26L, so that a total of 12 images composed of an image by specular reflection light or an image by diffuse reflection light are formed. Generate an image. Each image can be confirmed by the operator via the monitor 28.

As described above, according to the visual inspection device 20 according to the present embodiment, in addition to the effect of the visual inspection device 10 according to the first embodiment, inspection is performed by simultaneously photographing from one inspection object W from both the upper and lower sides. The entire object W can be inspected at once.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention, and these are also the present invention. It goes without saying that it is included in the range.

For example, in each of the above embodiments, the inspection object W is irradiated with three colors of light including red light, green light, and blue light, but it is not essential to use the three colors of light in the present invention. Depending on the type of the object W to be inspected and the type of defect to be detected, two colors or four or more colors of light may be used.

10,20 Visual inspection equipment 11R, 11G, 11B, 11RGB, 21R, 21B, 21RGB, 22R, 22G, 22RGB Lighting 12, 23L, 23U Half mirror 13, 24L, 24U Polarized beam splitter 14, 25L, 25U Prism 14m, 25Lm , 25Um Mirror 15, 26U, 26L Color camera 16, 27 Image processing device 17, 28 Monitor 30-32 Reflected light 41 Glass plate 42 ND filter S Stage S1 Mounting surface S2 Back surface W Inspection object

Claims (6)

The stage on which the inspection object is placed and
A first illumination that irradiates the inspection object with a first polarized light having a first wavelength and a predetermined linear polarization characteristic at a first angle.
The inspection target is a second polarized light having a second wavelength different from the first wavelength and having the same linear polarization characteristic as the predetermined linear polarization characteristic at a second angle different from the first angle. A second light that illuminates an object,
A first polarized beam splitter that receives reflected light from the inspection object and separates it into a first reflected light having the predetermined linear polarization characteristic and a second reflected light from which the predetermined linear polarization characteristic has been removed. When,
A first mirror in which the optical axis of the first reflected light and the optical axis of the second reflected light are parallel to each other.
A first color camera that simultaneously receives the first and second reflected lights in parallel and generates a first image based on the first reflected light and a second image based on the second reflected light. ,
An image processing device that extracts the first wavelength component and the second wavelength component from the first image and extracts the first wavelength component and the second wavelength component from the second image. , A visual inspection apparatus comprising. A third polarized light having a third wavelength different from the first and second wavelengths and having the same linear polarization characteristic as the predetermined linear polarization characteristic is different from the first and second angles. Further equipped with a third illumination that illuminates the inspection object at the angle of
The first aspect of the present invention, wherein the image processing apparatus further extracts the third wavelength component from the first image and further extracts the third wavelength component from the second image. Visual inspection equipment. A claim, further comprising a glass plate arranged on the optical path of the first or second reflected light and matching the optical path length of the first reflected light with the optical path length of the second reflected light. The visual inspection apparatus according to 1 or 2. The visual inspection apparatus according to any one of claims 1 to 3, further comprising an ND filter arranged on the optical path of the first or second reflected light. The stage is transparent
The first illumination is located on the surface of the stage on the mounting surface side on which the inspection object is mounted.
The visual inspection apparatus according to any one of claims 1 to 4, wherein the second illumination is located on the back surface side of the front surface of the stage opposite to the above-described mounting surface. A second polarized light that receives another reflected light from the inspection object and separates it into a third reflected light having the predetermined linear polarization characteristic and a fourth reflected light from which the predetermined linear polarization characteristic has been removed. Beam splitter and
A second mirror in which the optical axis of the third reflected light and the optical axis of the fourth reflected light are parallel to each other.
A second color camera that simultaneously receives the third and fourth reflected lights in parallel and obtains a third image based on the third reflected light and a fourth image based on the fourth reflected light. With more
The image processing apparatus extracts the first wavelength component and the second wavelength component from the third image, and extracts the first wavelength component and the second wavelength component from the fourth image. Extract and
The first polarization beam splitter and the first color camera are provided on the front surface side of the stage.
The visual inspection apparatus according to claim 5, wherein the second polarization beam splitter and the second color camera are provided on the back surface side of the stage.