CN111272762B - Surface defect inspection device for light-transmitting member - Google Patents
Surface defect inspection device for light-transmitting member Download PDFInfo
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- CN111272762B CN111272762B CN201911211712.7A CN201911211712A CN111272762B CN 111272762 B CN111272762 B CN 111272762B CN 201911211712 A CN201911211712 A CN 201911211712A CN 111272762 B CN111272762 B CN 111272762B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N21/958—Inspecting transparent materials or objects, e.g. windscreens
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
- G01N2021/8829—Shadow projection or structured background, e.g. for deflectometry
- G01N2021/8832—Structured background, e.g. for transparent objects
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
- G01N2021/8887—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges based on image processing techniques
Abstract
The invention provides a device which has high degree of freedom of arrangement and can inspect surface defects of a light-transmitting inspected object with high precision. A pattern irradiation unit is disposed on the back surface side of a light-transmitting workpiece, the pattern irradiation unit is composed of a light-shielding material for forming a bright and dark pattern and an illumination light source, the bright and dark pattern irradiated by the irradiation unit is shot through the workpiece by a shooting unit opposite to the irradiation unit through the workpiece, the image signal processing unit detects the surface defect of the workpiece based on the change (flare) of the emergent light quantity (brightness) on the shot image, the light of the transmitted light-transmitting part is guided to the light-shielding part side by a light diffusion unit as diffused light, the emergent light quantity in the dark part of the workpiece is increased, accordingly, the defect in the dark part is promoted to be obvious as the flare, and the detection precision is improved.
Description
Technical Field
The present invention relates to an apparatus for inspecting defects such as flaws on the surface of a translucent resin member such as a headlight cover for an automobile.
Background
Patent document 1 discloses a method and apparatus for inspecting a surface defect of an object to be inspected, in which a slit pattern (slit pattern) in which bright portions and dark portions are alternately continuous is irradiated to the surface of the object to be inspected such as a plating product or a coating product, the slit pattern mapped on the object to be inspected is imaged, and a detection unit (a signal processing unit having a built-in computer) detects the presence or absence of a defect based on a difference in the reflected light amount (brightness) of light in the imaged image.
That is, since the reflected light amount (luminance) at the defect such as the concave-convex or the flaw when light is irradiated is different from the reflected light amount (luminance) at the surface without the defect, the defect of the surface of the object to be inspected can be detected by detecting the change in the reflected light amount (luminance).
However, the amount of light irradiated in the dark portion is smaller than that in the bright portion, and accordingly, the difference between the amount of reflected light (luminance) at the defective portion and the amount of reflected light (luminance) at the surface without the defect in the captured image is smaller, and accordingly, the detection accuracy is also lower. Accordingly, the following patent document 2 has been proposed.
In patent document 2, a slit pattern imaged on an object to be inspected is imaged in synchronization with the movement of the slit pattern while the slit pattern is moved in a predetermined direction along the surface of the object to be inspected (for example, in a direction in which bright portions and dark portions of the slit pattern are alternately continued at a predetermined pitch), and a detection unit detects the presence or absence of a defect based on a change in the amount (brightness) of reflected light in a composite image obtained by combining a plurality of imaged images.
Since the slit pattern is moved along the surface of the object to be inspected in the direction in which the bright portion and the dark portion are continuous, for example, the defect can be captured at a position corresponding to the bright portion (the defect is irradiated with light at a certain position) with a certain degree of accuracy.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 63-95309
Patent document 2: japanese patent application laid-open No. 3197766
Disclosure of Invention
Problems to be solved by the utility model
However, in the conventional device, a slit pattern is formed by irradiating the surface of the object from an oblique direction, and the surface of the object is imaged by a camera from a direction orthogonal to the pattern irradiation direction.
That is, in such an inspection apparatus, in order to perform an inspection with high accuracy, it is desirable to irradiate the entire surface of the object to be inspected with a slit pattern having a small deformation, and to photograph the entire surface of the object to be inspected with the slit pattern. Therefore, it is desirable that the slit pattern irradiation means (the illumination light source and the pattern formation shade) is disposed so as to face the surface of the object to be inspected, and the camera is disposed behind the pattern irradiation means, and at this time, the pattern irradiation means disposed in front of the camera becomes an obstacle to photographing.
Therefore, in the conventional inspection apparatus (prior patent documents 1 and 2), it is necessary to dispose the pattern irradiation unit and the camera at an angle of approximately 45 degrees with respect to the surface of the object to be inspected, and there is no degree of freedom in disposing the equipment (inspection apparatus constituent member) constituting the apparatus (subject 1).
Further, since the slit pattern is irradiated onto the object to be inspected from the oblique direction and the slit pattern is photographed from the oblique direction, the slit pattern mapped on the surface of the object to be inspected is deformed in the area where the object to be inspected is bent, and the bright and dark boundary of the slit pattern becomes unclear, making it difficult to distinguish the change in the reflected light amount (luminance) at the defect (problem 2).
Further, as the degree of bending of the surface of the object to be inspected is increased, an area (an area that cannot be inspected) that cannot be imaged by the camera is generated (problem 3).
Accordingly, the inventors have found that, when a device for inspecting surface defects of a transparent resin product such as a front cover for a headlight is newly developed, the above-described 1 st, 2 nd, and 3 rd problems can be solved by constructing an inspection device as follows in consideration of the specificity (light transmittance, curved shape) of an object to be inspected.
That is, the pattern irradiation unit that is originally disposed on the front surface side of the subject is disposed on the back surface side of the subject (front cover), and the pattern irradiation unit is disposed so as to face the curved subject (front cover) with the camera interposed therebetween. The slit pattern irradiated by the pattern irradiation unit is photographed by the camera through the transparent front cover, but the depth of field of the camera is adjusted so that the Focus (Focus) is focused on the entire area between the pattern irradiation unit and the front cover, and the clear slit pattern is overlapped with the surface of the clear front cover in the image photographed by the camera.
Further, although the slit pattern irradiated to the back surface of the object to be inspected (front cover) transmits the transparent object to be inspected (front cover) to perform light distribution in the forward direction, since the amount of emitted light (luminance) at the defects such as irregularities and flaws on the surface of the object to be inspected (front cover) when the light is irradiated to the back surface of the object to be inspected (front cover) is different from the amount of emitted light (luminance) at the surface without defects, the detection means can detect the change in the amount of emitted light (luminance) from the slit pattern and the image of the surface of the object to be inspected (front cover) captured by the camera, thereby enabling detection of the defects on the surface of the object to be inspected.
The inventors made a test using an inspection apparatus (hereinafter referred to as a 1 st test machine) in which the specificity (light transmittance and curved shape) of the object to be inspected was considered, and confirmed that the 1 st, 2 nd and 3 rd problems described above were all eliminated. However, it is newly found that the following problem (problem 4) similar to the conventional patent document 1 exists in the 1 st trial machine.
That is, as described above, the irradiation light of the pattern irradiation means (irradiation light forming a slit pattern in which bright portions and dark portions are alternately continuous) is transmitted through the transparent object to be inspected (front cover) and is emitted from the surface of the object to be inspected (front cover), but in the region of the object to be inspected (front cover) corresponding to the dark portions, the amount of irradiation light is small and the amount of emitted light from the surface of the object to be inspected is small as compared with the region corresponding to the bright portions. Therefore, in the region of the surface of the object corresponding to the dark portion, the difference between the amount of light emitted from the defect (luminance) and the amount of light emitted from the surface without the defect (luminance) is relatively small, the defect is not apparent as a flare, and the detection accuracy of the defect is lowered.
The decrease in the detection accuracy of the defect in the 1 st test machine can be explained as follows.
Fig. 9 and 10 are views showing the main configuration of the 1 st test machine and the image captured by the camera, respectively, and are views for explaining a mode in which when the irradiation light (slit pattern in which bright portions and dark portions are alternately continuous) of the pattern irradiation unit 2 is captured while passing through the subject (front cover) 30, the slit pattern P in which the bright portions Pa and the dark portions Pb are continuous is formed on the surface of the transparent subject (front cover) 30. The pattern-forming light-shielding material 20 has a structure in which light-shielding portions 24 having a width of 10mm and having a black ink layer 25 formed on a light-transmitting resin film 21 and light-transmitting portions 22 having a width of 10mm and having no black ink layer 25 formed thereon are alternately continuous, and the black ink layer 25-forming side is disposed toward the subject 30.
As shown in fig. 9A, the diffused light L1 transmitted through the light transmitting portion 22 of the light shielding material 20 is guided to a region along the bright-dark boundary Pc in the dark portion Pb corresponding to the light shielding portion 24 of the pattern forming light shielding material 20 on the surface of the object 30, and a difference is generated between the amount of light emitted from the defect S1 (luminance) and the amount of light emitted from the surface without the defect S1 (luminance) in the vicinity of the bright-dark boundary Pc in the dark portion Pb, and as shown in fig. 9B, the defect S1 becomes apparent as a flare in the image, so that the defect S1 can be detected.
On the other hand, as shown in fig. 10A, regarding a defect S2 existing near the widthwise center in the dark portion Pb, which is located at a position distant from the bright-dark boundary Pc by 3mm or more from the bright-dark boundary Pc, for example, the diffused light L1 from the light transmitting portion 22 is not guided to the defect S2 at all, and the difference between the amount of emitted light (luminance) from the defect S2 and the amount of emitted light (luminance) from the face without the defect S2 is relatively small, as shown in fig. 10B, the defect S2 is not noticeable as a flare in the image, so that the defect S2 cannot be detected.
Accordingly, the inventors consider the following.
A light diffusion means for diffusing the light emitted from the light transmitting portion 22 toward the light shielding portion 24 side is provided on the slit pattern forming shade 20 constituting the pattern irradiation means 2, and if the light emitted from the light transmitting portion 22 is positively guided as diffused light to a region along the bright-dark boundary Pc in the dark portion Pb of the slit pattern P formed on the surface of the object (front cover) 30, the region to which the diffused light is guided expands in the width direction in the dark portion Pb, and the amount of light guided into the dark portion Pb and the amount of light emitted from the dark portion Pb increase.
As a result, in the dark portion Pb of the slit pattern, the difference between the amount of light (luminance) emitted from the defect and the amount of light (luminance) emitted from the surface without the defect becomes relatively large, and the amount of light (luminance) emitted is not so small, so that the defect that is not noticeable as a flare in the image is also noticeable as a flare by being guided by the diffused light, that is, the detection accuracy of the defect is improved.
The present application was made by improving the above-mentioned trial machine 1 so that the slit pattern formation shade 20 was provided with a light diffusing means, and verifying the effect thereof, and confirming that the above-mentioned problem 4 is also effective.
The present invention has been made in view of the above-described problems of the prior art and the findings of the inventors, and an object of the present invention is to provide a surface defect inspection device for a light-transmissive member, which inspects surface defects of a light-transmissive resin member with high accuracy, with a high degree of freedom in arrangement of inspection equipment.
Means for solving the problems
In order to achieve the above object, a surface defect inspection apparatus for a light-transmitting member according to one aspect of the present invention includes:
a pattern irradiation unit configured by a light-dark pattern forming shade in which a light-transmitting portion and a shade portion are alternately continuous, and an illumination light source provided on the back surface side of the shade, and irradiating a light-dark pattern in which a light portion and a dark portion corresponding to the light-transmitting portion and the shade portion are alternately continuous;
a light-transmitting resin member as an object to be inspected, the back surface side of which is disposed toward the pattern irradiation unit;
an imaging unit arranged to face the pattern irradiation unit through the subject to be inspected, and to image the bright and dark pattern through the subject to be inspected; a kind of electronic device with high-pressure air-conditioning system
A detection unit as an image signal processing unit for detecting a defect on the surface of the object based on a change in the amount of emitted light (brightness) in the image captured by the capturing unit,
the light-shielding material for forming a bright-dark pattern is provided with a light diffusion means for diffusing the light transmitted through the light-transmitting portion toward the light-shielding portion.
Since the depth of field of the photographing unit is adjusted so that the focal point is focused on the entire area between the pattern irradiation unit and the subject (light-transmissive resin member), on the image photographed by the photographing unit, the irradiation light of the pattern irradiation unit, that is, the clear image of the bright and dark pattern, which alternately continues with the light-transmissive portion and the dark portion of the light-shielding object, is displayed overlapping with the clear image of the light-transmissive resin member surface as the subject.
On the other hand, the light and dark pattern irradiated to the back surface of the light-transmissive resin member, which is the object to be inspected, is subjected to light distribution in the forward direction through the object to be inspected (light-transmissive resin member), but the light and dark pattern in which the light portion and the dark portion are alternately continuous is formed on the surface of the object to be inspected (light-transmissive resin member).
The bright portion of the bright-dark pattern formed on the front surface (back surface) of the object (light-transmissive resin member) is formed by the light-transmissive portion of the light-shielding material being transmitted by the irradiation light from the illumination light source, while the dark portion of the bright-dark pattern is formed by the irradiation light from the illumination light source being blocked by the light-shielding portion of the light-shielding material.
When the irradiation light irradiated to the back surface side of the object to be inspected (light-transmitting resin member) is transmitted through the object to be inspected and is emitted from the front surface side thereof, the amount of emitted light (luminance) from the surface of the object to be inspected when the light is irradiated to the back surface of the object to be inspected is different from the amount of emitted light (luminance) from the surface without the defect, so that the detection means as the image signal processing section detects the change (the apparent flare) of the amount of emitted light (luminance) based on the change of the amount of emitted light (luminance) in the image captured by the capturing means, thereby detecting the defect of the surface of the object to be inspected (see fig. 9).
However, as shown in fig. 10, the irradiation light amount is smaller in the region of the subject corresponding to the dark portion Pb, in particular, the farther from the bright-dark boundary Pc in the dark portion Pb, and the smaller the irradiation light amount is in the region corresponding to the bright portion Pa, the smaller the amount of light emitted from the surface of the subject. Therefore, in the region of the subject corresponding to the dark portion Pb, the difference between the amount of light emitted (luminance) from the defect S2 and the amount of light emitted (luminance) from the surface without the defect S2 is relatively small, and the change (flare) in the amount of light emitted (luminance) in the image captured as the capturing unit is not noticeable, so that there is a concern that the defect S2 on the surface of the subject cannot be detected (see fig. 10).
However, in one embodiment of the present invention, as shown in fig. 1, the light passing through the light transmitting portion 22 of the light shielding material is diffused toward the light shielding portion 24 by the light diffusing means 23 (23 a) provided in the light shielding material for forming the bright and dark pattern, and more irradiation light (diffused light) La is guided to the region of the subject corresponding to the dark portion Pb, mainly along the bright and dark boundary Pc, and the region to which the irradiation light (diffused light) is guided is expanded in the width direction within the dark portion Pb, as compared with the case where the light diffusing means 23 (23 a) is not provided. Therefore, the amount of light emitted from the region of the surface of the subject corresponding to the dark portion Pb, particularly along the bright-dark boundary Pc, increases, and the difference between the amount of light emitted (luminance) from the defect S in the region corresponding to the dark portion Pb and the amount of light emitted (luminance) from the surface without the defect S relatively increases, so that the defect S that was not apparent as a flare in the image captured by the capturing unit due to the small amount of light emitted (luminance) is also apparent as a flare. Namely, the defect detection accuracy is improved (problem 4 is solved).
In this embodiment of the present invention, since the pattern irradiation unit (the illumination light source and the light-dark pattern forming shade) and the imaging unit are disposed so as to sandwich the light-transmissive resin member, there is little restriction on the position where the equipment constituting the inspection apparatus is disposed (problem 1 is solved).
In this aspect of the present invention, since the pattern irradiation unit, the object to be inspected (light-transmissive resin member), and the imaging unit are disposed so as to face each other, the distortion of the bright and dark pattern formed (appearing) on the surface of the object to be inspected (light-transmissive resin member) is reduced, the bright and dark boundary of the bright and dark pattern becomes clear, and the change (flare) in the amount of emitted light (brightness) at the defect is easily discriminated (the problem of the 2 nd is solved).
In addition, even if the object to be inspected is curved, the entire surface of the object to be inspected can be imaged by the imaging means, so that the area that cannot be inspected is small (problem 3 is solved).
In another aspect, the light-transmitting portion and the light-shielding portion of the light-shielding material for forming a bright-dark pattern may be formed in a band shape having a predetermined width, respectively, a slit pattern in which the bright portion and the dark portion of the band shape are alternately continuous is formed on the surface of the object to be inspected, and the diffused light diffused by the light diffusion means may be guided to a widthwise central portion of the dark portion of the band shape on the surface of the object to be inspected.
The light (diffuse light) transmitted through the light-transmitting portion of the light-shielding material for forming a bright-dark pattern is guided to the widthwise central portion of the strip-shaped dark portion on the surface of the object to be inspected (light-transmitting resin member), whereby the light (diffuse light) transmitted through the light-transmitting portion of the light-shielding material is guided to the widthwise entire region within the dark portion on the surface of the object to be inspected.
That is, since the light (diffuse light) transmitted through the light-transmitting portion of the light-shielding material is guided to a defect at any position in the dark portion of the surface of the object to be inspected, the defect in the entire region in the dark portion of the surface of the object to be inspected can be detected.
In another aspect, the light-blocking material for forming a bright-dark pattern may be configured such that a black ink layer having a predetermined width is formed on a surface of a translucent resin film, the light-blocking portion on which the black ink layer is formed and the translucent portion on which the black ink layer is not formed are alternately continuous, and
the light diffusion unit is provided on a side of the light shielding object where the black ink layer is not formed, the side being a side facing the object to be inspected.
The black ink layer is provided on the opposite side of the light-transmitting resin film to the side on which the light diffusion means is provided, and the black ink layer constituting the light shielding portion does not interfere with the light diffusion action of the light diffusion means.
In another aspect, the light diffusion means may be constituted by a white ink layer having a rectangular cross section, the white ink layer being formed on the surface of the light-transmitting resin film constituting the light-transmitting portion.
Part of the light incident on the light-transmitting resin film is emitted from both end surfaces in the width direction of the white ink layer having a rectangular cross section, and the light emitted from both end surfaces in the width direction of the white ink layer is diffused toward the light shielding portion.
The white ink layer constituting the light diffusion means is formed so as to protrude from the surface of the light-transmitting resin film constituting the light-transmitting portion, and accordingly the diffusion range toward the light-shielding portion side increases.
In another aspect, the surface of the white ink layer having a rectangular cross section may be formed in an arc shape recessed inward, and light emitted from the surface of the white ink layer may be diffused.
Since the light emitted from the surface side of the white ink layer constituting the light transmitting portion also diffuses toward the light shielding portion side, the amount of light of the diffused light that is guided to the surface of the object to be inspected (light transmitting resin member) through the light transmitting portion increases.
In another aspect, the light diffusion means may be made of a pear-shaped material formed on the surface of the light-transmitting resin film.
When the light-transmitting resin film is produced, the pear skin-like material constituting the light diffusing means can be molded, so that the light diffusing means can be easily formed.
In another aspect, the light-shielding material for forming a bright-dark pattern may be configured to be movable in a direction in which the light-transmitting portion and the light-shielding portion are continuous with respect to the illumination light source, and the imaging unit may be configured to image the bright-dark pattern in association with the movement of the light-shielding material while moving the light-shielding material to shift the phase of the bright-dark pattern at a constant interval,
The detection means may measure a change in the amount of emitted light (luminance) in the image by a phase shift method in which a plurality of images captured by the capturing means are combined.
Since the change in the amount of emitted light (luminance) in the image is measured by a phase shift method in which a plurality of images whose phases of the bright and dark patterns are shifted at a constant interval are combined, the defect detection accuracy is certainly high, and defects located at any portion of the surface of the object to be inspected can be detected.
In another aspect, the light-dark pattern forming shade may be configured such that a 1 st shade and a 2 nd shade are integrated in a direction in which the shade moves, the 1 st shade forming a light-dark pattern effective for the visualization of spherical defects such as irregularities, and the 2 nd shade forming a light-dark pattern effective for the visualization of fine defects such as hairs.
(action) in the 1 st inspection using the 1 st shade, spherical defects such as irregularities can be detected, and in the 2 nd inspection using the 2 nd shade, fine defects such as hairs can be detected.
Effects of the invention
As is apparent from the above description, according to the present invention, there is provided an inspection apparatus for inspecting surface defects of a light-transmissive resin member with high degree of freedom in arrangement of inspection equipment and high accuracy.
Drawings
Fig. 1 is a diagram showing an overall configuration of a surface defect inspection apparatus according to embodiment 1.
Fig. 2 is a plan view showing an image of a bright-dark pattern captured by the camera of the surface defect inspection apparatus according to embodiment 1.
Fig. 3 is a diagram showing the luminance distribution of an image of a bright-dark pattern captured by a camera.
Fig. 4 shows luminance distribution of images of bright and dark patterns captured by a camera, fig. 4A, 4B, 4C, and 4D show luminance distribution of each image when a light shielding object is moved to shift the phase of the bright and dark patterns, fig. 4E and 4F are luminance distribution obtained by combining 4 images of fig. 4A to 4D, respectively, fig. 4E shows a case where there is a defect on the surface of an object to be inspected, and fig. 4F shows a case where there is no defect on the surface of the object to be inspected.
Fig. 5 is an enlarged cross-sectional view of a main part of the surface defect inspection apparatus according to embodiment 2.
Fig. 6 is a diagram showing a configuration of a main part of the surface defect inspection apparatus according to embodiment 3.
Fig. 7 is a plan view showing an image of a bright-dark pattern captured by the camera of the surface defect inspection apparatus according to embodiment 3.
Fig. 8 is a diagram showing a configuration of a main part of the surface defect inspection apparatus according to embodiment 4.
Fig. 9 is a diagram illustrating a manner in which defects are made apparent as flare on an image of a bright and dark pattern captured by a camera in the 1 st trial machine of the surface defect inspection apparatus, fig. 9A is a diagram illustrating a manner in which bright and dark patterns having continuous bright and dark portions are formed on the surface of a transparent object to be inspected, and fig. 9B is a plan view illustrating an image of a bright and dark pattern captured by a camera.
Fig. 10 is a diagram illustrating a manner in which defects are not apparent as flare on an image of a bright and dark pattern captured by a camera in the 1 st trial machine of the surface defect inspection apparatus, fig. 10A is a diagram illustrating a manner in which bright and dark patterns having continuous bright and dark portions are formed on the surface of a transparent object to be inspected, and fig. 10B is a plan view illustrating an image of a bright and dark pattern captured by a camera.
Description of the reference numerals
1. 1A, 1B, 1C inspection apparatus
2. Pattern irradiation unit
10. Planar illumination light source
20. 20A, 20B, 20C (20C 1, 20C 2) light shielding material for slit pattern formation
Slit pattern with alternately continuous P bright portions and dark portions
Bright portion of Pa slit pattern
Dark portion of Pb slit pattern
Light and dark boundary of Pc slit pattern
21. Light-transmitting resin film
21a as light diffusion unit
22. Light transmitting part
23. 23A white ink layer as light diffusion unit
23a end face of white ink layer as light diffusion unit
23b arc-shaped surface of white ink layer as light diffusion unit
24. Light shielding part
25. Black ink layer forming light shielding portion
30. Work piece (front cover as the checked body)
S defects carried on the surface of the workpiece
40. Camera as photographing unit for photographing slit pattern through subject to be inspected
50. Image signal processing unit as detection unit for detecting surface defect of workpiece
56. Analysis computer (personal computer) for determining whether or not the surface of the workpiece is defective
Detailed Description
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments are not intended to limit the invention, but rather are exemplary, and all the features and combinations thereof described in the embodiments are not necessarily essential features and combinations of the invention.
(embodiment 1)
Embodiment 1 of an apparatus for detecting surface defects of a front cover (light-transmissive resin member) for an automotive headlamp according to the present invention will be described with reference to fig. 1, 2, 3, and 4.
As shown in fig. 1, the surface defect inspection apparatus 1 includes: a planar illumination light source 10 horizontally arranged; a light-shielding object 20 for forming a bright-dark pattern, which is horizontally disposed at the front (upper) side in the irradiation direction of the planar illumination light source 10; a front cover 30 (hereinafter referred to as a workpiece) as an object to be inspected, disposed above the light shielding material 20; a digital camera 40 as a photographing unit disposed above the work 30; and an image signal processing unit 50 as detection means for detecting a defect on the surface of the workpiece 30 based on the image captured by the digital camera 40.
The planar illumination light source 10 formed to have a predetermined size is constituted by a light source that emits light in a planar shape, such as a Liquid Crystal Display (LCD) or an organic EL light emitting element, and the light emitting surface 10a faces upward in fig. 1.
A light-transmitting portion 22 having a predetermined width and a light-shielding portion 24 having a predetermined width are alternately and continuously formed in the left-right direction of fig. 1 on the light-shielding object 20 for forming a bright-dark pattern, and are movable in the left-right direction of fig. 1 with respect to the planar illumination light source 10. Further, both the light transmitting portion 22 and the light shielding portion 24 are formed with the same width (for example, 10mm width) to a prescribed length larger than the dimension of the workpiece 30 in the longitudinal direction (y direction of fig. 2).
The light-and-dark-pattern-forming shade 20 and the planar illumination light source 10 provided on the back surface side thereof constitute a pattern irradiation unit 2, and the pattern irradiation unit 2 irradiates a light-and-dark pattern (slit pattern) P (see fig. 2) in which light portions Pa and dark portions Pb corresponding to the light-transmitting portions 22 and the light-shielding portions 24 of the shade 20 alternately continue.
The workpiece 30 as an object to be inspected is horizontally arranged above the pattern irradiation unit 2 with its back side facing the pattern irradiation unit 2, and the light and dark pattern (slit pattern) P, which is the irradiation light of the pattern irradiation unit 2, passes through the workpiece 30 to be distributed upward. The distance between the work 30 and the shade 20 is, for example, 100 to 200mm, and the shade 20 can move (slide) with respect to the illumination light source 10, but the distance between the shade 20 and the illumination light source 10 is substantially 0.
Specifically, when the slit pattern P is irradiated onto the back surface of the work 30, the slit pattern P is developed on the front surface side of the transparent work 30. That is, the planar illumination light source 10 and the shade 20 form a slit pattern P on the surface of the workpiece 30, the slit pattern P being continuous between the strip-shaped bright portion Pa corresponding to the light-transmitting portion 22 and the strip-shaped dark portion Pb corresponding to the shade 24.
When the irradiation light irradiated to the back surface side of the workpiece 30 is emitted from the front surface side of the workpiece 30 through the workpiece 30, the amount of emitted light from the surface of the workpiece 30 when the light is irradiated to the back surface of the workpiece 30 is different from the amount of emitted light (brightness) from the surface having no defects such as irregularities and flaws, and therefore the image signal processing section 50 of the built-in analysis computer (personal computer) 56 performs image processing by a phase shift method described later based on the image captured by the digital camera 40, whereby a change in the amount of emitted light (brightness) from the surface of the workpiece 30 can be detected as a defect of the surface of the workpiece 30.
That is, a digital camera 40 that photographs the slit pattern P through the work 30 is arranged above the work 30 such that the digital camera 40 is opposed to the work 30 and the pattern irradiation unit 2.
Further, as shown in fig. 1, the camera 40 adjusts the depth of field so that the focal point (Focus) F of the photographed image is focused in a range from the pattern irradiation unit 2 to the workpiece 30. Further, by capturing the slit pattern P through the work 30, as shown in fig. 2, the clear slit pattern P is displayed superimposed on the image captured by the camera 40 over the entire surface of the clear work 30.
The digital camera 40 is connected to the image signal processing unit 50, and the image signal processing unit 50 detects defects on the surface of the workpiece 30 based on the image captured by the camera 40 and displays the processed image of the surface of the workpiece 30 on the monitor 60 so that the defects can be visually recognized.
The image signal processing unit 50 includes: an a/D converter (analog-to-digital converter) 52 that converts the image signal of the camera 40 generated by the read scan into a digital signal; a RAM (random access memory) 54 for storing digital signals as image data at addresses corresponding to pixels of the camera 40; an analysis computer (personal computer) 56 for capturing and processing the image data from the RAM 54; and a monitor 60 for simulating the image signal or the processing signal by the D/a converter 57 and selectively displaying the same via the switching circuit 58.
That is, the analysis computer (personal computer) 56 reads the image data taken into the RAM54 in the direction orthogonal to the slit (X direction in fig. 2), sequentially compares the image data with the signal levels of the addresses before and after, and determines that a defect exists at the position corresponding to the address when the difference between the compared signal levels (levels) is equal to or greater than a predetermined value.
As shown in fig. 1 and 2, in the light shielding material 20 for slit pattern formation, a black ink layer 25 having a predetermined width is formed on the surface of the translucent resin film 21 on the side of the planar illumination light source 10 by printing, and a band-shaped light shielding portion 24 having the black ink layer 25 and a band-shaped light transmitting portion 22 having no black ink layer 25 are formed in an alternating continuous manner.
Further, a white ink layer 23 having a rectangular cross section, which constitutes a light diffusion means, is formed on the surface of the light-transmissive resin film 21 constituting the light-transmissive portion 22 on the side where the black ink layer 25 is not formed, and light La (see fig. 1) diffused toward the light shielding portion 24 side is formed in such a manner that light emitted from both end surfaces 23a in the width direction of the white ink layer 23 out of light transmitted through the light-transmissive portion 22 toward the back surface of the work 30 is guided in a direction inclined with respect to the end surfaces 23 a. The white ink layer 23 is formed by printing on the light-transmitting resin film 21, similarly to the black ink layer 25, in which the light-diffusing material is dispersed in the white ink layer 23.
The white ink layer 23 constituting the light diffusion means is formed so as to protrude from the surface of the light-transmitting resin film 21, and the light diffusion range toward the light shielding portion 24 increases accordingly.
When the image signal processing unit 50 is capable of detecting a change (flare) in the amount of light emitted (brightness) from the surface of the workpiece 30 based on the image captured by the digital camera 40, the amount of light emitted in the dark portion Pb on the back surface of the workpiece 30 is smaller than the amount of light emitted in the bright portion Pa, and accordingly, the amount of light transmitted in the dark portion Pb on the surface of the workpiece 30 is smaller than the amount of light transmitted in the bright portion Pa, and in particular, the difference between the amount of light emitted (brightness) from the defect and the amount of light emitted (brightness) from the surface without the defect is relatively smaller as the position is away from the bright-dark boundary Pc, and the defect is less noticeable as a flare, so that there is a concern that the detection by the image signal processing unit 50 as a detection means cannot be performed (see fig. 10).
However, in the present embodiment, the light transmitted through the light transmitting portion 22 of the light shielding material 20 is diffused in large amounts toward the light shielding portion 24 by (the end surface 23a of) the white ink layer 23 as the light diffusing means provided on the light shielding material 20, and more irradiation light (diffused light) La is guided into the dark portion Pb on the back surface of the workpiece 30, mainly along the bright-dark boundary Pc in the dark portion Pb, as compared with the case where the white ink layer 23 is not provided (see fig. 10) (see fig. 1). Therefore, the amount of light (luminance) emitted from the region in the dark portion Pb, particularly along the bright-dark boundary Pc, of the surface of the workpiece 30 increases, and the difference between the amount of light (luminance) emitted from the defect S in the dark portion Pb and the amount of light (luminance) emitted from the surface without the defect S becomes relatively large, and the change (flare) in the amount of light (luminance) emitted from the image captured by the camera 40 becomes apparent. That is, as shown in fig. 10, even if the amount of light (brightness) emitted in the dark portion Pb is small, the defect S2 that is apparent as a flare does not exist in the image captured by the camera 40, and the flare is apparent by diffusing light, so that the defect S2 can be detected by the image signal processing portion 50 as the detecting means.
In particular, in embodiment 1, the distance between the work 30 and the white ink layer 23, the thickness of the white ink layer 23, and the like are adjusted, and the diffused light La transmitted through the light transmitting portion 22 is guided to the widthwise central portion of the belt-like dark portion Pb.
Therefore, the light (diffuse light) transmitted through the light-transmitting portion 22 of the light-shielding material 20 is guided to the entire area in the width direction in the dark portion Pb on the surface of the workpiece 30. That is, the diffuse light is guided to the defect S located at any position in the dark portion Pb on the surface of the workpiece 30, and the defect S located in the region corresponding to the dark portion Pb of the image captured by the camera 40 becomes apparent as a flare, so that the defect S in the entire region in the dark portion Pb on the surface of the workpiece 30 can be detected.
The pattern irradiation unit 2 irradiates a slit pattern P in which bright portions Pa and dark portions Pb of a slit width of 10mm are alternately continuous, but displays a slit pattern P (see fig. 2) of a predetermined period in which bright portions Pa and dark portions Pb are alternately continuous on an image captured by the camera 40. As shown in fig. 3, the luminance distribution of the image of the slit pattern P is a sine wave (sin wave) pattern of a predetermined period corresponding to the interval between the bright portion Pa and the dark portion Pb of the slit pattern P.
The light (diffuse light) La transmitted through the light-transmitting portion 22 of the light-shielding material 20 is guided to the region corresponding to the dark portion Pb of the workpiece 30, and accordingly, the amount of emitted light (luminance) from the defect S located in the region corresponding to the dark portion Pb increases. That is, since the light transmitted through the light transmitting portion 22 is guided as the diffused light La to the region corresponding to the dark portion Pb, the amount of light (luminance) b1 emitted from the defect in the case where the light transmitted through the light transmitting portion 22 is not guided as the diffused light to the region corresponding to the dark portion Pb (the test machine shown in fig. 10) increases as shown by a reference symbol b2 (> b 1) in fig. 3, and is apparent as a flare in the image.
Next, image processing by the image signal processing unit 50 using a phase shift method will be described.
In the phase shift method, the phase of a slit pattern P (sine wave pattern) irradiated to the workpiece 30 is shifted at a constant interval (for example, pi/2), the slit pattern P is photographed a plurality of times (4 times or more) by the camera 40, and the photographed image is analyzed, whereby the surface shape of the workpiece 30 is measured.
Specifically, the slit pattern forming shade 20 is moved at a constant speed relative to the camera 40, the workpiece 30, and the planar illumination light source 10 by an amount corresponding to at least one cycle of the slit pattern P (sine wave pattern). Then, the slit pattern P (sine wave pattern) is imaged at every constant interval (pi/2) by the camera 40 with respect to the change in phase of the slit pattern P (sine wave pattern) accompanying the movement of the light shielding object 20 (slit pattern P).
When the amount of shift in the vertical axis direction of the sine wave pattern and the amplitude are A, B, the brightness (luminance) of a certain point p (x, y) of each of all 4 captured images is expressed by the following 4 simultaneous equations:
then, the luminance B at the point p (x, y) is obtained by combining all 4 images, that is, by solving the above 4 simultaneous equations for B by phase operation.
That is, b=sqrt ((I) 1 -I 3 ) 2 +(I 2 -I 4 ) 2 ))/2。
In this way, the image signal processing unit 50 obtains the amplitude B (luminance) of the point p (x, y) on the image by image processing (phase shift method) (see fig. 4E), and determines that a defect exists at the position p (x, y) when the amount of change in the amplitude B (luminance) is equal to or greater than the threshold value.
Fig. 4 shows the luminance distribution (sine wave pattern) of the image of the bright-dark pattern P captured by the camera 40, and fig. 4A to 4D show the luminance distribution of each image when the shade 20 is moved so as to shift the phase of the bright-dark pattern P. Fig. 4E and 4F show luminance distributions obtained by combining the 4 images of fig. 4A to 4D, that is, luminance B at point p (x, y) measured by solving the above 4 simultaneous equations for B by phase operation, respectively, fig. 4E shows a case where there is a defect at point p (x, y), and fig. 4F shows a case where there is no defect at point p (x, y). If a defect exists at the point p (x, y), as shown in fig. 4E, the luminance B corresponding to the defect is amplified by an amount corresponding to the diffused light and becomes apparent as flare, and can be reliably detected by the image signal processing unit 50.
In the present embodiment, since the pattern irradiation unit 2 (the illumination light source 10 and the light shielding material 20 for pattern formation) and the camera 40 are disposed so as to sandwich the work 30, there is little restriction on the positions at which the devices constituting the surface defect inspection apparatus 1 are disposed.
In the present embodiment, since the pattern irradiation unit 2, the work 30, and the camera 40 are disposed so as to face each other, the deformation of the slit pattern P formed (appearing) on the surface of the work 30 is reduced, the bright-dark boundary Pc of the slit pattern P becomes clear, and the change (flare) in the amount of emitted light (brightness) at the defect is easily discriminated.
In the present embodiment, even if the workpiece 30 is curved, the entire surface of the workpiece 30 can be imaged by the camera 40, so that the number of areas that cannot be inspected is small.
In embodiment 1, the phase shift method is adopted in which the phase of the irradiated slit pattern P (sine wave pattern) is shifted by a constant interval (pi/2), the slit pattern P is imaged a plurality of times (4 times or more) by the camera 40, and the imaged image is analyzed, whereby the surface shape of the workpiece 30 is measured, but the phase shift method may be adopted in which the phase of the irradiated slit pattern P (sine wave pattern) is shifted by a constant interval (pi/4), the slit pattern P is imaged a plurality of times (8 times or more) by the camera 40, and the imaged image is analyzed, whereby the surface shape of the workpiece 30 is measured, and the narrower the interval of the phase shift of the irradiated slit pattern P (sine wave pattern) is, the more the number of times the imaged by the camera 40 is, whereby the surface shape of the workpiece 30 can be measured with higher accuracy.
(embodiment 2)
Fig. 5 shows a main part of a surface defect inspection apparatus 1A as embodiment 2 of the present invention.
In the slit pattern forming shade 20A of the surface defect inspection apparatus 1A, similarly to the case of embodiment 1 described above, the white ink layer 23A having a rectangular cross section constituting the light diffusion means is provided in the light transmitting portion 22, but the white ink layer 23A is configured such that the surface side 23b thereof is formed in an arc shape recessed inward, and the light emitted from the surface side of the white ink layer 23A of the light transmitting portion 22 is also diffused toward the light shielding portion 24 side.
That is, not only the diffused light La emitted from the both end surfaces 23A in the width direction of the white ink layer 23A, but also the diffused light Lb emitted from the arcuate surface 23b of the white ink layer 23A is guided into the dark portion Pb of the surface of the workpiece 30.
Therefore, the amount of light emitted from the region mainly along the bright-dark boundary Pc in the dark portion Pb of the surface of the workpiece 30 further increases, and the difference between the amount of light emitted (luminance) from the defect in the dark portion Pb and the amount of light emitted (luminance) from the surface without the defect further increases, and accordingly, the detection accuracy of the defect of the image signal processing section 50 as the detection means further improves.
The other components are the same as those of embodiment 1, and the same reference numerals are given thereto, so that redundant description thereof is omitted.
(embodiment 3)
Fig. 6 shows a configuration of a main part of the surface defect inspection apparatus 1B according to embodiment 3, and fig. 7 shows an image of a bright-dark pattern captured by the camera 40 of the surface defect inspection apparatus 1B according to embodiment 3.
In the surface defect inspection apparatus 1B according to embodiment 3, the slit pattern forming light shielding material 20B is formed with a black ink layer 25 having a predetermined width on the surface of the translucent resin film 21 on the side of the planar illumination light source 10, and is formed with a band-shaped light shielding portion 24 having the black ink layer 25 and a band-shaped light transmitting portion 22 having no black ink layer 25 alternately and continuously, similarly to the light shielding materials 20 and 20A according to embodiments 1 and 2.
The pear-shaped material 21a constituting the light diffusion means is formed on the side of the light-transmitting resin film 21 constituting the light-shielding material 20B where the black ink layer 25 is not formed, and when light La transmitted through the light-transmitting portion 22 and directed to the back surface of the work 30 is emitted from the surface of the light-transmitting portion 22 (the light-transmitting resin film 21) where the pear-shaped material 21a is formed, the light is diffused toward the light-shielding portion 24 side.
Accordingly, the amount of emitted light from the region in the dark portion Pb, particularly along the bright-dark boundary Pc, of the surface of the workpiece 30 increases, and accordingly, the difference between the amount of emitted light (luminance) from the defect s in the dark portion Pb and the amount of emitted light (luminance) from the surface without the defect s further increases, and accordingly, the detection accuracy of the defect of the image signal processing section 50 as the detection means further improves.
Otherwise, the same reference numerals are given to the same parts as those in embodiment 1, and thus overlapping description is omitted.
(embodiment 4)
Fig. 8 shows a structure of a main part of a surface defect inspection apparatus 1C as embodiment 4.
Regarding the slit pattern forming shade 20C of the surface defect inspection apparatus 1C, the 1 st slit pattern forming shade 20C1 and the 2 nd slit pattern forming shade 20C2 are integrated in a direction in which the light transmitting portion 22 and the light shielding portion 24 are continuous (a direction orthogonal to the slit), the 1 st slit pattern forming shade 20C1 is formed as a band-shaped light transmitting portion 22 of 0.5mm width and a band-shaped light shielding portion 24 of 0.5mm width are alternately continuous, and the 2 nd slit pattern forming shade 20C2 is formed as a band-shaped light transmitting portion 22 of 3mm width and a band-shaped light shielding portion 24 of 10 to 20mm width are alternately continuous. The width of the light shielding portion 24 of the light shielding object 20C2 is set to a predetermined value within a range of 10mm to 20 mm.
The 1 st light shielding material 20C1 and the 2 nd light shielding material 20C2 each adopt the structure of embodiment 3. That is, the black ink layer 25 is formed on the light-transmitting resin film 21 to constitute the light-shielding portion 24, and the pear-shaped material 21a as light diffusion means is formed on the side of the light-transmitting resin film 21 where the black ink layer is not formed, and light emitted from the light-transmitting portion 22 is diffused toward the light-shielding portion 24 side.
The slit pattern forming shade 20C is movable in the longitudinal direction (left-right direction in fig. 8), and a 1 st position (see fig. 8) where the 1 st shade 20C1 faces the workpiece 30 and the planar illumination light source 10 and a 2 nd position where the 2 nd shade 20C2 faces the workpiece 30 and the planar illumination light source 10 can be obtained alternatively.
When detecting a defect on the surface of the workpiece 30, the 1 st shade 20C1 having small widths of the bright portion Pa and the dark portion Pb of the slit pattern formed on the surface of the workpiece 30 is used because the dark portion Pb of the image captured by the camera 40 is somewhat bright and easier to detect with respect to a spherical defect such as a concave-convex shape. On the other hand, for a thin defect such as hair, the dark portion Pb of the image captured by the camera 40 is more easily detected over a certain length, and therefore, the 2 nd shade 20C2 having a width larger than that of the bright portion Pa of the dark portion Pb of the slit pattern P formed on the surface of the work 30 is used.
First, in the 1 st inspection step, in the embodiment shown in fig. 8 in which the 1 st light shielding object 20C1 is facing the camera 40, the workpiece 30, and the planar illumination light source 10, the slit pattern P1 (sine wave pattern) is imaged at a constant interval (pi/2) by the camera 40 while moving the slit pattern forming light shielding object 20C at a constant speed relative to the planar illumination light source 10 by an amount corresponding to at least one cycle of the slit pattern P1 (sine wave pattern) formed by the 1 st light shielding object 20C1, with respect to a change in phase of the slit pattern P1 (sine wave pattern) that follows the movement of the light shielding object 20C (slit pattern P1).
Then, the picked-up images are combined, that is, by performing a known image processing (phase shift method), the amplitude B (brightness) of all the points p (x, y) on the image is obtained, and when the amount of change in the amplitude B (brightness) is equal to or greater than the threshold value, it is determined that a defect exists at the position p (x, y).
Next, in the inspection step 2 after the inspection step 1, in a manner that the 2 nd light shielding object 20C is advanced relative to the planar illumination light source 10, the slit pattern forming light shielding object 20C is moved relative to the planar illumination light source 10 by an amount corresponding to at least one cycle of the slit pattern P2 (sine wave pattern) formed by the 2 nd light shielding object 20C2 while the slit pattern P2 (sine wave pattern) is shot at constant intervals (pi/2) by the camera 40 with respect to a change in phase of the slit pattern P2 (sine wave pattern) with the movement of the light shielding object 20C (slit pattern P2), in which the 2 nd light shielding object 20C2 is facing the camera 40, the work 30, and the planar illumination light source 10.
Then, the picked-up images are combined, that is, a known image process (phase shift method) is performed, and the amplitude B (brightness) of all the points p (x, y) on the image is obtained, and when the amount of change in the amplitude B (brightness) is equal to or greater than the threshold value, it is determined that a defect exists at the position p (x, y).
Then, the 1 st inspection step using the slit pattern P1 forming the 1 st light shielding object 20C1 and the 2 nd inspection step using the slit pattern P2 of the 2 nd light shielding object 20C2 are performed, and the "no defect" is determined only when the "no defect" is determined in all the inspection steps, and the "defect" is determined when the "defect" is determined in at least one of the 1 st and 2 nd inspection steps.
In this way, in embodiment 4, both the spherical defect such as the concave-convex shape and the thin defect such as the hair can be reliably detected.
Otherwise, the same reference numerals are given to the same parts as those in embodiment 1, and thus overlapping description is omitted.
In the above-described embodiment, the explanation was made with respect to the case where the subject was a colorless transparent (clear) front cover 30 for a headlight, but the subject is not limited to the colorless transparent (clear), and may be a front cover for a sign lamp such as an amber front cover for a turn signal lamp or a red front cover for a stop lamp, as long as it is a light-transmissive resin member.
Claims (7)
1. A surface defect inspection device for a light-transmitting resin member, characterized in that,
The device is provided with:
a pattern irradiation unit configured by a light-dark pattern forming shade in which a light-transmitting portion and a shade portion are alternately continuous, and an illumination light source provided on the back surface side of the shade, and irradiating a light-dark pattern in which a light portion and a dark portion corresponding to the light-transmitting portion and the shade portion are alternately continuous;
a light-transmitting resin member as an object to be inspected, the light-transmitting resin member being disposed with its back surface side facing the pattern irradiation unit;
an imaging unit configured to face the pattern irradiation unit through the subject, and to image the bright and dark pattern through the subject; a kind of electronic device with high-pressure air-conditioning system
A detection unit as an image signal processing unit for detecting a defect on the surface of the object based on a change in brightness, which is an amount of outgoing light, in the image captured by the imaging unit,
a light diffusion means for diffusing the light transmitted through the light transmitting portion toward the light shielding portion is provided on the light shielding material for forming the bright and dark pattern,
the light-transmitting portion and the light-shielding portion of the light-shielding material for forming a bright-dark pattern are formed in a band shape having a predetermined width, respectively, a slit pattern is formed on the surface of the object to be inspected, in which the bright portion and the dark portion are alternately continuous, and the diffused light diffused by the light diffusion means is guided to the widthwise central portion of the dark portion of the surface of the object to be inspected.
2. The apparatus for inspecting surface defects of a light-transmitting resin member according to claim 1, wherein,
the light-shielding material for forming bright and dark patterns is formed with a black ink layer of a prescribed width on the surface of a light-transmitting resin film, the light-shielding portion formed with the black ink layer and the light-transmitting portion not formed with the black ink layer are alternately continuous, and
the light diffusion unit is provided on a side of the light shielding object where the black ink layer is not formed, the side being a side facing the object to be inspected.
3. The apparatus for inspecting surface defects of a light-transmitting resin member according to claim 2, wherein,
the light diffusion unit is composed of a white ink layer having a rectangular cross section, which is formed on the surface of the light-transmitting resin film constituting the light-transmitting portion.
4. The apparatus for inspecting surface defects of a light-transmitting resin member according to claim 3,
the surface defect inspection device is configured such that a rectangular surface of the white ink layer is formed in an arc shape recessed inward, thereby diffusing light emitted from the surface of the white ink layer.
5. The apparatus for inspecting surface defects of a light-transmitting resin member according to claim 2, wherein,
The light diffusion means is formed of a pear-shaped material formed on the surface of the light-transmitting resin film.
6. The apparatus for inspecting surface defects of a light-transmitting resin member according to claim 1, wherein,
the light-shielding object for forming the bright-dark pattern is configured to be movable relative to the illumination light source in a direction in which the light-transmitting portion and the light-shielding portion are continuous, and the imaging unit is configured to image the bright-dark pattern in association with the movement of the light-shielding object while moving the light-shielding object to shift the phase of the bright-dark pattern at a constant interval,
the detection means measures a change in the amount of emitted light, that is, the brightness, in the image by using a phase shift method in which a plurality of images captured by the capturing means are combined.
7. The apparatus for inspecting surface defects of a light-transmitting resin member according to claim 6, wherein,
the light-dark pattern forming light-shielding material is configured such that a 1 st light-shielding material and a 2 nd light-shielding material are integrated in the direction in which the light-shielding material moves, the 1 st light-shielding material forming a light-dark pattern effective for the visualization of spherical defects such as irregularities, and the 2 nd light-shielding material forming a light-dark pattern effective for the visualization of thin defects such as hairs.
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| JP2018226965A JP2020091132A (en) | 2018-12-04 | 2018-12-04 | Surface defect inspection device of translucent member |
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| JP2020091132A (en) | 2020-06-11 |
| CN111272762A (en) | 2020-06-12 |
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