CN116465904A

CN116465904A - Appearance inspection device

Info

Publication number: CN116465904A
Application number: CN202211704543.2A
Authority: CN
Inventors: 铃木孝通; 樋野贵仁
Original assignee: Humo Laboratory Ltd
Current assignee: Humo Laboratory Ltd
Priority date: 2022-01-20
Filing date: 2022-12-28
Publication date: 2023-07-21
Also published as: JP2023106244A

Abstract

The appearance inspection device (1) is provided with: a base (10) on which an object (90) to be inspected having a convex curved mirror surface (91) on a reference axis (80) is disposed; an illumination device (20) for radiating illumination light having a changeable predetermined pattern in a direction along a reference axis (80); a reflection surface (32) inclined with respect to the reference axis (80) is provided so as to surround the space around the reference axis (80), and a whole-circle mirror (30) which reflects the illumination light emitted from the illumination device (20) and passing through the periphery of the object (90) to be inspected toward the convex curved mirror surface (91) is provided by the reflection surface (32); an imaging device (40) that images the direction of the convex curved mirror surface (91) through the space around the reference axis (80) of the full-circle mirror (30); an information processing device (50) for performing analysis on the surface of the convex curved mirror surface (91) based on a pattern including illumination light having a pattern reflected by the convex curved mirror surface (91) included in an image obtained by the image pickup device (40).

Description

Appearance inspection device

Technical Field

The present invention relates to an appearance inspection device.

Background

As a method of inspecting the appearance of an object to be inspected, the following method is known: the object to be inspected, which is irradiated with light, is photographed by an imaging device, and the obtained image is subjected to a predetermined image processing, thereby inspecting the surface of the object to be inspected for defects such as damage. In this method, when the object to be inspected has a defect, the light irradiated to the object to be inspected is diffusely reflected at the defective portion, and thus such a change as an increase or decrease in the amount of light incident on the imaging device can be seen with respect to the defective portion. By detecting such a change in image processing, determination of defects can be made. On the other hand, when the object to be inspected is a mirror surface, the environment other than the illumination light is reflected on the object to be inspected or the reflected light intensity of the irradiated light and the diffuse reflection of the defective portion is canceled by the reflected light, and it is generally difficult to detect the defective portion by the same method.

As an appearance inspection method for a mirror surface of an object to be inspected, for example, as disclosed in japanese patent application laid-open No. 2017-15647, a method of projecting a stripe-shaped bright-dark pattern on a mirror surface to obtain an image thereof is known. In this method, when there is a defect such as a flaw, the bright-dark pattern in the stripe shape is deformed in the portion, and therefore, a defective portion is easily detected based on the image. In the case of using such a method, it is known that a projection method, an imaging method, and the like of a pattern need to be appropriately set according to the shape and the like of an object to be inspected.

Disclosure of Invention

The object of the present invention is to easily and accurately perform an appearance inspection of an object having a convex curved mirror surface.

According to one aspect of the present invention, an appearance inspection device includes: a base configured to be disposed on an object to be inspected having a convex curved mirror surface on a reference axis; an illumination device configured to be disposed on a side of the convex curved mirror surface opposite to the convex side, the illumination device including an electronic display configured to radiate illumination light having a changeable predetermined pattern in a direction along the reference axis; a full-circle mirror configured to be disposed on a side opposite to the illumination device with respect to the base, the full-circle mirror being provided with a reflection surface inclined with respect to the reference axis so as to surround a space around the reference axis, the reflection surface being configured to specularly reflect the illumination light emitted from the illumination device and passing through the periphery of the object to be inspected toward the convex curved surface; an imaging device configured to be disposed on the opposite side of the base with respect to the full-circle mirror, and to take an image of the direction of the convex curved mirror surface via a space around the reference axis of the full-circle mirror; and an information processing device that analyzes a surface of the convex curved mirror surface based on a pattern of the illumination light including the pattern, which is included in the image obtained by the image pickup device, and which is reflected by the convex curved mirror surface.

According to the present invention, it is possible to easily and accurately perform an appearance inspection of an object having a convex curved mirror surface.

Drawings

Fig. 1 is a diagram schematically showing an outline of a configuration example of an appearance inspection device according to an embodiment.

Fig. 2 is a diagram showing the shape of the subject used in the embodiment.

Fig. 3 is a diagram showing an example of a bright-dark pattern appearing on a liquid crystal panel in the embodiment.

Fig. 4 is an example of an image obtained by photographing with the imaging device in the embodiment.

Fig. 5 is an example of an output image when the image shown in fig. 4 is input to the learning completion model.

Detailed Description

An embodiment of the appearance inspection device will be described with reference to the drawings. The appearance inspection device according to the present embodiment is a device for inspecting an object to be inspected having a convex curved mirror surface, and particularly, a device for inspecting whether or not a flaw such as a scratch exists in the convex curved mirror surface. The convex curved surface may include various curved surfaces protruding outward. The convex curved surface may be, for example, a curved surface including a part of an outer surface of a sphere, an ellipsoid, or the like.

[ Structure of appearance inspection device ]

Fig. 1 schematically shows an outline of a configuration example of an appearance inspection device 1 according to the present embodiment. As shown in fig. 1, the appearance inspection device 1 includes a base 10, an illumination device 20, a full-circle mirror 30, an imaging device 40, and an information processing device 50. In fig. 1, an object to be inspected 90 is shown in which a hemispherical convex mirror 91 is provided on the upper portion of a cylinder.

The base 10 is a structure in which the subject 90 is disposed. In this example, the placement surface 12 of the base 10 is horizontally disposed. A reference shaft 80 is vertically provided in the center of the base 10. In this example, the visual inspection apparatus 1 is configured such that the object to be inspected 90 is placed on the placement surface 12 of the base 10 such that the central axis of the cylinder coincides with the reference axis 80. A transparent portion 14 through which illumination light described later is transmitted is provided in the center portion of the base 10. The transparent portion 14 is formed of, for example, a glass plate. The base 10 may be formed of, for example, a glass plate only in the transparent portion 14 at the central portion, or the entire base 10 may be formed of a glass plate.

The structure of the base 10 shown here is an example, and the base may have other structures as long as the object 90 having the convex mirror surface 91 is disposed on the reference axis 80. For example, the base may be provided with a jig for fixing the subject 90. When the base holds the object 90 so that the central axis of the cylindrical body of the object 90 becomes horizontal, the reference axis 80 becomes horizontal, and other parts described below are also arranged in a manner that corresponds to this. The base may have any structure as long as illumination light described later can pass around the object to be inspected 90.

The illumination device 20 is disposed below the base 10. That is, the illumination device 20 is disposed on the opposite side of the convex curved mirror 91. The lighting device 20 includes a liquid crystal panel 22 and a backlight 24. The liquid crystal panel 22 is disposed on the base 10 side of the backlight 24. The liquid crystal panel 22 has a plurality of pixels, and is configured to switch between at least a substantially light-transmitting state and a non-transmitting state for each pixel. Light emitted from the backlight 24 is irradiated in the direction of the base 10 through the liquid crystal panel 22. The illumination device 20 is configured such that the projection optical axis of the illumination device 20 coincides with the reference axis 80. The illumination light irradiates a sufficiently wide area so as to pass through the periphery of the object 90.

The liquid crystal panel 22 is patterned, and the illumination light emitted from the backlight 24 and transmitted through the liquid crystal panel 22 is illumination light having a pattern including bright portions and dark portions. The pattern is, for example, a striped pattern in which light portions and dark portions are alternately repeated. The pattern may be, for example, a pattern in which light portions and dark portions extending radially around the reference axis 80 are alternately repeated in the circumferential direction. The pattern may be, for example, a pattern in which concentric bright portions and dark portions centered on the reference axis 80 are alternately repeated in the radial direction. A plurality of patterns having different widths and numbers of light portions and dark portions can be prepared.

The configuration of the illumination device 20 shown here is an example, and the illumination device includes various electronic displays, and may have other configurations as long as the illumination light including a changeable predetermined pattern is emitted so as to travel along the reference axis 80. For example, the illumination device 20 may include an electronic display such as an organic EL display. Here, the direction along the reference axis 80 may be any direction along the reference axis 80 as long as the irradiation direction of the illumination light is along the reference axis 80, and the illumination light does not need to be parallel light, and does not need to have an optical axis coincident with the light axis, or the like.

The entire periphery mirror 30 is provided on the opposite side of the illumination device 20 from the base 10, that is, above the base 10. The entire circumference mirror 30 has a reflecting surface 32 in the shape of the inner surface of a truncated cone. The entire peripheral mirror 30 has a partially open shape corresponding to the upper and lower bottom surfaces of the truncated cone. Here, the entire circumference reflecting mirror 30 is provided such that the bottom surface of the truncated cone faces the direction of the base 10 so that the central axis of the truncated cone coincides with the reference axis 80. That is, the reflection surface 32 is inclined with respect to the reference axis 80, and is provided so as to surround the space around the reference axis 80. The reflecting surface 32 is provided so as to surround the convex curved mirror surface 91 of the object to be inspected 90. The total-circumference mirror 30 is configured to reflect illumination light, which is irradiated from the illumination device 20, transmitted through the transparent portion 14 of the base 10 and passes through the periphery of the object 90 to be inspected, toward the convex curved mirror surface 91 of the object 90 to be inspected through the reflection surface 32.

The imaging device 40 includes a photographing lens and an image area sensor. The imaging device 40 is disposed above the full-circle mirror 30, that is, on the opposite side of the full-circle mirror 30 from the base 10. The imaging device 40 is configured to capture an image of the convex curved mirror surface 91 side of the object 90 via the upper and lower bottom surfaces of the open truncated cone of the full-circle mirror 30, that is, via the space around the reference axis 80 in the full-circle mirror 30. In the case where the convex curved mirror surface 91 of the object to be inspected 90 has a symmetrical shape with respect to the reference axis 80, it is particularly preferable that the imaging device 40 is arranged such that the imaging optical axis thereof coincides with the reference axis 80. The image pickup device 40 is configured to transmit image information obtained by shooting to the information processing device 50.

The information processing apparatus 50 includes a computer having various integrated circuits. The information processing device 50 operates in accordance with a program recorded in a recording device or the like. The information processing device 50 controls the operation of the illumination device 20. The information processing device 50 records information of a plurality of patterns of illumination light emitted from the illumination device 20, that is, a plurality of patterns displayed on the liquid crystal panel 22. The information processing device 50 controls the operation of the lighting device 20 using the information of the recorded pattern. The information processing device 50 controls the presentation of the pattern based on the liquid crystal panel 22. The information processing device 50 controls the amount of light emitted from the backlight 24. The information processing device 50 controls the operation of the imaging device 40. The information processing device 50 controls imaging conditions, imaging timing, and the like based on exposure, focal length, and the like of the imaging device 40.

The information processing device 50 also analyzes the subject 90 based on the image information acquired from the imaging device 40. In particular, the information processing device 50 analyzes the surface of the convex curved mirror 91 based on the pattern reflected by the convex curved mirror 91 of the illumination light including the pattern included in the image obtained by the image pickup device 40. The information processing apparatus 50 includes, for example, a program for analysis such as determination of pass or fail of the object 90, detection of a defective portion, and the like. Artificial intelligence may also be used in this parsing. For example, the information processing apparatus 50 may be provided with a learning completion model that is constructed in advance by machine learning using, for example, an image of a good as teacher data by a method such as an error back propagation method. The information processing apparatus 50 can determine whether or not the subject 90 is acceptable or unacceptable, that is, whether or not there is a defect, based on the image information acquired from the imaging apparatus 40, using the learning completion model.

[ operation of appearance inspection device ]

The operation of the appearance inspection device 1 will be described. The information processing device 50 controls the operation of the illumination device 20, and causes the illumination device 20 to emit illumination light. More specifically, under the control of the information processing apparatus 50, the liquid crystal panel 22 exhibits a pattern in which, for example, bright portions and dark portions are alternately repeated. The backlight 24 emits light in the direction of the liquid crystal panel 22 under the control of the information processing device 50. Light emitted from the backlight 24 passes through the liquid crystal panel 22, and becomes illumination light including a pattern exhibited by the liquid crystal panel 22. The illumination light passes through the transparent portion 14 of the base 10, passes around the object to be inspected 90, and reaches the reflection surface 32 of the entire circumference mirror 30. The reflecting surface 32 reflects the illumination light toward the convex curved mirror 91 of the object to be inspected 90. As a result, the pattern presented by the liquid crystal panel 22 is projected onto the convex curved mirror surface 91 of the object to be inspected 90 as a projection surface.

The imaging device 40 photographs a portion of the object 90 on which the pattern is projected, particularly, a convex curved mirror 91 under the control of the information processing device 50. The image pickup device 40 transmits the image information obtained by the photographing to the information processing device 50. The information processing device 50 determines whether or not there is a defect or the like associated with the convex mirror surface 91 of the object 90 based on the image information acquired from the imaging device 40.

In the inspection of one subject 90, analysis may be performed based on one image obtained by one image or may be performed based on a plurality of images. That is, a plurality of patterns may be projected onto the subject 90 to obtain a plurality of images, and analysis may be performed based on the plurality of images. For example, the finer the lines of the bright and dark fringe pattern (the narrower the space), the higher the resolution can be obtained, but the line width of the projection pattern which is easily detected may be different depending on the size of the damage or the like. Therefore, analysis can be performed using a plurality of patterns having different line widths. In addition, when there is a damage or the like so as to traverse the bright portion and the dark portion, the damage or the like is easily detected, but if the damage or the like is present in the bright portion or the dark portion, for example, the damage or the like may not be detected. Therefore, such damage or the like can be detected by moving the bright and dark pattern. Such damage can be detected by changing the pattern like a radial stripe pattern or a concentric stripe pattern.

Examples (example)

An embodiment of the appearance inspection device 1 will be described. Fig. 2 is a diagram showing the shape of the object to be inspected 90 used in the present embodiment. The object to be inspected 90 has a shape in which a convex curved mirror surface 91 is provided on a cylindrical portion 92. The top 93 of the convex mirror 91 is horizontally cut, and a hole 94 is provided along the central axis in the center. Such an object to be inspected 90 is placed on the placement surface 12 of the base 10 of the visual inspection apparatus 1 so that its center axis coincides with the reference axis 80.

Fig. 3 shows a pattern of light and dark appearing on the liquid crystal panel 22. As shown in the figure, in the present embodiment, a pattern is used in which light portions and dark portions extending radially around the reference axis 80 are alternately repeated in the circumferential direction.

Fig. 4 is an example of an image obtained by imaging by the imaging device 40. A pattern in which bright portions and dark portions extending radially around the center axis of the object 90 alternately repeat in the circumferential direction is projected on the peripheral edge portion of the convex curved mirror surface 91 of the object 90. In the resulting image, the reflection pattern of the pattern can be seen.

A learning completion model is generated by mechanical learning using an image of a conforming product as teacher data in advance using an error back propagation method. The information processing device 50 inputs the image acquired by the imaging device 40 into the learning completion model. Fig. 5 is an example of an output image when the image shown in fig. 4 is input to the learning completion model. As can be seen from fig. 5, the white portion 82 has a defect. As can be seen from an examination of fig. 4, the bright and dark fringe pattern is disturbed in this portion 81.

As described above, it is apparent that by using the appearance inspection device 1 of the present embodiment, it is possible to detect a defect of the convex curved mirror surface 91, and to determine whether the convex curved mirror surface 91 is a good or a bad.

[ about an appearance inspection device ]

In the appearance inspection device 1 of the above embodiment, a bright and dark fringe pattern is projected when inspecting the convex curved mirror surface 91. When an image of a mirror surface is obtained by photographing, it is generally difficult to determine a fine surface shape from the image, but by projecting a pattern of a fringe pattern and photographing a reflection pattern thereof, it is easy to determine a fine surface shape of the mirror surface.

There are various methods of projecting a pattern onto the object 90. For example, a method in which a transmissive film printed with a stripe pattern is formed in a cylindrical shape and is disposed around the object 90 to be inspected, and light is projected from the outside, and the like can be considered. In contrast, in the inspection of the convex curved mirror 91 as the object of the present embodiment, it was found that the pattern was projected more clearly by projecting the fringe pattern from above the object to be inspected 90.

In addition, when printing a pattern on a transmissive film, there are restrictions on line width in accordance with printing technology, or a plurality of transmissive films need to be prepared and replaced in order to project while changing various patterns, or a moving mechanism that physically moves the transmissive film in order to move the patterns is required. For example, if the bright-dark pattern is constant, the size, position, and the like of the damage or the like that can be detected may be limited. In addition, it is necessary to prepare different transmissive films according to the subject to be inspected. In contrast, by forming the pattern of the illumination light using the liquid crystal panel 22, various patterns can be formed relatively easily, and it is easy to change or move the pattern, and it is also possible to shorten the inspection time.

The illumination device 20 may be a self-luminous panel such as an organic EL display. However, in an organic EL display or the like, it is difficult to obtain sufficient luminance. In contrast, as in the present embodiment, by configuring the illumination device 20 with the liquid crystal panel 22 and the backlight 24, it is easy to use a high-luminance light source for the backlight 24. As a result, a sufficient amount of light can be easily obtained. Therefore, the use of the liquid crystal panel 22 and the backlight 24 is a preferred embodiment.

When it is necessary to project the illumination light formed by using the planar liquid crystal panel 22 onto the convex curved mirror surface 91 of the object 90 from above, it has been found that this object can be satisfactorily achieved by disposing the illumination device 20 and the entire peripheral mirror 30 having the reflecting surface 32 in the shape of the truncated cone inner surface so as to face each other with the object 90 interposed therebetween.

In the analysis of the image, it was found that the deformation of the pattern due to damage or the like can be detected with high accuracy by using a learning completion model created by machine learning.

While the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above embodiments, and various modifications and implementations are possible within the scope of the present invention.

Claims

1. An appearance inspection device, wherein,

the appearance inspection device comprises:

a base configured to be disposed on an object to be inspected having a convex curved mirror surface on a reference axis;

an illumination device configured to be disposed on a side of the convex curved mirror surface opposite to the convex side, the illumination device including an electronic display configured to radiate illumination light having a changeable predetermined pattern in a direction along the reference axis;

a full-circle mirror configured to be disposed on a side opposite to the illumination device with respect to the base, to be provided with a reflection surface inclined with respect to the reference axis so as to surround a space around the reference axis, and to specularly reflect the illumination light emitted from the illumination device and passing through the periphery of the object to be inspected toward the convex curved surface through the reflection surface;

an imaging device configured to be disposed on the opposite side of the base with respect to the full-circle mirror, and to capture an image of the convex curved mirror surface direction through a space around the reference axis of the full-circle mirror; and

and an information processing device that analyzes a surface of the convex curved mirror surface based on a pattern of the illumination light including the pattern, which is included in the image obtained by the image pickup device, and which is reflected by the convex curved mirror surface.

2. The visual inspection apparatus according to claim 1, wherein,

the illumination device is configured to have a liquid crystal panel and a backlight, and light emitted from the backlight passes through the liquid crystal panel to emit illumination light including the pattern.

3. The visual inspection apparatus according to claim 1 or 2, wherein,

the base has a transparent portion configured to mount the subject to be inspected,

the light emitted from the illumination device is configured to pass through the transparent portion and reach the full-circle mirror.

4. The visual inspection apparatus according to claim 1 or 2, wherein,

the pattern includes a pattern in which light portions and dark portions extending radially around the reference axis are alternately repeated in a circumferential direction, or,

the pattern includes a pattern in which light portions and dark portions, which are concentric circles around the reference axis, are alternately repeated in a radial direction.

5. The visual inspection apparatus according to claim 1 or 2, wherein,

the information processing device is configured to determine whether the subject is acceptable or unacceptable using a learning completion model created by an error back propagation method using an image of the acceptable as teacher data.