JP2001165864A - Surface inspection device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface inspection device capable of certainly detecting a scratch without being influenced by a diffusion direction of a light transmitting the scratch portion. SOLUTION: A licenser camera 17 photographs a line-like portion 10a to be inspected extending to a width direction of a band-like transparent sheet 10. Light sources 25, 26 and a bar-like light source 16 are disposed at the outside of a photographing range of the licenser camera 17 and illuminate the portion 10a to be inspected from a back surface side of the sheet 10. The light sources 25, 26 obliquely illuminate the portion 10a to be inspected from a width direction of the sheet 10. The bar-like light source 16 obliquely illuminates the portion 10a to be inspected from a downstream side of a traveling direction of the sheet 10. In an image by the licenser camera 17, a brightness of the scratch portion for strongly diffusing a transmitted light to the inside of a surface approximately perpendicular to a longitudinal direction of the sheet 10 becomes larger by an illumination light from the light sources 25, 26. A brightness of the scratch portion for strongly diffusing a transmitted light to the inside of a wide angle range of a traveling direction of the sheet 10 becomes large by the illumination light from the bar-like light source 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a surface inspection apparatus and method for inspecting the presence or absence of a linear scratch present on the front or back surface of a transparent sheet and having a constant longitudinal direction.

[0002]

2. Description of the Related Art In order to detect a defect existing on the surface of a continuously running transparent sheet, Japanese Patent Publication No. 57-3702 is disclosed.
No. 3 and a surface inspection apparatus known in Japanese Patent Application Laid-Open No. 8-285790 are used. Japanese Patent Publication No. 57-37023
As shown in FIG. 5, the surface inspection apparatus disclosed in
1, a light receiver 12, and a signal processing circuit 13.
The strip-shaped transparent sheet 10 runs between the light projector 11 and the light receiver 12 at a constant speed in the direction of the arrow in the figure. Floodlight 1
1 scans the spot light emitted from the laser oscillator 14 in the width direction of the sheet 10 by the rotating polygon mirror 15 rotating at high speed. The light receiver 12 photoelectrically detects the light transmitted through the portion to be inspected 10 a of the sheet 10 and sends a photoelectric conversion signal proportional to the intensity to the signal processing circuit 13. The surface inspection device 5 evaluates the presence or absence of a defect based on a change in the intensity of the transmitted light detected by the light receiver 12.

As shown in FIG. 6, a surface inspection apparatus disclosed in Japanese Patent Application Laid-Open No. 8-285790 has a rod-shaped light source 16, a line sensor camera 17 as an image sensor, and an image processing apparatus 18.
It has. As the rod-shaped light source 16, a light source longer than the width of the sheet 10 is used.
Illuminate from the side different from the surface to be inspected. The line sensor camera 17 captures an image of the linear inspected portion 10 a illuminated by the rod-shaped light source 16 and sends image data to the image processing device 18. As shown in FIG. 7B, the rod-shaped light source 1
Reference numeral 6 is arranged at a position shifted in the traveling direction of the seat 10 from a position facing the line sensor camera 17 with the inspected portion 10a interposed therebetween so that the illumination light does not directly enter the line sensor camera 17. The illumination light from the rod-shaped light source 16 is obliquely incident on the inspected portion 10a from the downstream side or the upstream side in the traveling direction of the sheet 10. The surface inspection device 6 evaluates the presence or absence of a defect based on the brightness data of the image obtained by the line sensor camera 17.

Each of the above surface inspection apparatuses utilizes the fact that light is scattered differently between a normal portion and a defective portion, and detects a defective portion based on the luminance or brightness of transmitted light. For example, when evaluating the presence or absence of a flaw on a sheet, it is determined that a flaw exists when the luminance or brightness of the transmitted light is equal to or higher than a specified level.

[0005] A linear scratch formed by rubbing the surface of the sheet in a certain direction diffuses transmitted light in various directions.
The diffusion direction of the transmitted diffused light varies depending on the mode of the abrasion, such as the depth of the abrasion, the shape of the edge portion, or the direction of the abrasion in the thickness direction of the sheet. Specifically, when there is a strong directivity such that most of the diffused light is included in a plane substantially perpendicular to the longitudinal direction of the abrasion, or includes a plane substantially perpendicular to the longitudinal direction of the abrasion, In some cases, the light beam does not have such a directivity as to diffuse the light beam within a certain angle range in the longitudinal direction.

When the above-mentioned surface inspection device 6 inspects for the presence or absence of a linear scratch generated in a direction substantially parallel to the running direction of the sheet, as shown in FIG. In the case where the transmitted light is not diffused so much in a plane that is substantially orthogonal (FIG. 7A), but the transmitted light is diffused in a wide angle range in the longitudinal direction (FIG. 7B). , A sufficient amount of transmitted and diffused light is
7, the abrasion 20 is easily detected.
On the other hand, as shown in FIG. 8, the abrasion 21 contains most of the diffused light in a plane substantially perpendicular to the longitudinal direction (FIG. 8A), and diffuses little transmitted light in the longitudinal direction. If not performed (FIG. 8B), the transmitted scratches are not so much incident on the line sensor camera 17, so that the abrasions 21 may not be detected.

When the surface inspection device 5 shown in FIG. 5 inspects the presence or absence of a linear scratch generated in a direction substantially parallel to the running direction of the sheet, the surface inspection device 5 is orthogonal to the scanning direction of the spot light. Scratches that diffuse transmitted light in the plane are easily detected, but scratches that diffuse transmitted light in the same direction as the spot light scanning direction are hard to detect.

[0008]

As described above, in the conventional surface inspection devices 5 and 6, depending on the mode of the abrasion, there may be little difference in brightness and luminance between the normal part and the abrasion part. Could not be accurately determined.

The present invention has been made in view of the above circumstances, and provides a surface inspection apparatus and method capable of reliably detecting a scratch without being affected by the diffusion direction of light transmitted through the scratch. Aim.

[0010]

In order to achieve the above object, a surface inspection apparatus of the present invention is an apparatus for inspecting the presence or absence of a linear scratch having a constant longitudinal direction. The illuminating means is arranged substantially orthogonal to the plane including the imaging means and outside the imaging range of the imaging means, and illuminates the inspected portion from an oblique direction.

According to a second aspect of the present invention, in the surface inspection apparatus, the sheet is a belt-shaped sheet in which the sheet runs continuously, and a line sensor for capturing an image of a linear inspection portion extending in the width direction of the belt-shaped sheet is used as the imaging means. Things.

According to a third aspect of the present invention, in the surface inspection apparatus, a bar-shaped second illuminating means extending in parallel with the linear inspection portion is arranged on the back side of the belt-shaped sheet and outside the imaging range of the imaging means. In addition, illumination is performed on the inspected portion from an oblique direction with respect to the traveling direction of the belt-shaped sheet.

Further, the surface inspection method of the present invention is a method for inspecting the presence or absence of a linear abrasion having a constant longitudinal direction, which is substantially perpendicular to the longitudinal direction of the abrasion and includes an imaging means. And illuminates the portion to be inspected from an oblique direction outside the imaging range of the imaging means. According to a fifth aspect of the present invention, there is provided a surface inspection method, wherein the sheet is a belt-shaped sheet in which the sheet continuously travels, and the imaging means captures an image of a linear inspected portion extending in the width direction of the belt-shaped sheet. The inspection unit is illuminated with the second illumination light from the back side of the belt-shaped sheet, outside the imaging range of the imaging unit, and obliquely with respect to the running direction of the belt-shaped sheet.

[0014]

FIG. 1 shows the configuration of a surface inspection apparatus according to the present invention. In the drawings, the same members as those of the surface inspection devices 5 and 6 shown in FIGS. 5 and 6 are denoted by the same reference numerals. The surface inspection device 7 is an inspection device that inspects for the presence or absence of scratches on the strip-shaped transparent sheet 10,
The inspection device is effective for detecting a linear scratch generated in a direction substantially parallel to the running direction of the seat 10. The surface inspection device 7 includes light sources 25 and 26, a rod-like light source 16, a line sensor camera 17 as an image sensor, and an image processing device 18.
It has. The belt-like sheet 10 travels between the light sources 25 and 26 and the rod-like light source 16 and the line sensor camera 17 at a constant speed in the direction of the arrow in the figure. The light sources 25 and 26 and the bar-shaped light source 16 illuminate the line-shaped inspection portion 10a extending in the width direction of the sheet 10 from the back side. The line sensor camera 17 captures an image of the inspection target 10 a illuminated by the light sources 25, 26, 16 from the front side, and sends image data to the image processing device 18.

As the light sources 25 and 26, for example, those obtained by attaching a light guide to a halogen lamp are used.
As shown in FIG. 2A, the light sources 25 and 26
0 in a plane substantially orthogonal to the traveling direction and including the line sensor camera 17,
Is located outside the imaging range of the
a is illuminated from an oblique direction. The rod-shaped light source 16 is a sheet 1
A length longer than the width of 0 is used. As shown in FIG. 2B, the rod-shaped light source 16 is configured so that the illumination light does not directly enter the line sensor camera 17.
The position to be inspected 10a is obliquely illuminated from the downstream side or the upstream side of the sheet 10 in the running direction of the sheet 10 so as to be displaced in the running direction of the sheet 10 from the position facing the line sensor camera 17 across the line 0a. In the present embodiment, the rod-shaped light source 16
Are arranged so as to illuminate the inspected portion 10a obliquely from the downstream side in the traveling direction of the sheet 10.

The illumination light emitted from the light sources 25, 26, and 16 passes through the inspected portion 10a. At this time, each light source 2
The illumination light from 5, 26, 16 is a line sensor camera 17
, The image obtained by the line sensor camera 17 is a dark part in a normal part on the inspected part 10a. On the other hand, when the abrasion is present on the inspected portion 10a, the illumination light emitted from the light sources 25, 26, and 16 is diffused when passing through the abrasion.

Here, as shown in FIG.
a, on the surface substantially perpendicular to the traveling direction of the sheet 10, there is a scratch 30 that does not diffuse much transmitted light but diffuses a large amount of transmitted light within a wide angle range of the traveling direction. Is a light source 25 as shown in FIG.
The light emitted from the sheet and transmitted through the 30 abrasions is
Since the light is not diffused much in the width direction of 0, the amount of light incident on the line sensor camera 17 is reduced. Therefore, in the image obtained by the line sensor camera 17, the brightness at the abrasion 30 does not become bright due to the illumination light from the light source 25, but remains as a dark portion. Further, for the same reason, the brightness of the abrasion 30 does not become bright even by the illumination light from the light source 26.

On the other hand, the light radiated from the rod-shaped light source 16 and transmitted through the abrasion 30 is not diffused much in the width direction of the sheet 10 like the transmitted light of the abrasion 20 shown in FIG. Since the light is diffused in a wide angle range with respect to the traveling direction, the transmitted diffused light enters the line sensor camera 17. Therefore, the brightness of the image from the line sensor camera 17 at the abrasion 30 is increased by the illumination light from the rod-shaped light source 16, and the brightness difference from the normal portion is increased.

As shown in FIG. 4, on the part to be inspected 10a,
If there is an abrasion 31 that diffuses transmitted light strongly in a plane substantially perpendicular to the longitudinal direction of the sheet 10 and does not diffuse much in the longitudinal direction of the sheet 10, the abrasion 31 radiated from the light source 25 reduces the abrasion 31. The transmitted light is diffused widely in the width direction of the sheet 10 and enters the line sensor camera 17. The illumination light from the light source 26 is also diffused widely in the width direction of the sheet 10 at the abrasion 31, and the transmitted diffused light enters the line sensor camera 17.

On the other hand, the light radiated from the rod-shaped light source 16 and transmitted through the abrasion 31 portion goes out of the imaging range of the line sensor camera 17 like the transmitted light at the abrasion portion 21 shown in FIG. However, the brightness of the scratches 31 does not become brighter due to the illumination light from the rod-shaped light source 16. Therefore, the brightness of the image of the line sensor camera 17 at the abrasion 31 is increased by the illumination light from the light sources 25 and 26, and the brightness difference from the normal portion is increased.

In the above embodiment, a line sensor camera is used as an image sensor, but an area sensor camera can be used. Further, the light sources for illuminating the inspected portion obliquely from the sides of the sheet are arranged on both sides of the sheet, but the number of light sources may be one. Further, the sheet to be inspected may be translucent.

[0022]

EXAMPLE A surface inspection of a belt-shaped transparent film running continuously was performed by a surface inspection apparatus 7 of the present invention. The line sensor camera is TL-2 manufactured by Takenaka System Equipment.
048HL (product name), and LS-30J (product name) manufactured by Takenaka System Equipment Co., Ltd. as the controller, arranged so that the field of view would be 200 mm. Further, as a light source for irradiating the inspection part with the illumination light from the side, a halogen light source device (product name: LA-150SE) manufactured by Hayashi Watch Co., Ltd.
Light guide (Product name: LGB2-3L1000L)
S) is attached and two of them are used, and the distance between them is 36
0 mm, the distance from the transparent film was 360 mm, and the angle of incidence of the illumination light on the transparent film was 55 °. Further, as a rod-shaped light source for illuminating the inspected portion from the running direction of the transparent film, a linear light source unit Linear Bright (product name: PDL-S) manufactured by Japan PI is used.

As a result of the inspection using the above-described surface inspection apparatus, abrasion that strongly diffuses the transmitted light in a plane substantially perpendicular to the running direction of the transparent film, and the transmitted light in the running direction of the transparent film. In any of the abrasions diffused within a certain angle range, the lightness at the abrasion part was significantly brighter, and abrasions that could not be detected by the conventional device were easily detected. Thus, it was confirmed that the surface inspection device of the present invention can reliably detect the abrasion without being affected by the diffusion direction of the light transmitted through the abrasion.

[0024]

As described above, according to the surface inspection apparatus of the present invention, the illuminating means is arranged in a plane substantially orthogonal to the longitudinal direction of the abrasion and including the imaging means and outside the imaging range of the imaging means. Then, since the inspected portion is illuminated from an oblique direction, the inspected portion strongly diffuses transmitted light in a plane substantially perpendicular to the longitudinal direction of the abrasion, and there are abrasions that do not diffuse much in the longitudinal direction. Then, the light emitted from the illumination means and transmitted through the abrasion part is widely diffused in a plane substantially orthogonal to the longitudinal direction of the abrasion, and enters the imaging means. Also,
On the back side of the continuously running belt-shaped sheet and outside the imaging range of the imaging unit, a bar-shaped second illumination unit extending in parallel with the inspected portion extending in the width direction of the belt-shaped sheet is arranged, and By illuminating obliquely with respect to the running direction of the belt-like sheet, the transmitted light is not diffused so much in the surface to be inspected in a plane substantially perpendicular to the longitudinal direction of the abrasion, but strongly in a wide angle range in the longitudinal direction. If there is an abrasion that diffuses the transmitted light, the light emitted from the second illuminating unit and transmitted through the abrasion part is diffused widely in the running direction of the belt-like sheet and enters the imaging unit. As a result, regardless of the diffusion direction of the light transmitted through the abrasion portion, the brightness at the abrasion portion becomes bright and the brightness difference from the normal portion increases, so that the abrasion portion can be reliably detected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a surface inspection apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a positional relationship between a line sensor camera and a light source shown in FIG.

FIG. 3 is an explanatory diagram showing a state where illumination light emitted from the light source shown in FIG. 1 is transmitted and diffused at a scratch portion.

FIG. 4 is an explanatory diagram showing another transmission and diffusion state of the abrasion part of the illumination light emitted from the light source shown in FIG. 1;

FIG. 5 is a schematic diagram showing a configuration of a conventional surface inspection device.

FIG. 6 is a schematic diagram showing another configuration of a conventional surface inspection apparatus.

FIG. 7 is an explanatory diagram showing a state where the illumination light emitted from the rod-shaped light source shown in FIG. 6 is transmitted and diffused at the abrasion portion.

FIG. 8 is an explanatory diagram showing another transmission and diffusion state at the abrasion portion of the illumination light emitted from the rod-shaped light source shown in FIG. 6;

[Explanation of symbols]

 5, 6, 7 Surface inspection device 10 Sheet 10a Inspection target 16 Bar-shaped light source 17 Line sensor camera 20, 21, 30, 31 Scratches 25, 26 Light source

Claims (5)

[Claims] An illumination unit configured to illuminate a portion to be inspected of a transparent sheet from a back side; and an imaging unit configured to capture an image of the inspection target from a front surface side of the sheet directly opposite to the front surface of the sheet. In a surface inspection device that inspects for the presence or absence of a linear abrasion having a constant longitudinal direction present on the front surface or the back surface of the sheet based on the obtained image signal, the illumination unit is substantially orthogonal to the longitudinal direction of the abrasion. A surface inspection apparatus which is arranged in a plane including the imaging means and outside the imaging range of the imaging means, and illuminates the inspected portion from an oblique direction. 2. The apparatus according to claim 1, wherein the sheet is a continuously running belt-shaped sheet, and the imaging unit is a line sensor that captures an image of a line-shaped inspected portion extending in a width direction of the belt-shaped sheet. Surface inspection equipment. 3. A bar-shaped second illuminating means extending in parallel with a line-shaped portion to be inspected is disposed on the back side of the band-like sheet and outside the imaging range of the image-taking means. 3. The surface inspection apparatus according to claim 2, wherein illumination is performed from an oblique direction with respect to a traveling direction. 4. A part to be inspected of a transparent sheet is illuminated from the back side, and the part to be inspected is imaged from the front side using an imaging means, and based on an image signal obtained from the imaging means,
In a surface inspection method for inspecting the presence or absence of a linear abrasion having a constant longitudinal direction present on the front surface or the back surface of the sheet, the surface is substantially orthogonal to the longitudinal direction of the abrasion and in a plane including the imaging unit, and A surface inspection method comprising illuminating the inspected portion from an oblique direction outside an imaging range of an imaging unit. 5. The sheet is a continuously running belt-like sheet, and the imaging means captures an image of a line-like inspected portion extending in a width direction of the belt-like sheet, and the line-like inspected portion has a back surface of the belt-like sheet. 5. The surface inspection method according to claim 4, wherein the second illumination light is emitted from the side and outside the imaging range of the imaging means and obliquely with respect to the running direction of the belt-shaped sheet.