JPH07104131A - Optical fiber line shaped light guide - Google Patents

Abstract

PURPOSE:To illuminate by a light guide so that the faults such as very slight scratches, fine wrinckels and stripes may be detected as the faults even in the case these faults are generated in a direction of carrying an object to be inspected. CONSTITUTION:The light guide is constituted of plural optical fibers 1 which are bundled on the light incident ends 2 and arranged on the light emitting end 3 in a line, a line shaped ferrule 3 for supporting the light emitting end part and a metal fixture 5 for bundling the light incident ends 2, and the light emitting end part of the optical fiber 1 is arranged while being inclined to the light emitting end face 6 of the light guide, the light emitting end face of the optical fiber 1 is formed perpendicularly to the light emitting axis of the optical fiber, and also, the end face is mirror-finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber linear light guide, and more particularly to an optical fiber linear light guide used for illumination in defect detection.

[0002]

BACKGROUND OF THE INVENTION For defect inspection of films, papers, resin plates, non-woven fabrics, metal foils, ceramics, etc. that are continuously produced, and glass plates, circuit boards, optical disks, drums, etc. Require high resolution, high speed inspection. In such a defect inspection, normally, for an object to be inspected that is continuously or intermittently transported,
A line-shaped illumination arranged in a direction traversing the inspection object and a line CCD camera that receives reflected light or transmitted light from the inspection object are used.

Defects found in the above-mentioned objects to be inspected, such as films and circuit boards, include surface-attached foreign matter, inclusion foreign matter,
There are irregularities such as bubbles and dents, surface scratches, stains and wrinkles, and if coating or vapor deposition is performed, there are pinholes, coating stripes, coating film unevenness and the like. As the linear illumination used for illumination in the above defect detection, there are a fluorescent lamp, a lamp light source such as a halogen lamp and a metal halide lamp, an optical fiber light guide and the like, and a combination thereof.

[0004]

In the detection of defects on the above-mentioned object to be inspected such as a film or a circuit board, very small scratches, fine wrinkles and stripes, especially those scratches which occur in the conveying direction of the object to be inspected, It is difficult to detect as a defect by conventional line illumination. This is because these shallow scratches are directional to light scattering, etc.

On the other hand, it has been proposed to incline the linear light source in the transport direction in order to irradiate light having a strong directivity with a light source parallel to the direction in which the scratch is generated. . However, in the carrying direction, there is a limit to the inclination due to the width of the light source itself, and it is difficult to incline in the longitudinal direction (line width direction) of the linear light source. Further, the light emitting ends of the plurality of optical fibers are arranged in a line, the light emitting end portions are arranged to be inclined with respect to the light emitting end face of the light guide, and the light emitting end faces are formed obliquely to align the light emitting end faces. Line-shaped fiber optic light guides have been proposed. Although the light is obliquely emitted to some extent, the emission angle of the light is widened, and the light component necessary for detecting shallow scratches is insufficient.

The present invention has been made on the basis of the background described above, and its object is to provide defects such as very shallow scratches, fine wrinkles and stripes, which are generated in the carrying direction of the object to be inspected. It is an object of the present invention to provide an optical fiber linear light guide that can be illuminated so that it can be detected as a defect.

[0007]

The above-mentioned problems can be solved by the optical fiber linear light guide according to the present invention. That is, the optical fiber linear light guide includes a plurality of optical fibers whose light incident ends are focused and whose light emitting ends are arranged in a line, and a line-shaped die which supports the light emitting ends arranged in a line. And a metal fitting for converging the light incident end, wherein the light emitting end portion of the optical fiber has an arrangement angle of 10 to 75 ° with respect to the light emitting end face of the light guide. It is characterized in that the light emitting end faces of the optical fibers are arranged so as to be inclined, are formed perpendicularly to the optical axis of the optical fibers emitted, and are mirror-finished. In a preferred embodiment according to the present invention, the light emitting ends arranged in a line can be formed in a plurality of layers.

[0008]

[Operation] The optical fiber linear light guide according to the present invention having the above structure operates as follows.
The light entering from the light incident end propagates in the optical fiber and exits from the light emitting end. In the illumination for defect detection, the emitted light hits an object to be inspected that is conveyed and travels, and is used to detect a defect.

In the present invention, since the light emitting end portion of the optical fiber is arranged at an inclination angle of 10 to 75 ° with respect to the light emitting end surface of the light guide, the surface of the object to be inspected that is conveyed and travels. Very shallow scratches, fine wrinkles,
Irradiation is performed at an angle, that is, at an angle, especially for scratches that occur in the running direction of the inspection target, such as lines.
Illuminate. In this way, since it is inclined with respect to a scratch or the like, light scattering is strengthened even if it is a shallow scratch or the like.

Further, since the light emitting end face of the optical fiber is formed perpendicular to the optical axis of the optical fiber and is mirror-finished, the light is emitted with a narrowed emission angle in the above-mentioned inclination angle direction. Therefore, the light can be effectively used and the amount of light can be secured. Moreover, since the light emitting end portions of the optical fibers are arranged so as to be inclined, the emitting angle is suppressed on the side surface of one adjacent optical fiber,
The directivity of the emitted light is further enhanced.

[0011]

The present invention will be specifically described with reference to the following examples. FIG. 1 is an external view showing an embodiment of an optical fiber linear light guide according to the present invention. The line-shaped light guide 8 includes a plurality of optical fibers 1 in which the light incident ends 2 are focused and the light emitting ends 3 are arranged in a line, and a line-shaped base that supports the light emitting ends arranged in a line. Four
And a metal fitting 5 for focusing the light incident end. FIG. 2 shows an enlarged cross-sectional view near the emission end face of the light guide. As shown in FIG. 2, with respect to the emission end face 6 of this light guide,
The light emitting end portions of the optical fibers are arranged so as to be inclined so that the arrangement angle A is 10 °, the light emitting end face 7 of the optical fibers is formed perpendicular to the optical fiber emitting optical axis, and is formed by optical polishing. It is processed into a mirror surface.

The optical fiber used in the present invention preferably has a clad (sheath) and a core (core), and the structure thereof is a step index type multimode in which the refractive index changes stepwise. There are an optical fiber, a step-index type single-mode optical fiber having a single mode in which the refractive index changes stepwise, and a graded index type multi-mode optical fiber that propagates different modes.

As a material forming the core material, an inorganic material such as multi-component glass or quartz glass, or an organic material such as polymethylmethacrylate resin or polycarbonate resin can be used. The clad (sheath) material used in the present invention has a smaller refractive index than the core material. When a PMMA-based resin is used as the core material, examples of the sheath material include a fluorine-based polymer, a perfluoroalkylmethacrylate-based polymer, and a methacrylic acid ester-based polymer.

FIG. 3 shows a mode of use of the linear light guide 8 according to this embodiment. The sheet 9 to be inspected is run, and the linear light guide 8 is obliquely arranged across the sheet 9 immediately above. Further, the CCD camera 10 is installed above. The light, which is connected to a light source (not shown) and enters from the light incident end of the linear light guide 8, travels in the optical fiber and exits from the light emitting end. The emitted light is the traveling inspection target 9
Upon hitting, light is scattered at a defective portion (such as a scratch), and the scattered light is detected by the CCD camera 10.

In this aspect, since the light emitting end portion of the optical fiber is arranged at an inclination angle of 10 ° with respect to the light emitting surface 6 of the light guide, it is on the surface of the running object 9 to be inspected. Very shallow scratches in the direction of travel,
It illuminates thin wrinkles, stripes, etc. at an angle, that is, at an angle, and enhances the scattering of light even with shallow scratches.

Further, since the light emitting end face of the optical fiber is formed perpendicular to the optical axis of the optical fiber and is optically polished, the light is emitted with a narrowed emission angle in the inclined direction. Therefore, the light can be effectively used and the amount of light can be secured. In the present invention, the linear optical fibers may be arranged in a single layer or plural layers. By forming a plurality of layers in this way, the amount of light can be secured. FIG. 5 shows a front view of the emission end face of the light guide. In this aspect, a four-layer optical fiber array is formed.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above-described embodiment, the inclination is in one direction, but as shown in FIG. 4, it may be inclined in both directions. With such a bidirectional inclination mode, it is possible to deal with various types of defects.

[0018]

According to the optical fiber linear light guide of the present invention having the above-mentioned structure, there are defects such as very shallow scratches, fine wrinkles and lines, which are generated in the carrying direction of the object to be inspected. However, it can be illuminated so that it can be detected as a defect.

[Brief description of drawings]

FIG. 1 is an external view of an embodiment of an optical fiber linear light guide according to the present invention.

FIG. 2 is an enlarged partial view of an emission end face of an embodiment of an optical fiber linear light guide according to the present invention.

FIG. 3 is a perspective view showing a mode of use of the optical fiber linear light guide according to the present invention.

FIG. 4 is an enlarged partial view of the emission end face of the embodiment of the optical fiber linear light guide according to the present invention in a state of being inclined in both directions.

FIG. 5 is a front view of an emission end face of a mode in which light emission ends arranged in a line are formed in four layers.

[Explanation of symbols]

 1 optical fiber 2 incident end 3 emitting end 4 base 5 metal fitting 6 light emitting end face of light guide 7 optical fiber emitting end face 8 light guide 9 object to be inspected 10 CCD camera

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shintaro Tashiro 3816 Noborito, Tama-ku, Kawasaki-shi, Kanagawa Mitsubishi Rayon Co., Ltd. Tokyo Research Laboratory

Claims (2)

[Claims] 1. A plurality of optical fibers each having a light incident end focused and a light emitting end arranged in a line, a line-shaped base for supporting the light emitting end arranged in a line, and a light incident end. A line-shaped light guide comprising a metal fitting for focusing, wherein the light emitting end portion of the optical fiber is inclined with respect to the emitting end face of the light guide so that the arrangement angle is 10 to 75 °. An optical fiber linear light guide characterized in that a light emitting end surface of an optical fiber is formed perpendicular to an optical axis of the optical fiber and is mirror-finished. 2. The optical fiber linear light guide according to claim 1, wherein the light emitting ends arranged in a line form a plurality of layers.