JPH0651128A - Linear light guide - Google Patents

Abstract

PURPOSE:To vary projection directivity and detect a wrinkle, a flaw, etc., in a travel direction by providing a prism plate, which is formed in a mountain or saw-tooth shape to a pitch equal to or less than the diameter of a fiber, on a linear end surface. CONSTITUTION:The linear light guide 1 is formed by circularly bundling one end 1a of an optical fiber bundle 2 and linearly arraying the other end 1b. In this case, the triangular prism plate 3 which is formed to the pitch equal to or less than the fiber diameter is provided on the linear end surface 1b and the projection directivity of line-directional light on the linear end surface is variable. In another case, the prism plate 3 may be formed in a saw-tooth shape. In this configuration, light can be projected from only one direction. The angle of the prism 3 is selected according to the projection direction. The prism 3 is manufactured by heating and molding a plastic plate of acrylic or polycarbonate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide for inspecting sheet materials produced in factories and the like.

[0002]

2. Description of the Related Art Conventionally, a linear light guide using an optical fiber has one end focused in a circular shape and the other end arranged in a linear shape, and the circular end surface is fitted to a light source device.
Light is incident from the lamp. In a linear light guide using a plastic optical fiber, the linear end face is 0.2
Fibers of about 5 to 1.0 mmφ are stacked in multiple stages.

[0003]

Such a line-shaped light guide is used for inspecting continuously produced sheet-like objects and the like. Light is radiated from the licking direction to the traveling direction of the sheet-like material, and the scattered light at the defective portion is observed by a line camera or the like. In this case, the optical fiber has a directivity distribution of light that is determined by the aperture angle and the incident condition, and a change in the scattering state of a scratch or the like perpendicular to the traveling direction is easy to catch. However, scratches parallel to the traveling direction have many light emission components parallel to the scratch direction, and it is difficult to observe changes in the scattered light state with a line camera installed vertically to the traveling direction.

[0004]

The above-mentioned problems can be solved by the present invention. That is, the line-shaped light guide of the present invention is a line-shaped light guide in which one end of an optical fiber bundle is converged in a circle and the other end is aligned in a line, and the line-shaped end face has a fiber diameter equal to or equal to that of the fiber diameter. It has a mountain-shaped or saw-tooth-shaped prism plate formed at the following pitches, and has a function of changing the emission directivity of light in the line direction at the line-shaped end face.

[0005]

In the linear light guide of the present invention having the above structure, light enters from the circular end surface of the optical fiber bundle.
The incident light propagates inside each optical fiber of the optical fiber bundle. The propagated light is emitted from the other end of the optical fiber bundle arranged in a line shape, and the linear shape is formed on the end face of the linear shape by a mountain-shaped or sawtooth-shaped prism plate formed at a pitch equal to or smaller than the fiber diameter. The emission directivity of light is changed in the line direction on the end face. The light with the changed directivity illuminates the object.

[0006]

EXAMPLES The present invention will be described in detail with reference to examples. FIG. 1 shows a schematic structure of a light guide according to an embodiment. The line-shaped light guide 1 of this aspect is a line-shaped light guide in which one end 1a of the optical fiber bundle 2 is converged in a circular shape and the other end 1b is aligned in a line, and the line-shaped end face 1b has a fiber diameter The triangular mountain-shaped prism plate 3 formed with a pitch equal to or less than that is provided, and has a function of changing the emission directivity of light in the line direction at the line-shaped end face.

In the embodiment shown in FIG. 1, as shown in FIG.
The prism plate 3 has a triangular mountain shape. The pitch d of the prisms is formed on the linear end face at a pitch equal to or smaller than the fiber diameter. In this mode, the object can be irradiated from both directions, and the light is emitted from the diagonal direction which is the contrast from the line direction of the linear light guide. In this embodiment, a triangular mountain-shaped prism having an angle of 30 ° is used on the line-shaped end face in which two 0.5 mmφ fibers are stacked. The pitch is 0.25 mm.

The present invention is not limited to the above-mentioned embodiment, but various modes are possible. For example, as shown in FIG. 3, the prism plate 3 may have a sawtooth cross section. In this aspect, light can be emitted from only one direction. The angle of the prism is selected according to the outgoing direction. It is preferable to use a prism having a small angle for detecting a relatively shallow flaw, and a large prism for detecting a deep flaw. The prism can be manufactured by heat molding an acrylic or polycarbonate plastic plate.

[0009]

According to the present invention, a prism having a diameter equal to or smaller than the fiber diameter is inserted into the linear end face of a linear light guide using an optical fiber to incline the light emitting direction with respect to the line direction. Can be
It is possible to detect wrinkles, scratches, etc. in the traveling direction that occur on the traveling sheet-like object.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a linear light guide according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a linear end surface side of an example in which the prism shape is a triangular mountain shape.

FIG. 3 is an enlarged cross-sectional view of a linear end face side of an example in which the prism shape is a sawtooth shape.

[Explanation of symbols]

 1 light guide 2 optical fiber bundle 3 prism

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

Claims (1)

[Claims] 1. A line-shaped light guide in which one end of an optical fiber bundle is converged in a circular shape and the other end is aligned in a line, and is formed on the line-shaped end face at a pitch equal to or smaller than a fiber diameter. A line-shaped light guide, which is provided with a mountain-shaped or saw-tooth shaped prism plate and has a function of changing the emission directionality of light in the line direction at the line-shaped end face.