JPH09230149A - Method for working front end of optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for working the front end of an optical fiber adequate for use for illumination and display devices. SOLUTION: The front end of the optical fiber 1 is worked in such a manner that its sectional shape is formed to a concave spherical surface. By which, the orientation characteristic of the exit light from the front end of the optical fiber 1 is determined in accordance with the ratio of the areas of the light refraction part 7a and light total reflection part 7b of the worked surface. In such a case, the sectional shape of the front end of the optical fiber 1 is conceivably formed to a semi-elliptical shape facing sideways when viewed from the front to narrow the orientation characteristic of the light emitted from the front end of the optical fiber. The sectional shape of the front end of the optical fiber is otherwise formed to a semi-elliptical shape facing longitudinally when viewed from the front to widen the orientation characteristic of the light emitted from the front end of the optical fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for processing a tip of an optical fiber used for illumination or a display device.

[0002]

2. Description of the Related Art The tip of a conventional optical fiber used for this kind of application has been processed as shown in FIG. 3 (A) or (B). FIG. 3A is a vertical sectional front view of the tip portion of the first conventional optical fiber, and FIG. 3B is a vertical sectional front view of the tip portion of the second conventional optical fiber. Figures (A) and (B)
In the figure, reference numeral 1 denotes an optical fiber, which is formed by a core 3 covered with a cladding 2 and in which light is repeatedly reflected (transmitted) in the core 3. Reference numeral 4 denotes an optical fiber fixing tool such as a sign for fixing the optical fiber 1. Reference numeral 5 denotes a light emitting portion that emits light at the tip of the optical fiber 1 of the first conventional example.
The cross section of the optical fiber 1 is cut and polished, and is installed parallel to the fixture 4. Reference numeral 6 denotes a light emitting portion at the tip of the optical fiber 1 of the second conventional example, which is formed in a pencil shape. Compared to the first conventional example (FIG. 3A), the tip of the optical fiber 1 is formed. It is processed so that the directional characteristics of the light from are somewhat widened.

[0003]

By the way, in the case of the first conventional example, there is a problem that the emitted light is in a substantially straight traveling direction and the directional characteristic is poor. In the second conventional example, the refracting action of light is increased as compared with the first conventional example, so that the directional characteristic is slightly increased, but the directional range is increased only by about 30 degrees, and the wide range is wide. It did not emit light to. Therefore, when the characters on the display plate or the like are formed by the light emitted from the optical fiber, the display on the display plate cannot be recognized from a wide range, and improvement thereof has been demanded. It is an object of the present invention to provide an optical fiber tip processing method that solves the above problems (problems) of conventional ones.

[0004]

In order to solve the above-mentioned problems, the optical fiber tip processing method of the present invention processes the tip of the optical fiber so that its cross-sectional shape is a concave spherical surface. The directional characteristic of the light emitted from the tip of the optical fiber is determined based on the ratio of the areas of the light refraction portion and the total light reflection portion in. In this case, the cross-sectional shape of the tip of the optical fiber is formed to be a lateral semi-elliptical shape when viewed from the front to narrow the directivity of the light emitted from the tip of the optical fiber, and the cross section of the tip of the optical fiber. It is considered that the shape is formed in a vertically oriented semi-elliptical shape when viewed from the front to widen the directional characteristics of the light emitted from the tip of the optical fiber.

In the optical fiber tip processing method of the present invention, the light emitting portion at the tip of the optical fiber is processed into a concave spherical surface, and the directional characteristics determined based on the ratio of refraction and total reflection of light on the processed surface Light from the tip of the optical fiber can be diffused and irradiated in a substantially hemispherical shape. In this case, if the cross-sectional shape of the light emitting portion at the tip of the optical fiber is processed into a lateral semi-elliptical shape when viewed from the front, the area ratio of the light refraction portion becomes larger than the area of the light total reflection portion. The directional characteristics of the light emitted from the tip of the optical fiber can be sharpened. Further, if the cross-sectional shape of the light emitting portion at the tip of the optical fiber is processed into a vertically oriented semi-elliptical shape when viewed from the front, the area ratio of the light refraction portion becomes smaller than the area of the light total reflection portion. It is possible to widen the directional characteristics of the light emitted from the tip of the optical fiber. Therefore, the light emitted from the optical fiber can be diffused with the directional characteristics that match the purpose of use, depending on how the tip of the optical fiber is processed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described with reference to FIGS. FIG. 1 (A) is a vertical sectional front view of a tip portion of an optical fiber which is the basic configuration of the present invention, and FIG. 1 (B) shows the state of light emitted from the optical fiber to show the principle of the present invention. It is a vertical cross-sectional front view of a front-end | tip part. In FIG. 1A, reference numeral 1 is an optical fiber, which is formed by a core 3 covered with a clad 2 and which is transmitted through the core 3 by repeating reflection. Reference numeral 4 denotes an optical fiber fixing tool such as a sign for fixing the optical fiber 1. Reference numeral 7 denotes a light emitting portion that emits light transmitted from a light source (not shown) from the tip of the optical fiber 1. The light emitting portion 7 is formed into a concave spherical shape, which is a characteristic feature of the present invention. is there. In this case, the emission surface of the light emitting portion 7 is roughly divided into a light refracting portion 7a in the central portion of the concave curved surface and a total light reflecting portion 7b on both side surface portions. Further, the light emitting portion 7 of the optical fiber 1 is installed so as to protrude from the fixture 4 by a predetermined length. FIG. 1B is a vertical sectional front view of the tip of the optical fiber, which also shows the state of the light emitted from the optical fiber 1. The same components as those in FIG. 1A are designated by the same reference numerals. In FIG. 1B, La represents incident light transmitted through the core 3, and Lb represents emitted light. Of the emitted light Lb, Lb1 is refracted by the light refracting portion 7a of the light emitting portion 7 and is emitted. Show the light, and also
Lb2 indicates the light emitted after being totally reflected by the light total reflection portion 7b of the light emitting portion 7. As shown in FIG. 2B, the light transmitted through the core 3 of the optical fiber 1 is formed by forming the light emitting portion 7 at the tip of the optical fiber 1 into a concave spherical surface so that the refracted portion in the concave spherical surface and the light It can be seen that the light is diffused with the directional characteristic determined based on the ratio of the area of the total reflection portion. Normally, the light in the core 3 of the optical fiber 1 is transmitted at an angle within a solid angle of 60 degrees, so that there is light obliquely incident from the core 3 of the optical fiber 1 to the light emitting portion 7. The present invention focuses on the use of the directional characteristic in which light is diffused with refraction and total reflection in each portion of the concave spherical surface of the light emitting portion 7 in a display device or the like. The present invention will be described more specifically with reference to the respective embodiments.

First Embodiment: FIG. 2A is a vertical sectional front view of a tip portion of an optical fiber according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an optical fiber, which is formed by a core 3 covered with a clad 2 and in which light is repeatedly reflected and transmitted in the core 3. Reference numeral 4 denotes an optical fiber fixing tool such as a sign for fixing the optical fiber 1. Reference numeral 8 denotes a light emitting portion that emits light at the tip of the optical fiber 1. The surface of the light emitting portion 8 is formed into a concave spherical surface. A characteristic feature of the present embodiment is that it is formed into a shape. In this case, the emitting surface of the light emitting portion 8 is roughly divided into a central light refracting portion 8a in the concave curved surface and a total light reflecting portion 8b on both side surfaces, and the light refracting portion 8a is more than the total light reflecting portion 8b. Is also formed to have a large area. Further, the light emitting portion 8 at the tip of the optical fiber 1 is installed so as to protrude from the fixture 4 by a predetermined length. As described above, when the cross-sectional shape of the light emitting portion 8 is formed in a horizontal semi-elliptical shape when viewed from the front, the area ratio of the light refracting portion 8a becomes larger than the area of the total light reflecting portion 8b. As shown in (B), the refracted light Lb1 increases and the reflected light Lb2 decreases, so that the outgoing light emitted from the optical fiber 1 has a narrow directional characteristic.

Second Embodiment: FIG. 2B is a vertical sectional front view of a tip portion of an optical fiber according to a second embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an optical fiber, which is formed by a core 3 covered with a clad 2 and in which light is repeatedly reflected and transmitted in the core 3. Reference numeral 4 denotes an optical fiber fixing tool such as a sign for fixing the optical fiber 1. Reference numeral 9 denotes a light emitting portion that emits light at the tip of the optical fiber 1. The surface of the light emitting portion 9 is formed into a concave spherical surface, and the cross sectional shape of the concave spherical surface is a vertical half when viewed from the front. A characteristic feature of the present embodiment is that it is formed into an elliptical shape. In this case, the emitting surface of the light emitting portion 9 is roughly divided into a central light refracting portion 9a in the concave curved surface and a total light reflecting portion 9b on both side surfaces, and the area of the light refracting portion 9a is the total light reflecting portion. 9b
Is formed to be smaller than the area. In this embodiment as well, the light emitting portion 9 of the optical fiber 1 is installed so as to protrude from the fixture 4 by a predetermined length. As described above, when the cross-sectional shape of the light emitting portion 9 is formed in a semi-elliptical shape in the horizontal direction when viewed from the front, the area ratio of the light refracting portion 9a becomes smaller than the area of the total light reflecting portion 9b. As shown in (B), the refracted light Lb1 decreases and the reflected light Lb2 increases, so that the outgoing light emitted from the optical fiber 1 has a wide directional characteristic.

[0009]

The method for processing the end of an optical fiber according to the present invention has the following excellent effects because the end of the optical fiber is processed as described above. (1) Conventionally, only the light is diffused by utilizing the refraction effect of light, but since the tip of the optical fiber is processed into a concave spherical surface, the area of the light refraction portion and the light total reflection portion is It is possible to appropriately set the directional characteristic of the emitted light, that is, the light distribution characteristic of the light emitted from the tip of the optical fiber, based on the ratio. (2) In this case, as shown in the first embodiment, the cross-sectional shape of the light emitting portion is formed in a lateral semi-elliptical shape when viewed from the front, and the optical fiber tip is narrowed so that the directivity of the optical fiber is narrowed. By processing the light emitting part, the light emitting part can be used for decoration, display, etc. by light that requires spot-like illumination. (3) Further, as shown in the second embodiment, the cross-sectional shape of the light emitting portion is formed in a lateral semi-elliptical shape when viewed from the front, and the tip of the optical fiber is widened so as to widen the directional characteristics of the optical fiber. By processing the light emitting portion, visibility from a wide range outside can be obtained. Therefore, if the display of the display plate is performed using a plurality of optical fibers having the ends of the optical fibers thus processed,
Illuminations that require recognition of characters / figures from a wide range (for example, to notify many people such as road signs such as "speed limit" and "stop", guide signs for telephone boxes, guide lights in tunnels, etc.) It is effective for uses such as advertising billboards.

[Brief description of drawings]

FIG. 1A is a vertical sectional front view of a tip portion of an optical fiber which is a basic configuration of the present invention, and FIG. 1B shows a state of light emitted from the optical fiber to show the principle of the present invention. It is a vertical front view of the front-end | tip part of the shown optical fiber.

FIG. 2 (A) is a vertical sectional front view of a tip portion of an optical fiber showing a first embodiment of the present invention, and FIG. 2 (B) is an optical fiber showing a second embodiment of the present invention. FIG. 4 is a vertical cross-sectional front view of a tip end portion of FIG.

3A is a vertical sectional front view of a tip portion of an optical fiber of a first conventional example, and FIG. 3B is a vertical sectional front view of a tip portion of an optical fiber of a second conventional example.

[Explanation of reference numerals] 1: optical fiber 2: clad 3: core 7, 8, 9: light emitting portion 7a, 8a, 9a: light refracting portion 7b, 8b, 9b: light total reflection portion La: incident light Lb: emitting Emitted light Lb1: Refracted light Lb2: Reflected light

Claims (3)

[Claims] 1. A tip of an optical fiber is machined so that its cross-sectional shape is a concave spherical surface, and the tip of the optical fiber is A method for processing the tip of an optical fiber, characterized in that the directional characteristic of the emitted light is determined. 2. A cross-sectional shape of the tip of the optical fiber is formed in a horizontal semi-elliptical shape when viewed from the front, and the directional characteristic of the light emitted from the tip of the optical fiber is narrowed.
The optical fiber tip processing method described. 3. The cross-sectional shape of the tip of the optical fiber is formed in a vertically oriented semi-elliptical shape when viewed from the front, so that the directional characteristic of the light emitted from the tip of the optical fiber is widened.
The optical fiber tip processing method described.