JPS63106604A - Surface light source - Google Patents

Abstract

PURPOSE:To obtain a surface light source having a high projection luminance, a uniform luminance distribution, and also, a high leakage light emission efficiency, by using a multi-optical fiber for the surface light source. CONSTITUTION:An incident light beam from an incident end 2 passes through each constitution fiber 8 being an optical propagation body in a multi-optical fiber 3 and propagated in the direction of the other end, and the propagated light beam is obstructed as to its straight traveling in a scattered light part 7, leaks to the side face and becomes a surface light source. In the scattered light part 7, when a deep damage is given in advance, as its part becomes distant successively from the incident side of the light beam, the surface light source of a wide range can be obtained. In such a way, an emitted light from each constitution fiber 8 becomes an end face emission, therefore, the dependency by incident angle of an incident light beam in case of a side face leakage light executed by collecting many single optical fibers of a core - sheath structure is eliminated, and also, the surface light source whose leakage light emission efficiency is high remarkably is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thin surface light source using a large number of multi-optical fibers.

[Prior art and problems]

Conventionally, in an illumination device, a large number of optical fibers with a core-sheath structure are arranged to form a sheet-like light guide, and light is input from at least one end of the sheet-like light guide. A known method is to make multiple scratches that reach the core and leak light from the sides.

However, with side light leakage technology, the larger the light emitting area, the more
It is difficult to make the light emitting surface shine uniformly, and if the side surface is uniformly damaged, the amount of light leakage from the light source side is large and a uniform leakage light flux distribution cannot be obtained. For this reason, special public relations
It is known that the distribution of the amount of light leakage can be made uniform by roughening the side surface to a certain functional density as described in No. 84. It is difficult to control this, and even if it were possible, it is known that if the acceptance angle from the light source deviates slightly, the leakage luminous flux distribution will be greatly disturbed, resulting in non-uniform illumination. Furthermore, the light rays that contribute to light leakage in the roughened portion are high-order mode incident light, and low-order mode incident light is transmitted through the flaws in the fiber side wall without being leaked. In other words, it is a surface light source that has a problem in that the light leakage and output efficiency with respect to the amount of incident light is extremely low.

[Means for solving problems]

In order to solve this problem, the present invention attempts to provide a surface light source with a uniform light emission distribution using multiple optical fibers.

The gist of the present invention is that at least one end of a sheet-like light guide in which a plurality of multi-optical fibers are aligned and arranged in a sheet form is used as a light incident part, and a light scattering part is provided on the side part of the sheet-like light guide. The reason lies in the use of fiber. Multi-optical fiber differs from the well-known single optical fiber with a core-sheath structure, and has approximately 30 to 10,000 optically transmitting high sections with a diameter of approximately 5 to 200 microns arranged in the sea. It has excellent functions such as

The cross-sectional shape of the multi-optical fiber itself may be circular, rectangular, or other shapes, but if a smooth surface light source is desired, a rectangular one is preferable. Further, the diameter or thickness can be changed as appropriate depending on the desired flexibility of the surface light source, but it is preferably 150 μm to 3 decoys.

The surface light source of the present invention is not limited to a sheet-like structure in which multi-optical fibers are simply arranged in parallel, but can also be laminated in several rows to form a relatively thick sheet-like light guide, if necessary.

Next, the present invention will be explained based on the drawings showing examples of the present invention.

FIG. 1 is a perspective view showing an embodiment of a surface light source according to the present invention, and FIG. 2 is a schematic cross-sectional view of the surface light source according to the present invention.
FIG. 3 is a sectional view taken along line B-B' in FIG. 2. Furthermore, the fourth
The figure shows an enlarged schematic cross-sectional view of the scattered light section A in FIG. 2.

In FIG. 2, the incident light beam from the input end (2) propagates in the multi-optical fiber (3) through each constituent fiber (8) which is a light propagating body toward the other end. The propagating light is prevented from going straight in the scattering light section (7), and leaks to the side as shown in FIG. 4, forming a surface light source.

In the scattering light section (7), if the damage is caused deeper as the distance increases from the light incident side, as shown in Fig. 4, the structure 7 eyeper (8) that takes charge of light propagation within the multi-optical fiber (3) will be created. The first layer (surface layer) is cut at the part marked with ■.
The propagating light is emitted from the side face at this portion. Furthermore, the light propagated by the constituent fiber (8) of the second layer is also emitted from the end face at the part (■). By repeating this process, it became possible to obtain a wide range of surface light sources. In this way, the light emitted from each constituent fiber (8) is end-emitted, which eliminates the problem of side light leakage, which is a problem in the case of side light leakage, which is performed by arranging a large number of single optical fibers with a conventional core-sheath structure. This results in a surface light source that has no dependence on the incident angle and has extremely high light leakage and output efficiency.

In addition, a diffuser plate (4) having a diffusion effect is provided in the scattering light section (7).
or paint, or place a reflective plate (5) on the back of the scattering light section (7).
), a surface light source with more uniform illumination and high illumination efficiency can be obtained. Furthermore, if the damaged part (6) is filled with a resin, paint, etc. that has a higher refractive index than the core material of the constituent fiber (8), side emission will be made more efficient, and the sheet-like light guide that will be formed if deep damage is caused. It is advantageous to prevent this from becoming brittle, and its shape is preferably circular or square.

FIG. 1 shows a surface light source created with this point in mind, and is an embodiment in which the incident end (2) is tied into a substantially square shape. Further, although the scattered light portion of the surface light source in FIG. 1 is damaged on the output side, the same effect can be obtained even if this is reversed. Furthermore, the entrance ends (2) can also be provided at both ends of the sheet-like light guide.

Regarding the scattering light portion (6), by arbitrarily changing the depth of each area, it is possible to obtain an arbitrary light leakage distribution. In order to make the overall light leakage distribution uniform, it is desirable that the scratches (6) be placed at approximately equal intervals and that the difference in depth between adjacent scratches (6) be constant. The shape of @(6) may be wedge-shaped or arc-shaped and is not particularly limited. Alternatively, instead of the scratches (6), it is possible to make the sheet-like light guide have a tapered end, as shown in FIG. 4, and provide an inclination so that light leaks uniformly from this inclined surface to the side surface. Further, the method for creating the scratches (6) includes, but is not limited to, laser processing, hot stamping, sanding, etc.

〔Effect of the invention〕

As described above, the main feature of the surface light source of the present invention is that it is possible to create a surface light source with extremely high projection brightness, uniform brightness distribution, and high light leakage/emission efficiency using multiple optical fibers. It is. Compared to conventionally developed surface light sources, the surface light source of the present invention can be easily made lighter, thinner, and larger, and has high brightness.
For example, it is extremely useful industrially for lighting from the back of LCDs, signboards, etc.

[Brief explanation of the drawing]

FIG. 1 shows an outline of the configuration of a surface light source according to the present invention. FIG. 2 is a schematic cross-sectional view of the surface light source of the present invention, FIG. 3 is a cross-sectional view of the section B-B' in FIG. 2, and FIG.
It is a partially enlarged view of the figure. Further, FIG. 4 is a schematic cross-sectional view showing an embodiment in which the scattered light portion is a tapered end face of a multi-optical fiber. (1)...Light source (2)...Incidence end (3)...Multi-optical fiber (4)...Diffusion plate (5)...Reflector ( 6)... Scratch (7)... Scattered light section (8)... Constituent fiber No. 1 Figure 5 Group procedural amendment October 1, 1988 1. Indication of the incident 1986 Patent Application No. 252585 2, Name of the Invention Surface Light Source 3, Relationship with the Amended Person Case Patent Applicant: 2-3-19 Kyobashi, Chuo-ku, Tokyo (603) Akio Kawasaki, President and Director of Mitsubishi Rayon Co., Ltd. 4. Agent Address: 2-3-19-7 Kyobashi, Chuo-ku, Tokyo 104 Contents of amendment

Claims (7)

[Claims] (1) A surface light source characterized in that at least one end of a sheet-like light guide in which a plurality of multi-optical fibers are aligned and arranged is used as a light incident part, and a light scattering part is provided on a side face of the sheet-like light guide. (2) The surface light source according to claim 1, wherein the scattered light portion is a light leakage portion that is damaged sequentially and deeply in the length direction from the light incident side. (3) A surface light source according to claim 1, wherein a plate and/or paint having a light diffusing effect is disposed in front of the scattering light section. (4) The surface light source according to claim 2, wherein at least the damaged portion is filled with a resin having a higher refractive index than the core material in the multi-optical fiber. (5) The surface light source according to claim 1, wherein a reflecting plate is installed on the back surface of the scattered light section. (6) A surface light source according to claim 1, characterized in that the light incident end of the sheet-like light guide is bundled into a circular or square point shape. (7) The surface light source according to claim 1, wherein the scattered light portion has a tapered end shape.