JP2000321444A - Optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical fiber having good flank light emission. SOLUTION: Particulates 3 having a refractive index different from the refractive index of a core 1 of the optical fiber and having a specific gravity within a range of 70 to 130% of the specific gravity of the core are mixed within the core 1, by which the distribution of the particulates is made uniform within the core 1. Light is transmitted to the front end of the optical fiber and the good flank light emission is obtained by specifying the diameter of the particulates within a range of 1 to 1000 μm and specifying the concentration thereof within a range of 0.001 to 0.1%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber having a resin core for transmitting light for illumination and a resin clad having a lower refractive index than the core.

[0002]

2. Description of the Related Art A fluorescent lamp is used as a linear light source for illumination, and a cold cathode tube or the like is used as a light source for backlight.

[0003]

However, when illuminating using these light sources, it is necessary to eliminate heat generated from the light sources, high-voltage electricity is required near the light-emitting portion, There is a problem such as the need for strategic protection.

[0004] Also, neon tubes are used for decorative purposes, but the light emitting portion requires electricity, and when used outdoors or underwater, electrical insulation is required to prevent electric shock. Furthermore, neon tubes are expensive because they are manufactured one by one on a custom basis.

For this reason, it has been proposed to use the light leaking from the side of the optical fiber. However, since the loss of a normal optical fiber is required to be reduced, the light leaking from the side is very small.

Further, there is an optical fiber in which a side surface luminous efficiency is improved by providing a scatterer in a core for transmitting light.
Although glass beads are used as the scatterer, the glass beads have a specific gravity higher than that of the core material of the optical fiber, and therefore, have a problem that they precipitate during the production of the optical fiber and the mixing ratio varies widely.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide an optical fiber having good side emission.

[0008]

To achieve the above object, an optical fiber according to the present invention comprises a resin core for transmitting illumination light and a resin clad having a lower refractive index than the core. In the optical fiber for illumination, fine particles having a refractive index different from that of the core and having a specific gravity in a range of 70% to 130% of the specific gravity of the core are mixed in the core.

[0009] In addition to the above structure, the core material of the optical fiber of the present invention is preferably silicone rubber.

In addition to the above constitution, the optical fiber of the present invention has a cladding material made of a fluororesin, a tetrafluoroethylene / hexafluoropropylene copolymer, an ethylene / tetrafluoroethylene copolymer, a tetrafluoroethylene / vinylidenefluoride copolymer. It is preferably one of a copolymer and a tetrafluoroethylene / hexafluoropropylene / vinylidenefluoride copolymer.

[0011] In addition to the above configuration, the optical fiber of the present invention is preferably a microcapsule in which fine particles expand when heated.

[0012] In addition to the above configuration, the optical fiber of the present invention preferably has a particle diameter in the range of 1 µm to 100 µm.

[0013] In addition to the above configuration, the optical fiber of the present invention preferably has a mixing ratio of the fine particles to the core in the range of 0.001% to 0.1%.

According to the present invention, the refractive index of the core of the optical fiber is different from that of the core, and is 70% to 13% of the specific gravity of the core.
By mixing fine particles having a specific gravity of 0%, the distribution of the scatterers inside the core becomes uniform, and the diameter of the fine particles is 1 μm.
１０００1000 μm, and the concentration is 0.001% 〜
By setting it within the range of 0.1%, the light for illumination incident from the incident end is transmitted to the tip of the optical fiber, and good side emission is obtained.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the optical fiber of the present invention.

The optical fiber of the present invention is an optical fiber having a resin core 1 for transmitting light and a resin clad 2 having a lower refractive index than the core 1. The refractive index is different from that of the core 1 and is 70% to 130% of the specific gravity of the core 1.
% Of fine particles 3 having a specific gravity in the range of%.

Here, when the specific gravity of the fine particles 3 is 70% or less of the material of the core 1, the specific gravity of the core 1 is too large, so that the liquid core obtained by mixing the fine particles 3 in the tube made of the material of the clad 2 is used. Is injected and cured, the fine particles 3
And the distribution in the core 1 is not uniform. When the specific gravity of the fine particles 3 is 130% or more of the specific gravity of the material of the core 1, the fine particles 3 precipitate in the liquid core and the distribution is not uniform. Therefore, it is preferable that the specific gravity of the fine particles 3 mixed with the core 1 is in the range of 70% to 130% of the material of the core 1.

As the material of the core 1 of the optical fiber, it is preferable to use silicone rubber in terms of transparency, heat resistance and flexibility. As the material of the clad 2, polytetrafluoroethylene, which is a fluororesin having a low refractive index and high heat resistance, a tetrafluoroethylene / hexafluoropropylene copolymer, an ethylene / tetrafluoroethylene copolymer, a tetrafluoroethylene It is preferable to use an ethylene / vinylidene fluoride copolymer or a tetrafluoroethylene / hexafluoropropylene / vinylidene fluorosulfide copolymer.

The fine particles 3 are preferably made of a material having the property of expanding when heated. As the fine particles 3 expand, the refractive index decreases, and the scattering effect increases. For example, when the fine particles 3 expand and the center becomes air, the refractive index of the fine particles 3 becomes about 1.

Since the scattering of light depends on the diameter of the fine particles 3 and efficient scattering does not occur on the order of the light wavelength or less, the diameter of the fine particles 3 is preferably 1 μm or more. However, if the diameter of the fine particles 3 is 1000 μm or more, the loss of the optical fiber becomes large, so that light cannot be transmitted to the tip of the optical fiber. Therefore, the fine particles 3 have a diameter of 1 μm to 10 μm.
It is preferably within the range of 00 μm. The fine particles 3
Is preferably a microcapsule which expands when heated.

When the concentration of the fine particles 3 is 0.001% or less, the efficiency of light emission by the fine particles 3 does not increase. When the concentration of the fine particles 3 is 0.1% or more, the loss of the optical fiber increases, Light cannot be transmitted to the tip. Therefore, the concentration of the fine particles 3 is 0.001% to 0.1%.
%.

With the optical fiber configured as described above,
The side emission becomes good.

[0024]

The present invention will be described with reference to specific numerical values, but the present invention is not limited thereto.

Example 1 As a material for an optical fiber, a core 1 was made of silicone rubber (refractive index 1.50, specific gravity 1.
2) and tetrafluoroethylene /
Hexafluoropropylene copolymer (refractive index 1.34)
Is used as the microparticles 3 as an expansion capsule (refractive index after expansion, specific gravity 1.2, diameter 10 μm, concentration 0.01%, 120
(Expansion at 0 ° C.). Core diameter 6m using these materials
m, a plastic optical fiber having a cladding diameter of 7 mm and a length of 7 m.

The manufacturing method is to mix an expandable capsule into the core material, press-fit into the clad tube, put the clad tube together in a thermostat at 120 ° C., cure the core material and expand the thermally expandable capsule. is there.

When light was incident on one end of the optical fiber manufactured under such conditions using a metal halide light source of 60 W, side emission was good over the entire length of 7 m.

The expansion temperature of the expansion capsule is 120 ° C.
The temperature is not limited to this, and may be any temperature within a range where the core material is cured.
Further, the refractive index after expansion is not limited to 1, and may be different from the refractive index of the core material.

(Comparative Example 1) As a material of an optical fiber, silicone rubber was used for the core (refractive index: 1.50, specific gravity: 1.2)
The cladding was a tetrafluoroethylene / hexafluoropropylene copolymer (refractive index: 1.34), and the fine particles were glass beads (specific gravity: 2, diameter: 30 μm, concentration: 0.01%).

Using these materials, a plastic optical fiber having a core diameter of 6 mm, a cladding diameter of 7 mm, and a length of 7 m was produced.

The manufacturing method is to mix glass beads in the core material, press-fit it into a clad tube, put the clad tube together in a constant temperature layer at 120 ° C., harden the core material, and simultaneously expand the thermal expansion capsule. .

When light was incident on one end of the optical fiber manufactured under such conditions using a metal halide light source of 60 W, uneven density of glass beads was observed.

(Comparative Example 2) As a material of the optical fiber, a silicone rubber was used for the core (refractive index: 1.50, specific gravity: 1.2)
And a cladding made of a tetrafluoroethylene / hexafluoropropylene copolymer (refractive index: 1.34), and an expanded capsule (refractive index after expansion: about 1, specific gravity: 1.2, diameter: 10 μm, concentration: 0) 0.5%, swelling at 120 ° C.).

Using these materials, a plastic optical fiber having a core diameter of 6 mm, a cladding diameter of 7 mm, and a length of 7 m was produced.

The manufacturing method is to mix an expandable capsule with the core material, press-fit it into a clad tube, put the clad tube together in a thermostat at 120 ° C., cure the core material, and expand the thermally expandable capsule. .

When light was incident on one end of the optical fiber manufactured under such conditions using a 60 W metal halide light source, light emission was large near the light source and no light was emitted at the tip of the optical fiber.

[0037]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide an optical fiber having good side emission.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an optical fiber of the present invention.

[Explanation of symbols]

 1 core 2 clad 3 fine particles

Claims (6)

[Claims] 1. A resin core for transmitting light for illumination,
In the optical fiber having a resin clad having a lower refractive index than the core, the core has a refractive index different from that of the core and a specific gravity in a range of 70% to 130% of the specific gravity of the core. An optical fiber, comprising fine particles having the same. 2. The optical fiber according to claim 1, wherein said core material is silicone rubber. 3. The cladding material is a fluororesin, tetrafluoroethylene / hexafluoropropylene copolymer, ethylene / tetrafluoroethylene copolymer, tetrafluoroethylene / vinylidenefluoride copolymer, tetrafluoroethylene / hexafluoro The optical fiber according to claim 2, wherein the optical fiber is any one of a propylene / vinylidene fluorolide copolymer. 4. The optical fiber according to claim 1, wherein the fine particles are microcapsules that expand when heat is applied. 5. The optical fiber according to claim 4, wherein the diameter of the fine particles is in a range of 1 μm to 100 μm. 6. The optical fiber according to claim 5, wherein a mixing ratio of the fine particles to the core is in a range of 0.001% to 0.1%.