JPH07198951A - Light transmission body - Google Patents

Abstract

PURPOSE:To provide a light transmission body provided with uniform and high luminance over the whole length while securing transmission property of light and capable of safely using even in the environment such as underwater, etc. CONSTITUTION:The light transmission body is constituted of a transparent core material 2 and a clad material 1 with a refractive index lower than the core material 2, and a beam is made incident from one end of the core material 2, and the incident beam is transmitted to the other end. Then, parallel to the advance direction of light and discontinuously, continuous or discontinuous minute ruggedness with projecting stripes and recessed groove shape inclining partialiy or wholly for the advance direction of light are formed on a boundary surface between the clad material 1 and the core material 2 from the incident side of light to the outgoing side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission body having an increased luminous brightness on the peripheral surface of the optical transmission body.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
A neon tube is a luminous body that can emit light over a long length. However, the neon tube requires an electric power of about 1 kW per 1 m, and when it becomes long, a high voltage proportional to its length is required. Therefore, the length of about 3 to 5 m is practically limited. Also, since there is a problem of leakage in water, it cannot be used in water, and since the neon tube is made of glass, the glass tube is damaged, and glass work is required when bending, There was a problem that it required skill.

Therefore, as a solution to these problems, an optical transmission tube (manufactured by Bridgestone) in which a transparent core liquid is enclosed in a flexible tube, and a plastic optical fiber twisted together (fiber star, manufactured by Mitsubishi Rayon), etc. An optical transmission tube that can be used with a length as long as 50 m has been proposed. This light transmission tube can be used in water and in environments where there is a risk of explosion.
It does not require complicated processing such as glasswork and has good workability, but the luminous brightness of the peripheral surface is 1/2 to 1/1 of that of neon tubes.
It is about 0.

Further, the applicant of the present invention has disclosed in Japanese Patent Application No. 4-26668 as an optical transmission tube for achieving high brightness.
We have proposed a blend type optical transmission tube that uses a phosphoric acid ester type liquid as the core material. In this light transmission tube, a small amount of an ester plasticizer is mixed with a phosphoric acid ester liquid, and the mixing ratio is changed to increase the brightness of the peripheral surface to about 5 times that of a conventional light transmission tube. . However, since the color temperature of the light transmission tube becomes smaller as it becomes longer, the light emission tends to be yellow, and non-uniformity of light emission may be observed in the length direction.

Further, by roughening the surface of the plastic optical fiber with sandpaper or the like,
A method of increasing the emission brightness of the side surface of the optical fiber has also been proposed, but it is difficult to roughen the surface, so the reproducibility of processing is poor, and the area near the light source is bright, but it rapidly darkens as it moves away from the light source. There is a problem in that it is not possible to obtain a light-emitting body that exceeds 1 m.

The present invention has been made in view of the above circumstances.
An object of the present invention is to provide an optical transmission tube which has high peripheral brightness over the entire length and can be safely used even in an environment such as underwater.

[0007]

Means for Solving the Problems The present inventor has conducted extensive studies to achieve the above object, and as a result, it is composed of a transparent core material and a clad material having a refractive index lower than that of the core material.
In an optical transmission body in which light is incident from one end of the core material and the incident light is transmitted toward the other end, parallel to the traveling direction of light at the interface between the clad material and the core material. When discontinuous or continuous or discontinuous ridges or groove-shaped minute irregularities that are partially or wholly inclined with respect to the traveling direction of light are formed from the light incident side to the light emitting side,
It has been found that the light is well transmitted and has a high brightness over the entire length. That is, in an optical transmission body having a core / clad structure, light is transmitted while being totally reflected at the interface between the core material and the clad material, but if unevenness in the direction perpendicular to the traveling direction of the light is large, the light will be transmitted. Since the incident angle in the traveling direction becomes large, the light is emitted from the side surface, while if there is unevenness along the traveling direction of the light, the incident angle in the traveling direction of the light does not change, so the light is transmitted while repeating total reflection. It In addition, the unevenness is deviated from the traveling direction of light, such as the unevenness is oblique to the traveling direction of light,
Alternatively, when the unevenness in the traveling direction of light is discontinuous, the incident angle changes at the starting point and the ending point of the groove, so that the light having a large incident angle among the transmitted light is gradually emitted to the outside of the optical transmission body. Found out. For this reason, unevenness is provided along the light traveling direction at the interface between the core material and the clad material, and the unevenness is made discontinuous, or incompleteness such as inclination or fluctuation is given to the light traveling direction. By,
The inventors have found that the optical transmission property in the length direction (light traveling direction) can be secured, the peripheral surface emission brightness is high, and the light can be emitted relatively uniformly over the entire length, and the present invention has been completed. It is a thing.

The present invention will be described in more detail below. The optical transmission body of the present invention comprises a transparent core material and a clad material having a refractive index lower than that of the core material, and light is incident from one end of the core material. In addition, in the optical transmission body in which the incident light is transmitted toward the other end, with respect to the discontinuity parallel to the traveling direction of the light or the traveling direction of the light at the interface between the clad material and the core material. Continuous or discontinuous ridges and concave groove-shaped minute irregularities that are partially or wholly inclined are formed from the light incident side to the light emitting side.

FIG. 1 shows an example of the optical transmission medium of the present invention. Figure 1
In the above, 1 is a transparent tubular clad material, 2 is a transparent core material with which the clad material 1 is filled, and 3 is a sealing plug.

Here, as the material for forming the hollow tubular clad material 1, it is preferable to use a flexible material such as plastic or elastomer, which can be molded into a tube and has a low refractive index. . Specific examples thereof include polyethylene, polypropylene, polyamide, polystyrene, ABS, polymethylmethacrylate, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyvinyl alcohol, polyethylene-polyvinyl alcohol copolymer. Polymer, fluororesin, silicone resin, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer, butyl rubber, halogenated butyl rubber, chloroprene rubber, acrylic rubber, EPDM, acrylonitrile-butadiene copolymer, fluororubber, Silicon rubber etc. are mentioned.

Among these, silicone type polymers and fluorine type polymers having a low refractive index are particularly preferable. Specifically, silicone type polymers such as polydimethylsiloxane polymer, polymethylphenylsiloxane polymer and fluorosilicone polymer, and polytetrafluoroethylene (P
TFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFE), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-ethylene Copolymer (ETFE), polyvinylidene fluoride, polyvinyl fluoride, vinylidene fluoride-trifluoroethylene chloride copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-propylene hexafluoride- Examples thereof include tetrafluoroethylene terpolymer, tetrafluoroethylene propylene rubber, and fluorine-based thermoplastic elastomer. These materials can be used alone or as a mixture of two or more kinds.

Further, the clad material may be a gas such as air, in which case the optical transmission body is substantially composed of a core material.

On the other hand, as the core material 2, a solid, liquid or fluid transparent material having a higher refractive index than the clad material is used.

In this case, an acrylic resin or a methacrylic resin is preferably used as the solid transparent material, and examples thereof include alkyl acrylates such as methyl acrylate and methyl methacrylate, homopolymers and copolymers of alkyl methacrylates, and monomers and co-polymers thereof. The thing which copolymerized other acrylate and methacrylate which can obtain a transparent polymer which can be polymerized can be mentioned.

Specific examples of the liquid or fluid transparent material include aqueous solutions of inorganic salts, polyhydric alcohols such as ethylene glycol and glycerin, silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane,
Hydrocarbons such as polyethers, polyesters, liquid paraffin, halogenated hydrocarbons such as trifluorochloroethylene oil, phosphoric acid esters such as tris (chloroethyl) phosphate and trioctylphosphate, polymer solutions prepared by diluting the polymer with an appropriate solvent. Is mentioned.

The sealing plug 3 can be used even when the core material 2 is solid, but it is necessary especially when the core material 2 is liquid or fluid, and in this case, a window material for light. The material forming the sealing plug 3 needs to be transparent, and specifically, the material of the sealing plug 3 is an inorganic material such as quartz glass, multi-component glass, sapphire, or quartz. Glass, polyethylene, polypropylene,
ABS resin, acrylonitrile-styrene copolymer resin,
Styrene / butadiene copolymer, acrylonitrile / styrene copolymer resin, styrene / butadiene copolymer, acrylonitrile / EPDM / styrene terpolymer, styrene / methyl methacrylate copolymer, methacrylic resin, epoxy resin, polymethylpentene, Allyl diglycol carbonate resin, spirane resin, amorphous polyolefin, polycarbonate, polyamide, polyarylate, polysulfone, polyallylsulfone, polyethersulfone, polyetherimide, polyimide,
Examples include organic glass and plastic transparent materials such as polyethylene terephthalate, diallyl phthalate, fluororesins, polyester carbonates and silicone resins. Among these, quartz glass, Pyrex glass,
Inorganic glass such as multi-component glass is excellent not only in transparency but also in heat resistance and is chemically stable. Therefore, the core material 2 in contact with the end face 3a and the gas and moisture in contact with the end face 3b are used. It does not chemically react with either, and can provide excellent performance in the long term.

If transparency is not required, metal or ceramics can be used.

The optical transmission medium of the present invention is not particularly limited, but usually the cladding material has an outer diameter of 3 to 110 m.
It can be formed in a cylindrical shape having a length of about m and a length of about 1 to 100 m. Further, it may be formed in a triangular shape, a prismatic shape, a plate shape, etc. other than the cylindrical shape.

In the optical transmission body of the present invention, as shown in FIGS. 2 and 3, a discontinuity a or light parallel to the traveling direction of light (axial direction of the clad material) is formed at the interface between the clad material and the core material. The continuous b or discontinuous c ridges and concave groove-shaped minute concaves and convexes that are partially or wholly inclined with respect to the traveling direction are provided from the light incident side d to the light emitting side e. The fine irregularities include various shapes such as a wedge shape, a groove shape, a trapezoidal shape, and a hemispherical cross-sectional shape, and a shape in which two or more kinds of these are combined can be used.

The average roughness in the circumferential direction (R
a) is preferably 0.05 to 20 μm, and particularly preferably 0.1 to 10 μm. Further, it is desirable that the average roughness in the light traveling direction of the fine irregularities is small, and it is preferably 0.01 to 10 μm, and particularly preferably 0.01 to 1 μm.

When the ridges and the groove-shaped minute irregularities are discontinuous, the average length is not particularly limited, but is 1 to 50.
It is preferably mm.

The fine irregularities may be provided on either the core material or the clad material, but are usually formed on the clad material.
However, when the clad material is gas, it is formed as a core material.

In the case of forming the above-mentioned ridges and groove-like minute irregularities on the inner peripheral surface of a hollow tubular clad material, for example, the following method may be mentioned. (1) The material of the clad material is extruded using an extrusion die having a desired uneven shape. (2) The material of the clad material is extruded into a hollow tube having a flat inner peripheral surface, and irregularities are formed by utilizing the temperature difference between the inside and the outside of the hollow tube during the cooling process. In this case, since the extrudate is cooled from the outside, the inside is subjected to stress and is strained, and undulations and cracks occur on the inner surface of the extrudate. (3) A needle-like protrusion that can be inserted and removed is provided on the inner pipe side of the extrusion die. In this case, the depth of the protrusions and recesses formed on the inner peripheral surface of the hollow tubular extruded product can be changed by changing the depth of the protrusions into and out of the hollow tubular extruded product. The brightness can be controlled by changing these.

It is possible to further improve the uniformity of the brightness in the traveling direction of the light by increasing the number of ridges and grooves and the number of minute irregularities in the vicinity of the light source and increasing the number thereof in the distance.

The thus obtained optical transmission body of the present invention is suitably used for applications such as an optical transmission tube having brightness over the entire length, a backlight of a liquid crystal display screen in a computer and the like.

[0026]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1] FEP having a wall thickness of 0.5 mm was extruded to obtain a tube (length 10 m) having an inner diameter of 12 mm and an outer diameter of 13 mm. The average roughness (Ra) of the inner peripheral surface of the tube in the light traveling direction was 0.70 μm, the Ra in the circumferential direction was 7 μm, and the average length of the groove was about 5 mm.

The FEP tube obtained above was filled with trioctyl phosphate as a core material, and then both ends were sealed with quartz rods to manufacture an optical transmission tube.

[Embodiment 2] An optical transmission tube (length 20 m) was used in the same manner as in Embodiment 1 except that the Ra in the circumferential direction of the FEP tube was set to 1.5 μm and the number of grooves was reduced. Was produced.

[Comparative Example 1] Example 1 except that an FEP tube (inner diameter 12 mm, outer diameter 13 mm) having a smooth inner peripheral surface with Ra of 0.03 mm in the light traveling direction and the circumferential direction was used as the clad material. Similarly, a light transmission tube (length 20
m) was prepared.

[Comparative Example 2] Ra in the light traveling direction and the circumferential direction was 0.6 mm, and the inner peripheral surface was uniformly roughened F.
An optical transmission tube (length 10 m) was produced in the same manner as in Example 1 except that the EP tube (inner diameter 12 mm, outer diameter 13 mm) was used as the clad material.

[Comparative Example 3] Ra in the traveling direction of light is 0.5.
2 μm, Ra in the circumferential direction is 0.46 mm, and an FEP tube (inside diameter 12
mm, the outer diameter was 13 mm), and an optical transmission tube (length 10 m) was produced in the same manner as in Example 1 except that the clad material was used.

Light (metal high-delo lamp, 150 W) was incident from one end of the light transmission tube obtained above, and the brightness at a predetermined point from the light source was measured. The results are shown in FIG. 4 by straight lines A (Example 1), B (Example 2), C (Comparative Example 1), D (Comparative Example 2) and E (Comparative Example 3).

From FIG. 2, it can be seen that in Example 1, a high peripheral brightness of the light transmission tube is obtained, and the uniformity of brightness is significantly improved. In Example 2, the number of grooves is reduced, that is, It can be seen that the brightness can be increased while maintaining the brightness uniformity by reducing the Ra value in the circumferential direction. On the other hand, in Comparative Example 1, since the inner peripheral surface of the clad material is smooth, peripheral surface emission brightness is low, and in Comparative Example 2 in which the inner peripheral surface is uniformly roughened, the light source is used as a light source. It can be seen that, although the peripheral surface emission brightness is extremely high in the vicinity, the peripheral surface emission brightness sharply decreases as the distance from the light source increases. Further, it is understood that in Comparative Example 3 using the clad material having irregularities in the circumferential direction, the uniformity of the peripheral surface emission luminance is further deteriorated as compared with Comparative Example 2.

Example 3 Transparent PMMA having a thickness of 5 mm
In a flat plate-like optical transmission body having an air transmission layer as a light transmission portion and an air layer as a clad material, grooves having a depth of 5 μm and a width of 100 μm are formed at 5 mm intervals at the interface with the air layer in the light traveling direction, and the same as above And measured the side emission brightness,
A uniform emission luminance distribution was obtained in the light traveling direction.

[0036]

According to the present invention, it is possible to obtain an optical transmission body which has a uniform and high luminance over the entire length while ensuring the light transmission property and which can be safely used even in an environment such as underwater. You can

[Brief description of drawings]

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

FIG. 2 is a plan view illustrating an example of minute unevenness according to the present invention.

FIG. 3 is a plan view illustrating another example of the minute unevenness of the present invention.

FIG. 4 is a graph showing the relationship between the distance from the light source and the brightness in the optical transmission bodies obtained in Examples of the present invention and Comparative Examples.

[Explanation of symbols]

 1 clad material 2 core material a minute unevenness b minute unevenness c minute unevenness

Claims (1)

[Claims] 1. A transparent core material and a clad material having a refractive index lower than that of the core material. Light is incident from one end of the core material, and the incident light is transmitted toward the other end. In the optical transmission body, a discontinuous ridge parallel to the light traveling direction or a continuous or discontinuous ridge partially or wholly inclined with respect to the light traveling direction is formed at the interface between the clad material and the core material. An optical transmission body, characterized in that concave and convex minute irregularities are formed from a light incident side toward a light emitting side.