JPH08184723A - Optical transmission pipe - Google Patents

Abstract

PURPOSE: To provide an optical transmission pipe capable of preventing not only the deterioration of light transmission characteristic caused by air bubbles formed in a core because of temperature change but also creep under a high temperature condition. CONSTITUTION: A clad 2 is provided by welding clad material on the inner surface of a metallic pipe 1 having strength enough to prevent the expansion of the clad 2 or forming a coating film by using the clad material, and the core 3 is obtained by filling the clad 2 with liquid or fluid core material having a higher refractive index than the clad material, then window materials 4 and 4 are fitted and fixed at both ends of the metallic pipe 1, and further stopper type bases 5 and 5 are provided on the outer peripheral surfaces of both ends of the metallic pipe 1 and the window materials 4 and 4 are fixed as necessary, thereby producing the optical transmission pipe A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission pipe that emits light that is incident on one end of a metal pipe and is transmitted through the pipe, and emits the light from the other end.

[0002]

2. Description of the Related Art A liquid type optical transmission tube B using a conventional flexible clad material is as follows.
Generally, as shown in FIG. 3, a core 3 made of a transparent liquid or fluid material (core material) and a clad 2 made of a flexible material (clad material) having a refractive index lower than that of the core 3,
It is composed of window members 4 and 4 made of a transparent material and fitted in both ends of the clad 2. In the case of such an optical transmission tube B, the core material and the clad material have greatly different coefficients of thermal expansion with respect to temperature changes, so that the internal pressure of the optical transmission tube B increases under high temperature conditions as shown in FIG. (Refer to the arrow in the inside), the clad 2 expands, but after that, when the temperature starts to decrease, the volume of the core 3 becomes smaller than the inner volume of the clad 2. Therefore, as shown in FIG. Permeate (see the arrow in the figure) to generate air bubbles C in the core 3 and deteriorate the light transmission characteristics of the light transmission tube B. Moreover, if the optical transmission tube B is left under high temperature conditions, the clad 2 continues to expand as described above, and creep occurs in the clad 2.

The present invention has been made in view of the above circumstances, and not only can prevent air bubbles from being generated in the core due to temperature change to deteriorate the light transmission characteristics, but also prevent creep under high temperature conditions. It is an object of the present invention to provide an optical transmission pipe that does.

[0004]

In order to achieve the above object, the present invention provides a metal pipe, a clad attached to the inner surface of the metal pipe, and a liquid or fluid core having a refractive index higher than that of the clad. And a window member fixed to both ends of the metal pipe, the metal pipe having a strength capable of preventing expansion of the clad.

In this case, it is more preferable that the clad is formed by fusing a clad material on the inner surface of the metal pipe or forming a coating on the inner surface of the metal pipe by the clad material.

[0006]

According to the present invention, the outermost shell of the optical transmission pipe is a metal pipe, and the coefficient of thermal expansion of metal is smaller than that of the core material and the clad material with respect to temperature change, and the metal pipe hinders the expansion of the clad. Since the clad can expand to some extent under the high temperature condition because it has the strength of only, it does not expand as described above. Further, in the case of metal, since gas does not permeate, air bubbles do not occur in the core even if the core shrinks more than the clad as the temperature decreases.

Here, in the case where the clad material is fused on the inner surface of the metal pipe or the coating is formed on the inner surface of the metal pipe by the clad material and the clad is attached to the inner surface of the metal pipe,
Since the adhesion between the metal pipe and the clad is good, expansion of the clad under high temperature conditions is further suppressed.

According to the optical transmission pipe of the present invention, the light from the light source is refracted at the interface between the window material on the one end side of the metal pipe and the air, and enters the window material from one end of the window material. Further, the light is refracted at the interface between the window material and the core and enters the core. Since the core has a higher refractive index than the clad, light is repeatedly totally reflected at the interface between the core and the clad. Therefore, the incident light from the light source is transmitted through the light transmission pipe, reaches the other end of the metal pipe, passes through the window member on the other end, and is emitted from the light transmission pipe to emit light.

[0009]

The present invention will be described below based on the embodiments shown in the drawings, but the present invention is not limited to the following embodiments.

FIG. 1 shows a part of an optical transmission pipe A according to a first embodiment of the present invention. This optical transmission pipe A has an outermost metal pipe 1, a clad 2 fused to the inner surface of the metal pipe 1, a core 3 filled in the clad 2, and fitted at both ends of the metal pipe 1, respectively. Fixed window material 4,
4 and bases 5 and 5 which are respectively provided around both ends of the metal pipe 1 and fix the window members 4 and 4 to the metal pipe 1.

The metal pipe 1 of this embodiment has an inner diameter of 11φ.
Although the outer diameter is a copper pipe having a diameter of 13φ, the thickness and the kind of metal of the metal pipe 1 are not limited as long as the metal pipe 1 has strength enough to prevent expansion of the clad 2 under high temperature conditions. Pipe thickness 0.5mm or more, especially 1-2
A metal pipe such as aluminum, SUS, brass, copper or iron having a size of mm is suitable.

The clad 2 of this embodiment was prepared by inserting a 0.5 mm thick tetrafluoroethylene-hexafluoropropylene copolymer (FEP) tube into the metal pipe 1 and then applying internal pressure at high temperature. The tube is fused to the inner surface of the metal pipe 1 and attached to the inner surface of the metal pipe 1.

As a means for attaching the clad 2 to the inner surface of the metal pipe 1 as described above, the clad 2 is attached to the metal pipe 1.
The means is not particularly limited as long as it can adhere to the inner surface of
Means or adhesive not only for fusing the tube of the clad material as described above, but also for coating and drying the clad material solution or liquid clad material diluted with an appropriate solvent on the inner surface of the metal pipe 1 to form a film. Means of using are also useful.

The clad material may be any material that can be fused to a metal, can be formed into a film, or can be bonded with an adhesive and has a low refractive index.
Specific examples thereof include polyethylene, polypropylene, polymethylmethacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyvinyl alcohol, polyethylene-polyvinyl alcohol copolymer, silicone rubber, silicone resin, Fluorine rubber, fluorine resin, butyl rubber, halogenated butyl rubber, chloroprene rubber, acrylic rubber, E
Examples thereof include PDM, acrylonitrile-butadiene copolymer and fluoroacrylate (poly). Of these, silicone resins, silicone rubbers, fluororesins, fluororubbers and fluoroacrylates (poly) are particularly preferred. Specifically, silicone polymers such as polydimethylsiloxane polymer, polymethylphenylsiloxane polymer, fluorosilicone polymer, polytetrafluoro Ethylene (PTFE), FEP, tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFE),
Polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene fluoride, polyvinyl fluoride, vinylidene fluoride-trifluorochloroethylene copolymer, vinylidene fluoride hexafluoride Propylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene propylene rubber, fluorine-based thermoplastic elastomer and the like. These materials may be used alone or in combination of two or more.

The core 3 of this embodiment is formed by using trioctyl phosphate (TOP) having a refractive index of 1.45 as a core material and filling the clad 2 with the core material.

The core material may be any material used as a material for a liquid or fluid core, for example, polyols such as polyethylene oxide, polypropylene oxide, glycerin, etc., polyol esters, polyol ethers, chloroethylene phosphate. , Phosphoric acid esters such as dichloropropyl phosphate, liquid paraffin, fluorine oil, silicone oil, polyisobutylene, polysiloxane modified polyether, aqueous solution of inorganic salt, polymer solution obtained by diluting polymer with a suitable solvent, etc. are used. These materials may be used alone or in combination of two or more.

The window members 4 and 4 of this embodiment are made of Pyrex glass having an outer diameter of 10φ, and are inserted into both ends of a metal pipe 1 having a cladding 2 fused to the inner surface thereof, and electromagnetically heated to form the cladding 2. It is fixed to each end of the metal pipe 1 by fusion bonding to the inner surface of the metal pipe 1.

As the window member 4, quartz glass, Pyrex glass, multi-component glass, sapphire, inorganic glass such as crystal, polyethylene, polypropylene, ABS resin, acrylonitrile / styrene copolymer resin, styrene / butadiene copolymer, acrylonitrile / EPDM / styrene terpolymer, styrene / methyl methacrylate copolymer, (meth) acrylic resin, epoxy resin, polymethylpentene, allyl diglycol carbonate resin, spirane resin, amorphous polyolefin, polycarbonate, polyamide, polyarylate, polysulfone ,
Examples include organic glass and plastic transparent materials such as polyallyl sulfone, polyether sulfone, polyetherimide, polyimide, polyethylene terephthalate, diallyl phthalate, fluororesin, polyester carbonate, and silicone resin. Among them, the inorganic glass such as quartz glass, Pyrex glass, and multi-component glass is excellent not only in transparency but also in heat resistance and is chemically stable, so that the core 3 contacted at the inner end face thereof and the outer side thereof It does not chemically react with the gas or moisture that comes into contact with the end faces, and can provide excellent performance over a long period of time.

The window members 4 and 4 are fixed to each end of the metal pipe 1 by being fused to the claddings 2 on the inner surfaces of both ends of the metal pipe 1 as described above. In the case of the example, the bases 5 and 5 are more firmly fixed. The base 5 is a stopper type base made of SUS, and is composed of a base body 5a of a tubular body and a flange-shaped window member locking portion 5b integrally projecting on an inner edge of one end thereof. The inner surface of 5a is threaded. In this case, the peripheral surfaces of both ends of the metal pipe 1 are pre-threaded so as to be screwed into the caps 5 and 5. And the base body 5
F on the internal thread portion of the inner surface of a and the inner surface of the window material locking portion 5b.
The EP coating is applied, and the window material 4 is heat-fused at the same time when the window material 4 is fused. It should be noted that instead of the FEP coating, it may be taped with a fusion-bondable sealing tape or a metal foil (plastic metal such as Cu or lead). Other sealing methods include:
Adhesives, solders, welding, etc. can also be used.

The window member 4 may be fixed by either one of the above-mentioned fusion bonding to the clad 2 and the fixing by the base 5. A method of fixing with a caulking mouthpiece is also useful. Further, the caulking mouthpiece 5 may be omitted and the caulking may be performed directly from the outside of the metal pipe 1.

The transmission loss of the optical transmission pipe A having the above structure was 200 dB / km. Also, this optical transmission pipe A
After the heat cycle from 60 ° C. to −20 ° C., air did not enter the core 3 and good light transmittance was maintained.

Incidentally, as in the second embodiment shown in FIG.
In the first embodiment, as a method of treating the sealed end of the light transmission pipe A, the window material locking portion 5b of the base 5 and the window material 4 are further processed.
When the sealing material 6 having adhesiveness and adhesiveness is inserted into both the window material 4 and the base 5 in the space formed by the outer end surface of the optical transmission pipe A, the hermeticity at the end portion of the optical transmission pipe A is further enhanced. , More effective.

Examples of the encapsulating material 6 include transparent adhesives such as epoxy resin, acrylic resin, and silicon resin; transparent materials such as low-melting point glass and inorganic encapsulating material such as sol-gel glass cured product.

[0024]

According to the present invention, the outermost shell of the optical transmission pipe is made of a metal pipe having a strength to prevent expansion of the clad, so that the expansion of the clad under high temperature conditions is suppressed and the core changes due to temperature change. It is possible not only to prevent air bubbles from being generated inside but to reduce the light transmission characteristics, but also to prevent the creep of the clad under high temperature conditions, thus providing an optical transmission pipe with excellent optical transmission efficiency. Obtainable. Here, it is more effective if the clad is fused to the inner surface of the metal pipe or is attached to the inner surface of the metal pipe by the clad material coating on the inner surface of the metal pipe.

The optical transmission pipe of the present invention is, for example, -20 to 20.
Especially, as a light transmission means for a street light, a vehicle, etc., which is installed in a predetermined shape in an environment where the temperature changes drastically from high temperature to low temperature such as heat cycle of about 60 ° C. and then from low temperature to high temperature. It is useful.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating the configuration of an optical transmission pipe according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of an optical transmission pipe of a second embodiment of the present invention.

FIG. 3 is a schematic sectional view illustrating an example of a conventional light transmission tube.

FIG. 4 is a schematic cross-sectional view of the light transmission tube under high temperature conditions.

FIG. 5 is a schematic cross-sectional view of the light transmission tube when the temperature drops.

[Explanation of symbols]

 A Optical transmission pipe 1 Metal pipe 2 Clad 3 Core 4 Window material

Claims (3)

[Claims] 1. A metal pipe, a clad attached to an inner surface of the metal pipe, a liquid or fluid core having a refractive index higher than that of the clad, and a window material fixed to both ends of the metal pipe. The optical transmission pipe, wherein the metal pipe has a strength capable of preventing expansion of the clad. 2. The optical transmission pipe according to claim 1, wherein the clad is formed by fusing a clad material on the inner surface of the metal pipe. 3. The optical transmission pipe according to claim 1, wherein the clad has a coating formed on the inner surface of the metal pipe by a clad material.