JPH0843662A - Optical transmission tube - Google Patents

Abstract

PURPOSE:To maintain the functions of an optical transmission tube without being impaired over a long period of time by preventing pull-out of the sealing plugs of a core from a clad even if the inside pressure of the core is high. CONSTITUTION:Cylindrical metallic sleeves 4 are respectively fitted to the outer peripheral parts at both ends of the clad 1 of the optical transmission tube formed by packing the liquid or fluid transparent core 2 having a refractive index higher than the refractive index of the tubular clad 1 into this clad 1 and closing the apertures at both ends of the clad 1 with the sealing plugs 3 so as to cover these outer peripheral parts. These two sleeves are respectively caulked 5 to compress and deform the sleeves 4 and the outer peripheral parts at both ends of the clad 1 at a caulking rate of 10 to 80% over the one circumference thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission tube in which a core material is in a liquid state or a fluid state, and more specifically, liquid leakage and oozing out of the core material and removal of sealing plugs at both ends are reliably prevented. Therefore, the present invention relates to an optical transmission tube in which the function of the optical transmission tube is not impaired for a long period of time.

[0002]

2. Description of the Related Art Conventionally known optical fibers include inorganic glass optical fibers such as quartz glass and multi-component glass, and plastic optical fibers such as polymethylmethacrylate and polystyrene. It is an all-solid-state optical fiber in which both the core material and the clad material are solid materials.

Although these optical fibers have excellent characteristics, their flexibility is limited, and in order to increase the diameter for transmitting a large amount of light, it is necessary to bundle a large number of fibers having a diameter of 10 to 1000 μm. There is. In this case, no matter how densely the optical fibers are bundled, since voids remain between the fibers, the effective light receiving area when light is incident becomes narrow, the efficiency deteriorates, and the cost becomes very high. In contrast to these all-solid-state optical fibers, there are optical fibers in which the core material is liquid as described in, for example, U.S. Pat. Nos. 4,093,382 and 3,814,497. These liquid-based optical fibers have a flexible hollow tubular clad filled with a liquid core having a refractive index higher than that of the clad, and openings at both ends of the clad are sealed with window materials. , It is easy to increase the diameter,
It is possible to make the effective light-receiving area wide and highly efficient, and also excellent in economic efficiency.

However, although the liquid type optical fiber as described above has excellent characteristics, there is a problem that the core liquid leaks from the sealing portion and the window material comes off during use.

Therefore, Japanese Patent Application Laid-Open No. 62-266504 proposes a sealing method for solving these problems. According to this sealing method, as shown in FIG. 1, a sealing film or a sealing plug that covers the openings at both ends of the clad is bonded to both ends of the clad by a liquid-tight method or the like. It is possible to prevent leakage of liquid and invasion of gas from the outside.

However, according to this method, in many cases, for example, in the case of a clad material made of fluororesin, sufficient adhesion cannot be secured, and when the internal pressure of the core liquid in the tube is high, the window material is not pulled out. There was a problem that sufficient bonding could not be obtained to prevent this.

The present invention has been made by paying attention to such a problem, and it is possible to surely prevent liquid leakage and oozing of the core material and the removal of the sealing plugs at both ends, and therefore the optical transmission function. It is an object of the present invention to provide an optical transmission tube that is not damaged for a long period of time.

[0008]

Means for Solving the Problems and Actions The inventors of the present invention have conducted extensive studies in order to achieve the above object, and as a result, have found that a liquid or fluid liquid having a refractive index higher than that of the cladding is inside the tubular cladding. In an optical transmission tube in which a transparent core is filled and both ends of the clad are closed with sealing plugs, a cylindrical metal sleeve is fitted over the outer circumferences of both ends of the clad, and these are fitted together. It has been found that it is effective to crimp each of the sleeves and compressively deform the outer peripheral portions of both ends of the sleeve and the clad at a crimping rate of 10 to 80% over the entire circumference.

That is, the optical transmission tube has a thin clad thickness of, for example, 0.5 mm, and is difficult to be compressed and deformed because it is made of a resin material. On the other hand, since the sealing plug is usually glass, it is fragile and cannot be subjected to excessive compressive stress. In addition, if the outer periphery of the sealing plug is not smooth, the optical characteristics deteriorate, so that it is not possible to provide the outer periphery of the sealing plug with a wavy shape for preventing slipping. Therefore, as a result of various studies on a caulking structure suitable for such an optical transmission tube, a caulking method of deforming by pressing a metal sleeve with a width of 0.3 to 3 times the diameter of the sealing plug (zone (Caulking) or by adopting a caulking method (multi-stage caulking) that deforms by pressing multiple points of the metal sleeve in a ring shape, and further by setting the caulking rate to 10-80%, the sealing plug is damaged. The present invention has been accomplished by finding that the sealing plug is firmly fixed to the clad without being carried out, and that the sealing plug does not come out even if the internal pressure of the core is high.

The present invention will be described in more detail below. As shown in FIGS. 1 and 2, the optical transmission tube of the present invention has a refractive index higher than that of the cladding 1 inside the tubular cladding 1. Liquid or liquid transparent core 2
And the openings at both ends of the clad 1 are closed by sealing plugs 3, respectively. In this case, the cylindrical metal sleeve 4 covering the outer circumference of both ends of the clad 1 is used.
And the crimping portions 5 of both sleeves 4 are crimped, and the sleeve 4 and the outer peripheral portions of both ends of the clad 1 are compressed and deformed.

In this light transmission tube, at least one of the light-incident side sealing plugs 3 is made of a transparent material, the light incident from the sealing plugs 3 is transmitted to the core 2, and the clad 1 is further provided. When the other sealing plug 3 is made of a transparent material, the light is emitted from the other sealing plug 3 when the light is reflected by the other sealing plug 3 and is transmitted to the other end of the core 2.

Here, as the material for forming the hollow tubular clad 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 resin, 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 polymers and fluorine polymers having a low refractive index are particularly preferable. Specifically, silicone 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-trifluorochloroethylene 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.

On the other hand, as a material for forming the core 2, a liquid or fluid transparent material having a refractive index higher than that of the clad material is used. 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 core 2 is usually enclosed in the clad 1 at a pressure higher than atmospheric pressure in order to prevent entry of air or the like from the atmosphere.

When the sealing plug 3 is used as a window material for light, the material forming the sealing plug 3 needs to be transparent. Specifically, the material of the sealing plug 3 is ,
Quartz glass, Pyrex glass, multi-component glass, sapphire, inorganic glass such as quartz, 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, 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 not only transparent, but also excellent in heat resistance and chemically stable, so it is chemically compatible with the core that contacts at its inner end surface and the gas and moisture that contact at its outer end surface. It does not react mechanically and can provide excellent performance in the long term.

The infrared film and the ultraviolet film are required to be transparent so that they do not interfere with visible light and allow it to pass therethrough. For this reason, a metal film or the like should be thin in the angstrom order. The film thickness is selected so that light can pass through. Further, the infrared reflection or absorption agent and the ultraviolet reflection or absorption agent are those which achieve desired infrared rays, visible rays or ultraviolet rays by changing the thickness of the film in accordance with the wavelength to be cut. The thickness of the film for ultraviolet rays and the film for ultraviolet rays is thus selected according to the transparency and the wavelength to be cut.

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

In the present invention, the optical transmission tube may be coated with an appropriate coating material for the purpose of protecting it.

Here, the coating material can be selected from plastic, elastomer, metal, glass and inorganic materials.

Specifically, polyamide, epoxy resin,
Polymers such as polyvinyl chloride, polycarbonate, polystyrene, fluororesin, butyl rubber, halogenated butyl rubber, polyethylene, polypropylene, polyurethane, hydrochloric acid rubber, natural rubber, polyisoprene rubber, polybutadiene rubber, chloroprene rubber, acrylic rubber, EPDM, fluororubber The material can be coated, extruded, wrapped with a tape-shaped material, heat-shrinked or the like to cover the clad.

Further, metal materials such as SUS, aluminum, copper, iron, etc., or the above-mentioned polymer materials are pipe-shaped, bellows-shaped,
A clad filled with a core may be inserted into a spiral wire-shaped product. Furthermore, a metal material may be coated on the outer periphery of the clad by plating, vapor deposition, sputtering or the like to cover the metal film.

These coating materials can be used alone or as a composite with other materials.

The above-mentioned coating material can be provided not only for the purpose of protecting the light transmission tube but also for the purpose of blocking light or causing only the required portion to emit light. For example, when a hole is formed in a required portion of the above covering material or the portion is made transparent, light leaks out from the portion to form a large number of spot-shaped or line-shaped light emitters.

Thus, according to the present invention, as shown in FIGS. 1 and 2, the sealing plugs 3a and 3b are firmly attached to the clad 1, and even if the internal pressure of the core 2 is high. 3a,
In order to prevent 3b from coming off from the clad 1, cylindrical metal sleeves 4 and 4 are provided on the outer peripheral portions of both ends of the clad 1, respectively.
Are fitted and caulked, and the outer peripheral portions of both ends of the sleeves 4, 4 and the clad 1 are compressed and deformed over the entire circumference.

Here, the metal sleeves 4 and 4 may be formed of copper alloy such as stainless steel, aluminum, copper and brass, steel, titanium, nickel and the like. Among them, stainless steel, aluminum, copper and copper alloy are preferable. It is preferably used in terms of corrosion resistance, thermal conductivity, cost and the like.

This metal sleeve has an inner diameter larger than the sum D'mm of the diameter of the sealing plug and the thickness of the clad,
It is desirable that it is smaller than D ′ × 1.05 mm, and the length is usually 10 mm or more, more preferably 20 mm or more, and the maximum length is not particularly limited. It's about. Further, the wall thickness is preferably 0.1 to 5 times, especially 0.2 to 2 times the wall thickness of the clad. If this wall thickness is too thick, the clad may not be effectively compressed and deformed, and the sealing plug may come off or liquid may leak. The metal sleeve has a tubular shape corresponding to the shape of the end of the clad, but if necessary, a stopper 6 for preventing the removal of the sealing plug is attached to the outer end of the sleeve as shown in FIG. A pipe mounting step 7 may be provided.

The caulking of the metal sleeve is, as shown in FIG. 1, 0.3 to 3 Dm with respect to the diameter Dmm of the sealing plug.
m, particularly 0.5 D to 2 D mm in a zone crimping that pressurizes along the circumferential direction, or, as shown in FIG. 2, multi-step crimping that presses a plurality of metal sleeves spaced apart from each other in a ring shape. It is suitable.

In this case, the zone crimping method is particularly suitable when the metal sleeve is relatively plastically deformable, such as aluminum, copper or copper alloy.

When the multi-step crimping method is adopted, 2
It is preferable to crimp at more than three points, particularly at three or more points. In this case, the crimping width at each ring-shaped crimping point is 0.2 to 5 mm for plastically deformable ones such as aluminum, copper, and copper alloys. In particular, it is preferable that the width is 0.5 to 3 mm, and those that are less likely to be plastically deformed, such as stainless steel, have the width of 0.2 to 1 mm, and particularly 0.3 to 0.8 mm, which makes the clad effective. The sealing plug can be fixed to the clad by compressing and deforming.

Further, the crimping rate depends on the material of the clad and the metal sleeve, but is preferably in the range of 10 to 80%, and particularly 30 to 70% in the case of stainless steel or the like which is hard to be plastically deformed, More preferably 35-6
5%, 15 to 70%, and more preferably 25 to 65% in the case of those that are easily plastically deformed, such as aluminum, copper, and copper alloys.
Is preferred. If the crimping rate is high, the sealing plug will crack or the clad will be damaged.If the crimping rate is low, the internal pressure of the core will be high, and if the metal sleeve becomes hot, the sealing plug will come out or the core will leak. May occur.

The crimping rate is a value obtained from the following formula (see FIG. 4) and approximates the deformation rate of the clad.

[0033]

[Equation 1]

For crimping, for example, a die as shown in FIG. 5 (zone crimping) or FIG. 6 (multistage crimping) is used.
This can be done by using a crimping machine equipped with a plurality of these. It is preferable that the number is 4 or more, and more preferably 6 or more in order to uniformly crimp in the radial direction.

[0035]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 and Comparative Example 1 A tetrafluoroethylene-hexafluoropropylene copolymer (FEP) tube having an inner diameter of 12 mm and a wall thickness of 0.5 mm was used as a clad,
Uses methylphenyl silicone oil as the core,
A quartz rod having a diameter of 13 mm and a length of 50 mm was used as a sealing plug, Al having an inner diameter of 14.3 mm and a wall thickness of 0.85 mm was used as a metal sleeve, and a die (8 mm in width and 8 mm in the die shown in FIG. 1), and the die was uniformly pressed against the sleeve by hydraulic pressure to perform zone caulking to obtain an optical transmission tube having a zone caulking portion as shown in FIG.

Next, the light transmission tube was cut at a position about 30 cm from the tip of the metal sleeve, and 6 kg / cm from the open end.
The internal pressure of ² was applied, and the die was heated at 150 ° C. to check whether the sealing plug was pulled out and whether the core was leaked. The results are shown in Table 1.

[0038]

[Table 1]

[Example 2 and Comparative Example 2] Light having the same material as in Example 1 and Comparative Example 1 and crimped in three steps in the same manner as described above and having a crimped portion as shown in FIG. Got the transmission tube.

Next, in the same manner as above, it was examined whether or not the sealing plug was pulled out and the core was leaked. Table 2 shows the results.

[0041]

[Table 2]

[0042]

The optical transmission tube of the present invention is such that the sealing plug of the optical transmission tube is prevented from slipping out of the clad even when the internal pressure of the core is high. Therefore, the function of the optical transmission tube is long-term. It will not be damaged.

[Brief description of drawings]

FIG. 1 is a partially omitted sectional view showing an example of a light transmission tube of the present invention.

FIG. 2 is a partially omitted sectional view showing another example of the optical transmission tube of the present invention.

FIG. 3 is a partially omitted sectional view showing another example of the optical transmission tube of the present invention.

FIG. 4 is a partially omitted sectional view of an optical transmission tube for explaining a crimping rate.

FIG. 5 is a cross-sectional view showing an example of a die used for caulking.

FIG. 6 is a cross-sectional view showing another example of a die used for caulking.

[Explanation of symbols]

 1 clad 2 core 3 sealing plug 4 metal sleeve 5 caulking part

Claims (4)

[Claims] 1. A liquid or fluid transparent core (2) having a refractive index higher than that of the clad (1) is filled inside the tubular clad (1), and openings at both ends of the clad (1) are filled. In a light transmission tube obtained by closing the above with a sealing plug (3), a cylindrical metal sleeve (4) is fitted over the outer peripheral portions of both ends of the clad (1), respectively, and these sleeves are respectively fitted. An optical transmission tube characterized by being crimped (5), and the outer peripheral portions of both ends of the sleeve (4) and the clad (1) being compressed and deformed at a crimping rate of 10 to 80% over the entire circumference. 2. The metal sleeve (4) is made of aluminum, copper or a copper alloy, and the swaged portion (5) has a width of 0.3 to 3 times the diameter of the sealing plug (3) and extends over one round. The optical transmission tube according to claim 1, which is present. 3. The optical transmission according to claim 1, wherein the metal sleeve (4) is made of aluminum, copper, or a copper alloy, and a plurality of swaged portions (5) are formed at a plurality of points each having a width of 0.2 to 5 mm. tube. 4. The light transmission tube according to claim 1, wherein the metal sleeve (4) is made of stainless steel, and a plurality of swaged portions (5) are formed at a plurality of points over a circumference of a width of 0.2 to 1 mm.