JPH01109310A - Plastic optical fiber connecting tube - Google Patents

Abstract

PURPOSE:To easily and surely connect plastic optical fibers with a small connection loss by using a connector formed by putting a transparent adhesive agent into a connecting tube. CONSTITUTION:The low-viscosity adhesive agent or resin raw material is stably held in the joining tube 1 by enclosing the transparent adhesive agent 2 with films 3. The films 3 are ruptured by the insertion pressure of the fibers. The refractive index of the films 3 is equaled or approximated to the refractive index of the adhesive agent after curing to prevent the increase in scattering and absorbing even when the films remain. The cured film of the adhesive agent is effective and the loss is additionally decreased if the raw material resin of the core is used for the adhesive agent. The smooth insertion is assured if a discharge hole for the excess resin is provided near the joint part at the time of insertion. The intrusion of air bubbles is effectively prevented by finely drawing a part of the joint tube toward the center. The use of a heat-shrinkable tube is a good alternative. The adhesion by using the adhesive agent of a curing type by mixing is successively executed by partitioning the components by a film and rupturing the partition by insertion of the fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a connecting tube for connecting plastic optical fibers.

[Conventional technology]

Conventional bonding methods include a method of abutting fibers in a cylindrical sleeve and injecting adhesive to harden and bond the fibers, as described in JP-A-51-5031;
As described in No. 11, there was a method of connection using a liquid having the same refractive index as the core member, a heat shrink tube, and a cladding film.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, as a connecting step, a fiber is inserted into a connecting pipe, and an adhesive is injected into the bonded portion and hardened. Alternatively, the end face of the fiber may be coated with a resin having a refractive index equivalent to that of the core, and the fiber may be inserted into a connecting pipe and joined within the pipe. This process is complicated and unsuitable for on-site work, and there are also problems in that dust, air bubbles, etc. get mixed in during the process, increasing connection loss.

An object of the present invention is to provide an optical fiber connector that can connect plastic optical fibers easily, reliably, and with less connection loss.

[Means for solving problems]

The above object is achieved by using a transparent adhesive in the joint tube. To do this, you can create a space covered with a thin film inside the pipe and inject the transparent adhesive there.Also, you can partially cure both sides of the transparent adhesive injected into the pipe to form a thin film. It is possible. This membrane is strong enough to be ruptured by fiber insertion or insertion pressure.

Further, if the film is a transparent film, preferably a cured adhesive, which has a refractive index equal to or similar to the refractive index when the transparent liquid adhesive is cured, reduction in adhesion loss can be achieved.

[Effect]

By surrounding the transparent adhesive with a film, low viscosity adhesive,
Alternatively, even resin raw materials can be stably held within the joint tube. Furthermore, by making the fiber strong enough to be broken by the insertion pressure of the fiber, the fiber can be easily inserted to the connecting portion at the center of the connecting tube. Furthermore, by making the film have a refractive index equal to or similar to the refractive index of the cured adhesive, it is possible to suppress an increase in scattering and absorption even if the torn film remains at the connection site.

This can be further improved by using a cured transparent adhesive as a film. Further, by using the raw material resin of the main component as the transparent adhesive, loss can be further reduced.

In addition, in terms of the structure, a hole for discharging excess resin during insertion is provided near the joint, allowing smooth insertion. Further, in order to prevent air bubbles from being mixed in during insertion, the joining tube may have a shape in which a portion thereof is narrowed toward the center. In addition, when using a mixed curing type transparent adhesive consisting of a plurality of components, each component is separated by a membrane and placed inside a tube, and the membrane is broken by inserting a fiber and the mixture is cured. Finally, a heat-shrinkable tube is used as the joint tube, and after the fiber is inserted, the tube is shrunk to align the fiber axes and remove excess transparent adhesive and air bubbles.

〔Example〕

Example 1 This example will be explained with reference to FIG. Reference numeral 1 denotes a coupling tube, which is made of a tube having an inner diameter almost equal to the plastic optical fiber core diameter and a refractive index equal to or close to the refractive index of the cladding. 2 is a methacrylic monomer raw material that is a raw material for the core material. 3 is a thin film for holding this raw material.

This is made by using a resin raw material mixed with an ultraviolet curing agent, and using a photomask to irradiate and cure only those areas with ultraviolet rays. With such a configuration, the resin raw material can be transported without leaking to the outside. In addition, in use, a bare fiber with a tapered end was inserted from both sides to the connection part by tearing the membrane, and the connection was made by curing it with ultraviolet irradiation. At that time, a connection loss of 1 dB was obtained at the junction.

Example 2 The present example will be explained with reference to FIG. To the connecting pipe.

The same one as in Example 1 was used. The thin film 3' and the partition film 4 are paraffin films. 5 and 6 are liquids A and B, respectively, of two-liquid hot-melting adhesives.

For connection, first insert a fiber core with a slightly tapered end from the left side of the figure (3' side) until it breaks through the membrane in 4, and mix adhesive A in 5 and adhesive liquid B in 6 to some extent. After that, I inserted the other fiber from the right side, mixed the two liquids completely, allowed them to harden, and was able to connect both fibers.

Example 3 This example will be explained using FIG. 3. 1 joint pipe, 2
The same transparent adhesive as in Example 1 and the thin film in 3 were used. The joint tube 1 is preliminarily bonded or fused to the optical fiber 7 to form an integral body. By inserting another fiber and core into this from the same left side and irradiating it with ultraviolet rays or heating it, the fibers could be easily connected.

〔Effect of the invention〕

According to the invention: - inserting the fiber into the connector;

Easy operation 9 For example, fibers can be connected by heating, UV irradiation, mixing, etc., so fibers can be easily connected on site, reducing man-hours and working time. There is. In addition, since the work is simplified, it is possible to avoid dust, air bubbles, etc. from entering the splicer during one work, which has the effect of lowering connection loss.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views of an optical fiber connector according to an embodiment of the present invention, and FIG. 3 is a partially sectional view of an embodiment of the present invention.

Claims (1)

[Claims] 1. The fiber is inserted into a tube having an inner diameter slightly larger than the outer diameter of the optical fiber, and the two are bonded inside the tube with a transparent adhesive having the same or almost the same refractive index as the core. holding the transparent adhesive inside the tube,
A resin optical fiber connecting tube characterized by having at least one thin film that is easily torn by fiber insertion and insertion pressure. 2. The resin optical fiber connecting tube according to claim 1, wherein the refractive index of the thin film is equal to or almost close to the refractive index of the adhesive when it is cured. 3. The resin optical fiber connecting tube according to claim 1 or 2, wherein the adhesive is the same as the resin raw material of the core material of the resin optical fiber to be connected. 4. The resin optical fiber connecting tube according to claim 1, 2, or 3, wherein the thin film is made of the same resin as the adhesive. 5. Claims 1 to 5, characterized in that the tube near the joint part has a hole for letting excess adhesive out, and the hole is covered by the thin film. The resin optical fiber connecting tube according to any one of Item 4. 6. The transparent adhesive is a mixture of multiple components and cured, and each component is injected into spaces corresponding to the number of components formed by the thin film. A resin optical fiber connecting tube according to any one of claims 1 to 5. 7. A resin optical fiber connecting tube according to any one of claims 1 to 6, characterized in that the connecting tube is heat-shrinkable.