JPH0345801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for connecting optical fiber cables, and particularly to handling of fiber cores during connection.

BACKGROUND OF THE INVENTION As shown in FIGS. 1 and 2, the most common structure of a fiber core 10 is one in which a primary coating 30 and a secondary coating 40 are provided on a glass fiber 20.

The primary coating 30 has the main purpose of maintaining the strength of the glass fiber 20 itself, and is, for example, a thin layer of urethane (see FIG. 1) or a modified silicone rubber layer.
2 and silicone rubber 34 (FIG. 2).

The secondary coating 40 is primarily intended to reduce or shatter the stress applied to the glass fiber 20, and is made of, for example, plastic (such as nylon) having a high Young's modulus.

A plurality of the above fiber core wires 10 are assembled and the outermost layer is covered with a jacket 52 to form an optical fiber cable 50.
(See Figure 5).

When connecting this optical fiber cable 50, the following work steps are usually performed: 1. Cutting out the fiber core: Remove the jacket and cut out the fiber core 10, allowing for an extra length of about 1 m.

2. Removal of coating: The secondary coating 40 and primary coating 30 at the end of the fiber core wire 10 are removed, and the glass fiber 20 is cut.

3. Connection: Connect the glass fibers 20 to each other by fixing them, for example, to a fusion device. Connectors may also be used.

4. Reinforcing the connection: There are ways to use heat shrink tubes, epoxy resin, silicone resin, etc.

5 Extra length processing: For example, make a loop in the fiber core 10,
There are methods such as winding it around a bobbin.

6 Connection of outer sheath 52: Take each step.

However, in the optical fiber cable 50,
Some do not have the secondary coating 40. For example, as shown in FIG. 3, there is also a structure in which only a primary coating 30 is provided on a glass fiber 20, that is, a structure in which fiber strands 12 are assembled.

If you try to connect such a cable using the above procedure, 1) the bare fiber 12 is thin and difficult to handle, 2) there is a risk of damaging the bare fiber 12, 3) especially if the primary coating 30 is coated with silicone rubber 3.
Products using No. 4 have problems such as being sticky and difficult to handle.

In addition, as shown in FIG. 4, inside the fiber core wire 10, a metal (such as aluminum) or hard plastic pipe is used as the primary coating 40, and a gap 42 is provided between it and the inner fiber wire 12. Some have a similar structure.

When connecting a fiber cable made of such a fiber core wire 10, during the step of pulling out the fiber core wire 10 in 1) above, the secondary sheathing 40 of the pipe is removed together with the outer sheath, and then the secondary covering 40 of the pipe is removed as described in 2) above.
Perform each of the following connection operations. Therefore, the work is difficult in this case as well, since a very thin fiber wire 12 with only a primary coating 30 provided on the glass fiber 20 is to be handled.

This invention makes it possible to solve the difficulty in handling the fiber wire 12 in the above-mentioned cases.

Structure of the Invention (1) An optical fiber cable 50 as follows: 1. A plurality of fiber wires 12 (FIG. 3) having a structure in which only a primary coating 30 is provided on a glass fiber 20 and no secondary coating is provided. Optical fiber cables assembled together and covered with a jacket 52 on the outside;
This relates to the connection of an optical fiber cable in which a plurality of fiber core wires 10 (FIG. 4) having a structure with a void 42 between them and a secondary sheath 40 are assembled, and an outer sheath 52 is covered on the outside thereof. (2) After removing the outer covering 52 and the secondary covering 40 and exposing the fiber strands 12 (FIG. 5), tightly cover each fiber strand with a heat shrink tube 60 ( 6), (3) Thereafter, the heat shrink tube 60 and the primary coating 30 are removed to expose the tip of the glass fiber 20.

The heat shrink tube 60 is made of, for example, crosslinked polyethylene.

Currently, the outer diameter of the most common fiber core 10 as shown in Figures 1 and 2 is approximately 0.9 mm, and the dimensions of the connection jig (V groove block, etc.) are also adjusted accordingly. It's made. Therefore, after covering with heat shrink tube 60 and shrinking, the outer diameter is 0.9
If the thickness is about mm, it is convenient because conventional jigs can be used as is.

The heat shrink tube 60 is placed over the entire length of each exposed fiber strand 12 (FIG. 6).

After that, only the heat shrink tube 60 and the primary coating 30 at the tip are removed, and the glass fiber 20 is exposed.
Subsequently, the glass fiber 20 is connected, the connection portion is reinforced, excess length is processed, and the outer sheath is connected.

All of these operations are performed on the fiber strand 12 covered with the heat shrink tube 60.

Therefore, the fiber wire 12 is no longer too thin and difficult to handle, and especially even wires using silicone rubber 34 for the primary coating 30,
It's not sticky and you don't have to worry about it getting damaged.

Effects of the Invention After removing the outer sheath and the secondary coating and exposing the fiber strands, a heat-shrinkable tube is closely covered over each fiber strand, and then the heat-shrinkable tube and the primary coating are removed. Since the tip of the glass fiber is exposed using the above method, even in the case of an optical fiber cable in which there is no secondary coating on the exposed fiber after removing the outer sheath and secondary coating, the above-mentioned method can be applied. Furthermore, fiber wires are no longer too thin and difficult to handle, and even wires that use silicone rubber for their primary coating do not become sticky and there is no need to worry about damaging them.

Therefore, handling becomes easier.

[Brief explanation of drawings]

1, 2, and 4 are explanatory diagrams of a cross section of the fiber core wire 10, FIG. 3 is an explanatory diagram of a cross section of the fiber strand 12 without the secondary coating 40, and FIG. 5 and FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing the method of the present invention in order of steps. 10: Fiber core wire, 12: Fiber bare wire, 2
0: glass fiber, 30: primary coating, 40: secondary coating, 42: void, 50: optical fiber cable, 52: jacket, 60: heat shrink tube.

Claims (1)

[Scope of Claims] 1. An optical fiber cable in which a plurality of fiber wires having a structure in which only a primary coating is provided on a glass fiber and no secondary coating is provided, and a jacket is covered on the outside of the fiber cable, or a glass fiber When connecting an optical fiber cable in which a plurality of fiber core wires are assembled with a structure in which there is a gap between the fiber strands with a primary coating on top and a secondary coating, and a jacket is covered on the outside. , After removing the outer sheath and the secondary coating and exposing the fiber strands, a heat-shrinkable tube is closely covered over each of the fiber strands, and then, the tips of the heat-shrinkable tube and the primary coating are removed. A method for connecting an optical fiber cable, the method comprising: removing a portion of the glass fiber to expose a tip portion of the glass fiber.