JPH0336967Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Background of the Invention] The present invention relates to an improvement in the simple connection of optical fiber cores. Optical fiber connections are usually made using a thin wire rod made of quartz or the like (for example, outer diameter 125 μm).
They are connected by heat fusion and given appropriate reinforcement, but a heating device is required for heat fusion, and a fusion machine or the like with an electric arc generator is generally used. .

However, this working method is not necessarily simple, and may not be optimal for emergency situations such as restoration connection when the optical fiber cable line is damaged or disconnected.

Therefore, in such a case, even if the quality (for example, loss) at the connection point is somewhat poor, it is within the margin of the system loss of the optical fiber cable transmission line, and as long as the system operates normally, it is not a practical problem. Even if the connection method is simple and has poor quality to some extent, it is often preferable to use it for emergency situations until the connection is fully restored.

In general, full-scale fusion splicing is performed at most
There is a loss of 0.2dB/1 connection point or less. On the other hand, as will be explained later, the loss of the simple connection of the present invention is due to the butt method used to transmit light between optical fibers, so there is a slight gap in the contact surface of the optical fibers, By inserting a medium for refractive index matching into the refractive index, the connection loss can be suppressed to 1 dB/1 connection point or less.

[Structure of the idea] The embodiments shown in the drawings will be described below.

FIG. 1A is a partial longitudinal cross-sectional view of the connecting portion of the present invention, and FIG. 1B is a cross-sectional view of the connecting portion of FIG. 1A.

1 and 1' are optical fiber core wires to be butt-connected to each other, and 2 and 2' are protective layers of the optical fibers. The tips of the optical fiber core wires 1 and 1' are cut at right angles, and the tips are abutted at an abutment point 3 in a connecting pipe, which will be described later. This is intended to transmit light through this abutment point 3 with relatively low loss. At this time, in order to pass the light through the contact surface at the abutment point 3 with low loss, it is necessary to ensure that the axes of the optical fiber cores 1 and 1' are in a straight line, that the end surfaces are not separated from each other, and that the end surfaces are aligned with the optical fiber axis. It is necessary to cut at a right angle as much as possible.

Although the optical fiber can be easily cut using a separately prepared cutter, a guide is required to precisely align the end faces of the optical fiber. In FIG. 3B, 4 is a connecting pipe for guiding the optical fiber, and the circular cross section near the abutting point 3 at the center has an inner diameter that almost circumscribes the optical fibers 1 and 1'. A pore 5 for air venting is opened through the surface at the section.

The connecting pipe 4 usually has the inner diameter as described above at its center, and has fiber cores 1, 1' at both ends.
It is made with a thick inner diameter to make it easier to insert the tip.

When abutting the end faces of the tips of both optical fibers 1 and 1', in order to prevent loss due to reflection at the contact surface, it is recommended to fill with anti-reflection matching liquid to reduce loss at the abutting point. preferable.

After inserting the optical fibers 1, 1' into the connecting pipe 4 in this manner, the ends of the connecting pipe 4 are fixed to both optical fibers with adhesive 6, and both optical fibers 1, 1' Stabilizes the contact condition.

The optical fibers connected in this way within the connecting pipe 4 have no protective layer around them and are mechanically weak and cannot be put to practical use, so it is necessary to reinforce them with a protective member. .

For this reason, in the present invention, as shown in cross section in FIG. 2, prior to connection, a pipe 7 made of hot melt agent (for example, EVA) and a heat-shrinkable plastic pipe 9 having an inner diameter larger than the outer diameter of this pipe 7 are used as protective members. Put it through the optical fiber.

The periphery of the connecting pipe 4 to which the optical fiber cores 1, 1' already described and the protective layers 2, 2' of the optical fiber cores 1, 1' are covered with the pipe 7 made of the hot melt agent. Further, the pipe is covered with the heat-shrinkable plastic pipe 9, a steel wire or the like is attached as a reinforcing body 8 between the connection part and the heat-shrinkable plastic pipe 9, and the pipe made of the hot-melt agent is melted by heating. Heat shrinkable tube 9
The connection is completed by applying heat shrinkage to the . FIG. 1B shows its cross section.

When the heat-shrinkable plastic pipe contracts, the hot-melt agent melts and fills the connecting pipe 4 and the parts of the optical fiber that have the protective layers 2 and 2', and they are fused to each other, thereby creating a configuration in which they are confined by the protective member. It will be understood that the reinforcing body 8 further strengthens the inner connecting portion.

In such a structure, the connecting pipe 4 and the reinforcing body 8 are preferably made of a material that has similar temperature and mechanical properties to the material of the optical fiber and is less brittle, such as metal such as steel or ceramic. Experience shows good characteristics.

In addition, the heat-shrinkable plastic pipe 9 used for the outer protection member is normally one that shrinks over its entire length, but in order to easily perform the heat-shrinking process, it is necessary to shrink only both ends of the plastic pipe and connect the optical fibers together. It is also possible to shorten the connection by reinforcing the adhesive.

According to experiments to date, it has been confirmed that this connection has sufficient functionality as a transmission line and is sufficiently durable for practical use if used for a short period of time under normal environmental conditions.

[Effects of the invention] As explained above, the connection part according to the invention does not require special tools when an optical fiber is broken due to an accident during maintenance of an optical fiber cable system and the breakage can be quickly repaired. , has a configuration that allows connection work to be completed in a short time with little transmission loss, and has a configuration that can maintain sufficient strength, so it can be fully expected to be useful in practice.

[Brief explanation of drawings]

1A and 1B are a partial longitudinal sectional view and a transverse sectional view of an embodiment of the present invention. FIG. 2 shows the protective member before being heat-shrinked. Figures 3A and 3B show a cross-sectional shape and a partial vertical cross-sectional shape of a connecting pipe used in the present invention. 1, 1'... Optical fiber core wire, 2, 2'... Protective layer, 3... Butt point, 4... Connection pipe, 5...
Air vent pores, 6...adhesive, 7...pipe made of hot melt agent, 8...reinforcement material, 9...heat-shrinkable plastic pipe.

Claims (1)

[Scope of utility model registration request] The end surfaces of the tips of the optical fibers are butted together in a connecting pipe with a circular cross section that has an air vent hole in the center and is approximately circumscribed to the outer diameter of the optical fiber, and each end of the connecting pipe is bonded with an adhesive at both ends of the connecting pipe. The optical fiber is fixed, the connecting pipe and a part of the optical fiber are covered with a pipe made of a hot melt agent, and the pipe is further covered with a heat-shrinkable plastic pipe, and the pipe made of the hot-melt agent and the heat-shrinkable plastic pipe are covered. A reinforcing body is placed between the plastic pipes, and the connecting pipe, the optical fiber protective layer, and the reinforcing body are integrally enclosed in the heat-shrinkable plastic pipe by heating the pipe made of the hot melt agent and the heat-shrinkable plastic pipe. Optical fiber connection.