JPH0669250B2 - Optical cable laying method using self-supporting Daruma type overhead cable conduit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of laying an optical cable using a self-supporting daruma-shaped overhead cable conduit.

[Object and Structure of the Invention] At present, a daruma-shaped cable is widely used as a cable for telephone subscribers as a self-supporting overhead cable. Daruma-shaped cables are easy to lay and can be distributed to subscribers.
It is also convenient for pulling in. However, if the conductor size increases or the number of core wires increases, the weight of the cable increases, and it is necessary to increase the size of the tension member, and the problem of dancing due to wind increases.
There is a limit to the size of the structure that can be naturally constructed as an overhead line.

By the way, it is clear that subscriber cables will shift from copper cables to optical cables sooner or later due to the progress of communication systems using optical cables, but in this case, optical cables have the major feature of being lighter than copper cables. ing. However, since the optical fiber that constitutes the optical cable has a larger transmission loss due to the connection than the copper wire, it is necessary to adopt a line configuration that minimizes the connection of the optical fiber. In the case of a conventional cable composed of copper wire, the deterioration of the transmission loss due to the connection work is not so large, so when branching is required, the cable is cut at that location to connect with the branch cable. In the case of an optical cable, it is necessary to suppress an increase in transmission loss due to an increase in the number of connection points. Therefore, it is necessary to devise an optical cable itself or an optical fiber constituting the optical cable without connecting at the branch point, if possible.

The present invention has been made from such a point of view, and its feature is that a tension member and a plurality of branchable and independent conduits are integrally covered with a self-supporting Daruma cable conduit in advance. And install a light and round optical cable by pulling in or removing it from the independent conduit, and further laying a required number of the independent conduits to the self-supporting sill-shaped cable conduit. It is a method of laying an optical cable that forms an optical cable line of a required number of cores that is branched laterally from an outer cover.

The figure shows the self-supporting daruma-shaped aerial cable conduit used in the present invention with a part thereof being cut away.

In the figure, 1 is a tension member made of steel strands or the like, 2 is an independent conduit made of plastic such as polyethylene, 3 is a jacket, and 4 is a coarse winding yarn.

A plurality of independent pipelines, for example, four independent pipelines are bundled in a straight line and restrained and wound with a coarse winding thread 4 or the like, and the tension members 1 are longitudinally spaced apart from each other using this as a core. The outer cover 3 is integrally formed so as to have a duller-shaped cross section by extruding the plastic as described above. In addition, 5 is a neck.

In the present invention, such a self-supporting Daruma type aerial cable conduit is laid aerial in advance, and some of the independent conduits that compose the self-supporting cable conduit are provided in accordance with the required number of core wires. A round, lightweight optical cable is pulled in or removed, and a necessary number of independent conduits corresponding to the number of branch cores are provided from the jacket of the self-supporting daruma-shaped cable conduit as needed for branching. An optical cable line having a branch is formed by taking it out to one side.

The specific way to take out the optical cable at the branch point is to make a hole in the jacket of the self-supporting Dharma type cable conduit at the branch point or remove the jacket to remove the required independent conduit. Take out to the side of the object and cut or make a hole only in the independent pipeline, connect the branch pipeline with the same inner diameter as the independent pipeline, and then connect to the independent pipeline. If the optical cable is retracted, the optical cable can be branched without a connection point. If the optical cable is previously drawn into the independent conduit, remove the jacket of the self-supporting daruma cable conduit at the branch point so that the optical cable in the independent conduit is not damaged. It is also possible to cut only the tube and to branch out the optical cable on one side from there, paying attention to. Of course, in this case, it is necessary to protect the optical cable by processing such as pulling the drawn optical cable through another branch pipe.

[Effect] According to the optical cable laying method of the invention described above,
Since a self-supporting Daruma-shaped overhead cable conduit is installed in advance and only the required number of optical fibers are drawn in, there is an effect that the initial investment of the system configuration can be small. Further, the aerial cable conduit has an appearance structure similar to that of the conventional Daruma type cable, and can be easily installed aerial.

Furthermore, if the number of required core wires decreases in accordance with the demand trend of the subscriber line, part of the optical cable will be removed, or if branching becomes necessary, an independent pipeline is free to branch. Since a required number of independent conduits can be taken out laterally from the jacket of the self-supporting cable conduit and a branching optical cable line with no connection to the optical cable itself can be configured, there is little transmission loss. An optical cable line can be constructed. In designing, manufacturing, and laying self-supporting Daruma-shaped cable conduits, strength (dancing by wind or tension at the time of overhead wire) is sufficient based on the results of conventional copper-wire self-supporting Daruma-shaped overhead cables. Since it is known, these can be referred to, and since the manufacturing equipment, jigs and tools can also be technically diverted, a self-supporting Daruma type cable conduit with no quality or technical problems can get.

[Brief description of drawings]

The drawings show a self-supporting daruma overhead cable conduit for use in the laying method of the present invention. 1 ... tension member, 2 ... independent conduit, 3 ... jacket, 4 ... coarse thread, 5 ... neck.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Fumio Harano 1 Taya-cho, Totsuka-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Yoshiaki Shiotani 1-tani, Taya-cho, Totsuka-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd.Yokohama Works (72) Inventor Kenya Fuchigami Tokai-mura, Naka-gun, Ibaraki Prefecture, Shirahoji 162 Shirane, Nippon Telegraph and Telephone Public Corporation, Ibaraki Telecommunications Research Institute (56) References 145885 (JP, A) JP 56-86012 (JP, A) Actually opened 59-7411 (JP, U) Actually opened 55-37561 (JP, U)

Claims (1)

[Claims] 1. A self-supporting daruma-shaped cable conduit having a tension member and a plurality of branchable and independent conduits integrally covered with a sheath is preliminarily laid in an imaginary state to provide a lightweight round optical cable. The required number of cores is installed by pulling in or out of an independent pipe line, and further, a required number of the independent pipe lines are taken out laterally from the jacket of the self-supporting daruma type cable pipe line and branched. A method of laying an optical cable using a self-supporting daruma-shaped overhead cable conduit, which is characterized in that the optical cable line is constructed.