JPH0841977A - Method of laying transmission line using optical fiber - Google Patents

Abstract

PURPOSE:To shorten a laying period and reduce laying cost without impeding water flowing in a main pipe. CONSTITUTION:Branch lines 5 with conductors, having optical fibers, coated with flexible resin are made branch off from an optical fiber cable 1, laid in a main pipe 2, by a branching device 4 disposed in a manhole 3. The branch lines 5 are laid along the inner peripheral surface of the main pipe 2 and that of fitting pipes 8 branching off from the main pipe 2, and connected to objects 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of laying a transmission line using an optical fiber.

[0002]

2. Description of the Related Art Optical fiber transmission methods take advantage of the characteristics of optical fibers such as low loss, wide band, light weight, and small diameter, and have a wide range of application fields including fields that were difficult to achieve by telecommunications methods. It is used for backbone transmission lines such as telephone stations, telephone stations, in-factory communications, and between public facilities.

To lay it as a transmission line, for example, as shown in an explanatory view in FIG. 5, an optical fiber is laid in a drainage pipe E such as a sewer pipe connecting the public facilities A, B, C and D to each other. Done by

In order to actually lay an optical fiber in the conduit E, since the optical strength of the optical fiber alone has a limit to the mechanical strength and the environmental resistance, a number of tension members supporting tension and other reinforcing materials are used. These optical fibers are bundled and processed into optical fiber cables for use.

The structure of the optical fiber cable 1 is, for example, as shown in an explanatory perspective view of FIG. 6, a fiber core 1a in which a fiber element in which an optical fiber is primarily coated with a plastic resin is further coated with a secondary coating such as nylon or polyethylene. Are bundled and covered with a metal thin tube 1b, a plurality of metal thin tubes 1b are arranged around a tension member 1c made of a steel wire, and these are integrally covered with a plastic protective cloth 1d. . Furthermore, this protective cloth 1d
It is covered from above with a metal protective coating 1e knitted in the shape of a mesh, and from above with a plastic sheath 1f.

[0006]

When laying the above-mentioned optical fiber, mechanical strength and environment resistance are required because it is processed into an optical fiber cable in which several optical fibers are bundled together with a tension member and a reinforcing material. It is possible to lay it in pipes such as sewer pipes in excellent condition. However, since the sewage pipes such as the sewer pipes that connect the above-mentioned public facilities and the like have a relatively large diameter, the optical fiber cable has a large bending rigidity including a tension member and a reinforcing material. Even if it is greatly curved, for example, the radius of curvature is 45 cm or more, it is possible to lay it in a pipe, but a pipe such as a sewer pipe for laying an optical fiber cable, for example, a main pipe is relatively thin, for example, an inner diameter is 70
It is within 0 mm, and the inner diameter that is branched from this main pipe, for example, commonly used as an office or home mounting pipe is 15
In the case of a thin pipe of 0 or 200 mm, the inner radius of the main pipe and the mounting pipe is limited to the inner circumferential faces of the main pipe and the mounting pipe due to the large minimum radius of curvature of the optical fiber cable 1. It is difficult to lay an optical fiber cable through the route. Further, even for a main pipe and an attachment pipe having an inner diameter that enables the laying of an optical fiber cable, it is inevitable that the main pipe is laid so as to curve downward from the upper part of the inner peripheral surface of the main pipe, which may prevent running water flowing through the main pipe. There is a defect of.

As a countermeasure against this, as shown in FIG.
An optical fiber cable 1 which is laid in the main pipe 11 and serves as a trunk is branched by a branching device 13 in a manhole 12 arranged between the main pipes 11 and 11, and is bendable with a small radius of curvature. It is also possible to use a branch line 14 such as a core line to lead the object 15 to each office or home.

However, in this laying method, the manhole 1
It is necessary to newly install a laying pipe or the like for installing a branch line 14 that connects the branching device 13 and the target object 15 arranged in 2, which causes a long laying period and an increase in laying cost. There is a defect.

Therefore, according to the present invention, the laying from the optical fiber cable arranged in the main pipe having a relatively small inner diameter to each object does not prevent running water in the main pipe, and the laying period and the laying cost are reduced. Another object of the present invention is to provide a method of laying a transmission line using an optical fiber.

[0010]

A method of laying a transmission line using an optical fiber according to the present invention which achieves the above object is a method of branching an optical fiber cable laid in the main pipe along the upper portion of the inner peripheral surface of the main pipe by a branching device. A branch line in which a core wire having an optical fiber is covered with a flexible resin is branched, and the branch line is laid along the inner peripheral surface of the main pipe and a mounting pipe branching from the main pipe to connect to a target object. is there.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a transmission line laying method using an optical fiber according to the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing the outline of the present embodiment, in which reference numeral 1 is a main pipe 2 such as a sewer pipe and the main pipes 2 and 2 arranged adjacent to each other. It is an optical fiber cable that is laid in the human hole 3 and serves as a trunk line.

The optical fiber cable 1 serving as a trunk line is laid along the upper part of the inner peripheral surface of one main pipe 2, and swivels along the peripheral surface of the human hole 3 to the upper part of the inner peripheral surface of the other main pipe 2. Is laid along. A branching device 4 is installed in the human hole 3, and a plurality of branch lines 5 are branched from the optical fiber cable 1 in the branching device 4.

The branch line 5 branched in the branching device 4 is
As shown in FIG. 2 which is an explanatory view of main parts, an optical fiber or a fiber element in which the optical fiber is primarily coated with a plastic resin or a fiber core wire in which a secondary coating is further applied is a core wire 6
A flexible cable in which the core wire 6 is covered with a flexible resin 7, which is laid along the upper part of the inner peripheral surface of the main pipe 2 and is connected to the main pipe 2 for each office or home. Via a pipe 8, a rainwater spill (not shown) or the like is connected to an object 9 such as an office or a home.

The mounting pipe 8 connected to the main pipe 2 is generally
As shown in FIGS. 3 (a), (b), (c), and (d), the attachment angle θ with the main pipe 2 is 30 °, 45 °, 60 °, 90.
The branch line 5 is made of a flexible cable as described above, and can be bent with a relatively small radius of curvature, so that the branch line 5 is formed along the upper part of the inner peripheral surface of the main pipe 2. It is possible to bend the branch line 5 that has been laid down along the joint between the main pipe 2 and the mounting pipe 8 to a small radius of curvature and to lay it along the inner peripheral surface of the mounting pipe 8, which is relatively small. Even the main pipe 2 and the mounting pipe 8 having the inner diameter can be laid on the main pipe 2 and the mounting pipe 8 without curving downward from the upper portion of the inner peripheral surface of the main pipe 2.

In the above embodiment, the branch wire 5 branched by the branching device 4 is composed of a flexible cable in which a single core wire 6 is covered with a flexible resin 7. However, FIG. As shown in FIG. 3, a plurality of core wires 6 are integrally formed with the flexible resin 7 and the number of branch wires 5 to be laid is reduced by branching into a suitable number of core wires 6 at appropriate positions. It is also possible to obtain a reduction in laying work.

[0017]

According to the above-described method of laying a transmission line using an optical fiber according to the present invention, a flexible branch line that is laid inside a main pipe and includes an optical fiber by a branching device from an optical fiber cable serving as a transmission line. Since the branch is branched, a branch line is laid along the inner peripheral surface of the main pipe and the mounting pipe branched from the main pipe without disturbing the running water flowing through the main pipe, and a transmission line is formed by an optical fiber to the target object. It is possible to lay a transmission line using an existing pipe without the need to install a new pipe for laying the pipe, and it is possible to shorten the laying period of the transmission line and reduce the installation cost. It has an effect peculiar to the present invention.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view explaining an embodiment of a transmission path laying method using an optical fiber according to the present invention.

FIG. 2 is an explanatory view of a main part of a branch line used in this embodiment.

FIG. 3 is a sectional view of an essential part for explaining a mounting state of a main pipe and a mounting pipe used in this embodiment.

FIG. 4 is a main part explanatory view showing another embodiment of the branch line.

FIG. 5 is a schematic explanatory diagram illustrating a transmission path using a conventional optical fiber.

FIG. 6 is an explanatory view of a main part of an optical fiber cable.

FIG. 7 is a schematic explanatory diagram illustrating a transmission path by an optical fiber.

[Explanation of symbols]

 1 Optical fiber cable 2 Main tube 3 Human hole 4 Branching device 5 Branching wire 6 Core wire 7 Flexible resin 8 Mounting tube 9 Target object

Claims (4)

[Claims] 1. A branch line in which a core having an optical fiber is covered with a flexible resin is branched from an optical fiber cable laid inside the main pipe along an upper portion of an inner peripheral surface of the main pipe by a branching device. A method for laying a transmission line using an optical fiber, which comprises laying along the inner peripheral surface of a main pipe and a mounting pipe branched from the main pipe and connecting the main pipe to a target object. 2. The method of laying a transmission line using an optical fiber according to claim 1, wherein the branching device is arranged in a human hole connected to the main pipe. 3. The method of laying a transmission line using an optical fiber according to claim 1, wherein one or a plurality of branch wires are integrally covered with a flexible resin. 4. The transmission line laying method using one optical fiber according to claim 1, wherein the mounting angle between the main pipe and the mounting pipe branched from the main pipe is 30 ° to 90 °.