JPS6059611A - Composite cable of optical fiber and conductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Concerning composite keys that combine bodies.

Composite cables that combine optical fibers with communication or power conductors are extremely useful, contributing to labor-saving installation and lower system costs.

A conventional example of such a composite cable is shown in FIG. As shown in the figure, the conventional composite cable consists of twisting the conductors 4 and 6 covered with the insulating layer 8 and the optical fiber l together with a protective and reinforcing material (generally fibrous jute is used). ) 2 are twisted together, and an outer cover 7 having sufficient crushing blades is placed thereon.

In a conventional composite cable having such a structure, the protective and reinforcing material 2 includes the optical fiber 1 and the conductor 4.

M9 is aligned with the same twist pitch as 6, and therefore, when tension is applied to the cable, the protective/reinforcing material 2 easily stretches due to untwisting. In other words, the protective/reinforcing material 2 will stretch due to a slight tension before exhibiting its tensile strength. Therefore, the tension applied to the cable is not immediately applied to the optical fiber 1. In the current situation where the permissible tension of the optical fiber 1 is limited to approximately 0.2 light, the optical fiber is stretched by the permissible tension. This could easily lead to increased transmission loss and breakage.

On the other hand, since the optical fiber is sandwiched between the insulating layers 80 of the conductors 4 and 6, it is easily subjected to pressure from the sides, and the pressure applied from the sides to the outer sheath 7 of the cable acts unevenly, so that the optical fiber is The side pressure of the fiber 1 is partially excessive, which causes an increase in transmission loss, damage, and breakage of the optical fiber 1.

Further, when the cable is pulled, the optical fiber 1. Conductors 4, 6. Since the protective/reinforcing layer 2 rotates in the untwisted direction and the optical fiber 1 is twisted, the above-mentioned disadvantage becomes worse.

In view of the above-mentioned prior art, an object of the present invention is to provide a composite cable of an optical fiber and a conductor, which does not increase transmission loss even when lateral pressure or tension is applied, and does not cause damage or breakage of the optical fiber. shall be. To achieve such an object, the present invention provides a composite cable in which a protective/reinforcing layer is provided on the outer periphery of an optical fiber, and a plurality of conductor layers are coaxially arranged around the outer periphery of the optical fiber, wherein the protective/reinforcing layer is made of a fibrous material. The conductor should not be placed vertically along the axial direction, and the conductor should not be wrapped around the outer periphery of the protective/reinforcing layer for each conductor layer.Moreover, the direction of the winding of the conductor should be opposite to each other between the conductor layers. It is characterized by:

Hereinafter, the composite cable of the present invention will be explained in detail based on examples.

FIG. 2 shows an embodiment of the present invention. As shown in the figure, a protective/reinforcing layer 12 is provided on the outer periphery of the optical fiber 11, and this protective/reinforcing layer 12 is made by longitudinally supporting a fibrous material such as jute along the axial direction. It is. The method of splicing the fibrous bodies is to draw the fibrous bodies in a substantially straight line.
Although Li may be placed in the state, the fibrous bodies may be twisted together with extremely long strands in order to ensure the flexibility of the cable. Further, the optical fiber 1 may be a single fiber or a plurality of fibers. A coating 13. Conductor layer 14° Insulating layer 15. Conductor layer 16. Outer cover 1
7 are stacked coaxially. Conductor layer 14.16
is formed by winding a conductor on a coating 13 or an insulating layer 15. Moreover, the direction of winding of the conductor is different from that of each seed layer 14.
, 16 are in opposite directions. In this embodiment, there are two conductor layers, but three or more layers may be used. In this case, it is preferable that the conductor layers are wound in alternately opposite directions. Also coating 13. Insulating layer 15. The outer cover 17 does not have any features of the present invention, and a commonly used one may be used.

In the composite cable of the present invention having the above-mentioned structure, the protective/reinforcing layer 12 is formed by longitudinally supporting the fibrous material, so that when tension is applied, the fibrous material hardly stretches when untwisted. This means that the protective/reinforcing layer 12 exhibits sufficient tensile strength even in a state of little elongation. Therefore, even if tension is applied to the cable, the protective/reinforcing layer 12 effectively exhibits tension resistance, and the stretching of the optical fiber 11 is suppressed. Furthermore, in the present invention, since the conductor layers 14 and 16 are arranged coaxially around the outer periphery of the optical fiber 11, the external pressure applied from outside the cable is relaxed or dispersed by the conductor layers 14 and 16, and no excessive or excessive pressure is applied to the optical fiber 1. Partially acting suft, 1-M h l/1- two) h -knl/
1) The frost 1b and 1b can sufficiently withstand lateral pressure from outside the cable, and transmission loss does not increase. Further, in the present invention, since the directions of the conductor winding between the conductor layers 14 and 16 are opposite to each other, when tension is applied to the cable, these conductor layers 14 and 16 tend to rotate in the untwisted direction. However, since the directions of rotation are opposite to each other, they cancel each other out and do not rotate in either direction. Therefore,
In the present invention, unlike conventional ones, the optical fiber 11 does not twist in any direction even when tension is applied, and the optical fiber 11
damage etc. can be prevented. 1. In the protective/reinforcing layer 12, if the fibrous body is twisted with an extremely long twist pitch, when tension is applied, this fibrous body also rotates in the direction of the twist return, but the twist pitch is Extremely long and small rotation amount δ
So it's hardly a problem.

As explained above in detail based on the examples, the composite cable of the present invention protects the optical fiber from tension and lateral pressure, so the transmission loss is low and the optical fiber is not damaged by damage.
The pores that break are small.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a conventional composite cable, and FIG. 2 is a structural diagram of an embodiment of the composite cable of the present invention. In the drawing, 11 is an optical fiber, 12 is a protective/reinforcing layer, 13 is a coating, 14 and 16 are a conductor layer, 15 is an insulating layer, and 17 is an outer jacket. Patent Applicant Sumitomo Electric Industries Co., Ltd. Agent Patent Attorney Shibu Mitsuishi (and 1 other person) Figure 1

Claims (1)

[Claims] In a composite cable in which a protective/reinforcing layer is provided on the outer periphery of an optical fiber and a plurality of conductor layers are coaxially arranged around the outer periphery of the optical fiber, the protective/reinforcing layer has a fibrous body longitudinally attached along the axial direction. Furthermore, each conductor layer is formed by winding a conductor around the outer periphery of the protective/reinforcing layer, and the winding directions of the conductors are opposite to each other. composite cable.