JPS6027364Y2 - self-supporting fiber optic cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-supporting optical fiber cable for optical communication used in the field of optical communication using optical fiber as a transmission medium.

Self-supporting cables, in which stranded copper wires serving as support wires are run along a cable core and integrally molded, are widely used for the purpose of improving workability during installation.

An example of a conventional self-supporting cable made of metal conductors is shown in FIG. 1, where 1 is a cable core, 2 is a support wire, and 3
is the cable sheath, and the support wire and the cable sheath are designed not to separate easily.

When the optical fiber cable is such a self-supporting optical fiber cable, the support wire 2, that is, the optical fiber cable, stretches due to the load applied to the support wire 2 when the optical fiber cable is strung, and the optical fiber core wire is constantly stretched. Tensile stress is generated, and in some cases, rupture due to static fatigue occurs.

Furthermore, as the optical fiber cable stretches, lateral pressure is applied to the optical fiber core, causing slight bending and increasing loss.

Furthermore, optical fiber cables strung under constant tension expand and contract due to changes in outside temperature, but since the coefficients of thermal expansion of the optical fiber core wire and the support wire receiving tension are different, the optical fiber core wire and the support wire receiving tension are different. As a result, the optical fiber core wire will expand and contract differently, and tension or slight bending will occur in the optical fiber core wire, which may cause an increase in loss.

This invention is a self-supporting type optical fiber cable, and when molding the optical fiber cable into a self-supporting type, the support wire is not brought into close contact with the optical fiber cable jacket, and the support wire can move freely to some extent within the optical fiber cable jacket. Its purpose is to prevent the effects of the elongation of the support wire that occurs during the installation of the optical fiber cable or the expansion and contraction of the support wire due to changes in temperature from directly affecting the optical fiber cable. be.

FIG. 2 is a sectional view of an embodiment of the present invention, in which 4 is an optical fiber cable core, 5 is a support wire, 6 is an optical fiber cable jacket, 7 is a gap or a lubricant, and the support wire 5 and the optical It has a structure that allows it to move relative to the fiber cable jacket 6.

In such a self-supporting type cable, the tension when the optical fiber cable is strung is handled by the support wire 5, but if the strut tension causes the support wire to stretch or the heat between the support wire and the optical fiber cable The structure is such that the support wire 5 and the optical fiber cable sheath 6 can move even if there is a difference in the amount of expansion and contraction between the support wire and the optical fiber cable due to changes in temperature due to differences in expansion characteristics. Therefore, it is possible to prevent the effects of the expansion and contraction of these supporting wires from affecting the optical fiber cable core, and to prevent breakage of the optical fiber core wire due to static fatigue or increase in loss due to tension or bending of the optical fiber core wire. It can be prevented.

As explained above, the self-supporting optical fiber cable of the present invention does not have the influence of expansion and contraction of the support wire on the optical fiber cable, so the characteristics of the optical fiber cable are not affected by the expansion and contraction of the support wire during installation of the optical fiber cable. It has the advantage that there is no need to pay attention to deterioration, construction is easy, and it can be used outdoors where the temperature changes rapidly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional self-supporting cable made of metal conductors, and FIG. 2 is a sectional view of an embodiment of the present invention. 1... Cable core, 2... Support wire, 3
...... Cable jacket, 4... Optical fiber cable core, 5... Support wire, 6... Optical fiber cable jacket, 7... ...Voids or lubricants.

Claims (1)

[Scope of utility model registration request] In an optical fiber cable jacket having an optical fiber cable core and covering the outside of the optical fiber cable core, a gap is provided between the optical fiber cable jacket and a support wire that is disposed not in close contact with the optical fiber cable core. Alternatively, a self-supporting optical fiber cable characterized in that a lubricant is filled between the support wire and the optical fiber cable jacket so that the support wire can be moved.