JPH08110451A - Optical fiber cable - Google Patents

Abstract

PURPOSE: To provide a self-supporting optical fiber cable which is windable in alignment on a drum, eliminates troubles, such as occurrence of a collapse in winding during transportation, is widen in the degree of freedom in surplus length, assures the sufficient surplus lengths under any conditions, has excellent workability at the time of laying and is easily producible by using apparatus for general purpose. CONSTITUTION: This optical fiber cable is provided with a tension member consisting of a steel wire or FRP (glass fiber reinforced resin), etc., at its center and is provided with a solid body 5 consisting of plastic, such as polyethylene, on the outer periphery thereof. Plural pieces of optical fiber units 8 formed by loosely housing plural pieces of coated optical fibers 7 in tubes 6 consisting of a polybutyrene terephthalate (PBT), etc., are embedded into the solid body 5 in the form of doubling and twisting these units part nearly equal intervals around the tension member 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a self-supporting optical fiber cable.

[0002]

2. Description of the Related Art Conventionally, as an optical fiber cable for improving workability during installation, as shown in FIG. 8, a cable body 2 is supported and fixed to a support wire 1 by a prehanger 3 at a predetermined interval. A so-called self-supporting type of structure is known.

In this self-supporting cable, as shown in the figure, the cable body 2 is fixed to the support wire 1 with slack. That is, the length of the cable body between the prehangers 3 is slightly longer than that of the support wire 1.
This is for the following reason.

That is, the cable actually laid is
Although it expands and contracts due to changes in the ambient temperature, etc., the coefficient of thermal expansion of the optical fiber core wire is much smaller than that of the material (usually steel wire) forming the support wire 1, so that the cable body between the prehangers 3 and If the lengths of the support wires 1 are the same, the support wires 1
Since the expansion and contraction of the optical fiber cannot follow the expansion and contraction of the optical fiber, tension or minute bending occurs in the optical fiber, which may lead to deterioration or breakage of transmission characteristics.

Further, the connecting portion of the cable has a structure in which optical fiber core wires are joined together, and a connection box is watertightly fitted on the outer side of the optical fiber core wires. Since a so-called creep phenomenon that is drawn into the cable occurs, it is necessary to connect the optical fiber cores with a sufficient extra length.

Further, an extra length is required for branching from an overhead cable.

By the way, in general, it is necessary to have an extra length of about 0.3% with respect to the tension of the former supporting wire and about 3% at the connecting portion.

[0008]

However, in the conventional self-supporting cable as described above, the structure in which the cable body 2 is loosened to have an extra length, that is, the outer shape in the length direction is changed. Due to this structure, it is difficult to align and wind the drum, and there is a problem that the cable may collapse during transportation. Further, there is also a problem that the extra length that can be given is limited because of this.
In addition, there is also a problem that iron lines are liable to be squeezed by a gold car or the like. In addition, there is a problem in terms of manufacturing, such that a special manufacturing apparatus is required for molding the pre-hanger 3 and it is necessary to slow down the linear velocity because cooling takes time in the molding process.

The present invention has been made in order to solve such a conventional problem, and it is possible to wind the drum in a line, and there is no inconvenience such as winding collapse during transportation. A self-supporting optical fiber cable that has a wide degree of freedom, can secure a sufficient excess length under any conditions, has excellent workability during installation, and can be easily manufactured using general-purpose equipment. The purpose is to provide.

[0010]

The optical fiber cable of the first invention of the present application comprises a tension member and a solid body provided on the outer periphery of the tension member, and the solid body has an internal body. In addition, a tube in which at least one optical fiber core wire is housed in a loose is meandered in the length direction and embedded.

Further, in the optical fiber cable of the second invention of the present application, in the optical fiber cable, marking is provided on the outer periphery of the solid body to indicate the embedding position of the tube accommodating the optical fiber core wire. It is characterized by.

Further, in the optical fiber cable of the third invention of the present application, a tube in which at least one optical fiber core wire is loosely housed is buried in the solid body so as to meander in the longitudinal direction. The optical fiber cable main body, the cable support wire arranged in parallel with the optical fiber cable main body, and the cable jacket that collectively covers these are provided.

[0013]

In the optical fiber cable of the present invention, the extra length required for the optical fiber core wire can be provided inside the cable (or inside the cable body), so that the outer shape of the cable is uniform in the length direction. As a result, winding of the drum is facilitated, and there is no fear of winding collapse during transportation. Further, the manufacturing is easy, and efficient manufacturing can be performed without using a special device. Moreover, the extra length can be adjusted by changing the meandering pitch of the tube, etc., and the degree of freedom of the extra length can be expanded to meet various erection conditions. Furthermore, in the case where a marking indicating the embedded position of the tube accommodating the optical fiber core wire is provided on the outer periphery of the solid body, the required optical fiber core wire was easily accommodated when branching the cable. The position of the tube can be known, and the workability of branching work can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the optical fiber cable of the present invention, and FIG. 2 is a perspective view thereof.

As shown in these figures, this optical fiber cable has a tension member 4 made of steel wire, FRP (glass fiber reinforced resin) or the like as a center, and a solid member made of plastic such as polyethylene around the tension member 4. The body 5 is provided and configured. The solid body 5 has a tube 6, preferably a plastic having a softening temperature at least about 10 ° C. higher than that of the material forming the solid body 5, such as polybutylene terephthalate (PBT) when the solid body 5 is made of polyethylene. A plurality of optical fiber units 8 in which a plurality of optical fiber core wires 7 are loosely housed in a tube made of nylon or the like are twisted by SZ twist around the tension member 4 at substantially equal intervals. It is buried in the form. In FIG. 2, the twisted shape of the tension member 4 of one optical fiber unit 8 is shown by a broken line, but the twisting method of the unit 8 is not limited to such SZ twisting,
It may be S twist or Z twist.

In order to manufacture such an optical fiber cable, the optical fiber unit 8 may be twisted around the outer periphery of the tension member 4 while the plastic for the solid body 5 is extrusion coated. At that time, the softening temperature is at least as high as that of the material forming the solid body 5 as the tube 6.
If a material having a high temperature of about 10 ° C. is used, it is possible to prevent the tube 6 from being deformed due to heat when the solid body 5 is extruded.

In the optical fiber cable having the above structure, since the outer shape is uniform in the lengthwise direction, it is easy to wind in a line on the drum, and the winding is not collapsed during transportation. In addition, there is no risk that the optical fiber will be broken due to ironing by the gold wheel during installation. Further, at the time of manufacturing, a general-purpose cable manufacturing apparatus can be used to efficiently manufacture the cable without delaying the linear velocity. Moreover, the extra length of the optical fiber core wire is sufficiently secured by the fact that the optical fiber core wire 7 itself is housed in the tube 6 loosely and the tube 6 in the cable is twisted. . Therefore, even when the tension member 4 at the center is actually laid and tension is applied, it does not cause breakage of the optical fiber core or deterioration of transmission characteristics, and can sufficiently cope with cable branching. further,
Since the surplus length of the optical fiber core wire 7 can be adjusted by changing the twist pitch of the tube 6, there is also an advantage that the degree of freedom of the surplus length is widened and various installation conditions can be met. In addition, at the time of branching, a knife or the like is put in the solid body 5 to take out the optical fiber core wire 7,
Although a part thereof is cut off, since the optical fiber core wire 7 is housed in the tube 6, the knife does not directly reach the optical fiber core wire 7 and its damage can be prevented. Further, since the surface of the tube 6 is closely fixed to the solid body 5, there is no inconvenience that the tube 6 moves in the longitudinal direction even if it receives vibrations such as wind.

Next, another embodiment of the present invention shown in FIGS. 3A and 3B will be described. As shown in FIG.
In each of these embodiments, a marking indicating the position of the tube 6 accommodating the optical fiber core wire 7 is provided on the outer peripheral surface of the solid body 5 of the optical fiber cable having the above configuration. That is, in the example shown in FIG. 3A, one groove 9 is provided on one of the two adjacent tubes 6 and one groove 9 is provided on the other. Further, in the example shown in FIG. 3B, one fin-shaped protrusion 10 is provided on one of the two adjacent tubes 6.
However, two fin-shaped protrusions 10 and 10 are provided on the other side.

In such an optical fiber cable, in addition to the effect of the above embodiment, the position of the tube 6 accommodating the required optical fiber core wire 7 can be easily known when the cable is branched. Thus, it is possible to obtain the effect that the workability of the branch work can be improved. The optical fiber core wire 7 in the tube 6 may be identified by coloring the optical fiber core wire 7 in a predetermined color.
In the present invention, marking is not limited to the grooves 9 and the protrusions 10 as shown in these examples, but may be performed by printing a line using ink, for example. In this case, if the ink color is changed, it is only necessary to print one line on each of the two adjacent tubes.
In addition, in this embodiment, the example in which the marking is made on the two tubes 6 is illustrated.
It may be applied only on the top or on all tubes 6.

FIG. 4 and FIG. 5 are sectional views showing still another embodiment of the present invention.

First, in the embodiment shown in FIG.
The optical fiber cable 11 is provided with a support wire 12 made of steel wire or FRP in parallel with each other, and polyethylene or the like is extruded on the outer circumference of the support wire 12 at a time to provide a cable jacket 13.

In this embodiment, the tube 6 is twisted, and the optical fiber core wire 7 is loosely accommodated in the tube 6 thus twisted. The line 7 can secure a sufficient extra length with respect to the support line 12.

Further, in the embodiment shown in FIG.
The optical fiber cable 11 has a structure in which the support wire 12 provided with the coating 14 on the outer periphery is twisted into an SZ twist. Also in this case, not only SZ twisting but S twisting or Z twisting may be used.

Also in this embodiment, since the tube 6 is twisted and the optical fiber core wire 7 is loosely accommodated in the tube 6 thus twisted, the optical fiber core The line 7 can secure a sufficient extra length with respect to the support line 12.

In each of these embodiments, FIG.
Similar to the one described above, there are advantages that the drum can be easily wound, the manufacturing is easy, and the like, and the cable can be laid by the conventional method. Furthermore, in these examples, the tube 6 containing the optical fiber core wire 7 as shown in FIG.
By marking the outer surface of the solid body 5 with the marking indicating the position, the workability of the cable branching work can be improved. In these embodiments, since the optical fiber cable 11 is supported by the support line 12, the tension member 4 at the center of the optical fiber cable 11 need not be provided.

In all of the above-described embodiments, the optical fiber core wire 7 housed in the tube 6 has a round cross section, but the present invention is not limited to such embodiments. The present invention is not limited to this, and instead of the optical fiber core wire 7 having a round cross section, a multi-core optical fiber tape core wire 15 as shown in FIG. 6 may be used.
As shown in FIG. 7, the jelly-like admixture 16 may be filled in the void portion of the optical fiber core wire 7.

[0028]

As described above, according to the optical fiber cable of the present invention, the extra length required for the optical fiber core is
Since it can be held inside the cable (or inside the cable body), the outer shape of the cable can be made uniform in the length direction, which facilitates winding on a drum and may cause winding collapse during transportation. Also disappears. Further, it is possible to easily and efficiently manufacture without using a special device. Moreover, since the extra length can be adjusted by changing the meandering pitch of the tube, the degree of freedom of the extra length can be increased, and various installation conditions can be met.

Further, when marking is provided on the outer periphery of the solid body to indicate the embedding position of the tube accommodating the optical fiber core, the required optical fiber core can be easily accommodated when the cable is branched. The position of the broken tube can be known, and the workability of branching work can be greatly improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an optical fiber cable according to an embodiment of the present invention.

FIG. 2 is a perspective view of the embodiment shown in FIG.

3A and 3B are cross-sectional views showing the configuration of an optical fiber cable according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of an optical fiber cable according to still another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the configuration of an optical fiber cable according to still another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing another configuration example of the optical fiber unit according to the embodiment of the invention.

FIG. 7 is a cross-sectional view showing still another configuration example of the optical fiber unit according to the embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of a conventional self-supporting optical fiber cable.

[Explanation of symbols]

 4 ……… Tension member 5 ……… Solid body 6 ……… Tube 7 ……… Optical fiber core wire 9 ……… Groove 10 ……… Fin-like protrusion 11 ……… Optical fiber cable 12 ……… Support Wire 13 ... Cable jacket 15 ... Optical fiber tape core wire

Claims (3)

[Claims] 1. A tension member, and a solid body provided on the outer periphery of the tension member, and
An optical fiber cable, wherein a tube having at least one optical fiber core wire loosely housed therein is embedded in the solid body in a meandering manner in a length direction. 2. The optical fiber cable according to claim 1, wherein an outer periphery of the solid body is provided with a marking indicating a buried position of a tube accommodating the optical fiber core wire. 3. An optical fiber cable main body in which a tube, in which at least one optical fiber core wire is housed loosely, is embedded in the solid body in a meandering manner in the longitudinal direction.
An optical fiber cable comprising: a cable support wire arranged in parallel with the optical fiber cable body; and a cable jacket that collectively covers these.