JPH08114731A - Optical cable pipeline - Google Patents

Abstract

PURPOSE: To provide an optical cable which is capable of applying sufficient surplus length uniform in a longitudinal direction on an optical fiber, eliminating a possibility of degradation in transmission characteristic and breakage by loading of tension and permitting easy branching. CONSTITUTION: The outer periphery of a slot rod 5 having recessed grooves 6 formed in the state twisted in SZ directions, etc., along the longitudinal direction on the outer peripheral surface is provided with a retaining winding layer 7 by winding of a retaining winding tape, etc., to delineate a space for force feeding of optical fibers between these recessed grooves 6 and the retaining winding layer 7. Tubes for force feeding the optical fibers are otherwise arranged in the recessed grooves 6. A supporting wire is arranged on such core 8 in parallel therewith and the core and the supporting wire are integrally coated with a sheath 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable line which allows easy addition and modification of optical fibers after installation.

[0002]

2. Description of the Related Art As the application of optical communication to various information networks is rapidly expanding, a cable pipe is installed in advance when the network is constructed, and then an optical fiber cable is pulled in as necessary. Roads have been devised, and are attracting attention as being able to respond to future demand growth and network expansion in a timely manner.

FIG. 5 shows an example of such a cable conduit, in which a plurality of conduits 1 are linearly bundled to form a core 2.
A support wire 3 made of a steel wire or the like is vertically provided on the core 2 with a space therebetween, and an outer jacket 4 having a dharma section is integrally provided on the outer periphery of the support wire 3.

By the way, when an optical fiber is drawn into such a cable conduit after being laid, it is important to give a sufficient extra length to the optical fiber, preferably uniformly in the longitudinal direction. This is because the actually laid cable expands and contracts due to changes in the ambient temperature, etc., but the coefficient of thermal expansion of the optical fiber is much smaller than the coefficient of thermal expansion of the material forming the support wire 3, so the extra length is small. This is because the optical fiber cannot follow the expansion and contraction of the support line 3, and it is necessary to secure an extra length for branching after installation.

[0005]

However, in the conventional cable conduit as described above, it is difficult to give the optical fiber in the conduit 1 a sufficient excess length evenly, and the branching work is difficult. There was a problem that it was difficult.

The present invention has been made in order to solve these problems, and it is possible to give a sufficient extra length to the optical fiber and a uniform extra length in the longitudinal direction, and to improve the transmission characteristics due to the load of tension. It is an object of the present invention to provide an optical cable conduit which is not likely to deteriorate or break and which can be easily branched.

[0007]

A first optical cable conduit of the present invention has a slot rod having a groove formed in the outer peripheral surface in a twisted state along the length direction, and a slot rod on the outer periphery of the slot rod. A coating layer is provided to cover the opening of the concave groove, and a space for optical fiber pumping is defined between the concave groove and the coating layer.

The second optical cable conduit of the present invention is
It is characterized by comprising a slot rod having a concave groove formed on the outer peripheral surface in a twisted state along the length direction, and an optical fiber pumping tube housed in the concave groove.

Here, the optical fiber pressure-feeding space or the optical fiber pressure-feeding tube is a construction method of pressure-feeding an optical fiber core wire or an optical fiber unit using the flow pressure of a gas such as compressed air (pressure feed installation). A space or tube to which the construction method) is applied.

[0010]

In the optical cable line of the present invention, since the optical fiber pressure feeding space or the optical fiber pressure feeding tube is formed or arranged in a twisted state, the optical fiber to be pressure fed and laid in these spaces is provided. Can easily provide a sufficient extra length uniformly in the length direction. Therefore, deterioration and breakage of the transmission characteristics of the optical fiber due to the load of tension are prevented, and branching is facilitated.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment in which the optical cable conduit of the present invention is applied to a self-supporting optical cable.
In FIG. 1, 5 indicates a slot rod in which a plurality of concave grooves 6 are formed on the outer peripheral surface, and each concave groove 6 is, as shown in FIG. 2, centered on the axis of the slot rod 5 in the S direction, SZ, or SZ in which the S and Z directions are alternately repeated
It is formed in a twisted state (note that FIG. 2 shows S
The concave groove 6 twisted in the direction is shown. ). A holding winding layer 7 formed by winding a holding tape is provided on the outer periphery of the slot rod 5, and constitutes a core 8 together with the slot rod 5. Further, on the core 8, a supporting wire 9 made of a steel wire or the like is arranged along the length direction thereof, and a jacket 10 formed in a dulled cross section by collective extrusion of plastic.
Are integrally connected by. In FIG. 1, 1
Reference numeral 1 denotes a neck portion of the jacket 10.

And, in this optical cable conduit,
If necessary, the space between the concave grooves 6 and the press-wound layer 7 covering them is used as an optical fiber pressure feeding space, in which the optical fiber core wire 12 or a plurality of optical fiber core wires as shown in FIG. An optical fiber unit 16 having a structure in which 12 is bundled together with a tear cord 13 and a nylon resin coating 14 and a foamed polyethylene layer 15 are sequentially coated thereon is laid by being sent under pressure by compressed air or the like. Each groove 6 is formed in a twisted state around the axis of the slot rod 5, and the optical fiber core wire 12 or the optical fiber unit 16 has a sufficient extra length with respect to the support wire 9. And the surplus length ratio becomes substantially uniform in the length direction. Therefore, for example, even if the cable expands and contracts due to changes in the ambient temperature, the characteristics of the optical fiber are not deteriorated and a disconnection accident is not caused, and branch connection can be easily performed.

Next, another embodiment of the present invention shown in FIG. 4 will be described.

In this embodiment, a press winding layer 7 is provided on the outer circumference of the slot rod 5 having a plurality of grooves 6 formed on the outer peripheral surface thereof.
Are formed to form the core 8, the support wires 9 are arranged in parallel on the core 8, and the outer circumferences thereof are collectively covered with the jacket 10. Further, the plurality of concave grooves 6 are formed. Centering around the axis of the slot rod 5, the S direction, Z direction, or S direction
It is the same as the above embodiment in that it is formed in a twisted state in the SZ direction in which the Z direction and the Z direction are alternately repeated.

In this embodiment, however, the optical fiber pressure feeding tube 17 made of polyethylene or the like is housed in each groove 6 on the outer peripheral surface of the slot rod 5.

In the thus constructed optical cable conduit, after installation, when necessary, the optical fiber core wire 12 or the optical fiber unit 16 as described above is provided.
However, the optical fiber pressure feeding tube 1 is manufactured by the pressure feeding construction method.
The optical fiber pressure feeding tube 1
Since 7 is housed in the concave groove 6 formed by twisting, the optical fiber core wire 12 or the optical fiber unit 16 is laid on the support wire 9 with a sufficient extra length, and the extra length ratio is increased. It can be made substantially uniform in the length direction. Therefore, as in the case of the above-mentioned embodiment, the deterioration of the characteristics of the optical fiber and the disconnection due to the tension are prevented, and the branching can be easily performed.

Although the embodiment described above has a self-supporting structure suitable for aerial installation, the present invention is not limited to such an embodiment, and, for example, the support wire 9 is not provided. The cross-sectional structure may be round, or the tension member may be arranged at the center of the slot rod 5.

[0018]

As described above, according to the optical cable conduit of the present invention, the optical fiber pressure-feeding space or the optical fiber pressure-feeding tube is formed or arranged in a twisted state. A sufficient extra length can be easily and almost uniformly provided in the length direction to the optical fiber to be pumped therein. Therefore, deterioration of the characteristics of the optical fiber and breakage of the optical fiber due to tension can be prevented, and branching can be easily performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an optical cable conduit of the present invention.

FIG. 2 is a perspective view showing a groove formed on the outer peripheral surface of the slot rod in the embodiment.

FIG. 3 is a sectional view showing an example of an optical fiber unit.

FIG. 4 is a perspective view showing another embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional example.

[Explanation of symbols]

 5 ………… Slot rod 6 ………… Concave groove 7 ………… Presser winding layer 9 ………… Support wire 10 ………… Outer sheath 17 ………… Optical fiber pumping tube

Claims (3)

[Claims] 1. A slot rod having a concave groove formed on the outer peripheral surface in a twisted state along the length direction, and a coating layer provided on the outer periphery of the slot rod and covering the opening of the concave groove. An optical cable conduit, comprising an optical fiber pumping space defined between the groove and the coating layer. 2. A slot rod having a concave groove formed on the outer peripheral surface in a twisted state along the length direction, and an optical fiber pressure-feeding tube housed in the concave groove. A characteristic optical cable conduit. 3. The optical cable line according to claim 1 or 2, wherein support wires are arranged parallel to the slot rods, and outer peripheries thereof are integrally covered.