JPH11194245A - Optical fiber cable and branching method for optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the optical fiber cable which can improve the efficiency of branching operation and is small in material cost and fitting cost and suitable to a low-cost prefabricated branch cable. SOLUTION: At a halfway point of an optical fiber cable 10 formed by alternately stranding an optical fiber cord reinforcing wire 2 and an optical fiber cord 3 around a tension member, the optical fiber cord reinforcing wire 2 and optical fiber cord 3 are cut and led out and this lead-out part 2a of the optical fiber cord reinforcing wire 2 is wound with the lead-out part 3a of the optical fiber cord to complete the branching operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable, and more particularly to an optical fiber cable suitable for prefabricated branching.

[0002]

2. Description of the Related Art A prefabricated branch cable is composed of an aggregate of a plurality of communication lines. The prefabricated branch cable is laid in advance in a condominium or other apartment complex, and if necessary, the communication line is branched off in the middle thereof. The line is supplied to the subscriber.
Conventionally, prefabricated branch cables for communication used in apartment houses such as condominiums are composed of metal communication lines, and for example, a metal twisted cord or a coaxial cord is used. However, a prefabricated branch cable using an optical fiber is conceivable for application to broadband information transmission in the future.

[0003] In an optical fiber cable, a plastic sheath is provided on an assembly of a plurality of optical fiber cords, for example, in order to prevent the performance of the optical fiber from deteriorating due to external stress. Configuration. Therefore, in order to branch the optical fiber cord from the optical fiber cable, the sheath must first be peeled off and removed, resulting in low branching operation efficiency and high processing cost. Further, in order to make the sheath easy to peel off, the constituent material of the sheath is limited. Further, when a closure is used for branching, a space for installing the closure is required at each branching point, and the material cost increases. On-site work such as installation of a closure at a branch point is required. For these reasons, there is a problem that the cost is increased in the ordinary optical fiber cable.

On the other hand, a configuration in which a sheath at a branching point of an optical fiber cable is removed in advance and a cylindrical branching protection case which is slightly larger than the outer diameter of the optical fiber cable is covered on a portion where the optical fiber cord is exposed. It is also conceivable to lay something. In this case, at the time of branching, the optical fiber cord can be directly taken out from the branch protection case and branched. This configuration requires less installation space than the case where a closure is provided, and can reduce on-site work. However, since the optical fiber cord has low bending characteristics, it is necessary to attach a component to be protected to the optical fiber cord so that the optical fiber cord drawn out of the branch protection case is not bent excessively and deteriorated. Therefore, after all, on-site work is required, and further, not only a branch protection case but also other new parts are required, so that the material cost and the mounting cost are increased, and it is difficult to improve the work efficiency and cost.

[0005]

Accordingly, an object of the present invention is to provide an optical fiber cable suitable for a low-cost prefabricated branch cable which can improve the operation efficiency of branching, has low material and mounting costs, and is low in cost. And

[0006]

According to a first aspect of the present invention, an optical fiber cord and an optical fiber cord reinforcing wire are alternately twisted on a tension member. Optical fiber cable. A second invention is the optical fiber cable according to the first invention, wherein an outer diameter of the optical fiber cord reinforcing wire is larger than an outer diameter of the optical fiber cord. According to a third aspect of the present invention, an optical fiber cord reinforcing wire and an optical fiber cord are cut and pulled out in the middle of an optical fiber cable in which an optical fiber cord reinforcing wire and an optical fiber cord are alternately twisted on a tension member. A method for branching an optical fiber cable, wherein the branch is performed by winding or attaching the drawn-out optical fiber cord to an optical fiber cord reinforcing wire.

[0007]

FIG. 1 is a sectional view showing an example of an optical fiber cable according to the present invention. 2 and 3 are plan views showing the operation of branching the optical fiber cable shown in FIG. In the figure, reference numeral 1 denotes a tension member 1, on which six optical fiber cord reinforcing wires (hereinafter abbreviated as reinforcing wires) 2 and six optical fiber cords 3 are provided one by one. They are alternately twisted. In this optical fiber cable 10, the outer diameter of the reinforcing wire 2 is sufficiently larger than the outer diameter of the optical fiber cord 3, and the adjacent reinforcing wires 2 are in contact with each other. 1 and 6 are formed. Then, one optical fiber cord 3 is inserted into these gaps.
Books are arranged one by one. Further, a holding cord 4 is wound on the assembly in a direction opposite to the twisting direction of the reinforcing wire 2 and the optical fiber cord 3, and the optical fiber cable 10 is wound.
Is configured. One branch line 2 for branching work
And one optical fiber cord 3 in contact with the reinforcing wire 2 is treated as one set.

In order to perform branching in the optical fiber cable 10, for example, as shown in 2, a pair of reinforcing wires 2 and an optical fiber cord 3 are cut and pulled out in the middle. At this time, the length of the lead portion 3a of the optical fiber cord 3 is made longer than the length of the lead portion 2a of the reinforcing wire 2. Next, the drawer 3 of the optical fiber cord 3
The lead portion 3a of the optical fiber cord 3 is wrapped around the lead portion 2a of the reinforcing wire 2 to protect the optical fiber cord 3 from being bent so that the performance is not deteriorated. Furthermore, the branching operation is completed by, for example, fusing the end of the lead-out portion 3a of the optical fiber cord 3 to another external optical fiber cord or the like or connecting the connector.

The optical fiber cable 10 can be manufactured by alternately twisting the reinforcing wires 2 and the optical fiber cords 3 on the tension member 1 and further winding the holding cord 4.

The tension member 1 is made of steel wire or the like.
The size can be appropriately changed according to the size of the reinforcing wire 2 or the optical fiber cable 10, the number of cores of the optical fiber cable 10, and the like.

The reinforcing wire 2 must have a certain degree of rigidity so that the lead-out portion 3a of the optical fiber cord 3 wound around the lead-out portion 2a of the reinforcing wire 2 in the above-mentioned branching operation is not excessively bent. No. For this reason, as a material of the reinforcing wire 2, a metal such as steel or a plastic such as polyethylene is used.

In this example, the outer diameter of the reinforcing wire 2 is sufficiently large, the adjacent reinforcing wires 2 are in contact with each other, and an optical fiber is inserted into a gap surrounded by the tension member 1 and the two reinforcing wires 2. Code 3 is arranged. For this reason, since the optical fiber cord 3 is not exposed on the outer surface of the optical fiber cable 10, external stress is less likely to affect the optical fiber cord 3, and mechanical properties can be improved without providing a sheath. it can.

However, even if the optical fiber cord 3 cannot be completely contained in the gap, if the outer diameter of the reinforcing wire 2 is designed to be at least larger than the outer diameter of the optical fiber cord 3, the Since 3 is disposed inside the circumscribed circle of the optical fiber cable 10, external stress is first absorbed by the reinforcing wire 2. Therefore, the influence on the optical fiber cord 3 is reduced, and the mechanical characteristics of the optical fiber cable 10 can be improved. In order to make the size of the optical fiber cable 10 as small as possible with emphasis on space efficiency, the outer diameter of the reinforcing wire 2 is preferably set to be one time the outer diameter of the optical fiber cord 3.

As the reinforcing wire 2, a power line, a metal communication line, or the like can be used. As a power line, for example,
For example, a conductor obtained by providing a coating made of a plastic such as polyethylene on a conductor obtained by twisting a plurality of copper wires is used. As the metal communication line, a single-core coated copper wire coated with plastic is twisted, and a wire coated thereon is used. If a power line is used as the reinforcing wire 2, the optical fiber cable 10 becomes a composite cable with the power line. Therefore, it is not necessary to separately lay the communication cable and the power cable, and the space for laying cables can be reduced in an apartment house or the like. Further, if a metal communication line is used as the reinforcing wire 2, an optical metal communication composite cable is obtained, and switching between the metal communication line and the optical communication can be easily performed. If the power line or the metal communication line laid in an apartment house or the like is combined as described above, further space saving and cost reduction can be achieved.

The optical fiber cord 3 is composed of an ordinary bare optical fiber having an outer diameter of 125 μm made of quartz glass and coated with a plastic made of a silicone resin, an ultraviolet curable resin, or the like. above,
In addition, a coating layer made of nylon or the like is formed with a plurality of tensile strength members such as aramid fibers vertically attached, and has an outer diameter of about 1 mm.

The presser cord 4 is not indispensable, but is preferably provided to keep the twisting of the reinforcing wire 2 and the optical fiber cord 3 stable. The presser winding string 4 may be a string shape or a tape shape, and the outer diameter (width) and the winding pitch (interval) are adjusted according to the size of the optical fiber cable 10 and the workability of branching. . Examples of the material for the presser cord 4 include a color tie having an iron wire having an outer diameter of about 0.5 mm provided with a coating made of polyvinyl chloride (PVC).

FIGS. 1 to 3 show examples in which the outer diameter of the reinforcing wire 2 is larger than the outer diameter of the optical fiber cord 3. As an example, a six-core optical fiber cable 10 in which the outer diameter of the reinforcing wire 2 is 6.5 times the outer diameter of the optical fiber cord 3
An example of the configuration is shown below. That is, the tension member 1 is made of, for example, a steel wire and has an outer diameter of 6.5 mm. The reinforcing wire 2 is made of, for example, polyethylene and has an outer diameter of 6.5 mm. The outer diameter of the optical fiber cord 3 is 1.0
mm. In these examples, the six-core optical fiber cable 10 has been described, but the number of cores, the size, and the like can be changed as appropriate.

In this optical fiber cable 10,
Necessary mechanical characteristics can be obtained without providing a sheath, so that there is no need to remove the sheath, and the efficiency of branching can be improved. Also, since one reinforcing wire 2 and one optical fiber cord 3 are twisted as a set, at the time of branching, the set of reinforcing wire 2 and the optical fiber cord 3 are pulled out, and furthermore, By winding the lead portion 3a of the optical fiber cord 3 around the lead portion 2a of the reinforcing wire 2, it is possible to prevent the lead portion 3a of the optical fiber cord 3 from being bent more than necessary and deteriorating its performance.

Further, by arranging the optical fiber cords 3 between the reinforcing wires 2 whose outer diameters are larger than the outer diameter of the optical fiber cords 3, the optical fiber cords 3 are located inside the circumscribed circle of the optical fiber cable 10. And the external stress is absorbed by the reinforcing wire 2, so that the influence of the external stress on the optical fiber cord 3 is reduced, and the mechanical characteristics of the optical fiber cable 10 can be improved. Further, since there is no need to attach a special component such as a closure, space efficiency is excellent, and material costs and installation costs can be kept low. With these effects, cost reduction can be achieved.

[0020]

As described above, the optical fiber cable according to the present invention can obtain the required mechanical characteristics without providing a sheath, so that the efficiency of branching can be improved. Further, by winding the optical fiber cord around the optical fiber cord reinforcing wire at the time of branching, it is possible to prevent the optical fiber cord from being bent more than necessary and deteriorating its performance. Further, since there is no need to attach a special component such as a closure, space efficiency is excellent, and material costs and installation costs can be kept low. With these effects, cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an optical fiber cable according to the present invention.

FIG. 2 is a plan view showing an operation of branching the optical fiber cable shown in FIG.

FIG. 3 is a plan view showing an operation of branching the optical fiber cable shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tension member, 2 ... Optical fiber cord reinforcement wire (reinforcement line), 2a ... Lead-out part, 3 ... Optical fiber cord, 3a ... Lead-out part, 10 ... Optical fiber cable.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Takada 2899 Dagahara, Oita City, Oita Prefecture Nishi Nippon Electric Wire & Cable Co., Ltd. ) Inventor: Akio Mogi, 1440, Misaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Plant, Inc. 1440 Fujikura Co., Ltd.Sakura Plant, Fujikura Co., Ltd.

Claims (3)

[Claims] 1. An optical fiber cable, wherein an optical fiber cord and an optical fiber cord reinforcing wire are alternately twisted on a tension member. 2. An outer diameter of the optical fiber cord reinforcing wire is as follows:
The optical fiber cable according to claim 1, wherein the cable is larger than the outer diameter of the optical fiber cord. 3. An optical fiber cord reinforcing wire and an optical fiber cord are cut and pulled out in the middle of an optical fiber cable in which an optical fiber cord reinforcing wire and an optical fiber cord are alternately twisted on a tension member, and the drawn out. A method for branching an optical fiber cable, wherein the optical fiber cord is wound around or attached to an optical fiber cord reinforcing wire to perform branching.