JP3710040B2 - Fiber optic cable - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical fiber cable capable of branching an optical fiber core wire from an arbitrary point in the middle of an installed cable.
[0002]
[Prior art]
One of the basic structures of optical fiber cables is a loose tube structure. This is a tube made of plastic such as polybutylene terephthalate or polypropylene, in which an optical fiber core wire or a tape core wire is accommodated, and a gap is filled with a gel filler such as jelly. As a loose tube structure cable, as shown in FIG. 4 (a), a plurality of tubes 6 containing optical fibers 7 are gathered around a central strength member 10, and as shown in FIG. 4 (b). In addition, there is a central core type having a loose tube portion at the center of the cable, in which a laminated body of tape cores 1 is housed.
[0003]
The tape core wire is formed by arranging a plurality of, for example, four optical fibers in parallel and integrating them with resin to form a tape. Since such a tape core can be in a free state in a complete free space, each optical fiber is not locally bent, and transmission loss is hardly increased. However, when multiple tape cores are placed in a closed space, the movement of each tape core that occurs with the change in the closed space interferes with each other, making it impossible for some of the tape cores. The transmission loss increases due to the additional bending.
[0004]
Therefore, in an optical fiber cable using a conventional tape core, by forming two or more tape cores to form an aggregate, the behavior direction of each tape core is substantially the same, and some tapes Only the core wire is prevented from obstructing movement. In the central core type optical fiber cable, such a tape core laminated body is accommodated in a loose tube, a gap is filled with a jelly 8, and a jacket 3 together with strength members 4 and 4 is placed thereon. Is forming. Then, by adjusting the viscosity of the jelly 8 appropriately, even if an external force such as pulling and bending is applied to the cable, the tape core wire 1 moves in the tube and can relieve the stress applied to the optical fiber. .
[0005]
As described above, the optical fiber cable having the loose tube structure has excellent characteristics, but has a drawback that workability at the time of connection is poor. That is, when the cable is connected, it is necessary to wipe off the jelly 8, and at that time, it is necessary to carefully work so as not to damage or break the tape core wire 1 and the optical fiber therein. Take it.
[0006]
Therefore, in Japanese Patent Application No. 10-116230, we previously proposed an optical fiber cable that protects an optical fiber by placing a fiber body around the tape core laminate instead of the jelly 8. . In the cable, the tape core laminate was further twisted about its central axis so that each tape core of the tape core laminate was constrained and the collapse of the stack was reduced. In addition, when pulling out the tape core at the middle part of the cable when connecting the cable, the fiber body has a large extra length, and a gap is created between the tape core laminate and the fiber body, making it easy to work. The fiber body was twisted around the outer periphery of the tape core laminate so as to be arranged. As a result, it was possible to realize an optical fiber cable with good workability at the time of cable connection while suppressing cost.
[0007]
[Problems to be solved by the invention]
By the way, in such an optical fiber cable, it is necessary to separate the fiber body and the tape core wire and take out only the tape core wire when removing the cable jacket and taking out the tape core wire during the intermediate branching operation. There is. However, in the optical fiber cable, the fiber body is disposed around the tape core laminate, and the fiber body and the tape core are integrated. Therefore, at the time of intermediate branching work, the fiber body is cut and removed to separate the fiber body and the tape core wire, and the tape core wire is not cut together with the fiber body when taking out only the tape core wire. There was a problem that careful attention was required and there were still insufficient points to improve workability.
[0008]
An object of the present invention is to solve such problems and to facilitate the separation of a tape core and a fiber body during an intermediate branching operation and to improve workability.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problem, the optical fiber cable according to claim 1 is an optical fiber cable in which the entire outer periphery of the optical fiber core wire is covered with a continuous fiber body in the longitudinal direction, and an outer sheath is formed on the outer periphery thereof. The fiber body is divided into a plurality of fiber bundles, and a winding material is spirally wound around the outer periphery of each fiber bundle. If it does in this way, isolation | separation of a tape core wire and a fiber bundle will become easy at the time of an intermediate | middle branch operation | work, and workability | operativity will improve.
[0010]
The optical fiber cable according to claim 2 is characterized in that the color of the wound material is different from the color of the fiber bundle. If it does in this way, at the time of a separation operation | work, identification of each fiber bundle will become easy and workability | operativity will improve.
[0011]
The optical fiber cable according to claim 3 is characterized in that a winding pitch of the winding material is 500 mm or less. In this way, the winding material completely surrounds the circumference of the fiber bundle within the normal range of 500 mm for removing the outer cover during the intermediate branching operation, and separation of each fiber bundle becomes easy. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of one embodiment of the present invention. In FIG. 1, 1 is a tape core wire, 2 is a fiber bundle, 3 is a jacket, and 4 is a strength member.
[0013]
The tape core wire 1 is formed in a tape shape by embedding four optical fibers arranged in parallel in a resin and integrating them. The entire outer periphery of the tape core laminate in which six such tape cores 1, 1,... Are laminated is covered with a plurality of fiber bundles 2 that are continuous in the longitudinal direction, and the outside thereof is a tensile body. 4 and 4 are integrally covered with an envelope 3 embedded therein. Thus, by attaching a plurality of fiber bundles 2 so as to surround the entire circumference of the tape core laminate, by covering the tape core laminate from the outside with the fiber bundle 2 and pressing it down, Each of the tape cores 1 is restrained from moving independently to suppress the occurrence of bends due to local buckling of some of the tape cores 1. Furthermore, if twist is given to the whole, each tape core wire 1 of a tape core wire laminated body will be restrained, and lamination | stacking collapse will decrease.
[0014]
FIG. 2 shows a state in which a part of the jacket of the optical fiber cable is removed. In FIG. 2, 5 is a winding material. The fiber bundle 2 is formed by bundling a long fibrous body made of polypropylene or the like into an appropriate thickness, and winding the wound material 5 around the outer periphery in a spiral manner so that the fiber bundle 2 can be easily separated into individual fiber bundles 2. Yes. As a result, at the time of the intermediate branching operation, the winding material 5 of each fiber bundle 2 is picked and pulled away from the tape core laminate so that the individual fiber bundles 2 can be removed in a lump. It is possible to easily perform the pull-out operation of 1 manually.
[0015]
The fiber bundle 2 may be twisted or may not be twisted. Further, the winding material 5 may be formed in a tape shape or a string shape, and may be formed of the same fiber as the fibrous body, or may be formed of another material different from that. Furthermore, it is preferable that the winding material 5 has a color different from that of the fiber bundle 2. By doing so, the winding material 5 and each fiber bundle 2 can be easily identified, and the workability is further improved.
[0016]
Further, in order to take out the tape core wire during the intermediate branching operation, the outer cover 3 is removed. At this time, the outer cover 3 is usually removed with a length of about 500 mm. Considering this, the pitch for winding the wound material 5 is set to 500 mm or less. If it does so, as shown in FIG. 3, the winding material 5 will be wound at least 1 round around each fiber bundle 2 within the jacket removal section, and within the jacket removal section. The bundle is held without the fiber bundles 2 being separated, and the handling becomes easy.
[0017]
【Example】
Six standard 4-core tape cores having a thickness of 0.3 mm and a width of 1.1 mm were laminated to form a tape core laminate. Then, 6000 deniers of polypropylene materials were collected, and a 3 mm wide polypropylene tape was wound around the outer periphery at a pitch of 250 mm to form a fiber bundle 2. Ten such fiber bundles 2 are attached to the outer periphery of the tape core laminate, and the cable core is formed by twisting the tape core laminate and the ten fiber bundles 2 at a pitch of 500 mm integrally. did. Then, two 1.2 mm steel wires were arranged in parallel as tensile strength members 4 and 4 on both sides of the cable core, and were integrated with a jacket 3 made of polyethylene to form an optical fiber cable.
[0018]
Then, the optical fiber cable was wound around a drum having a body diameter of 1000 mm, the temperature was changed from -30 to 70 ° C., and the transmission loss at a wavelength of 1.55 μm was measured. As a result, the average transmission loss was 0.2 dB / km, and good characteristics were obtained. Moreover, when the intermediate jacket 3 was removed by 500 mm and the wound material 5 of each fiber bundle 2 was pulled outward, the fiber bundle 2 could be easily separated from the tape core laminate.
[0019]
In the above embodiment, a tape core is used as the optical fiber core. However, the optical fiber cable to which the present invention can be applied is not limited thereto, and is also applied to an optical fiber cable in which a plurality of optical fiber cores are assembled. it can.
[0020]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
That is, in the optical fiber cable according to claim 1, the fiber body is divided into a plurality of fiber bundles, and the winding material is spirally wound around the outer periphery of each fiber bundle. Separation from the fiber bundle is facilitated, and workability is improved.
[0021]
In the optical fiber cable according to the second aspect, since the color of the winding material is different from the color of the fiber bundle, each fiber bundle can be identified at the time of separation work, and the work becomes easier.
[0022]
Further, in the optical fiber cable according to claim 3, since the winding pitch of the winding material is 500 mm or less, the winding material is around the fiber bundle within a normal range of 500 mm for removing the jacket during the intermediate branching operation. Is completely surrounded by one round, and separation of each fiber bundle becomes easy.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of one embodiment of the present invention.
2 is a view showing a state in which a part of the jacket of the optical fiber cable in FIG. 1 is removed. FIG.
FIG. 3 is a diagram showing a jacket removing portion at the time of intermediate branching work.
FIG. 4 is a cross-sectional view of a conventional optical fiber cable.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Tape core wire 2 ... Fiber bundle 3 ... Outer sheath 4 ... Strength body 5 ... Winding material 6 ... Tube 7 ... Optical fiber 8 ... Jerry 9 ... Outer sheath 10 ... Center strength body

Claims (3)

In an optical fiber cable in which the entire outer periphery of the optical fiber core is covered with a continuous fiber body in the longitudinal direction and an outer sheath is formed on the outer periphery, the fiber body is divided into a plurality of fiber bundles, and the outer periphery of each fiber bundle is An optical fiber cable characterized by spirally winding a winding material. 2. The optical fiber cable according to claim 1, wherein a color of the wound material is different from a color of the fiber bundle. The optical fiber cable according to claim 1 or 2, wherein a winding pitch of the winding material is 500 mm or less.

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