JP3745921B2 - Optical fiber cable for aerial installation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aerial laying optical fiber cable, and more particularly to an optical fiber cable that enables high-density accommodation of optical fiber core wires and intermediate rear branching.
[0002]
[Prior art]
As an optical fiber cable containing an optical fiber core wire at a high density, a cable as described in Japanese Patent Application Laid-Open No. 8-21162 is known. This optical fiber cable accommodates a laminated body of tape-shaped multi-core optical fibers in the SZ spiral groove of the inner groove groove spacer having a tensile body at the center and a plurality of SZ spiral grooves on the outer periphery. Outside, a plurality of segment-type groove members are SZ twisted with the grooves facing outward to form a spacer with an outer layer groove, and a tape-shaped multi-core optical fiber is accommodated in the groove of the segment-type groove member However, a sheath is provided on the outside.
[0003]
Thus, in order to accommodate the optical fiber cores at high density, it is effective to provide a spacer with inner layer grooves and spacers with outer layer grooves so that the optical fiber cores are accommodated in the grooves of each spacer. . However, in the case of an optical fiber cable laid overhead, there are cases in which the laying tension cannot be withstood only by the tension member disposed at the center of the inner layer grooved spacer. For this reason, conventionally, it has been proposed to provide a layer of tensile strength on the outer side of the outer grooved spacer, or to provide a suspension line in parallel with the cable body and to integrate them with a common sheath to be a self-supporting type. .
[0004]
On the other hand, in the case of an aerial laying optical fiber cable, it is a structure capable of intermediate post-branching at any position as needed (taken off an optical fiber core wire from an arbitrary position of the optical fiber cable after aerial laying). Is required. For that purpose, it is preferable that the outer-layer grooved spacer is formed as an SZ spiral groove and the optical fiber core wire can be taken out from the outer-layer grooved spacer by peeling the sheath in the middle.
[0005]
[Problems to be solved by the invention]
However, as described above, in the structure in which the tensile strength layer is provided outside the outer layer grooved spacer, the optical fiber core wire cannot be taken out even if the sheath is peeled off in the middle, and the self-supporting type Also in this case, there is a problem that it is difficult to take out the optical fiber core wire because the suspension wire is in the way.
[0006]
Accordingly, an object of the present invention is a high-density cable structure having a spacer with an inner layer groove and a spacer with an outer layer groove, which has a tensile strength that can withstand the aerial installation tension and can easily perform branching after intermediate. It is to provide an optical fiber cable for use.
[0007]
[Means for Solving the Problems]
In order to achieve this object, an aerial laying optical fiber cable according to the present invention accommodates an optical fiber core wire in the groove of an inner-layer grooved spacer having a unidirectional spiral groove or SZ spiral groove on the outer periphery, and on the outside thereof. An intermediate layer of strength members that handle the tension at the time of aerial laying is provided, an outer layer grooved spacer having an SZ spiral groove is provided on the outer periphery thereof, and an optical fiber core wire is accommodated in the SZ spiral groove, and the outer side thereof. A sheath is provided without a layer of tensile strength.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a spacer with an inner layer groove, and 2 is a spacer with an outer layer groove. The inner-layer grooved spacer 1 has a strength member 3 in the center and a required number of unidirectional spiral grooves 4 (or SZ spiral grooves) on the outer periphery, and each unidirectional spiral groove 4 has a tape-like light. A plurality of fiber core wires 5 are accommodated in a stacked state. A presser winding 6 is applied to the outer side of the inner layer grooved spacer 1, and an intermediate layer of the strength member 7 is provided on the outer side thereof.
[0009]
If the optical cable is desired to be lightened, it is preferable to use a high-strength fiber such as polyaramid fiber (trade name Kevlar, etc.), glass FRP, PBO fiber, etc. It is also possible to use it. When twisting high tensile strength fibers or steel wires, it is preferable to twist the two layers by changing the twist direction so that torque is not generated when tension is applied. The thickness of the intermediate layer of the strength member 7 is about 0.1 to 2.0 mm, usually about 1.0 to 2.0 mm, when a high strength fiber is used. When a steel wire is used for the strength member 7, it is preferable to provide a plastic inner sheath on the inner side in order to prevent damage to the tape-shaped optical fiber 5 in the inner grooved spacer 1. A tear string 8 is vertically attached to the outer side of the intermediate layer of the strength member 7.
[0010]
The outer layer grooved spacer 2 is provided outside the intermediate layer of the strength member 7. The outer-layer grooved spacer 2 has a required number of SZ helical grooves 9 on the outer periphery, and a plurality of tape-shaped optical fiber cores 10 are accommodated in each SZ helical groove 9. The outer grooved spacer 2 can be formed by extrusion molding of a resin, or can be formed by SZ twisting a segment type groove member. A presser winding 11 is applied to the outside of the outer grooved spacer 2, and a plastic sheath 12 is coated on the outside.
The outer diameter of the inner grooved spacer 1 of this cable is about 250 mm, the outer diameter of the outer grooved spacer 2 is about 300 mm, and the pitch of the SZ spiral groove 9 is about 50 to 1000 mm (usually 250 to 300 mm). .
[0011]
Since the optical fiber cable of this embodiment has a structure in which the outer layer grooved spacer 2 is provided outside the inner layer grooved spacer 1 as described above, the optical fiber core wire can be accommodated at a high density. Further, since the intermediate layer of the strength member 7 is provided between the spacer 1 with the inner layer groove and the spacer 2 with the outer layer groove, the tensile strength that can sufficiently withstand the aerial laying tension can be provided and the outer side of the spacer 2 with the outer layer groove is provided. Therefore, if the sheath 12 is peeled off in the middle, the tape-shaped optical fiber core wire 10 can be easily taken out from the SZ spiral groove 9 of the outer-layer grooved spacer 2, and the intermediate post-branching operation can be performed efficiently. It can be carried out. The groove 4 of the spacer 1 with the inner layer groove accommodates a tape-shaped optical fiber core wire 5 that does not need to be branched after intermediate.
[0012]
【The invention's effect】
As described above, the aerial laying optical fiber cable according to the present invention can accommodate optical fiber core wires at high density and has a tensile strength that can withstand aerial laying tension by providing an intermediate layer of a tensile strength body. In addition, there is an advantage that the intermediate post-branch can be easily performed because there is no tensile strength layer or suspension line outside the outer grooved spacer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of an aerial laying optical fiber cable according to the present invention.
[Explanation of symbols]
1: Spacer with inner layer groove 2: Spacer with outer layer groove 3: Central tensile member 4: Unidirectional helical groove 5: Tape-shaped optical fiber core wire 7: Tensile member 9: SZ helical groove
10: Tape optical fiber core
12: Sheath

Claims (1)

An optical fiber core wire is accommodated in the groove of the inner-layer grooved spacer having a unidirectional spiral groove or SZ spiral groove on the outer periphery, and an intermediate layer of a tensile body that handles the tension at the time of aerial installation is provided on the outer side. An outer layer grooved spacer having an SZ spiral groove is provided on the outer periphery, an optical fiber core wire is accommodated in the SZ spiral groove, and a sheath is provided without providing a layer of tensile strength on the outer side. Optical fiber cable for aerial installation.

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