JPH11264924A - Optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable which can prevent a transmission loss due to a drop in temperature from increasing and also prevent the loss from increasing when its connector is connected to a terminal. SOLUTION: The optical fiber cable is constituted by coating ribbons 9 of coated optical fibers arranged in a plane shape in parallel and a tensile strength body 4 arranged between the ribbons 9 together with a coating layer 3 and grooves 8 for tearing are formed in the coating layer 3 between the ribbons 9 and tensile strength body 4; and the tensile strength body 4 is brought into contact with the coating layer 3, and the ribbons 9 of coated optical fibers are coated with the coating layer 3 across tensile strength fibers 2, which are coated with the coating layer 3 slidably along the length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of an optical fiber cable used for optical communication and the like.

[0002]

2. Description of the Related Art A conventional optical fiber cable has, for example, the following structure. FIG. 4 is a sectional view of a two-core parallel optical fiber cable. This fiber optic cable is
Two optical fiber cords 6 provided with a tensile fiber 2 (for example, Kevlar) around the optical fiber core 1 and provided with a coating layer 3 on the outside thereof are arranged in parallel, and the coating layer of the two optical fiber cords 6 3 is integrated. FIG. 5 is a sectional view of another example of the conventional optical fiber cable. This fiber optic cable has a central tensile member 4 (eg, steel wire).
Optical fiber cords 6 are arranged on both sides in parallel, and these are collectively covered with a coating layer 7 of polyethylene, vinyl chloride or the like. This optical fiber cable is manufactured by vertically attaching an optical fiber cord 6 and a tensile strength member 4 and collectively forming a coating layer 7 by pressure extrusion.

[0003]

However, the above-mentioned optical fiber cable has the following problems. 1) When the temperature of the optical fiber cable having the structure shown in FIG. Line 1
Causes slight bending, and transmission loss increases. For example,
The optical fiber 1 is a GI optical fiber (50 / 125GI) having a core diameter of 50 μm and a cladding outer diameter of 125 μm.
Nylon core wire), at room temperature, wavelength 1.3μ
m, the transmission loss averaged 0.5 dB / km is-
At 20 ° C., it increases to 1.0 dB / km.

2) In the optical fiber cable having the structure shown in FIG. 5, since the strength member 4 and the optical fiber cord 6 are collectively covered by the coating layer 7, even if the temperature is lowered, the coating layers 3 and
The contraction of 7 is suppressed by the tensile strength member 4, thereby preventing an increase in transmission loss due to a temperature drop. However, since the coating layers 3 and 7 are in an adhered state, it is difficult to remove the coating layer 7 and separate the optical fiber cord 6 during terminal processing.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 comprises a plurality of optical fibers arranged in parallel in a plane and the optical fiber. An optical fiber cable in which a tensile strength member disposed between fiber cores is collectively coated with a coating layer, wherein a groove for tearing is provided in a portion of the coating layer between the optical fiber core and the tensile strength member. An optical fiber cable characterized by being provided. Here, the optical fiber core includes the optical fiber tape.

According to a second aspect of the present invention, in the optical fiber cable according to the first aspect, the plurality of optical fiber cores are covered with a coating layer via a tensile fiber, and the tensile strength member is in close contact with the coating layer. The tensile strength fiber is covered with a coating layer so as to be slidable in the longitudinal direction.

According to the first aspect of the present invention, since the tensile strength members are arranged between the optical fibers and coated collectively, even if the temperature decreases, the shrinkage of the coating layer is suppressed by the tensile strength members. An increase in transmission loss due to a decrease in temperature can be prevented. Further, since a tearing groove is provided in a portion of the collective coating layer between the optical fiber core and the tensile member, the optical fiber core can be easily separated for terminal treatment.

According to the second aspect of the present invention, since the tensile strength fiber is covered with the covering layer so as to be slidable in the longitudinal direction, the optical fiber core wire can be easily connected to connect the connector to the terminal. The extra length of the drawn optical fiber can be stored in the coating layer after connecting the connector, and the extra length can be reduced to prevent bending and increase in loss. Such coating of the optical fiber cable is desirably performed by pipe extrusion. Because, when the optical fiber cable is coated by pressure extrusion, the tensile strength fiber and the coating layer adhere to each other, making it difficult to separate and pull out the tensile strength fiber and the optical fiber core when connecting the connector. Because it becomes. Furthermore, after the connector is connected, the extra length of the drawn optical fiber core remains as it is, and this portion may bend to increase the loss or break the wire.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the optical fiber cable according to the present invention. FIG.
Are the same as those described with reference to FIG. In this embodiment, an optical fiber core 1 having a tensile fiber 2 made of Kevlar (trade name) or the like is provided around
A tensile strength member 4 made of a galvanized steel wire or the like is arranged in parallel on both sides, and a coating layer 3 made of a polyethylene resin, a vinyl chloride resin, or the like is collectively applied thereto. Also, when the coating layer 3 is formed by extruding all at once, the portion of the coating layer 3 between the fiber core 1 and the tensile strength member 4,
Grooves 8 for tearing are provided at two places. In the present embodiment, when the optical fiber core 1 is made of a 50 / 125GI nylon core, the width is about 7.0 mm. Further, when the temperature decreases from room temperature to −20 ° C., at a wavelength of 1.3 μm, the increase in the transmission loss is 0.1 dB / km or less, and the increase in the transmission loss is smaller than in the related art. This is because, since the coating layer 3 is in close contact with the tensile strength member 4, the shrinkage of the coating layer 3 is suppressed even when the temperature is lowered, and it is possible to prevent the optical fiber core wire 1 from being slightly bent. It is. Furthermore, since the optical fiber cable of the present embodiment has a groove 8 for tearing on the surface, the optical fiber cord 6 (the optical fiber core wire 1 and the tensile strength fiber 2 are coated with the coating layer 3 for terminal treatment). ) The operation of separating the portion from the strength member 4 becomes easy.

FIG. 2 is a sectional view of another embodiment. In this embodiment, a four-core optical fiber ribbon 9 is used instead of the optical fiber core 1 of the above embodiment. Thus, the coating layer 3 is in close contact with the tensile strength member 4, but is not in close contact with the tensile strength fiber 2, and the tensile strength fiber 2 is slidable in the longitudinal direction. As described above, in this embodiment, since the tensile strength fiber 2 is slidable in the longitudinal direction, the optical fiber ribbon 9 can be easily pulled out from the terminal, and the connector can be connected thereto. After the connector is connected, the pulled-out optical fiber ribbon 9 can be returned to its original state, so that the pulled-out extra length does not remain exposed.
The extra length is not bent or broken, and thus the connector can be connected without increasing loss. The optical fiber cable of the present embodiment has an optical fiber tape core wire 9.
Can be produced by extrusion using a jig (nipple and die) that uses a pipe method for the portion of the tensile strength member 4 and a pressurizing method for the portion of the tensile strength member 4. In the present embodiment, the number of the optical fiber ribbons 9 is not limited to two, and may be, for example, three as shown in FIG. As shown, the strength members 4 may be inserted alternately with respect to the optical fiber ribbon 9.

[0011]

As described above, according to the first aspect of the present invention, it is possible to prevent an increase in transmission loss due to a decrease in temperature and to easily separate the optical fiber core for terminal processing. There is an excellent effect that can be. According to the second aspect of the present invention, there is an excellent effect that an increase in transmission loss can be prevented when a connector is connected to a terminal.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of another embodiment.

FIGS. 3A and 3B are cross-sectional views of still another embodiment.

FIG. 4 is a sectional view of an example of a conventional optical fiber cable.

FIG. 5 is a cross-sectional view of another example of the conventional optical fiber cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber core wire 2 Tensile fiber 3, 7 Coating layer 4 Tensile body 6 Optical fiber cord 8 Groove 9 Optical fiber tape core

Claims (2)

[Claims] An optical fiber cable comprising a plurality of optical fiber cores arranged in parallel in a plane and a strength member disposed between the optical fiber cores collectively covered with a coating layer, An optical fiber cable, wherein a groove for tearing is provided in a portion of the coating layer between the optical fiber core wire and the strength member. 2. The plurality of optical fiber core wires are covered with the covering layer via a tensile fiber, the tensile strength member is in close contact with the covering layer, and the tensile fiber is a covering layer slidable in a longitudinal direction. The optical fiber cable according to claim 1, wherein the optical fiber cable is coated.