JP2003107307A - Tension member for optical fiber cable and optical fiber cable using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tension member for an optical fiber cable which is capable of assuring the grounding area with coated optical fibers and intervention and is excellent in handling quality and an optical fiber cable using the same. SOLUTION: The outer periphery of the tension member is provided with a coating layer 17 consisting of a low-density polyethylene of 40 to 60% in expansion rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension member for an optical fiber cable used for home wiring and the like and an optical fiber cable using the same.

[0002]

2. Description of the Related Art Generally, an optical fiber cable to be installed in a conduit tube in a home is formed by twisting tension members together with an optical fiber core wire, interposition, etc. Fiber cables are used.

FIG. 5 shows an end view of an optical fiber cable having a conventional tension member. In the figure, reference numeral 1 is an optical fiber cable, and a tension member 2 is provided at a substantially central position on an end face. The tension member 2 is made of steel wire or FRP,
The plurality of optical fiber core wires 3 and the interposition 4 are in contact with each other and are twisted together. Further, the optical fiber cable 1 is provided with four interwoven fibers 5, which are twisted together with the tension member 2 and the optical fiber core wire 3 or the interposition 4 arranged around the tension member 2.
That is, the optical fiber cable 1 has the tension member 2, the optical fiber core wire 3, the interposition 4 and the intermediary yarn 5 are provided around the tension member 2, and these are collectively held by the winding tape 6.
It is formed into a substantially round shape by being pressed and wound with, and has a structure in which the outer side thereof is covered with a sheath 7.

[0004]

As described above, the optical fiber cable 1 constructed by pulling in the tension member 2 is mainly used for short-distance wiring, and is laid on a conduit tube or the like in a house. However, there were the following problems.

Since both the tension member 2 and the optical fiber core wire 3 in the optical fiber cable 1 are formed in a substantially round shape, the ground area of the contact point between the tension member 2 and the optical fiber core wire 3 is small. It was small. Therefore, when the short-distance optical fiber cable 1 is laid on a conduit tube or the like in a house, when the tension member 2 is pulled to pull the optical fiber cable 1 into the conduit tube, slippage occurs and tension occurs. Only the member 2 has been pulled into the conduit, and the entire optical fiber cable 1 cannot be pulled into the conduit.

Further, since the optical fiber cable 1 has a structure in which the tension member 2 formed of a steel wire or the like is provided in the substantially central portion thereof, when the optical fiber cable 1 is subjected to external pressure, this pressure is generated. It is transmitted to the optical fiber core wire 3 through both ends of the sheath 7 and the tension member 2 and becomes a load, and the transmission loss of the optical fiber cable 1 is increased.

An object of the present invention is to provide a tension member for an optical fiber cable which can secure a large grounding area with the optical fiber core wire and an interposition and is excellent in handleability, and an optical fiber cable using the same. .

[0008]

In order to achieve the above object, the tension member for an optical fiber cable according to claim 1 has a foaming ratio of 40 to 6 on the outer circumference of the tension member.
It is characterized in that a coating layer made of 0% low-density polyethylene was provided. As described above, according to the first aspect of the invention, the ground area between the tension member for the optical fiber cable and the optical fiber core wire can be increased.

In order to achieve the above object, the optical fiber cable according to a second aspect of the invention has a foaming rate of 40 to 60% on the outer circumference.
The tension member provided with a coating layer made of low-density polyethylene and the optical fiber core wire are arranged so as to be in close contact with each other, and they are collectively press-wound with a press-wrap tape, and the press-wrap tape is covered with a sheath. It is characterized by that. As described above, according to the second aspect of the invention, it is possible to provide an optical fiber cable having excellent retractability.

In order to achieve the above object, the tension member for an optical fiber cable according to a third aspect of the present invention is characterized in that a coating layer made of polyurethane foam having a foaming rate of 30 to 40% is provided on the outer periphery of the tension member. I am trying.
As described above, according to the third aspect of the invention, the ground area between the tension member for the optical fiber cable and the optical fiber core wire can be increased.

In order to achieve the above object, the optical fiber cable according to a fourth aspect of the invention has a foaming rate of 30 to 40% on the outer circumference.
The tension member provided with a coating layer made of polyurethane foam and the optical fiber core wire are arranged so as to be in close contact with each other, and are clamped and wound together with a presser-winding tape, and the presser-winding tape is covered with a sheath. Is characterized by. Thus, according to the invention of claim 4, it is possible to provide an optical fiber cable having excellent retractability.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a tension member for an optical fiber cable according to the present invention will be described below. FIG. 1 is an end view showing an embodiment of an optical fiber cable using a tension member for an optical fiber cable according to the present invention. In FIG. 1, 10 is an optical fiber cable according to the present invention, in which a tension member 11 is provided at a substantially central portion of an end face, and an optical fiber core wire 12 and an intervening 13 are provided around the tension member 11. It is provided by being twisted so as to come into contact with the tension member 11. In the present embodiment, two optical fiber cores 12 and two intervening fibers 13 are provided. Further, 14 is a yarn, which is arranged between the optical fiber core 12 and the interposition 13. Then, the optical fiber core wire 12, the interposer 13 and the interwoven yarn 14 are collectively pressed and wound with a press winding tape 15 so as to have a substantially round shape, and the outer side thereof is covered with a sheath 16 to cover the optical fiber cable. 10 are formed.

In this embodiment, the tension member 11 of the optical fiber cable 10 is made of steel wire or FRP, and has a coating layer 17 as an outer layer. The coating layer 17 has a coating thickness of 20 to 40% of the outer diameter of the tension member 11, and is made of a foamed elastic material.

The coating layer 17 is made of low density polyethylene in the present embodiment. The low density polyethylene is similar to that used in the coating of ordinary electric wires, and its hardness is usually 45 to 50.
(Share D). The coating layer 17 in the present embodiment is made of this low density polyethylene with a foaming ratio of 40 to 60%
It is foamed and is reduced in hardness to about 75 to 80 (share A). Thus, when the hardness is reduced by foaming, when the tension member 11 and the optical fiber core wire 12 or the interposition 13 are twisted together as shown in FIG.
The coating layer 17 of the tension member 11 is pressed and elastically deformed along the shape of the optical fiber core wire 12 or the interposition 13. That is, since the covering layer 17 is elastically deformed, the ground contact area between the tension member 11 and the optical fiber core wire 12 or the interposition 13 is increased.
The frictional force between the tension member 11 and the optical fiber core wire 12 or the interposition 13 becomes large, and the optical fiber cable 1
Even if the tension member 11 is pulled in the work of pulling 0 into the electric wire tube in the house, the tension member 11 and the optical fiber core wire 12 are less likely to be displaced.

The low-density polyethylene has a foaming ratio of 40 to
60% means that the low-density polyethylene has a foaming ratio of 40.
If it is less than%, the low-density polyethylene has a high elastic modulus and does not elastically deform, so that it is difficult to secure a sufficient grounding area between the tension member 11 and the optical fiber core wire 12 or the interposition 13. When the foaming rate of the density polyethylene exceeds 60%, the elastic modulus of the low density polyethylene becomes too small and it breaks, and the steel wire or FRP of the tension member 11 and the optical fiber core wire 12 come into direct contact with each other. This is because the purpose cannot be met.

Further, the coating layer 17 in the present embodiment
It is also possible to form foamed polyurethane instead of low density polyethylene. This polyurethane foam is
It is preferable that the foaming rate is 30 to 40% and the hardness is 70 to 75 (share A). The coating layer 17 in the tension member 11 formed of polyurethane foam within the above range is
By coming into contact with the optical fiber core wire 12 or the interposition 13, the elastic member is elastically deformed along the shape of the optical fiber core wire 12 or the interposition 13, and the tension member 11 and the optical fiber core wire 12 or the interposition 13 have an appropriate ground area. You will be able to get it.

The foaming ratio of the foamed polyurethane is set within the above range, because when the foaming ratio of the foamed polyurethane is less than 30%, the elastic modulus of the coating layer is high and the elastic deformation does not occur.
Since the ground contact area between the tension member 11 and the optical fiber core wire 12 or the interposition 13 cannot be secured, a good frictional force cannot be obtained, and when the foaming rate of the polyurethane foam exceeds 40%, the elastic modulus of the polyurethane foam is increased. Becomes smaller and breaks, and the steel wire of the tension member 11 or FR
This is because the disadvantage that P and the optical fiber core wire 12 directly contact each other occurs. That is, by foaming polyurethane foam with a foaming ratio within the above range and forming the coating layer 17 of the tension member 11, the coating layer 17 is elastically deformed, and the tension member 11 and the optical fiber core wire 12 or the interposition 13 are formed. Can have a suitable ground contact area.

When the tension member 11 having the coating layer configured as described above is arranged in the optical fiber cable 10, the tension member 11 is located outside the space between the four optical fiber core wires 12 or the interpositions 13 twisted together. A tension member 11 having a large diameter is selected, and four optical fiber core wires 12 or interpositions 13 are twisted around the tension member 11. At this time, by twisting the optical fiber core wire 12 or the interposition 13 with a tension of 200 to 300 g, the coating layer 17 of the tension member 11 is made to be the optical fiber core wire 12
Alternatively, the tension member 11 and the optical fiber core wire 12 or the intervening member 13 are crushed by the intervening member 13 and closely contact each other without any gap. Therefore, when pulling in the tension member 11 during work,
The optical fiber core wire 12 that comes into close contact with the tension member 11 can be pulled together with the tension member 11 into the conduit without being displaced.

Further, by providing the coating member 17 on the tension member 11 as described above, even when lateral pressure or the like is applied to the optical fiber cable 10 from the outside, the elasticity of the coating layer 17 causes the optical fiber core wire 12 to be applied. Lateral pressure can be absorbed and an increase in transmission loss can be prevented. Further, since the lateral pressure can be absorbed by the coating layer 17, the sheath 16 of the optical fiber cable 10 can be made thinner than before, and the outer diameter of the optical fiber cable can be reduced.

FIG. 2 is an end view showing another embodiment of an optical fiber cable using a tension member for an optical fiber cable according to the present invention. In the figure, the optical fiber cable 18 has a tension member 19 at a substantially central position on the end face.
Two optical fiber cores 20 and two intervening 21 are provided so as to contact with each other, and four intermediary yarns 22 are provided so as to contact the optical fiber cores 20 and intervening 21. . Reference numeral 23 is a holding tape, and the holding tape 23 is covered with a sheath 24.

As an application example of the present embodiment, the tension member 19 has a steel wire or FRP and a coating layer 25 made of a low foam elastic material on the outer layer thereof, and further made of a high foam elastic material on the outer side thereof. The outermost layer 26 is formed. Coating layer 2 made of low foam elastic material
As 5, a low density polyethylene having a low foaming rate (for example, 40%) is used. When a low foaming elastic material is used for the coating layer 25 for coating the steel wire or FRP, the adhesion between the coating layer 25 and the steel wire or FRP is improved. The outermost layer 26 made of a highly foamed elastic material may be low density polyethylene having a high foaming rate (for example, 60%). If such a highly foamed elastic material is used for the outermost layer 26, the adhesion between the optical fiber core wire 20 and the outermost layer 26 can be improved.

The low-foaming elastic material and the high-foaming elastic material in the present embodiment are not limited to this, and the low-foaming elastic material is coated with foamed polyurethane having a low foaming rate (for example, 30%). The same effect can be obtained by using a foamed polyurethane having a high foaming rate (for example, 40%) as the highly foamed elastic material in the outermost layer.

FIGS. 3 and 4 show another embodiment of an optical fiber cable using a tension member for an optical fiber cable according to the present invention. In FIG. 3, the optical fiber cable 27 includes a tension member 29 having a coating layer 28 and one optical fiber core wire 30 and 3.
It is formed by the interposition 31 of the book. When the optical fiber cable is used at home, the number of optical fiber core wires required is usually 1 to 4, but in the present embodiment, the required number of optical fiber core wires 30 is 1. Only the case is shown. As shown in the figure, when the number of the optical fiber core wires 30 required for the wiring is only one, three interpositions are provided and the optical fiber core wires 30 are provided.
The outer diameter of the optical fiber cable 27 can be kept constant by twisting the optical fiber cable 27 and the optical fiber cable 27, and the optical fiber cable 27 can be easily installed in a conduit tube in a house.

Further, FIG. 4 shows an end view of an optical fiber cable 32 including a tension member 29 having a coating layer 28 and four optical fiber core wires 30.
The optical fiber cable 32 has a structure in the case where four optical fiber core wires 30 are required for wiring in the house,
Instead of the interposition 31 in FIG. 3, four optical fiber core wires 30 are provided.

That is, as shown in FIGS. 3 and 4, when wiring an optical fiber cable in a house, the number of interpositions is adjusted according to the number of optical fiber core wires required to be provided in the optical fiber cable. Therefore, it is possible to keep the outer diameter of the optical fiber cable constant regardless of whether the number of the optical fiber cores is one or four, and it is possible to easily install the optical fiber cable in the electric conduit in the house. it can.

[0026]

Since the present invention is constructed as described above, it has the following effects.

According to the first aspect of the invention, since the tension member for the optical fiber cable is provided with the elastic coating layer, it is possible to provide the tension member having excellent flexibility and handleability.

According to the second aspect of the present invention, since the ground area between the tension member for the optical fiber cable and the optical fiber core wire can be increased, the tension member and the optical fiber core wire generate a frictional force. It is possible to provide an optical fiber cable that has the above and can be easily pulled into a conduit.

According to the third aspect of the invention, since the tension member for the optical fiber cable is provided with the elastic coating layer, it is possible to provide the tension member excellent in flexibility and handleability.

According to the invention described in claim 4, since the contact area between the tension member for the optical fiber cable and the optical fiber core wire can be increased, the tension member and the optical fiber core wire have a frictional force. It is possible to provide an optical fiber cable that has the above and can be easily pulled into a conduit.

[Brief description of drawings]

FIG. 1 is an end view showing an embodiment of an optical fiber cable using a tension member for an optical fiber cable according to the present invention.

FIG. 2 is an end view showing another embodiment of an optical fiber cable using a tension member for an optical fiber cable according to the present invention.

FIG. 3 is an end view showing another embodiment of an optical fiber cable using a tension member for an optical fiber cable according to the present invention.

FIG. 4 is an end view showing another embodiment of an optical fiber cable using a tension member for an optical fiber cable according to the present invention.

FIG. 5 is an end view of an optical fiber cable using a conventional tension member for an optical fiber cable.

[Explanation of symbols]

10 ………………………… Optical fiber cable 11 ……………………………… Tension member 12 ……………………………… Optical fiber 15 ……………………………… Presser roll tape 16 ……………………………… Sheath 17 ……………………………… Coating layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiko Kato             2771 Ooka, Numazu-shi, Shizuoka Yazaki Electric Cable Co., Ltd.             Within F term (reference) 2H001 DD04 DD11 DD15 DD21 PP01

Claims (4)

[Claims] 1. A foaming ratio of 40 to 40 around the tension member.
A tension member for an optical fiber cable, which is provided with a coating layer made of 60% low-density polyethylene. 2. A tension member having an outer periphery provided with a coating layer made of low density polyethylene having a foaming rate of 40 to 60%,
An optical fiber cable, characterized in that it is arranged so as to be in close contact with an optical fiber core wire, and is press-wound together with a press-winding tape, and the press-winding tape is covered with a sheath. 3. A foaming rate of 30 to 30 around the tension member.
A tension member for an optical fiber cable, which is provided with a coating layer made of 40% polyurethane foam. 4. A tension member having a covering layer made of foamed polyurethane having a foaming rate of 30 to 40% on the outer periphery and an optical fiber core wire are arranged so as to be in close contact with each other, and are wound together with a holding tape. An optical fiber cable characterized in that the pressing tape is covered with a sheath.