WO2018021299A1 - Optical fiber cable - Google Patents

Abstract

This optical fiber cable includes: a striated body; two cable supporting members disposed at both sides of the striated body and in line with the striated body; and an outer cable jacket that entirely covers the striated body and the two cable supporting members. A first cable supporting member has a bending rigidity that is set to a value smaller than the bending rigidity of a cable supporting member made of an aramid fiber, and set to a value larger than the bending rigidity of only the outer cable jacket.

Description

Fiber optic cable

The present invention relates to an optical fiber cable.
This application claims priority based on Japanese Patent Application No. 2016-146076 filed on July 26, 2016, and incorporates all the description content described in the above Japanese application.

In recent years, with the expansion of broadband services such as video distribution, IP telephony, and data communication, the number of subscribers to home-use data communication services (FTTH: Fiber To The Home) using optical fibers is increasing. In this FTTH, a drop optical cable is used to drop from an aerial or underground trunk optical cable to a subscriber's house. These optical cables have a structure in which an optical fiber core wire and a pair of cable support members (also referred to as strength members) that are arranged with the optical fiber core wire in between are integrally molded with a cable jacket. ing.

• If these optical cables are bent with a small radius of curvature, the tensile body may break. For this reason, for example, Patent Documents 1 and 2 disclose a technique of an optical fiber cable in which a tensile body is hardly broken.

Japanese Unexamined Patent Publication No. 2005-107256 Japanese Unexamined Patent Publication No. 2005-49658

An optical fiber cable according to an aspect of the present disclosure includes a linear body, two cable support members arranged in line with the linear body on both sides of the linear body, the linear body, and the 2 A cable jacket that collectively covers the cable support members, and the bending rigidity of the first cable support member is set to a value smaller than the bending rigidity when the cable support member is formed of an aramid fiber. And, it is set to a value larger than the bending rigidity only by the cable jacket.

It is a figure which shows the structural example of the optical fiber cable by Example 1 of this invention. It is a figure which shows the structural example of the optical fiber cable by Example 2 of this invention. It is a figure for demonstrating a bending test.

[Problems to be solved by the present disclosure]
When two strength members are arranged like the optical fiber cables of Patent Documents 1 and 2, the optical fiber cable is difficult to bend in the direction in which the strength members are arranged (also referred to as the longitudinal direction of the cable). For this reason, when the bending direction of the pipe line in which the optical fiber cable is laid is the longitudinal direction of the cable, the optical fiber cable is lifted or twisted.
On the other hand, it is desirable for the tensile body to easily tear the cable jacket along the longitudinal direction of the cable when the optical fiber core is taken out from the optical fiber cable.

This disclosure is intended to provide an optical fiber cable that can be easily bent even in a direction in which strength members are arranged, and that can easily tear the cable jacket along the longitudinal direction of the cable.

[Effects of the present disclosure]
According to the present disclosure, the optical fiber cable can be easily bent in the direction in which the cable support members are arranged, and the cable jacket can be easily torn along the cable longitudinal direction.

[Description of Embodiment of the Present Invention]
First, the contents of the embodiment of the present invention will be listed and described.
An optical fiber cable according to one aspect of the present invention is provided.
(1) the striatum;
Two cable support members arranged in a straight line with the linear body on both sides of the linear body;
A cable jacket covering the wire body and the two cable support members at once;
With
The bending rigidity by the first cable support member is set to a value smaller than the bending rigidity when the cable support member is formed of an aramid fiber, and is set to a value larger than the bending rigidity only by the cable jacket. Is done.
Since the bending rigidity by the first cable support member is set to a value smaller than the bending rigidity in the case of an aramid fiber that is normally used as a cable support member, the optical fiber cable has a cable support compared to a normal optical fiber cable. It becomes easy to bend in the direction in which the members are arranged. Further, since the bending rigidity by the first cable support member is set to a value larger than the bending rigidity by the cable jacket, when the linear body is taken out from the optical fiber cable, the cable jacket is moved along the cable longitudinal direction. And can be easily torn.

(2) The first cable support member is made of glass fiber.
Since the first cable support member is made of glass fiber, it is easier to bend than the aramid fiber normally used as the cable support member, and the optical fiber cable is easily bent in the direction in which the cable support members are arranged.
(3) The bending rigidity by the first cable support member is set to a value smaller than the bending rigidity by the second cable support member.
When the optical fiber cable is bent in the longitudinal direction, the second cable support member whose bending rigidity is set to a large value becomes the center of bending, and therefore the cable jacket side on which the first cable support member is arranged is enlarged. Can be bent.
(4) The first cable support member is formed of glass fiber, and the second cable support member is formed of aramid fiber.
The cable jacket side on which the glass fiber is disposed has a lower bending rigidity than the cable jacket side on which the aramid fiber is disposed. Therefore, the first cable support is performed with the second cable support member having a large bending rigidity as the center of bending. The cable jacket side on which the members are arranged can be bent greatly.

(5) The bending rigidity by the first cable support member is set to the same value as the bending rigidity by the second cable support member.
The optical fiber cable is bent around the wire body, and both cable jackets on which the first and second cable support members are arranged can be bent.
(6) The first cable support member and the second cable support member are formed of glass fiber.
Both cable jackets on which the glass fibers are arranged can be bent larger than when the aramid fibers are arranged on both sides.

[Details of the embodiment of the present invention]
Hereinafter, a specific example of an optical fiber cable according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of an optical fiber cable according to a first embodiment of the present invention. The optical fiber cable 1 has, for example, a cable main body 2 having a square cross section. The cable body 2 has, for example, a single-core optical fiber 4 at the center, and two pairs of strength members 5 and 6 on both sides thereof.

The optical fiber core 4 is obtained by further coating a colored coating on the outside of what is called an optical fiber obtained by coating a glass fiber having a standard outer diameter of 125 μm with a coating outer diameter of about 250 μm. The number of cores of the optical fiber core wire can be selected from any number of cores such as 2 or 8 cores. Moreover, it may replace with the optical fiber core wire 4, and may be the optical fiber tape core wire which integrated the optical fiber core wire in which several arranged in tape shape with the common coating | cover. In addition, the optical fiber core wire 4 and the optical fiber tape core wire correspond to the linear body of this invention.

The strength members 5 and 6 are respectively arranged on both sides of the optical fiber core 4 in parallel with the optical fiber core 4 along the longitudinal direction thereof. Is not meant to be parallel, but it is meant to have a width within the range where the effects of the present invention are exhibited as long as it is considered as parallel.
Specifically, a first strength member 5 is disposed below the optical fiber core 4 as viewed in FIG. The first strength member 5 is formed of, for example, a glass fiber having a circular cross section, that is, a single glass fiber similar to the optical fiber core wire 4 and has, for example, an outer diameter of about 250 μm. The first strength member 5 corresponds to the first cable support member of the present invention.

Further, a second strength member 6 is disposed above the optical fiber core wire 4 as viewed in FIG. The second strength member 6 is formed of, for example, an aramid fiber reinforced plastic (K-FRP, hereinafter referred to as an aramid fiber) having a circular cross section, and has an outer diameter of about 0.4 mm, for example. The second strength member 6 corresponds to the second cable support member of the present invention. In place of the aramid fiber, a steel wire or glass fiber reinforced plastic (FRP) may be used.

A cable jacket (also referred to as a sheath) 7 constitutes a coating for the cable body 2 and is formed by extruding a hard resin (for example, a flame-retardant polyolefin resin) on the outside of the optical fiber core wire 4 and the tensile strength members 5 and 6. Formed.
When the optical fiber core wire 4 is one core, the cable main body 2 can be formed with one side of about 2 mm. When the direction connecting the centers of the strength members 5 and 6 is the longitudinal direction of the cable and the direction perpendicular to the longitudinal direction is the lateral direction of the cable, the longitudinal width is about 3.0 mm and the lateral width. The width in the vertical direction may be longer than the width in the horizontal direction.

Further, the center-to-center distance between the second strength member 6 and the optical fiber core wire 4 may be shorter than the center-to-center distance between the first strength member 5 and the optical fiber core wire 4.
Note that, for example, a central portion of the surface of the cable body 2 is provided with a notch 8 for tearing the jacket in a direction orthogonal to the direction (vertical direction) connecting the centers of the two strength members 5 and 6. Yes.

Here, the bending rigidity of the first strength member 5 described above can be expressed as E ₁ I ₁ when the Young's modulus of the glass fiber is E ₁ and the secondary moment of inertia is I ₁ . Flexural rigidity is an index indicating the difficulty of bending deformation of a beam member. It is the product of the moment of inertia (determined by the sectional shape and size of the member) and the Young's modulus of the material. expressed. That is, the bending rigidity of the first strength member 5 made of glass fiber having a circular cross section is expressed by the product E ₁ I ₁ of the Young's modulus E ₁ and the second moment of inertia I ₁ of the glass fiber.

Further, the bending rigidity of the second tensile body 6 made of the aramid fiber having a circular cross section is represented by the product E ₂ I ₂ of the Young's modulus E ₂ and the cross sectional second moment I ₂ of the aramid fiber.
Furthermore, the cross-sectional shape of the cable jacket 7 is formed with holes for receiving the optical fiber core wire 4 and the strength members 5 and 6 in addition to the notches 8, and the bending rigidity of the cable jacket 7 is made of flame-retardant polyolefin resin. It is represented by the product E ₀ I ₀ of Young's modulus E ₀ and cross-sectional secondary moment I ₀ .

In this embodiment, the bending stiffness E ₁ I _{1 of} the first strength member 5 is the bending stiffness of the support member formed of aramid fibers (in this embodiment, the bending stiffness E of the second strength member 6). ₂ I ₂ ) is set to a smaller value. For this reason, it becomes easy to bend the optical fiber cable 1 in the direction (longitudinal direction of the cable) in which the strength members 5 and 6 are arranged.
More specifically, the optical fiber cable 1 is bent around the second strength member 6 whose bending rigidity is set to a large value, and the cable jacket side on which the first strength member 5 is arranged is connected to the second strength member. 6 can be bent larger than the side of the cable jacket where the 6 is disposed.

Further, the bending rigidity E ₁ I ₁ of the first strength member 5 is set to a value larger than the bending rigidity E ₀ I ₀ of the cable jacket 7. Thereby, when taking out the optical fiber core wire 4 etc. from the optical fiber cable 1, the cable jacket 7 becomes easy to tear, and the cable jacket 7 can be easily torn along the cable longitudinal direction.

FIG. 2 is a diagram illustrating a configuration example of an optical fiber cable according to a second embodiment of the present invention.
In the first embodiment, the first strength member 5 is formed of glass fiber and the second strength member 6 is formed of aramid fiber. However, the second strength member 6 is also composed of the first strength member 5 and the second strength member 5. Similarly, for example, it may be formed of one glass fiber.
Thus, even if the bending stiffness E ₁ I ₁ of the _first strength member 5 and the bending stiffness E ₂ I _{2 of} the second strength member 6 are set to the same value, the aramid fiber strength members are arranged on both sides. It can be bent greatly compared to ordinary optical fiber cables.

FIG. 3 is a diagram for explaining a bending test.
In the bending test, an optical fiber cable 1 having a length of 5 cm is prepared, one end of which is a fixed end, and the other end is a free end. Then, as shown in FIG. 3, a load W (applied vertically below) necessary for the deflection amount y of the free end to be 2 (cm) is measured.

When the optical fiber cable 1 described in the first embodiment, that is, the first strength member 5 is glass fiber, the bending rigidity E ₁ I ₁ is 7300 (kgf / mm ² ) × 0.0278 (mm ⁴ ) = 202.94 (kgf · mm ² ). When the second tensile body 6 is an aramid fiber, the bending rigidity E ₂ I ₂ is 6300 (kgf / mm ² ) × 0.072 (mm ⁴ ) = 453.6 (kgf · mm ² ).
Further, the bending rigidity E ₀ I ₀ of the cable jacket 7 is 40 (kgf / mm ² ) × 4.353 (mm ⁴ ) = 174.1 (kgf · mm ² ).

As a comparative example, a bending test was conducted in the case of a normal optical fiber cable in which an aramid fiber strength member was arranged on both sides. As a result of the bending test of this comparative example, the load W necessary for the free end deflection amount y to be 2 (cm) was W = 1.6 (N). On the other hand, as in Example 1, the result of the bending test when one of the first strength members 5 is made of glass fiber is a load W = 0.3 (N), which is a smaller load than the comparative example. Was enough.

Next, a bending test was conducted when the optical fiber cable 1 described in Example 2, that is, the first and second strength members 5 and 6 were both glass fibers. The result of the bending test in this case was also a load W = 0.3 (N), and a smaller load was sufficient as compared with the comparative example.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber cable, 2 ... Cable main-body part, 4 ... Optical fiber core wire, 5 ... 1st strength body, 6 ... 2nd strength body, 7 ... Cable jacket, 8 ... Notch.

Claims (6)

1. The striatum,
   Two cable support members arranged in a straight line with the linear body on both sides of the linear body;
   A cable jacket covering the wire body and the two cable support members at once;
   With
   The bending rigidity by the first cable support member is set to a value smaller than the bending rigidity when the cable support member is formed of an aramid fiber, and is set to a value larger than the bending rigidity only by the cable jacket. Fiber optic cable.
2. The optical fiber cable according to claim 1, wherein the first cable support member is formed of glass fiber.
3. The optical fiber cable according to claim 1 or 2, wherein the bending rigidity by the first cable support member is set to a value smaller than the bending rigidity by the second cable support member.
4. The optical fiber cable according to claim 3, wherein the first cable support member is formed of glass fiber, and the second cable support member is formed of aramid fiber.
5. The optical fiber cable according to claim 1 or 2, wherein the bending rigidity of the first cable support member is set to the same value as the bending rigidity of the second cable support member.
6. The optical fiber cable according to claim 5, wherein the first cable support member and the second cable support member are made of glass fiber.

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