JP3398034B2 - Fiber optic cable - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable using a tape-shaped optical fiber core wire.

[0002]

2. Description of the Related Art A tape-shaped optical fiber core is formed by arranging a plurality of optical fiber element wires in a plane in the same direction, and coating the outer circumference of the optical fiber wires in a batch to form a tape. When such a tape-shaped optical fiber core wire is used as a core wire of a cable, it is rare to use only one sheet, and it is often used in a state in which a plurality of layers are stacked. For example, as shown in FIG.
It is a form like a cable core 3 in which a plurality of tape-shaped optical fiber core wires 1 are laminated and the outer periphery thereof is collectively covered 2. The material of the collective coating 2 is an ultraviolet curable resin or the like. Then, as shown in FIG. 5, when the optical fiber cable 5 having the protective sheath 4 formed on the outer periphery of the cable core 3 formed by laminating a plurality of tape-shaped optical fiber core wires 1 and applying the collective coating 2 is bent, For the reason that the strain applied to the optical fiber is reduced, it has been considered preferable to bend the stacking direction so as to be perpendicular to the plane including the bending direction of the cable.

[0003]

However, such a cable core has the tape-shaped optical fiber core wire 1 shown in FIG.
When the stacking thickness T is smaller than the width W of the above, when the structure is stacked in the direction perpendicular to the plane including the regulated brow direction, there is a problem that the strain becomes larger than that in the structure stacked in the bending direction.

An object of the present invention is to provide an optical fiber cable which solves the above problems.

[0005]

SUMMARY OF THE INVENTION To achieve this object the present invention, a tape-shaped optical fiber laminating a plurality, have a cable core comprising subjecting a collective coating on its outer periphery, pre
In an optical fiber cable whose bending direction is restricted, the tape-shaped optical fiber is wider than the width of the tape-shaped optical fiber core wire.
The laminated thickness of the fiber core wire is smaller, and a plurality of tape-shaped optical fiber core wires are laminated in a direction in which the bending direction of the cable is restricted. Is. INDUSTRIAL APPLICABILITY The present invention is particularly effective when applied to a cable whose bending direction is previously regulated by the presence of a tension member, such as a self-supporting optical fiber cable.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. The optical fiber cable 5, the tape-shaped optical fiber 1 by laminating two (tape-like optical fiber
The laminated thickness T is smaller than the width W) and the outer periphery thereof is collectively covered 2 to form the cable core 3 (see FIG. 4 for details), and the outer periphery of the cable core 3 is covered with the protective sheath 4. Is. The bending direction when winding the cable 5 around the drum is the direction having the smallest bending rigidity, that is, the direction of the arrow, due to the difference in the bending rigidity of the cables themselves. That is, the cable 5 is formed by stacking two tape-shaped optical fiber core wires 1 in the pre- regulated bending direction of the cable 5 , that is, in the direction of the arrow in FIG. With such a configuration, an increase in transmission loss can be reduced when the cable 5 is bent.

By the way, a cable core is formed by collectively coating a laminate of three 4-core tape-shaped optical fiber core wires (the laminated thickness T is smaller than the width W of the tape-shaped optical fiber core wire), When a cable coated with a protective sheath is wound on a drum, it is necessary to bend the tape-shaped optical fiber core wire so that the stacking direction is perpendicular to the plane that includes the radial direction of bending. When wound on a drum, the average transmission loss of the optical fiber is 0.30 dB / km.
(At λ = 1.55 μm), the average transmission loss value of the optical fiber when the tape is wound in a drum so that the laminating direction of the optical fiber core is the bending direction of the cable as in the present invention. 0.19 dB / km (at λ = 1.5
5 μm).

Next, a second embodiment of the present invention will be described with reference to FIG. The optical fiber cable 5 is in the form of a self-supporting cable in which a cable core 3 and a tension member 6 along the cable core 3 are provided with a common protective sheath 4 having a substantially 8-shaped cross section. The internal structure of the cable core 3 is shown in FIG.
Is the same as the cable. In the case of a self-supporting cable, due to its structure, due to the difference in the direction of bending rigidity of the cable itself, the direction with the largest bending rigidity, that is, the direction that traverses the tension member and the cable core in this order ,
That is, each of the tension member and the cable core
The cable cannot be bent in the direction that crosses the center ,
As shown in the figure, the cable core 3 and the tension member 6 can be bent only in the directions in which they have the same curvature ( preliminary
Because the bending direction is restricted in this direction).

Therefore, the cable 5 is formed by laminating a plurality of tape-shaped optical fiber core wires 1 in a direction perpendicular to a direction traversing the tension member 6 and the cable core 4 in this order. By doing so, when the cable 5 is bent by winding a drum or the like, the width surface of the tape-shaped optical fiber core wire 1 is oriented in the direction perpendicular to the surface including the bending direction of the cable, so that the strain applied to the optical fiber is increased. Can be kept small, and as a result, an increase in transmission loss can be kept low.

Next, a third embodiment of the present invention will be described with reference to FIG. This optical fiber cable 5 is also in the form of a self-supporting cable, but the cable core 4 is made to meander with respect to the tension member 6. Other than that, the cable is the same as that of FIG. 2, and therefore, the same portions are denoted by the same reference numerals and the description thereof is omitted.

[0011]

As described above, according to the present invention, in an optical fiber cable having a plurality of tape-shaped optical fiber cores laminated together and collectively coated on the outer periphery thereof as a cable core, the cable is bent. There is an effect that it is possible to reduce an increase in transmission loss when it is generated.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing the same as the second embodiment.

FIG. 3 is a perspective view showing a third embodiment of the present invention.

FIG. 4 is a sectional view of a cable core.

FIG. 5 is a perspective view showing a problem when a laminated body of tape-shaped optical fibers is bent.

[Explanation of symbols]

1 Tape-shaped optical fiber 2 batch coating 3 cable core 4 protective sheath 5 optical fiber cable 6 tension members

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuhiro Uekura 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Hideyuki Iwata 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation (56) Reference JP-A-9-318855 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 6/44

Claims (2)

(57) [Claims] 1. A plurality of tape-shaped optical fiber cores are laminated,
It has a cable core that is collectively coated on its outer circumference,
In an optical fiber cable in which the bending direction is regulated in advance , the tape-shaped optical fiber is more than the width of the tape-shaped optical fiber core wire.
The laminated thickness of the fiber core wire is smaller, and a plurality of tape-shaped optical fiber core wires are used in the bending direction of the cable.
Is laminated in a regulated direction, an optical fiber cable. 2. A plurality of tape-shaped optical fiber core wires are laminated,
In a self-supporting optical fiber cable in which a cable core formed by covering the outer periphery at once and a tension member along the cable core are covered with a common protective sheath, a width of the tape-shaped optical fiber core wire tape
Wherein the laminated optical fiber core wire has a smaller laminated thickness, and the plurality of tape-shaped optical fiber core wires are laminated in a direction perpendicular to a direction traversing each center of the tension member and the cable core. Self-supporting optical fiber cable.