JPH09243879A - Optical fiber unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an optical fiber unit to multiple fibers and to the diameter of the unit while maintaining the sectional shape of this unit at a circular shape by disposing coated optical fibers separate from the laminated plural coated optical fibers on the outer side in the transverse direction of these coated optical fibers. SOLUTION: A laminated coated fiber part 25 is constituted by laminating five sheets of the coated optical fiber ribbons 21 in a thickness direction. Each coated optical fiber ribbon 21 is constituting by integrally coating the four optical fibers 22 lined up in parallel with a coating layer 23. Lateral coated fiber parts 26 are disposed adjacently to the laminated coated fiber part 25 on the outer side in the transverse direction of the laminated coated fiber part 25. The size (a) in the thickness direction over the entire part of the laminated coated fiber part 25 is so set as to be made larger than the size (b) in the same direction of the lateral coated fiber parts 26. An integrally coating layer 24 is formed by extrusion coating on the circumferences of the laminated coated fiber part 25 and the lateral coated fiber parts 26 so as to constitute a circular section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber unit in which a plurality of optical fiber core wires are integrated, and in particular, an optical cable is constructed by pneumatically feeding the optical fiber unit into a pipe laid in advance. The present invention relates to an optical fiber unit for pneumatic feeding / pulling in which is suitably used.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing a conventional example of an optical fiber unit that is preferably used as an optical fiber unit for pneumatic feeding and drawing. Reference numeral 2 in the drawing denotes an optical fiber tape core wire, which is formed by arranging four optical fiber element wires 3 in parallel and coating them all together with an ultraviolet curable resin or the like. The optical fiber unit 1 of this example has a structure in which four optical fiber ribbons 2 are laminated and a collective coating layer 4 made of foamed polyethylene is formed around them to have a circular cross section. Has been done.

The optical fiber unit 1 thus constructed is laid by a pneumatic feeding method as shown in FIG.
That is, first, the pipe 10 is laid, and the optical fiber unit 1 is inserted from one end side of the pipe 10 and at the same time, air is blown at a high speed, the optical fiber unit 1 is placed on the air stream, and the optical fiber unit 1 is run to the other end side. is there. In this way, an optical cable is constructed in which the multi-fiber optical fiber unit 1 is housed in the single pipe 10. The pipe 10 is preferably as thin as possible from the viewpoint of reducing the diameter of the optical cable, and in order to secure a greater pumping property in the thinner pipe 10, it is desirable to reduce the outer diameter of the optical fiber unit 1. Further, in order to obtain good pumpability, it is desirable that the cross-sectional shape of the optical fiber unit 1 be circular.

By the way, in order to cope with an increase in the capacity of optical transmission, a larger number of optical fiber core wires 2 are gathered than before,
It is being studied to further increase the number of optical fiber units 1. However, it is not easy to make the optical fiber unit 1 multi-core while keeping the cross-sectional shape of the optical fiber unit 1 circular and to make the outer diameter of the optical fiber unit as thin as possible.

For example, as shown in FIG. 4, when attempting to increase the number of cores of the optical fiber unit 1 by laminating a large number of optical fiber ribbons 2, the entire optical fibers of the laminated optical fiber tapes 2 are The dimension of the tape core wire 2 in the thickness direction increases. Therefore, there is a problem that the outer diameter of the optical fiber unit 1 has to be extremely large in order to form the collective coating layer 4 in a circular cross section. Further, as a configuration suitable for making the cross-sectional shape of the optical fiber unit 1 circular, as shown in FIG. 5, the optical fiber tape core wires 2 are gathered around the central member 5 and the press winding layer 6 is provided on the circumference thereof. And the sheath 7 is sequentially formed. However, in this case, since the central member 5 is provided in the optical fiber unit 1, the optical fiber unit 1
However, there was a problem that the outer diameter of was very large.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to increase the number of optical fiber units while keeping the cross-sectional shape of the optical fiber unit circular, and to reduce the diameter of the optical fiber unit. is there.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is a tape-shaped optical fiber in an optical fiber unit in which a plurality of optical fiber core wires are integrated by a collective coating layer. An optical fiber unit characterized in that two or more optical fibers are laminated in a thickness direction, and an optical fiber optical fiber different from the optical fiber optical fibers is arranged outside the laminated optical fiber optical fibers in the width direction. is there. According to a second aspect of the invention, when the dimension in the thickness direction of the entire laminated optical fiber core wires is a and the dimension in the same direction of another optical fiber core wire arranged outside thereof is b. , A> b, the optical fiber unit according to claim 1.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
FIG. 1 is a sectional view showing an embodiment of the optical fiber unit of the present invention. The optical fiber unit 20 of the present embodiment is composed of a laminated core wire portion 25, a side core wire portion 26, and a collective coating layer 24.

The laminated core wire portion 25 is formed by laminating five optical fiber tape core wires 21 in the thickness direction. As the optical fiber tape core wire 21 forming the laminated core wire portion 25, an optical fiber tape core wire having an arbitrary configuration can be used as long as it has two or more cores. In this embodiment, a four-core optical fiber tape core wire 21 in which four optical fiber element wires 22 arranged in parallel are collectively covered with a coating layer 23 is used. The number of the optical fiber tape core wires 21 constituting the laminated core wire portion 25 is two or more, and the dimension a in the thickness direction of the entire laminated core wire portion 25 is the dimension of the side core wire portion 26 in the same direction. It is set to be larger than b. If these dimensions are a ≦ b, the cross-sectional shape of the portion where the laminated core wire portion 25 and the lateral core wire portion 26 are combined cannot be close to a circular shape, which will be described later, which is not preferable.

The lateral core wire portion 26 is provided outside one or both of the width direction of the laminated core wire portion 25 adjacent to the laminated core wire portion 25, and is composed of an optical fiber core wire.
The optical fiber core wire forming the side core wire portion 26 may be a single core optical fiber core wire or an optical fiber tape core wire having two or more cores. Further, one (one) optical fiber core wire may be used to configure the side core wire portion 26 on one side, or a plurality of optical fiber core wires may be used. The shape of the side core wire portion 26 is preferably designed so that the cross-sectional shape of the combined portion of the laminated core wire portion 25 and the side core wire portion 26 is as close to a circle as possible. To this end, for example, when the lateral core wire portion 26 is formed by using two or more optical fiber tape core wires 21, the width direction of the optical fiber tape core wire 21 forming the lateral core wire portion 26 is The optical fibers may be arranged so as to be perpendicular to the width direction of the optical fiber ribbons 21 that form the laminated core 25. Although not shown, when the lateral core portion 26 is configured by using a single-core optical fiber core, the single-core optical fiber cores are laminated so that the above dimension is a> b. It may be laminated in the thickness direction of the core wire portion 25. Alternatively, the whole of the laminated core wire portion 25 and the side core wire portion 26 may be twisted. In the present embodiment, the optical fiber tape core wire 2 which is the same as the optical fiber tape core wire 21 which constitutes the laminated core wire portion 25.
1 are arranged adjacent to each other on both sides of the laminated core wire portion 25 so that the width direction thereof is perpendicular to the width direction of the optical fiber tape core wire 21 forming the laminated core wire portion 25.

The collective coating layer 24 is formed by extrusion coating around the laminated core wire portion 25 and the lateral core wire portion 26 so as to have a circular cross section. As the material of the collective coating layer 24, the same foamed polyethylene as that used in the conventional optical fiber unit can be used. Collective coating layer 2
The size of 4 is appropriately set so that the laminated core wire portion 25 and the lateral core wire portion 26 can be integrated and the mechanical characteristics required for the optical fiber unit can be secured. In order to reduce the diameter of the optical fiber unit, the collective coating layer 24 is preferably as small as possible.

In the optical fiber unit of this embodiment, as shown in FIG. 1, in a state where seven optical fiber ribbons 21 are gathered, one end of the optical fiber ribbon 21 is passed through a molding die and the periphery thereof is made of polyethylene foam. It is obtained by forming the coating layer 24 to have a circular cross section.

In the optical fiber unit of this embodiment, a total of seven optical fiber tape core wires 21 are integrated, and two of them are located on both sides of the laminated core wire portion 25, respectively. Since the optical fibers are arranged as the core portion 26, the sectional shape of the entire seven optical fiber tape core wires 21 is close to a circle. Therefore, when the collective coating layer 24 is formed in a circular cross section to form an optical fiber unit, as compared with the case where seven optical fiber ribbons 2 are stacked as shown in FIG. The outer diameter of can be reduced. In addition, the laminated core wire portion 25 and the lateral core wire portion 2
By twisting the whole 6 together, the bending characteristics of the optical fiber unit can be improved. The bending characteristics can also be improved by forming the side core wire portion 26 using a single-core optical fiber core wire. Further, in the optical fiber unit of the present embodiment, the laminated core wire portion 25 and the side core wire portion 26 are formed by using the optical fiber tape core wire 21 having the same structure, so that the material cost can be kept low. It is advantageous and has good workability in branching and connecting the optical fiber unit.

[0014]

【Example】

(Example 1) An optical fiber unit was constructed using four optical fiber ribbons each having a thickness of 0.3 mm and a width of 1.1 mm. Four of the optical fiber ribbons were laminated to form a laminated fiber portion, and one optical fiber ribbon was arranged on each side of the laminated fiber portion to form a lateral fiber portion. An optical fiber unit having a circular cross section was obtained by forming a collective coating layer made of foamed polyethylene around the six optical fiber tape core wires thus assembled. The outer diameter of the optical fiber unit is 2.8m
m.

(Comparative Example 1) An optical fiber unit was constructed by using six 4-fiber optical fiber ribbons similar to those in Example 1 above. The side core portion was not provided, and six optical fiber ribbon core wires were laminated in the thickness direction. An optical fiber unit having a circular cross section was obtained by forming a collective coating layer made of foamed polyethylene around the six optical fiber tape core wires thus assembled. The outer diameter of the optical fiber unit is 3.
It was 0 mm.

(Example 2) Thickness 0.4 mm, width 0.6 m
An optical fiber unit was constructed by using two optical fiber ribbons of m. Two of the optical fiber ribbons were laminated to form a laminated fiber portion, and one optical fiber ribbon was placed on each side of the laminated optical fiber portion to form a lateral fiber portion. An optical fiber unit having a circular cross section was obtained by forming a collective coating layer made of expanded polyethylene around the four optical fiber tape core wires thus assembled. The outer diameter of the optical fiber unit was 2.3 mm.

(Comparative Example 2) An optical fiber unit was constructed by using four two-core optical fiber tape core wires similar to those of the above-mentioned Example 1. The side core portion was not provided, and four optical fiber ribbon core wires were laminated in the thickness direction. An optical fiber unit having a circular cross section was obtained by forming a collective coating layer made of expanded polyethylene around the four optical fiber tape core wires thus assembled. The outer diameter of the optical fiber unit is 2.
6 mm. Examples 1 and 2 and Comparative Examples 1 and 2
From the results, it is recognized that the diameter of the optical fiber unit can be reduced by providing the side core portion.

[0018]

As described above, according to the optical fiber unit of the present invention, two or more tape-shaped optical fiber cores are laminated in the thickness direction, and the laminated optical fiber cores are arranged in the width direction. By arranging an optical fiber core wire different from this on the outside, while keeping the cross-sectional shape of the optical fiber unit circular, while increasing the number of optical fiber units,
The diameter of the optical fiber unit can be reduced. Preferably, the dimension a in the thickness direction of the entire laminated optical fiber core wires is set to be larger than the dimension b in the same direction of another optical fiber core wire arranged on the outer side thereof, For example, the cross-sectional shape of the entire optical fiber core wire forming the optical fiber unit can be made close to a circle. Therefore,
When forming a collective coating layer with a circular cross section around these,
It is possible to suppress waste of the collective coating layer and obtain an optical fiber unit in which the optical fiber core wires are arranged at a high density.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an optical fiber unit of the present invention.

FIG. 2 is a sectional view showing an example of a conventional optical fiber unit.

FIG. 3 is an explanatory diagram of a pneumatic feeding method.

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

FIG. 5 is a sectional view showing an example of a conventional optical fiber unit.

[Explanation of symbols]

 21 ... Optical fiber tape core wire, 24 ... Collective coating layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Araki 1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Ltd. Sakura Factory

Claims (2)

[Claims] 1. An optical fiber unit in which a plurality of optical fiber core wires are integrated by a collective coating layer, two or more tape-shaped optical fiber core wires are laminated in the thickness direction, and the laminated optical fiber. An optical fiber unit in which another optical fiber core wire is arranged outside the width direction of the fiber core wire. 2. When the dimension in the thickness direction of the entire laminated optical fiber core wires is a and the dimension in the same direction of another optical fiber core wire arranged outside thereof is b, a> b The optical fiber unit according to claim 1, wherein