JP2002350695A - Optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical cable in which the identifying property of a cord-form buffer from a ripping cord is improved for mid-span branching and the like. SOLUTION: An optical cable 10 has a buffer 13 made of an open cord 13a around optical coated fibers 12 and an enclosure 14 outside the buffer 13. The ripping cord 16 embedded in the longitudinal direction in the enclosure 14 can be visually identified from the open cord 13a constituting the buffer body 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable which is useful for constructing an optical communication network and which has excellent intermediate branchability.

[0002]

2. Description of the Related Art In recent years, with the rapid spread of the Internet and the like, construction of an optical communication network using low-loss, wide-band optical fibers has been promoted. There is a growing need for a so-called middle post-branch compatible optical cable that can take out a fiber and connect a desired optical fiber.

[0003] Various types of optical cables having an intermediate post-branch property have been developed in the past. Among them, as shown in FIG. 3, a plurality of optical fiber wires 1a are connected in parallel. One or a plurality of optical fiber ribbons 1 coated in a lump on the outer periphery are laminated, a string-like buffer 2 made of plastic or the like is provided around the core, and a jacket 3 is further provided on the outside. However, not only does it have intermediate post-branching properties, it has a simple structure,
Because the diameter and weight of the cable can be reduced,
Attention has been paid.

That is, in this optical cable, two tensile members 4 and 4 and tearing strings 5 and 5 are embedded in the jacket 3 in a longitudinally attached manner. Is to make a cut into the jacket 3 using a cutter or the like to take out the tear string 5 and pull the tear string 5 outward, whereby the jacket 3 is torn in the length direction and the inner optical fiber tape core is cut. The wire 1 can be easily taken out. In addition, as shown in FIG. 3, the sheath 3a of the embedment portion of each tear string 5 has the thickness of the jacket 3 thinner than that of the other portion by embedding the tear string 5, and the tear string 5 is embedded. When a lateral pressure is applied to the portion of the optical cable, even if the force is small, the optical cable is deformed and a force is applied to the optical fiber in the optical cable to prevent transmission loss from increasing. Since it is formed thicker than the jacket 3, the embedding position of the tear string 5 can be easily estimated from the thickened portion 3a.

[0005]

As described above, the above-mentioned optical cable has excellent characteristics. However, when the optical fiber cable is cut in the middle after branching in the middle, it is necessary to actually take out the tear string 5 by cutting the outer jacket 3 with a cutter or the like. Even when the cut 3 is made using the thick portion 3a of the jacket 3 as a guide, the colors of the tear string 5 and the string-shaped buffer 2 are the same (normally, the tear string 5 and the string-shaped buffer 2). 2 uses a white polypropylene fiber.) Therefore, in a dark place or the like, it was sometimes difficult to distinguish between the two.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical cable capable of improving the discriminability between a string-shaped buffer and a tear string at the time of intermediate branching or the like. Aim.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a string-shaped buffer is provided around an optical fiber core, and a jacket is provided outside the buffer. An optical cable, characterized in that a tear string is vertically embedded in the jacket and the tear string and the string-shaped buffer are visually identifiable. .

[0008] The invention described in claim 2 is an optical cable, characterized in that the tear string and the string-shaped buffer are distinguishable by color.

In the optical cable according to the present invention, since the tear string and the string-shaped buffering body vertically embedded in the jacket can be visually distinguished, the tear string is used in the middle rear branch and the like. And the string-shaped buffer can be easily identified.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing one embodiment of the optical cable of the present invention. As shown in FIG. 1, this optical cable 10 comprises four optical fiber strands 11 arranged in parallel, and an optical fiber tape core 12 having its outer periphery coated collectively.
The four layers are laminated, and an opening string 13a made of white polypropylene fiber is vertically attached or twisted around the four layers to form a buffer 1
3 and a structure in which an outer cover 14 made of a plastic such as polyethylene or polyvinyl chloride is provided on the outside of the cover. In the jacket 14, two steel wires or FR
Tensile strength members 15, 15 made of P (glass fiber reinforced plastic) or the like are vertically attached so as to be symmetrical with respect to the center of the cable, and are substantially circumferentially extended from each of the tensile strength members 15, respectively. Two tear cords 16, 16 each made of a yellow-colored polypropylene fiber or the like are embedded in the position rotated by 90 °, one by one in each case. Therefore, these two tear cords 16 and 16 also have two tensile strength members 1.
Like 5 and 15, they are embedded at positions symmetrical to each other with respect to the center of the cable. Further, the thickness of the jacket 14 of the embedded portion of each tear string 16 is larger than the thickness of the jacket of the portion other than the embedded portion of the tear string 16. FIG.
The reference numeral 14a indicates the thickened portion.

In the optical cable thus configured, the buffer 13 is formed by the opened string 13a made of white polypropylene fiber, while the tear string 16 is formed by the yellow colored polypropylene fiber. ,
In the middle post-branch, when the tear 14 is to be taken out by making a cut in the jacket 14 using a cutter or the like, the tear string 16 can be instantaneously identified by the naked eye from the opened fiber 13a due to the difference in color. . Therefore, the identifiability of the tear string 16 with the spread string 13a is improved, and the workability of taking out the optical fiber ribbon 12 can be improved.

In the embodiment described above, a normal white polypropylene fiber is used for the open string 13a constituting the buffer 13 and a tear string 16 made of yellow-colored polypropylene fiber is used. But
In the present invention, the buffer 13 and the tear string 16 only need to be visually identifiable, and are not particularly limited to such an example.

That is, for example, an open fiber 13a made of yellow colored polypropylene fiber may be used for the buffer 13 and a conventional white polypropylene fiber may be used for the tear string 16, The buffer 13 and the tear string 16 may both be made of a material colored yellow or another color. Further, the buffer 13
Alternatively, the tear string 16 may not be formed of a material that has been colored in advance, and only the surface thereof may be colored. Also,
The buffer 13 or the tear string 16 may be partially colored as long as it can be visually identified.

The materials of the buffer 13 and the tear string 16 are not particularly limited to the above examples, as long as they can exhibit the required functions. For example, examples of the material of the buffer 13 include polyethylene terephthalate fiber, polyester fiber, aramid fiber, and glass fiber, and examples of the material of the tear string 16 include polyester fiber, aramid fiber, and glass fiber.

Furthermore, in the above embodiment, four four-core optical fiber ribbons are stacked and accommodated inside. However, the type, number, and accommodation form of the optical fiber cores are appropriately determined according to the application. May be selected.

Further, as shown in FIG. 2, a structure in which a cable supporting wire 18 is attached to the jacket 14 of the optical cable 10 of the above embodiment may be adopted. In FIG. 2, reference numeral 19 denotes a covering portion provided on the outer periphery of the cable support wire 18, and reference numeral 20 denotes a neck portion that connects the jacket 14 of the optical cable 10 and the cable support wire covering portion 19.

In such an optical cable with a supporting wire, as in the case of the optical cable 10 of the above-described embodiment, at the time of intermediate rear branching, when a cut is made in the jacket 14 using a cutter or the like to take out the tear string 16, Since the tear string 16 can be instantaneously identified from the buffer 13 with the naked eye, the discriminability between the tear string 16 and the buffer 13 is improved, and the workability of taking out the optical fiber ribbon 12 can be improved. .

[0019]

As described above, according to the optical cable of the present invention, the tear string embedded vertically in the jacket and the string-shaped buffering body disposed around the optical fiber core are provided. Is visually identifiable, so that the tearing string can be more easily distinguished from the string-shaped buffer at the time of intermediate rear branching or the like.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing another embodiment of the optical cable of the present invention.

FIG. 3 is a sectional view showing an example of a conventional optical cable.

[Explanation of symbols]

 Reference numeral 10: Optical cable 12: Optical fiber ribbon 13: Buffer 13a: Spreading cord 14: Jacket 16: Tearing cord

Claims (2)

[Claims] 1. An optical cable comprising a cord-shaped buffer around an optical fiber core wire, and further comprising an outer jacket, wherein a tear string is vertically embedded and embedded in the outer jacket, An optical cable characterized in that the tear string and the string-shaped buffer can be visually identified. 2. The optical cable according to claim 1, wherein the tear string and the string-shaped buffer are distinguishable by color.