JPH11183764A - Optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable capable of efficiently storing tape- like coated optical fibers in a cylindrical space and is excellent in a loss characteristic. SOLUTION: Plural tape-like coated optical fibers 1 are laminated, cushiony fiber 2 is arranged on the outside of these coated fibers 1 and the fibers 1 and the fibers 2 are stored in a cylindrical member 3. The occupation ratio of the filler 2 in space excluding the fibers 1 in the inner space of the member is 10 to 50%. Consequently an initial transmission loss and a loss increasing characteristic at a low temperature can be improved.

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 having a structure in which an optical fiber ribbon is accommodated in a cylindrical space.

[0002]

2. Description of the Related Art As one of the methods for realizing a multi-core optical fiber cable, a tape-shaped optical fiber core is used in which an optical fiber is aligned and coated to form a tape. By laminating a plurality of the tape-shaped optical fiber cores, a multi-core optical fiber cable can be easily configured. However, simply laminating a plurality of tape-shaped optical fiber cores is susceptible to an external force, and the microbend loss increases. As a countermeasure, for example, in an optical fiber cable described in Japanese Patent Application Laid-Open No. 8-278432, a structure in which a plurality of tape-shaped optical fiber core wires are housed in a metal tube is adopted.

However, in the conventional structure in which only the tape-shaped optical fiber core is directly accommodated in the cylindrical space, the optical fiber core located at the end of the tape-shaped optical fiber core is formed by the inner wall of the metal cylinder. There is a problem that the transmission loss is likely to increase due to the side pressure. Therefore, in order to prevent lateral pressure from acting on the tape-shaped optical fiber, the cylindrical space is enlarged, and the number of cores and the number of laminated tape-shaped optical fibers accommodated in the cylindrical space are limited. There has been a problem in designing the fiber cable.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in consideration of the above circumstances. An optical fiber which can efficiently store a tape-shaped optical fiber core in a cylindrical space and has good loss characteristics is provided. It is intended to provide a cable.

[0005]

According to the first aspect of the present invention, there is provided a structure in which a plurality of tape-shaped optical fiber cores are laminated, and a cushioning filler is arranged around the cores and housed in a cylindrical space. An optical fiber cable comprising: a space factor of the cushioning filler in a space excluding the tape-shaped optical fiber core wire in the cylindrical space;
0 to 50%.

According to a second aspect of the present invention, there is provided the optical fiber cable according to the first aspect, wherein the plurality of tape-shaped optical fiber cores are formed from one or more kinds of four to twelve fibers. It is characterized by becoming.

According to a third aspect of the present invention, in the optical fiber cable according to the first or second aspect, the cylindrical space is formed by extruding a plastic material on the outer periphery of the cushioning filler. It is characterized by the following.

According to a fourth aspect of the present invention, in the optical fiber cable according to the first or second aspect, the cylindrical space is formed of a metal tube formed on the outer periphery of the cushioning filler. Is what you do.

According to a fifth aspect of the present invention, in the optical fiber cable according to any one of the first to fourth aspects, the cushioning filler is formed by laminating a tape-shaped optical fiber core. It is characterized by being twisted while reversing the direction or direction.

According to a sixth aspect of the present invention, in the optical fiber cable according to any one of the first to fifth aspects, the cushioning filler is a yarn or a fiber bundle. is there.

According to a seventh aspect of the present invention, in the optical fiber cable according to any one of the first to sixth aspects, the cushioning filler has a water absorbing property. It is.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An outline of an optical fiber cable according to the present invention will be described. The basic configuration is to stack a plurality of tape-shaped optical fiber cores, place a cushioning filler at an appropriate space factor around the core, and then place a metal or plastic inside cylindrical member. It is housed in a cylindrical space. As described above, the optical fiber cable may be formed by using the cylindrical member itself accommodating the tape-shaped optical fiber core wire as an outer jacket, or an outer jacket may be provided on the cylindrical member to constitute the optical fiber cable. Further, as described above, the cylindrical member accommodating the tape-shaped optical fiber core wire may be used as a constituent element of the optical fiber cable, and a plurality of the cable elements may be assembled and sheathed to form an optical fiber cable. . In this specification, such a cable element is also called an optical fiber cable.

Here, the space factor of the cushioning filler disposed around the plurality of optical fibers in the cylindrical space will be defined. The inner diameter of the cylindrical member is 2
r, when the total cross-sectional area of the optical fiber ribbon is A and the total cross-sectional area of the cushioning filler is B, the space factor S (%)
Is represented by S = (B / (πr ² -A)) × 100. Here, as a cushioning filler,
When a fibrous material whose thickness is represented by denier is used, the total cross-sectional area B (cm ² ) of the cushioning filler is used.
Is represented by B = (denier number × total number) / 900000 × specific gravity of cushioning filler).

When the space factor of the cushioning filler and the characteristics of the optical fiber cable were examined, the following facts were found. Since the cushioning filler is located between the tape-shaped optical fiber core wire and the inner wall of the cylindrical member and acts as an elastic buffer layer, when the transmission loss at room temperature is considered, the space factor is increased. Better. Specifically, 10%
It is better to do the above. In a low temperature state, metal or plastic, which is a constituent material of the cylindrical member, shrinks and bends the tape-shaped optical fiber core in the width direction, thereby increasing transmission loss. In order to suppress the increase in the transmission loss, it is necessary to reduce the space factor to 50% or less and to sufficiently secure a space in which the optical fiber ribbon can move.

As a result of such consideration, the space factor is 10 to 50%.
By arranging the cushioning filler around the tape-shaped optical fiber core such that the optical fiber cable has good initial loss and loss temperature characteristics.

The optical fiber ribbon in the cylindrical space may be loosely accommodated so as to give a slight meandering.

Hereinafter, embodiments will be described. FIG.
FIG. 2 is a sectional view of a first embodiment of the optical fiber cable of the present invention. In the figure, 1 is a tape-shaped optical fiber core wire, 2 is a cushioning filler, and 3 is a cylindrical member. A plurality of tape-shaped optical fiber cores 1 are laminated, a cushioning filler 2 is arranged around the core, and the tape-shaped optical fiber is housed in a cylindrical member 3.

In a prototype example based on this embodiment, the tape-shaped optical fiber core 1 is 0.3 mm thick and 2.1 m wide.
An eight-core tape-shaped optical fiber core having a length of m was used, and eight such cores were laminated to form a 64-core optical fiber cable. As the cylindrical member 3, a plastic tube having an outer diameter of 6 mm and an inner diameter of 4.8 mm was used. As the cushioning filler 2, a polyester string was used, and the space factor was experimentally manufactured in a range of 0 to 80%. As the polyester string, a trial-produced version was prepared by vertically twisting the optical fiber ribbon 1 and twisted in one direction. Transmission loss and loss temperature characteristics at a wavelength of 1.55 μm were evaluated for the prototype optical fiber cables having different space factors. Regarding the loss temperature characteristic, the low temperature characteristic was measured, and the measurement condition was −20.
An increase in loss at ℃ was observed.

FIG. 2 shows the measurement results. The transmission loss is 0.25 dB / when the space factor of the cushioning filler is 10% or more.
It is a good level of less than km. On the other hand, as for the low temperature characteristics, the increase in loss at −20 ° C. was 0.03 dB / km or less, which is the measurement accuracy, in the range where the space factor of the cushioning filler was 50% or less, indicating good characteristics. .

From these results, it was confirmed that when the space factor of the cushioning filler is 10 to 50%, the initial transmission loss and low-temperature loss increasing characteristics can be improved.

Similar prototypes and evaluations were made for other specific examples. That is, the outer diameter is 5.0 mm and the inner diameter is 3.8 mm
And an optical fiber cable having an outer diameter of 6.5 mm and an inner diameter of 5.3 mm. As in the case of the outer diameter of 6.0 mm and the inner diameter of 4.8 mm, it was confirmed that the initial transmission loss and low-temperature loss increase characteristics can be improved by setting the space factor of the cushioning filler to 10 to 50%. did it.

As described above, according to the present invention, an index for configuring an optical fiber cable to have a small diameter is obtained, which is effective in reducing manufacturing, transport, and storage costs.

FIG. 3 is a sectional view of a second embodiment of the optical fiber cable according to the present invention. In the figure, the same parts as those in FIG. In this example,
Different types of tape-shaped optical fiber cores to be laminated were combined. In a specific example, three 12-core optical fiber cores are laminated at the center, and eight upper and lower tape-type optical fiber cores are laminated one above each above and below. The total is 60 hearts.

As described above, even in the optical fiber cable in which the tape-shaped optical fibers having different numbers of cores are combined, the space factor of the cushioning filler 2 is 10 to 50%.
It was confirmed that the initial transmission loss and the low-temperature loss increase characteristics can be improved by setting to.

FIG. 4 is a sectional view of a third embodiment of the optical fiber cable according to the present invention. In the figure, the same parts as those in FIG. 4 is a sheath, 5 is a tension member, and 6 is a plastic tube. In this embodiment, the present invention is applied to a self-supporting type optical fiber cable. The tension member 5 is installed as a support wire.

In the optical fiber cable of FIG. 4A, the sheath 4 for connecting the cable core and the tension member is used as a cylindrical member of the cable core. The sheath 4 is formed by extrusion coating of plastic. As described above, the space factor of the cushioning filler 2 is set in the range of 10 to 50%.

In the optical fiber cable shown in FIG. 4B, the cylindrical member has a two-layer structure of a plastic tube 6 and a sheath 4. Also in this embodiment, the space factor of the cushioning filler 2 is set in the range of 10 to 50%.

FIG. 5 is a sectional view of a fourth embodiment of the optical fiber cable according to the present invention. In the figure, the same parts as those in FIG. 7 is a holding roll,
8 is a tube and 9 is a tension member. In this embodiment, as the cushioning filler 2 disposed around the lamination of the tape-shaped optical fiber cores 1, a fibrous or cord-like linear body is used, and a holding roll 7 is applied thereon. And housed in a sheath 8 which is a cylindrical member. The inner diameter of the sheath 8 is made larger than the outer diameter of the presser winding 7 so as to provide a gap for securing the space factor. Note that the holding roll 7 may be loosened to have a space factor. The tube 8 is formed by extruding plastic. The cushioning filler 2 was vertically attached.

In a specific example, the tape-shaped optical fiber core is
Eight pieces of eight cores were laminated. The cushioning filler 2 is
A polyester string was used, and a non-woven tape having a thickness of 0.1 mm was used for the holding roll 7. The tube 8 is formed by extruding polyethylene and has an inner diameter of 4.8 m.
m, outer diameter 8.0 mm.

FIG. 6 is a sectional view of a fifth embodiment of the optical fiber cable according to the present invention. In the figure, the same parts as those in FIG. In this embodiment, the cushioning filler 2 is made of the same material as that of the fourth embodiment, but is twisted in one direction around the laminated optical fiber ribbon.

FIG. 7 is a sectional view of a sixth embodiment of the optical fiber cable according to the present invention. In the figure, the same parts as those in FIG. In this embodiment, the cushioning filler 2 is made of the same material as that of the fourth embodiment, but is made of SZ twist in which the twist direction changes alternately around the laminated optical fiber ribbon. In the specific example, the twisting direction was changed by about 3 to 4 turns.

In the prototypes of the optical fiber cables of the fourth to sixth embodiments, the space factor of the cushioning filler was set to 20%, but in all cases, the initial transmission loss and the increase in the low-temperature loss at -20.degree. The characteristics were good.

The bending characteristics of the prototypes of the optical fiber cables of the fourth to sixth embodiments were evaluated. Bending diameter 10
When bent to a small diameter of 0 mm, no change in transmission characteristics was observed in the fifth and sixth embodiments, but a transmission loss of 0.06 dB / km occurred in the fourth embodiment. Was. This is because, in the fifth and sixth embodiments, the cushioning filler 2 is twisted, so that the laminated tape-shaped optical fiber core wires can be prevented from protruding from the cushioning filler, and the lateral pressure is reduced. It is considered that the transmission loss was hardly increased by the transmission. Furthermore, in the case of the fifth embodiment, when the tube 8 and the presser winding 7 are removed at the terminal, the cushioning filler 2 does not enter the gap of the laminated tape-shaped optical fiber core 1 or the like, It was confirmed that the cushioning filler 2 could be easily removed and excellent handling workability was obtained. In the fourth and sixth embodiments, when the tube 8 and the presser winding 7 are removed at the end, the cushioning filler 2 does not wrap around the laminated optical fiber ribbon 1. Workability is good, especially when a long tape-shaped optical fiber core wire is taken out at a terminal.

In the seventh embodiment, a water-absorbing yarn is used as the cushioning filler 2 in the fifth embodiment. As in the fifth embodiment, the initial transmission loss and the low-temperature loss increasing characteristics at -20 ° C are good. Further, as a result of extending the cable in a horizontal state, opening the middle part and injecting water, the running The water length is only 5 m, and has good characteristics as an optical fiber cable buried outdoors or underground where there is a possibility of flooding.

In each of the above-described embodiments, the tape-shaped optical fiber core is laminated straight.
The laminated optical fiber ribbon may be twisted at an appropriate pitch, and a cushioning filler may be disposed around the twisted optical fiber.
When twisting is performed on the laminated optical fiber ribbon, when the optical fiber cable is bent, the length of the optical fiber becomes uniform, so that performance with excellent transmission characteristics and reliability can be exhibited.

As the cushioning filler, in addition to the above-mentioned polyester string, a linear body having appropriate elasticity and cross-sectional area, such as polypropylene yarn, cotton fiber bundle, and porous fiber, can be used. In the case where the holding roll is applied to the outside of the cushioning filler as in the fourth to sixth embodiments, the material of the holding roll is not limited to the nonwoven fabric, but may be a string-like material or a tape-like material. Can be used.

As the material of the cylindrical member, besides polyethylene, polyester, nylon, or another suitable plastic material can be used. In addition, it is not limited to plastic materials, but stainless steel,
Metal materials such as aluminum and copper can also be used. Further, the cylindrical member may be formed of a plurality of layers of materials selected from these materials. Note that the cylindrical member does not mean a geometrical cylindrical shape, but a third member.
As in the embodiment of the present invention, it is also possible to include a structure in which a connection portion with a support wire is added, and may have any shape as long as a substantially cylindrical space is formed therein.

[0038]

As is apparent from the above description, according to the present invention, a plurality of tape-shaped optical fiber cores are laminated, a cushioning filler is provided around the core, and a space factor of 10 is provided.
By arranging it at about 50% and storing it in a cylindrical space, it is possible to obtain an optical fiber cable having good initial transmission loss and loss increasing characteristics at low temperatures. In particular, it is effective when applied to overhead optical fiber cables, underground optical fiber cables, and the like.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the optical fiber cable of the present invention.

FIG. 2 is a diagram showing measurement results of a prototype example.

FIG. 3 is a sectional view of a second embodiment of the optical fiber cable of the present invention.

FIG. 4 is a sectional view of a third embodiment of the optical fiber cable of the present invention.

FIG. 5 is a sectional view of a fourth embodiment of the optical fiber cable of the present invention.

FIG. 6 is a sectional view of a fifth embodiment of the optical fiber cable of the present invention.

FIG. 7 is a sectional view of a sixth embodiment of the optical fiber cable of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tape-shaped optical fiber core wire, 2 ... Cushioning filler, 3 ... Cylindrical member, 4 ... Sheath, 5 ... Tension member, 6 ... Plastic tube, 7 ... Holding coil, 8 ... Tube, 9 ... Tension member.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiyuki Suetsugu 1-chome, Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Hideyuki Iwata 3-9-1, Nishishinjuku, Shinjuku-ku, Tokyo No. Japan Telegraph and Telephone Corporation

Claims (7)

[Claims] 1. An optical fiber cable having a structure in which a plurality of tape-shaped optical fiber cords are laminated, a cushioning filler is disposed around the plurality of optical fibers, and is housed in a cylindrical space. An optical fiber cable, wherein a space factor of the cushioning filler in a space excluding the tape-shaped optical fiber core is 10 to 50%. 2. The optical fiber cable according to claim 1, wherein the plurality of tape-shaped optical fiber cores are formed of one or more types of four to twelve cores. 3. The optical fiber cable according to claim 1, wherein the cylindrical space is formed by extruding a plastic material around the cushioning filler. 4. The optical fiber cable according to claim 1, wherein the cylindrical space is formed of a metal tube formed on an outer periphery of the cushioning filler. 5. The method according to claim 1, wherein the cushioning filler is formed by laminating a tape-shaped optical fiber core and twisting it in one direction or reversing the direction.
The optical fiber cable according to any one of claims 4 to 4. 6. The optical fiber cable according to claim 1, wherein the cushioning filler is a yarn or a fiber bundle. 7. The optical fiber cable according to claim 1, wherein the cushioning filler has water absorbency.