JP3058203B2 - Optical cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of optical fiber ribbons using thin optical fiber wires in a gutter-shaped container.
The present invention relates to a housed multi-core optical cable.

[0002]

2. Description of the Related Art At present, a subscriber optical cable having a capacity of up to 4000 cores is being developed. As such an optical cable, one having a structure as shown in FIG. 2 has been proposed. In FIG. 2, reference numeral 1 denotes a tension member formed of a metal stranded wire, an FRP rod, or the like. A plurality of gutter-like containers 2 are twisted around the tension member 1, and a polyester tape is placed thereon. A tape winding layer 3 on which a tape such as a tape is wound is provided, on which a plurality of gutter-shaped containers 2 are twisted, and a tape winding layer 3 is provided, on which a polyvinyl chloride or the like is provided. Is covered. The gutter-shaped container 2 is
As shown in FIG. 3, it is a long body having a U-shaped cross section and an inner width of about 3 mm and a depth of about 5 mm made of plastic such as polyethylene.

As shown in FIG. 3, a plurality of optical fiber ribbons (hereinafter abbreviated as tape ribbons) 5 are stored in the gutter-shaped container 2 in a bundled state.
This tape core wire 5 has a wire diameter of 200 as shown in FIG.
... A plurality of optical fibers 6 .mu.m or less are arranged in parallel and covered with a collective coating layer 7 made of an ultraviolet curable resin or the like. In such an optical cable, the outer diameter of the optical fiber 6 is set to 200 μm or less to make the outer diameter of the optical fiber 6 smaller than that of the conventional optical fiber, and at the same time, as shown in FIG. The thickness of the optical fiber 5 is also substantially the same as or slightly larger than the outer diameter of the optical fiber 6, and its width is also slightly wider than the sum of the outer diameters of the optical fiber 6. Accordingly, the thickness of the collective coating layer 7 is 2 to 5 μm at the thinnest portions of both side portions 5 a and 5 a and the flat portions 5 b and 5 b of the tape core wire 5.
It is very thin with a degree.

By the way, in such an optical cable, of the optical fiber wires 6 constituting the tape core wire 5 housed in the gutter-shaped housing body 2, the optical fiber wires located at both ends thereof are arranged. Transmission loss on line 6 may increase.
This is because when the gutter-like container 2 is twisted,
One end of the tape core 5 is pressed against one of the side walls 2a, 2a, and the thickness of the collective coating layer 7 is extremely thin. This is due to receiving a large lateral pressure.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent an increase in the transmission loss of the optical fiber at both sides constituting the tape core housed in the gutter-shaped housing of the optical cable. is there.

[0006]

An object of the present invention is to provide an optical cable.
This problem can be solved by making the thickness of both sides of the collective coating layer of the tape core wires accommodated in the gutter-shaped container of the taper thicker than the thickness of the flat portion. In addition, the thickness of both sides of the batch coating layer is set to 10
It is preferable to set the range to 30 μm.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a tape core 11 used in the optical cable of the present invention. The difference between the tape core 11 of this example and the conventional tape core 5 shown in FIG. 4 is that the thickness of the collective coating layer 12 on both side parts 11a, 11a is larger than the flat parts 11b, 11b. It is a point. The batch covering layer 1 of the both side portions 11a, 11a
The thickness of No. 2 is indicated by W in FIG. 1;
The range is 30 μm. If W is less than 10 μm, the effect of preventing an increase in transmission loss cannot be obtained, and if it exceeds 30 μm, the width of the tape core 11 becomes wide, which is contrary to the demand for downsizing the tape core 11. Also, the flat portion 11
b, 11b are thicker than both side parts 11a, 11a
And the thickness of the tape core wire 11 becomes thicker, and the number of accommodated core wires decreases.
Less.

In order to manufacture such a tape core 11, it is possible to slightly change the shape of a discharge port of a die for forming the collective coating layer 12. In addition, the collective coating layer 12 is preferably formed from an ultraviolet curable resin, but other resins such as a polyamide resin and a silicone resin are used. However, an excessively hard resin is not preferable in terms of the effect of relaxing the side pressure. , 50-150 in elastic modulus
It is desirable to use a resin in the range of kg / mm ² .

In the optical cable of the present invention, a plurality of the above-described tape core wires 11 are stacked and housed in the gutter-shaped housing body 2 .
2 and a plurality of the gutter-like containers 2 are bundled and assembled, a tape winding layer is provided, a sheath is applied, and a plurality of tape cores 11 are gutter-like containers. 2 is used.

In such an optical cable, its gutter is used.
Side portions 1 of the tape core wire 11 stored in the container
Since the coating thickness of 1a and 11a is large, even when pressed against the side walls 2a and 2a of the gutter-shaped container 2, the lateral pressure is not transmitted to the internal optical fiber 6 and the light located on both sides is not transmitted. The transmission loss of the fiber strands 6, 6 does not increase. Hereinafter, working effects will be clarified by showing examples.

(Example) A bare optical fiber having an outer diameter of 125 μm was coated with an ultraviolet curable resin to obtain an optical fiber having an outer diameter of 200 μm. Eight such optical fiber wires were arranged in parallel and passed through a die to form a collective coating layer made of an ultraviolet-curable resin, thereby obtaining eight core fibers. At this time, the shape of the discharge port of the die was changed, and the coating thickness on both sides was changed in the range of 5 to 100 μm. Note that the coating thickness of the flat portion was fixed at 5 μm. Twenty of the tape core wires thus obtained are made of polyethylene and housed in a gutter-like container having an inner width of 3.0 mm and a depth of 5.0 mm, and the gutter is placed on a mandrel having an outer diameter of 100 cm. The container was wound twice in close contact winding such that one side wall of the container was in contact with the outer periphery of the mandrel, and the change in transmission loss of each fiber before and after winding was measured. Table 1 shows the results.

[0012]

[Table 1]

In Table 1, the "inner position" indicates an optical fiber positioned on the inside when wound around the mandrel among the optical fibers positioned on both sides of the tape core, and the "outer position" Similarly, the optical fiber strand located on the outer side is shown, and the “center position” indicates the fourth optical fiber strand from the optical fiber strand at the “inner position”. The transmission loss change was represented by a measured value at a wavelength of 1.55 μm in “dB / km”.

As is evident from the results in Table 1, when the coating thickness on both sides is 10 μm or more, it is possible to suppress an increase in transmission loss due to the side pressure of the optical fiber wires located on both sides.

[0015]

As described above, the optical cable of the present invention is
As the optical fiber tape core wire accommodated in the gutter-shaped container , a plurality of optical fiber wires having an outer diameter of 200 μm or less are arranged and integrated by a collective coating layer, and the thickness of both sides of the collective coating layer is reduced. The thickness was set to 10 to 30 μm , and the thickness was larger than the thickness of the flat portion . Therefore, the transmission loss of the optical fiber located on both sides of the optical fiber ribbon is, when the cabling, the optical fiber is hitting the side wall of the trough-shaped container, even under lateral pressure, increased Never do.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an optical fiber ribbon used for an optical cable according to the present invention.

FIG. 2 is a schematic sectional view showing an optical cable according to the present invention.

FIG. 3 is a cross-sectional view showing a gutter-shaped container according to the present invention and a core of an optical fiber tape accommodated therein.

FIG. 4 is a sectional view showing an optical fiber ribbon used for a conventional optical cable .

[Explanation of symbols]

2 ... gutter-shaped container, 6 ... optical fiber wire, 11 ... optical fiber tape core wire, 11a ... both side parts, 11b ... flat part,
12: Collective coating layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yutaka Kurosawa 1440, Mukurosaki, Sakura-shi, Chiba Fujikura Electric Wire Co., Ltd.Sakura Plant (72) Inventor Shinji Araki 1,440, Mukurosaki, Sakura-shi, Chiba Sakura Factory (72) Inventor Hiroyuki Sawano 1440 Mutsuzaki, Sakura City, Chiba Prefecture Inside the Sakura Plant, Fujikura Electric Cable Co., Ltd. (72) Inventor Shigeru Tomita 1-6-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-63-53507 (JP, A) JP-A-61-72212 (JP, A) JP-A-55-45087 (JP, A) Fully open 1979-170136 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) G02B 6/44 371 G02B 6/44 366 G02B 6/08

Claims (1)

(57) [Claims] An optical fiber having an outer diameter of 200 μm or less is arranged and united by a collective coating layer, and the thickness of both side portions of the collective coating layer is set to 10 to 30 μm and larger than the thickness of a flat portion. Optical fiber ribbon
A plurality of sheets are stacked and stored in a gutter-shaped container, and a plurality of
An optical cable characterized in that: