JP3091991B2 - 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, and more particularly to an optical fiber cable having an improved mounting density and a multi-core cable having a smaller diameter.

[0002]

2. Description of the Related Art Conventional multi-core optical cables are most commonly of the multi-slot type shown in FIG. In the figure, reference numeral 12 denotes a slot. The optical fiber tape 1 is inserted into the spiral groove 14.
6 are stacked and housed, and a holding roll 18 is applied to form a slot type unit 20. The slot type unit 20 is twisted and assembled around the center tension member 22, and a sheath 24 is provided to form a multi-slot type cable 26.

In recent years, a U-groove type cable shown in FIG. 3 has been studied with the aim of further increasing the number of cores and increasing the density.
In the figure, reference numeral 28 denotes a U groove. The optical fiber tape 16 is stacked and stored in the U-groove type unit 30.
And The U-groove type unit 30 is twisted and assembled around the center tension member 32, and a sheath 34 is provided to form a U-groove type cable 36.

[0004] An H-groove type cable shown in FIG. 4 has also been proposed. FIG. 3A is a side view of the H groove 38, and FIG. H groove 3
Reference numeral 8 denotes an elongated rod-shaped main body 39 (generally having a circular cross section);
The two back-to-back grooves 40 are provided in a spiral shape, and the cross-sectional shape perpendicular to the longitudinal direction is substantially H-shaped.
The optical fiber tape 16 is stacked and housed in the groove 40 of the H-groove 38, and the press-winding 42 is applied to form an H-groove type unit 44 (c). The H-groove type unit 44 is assembled in a large twist around the center tension member 46, and a sheath 48 is provided to form an H-groove type cable 50 (d).

[0005]

For each of the above cables, for example, considering a 4000-core structure using a 16-core optical fiber tape having a width of 3.3 mm and a thickness of 0.25 mm, the outer diameter of the cable is as follows. <Cable structure><Cable outer diameter>-Multi-slot type (Fig. 2) 50mm-U-groove type (Fig. 3) 44mm-H-groove type (Fig. 4) 48mm As shown in the above table, the cable outer diameter is U-groove. The smallest type. This is most advantageous for achieving high density.

However, in this U-groove type cable,
The following points are issues: That is, when manufacturing this cable, a large number of U-grooves 28 and optical fiber tapes 16 must be assembled around the central tension member 32 at one time. The grooves of the U-groove 28 are straight and not spiral. U groove type unit 3 in advance
0 and manufacture it with the central tension member 32.
If twisting is performed on the upper layer, the tape in the outer layer receives a strong tensile stress due to the difference in the twisting diameter (helical diameter) between the inner layer and the outer layer of the tape in the U-groove 28, whereby the tape in the inner layer is caused to have Since transmission loss is likely to occur due to being strongly pressed against the bottom surface, the outer layer must be made longer, but it is impossible to store the tape in such a state. For this reason, the manufacturing and the assembly of the U-groove type unit 30 cannot be performed in separate processes.
Inevitably, the U-groove 2
8 and immediately after that the optical fiber tape 16 must be stored. Although the first layer is also difficult, the number of the U-grooves 28 is particularly large in the second layer. A very large number of U grooves 28 and optical fiber tapes 16 are congested in a narrow space. Therefore, the manufacturing equipment becomes complicated and the manufacturing operation becomes difficult, so that there is a problem that it is almost impossible to obtain a multi-core cable of a certain degree or more. An object of the present invention is to provide a high-density multi-core optical fiber cable that solves such a problem.

[0007]

Means for Solving the Problems As exemplified in FIG.
The cable structure is such that a layer of the H-groove type unit 70 is provided on the slot type unit 60.

The slot type unit 60 has a slot 62
The optical fiber tape 16 is stacked and stored in the spiral groove 64. 66 is a tension member, and 68 is a presser winding. This corresponds to the slot type unit 20 shown in FIG.
It has the same structure as. However, the number of grooves 64 is large. Also,
The H-groove type unit 70 has the same structure as the H-groove type unit 44 in FIG. 4 and has two back-to-back spiral grooves 76, 76 provided in an elongated rod-shaped main body 74 of an H-groove 72.
The optical fiber tape 16 is stacked and housed therein, and a holding roll 78 is provided.

The term "H-groove type unit 70" in the claims refers to the above-mentioned "H-groove in which an elongated rod-shaped main body is provided with two spiral grooves back to back, and an optical fiber tape is inserted in the groove. It means "stacked and stored."

The H-groove type unit 70 can be manufactured in a separate process in advance. This is twisted and assembled on the slot type unit 60, and the presser winding 80 and the sheath 82
To form an H groove + slot type cable 84.
Further, the H-groove type unit 70 can have two or more layers as needed.

[0011]

[Operation]

(1) When the cable structure is such that the layer of the H-groove type unit 70 is provided on the slot-type unit 60, the outer diameter of the cable can be smaller than that of the H-groove type two-layer structure as described later. (2) Since the H-groove type unit 70 has a spiral groove, only the spiral groove can be manufactured in advance and assembled later (the difference between the lengths of the inner tape and the outer tape in the groove 76 is not accumulated).

[0012]

[Example] In the same manner as above, 16 mm width 3.3 mm and 0.25 mm thick
In the case of a 4000 core structure using a core optical fiber tape, the outer diameter of the H groove + slot type cable of the present invention is:
45mm. The above data is described again for reference. <Cable structure><Cable outer diameter> ・ U-groove type 44mm ・ H-groove type 2 layers 48mm By this, the cable outer diameter is reduced compared to H-groove type 2 layers, and it is possible to achieve almost the same as U-groove type. I understand.

[0013]

According to the structure in which the layer of the H-groove type unit is provided on the slot type unit, the following effects are achieved. (1) As described above, the cable outer diameter can be reduced to the same extent as that of the U-groove type cable. (2) In addition, compared to the U-groove type cable, since there is no problem in manufacturing when multi-cores are used, the cable can be manufactured relatively easily. (3) Even if a large number of tapes with a thin coating layer and a high density are stored in order to further increase the density, the tape is divided and stored in two spiral grooves that are back to back, so that transmission loss is reduced. It is unlikely to occur. Therefore, a high-density multi-core cable can be easily obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an example of a conventional high-density optical cable.

FIG. 3 is an explanatory view of another example of a conventional high-density optical cable.

FIG. 4 is an explanatory view of still another example of the conventional high-density optical cable.

[Explanation of symbols]

 12, 62 slot 14, 40, 64, 76 groove 16 optical fiber tape 18, 42, 68, 78, 80 presser winding 20, 60 slot type unit 22, 32, 46 central tension member 24, 34, 48, 82 sheath 26 Multi slot type cable 28 U groove 30 U groove type unit 36 U groove type cable 38,72 H groove 39,74 Body 44,70 H groove type unit 50 H groove type cable 60 Slot type unit 66 Tension member 84 H groove + slot Type cable

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Suehiro Miyamoto 1440, Rokkazaki, Sakura City, Chiba Prefecture Fujikura Co., Ltd. Sakura Plant (72) Inventor Hideyuki Iwata 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation In-company (56) References JP-A-5-241055 (JP, A) JP-A-60-169607 (JP, U) JP-A-5-38613 (JP, U) (58) Fields investigated (Int. . ^7, DB name) G02B 6/44

Claims (1)

(57) [Claims] 1. A spiral groove is formed on a cylindrical surface.
Back-to-back provided on a rod-shaped body on a slot-type unit containing an optical fiber tape in the slot rod groove
An optical fiber cable, wherein a layer of an H-groove type unit accommodating an optical fiber tape is provided in a spiral groove .