JPH07234346A - Optical cable - Google Patents

Abstract

PURPOSE:To provide an optical cable which is twisted with single-groove units around a central body and is capable of maintaining stable twists. CONSTITUTION:Spacers 2 are formed with grooves which are twisted in a left direction. Plural sheets of coated fiber ribbons 1 which are laminated are twisted in the same direction so as to synchronize with the twists of the grooves and are housed into these grooves. These fibers are then subjected to retaining winding, by which the single groove units 3 are formed. A tension body 4 is positioned at the center of this optical cable and the single groove units 3 are twisted around the circumference thereof, by which the optical cable is formed. The twisting direction is a right-hand twist reverse from the twist direction of the single groove units 3 at the time of twisting. As a result, the stable twists are maintained without untwisting of the regular spirals of the single groove units 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a high-density optical cable for realizing a multi-core optical cable with a high storage density.

[0002]

2. Description of the Related Art The structure of an optical cable that accommodates 1000 optical fibers, which has the largest number of mounted cores among the multi-core optical cables currently in practical use, is described in, for example, M.K. Kawase
et. al. "Loop Network Con
configuration ForSubscriber
Loops and Single-Mode Opt
iCal Fiber Ribbon Cable T
technologies Sustainable For
Mid-Span Access ", 37th IWC
S, pp. 141-149, '88 are shown in FIG. 8 (b).

Further, as an example of an optical cable for realizing a high-density and high-mounting optical cable, Japanese Unexamined Patent Publication No. 4-355418 is cited, and development is proceeding so that stable transmission characteristics can be obtained.

However, an optical cable (hereinafter, referred to as a one-groove unit) including a unit having one groove as described in Japanese Patent Laid-Open No. 4-355418 (hereinafter, referred to as one-groove unit).
It is called a single groove type optical cable. ), The spacer that stores the tape core wire has a shape similar to the "U" shape of katakana,
Considering the second moment of area, bending around the A axis is apt to occur among the two axes of the A axis and the B axis in the spacer 2 of FIG.

Therefore, when a part of the one-groove unit is bent, it cannot be bent in a uniform state, and the spacer is stable when the opening of the spacer faces the outside or inside of the bend, and the one-groove unit has a trigonometric function. The twist of the one-groove unit that regularly drew a spiral is disturbed.

Such a phenomenon is caused, for example, by the above-mentioned 100.
This is a characteristic defect of the single-groove unit because it is unlikely to occur with a spacer that is almost symmetrical to the left and right like a 0-core cable. Also,
This phenomenon occurs not only in the single groove unit alone, but also in the case where the single groove unit is twisted around the central body to form the core of the single groove type cable, and should be maintained by drawing a normal spiral. Affect the mechanical and transmission characteristics of the unit.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and in an optical cable in which one groove unit is twisted around a central body, an optical cable capable of maintaining a stable twist. It is intended to provide.

[0008]

DISCLOSURE OF THE INVENTION The present invention is centered on a one-groove unit in which a tape core wire laminated in a groove of a rod-shaped body having a twisted groove is twisted and housed in the same direction so as to synchronize with the groove In an optical cable formed by twisting spirally around the body, the twisting direction of the one groove unit is opposite to the twisting direction of the groove of the rod-shaped body in the one groove unit to be twisted together. .

It is also characterized in that the one groove unit is twisted into a plurality of layers and adjacent layers are twisted in opposite directions.

[0010]

The groove of the one groove unit is formed by twisting, and the tape core wire laminated on the groove is twisted and housed in the same direction so as to be synchronized with the twist of the groove. The rod-shaped groove is deeper than the center and has only one groove. A plurality of one-groove unit units are twisted around the central body, and the one-groove unit is bent with the direction of the center of the central body being the inside of bending.

FIG. 3 is an explanatory view showing the relationship between the twisting direction and the twisting direction of the one groove unit. In the figure, 1 is a tape core wire, 2 is a spacer, 3 is a single groove unit, and 6 is a central body. FIG. 3A shows a case where the twisting direction and the twisting direction of the one groove unit 3 are the same. In this example, the one groove unit 3 is twisted to the left, and the one groove unit 3 is twisted to the left. In this case, the cycle in which the single groove unit 3 rotates around the central body 6 which is the inside of the bending becomes long. For example, the twist pitch of the one groove unit 3 is 500 m.
m, and the twisting pitch is 800 mm, the one-groove unit 3 goes around the central body 6 by 1333 mm. When the opening of the spacer 2 is directed to the outside or the inside of the central body 6 over such a long section, the spacer 2 is bent in a direction in which the spacer 2 is easily bent and twisted together, so that the one-groove unit 3 is formed.
The regular spiral of is disturbed.

FIG. 3B shows the case where the twisting direction and the twisting direction of the one groove unit 3 are opposite to each other. In this example, the one groove unit 3 is twisted to the left and the one groove unit 3 is twisted to the right. In this case, the one groove unit 3 goes around the central body 6 in a short cycle. Under the same assumption as in the previous example, even if the one-groove unit 3 has a twist pitch of 500 mm and a twisting pitch of 800 mm, the one-groove unit 3 makes one turn around the central body 6 by about 307 mm by reversing the twisting direction. To do. In this way, when the bendability of the slot 2 changes in a short cycle of a half pitch of 154 mm, the regular spiral of the original one-groove unit 3 can be maintained without twisting back.

Considering the condition where the optical cable is wound on the drum and there is a section that requires bending in the construction section, the tape core wire moves smoothly inside and outside the bending, and the line length difference occurs. In order to alleviate this, the twisting pitch cannot be unintentionally increased, and it is necessary to confirm it experimentally.

[0014]

1 is a view for explaining a first embodiment of an optical cable according to the present invention. FIG. 1 (A) is a sectional view and FIG.
(B) is a perspective view of the one groove unit. In the figure, 1 is a tape core wire, 2 is a spacer, 3 is a one-groove unit, 4 is a strength member, and 5 is a sheath. In the rod-shaped spacer 2, a groove is formed to a position deeper than the center, and the twist direction of the groove is, for example, the left direction. In this groove, an ultraviolet curable resin (U
A single-mode type optical fiber coated with V resin) is formed by laminating a plurality of strip-shaped tape core wires arranged in a horizontal row and twisted in the same direction in synchronization with the twist of the groove. On this, a one-groove unit 3 is created by pressing and winding with a polyester tape. The strength member 4 is located at the center of the optical cable. Strength member 4
Is a multiple steel wire twisted together, resin coating around it,
For example, it is formed by coating low density polyester. The single groove unit 3 was twisted around the strength member 4. When twisting, the twisting direction is opposite to the twisting direction of the groove of the one groove unit 3, for example, right twisting. Of course, the twisting direction of the groove and the twisting direction of the one groove unit may be opposite to the above-described examples.

A prototype example of the embodiment shown in FIG. 1 will be described. Single-mode optical fibers coated with UV resin are arranged in a row, and 10 strips of ribbon tape with a width of 3 mm and a thickness of 0.22 mm are twisted and stored in a plastic spacer with a diameter of 6.2 mm, and then polyester is used. A one-groove unit was created by applying pressure winding with tape. The twisting direction was left and the pitch was 500 mm. As the tensile strength member, a low-density polyester was coated around a steel stranded wire formed by twisting seven steel wires having a diameter of 2 mm to obtain a tensile strength member having a diameter of 13.6 mm, and one groove unit was twisted around this. At the time of twisting, we made a left-hand twist and a right-hand twist that had the same twist direction as the unit twist direction. Prototype length is 70 each
It is 0m.

The results of the trial production are shown in FIG. Wavelength 1.55μ
The loss with respect to the light of m was measured, and the number of locations where the twist of the one-groove unit was defective was counted. In an optical cable in which the twisting direction is the same as the twisting direction of the one-groove unit, the helix of the one-groove unit is untwisted and a defective section is partially generated, resulting in significant deterioration in transmission characteristics. However, it can be seen that when the twisting direction is the reverse twisting with respect to the twisting direction of the one-groove unit, no defective portion is generated and the transmission characteristic is good.

However, even with the optical cables twisted in the opposite directions in this way, if the twisted pitch is 1500 mm, the maximum loss exceeds 0.1 dB / km when the drum is wound, and the twisted pitch may be too long. I understand.
This pitch depends on the friction between the core wire of the tape and the spacer, and it is good to confirm it experimentally. From the prototype example,
The result was that the twisting pitch was less than 1500 mm, but when the safety factor was doubled and the frictional force was doubled, the friction was proportional to the friction coefficient and the pitch (target length)
Since it is exponentially proportional to the length of 1,500 × ln2 = 1040 mm, the safe design value is a pitch of 1000 mm or less.

FIG. 5 is a sectional view for explaining a second embodiment of the optical cable of the present invention. In the figure, the same parts as those in FIG. In this embodiment, the one-groove unit 3 is twisted into two layers around the tensile strength member 4, and the sheath 5 is provided thereon. Strength member 4
As for the first layer in contact with, the twisting direction of the one groove unit 3 was set to the left direction and the twisting direction was set to the right direction, as in the first embodiment. The twisting direction and the twisting direction of the second layer may be the same as the first layer, but in this embodiment, the twisting direction of the one groove unit 3 of the second layer is the right direction and the twisting direction is the left direction. . This makes it easier to twist during production, and the twist is more stable.

[0019]

As is apparent from the above description, according to the present invention, the one groove unit can be cabled while maintaining good unit characteristics by twisting the one groove unit in the direction opposite to the twisting direction. There is an effect.

[Brief description of drawings]

1A and 1B are views for explaining a first embodiment of an optical cable of the present invention, FIG. 1A is a sectional view, and FIG. 1B is a perspective view of a single groove unit.

FIG. 2 is an explanatory diagram of a spacer.

FIG. 3 is an explanatory diagram showing a relationship between a twisting direction and a twisting direction of the one groove unit.

FIG. 4 is an explanatory diagram of experimental results of a prototype example.

FIG. 5 is a sectional view for explaining a second embodiment of the optical cable of the present invention.

[Explanation of symbols]

 1 Tape core wire 2 Spacer 3 One groove unit 4 Strength element 5 Sheath

Front page continuation (72) Inventor Shigeru Tanaka 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Shigeru Tomita 1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Nihon Telegraph Phone Co., Ltd.

Claims (2)

[Claims] 1. A one-groove unit, which is housed by twisting in the same direction so that a tape core wire laminated in a groove of a rod-shaped body having a twisted groove is synchronized with the groove, is twisted spirally around a central body. In the optical cable formed together, the twisting direction of the one groove unit is opposite to the twisting direction of the groove of the rod-shaped body in the one groove unit to be twisted. 2. The optical cable according to claim 1, wherein the one groove unit is twisted into a plurality of layers, and adjacent layers are twisted in opposite directions.