JPH06331863A - Groove type optical cable - Google Patents

Abstract

PURPOSE:To provide the groove type optical cable where the degradation in transmission characteristic of a tape core housed on a groove which has a tape storage space part having a square-shaped cross section is prevented. CONSTITUTION:This groove type optical cable is constituted so that a tape core 3 is housed in a groove 1 which has the tape housing space part having a square-shaped cross section, and the Young's modulus of the groove material is <=30kgf/mm<2>. Since the Young's modulus of the groove material is <=30kgf/ mm<2>, the stress generated between the groove 1 and the tape core 3 is effectively absorbed on the groove material side, and the stress received on the side of the tape core 3 is minimized. As the result, the degradation in transmission characteristic of the tape core 3 is effectively suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a groove type optical cable for preventing deterioration of transmission characteristics of a tape core wire housed in a groove having a rectangular cross section.

[0002]

2. Description of the Related Art Conventionally, as an optical cable capable of storing a tape core wire at a high density, a cable having a plurality of grooves formed in a longitudinal direction of a long rod and the tape core wire being housed in the groove Is used. However, this conventional optical cable has a drawback in that when it is bent, the tape core wire receives lateral pressure and transmission loss increases. Therefore, in order to improve this drawback, a plurality of tape core wires are housed in a groove having a square cross section (corner groove), and a plurality of the corner grooves are twisted around a central tension member to form a groove type optical cable. Is proposed. And, as the tape core wire used in this optical cable, generally, an optical fiber element wire (fiber outer diameter = 125 μm, MF
D = 8.5 to 10.5 μm, λc = 1.1-1.36 μ
m, UV coating diameter = 150 to 220 μm) are arranged side by side in 8 to 16 cores, and these are integrated with a UV curable resin.

[0003]

However, even in the case of the optical cable having the above structure, the tape core wire which comes into contact with the inner wall surface of the square groove when wound around the transport drum after manufacturing or bent during installation is also considered. There is a problem that the transmission loss of the optical fiber increases at both ends. It is considered that the reason why the transmission loss increases on both end sides of the tape core wire is that when the tape core wire is bent in the edge direction where the bending rigidity is large, a large stress is applied to the core wires on both end sides.

Therefore, the inventors of the present invention have made various studies in order to solve the above-mentioned problems. As a result, the Young's modulus of the groove material is set to a specific value or less to reduce the transmission loss of the tape core wire. The inventors have found that the increase can be effectively suppressed, and arrived at the present invention.

[0005]

The feature of the present invention resides in an optical cable in which a tape core wire is housed in a groove having a tape housing space portion having a rectangular cross section, and the groove material is the groove material. Young's modulus of 30 Kgf / m
It is in a groove type optical cable with m ² or less.

[0006]

In the present invention, the Young's modulus of the groove material is 3
Since it is 0 Kgf / mm ² or less, the stress generated between the groove and the tape core wire is effectively absorbed by the groove material side. Therefore, the stress received on the tape core side is minimized.

[0007]

1 shows an embodiment of a groove type optical cable according to the present invention, and FIG. 2 shows a groove used in the optical cable. In these drawings, 1 is a groove (square groove) having a tape storage space portion having a square cross-section, which is twisted around the outer periphery of the tension member 2, and 3 is a plurality of tapes stored in the square groove 1. The core wires 4 are cable sheaths coated on the outside of the square groove 1.

The square groove 1 is made of resin, and its Young's modulus is set to 30 Kgf / mm ² or less. The setting of the Young's modulus may be adjusted by selecting the resin used. Then, examples of resins satisfying such characteristics include low density polyethylene, EVA, EEA, and soft vinyl chloride resin. When a more specific shape of the corner groove 1 is presented, for example, as shown in FIG.
The side surface thickness L ₁ is 1 mm, the bottom surface thickness L ₂ is 1 mm, the inner width L ₃ is 3.5 mm, and the inner depth L ₄ is 2.8 mm.
The four square grooves 1 thus formed are twisted around the outer circumference of the tension member 2 at a pitch of 500 mm, for example.

As the above-mentioned tape core wire 3, for example, an SM type small-diameter optical fiber element wire having an outer diameter of 180 μm (fiber outer diameter = 125 μm, MFD = 8.5) having the same structure as the conventional one.
10.5 μm, λc = 1.1 to 1.36 μm, UV coating diameter = 150 to 220 μm) are arranged in parallel, and 16 cores are UV-coated.
As shown in FIG. 2, the width L ₅ is 3.0 mm and the thickness L ₆ is 0.2 m, using the tape core wire integrated with the cured resin.
In this example, 10 sheets (books) are stored in the square groove 1. Then, as the UV curable resin of the tape core wire 3 used here, for example, urethane acrylate resin, epoxy acrylate resin or the like is used.

As described above, in the optical cable of the present invention, the Young's modulus is 30 Kgf / mm ² as the material of the square groove 1.
The following resins are used, and since the coating resin on the side of the tape core wire 3 is a urethane acrylate-based or epoxy acrylate-based UV curable resin that is less likely to be deformed than the groove material, when the cable is bent Even if a large compressive stress locally occurs between the groove 1 and the tape core wire 3, those stresses are effectively absorbed by the groove material side having a small Young's modulus. Therefore, the tape core wire 3
The stress on the side is minimized, and as a result,
It is possible to effectively prevent deterioration of the transmission characteristics of the tape core wire 3.

Incidentally, the Young's modulus is different, 3 Kgf / mm
^{2, 5Kgf / mm 2, 10Kgf} / mm 2, 20Kg
f / mm ² , 30 Kgf / mm ² , 50 Kgf / m
Various (7) square grooves of m ² and 100 Kgf / mm ² were prepared, and 10 tape cores similar to those of the above-mentioned embodiment were housed in these square grooves to prepare a unit. 4 unitized square grooves were twisted around the outer periphery of the tension member at a pitch of 500 mm, and respective optical cables were produced as prototypes. Then, when the respective optical cables are wound on a conveying drum having a body diameter of 1 m, the transmission loss of the tape core wire in each square groove (measurement light wavelength = 1.55 μm)
The results are shown in Table 1. The maximum transmission loss in the table is about 0.21 dB / Km because the transmission loss of the tape core wire used here is approximately 0.21 dB / Km.
It is shown as a value added to this value (0.21 + α, α = loss due to cable formation).

[0012]

[Table 1]

As is clear from Table 1, when the Young's modulus of the square groove material is 30 Kgf / mm ² or less,
It can be seen that the transmission loss is large when the square groove made of a material having a size exceeding 30 Kgf / mm ² is used, while the transmission loss is small.

In the above embodiment, the four grooves 1 are twisted around the outer circumference of the tension member 2. However, the groove type optical cable of the present invention is not limited to this, and the square groove 1 is formed from this. At most, it may be small, or a single groove type optical cable in which the tape core wire 3 is simply housed in one groove 1 may be used. further,
A high-density optical cable in which the square groove 1 is twisted in a multi-stage structure on the outer circumference of the tension member 3 may be used. Further, the cable structure is not limited to the above-mentioned embodiment, and the interstices between the four square grooves 1 are filled with interpositions, or the winding tape is wound on the square grooves 1, and then the cable sheath is covered. It may be one.

[0015]

As is clear from the above description, according to the groove type optical cable of the present invention, since the material having the Young's modulus of 30 Kgf / mm ² or less is used as the groove material, it is wound on the drum after the cable is manufactured. Or, even if the edge part of the optical fiber tape core wire housed in the groove is strongly pressed against the groove when it is bent during installation, the groove itself effectively absorbs the stress. Therefore, the stress on the tape core side is minimized, and as a result, an excellent optical cable in which the deterioration of the transmission characteristics of the tape core is effectively prevented can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of a groove type optical cable according to the present invention.

FIG. 2 is a vertical sectional view showing a groove used in the optical cable of FIG.

[Explanation of symbols]

 1 groove 2 tension member 3 tape core wire 4 cable sheath

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichiro Watanabe 1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Co., Ltd.Sakura Factory (72) Inventor Shin Saito 1440, Rokuzaki, Sakura City, Chiba Prefecture Fujikura Sakura Factory, Ltd. ( 72) Inventor Suehiro Miyamoto 1440 Rokuzaki, Sakura City, Chiba Fujikura Co., Ltd. Sakura Factory (72) Inventor Shigeru Tomita 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. An optical cable having a tape core wire accommodated in a groove having a tape accommodation space portion having a rectangular cross section, wherein the Young's modulus of the groove material is 30 kg.
A groove type optical cable characterized in that it is f / mm ² or less.