JPH06331864A - 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 in a groove which has a tape housing space part having a square-shaped cross section is prevented. CONSTITUTION:With respect to this groove type optical cable, 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 groove 1 consists of two kinds of inner and outer groove materials, and the Young's modulus of the groove material on an inner layer side 1a is <=30Kgf/mm<2>, and that on an outer layer side 1b exceeds 30Kgf/mm<2>. Therefore, the stress generated between the groove 1 and the tape core 3 is effectively absorbed to the groove material on the inner layer side 1a, and the stress received on the side of the tape core 3 is minimized, and the optical cable is made superior in transmission characteristic and has a sufficient groove strength.

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 groove type optical cable having a structure in which a plurality of tape core wires are housed in a groove (square groove) having a square cross section and a plurality of these grooves are twisted around a central tension member is provided. Proposed. And, as a tape core wire used in this optical cable, in general,
Optical fiber strand (fiber outer diameter = 125 μm, MFD =
8.5-10.5 μm, λc = 1.1-1.36 μm,
(UV coating diameter = 150 to 220 μm) is arranged in parallel with 8 to 16 cores and 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. 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 having a large bending rigidity, 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 groove has an inner-outer two-layer structure to increase the Young's modulus of the outer-layer-side groove material to increase the inner-layer-side groove. On the other hand, it was found that the increase of the transmission loss of the tape core wire can be effectively suppressed by easily setting the Young's modulus of the inner layer side groove material in contact with the tape core wire to a specific value or less while reinforcing the It has arrived.

[0005]

The feature of the present invention resides in an optical cable in which a tape core wire is accommodated in a groove having a tape accommodation space portion having a rectangular cross section, wherein the groove is It consists of two kinds of inner and outer groove materials, and the Young's modulus of the inner layer side groove material is 30 Kgf / m.
m ² or less and the Young's modulus of the outer layer side groove material is 30
It is in a groove type optical cable exceeding Kgf / mm ² .

[0006]

In the present invention, since the Young's modulus of the inner side of the groove material is 30 Kgf / mm ² or less, the stress generated between the groove and the tape core wire is effectively absorbed by the groove material side. become. Therefore, the stress received on the tape core side is minimized. In addition, since the Young's modulus of the groove material on the outer layer side exceeds 30 Kgf / mm ² , it has a good reinforcing effect on the inner layer groove material, and it becomes possible to set a smaller Young's modulus of the inner layer groove material at the same time. Even if the Young's modulus setting of the groove material on the inner layer side is small, the groove as a whole has a sufficient strength.

[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 has a two-layer structure composed of two kinds of inner and outer groove materials. The Young's modulus of the groove material on the inner layer side 1a is 30 Kgf / mm ² or less, and the Young's modulus of the groove material on the outer layer side 1b is It is set to a value exceeding 30 Kgf / mm ² . Examples of the groove material on the inner layer side 1a include resins such as EVA, EEA, low density polyethylene and soft vinyl chloride resin, and examples of the groove material on the outer layer side 1b include high density polyethylene, PBT and polycarbonate. , And resins such as polyamide.

When a more specific shape of the square groove 1 is presented, for example, as shown in FIG. 2, the side surface thickness L ₁ is 0.8 mm (inner layer thickness L ₁₁ = 0.3 mm, outer layer thickness). L ₁₂ = 0.5 mm), bottom thickness L ₂ is 0.8 mm
(Inner layer thickness L ₁₁ = 0.3 mm, outer layer thickness L ₁₂ = 0.5 m
m), the inner width L ₃ is 3.5 mm, and the inner depth L ₄ is 2.8 mm.
4 of them on the outer circumference of the tension member 2 with a pitch of 50, for example.
It is twisted with 0 mm.

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 the present example, 10 sheets (books) are stored in the 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, as the material of the square groove 1, the Young's modulus of the inner layer side 1a is 30K.
Young's modulus of the outer layer side 1b is 30 kg at gf / mm ² or less
Since a resin having a value exceeding f / mm ² is used, even if stress such as rubbing or twisting occurs between the square groove 1 and the tape core wire 3, those stresses have a small Young's modulus. It is effectively absorbed by the groove material side of the inner layer side 1a. Therefore, the stress received on the tape core wire 3 side is minimized, and as a result, it is possible to effectively prevent deterioration of the transmission characteristics of the tape core wire 3.

On the other hand, the outer layer side 1 having a large Young's modulus
Since the groove material of b exhibits a reinforcing function for the inner layer side 1a, the Young's modulus of the inner layer side groove material can be made smaller, and the degree of freedom in setting the Young's modulus is increased, and the inner layer side groove material can be set. Even if the Young's modulus setting is small, the corner groove 1 does not lose its shape or stretches more than necessary, and the original holding function of the groove with respect to the internal tape core wire 3 is well achieved.

Incidentally, as the groove material of the inner layer side 1a, Young's modulus is different, 3 Kgf / mm ² , 5 Kgf / m
m ² , 10 Kgf / mm ² , 20 Kgf / mm ² , 30
Kgf / mm ² , 50 Kgf / mm ² , 100 Kgf /
While using the seven resin mm ^2, the Young's modulus as the groove material of the outer layer side 1b is prepared each groove with one resin of 150 kgf / mm ^2, each of these grooves, one of the above Examples A unit is created by accommodating 10 tape cores similar to the above, and four of these unitized grooves are arranged on the outer circumference of the tension member at a pitch of 500 m.
Prototypes of each optical cable were made by twisting at m. Then, the transmission loss (measurement light wavelength = 1.55 μm) of the tape core wire in each groove when the respective optical cables were wound around a conveying drum having a body diameter of 1 m was examined, and it was as shown in Table 1. Note that the maximum transmission loss in the table is that the transmission loss of the tape core wire used here is approximately 0.21d.
Since it is B / Km, the value added to this value (0.21+
α, α = loss due to cable formation).

[0014]

[Table 1]

As is apparent from Table 1, in the cable of the present invention in which the inner and outer layers of the square groove are made of two kinds of materials having different Young's moduli, the outer layer side groove material is a material having a large Young's modulus (150 Kgf / mm ² ). Using a material having a small Young's modulus (30 Kgf / m
It can be seen that the transmission loss is small in the case of using m ² or less).

Although the four grooves 1 are twisted around the outer circumference of the tension member 2 in the above embodiment, the groove type optical cable of the present invention is not limited to this, and the number of the grooves 1 is larger than that. In addition, the number 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 grooves 1 are twisted in a multi-stage structure around 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 gap between the four grooves 1 may be filled with an interposition, or a winding tape may be wound on the grooves 1 and then the cable sheath may be covered. It may be.

[0017]

As is apparent from the above description, according to the groove type optical cable of the present invention, the groove is made of two kinds of groove materials, the inner and outer kinds, and the Young's modulus of the inner layer side groove material is 30 Kgf / mm ² or less, In addition, since the Young's modulus of the outer layer side groove material exceeds 30 kgf / mm ² , the stress generated between the groove and the tape core wire is effectively absorbed by the inner layer side groove material side of the groove. . Therefore, the stress applied to 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. Also, since the Young's modulus of the groove material on the outer layer side exceeds 30 Kgf / mm ² , the strength of the groove itself is large, and an excellent optical cable can be obtained in which the original retaining function of the groove against the internal tape core wire is satisfactorily achieved. .

[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 1a Groove inner layer side 1b Groove outer layer side 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 in which a tape core wire is housed in a groove having a tape housing space portion having a rectangular cross section, wherein the groove is made of two kinds of groove materials inside and outside, and Young's modulus of the groove material on the inner layer side. Is 30 kg
A groove type optical cable having a Young's modulus of f / mm ² or less and an outer layer side groove material exceeding 30 kgf / mm ² .