KR20110012705A - Central loose tube double jacket optical fiber cable - Google Patents

Abstract

PURPOSE: A central loose tube double jacket optical fiber cable is provided to obtain stable optical property against temperature change. CONSTITUTION: A loose tube(23) surrounds at least one core wires. A tensile material(24) surrounds the loose tube. An internal coating(25) surrounds the tensile material. A bellows steel tape(26) surrounds an inner sheath. An external coating(27) surrounds the bellows steel tape.

Description

CENTRAL LOOSE TUBE DOUBLE JACKET OPTICAL FIBER CABLE}

The present invention relates to an optical fiber cable, and more particularly to a loose tube type optical fiber cable having reduced outer diameter and weight of the cable.

Optical fiber cables are getting more and more attention in the electric and electronic fields, particularly in the communication field, because they can transmit vast amounts of information faster than conventional coaxial cables in transmitting electric and electronic signals. However, the optical fiber used in such an optical fiber cable is an optical fiber having a fine diameter and is easily damaged by external shocks. Therefore, in order to use the optical fiber as a cable for signal transmission, the optical fiber must be protected from such external impacts. . In addition, in the process of connecting the optical fiber cables, the deformation of the shape is often inevitable, such as deflection due to gravity, embedding the optical fiber cable, or bending the cable, depending on the terrain, etc. installed, Self elasticity and flexibility are essential.

Therefore, the optical fiber cable should have sufficient strength to protect the optical fiber mounted therein and sufficient flexibility to bend the shape relatively freely for ease of installation of the optical fiber cable according to the terrain. . Materials and structures that have sufficient strength and flexibility have been conventionally proposed according to these needs.

In general, optical fiber cables are largely divided into a loose tube type and a ribbon slot type according to an optical fiber mounting structure. Among them, a loose tube optical fiber cable generally has a structure in which a plurality of optical fiber units in which as many fiber core wires as necessary in a plastic tube are mounted together with a jelly compound are longitudinally assembled around a tensile line located at the center of the cable.

On the other hand, Fig. 1 shows a cross section of a cable in the case of a low-core cable having 12 cores or less in a loose tube type optical fiber cable having the above-described general structure.

As shown in FIG. 1, the conventional low-core cable has a 12-core tube 1 in which the optical fibers are mounted around a steel center tension line 2 located at the center of the cable, and a circumferential direction of the steel center tension line 2. The remaining space forms a structure in which the interposition shim 3 is filled around the tension line in the center of the cable to maintain the circular shape of the cable. In addition, the tube 1 and the interposition shims 3 are bound by a tape 4 and a sheath 5 is laminated on the outer circumference of the tape 4.

Therefore, when the low-core cable is formed according to the conventional loose tube type optical fiber cable structure, there is a limit in reducing the outer diameter and the weight of the cable.

An object of the present invention for solving the above problems, by placing a loose tube surrounding the optical fiber core wire and the optical fiber core wire instead of the tensile wire in the center of the optical fiber cable, and to allow the tension material to surround the loose tube, thereby reducing the outer diameter and weight Provided is an optical fiber cable that is easy to install and handle.

Another object of the present invention is to provide a stable optical fiber cable with a small amount of light loss change even in a low temperature and high temperature installation environment by managing the high temperature shrinkage of the loose tube to 0.4% or less.

According to an exemplary embodiment of the present invention, an optical fiber cable includes optical fiber cores, a loose tube surrounding the optical fiber cores, a tension member surrounding the loose tube, an inner covering surrounding the tension member, and a corrugated steel surrounding the inner covering. And an outer sheath surrounding the tape and the corrugated steel tape.

In addition, according to another embodiment of the present invention, the loose tube includes a plurality of optical fiber groups, wherein each optical fiber group includes a plurality of optical fiber cores and a coating layer surrounding the optical fiber cores.

Further, according to the embodiments of the present invention, the length of the loose tube is characterized in that the length shrinkage of 0.4% or less after 1 hour at 80 ℃.

According to the present invention, in order to provide an optical fiber cable having an appropriate tensile strength to suit the purpose of the signal transmission cable, instead of arranging the tensile line in the center of the optical fiber cable, the optical fiber core wire and a loose tube surrounding the optical fiber core wire is arranged By forming the optical fiber cable in a structure in which the loose tube is surrounded by the tension member, the outer diameter and the weight of the cable are greatly reduced, thereby facilitating installation and handling, and by managing the high temperature shrinkage of the loose tube at 0.4% or less. Even in a low temperature and high temperature installation environment, there is an advantage of enabling a stable signal transmission because the amount of light loss change is small.

In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention.

Hereinafter, a fiber-optical cable according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of an optical fiber cable according to the first embodiment of the present invention.

As shown in FIG. 2, the optical fiber cable according to the present invention includes one or more optical fiber core wires 21, a loose tube 23 surrounding the core wires 21, and a tension member 24 surrounding the loose tube 23. ) And sheaths 25 and 27.

As shown in FIG. 2, unlike the conventional method, the optical fiber cable has a structure in which the loose tube 23 including the optical fiber core wire 21 is disposed at the center of the optical fiber cable. In other words, the optical fiber cable, the one or more optical fiber core wires 21 are disposed in the center of the optical fiber cable, forming the loose tube 23 surrounding the optical fiber core wires 21, and a tension member surrounding the loose tube ( 24 to form an inner sheath 25 surrounding the tension member 24, to form a corrugated steel tape 26 surrounding the inner sheath 25, and to form the corrugated steel tape 26. The enclosing outer sheath 27 is formed. Therefore, since the interposition for maintaining the optical fiber cable cross section is unnecessary, the optical fiber cable can be reduced in size and weight.

The optical fiber core wires 21 may be colored in different colors with ink cured by ultraviolet rays to facilitate identification of each core wire 21 at both ends of the optical fiber cable.

In addition, the loose tube 23 is required to have a low shrinkage rate at high temperature in order to suppress the deterioration of the optical transmission loss due to shrinkage that occurs when heat is applied. According to a preferred embodiment of the present invention, the length of the loose tube 23 should be 0.4% or less in length shrinkage after 1 hour at 80 ℃.

On the other hand, the tension member 24 is used in the optical fiber cables to maintain a sufficient tensile force, unlike the conventional structure for placing the tension line in the center of the optical fiber cable, according to embodiments of the present invention placed in the center of the optical fiber cable The loose tube 23 is formed in a structure in which the tension member 24 is surrounded. The tension member 24 may be formed of glass yarns or aramid yarns.

In addition, the inner sheath 25 surrounds the tension member 24, a corrugated steel tape 26 surrounds the inner sheath 25, and an outer sheath 27 surrounds the corrugated steel tape 26. The fiber optic cable is formed in a surrounding structure.

Further, materials of the inner coating 25 and the outer coating 27 may include low smoke zero halogen (LSZH), polyolefin (Polyolefin), Polymer compounds such as poly (Ethylene), polyurethane (PU) or polyvinyl chloride (PVC) may be used. Fabrication of the inner sheath 25 and the outer sheath 27 may be formed by an extrusion process. The outer sheath 27 may also have a ripcord adjacent to its inner wall for ease of stripping. In addition, the corrugated steel tape 26 is wrinkled to minimize the stress received by the optical fiber during compression, impact or bending of the optical fiber cable.

Table 1 below shows the result of comparing the characteristics of the optical fiber cable of the present invention having the configuration as shown in FIG. 2 and the conventional optical fiber cable having the configuration as shown in FIG.

Item Conventional fiber optic cable (12 cores) Fiber optic cable (12 cores) according to FIG. 2 Cable outer diameter 11.1 mm 9.0mm% (19% decrease) Cable weight 139㎏ / km 90㎏ / km (35% decrease) Compression characteristics 400㎏ / 10㎝ 500 kg / cm (25% increase) Bend diameter 145 mm 36㎜ (4 times better) Tube shrinkage
(80 ℃ one hour) 0.4% or less 1% or less

As shown in Table 1, the optical fiber cable according to the present invention has a 19% reduction in outer diameter and a 35% reduction in weight compared to the conventional optical fiber cable in terms of cost and a 4 times reduction in bending diameter. It can be seen that there are many advantages in terms of repair.

3 is a cross-sectional view of an optical fiber cable according to a second embodiment of the present invention.

As shown in FIG. 3, the optical fiber cable includes a loose tube 34 and a loose tube 34 each having a plurality of groups having a plurality of optical fiber cores 31 and a coating layer 32 surrounding the optical fibers. ), A tension member 35, corrugated steel tape 37, and inner and outer coatings 36 and 38.

As shown in FIG. 3, unlike the conventional method, the optical fiber cable has a structure in which the loose tube 34 including the optical fiber core wires 31 is disposed at the center of the optical fiber cable. That is, the optical fiber cable wraps a plurality of optical fiber groups composed of a plurality of optical fiber core wires 31 and a coating layer 32 per group with a loose tube 34 to be disposed at the center of the cable, and the loose tube 34 is a tension member. (35) surrounds, the tension member (35) surrounds the inner sheath (36), the inner sheath (36) surrounds the pleated steel tape (37), and the pleated steel tape (37) covers the outer sheath (38). ) Is formed in a surrounding structure. Therefore, the intervening core is unnecessary to keep the cross section of the optical fiber cable circular, thereby making it possible to reduce the size and weight of the optical fiber cable.

The optical fiber core wires 31 may be colored in different colors by ink cured by ultraviolet rays so as to be easily identified at both ends of the optical fiber cable, and the coating layer 32 surrounding the plurality of optical fiber core wires 31 may also be formed at both ends of the optical fiber cable. It can be colored in different colors for easy identification. The plurality of colored optical fiber core wires 31 are coated to form one optical fiber group, and the optical fiber group thus formed is wrapped with a loose tube 34.

In addition, the loose tube requires a low shrinkage rate at a high temperature in order to suppress deterioration of the optical transmission loss due to shrinkage that occurs when heat is applied. According to a preferred embodiment of the present invention, the length of the loose tube should be 0.4% or less in length shrinkage after 1 hour at 80 ℃.

In addition, the plurality of loose tubes may be aggregated in a helical twist or SZ twist to minimize stress transmitted to the optical fiber by bending the optical cable when the optical fiber cable is laid or the drum is wound.

On the other hand, the tension member 35 is used in the optical fiber cables to maintain a sufficient tensile force, unlike the conventional structure for placing the tension line in the center of the optical fiber cable, according to embodiments of the present invention placed in the center of the optical fiber cable The loose tube is formed in a structure in which the tension member 35 is surrounded. The tension member 35 may be made of glass yarn or aramid yarn.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims below, but also by those equivalent to the claims.

1 is a cross-sectional view of an optical fiber cable having a conventional tension line positioned at the center of the cable;

2 is a cross-sectional view of an optical fiber cable in which a fiber core is located at the center of a cable, the fiber core is surrounded by a loose tube, and the loose tube is surrounded by a tension member according to a first embodiment of the present invention;

FIG. 3 is a diagram illustrating an optical fiber having a plurality of optical fiber groups consisting of optical fiber cores in a center of a cable, surrounding the optical fiber groups with a loose tube, and surrounding the loose tube with a tension member according to a second preferred embodiment of the present invention. Section of the cable.

Claims (3)

A loose tube surrounding one or more optical fiber cores and the optical fiber cores; A tension member surrounding the loose tube; An inner sheath surrounding the tension member; Corrugated steel tape surrounding the inner sheath; and And an outer sheath surrounding the corrugated steel tape. The method of claim 1, The loose tube surrounds a plurality of optical fiber groups, each optical fiber group including a plurality of optical fiber cores and a coating layer surrounding the optical fiber cores. The method according to claim 1 or 2, The loose tube is an optical fiber cable, characterized in that the length shrinkage is 0.4% or less after 1 hour at 80 ℃.

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