JPH1020160A - Optical fiber unit for pneumatic feeding - Google Patents

Abstract

(57) [Problem] To remove an outer jacket of an optical fiber unit used for a pneumatic light transmission cable without applying a large external force. SOLUTION: A material that is soluble in water or alcohol, such as polyvinyl alcohol, carboxymethylcellulose, nitrocellulose, etc., is used as a material forming a jacket 4. It is desirable that the jacket 4 is further foamed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic optical fiber unit for use in an optical cable for pneumatic transmission, in which a jacket of the optical fiber unit can be easily removed.

[0002]

2. Description of the Related Art A pneumatic light transmission cable is made by gathering at least one long pipe made of polyethylene or the like having an outer diameter of about 6 mm and an inner diameter of about 4 mm. The optical fiber cable is laid in advance in a building or a canal, and if necessary, a multi-core optical fiber unit is pressure-fed into the pipe of the cable by pressurized air, and sent into an optical cable.

[0003] This system has an advantage that an optical fiber line can be easily added in a short time according to demand.
Fictitious types, such as installing cables between telephone poles, have also been developed.

Various types of pneumatic transmission optical fiber units (hereinafter abbreviated as optical units) used in the pneumatic transmission cable have been developed, but a plurality of optical fiber strands are twisted. The main component is a structure in which a combined assembly or an assembly in which a plurality of optical fiber tape cores are laminated is covered with nylon, and is further covered with a foam such as foamed polyethylene or foamed ultraviolet curable resin to form an outer jacket. It is.

[0005] In such terminal opening processing of the optical unit, the outer jacket is removed by a method of mechanically removing the outer jacket using a blade or the like. There is a danger of accidentally damaging the optical fiber of the aggregate that is present. In addition, when removing the jacket of the optical unit when there is a live optical fiber in the aggregate, the live optical fiber may be damaged for the same reason, and a communication error may occur. There is a risk of occurring.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make it possible to remove the jacket of an optical unit with little application of a mechanical external force, and to damage an optical fiber or an optical fiber ribbon. The point is not to give.

[0007]

This problem is solved by using a material that is soluble in water or alcohol as a material for forming the jacket. In addition, it is preferable that the outer cover is foamed because the air pumpability is improved and the solubility in water and alcohol is improved.

[0008]

FIG. 1 shows an example of an optical unit according to the present invention. In FIG. 1, reference numeral 1 denotes a four-core optical fiber ribbon. Three optical fiber ribbons 1 are laminated and assembled by an inner jacket 2 to form an aggregate 3, and the aggregate 3 is covered with an outer jacket 4 to form an optical unit of this example. The inner cover 2 is made of a flexible material such as an ultraviolet-curable resin having an extremely low Young's modulus of about 0.1 to 1 kg / mm ² , is maintained in an assembled state, and is easily removed by a slight external force. It has become.

The outer cover 4 is made of a material soluble in water or alcohol. Here, the alcohol refers to lower alcohols such as methanol, ethanol, and isopropanol, and includes those containing a small amount of water. Examples of water-soluble materials include polyvinyl alcohol, methylcellulose, carboxymethylcellulose, polyethylene glycol, and polypropylene glycol.Examples of alcohol-soluble materials include nitrocellulose, acetylcellulose, and styrene rubber. It is used as one kind or a mixture of two or more kinds. Further, a mixture of a material soluble in water and a material soluble in alcohol can be used.

The jacket 4 can be formed by a usual extrusion coating method since these materials are almost thermoplastic resins. The thickness of the jacket 4 is usually 0.5 to 3 mm
Degree. Further, the jacket 4 may be foamed.
In this case, the specific gravity of the entire optical unit is reduced, so that the air pumpability is improved, and at the same time, the permeability of water or alcohol is improved, so that the dissolution rate of the jacket 4 is preferably increased.

A method of adding a decomposable foaming agent such as an inorganic carbonate, an azo compound or a nitroso compound and extruding the foam is used for foaming the jacket 4, and the foaming ratio should be about 5 to 10 times. Is preferred. The finished outer diameter of such an optical unit is about 2 to 4 mm, but is not limited to this range.

FIG. 2 shows another example of the optical unit of the present invention. In this example, six ultraviolet curable resin-coated optical fiber wires 11 having an outer diameter of 250 mm and a tear string 12 having substantially the same diameter are used. Are twisted with each other to form an aggregate 3, which is covered with a jacket 4 made of a material soluble in water or alcohol.

In the optical unit having such a configuration,
Since the jacket 4 is formed from a material soluble in water or alcohol, the jacket 4 is swollen or dissolved by contacting the jacket 4 with water or alcohol when removing the jacket 4. It can be removed simply by applying a slight external force without using tools such as blades. Therefore, the jacket 4 can be removed without damaging the optical fiber 11 or the optical fiber ribbon 1.

In the first embodiment, since the ultraviolet-curable resin of the inner cover 3 that assembles the optical fiber ribbons 1 is a soft jelly having a very low Young's modulus, A slight force is enough to remove it. Therefore, the tapping process can be performed on the optical fiber ribbon 1 and the optical fiber 11 without damaging them by a slight external force.

Further, even in the case of intermediate rear branching in the case where a live optical fiber is present in the optical unit, the jacket can be easily removed without adversely affecting the live optical fiber. For this reason, for example, when there is a surplus empty line in the operating optical unit housed in the pneumatic transmission cable and a new demand occurs in the middle section where the optical unit is laid and wired, a new Without laying the light unit
It is possible to take measures to meet the demand by branching the surplus optical unit in the middle, and it is possible to perform the wiring laying process in a short time and at low cost.

Since the outer cover is made of a material soluble in water or alcohol, there is a concern about the reliability of the optical unit after the cable is laid in the air pressure transmission cable. Except when performing, the outer jacket is not essential for the optical unit in the pipe of the pneumatic cable, so if the optical unit with the most cores that can be pumped into the pipe is used as the optical unit, the optical unit Need not be pulled out of the pipe, and there is no operational problem.

[0017]

As described above, according to the optical unit of the present invention, the jacket can be easily removed by a small external force without using a blade or the like. For this reason, it is possible to perform terminal exit processing, intermediate branching, and the like without damaging the optical fiber in the optical unit, and it is possible to obtain an effect that a communication error is not caused by adversely affecting a live optical fiber. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an optical unit according to the present invention.

FIG. 2 is a sectional view showing another example of the optical unit of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical fiber tape core wire 3 ... Assembly 4 ... Jacket 11 ... Optical fiber strand

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Suehiro Miyamoto 1440, Musaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Plant

Claims (2)

[Claims] 1. An air pressure sending optical fiber unit in which an assembly in which one or more optical fibers are assembled is covered with a jacket, wherein the jacket is made of a material soluble in water or alcohol. Optical fiber unit for pneumatic feeding. 2. An optical fiber unit for pneumatic feeding, wherein the jacket is foamed.