JPH11295572A - Optical fiber cord and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cord with excellent flexibility capable of being made multiple and useful as the one for indoor wiring by providing a reinforcing layer composed of high tensile fibers for surrounding a coated optical fiber and an outer jacket provided on the outer periphery of the reinforcing layer and twisting the plural coated optical fibers to SZ twist. SOLUTION: The plural, normally 3-12, coated optical fibers 11 of a structure for which coating is executed to optical fibers are SZ twisted with a prescribed inversion pitch, the high tensile fibers such as aramid fibers or carbon fibers, etc., are vertically attached on the outer side and the reinforcing layer 12 is formed. Also, on the outer periphery of the reinforcing layer 12, thermoplastic resin such as polyvinyl chloride resin or polyethylene resin is extruded and coated and the outer jacket 13 is provided. Then, by immediately performing a coating process after a twisting process, the twisted state of the coated fibers is fixed by the pressure of coating resin and the return is prevented without executing press winding by a tape as conventional manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-core optical fiber cord useful for indoor wiring of an optical fiber communication line and a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, an optical fiber cord or an optical fiber cable is used for indoor wiring of a communication line using an optical fiber according to the number of cores.

That is, when the number of cores is one or two,
For example, as shown in FIG. 3, a high tensile strength fiber 2 such as an aramid fiber or a carbon fiber is vertically attached to one (or two) optical fiber core wires 1 and a jacket such as a polyvinyl chloride resin is further placed thereon. 3 is used.
These have good flexibility and can be easily wired even in a narrow place.

On the other hand, when the number of cores is three or more, a so-called single-core cord in which the above-described single-core optical fiber cord is twisted around the outer periphery of the tension member and a jacket is provided on the outer periphery. A so-called layered optical fiber cable, in which a bundled optical fiber cable or optical fiber core wire is directly twisted on a tension member, the outside of which is covered with a cushioning material, and further covered with a jacket, is extruded around the outer periphery of the tension member. An optical fiber cable such as a so-called spacer type optical fiber cable in which a plurality of optical fiber cores are accommodated in a groove of a spacer is used. In some cases, a plurality of single-core or two-core optical fiber cords are wired.

[0005] However, the above-mentioned optical fiber cables are provided with a tension member and a presser winding because of problems in protection and manufacturing of the optical fiber, so that they are poor in flexibility and narrow as in an indoor space. There is a problem that the wiring work is difficult when the floor wiring with a curve is performed in a place. Also, workability was poor when a plurality of optical fiber cords were wired.

[0006]

As described above, the optical fiber cables used for indoor wiring having three or more cores of the optical fiber communication line are all provided with a tension member. Poorly flexible
There is a problem that wiring work is difficult. Further, even when a single-core or two-core optical fiber cord having good flexibility is used, a plurality of wires need to be wired, so that there is a problem that workability is poor. For this reason, there is a demand for an optical fiber cord that can be multi-cored with three or more cores and has excellent flexibility.

SUMMARY OF THE INVENTION The present invention has been made to meet such a demand, and an object of the present invention is to provide an optical fiber cord which is useful for indoor wiring, can be multi-core, and is excellent in flexibility. I do.

[0008]

According to the present invention, there is provided an optical fiber cord comprising a plurality of optical fiber cores and a high tensile strength fiber surrounding the optical fiber cores. And a sheath provided on the outer periphery of the reinforcing layer, and the plurality of optical fibers are twisted in SZ twist.

Here, it is preferable that the outer cover is provided immediately above the reinforcing layer.

The method for manufacturing an optical fiber cord according to the present invention comprises:
As described in claim 3, while a plurality of optical fiber cores are SZ-twisted, a high tensile strength fiber is longitudinally added to the outside thereof so as to cover the optical fiber core, and is heated and melted immediately above. It is characterized by extrusion coating of a thermoplastic resin.

In the optical fiber cord of the present invention, since the optical fiber is twisted SZ and the reinforcing layer is present outside the optical fiber, the tension applied at the time of wiring is limited by the reinforcing layer made of the high tensile strength fiber surrounding the optical fiber. And does not affect the optical fiber. Therefore, even if the number of cores is three or more, there is no need to dispose the tension member, and the flexibility can be improved.

When the jacket is provided directly above the reinforcing layer, the optical fiber core and the reinforcing layer are not restrained, so that the characteristics of the optical fiber are prevented from deteriorating due to impact. That is, in such a configuration, when the optical fiber cord receives an external impact, the optical fiber core wire and the reinforcing layer move and deform together with the jacket, and the impact force is dispersed. For this reason,
The impact force is not directly applied to the optical fiber core as it is, so that the transmission characteristics of the optical fiber are prevented from deteriorating. By the way, when the reinforcing layer is held down by the holding tape, the shapes of the reinforcing layer and the optical fiber core are maintained by the holding tape. There is no escape for the wire and the reinforcing layer, and a direct impact is applied to the core wire, which may degrade the characteristics of the optical fiber. According to the method for manufacturing an optical fiber cord of the present invention, it is possible to easily manufacture an optical fiber cord having excellent characteristics as described above.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross sectional view showing an example of the optical fiber cord of the present invention.

In FIG. 1, a plurality of optical fiber cores 11 having a structure in which a primary coating made of a silicone resin or the like and a secondary coating made of a nylon resin or the like are sequentially applied on a quartz optical fiber such as an SM type or a GI type are provided. SZ strands, usually 3 to 12 strands, are twisted at a predetermined reversal pitch, and a high tensile strength fiber such as aramid fiber or carbon fiber is longitudinally added to the outside thereof to form a reinforcing layer 12. A jacket 13 is provided on the outer periphery of the reinforcing layer 12 by extrusion-coating a thermoplastic resin such as a polyvinyl chloride resin or a polyethylene resin.
FIG. 2 shows the appearance of the optical fiber core wire 11 twisted with SZ.

This optical fiber cord is manufactured, for example, as follows.

While the plurality of optical fiber cores 11 are SZ-twisted, high tensile strength fibers are longitudinally added to the outside thereof so as to cover the optical fiber cores. A jacket 13 is formed by extrusion-coating a thermoplastic resin such as a polyvinyl chloride resin melted by heating. In this way, by performing the coating step immediately after the twisting step, the twisted state of the core wire is fixed by the pressure of the coating resin, and it is possible to prevent the return of the core wire without performing the press-winding by tape as in the related art. Can be.

The optical fiber cord thus obtained is excellent in flexibility because it is not provided with a tension member or a presser winding. In addition, the tension at the time of wiring is the reinforcing layer 1
2 and is not applied to the optical fiber core wire 11, so that the characteristics of the optical fiber are not degraded even if tension is applied. Further, since the presser winding is not applied, when an impact is received from the outside, the optical fiber core wire 11 and the reinforcing layer 12 are moved and deformed together with the jacket 13 and the impact force is dispersed. For this reason, the deterioration of the characteristics of the optical fiber core 11 due to the impact is prevented.

[0019]

Next, examples of the present invention will be specifically described.

EXAMPLE On a GI-type quartz glass optical fiber (core diameter 50 μm, clad outer diameter 125 μm), a primary coating made of silicone resin and a secondary coating made of nylon 12 having a finishing diameter of 900 μm were sequentially applied in order. Twisted 12 optical fibers are SZ twisted (reversal pitch 300mm, reversal angle 550
°) and aramid fiber (trade name Kevlar 49) as a high tensile strength fiber is introduced along the outside of the extruder and extruded with polyvinyl chloride resin to form an outer diameter of 6.5
mm optical fiber cord was manufactured. Aramid fibers were used in combination with fibers of different thicknesses (1140 denier 9
Book and 3 1140 deniers).

Table 1 shows the results of a characteristic evaluation test (according to JIS C 6821) performed on the obtained optical fiber cord.

[0022]

[Table 1] As is clear from Table 1, the optical fiber cord of the embodiment has various characteristics that can be sufficiently used for indoor wiring.

[0023]

As described above, according to the present invention,
Conventionally, the need for a tension member or presser winding required for three or more cores can be eliminated, so that an optical fiber cord with excellent flexibility can be obtained even with three or more cores. By using this, bent floor wiring and the like can be easily performed with good workability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an optical fiber cord according to the present invention.

FIG. 2 is a side view showing a twisted state of the optical fiber core of the optical fiber cord shown in FIG. 1;

FIG. 3 is a cross-sectional view showing an example of a conventional optical fiber cord.

[Explanation of symbols]

 11 optical fiber core wire 12 reinforcing layer 13 jacket

Claims (3)

[Claims] 1. A plurality of optical fiber cores twisted in SZ twist, a reinforcing layer made of high tensile strength fibers surrounding these optical fiber cores, and a jacket provided on the outer periphery of the reinforcing layer. An optical fiber cord comprising: 2. The optical fiber cord according to claim 1, wherein the jacket is provided immediately above the reinforcing layer. 3. While twisting a plurality of optical fiber cores with SZ, a high tensile strength fiber is longitudinally added to the outside of the optical fiber core so as to cover the optical fiber core, and a thermoplastic resin heated and melted immediately above the high tensile strength fiber. A method for producing an optical fiber cord, comprising extrusion coating.