JP2003131094A - Optical fiber unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber unit suppressing deterioration of the optical characteristic of optical fibers due to the presence of a rip cord. SOLUTION: In the optical fiber unit provided with a ripping cord 1 along coated optical fibers 2 and coating layers 3, 4 on the outer circumference of the coated optical fibers, the ripping cord 1 having a structure provided with a central material coated with the same ultraviolet curing resin as the coating of the coated optical fibers 2, is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber unit installed in a pipe installed in advance by gas pressure.

[0002]

2. Description of the Related Art Generally, an optical fiber unit laid by a gas pressure in a laid pipe has one or a plurality of single-core optical fibers or a plurality of optical fibers arranged in parallel. It has a structure in which a coating layer made of resin or the like is provided on the tape-shaped optical fiber core wire which is collectively coated. Therefore, it is necessary to remove the coating layer in order to expose the single-core optical fiber core wire or the tape-shaped optical fiber core wire (hereinafter simply referred to as the optical fiber core wire) when processing the end of the optical fiber unit. is there.

In order to easily remove the coating layer, an optical fiber unit having a structure in which a tear cord is provided along the optical fiber core and a coating layer formed by coating a resin on the outer periphery thereof is conventionally proposed. Has been done. In such an optical fiber unit with a tear string, by pulling the tear string in a direction away from the optical fiber unit from the end of the optical fiber unit and tearing the coating layer, the optical fiber core wire can be easily exposed. it can.

[0004]

However, the tearing string provided for tearing the conventional optical fiber unit has a surface property different from that of the optical fiber core wire (ultraviolet curable resin coating) arranged adjacently. Materials such as thermoplastic resins (olefin series, polyvinyl chloride, etc.) have been used as coating materials.

For this reason, when the surface property of the tear string loses uniformity, the optical characteristics of the adjacent optical fibers may be impaired, causing transmission loss of the optical fibers.

Therefore, an object of the present invention is to solve the above problems and to provide an optical fiber unit in which the deterioration of the optical characteristics of the optical fiber due to the presence of the tear cord is suppressed.

[0007]

In order to achieve the above object, the present invention is configured as follows.

According to a first aspect of the present invention, in a fiber optic unit having a tear cord along the optical fiber core and a coating layer on the outer periphery thereof, the tear cord covers the center material of the optical fiber core. It is characterized in that it has a structure coated with the same ultraviolet curable resin as described above.

According to the present invention, the string for tearing used when pulling out the inner optical fiber core wire from the optical fiber unit is coated with the ultraviolet curable resin so that the optical characteristics of the adjacent optical fibers can be improved. The deterioration can be suppressed.

The invention according to claim 2 is the optical fiber unit according to claim 1, characterized in that the center material of the tear cord is made of copper. By adopting copper as the central material of the tear string used for the optical fiber unit,
The effective tearing property of the optical fiber unit can be realized.

According to a third aspect of the present invention, in the optical fiber unit according to the first or second aspect, the outer diameter of the central material of the tear cord is 120 to 130 μm, preferably 125.
It is characterized in that it is μm. By setting the outer diameter of the central material of the tear cord to 125 μm (120 to 130 μm), for example, the tear characteristic of the optical fiber unit can be obtained.
Moreover, it is possible to suppress the deterioration of the optical characteristics of the adjacent optical fibers.

According to a fourth aspect of the present invention, in the optical fiber unit according to the first, second or third aspect, the outer diameter after coating the tear cord with an ultraviolet curable resin is 240 to 26.
An optical fiber unit having a thickness of 0 μm, preferably 250 μm. By setting the outer diameter of the ultraviolet curable resin that covers the tearing string used in the optical fiber unit after coating to, for example, 250 μm (240 to 260 μm), deterioration of optical characteristics of adjacent optical fibers is suppressed. You can

The invention as claimed in claim 5 is as follows.
Alternatively, in the optical fiber unit described in 4, the coating of the tear cord is a two-layer coating of the same ultraviolet curable resin as the coating of the optical fiber core wire. By coating the tearing string used in the optical fiber unit with the ultraviolet curable resin in two layers, it is possible to suppress the deterioration of the optical characteristics of the adjacent optical fibers.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiments.

FIG. 1 is a sectional view showing an embodiment of the optical fiber unit of the present invention. In the figure, 1 is a tear cord, 2
Is an optical fiber core wire, 3 is a collective coating layer, and 4 is a foam coating layer. In this embodiment, six optical fiber core wires 2 and 1 are used.
A tear string 1 of a book is used, which is twisted or bundled without twisting to form an inner core, and a collective coating layer (primary coating layer) 3 is coated thereon, and foamed polyethylene or the like is further formed thereon. The foam coating layer (secondary coating layer) 4 was applied.

In short, in the optical fiber unit shown in FIG. 1, the inner core is composed of a plurality of optical fiber core wires 2, one of which is provided with a tear cord, the collective coating layer 3 and the foam coating. The layer 4 is provided.

As a specific example of the optical fiber core wire 2,
An optical fiber core wire having an outer diameter of 0.25 mm and coated with an ultraviolet curable resin was used. The tear cord 1 has an outer diameter of 120 to 130 μm.
m (preferably 125 μm) copper core material,
A structure in which the same ultraviolet curable resin as the coating of the optical fiber core wire 2 was coated and the outer diameter thereof was 240 to 260 μm (preferably 250 μm) was used. The coating of the tear cord 1 is not limited to a single layer structure but may be a double layer structure.
In any case, the same ultraviolet curable resin as that for coating the optical fiber core is used to form a coating of one or two layers.

The number of optical fiber cores 2 to be focused here is
The number is not limited to six, and may be one or two or more.

The embodiment shown in FIG. 2 is an example in which one tearing string 1 is provided in an optical fiber unit having a structure in which a gap 7 is provided between the collective coating layer 3 and the inner core. Is a modified example thereof, in which the packing degree of the collective coating layer 3 is increased.

In the above embodiment, only the optical fiber core wire 2 is focused together with the tear cord 1, but the present invention is not limited to this form, and an intervening cord or a tension member may be focused together.

FIG. 4 shows an example of an optical fiber unit in which a tension member 5 is arranged at the center of an inner core, and five optical fiber core wires 2 and one tear cord 1 having the above structure are arranged around the tension member 5. Is. The number of the optical fiber core wires 2 arranged together with the tear cord 1 shown here is merely an example, and the number of the optical fiber core wires 2 arranged around the tension member 5 is, for example, 6, 7, or 8. Book, 10
The number of books, 12 books, etc. can be arbitrarily set.

FIG. 5 shows an example of the structure of an optical fiber unit having a plurality of tear cords 1. That is, a structure in which a plurality (here, 6) of optical fiber core wires 2 are arranged around the tension member 5, and a plurality of (here, 2) tear cords 1 are arranged together with this. Is. In FIG. 5, the tear cords 1 are arranged so that the optical fiber core wires 2 are divided into every three fibers, but the number and arrangement position of the tear cords 1 are merely examples, and the invention is applied to other combinations. It is also possible to do so.

FIG. 6 shows another embodiment of the optical fiber unit of the present invention, in which an optical fiber unit having a structure in which an optical tape fiber is provided as an optical fiber core wire in an inner core is provided with a tear cord having the above-mentioned configuration. This is an example of deploying 1. In the figure, 6 is a four-core optical fiber ribbon (optical fiber ribbon), and three optical fiber ribbons 6 are laminated and assembled by a collective coating layer 3 to form an aggregate. The body has a tear cord 1 along it
Together with the foam coating layer 4, the optical fiber unit of this example is constituted.

The number of optical fibers constituting the tape fiber 6 shown in the figure, the number of laminated layers, the laminating method, the number of the tear cords 1 and the disposition position are merely examples, and the invention is applied to other combinations and structures. It is possible to

[0025]

As described above, according to the present invention, the same cord for tearing used when pulling out the internal optical fiber core wire from the optical fiber unit is provided with the same ultraviolet curable resin as the coating of the optical fiber core wire. Since the one coated with is used, it is possible to suppress the deterioration of the optical characteristics of the optical fiber element wire adjacent thereto, and to suppress the deterioration of the optical characteristics of the entire optical fiber unit.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a modified example of the optical fiber unit of FIG.

FIG. 3 is a sectional view showing another modification of the optical fiber unit of FIG.

FIG. 4 is a cross-sectional view showing another embodiment of the optical fiber unit of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the optical fiber unit of the present invention.

FIG. 6 is a sectional view showing another embodiment of the optical fiber unit of the present invention.

[Explanation of symbols]

1 tear string 2 Optical fiber core 3 Collective coating layer 4 Foam coating layer 5 tension members 6 optical tape fiber 7 void

Claims (5)

[Claims] 1. An optical fiber unit having a tear cord along an optical fiber core and a coating layer on the outer periphery thereof, wherein the tear cord has a central material made of the same UV curable resin as that for coating the optical fiber core. An optical fiber unit comprising a coated structure. 2. The optical fiber unit according to claim 1, wherein a central material of the tear cord is copper. 3. The optical fiber unit according to claim 1 or 2, wherein the outer diameter of the central material of the tear cord is 120 to 130 μm.
m, preferably 125 μm. 4. The optical fiber unit according to claim 1, 2 or 3, wherein an outer diameter after coating the tear cord with an ultraviolet curable resin is 240 to 260 μm, preferably 250 μm. Fiber unit. 5. The optical fiber unit according to claim 1, 2, 3 or 4, wherein the coating of the tear cord is a two-layer coating of the same UV curable resin as the coating of the optical fiber core wire. Optical fiber unit.