JP3349643B2 - Sealing structure for optical fiber tape cord branch and method of forming the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing structure for a branch portion of an optical fiber tape cord and a method of forming the same.

[0002]

2. Description of the Related Art An optical fiber tape cord constituting an optical fiber cable used in an optical communication system is used for connection between optical fiber cables or connection to other devices.
As shown in FIG. 2, the outer sheath 2 of the optical fiber tape cord 1
Then, the tensile strength fiber 3 is peeled off to expose the inner optical fiber core wire 4, each exposed optical fiber core wire 4 is inserted into the protective tube 5, and further surrounded by the same tensile strength fiber 3 as the optical fiber tape cord 1. The outer periphery is covered with an outer skin 6 to form a reinforcing cord 7, and the optical fiber core 4, the tensile strength fiber 3, and the protective tube 5 are exposed and branched (hereinafter referred to as a branch A). ) Is accommodated in a protective case 8, and the inside of the protective case 8 is filled with a resin 9 and sealed. The joint between the optical fiber tape cord 1 and the reinforcing cord 7 and the protective case 8 is fixed in a sealed state with an adhesive 10. An optical connector or the like (not shown) is connected to the end of the reinforcing cord 7 so that connection with other devices or the like is possible.

[0003]

It is desirable that the resin 9 used for sealing the branch portion A spreads over the protective case 8 without any gap from the viewpoint of sealing performance and is solidified.
However, at the branch portion A, the interval between the optical fiber cores 4 is narrow, and in order to spread the resin 9 to the gap, the resin 9 needs to have a somewhat high fluidity, that is, a low viscosity. Therefore, the viscosity at room temperature is 300
Generally, a low-viscosity epoxy resin of about 0 to 5000 cps is used. By the way, the optical fiber core 3
Are surrounded by the tensile strength fiber 3 to form the reinforcing cord 7, and a part thereof is exposed at the branch portion A. Also, in the optical fiber tape cord 1, the optical fiber core 4
In general, the tensile strength fiber 3 is exposed from the end 11 of the optical fiber tape cord 1 at the branch portion A, with the periphery thereof being surrounded by the tensile strength fiber 3 and covered with the outer skin 2. However, the tensile strength fiber 3 is generally an aramid fiber typified by Kepler fiber (trade name; manufactured by DuPont). When the affinity is high, and especially when the viscosity of the resin 9 is low, the resin 9 easily penetrates the optical fiber tape cord 1 and the reinforcing cord 7 through the tensile strength fiber 3.
As a result, the sealing resin 9 becomes the optical fiber tape cord 1
Hardened inside the reinforcing cord 7 and the optical fiber 4
And reduce the light transmission characteristics. In addition, bending resistance and impact resistance are also affected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sealing structure for a branch portion of an optical fiber tape cord, which ensures sealing with a resin and prevents the resin for sealing from penetrating into an optical fiber tape cord and a reinforcing cord. It is to provide a method for forming the same.

[0005]

The above object is achieved by the following sealing structure and a method of forming the sealing structure according to the present invention. (1) Optical fiber tape cord and the optical fiber tape
Holds multiple optical fibers at the end of the cord.
Protective tube, tensile strength fiber and outer skin
A sealing portion for sealing the branch portion between the reinforcing cord and the reinforcing cord in a protective case, wherein the circumference of the branch portion is 1 mm at room temperature.
It sealed with a cured product of the first resin having a viscosity of 5000～20000Cps, the first addition in protective case
The area other than the resin-sealed part is 3000-5 at room temperature.
A sealing structure for a branch portion of an optical fiber tape cord, which is sealed with a cured product of a second resin having a viscosity of 000 cps. (2) Optical fiber tape cord and the optical fiber tape
Holds multiple optical fibers at the end of the cord.
Protective tube, tensile strength fiber and outer skin
And sealing the branch between the reinforcing cord and the reinforcing cord in a protective case.
After curing and sealing with a first resin having a viscosity of 00 to 20,000 cps, the inside of the protective case including the sealing portion of the first resin is filled with a second resin having a viscosity of 3000 to 5000 cps at room temperature. And forming a sealing structure for the optical fiber tape cord branch portion.

According to the present invention, and the sealing with two kinds of resins of high viscosity and low viscosity, in which the periphery of the high affinity tensile strength fiber with sealing resin using a high-viscosity resin sealing By stopping, the resin is prevented from penetrating the fiber optic tape cord or the reinforcing cord through the tensile strength fiber and having a low viscosity inside the protective case including the outer region of the sealing portion with the high-viscosity resin. Filling with (fluid) resin, the resin spreads all over the inside of the protective case,
Good resin sealing can be realized.

[0007]

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The structure of the optical fiber tape branch portion itself to be sealed by the present invention is not particularly limited, and any structure that has been conventionally proposed and put into practical use as this type of branch portion can be used. Needless to say, the structure of the branch portion A shown in FIG. 2 is also within the target range. That is, in the present invention, the branch portion generally indicates a portion where the optical fiber 4, the protective tube 5, the tensile strength fiber 3, and the like are exposed between the optical fiber tape cord 1 and the reinforcing cord 7.

As shown in FIG. 1, the branch portion sealing structure of the present invention surrounds the branch portion A at a room temperature of 15,000 to 20,000.
While sealing with the first resin 12 having a viscosity of cps, the entire interior of the protective case 8 including the branch portion A is made of a second resin having a viscosity of 3000 to 5000 cps at room temperature.
It is characterized by being filled with the resin 13 and sealed. First
The higher the viscosity of the resin 12, the higher the optical fiber tape 1
However, the permeability to the reinforcing cord 7 is low, but on the other hand, the fluidity is low, so that the resin does not enter the gaps between the optical fiber core wires 4 and becomes hollow after curing, which is not preferable. In the present invention, it has been found that the viscosity having low permeability to the optical fiber tape cord 1 and the reinforcing cord 7 and suitable fluidity is 15,000 to 20,000 cps at room temperature. On the other hand, the viscosity of the second resin 13 is within the range of the viscosity of the resin conventionally used for this type of sealing structure. As the type of the first and second resins 12 and 13, an epoxy resin can be suitably used as in the conventional case.

At the time of sealing, the first resin 12 is applied by, for example, a brush and cured. At the time of application, if the fluidity is insufficient and the resin 12 does not sufficiently enter the gap between the optical fiber cores 4 due to a low ambient temperature or the like, the fluidity of the resin 2 is increased by heating. You may. The sealing with the second resin 13 is performed after the first resin 12 is cured according to a conventional method.
Filling and curing so as to spread over the entire interior of the device.

Since the resin that comes into contact with the tensile strength fiber 3 is the high-viscosity (low-flowability) resin 12 in the branch portion A sealed as described above, the optical fiber tape cord 1 and the The permeation of the resin into the reinforcing cord 7 is substantially eliminated, and the transmission loss of the optical fiber core 4 due to sealing is not reduced.

[0011]

[0012]

[0013]

According to the present invention, and the sealing with two kinds of resins of high viscosity and low viscosity, using the time, the resin higher the viscosity around the high affinity tensile strength fiber with sealing resin This prevents the resin from penetrating the fiber optic tape cord and the reinforcing cord through the tensile strength fiber, and the viscosity inside the protective case, including the area outside the sealed part of the high-viscosity resin. Since the resin is filled with a low (highly fluid) resin, the resin spreads throughout the inside of the protective case and good resin sealing can be realized . That is, according to the present invention, it is possible to provide an optical fiber tape cord branch portion which is excellent in sealing performance and does not deteriorate optical transmission characteristics.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a branch portion sealing structure of the present invention.

FIG. 2 is a partial cross-sectional view showing a conventional branch portion sealing structure.

[Explanation of symbols]

 A Branch 1 Optical fiber tape cord 3 High-tension fiber 4 Optical fiber core 7 Reinforcement cord 8 Protective case 9 Resin 10 Adhesive 12 First resin (high viscosity) 13 Second resin (low viscosity)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 6/00 G02B 6/24 G02B 6/44

Claims (2)

(57) [Claims] An optical fiber tape cord ;
Multiple optical fibers branching from the end of the tape
Protective tube, tensile fiber and outer sheath are sequentially fitted to the core wire
A sealing portion for sealing a branch portion between the reinforcing cord and the reinforcing cord formed in the protective case with a resin, wherein a cured material of the first resin having a viscosity of 15,000 to 20,000 cps at room temperature around the branch portion And the area other than the portion sealed by the first resin in the protective case is 30 ° C. at room temperature.
Curing of a second resin having a viscosity of 00 to 5000 cps
A sealing structure for a branch portion of an optical fiber tape cord, characterized by being sealed with an object . 2. An optical fiber tape cord and said optical fiber tape.
Multiple optical fibers branching from the end of the tape
Protective tube, tensile fiber and outer sheath are sequentially fitted to the core wire
A method for sealing a branch between the reinforcing cord and the reinforcing cord formed in a protective case with a resin, wherein the periphery of the branch is cured and sealed with a first resin having a viscosity of 15,000 to 20,000 cps at room temperature. After that, sealing with the first resin
3000-5000 at room temperature in the protective case including the part
A method for forming a sealing structure for a branch portion of an optical fiber tape cord, which comprises filling and curing with a second resin having a viscosity of cps.