JPH09203833A - Optical fiber cable core fixing method - Google Patents

Abstract

(57) An object of the present invention is to provide a method for fixing an optical fiber cable, which does not require a wide construction space, in a method for connecting optical fiber cables. According to the present invention, a spiral groove (3a) is provided on the outer circumference.
In the case of connecting an optical fiber cable having a structure in which the optical fiber core wire (2) is housed in a cylindrical spacer (3) having an optical fiber cable and another optical fiber cable, the length of the optical fiber cable is The optical fiber core wire (2) and the cylindrical spacer (3) in the direction of 3 mm to 50 mm.
And JIS are fixed by using a plastic material such as an adhesive (6) having a JIS spring hardness of 20 degrees or more and 60 degrees or less, a tube, a tape, etc. Is.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fixing an optical fiber cable core wire to a method for suppressing movement of the optical fiber core wire in a method of connecting optical fiber cables.

[0002]

2. Description of the Related Art When an optical fiber cable is laid in a place where vibration and temperature change are large, a force generated in order to relieve tension applied at the time of manufacture acts on the terminal portion from the inside of the cable. Thus, the optical fiber core wire at the end portion of the optical fiber cable tends to be drawn and moved inside the cable. Due to this movement, a slight bending may be applied to the optical fiber core wire in the vicinity of the connection portion, or pressure may be applied from the side surface, which may interfere with optical communication.

Specifically, as shown in FIG. 4, the optical fiber cable is first connected to the end of the optical fiber cable 10 to be connected, and the central tensile strength member 5 thereof is fixed to the closure 21 by means of the fixing metal fitting 5a. After fixing the optical fiber cores 2 to each other, the optical fibers 2 are connected like the optical fiber connecting portion 2a in a state where the loop 22 is formed inside the optical fiber connection box 20. In this case, the optical fiber core wire 2 moves toward the inside of the cable opposite to the connection terminal of the cable 10 due to the above-mentioned cause, and as a result, the radius of the optical fiber loop 22 becomes smaller and bending deformation is added. In some cases, the optical communication may be hindered by contact with the fixing metal 5a and receiving lateral pressure. Conventionally, as a means for suppressing this movement, as shown in FIG. 8, immediately before the connection point of the optical fiber cable 10,
That is, a method of increasing the frictional force of the optical fiber core by forming a loop 11 of the optical fiber cable 10 having a diameter 12 which is 20 times or more the outer diameter of the cable before the closure 21. Have been adopted.

As a prior art of the present invention, in addition to the above-mentioned well-known techniques, the general state of the art is shown as a practical technique.
No. 60713, Japanese Utility Model Laid-Open No. 62-181907,
As described in Japanese Utility Model Application Laid-Open No. 7-39004 and Japanese Patent Application Laid-Open No. 7-20363, there are inventions and inventions relating to the movement of the optical fiber core wire that constitutes the optical fiber cable. The present invention relates to causes of movement of different optical fiber cores, movement prevention means, and the like.

[0005]

With the recent increase in the amount of information and the increase in information speed, many optical fiber cables for transmitting information are laid at the same place, so that a sufficient space for laying can be provided at the time of laying. It has become difficult to adopt the conventional connecting method for forming the loop 11 that requires the above. In view of this, the present invention provides a method for connecting optical fiber cables, which allows the installation of a large number of optical fiber cables even in a narrow space without the need to form the loop 11 of the optical fiber cable.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an optical fiber cable having a structure in which optical fiber core wires are housed in a plurality of spiral grooves on the outer periphery of a cylindrical spacer and another optical fiber cable are provided. When connecting the cable, the optical fiber core wire near the connection end of the cable is made of a certain soft plastic material so as not to give bending strain or lateral pressure that causes optical loss. This is a method for fixing the core wire of an optical fiber cable, which is characterized in that a fixed predetermined length portion is fixed in the direction.

That is, a predetermined portion of each spiral groove is filled with a thermoplastic resin, or the optical fiber cores are bundled with a heat shrink tube or the like, heat treated, and then housed in the spiral groove. By so doing, the optical fiber core wire and the cylindrical spacer are fixed by a fixed length, and the movement of the optical fiber core wire is easily and effectively suppressed. This is a method of fixing the fiber core wire.

Specifically, the invention according to claim 1 is an optical fiber cable having a structure in which an optical fiber core wire is housed in a cylindrical spacer having a spiral groove on the outer periphery, and another optical fiber cable. In the case of connecting the optical fiber cable and the terminal, 3 m in the length direction of the cable near the terminal of the optical fiber cable.
Fixing the optical fiber core wire and the cylindrical spacer over a range of m to 50 mm using a thermoplastic resin having a JIS spring hardness of 20 degrees or more and 60 degrees or less, a tube, a tape or the like plastic material. This is a method for fixing the core wire of an optical fiber cable.

The invention according to claim 2 is characterized in that a thermoplastic resin such as polyamide resin is filled in the spiral groove accommodating the optical fiber core wire. It is a method of fixing the core of the bull.

According to a third aspect of the present invention, the optical fiber core wires housed in the spiral groove are bundled by a heat shrink tube, heat-treated, and inserted into the spiral groove. 1 is a method of fixing a core wire of an optical fiber cable.

According to a fourth aspect of the present invention, the optical fiber core wire housed in the spiral groove is wound with a heat collecting tape, heat-treated, and inserted into the spiral groove. 1 is a method of fixing a core wire of an optical fiber cable.

A fifth aspect of the present invention is the optical fiber cable core fixing method according to any one of the first to fourth aspects, further comprising 3 mm to 3 mm in the longitudinal direction of the optical fiber cable. A method of fixing a core wire of an optical fiber cable, characterized in that an adhesive tape is wound around the outer periphery of the spacer for 50 mm to enhance a fixing force between the spacer and the optical fiber core wire. is there.

According to a sixth aspect of the present invention, there is provided an optical fiber cable core wire fixing method according to any one of the first to fourth aspects, further comprising 3 mm to 3 mm in a length direction of the optical fiber cable. A core wire of an optical fiber cable, characterized in that a heat-shrink tape is wound around the outer periphery of the spacer for 50 mm for heat treatment to enhance the fixing force between the spacer and the optical fiber core wire. It is a fixing method.

In the invention described in claim 7, the optical fiber core wire is a tape core wire, and the optical fiber cable according to any one of claims 1 to 6 is characterized. It is a method of fixing the core wire.

The optical fiber cable is used for long-distance information transmission, and is restricted in its length due to manufacturing conditions, convenience in handling at the time of sale, etc. It will be connected for use during installation and used.
By the way, the connection of the optical fiber cable is performed by using a special connecting member such as the closure 21 and the optical fiber connection box 20 as shown in FIG. Moves toward the inside of the optical fiber cable, and as described above, the fixing fitting 5a inside the closure 21 is moved.
When external vibration is applied while it is in contact with etc.,
A sudden side pressure may be applied, which may hinder communication. When the radius of the optical fiber loop 22 becomes smaller,
Large bending strain may be applied and transmission loss may increase.

As a solution to this problem, the conventional method for constructing the cable loop 11 shown in FIG. 8 cannot be connected without the wide construction space as described above.

Therefore, as a result of various trial and error, the inventor of the present application uses a relatively soft plastic material so as not to cause optical loss and uses a cylindrical space for a part of the optical fiber core wire.
A thermoplastic resin such as a polyamide resin is filled in a predetermined position in each spiral groove in the cylindrical spacer in a length of the optical fiber cable by about 3 mm to 50 mm. By simply solidifying or bundling the optical fiber core wires with a heat shrinkable tube or the like and inserting them into the spiral groove after heat treatment, the optical fiber core wire and the spacer can be made to have optical characteristics extremely easily and effectively. It has been found that the movement of the optical fiber core can be suppressed by fixing the optical fiber without any hindrance.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the present invention, as described above, the optical fiber core wire 2 is provided with a cylindrical spacer 3.
In addition, a mode in which an adhesive such as a thermoplastic resin is used for fixing by an adhesive force, and an optical fiber core wire is bundled in a spiral groove of the cylindrical spacer 3 by using a plastic tube, a tape or the like. In a form of inserting and fixing by frictional force, in addition to these, an adhesive tape is wound around the circumference of these fixed portions of the cylindrical spacer 3, and the above-mentioned fixing force is applied by the adhesive force of the tape. There are forms to reinforce. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

[0019]

EXAMPLE A first example will be described. FIG. 1 is a view showing a cross section of an optical fiber cable of a fixed portion of an optical fiber core wire used in this embodiment. FIG. 2 is a view showing a cross section of an optical fiber cable which is a target of this embodiment. FIG. 3 is a view showing a side surface of the optical fiber cable of the fixed portion of the optical fiber core wire according to the present embodiment. FIG.
FIG. 6 is a diagram showing a state in which optical fiber cables are connected using the method of fixing a core wire according to the present embodiment.

The optical fiber cable used in this embodiment will be described with reference to FIG. 2. The sheath 1 is an outer coating, has a function of protecting the optical fiber cable from the outside, and has an outer diameter of 21 mm. . The cylindrical spacer 3 has five
It is a columnar linear body having a helical groove 3a for accommodating an optical fiber core wire, and has a central tensile strength body 5 for sharing the tension in the central portion. The material of this cylindrical spacer 3 is polyethylene, the diameter is 15 mm, and the width of the spiral groove is 1.5 m.
m, the depth is 2.5 mm, and the pitch of the spiral is 500 mm. As the optical fiber core wire 2, in the present embodiment, an optical fiber tape core wire having a width of 1.1 mm and a thickness of 0.4 mm, in which a plurality of optical fibers are arranged horizontally and covered with an ultraviolet curable resin, is used. Five pieces were stored in each of the spiral grooves 3a.

To fix the optical fiber tape core wire 2, as shown in FIG. 3, the sheath 1 and the presser winding 4 wound inside the sheath 1 at the end of the optical fiber cable 10 to be connected are fixed. At the position where the optical fiber tape core wire 2 is peeled off and exposed from the presser winding 4, a commercially available polyamide resin is heat-injected into each of the five spiral grooves 3a by 5 mm in the length direction of the cable. , The optical fiber tape core wire 2 and the spiral groove 3a are fixed. A cross section of this fixing portion is shown in the polyamide resin fixing portion 6 of FIG. 1, and a state seen from the side is shown in the polyamide resin fixing portion 6 of FIGS. 3 and 4, respectively. In this case, as shown in FIG. 1, the inside of the spiral groove 3a is filled with a polyamide resin in the gap of the optical fiber tape core wire 2 and is in a state in which it is slightly raised. The hardness of the polyamide resin after being fixed is sufficiently low so as not to affect the optical loss of the optical fiber core wire 2, and a rod-shaped body having a constant tip is pressed with a constant force to reduce the degree of depression. The JIS spring hardness to be judged was about 30 degrees.

In order to confirm the strength of fixation of the polyamide resin to the cylindrical spacer 3 (hereinafter referred to as the fixing force), the optical fiber cable 10 shown in FIG.
With respect to each of the five helical grooves 3a of one end, tensile stress is applied to the five accommodated and fixed optical fiber tape core wires, and the maximum stress required for separation from the cylindrical spacer 3 is measured, As a result of obtaining the average value, 3000 g / (5 m · 1 spiral groove) (hereinafter, simply “gram”)
That. )Met. Further, even when the optical fiber core wire 2 was not fixed to the columnar spacer 3, the tensile stress due to the frictional force was measured under the same conditions, and it was only 40 grams. Therefore, the difference from the former, that is, the net fixing force of the polyamide resin is 2960 grams. These results are shown in Table 1 as a polyamide resin (Example 1).
Column.

[0023]

[Table 1]

Next, in order to measure the fixing force by the conventional method, 5 m of the optical fiber cable shown in FIG. 2 was prepared, and the loop having a diameter of 420 mm, which was 20 times the diameter of 21 mm, was prepared. The force required to pull out the five optical fiber core wires 2 stored was measured, and the average value was obtained. The result was 600 grams as shown in the cable loop (comparative example) column of Table 1 and was therefore a net 560 grams.

From Table 1, the fixing force by the conventional method is 5 net.
While the fixing force by the polyamide resin of the present example was 60 grams, the net fixing force was 2940 grams, which was 5 times better than the conventional results.

Regarding the effect of fixing the tape core wire 2 with a polyamide resin on the optical loss, 1.55 μm of light is made incident from the other end of the 5 m optical fiber cable to make the optical fiber core. The optical fiber core wire for measurement was connected to the optical fiber core wire of the terminal portion on the side where the wire was fixed, and the optical loss was measured by a power meter. The optical loss was 0 dB before and after the fixed portion 6, and it was confirmed that fixing with a polyamide resin did not affect the optical characteristics.

Further, in order to confirm the soundness of the fixed portion 6 of the optical fiber core wire 2 according to this embodiment under the use environment,
At the other end of the 5 m optical fiber cable, a heat cycle was applied with a force of 600 g estimated to be the upper limit of the force acting in the inward direction of the cable being applied, and an optical strength was also added. I confirmed that there was no problem. That is, a heat cycle test in which the process of leaving the upper and lower limits for 2 hours each in the operating environment temperature range of −20 ° C. to + 60 ° C., which is recognized as a verification test condition of the soundness of the optical fiber cable, is repeated 100 times. Then, the presence or absence of movement of the tape core wire 2 was examined, but no movement was observed. In addition, no increase in optical loss due to deterioration of the fixed part was observed.

In this embodiment, the hardness of the polyamide resin after being fixed is 30 degrees in JIS spring hardness.
It is not limited to this, and the optical characteristics are not affected in the range of 20 ° to 60 °. However, at the lower limit, the strength is slightly lowered, and at the upper limit, the optical characteristics start to be affected. Therefore, the JIS spring hardness is preferably in the range of 30 to 50 degrees. In the present embodiment, the optical fiber cable in which the spiral groove 3a has five columnar spacers is used, but the present invention is not limited to this, and even if the spiral groove 3a has more than 5, May be small. Further, although the optical fiber tape core wire 2 is used in the present embodiment, the present invention is not limited to this, and an ultraviolet curable resin is applied to the surface of the core wire of a plurality or a single optical fiber, that is, the cladding of the optical fiber. It may be an optical fiber in a coated state. Also,
In the present embodiment, a case is adopted in which the five tape cores 2 which are the storage capacities of the spiral grooves 3a are stored in the spiral grooves 3a, but the present invention is not limited to this. It is also possible to accommodate a smaller number of optical fiber ribbons 2.

Further, in the present embodiment, the tape core wire 2 is fixed by the polyamide resin in the length direction of the cable by 5 mm, but the present invention is not limited to this, and it is 3 mm to 50 m.
It is effective even if fixed within the range of m. However, the lower limit is 3 mm
Even though the fixing force is sufficient, the work becomes difficult, and the upper limit is usually about 50 mm from the end of the presser winding 4 to the end of the cylindrical spacer 3 as shown in FIG. 3, and the fixing can be made within this range. The range of 3 mm to 40 mm is desirable.

The second embodiment will be described with reference to FIG. In this embodiment, an adhesive tape 9 is further wound on the fixing portion 6 made of the polyamide resin of the first embodiment to reinforce the fixing force to the cylindrical spacer 3. Adhesive tape 9 is a polyethylene base having a thickness of 0.3 mm and a width of 5 mm coated with a rubber-based adhesive.
The spring hardness is 40, which is relatively soft. In this embodiment, the adhesive tape 9 is wound around the fixed portion 6 made of polyamide resin for two rounds.
Under the same conditions as in Example 1, the force required for pulling out the optical fiber ribbon 2 and the optical loss were measured. As shown in the column of polyamide resin (Example 2) in Table 1, the fixing force to the cylindrical spacer 3 was increased by about 20%. It was also confirmed that there was no increase in light loss.

In this embodiment, an optical fiber cable in which five tape cores are housed in each spiral groove 3a is used, but the number is not limited to this, and the number is less than this. Good. However, in this case, even if the adhesive tape 9 is sprinkled, the optical fiber tape core wire 2 housed in the spiral groove 3a cannot be contacted and the reinforcing effect cannot be exerted.
An adhesive tape 9 was relatively loosely wound on the cylindrical spacer 3 and then appropriately pressed from the outside through a sheet made of a soft material to be housed in the spiral groove 3a. It is desirable to bond and fix the tape core wire 2 made of a polyamide resin by bringing the adhesive tape 9 into contact with the tape core wire 2. Alternatively, a method of previously raising the bottom of the spiral groove of the fixed portion by filling an appropriate material may be used. In this embodiment, the adhesive tape 9 is wound on the cylindrical spacer 3 to reinforce the fixing force, but the present invention is not limited to this, and the heat shrinkage is made of a material having a low hardness such as polyethylene. Similar effects can be obtained by winding a tape or the like and heat-treating it.

The third embodiment will be described with reference to FIG. In this embodiment, a predetermined portion of the five optical fiber tape core wires 2 housed in each spiral groove 3a is heat-shrinkable.
It is bundled by the sleeve 7, heat-treated, and then inserted into the original position of the spiral groove 3a. The heat-shrink tube used was a polyethylene tube having a thickness of 0.2 mm and a radius of 1.0 mm, and had a JIS spring hardness of 50, which was relatively soft. This tube was passed through five optical fiber tape cores, heat-treated with a hair dryer, and width 1.
After the size of 3 mm and the height of 2.8 mm, the length of the portion covered with the heat-shrinking tube becomes a bundle of the tape core wires 2 of about 5 mm, and then the position of the original spiral groove 3a Inserted in.

The fixing force of the optical fiber core wire 2 to the cylindrical spacer 3a was measured by the same method as described above.
No. 14 heat-shrink tubing (Example 3)
It was possible to obtain a fixing force that was slightly less than three times that of 60 grams, which is 560 grams of the conventional method. The light loss of the fixed portion 7 was 0 dB, which was the same as in Examples 1 and 2, and there was no problem. The results of the heat cycle test were also good as in Examples 1 and 2.

Although the heat shrink tube is used in this embodiment, a heat shrink tape may be used. The heat-shrink tape used was a polyethylene heat-shrink tape with a thickness of 0.2 mm and a width of 7 mm, and the JIS spring hardness was 50.
And a relatively soft one was adopted. Similarly, after winding 5 rounds of the optical fiber tape with this heat shrink tape,
Heat-treated with a hair dryer, width 1.3 mm, height 2.8 m
m size, the length of the part covered with heat shrink tape is 5
After forming a bundle of the tape core wires 2 having a size of about mm, the tape core wires 2 were inserted into the spiral groove 3a. When the fixing force of the optical fiber core wire 2 to the cylindrical spacer 3a was measured by the same method, as shown in the parentheses of the heat shrink tube (Example 3) in Table 1, the net force was 1210 g. , Net of conventional method 5
It was possible to obtain a value slightly less than three times that of 60 grams. The light loss of the fixed portion 7 was 0 dB, which was the same as in Examples 1 and 2, and there was no problem. The results of the heat cycle test were also good as in Examples 1 and 2.

The fourth embodiment will be described with reference to FIG. In this embodiment, an adhesive tape 9 is further wound on the fixing portion 7 of the tape core wire 2 of the third embodiment to reinforce the fixing force to the cylindrical spacer 3. It is. Adhesive tape
The same type as that used in Example 2 was used for Group 9. In this embodiment, the adhesive tape 9 is wound around the circumference of the cylindrical spacer 3a including the fixing portion 7 by the heat shrink tube of the third embodiment only twice. As shown in the heat shrink tube (Example 4) column of Table 1, a cylindrical spacer 3
It was confirmed that the fixing power to a was increased and that the optical loss was not increased at all. The results of the heat cycle test were also good as in Examples 1, 2, and 3.

In the fourth embodiment, the case where the optical fiber tape core wire 2 is fixed by using the heat shrinkable tube is carried out. However, even when the heat shrinkable tape is used, the result shown in Table 1 is obtained. It was confirmed that similarly good results were obtained, as shown by an example of the results in the parentheses in the heat shrink tube (Example 4) column.

[0037]

As described above, according to the present invention, the optical fiber core wire in the vicinity of the connection terminal of the optical fiber cable is made light by using a certain soft plastic material without affecting the optical characteristics. By fixing to the fiber cable and suppressing the movement of the optical fiber core easily and effectively, the fixing is equal to or better than the core fixing method which constitutes the proven conventional cable loop. Have power,
Moreover, a large number of optical fiber cables can be laid with a narrow construction space.

[0038]

[Brief description of drawings]

FIG. 1 is a view showing a cross section of a fixed portion of an optical fiber according to the present invention.

FIG. 2 is a view showing a cross section of an optical fiber cable, which is a target of the present invention.

FIG. 3 is a diagram showing a side surface of a fixed portion of an optical fiber according to the present invention.

FIG. 4 is a diagram showing a state in which optical fiber cables are connected by using the core wire fixing method of the present invention.

FIG. 5 is a cross-sectional view of a fixed portion of an optical fiber core wire according to another fixing method of the present invention.

FIG. 6 is a view showing a cross section of a fixed portion of an optical fiber core wire according to another fixing method of the present invention.

FIG. 7 is a view showing a cross section of a fixed portion of an optical fiber core wire according to another fixing method of the present invention.

FIG. 8 is a diagram showing a method of fixing an optical fiber according to a conventional technique.

[Explanation of symbols]

 1: Seed 2: Optical fiber core wire 2a: Optical fiber core wire connection part 2c: Optical fiber connection tube 3: Cylindrical spacer 3a: Spiral groove 4: Presser winding 5: Central tensile member 5a: Fixing bracket 6: Polyamide resin 7: Heat shrink tube 8: Heat shrink tape 9: Adhesive tape 10: Optical fiber cable 11: Optical fiber cable loop 11 12: Cable loop diameter 20: Optical Fiber connection box 21: Closure 22: Optical fiber loop

Claims (7)

[Claims] 1. A cylindrical spacer having a spiral groove on the outer periphery thereof.
Optical fiber cable with a structure in which the optical fiber core is stored in the
When connecting the optical fiber cable to another optical fiber cable, the optical fiber core wire and the cylindrical spacer are extended in the length direction of the cable near the terminal of the optical fiber cable for 3 mm to 50 mm. And a thermoplastic resin having a JIS spring hardness of 20 degrees or more and 60 degrees or less, a tube,
A method for fixing the core wire of an optical fiber cable characterized by fixing using a plastic material such as tape 2. The method of fixing a core wire of an optical fiber cable according to claim 1, wherein a poamide resin is used as a thermoplastic resin for fixing the core wire of the optical fiber, and the spiral groove is filled with the polyamide resin. 3. The optical fiber cable according to claim 1, wherein the optical fiber cores housed in the spiral groove are bundled by a heat shrink tube, heat-treated, and inserted into the spiral groove. Bull core fixing method 4. The optical fiber according to claim 1, wherein the optical fiber core wires housed in the spiral groove are wound with a heat collecting tape, bundled, heat-treated, and inserted into the spiral groove. Fiber cable core fixing method 5. The optical fiber cable core fixing method according to any one of claims 1 to 4, further comprising 3 mm to 50 m in a length direction of the optical fiber cable.
A method for fixing a core wire of an optical fiber cable, characterized in that an adhesive tape is wound around the outer periphery of the spacer over a length of m to reinforce the fixing force between the spacer and the optical fiber core wire. 6. The optical fiber cable core fixing method according to any one of claims 1 to 4, further comprising 3 mm to 50 m in a length direction of the optical fiber cable.
The core of the optical fiber cable is characterized in that a heat shrink tape is wound around the outer periphery of the spacer over a length of m to perform heat treatment to reinforce the fixing force between the spacer and the optical fiber. Fixing method 7. The optical fiber core wire according to claim 1, wherein the optical fiber core wire is a tape core wire.
Of fixing the optical fiber cable to the optical fiber