JPH08262290A - Central member for optical fiber assembly and composite fiber optic overhead ground wire - Google Patents

Abstract

PURPOSE: To make it possible to increase the fibers of a composite fiber optic overhead ground wire without increasing the diameter of an optical fiber unit by forming an equal and smooth cushion layer on the outer peripheral surface of a central member and reducing the diameter of an optical fiber assembly. CONSTITUTION: The optical fiber unit of the composite fiber optic overhead ground wire is composed of an aluminum protective pipe, an FRP main tensile member and eight optical fiber assemblies 3 arranged on the circumference. Each optical fiber assembly 3 is composed by bundling a bar-shaped auxiliary tensile member 7 as the central member and six pieces of coated optical fibers 8, 8,... arranged adjacently to each other in the circumferential direction of the member so as to enclose its circumference with a polyimide tape 9. The surface of the FRP bar-shaped body 7a of the auxiliary tensile member is coated with a coating layer 7b thinner than a UV resin added with silicone to make an even and smooth circumferential surface. On the other hand, UV curing resin coated fibers formed by applying UV curing resin coatings 8b on optical fibers 8a are used as the coated optical fibers to be pressed to the coating layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a central member for an optical fiber assembly which constitutes an optical fiber composite overhead ground wire (OPGW) used in the field of electric power, and an optical fiber composite overhead ground using this central member. Regarding the line.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5 and FIG. 6, there is known an optical fiber composite overhead ground wire of this type. This is constructed such that the optical fiber unit 40 is protected by a plurality of aluminum-covered steel wires 5, 5, ... Which are twisted wires so as to surround the periphery thereof. The optical fiber unit 40 is a protective pipe. 1 and a central interposition member 20 arranged along the shaft portion of the protection pipe 1.
And four optical fiber assemblies 30, 3 arranged in the circumferential direction between the central interposition member 20 and the protection pipe 1.
It is composed of 0 ,. As shown in detail in FIG. 7, each of the optical fiber assemblies 30 therein has a glass fiber reinforced plastic (FRP) arranged in a central position.
Made of a rod-shaped central member 70 having a circular cross section, and the central member 70
, And six optical fiber core wires 80, 80, ... Arranged in the circumferential direction so as to surround the circumference of the core member. The plurality of optical fiber core wires 80, 80 ,. A tape 9 made of polyimide or the like is wound around and bundled in a state of being in contact with the surface.

The center member 70 and each optical fiber core wire 80 are formed to have the same diameter because of the convenience of using them as a stranded wire, and therefore, the optical fibers surrounding the center member 70. The number of core wires 80 is six.
As the optical fiber core wire 80, a silicone-coated fiber in which a coating 80b of silicone resin is applied to the optical fiber element wire 8a is used. Diameter is tape 9
It becomes 1.25 mm including. On the other hand, since the optical fiber unit 40 is formed to have an outer diameter of 3.8 mm at the maximum according to the specifications in the field of electric power, the wall thickness of the protective pipe 1 is set to 0.4 mm and the center interposition member 20 is used.
If the outer diameter is 0.5 mm, the maximum diameter becomes 3.0 mm inside the protective pipe 1, and four optical fiber assemblies 30, 30, ... Are arranged. This allows
The optical fiber unit 40 of the optical fiber composite overhead ground wire is 2
It is configured by incorporating four optical fiber core wires.

[0004]

By the way, in the above-mentioned optical fiber composite overhead ground wire, it is required to increase the number of optical fibers so that one optical fiber composite overhead ground wire includes a larger number of optical fiber core wires. ing. In this case, in order to increase the number of cores without changing the strength of the tower over which the optical fiber composite overhead ground wire is suspended, it is necessary to make the load on the steel tower approximately the same as that of the conventional optical fiber composite overhead ground wire. Therefore, for this reason, the outer diameter of the optical fiber unit is limited to the same as the conventional one, and the aluminum covered steel wire 5, which occupies almost all of its own weight,
5, and the protection pipe 1 must be kept the same size as the conventional one. Therefore, in order to increase the number of fibers, it is conceivable to reduce the diameter of the optical fiber assembly itself to increase the number of optical fiber assemblies arranged in the optical fiber unit.

As a measure for this, an ultraviolet-curable resin-coated fiber (UV-coated fiber) coated with an ultraviolet-curable resin that can be made thinner than the above-mentioned silicone-coated fiber 80 to have a smaller diameter is used as an optical fiber core wire. It is conceivable that the diameter of the above optical fiber assembly is made smaller than that of the case where the silicone-coated fiber 80 is used.

However, in this case, since the coating thickness of the above UV coated fiber is thinner than that of the silicone coated fiber, the transmission loss (side pressure loss) may increase due to the side pressure acting through the contact portion with the central member 70. There is. In particular, the outer peripheral surface of the FRP center member is likely to be affected by surface roughness and surface slippage, and the transmission characteristics may be deteriorated due to the influence of lateral pressure. Therefore, it is possible to cover the outer peripheral surface of the central member with a cushion layer, but in order to minimize the influence of the lateral pressure, the outer peripheral surface of the cushion layer needs to be sufficiently smooth. Further, when a smaller diameter UV coated fiber is used as the optical fiber core, the center member also has the same diameter as the above UV coated fiber, and in this case, in order to secure the tensile strength by the center member. The cushion layer should be as thin as possible. As a coating material for forming such a cushion layer, it is conceivable to use a silicone resin or an ultraviolet curable resin (hereinafter, also referred to as a UV resin) as in the case of coating the optical fiber element wire 8a.

However, when a silicone resin is used as the coating material, it is necessary to make it thicker than the UV resin in order to ensure the same cushion performance, and the outer peripheral surface of the cushion layer formed using the silicone resin is sticky. The lateral pressure loss may increase due to the relative displacement between the UV-coated fiber and the outer peripheral surface. On the other hand, when a UV resin is used as the coating material, a relatively thin coating can be obtained, but the above-mentioned center member is FR.
Since it is formed of P, the wettability between the outer peripheral surface and the UV resin is extremely poor, the coating material is unlikely to adhere, the thickness of the coating fluctuates easily, and air bubbles are easily entrained in the interface with the central member. The mixed bubbles may cause unevenness on the outer surface of the cushion layer. Then, if the above-mentioned variation in wall thickness or unevenness on the outer surface occurs, the lateral pressure loss will significantly increase.

That is, in order to increase the number of cores of the optical fiber composite overhead ground wire, it is necessary to reduce the diameter of the optical fiber assembly, and in order to reduce the diameter of the optical fiber assembly, the coating layer formed on the central member is used. Smoothing is an issue.

The present invention has been made in view of the above circumstances, and an object of the present invention is to form a thin, uniform and smooth cushion layer on the outer peripheral surface of a central member to form an optical fiber assembly. The purpose is to make the diameter small, and to make the optical fiber composite overhead ground wire multi-core without using the central member to increase the diameter of the optical fiber unit.

[0010]

In order to achieve the above object, the invention according to claim 1 is a rod-shaped central member having a circular cross-section formed of an insulating material and arranged at the central position of the optical fiber assembly. A plurality of optical fiber cores are arranged in the circumferential direction so as to surround the periphery of the central member and are bundled in contact with the outer peripheral surface of the central member to form an optical fiber assembly. Assumption. The central member is composed of a rod-shaped main body having a circular cross section and a coating layer for coating the outer peripheral surface of the main body, and the coating layer is formed by coating a silicone-containing UV-curable resin. It is a thing.

According to a second aspect of the present invention, the rod-shaped main body of the central member in the first aspect is formed of glass fiber reinforced plastic to constitute a tensile strength member.

Further, the invention according to claim 3 is the same as claim 1.
The invention relates to an optical fiber composite overhead ground wire using a central member for an optical fiber assembly, the optical fiber composite overhead ground wire, a protective pipe, and a central interposition member arranged along the axis of the protective pipe. And eight optical fiber assemblies disposed in the circumferential direction along the outer peripheral surface of the central interposing member between the central interposing member and the protective pipe. Each of the optical fiber assemblies is provided with one center member and six optical fiber core wires arranged so as to surround the center member, and the center member and each optical fiber core wire are provided. Are formed so as to have the same outer diameter as each other, and the optical fiber core wires are arranged so as to contact the central member and the optical fiber core wires that are adjacent to each other in the circumferential direction contact each other. Be bundled together. In addition, the central member is composed of a rod-shaped main body having a circular cross section and a coating layer that coats the outer peripheral surface of the main body, and the coating layer is formed by coating a silicone-containing UV-curable resin. To do.

[0013]

According to the above-mentioned structure, according to the first aspect of the present invention,
Since a thin coating layer is formed on the outer peripheral surface of the central member having a circular cross section, the coating layer acts as a cushion layer for a plurality of optical fiber core wires arranged in contact with the periphery of the central member. Thus, the side pressure acting on the optical fiber core wire is relaxed, and the increase of the side pressure loss is suppressed. At this time, since the coating layer is formed of silicone-added UV resin, the wettability with the central member is remarkably improved, which stabilizes the adhesion to the outer peripheral surface of the central member and prevents bubbles. The mixture is prevented. For this reason, the outer diameter of the outer peripheral surface of the formed coating layer is prevented from becoming uniform and uniform, and the unevenness due to the inclusion of air bubbles is prevented to improve the smoothness of the outer peripheral surface. It is possible to prevent an increase in lateral pressure loss with respect to each optical fiber core wire due to fluctuations and the occurrence of irregularities. As a result, even if a UV coated fiber having a relatively thin coating thickness on the optical fiber is adopted as the optical fiber core wire forming the optical fiber assembly, the lateral pressure loss of the optical fiber core wire is about the same as the conventional one. Or, since it can be suppressed to a lower level, it becomes possible to construct an optical fiber assembly by the above UV coated fiber, and as a result,
Even if the same number of optical fiber cores as those in the prior art are arranged to form an optical fiber assembly, the diameter can be reduced. Then, since it becomes possible to reduce the diameter of the optical fiber assembly by using such a central member, by configuring an optical fiber composite overhead ground wire using the optical fiber assembly,
Even if the protection pipe has the same diameter as that of the conventional one, the number of optical fiber assemblies arranged inside increases, and the number of optical fiber core wires in the optical fiber composite overhead ground wire can be increased.

According to the invention described in claim 2,
In addition to the action of the invention described above, even if the rod-shaped main body of the central member to be coated is formed of FRP and the wettability with the coating material is extremely poor, the wettability is dramatically increased by adding silicone to the UV resin. Therefore, it is possible to stabilize the adhesion of the silicone-added UV resin to the FRP rod-shaped main body and prevent bubbles from entering. This allows FR
Even with respect to the P-shaped rod main body, the uniform and smooth outer peripheral surface is formed as described above, and it is possible to prevent an increase in the lateral pressure loss of each optical fiber core due to the variation of the outer diameter and the occurrence of irregularities.

Further, according to the third aspect of the present invention, the coating layer is formed on the central member by using the silicone-added UV resin, and as described above, the optical fiber is used as the optical fiber core wire forming the optical fiber assembly. Since it becomes possible to employ a small diameter UV coated fiber having a relatively thin coating thickness on the strands, an optical fiber assembly constituted by arranging six UV coated fibers for a central member having the same diameter as the above The body is smaller than the conventional one. Therefore, it becomes possible to form an optical fiber unit in which eight optical fiber assemblies are arranged in the protection pipe having the same diameter as the conventional one, which is more than four in the conventional case. In addition to making it possible to increase the number of optical fiber cores in the optical fiber, it becomes possible to make the central intervening member thick as the diameter of the optical fiber assembly is reduced, and when the central intervening member is configured as a tensile strength member. Has a greater safety margin for working tension.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a central member for an optical fiber assembly and an optical fiber composite overhead ground wire using the same according to an embodiment of the present invention. In the figure, 1 is a protection pipe made of aluminum having a circular cross section, 2 is a main tensile member as a central intervening member extending along the axis of the protection pipe 1,
.. are optical fiber assemblies, and the protective pipe 1, the main tensile strength member 2, and the eight optical fiber assemblies 3, 3, ... Form an optical fiber unit 4. The optical fiber unit 4 is covered with a plurality of (seven in the illustrated example) aluminum-covered steel wires 5, 5, ... Around the optical fiber unit 4 to form an optical fiber composite overhead ground wire.

The main tensile member 2 is formed of FRP into a rod shape having a circular cross section, and a coating layer 2a is formed on the outer peripheral surface of the main tensile member 2 with, for example, nylon paint. The eight optical fiber assemblies 3, 3, ... Are arranged in the circumferential direction of the main tensile member 2 so as to surround the main tensile member 2, and the eight optical fiber assemblies 3, 3 ,. The tensile strength member 2 is wrapped around the periphery by a tape 6 made of polyimide, for example, to be bundled. The surroundings of the eight optical fiber assemblies 3, 3, ... In the bundled state are covered with an aluminum plate material and welded to form a protective pipe 1 made of the aluminum plate material.

As shown in detail in FIG. 3, each of the optical fiber assemblies 3 has a rod-shaped sub-tensile member 7 as a central member arranged at a central position, and the sub-tensile member 7 surrounding the sub-tensile member 7. It is composed of six optical fiber core wires 8, 8, ... Arranged adjacent to each other in the circumferential direction.

The sub-tensile member 7 is composed of a rod-shaped main body 7a made of FRP and having a circular cross section, and a thin coating layer 7b formed of a UV resin containing silicone so as to cover the outer peripheral surface of the rod-shaped main body 7a. ing. In the sub-tensile member 7, the thin-walled coating layer 7b is formed on the rod-shaped main body 7a having an outer diameter of 0.21 mm, and the outer diameter is 0.25 mm which is the same as that of each optical fiber core wire 8 described later. Is formed. The above UV resin has urethane acrylate as a main component, and silicone oil is added with silicone oil, silicone acrylate, etc.
It may be added in a small amount (for example, 0.1% by weight) with respect to the V resin.

Each of the optical fiber core wires 8 has a primary and secondary coating 8b of UV resin around the optical fiber element wire 8a.
It is made of a UV-coated fiber having a diameter of 0.25 mm and has an outer diameter of 0.25 mm. The above six optical fiber core wires 8, 8, ... Are made into a stranded wire with the sub-tension member 7 as a core, and a tape 9 made of polyimide or the like is wound around and bundled to form the optical fiber assembly 3 Thus, the outer peripheral surfaces of the optical fiber core wires 8 and 8 adjacent to each other and the outer peripheral surfaces of the optical fiber core wires 8 and the sub-tensile member 7 are in contact with each other. .

Then, each optical fiber core wire 8 which is a UV-coated fiber having an outer diameter of 0.25 mm is bundled by a tape 9 with respect to the auxiliary tensile member 7 having an outer diameter of 0.25 mm, and an optical fiber having an outer diameter of 0.80 mm. The aggregate 3 is formed, and the outer diameter of the main tensile strength member 2 is 1.40 m when arranging the eight optical fiber aggregates 3, 3, ...
m, the maximum diameter of the peripheral surface is 3.0 mm.

In the case of the optical fiber unit structure having the above-mentioned configuration, in each optical fiber assembly 3, since the outer peripheral surface of the sub-tensile member 7 having a circular cross section is constituted by the coating layer 7b, the periphery of the sub-tensile member 7 is formed. The coating layer 7b for the plurality of optical fiber core wires 8, 8, ...
Acts as a cushion layer, and each of the optical fiber core wires 8
The side pressure that acts on the side wall is relaxed, and the increase in the side pressure loss is suppressed. At this time, even if the main body 7a of the sub-tensile member 7 to be coated is formed of FRP and the wettability is extremely poor when a single UV resin is used as the coating material, silicone is added to the UV resin. Since the material is used as the covering material, the covering material and the sub-tensile member 7
The wettability between and is drastically improved, thereby stabilizing the adhesion of the silicone-added UV resin, which is the coating material, to the outer peripheral surface of the FRP sub-tensile member 7, and preventing the inclusion of bubbles. it can. As a result, the outer diameter of the outer peripheral surface of the coating layer 7b formed on the FRP sub-strength member 7 is prevented from becoming uniform and uniform, and the unevenness due to the inclusion of bubbles is prevented and the outer peripheral surface is smoothed. The degree is improved, and it is possible to prevent the increase of the lateral pressure loss of each optical fiber core wire 8 due to the change of the outer diameter and the occurrence of the unevenness.

Therefore, as the optical fiber core wire 8 for constructing the optical fiber assembly 3, even if the coating 8b for the optical fiber element wire 8a is made relatively thin and a small diameter UV coated fiber is adopted, The lateral pressure loss of each optical fiber core wire 8 due to the influence of lateral pressure from the tensile strength member 7 can be suppressed to an extremely low value. Therefore, the optical fiber assembly 3 is constructed using such a small diameter UV coated fiber. As a result, the diameter of the optical fiber assembly 3 can be reduced. Specifically, the outer diameter of the optical fiber assembly 3 is 1.25 mm when a conventional silicone-coated fiber is used.
0.8 mm from (outer diameter of optical fiber assembly 30 in FIG. 7)
The diameter can be reduced. As the diameter of the optical fiber assembly 3 is reduced, even if the protective pipe 1 having the same size as that in the conventional optical fiber unit structure is used, the optical fiber assembly can be arranged in the protective pipe 1. 3 to 8 in the case of the conventional optical fiber unit structure (see the optical fiber assembly 30 in FIG. 5).
With books can be increased significantly. In addition, the outer diameter of the main tensile strength member 2 at the center is 0.5 mm in the case of the conventional optical fiber unit structure as the diameter of the optical fiber assembly 3 is reduced.
The outer diameter of the main tensile strength member 20 in FIG. 5 can be increased to 1.4 mm. As a result, the number of built-in optical fiber core wires 8 can be significantly increased and the number of optical fibers can be increased while maintaining the same diameter size as in the conventional optical fiber unit structure. In addition, by increasing the diameter of the main tensile strength member 2 described above, it is possible to further increase the safety margin against the acting tension of the optical fiber composite overhead ground wire.

<Performance Test> -Surface Texture According to Resin Type-Coating layer 7c using silicone resin as a coating liquid on the outer peripheral surface of the rod-shaped body 7a having an outer diameter of 0.21 mm.
(See FIG. 4) to form a sub-tensile member 7'having an outer diameter of 0.4 mm, and a coating layer using a UV resin containing urethane acrylate as a main component as a coating liquid to form an outer diameter of 0. A second test body having a sub-tensile member of 25 mm and a third sub-strength member 7 having an outer diameter of 0.25 mm formed by using the above UV resin with silicone added as a coating liquid to form a coating layer 7b. 3 with test body
For one case, the smoothness of the outer peripheral surface and the workability in forming an optical fiber assembly by bundling with each optical fiber core wire 8 were confirmed. Table 1 shows the results.

[0026]

[Table 1]

As a result of this test, in the case of the first test body using the silicone resin as the coating liquid, the outer surface of the coating layer 7c becomes sticky and the smoothness is extremely inferior to the other cases, and the optical fiber core Since the wire 8 was apt to be adsorbed, the work of forming the optical fiber assembly was extremely difficult (see XX mark in Table 1). In this case, due to the stickiness, the outer surface of the coating layer 7c and the coating thickness U are relatively thin.
It is considered that when a relative displacement occurs due to thermal contraction or the like with the outer peripheral surface of the V-coated fiber, the lateral pressure loss is significantly increased.

Further, in the case of the second test body using the UV resin as the coating liquid, although the coating can be made relatively thin, the variation in the wall thickness causes difficulty in the uniformity of the outer diameter and inclusion of bubbles. Occurred, and unevenness was generated on the outer surface of the bubble-mixed portion (see x mark in Table 1). This is because the wettability between the FRP rod-shaped main body 7a and the UV resin is extremely poor.
It is considered that the UV resin did not adhere evenly to the outer peripheral surface of the rod-shaped main body 7a, and the variation in wall thickness and the inclusion of bubbles occurred. On the other hand, in forming the optical fiber assembly, attention was paid to the fact that the uniformity of the outer diameter was difficult as described above, but it was relatively good without stickiness as described above (Table 1). Refer to ○).

Further, in the case of the third test body using a silicone-added UV resin as the coating liquid, the outer surface of the formed coating layer 7b had a uniform outer diameter and was smooth without inclusion of bubbles (Table Refer to the ○○ mark in 1.). This is because the wettability between the UV resin after the addition and the FRP-made rod-shaped main body 7a is dramatically improved by the addition of the above silicone, and the adhesion to the outer peripheral surface of the rod-shaped main body 7a is improved, so that the adhesiveness is even. It is considered that a smooth outer surface was obtained. in addition,
Since the surface properties of the sub-tensile member 7 have a uniform outer diameter and are smooth, the workability of forming the optical fiber assembly was also very good (see XX mark in Table 1).

-Transmission Characteristics- The optical fiber assembly formed by using the above-mentioned second and third test bodies was examined for transmission loss in the temperature range of -20 ° C to + 100 ° C. Table 2 shows the maximum transmission loss in this case.

[0031]

[Table 2]

As a result of this test, UV without silicone was added.
The maximum transmission loss was 0.5 dB / km in the optical fiber assembly composed of the second test body made of resin, whereas the optical fiber assembly made of the first test body made of the silicone-added UV resin was used. The maximum transmission loss in the body is 0.1
It is suppressed to an extremely low value of dB / km. this is,
Since the outer peripheral surface of the sub-tensile member 7 is smooth as described above, an increase in lateral pressure loss for each optical fiber core due to unevenness caused by fluctuations in the outer diameter of the second test body and inclusion of bubbles is prevented, and the transmission characteristics are reduced. It is considered that the improvement was achieved.

<Other Embodiments> The present invention is not limited to the above embodiments, but includes various other modifications. That is, in the above embodiment, the case where the optical fiber assembly 3 configured by using the auxiliary tension member 7 as the central member is used as a constituent element of the optical fiber unit 4 is shown, but the present invention is not limited to this. The fiber assembly 3 may be used alone or as a component other than the optical fiber composite overhead ground wire.

In the above embodiment, the optical fiber assembly 3 is composed of 8
Although the optical fiber unit 4 is configured by arranging the main fibers, the number of the optical fiber units 4 is not limited to this, and the main tensile strength member having an outer diameter that can be surrounded by the number of the optical fiber assemblies of eight is used to increase the number of cores. In addition to this, the diameter of the optical fiber unit itself may be reduced.

Although the rod-shaped main body 7a of the sub-tensile member 7 is formed of FRP in the above embodiment, the present invention is not limited to this.
Other materials may be used as long as they have an insulating property and can exhibit a predetermined tensile strength. Also in this case, by using the UV resin added with silicone, the wettability can be further increased, and the smooth coating layer 7b without air bubbles can be formed, and the transmission loss due to the influence of the lateral pressure can be reduced to reduce the diameter. It is possible to increase the number of cores by reducing the diameter of the optical fiber assembly using the UV coated fiber. Further, the above central member does not necessarily have to be configured as a tensile strength member,
Further, the central member may be formed of an insulating material other than FRP.

Further, although the main tensile member 2 is shown as the center interposing member in the above embodiment, the present invention is not limited to this, and the center interposing member is, for example, a grooved spacer around which a groove for holding the optical fiber assembly 3 is formed. You may comprise a member.

Further, in the above-mentioned embodiment, only the asserting force member 2 and the plurality of optical fiber aggregates 3, 3, ... Are provided in the protective pipe 1 of the optical fiber unit 4, but the present invention is not limited to this. Instead, other inclusions may be arranged in the gap in the protection pipe 1.

[0038]

As described above, according to the center member for an optical fiber assembly of the invention described in claim 1, since the thin coating layer is formed on the outer peripheral surface of the center member having a circular cross section, The above-mentioned coating layer acts as a cushion layer for a plurality of optical fiber core wires arranged in contact with the periphery of the central member, and the side pressure acting on the optical fiber core wires can be relieved, resulting in a side pressure loss. Can be suppressed. At this time, since the coating layer is made of a silicone-added UV resin, the wettability with the central member is dramatically improved, the adhesion to the outer peripheral surface of the central member is stabilized, and the inclusion of bubbles is prevented. It can be prevented. Therefore, it is possible to prevent the outer diameter variation of the outer peripheral surface of the formed coating layer to be uniform and to improve the smoothness of the outer peripheral surface. It is possible to reliably prevent an increase in lateral pressure loss for each optical fiber core wire. As a result, even if a small diameter UV coated fiber having a relatively small coating thickness for the optical fiber is adopted as the optical fiber core wire forming the optical fiber assembly, the lateral pressure loss of the optical fiber core wire is conventionally reduced. As a result, it can be suppressed to the same level as or lower than the relatively thick-walled silicone-coated fiber used, and as a result, even if the same number of optical fiber cores are arranged to form an optical fiber assembly, the diameter can be reduced. Can be planned. Then, since it is possible to reduce the diameter of the optical fiber aggregate by using the above-mentioned central member, by configuring the optical fiber composite overhead ground wire using the optical fiber aggregate, without increasing the diameter, It is possible to realize the multi-core optical fiber in the optical fiber composite overhead ground wire.

Further, according to the invention of claim 2, in addition to the effect of the invention of claim 1, the rod-shaped main body of the central member to be coated is formed of FRP, and the wettability with the UV resin is extremely poor. However, the addition of silicone to the UV resin dramatically improves the wettability,
It is possible to stabilize the adhesion of the silicone-added UV resin to the FRP rod-shaped main body and prevent the inclusion of air bubbles. As a result, the FRP rod-shaped main body also has an even and smooth outer peripheral surface as described above. Therefore, it is possible to prevent the increase of the lateral pressure loss with respect to each optical fiber core wire due to the variation of the outer diameter and the occurrence of the unevenness. Further, since the central member is configured as a tensile strength member, it can be a resistance element that resists the tensile force acting on the optical fiber assembly.

Further, according to the third aspect of the invention, as described in the effect of the first aspect of the invention, by forming a coating layer on the central member using a silicone-added UV resin, the optical fiber assembly is formed. Even if a small diameter UV coated fiber having a relatively thin coating thickness for the optical fiber is used as the optical fiber core wire constituting the body, its lateral pressure loss can be suppressed to the same level as or lower than that of the conventional one. It is possible to reduce the diameter of the optical fiber assembly formed of the UV-coated fibers. Therefore, an optical fiber unit structure in which the above-mentioned optical fiber aggregates are arranged in the protection pipe having the same diameter as the conventional eight pipes, which is more than four in the conventional case, becomes possible. The number of optical fibers in the optical fiber can be increased without increasing the diameter of the optical fiber unit, and the diameter of the optical fiber assembly can be decreased to increase the diameter of the central interposition member. Therefore, by using this central interposition member as a tensile strength member, it is possible to further increase the safety margin for the acting tension.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view in which the optical fiber composite overhead ground wire of FIG. 1 is sequentially broken from the outer peripheral side.

3 is an enlarged sectional view of the optical fiber assembly in FIG.

FIG. 4 is a cross-sectional view of a secondary tensile strength member coated with a silicone resin.

FIG. 5 is a view corresponding to FIG. 1 of a conventional optical fiber composite overhead ground wire.

6 is a view corresponding to FIG. 2 of the optical fiber composite overhead ground wire of FIG. 5.

7 is a view of the optical fiber assembly in FIG. 5 corresponding to FIG.

[Explanation of symbols]

 1 Protective Pipe 2 Main Tensile Member (Center Intervening Member) 3 Optical Fiber Assembly 7 Sub Tensile Member (Center Member) 7a Rod-shaped Main Body 7b Coating Layer 8 Optical Fiber Core

Claims (3)

[Claims] 1. A rod-shaped center member formed of an insulating material and arranged at the center of an optical fiber assembly and having a circular cross section, wherein a plurality of optical fiber core wires surround the center member. A central member for an optical fiber assembly, which is arranged in a circumferential direction and is bundled in a state of being in contact with the outer peripheral surface of each of the central members to form an optical fiber assembly, wherein the central member is a rod-shaped main body having a circular cross section. A central member for an optical fiber assembly, comprising a coating layer for coating an outer peripheral surface of the main body, wherein the coating layer is formed by coating a silicone-added ultraviolet curable resin. 2. The central member for an optical fiber assembly according to claim 1, wherein the rod-shaped main body of the central member is formed of glass fiber reinforced plastics and configured as a tensile strength member. 3. A protective pipe, a central interposition member arranged along an axis of the protective pipe, and a circumferential direction along an outer peripheral surface of the central interposition member between the central interposition member and the protective pipe. Eight optical fiber assemblies arranged, each optical fiber assembly is provided with one center member and six optical fiber core wires arranged so as to surround the center member. And the central member and the optical fiber core wires are formed to have the same outer diameter as each other, the optical fiber core wires are respectively in contact with the central member, and are adjacent to each other in the circumferential direction. The optical fiber core wires are arranged and bundled so as to contact each other, and the central member is composed of a rod-shaped main body having a circular cross section and a coating layer that coats the outer peripheral surface of the main body. Is UV light with silicone addition Optical fiber composite overhead ground wire, characterized in that the resin is formed by coating.