JP2003344728A - Fiber optic cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve adhesiveness between an optical fiber core wire and a tensile strength member in an optical fiber cable in which an optical fiber core wire and a tensile strength member are collectively coated with a jacket material, and furthermore, a manufacturing process. To provide an optical fiber cable that can be easily used. SOLUTION: Tensile members 2 are arranged on both sides of an optical fiber core 1, and these are collectively coated. As a material of the coating 3, an adhesive resin material is used. The adhesion between the tensile strength member and the coating can be increased, and the shrinkage of the coating,
Meandering can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable for communication.

[0002]

2. Description of the Related Art FIG. 3 is a cross-sectional view of a prior art optical fiber cable previously proposed by the present applicant, as described in Japanese Patent Laid-Open No. 2000-171673. In the figure,
Reference numeral 1 is an optical fiber core wire, 2 is a strength member, 3 is a coating, 4 is a notch portion, and 7 is an adhesive layer.

This optical fiber cable is mainly used as a drop cable (cable for pulling down) from an underground cable.
Place the strength members 2 on both sides of the
Has been applied. Since the optical fiber core wire 1 and the tensile strength member 2 are collectively covered, the tensile strength member 2 bears the tension applied to the optical fiber cable and protects the optical fiber core wire 1 from an external force. By providing the notch portion 4, it becomes easy to tear the coating 3 from the notch portion 4 and take out the optical fiber core wire 1.

FIG. 4 is a cross-sectional view of a prior art fiber optic cable primarily used as a drop cable from an overhead cable. In the figure, the same parts as in FIG.
The same reference numerals are given and the description is omitted. Reference numeral 5 is a support line, 6 is a connecting portion, and 8 is an adhesive layer. In this optical fiber cable, an optical fiber cable main body portion having a structure similar to that shown in FIG. Since the connecting portion 6 is formed thin, it is easy to divide the optical fiber cable main body portion from the support wire portion. Since it is integrated with the support wire 5, it can be installed in the air.

A thermoplastic resin such as PVC is used as the coating 3 in this prior art optical fiber cable. Adhesive layer 7 in this optical fiber cable,
In the case where 8 is not provided, the optical transmission loss increases or the cable is housed in the cable when bending, ironing, etc. is applied, or when heat history such as heat cycle is applied in addition to these. There was a case where an abnormality such as a break of the existing optical fiber core occurred.

When the optical fiber cable in which such an abnormality has occurred is investigated, there is almost no adhesion between the strength member 2 and the thermoplastic resin coating 3 in the portion showing the local abnormality in the transmission loss. It was confirmed that the coating 3 contracted or meandered by bending, ironing, or heat cycle.

When the coating 3 of the optical fiber cable meanders, it is presumed that the optical fiber core wire 1 accommodated inside the coating 3 locally bends, resulting in an increase in transmission loss. In addition, the rapid bending of the optical fiber causes a large strain, causing a break in the optical fiber core wire, etc.
There is also a problem that the long-term reliability is deteriorated.

In the optical fiber cable of the prior art, in an optical fiber cable in which the optical fiber core wire 1 and the tensile strength member 2 are collectively covered with a coating 3 made of a thermoplastic resin, a space between the tensile strength member 2 and the coating 3 is provided. In addition, an adhesive layer 7 capable of enhancing the adhesiveness between the strength member 2 and the coating 3 is interposed. In the case where the support wire 5 is provided in parallel with the main body of the optical fiber cable, the adhesive layer 8 is interposed between the support wire 5 and the coating 3 to bond the support wire 5 and the coating 3 together. Try to improve the sex.

In this optical fiber cable of the prior art, when the optical fiber core wire and the tensile strength member are collectively covered with a thermoplastic resin, the tensile strength member suppresses coating shrinkage and meandering by increasing the adhesiveness between the tensile strength member and the coating. This has the effect of suppressing an increase in loss and disconnection of the optical fiber core wire.

However, in this optical fiber cable of the prior art, since the resin layer is composed of two layers, two steps, that is, the step of applying the adhesive layer and the step of applying the coating are required, resulting in an increase in cost. There's a problem. There is also a method of using a tandem machine that continuously performs two-layer coating in one step, but there is a problem that the equipment scale becomes large because two extrusion equipments are required in one line.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and provides an optical fiber cable capable of enhancing the adhesiveness between the optical fiber core wire and the strength member and simplifying the manufacturing process. It is intended to be provided.

[0012]

DISCLOSURE OF THE INVENTION The present invention provides an optical fiber cable in which an optical fiber core wire and a tensile strength member are collectively covered with an outer jacket material, and the outer jacket material has adhesiveness with the tensile strength member. It is characterized by using an adhesive resin material which can be improved. As the adhesive resin material, an adhesive resin or a mixture of an adhesive resin and a thermoplastic resin can be used. In addition, flame-retardant polyolefin can be used as the thermoplastic resin.

[0013]

1 is a sectional view of a first embodiment of an optical fiber cable according to the present invention. In the figure, the same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, as the material of the coating 3 which is the outer coating material,
An adhesive resin material was used. The adhesive resin material has a property of increasing the adhesiveness between the tensile strength body 2 and the coating 3 more than the adhesive force between the tensile strength body 2 and the coating 3 when the resin material having no adhesiveness is used. To use. Therefore,
As the adhesive resin material, one having excellent adhesiveness to the tensile strength member 2 is preferable.

The longitudinal direction with respect to the cross section shown in FIG. 1 was formed so as not to be twisted. However, the coating 3 may be extruded so that the twist is applied at a constant pitch or an indefinite pitch, or the twist direction may be changed regularly or irregularly. Since the coating 3 is extruded and molded, the material of the coating 3 is preferably a resin having thermoplasticity. As the adhesive resin having thermoplasticity, for example, a modified polyolefin resin is generally used,
As a commercially available product, "Admer" (registered trademark) manufactured by Mitsui Chemicals or "Nac Ace" (registered trademark) manufactured by Nippon Unicar can be used.

The optical fiber core wire is not limited to a single-core optical fiber core wire, and an appropriate optical fiber core wire such as a tape-shaped optical fiber core wire or an optical unit can be used. As for the number, one or a plurality can be collectively coated with a coating resin together with the tensile strength member.

As described above, by using the adhesive resin material as the jacket of the optical fiber cable, it is not necessary to form a two-layer coating as in the prior art, and a tensile strength member can be formed by one coating step. It is possible to achieve both the adhesiveness of the jacket material and the adhesiveness of the jacket material. Further, by increasing the adhesiveness between the tensile strength member and the jacket material, it is possible to suppress shrinkage and meandering of the coating when ironing or bending is applied, and it is possible to prevent an increase in loss and occurrence of wire breakage.

The material of the coating 3 is not limited to the adhesive resin alone, but may be an adhesive resin formed by mixing a plurality of types of adhesive resins in advance, or substantially adhered to the adhesive resin. It may be a mixture such as a mixture of a thermoplastic resin having no property in advance, or the like. By using a resin having an adhesive property as an outer covering material, one coating step and a tensile strength member can be obtained. It is possible to achieve both adhesiveness of the jacket material. When the jacket material is required to have special properties such as flame retardancy and environmental resistance, the resin thus mixed is useful.

A specific example will be described. A specific example is an underground drop cable. As the optical fiber core wire 1, a single core optical fiber core wire having a coating outer diameter of 0.25 mm and coated with a UV resin was used, and as the tensile strength member 2, a steel wire having an outer diameter of 0.4 mm was used. The width in FIG. 1 is 2.0
mm, the total height is 2.6 mm, 0.4 m in the middle
A notch portion having a V-shaped cross section is formed in the opening of m. As the resin of the coating 3, an adhesive resin or a mixed material of an adhesive resin and a thermoplastic resin is used to strengthen the adhesion between the coating 3 and the steel wire. However, it goes without saying that the numerical values of this specific example do not limit the present invention and can be set to appropriate values.

FIG. 2 is a sectional view of a second embodiment of the optical fiber cable of the present invention. In the figure, the same parts as those in FIGS. 1, 3 and 4 are designated by the same reference numerals and the description thereof will be omitted.
Reference numeral 5 is a support line, and 6 is a connecting portion. In this embodiment,
A support wire 8 is provided along the optical fiber cable main body described with reference to FIG. 1 and is integrated with a common coating 3 and is similar to the optical fiber cable of the prior art described with reference to FIG. . The difference from FIG. 4 is that an adhesive resin material is used as the material of the coating 3 as in the first embodiment. Similar to the first embodiment, it is possible to achieve both the one-time coating step and the adhesiveness between the strength member and the jacket material.
Moreover, the adhesiveness between the support wire 5 and the coating 3 can be improved.

A specific example will be described. An example of this is
This is an optical drop cable used for aerial applications. Since the main body of the optical fiber cable is the same as the specific example in the first embodiment, its explanation is omitted. As the supporting wire 5, a steel wire having an outer diameter of 1.2 mm was used. The thickness of the coating 3 at the portion of the supporting wire 5 is 0.4 mm, and the height of the connecting portion 6 is 0.2 mm. Also in this specific example, the above numerical values do not limit the present invention, and it goes without saying that they can be set to appropriate values.

In each of the specific examples described above, a steel wire was used as a tensile strength member, but the tensile strength member of the present invention is not limited to a steel wire or a steel stranded wire, but other metal wires. Alternatively, an appropriate material capable of reinforcing tension such as FRP can be used.

[0022]

As is apparent from the above description, according to the present invention, in an optical fiber cable in which an optical fiber core wire and a tensile strength member are collectively covered with a jacket material, the optical fiber core wire and the tensile strength member are provided. It is possible to improve the adhesiveness with the cable, and the manufacturing cost can be reduced because the cable manufacturing process is performed only once. Also, large-scale equipment such as tandem machines is not required.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of an optical fiber cable of the present invention.

FIG. 2 is a sectional view of a second embodiment of the optical fiber cable according to the present invention.

FIG. 3 is a cross-sectional view of a prior art fiber optic cable.

FIG. 4 is a cross-sectional view of a prior art fiber optic cable.

[Explanation of Codes] 1 ... Optical fiber core wire, 2 ... Tensile member, 3 ... Coating, 4 ... Notch portion, 5 ... Support wire, 6 ... Connecting portion, 7, 8 ... Adhesive layer.

Claims (3)

[Claims] 1. An optical fiber cable in which an optical fiber core wire and a tensile strength member are collectively covered with an outer jacket material, and an adhesive resin capable of enhancing adhesiveness with the tensile strength member as the outer jacket material. An optical fiber cable characterized by using a material. 2. The optical fiber cable according to claim 1, wherein the adhesive resin material is an adhesive resin or an adhesive resin mixed with a thermoplastic resin. 3. The optical fiber cable according to claim 2, wherein the thermoplastic resin is flame-retardant polyolefin.