JPH0968632A - Optical drop wire - Google Patents

Abstract

(57) An object of the present invention is to provide an optical drop wire that can be manufactured by a small number of processes, is low in cost, and has low loss. SOLUTION: A plastic jacket forming a cavity for housing an optical fiber core and a plastic jacket of a supporting wire are joined and integrally molded, and an optical fiber core is movably in the cavity. It is housed. Slits may be provided at appropriate intervals at the joint between the outer cover of the cavity and the outer cover of the support wire. Conveniently, the optical fiber core wire is a single-core coated optical fiber core wire having an outer diameter of 0.5 mm to 0.9 mm. Of course, it may be an optical fiber ribbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical drop used for pulling down an optical fiber from a drop point to a subscriber in an aerial wiring portion for wiring an optical fiber from an overhead optical cable to a subscriber via a drop point. It is about wires.

[0002] In the future, in addition to telephone service, CATV
(Cable TV), VOD (Video On Demand), and to provide high-speed and broadband services such as video services represented by videophones, access systems are all-optical, that is, FT.
TH (Fiber To The Home) is indispensable. This FT
In order to realize TH, it is particularly important to establish a technology capable of economically and efficiently pulling down an optical fiber from an overhead optical distribution cable to a subscriber.

FIG. 1 is a sectional view of an example of an optical drop wire currently in use. 1 is a single-core coated optical fiber core wire, 2 is a steel core of a supporting wire of the optical drop wire, and 3 is an optical drop wire. The plastic jacket 4 of the support wire is a plastic jacket of a portion in which the single-core coated optical fiber core wire is accommodated, and 5 is a reinforcing steel wire. In this wire, a portion in which the single-core coated optical fiber core wire is accommodated and a portion in which the support wire is accommodated are twisted and assembled. Here, an example of the structure in which only one single coated optical fiber core wire is mounted is shown.

[0004]

The optical drop wire having the structure shown in FIG. 1 has a drawback that the number of manufacturing steps for manufacturing the optical drop wire increases. That is, a step of applying a coating to the optical fiber to make a single-core coated optical fiber,
A process of arranging steel wires at both ends of the core wire and applying a plastic jacket to them, a process of applying a plastic jacket to the outer circumference of the support wire, a part containing the single-core coated optical fiber core wire and the support wire It is necessary to perform four steps of twisting and gathering the part that has been formed. Therefore, an increase in manufacturing cost cannot be avoided.

The object of the present invention is to manufacture in a small number of steps,
An object is to provide an optical drop wire that is low in cost and low in loss.

[0006]

In order to achieve the above-mentioned object, the optical drop wire of the present invention comprises a plastic jacket forming a cavity for accommodating an optical fiber core wire and a plastic jacket of a support wire. The optical fiber core wire is joined and molded integrally, and the optical fiber core wire is accommodated in the cavity so as to be movable. One or a plurality of single-core coated optical fiber cores or optical fiber tape cores having an outer diameter of 0.5 mm to 0.9 mm are accommodated in this cavity.

The optical drop wire of the present invention having such a structure, when accommodating a single-core coated optical fiber,
A core-forming step of applying a coating to an optical fiber element to form a single-core coated optical fiber core, and accommodating the single-core coated optical fiber core so as to be freely movable in an optical drop wire and a supporting wire. It can be manufactured in two steps, that is, an integrated extrusion process.

According to the present invention as described above, the manufacturing process of the optical drop wire can be reduced, and therefore the manufacturing cost can be reduced, and further, the single-core coated optical fiber core wire can be provided in the optical drop wire. Since it can be moved in the cross-sectional direction and the longitudinal direction with, it is possible to prevent the strain applied to the optical fiber core wire due to the expansion and contraction of the optical drop wire sheath due to the bending of the optical drop wire or the temperature change,
It is possible to suppress an increase in light loss.

Further, in the optical drop wire of the present invention, it is convenient to provide slits at appropriate intervals at the joint portion between the outer cover of the cavity and the outer cover of the support wire. By doing so, there is an advantage that the work of separating the support wire portion and the optical fiber core wire accommodating portion becomes easy when the optical drop wire is retained on the electric pole.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a sectional view of an optical drop wire according to a first example of the present invention. In this figure, 11 is a support line part,
12 is an optical fiber core receiving part, 13 is a steel core of a supporting wire, 14 is a plastic jacket of the supporting wire part, 15 is a cavity for housing the optical fiber core wire, 16 is a plastic jacket of the optical fiber core wire containing part. , 17 is an optical fiber core wire, and 18 is a joint portion between the support wire portion and the optical fiber core wire accommodation portion. In the cavity 15 for accommodating the optical fiber core wire, one or a plurality of single-core coated optical fiber core wires or tape core wires are movably accommodated. The state where the book is fully accommodated is shown.

The optical drop wire of the present invention having such a structure that the fiber core wire is housed in the cavity as described above, in the case of housing the single-core-coated optical fiber core wire, the optical fiber element wire is coated to form a single-core coating. Manufactured in two steps: an optical fiber core wire forming step and a single core coated optical fiber core wire which is housed so as to be freely movable in the optical drop wire and is integrated with the supporting wire. can do.

In this case, it is preferable that the single-core coated optical fiber has an outer diameter of 0.5 mm to 0.9 mm. If the optical fiber core is thicker than this, the entire optical drop wire becomes thicker and difficult to handle. Conversely, if the optical fiber core is thin, the handling characteristics of the optical fiber core itself deteriorate, and when the optical fiber core wire is handled at the connection part. Comes with an increase in light loss. The handling characteristics are closely related to the method of accommodating the optical fiber core wire at the connection part, but the outer diameter is 0.5 mm to 0.9 mm.
Within the range, the increase in optical loss can be suppressed to be small.

In addition, when the optical fiber core is housed so as to be freely movable in the housing cavity, the drop wire jacket expands or contracts due to temperature change, or the optical drop wire is subjected to bending force. However, it is possible to prevent the optical fiber core wire from moving in the cross-sectional direction and the longitudinal direction within the wire and applying strain to the optical fiber core wire, and it is possible to prevent optical loss due to such distortion.

When the optical drop wire of the present invention is retained on the electric pole, the supporting wire portion 11 and the optical fiber core wire accommodating portion 12 are separated over a length of about 50 cm as shown in FIG. Attach it to the retaining device 23 and retain it. In this figure, 21 is an electric pole, 22 is an L-shaped metal object, and 24 is a protective tape for separating the support wire portion 11 and the optical fiber core wire accommodation portion 12.

Since the supporting wire portion 11 and the optical fiber core wire receiving portion 12 are separated at the holding portion of the electric pole, the influence of expansion and contraction of the plastic jacket of the optical fiber core wire receiving portion 12 becomes large, but the optical fiber core wire is large. It is possible to prevent an increase in the optical loss by moving in the cross section direction and the longitudinal direction inside the cavity 15.

FIG. 4 shows a perspective view of an optical drop wire according to a second example of the present invention. In this example, slits 19 are provided at appropriate intervals in a joint portion 18 between the support wire portion 11 and the optical fiber core wire accommodation portion 12. This can be manufactured in two steps as in the case of the above-mentioned first example, since the optical drop wire can be manufactured by extrusion forming the plastic jacket while providing slits at regular intervals, for example. By providing this slit, when the optical drop wire is retained on the electric pole as shown in FIG. 3, the support wire portion and the optical fiber core wire accommodating portion can be easily separated.

In the above description with reference to the drawings, the case where only one single-core coated optical fiber core wire is accommodated in the cavity of the optical drop wire has been described. However, in the optical drop wire of the present invention, if necessary. As a matter of course, an optical fiber tape core wire may be used, and a plurality of core wires may be accommodated without being limited to one.

[0018]

According to the present invention, as described above,
The number of steps for manufacturing the optical drop wire can be reduced, and thus the manufacturing cost can be reduced. Further, according to the present invention, since the optical fiber core wire can be moved in the cross-sectional direction and the longitudinal direction within the optical drop wire, the optical fiber core wire is bent by the bending of the optical drop wire or the expansion and contraction of the jacket accompanying the temperature change. It is possible to reduce the distortion applied to the optical disk and to suppress the increase of the optical loss.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of a currently used optical drop wire.

FIG. 2 is a cross-sectional view of an optical drop wire according to a first example of the present invention.

FIG. 3 is a diagram illustrating a portion where an optical drop wire of the present invention is retained on an electric pole.

FIG. 4 is a perspective view of an optical drop wire according to a second example of the present invention.

[Explanation of symbols]

1 Single-core-coated optical fiber core wire 2 Steel core of support wire 3 Plastic sheath of support wire 4 Plastic sheath of the part where the single-core coated optical fiber core wire is accommodated 5 Steel wire for reinforcement 11 Support wire portion 12 Optical fiber core housing part 13 Steel core of support wire 14 Plastic sheath of support wire part 15 Cavity for housing optical fiber core wire 16 Plastic jacket of optical fiber core wire housing part 17 Optical fiber core wire 18 Support wire part Joining part with the optical fiber core housing part 19 Slit 21 Power pole 22 L-shaped metal object 23 Pulling tool 24 Support tape for separating the supporting wire part 11 and the optical fiber core housing part 12

Claims (4)

[Claims] 1. A plastic outer sheath forming a cavity for accommodating an optical fiber core and a plastic outer sheath of a support wire are joined and integrally molded, and the optical fiber core is movable in the cavity. An optical drop wire characterized by being housed in. 2. The optical drop wire according to claim 1, wherein slits are provided at appropriate intervals at a joint portion between the outer cover of the cavity and the outer cover of the support wire. 3. The optical drop wire according to claim 1, wherein the optical fiber core wire is a single-core coated optical fiber core wire having an outer diameter of 0.5 mm to 0.9 mm. 4. The optical drop wire according to claim 1, wherein the optical fiber core wire is an optical fiber tape core wire.