JP2004361475A - Fiber optic cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable in which a plurality of coated optical fibers are directly stored in the coated resin of the cable body without preliminarily being made into a tape, in which the plurality of the coated optical fibers are bent all in the same bending radius with respect to the bend of the cable body, and in which the fiber length is also uniform. <P>SOLUTION: In the optical fiber cables 10, 10', a plurality of coated optical fibers 1 are stored in the air gap 5 inside the coating resin 4 of the cable body that is provided with an easily bendable surface. The cross section of the air gap 5 is formed long sideways in the direction parallel to the easily bendable surface of the cable body. The long-sideways cross section of the air gap 5 is either rectangular or oblong. By making the major side longer than the sum total of the outer diameters of the stored coated optical fibers 1, the plurality of coated optical fibers 1 are designed to be stored in one row. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical fiber cable in which a plurality of optical fiber core wires are housed in a cable body made of a coated resin body and used for indoor or outdoor wiring or withdrawal.
[0002]
[Prior art]
Conventionally, various types of optical fiber cables, such as self-supporting optical fiber cables for overhead wiring, drop-down optical fiber cables for branching and dropping a part of this cable, and optical fiber cables for indoor wiring used for wiring of apartment houses and the like. Fiber cables are known. These optical cables are relatively lightweight and small-sized optical fiber cables having several to several tens of optical fibers having a small number of cores.
[0003]
FIGS. 2A and 2B are diagrams illustrating an example of a conventional optical fiber cable suitable for use in the above-described indoor and outdoor wiring. In the figure, 1 is an optical fiber core wire, 2 is a fibrous inclusion, 3 is a tensile strength wire, 4 is a coating resin body of a cable body, 5 is a void, 6 is a cut groove, 7 is a support wire coating, and 8 is a support wire coating. The neck, 9 indicates a support wire, and 10 and 10 'indicate optical fiber cables.
[0004]
The optical fiber cable 10 shown in FIG. 2A has a circular gap 5 in the center of the covering resin body 4 of the cable body, and the fibrous inclusions 2 for buffering the lateral pressure are provided in the gap 5. And accommodates a plurality of optical fiber cores 1. Tensile strength wires 3 are integrally buried on both sides of the gap portion 5, and a tear groove 6 is formed to make it easy to take out the optical fiber core 1 for branching or dropping. In such an optical fiber cable 10, since the circular void portion 5 accommodating the plurality of optical fiber cores 1 and the tensile strength wire 3 are arranged in a line, the covering resin body 4 of the cable body has a large width dimension a. It has an irregular shape with a thin width dimension b. For this reason, the optical fiber cable 10 is generally easy to bend on the width dimension b side where the thickness is small. Hereinafter, the center X on the width dimension b side where the thickness is small will be described as an “easy bending surface”.
[0005]
The optical fiber cable 10 ′ of FIG. 2B is configured as a self-supporting type optical fiber cable, and has the same configuration as the optical fiber cable 10 of FIG. is there. The support wire 9 is formed by twisting a plurality of steel wires, galvanized steel wires, or the like or a single wire, and integrally forms the support wire coating 7 with the coating resin body 4 of the cable main body via the neck 8. . Usually, the support wire portion is provided on an extension of the center X of the easily bendable surface of the coating resin body 4 of the cable body.
[0006]
FIG. 3A is a view schematically showing a method of manufacturing the above-described optical fiber cable, and FIG. 3B is a view showing a state in which the optical fiber cable is being taken. In the figure, 11 is an optical fiber core supply reel, 12 is a fiber supply reel, 13 is a wire supply reel, 14 is a coating molding device, 15 is a coating cooling device, 16 is a capstan wheel, and 17 is a winding drum. .
[0007]
As shown in FIG. 3A, the optical fiber cable 10 is supplied with a plurality of optical fiber cores 1 from an optical fiber core supply reel 11, and has a fibrous intervening longitudinally attached to the optical fiber core 1. The object 2 is supplied from the fiber material supply reel 12. Further, the tensile strength wire 3 is supplied from the wire supply reel 13, the coating resin body 4 of the cable body is extruded by the coating molding device 14, and is cured by the cooling device 15. After the coated resin body 4 of the optical fiber cable 10 is formed and cooled, it is wound around a capstan wheel 16, taken up, and wound up on a winding drum 17.
[0008]
When the optical fiber cable 10 is taken out by the capstan wheel 16, the optical fiber cable 10 is wound so that the easily bendable surface of the cable body is parallel to the rotation axis of the capstan wheel 16, as shown in FIG. Will be taken over. When the cooled optical fiber cable 10 is pulled off by the capstan wheel 16, the storage position and state of each optical fiber core 1 in the coating resin body 4 are determined, and the fiber characteristics are often determined. The optical fiber cable 10 is wound around the outer peripheral surface of the capstan wheel 16 around the center X of the easily bendable surface of the coating resin body 4, and at this time, each optical fiber core 1 itself is coated with a tension. In the cavity 5 of the resin body 4, the resin body 4 is offset and taken off so as to stick to the capstan wheel 16 side.
[0009]
However, the arrangement of the optical fiber core wires 1 in the gap 5 is not constant because the cross section of the gap 5 is usually circular and the fibrous inclusions 2 are vertically attached. With respect to the capstan wheel 16, the plurality of optical fiber cores 1 housed in the gaps 5 of the coating resin body 4 are such that the fiber located at the center X of the easily bendable surface has a bending radius Rx and a bending radius Rx. The fiber located inside the center X is wound with the bending radius Rxi, and the fiber located outside the bending center X is wound with the bending radius Rxo. That is, the optical fiber core wires 1 have different bending diameters, resulting in a difference in fiber length, and as a result, distortion and transmission characteristics of each optical fiber may be non-uniform.
[0010]
On the other hand, it is also known that, for example, after a plurality of optical fiber cores are previously formed into a tape shape, a tensile strength wire or the like is longitudinally added, and a coated resin body is integrally molded to form an optical fiber cable. (For example, see Patent Documents 1 and 2). In each of these patent documents, a cable in which a plurality of optical fiber cords or optical fiber cords are integrated in a tape shape in advance and further coated with a resin body is formed. According to this configuration, a plurality of optical fiber core wires can be arranged in a line in parallel and embedded in the covering resin body. As a result, by making the plurality of optical fiber cores taped to coincide with the center X shown in FIG. 3 (B), the plurality of optical fiber cores have uniform bending and length. It is possible to take over.
[0011]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-243884 (FIG. 10)
[Patent Document 2]
JP-A-11-174291 (FIG. 6C)
[0012]
[Problems to be solved by the invention]
However, the optical fiber cable disclosed in Patent Document 1 or 2 described above requires a plurality of optical fiber cores to be integrally taped with a common coating in advance, which increases the number of manufacturing steps for making the cable, The cost is high. In addition, the optical fiber cable may be branched for drop-down connection or the like. In this case, it is necessary to tear the coated resin body of the cable body to take out the taped optical fiber core, and to tear the taped coating to take out the optical fiber core inside, which is inferior in workability.
[0013]
The present invention has been made in view of the above-described circumstances, and has a configuration in which a plurality of optical fiber cores are directly housed in a coating resin body of a cable body without being taped in advance, and a plurality of optical fiber cores are provided. An object of the present invention is to provide an optical fiber cable in which an optical fiber core wire is bent with a substantially uniform bending diameter and a fiber length is also substantially uniform with respect to bending of a wire in a manufacturing stage of a cable body.
[0014]
[Means for Solving the Problems]
An optical fiber cable according to the present invention is an optical fiber cable in which a plurality of optical fiber cores are accommodated in a gap portion in a coating resin body of a cable body having an easily bendable surface, and the cross section of the gap portion is a cable body. Is formed so as to be horizontally long in a direction parallel to the easy bending surface. In addition, the laterally long cross section of the void portion is rectangular or oblong, and its long side is desirably equal to or larger than the sum of the outer diameters of the stored optical fiber cores, and a plurality of optical fiber cores are arranged in a line. Is possible.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIG. 1A illustrates an example of an optical fiber cable used for indoor or outdoor wiring, and FIG. 1B illustrates an example of a self-supporting type optical fiber cable. The reference numerals in the figure are the same as those used in FIG.
[0016]
An optical fiber cable 10 shown in FIG. 1A has a gap 5 for accommodating a plurality of optical fiber cores 1 in the center of a coating resin body 4 of the cable body. It is housed through the fibrous inclusion 2. The gap 5 is formed, for example, in a rectangular shape, and its long side is larger than the sum of the diameters of the plurality of optical fiber core wires 1. For example, when one optical fiber core has an outer diameter of 0.25 mm and accommodates six optical fiber cores, the length of the long side of the gap 5 is 1.5 mm or more, preferably 2. It is molded so as to be about 0 mm.
[0017]
The plurality of optical fiber cores 1 are arranged in a line when the coated resin body 4 is formed, and the coated resin body 4 is extruded in a loose structure. If necessary, a fiber inclusion 2 for buffering the lateral pressure is vertically attached to the optical fiber 1, and the coated resin body 4 is extruded in a loose structure. Further, tensile strength lines 3 are integrally embedded on both sides of the long side of the rectangular gap 5 as in FIG.
[0018]
As a result, the covering resin body 4 of the cable main body has an irregular shape having the thick width dimension a and the thin width dimension b, and the surface having the center of the thin width dimension X as X is easily bent with respect to other surfaces. It shows the property and becomes the surface easy to bend. The cross section of the gap portion 5 has a shape that is horizontally long in a direction parallel to the easy bending surface. A tear groove 6 is formed on the surface side of the thin resin member 4 with the small width dimension b along the axial direction so that the optical fiber core 1 can be easily taken out at the time of branching or dropping.
[0019]
As described with reference to FIG. 3, when the optical fiber cable 10 configured as described above is wound around the capstan wheel 16 at the time of manufacturing, a plurality of optical fiber cores are set around the center X of the easily bendable surface. 1 are aligned so as to line up in a horizontally long gap 5 in the coating resin body 4. As a result, the plurality of optical fiber core wires 1 can be uniformly bent on the capstan wheel at the bending center X, and can be taken up by the capstan wheel with the same fiber length and wound on the winding drum.
Further, since all the optical fiber core wires 1 are uniformly and directly contacted (or stuck) inside the bend of the gap 5 due to the tension at that time, the pulling force can be increased.
[0020]
The self-supporting type optical fiber cable 10 'shown in FIG. 1B has almost the same configuration as the optical fiber cable 10 of FIG. The support wire 9 is formed by twisting a plurality of steel wires, galvanized steel wires, or the like or a single wire, and integrally forms the support wire coating 7 with the coating resin body 4 of the cable main body via the neck 8. . Usually, the supporting wire portion is provided on an extension of the width dimension a where the thickness of the coating resin body 4 is large.
[0021]
FIG. 1B shows an example in which the gap 5 is formed in an oblong shape when it is difficult to form the gap 5 in a rectangular shape as in FIG. 1A. The long-elliptical void portion 5 has its long side larger than the sum of the diameters of the plurality of optical fibers 1. For example, as in the case of FIG. 1A, when one optical fiber core has an outer diameter of 0.25 mm and accommodates six optical fiber cores, the length of the long side of the gap 5 is Is formed to be 1.5 mm or more, preferably about 2.0 mm. When molding the covering resin body 4 of the cable body, the plurality of optical fiber core wires 1 are arranged in a line, and the covering resin body 4 is extruded in a loose structure so as to form the oblong space 5. Further, if necessary, the fibrous inclusions 2 are vertically attached to the optical fiber 1 and the coated resin body 4 is extruded in a loose structure. It is to be noted that molding of the oblong void 5 is easier than the rectangular shape of FIG.
[0022]
When the optical fiber cable 10 ′ configured as described above is wound around a capstan wheel at the time of manufacturing, the plurality of optical fiber cores 1 are covered with the same as described with reference to FIG. It is aligned so as to be substantially aligned in the elongated elliptical void portion 5 in the resin body 4. As a result, the plurality of optical fiber cores 1 are bent almost uniformly on the capstan wheel near the bending center X, the fiber lengths are also made substantially equal, and the optical fiber 1 is taken up by the capstan wheel and wound on the winding drum. Can be.
Further, since all the optical fiber cores 1 are uniformly and directly contacted (or stuck) inside the bend of the gap 5 due to the tension at that time, the pulling force can be increased.
[0023]
【The invention's effect】
As described above, according to the present invention, a plurality of optical fiber cores can be stored in a line in a coating resin body of a cable body without being taped in advance, and a cable manufacturing step of a plurality of optical fiber cores is performed. The fiber diameter can be made uniform so that a difference in fiber length does not occur. Thereby, the transmission characteristics of each optical fiber core can be made uniform without lowering the workability of branching the optical fiber cable. Further, the pulling force of each optical fiber from the cable can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a conventional optical fiber cable.
FIG. 3 is a diagram illustrating a conventional method for manufacturing an optical fiber cable.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical fiber core wire, 2 ... Fibrous inclusion, 3 ... Tensile wire, 4 ... Coated resin body, 5 ... Void, 6 ... Cut groove, 7 ... Support wire coating, 8 ... Neck, 9 ... Support wire 10, 10 'optical fiber cable, 11 optical fiber core supply reel, 12 fiber supply reel, 13 wire supply reel, 14 coating forming apparatus, 15 coating cooling apparatus, 16 capstan wheel, 17 ... winding drum.

Claims (7)

An optical fiber cable in which a plurality of optical fiber cores are accommodated in a gap in a coating resin body of a cable body having an easily bendable surface, wherein a cross section of the gap is parallel to the easily bendable surface of the cable body. An optical fiber cable characterized by being formed horizontally long in various directions. The optical fiber cable according to claim 1, wherein a long side of the horizontal section of the gap is equal to or larger than a sum of outer diameters of the optical fibers to be stored. The optical fiber cable according to claim 1, wherein a horizontal cross section of the gap is rectangular. The optical fiber cable according to claim 1, wherein a laterally long cross section of the gap has an elliptical shape. The optical fiber cable according to any one of claims 1 to 4, wherein the plurality of optical fibers are housed in the gap via a fiber inclusion. The optical fiber cable according to any one of claims 1 to 5, wherein a tensile strength wire is buried in the covering resin body of the cable body so as to be located on both sides of a horizontal cross section of the gap. . The optical fiber cable according to claim 6, wherein a support wire portion is provided on a line connecting the tensile wires on both sides.

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