JP2017009924A - Optical fiber unit, optical fiber cable, and manufacturing method for optical fiber unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber unit which can be manufactured at low cost and offers superior branching workability.SOLUTION: An optical fiber unit 1 comprises a bundle of optical fibers 3, bundling material 5, and others. One bundling material 5 is provided on an outer periphery of the plural bundle of optical fibers 3. The bundling material 5 is spirally wound around the plural bundle of optical fibers 3. Since the bundling material 5 is designed to maintain its spirally-wound shape by itself even when the bundling material 5 alone is cut out from the optical fiber unit 1, the bundle of optical fibers 3 is kept intact by the spirally-wound shape of the bundling material 5 and, as such, there is no need to tightly wind the bundling material 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical fiber unit that can be manufactured at low cost.

  In recent years, with the widespread use of the Internet, FTTH (Fiber To The Home) that realizes a high-speed communication service by directly drawing an optical fiber into a general household is rapidly expanding. In general, an optical fiber cable used for FTTH accommodates a collection of optical fibers so as to be compatible with large-capacity data communication.

  Here, the aggregate of optical fibers is formed by aggregating a plurality of optical fiber ribbons, for example. Moreover, what bundled this optical fiber assembly with the bundle material is named generically, and is called the optical fiber unit.

  As such an optical fiber unit, for example, there is one in which a plurality of optical fiber core wires are formed by spirally winding two strings, which are bundle materials, in directions opposite to each other (Patent Document 1).

  In addition, an optical fiber unit is proposed in which a bundle of optical fibers is bundled and a plurality of bundle materials are spirally wound in the longitudinal direction, and the bundle materials are bonded to each other at the intersection where the two intersect. (Patent Document 2).

Japanese Patent Laid-Open No. 9-26534 JP 2011-169939 A

  However, since two bundle materials are used, there is a problem that a material cost and a manufacturing cost are required.

  However, when only one bundle material is wound, the holding power of the optical fiber aggregate by the bundle material is not sufficient, and there is a possibility that the inner optical fiber ribbon or the like jumps out of the optical fiber unit. For this reason, there is a possibility that the discriminability and the branching workability are deteriorated.

  The present invention has been made in view of such problems, and an object thereof is to provide an optical fiber unit or the like that can be manufactured at low cost.

  In order to achieve the above-described object, the first invention includes a plurality of optical fiber cores and a single bundle material made of a thermoplastic resin spirally wound around the outer periphery of the plurality of optical fiber cores. The bundle material is an optical fiber unit that maintains a spiral shape by its shape retention.

  The bundle material may be formed of a plurality of layers of resins of different materials, and the amount of heat shrinkage of the resin on the inner surface side may be larger than the amount of heat shrinkage of the resin on the outer surface side.

  According to the first invention, since the bundle material is held in a spirally wound shape, the optical fiber assembly can be reliably held even with only one bundle material. For this reason, branch workability is good. Moreover, since it is not necessary to use two bundle materials, it can manufacture at low cost.

  Moreover, if the bundle material is composed of a plurality of layers and the amount of heat shrinkage of the resin on the inner surface side is larger than the amount of heat shrinkage of the resin on the outer surface side, the spirally wound shape can be more reliably maintained.

  A second invention is an optical fiber cable comprising a plurality of optical fiber units according to the first invention, a tension member, and a jacket provided on an outer periphery of the optical fiber unit.

  According to the second invention, an optical fiber cable that can be manufactured at low cost can be obtained.

  According to a third aspect of the present invention, there is provided a step of bundling a plurality of optical fiber cores and spirally winding one bundle material made of a thermoplastic resin around an outer periphery of the optical fiber core wire, A method of manufacturing an optical fiber unit, comprising: a step of heating to a temperature; and a step of cooling the bundle material to room temperature.

  According to the third invention, an optical fiber unit that can be manufactured at low cost can be easily obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the optical fiber unit etc. which can be manufactured at low cost can be provided.

The figure which shows the optical fiber unit 1. FIG. (A) is a figure which shows the optical fiber cable 10, (b) is a figure which shows the optical fiber cable 10a.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an optical fiber unit 1. The optical fiber unit 1 includes an optical fiber core wire 3, a bundle material 5, and the like.

  The optical fiber core wire 3 may be a single wire or a tape core wire. The number of the optical fiber cores 3 is not limited to the illustrated example. One bundle member 5 is provided on the outer periphery of the plurality of optical fiber cores 3. The bundle material 5 is a member made of a thermoplastic resin, and for example, PET (polyethylene terephthalate), polyethylene, polypropylene, nylon, or the like can be applied. Further, a material obtained by mixing a plurality of thermoplastic resins may be used, and different materials may be formed in a plurality of layers.

  Although the form of the bundle material 5 is not ask | required, it is desirable to set it as the tape shape with a certain amount of width. By making the bundle material 5 into a tape shape having a predetermined width or more, the bundle material 5 can be easily identified. However, if the bundle material 5 is too wide, the tape may stand up when wound. For this reason, as a width | variety of the bundle material 5, about 1.0-2.5 mm is desirable, for example.

  The bundle material 5 is spirally wound around the outer periphery of the plurality of optical fiber core wires 3. As for the winding pitch of the bundle material 5, the finer one is discriminability and bundle feeling (the degree to which the optical fiber cores 3 are held as a bundle, and the optical fiber cores 3 are bundled without being scattered. The feeling of bundle is high, and it is assumed that the bundle feeling is low when the optical fiber core wire 3 is broken. On the other hand, when the winding pitch of the bundle material 5 becomes too narrow, workability at the time of taking out the optical fiber core wire 3 is deteriorated. For this reason, it is desirable that the winding pitch of the bundle material 5 is 25 mm to 150 mm.

  Here, the bundle material 5 holds the spirally wound shape. That is, even if only the bundle material 5 is cut out from the optical fiber unit 1, the bundle material 5 maintains the spirally wound shape due to the self-shape retention. Therefore, the optical fiber core wire 3 is held in a bundle by the spiral shape of the bundle material 5.

  Next, a method for manufacturing the optical fiber unit 1 will be described. First, a plurality of optical fiber core wires 3 supplied from the optical fiber core wire supply unit are bundled to form an optical fiber core wire bundle. Next, one bundle material 5 is spirally wound around the outer periphery of the optical fiber core bundle.

  Next, the bundle material 5 is heated at a temperature not lower than the softening temperature and not higher than the melting temperature. As a heating method, for example, a heating furnace or a dryer can be used.

  Next, the bundle material 5 is cooled to room temperature. For cooling, a cold air dryer or the like may be used, or natural cooling may be used. Thus, the optical fiber unit 1 can be manufactured.

  Here, if the bundle material 5 is composed of a plurality of layers and is made of different materials, and the amount of heat shrinkage of the resin on the inner surface side is larger than the amount of heat shrinkage of the resin on the outer surface side, the spiral shape can be easily maintained. Specifically, by forming a layer of a material with a relatively large amount of heat shrinkage on the inner surface side when wound, and forming a layer of a material with a relatively small amount of heat shrinkage on the outer surface side, a spiral shape It becomes easier to hold.

  Next, an optical fiber cable using the optical fiber unit 1 will be described. FIG. 2A is a cross-sectional view showing the optical fiber cable 10. A plurality of optical fiber units 1 obtained by the above-described method are twisted together, and a buffer body 11 such as polypropylene yarn is provided on the outer periphery thereof to form a cable core. Further, an outer sheath 13 made of polyethylene or the like is extruded and coated on the outer periphery of the obtained cable core together with the tension member 15 made of steel wire or the like and the tear string 17. That is, a pair of tension members 15 are provided inside the jacket 13 at positions facing each other across the cable core, and are opposed to each other across the cable core in a direction substantially perpendicular to the facing direction of the tension member 15. A tear string 17 is provided.

  Here, when the outer cover 13 is extrusion-coated, heat may be applied to the optical fiber unit 1. Therefore, as described above, a method of using the heat at the time of extruding the outer jacket 13 for the heating for maintaining the shape of the bundle material 5 is also conceivable.

  However, the heat at the time of extruding the jacket 13 is insulated by the buffer 11. Further, the position of the optical fiber unit 1 in the cross section and the circumferential portion of the optical fiber unit 1 cannot be heated uniformly. Such uneven heating makes it difficult to maintain the shape due to partial heating shortage. Therefore, in this invention, it shall heat at the time of manufacture of the optical fiber unit 1, and shall maintain the shape of the bundle material 5. FIG. In addition, if the extrusion temperature of the jacket 13 is set to be equal to or lower than the melting temperature of the bundle material 5, even if a part of the bundle material 5 is equal to or higher than the softening temperature, the spiral shape is maintained by the subsequent cooling, so the problem Absent.

  Further, in the present invention, in addition to the optical fiber cable 10 shown in FIG. 2A, for example, an optical fiber cable 10a using a slot shown in FIG. 2B may be used.

  In the optical fiber cable 10a, the optical fiber units 1 are arranged in a plurality of slot grooves 21 formed on the outer periphery of the slot 19, respectively. The tension member 15 is provided substantially at the center of the slot 19, and the outer cover 13 is formed after the outer periphery of the slot 19 is pressed and wound as necessary. Even in this case, the same effect as that of the optical fiber cable 10 can be obtained.

  As described above, according to the present embodiment, since the bundle material 5 maintains the spiral winding shape, the single bundle material 5 suppresses the jump-out of the optical fiber core wire 3 and the like. The fiber core wire 3 can be reliably held. For this reason, for example, in the branching operation or the like, the optical fiber core wire 3 is not separated, and the optical fiber core wire 3 can be easily identified and branched.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  The optical fiber unit according to the present invention was evaluated. The product of the present invention is substantially the same as the optical fiber unit shown in FIG. Specifically, eight optical fiber cores having a diameter of 0.25 mm were bundled, and a bundle material was wound to manufacture an optical fiber unit.

  The bundle material was selected from polyethylene terephthalate, polyethylene, and polypropylene, and was spirally wound at a pitch of 15 mm to 1500 mm.

  For each of the obtained optical fiber units, first, the shape retention of the bundle material was evaluated. Moreover, the discriminability and take-out property of the optical fiber core wire were evaluated. The results are shown in Table 1.

  From the results, the heating temperature of the bundle material was not lower than the softening temperature and not higher than the melting temperature under all conditions, so that the spiral wound shape could be maintained. Moreover, when the discriminability of the optical fiber unit was visually evaluated, all the discriminability of the optical fiber unit was good. However, in the example with a pitch of 15 mm, the pitch was too narrow, and it was somewhat difficult to take out the optical fiber core wire.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber unit 3 ... Optical fiber core wire 5 ... Bundle material 10, 10a ... Optical fiber cable 11 ... Buffer body 13 ... Jacket 15 ... Tension member 17 ... …… Tear string 19 ……… Slot 21 ……… Slot groove

Claims (4)

A plurality of optical fiber cores;
One bundle material made of thermoplastic resin spirally wound around the outer periphery of the plurality of optical fiber cores;
Comprising
The bundle material maintains a spiral shape by its shape retaining property, and is an optical fiber unit. The bundle material is formed of a plurality of layers of resins of different materials,
2. The optical fiber unit according to claim 1, wherein the heat shrinkage amount of the resin on the inner surface side is larger than the heat shrinkage amount of the resin on the outer surface side. A plurality of optical fiber units according to claim 1 or claim 2,
A tension member;
A jacket provided on the outer periphery of the optical fiber unit;
An optical fiber cable comprising: Bundling a plurality of optical fiber cores, and spirally winding one bundle material made of thermoplastic resin around the outer periphery of the optical fiber core wire;
Heating the bundle material to a temperature below the melting temperature;
Cooling the bundle material to room temperature;
An optical fiber unit manufacturing method comprising:

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