JP2013182094A - Optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical cable around which a roughly wound string is wound so as not to be located under overlapping parts of a spirally wound wrapping tape.SOLUTION: In the optical cable, a roughly wound string 15 is spirally wound around an outer periphery of a slot rod 12 housing a plurality of coated optical fibers 14, a wrapping tape 16 is spirally wound over the roughly wound string 15, the outside of the wrapping tape 16 is coated with a sheath 17 formed by extrusion molding, and the roughly wound string 15 is bonded to the inner surface of the wrapping tape 16. The roughly wound string 15 and the wrapping tape 16 are wound in the same direction at the same pitch so that the roughly wound string 15 is not located under overlapping parts 16a of the wrapping tape. When a plurality of roughly wound strings are used, all of the roughly wound strings are wound in parallel at the same pitch as the wrapping tape.

Description

  The present invention relates to a slot-type optical cable in which a coarsely wound string, an upper wound tape, and a sheath are sequentially provided on the outer periphery of a slot rod that accommodates a plurality of optical fiber core wires.

  With the recent expansion of broadband services such as video distribution, IP telephony, and data communication, the number of subscribers to home-use data communication services (FTTH: Fiber To The Home) using optical fibers has increased, and the construction for that has increased. In this FTTH, a drop optical cable is used to drop a subscriber's house from a trunk optical cable. For example, the optical fiber can be pulled down to the subscriber's home by, for example, branching the optical fiber core from a trunk optical cable laid on a utility pole in a city with a connection box usually called a closure. A drop optical cable is connected to the fiber core using a fusion connection or an optical connector.

  In order to draw an optical fiber from the middle part of the trunk optical cable to a subscriber's house, etc., one to several optical fiber cores are selected from a plurality of optical fiber cores housed in the cable. A branching operation is performed. In this branching operation, when the optical fiber core wire is taken out from the optical cable, a sheath (also referred to as a jacket) made of polyethylene or the like is peeled off, and then the upper winding tape and the coarse winding string are removed.

  The upper winding tape (also referred to as a presser winding tape) is used for water insulation in the cable or thermal insulation at the time of forming the sheath, and is usually applied in a spiral manner by lap winding. The coarsely wound string is used to prevent the optical fiber core housed in the slot of the slot rod at the cable manufacturing stage from falling off the slot rod before winding the upper winding tape. It is wound around the outer periphery of the spiral.

  However, the optical cable wound with the above-described rough winding cord has a problem that it is not easy to remove the rough winding cord by the above-described branching operation of the optical fiber core wire or recycling and dismantling of the cable. In order to solve this problem, for example, in Patent Document 1, when the rough winding string after winding is bonded to the inner surface of the upper winding tape and the upper winding tape is peeled off, the rough winding string is also removed at the same time. A method is disclosed. The rough winding string and the upper winding tape are bonded by heat at the time of extrusion of the sheath. For this reason, the rough winding string has an adhesive layer that melts by the heat described above. .

Japanese Patent No. 4577302

  The coarsely wound string is wound spirally at a pitch that does not drop the optical fiber core wire from the slot rod. On the other hand, the upper winding tape is wound in a spiral manner by lap winding so that the optical fiber core wire in the slot rod is not exposed. Therefore, normally, the winding pitches of the coarsely wound string and the upper winding tape are individually set and different, and the winding directions may be opposite to each other. In this case, a portion where the coarsely wound string always crosses occurs at the overlapping portion of the upper winding tape.

The overlapping portion of the upper winding tape has double the tape thickness and the thermal resistance increases, so the rough winding string located under the tape of the overlapping portion of the tape may not be bonded by the heat of the sheath, There exists a problem that the removal property of a rough winding string is impaired.
Moreover, when the coarsely wound string located under the tape of the overlapping portion of the upper winding tape is bonded by the heat of the sheath, there is a possibility that the tapes are bonded to each other by the coarsely wound string that is heat-melted in the overlapping portion of the tape. There is a problem that the upper winding tape is difficult to unwind.

  The present invention has been made in view of the above-described actual situation, and an object of the present invention is to provide an optical cable that is wound so that a coarsely wound string is not positioned below an overlapping portion of an upper winding tape that is wound spirally. And

In the optical cable according to the present invention, a rough winding string is spirally wound around the outer periphery of a slot rod in which a plurality of optical fiber cores are accommodated, and then an upper winding tape is spirally wound in an overlapping manner, and the outside thereof Is an optical cable that is covered with a sheath by extrusion molding, and the rough winding cord is bonded to the inner surface of the upper winding tape. The rough winding cord and the upper winding tape are wound in the same direction at the same pitch. It does not exist under the overlapping part of the upper winding tape.
Even when a plurality of coarsely wound cords are used, all of the roughly wound cords are wound in parallel at the same pitch as the upper winding tape.

  According to the present invention, since the coarse winding string is not located under the overlapping portion of the upper winding tape, the tape is not bonded to the overlapping portion of the upper winding tape, and the upper winding is wound around the rough winding cord. The part which is not bonded to the tape does not occur, and the branching workability and recycling dismantling workability of the optical cable can be improved.

It is a figure explaining embodiment of the optical cable by this invention. It is a figure explaining other embodiment of the optical cable by this invention.

  Embodiments of the present invention will be described with reference to the drawings. In the figure, 11 is an optical cable, 12 is a slot rod, 12a is a groove, 13 is a tension member, 14 is an optical fiber core wire, 15 is a coarsely wound string, 16 is an upper tape, 16a is an overlapping portion, and 17 is a sheath. .

  As shown in FIG. 1, the optical cable 11 includes a slot rod (also referred to as a spacer) 12 made of a plastic material such as polyethylene, in which a tension member (also referred to as a tensile body) 13 is embedded and integrated, and a plurality of grooves 12a are provided. Composed. The groove 12a of the slot rod 12 is formed in a spiral shape or an SZ shape, and a plurality of optical fiber core wires or tape-like optical fiber core wires 14 are accommodated in the groove 12a. In order to prevent the optical fiber core wire 14 from falling out of the groove 12a (especially in the case of the SZ groove) after the optical fiber core wire 14 is accommodated in the groove 12a during the manufacturing process of the optical cable, the rough winding string 15 is immediately inserted into the slot rod 12. It is wound around the outer periphery of the spiral. Further, an upper winding tape (also referred to as a presser winding tape) 16 is spirally wound thereon, and then a sheath 17 is applied by extrusion molding.

The coarsely wound string 15 is formed of a thermoplastic material that can be bonded to the upper winding tape 16, and is bonded to and integrated with the inner surface of the upper winding tape 16 by heat at the time of extrusion molding of the sheath 17. And, at the time of branching work of the optical fiber core or dismantling work for recycling, the coarsely wound string 15 is removed from the slot rod 12 at the same time as the upper winding tape 16 is peeled off. .
In addition, since the resin temperature in the extrusion molding of the sheath using a resin such as polyethylene that is generally used is 180 to 220 ° C., the coarsely wound string 15 is formed of an adhesive resin having a melting point of 180 ° C. or less. Or has an adhesive resin layer.

  As the coarsely wound string 15, for example, a narrow tape-shaped one or a fiber bundle-like one in which fibers are bundled can be used. As the tape-shaped rough winding string, for example, a two-layer structure in which a low melting point resin adhesive layer is covered on the outside of a resin base material having a high melting point temperature and a high tensile strength can be used. Further, as the fiber bundle-like coarse winding string, for example, a fiber strand having a high melting point temperature and a high tensile strength and a plurality of fiber yarns covered with a low melting point resin adhesive layer can be used. . In addition, a single material of the low-melting point resin adhesive layer may be a tape-shaped or fiber bundle-shaped string.

The upper winding tape 16 is formed of a material to which the rough winding string 15 is easily bonded (the same kind of material as the rough winding string) and does not melt at the molding temperature of the sheath 17. For example, it can be formed of a resin material having a high melting point temperature and a high tensile strength as the resin base material of the above-described rough winding string 15.
When the upper tape 16 has a tape width (W) and the overlap width of the overlapping portion 16a is wound spirally by (L), the winding pitch becomes (W-L).

  The tape width W of the upper winding tape 16 varies depending on the number of optical fibers accommodated in the cable (that is, the thickness of the slot rod 12). For example, with a 200-core cable, the tape width W is about 30 mm. The winding overlap width L is set to about 5 mm. In this case, the winding pitch (W-L) of the upper winding tape 16 is uniquely determined as 25 mm. On the other hand, the winding pitch (P) of the rough winding string 15 can be arbitrarily selected.

However, if the winding pitch (W-L) of the upper winding tape 16 and the winding pitch (P) of the coarse winding string 15 are different, the coarse winding string 15 intersects at any part of the overlapping portion 16a of the tape. It will be. As a result, as described in the section of the subject matter of the present invention, a portion where the sheath is not bonded by heat of the sheath is generated, or the tapes are bonded to each other at the overlapping portion of the tape, and the workability of removing the tape is lowered. .
For this reason, in the present invention, the winding pitch (W-L) of the upper winding tape 16 and the winding pitch (P) of the coarse winding string 15 are made the same, and the bottom of the overlapping portion 16a of the upper winding tape. Is characterized in that the coarsely wound string 15 is not positioned.

By preventing the coarsely wound string 15 from being located (not present) under the overlapping portion 16a of the upper wound tape 16, the coarsely wound string 15 is securely bonded to the lower surface of the upper wound tape 16, and the tape It is possible to prevent the tapes from adhering at the overlapping portion 16a.
As a result, when the upper winding tape 16 is cut or unwound by a cutter or the like, the coarse winding string 15 can be surely removed together with the upper winding tape 16. Moreover, since the upper winding tape is not adhere | attached between tapes, it can unwind smoothly.

As the number of optical fiber cores increases, the diameter of the slot rod 12 also increases, the upper winding tape 16 to be used becomes wider, and the winding pitch also increases. For this reason, when the number of the coarsely wound string 15 is one, it may be insufficient for preventing the optical fiber core wire from dropping off.
In this case, as shown in FIG. 2, the coarsely wound string 15 can use not only one but also a plurality (two are shown in the figure). The plurality of coarsely wound cords 15 are set on the slot rod 12 at the same pitch (P) as the winding pitch (W-L) of the upper winding tape 16 at the same interval as in the example of FIG. Wrap.

  As a result, as in the case of FIG. 1, it is possible to prevent any of the coarsely wound strings 15 from being located (existing) under the overlapping portion 16 a of the upper winding tape 16. As a result, the coarsely wound string 15 can be securely bonded to the lower surface side of the upper winding tape, and the tapes can be prevented from adhering to each other at the tape overlapping portion 16a.

DESCRIPTION OF SYMBOLS 11 ... Optical cable, 12 ... Slot rod, 12a ... Groove, 13 ... Tension member, 14 ... Optical fiber cord, 15 ... Coarse winding string, 16 ... Top wound tape, 16a ... Overlapping part, 17 is a sheath.

Claims (2)

Coarse winding cords are spirally wound around the outer periphery of a slot rod containing a plurality of optical fiber cores, and then the upper winding tape is spirally wound in a layered manner, and the outside is a sheath by extrusion molding. An optical cable that is covered and the rough winding string is bonded to the inner surface of the upper winding tape,
The optical cable, wherein the coarsely wound string and the upper wound tape are wound in the same direction at the same pitch, and the coarsely wound string is not located below the overlapping portion of the upper wound tape.   The optical cable according to claim 1, wherein a plurality of the coarse winding cords are wound in parallel.

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