JP2005077704A - Optical drop cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hanging optical drop cable in which workability is made superior for indoor wiring, and no breakage of a coated optical fiber occurs, even though careless bending is applied when the coated optical fiber is taken out and the weight and diameter are reduced. <P>SOLUTION: An optical drop cable 101 is provided with a cable section 12 and a supporting line section 11 which supports the cable section 12. The cable section 12 is constituted only by an optical fiber cord 19, in which no high-tensile body is buried via a high-tensile fiber layer 17 at the outer periphery of the coated optical fiber 16. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical drop cable used for lead-in wiring from a wiring system cable installed in an aerial to a general subscriber's house.

  The concept of spreading the optical fiber communication network to the homes of subscribers such as ordinary houses and buildings is progressing concretely, and accordingly, development of various optical fiber cables necessary for the construction of such a communication network is continued.

  Among these, as a so-called overhead optical drop cable for drawing and wiring from a wiring system cable installed in the aerial to a general subscriber's house, a structure having a structure as shown in FIG. 9 has been proposed (for example, Patent Document 1). reference.).

  That is, as shown in the figure, this aerial optical drop cable has tensile strength members 2 and 2 made of FRP (glass fiber reinforced plastic) or steel wire on the upper and lower sides of a single optical fiber core wire 1. Further, a support wire 3 made of a steel wire is further disposed thereon, and a jacket 4 is provided by collectively extruding a resin such as polyethylene on the outer periphery thereof. Between the support wire 3 and the strength member 2 of the cable, a neck portion (connecting portion) 7 for dividing the cable into the support wire portion 5 and the cable portion 6 is provided. The notches 8 and 8 for tearing are provided in the part which the single-core optical fiber core wire 1 is located in both sides.

  In such an optical drop cable, since the support wire 3 is provided, aerial laying is possible. And since the neck part 7 is provided, after drawing a cable to a subscriber's house, the cable part 8 can be isolate | separated from the support wire part 5, and only the cable part 8 can be used for indoor wiring. In addition, since the strength member 2 is disposed with the optical fiber core 1 sandwiched therebetween, an increase in transmission loss of the optical fiber due to temperature change can be prevented, and light caused by tensile stress when the cable portion 8 is wired indoors can be prevented. Fiber breakage can also be prevented. Further, since the notch 8 for tearing is provided, it is possible to easily take out the optical fiber core wire 1 by tearing the jacket 4 in the width direction of the cable at the time of cable end processing or the like.

  However, in such a conventional optical drop cable, since the cross-sectional shape of the cable portion 8 is rectangular or elliptical, directionality occurs in the bending direction (usually the direction indicated by the arrow in FIG. 9, ie, the cable In addition, in the case of the tensile body 2 made of FRP, the allowable bending diameter is large. On the other hand, when the tensile body 2 is made of steel wire, the repulsive force when bent is due to its rigidity. Therefore, there is a problem that indoor wiring work, particularly wiring work in a narrow place or a winding place is not easy. Moreover, when the tensile strength member 2 is a steel wire, there is a problem that lightning / surge current countermeasures are necessary.

Recently, with the spread and expansion of optical communication networks, the demand for lighter and thinner optical fiber cables has been increasing. It has been demanded.
JP 2001-337255 A

  The present invention has been made to solve the above-described problems of the prior art, and provides an optical drop cable that is excellent in workability during indoor wiring and can be reduced in weight and diameter as compared with the prior art. For the purpose.

  In order to achieve the above object, an optical drop cable according to claim 1 of the present application is an optical drop cable including a cable portion and a support line portion that supports the cable portion, and the cable portion includes: The optical fiber cord is composed only of an optical fiber cord provided with an outer sheath in which a tensile strength body is not embedded via a tensile strength fiber layer.

  The invention according to claim 2 is an optical drop cable including a cable portion and a support wire portion that supports the cable portion, and the cable portion has a tensile fiber layer interposed on the outer periphery of the optical fiber core wire. It is composed only of a plurality of optical fiber cords provided with a jacket in which a tensile body is not embedded, and these optical fiber cords are connected in parallel on the same plane. It is.

  According to a third aspect of the present invention, in the optical drop cable according to the first or second aspect, the outer jacket of the optical fiber cord is formed in a circular shape in cross section.

  According to the optical drop cable of the present invention, since the tensile strain applied in the longitudinal direction of the cable is suppressed by the tensile strength fiber arranged around the optical fiber core wire, the tensile strength body is provided in the jacket as in the conventional case. There is no need to bury it. And the tensile strength fiber arrange | positioned around the optical fiber core wire does not restrict | limit the bending radius of a cable part or increase rigidity like the tensile strength body embed | buried in the jacket. Therefore, the handleability of the cable portion after separation of the support wire portion is improved, and the workability of the indoor wiring can be improved. In addition, since it has a loose structure in which the optical fiber core wire and the jacket are not in close contact with each other, it is possible to prevent an increase in transmission loss of the optical fiber due to a temperature change.

  In addition, since the cable portion is easy to handle as described above, the cable portion drawn into the subscriber's house can be directly connected to an optical connection device or the like.

  Furthermore, since it is not necessary to embed a strength member in the jacket, it is possible to reduce the thickness of the jacket, thereby making it possible to reduce the diameter and weight of the cable.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of the optical drop cable of the present invention.
As shown in FIG. 1, the optical drop cable 101 of the present embodiment includes a support line portion 11, a cable portion 12, and a connecting portion 13 that connects them. The support wire part 11 is comprised from the support wire 14 which consists of a steel wire etc., and the outer sheath 15 provided in the outer periphery. On the other hand, the cable portion 12 is composed of an optical fiber cord 19 in which a layer 17 made of tensile strength fibers is provided around two single-core optical fibers 16 and an outer sheath 18 is provided on the outer side thereof. The outer sheath 15 of the support wire 11, the outer sheath 18 of the optical fiber cord 19 constituting the cable portion 12, and the connecting portion 13 are formed by extrusion of a thermoplastic resin, and the support wire portion 11 and the cable portion 12. Each of the cross-sectional shapes is formed in a circular shape.

  The single-core optical fiber core wire 16 is not particularly limited, and the outer periphery of the optical fiber is coated with a silicone resin or an ultraviolet curable resin, and the outer periphery is further coated with a nylon resin (usually nylon) And so on).

  Further, as the tensile strength fiber constituting the tensile strength fiber layer 17 provided around the single-core optical fiber core wire 16, aramid fiber such as poly-p-phenylene terephthalamide fiber, polyarylate fiber, polyparaphenylene benz Bisoxazole fibers, polyester fibers such as polyethylene terephthalate fibers, nylon fibers, and the like are used. The tensile strength fiber layer 17 is formed by vertically attaching such tensile strength fibers around each single-core optical fiber core wire 16.

  Furthermore, as the thermoplastic resin that constitutes the jackets 15 and 18 and the connecting portion 13, a thermoplastic resin such as polyethylene or polyvinyl chloride is used. These resins may contain a flame retardant and a colorant.

  In the present invention, if the thickness of the tensile strength fiber layer 17 and the jacket 18 is too thin, the protective effect on the optical fiber core wire 16 and the mechanical strength of the cable portion 12 become insufficient. Conversely, if the thickness is too thick, The outer diameter and weight increase, making it difficult to reduce the diameter and weight. From this point of view, the thicknesses of the tensile strength fiber layer 17 and the jacket 18 depend on the type of material constituting them and the number and type of the optical fiber cores 16 to be accommodated, but generally the tensile strength The fiber layer 17 preferably has a range in which the outer diameter is about 1 mm to 2.0 mm, and the jacket 18 has a range in which the outer diameter (outer diameter of the optical fiber cord 19) is about 1.5 mm to 3.0 mm. preferable.

  For example, as shown in FIG. 2, the optical drop cable 101 of this embodiment is connected to a wiring system cable (not shown) in the closure, and is wired outdoors to the eaves of the subscriber house 30. Therefore, the support wire portion 11 is separated, and only the cable portion 12 is drawn into the subscriber house 30 and wired indoors. The support line part 11 is fixed to the wall surface of the house of the subscriber house 30. The cable unit 12 wired indoors is connected to the O / E converter 31 and the like. In FIG. 2, reference numerals 32 and 33 denote fixing portions of the support wire portion 11 and the cable portion 12, respectively.

  Since the optical fiber cable 101 of the present embodiment has a configuration in which tensile strain applied in the longitudinal direction of the cable is suppressed by the tensile strength fibers arranged around the optical fiber core wire 16, the tensile strength in the outer sheath 18 is conventionally provided. Eliminates the need to bury the body. The tensile strength fibers arranged around the optical fiber core 16 do not limit the bending radius of the cable portion 12 or increase the rigidity unlike the tensile strength member embedded in the outer sheath. Therefore, the handleability of the cable portion 12 is improved, and indoor wiring can be easily and smoothly advanced. In particular, in the optical fiber cable 101 of this embodiment, since the cross section of the cable part 12 is circular, the directionality at the time of bending does not arise. For this reason, workability at the time of indoor wiring is further improved. In addition, since the optical fiber core and the outer sheath are not in close contact, and the outer sheath expands and contracts due to temperature changes, the optical fiber core does not become distorted. Can be prevented.

  Further, since it is not necessary to embed a tensile body in the jacket 18, the thickness of the jacket 18 can be reduced, and the cable can be made thinner and lighter.

  In the present invention, for example, as shown in FIGS. 3 and 4, the number of single-core optical fibers 16 may be one, or may be three or more. The optical drop cable 102 shown in FIG. 3 is one in which one single-core optical fiber 16 is arranged in the above embodiment, and the optical drop cable 103 shown in FIG. 4 is a single core in the above embodiment. Three optical fiber cores 16 are arranged.

  For example, as shown in FIGS. 5 and 6, one or a plurality of optical fiber ribbons 161 and 162 may be used instead of the single-fiber ribbon 16. The optical drop cable 104 shown in FIG. 7 is a two-core cable in which two optical fiber strands are arranged in parallel instead of the two single-core optical fiber wires 16 and the outer periphery thereof is collectively covered in the above embodiment. One optical fiber ribbon 161 is disposed, and the optical drop cable 105 shown in FIG. 6 has four optical fibers instead of the two single-fiber ribbons 16 in the above embodiment. One fiber-core optical fiber 162 is arranged in which fiber strands are arranged in parallel and the outer periphery thereof is collectively covered. In the optical drop cable 105 shown in FIG. 6, the cross section of the cable portion 12 is formed in a rectangular shape, and such a shape is also included in the present invention, but the handleability and wiring workability of the cable portion 12 are also included. From this point of view, it is desirable to form a circular cross-section that does not cause bending directionality.

  In the present invention, for example, as shown in FIG. 7, the cable portion 12 may be composed of a plurality (two in the example of the drawing) of optical fiber cords 19A and 19B.

  That is, the optical drop cable 106 shown in FIG. 7 has two optical fiber cords 19A in which a layer 17 made of a tensile strength fiber is provided around one single-core optical fiber core wire 16 and a jacket 18 is provided on the outer side thereof. , 19B are arranged in parallel and are connected by a jacket 18. The support line portion 11 is connected to one of these optical fiber cords 19A and 19B so that the support line portion 11 and the two optical fiber cords 19A and 19B are arranged in parallel on the same plane.

  As shown in FIG. 8, the optical drop cable 106 is in a state in which the two optical fiber cords 19A and 19B are joined after the support wire portion 11 is separated and pulled into the subscriber's home 30. (FIG. 8B) Or, if necessary, the optical fiber cords 19A and 19B are further disconnected (FIG. 8C) and wired indoors.

  Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

Example An optical drop cable 101 having the structure shown in FIG. 1 was manufactured. The single-core optical fiber core 16 was a single-core ultraviolet curable resin-coated optical fiber core having an outer diameter of 250 μm, and the support wire 14 was a single steel wire having an outer diameter of 1.2 mm.

  First, poly-p-phenylene terephthalamide fiber (Kevlar 49: trademark) is vertically attached to the outer periphery of the two single-core optical fibers 16, and the support wire 14 is guided in parallel to this and introduced into the extruder. Then, non-halogen flame retardant polyethylene (trade name NUC9739 manufactured by Nippon Unicar Co., Ltd.) is extrusion coated on the outer periphery, and the cross-sectional shape of the support wire portion 11 is a circular shape having an outer diameter of about 2 mm, and the cross-sectional shape of the cable portion 12 is the outer diameter. An optical drop cable having a circular shape of about 2 mm and a cable height of about 4.2 mm was manufactured.

  The obtained optical fiber cable was subjected to a heat cycle test (−30 ° C. to + 60 ° C., 10 cycles), and the maximum transmission loss increase was examined. It was less than 0.05 dB / km and had good temperature characteristics. It was. In fact, when the support wire portion 11 was separated and indoor wiring of the cable portion 12 was attempted, the cable portion 12 could be freely bent in an arbitrary direction and could be smoothly wired.

Sectional drawing which shows one Embodiment of the optical drop cable of this invention. The figure which shows typically the example of wiring of the optical drop cable shown in FIG. Sectional drawing which shows the modification of the optical drop cable of this invention. Sectional drawing which shows the modification of the optical drop cable of this invention. Sectional drawing which shows the modification of the optical drop cable of this invention. Sectional drawing which shows the modification of the optical drop cable of this invention. Sectional drawing which shows other embodiment of the optical drop cable of this invention. Sectional drawing which shows the usage condition of the optical drop cable shown in FIG. Sectional drawing which shows an example of the conventional optical drop cable.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Support wire part, 12 ... Cable part, 13 ... Connection part, 14 ... Support wire, 15, 18 ... Outer sheath, 16 ... Single-core optical fiber core wire, 17 ... Buffer layer, 19, 19A, 19B ... Optical fiber Cord, 101-106: optical fiber cable, 161, 162: optical fiber ribbon

Claims (3)

An optical drop cable comprising a cable part and a support line part that supports the cable part,
The optical drop cable is characterized in that the cable portion is composed only of an optical fiber cord provided with an outer sheath in which a strength member is not embedded via a strength fiber layer on the outer periphery of the optical fiber core. An optical drop cable comprising a cable part and a support line part that supports the cable part,
The cable portion is composed of only a plurality of optical fiber cords provided with an outer sheath in which a tensile strength body is not embedded via a tensile strength fiber layer on the outer periphery of the optical fiber core, and these optical fiber cords are the same. An optical drop cable characterized by being connected in parallel on a plane.   The optical drop cable according to claim 1 or 2, wherein the outer cover of the optical fiber cord has a circular cross section.

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