JP4059825B2 - Optical drop cable - Google Patents

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 cable having a structure as shown in FIG. 12 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. In addition, in the case of the tensile body 2 made of FRP, the allowable bending diameter is not so large. On the other hand, when the tensile body 2 is made of steel wire, due to its rigidity, the repulsion when bending is made. Due to the large force, there has been a problem that indoor wiring work, especially wiring work in a narrow place or winding place is not easy.

In addition, since the outer diameter of the single-core optical fiber 1 is very thin (usually 250 μm), if the optical fiber 1 is taken out and wired, it may be easily broken when bent. was there. For this reason, it is necessary for the operator to handle the cord with great care, which is a heavy burden.
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 that does not cause the optical fiber core wire to be broken during wiring. For the purpose.

In order to achieve the above object, the optical drop cable according to the first aspect of the present invention is such that the optical fiber core wire and the tensile body are arranged substantially in parallel with a space therebetween, and the outer periphery is collectively covered with the outer periphery thereof. a cable portion and comprising, a aerial optical drop cable that includes a support wire portion for supporting the cable portion, the envelope between the optical fiber and the strength members of the cable portion, the cable A separation groove for separating the optical fiber core wire portion and the tensile strength body portion is provided, tensile strength fibers are disposed around the optical fiber core wire, and the cross-sectional shape of the optical fiber core wire portion is circular. It is characterized by being.

The invention of claim 2 is characterized in that the optical drop cable of claim 1, wherein the tear notch to envelope of said optical fiber portion.

  According to the optical drop cable of the present invention, the cable part can be further separated into the optical fiber core part and the tensile body part, so that the workability of the indoor wiring can be improved. Further, since it is not necessary to take out the optical fiber core wire just before the connection device at the time of terminal processing, there is no possibility that the optical fiber core wire is broken, and the burden on the operator can be reduced.

  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 jacket 15 provided in the outer periphery. The cable portion 12 includes two single-core optical fiber core wires 17 each provided with a layer 16 made of a tensile strength fiber, and a tensile strength composed of steel wires or FRPs disposed in parallel at intervals on the upper and lower sides thereof. It comprises a body 18 and a jacket 19 that covers them all together. The jacket 15 of the support wire portion 11, the jacket 19 of the cable portion 12, and the connecting portion 13 are formed by batch extrusion of a thermoplastic resin.

  In this embodiment, a total of four separation grooves 20 are provided on the left and right sides between the single-core optical fiber core wire 17 and the strength member 18 of the jacket 19 of the cable portion 12, and these separation grooves 20 are provided. The cable portion 12 can be easily cut in the width direction at the position of the groove 20. That is, by cutting at the position of the separation groove 20, the cable portion 12 is divided into three parts, a tensile strength body portion 12 </ b> A including the strength body 18 and an optical fiber core wire portion 12 </ b> B including the single-core optical fiber core wire 17. It is like that. Further, in this embodiment, the separation groove 20 is provided so that the cross-sectional shape of the separated optical fiber core portion 12B is circular.

  Further, tearing notches 19a are provided on both sides of the outer sheath 19 of the optical fiber core portion 12B, and the outer sheath 19 of the optical fiber core portion 12B can be easily provided at the positions of these tear notches 19a. It can be torn. In this way, the inner two single-core optical fibers 17 can be easily taken out by tearing the outer sheath 19 of the optical fiber core portion 12B at the position of the tearing notch 19a.

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

  Furthermore, as the thermoplastic resin that constitutes the jackets 15 and 19 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 depth of the separation groove 20 is too deep, the outer cover 19 may be torn or the support wire portion 11 and the cable portion 12 may be separated during winding of the cable drum and laying. On the other hand, if the depth is too shallow, the separation workability is deteriorated, and a part of the strength member 12A remains on the surface of the optical fiber core portion 12B, which causes inconvenience in the subsequent terminal processing of the optical fiber core portion 12B. There is a fear. From such a viewpoint, in the present embodiment, a range in which the width between the facing separation grooves 20 is about 0.3 mm to 0.7 mm is 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 a closure and 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 portion 12 wired indoors is further separated from the tensile strength portion 12A, and only the optical fiber core portion 12B is connected to the optical connection device 31. Since no tensile body is embedded in the optical fiber core portion 12B and the cross-sectional shape is circular and can be freely bent in any direction, the optical fiber core wire 17 is connected as in the conventional case. This can be done without removing it from the jacket 19. In FIG. 2, 32 and 33 indicate the fixed portions of the support wire portion 11 and the strength member portion 12 </ b> A that are separated, respectively.

  As described above, in the optical fiber cable 101 of the present embodiment, the portion where the tensile body 18 is embedded from the cable portion 12, that is, the tensile body portion 12A is separated, and only the optical fiber core portion 12B is wired and connected. Therefore, the wiring workability is improved as compared with the conventional case, and the optical fiber core wire 17 can be wired just before the optical connection device without being taken out from the jacket 19. As a result, the optical fiber core wire 16 is not broken during wiring work, and the burden on the operator is reduced.

  In the present invention, for example, as shown in FIGS. 3 and 4, the number of single-core optical fibers 17 may be one, or may be three or more. The optical drop cable 102 shown in FIG. 3 has a single optical fiber core wire 17 arranged in the above embodiment, and the optical drop cable 103 shown in FIG. 4 has a single fiber core in the above embodiment. Three optical fiber cores 17 are arranged.

  Further, for example, as shown in FIGS. 5 and 6, one or more optical fiber tape cores 171 and 172 may be used instead of the single optical fiber core wire 17. The optical drop cable 104 shown in FIG. 5 is a two-core cable in which two optical fiber strands are arranged in parallel instead of the two single-core optical fiber wires 17 and the outer periphery thereof is collectively covered in the above embodiment. One optical fiber ribbon 171 is disposed, and the optical drop cable 105 shown in FIG. 6 has four optical fibers instead of the two single optical fibers 17 in the above embodiment. A single-fiber four-core optical fiber ribbon 172 in which fiber strands are arranged in parallel and the outer periphery thereof is collectively covered is disposed. In the optical drop cable 105 shown in FIG. 6, the cross section of the optical fiber core portion 12B is formed in a rectangular shape, and such a shape is also included in the present invention. From the viewpoint of handleability and wiring workability, it is desirable to form a circular cross section that does not cause bending directionality.

  Furthermore, in the said embodiment, the tensile strength fiber layer 16 is not necessarily essential, and only the outer sheath 19 may be given to the outer periphery of the optical fiber core wire 17. In this case, the optical fiber core wire 17 and the jacket 19 may be in close contact like the optical drop cable 106 shown in FIG. 7, and inside the jacket 19 like the optical drop cable 107 shown in FIG. The optical fiber core wire 17 may be accommodated loosely. Further, as in the optical drop cable 108 shown in FIG. 9, another coating layer 21 may be interposed between the tensile strength fiber layer 16 and the jacket 19.

  In the examples described above, the two tension members 18 are arranged in parallel with a space above and below the single optical fiber core wire 17 or the optical fiber tape core wires 171 and 172. The optical fiber core wire 17 or the optical fiber tape core wires 171 and 172 may be disposed only on the upper or lower side. An optical fiber cable 109 shown in FIG. 10 is an example thereof, and in the above-described embodiment, one strength member 17 is disposed only on the opposite side of the support wire 14.

  In the present invention, for example, as shown in FIG. 11, a plurality (two in the example of the drawing) of optical fiber core portions 12B may be formed.

  That is, in the optical drop cable 110 shown in FIG. 11, the cable portion 12 includes two single-core optical fiber cores 17 a and 17 b each provided with a layer 16 made of a tensile strength fiber and spaced in parallel with each other. Further, the tensile strength members 18 are arranged in parallel at intervals on the upper and lower sides, and these are collectively covered with the outer cover 19. And between one single-core optical fiber core wire 17a and the tensile body 18 adjacent thereto, between the other single-core optical fiber core wire 17b and the tensile body 18 adjacent thereto, a single-core optical fiber core wire. A total of six separation grooves 20 are provided on the left and right sides of the jacket 19 between the wire 17b and the single-core optical fiber 17b, and the cable portion 12 is cut by cutting at the positions of the separation grooves 20. Are separated into four parts: two tensile body parts 12A including the tensile body 18 and two optical fiber core parts 12B each including the single-core optical fiber core wire 17a and the single-core optical fiber core wire 17b. It is like that. The two optical fiber core portions 12 are separated and connected by wiring as necessary.

Next, although the Example of this invention is described, this invention is not limited to a following example at all.

Example An optical drop cable 101 having the structure shown in FIG. 1 was manufactured. The single-core optical fiber core wire 17 is a single-core ultraviolet curable resin-coated optical fiber core wire having an outer diameter of 250 μm, and the tensile body 18 of the cable body 12 is an FRP rod having an outer diameter of 0.4 mm. For No. 14, a single steel wire having an outer diameter of 1.2 mm was used.

  First, while the poly-p-phenylene terephthalamide fiber (Kevlar 49: trademark) is vertically attached to the outer periphery of the two single-core optical fibers 17, the two strength members 18 and the support wires 14 are connected to each other as shown in FIG. And introduced into an extruder in a state of being arranged in parallel, and non-halogen flame retardant polyethylene (trade name NUC9739 manufactured by Nihon Unicar Co., Ltd.) is extrusion coated on the outer periphery thereof so that the cross-sectional shape of the support wire portion 11 has an outer diameter of about 2 mm. The depth of the separation groove 20 provided in the jacket 19 of the cable portion 12 is about 0.75 mm (the width between the separation grooves 20 facing each other is about 0.5 mm), and the optical fiber core portion 12B An optical drop cable in which the thickness of the outer cover 19 at the deepest part of the tearing notch 19a provided in the outer cover 19 is about 0.3 mm and the cable height is about 7 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. Further, when the support wire portion 11 is actually separated and the strength member portion 12A is further separated and wiring connection of the optical fiber core portion 12B is attempted, the optical fiber core portion 12B can be freely moved in any direction. It was possible to bend the wire smoothly and connect the wires smoothly.

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 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 the modification of the optical drop cable of this invention. 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, 12A ... Optical fiber core wire part, 12B ... Strength body part, 13 ... Connection part, 14 ... Support line, 15, 19 ... Outer jacket, 16 ... Tensile fiber layer, 17, 17a, 17b ... single-core optical fiber, 18 ... tensile body, 19a ... tearing notch, 20 ... separation groove, 101-110 ... optical fiber cable, 171, 172 ... optical fiber tape core

Claims (2)

An aerial light comprising an optical fiber core and a tensile body that are arranged substantially in parallel with a space therebetween, and a cable portion in which the outer periphery is collectively covered with a jacket and a support wire portion that supports the cable portion. A drop cable,
A separation groove for separating the cable portion into an optical fiber core portion and a tensile body portion is provided in a jacket between the optical fiber core wire and the tensile body of the cable portion, and the periphery of the optical fiber core wire is provided. An optical drop cable characterized in that a tensile strength fiber is disposed on the optical fiber core and a cross-sectional shape of the optical fiber core portion is circular.   The optical drop cable according to claim 1, wherein a tear notch is provided in a jacket of the optical fiber core portion.

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