JP2005283765A - Optical drop cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical drop cable in which the number of coated optical fibers which are not connected at a drop point and left unused is decreased, an midway branching after dropped is possible, and discrimination, housing and handling properties of the coated optical fibers are improved. <P>SOLUTION: In the optical drop cable 100, an optical fiber units is provided with unit cores, in which a plurality of coated optical fibers are bundled together with tension fibers and unit outer sheath provided on the outer periphery of the unit cores, and a plurality of the optical fiber units are connected in parallel as a unit, and the adjacent optical fiber units 11A are connected via neck parts 20. <P>COPYRIGHT: (C)2006,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 or underground to a general subscriber's house.

  As a so-called optical drop cable used to draw into a general subscriber's house from a wiring system cable installed in an aerial or underground, steel wire or FRP (glass fiber reinforced plastic) is provided on both sides or one side of a single-core optical fiber. ) And the like, and these are collectively covered with a resin such as polyethylene (underground optical drop cable), or those that are integrated with such a cable along a support line (aerial optical drop cable) It is known (for example, refer to Patent Document 1).

  FIG. 7 shows an example of an aerial optical drop cable. As shown in the figure, this optical drop cable 10 has tensile strength members 2 and 2 disposed above and below a single optical fiber core wire 1 and further a support wire 3 disposed on the upper and lower ends thereof. The outer cover 4 is provided by batch extrusion coating of resin such as polyethylene. Between the support wire 3 and the strength member 2 of the cable, a neck portion 5 for dividing the cable into a support wire portion 10A and a cable portion 10B is provided. At portions where the core optical fiber core wire 1 is located, tearing notches 6 and 6 are provided.

  In such an optical drop cable, since the support line 3 is provided, the aerial laying is possible, and since the neck part 5 is provided, the cable part 10B can be easily separated from the support line part 10A. Can be wired indoors. Further, since the notch 6 for tearing is provided, the inner optical fiber core wire 1 can be easily taken out by tearing the jacket 4 in the width direction of the cable.

  By the way, the one-core type or two-core type optical drop cable 10 as shown in FIG. 7 is a cable mainly used for dropping from a drop point closure to each home or office, and the trunk cable is intermediated with an AO closure. In the optical drop cable for branching and dropping to the drop point, a large number of optical fiber cores 1 having a colored layer 1a on the surface as shown in FIG. In addition, an optical fiber unit 8 having a batch coating 7 on its outer periphery is used. The colored layers 1a of the optical fiber cores 1 are colored in different colors such as red, green, yellow, and blue in order to improve the connection work of the cores in the closure.

  However, such a conventional optical drop cable has a structure in which all the optical fiber cores 1 are taken out when the outer cover 4 and the unitary covering 7 of the unit are torn starting from the notch 6 for tearing. However, at a drop point where the number of optical fiber cores that require connection is small, there is a problem that an optical fiber core wire that is not connected and is wasted. In addition, there is a problem that the withdrawal cannot be performed by an intermediate post branch after the withdrawal. Furthermore, since many optical fiber cores 1 jump out at once, the optical fiber core wires 1 are scattered, and there is a problem that the optical fiber core wires 1 are not easily stored in the closure.

  Further, as described above, the optical fiber core wire 1 can be identified by the colored layer 1a. However, when the number of core wires increases, a lot of colors must be used. Since it increases, there is a problem that the distinguishability due to coloring decreases. If the number of optical fiber cores 1 to be accommodated is reduced, this problem can be solved. However, if the number of core fibers is reduced, it is necessary to lay a plurality of cables of the same type in a bundle. In this case, if a large number of cables are to be connected at one drop point, a large number of optical fiber cores 1 of the same color are handled in the closure. Since identification is impossible, connection workability is reduced.

Further, the conventional single-core optical fiber 1 has a very thin outer diameter (usually 250 μm). However, when the surroundings become dark, such as in the evening, the color discriminability decreases, particularly in blue. Those colored in dark colors such as green and purple are very difficult to identify, and there is a problem that connection workability is further reduced. Moreover, since it is such a small diameter, there is a possibility that it may enter a slight gap such as a work tool, and there has been a problem that careful handling must be taken.
JP 2002-365499 A

  The present invention has been made in response to the above-described problems of the prior art, and can reduce the number of optical fiber cores that are not connected at a drop point and are wasted as much as possible. Provided is an optical drop cable that can be pulled down by an intermediate post-branch, and that can further improve the connection workability of an optical fiber core in a closure with good identification, storage and handling of the optical fiber. For the purpose.

  In order to achieve the above object, an optical drop cable according to claim 1 of the present application includes a unit core in which a plurality of optical fiber cores are gathered together with a tensile fiber, and an external unit provided around the unit core. An optical drop cable in which a plurality of optical fiber units each having a cover are arranged in parallel and connected together, wherein adjacent optical fiber units are connected via a neck portion. is there.

  According to a second aspect of the present invention, in the optical drop cable according to the first aspect, the plurality of optical fiber units are coupled so that the center of the unit core of each optical fiber unit is located on substantially the same plane. It is characterized by being.

  According to a third aspect of the present invention, in the optical drop cable according to the first aspect, a support line portion is provided in parallel with the plurality of optical fiber units to support these optical fiber units. The line portion is also connected to the optical fiber unit adjacent thereto via a neck portion.

  According to a fourth aspect of the present invention, in the optical drop cable according to the third aspect, the plurality of optical fiber units and the support line portions are unit cores of the optical fiber units and support lines of the support line portions. The centers are connected so as to be located on substantially the same plane.

  According to a fifth aspect of the present invention, in the optical drop cable according to any one of the first to fourth aspects, the optical fiber core wires in the respective optical fiber units are configured to be distinguishable from each other. To do.

  According to a sixth aspect of the present invention, in the optical drop cable according to any one of the first to fifth aspects, the optical fiber core wire is provided with a coating made of a thermoplastic elastomer on the outer periphery of the optical fiber strand. It is characterized by being.

  According to a seventh aspect of the present invention, in the optical drop cable according to any one of the first to sixth aspects, the optical fiber core wire is a single-core optical fiber core having an outer diameter of approximately 0.5 mm. It is a feature.

  According to an eighth aspect of the present invention, in the optical drop cable according to any one of the first to seventh aspects, a tear notch is provided in a jacket of each of the optical fiber units. is there.

  According to the optical drop cable of the present invention, since the optical fiber unit unit can be pulled down at the drop point, the number of optical fiber cores that are not connected at the drop point and are wasted can be reduced as compared with the conventional one, Branching after the middle after withdrawal is also possible. In addition, since the optical fiber cores can be taken out in units of optical fiber units, the optical fiber cores can be identified, stored and handled, and the optical fiber cores can be connected easily. Can be improved.

  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 100 of this embodiment is provided with two optical fiber units 11A and a coating 13 made of a thermoplastic resin such as polyethylene on the outer periphery of a support wire 12 made of a steel wire or the like. A support line portion 14 is provided.

  Each optical fiber unit 11A has a unit core 17 in which eight single-core optical fibers 15 are assembled together with tensile fibers 16, and a thermoplastic resin such as polyethylene is extruded into a pipe shape on the outer periphery of the unit core 17. It is comprised from the unit jacket 18 formed by. A colored layer 15a colored in different colors such as red, green, purple, yellow,... Is provided for each optical fiber unit 11A on the surface of the single-core optical fiber core 15A. In the unit 11A, the single-core optical fibers 15 are distinguished from each other. Further, a pair of tear notches 19 are provided on the surface of the unit jacket 18 on both sides of the unit core 17. By tearing the jacket 18 starting from these tear notches 19, that is, a tear notch By tearing the jacket 18 in the direction of the line connecting the tips of the ends 19, the inner optical fiber core wire 15 can be easily taken out.

  The optical drop cable 100 includes the two optical fiber units 11A and the support wire portion 14 such that the support wire portion 14 is located at the top and the center of the unit core 17 of each optical fiber unit 11A. And the center of the support line 12 are arranged in parallel so that they are substantially on the same plane, and are connected continuously or intermittently integrally through a narrow neck portion 20 made of a thermoplastic resin such as polyethylene. It has a structure.

  The single-core optical fiber core 15 is not particularly limited, but has an outer diameter of about 0.25 mm in which an optical fiber is coated with a silicone resin, an ultraviolet curable resin, or the like from the viewpoints of handleability and distinguishability. It is preferable to use a single-core optical fiber having an outer diameter of about 0.5 mm in which a coating made of a thermoplastic elastomer blended with a colorant is provided on the outer periphery of the optical fiber. By using such a single-core optical fiber, the inconvenience of entering a slight gap such as a work tool when connecting is eliminated, and the identification is improved and the surroundings such as evening are increased. Even if it becomes dark, it becomes possible to identify without misidentification, and the connection work can be promptly advanced. As the thermoplastic elastomer, a polyester thermoplastic elastomer such as a polybutylene naphthalate thermoplastic elastomer or a polybutylene terephthalate thermoplastic elastomer is used.

  Further, as the tensile strength fibers 16 that are assembled together with the optical fiber core 15 to form the unit core 17, aramid fibers such as poly-p-phenylene terephthalamide fibers, polyarylate fibers, polyparaphenylene benzbisoxazole fibers Polyester fibers such as polyethylene terephthalate fibers, nylon fibers, etc. are used. Such tensile strength fibers may be vertically attached around the optical fiber core wire 15.

  Furthermore, as a material constituting each jacket 18 of the optical fiber unit 11A, the covering 13 of the support wire portion 14 and the neck portion 20, various polyethylenes such as low density polyethylene, linear low density polyethylene, high density polyethylene, etc., Polyolefin thermoplastic resins such as polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer are preferably used. These resins may contain a flame retardant, a colorant and the like.

  The optical drop cable 100 of the present embodiment has a structure in which the optical fiber unit 11A and the support wire portion 4 are connected via the neck portion 20, and each optical fiber unit 11A can be easily separated by tearing at the neck portion 20. Can do. For this reason, optical fiber cores that can be pulled out at each drop point in units of optical fiber units and are wasted without being connected compared to conventional optical drop cables in which all optical fiber core wires are taken out at one drop point. The number of lines can be reduced. That is, FIG. 2 schematically shows a wiring example of the optical drop cable 100 of the present embodiment. As shown in the figure, in the optical drop cable 100, a required optical fiber unit 11 </ b> A is intermediately branched by a closure 22 for each drop point of each power pole 21, and pulled down to a general home or office by an optical drop cable 23. In FIG. 2, 24 indicates a trunk cable.

  Further, since it can be pulled down in units of optical fiber units in this way, it is possible to branch after the middle after pulling down.

  Further, when connecting the optical fiber core wire 15 in the drop point closure, the optical fiber core wire 15 can be taken out and connected by tearing the jacket 18 for each optical fiber unit 11A. The optical fiber core wire 15 is not misidentified between 11A (in some cases, with another optical drop cable), and the connection work can be promptly advanced.

  FIG. 3 schematically shows a connection example in the drop point closure 22 of the optical drop cable 100 of the present embodiment. As shown in FIG. In the closure 22, the optical drop cable 23 to be connected can be handled in the state of the optical fiber unit 11 </ b> A up to the vicinity of the connection portion 26 with the optical fiber core wire 25.

  In the present invention, the number of optical fiber units, the connecting method thereof, and the number of single-core optical fibers housed in the optical fiber unit are not particularly limited to the above example. 4 to 6 show such modifications. The optical fiber cable 101 shown in FIG. 4 supports the two 8-fiber optical fiber units 11A one by one in the embodiment shown in FIG. This is an example in which the line portion 14 is sandwiched. Further, in the embodiment shown in FIG. 1, the optical drop cable 102 shown in FIG. 5 is replaced with two 8-core optical fiber units 11A and one 8-core optical fiber unit 11A and one 4-core optical fiber unit 11B. 6 is an example of a 12-core optical drop cable connected in parallel vertically, and the optical fiber cable 103 shown in FIG. 6 is replaced with two 8-core optical fiber units 11A in the embodiment shown in FIG. This is an example of a 12-core optical drop cable in which only three 4-core optical fiber units 11B are connected in parallel in the vertical direction.

  Also, the shape of the unit jacket of each optical fiber unit is not particularly limited. For example, in the embodiment described above, the outer sheath 18 of each of the optical fiber units 11A and 11B has a substantially circular cross section. However, it may have an elliptical cross section or a rectangular cross section.

  Furthermore, in the embodiment described above, the support wire portion 14 is provided, but depending on the application, only the optical fiber units 11A and 11B may be connected.

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

Example 1
An optical drop cable having the structure shown in FIG. 1 was manufactured. The single-core optical fiber 15 is made of Hytrel 5557 (trade name of polyether / polybutylene terephthalate block copolymer, Toray DuPont Co., Ltd.) on the outer periphery of a single-core UV-curable resin-coated optical fiber having an outer diameter of 0.25 mm. 8 types of single-core optical fiber cores having an outer diameter of 0.5 mm coated with colored layers 15a of red, yellow, green, purple, blue, white, brown, and ash. The support wire 13 was a single steel wire having an outer diameter of 2.3 mm.

  First, two sets of eight single-fiber optical fibers 15 of different colors are assembled together with Kevlar 49 (trade name, manufactured by Toray DuPont), and in parallel with the support wires 13 as shown in FIG. The optical drop cable was manufactured by introducing into an extruder in an aligned state and coating the outer periphery with black low-density polyethylene (trade name UBEC700V, manufactured by Ube Industries) at the same time. In this optical drop cable, each of the cross-sectional shapes of the optical fiber unit 11A and the support wire portion 13 is a circular shape having an outer diameter of about 3.3 mm, and the overall height is about 10.5 mm. The thickness of the unit jacket 18 in each optical fiber unit 11A was about 0.5 mm.

  The transmission characteristics of the obtained optical drop cable were examined. As a result, the loss was 0.33 to 0.35 dB / km (λ = 1.31 μm) and 0.19 to 0.22 dB / km (λ = 1.55 μm). In addition, when an attempt was made to connect each single-core optical fiber in the closure, it was possible to connect single-fiber optical fibers of the same color while sufficiently identifying them.

Example 2
The optical drop cable having the structure shown in FIG. 4 was manufactured in the same manner using the same material as in Example 1 above. In this optical drop cable, each of the cross-sectional shapes of the optical fiber unit 11A and the support wire portion 13 is a circular shape having an outer diameter of about 3.3 mm, and the overall height is about 10.5 mm. The thickness of the unit jacket 18 in each optical fiber unit 11A was about 0.5 mm.

  The transmission characteristics of the obtained optical drop cable were examined. As a result, the loss was 0.33 to 0.35 dB / km (λ = 1.31 μm) and 0.19 to 0.22 dB / km (λ = 1.55 μm). In addition, when an attempt was made to connect each single-core optical fiber in the closure, it was possible to connect single-fiber optical fibers of the same color while sufficiently identifying them.

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. The figure which shows typically the example of a connection in the closure of the optical drop cable shown in FIG. Sectional drawing which shows other embodiment 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 other embodiment of the optical drop cable of this invention. Sectional drawing which shows an example of the conventional optical drop cable. Sectional drawing which shows the structure of the conventional optical fiber unit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11A, 11B ... Optical fiber unit, 12 ... Support wire, 14 ... Support wire part, 15 ... Single-core optical fiber core wire, 15a ... Colored layer, 16 ... Tensile fiber, 17 ... Unit core, 18 ... Unit jacket, 19 ... Tear notch, 20 ... Neck, 100-103 ... Optical drop cable

Claims (8)

Light that is formed by connecting a plurality of optical fiber units each having a unit core in which a plurality of optical fiber cores are gathered together with tensile fibers and a unit jacket provided on the outer periphery of the unit core in parallel and integrally. A drop cable,
An optical drop cable characterized in that adjacent optical fiber units are connected via a neck.   2. The optical drop cable according to claim 1, wherein the plurality of optical fiber units are connected so that a center of a unit core of each optical fiber unit is located on substantially the same plane.   A support line portion that supports these optical fiber units is provided in parallel with the plurality of optical fiber units, and this support line portion is also connected to an adjacent optical fiber unit via a neck portion. The optical drop cable according to claim 1.   The plurality of optical fiber units and the support line portion are connected so that the center of the support core of the unit core and the support line portion of each optical fiber unit are located on substantially the same plane. The optical drop cable according to claim 3.   5. The optical drop cable according to claim 1, wherein the optical fiber core wires in each of the optical fiber units are configured to be distinguishable from each other.   The optical drop cable according to any one of claims 1 to 5, wherein the optical fiber core is provided with a coating made of a thermoplastic elastomer on an outer periphery of an optical fiber.   The optical drop cable according to any one of claims 1 to 6, wherein the optical fiber core is a single-core optical fiber having an outer diameter of approximately 0.5 mm.   The optical drop cable according to any one of claims 1 to 7, wherein a tear notch is provided in a jacket of each optical fiber unit.

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