JP4304106B2 - 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 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, a steel fiber 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 line 3 and the strength member 2 of the cable, a neck part (connection part) 5 that divides the cable into a support line part 10A and a cable part 10B is provided, and an outer cover 4 of the cable part 10B is provided. The notches 6 and 6 for tearing are provided in the side part and the part in which the single-core optical fiber core wire 1 is located.

  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 general home or office. In the optical drop cable for branching and dropping to the drop point, an optical fiber provided with a colored layer 1a on the surface of about 4 to 8 cores as shown in FIG. An optical fiber unit 8 in which the core wire 1 is provided with a batch coating 7 is used.

  That is, as shown in FIG. 9, an optical drop cable 20 using this optical fiber unit 8 is an optical drop cable for dropping to a general home or office in the drop point closure 9, for example, the optical drop cable 10 shown in FIG. Connected. And in order to improve the connection workability | operativity in that case, the colored layer 1a of each optical fiber core wire 1 is colored in different colors like red, green, yellow, and blue. In FIG. 9, 11 shows a core wire connection part.

  However, in such a conventional optical drop cable 20, when many similar cables are gathered at one drop point, that is, it is necessary to connect many similar cables within one drop point closure 11. When this occurs, a large number of optical fiber cores 1 of the same color are handled. However, since the optical fiber core wires 1 of the same color cannot be distinguished, there is a problem that connection workability is lowered. This is because in the conventional optical drop cable 20, the coating 7 of the optical fiber unit 8 and the cable jacket 4 are bonded together, and the cable jacket 4 starts from the tearing notch 6 when connecting. This is because the sheath 4 of the optical fiber unit 8 is also torn together with the jacket 4 so that the inner optical fiber core 1 suddenly jumps out, making it difficult to distinguish it from the cores of other cables. Further, since the optical fiber core wire 1 suddenly jumps out in this manner, the optical fiber core wire 1 is scattered, and there is a problem that the optical fiber core wire 1 is not easily stored in the drop point closure 11.

Furthermore, since the conventional single-core optical fiber core 1 has a very thin outer diameter (usually 250 μm), when the surroundings become dark, such as in the evening, those that are colored in dark colors such as blue, green, purple, etc. Even the identification by color becomes difficult, and there is a problem that the 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 2001-337255 A

  The present invention has been made in response to the above-described problems of the prior art, and is excellent in distinguishability between optical fiber cores, storage of optical fiber cores, and handleability of optical fiber cores, and an optical fiber core in a closure. An object of the present invention is to provide an optical drop cable capable of improving the wire connection workability.

To achieve the above object, an optical drop cable of the present invention according to a first aspect of the present invention, an optical fiber unit which has been subjected to coating plurality of assembled outer periphery thereof a single-core optical fiber, the optical fiber unit a tension member disposed in parallel, and collectively these outer peripheral extrusion coated cross section with an elliptical shape or a rectangular shape of the enveloping city, between the coating and the sheath of the optical fiber unit is not bonded The single-core optical fiber is provided with a coating made of a polyether-polybutylene terephthalate copolymer on the outer periphery of the optical fiber, and the coating of the optical fiber unit is made of a stretched polypropylene tape. consists laterally wound layer, wherein the envelope is characterized in that, low-density polyethylene, and a notch for tearing the sides of the outer object of the short side is provided That.

According to a second aspect of the invention, an optical drop cable according to claim 1, wherein the optical fiber is characterized in that it is distinguishable configured together.

According to a third aspect of the present invention, in the optical drop cable according to the first or second aspect , the optical fiber core is a single-core optical fiber having an outer diameter of approximately 0.5 mm. is there.

According to a fourth aspect of the present invention, in the optical drop cable according to any one of the first to third aspects, a plurality of the optical fiber units are provided, and these optical fiber units are configured to be distinguishable from each other. It is characterized by.

  According to the optical fiber cable of the present invention, it is possible to improve the discriminability between the optical fiber cores, the storage property of the optical fiber cores, and the handleability of the optical fiber cores. 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 the present embodiment includes two optical fiber units 21A and 21B and steel wires or parallel wires arranged at intervals above and below these optical fiber units 21A and 21B. The first tensile body 22a and the second tensile body 22b made of FRP (glass fiber reinforced plastic) and the like, and a support wire made of a steel wire or the like arranged in parallel at a distance above the first tensile body 22a 23 and a jacket 24 made of a thermoplastic resin that is extrusion-coated collectively on the outer periphery thereof. Between the first strength member 22a of the jacket 24 and the support wire 23, a cable, a support wire portion 25 including the support wire 23, the optical fiber units 21A and 21B, and the first and second strength members 22a. , 22b, and a neck portion 27 is provided to facilitate separation of the support wire portion 25 from the cable portion 26. In addition, a tear notch 28 is provided at substantially the center of both side surfaces of the jacket 24 of the cable portion 26.

  Each of the optical fiber units 21A and 21B includes a plurality of single-core optical fiber core wires 29 (eight optical fiber units 21A and four optical fiber units 21B) and an outer sheath 24 that is extrusion-coated. A coating 30 formed of a material that does not melt by the heat at the time, more specifically, for example, a thermoplastic resin that does not melt by the heat at the time of extrusion coating the outer sheath 24 is extruded into a pipe shape or It is composed of a coating formed by foaming at the same time as extrusion, or a coating formed by winding a tape made of a resin that does not melt by heat when the outer coating 24 is extrusion coated. . Since the coating 30 is not melted by the heat when the coating 24 is extrusion coated, the coating 30 and the coating 14 are not bonded and can be separated. The tape may be wound either horizontally or vertically.

  In this embodiment, the colored layer 29a is provided on the surface of the single-core optical fiber core wire 29. In each optical fiber unit 21A, 21B, different colors such as red, green, purple, yellow,... By being colored, it is possible to distinguish between the single-core optical fiber core wires 29 in the respective optical fiber units 21A and 21B. Each coating 30 constituting each optical fiber unit 21A, 21B is also colored in a different color such as blue and yellow, so that each single-core optical fiber core wire 29 is also connected between the optical fiber units 21A, 21B. It can be identified.

  The single-core optical fiber core wire 29 used in the present invention is not particularly limited, but from the viewpoint of handleability and distinguishability, the outer diameter of the optical fiber coated with a silicone resin, an ultraviolet curable resin, or the like. 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 mixed with a colorant is provided on the outer periphery of an optical fiber having a diameter of about 0.25 mm. That is, by using such a single-core optical fiber, the inconvenience of entering a slight gap such as a work tool at the time of connection as in the conventional case is solved, and the identification is also improved. Even if the surroundings become dark, it is possible to proceed with the connection work promptly without misunderstanding. Examples of the thermoplastic elastomer include polyester-based thermoplastic elastomers such as polybutylene naphthalate-based thermoplastic elastomers and polybutylene terephthalate-based thermoplastic elastomers.

  In addition, the thermoplastic resin or tape material constituting each coating 30 of the optical fiber units 21A and 21B and the thermoplastic resin constituting the jacket 24 are melted by the heat at the time of extrusion coating the jacket 24. As long as there is no such thing, the kind in particular is not limited. However, it is preferable that the material constituting the coating 30 is excellent in handleability, can easily take out the core wire, and is difficult to adhere to the outer sheath 24. On the other hand, the heat constituting the outer sheath 24 is preferable. The plastic resin is preferably a material that has high mechanical strength, good flexibility, and does not crack at ambient temperature (-30 ° C to + 70 ° C).

From this point of view, the thermoplastic resin constituting the jacket 24 includes low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, ethylene-acetic acid, which are blended with additives such as flame retardants and fillers. Polyolefin thermoplastic resins such as vinyl copolymers, ethylene-ethyl acrylate copolymers, and ethylene-propylene copolymers are preferably used. Further, for the jacket 24 made of such a thermoplastic resin, the coating 30 of the optical fiber units 21A and 21B is made of the same polyolefin-based thermoplastic resin, the aforementioned polybutylene naphthalate-based thermoplastic elastomer, or polybutylene terephthalate-based. It is preferable to use a polyester thermoplastic elastomer such as a thermoplastic elastomer extruded or extruded and foamed, or a tape made of a stretched polyolefin thermoplastic resin.

  If the thickness of the covering 30 is too thin, the strength against the side pressure is reduced. Conversely, if the thickness is too thick, the outer diameter of the entire cable portion 26 is increased (if the thickness of the jacket 24 is reduced). The outer diameter of the entire cable portion 26 can be reduced, but the strength of the jacket 24 is reduced.) From such a point of view, the thickness of the coating 30 depends on the type of material constituting it and the number of single-core optical fiber cores 29, but in general, the range of 100 μm to 700 μm is preferable, and 200 μm to 600 μm. It is more preferable in the range.

  In the optical drop cable 100 configured as described above, the coating 30 of the optical fiber units 21A and 21B and the cable jacket 24 are configured to be separable without being bonded, and therefore the cable jacket 24 is notched for tearing. When the optical fiber units 21A and 21B are torn, the optical fiber units 21A and 21B are taken out first, and then the coating 30 of these optical fiber units 21A and 21B is peeled off to take out the single-core optical fiber core wire 29 to the outside. For this reason, even if it is necessary to connect a large number of cables of the same type in one drop point closure, it is not immediately mixed with the single-core optical fiber cores 29 of the same color of other cables as in the past, The single-core optical fiber core wire 29 can be identified, and the connection work can proceed smoothly. In this embodiment, two optical fiber units 21A and 21B are provided in one optical drop cable 100, and only this optical drop cable 100 is connected in the drop point closure. Although the single-color optical fiber core wire 29 of the same color may be handled, the single-fiber optical fiber core wire 29 can be distinguished between the optical fiber units 21A and 21B. In particular, since the coatings 30 of the optical fiber units 21A and 21B are colored in different colors, the identification is easier.

FIG. 2 schematically shows a connection example in the drop point closure 40 of the optical drop cable 100 of the present embodiment. As shown in FIG. in the closure 40 within the optical fiber unit 21A to the vicinity connecting portion 33 of the optical fiber 32 of the optical drop cable 31 to be connected, it is possible to handle in a state of 21B, it is excellent in storability in the closure 40 Yes.

  In the present invention, the number of optical fiber units, the assembly method thereof, the number of single-core optical fibers housed in the optical fiber unit, and the like are not particularly limited. 3 and 4 show such a modification. The optical fiber cable 101 shown in FIG. 3 is an optical fiber unit that accommodates eight single-core optical fibers 29 in the embodiment shown in FIG. This is an example of an 8-fiber optical drop cable in which only one 21A is arranged. In addition, the optical fiber cable 102 shown in FIG. 4 is a 16-core type in which two optical fiber units 21A containing eight single-core optical fibers 29 are arranged in parallel in the upper and lower directions in the embodiment shown in FIG. It is an example of an optical drop cable.

  In addition, the optical drop cable 103 shown in FIG. 5 is a 12-core type in which three optical fiber units 21B accommodating four single-core optical fibers 29 are arranged in parallel vertically in the embodiment shown in FIG. It is an example of an optical drop cable. In this example, tearing notches 28 are further provided on both side surfaces on the short side of the jacket 24 of the cable portion 26 provided in a rectangular shape at positions slightly shifted from the center to the left and right sides. Thereby, the optical fiber unit 21B can be easily taken out when the outer cover 24 is torn starting from the notch 28 for tearing. That is, as in this example, when three or more optical fiber units are arranged in parallel vertically, the tearing notch 28 has a jacket for the cable portion 26 in order to facilitate removal of the optical fiber unit. 24 are preferably provided on both side surfaces on the short side. With the change of the formation position of the notch 28 for tearing, in this optical drop cable 103, the first strength member 22a and the second strength member 22b are also embedded at positions slightly shifted on the left and right sides from the center. It has become.

  Further, in the present invention, as shown in FIG. 6, the single-core optical fiber core wires 29 may be gathered around the interposition 34 or together with the interposition 34, and a coating 30 may be applied to the outer periphery thereof. In the optical fiber cable 104 shown in FIG. 6, an optical fiber unit 21 </ b> C in which single-core optical fibers 29 are gathered around the interposition 34 and a coating 30 is applied to the outer side thereof is used.

  In the embodiment described above, the cable support line 23 is provided. However, the support line 23 is not essential, and may be configured with only the cable portion 26 depending on the application.

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

Reference Example An optical drop cable having the structure shown in FIG. 1 was manufactured. The single-core optical fiber 29 is made of Hytrel 6347 (trade name of polyether / polybutylene terephthalate block copolymer, Toray DuPont Co., Ltd.) on the outer periphery of a single-core ultraviolet curable resin-coated optical fiber having an outer diameter of 0.25 mm. 8 types of single-core optical fiber cores with an outer diameter of 0.5 mm coated with colored layers of red, yellow, green, blue, white, purple, brown, and ash. Further, single steel wires having an outer diameter of 0.4 mm were used for the first and second strength members 22 a and 22 b, and single steel wires having an outer diameter of 2.3 mm were used for the support wires 23.

  First, Hytrel 7237 (polyester) is a collection of eight types of single-core optical fibers colored in red, yellow, green, blue, white, purple, brown, and ash, with a blue colorant added to the outer periphery. An ether-polybutylene terephthalate block copolymer trade name, manufactured by Toray DuPont Co., Ltd.) was extruded into a pipe shape to form a coating 30 having a thickness of about 0.2 mm to form an 8-fiber optical fiber unit 21A having an outer diameter of about 2 mm. In the same manner, four types of single-core optical fiber cores colored in red, yellow, green, and blue are assembled, and Hytrel 7237 with a yellow colorant added to the outer periphery thereof is extruded into a pipe shape with a thickness of about 0.2 mm. A coating 30 was formed to form a four-core optical fiber unit 21B having an outer diameter of about 2 mm.

  Next, an extruder in which these optical fiber units 21A and 21B, two single steel wires for strength members 22a and 22b, and single steel wires for support wire 23 are arranged in parallel as shown in FIG. And a black low-density polyethylene (trade name UBEC700V, manufactured by Ube Industries Co., Ltd.) was collectively extrusion coated on the outer periphery to produce an optical drop cable having a total width of about 3.3 mm and a height of about 7.5 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 The coating 30 of the optical fiber units 21A and 21B was formed in the same manner as in the reference example except that the entire width was about 3.3 mm, except that each of the coatings 30 was formed by horizontal winding of a 0.25 mm-thick stretched polypropylene tape (Daido Processing Co., Ltd.) An optical drop cable with a height of approximately 7.5 mm was manufactured.

  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 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 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. The figure which shows typically the example of a connection in the closure of the conventional optical drop cable.

Explanation of symbols

21A, 21B, 21C ... optical fiber unit, 22a ... first tensile body, 22b ... second tensile body, 24 ... jacket, 28 ... tearing notch, 29 ... single-core optical fiber, 29a ... colored layer 30 ... covering, 100-104 ... optical drop cable

Claims (4)

An optical fiber unit which has been subjected to coating a single-core optical fiber to the plurality of assembled outer periphery thereof, a tension member disposed parallel to the optical fiber unit, extrusion coated section collectively to these outer periphery An oval or rectangular outer sheath; the coating of the optical fiber unit and the outer sheath are separable without being bonded; and the single-core optical fiber core is a polyether on the outer periphery of the optical fiber strand A coating made of a polybutylene terephthalate copolymer, wherein the coating of the optical fiber unit is made of a horizontally wound layer of a stretched polypropylene tape, the jacket is made of low-density polyethylene, and a short of the jacket An optical drop cable characterized in that notches for tearing are provided on both sides of the side . Optical drop cable of claim 1, wherein said optical fiber is characterized in that it is distinguishable configured together. 3. The optical drop cable according to claim 1, 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 3 , wherein a plurality of the optical fiber units are provided, and the optical fiber units are configured to be distinguishable from each other.

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