JP2008076898A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform lead-out operation of an optical fiber, without damaging the optical fiber in the slot groove of a slot core of an optical fiber cable in intermediate post branching. <P>SOLUTION: The optical fiber cable 1 comprises: a slot core 7 having a slot groove 5 which houses the optical fiber 3; a sheath 9 which covers the periphery of the slot core 7; and a lip cord 11 which is added longitudinally in the sheath 9. Furthermore, an eccentric sheath structure is adopted where the sheath 9 has a sheath thickness which is relatively larger on the side of an open part 13 of the slot groove 5 than on the opposite side of the open part 13 of the slot groove 5. The lip cord 11 is disposed in the sheath 9 at a position opposite to the open part 13 side of the slot groove 5, as well as, in the outer periphery of the slot core 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical fiber cable, and in particular, a one-groove slot in which a periphery of a slot core having one slot groove for accommodating an optical fiber is covered with a sheath, and a lip cord is vertically attached to the inside of the sheath. The present invention relates to a core-type optical fiber cable, which can easily lead out an optical fiber without damaging the optical fiber in the slot groove at the time of intermediate post branching.

  As a conventional optical fiber cable, as shown in Patent Document 1, the periphery of a slot core having one slot groove for accommodating an optical fiber is covered with a sheath, and the inside of the sheath is a lip cord. Is a one-slot slot-core type optical fiber cable with the slot attached, wherein the sheath thickness on the opening side of the slot groove is relatively thinner than the sheath thickness on the side opposite to the opening side of the slot groove The sheath structure is a structure in which a lip cord is disposed inside the sheath on the opening side of the slot groove.

  The optical fiber cable of Patent Document 2 is a loose tube type optical fiber cable with a slit in which an optical fiber is housed in a tube having a slit that communicates the inside and outside continuous in the axial direction. This is an eccentric sheath structure in which the sheath thickness is relatively thinner than the sheath thickness on the side opposite to the slit side, and a lip cord is disposed inside the sheath on the slit side.

The optical fiber cable of Patent Document 3 is a one-groove slot core type optical fiber cable in which the periphery of a slot core having one slot groove for accommodating an optical fiber is covered with a sheath. In this embodiment, the sheath falls into the opening of the slot groove so that the sheath of the opening of the slot groove is partially thickened.
JP 62-291608 A JP 63-5313 A JP-A-62-80611

  By the way, in the conventional optical fiber cable of Patent Document 1, since the sheath thickness on the opening side of the slot groove is thin, the mechanical strength of the sheath at this portion is deteriorated. Conversely, in order to ensure the mechanical strength of the sheath, it is necessary to increase the thickness of the sheath on the opening side of the slot groove to some extent. There was a problem that it was difficult to tear the sheath on the side.

  Furthermore, when the thickness of the sheath is uneven while ensuring the mechanical strength of the sheath on the opening side of the slot groove as a minimum, the outer diameter of the optical fiber cable has to be increased.

  Further, when taking out the lip cord, it is necessary to cut the sheath with the cutting edge of a cutting tool such as a knife. However, since the lip cord is mounted on the opening side of the slot groove, There is a problem that there is a risk of damaging the optical fiber. In particular, damaging the optical fiber at the time of intermediate post branching becomes a fatal obstacle.

  In the optical fiber cable of Patent Document 2, since the sheath thickness on the slit side is thin, there is almost the same problem as the optical fiber cable of Patent Document 1 described above.

  In the optical fiber cable of Patent Document 3, the sheath of the slot groove opening is partially thickened by simply dropping the sheath into the slot groove opening. There was a problem that it was difficult to do.

In order to achieve the problem to be solved by the above invention, an optical fiber cable of the present invention includes a slot core having one slot groove for accommodating an optical fiber therein, and a sheath covering the periphery of the slot core. In the optical fiber cable consisting of a lip cord vertically attached to the inside of the sheath,
The sheath has an eccentric sheath structure in which the sheath thickness on the opening side of the slot groove is relatively thicker than the sheath thickness on the opposite side to the opening side of the slot groove, and the lip cord is an opening of the slot groove. It is characterized in that the structure is disposed inside the sheath at a position opposite to the part side and on the outer periphery of the slot core.

  In the optical fiber cable of the present invention, in the optical fiber cable, the optical fiber protection linear member is positioned on a straight line connecting the slot groove and the lip cord, and extends in the longitudinal direction of the slot core. It is preferably embedded in the slot core.

  Moreover, the optical fiber cable of this invention WHEREIN: It is preferable that the said filament is comprised with the steel wire or FRP in the said optical fiber cable.

  As understood from the means for solving the above problems, according to the present invention, the sheath thickness on the opening side of the slot groove is relatively thicker than the sheath thickness on the opposite side to the opening side of the slot groove. Therefore, even if an external force is applied, the optical fiber inside the slot groove can be prevented from being damaged, and the mechanical strength of the portion where the sheath thickness is thin on the side opposite to the opening side of the slot groove is compensated at the bottom of the slot core. it can.

  Also, since the sheath stripping starts from the thin sheath thickness on the side opposite to the opening side of the slot groove that accommodates the optical fiber, the optical fiber can be cut with the cutting edge of the cutting tool when connecting the optical fiber. The optical fiber can be easily led out without damaging the optical fiber.

  Further, since the lip cord is located inside the sheath opposite to the opening side of the slot groove and the sheath thickness of this portion is thin, the lip cord can be easily taken out and the sheath can be easily torn. In addition, since the sheath thickness of the tearing portion is thin, the slot core can be easily taken out.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1, an optical fiber cable 1 according to this embodiment is a one-groove slot type optical fiber cable, and includes a slot core 7 having one slot groove 5 for accommodating the optical fiber 3 therein. And a sheath 9 covering the periphery of the slot core 7 and a lip cord 11 (Rip Cord) attached vertically to the inside of the sheath 9. This lip cord 11 is used for tearing the sheath 9 when the optical fiber 3 is taken out from the slot core 7.

  In FIG. 1, the slot groove 5 has a circular cross section, and one or a plurality of optical fibers 3 are accommodated in the slot groove 5. In FIG. 1, eight optical fibers 3 are accommodated. In addition, as the optical fiber 3, an optical fiber strand, an optical fiber core wire, an optical fiber tape core wire, or the like is used.

  The sheath 9 is made of, for example, a resin such as polyethylene resin, and the sheath thickness on the opening 13 side of the slot groove 5 is relatively thicker than the sheath thickness on the side opposite to the opening 13 side of the slot groove 5. It has a sheath structure. In addition, the lip cord 11 has a structure disposed inside the sheath 9 and on the outer periphery of the slot core 7 at a position opposite to the opening 13 side of the slot groove 5. For example, the sheath thickness of the portion where the lip cord 11 is located is about 1 mm, for example.

  The operation and effect of the optical cable 1 will be described with the above configuration. The sheath thickness on the opening 13 side of the slot groove 5 is relatively thicker than the sheath thickness on the opposite side of the slot groove 5 to the opening 13 side. Therefore, even if an external force is applied, damage to the optical fiber 3 inside the slot groove 5 can be prevented. Moreover, the mechanical strength of the portion of the slot groove 5 on the side opposite to the opening 13 side where the sheath thickness is thin is compensated for at the bottom of the slot core 7 on the side opposite to the opening 13 side of the slot groove 5.

  Further, when the optical fiber 3 is led out from the optical fiber cable 1 in an intermediate rear branch or the like, the cutting edge of a cutting tool 15 such as a knife is applied to the sheath 9 as shown in FIG. After the tearing, the lip cord 11 is taken out from the inside of the sheath 9. At this time, since the lip cord 11 is located inside the sheath 9 opposite to the opening 13 side of the slot groove 5 and the sheath thickness of this portion is as thin as about 1 mm, the lip cord 11 can be easily taken out, and Since this portion is located on the bottom of the slot core 7, that is, on the side opposite to the opening 13 side of the slot groove 5, it is possible to prevent the optical fiber 3 from being damaged.

  Further, when the lip cord 11 is taken out as described above and then pulled, the sheath 9 is easily torn because the sheath thickness is as thin as about 1 mm as shown in FIG. . In addition, since the sheath thickness of the tearing portion 17 is thin, the sheath 9 can be easily spread by the tearing portion 17, so that the slot core 7 can be easily taken out as shown in FIG.

  Next, as shown in FIG. 3D, the sheath 9 of the portion to be punctured is cut out. As shown in FIG. 3E, the desired optical cable 1 can be easily taken out from the opening 13 of the slot groove 5 of the slot core 7.

  Next, an optical fiber cable 19 according to another embodiment of the present invention will be described with reference to the drawings. In addition, since it is substantially the same as the optical fiber cable 1 of embodiment mentioned above, only a different part is mainly demonstrated, the same member attaches | subjects the same code | symbol and detailed description is abbreviate | omitted.

  Referring to FIG. 2, the optical cable 19 is different from the optical cable 1 described above in that the slot groove 5 of the slot core 7 is a deep groove and its bottom is semicircular in cross section in this embodiment. However, the cross-sectional shape of the slot groove 5 is not limited. Further, inside the slot core 7, for example, a tensile member 21 (tension member) as a linear member for protecting an optical fiber is positioned on a straight line connecting the center portion of the slot groove 5 and the lip cord 11. It is extended and embedded in the longitudinal direction. In addition, as the tensile body 21, a steel wire, FRP, etc. can be used.

  The operation and effect of the optical fiber cable 19 will be described with the above configuration. Since the tensile strength member 21 as an optical cable protection filament is mounted on the bottom portion of the slot core 7, light from the cutting edge of the cutting tool 15 can be obtained. The protection effect for the fiber 3 can be further enhanced. Others are the same as those of the optical fiber cable 1.

It is sectional drawing of the optical fiber cable of embodiment of this invention. It is sectional drawing of the optical fiber cable of other embodiment of this invention. (A)-(E) are operation | movement explanatory drawings when performing extraction of the optical fiber cable of FIG.

Explanation of symbols

1 Optical Fiber Cable 3 Optical Fiber 5 Slot Groove 7 Slot Core 9 Sheath 11 Rip Cord (Rip Cord)
13 Opening (slot groove 5)
15 Cutting tool 17 Tear 19 Optical fiber cable (of other embodiments)
21 Tensile strength (strands for optical fiber protection)

Claims (3)

In an optical fiber cable comprising: a slot core having one slot groove for accommodating an optical fiber therein; a sheath covering the periphery of the slot core; and a lip cord vertically attached to the inside of the sheath;
The sheath has an eccentric sheath structure in which the sheath thickness on the opening side of the slot groove is relatively thicker than the sheath thickness on the opposite side to the opening side of the slot groove, and the lip cord is an opening of the slot groove. An optical fiber cable characterized by having a structure disposed on the inner side of the sheath at a position opposite to the part side and on the outer periphery of the slot core.   The optical fiber protecting linear body is located on a straight line connecting the slot groove and a lip cord, extends in the longitudinal direction of the slot core, and is embedded in the slot core. 1 is an optical fiber cable.   The optical fiber cable according to claim 2, wherein the linear body is made of steel wire or FRP.

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