JP5798885B2 - Fiber optic cable - Google Patents

Description

  The present invention relates to an optical fiber cable including a slot core having a C-shaped cross section for accommodating an optical fiber unit therein.

  For example, in the optical fiber cable described in Patent Document 1, in order to be able to branch at a cable terminal or a cable middle part with a general-purpose tool, optical fiber units are assembled in a slot core having a C-shaped cross section, The structure is covered with a sheath.

  In recent years, the diameter of cables has been reduced, and the area of the slot groove formed in the slot core has been reduced to the extent that optical fiber characteristics can be guaranteed, and the slot core and sheath have been made thinner to pursue a smaller diameter. It is requested to do.

JP 2008-76897 A

  However, in an optical fiber cable having a slot core having a C-shaped cross section, when the optical fiber unit is taken out from the slot core, the optical fiber unit is covered with a slot core rib formed at the end of the opening of the slot groove. If so, the removal of the optical fiber unit becomes worse.

  As the opening width of the slot groove becomes narrower, the optical fiber unit is further covered by the slot core rib, so that a trigger for taking out the optical fiber unit cannot be secured. Even if the optical fiber unit is grabbed and taken out, the optical fiber unit may be squeezed by the slot core rib, giving a large loss fluctuation.

  In particular, in an optical fiber cable whose mounting density has been improved with the aim of reducing the diameter due to recent demands, it becomes difficult to take out the optical fiber unit from the slot groove of the slot core because the optical fiber unit diameter and the slot groove diameter are close to each other. Becomes more prominent. On the other hand, when the opening width of the slot groove is widened, when an optical fiber unit is to be assembled into the slot groove at the time of cable manufacture, the optical fiber unit is removed from the slot groove when rotation during assembly propagates. Or drop off.

  Therefore, the present invention enables an optical fiber unit to be taken out from a slot core without causing a loss fluctuation, and prevents the optical fiber unit from dropping from the slot core during cable manufacture. The purpose is to provide.

  A first invention includes a slot core having a C-shaped cross section having one or a plurality of slot grooves for accommodating an optical fiber unit therein, and a sheath for covering the periphery of the slot core with a presser winding tape, An optical fiber cable including a tensile core embedded in the slot core and the sheath along a longitudinal direction of the cable, wherein the optical fiber unit partially protrudes from the slot groove. An opening of the slot groove including the protruding portion is covered with the presser winding tape.

  According to a second invention, in the first invention, the slot groove opening width is W, the optical fiber unit diameter is Ud, the slot groove diameter is D, and the distance from the slot groove opening tip to the slot groove bottom is When S1 is S1, 0.66 Ud ≦ W ≦ D and 0.49 Ud ≦ S1 ≦ 1.0 Ud are satisfied.

  According to the optical fiber cable of the present invention, since a part of the optical fiber unit protrudes from the slot groove, the optical fiber unit can be taken out without being squeezed by the slot core rib, and the loss variation of the optical fiber is suppressed. be able to. In addition, since a part of the optical fiber unit protruding from the slot groove is covered with the press-wound tape, it is possible to prevent the optical fiber unit from dropping from the slot groove by the press-wound tape when concentrating to the slot groove.

It is a cross-sectional view of the optical fiber cable of this embodiment. It is a figure which shows the dimensional relationship of the slot groove | channel of the slot core which comprises the optical fiber cable of this embodiment, and an optical fiber unit, respectively.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable to which the present invention is applied.

  An optical fiber cable 1 includes a slot core 4 having a C-shaped cross section having one or a plurality of slot grooves 3 for accommodating an optical fiber unit 2 therein, and a periphery of the slot core 4 via a press-winding tape 5. The sheath 6 is covered, and the slot core 4 and the strength member 7 embedded in the sheath 6 along the longitudinal direction of the cable.

  The optical fiber unit 2 is a unit in which a plurality of optical fiber strands, optical fiber ribbons, and the like are collected into a circular shape. The optical fiber is a quartz glass fiber coated with an ultraviolet curable resin. An optical fiber ribbon is composed of a plurality of optical fiber strands arranged in parallel and coated with a tape material, or a plurality of optical fiber strands arranged in parallel and intermittently connected to each other. It is a thing.

  As shown in FIG. 2, the slot core 4 is formed in a C-shaped cross section. The slot core 4 is formed with a slot groove 3 as a fiber storage portion for storing the optical fiber unit 2 therein. The slot core 4 has a cross-sectional shape in which a part of a circle is cut off. Therefore, there is no slot core rib on the slot groove opening side of the slot core 4, and both opening ends of the slot groove 3 are horizontal surfaces 4a. The slot groove 3 has an arc shape centered on a position deviated from the center position of the slot core 4. In this embodiment, the number of slot grooves 3 is one, but the number may be plural.

  The slot core 4 is provided with a strength member 7 for regulating the bending direction of the cable and ensuring the rigidity of the cable itself. The strength member 7 is made of a steel wire, a resin fiber wire, or the like, and is embedded at a position below the bottom of the slot groove of the slot core 4 along the cable longitudinal direction.

  The presser winding tape 5 covers the entire slot groove so as to be in close contact with the horizontal surfaces 4 a formed at both ends of the slot groove opening of the slot core 4 including the portion protruding from the slot groove 3 of the optical fiber unit 2. Yes.

  The sheath 6 is formed by extrusion molding so as to cover the entire outer periphery of the optical fiber unit 2 and the slot core 4. For the sheath 6, for example, a resin such as polyethylene (PE) or polyolefin (PO) is used. In the sheath 6, the tensile body 7 is embedded along the longitudinal direction of the cable on the center line passing through the center of the optical fiber cable 1, similar to the tensile body 7 embedded in the slot core 4 with the optical fiber unit 2 interposed therebetween. ing.

  In the optical fiber cable 1 configured as described above, the dimensional relationship between the slot groove 3 of the slot core 4 and the optical fiber unit 2 is as follows. As shown in FIG. 2, the opening width of the slot groove 3 is W, the diameter of the optical fiber unit 1 is Ud, the diameter of the slot groove 3 is D, and the distance from the opening end of the slot groove 3 to the slot groove bottom is S1. In this case, the relationship is 0.66 Ud ≦ W ≦ D and 0.49 Ud ≦ S1 ≦ 1.0 Ud.

  The relationship between the opening width W, the groove depth S1 and the diameter D of the slot groove 3 and the optical fiber unit diameter Ud is based on the following reason and experimental results. Regarding the gripping property (pinch-out property) of the optical fiber unit, when the slot groove depth S1 is larger than the optical fiber unit diameter Ud, it is difficult to grip (pinch-out) the optical fiber unit 2 from the slot groove 3. On the other hand, when the slot groove depth S1 is smaller than the optical fiber unit diameter Ud, a part of the optical fiber unit 2 protrudes from the slot groove 3, so that the portion can be gripped.

  Further, in general, the optical fiber unit 2 has an extra length in the cable so that the optical fiber unit 2 extends to the optical fiber so as not to be distorted, and the optical fiber unit 2 is bent slightly so that the opening of the cable is inside. 2 protrudes from the opening and is relatively easy to grip. Further, since the optical fiber unit 2 is formed by twisting a plurality of optical fiber cores, if it is possible to grip a part of the optical fiber unit 2, other optical fiber cores twisted together by pulling up the optical fiber unit 2 are also included. It can be taken out.

  Regarding the take-out property of the optical fiber unit 2, when the opening width W of the slot groove 3 is sufficiently larger than that of the optical fiber unit 2, the take-out property becomes easy. On the other hand, if the opening width W of the slot groove 3 is small, the optical fiber unit 2 is ironed with the slot core rib when the optical fiber unit 2 is taken out, causing loss fluctuation to the optical fiber, or causing damage or disconnection. become. In addition, since the optical fiber unit 2 is an assembly of a plurality of optical fiber core wires, the optical fiber unit 2 itself is deformed when taken out. Therefore, the opening width W of the slot groove 3 is not necessarily larger than the optical fiber unit diameter Ud.

  The verification by experiment was as follows. A 200-core optical fiber cable having an outer diameter of φ10.0 mm was manufactured. The sheath and the slot core were coated with high-density polyethylene, and a tensile body having a diameter of 0.95 mm was mounted on each of the sheath and the slot core. The aggregate diameter of the 200 optical fiber units was φ5.2 mm.

Then, the slot groove depth S1 was changed as shown in Table 1, and the gripping property (pinch-out property) of the optical fiber unit from the optical fiber cable and the assembly property at the time of manufacture were confirmed.

  The gripping performance of the optical fiber unit can be determined by bending the optical fiber cable toward the opening side of the slot groove when the optical fiber cable can be pulled out from the slot groove with a finger when the optical fiber cable is branched after the middle. The case where the optical fiber unit could be picked up was evaluated as Δ, and the case where the optical fiber unit could not be picked up was evaluated as ×. The assembly property of the optical fiber unit was evaluated as x when the optical fiber unit was detached from the slot groove between the assembly point and the sheath at the time of assembly of the optical fiber unit to the slot core, and was evaluated as ◯ when it could be assembled properly.

  As a result of these examinations, when the slot groove depth S1 is 1.12 Ud, it is difficult to take out the optical fiber unit and it is difficult to take out. In addition, regarding the collectability at the time of manufacture, if the slot groove depth S1 is not 0.49 Ud or more of the optical fiber unit, the optical fiber unit is detached from the slot groove, and a phenomenon that the assembly becomes difficult occurs.

Next, the opening width W of the slot groove was changed as shown in Table 2, and the loss fluctuation at the time of taking out the optical fiber unit from the optical fiber cable was confirmed.

  When the optical fiber cable was branched after the middle and the optical fiber unit was taken out from the slot groove, the loss variation was 0.1 dB or more, and the case where it was less than 0.1 dB was marked as ◯. As a result, it was confirmed that if the optical fiber unit diameter Ud is 0.66 times or more, the transmission loss during extraction can be kept good. From the above results, it is desirable that the optical fiber cable has a relationship of 0.66 Ud ≦ W ≦ D and 0.49 Ud ≦ S1 ≦ 1.0 Ud as described above.

  Next, the optical fiber cable of the present embodiment satisfying the relational expression was manufactured based on the following conditions, and the cable characteristics were examined. A 200-core optical fiber cable having an outer diameter of φ10.0 mm was manufactured. The sheath and the slot core were coated with high-density polyethylene, and a tensile body having a diameter of 0.95 mm was mounted on each of the sheath and the slot core. For the 200-fiber optical fiber unit, a 4-fiber ribbon was used in which adjacent optical fibers were intermittently fixed, and the aggregate diameter was set to φ5.2 mm. For the slot core, the slot groove opening width W was 4.5 mm, and the slot groove depth S1 was 3.1 mm.

Table 3 shows the cable characteristics of the optical fiber cable. The items of cable characteristics are transmission loss after manufacture, transmission loss temperature characteristic, lateral pressure characteristic, impact characteristic, bending characteristic, twisting characteristic, and loss fluctuation when taking out the optical fiber unit.

  According to the result of Table 3, the result which was excellent in each each item was obtained.

  As described above, according to the optical fiber cable of this embodiment, since a part of the optical fiber unit 2 protrudes from the slot groove 3, the optical fiber unit 2 can be taken out without being squeezed by the slot core rib. . As a result, it is possible to suppress loss fluctuations when taking out the optical fiber unit.

  In addition, according to the optical fiber cable of the present embodiment, a part of the optical fiber unit 2 that protrudes from the slot groove 3 is covered with the press-wound tape 5, so that the optical fiber unit 2 is not It is possible to prevent the winding tape 5 from dropping from the slot groove 3.

  Further, according to the optical fiber cable of the present embodiment, the opening width of the slot groove 3 is W, the diameter of the optical fiber unit 2 is Ud, the diameter of the slot groove 3 is D, and the slot groove 3 extends from the opening end of the slot groove 3. When the distance to the bottom is S1, the relationship is 0.66 Ud ≦ W ≦ D and 0.49 Ud ≦ S1 ≦ 1.0 Ud, so that the gripping property of the optical fiber unit 2 and the light into the slot groove 3 are Both the collectability of the fiber unit 2 and the take-out property of the optical fiber unit 2 from the slot groove 3 are good.

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical fiber cable including a slot core having a C-shaped cross section that houses an optical fiber unit.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber cable 2 ... Optical fiber unit 3 ... Slot groove 4 ... Slot core 6 ... Sheath 7 ... Strength body

Claims (1)

A slot core having a C-shaped cross section having one slot groove for accommodating the optical fiber unit therein, a sheath for covering the periphery of the slot core with a presser winding tape, and a cable longitudinal direction on the slot core and the sheath In a fiber optic cable provided with a tensile body embedded along
A part of the optical fiber unit protrudes from the slot groove, and an opening of the slot groove including a part protruding from the slot groove is covered with the press-wrapping tape,
When the slot groove opening width is W, the optical fiber unit diameter is Ud, the slot groove diameter is D, and the distance from the slot groove opening tip to the slot groove bottom is S1, 0.66 Ud ≦ W ≦ D and 0.49 Ud ≦ S1 ≦ 1.0 Ud. An optical fiber cable characterized by:

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