JP2017129706A - Fiber optic cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable capable of facilitating branching work and also restraining an optical fiber from being pulled out.SOLUTION: An optical fiber cable 1 comprises: a pair of tension members 11; an optical fiber bundle 12 made up of a plurality of optical fibers 10 that is disposed between the pair of tension members 11; a pair of separators 13 that sandwich the optical fiber bundle 12 therebetween in a different direction from a direction in which the pair of tension members 11 hold the optical fiber bundle 12 therebetween; and a sheath 16 that covers the pair of tension members 11, the optical fiber bundle 12, and the pair of separators 13. A fibrous intervening object 14 is made to intervene between the optical fiber bundle 12 and the sheath which intrudes between the pair of separators 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical fiber cable.

  As an optical fiber cable divided by a dividing tool, an optical fiber cable described in Patent Document 1 is known. The optical fiber cable described in Patent Literature 1 sandwiches a pair of strength members, a plurality of optical fibers disposed between the pair of strength members, and a plurality of optical fibers from the side where the strength members are not disposed. It has a structure in which a pair of arranged separators are covered with a jacket.

JP 2008-70601 A

  When a plurality of optical fibers are bundled and arranged between a pair of separators and covered with a resin (jacket) to form an optical fiber cable, the resin (jacket) that enters between the pair of separators is light. May enter fiber gaps. As a result, when the jacket of the optical fiber cable is divided, the optical fiber of the intermittently fixed type optical fiber tape may enter the jacket, and branching may be difficult.

  On the other hand, in order to prevent the resin from entering the gap between the optical fibers, if a space is provided between the optical fiber and the resin that has entered between the pair of separators, the pulling force (optical fiber cable) When an external force along the longitudinal direction is applied, the optical fiber is easily pulled out.

  An object of the present invention is to facilitate the branching operation and to suppress the drawing of the optical fiber.

  The main invention for achieving the above object is that a pair of strength members, an optical fiber bundle composed of a plurality of optical fibers arranged between the pair of strength members, and the pair of strength members are the optical fibers. An optical fiber cable comprising a pair of separators that sandwich the optical fiber bundle from a direction different from the direction in which the bundle is sandwiched, and the pair of strength members, the optical fiber bundle, and a jacket that covers the pair of separators. The optical fiber cable is characterized in that a fibrous inclusion is interposed between the optical fiber bundle and the jacket that has entered between the pair of separators.

  Other characteristics of the present invention will be made clear by the description and drawings described later.

  According to the present invention, the branching operation can be facilitated and the optical fiber can be prevented from being pulled out.

1A and 1B are explanatory diagrams of the optical fiber cable of the first embodiment. It is explanatory drawing of the state which divided | segmented the optical fiber cable of FIG. 1B. It is explanatory drawing of an example of an intermittently fixed type optical fiber tape.

  At least the following matters will be apparent from the description and drawings described below.

A pair of strength members, an optical fiber bundle composed of a plurality of optical fibers disposed between the pair of strength members, and the light from a direction different from a direction in which the pair of strength members sandwich the optical fiber bundle. An optical fiber cable comprising: a pair of separators sandwiching a fiber bundle; and the pair of strength members, the optical fiber bundle, and a jacket covering the pair of separators, wherein the optical fiber bundle and the pair of separators An optical fiber cable characterized by interposing a fibrous inclusion between the outer cover that has entered between is clarified.
According to such an optical fiber cable, since the optical fiber does not enter the jacket, branching work can be facilitated. Further, since the fibrous inclusions are interposed between the jacket and the optical fiber, the optical fiber can be prevented from being pulled out.

  It is desirable that the plurality of optical fibers constituting the optical fiber bundle are spirally twisted. Thereby, signal loss can be suppressed.

  The optical fiber bundle may be configured by bundling intermittently fixed optical fiber tapes.

  The fibrous inclusion is preferably an aggregate of long fibers. Thereby, fibrous inclusions easily enter the gaps between the optical fibers.

  It is desirable that a notch is formed on the outer periphery of the jacket. Thereby, the division | segmentation property of an outer jacket is securable.

  It is desirable that M> D, where M is the distance between the pair of notches and D is the width of the optical fiber bundle and the intervening layer. Thereby, it is possible to easily divide the jacket.

The outer diameter of the fibrous inclusion is 50 μm or less, and the area between the pair of separators on which the optical fiber and the fibrous inclusion are mounted, and the outer envelope, and the fibrous inclusion The mounting density defined by a value in which the difference from the cross-sectional area is a denominator and the number of optical fibers is a numerator is preferably 9.0 to 12.0 / mm ² . Thereby, both optical loss and a core wire drawing force can be made favorable.

=== First Embodiment ===
<Optical fiber cable>
1A and 1B are explanatory diagrams of the optical fiber cable of the first embodiment. FIG. 2 is an explanatory diagram of a state where the optical fiber cable of FIG. 1B is divided.

  An optical fiber cable 1 shown in FIG. 1A includes a support wire 2 and a cable body 4. The support wire 2 is configured by covering a steel wire or the like with a jacket. The support wire 2 and the cable body 4 are connected by a neck portion 2A.

When the support wire 2 and the cable body 4 are branched at the neck 2A of the optical fiber cable 1 shown in FIG. 1A, the configuration of the cable body is as shown in FIG. 1B.
In the following description, both the optical fiber cable 1 of FIG. 1A from which the support wire 2 is removed (cable body 4) and the optical fiber cable 4 of FIG. 1B from the beginning are simply referred to as “optical fiber cables”. , 4 is attached.

  In the following description, the longitudinal direction, the long side direction, and the short side direction are defined as shown in FIG. 1A. The longitudinal direction is a direction along the linear strength member 11 of the optical fiber cable 4. The long side direction is a direction along the long side of the cross section of the optical fiber cable 4 and is a direction in which the pair of strength members 11 are arranged. The short side direction is a direction along the short side of the cross section of the optical fiber cable 4, and is a direction orthogonal to the long side direction and the long side direction.

  1B includes a pair of strength members 11, an optical fiber bundle 12 (a plurality of optical fibers 10), a pair of separators 13, an intervening layer 14, and a jacket 16 covering them. I have.

  The strength member 11 is a member (tension member) that resists the shrinkage of the outer cover 16 and suppresses distortion and bending applied to the optical fiber 10 due to the shrinkage of the optical fiber cable 4. The strength member 11 is a linear member, and is embedded in the optical fiber cable 4 so that the longitudinal direction thereof is along the longitudinal direction of the optical fiber bundle 12 (the plurality of optical fibers 10). As the material of the strength member 11, a non-metallic material or a metallic material can be used. Non-metallic materials include fiber reinforced plastic (FRP) such as glass fiber reinforced plastic (GFRP), aramid fiber reinforced plastic (KFRP) reinforced with Kevlar (registered trademark), polyethylene fiber reinforced plastic reinforced with polyethylene fiber, etc. Is possible. As the metallic material, a metal wire such as a steel wire can be used. The cross-sectional shape of the strength member 11 is circular here, but the cross-sectional shape may be, for example, a flat shape, an elliptical shape, a rectangular shape, or a rectangular shape.

  Each of the pair of strength members 11 is arranged in parallel to the longitudinal direction, and is arranged side by side in the long side direction. Between the pair of strength members 11, an optical fiber bundle 12 (a plurality of optical fibers 10), a pair of separators 13, and an intervening layer 14 are disposed.

  The optical fiber bundle 12 is a bundle of optical fibers configured by bundling a plurality of optical fibers 10, and there is a gap between the optical fibers 10. Here, the optical fiber bundle 12 is configured by bundling one or a plurality of intermittently fixed optical fiber tapes.

FIG. 3 is an explanatory diagram of an example of an intermittently fixed type optical fiber tape.
The intermittently fixed type optical fiber tape shown in the figure is an optical fiber tape in which a plurality (here, four) of optical fibers 10 are connected in parallel and intermittently connected. Two adjacent optical fibers 10 of the intermittently fixed optical fiber tape are connected by a connecting portion 5. A plurality of connecting portions 5 are intermittently disposed in the longitudinal direction between two adjacent optical fibers 10. The plurality of connecting portions 5 of the optical fiber tape are intermittently arranged two-dimensionally in the longitudinal direction and the tape width direction. The connecting portion 5 is formed of, for example, an ultraviolet curable resin or a thermoplastic resin. A region other than the connecting portion 5 between the two adjacent optical fibers 10 is a non-connecting portion 6. In the unconnected portion 6, the adjacent two optical fibers 10 are not constrained. For this reason, if the intermittently fixed optical fiber tape is a single unit, the optical fiber tape can be rolled up into a bundle or folded.

  In this embodiment, as described above, the optical fiber bundle 12 is formed by bundling one or a plurality of intermittently fixed optical fiber tapes. Furthermore, in this embodiment, the some optical fiber 10 which comprises the optical fiber bundle 12 is twisted helically. The twist direction may be one direction or the SZ direction.

  The reason why the optical fiber 10 is twisted in this way is to suppress signal loss, as will be described below. For example, when the optical fiber cable 4 is bent in the short side direction, the neutral plane of the bending becomes a surface connecting the pair of strength members 11. The optical fiber 10 outside the neutral plane is stretched and deformed, and the optical fiber 10 inside the neutral plane is compressed and deformed. When the optical fiber 10 is not twisted, the optical fiber 10 inside the neutral plane meanders due to compression deformation, and signal loss increases. On the other hand, when the optical fiber 10 is twisted as in this embodiment, the elongation deformation and the compression deformation of the optical fiber are offset. Therefore, signal loss can be suppressed.

  However, the optical fiber bundle 12 is not limited to a bundle of intermittently fixed optical fiber tapes. A plurality of single-core optical fibers may be bundled, or a plurality of two-core optical fiber tapes may be bundled.

  The separator 13 is a member that separates the outer cover 16 in the short side direction. The separator 13 is also a member that prevents part of the optical fiber bundle 12 (the plurality of optical fibers 10) from being covered with the jacket 16 and facilitates removal of the optical fiber 10. The separator 13 is a tape-like (flat or belt-like) member, and is embedded in the optical fiber cable 4 so that the longitudinal direction thereof is along the longitudinal direction of the optical fiber 10. In the present embodiment, a pair of separators 13 are provided so as to sandwich the optical fiber bundle 12 and the intervening layer 14 from the short side direction, and are respectively arranged such that the tape surface is parallel to the long side direction. The thickness of the separator 13 is, for example, about 0.2 mm. The separator 13 is not fused or bonded to the jacket 16 and the optical fiber 10, and is formed of a material that can be easily peeled off from the jacket 16. “Fusion” means that the outer cover 16 is fused by heat at the time of extrusion molding, and “adhesion” is a method different from fusion by heat at the time of extrusion molding. Means that it is adhered.

  Examples of the material of the separator 13 include thermoplastic resins such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and nylon (registered trademark), or thermosetting resins such as epoxy. Metal materials such as steel, iron (Fe), copper (Cu), and aluminum (Al) can be used.

  The intervening layer 14 is a fibrous inclusion (specifically, PP yarn, polyester yarn, PET yarn, aramid fiber) disposed between the optical fiber bundle 12 and the jacket 16 that has entered between the pair of separators 13. (Kevlar), glass yarn, etc.).

  The intervening layer 14 is adjacent to the optical fiber bundle 12 in the long side direction and is in contact with the optical fiber bundle 12. As a result, the fibrous inclusions (intervening layer 14) also enter the gaps between the optical fibers 10 of the optical fiber bundle 12.

  1A and 1B, the intervening layer 14 is located between the pair of separators 13, and further, between the strength member 11 and the optical fiber bundle 12, and between the optical fiber bundle 12 and the jacket 16. Located between and

  Thereby, the intervening layer 14 suppresses the outer cover 16 from entering the gap (the intermittently fixed optical fiber tape non-connecting portion 6) of the optical fiber 10.

  The intervening layer 14 has a function of stabilizing the cross-sectional shape of the optical fiber bundle 12. When the intervening layer 14 is not provided, if the pair of separators 13 sandwich the optical fiber bundle 12 from the short side direction, the cross-sectional shape of the optical fiber bundle 12 cannot be predicted. By providing the intervening layer 14 on both sides of the optical fiber bundle 12, the cross-sectional shape of the optical fiber bundle 12 becomes stable.

  The intervening layer 14 also has a function of filling the space between the optical fiber bundle 12 and the jacket 16 and suppressing the drawing (movement in the longitudinal direction) of the optical fiber 10.

  Further, the intervening layer 14 also functions as a buffer layer against external stress.

  The fibrous inclusion constituting the intervening layer 14 is preferably an aggregate of long fibers. For example, when the fibrous inclusions are those obtained by slitting a film like PP yarn, the fibrous inclusions cannot enter the gap of the optical fiber 10. On the other hand, when the fibrous inclusions are aggregates of long fibers such as polyester yarn (or PET yarn, aramid fiber (Kevlar), glass yarn), the fibrous inclusions may enter the gaps of the optical fiber 10. it can.

  The jacket 16 is a member (sheath) that covers the other components of the optical fiber cable 4. Here, the jacket 16 collectively covers the periphery of the pair of separators 13, the strength members 11, and the intervening layer 14. Further, the outer cover 16 enters between the pair of separators 13. However, since the intervening layer 14 is present, the jacket 16 does not enter between the optical fibers 10. In FIG. 1A and FIG. 1B, the boundary between the jacket 16 and the intervening layer 14 is indicated by a straight line, but in reality, it is often a curve.

  Further, two pairs of notches 16 </ b> A are formed in the jacket 16. The notch 16A is for ensuring the splitting property of the jacket 16, and when the notch 16A of the jacket 16 is cut with a split tool, the optical fiber cable 4 is split as shown in FIG. Become.

  In FIG. 2, the intervening layer 14 is schematically shown. In FIG. 2, the intervening layer 14 is shown separately from the outer cover 16, but when the outer cover 16 is divided, a part of the intervening layer 14 is in a state of biting into the outer cover 16. Further, when divided, a part of the intervening layer 14 may remain in the gap between the optical fibers 10 of the optical fiber bundle 12. However, even if a part of the intervening layer 14 remains in the gap between the optical fibers 10, the intervening layer 14 is a fibrous member and is not bonded to the optical fiber 10. 10 can be removed.

  If the intervening layer 14 is not provided, the optical fiber 10 enters the jacket 16 that enters between the separators 13. For this reason, when the optical fiber cable 4 is divided, it becomes difficult to take out the optical fiber 10 and the branching operation becomes difficult. Further, in order to prevent the optical fiber 10 from entering the jacket 16, if a space is provided between the jacket 16 and the optical fiber 10, a pulling force (the longitudinal length of the optical fiber cable 4) is applied to the optical fiber 10. When an external force along the direction) is applied, the optical fiber 10 is easily pulled out.

  On the other hand, in this embodiment, the intervening layer 14 is interposed between the optical fiber bundle 12 and the jacket 16 that has entered between the pair of separators 13. For this reason, when the optical fiber cable 4 is divided, the optical fiber 10 does not enter the jacket 16 that enters between the pair of separators 13, and the branching operation is facilitated. Moreover, since the intervening layer 14 is interposed between the jacket 16 and the optical fiber 10, it is possible to prevent the optical fiber 10 from being pulled out (to improve the core wire pulling force described later).

  As shown in FIG. 1B, it is desirable that M <W, where M is the distance between the pair of notches 16A, W is the width of the separator 13, and D is the width of the optical fiber bundle 12 and the intervening layer 14. By doing so, it is possible to protect the optical fiber 10 from the blades of the dividing tool at the time of branching.

  Further, it is desirable that M> D. Thus, when the blade of the dividing tool is inserted into the notch 16A and the outer cover 16 is cut, the outer cover 16 entering the separator 13 makes it difficult for the separator 13 to sink, and the outer cover 16 is divided. Cheap.

=== Second Embodiment ===
The second embodiment is different from the first embodiment in that the optical fiber 10 is not twisted. Since it is the same structure as 1st Embodiment (FIG. 1A, FIG. 1B) except this point, illustration is abbreviate | omitted and it demonstrates using the same code | symbol as 1st Embodiment.

  In the case of the second embodiment, since the optical fiber 10 is not twisted, as described above, when the optical fiber cable 4 is bent, the signal loss is larger than that in the first embodiment. However, also in the second embodiment, since there is the intervening layer 14, the effect of facilitating the branching operation and suppressing the drawing of the optical fiber can be obtained as in the first embodiment.

=== Example ===
The optical fiber cable 4 shown in FIG.

  The optical fiber bundle 12 to be mounted has a total of 24 cores of 4 cores intermittently fixed tape cores × 6 sheets. Further, a steel wire of φ = 0.5 mm was used as the tensile body 11, a nylon flat yarn having a width of 3.3 mm and a thickness of 0.2 mm was used as the separator 13, and a polyester yarn of 2200 dTex was used as the intervening layer 14. The jacket 16 was coated with LLDPE so that the major axis was 5.5 mm and the minor axis was 3.3 mm. In addition, two pairs of notches 16A were formed in the jacket 16 so that the notch spacing M = 2.8 mm.

Then, the outer diameter (average diameter) of the fibers of the intervening layer 14 (polyester yarn) and the mounting density of the optical fiber 10 were evaluated as parameters. Here, the mounting density means that the cross-sectional area of the space (the space surrounded by the pair of separators 13 and the jacket 16) in which the optical fiber bundle 12 and the intervening layer 14 are mounted is Sa, and the cross-sectional area Sb of the intervening layer 14 When N is the number of optical fibers 10 mounted, the value is defined by N / (Sa−Sb). The cross-sectional area Sb of the intervening layer 14 is defined as fineness (dTex) / specific gravity (g / cm ³ ) × 0.0001, and the outer diameter (mm) of the fibers of the intervening layer 14 is √ (Sb × 4 / π).

  In the evaluation of the optical loss, the case where the optical loss at the measurement wavelength of 1550 nm was larger than 0.3 dB / km was evaluated as “x”, and the case where the optical loss was 0.3 dB / km or less was evaluated as “◯” (less than 0.25 dB / km. The core wire pulling force is the tension when the optical fiber core wire starts moving on the side opposite to the tensile end when the optical fiber core wire of the optical fiber cable cut to 10 m is pulled out, and this core wire pulling force is 50 N. / 10 m or less was rated as x, and 50 N / 10 m or more as ◯.

Furthermore, the evaluation of the penetration into the jacket 16 was also performed. The case where the optical fiber 10 entered the jacket 16 was marked as x, and the case where it was not penetrated was marked as ◯.
The evaluation results are as shown in Table 1.

  As shown in Table 1, it can be confirmed that the optical fiber 10 does not enter the jacket 16 by providing the intervening layer 14.

Further, when the mounting density is 9.0 pieces / mm ² or more, the pulling force is good, and the effect of providing the intervening layer 14 appears. In particular, from Table 1, good results are obtained for both the optical loss and the core wire drawing force when the outer diameter of the fibers of the intervening layer 14 is 50 μm or less and the mounting density is 9.0 to 12.0. It can confirm that it is a case (Examples 2-5, 8-11).

=== Others ===
The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified and improved without departing from the gist thereof, and it goes without saying that the present invention includes equivalents thereof.

1 optical fiber cable, 2 support line, 2A neck,
4 Optical fiber cable (cable body),
5 connected parts, 6 unconnected parts,
10 optical fibers, 11 strength members,
12 optical fiber bundles, 13 separators,
14 Intervening layer, 16 outer jacket

Claims (7)

A pair of strength members,
An optical fiber bundle composed of a plurality of optical fibers disposed between the pair of strength members;
A pair of separators that sandwich the optical fiber bundle from a direction different from a direction in which the pair of tensile members sandwich the optical fiber bundle;
An optical fiber cable comprising the pair of strength members, the optical fiber bundle, and a jacket covering the pair of separators,
An optical fiber cable, wherein a fibrous inclusion is interposed between the optical fiber bundle and a jacket that is inserted between the pair of separators. The optical fiber cable according to claim 1,
An optical fiber cable, wherein a plurality of optical fibers constituting the optical fiber bundle are spirally twisted. The optical fiber cable according to claim 1 or 2,
The optical fiber bundle is constituted by bundling intermittently fixed optical fiber tapes. The optical fiber cable according to any one of claims 1 to 3,
The optical fiber cable, wherein the fibrous inclusions are aggregates of long fibers. The optical fiber cable according to any one of claims 1 to 4,
An optical fiber cable, wherein a notch is formed on an outer periphery of the jacket. The optical fiber cable according to claim 5,
An optical fiber cable, wherein M> D, where M is a distance between a pair of notches and D is a width of the optical fiber bundle and the intervening layer. The optical fiber cable according to any one of claims 1 to 6,
The outer diameter of the fibrous inclusion is 50 μm or less, and the area between the pair of separators on which the optical fiber and the fibrous inclusion are mounted, and the outer envelope, and the fibrous inclusion The optical fiber cable is characterized in that a mounting density defined by a value in which the difference from the cross-sectional area is a denominator and the number of optical fibers is a numerator is 9.0 to 12.0 / mm ² .

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