JP6542648B2 - Fiber optic cable - Google Patents

Description

  The present invention relates to an optical fiber cable, and more particularly to an optical fiber cable in which a plurality of optical fiber cores are covered with a cable jacket.

  A slot type and a slotless type are known as multifiber optical fiber cables. The slot type has a slot rod (also referred to as a spacer) capable of containing an optical fiber core wire, the outer periphery of which is wound with a winding tape, and a cable sheath (also referred to as a sheath) is provided. In this slot type, the cable sheath and the slot rod protect the optical fiber core against the pressure from the side of the optical fiber cable (hereinafter referred to as the side pressure).

  On the other hand, in the slotless type, the optical fiber core is covered with, for example, inclusions, and a cable jacket is provided on the outer periphery thereof. In the slotless type, the cable jacket mainly protects the optical fiber core against the side pressure. Therefore, the cable jacket is thickened to obtain the necessary strength. Normally, one tearing cord for dismantling the cable is embedded in the cable sheath, but as the cable sheath becomes thicker, it becomes difficult to tear the cable sheath with the embedded tearstring. . On the other hand, for example, Patent Document 1 discloses an optical fiber cable technology in which outer and inner tear cords are arranged in the radial direction of the cable and these are connected by a connecting material in order to improve workability at the time of disassembly. There is.

JP, 2009-198701, A

  In the technique of this patent document 1, the outer tearing cord, the connecting member, and the inner tearing cord are integrally formed, and the outer tearing cord is picked up, and the inner tearing cord is pulled out to tear the cable jacket. It has become. However, even with this configuration, it is difficult to tear the cable sheath as the cable sheath becomes thicker, since most of the cable sheaths are torn substantially by one tearing cord. For this reason, even if the cable jacket becomes thick, it is desirable to tear the cable jacket with as little force as possible.

  The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide an optical fiber cable which requires a small force to tear the cable jacket with a tearing cord.

Optical fiber cable according to one embodiment of the present invention, a set core summarized in round with presser winding tape a plurality of optical fibers, the cable jacket provided around the said set core, the optical fiber cable and a jacket tear string being pulled, a plurality of the external optical fiber cable which the tear cord is embedded in the outside of the cable, the previous Kigai the tear string, composed of at least three the are arranged side by side at 2.5mm or less equally spaced along the radial direction on one side of the set core is embedded in the cable jacket in the same layer in independent state.

  According to the above, the force required to tear the cable jacket with the tear cord may be small.

1 is a cross-sectional view showing an example of an optical fiber cable according to an embodiment of the present invention. It is a figure which shows an example of the structure of an intermittent tape core. It is a figure explaining the deformation | transformation of the optical fiber cable at the time of side pressure application. It is a figure explaining an example which tears the cable jacket of an optical fiber cable.

Description of the embodiment of the present invention
First, the contents of the embodiment of the present invention will be listed and described.
An optical fiber cable according to one aspect of the present invention comprises: (1) a collective core formed by holding a plurality of optical fiber cores in a round shape with a holding and winding tape; a cable jacket provided around the collective core ; and a jacket tear string which is pulled from the fiber cable, a plurality of the external optical fiber cable which the tear cord is embedded in the outside of the cable, the previous Kigai the tear string, at least three And are arranged at equal intervals of 2.5 mm or less along the radial direction on one side of the collective core, and are embedded in the cable jacket in the same layer in an independent state. As described above, when the respective tearing cords are arranged side by side along the radial direction of the collective core so as to be independent, it is sufficient to tear a part of the cable sheathing from the outside, so the cable sheathings are tearing cords The amount of force required to tear it is small. And if it is constituted by three or more, since the coating may be torn apart three or more times, the cable jacket can be torn by smaller force. In addition, if the distance is 2.5 mm or less, the coating thickness is equivalent to that of, for example, the cable sheath of a 100-fiber optical fiber cable, so that the force for tearing may be small.

( 2) Each of the sheath tear cords is configured with a tensile breaking strength of 15 kgf or less. Since the tearing force may be small with a tensile breaking strength of 15 kgf or less, a general-purpose cord-like member can be used.

Details of the Embodiment of the Present Invention
Hereinafter, preferred embodiments of the optical fiber cable according to the present invention will be described with reference to the attached drawings.
FIG. 1 is a cross-sectional view showing an example of an optical fiber cable according to an embodiment of the present invention, and FIG. 2 is a view showing an example of the structure of an intermittent tape core. In addition, although the structure which does not have a support wire is demonstrated with the following optical fiber cable 1, the self-supporting structure provided with the support wire may be sufficient.

The optical fiber cable 1 shown in FIG. 1 is a slotless type, and has, for example, a round collective core 20 and a cable jacket 30 formed around the collective core 20.
The collective core 20 accommodates, for example, 2000 cores using 500 sheets of the four intermittent cored cables 10. In the example of illustration, 100 bundles of intermittent tape cores 10 are carried out by coarse winding cords (illustration abbreviation) etc., and five bundles are formed. In this case, since the intermittent tape core wire 10 can be freely deformed in the collective core 20, it is effective for increasing the density.

  In the intermittent tape core, a plurality of optical fiber cores are arranged in a parallel line, and adjacent optical fiber cores are intermittently connected by the connecting portion and the non-connecting portion. Specifically, FIG. 2 (A) shows a state in which the intermittent tape core is closed, and FIG. 2 (B) shows a state in which the intermittent tape core is opened in the arrangement direction. The four optical fiber cores 11 to 14 are arranged in a parallel row (also referred to as a four-core intermittent tape core), and adjacent optical fiber cores are intermittently connected by the connecting portion 15a and the nonconnecting portion 15b. ing.

  The optical fiber core housed in this intermittent tape core is a glass fiber with a standard outside diameter of 125 μm and a coating outside of about 250 μm coated with an outside diameter of an optical fiber strand. The number of optical fiber cores accommodated is arbitrary. In addition, the intermittent tape core wire does not have to be provided with a connecting part and a non-connecting part every one core, for example, even if core wires of two cores are integrated intermittently by the connecting part and the non-connecting part Good.

As shown in FIG. 1, the assembly core 20 is, for example, vertically bundled or laterally wound with a holding and winding tape 21 into a round shape by bundling five bundles obtained by bundling 100 intermittent tape cores 10.
In the collective core, for example, a stack of a plurality of ordinary tape ribbons is bundled and covered with inclusions or contained, or a single optical fiber ribbon is bundled to form a plurality of bundles. They may be covered and contained with inclusions.

The outer side of the holding and winding tape 21 is covered with a cable jacket 30 made of, for example, PE (polyethylene), PVC (polyvinyl chloride) or the like.
The cable jacket 30 includes two tension members (also referred to as tensile members) 31 for maintaining strength in the longitudinal direction, and, for example, six first to sixth cables for tearing the cable jacket 30 in the cable longitudinal direction. The three tearing cords 32 to 34 are vertically attached and embedded at the time of extrusion of the cable jacket 30. The first to third tearing cords 32 to 34 correspond to the outer covering tearing cord of the present invention.

For the tension member 31, a wire having a resistance against tension and compression, for example, a steel wire or FRP (Fiber Reinforced Plastics) is used, and is provided on both sides of the collective core 20.
The first to third tearing cords 32 to 34 are, for example, first to third three on both sides of the collective core 20 at a position on a line orthogonal to a line connecting the centers of the two tension members 31. Each book is provided.

The first to third tearing cords 32 to 34 are, for example, cord-like members having a circular cross-sectional shape in which a resin material such as nylon or polyester is used, and are arranged, for example, on the same straight line along the radial direction of the collective core 20 It is.
Specifically, first, the third tear cord 34 is disposed in contact with the surface of the holding and winding tape 21 and extends along the longitudinal direction of the cable.

Next, the second tear cord 33 is disposed outside the third tear cord 34. The second tearing cord 33 is along the longitudinal direction of the cable in a state independent of the third tearing cord 34, that is, in a state where the cable jacket 30 is filled between the second tearing cord 33 and the third tearing cord 34. It extends.
In addition, a first tear cord 32 is disposed outside the second tear cord 33. The first tearing strap 32 is in a state independent of the second tearing strap 33, that is, in a state in which the cable jacket 30 is also filled between the first tearing strap 32 and the second tearing strap 33 in the longitudinal direction of the cable. It extends along.

  In addition, the projection part 35 is formed at the time of extrusion molding in the cable jacket 30 so that the embedding | burying position of the 1st tearing cord 32 can be visually recognized from the outside.

FIG. 3 is a view for explaining the deformation of the optical fiber cable at the time of side pressure application.
When the slotless optical fiber cable as described in FIG. 1 is crushed by the side pressure, the area inside the cable is reduced and the occupancy density of the optical fiber core accommodated is increased, so bending force is applied to the optical fiber core. In addition, transmission loss may increase. For this reason, the thickness of the cable jacket is designed to such a thickness as to ensure normal side pressure characteristics.

Specifically, as shown in FIG. 3, when the cable jacket 30 is regarded as an elastic pipe, the deformation amount Δ of the cable, the side pressure F, the cable outer diameter OD, the cable inner diameter ID, the Young's modulus E of the cable jacket, Assuming that the side pressure application length L and the correction coefficient A, the relationship between the deformation amount Δ of the cable and the specifications of the cable structure is given by the following equation.
Δ = A × 2 × F × (π / 8-1 / π) × [(OD + ID) / 4] 3 / [E × L × [(OD-ID) / 2] 3/12]

  In this equation, (OD + ID) / 4 corresponds to the radius of a circle passing the center line of the cable jacket, and (OD-ID) / 2 corresponds to the thickness of the cable jacket. It can be seen that when the diameter is considered constant, the amount of deformation of the cable increases as the diameter of the cable increases. Therefore, in order to reduce the amount of deformation of the cable, it is necessary to make the cable jacket thicker as the number of cores increases. For example, in the case of a 100-fiber optical fiber cable, it is sufficient for the thickness of the cable jacket to be about 2.5 mm, whereas in the case of a 1000-fiber cable, the thickness of the cable jacket is In the case of the 2000-fiber optical fiber cable described in FIG. 1, the thickness of the cable jacket is required to be about 3.5 mm.

On the other hand, in the cable jacket 30 of the optical fiber cable 1 described in FIG. 1, which is an embodiment of the present invention, first to third tearing cords 32 to 34 are provided, for example, three each on both sides of the collective core 20. ing.
In addition, the third tearing cord 34 and the second tearing cord 33 in the radial direction of the collective core 20 so that the cable jacket 30 can be torn apart with the same force one by one from the outside until the collective core 20 is exposed. And the distance between the second tear cord 33 and the first tear cord 32 are provided at equal intervals. Further, if the distance between them is set to, for example, 2.5 mm or less, a force enough to tear a 100-core optical fiber cable is sufficient.

  In each of the first to third tearing cords 32-34, when tearing a thick cable jacket, it is necessary to use one having high tensile breaking strength so as not to cut along the way. If the thickness is, for example, about 2.5 mm, it can be made of one having a low tensile breaking strength (for example, 15 kgf or less). If the cable jacket can be torn using a general-purpose string-like member having a low tensile breaking strength, it can contribute to the reduction of the manufacturing cost.

FIG. 4 is a view for explaining an example in which the cable sheath of the optical fiber cable is torn. In addition, in FIG. 4, in order to clarify the 1st-3rd tearing cords 32-34, the cross section of the cable is also shown.
In the branching operation of the optical fiber cable, a worker first inserts a tool, for example, into the projection 35 located in the portion of the optical fiber cable 1 where the intermediate branching is desired, and picks up the first tearing cord 32.

When the first tearing cord 32 is pulled out in the longitudinal direction of the cable, as shown in FIG. The pull-out length of the first tearing cord 32 is, for example, about 50 cm required for the middle branch.
Subsequently, when, for example, a tool is inserted into this tear 40 and the second tearing string 33 is picked out and pulled out along the longitudinal direction of the cable, the tear 40 in the cable jacket 30 becomes deeper. Then, the assembly core 20 is exposed from the tear 40 by, for example, inserting a tool into the deep tear 40 and picking out the third tear cord 34 and pulling it out along the longitudinal direction of the cable.

Similarly, with regard to the first to third tearing cords 32 to 34 shown in the lower side of FIG. 4, the first tearing cord 32, the second tearing cord 33, and the third tearing cord 34 are picked in this order to extend along the cable longitudinal direction. When it is pulled out, the collective core 20 is exposed from the tear.
Then, when the cable jacket 30 remaining around the collective core 20 is peeled off, and the holding and winding tape 21 is peeled off from the exposed collective core 20, the inside of the intermittent tape core can be taken out.

  As described above, if the respective tearing cords 32 to 34 are arranged side by side independently in the radial direction of the collective core 20, the collective core 20 can not be exposed in one pulling operation, but it is possible to Since the cable jacket 30 is torn by each book, the force required to tear the cable jacket 30 with the tearing cord is small, and the tearing cord is not broken in the middle.

  As described above, the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is not limited to the examples described above, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. .

DESCRIPTION OF SYMBOLS 1 ... Optical fiber cable, 10 ... Intermittent tape core wire, 11-14 ... Optical fiber core wire, 15a ... Connection part, 15b ... Non-connection part, 20 ... Assembly core, 21 ... Press winding tape, 30 ... Cable jacket, 31: Tension member, 32: first tear cord, 33: second tear cord, 34: third tear cord, 35: projection, 40: tear.

Claims (2)

A collective core in which a plurality of optical fiber cores are put together in a round shape with a holding and winding tape, a cable jacket provided around the collective core, and a jacket tear cord drawn from the optical fiber cable , A fiber optic cable having a plurality of the jacket tearing cords embedded in the cable jacket,
Before Kigai the tear cord is composed of at least three, are arranged side by side at equal intervals on one side along the radial direction to 2.5mm below the set core, said cable in the same layer in independent states Fiber optic cable embedded in the jacket. The optical fiber cable according to claim 1, wherein each of the jacket tear cords is configured with a tensile breaking strength of 15 kgf or less.

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