JPH0660808U - Layered fiber optic cable - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve mechanical properties such as impact resistance, compression resistance, and bending resistance without changing the outer diameter and appearance of optical fiber cables. [Structure] A plurality of optical fiber cores are arranged at least on the outer periphery of a tension member, and a twisted aluminum laminate tape is wound to cover a polyethylene sheath between the aluminum laminate tape and the polyethylene sheath of a layer-twisted optical fiber cable. A buffer layer made of a resin that is more elastic than the polyethylene sheath is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a layer-twisted type optical fiber cable in which a multiplicity of optical fiber cores are arranged on the outer circumference of a tension member, twisted together, wound with an aluminum laminate tape, and covered with a polyethylene sheath. The present invention relates to a layer-twisted optical fiber cable capable of improving mechanical properties such as impact resistance, compression resistance, and bending resistance without change.

[0002]

[Prior art]

 The optical fiber strand is a glass fiber drawn from an electric furnace and spun in an optical fiber drawing device. In this state, the surface of the glass fiber is easily scratched and its mechanical strength is weak.Therefore, in order to protect the surface immediately, a thermosetting resin was applied as the primary coating material in the coating die to further protect it. Further, a thermoplastic material such as nylon is coated as a secondary coating material for the purpose of facilitating the handling of the optical fiber and serving as a protective layer when the optical fiber is made into a cable. In this way, the optical fiber is coated with the primary coating, the secondary coating, etc., and the optical fiber core wire is formed.

As described above, since the optical fiber has a remarkable difference in physical or mechanical characteristics from the conventional copper conductor, a primary coating, a secondary coating, and the like are applied to the optical fiber so that the optical fiber is mechanically treated. The characteristics and ease of handling are improved. However, in the case of making a cable, if a large external force such as lateral pressure is applied to the optical fiber core, a slight bending (microbending) will occur in the optical fiber and the transmission loss will increase, so consider the cable structure and manufacturing. There is a need to.

An optical fiber cable is manufactured by collecting the optical fiber core wires. This optical fiber has a conventional structure as shown in FIG. That is, the optical fiber cable 100 is provided with a strength member (tension member) 110 at the center thereof. The strength member 110 is formed of a single steel wire. A polyethylene sheath 120 is coated on the outside of the strength member 110. On the outer circumference of the polyethylene sheath 120, multiple optical fibers 130 (12 fibers in FIG. 2) are arranged. Therefore, the polyethylene sheath 120 is for preventing the optical fiber core wire 130 arranged on the outer periphery of the strength member 110 from being damaged by the strength member 110 which is a single steel wire.

A press winding tape 140 is wound so as to bundle the optical fiber core wires 130 arranged on the outer periphery of the polyethylene sheath 120. A wrap tape (aluminum laminate tape) 150 is wound around the press-wrap tape 140. Further, the outermost layer polyethylene sheath 160 is covered on the wrap tape 150.

[0006]

[Problems to be solved by the device]

 However, in such a conventional optical fiber cable 100, if it is left as it is, a lateral pressure due to an impact force, a compression force, and a bending force is applied from the outside, micro-bending occurs, and the transmission loss increases. Therefore, conventionally, as shown in FIG. 3, the number of the press-wrap tapes 140 wound around the conventional optical fiber cable 100 to bundle the optical fiber core wires 130 arranged on the outer periphery of the polyethylene sheath 120. Has been adopted. Alternatively, conventionally, as shown in FIG. 4, in the conventional optical fiber cable 100, a method of interposing the string 200 as a cushioning material around the optical fiber core wire 130 arranged on the outer periphery of the polyethylene sheath 120 is adopted. ing.

However, in any of these methods, when the outer diameter of the optical fiber cable 100 becomes large and the outer diameter dimension of the optical fiber cable 100 is restricted, the outer diameter dimension of the optical fiber cable 100 becomes smaller. If the number of the press-wrapping tapes 140 is increased or the string 200 is interposed around the optical fiber core wire 130 as a cushioning material within the restriction range, the storage space of the optical fiber core wire 130 is narrowed, and as a communication line. There is a problem that the function deteriorates.

The present invention has been made in view of the above problems of the prior art, and an object thereof is impact resistance without changing the outer diameter dimension and appearance of the optical fiber cable. Another object of the present invention is to provide a layer-twisted optical fiber cable capable of improving mechanical properties such as compression resistance and bending resistance.

[0009]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the layer-twisted optical fiber cable according to the present invention is a layer in which a plurality of optical fiber core wires are arranged at least on the outer circumference of a tension member and twisted together. A buffer layer made of a resin having elasticity higher than that of a polyethylene sheath is provided between the aluminum laminate tape and the polyethylene sheath of the twisted type optical fiber cable.

The buffer layer is preferably made of polyvinyl chloride resin or urethane resin.

[0011]

[Action]

 Since a buffer layer that is more elastic than the polyethylene sheath is provided between the aluminum laminate tape and the polyethylene sheath of the layer-twisted type optical fiber cable, even if an external mechanical force such as impact, compression or bending is applied. , The buffer layer can reduce the mechanical force applied from outside, and the buffer layer is formed as a part of the polyethylene sheath to set the outer diameter of the optical fiber cable to the designed sheath thickness. The outer diameter of the optical fiber cable and the appearance of the optical fiber cable are not changed.

Further, by forming the buffer layer from polyvinyl chloride resin or urethane resin, the buffering force can be further increased.

[0013]

【Example】

 Embodiments of the present invention will be described below. FIG. 1 shows an embodiment of the layer-twisted optical fiber cable according to the present invention.

Reference numeral 1 denotes a layer-twisted optical fiber cable, which constitutes a non-induction, low-loss, high-bandwidth communication cable.

Reference numeral 2 denotes a tensile strength member (tension member), which is arranged at the center of the layer-twisted optical fiber cable 1. The tensile strength member 2 is for pulling and suspending and fixing the layer-twisted optical fiber cable 1 when the layer-twisted optical fiber cable 1 is laid. That is, the tensile strength member 2 is for supporting the layer-twisted optical fiber cable 1 so that tension is not applied to the optical fiber when the both ends of the layer-twisted optical fiber cable 1 are fixed and suspended. The strength member 2 is formed of a single steel wire.

Reference numeral 3 denotes a polyethylene sheath for a strength member, which is coated on the strength member 2. The polyethylene sheath 3 for a strength member is a protective material for preventing the optical fiber core wire 4 twisted on the strength member 2 from being damaged by the strength member 2 made of metal. .

Reference numeral 4 denotes an optical fiber core wire. In the optical fiber drawing device, a glass fiber (optical fiber element wire) composed of a core of a high refractive index portion and a clad of a low refractive index portion drawn from an electric furnace and spun ) Is coated with a thermosetting resin as a primary coating material, and as a secondary coating, a thermoplastic material such as nylon is coated as a secondary coating material. A plurality of (12 cores in this embodiment) optical fibers 4 are arranged on the outer periphery of the strength member 2 covered with the polyethylene sheath 3 for strength member.

Reference numeral 5 denotes a press-winding tape, which is wound around a plurality of optical fiber core wires 4 arranged on the outer circumference of the tensile strength body 2 covered with the tensile strength polyethylene sheath 3. This holding tape 5 is made of polyethylene for a tensile strength body in which a plurality of optical fiber core wires 4 arranged on the outer periphery of the tensile strength body 2 covered with a polyethylene sheath 3 for a tensile strength body are coated on the tensile strength body 2. It is for pressing and fixing to the sheath 3. As the press-wrap tape 5, a vinyl chloride resin-based synthetic resin tape is used.

Reference numeral 6 is a wrap tape (aluminum laminate tape), which is wound around the press-winding tape 5. The wrap tape 6 is for protecting the plurality of optical fiber core wires 4 arranged on the polyethylene sheath 3 for strength member. The wrap tape 6 is made of aluminum laminate, has excellent mechanical properties, can suppress thermal contraction of the outermost polyethylene sheath 8, and has a moisture-proof effect.

Reference numeral 7 denotes a buffer layer, which is made of synthetic resin having a far higher elasticity than the outermost polyethylene sheath 8. That is, the outermost layer sheath has a double structure of the buffer layer 7 and the outermost layer polyethylene sheath 8. The outermost layer sheath is formed by coating the buffer layer 7 and the outermost layer polyethylene sheath 8 by double extrusion. Further, the outermost layer sheath constituted by the buffer layer 7 and the outermost layer polyethylene sheath 8 is set to the designed sheath thickness. Therefore, as for the sheath thickness of the outermost layer sheath, the thickness of the buffer layer 7 and the thickness of the outermost layer polyethylene sheath 8 may be determined within a range of a predetermined sheath thickness (designed sheath thickness). In this case, the thickness of the buffer layer 7 is arbitrarily determined according to the required mechanical characteristics of the layer-twisted optical fiber cable 1. The buffer layer 7 is specifically made of polyvinyl chloride resin or urethane resin.

Reference numeral 8 denotes an outermost polyethylene sheath, which is formed by extrusion-coating polyethylene (PE) on the buffer layer 7. The outermost layer polyethylene sheath 8 is coated on the outermost layer in order to protect the layer-twisted optical fiber cable 1. This outermost layer polyethylene sheath 8 constitutes the outermost layer sheath of the layer-twisted optical fiber cable 1 together with the buffer layer 7.

Therefore, when lateral force such as impact force, compression force, bending force, etc. is applied to the layer-twisted optical fiber cable 1 from the outside, the impact force, compression force, bending force, etc. are generated by the buffer layer 7 constituting the outermost layer sheath. Is absorbed, and lateral pressure is not applied to the plurality of optical fiber core wires 4 arranged on the outer periphery of the tensile strength body 2 covered with the tensile strength polyethylene sheath 3. In this way, since lateral pressure is not applied to the plurality of optical fiber core wires 4, it is possible to prevent the occurrence of microbending.

[0023]

[Effect of device]

 Since the present invention is configured as described above, it has the following effects.

In the layer-twisted type optical fiber cable according to claim 1, a layer-twisted type optical fiber cable in which a plurality of optical fiber core wires are arranged at least on the outer circumference of the tension member and the aluminum laminate tape is wound and a polyethylene sheath is covered. Since a buffer layer made of a resin that is more elastic than the polyethylene sheath is provided between the aluminum laminate tape of the optical fiber cable and the polyethylene sheath, impact resistance is maintained without changing the outer diameter dimension and appearance of the optical fiber cable. It is possible to improve mechanical properties such as compression resistance and bending resistance.

In the layer-twisted optical fiber cable of the second aspect, since the buffer layer is made of polyvinyl chloride resin or urethane resin, the buffer force can be further increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a layer-twisted optical fiber cable according to the present invention.

FIG. 2 is a cross-sectional view of a conventional layer-twisted optical fiber cable.

FIG. 3 is a cross-sectional view of a layer-twisted optical fiber cable having a structure in which the number of press-wrapping tapes in the related art is increased to reduce the impact from the outside.

FIG. 4 is a cross-sectional view of a layer-twisted optical fiber cable having a structure in which a string is interposed around a conventional optical fiber core as a cushioning material.

[Explanation of symbols]

1 …………………………………………………… Layer-twisted optical fiber cable 2 ……………………………………………… Tensile body 3 ………………………………………………………… Polyethylene sheath for tensile strength body 4 …………………………………………………… Optical fiber core Wire 5 ………………………………………………………… Presser foot tape 6 …………………………………………………… Aluminum laminated tape 7 …………………………………………………… Buffer layer 8 …………………………………………………… Outermost layer polyethylene sheath

Claims (2)

[Scope of utility model registration request] 1. A layer-twisted optical fiber cable in which a plurality of optical fiber cores are arranged at least on the outer periphery of a tension member and a twisted aluminum laminate tape is wound to cover a polyethylene sheath, wherein the aluminum laminate tape and the polyethylene sheath. A layer-twisted optical fiber cable, characterized in that a buffer layer made of a resin having elasticity higher than that of a polyethylene sheath is provided between the optical fiber cable and the polyethylene sheath. 2. The layer-twisted optical fiber cable according to claim 1, wherein the buffer layer is made of polyvinyl chloride resin or urethane resin.