JP2008310041A - Multi-fiber optical cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-fiber optical cable capable of minimizing a gap between a tearing string and a jacket produced when an impact is applied to the cable and the jacket is flattened and capable of preventing disconnection or the like caused by that optical fibers are put between the tearing string and the jacket. <P>SOLUTION: In the multi-fiber optical cable, a collection of a plurality of single-core coated optical fibers 21 is covered with the jacket 24 and the jacket tearing string 26 is disposed in the jacket 24, wherein, as the jacket tearing string 26, a jacket tearing string 26<SB>1</SB>having a buffer layer 27 on the outer circumference thereof is used. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-core optical fiber cable which is a component part of information wiring using an optical fiber outdoors or indoors.

  Currently, in order to provide a wide variety of broadband services, optical fibers having the characteristics of low loss and broadband have been introduced into communication networks. When an optical fiber is used in a communication network, the optical fibers are bundled and coated to provide a multi-core optical fiber cable. For example, a multi-core optical fiber cable mounted with a single-core coated optical fiber has been proposed (see, for example, Patent Document 1). In order to easily take out the single-core coated optical fiber inside the optical fiber cable, a cord for tearing (hereinafter referred to as a tearing cord) in which tetron fiber or Kevlar fiber is twisted or used as it is is provided in the jacket. Embedded in. Further, in order to improve the jacket division by using this tear string, for example, as shown in Patent Document 2, a method of exposing a part of the tear string and embedding the remainder in the jacket has been proposed.

JP 2007-41568 A JP 2001-42182 A

  However, as shown in FIG. 4, in the multi-core optical fiber cable 12 in which a plurality of single-core coated optical fibers 11 (partially not shown) are assembled and mounted, all of the tear strings 14 are formed in the jacket 13. Alternatively, since most of the fibers are embedded, an impact is applied to the tear string 14 side of the optical fiber cable 12, and when the jacket 13 is greatly flattened, the embedded portion of the tear string 14 opens, and the multi-fiber optical fiber cable 12, the single-core coated optical fiber 11 is sandwiched between the tear string 14 and the jacket 13 (A portion in FIG. 4), and the single-core coated optical fiber 11 is excessively bent, resulting in a large There is a problem that optical loss increases or breaks. Reference numeral 15 denotes a tensile body such as a steel wire.

  In general, it is possible to prevent pinching of the single-core coated optical fiber by gathering the single-core coated optical fibers and then holding the tape with a tape-like material. There is a problem that the manufacturing process is increased and the outer diameter of the multi-fiber optical fiber cable is increased by the amount of press-wrapping with the tape-like material. In addition, it is possible to prevent the optical fiber from being broken by increasing the thickness of the outer sheath of the multi-core optical fiber cable, but the problem that the outer diameter of the multi-core optical fiber cable is increased similarly to the above problem. is there.

  The present invention has been made in view of the above circumstances, and it is possible to reduce the gap between the tear string and the jacket that occurs when the cable is impacted and the jacket is flattened. It is an object of the present invention to provide a multi-core optical fiber cable that can prevent disconnection or the like due to being sandwiched between the outer jacket and the like.

  In order to achieve the above object, the present invention provides a multi-core optical fiber cable in which a plurality of single-core-coated optical fibers are assembled to provide a jacket, and the jacket is provided with a string for tearing the jacket. As the tearing cord, an outer tearing cord provided with a buffer layer on the outer periphery is used.

  Further, the present invention is a multi-core optical fiber cable in which a plurality of single-core coated optical fibers are assembled to provide a jacket, and the jacket is provided with a string for tearing the jacket. It is characterized by using a molding-shaped outer-stripping string provided with fibers on the outer periphery.

  Further, the present invention is characterized by a structure in which an outer cover is provided on an outer periphery in which a plurality of the above-mentioned multi-core optical fiber cables are gathered around a tensile strength member in a straight or twisted manner.

  The multi-core optical fiber cable of the present invention is designed to reduce the size of the gap formed between the tear string and the jacket when the cable is subjected to an impact and the jacket is flattened. The single-core coated optical fiber thus formed is not sandwiched between the jacket and the tear string, and excessive bending applied to the optical fiber and disconnection of the optical fiber can be prevented. In addition, it is possible to prevent the optical fiber from being caught without gathering the single-core coated optical fiber from the tape-like material, and compared with the case where the pressure-wound is made from the tape-like material. As a result, the cable outer diameter can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a structural cross-sectional view showing a multi-core optical fiber cable used in an embodiment of the present invention. As shown in FIG. 1, an identification yarn or identification tape 22 is formed on the outer periphery of a plurality of single-core coated optical fibers 21 that are coated concentrically on the outer periphery of the optical fiber, for example, 20 straight or twisted together. To form an optical fiber unit 23 of an optical fiber bundle, and further, a plurality of optical fiber units 23 wound with the identification yarn or identification tape 22, for example, five straight or twisted together on the outer periphery densely gathered together A multi-core optical fiber cable is formed by applying a jacket 24. In addition, a tensile strength body 25 such as two steel wires is embedded in the jacket 24 so as to be symmetrical with respect to the center of the multi-core optical fiber cable, and from the inside of the multi-core optical fiber cable. In the outer sheath 24, two tearing cords (outer tearing cords) 26 for easily taking out the single-core-coated optical fiber 21 are symmetrical with respect to the center of the multi-core optical fiber cable. Embedded.

  Note that a multi-core optical fiber cable may be configured by applying a jacket to the outer periphery in which a plurality of single-core coated optical fibers, for example 100 straight or twisted, are closely gathered together.

FIG. 2 is a structural explanatory sectional view showing an example of a tear string according to the embodiment of the present invention. As shown in FIG. 2, as tear string 26 ₁ of 2 in the vicinity of the inner peripheral surface in the envelope 24 of the multi-core optical fiber cable is positioned symmetrically to each other with respect to the multi-fiber optical fiber cable center, slits to expose a portion of the string 26 _1, is provided embedded rest on envelope 24.

As a material used for the tear string 26 _1, high tensile strength, as tetronic fibers or Kevlar fibers, or those twisted are used.

Here, the tearing periphery of the cord 26 _1, soft material concentrically, i.e. lower elastic modulus than the material of the envelope 24, the buffer layer 27 is provided with elongation amount consists of large material. For example, the buffer layer 27 is cut when a large impact is applied to the multi-core optical fiber cable so that a weight of 1 kg in weight is dropped from the height of 1 m onto the multi-core optical fiber cable, and the jacket 24 is flattened. string embedding unit tries to open (see portion a in FIG. 4) comprises a buffer layer 27 is some displacement occurs, reducing the size of the gap formed between the tearing string 26 ₁ and the cover fabric 24 be able to.

  As the material used for the buffer layer 27, for example, an ultraviolet curable resin, a urethane resin, a silicon resin, or the like having a lower elastic modulus and a larger elongation than polyethylene used for the outer sheath 24 of a multi-core optical fiber cable is used. I can do it.

  In addition, as a result of manufacturing a multi-core optical fiber cable having the structure shown in FIG. 2 and actually carrying out a test for applying a large impact such as dropping a weight of 1 kg from a height of 1 m to the multi-core optical fiber cable, It was confirmed that there was no increase in optical loss and no breakage of the single-core coated optical fiber 21 due to the sandwiching of the core-coated optical fiber 21.

FIG. 3 is a cross-sectional view illustrating the construction of another example of the tear string according to the embodiment of the present invention. As shown in FIG. 3, in the vicinity of the inner peripheral surface of the outer sheath 24 of the multi-core optical fiber cable, the _two tear strings 262 are positioned symmetrically with respect to the center of the multi-core optical fiber cable. slits to expose a portion of the cord 26 _2, provided embedded rest on envelope 24.

As a material used the the tearing cord 26 _2, high tensile strength, as tetronic fibers or Kevlar fibers, or those twisted are used.

Here, examples of tearing cord 26 _2, the fiber 28 using a mall-like tearing cord attached concentrically on the outer circumference. A mall is known as a wire or string for handicrafts that is often used when packaging sweets, for example, and is formed by specially processing fibers concentrically on the outer periphery.

Examples tearing cord 26 _2, by the use of a mall-like tear string, fiber 28 attached to the outer periphery of the cord 26 ₂ tear is embedded in the jacket 24 in the time multifiber optic cable manufacturing, tearing cord 26 ₂ Since a fiber bridging effect is obtained at the interface between the outer sheath 24 and the outer sheath 24 material, for example, a large impact such as dropping a weight of 1 kg from a height of 1 m onto a multi-core optical fiber cable. added to the core optical fiber cable, when the envelope 24 is flattened, tearing attempts to open the straps 26 _second buried portion (see portion a in FIG. 4) is, by fiber crosslinking (bridging) effect, the jacket 24 in the tearing cord 26 _second buried portion, the tearing can reduce the magnitude of the gap formed between the string 26 ₂ and the cover fabric 24 and the single-core coated optical fiber 21 into the gap The effect of protection so as not rare to do so.

As described above, for the impact applied to the tear string side of the multi-core optical fiber cable, when the outer cover is flattened, so as to obtain an effect of making it difficult to open the tear string embedded portion, A tear string in which fibers are concentrically attached to the outer periphery, or a tear string in which a buffer layer made of a soft material is provided concentrically on the outer periphery of the tear string is used.
In addition, the multi-core optical fiber cable may be configured by applying a jacket to the outer periphery of the multi-fiber optical fiber cable configured as described above and gathered by a plurality of straight or twisted pieces around the tensile strength body. Can accommodate more single-core coated optical fibers.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

It is composition explanation sectional view showing the multi-core optical fiber cable used for the embodiment of the present invention. It is a composition explanation sectional view showing an example of a tear string concerning an embodiment of the present invention. It is a composition explanation sectional view showing other examples of a tear string concerning an embodiment of the present invention. It is structure explanatory sectional drawing which shows the conventional multi-core optical fiber cable.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 21 ... Single-core coated optical fiber, 22 ... Identification thread or identification tape, 23 ... Optical fiber unit, 24 ... Outer jacket, 25 ... Strength member, 26 ... Rupture string

Claims (3)

In a multi-core optical fiber cable in which a plurality of single-core coated optical fibers are assembled to provide a jacket, and the jacket is provided with a string for tearing the jacket,
A multi-fiber optical fiber cable characterized in that as the jacket tearing string, a jacket tearing string having a buffer layer on the outer periphery is used. In a multi-core optical fiber cable in which a plurality of single-core coated optical fibers are assembled to provide a jacket, and the jacket is provided with a string for tearing the jacket,
A multi-fiber optical fiber cable using a molding-like outer-stripping string having fibers on the outer periphery as the outer-stripping string.   A multi-core optical fiber cable having a structure in which an outer cover is provided on an outer periphery in which a plurality of the multi-fiber optical fiber cables according to claim 1 are further gathered straight or twisted around a tensile strength body.

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