JP2007212942A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable which effectively prevents an optical fiber inside from being bitten and damaged by squirrel, rat, and the like, and permits use of a conventional tool and a connection member without spoiling workability. <P>SOLUTION: The optical fiber cable is made up by covering a cable main body part 21 covered in package with a main body part sheath 22 with tension members 24 arranged linearly on both sides of a coated optical fiber 23 and protective members 26a disposed so as to hold both sides of the cable main body part 21 in-between, with a jacket sheath 27 in package. The protective members 26a are formed belt-like having a flat plate or U-shaped cross section, and the protective members 26a and the cable main body part 21 are arranged so as to be mutually movable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical fiber cable such as a drop cable protected from rodents such as squirrels and mice and birds.

  With the rapid spread of the Internet, etc., in addition to increasing the speed of information communication and increasing the amount of information, the construction of an optical network for two-way communication and large-capacity communication has recently progressed. FTTH (Fiber To The Home) service that provides high-speed communication services has been started. As a result, there is an increasing demand for drop cables and indoor cables used for indoor wiring. These optical fiber cables are generally formed by embedding and integrating a tension member in the cable main body parallel to the optical fiber core, and a self-supporting optical fiber cable having a detachable support line is used. (For example, refer to Patent Document 1).

Along with the increase in the use of optical fiber cables having such a structure, problems that have not existed before have also occurred. For example, there has been a case where a drop cable is bitten by a squirrel or a mouse and an internal optical fiber is damaged. On the other hand, conventionally, in a multi-core type optical fiber cable having a relatively large cable diameter, the optical fiber core wire is covered with a hard plastic, stored in a metal tube, or a metal tape is wrapped around the cable jacket. (For example, refer to Patent Document 2). In addition, a method of including a spicy component in the cable jacket (for example, see Patent Document 3) is also known.

JP 2003-98409 A JP-A-6-174985 JP 2005-37526 A

  In general, drop cables used for pulling optical fibers are usually connected with the optical fibers in the cable in a single-core state. Therefore, as a drop cable, a single-core optical fiber is accommodated in one to a plurality of cores. There are many things. Further, as shown in FIG. 3A, for example, an optical fiber cable 1 for a drop cable usually has a structure in which a cable body 2 and a support wire 3 are connected and integrated by a neck 4. It is done.

  The cable main body portion 2 of the optical fiber cable 1 is formed by arranging tension members 6 on both sides of the optical fiber core wire 5 and integrally housing and covering them with a main body jacket 7. The support wire portion 3 is formed, for example, by covering the outer periphery of a support wire 9 made of a steel wire of about 1.2 mmφ with a support wire jacket 10. The same resin material such as black polyethylene is used for the main body jacket 7 and the support wire jacket 10, both of which are connected together via a narrow neck 4, and are formed collectively by extrusion molding. The

  The cable body 2 and the support wire 3 are formed so that the neck 4 can be separated by hand. For example, the cable body 2 and the support wire 3 are separated at both ends of the optical fiber cable 1, the end of the support wire 3 is fixed to a building or the like with a gripping tool, and the end of the cable body 2 is closed. Or install indoors. Further, a V-shaped notch 8 is provided on the side surface of the cable main body 2, and the inner optical fiber 5 is taken out by tearing the main body sheath 7 at this notch portion, so that branch connection and terminal formation are easy. It can be done.

  The optical fiber cable having the above-described configuration has a thin and simple structure in which the outer periphery of the optical fiber core 1 is coated with a single layer of resin. Is easy to break. Optical fiber cables of relatively small diameter, such as drop cables and indoor cables, have the appropriate hardness and thickness for rodents such as squirrels and mice without the risk of electric shock, and will continue to cause damage in the future. is expected. Therefore, for example, as shown in FIG. 3B, a plurality of optical fiber ribbons 13 are accommodated in the slot 12 and integrated with the outer cover 15 together with the support wire 14, and a metal such as stainless steel is provided inside the outer cover 15. It is conceivable to prevent the optical fiber from being damaged by squirrels and mice by using the high-strength optical fiber cable 11 in which the tape 16 is vertically attached to the tube.

  However, as shown in FIG. 3B, the structure in which the optical fiber is surrounded by a metal tube such as stainless steel has a small diameter in a drop cable or indoor cable having a small number of optical fiber cores and a small diameter. There is a problem that the processing cost is high, and the bending rigidity is increased, making it difficult to handle. Furthermore, in the cable terminal processing, it takes time to take out the optical fiber core wire, and a dedicated tool and careful work are required.

  The present invention has been made in view of the above-described circumstances, and effectively prevents damage to an internal optical fiber by being bitten by a squirrel, a rat, or the like, and can be used with conventional tools and connection members. An object is to provide an optical fiber cable that does not impair the performance.

  An optical fiber cable according to the present invention includes a cable main body portion in which tension members are linearly arranged on both sides of an optical fiber core wire and collectively covered with a main body sheath, and a protective member disposed so as to sandwich both side surfaces of the cable main body portion. Are collectively covered with an outer sheath. The protective member is formed in a strip shape having a flat plate shape or a U-shaped cross section, and the protective member and the cable main body are arranged to be movable relative to each other.

  According to the present invention, it is possible to effectively prevent damage to a cable main body covering an optical fiber even when the protective member is exposed due to the optical fiber cable being squeezed by a squirrel or a rat. Can improve reliability. Moreover, since the shape of the cable main body part directly covered with the optical fiber can be the same as the conventional structure, it can be used as it is without changing the connecting member or the tool. Furthermore, the protection member and the cable body can be moved relative to each other, so that stress when the optical fiber cable is bent can be alleviated and the ease of bending can be prevented from being greatly impaired.

  An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining the first embodiment, and FIG. 2 is a diagram for explaining the second embodiment. In the figure, 20a and 20b are optical fiber cables, 21 is a cable body part, 22 is a body part sheath, 23 is an optical fiber core wire, 24 is a tension member, 25 is a tear notch, 26a and 2b are protective members, and 27 is An outer sheath, 28 is a notch, 29 is a neck, 30 is a support wire, and 31 is a support wire sheath.

  FIG. 1 is a diagram for explaining the first embodiment, and FIG. 1 (A) shows an example of a self-supporting optical fiber cable 20a having a support line portion called a drop cable, and FIG. These show the example of the optical fiber cable 20b which does not have a support line part also called the indoor cable. As shown in FIG. 1A, a self-supporting optical fiber cable 20a according to the present invention further comprises a cable main body 21 in which an optical fiber core wire 23 and a tension member 24 are collectively covered with a main body sheath 22 and a protective member. It is configured by covering with an outer sheath 27 via 26a.

  The cable main body 21 may have the same configuration as the support line portion of the optical fiber cable described with reference to FIG. The cable main body 21 is arranged so that both sides of one to several optical fiber core wires 23 (shown by one and two examples in the figure) are sandwiched between tension members 24 in the center, Are collectively covered with the main body sheath 22 so as to be rectangular.

  As the optical fiber core 23, for example, a glass fiber having a standard outer diameter of 125 μm coated with a coating outer diameter of about 250 μm, or a fiber with a reinforcing coating on the outer side thereof is used. For the tension member 24, for example, a steel wire having an outer diameter of about 0.4 mm, glass fiber reinforced plastic (FRP), or aramid fiber reinforced (K-FRP) is used, and the material of the main body sheath 22 is particularly limited. However, it is preferable to have good moldability and appropriate hardness and flexibility. For example, flame retardant polyethylene (PE) and polyvinyl chloride (PVC) are used.

  The cable main body 21 has a slit notch 25 for facilitating removal of the inner optical fiber core 23 on both sides parallel to the straight line Y connecting the center of the optical fiber core 23 and the two tension members 24. Is provided. Note that the tear notch 25 is not a feature of the present invention, and is not necessarily required. The tear notch 25 may be omitted.

  The protection member 26a is a band-shaped member having a flat cross section, and is parallel to the straight line Y connecting the center of the optical fiber core wire 23 and the tension member 24, and covers the entire side surfaces of the body portion sheath 22. Arranged between. The protective member 26a is made of a material that cannot be bitten by squirrel or mouse teeth. For example, the protective member 26a is harder than the body sheath 22 or the sheath 27, and is made of metal, nylon, polycarbonate, polyphenylene sulfide (PPS). ), Polyester or the like. The thickness is preferably about 0.5 mm to 1.5 mm in consideration of anti-risk, murine and handling properties.

  The optical fiber cables 20a and 20b are formed by covering them with the sheaths 27 and 27 'in a state where the protective members 26a are disposed on both side surfaces of the cable body 21. The sheaths 27 and 27 ′ are preferably formed in a loose state in which the cable main body 21 and the protection member 26 a are not closely integrated with each other, and are formed into a rectangular shape similar to the cable main body 21. However, the shape is not necessarily rectangular, and may be, for example, circular or elliptical.

  You may make it provide the notch 28 similar to the tear notch 25 provided in the cable main-body part 21 in the both sides | surfaces (surface parallel to the straight line Y) of the sheaths 27 and 27 '. The notch 28 is for tearing the outer sheaths 27 and 27 'so that the cable main body 21 can be easily taken out. However, even if the notch 28 is not provided, the notch 28 can be taken out by using a tearing tool or the like. . Further, as shown in FIG. 1A, in the self-supporting type optical fiber cable 20 a having a support line portion, the neck portion 29 and the support wire sheath 31 are formed integrally with the outer sheath sheath 27. The optical fiber cable 20b in FIG. 1B may be used by removing the support line portion of the self-supporting optical fiber cable 20a, and was manufactured from the beginning without providing the support line portion. It may be a thing.

  In the embodiment of FIG. 1 described above, the protective member 26a having a flat cross section can protect the side surface that is easily squeezed by squirrels and mice. For example, even if the protective member 26a is exposed to the outside due to being squeezed by a squirrel or the like, the optical fiber core wire 23 covered by the cable body 21 is not directly exposed, and the reliability Can increase the sex. Further, since the protective member 26a is a simple flat plate and can be reduced in thickness, the flexibility as an optical fiber cable is not greatly impaired. Note that both end surfaces (surfaces orthogonal to the straight line Y) of the cable main body 21 are not protected by the protective member 26a. However, since the tension member 24 is embedded on the end surface side, a squirrel or a mouse is used. There is little worry about biting.

  FIG. 2 shows a second embodiment. Like the embodiment of FIG. 1, FIG. 2A shows an example of a self-supporting optical fiber cable 20a having a support line portion called a drop cable. FIG. 2B shows an example of an optical fiber cable 20b that does not have a support line portion, which is also called an indoor cable. The embodiment shown in FIG. 2 is different from the embodiment shown in FIG. 1 only in that the protective member 26a has a flat cross section, whereas the protective member 26b has a U-shaped cross section. Since the configuration can be made common, description of the common configuration is omitted here.

  The protection member 26b is formed in a band shape having a U-shaped cross section, and is sandwiched so as to be parallel to a straight line Y connecting the center of the optical fiber core wire 23 and the tension member 24 and to cover the entire side surfaces of the body sheath 22. It is arranged with. The material of the protective member 26b is formed of a material that cannot be bitten by squirrel or rat teeth. For example, the protective member 26b is harder than the body sheath 22 and the sheath 27, and is made of metal, nylon, polycarbonate, polyphenylene sulfide (PPS). ), Polyester or the like. The thickness is preferably about 0.5 mm to 1.5 mm in consideration of anti-risk, murine and handling properties.

  By sandwiching both side surfaces of the cable main body 21 with the U-shaped protection member 26b, the main body sheath 22 is completely surrounded by the protection member 26b. However, it is desirable that the cable main body 21 and the protection member 26b are not in a state of being joined so as to be in close contact with each other, but in a state of being movable in the longitudinal direction. Since the sheaths 27 and 27 'are formed so as to surround the outer periphery of the protection member 26b, the cable body 21 and the protection member 26b are slightly inferior in terms of flexibility as compared with the embodiment of FIG. Assembling state is easy and workability is improved. Further, since the tension member 24 is present on both end surfaces (surfaces orthogonal to the straight line Y) of the cable main body 21, there is little fear of being squeezed by a squirrel or a mouse, but this end surface is also surrounded by the protective member 26b. More complete protection can be done.

  Further, as a matter common to the embodiments of FIGS. 1 and 2, the cable body covered with the jacket sheath and the protective member can have the same structure as the body of the conventional optical fiber cable. For this reason, the tools and connection members currently used can be used as they are, and when using the cable body alone, for example, when retracting indoors, it is possible to work with the same handling as before. it can. When the optical fiber is taken out, the protective member and the cable main body can be easily taken out by cutting the outer sheath or cutting the outer sheath with a tear notch. Since the protective member simply sandwiches the cable body from both sides, it can be easily removed.

  Moreover, when the optical fiber cable is bent, the cable main body and the protective member can be reciprocally moved instead of being integrated. For this reason, the distortion added to an optical fiber can be relieved and the fall of the flexibility by a protection member can be made not to be impaired much.

It is a figure explaining the 1st Embodiment of this invention. It is a figure explaining the 2nd Embodiment of this invention. It is a figure explaining the prior art.

Explanation of symbols

20a, 20b ... optical fiber cable, 21 ... cable body, 22 ... body sheath, 23 ... optical fiber core, 24 ... tension member, 25 ... tear notch, 26a, 2b ... protective member, 27 ... jacket sheath 28 ... Notch, 29 ... Neck, 30 ... Support wire, 31 ... Support wire sheath.

Claims (4)

  A cable body part in which tension members are arranged in a straight line on both sides of the optical fiber core and collectively covered with a body part sheath, and a protective member arranged so as to sandwich both sides of the cable body part are covered with an outer sheath. An optical fiber cable characterized by that.   The optical fiber cable according to claim 1, wherein the protective member has a flat cross section.   The optical fiber cable according to claim 1, wherein the protection member has a U-shaped cross section.   The optical fiber cable according to any one of claims 1 to 3, wherein the protection member and the cable main body are movable with respect to each other.

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