JP2007147759A - Communication cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve workability in cable lead-out or intermediate post branching operation by facilitating separation and removal of a sheath without damaging the cable core of an optical fiber cable. <P>SOLUTION: The communication cable 1 is composed of at least two or more layers of cable sheaths 7, 7A, 7B, 9 layered on the outside of a cable core 3. The communication cable is characterized in that the cross section of the outermost layer 9 of the cable sheaths is formed nearly in a circle and that the thinnest part having an uneven thickness is formed in the cross section of each cable sheath. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication cable, and more particularly to an improvement in workability of cable lead-out and intermediate post-branching, and to a communication cable that can easily peel off and remove a cable sheath without damaging the cable core.

  For example, as an optical fiber cable 101 as a conventional communication cable excellent in branching property, as shown in FIG. 9, an optical fiber such as an optical fiber, an optical fiber, an optical fiber tape, or the like, A cable core 103 containing an optical fiber of another form such as a loose tube, and a cable sheath 105 (outer jacket) such as resin coated on the outer periphery of the cable core 103 is known. In FIG. 9, which shows a cross section of the optical fiber cable 101, a lip cord 107 (a tear string) provided on the left and right sides and in contact with the outer surface of the cable core 103, and the lip A structure in which a tension member 109 disposed inside the cable sheath 105 with a displacement of about 90 ° in the circumferential direction of the cable sheath 105 with respect to the cord 107 is mounted is common.

  In addition, as a self-supporting type (SS type) optical fiber cable 111 of another example, as shown in FIG. 10, a tensile strength body 113 (for example, a steel stranded wire obtained by twisting seven steel wires) as a suspension line. Is provided with a long cable support line part 117 whose sheath is covered with a sheath resin 115, and the cable support line part 117 is integrated in parallel with the optical fiber cable 101 via a neck part 119. Yes.

  In the post-intermediate branching operation for extracting the optical fiber in the cable core 103 from the middle of the optical fiber cable 101, it is necessary to peel off the cable sheath 105 without damaging the optical fiber in the cable core 103. When the cable sheath 105 is peeled off at the time of branching after the middle, the lip cord 107 mounted in the optical fiber cable 101 in advance is taken out, the lip cord 107 is pulled to tear the cable sheath 105, and the cable core 103 A method of taking out the optical fiber is employed.

  However, in the structure of the conventional optical fiber cable 101, in order to take out the lip cord 107 in advance, a method of carefully scraping the cable sheath 105 with a blade is taken. There was a risk of damage.

  As a countermeasure, a structure has been proposed in which the lip cord 107 is attached in the vicinity of the tension member 109 embedded in the cable sheath 105 to prevent the blade from reaching the inside of the cable core 103. There are problems that the adhesion between the tension member 109 and the cable sheath 105 is adversely affected, and the tension member 109 is damaged when the lip cord 107 is taken out.

  Therefore, in order to further improve the workability of the above-described lead-out and intermediate post-branching, as shown in Patent Document 1, in recent years, an optical fiber cable has an extruded structure in which the cable sheath is deformed in two layers. In addition, a part of the cable sheath (one of the two layers) is made of a material that can be easily removed. The optical fiber in the cable core can be taken out easily by tearing from one layer made of a material that is easy to remove.

  Moreover, as shown in Patent Document 2, in an optical-metal composite communication cable, a pair of conductor wires and an optical fiber arranged at the center between the pair of conductor wires are optical fiber composite metal cores. The pair of conductor wires and the central axis of the optical fiber are arranged linearly in a cross section in a direction perpendicular to the axial direction of the optical fiber composite metal pair core wire, all in parallel in the length direction of the wire. Furthermore, the pair of conductor wires and the optical fiber are integrated into a substantially spectacle-shaped cross section by a collective coating layer to form an optical fiber composite metal pair. Furthermore, the optical fiber composite metal pair core wire is extrusion coated with an exterior coating layer to make the entire cross-sectional shape circular, thereby facilitating twisting of a plurality of optical fiber composite metal pair core wires. Yes.

As a result, the outer covering layer (corresponding to the outer sheath) has a thin portion, so the outer covering layer can be easily torn from this thin portion, and the collective covering layer (corresponding to the inner sheath) has a substantially cross-sectional shape. Since it is a glasses-type, it is possible to easily split the conductor wire and the optical fiber by cutting from the recessed portion where the optical fiber is disposed.
US Pat. No. 5,970,196 JP-A-11-2111947

  By the way, among the conventional optical fiber cables described above, in the optical fiber cable of Patent Document 1, the layer of the material that can be easily removed is weak in strength. There has been a problem that the overall sheath strength of the sheet becomes weak.

  Further, in the optical fiber cable of Patent Document 2, when the collective covering layer corresponding to the inner sheath is torn, the thickness of the concave portion having a substantially spectacle-shaped cross section is thick, so the optical fiber is taken out by tearing the concave portion. It is not easy. For this reason, when a blade such as a cutter is inserted into the above-mentioned dent portion and it is torn, there is a possibility that the optical fiber may be scratched, and there is a problem in that it is troublesome to use a tool such as a cutter. there were.

  The present invention has been made to solve the above-described problems.

  In order to achieve the object to be solved by the above invention, a communication cable according to the present invention is a communication cable formed by laminating at least two layers of cable sheaths on the outside of a cable core. The outer layer cable sheath has a substantially circular cross section, and a thinnest portion is formed on the cross section of each cable sheath.

  The communication cable according to the present invention is preferably configured by extruding the communication cable in a substantially cylindrical state in which a cross section of the cable sheath of the inner layer is eccentric with respect to the center of the cable core. .

  Further, the communication cable of the present invention is configured by extruding the communication cable in a non-cylindrical state in which the transverse section of the inner layer cable sheath is concentric or eccentric with respect to the center of the cable core. Is preferred.

  Further, the communication cable according to the present invention is the communication cable, wherein the cable sheath has a cylindrical inner layer that is extruded in a state in which the cross section of the cable sheath is eccentric with respect to the center of the cable core, and a non-extruded shape that is extruded in a concentric state. It is preferable to have a cylindrical inner layer.

  Moreover, in the communication cable according to the present invention, it is preferable that a lip cord is embedded along the longitudinal direction of the cable core in the communication cable in the thinnest thinned portion or in the vicinity of the thinnest portion.

  As will be understood from the means for solving the above problems, according to the present invention, the outermost cable sheath of the cable sheath is formed in a substantially circular cross section, and each cable sheath has at least two layers. Since the thinnest part with uneven cross-section is formed, the thinnest part of each thin part has weak sheath strength, so even without using a tool such as a cutter, the outer layer sheath is directed toward the inner layer side of the inner layer sheath. In turn, the cable sheaths of the respective layers can be easily peeled one after another by tearing from the thinnest wall portions by hand.

  Moreover, since the thinnest part of the cable sheath of each layer can be arranged so as to be covered by the cable sheath of the other layer, the overall sheath strength of the communication cable can be increased.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1, for example, an optical fiber cable 1 as a communication cable according to the first embodiment includes an optical fiber such as an optical fiber, an optical fiber, an optical fiber tape, or a loose tube. A cable core 3 in which an optical fiber of another form is accommodated, and a cable sheath 5 (outer jacket) coated on the outer periphery of the cable core 3 are provided.

  In addition, as said cable core 3, the one-way slot and SZ slot which accommodated said optical fiber in the slot groove | channel can also be used as the cable core 3. FIG.

  The cable sheath 5 is composed of a first inner sheath 7 and a second outer sheath 9. The first inner sheath 7 and the second outer sheath 9 are located at the center O of the cable core 3. In contrast, the thinnest wall portions 11 and 13 that are unevenly formed are formed, and the outer cross-sectional outer shape of the outer sheath 9 is a circle that is substantially concentric with the center O of the cable core 3. Furthermore, the sheath thickness of the cable sheath 5, that is, the total sheath thickness of the inner layer sheath 7 and the outer layer sheath 9 is substantially constant, and the sectional outer shape of the inner layer sheath 7 is eccentric with respect to the center O of the cable core 3. It is a circle centered on an eccentric position O1 that is eccentric from the center O by a distance a.

  As a result, the first thinnest portion 11 (of the first layer sheath) is continuously formed in the inner layer sheath 7 in the same direction as the longitudinal direction of the cable core 3, and the outer layer sheath 9 has the inner layer sheath 7. The second thinnest wall portion 13 (of the second layer sheath) is continuously formed in the same direction as the longitudinal direction of the cable core 3 on the opposite side (opposite side) across the first thinnest wall portion 11 and the cable core 3. The Rukoto.

  Therefore, in the inner layer sheath 7, the first thinnest portion 11 is a portion having a weak sheath strength in the longitudinal direction, and in the outer layer sheath 9, the second thinnest portion 13 is a portion having a weak sheath strength in the longitudinal direction.

  Further, the first thinnest portion 11 of the inner layer sheath 7 and the second thinnest portion 13 of the outer layer sheath 9 are displaced in the circumferential direction of the cable sheath 5 as viewed from the cross section orthogonal to the longitudinal direction of the cable core 3. The overall sheath strength of the cable sheath 5 can be maintained at the same level as in the conventional case. In this embodiment, the first thinnest portion 11 and the second thinnest portion 13 are inevitably displaced by 180 ° in the circumferential direction of the cable sheath 5.

  In addition, L-LDPE is normally used for the inner layer sheath 7 and the outer layer sheath 9 described above, but the inner layer sheath 7 and the outer layer sheath 9 do not necessarily have to be the same resin. In addition to these, thermoplastic resins such as PVC, PBT, PP, PET, and Ny can also be used.

  Moreover, it is desirable that the inner layer sheath 7 and the outer layer sheath 9 have an adhesive force that can be easily peeled by hand. For example, the adhesion between the inner layer sheath 7 and the outer layer sheath 9 can be reduced by making the inner layer sheath 7 and the outer layer sheath 9 different materials as described above, but a release layer is interposed between the inner layer sheath 7 and the outer layer sheath 9. You can also

  Next, a method of intermediate post-branching of the optical fiber cable 1 according to the first embodiment will be described. As shown in FIG. 1, in the so-called intermediate rear branch portion that branches in the middle of the optical fiber cable 1, the second thinnest portion 13 of the outer sheath 9 is a portion having a weak sheath strength. The outer layer sheath 9 can be easily torn from the thinnest portion 13 and can be easily peeled off from the inner layer sheath 7.

  Next, since the first thinnest portion 11 of the inner layer sheath 7 is a portion having a weak sheath strength, the inner layer sheath 7 can be easily torn from the first thinnest portion 11 and easily peeled off from the cable core 3.

  Therefore, the cable sheath 5 can be easily torn by hand without being cut off by using a cutting tool, and there is no trouble and the optical fiber inside the cable core 3 is not damaged. The inner optical fiber can be easily taken out. Then, connection processing and repair processing are performed on optical fibers such as cable strands as appropriate.

  Next, for example, an optical fiber cable 15 as a communication cable according to a second embodiment of the present invention will be described. The same members as those of the optical fiber cable 1 of the first embodiment described above will be described with the same reference numerals, and only different portions will be mainly described.

  Referring to FIG. 2, this optical fiber cable 15 is basically the same as that of the first embodiment, and is different in that the inner layer sheath 7 is composed of two layers.

  That is, the cable sheath 5 includes a first inner layer sheath 7A, a second inner layer sheath 7B provided on the outer periphery of the inner layer sheath 7A, and a third outer layer sheath 9 provided on the outer periphery of the inner layer sheath 7B. And is composed of. The outer shape of the outer sheath 9 is a circular shape that is substantially concentric with the center O of the cable core 3. Furthermore, the sheath thickness of the cable sheath 5, that is, the total sheath thickness of the inner layer sheaths 7A and 7B and the outer layer sheath 9, is substantially constant, and the outer cross-sectional outer shapes of the inner layer sheaths 7A and 7B are A circular shape centered on eccentric positions O1 and O2 that are eccentric with respect to the center O and are eccentric from the center O by distances a and b, respectively. In this embodiment, the eccentric directions with respect to the center O of the cable core 3 having the outer cross-sectional outer shape of the inner sheaths 7A and 7B are shifted from each other.

  As a result, the innermost sheath 7A is formed with the first thinnest portion 11 (of the first layer sheath) continuously in the same direction as the longitudinal direction of the cable core 3, and the inner layer sheath 7B has the first innermost sheath 7A. The second thinnest wall portion 13 (of the second layer sheath) is continuously formed in the same direction as the longitudinal direction of the cable core 3 at a position shifted in the circumferential direction of the cable sheath 5 with respect to the thinnest wall portion 1. The outermost sheath 9 has a third thinnest part 17 (of the third layer sheath) in the longitudinal direction of the cable core 3 at a position shifted in the circumferential direction of the cable sheath 5 with respect to the second thinnest part 13 of the inner layer sheath 7B. It is formed continuously in the same direction as the direction.

  Therefore, in the inner layer sheath 7A, the first thinnest portion 11 is a portion having a weak sheath strength in the longitudinal direction, and in the inner layer sheath 7B, the second thinnest portion 13 is a portion having a weak sheath strength in the longitudinal direction. In the outer layer sheath 9, the third thinnest portion 17 is a portion having a weak sheath strength in the longitudinal direction.

  Note that the eccentric directions of the inner-layer sheaths 7A and 7B with respect to the center O of the cable core 3 having the outer cross-sectional outer shape are shifted from each other because the first thinnest portion 11 of the inner-layer sheath 7A and the second thinnest portion of the inner-layer sheath 7B. 13 and the third thinnest portion 17 of the outer sheath 9 are shifted in the circumferential direction of the cable sheath 5 as seen from the cross section orthogonal to the longitudinal direction of the cable core 3, and the overall sheath strength of the cable sheath 5 is the conventional one. This is desirable in that it can be maintained at the same level as the case.

  Since the inner layer sheaths 7A and 7B and the outer layer sheath 9 have an adhesive force that can be easily peeled by hand, the inner layer sheaths 7A and 7B and the outer layer sheath are similar to the first embodiment described above. 9 may be made of different materials, or a release layer may be interposed between the inner layer sheaths 7A and 7B and the outer layer sheath 9.

  Next, the method of intermediate post-branching of the optical fiber cable 15 of the second embodiment will be described. The method is basically the same as that of the optical fiber cable 1 of the first embodiment described above. That is, as shown in FIG. 2, in the so-called intermediate rear branch portion that branches in the middle of the optical fiber cable 15, the third thinnest portion 17 is a portion having a weak sheath strength in the outer sheath 9. The outer layer sheath 9 can be easily torn from the third thinnest portion 17 and easily peeled off from the inner layer sheath 7B.

  Next, in the inner layer sheath 7B, since the second thinnest portion 13 is a portion having a weak sheath strength, it can be easily torn from the second thinnest portion 13, and the inner layer sheath 7B can be easily peeled off from the inner layer sheath 7A. it can.

  Next, in the inner layer sheath 7A, the first thinnest portion 11 is a portion having a weak sheath strength. Therefore, the inner layer sheath 7A can be easily torn from the first thinnest portion 11 and easily peeled off from the cable core 3.

  Therefore, like the optical fiber cable 1 of the first embodiment described above, the cable sheath 5 can be easily torn without scraping off the cable sheath 5, and there is no labor, and the optical fiber inside the cable core 3 can be easily broken. The optical fiber in the cable core 3 can be easily taken out without damaging the cable. Then, connection processing and repair processing are performed on optical fibers such as cable strands as appropriate.

  Next, for example, an optical fiber cable 19 as a communication cable according to a third embodiment of the present invention will be described. The same members as those of the optical fiber cable 1 of the first embodiment described above will be described with the same reference numerals, and only different portions will be mainly described.

  Referring to FIG. 3, the optical fiber cable 19 is different from the first embodiment in the outer shape of the inner layer sheath 7.

  That is, the cable sheath 5 is composed of a first inner sheath 7 and a second outer sheath 9, and the outer cross-sectional shape of the outer sheath 9 is a circular shape that is substantially concentric with the center O of the cable core 3. is there. Further, the sheath thickness of the cable sheath 5, that is, the total sheath thickness of the inner layer sheath 7 and the outer layer sheath 9 is substantially constant, and the cross-sectional lateral outer shape of the inner layer sheath 7 is concentric with the center O of the cable core 3. Non-circular oval. That is, the center C of the intersection point of the elliptical major axis and minor axis is concentric with the center O of the cable core 3. The non-circular shape is not limited to the above ellipse, and may be other non-circular shapes such as an oval shape.

  As a result, two first thinnest portions 11 (of the first layer sheath) are continuously formed in the inner layer sheath 7 in the same direction as the longitudinal direction of the cable core 3, for example, in an elliptical short diameter portion. At the same time, the outer layer sheath 9 has two second thinnest portions 13 (of the second layer sheath) between the outer surface of the elliptical long diameter portion of the inner layer sheath 7 and the outer surface of the outer layer sheath 9. It is formed continuously in the same direction as the longitudinal direction.

  Therefore, in the inner layer sheath 7, the first thinnest portion 11 is a portion having a weak sheath strength in the longitudinal direction, and in the outer layer sheath 9, the second thinnest portion 13 is a portion having a weak sheath strength in the longitudinal direction.

  Further, the first thinnest portion 11 of the inner layer sheath 7 and the second thinnest portion 13 of the outer layer sheath 9 are displaced in the circumferential direction of the cable sheath 5 as viewed from the cross section orthogonal to the longitudinal direction of the cable core 3. The overall sheath strength of the cable sheath 5 can be maintained at the same level as in the conventional case. In this embodiment, the first thinnest portion 11 and the second thinnest portion 13 are necessarily shifted by 90 ° in the circumferential direction of the cable sheath 5.

  In addition, since the inner layer sheath 7 and the outer layer sheath 9 have an adhesive force that can be easily peeled off by hand, the material of the inner layer sheath 7 and the outer layer sheath 9 is the same as in the first embodiment described above. They can be different, or a release layer can be interposed between the inner layer sheath 7 and the outer layer sheath 9.

  Next, a method of intermediate post-branching of the optical fiber cable 19 according to the third embodiment will be described. The method is basically the same as that of the optical fiber cable 1 according to the first embodiment described above. That is, as shown in FIG. 3, in the so-called intermediate rear branch portion that branches in the middle of the optical fiber cable 19, in the outer sheath 9, the second thinnest portion 13 is a portion having a weak sheath strength. The outer layer sheath 9 can be easily torn from the second thinnest wall portion 13 and can be easily peeled off from the inner layer sheath 7.

  Next, since the first thinnest portion 11 of the inner layer sheath 7 is a portion having a weak sheath strength, the inner layer sheath 7 can be easily torn from the first thinnest portion 11 and easily peeled off from the cable core 3. Other functions and effects are the same as those of the first embodiment.

  Next, for example, an optical fiber cable 21 as a communication cable according to a fourth embodiment of the present invention will be described. The same members as those of the optical fiber cable 1 of the first embodiment described above will be described with the same reference numerals, and only different portions will be mainly described.

  Referring to FIG. 4, the optical fiber cable 21 is different in that the inner layer sheath 7 is non-circular as in the third embodiment, but is eccentric with respect to the center O of the cable core 3.

  That is, the cable sheath 5 is composed of a first inner sheath 7 and a second outer sheath 9, and the outer cross-sectional outer shape of the outer sheath 9 is a circular shape that is substantially concentric with the center O of the cable core 3. is there. Further, the sheath thickness of the cable sheath 5, that is, the total sheath thickness of the inner layer sheath 7 and the outer layer sheath 9 is substantially constant, and the outer cross-sectional outer shape of the inner layer sheath 7 is in relation to the center O of the cable core 3. It is an eccentric non-circular ellipse. That is, the center C of the intersection of the elliptical major axis and minor axis is at a position different from the center O of the cable core 3. The non-circular shape is not limited to the above ellipse, and may be other non-circular shapes such as an oval shape.

  As a result, in the inner layer sheath 7, for example, one first thinnest portion 11 (of the first layer sheath) is continuously formed in the same direction as the longitudinal direction of the cable core 3 in an elliptical short diameter portion. At the same time, the outer layer sheath 9 has two second thinnest portions 13 (of the second layer sheath) between the outer surface of the elliptical long diameter portion of the inner layer sheath 7 and the outer surface of the outer layer sheath 9. It is formed continuously in the same direction as the longitudinal direction.

  Therefore, in the inner layer sheath 7, the first thinnest portion 11 is a portion having a weak sheath strength in the longitudinal direction, and in the outer layer sheath 9, the second thinnest portion 13 is a portion having a weak sheath strength in the longitudinal direction.

  Further, the first thinnest portion 11 of the inner layer sheath 7 and the second thinnest portion 13 of the outer layer sheath 9 are displaced in the circumferential direction of the cable sheath 5 as viewed from the cross section orthogonal to the longitudinal direction of the cable core 3. The overall sheath strength of the cable sheath 5 can be maintained at the same level as in the conventional case. In this embodiment, the first thinnest portion 11 and the second thinnest portion 13 are necessarily shifted by 90 ° in the circumferential direction of the cable sheath 5.

  In addition, since the inner layer sheath 7 and the outer layer sheath 9 have an adhesive force that can be easily peeled off by hand, the material of the inner layer sheath 7 and the outer layer sheath 9 is the same as in the first embodiment described above. They can be different, or a release layer can be interposed between the inner layer sheath 7 and the outer layer sheath 9.

  Next, a method of intermediate post-branching of, for example, the optical fiber cable 21 as the communication cable of the fourth embodiment will be described. Basically, the optical fiber cable 1 of the first embodiment described above and It is the same. That is, as shown in FIG. 4, in the so-called intermediate rear branch portion that branches in the middle of the optical fiber cable 21, the outermost sheath 9 has the second thinnest portion 13 having a weak sheath strength. The outer layer sheath 9 can be easily torn from the second thinnest wall portion 13 and can be easily peeled off from the inner layer sheath 7.

  Next, since the first thinnest portion 11 of the inner layer sheath 7 is a portion having a weak sheath strength, the inner layer sheath 7 can be easily torn from the first thinnest portion 11 and easily peeled off from the cable core 3. Other functions and effects are the same as those of the first embodiment.

  Next, for example, an optical fiber cable 23 as a communication cable according to a fifth embodiment of the invention will be described. The same members as those of the optical fiber cable 1 of the first embodiment described above will be described with the same reference numerals, and only different portions will be mainly described.

  Referring to FIG. 5, this optical fiber cable 23 is basically a combination of the first embodiment and the third embodiment.

  That is, the cable sheath 5 includes a first inner sheath 7A, a second inner sheath 7B provided on the outer periphery of the inner sheath 7A, a third outer sheath 9 provided on the inner sheath 7B, The outer shape of the outer sheath 9 is a circular shape that is substantially concentric with the center O of the cable core 3. Further, the sheath thickness of the cable sheath 5, that is, the total sheath thickness of the inner layer sheaths 7 A and 7 B and the outer layer sheath 9 is substantially constant, and the outer cross-sectional outer shape of the inner layer sheath 7 A is at the center O of the cable core 3. The inner layer sheath 7B is a non-circular ellipse that is concentric with the center O of the cable core 3 and has a circular shape centered on a position O1 that is eccentric with respect to the center O by a distance a. That is, the center C of the intersection point of the elliptical major axis and minor axis is concentric with the center O of the cable core 3. The non-circular shape is not limited to the above ellipse, and may be other non-circular shapes such as an oval shape.

  As a result, the inner layer sheath 7A is formed with one first thinnest portion 11 (of the first layer sheath) continuously in the same direction as the longitudinal direction of the cable core 3, and the inner layer sheath 7B has an elliptical shape, for example. The second thinnest portion 13 (of the second layer sheath) at two locations in the vicinity of the short diameter portion of the inner sheath 7A is displaced from the first thinnest portion 11 in the circumferential direction of the cable sheath 5 in the circumferential direction. It is formed continuously in the same direction as the longitudinal direction of the cable core 3, and the outer sheath 9 has two third outermost sheaths between the outer surface of the elliptical long diameter portion of the inner sheath 7 B and the outer surface of the outer sheath 9. The thin portion 17 (of the third layer sheath) is continuously formed in the same direction as the longitudinal direction of the cable core 3.

  Therefore, in the inner layer sheath 7A, the first thinnest portion 11 is a portion having a weak sheath strength in the longitudinal direction, and in the inner layer sheath 7B, the second thinnest portion 13 is a portion having a weak sheath strength in the longitudinal direction. In the outer layer sheath 9, the third thinnest portion 17 is a portion having a weak sheath strength in the longitudinal direction.

  The first thin portion 11 of the inner layer sheath 7A, the second thinnest portion 13 of the inner layer sheath 7B, and the third thinnest portion 17 of the outer layer sheath 9 are cable sheaths as viewed from a cross section perpendicular to the longitudinal direction of the cable core 3. 5, the overall sheath strength of the cable sheath 5 can be maintained at the same level as in the conventional case.

  Further, since the inner layer sheaths 7A and 7B and the outer layer sheath 9 have an adhesive force that can be easily peeled off by hand, the inner layer sheaths 7A and 7B and the outer layer sheath are similar to the first embodiment described above. 9 may be made of different materials, or a release layer may be interposed between the inner layer sheaths 7A and 7B and the outer layer sheath 9.

  Next, a method of intermediate post-branching of the optical fiber cable 23 according to the fifth embodiment will be described. The method is basically the same as that of the optical fiber cable 1 according to the first embodiment described above. That is, as shown in FIG. 5, in the so-called intermediate rear branch portion that branches in the middle of the optical fiber cable 23, the third thinnest portion 17 in the outer sheath 9 is a portion having a weak sheath strength. The outer layer sheath 9 can be easily torn from the third thinnest portion 17 and easily peeled off from the inner layer sheath 7B.

  Next, in the inner layer sheath 7B, since the second thin portion 13 is a portion having a weak sheath strength, it can be easily torn from the second thinnest portion 13, and the inner layer sheath 7B can be easily peeled off from the inner layer sheath 7A. .

  Next, in the inner layer sheath 7A, the first thinnest portion 11 is a portion having a weak sheath strength. Therefore, the inner layer sheath 7A can be easily torn from the first thinnest portion 11 and easily peeled off from the cable core 3. Other functions and effects are the same as those of the first embodiment.

  When the inner layer sheath 7 has two or more layers, (1) one of the inner layer sheaths 7 is a circular shape eccentric with respect to the center O of the cable core 3, and (2) any one of the inner layer sheaths 7 is a cable. Any combination of non-circular concentricity with the center O of the core 3 and (3) any inner-layer sheath 7 being non-circular eccentric with respect to the center O of the cable core 3 Also good. For example, the example of FIG. 5 described above is a combination of the examples of FIG. 1 and FIG. 3, but other examples are combinations of the examples of FIG. 1 and FIG. 4, or FIG. 1, FIG. A combination of these examples is also possible.

  Next, for example, an optical fiber cable 25 as a communication cable according to a sixth embodiment of the invention will be described. The same members as those of the optical fiber cable 1 of the first embodiment described above will be described with the same reference numerals, and only different portions will be mainly described.

  Referring to FIG. 6, this optical fiber cable 25 is basically the same as the first thinnest portion 11 and 2 of the inner layer sheath 7 of the first layer of the cable sheath 5 in the optical fiber cable 1 of the first embodiment. In the second thinnest portion 13 of the outer sheath 9 of the layer, a single lip cord (tear string) 27 and 29 extending substantially parallel to the longitudinal direction of the cable sheath 5 is embedded. That is, the first lip cord 27 is embedded in the first thinnest portion 11 of the inner layer sheath 7, and the second lip cord 29 is embedded in the second thinnest portion 13 of the outer layer sheath 9.

  Accordingly, since the first and second lip cords 27 and 29 are always located in the shallow portion (thinnest wall portion) of each layer sheath, the first and second lip cords 27 and 29 can be easily taken out. Each layer sheath can be torn more easily by pulling. Other functions and effects are the same as those of the first embodiment, and thus detailed description thereof is omitted.

  7A to 7D, the optical fiber cable 1 of the first embodiment is also applied to the optical fiber cables 15, 19, 21, and 23 of the second to fifth embodiments. In the same manner as above, the shallow portion of each layer sheath, that is, each of the first, second, and third thinnest portions 11, 13, and 17, respectively, corresponds to one strip extending substantially parallel to the longitudinal direction of the cable sheath 5. The first, second, and third lip cords 27, 29, and 31 can be embedded. That is, the optical fiber cable 33 in FIG. 7A corresponds to the optical fiber cable 15 in the second embodiment, and the optical fiber cable 35 in FIG. 7B is an optical fiber in the third embodiment. 7C corresponds to the optical fiber cable 21 of the fourth embodiment, and the optical fiber cable 39 of FIG. 7D corresponds to the fifth embodiment. It corresponds to the optical fiber cable 23 of the form. Since each operation effect is the same as that of the case of the optical fiber cable 25 of 6th Embodiment, detailed description is abbreviate | omitted.

  Next, as a self-supporting type (SS type) optical fiber cable 41 according to the seventh embodiment of the present invention, as shown in FIG. 8, a tensile body 43 (for example, seven steel wires) as a hanging line is used. A long cable support wire portion 47 in which the periphery of a twisted steel stranded wire is covered with a sheath resin 45 is provided, and this cable support wire portion 47 is connected to the neck 49 through the first embodiment. The optical fiber cables 1 are integrated in parallel with each other.

  The operation and effect of the self-supporting (SS type) optical fiber cable 41 of the seventh embodiment are the same as those of the optical fiber cable 1 of the first embodiment described above, and detailed description thereof is omitted. To do.

  Further, for the optical fiber cables 15, 19, 21, 23, 25 of the second to sixth embodiments described above, the optical fiber cables 33 of the forms shown in FIGS. Similarly to the optical fiber cable 33 of the seventh embodiment, 35, 37, 39 are also provided with a long cable support line portion 47, and the cable support line portion 47 is respectively connected via the neck portion 49. The optical fiber cables 15, 19, 21, 23, and 25 and the optical fiber cables 33, 35, 37, and 39 in the form of FIGS. Type) optical fiber cable.

  The positions of the neck portion 49 and the thin portion of the outer layer sheath need to be shifted from each other.

  The operation and effect of each of the above-mentioned self-supporting type (SS type) optical fiber cables is the same as that of the corresponding optical fiber cables 15, 19, 21, 23, 25 and FIGS. 7 (A) to (D). Since it is the same as that of the optical fiber cables 33, 35, 37, 39, detailed description is omitted.

  It should be noted that the present invention is not limited to the above-described embodiment, and even if the positions of the thinnest portions 11 and 13 of the first inner layer sheath 7A and the second inner layer sheath 7B are not shifted in FIG. Is possible. Moreover, although the example of this Embodiment demonstrated by the example of 1 layer and 2 layers like the inner layer cases 7, 7A, 7B, it can respond also to 3 layers or more. Moreover, although the above-mentioned communication cable has been described by taking an optical fiber cable as an example, it can also be applied to, for example, a communication cable in which a coaxial cable or the like is accommodated in the cable core 3 and other cables.

It is sectional drawing orthogonal to the longitudinal direction of the optical fiber cable as a communication cable of 1st Embodiment of this invention, for example. It is sectional drawing orthogonal to the longitudinal direction of the optical fiber cable as a communication cable of 2nd Embodiment of this invention, for example. It is sectional drawing orthogonal to the longitudinal direction of the optical fiber cable as a communication cable of 3rd Embodiment of this invention, for example. It is sectional drawing orthogonal to the longitudinal direction of the optical fiber cable as a communication cable of 4th Embodiment of this invention, for example. It is sectional drawing orthogonal to the longitudinal direction of the optical fiber cable as a communication cable of 5th Embodiment of this invention, for example. It is sectional drawing orthogonal to the longitudinal direction of the optical fiber cable as a communication cable of 6th Embodiment of this invention, for example. (A) to (D) respectively correspond to, for example, optical fiber cables as communication cables of the second to fifth embodiments, and each layer is similar to the optical fiber cable of the sixth embodiment. It is sectional drawing of the optical fiber cable which provided the lip cord in the thin part of the sheath. It is sectional drawing orthogonal to the longitudinal direction of the self-supporting type optical fiber cable as a communication cable of 7th Embodiment of this invention, for example. It is sectional drawing of the optical fiber cable as a conventional communication cable, for example. It is sectional drawing of the self-supporting type | mold optical fiber cable as another conventional communication cable, for example.

Explanation of symbols

1 Optical fiber cable (communication cable)
DESCRIPTION OF SYMBOLS 3 Cable core 5 Cable sheath 7, 7A, 7B Inner layer sheath 9 Outer layer sheath 11 1st thinnest part 13 2nd thinnest part 15 Optical fiber cable (communication cable)
17 Third thinnest part 19 Optical fiber cable (communication cable)
21 Optical fiber cable (communication cable)
23 Optical fiber cable (communication cable)
25 Optical fiber cable (communication cable)
27 First lip cord 29 Second lip cord 31 Third lip cord 33 Optical fiber cable (communication cable)
35 Optical fiber cable (communication cable)
37 Optical fiber cable (communication cable)
39 Optical fiber cable (communication cable)
41 Optical fiber cable (communication cable)
O Center of cable core C Center of non-circular outer shape

Claims (5)

  A communication cable in which at least two layers of cable sheaths are laminated on the outside of a cable core, wherein the outermost cable sheath of the cable sheath has a substantially circular cross section, and the cross section of each cable sheath is biased. A communication cable characterized in that the thinnest part is formed.   The communication cable according to claim 1, wherein the inner layer cable sheath is formed by extrusion molding in a substantially cylindrical state eccentric with respect to the center of the cable core.   2. The communication cable according to claim 1, wherein the inner layer cable sheath is extruded and formed in a non-cylindrical state concentrically or eccentrically with respect to the center of the cable core.   2. A cylindrical inner layer extruded with a cross section of the cable sheath being eccentric with respect to the center of the cable core, and a non-cylindrical inner layer extruded in a concentric state. The communication cable described. The communication cable according to claim 1, 2, 3, or 4, wherein a lip cord is embedded along the longitudinal direction of the cable core in the thinned thinned portion or in the vicinity of the thinned portion.

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