JP4376257B2 - Fiber optic cable - Google Patents

Description

  The present invention relates to an optical fiber cable, and more particularly to a one-groove slot core type optical fiber cable in which the periphery of a slot core having a single slot groove for accommodating the optical fiber inside the slot core is covered with a sheath. The present invention relates to an optical fiber cable that can easily lead out an optical fiber without damaging the optical fiber in the slot groove at the time of intermediate post branching.

  As a conventional optical fiber cable, as shown in Patent Document 1, the periphery of a slot core having one slot groove for accommodating an optical fiber is covered with a sheath, and the inside of the sheath is a lip cord. 1-slot slot core type optical fiber cable with (tear string) vertically attached, the sheath thickness on the opening side of the slot groove being relative to the sheath thickness on the opposite side to the opening side of the slot groove In this structure, the lip cord is disposed inside the sheath on the opening side of the slot groove.

  The optical fiber cable of Patent Document 2 is a loose tube type optical fiber cable with a slit in which an optical fiber is housed in a tube having a slit that communicates the inside and outside continuous in the axial direction. This is an eccentric sheath structure in which the sheath thickness is relatively thinner than the sheath thickness on the side opposite to the slit side, and a lip cord (tear string) is disposed inside the sheath on the slit side.

  The optical fiber cable of Patent Document 3 is a one-groove slot core type optical fiber cable in which a periphery of a slot core having one slot groove for accommodating an optical fiber is covered with a sheath, Since the tensile strength members of the cable are arranged in parallel in the direction perpendicular to the depth direction of the slot groove, the cable bending neutral line is perpendicular to the depth direction of the slot groove, and the optical fiber is It is the structure arrange | positioned in the cable center inside a cable bend neutral line.

  The optical fiber cable of Patent Document 4 is a method for manufacturing a waterproof single groove slot core optical fiber cable, and the extra length necessary for the optical fiber accommodated in the slot groove of the slot core when manufacturing the optical fiber cable. Is to secure.

  The optical fiber cable of Patent Document 5 is a one-groove slot core type optical fiber cable in which the periphery of a slot core provided with one slot groove for accommodating an optical fiber is covered with a sheath. Since the tensile strength members are arranged on both sides of the slot groove in a direction perpendicular to the depth direction of the slot groove, the cable bending neutral line is a direction perpendicular to the depth direction of the slot groove. The optical fiber is located at the center of the cable inside the slot groove and is arranged in the cable bending neutral line.

  The optical fiber cable of Patent Document 6 has an optical fiber cable structure in which a single groove slot core is used as a unit, and a plurality of such units are assembled.

The optical fiber cable of Patent Document 7 is a one-groove slot core type optical fiber cable that alleviates distortion of the optical fiber ribbon, and the two strength members are orthogonal to the depth direction of the slot groove. The cable bend neutral line is perpendicular to the depth direction of the slot groove and the optical fiber is arranged near the cable center of the slot groove. is there.
JP 62-291608 A JP 63-5313 A Japanese Patent Publication No.7-111493 JP-A-1-13106 Japanese Utility Model Publication No. 6-50009 JP-A-8-160265 Japanese Patent Laid-Open No. 8-21261

  By the way, in the conventional optical fiber cable of Patent Document 1, since the sheath thickness on the opening side of the slot groove is thin, the mechanical strength of the sheath at this portion is deteriorated. Conversely, in order to ensure the mechanical strength of the sheath, it is necessary to increase the thickness of the sheath on the opening side of the slot groove to some extent. There was a problem that it was difficult to tear the sheath on the side.

  Furthermore, when the thickness of the sheath is uneven while ensuring the mechanical strength of the sheath on the opening side of the slot groove as a minimum, the outer diameter of the optical fiber cable has to be increased.

  Further, when taking out the lip cord, it is necessary to cut the sheath with the cutting edge of a cutting tool such as a knife. However, since the lip cord is mounted on the opening side of the slot groove, There is a problem that there is a risk of damaging the optical fiber. In particular, damaging the optical fiber at the time of intermediate post branching becomes a fatal obstacle.

  In the optical fiber cable of Patent Document 2, since the sheath thickness on the slit side is thin, there is almost the same problem as the optical fiber cable of Patent Document 1 described above.

  In the optical fiber cables of Patent Literature 3, Patent Literature 5 and Patent Literature 7, the cable bending neutral line is a direction orthogonal to the depth direction of the slot groove, and the optical fiber is located at the cable center of the slot groove, Since the structure is arranged in the cable bending neutral line, the slot groove needs to be deeper than the center of the cable, so that the strength of the slot core is lowered. In addition, since the optical fiber has a degree of freedom in the depth direction of the slot groove, it is not always easy to place the optical fiber at the center of the cable in the depth direction of the slot groove, and the optical fiber may be out of the cable bending neutral line. There is. In this case, there has been a problem that the optical fiber is stretched and strained, or conversely, the optical fiber meanders inside the slot groove.

  In the optical fiber cable of Patent Document 4, in order to ensure the extra length of the optical fiber, the clearance must be increased in order to ensure the freedom in the slot groove, and the cable outer diameter must be designed to be large. There was a problem not getting.

  In the optical fiber cable of Patent Document 6, in each slot slot core constituting each unit, a tension member (strength member) is disposed in the bottom opposite to the opening of the slot groove. The slot groove opening is always configured to face outward, and is basically configured differently from the one-groove slot core type optical fiber cable.

The present invention has been made in view of the conventional problems as described above, and the slot groove (5) for accommodating the optical fiber (3) therein at an eccentric position in the sheath (9) of the optical fiber cable. The thickness of the sheath (9) on the side of the opening (11) of the slot groove (5) in the slot core (7) is opposite to that of the opening (11). provided thicker than the thickness of the side of the sheath (9), the direction connecting the center of the opening of the street the slot grooves cable center and Y-axis in a cross section perpendicular against the longitudinal direction of the optical fiber cable, said cable When the direction perpendicular to the Y-axis passing through the center is the X-axis, the linear body is separated by two points on the Y-axis and / or on the Y-axis to make the Y-axis a cable bending neutral line. 2 points between the Y axis To face the vicinity of the Y-axis is arranged and equipped by arranging such that the position of the optical fiber to be received in the slot grooves are substantially coincident with the Y-axis, wherein the opening of the slot groove (5) The mechanical strength of the thin portion of the sheath (9) on the opposite side of the portion (11) is compensated at the bottom of the slot core (7) on the opposite side of the opening (11). It is characterized by .

  In the optical fiber cable according to the present invention, it is preferable that in the optical fiber cable, the linear body is disposed on the Y axis and embedded in both the slot core and the sheath.

In the optical fiber cable, the linear body is disposed at two points apart on the Y axis and is embedded only in the slot core.

In addition, a slot core (7) having a slot groove (5) for accommodating the optical fiber (3) therein is provided at an eccentric position in the sheath (9) of the optical fiber cable. ), The thickness of the sheath (9) on the opening (11) side of the slot groove (5) is larger than the thickness of the sheath (9) on the opposite side of the opening (11), and the light When the cross section perpendicular to the longitudinal direction of the fiber cable passes through the center of the cable and connects the center of the opening of the slot groove as the Y axis, the direction passing through the center of the cable and perpendicular to the Y axis is the X axis. In order to make the Y-axis a cable bending neutral line, a linear body is arranged on the Y-axis and in the vicinity of the Y-axis across the Y-axis, and the linear body on the Y-axis and the Y-axis A linear body arranged opposite to the vicinity of the Y axis across the The provided at a position apart in the Y-axis direction, and comprises by arranging such that the position of the optical fiber to be received in the slot grooves are substantially coincident with the Y-axis, wherein the opening of the slot groove (5) The mechanical strength of the thin portion of the sheath (9) on the opposite side of (11) is compensated at the bottom of the slot core (7) on the opposite side of the opening (11). It is a feature.

  In the optical fiber cable of the present invention, in the optical fiber cable, the linear body is preferably made of a steel wire or FRP.

Further, in the optical fiber cable, a lip cord is vertically attached to the inside of the sheath, and the lip cord is disposed inside the sheath at a position near the X axis and on the outer periphery of the slot core. It is characterized by a structure.

  As understood from the means for solving the above problems, according to the present invention, the sheath thickness on the opening side of the slot groove is relatively thicker than the sheath thickness on the opposite side to the opening side of the slot groove. Therefore, even if an external force is applied, the optical fiber inside the slot groove can be prevented from being damaged, and the mechanical strength of the portion where the sheath thickness is thin on the side opposite to the opening side of the slot groove is compensated at the bottom of the slot core. it can.

  In addition, the sheath is cut with the cutting edge of a cutting tool such as a knife at a position away from the slot groove opening of the one-groove slot core containing the optical fiber, and the sheath stripping operation is started. It is possible to perform the optical fiber lead-out operation without damaging the optical fiber with a cutting edge of a tool or the like during the connection operation.

  Further, the linear body is disposed on the Y axis and / or in the vicinity thereof so that the cable bending direction is restricted only in the X axis direction forming an angle of 90 ° with respect to the Y axis in the depth direction of the slot groove, In addition, since the position of the optical fiber accommodated in the slot groove is arranged so as to substantially coincide with the Y-axis, the optical fiber does not expand or contract even when the optical fiber cable is bent in the X-axis direction. As a result, a thin cable design with good transmission characteristics can be achieved.

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

  Referring to FIG. 1A, an optical fiber cable 1 according to the first embodiment is a one-groove slot type optical fiber cable. Basically, the optical fiber cable 1 is for storing the optical fiber 3 therein. A slot core 7 having one slot groove 5 and a sheath 9 covering the periphery of the slot core 7 are provided. The sheath 9 is made of a resin such as polyethylene resin, and the opening of the slot groove 5 is provided. 11 has an eccentric sheath structure in which the sheath thickness on the 11 side is relatively thicker than the sheath thickness on the opposite side to the opening 11 side of the slot groove 5.

  In the one-groove slot type optical fiber cable 1 having the above-described configuration, the direction connecting the center of the opening 11 of the slot groove 5 through the cable center C in the cross section perpendicular to the longitudinal direction of the optical fiber cable 1 is defined as the Y axis. When the direction passing through the cable center C and perpendicular to the Y-axis is the X-axis, for example, the tension members 13 and 15 as two line states are arranged on the Y-axis so that the Y-axis becomes a cable bending neutral line. In FIG. 1, they are arranged vertically. That is, by arranging the two or more strength members 13 and 15 on the Y axis, the Y axis inevitably becomes a cable bending neutral line.

  In the first embodiment, one strength member 13 is disposed on the Y axis of the sheath 9, and another strength member 15 is disposed on the Y axis of the slot core 7. In this case, because of the relationship between the two strength members 13 and 15, as shown in FIG. 2, the Y-axis connecting the two strength members 13 and 15 is set to the cable bending neutral line on the X-axis. This is a bending in the X-axis direction with a radius of curvature R from the bending center O (lateral bending in FIGS. 1A and 2). Incidentally, as shown in FIG. 3, for example, the X-axis passing through the cable center C is a cable bending neutral line, and is bent from the bending center O on the Y-axis in the Y-axis direction with a radius of curvature R (FIG. 1 (A ) And FIG. 3), the vertical bending in the state of FIG. 3 hardly occurs due to the relationship between the two strength members 13 and 15. In addition, as a tensile body, a steel wire, FRP, etc. can be used.

  Furthermore, in this embodiment, the slot groove 5 of the slot core 7 has a circular cross section, but the cross sectional shape of the slot groove 5 is not limited to a circular cross section. One or a plurality of optical fibers 3 are accommodated in the slot groove 5. In FIG. 1A, a total of 10 optical fiber ribbons are accommodated as the optical fibers 3. When the optical fiber 3 is accommodated in the slot groove 5, the periphery of the optical fiber 3 may be a gap or a buffer material may be interposed. In any of these cases, the position of the optical fiber 3 housed in the slot groove 5 is characterized by being disposed so as to substantially coincide with the Y axis.

  As the optical fiber 3, an optical fiber strand, an optical fiber core wire, an optical fiber tape core wire, or the like is used.

  Furthermore, in the first embodiment, two lip cords 17 (Rip Cords) are vertically attached to the inside of the sheath 9, and the two lip cords 17 are in the vicinity including the X axis. In this position, the inside of the sheath 9 and the outer periphery of the slot core 7 are symmetrically disposed on both sides around the Y axis. The lip cord 17 is used to tear the sheath 9 at the time of opening for taking out the optical fiber 3 from the slot core 7. The number of lip cords 17 may be only one, and the number is not limited.

  The operation and effect of the optical fiber cable 1 of the first embodiment will be described with the above configuration. The sheath thickness on the opening 11 side of the slot groove 5 is opposite to the opening 11 side of the slot groove 5. Since it is relatively thicker than the sheath thickness, the mechanical strength of this portion is compensated, so that damage to the optical fiber 3 inside the slot groove 5 can be prevented even if an external force is applied. Moreover, the mechanical strength of the portion of the slot groove 5 opposite to the opening 11 side where the sheath thickness is thin is compensated at the bottom of the slot core 7 opposite to the opening 11 side of the slot groove 5. Become.

  Further, when the optical fiber 3 is led out from the optical fiber cable 1 in an intermediate rear branch or the like, as shown in FIG. 4A, in the first embodiment, first, the optical fiber 3 is used. The slot 11 of the slot core 7 in the slot core 7 is cut at an angle of about 90 degrees away from the opening 11 of the slot groove 5 by applying the cutting edge of a cutting tool 19 such as a knife to the sheath 9 and then cutting the sheath. The lip cord 17 is taken out from the inside of 9. At this time, since the lip cord 17 is located in the sheath 9 in the vicinity of the X axis and the sheath thickness of this portion is relatively thin, the lip cord 17 can be easily taken out, and the slot core 7 is provided in this portion. Since the wall exists, the optical fiber 3 can be prevented from being damaged.

  Further, when the two lip cords 17 are taken out as described above and then pulled, the sheath 9 can be easily torn because the sheath thickness is relatively thin, and the two lip cords 17 can be used as the sheath. In order to divide 9 into two, the slot core 7 can be easily taken out. Therefore, the desired optical fiber 3 can be easily taken out from the opening 11 of the slot groove 5 of the slot core 7.

  Further, the optical fiber cable 1 of the first embodiment has two cables so that the cable bending direction is restricted only in the direction that forms an angle of 90 ° with respect to the Y axis in the depth direction of the slot groove 5. Since the tensile strength members 13 and 15 are mounted on the Y axis inside the slot core 7 and the sheath 9, as shown in FIG. Since the bending is in the X-axis direction with a radius of curvature R from the center O (lateral bending in FIGS. 1A and 2), the mounting position of the optical fiber 3 is made to substantially coincide with the position of the cable bending neutral line (Y-axis). be able to.

  In general, in the cross-sectional direction of the optical fiber cable 1, the optical fiber 3 on the side with the larger bend R (outside of the bend) extends, and conversely, the optical fiber 3 on the side with the smaller bend R (outside of the bend) shrinks. In this first embodiment, even if the optical fiber cable 1 is bent in the X-axis direction, the optical fiber 3 becomes a cable bending neutral line in the first embodiment. Since it almost coincides with the axis, the optical fiber 3 is not expanded or contracted. As a result, it is possible to apply an elongation strain to the optical fiber 3 and to prevent meandering due to the remainder of the optical fiber 3, so that the optical fiber is placed inside the slot groove 5 in order to reduce the elongation strain of the optical fiber 3. Therefore, it is not necessary to secure a surplus length of 3 or to design a large clearance in order to prevent an increase in loss due to meandering of the optical fiber 3, so that it is possible to achieve a small-diameter cable design with good transmission characteristics. it can.

  As a modification of FIG. 1A, an optical fiber cable 1 as shown in FIG. 1B, the same members as those in FIG. 1A are denoted by the same reference numerals, overlapping description is omitted, and different points will be described. In FIG. 1A, the lip cord 17 has a structure in which the lip cord 17 is symmetrically disposed on the inner side of the sheath 9 at a position including the X axis and on the outer periphery of the slot core 7 on both sides around the Y axis. In FIG. 1B, the lip cord 17 may be disposed at a position below the sheath 9 on the Y axis. In this case, as shown in FIG. 4B, when the optical fiber 3 is led out from the optical fiber cable 1 by an intermediate rear branch or the like, the slot groove of the slot core 7 accommodating the optical fiber 3 is used. The lip cord 17 is taken out after the cutting edge of a cutting tool 19 such as a knife is applied to the sheath 9 at a position substantially below the Y-axis at an angle of 180 degrees away from the opening 11. At this time, the lip cord 17 is positioned inside the sheath 9 on the Y axis, and the sheath thickness of this portion is relatively thin. Therefore, the lip cord 17 can be easily taken out, and the wall of the slot core 7 is unclear. Therefore, it is possible to prevent the optical fiber 3 from being damaged. Other configurations and effects are the same as those in FIG.

  Next, an optical fiber cable 21 according to a second embodiment of the present invention will be described with reference to the drawings. In addition, since it is substantially the same as the optical fiber cable 1 of 1st Embodiment mentioned above, only a different part is mainly demonstrated, the same member attaches | subjects the same code | symbol and detailed description is abbreviate | omitted.

  5 and 6, the optical fiber cable 21 is different from the optical fiber cable 1 described above in that, for example, strength members 23 and 25 as two linear bodies are on the Y axis of the slot core 7. It is to be arranged. At this time, in order to provide a margin for arranging the two strength members 23 and 25, the slot core 7 is provided with a semicircular protrusion 27 that protrudes downward in FIG. 5 at a position on the Y axis. One strength member 23 is disposed inside the slot core 7, and another strength member 25 is disposed in the protrusion 27.

  Accordingly, the arrangement state of the two strength members 23 and 25 is different from that of the optical fiber cable 1 described above, and is mounted on the Y axis inside the slot core 7. Since the strength members 23 and 25 are arranged on the Y-axis, as shown in FIG. 6, the Y-axis is the cable bending neutral line, and the X-axis with the curvature radius R from the bending center O on the X-axis. This is a directional curve (lateral bending in FIGS. 5 and 6). In addition, since the optical fiber 3 substantially coincides with the Y-axis that is the cable bending neutral line, it is possible to achieve a small-diameter cable design with good transmission characteristics for the same reason as the optical fiber cable 1 described above. it can.

  Also, the point that the lip cord 17 is not provided is different from the optical fiber cable 1 described above. However, even in the case where there is no lip cord 17, a cutting tool 19 such as a knife or the like from a substantially X-axis position that is 90 ° apart from the opening 11 of the slot groove 5 of the slot core 7 that accommodates the optical fiber 3. Since the cutting of the sheath 9 is started with the cutting edge of the blade and the sheath 9 is peeled off, the lead-out operation of the optical fiber 3 can be performed without damaging the optical fiber 3 with the cutting edge of the tool or the like during the connection work.

  In addition, the one tension body 25 arrange | positioned in said protrusion 27 can also be used as a lip cord.

  As described above, the operation and effect of the optical fiber cable 21 of the second embodiment are basically the same as those of the optical fiber cable 1 of the first embodiment described above.

  In the second embodiment described above, the two strength members 23 and 25 are mounted on the Y axis inside the slot core 7, but two or more strength members are located inside the sheath 9. Even when mounted on the Y axis, the same action and effect are brought about.

  Next, an optical fiber cable 29 according to a third embodiment of the present invention will be described with reference to the drawings. In addition, since it is substantially the same as the optical fiber cable 1 of 1st Embodiment mentioned above, only a different part is mainly demonstrated, the same member attaches | subjects the same code | symbol and detailed description is abbreviate | omitted.

  7 and 8, this optical fiber cable 29 is different from the above-described optical fiber cable 1 in that, for example, a tensile body 31 as a single linear body is disposed on the Y axis of the slot core 7. In addition, for example, strength members 33 and 35 as a pair of linear bodies are arranged so as to face the slot core 7 in the vicinity thereof with the Y axis interposed therebetween.

  In this case, with respect to controlling the cable bending direction, the pair of strength members 33 and 35 facing each other in the vicinity of the Y axis has the same function as one strength member arranged on the Y axis. The pair of strength members 33 and 35 and the other strength member 31 are basically the same as the state in which two strength members are arranged on the Y axis.

  Therefore, as shown in FIG. 8, the Y-axis is the cable bending neutral line and the X-axis direction is bent at the radius of curvature R from the bending center O on the X-axis (lateral bending in FIGS. 7 and 8). Become. In addition, since the optical fiber 3 substantially coincides with the Y-axis that is the cable bending neutral line, it is possible to achieve a small-diameter cable design with good transmission characteristics for the same reason as the optical fiber cable 1 described above. it can.

  Also, the point that the lip cord 17 is not provided is different from the optical fiber cable 1 described above. Since this point is the same as that of the second embodiment described above, detailed description is omitted. It should be noted that the pair of strength members 33 and 35 facing the vicinity with the Y axis interposed therebetween can also be used as a lip cord.

  In addition, regarding controlling the cable bending direction, as described above, even if two or more pairs of tensile bodies facing the vicinity of the Y axis are arranged on the Y axis, the same is applied. It will have a function. For example, as shown in the optical fiber cable 37 of the fourth embodiment in FIG. 9, for example, strength members 33 and 35 as a pair of linear bodies facing the vicinity of the Y axis are slot cores. 7, for example, strength members 39 and 41 as a pair of linear bodies facing the vicinity of the Y-axis with the Y-axis interposed therebetween are arranged inside the sheath 9. Others are almost the same as the optical fiber cables 1 and 29 of the first and third embodiments described above.

  In another embodiment, at least two pairs of strength members facing each other in the vicinity of the Y axis may be arranged inside the slot core 7 or inside the sheath 9. .

  As described above, the operations and effects of the optical fiber cables 29 and 37 of the third and fourth embodiments are basically the same as those of the optical fiber cable 1 of the first embodiment described above. .

(A), (B) is sectional drawing of the optical fiber cable of 1st Embodiment of this invention. It is a perspective view explaining the state in which the optical fiber cable of FIG. 1 (A) was actually bent in the X-axis direction. FIG. 2 is a perspective view illustrating a state in which the optical fiber cable of FIG. 1A is bent in the Y-axis direction, although it is actually difficult to bend. (A), (B) is explanatory drawing when extracting each optical fiber cable of FIG. 1 (A), (B). It is sectional drawing of the optical fiber cable of 2nd Embodiment of this invention. FIG. 6 is a perspective view illustrating a state where the optical fiber cable of FIG. 5 is actually bent in the X-axis direction. It is sectional drawing of the optical fiber cable of the 3rd Embodiment of this invention. FIG. 8 is a perspective view illustrating a state where the optical fiber cable of FIG. 7 is actually bent in the X-axis direction. It is sectional drawing of the optical fiber cable of 4th Embodiment of this invention.

Explanation of symbols

1 Optical fiber cable (of the first embodiment)
3 Optical Fiber 5 Slot Groove 7 Slot Core 9 Sheath 11 Openings 13 and 15 Strength Body (Linear Body)
17 Lip cord 19 Cleaving tool 21 Optical fiber cable (of the second embodiment)
23, 25 Tensile body (linear body)
27 Protrusion 29 Optical fiber cable (of the third embodiment)
31, 33, 35 Strength body (Linear body)
37 Optical fiber cable (of the fourth embodiment)
39, 41 Tensile body (linear body)

Claims (6)

  A slot core (7) having a slot groove (5) for accommodating the optical fiber (3) therein is provided at an eccentric position in the sheath (9) of the optical fiber cable, and the slot core (7) The thickness of the sheath (9) on the opening (11) side of the slot groove (5) is set larger than the thickness of the sheath (9) on the opposite side of the opening (11), and the optical fiber cable When the direction connecting the center of the opening of the slot groove in the cross section perpendicular to the longitudinal direction of the slot groove is defined as the Y axis, and the direction passing through the cable center and perpendicular to the Y axis is defined as the X axis, In order to make the Y-axis a cable bending neutral line, the linear body is arranged facing the vicinity of the Y-axis with the Y-axis sandwiched between two points on the Y-axis and / or two points away on the Y-axis. Installed in the slot groove. The optical fiber is arranged so that the position of the optical fiber substantially coincides with the Y-axis, and the sheath (9) on the opposite side of the opening (11) of the slot groove (5) An optical fiber cable characterized in that the mechanical strength is compensated for at the bottom of the slot core (7) opposite to the opening (11).   2. The optical fiber cable according to claim 1, wherein the linear body is disposed on the Y axis and embedded in both the slot core and the sheath.   2. The optical fiber cable according to claim 1, wherein the linear body is disposed at two points apart on the Y-axis and is embedded only in the slot core. A slot core (7) having a slot groove (5) for accommodating the optical fiber (3) therein is provided at an eccentric position in the sheath (9) of the optical fiber cable, and the slot core (7) The thickness of the sheath (9) on the opening (11) side of the slot groove (5) is set larger than the thickness of the sheath (9) on the opposite side of the opening (11), and the optical fiber cable When the direction connecting the center of the opening of the slot groove in the cross section perpendicular to the longitudinal direction of the slot groove is defined as the Y axis, and the direction passing through the cable center and perpendicular to the Y axis is defined as the X axis, In order to make the Y-axis a cable bending neutral line, the linear body is arranged on the Y-axis and in the vicinity of the Y-axis with the Y-axis in between, and the linear body on the Y-axis and the Y-axis are sandwiched between them. And the linear body arranged opposite to the vicinity of the Y axis Provided at a position apart in the direction, and, provided by arranging such that the position of the optical fiber to be received in the slot grooves are substantially coincident with the Y-axis, wherein the opening of the slot grooves (5) (11) The mechanical strength of the thin portion of the sheath (9) on the opposite side of the opening is compensated at the bottom of the slot core (7) on the opposite side of the opening (11). Fiber optic cable.   The optical fiber cable according to any one of claims 1 to 4, wherein the linear body is made of a steel wire or FRP.   A lip cord is vertically attached to the inside of the sheath, and the lip cord is disposed inside the sheath at a position near the X axis and on the outer periphery of the slot core. The optical fiber cable in any one of Claims 1-5.

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