JP4741876B2 - Fiber optic cable - Google Patents

Description

  The present invention relates to an optical fiber cable such as an optical fiber drop cable or an indoor optical fiber cable used when an optical fiber core wire is pulled down from an optical fiber cable to a small-scale building or a general home.

  Conventionally, FTTH (Fiber to the Home), that is, home or office, can be used to transmit and receive high-speed broadband information such as ultra-high-speed data, from an access optical fiber cable extended from a telephone station, to a building or general home. An optical fiber core cable such as an optical fiber tape core is drawn down to a subscriber's home, and an optical fiber drop cable is used for wiring the optical fiber core cable. In other words, an optical fiber drop bar cable is used when an optical fiber is drawn into a home from a main cable branch closure on a utility pole. Mainly, an optical fiber drop cable (outdoor line) as shown in FIG. In order to apply to a longer laying span length, a low optical fiber aerial cable with an increased support line size is used.

  Referring to FIG. 2, a conventional optical fiber drop cable 101 includes, for example, two two-core optical fiber ribbons 103 as optical fiber cores as shown in FIG. A cross-sectional shape covering at least a pair of tensile members 105 arranged in parallel on both sides of the two-core optical fiber ribbon 103 and covering the outer periphery of the optical fiber ribbon 103 and the pair of tensile members 105. For example, a long optical element 109 is constituted by a flat sheath 107 made of resin.

  The center axis (Y axis) of the two-core optical fiber ribbon 103 is perpendicular to the first plane 111 passing through the center axis (X-axis) of the two-core optical fiber ribbon 103 and the pair of tension members 105. The surface of the sheath 107 in the third and fourth planes 115 and 117 perpendicular to the outer surface of the two two-core optical fiber ribbons 103 separated from both sides of the second plane 113 passing by a distance L is a cross-section. For example, isosceles triangle notches 119 and 121 are formed.

  Cable support integrated with the long optical element part 109 and a sheath 127 made of resin covering a suspension line 125 as a support line via a neck part 123 on the left side of the jacket 107 in the optical element part 109 The optical fiber drop cable 101 is composed of the line portion 129. In addition, a plane passing through the central axis (X axis) of the suspension line 125 coincides with the first plane 111.

Patent Document 2 discloses an optical fiber core wire as in the optical element portion in the optical fiber drop cable, and at least a pair of strength members disposed in parallel on both sides of the optical fiber core wire. A long optical element portion is shown by a sheath made of a resin having a flat cross-sectional shape covering the outer periphery of the optical fiber core and a pair of strength members, for example. In this long optical element portion, a notch is formed on the surface of the sheath between the optical fiber core wire and the strength member apart from the optical fiber core wire, and the cross section of the notch is an isosceles triangle shape or a right angle. It has a triangular shape, and the tip of the notch does not face the optical fiber core wire.
JP 2004-206008 A JP 2002-90593 A

  By the way, in the optical fiber drop cable 101 of FIG. 2 as shown in Patent Document 1 described above, the suspension line 125 and the optical element portion 109 are cut off from the neck portion 123 to separate the suspension line 125 and the optical element portion 109. Incisions are made along the notches 119 and 121 from the end of the optical fiber drop cable 101, and the sheath 107 is torn by grasping with fingers, and the two-fiber optical fiber ribbon 103 is led out. Such a lead-out method can be torn in the direction in which the two strength members 105 are connected and in the vertical direction. In the case of the optical fiber drop cable 101 in which the two-fiber optical fiber ribbon 103 is mounted, shearing is given to the two-fiber optical fiber ribbon 103 when tearing in the direction perpendicular to the line connecting the two strength members 105. There is a risk of damage.

  In the optical fiber drop cable shown in Patent Document 2 described above, the cross section of the notch is made into an isosceles triangle shape or a right triangle shape so as not to damage the optical fiber core wire even if, for example, a spawning tube is inserted into the notch However, since the notch tip of the notch does not face the optical fiber core wire, the lead-out property of the optical fiber core wire is inferior to that shown in Patent Document 1 described above.

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

In order to achieve the problem to be solved by the invention, an optical fiber cable of the invention includes an optical fiber core, a pair of strength members disposed on both sides in parallel in the vicinity of the optical fiber core, A flat sheath in which the center of the optical fiber core and the center of the tensile body are covered so as to pass through the first plane; a pair of notches for tearing the sheath provided on both side surfaces of the long side of the sheath; The notch is arranged at a diagonal position with respect to the center of the optical fiber element part, the cross section has an obtuse triangular shape, and the notch tip of the notch to sit near the end of the optical fiber, 2 sides except an opening portion of the notch is located outside the long side direction of the optical fiber element portion from the notch tip, in the first plane Distance between the position of intersection between the first plane of the perpendicular dropped from the notch tip and outer positions in the long side direction of the fiber cable is characterized in that is within 0.15 mm.

  In the optical fiber cable according to the present invention, in the optical fiber cable, it is preferable that a long cable support line portion in which a support wire is covered with a sheath is integrated with the optical fiber element portion in parallel with each other.

  As can be understood from the description of the means for solving the problems as described above, according to the present invention, the notch is disposed at a diagonal position with respect to the center of the optical fiber element portion, and the cross section is an obtuse triangle. The notch tip of the notch is positioned in the vicinity of the end of the optical fiber core, and the two sides excluding the opening of the notch are in the long side direction of the optical fiber element portion from the notch tip. Since it is located outside, the line connecting the two notch tips approaches parallel to the long side of the optical fiber core. Therefore, when the sheath is grasped with a finger and is torn, the crack runs along the boundary between the optical fiber core and the sheath.

  At this time, the sheath tears in a direction orthogonal to the line connecting the two strength members, but since the crack runs along the boundary between the optical fiber core and the sheath, no shear is applied to the optical fiber core. Further, since the optical fiber core wire is not pulled in the major axis direction, no tension is applied between the core wires and the core wires are not separated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 1, for example, an optical fiber drop cable 1 as an optical fiber cable includes, for example, a four-core optical fiber tape core 3 as an optical fiber core, and a four-fiber optical fiber ribbon 3 sandwiched between The cross-sectional shape covering the outer periphery of at least a pair of strength members 5 arranged in parallel on both sides and the optical fiber tape core wire 3 and the pair of strength members 5 is a flat shape, for example, polyvinyl chloride (PVC). A long optical element portion 9 is composed of a sheath (sheath) 7 made of a thermoplastic resin such as flame retardant polyethylene (PE).

  A plane passing through the four-core optical fiber ribbon 3 and the central axis (X axis) of the pair of strength members 5 is a first plane 11. A plane perpendicular to the first plane 11 and passing through the central axis (Y axis) of the four-core optical fiber ribbon 3 is a second plane 13. Vertical planes passing through the outer surface of the four-core optical fiber ribbon 3 away from both sides of the first plane 11 by a distance L1 are third and fourth planes 15 and 17, respectively. Vertical planes separated by a distance L2 from the third and fourth planes 15 and 17 to the left and right are the fifth and sixth planes 19 and 21, respectively.

  Intersection points at which the fifth and sixth planes 19 and 21 and the first plane 11 intersect are defined as A and B, respectively. Points on the fifth and sixth planes 19 and 21 that are separated from the intersections A and B by a distance L3 in the vertical direction are defined as points C and D, respectively. These points C and D are the notch tips of the notch 23. The notch 23 is disposed diagonally with respect to the center O of the optical fiber element portion 9 (intersection of the first plane 11 and the second plane 13), and the cross section has an obtuse triangular shape. Two sides 27 and 29 excluding the opening 25 of the notch 23 are the notch tips (C and D) so that the notch tip (C and D) end of the notch 23 is positioned near the end of the optical fiber core 3. Further, the optical fiber element portion 9 is located outside the long side direction. The notch 23 has an obtuse triangular cross section. That is, the angle (θ) between the opening 25 and the side 29 is an obtuse angle.

  For example, polyvinyl chloride (PVC) or flame-retardant polyethylene in which the long optical element portion 9 and a suspension wire 33 as a support wire are covered via a neck portion 31 on the left side of the sheath 7 in the optical element portion 9. The optical fiber drop cable 1 is composed of a cable support line portion 37 integrated with a sheath 35 made of a thermoplastic resin such as (PE). Moreover, the plane passing through the central axis (X axis) of the suspension line 33 coincides with the first plane 11.

  With the above configuration, the two sides 27 and 29 excluding the opening 25 of the notch 23 are formed on the notch tip (C) so that the notch tip (C, D) of the notch 23 is positioned near the end of the optical fiber core wire 3. , D) is located on the outer side in the long side direction of the optical fiber element portion 9, the line connecting the two notch tips (C, D) is parallel to the long side of the four-fiber optical fiber core wire 3. Will approach. Therefore, when the sheath 7 is grasped with a finger and is torn, the crack runs along the boundary between the four-core optical fiber 3 and the sheath 7.

  At this time, the sheath 7 is torn in a direction connecting the centers of the two strength members 5, that is, in a direction orthogonal to the first plane 11, but the crack runs along the boundary between the four-fiber optical fiber ribbon 3 and the sheath 7. Therefore, no shear is applied to the four-core optical fiber core wire 3. Further, since the four-core optical fiber core wire 3 is not pulled in the major axis direction, no tension is applied between the core wires and the core wires are not separated.

  A distance L2 between the third and fourth planes 15 and 17 and the fifth and sixth planes 19 and 21 is preferably within 0.15 mm. This is because if the distance L2 exceeds 0.15 mm, the distance from the notch tip of the notch 23 to the end of the four-core optical fiber core wire 3 becomes long, and the tearability deteriorates.

  The optical fiber drop cable 1 shown in FIG. As the optical fiber ribbon 3, an optical fiber ribbon that can be easily divided into single optical fibers was used. The tensile body 5 was made of aramid FRP, the suspension wire 33 was made of φ1.2 mm galvanized steel wire, and the sheaths 7 and 35 were made of flame-retardant polyolefin. The outer diameter was about 5.8 × 2.0 mm.

  As a result of trial manufacture, transmission loss is 0.25 dB / km or less (measurement wavelength: 1.55 μm), loss temperature fluctuation at −30 to + 70 ° C. × 3 cycles is 0.1 dB / km or less (measurement wavelength: 1.55 μm), good It was confirmed that.

  From the experimental results, the notch tip (C, D) of the notch 23 is ± 0.15 mm from the end of the optical fiber ribbon 3, and the opening 25 of the notch 33 is light from the position of the notch tip (C, D). When positioned outside the element portion 9, the crack runs along the boundary between the optical fiber ribbon 3 and the sheath 7, and easily breaks without breaking the optical fiber ribbon 3 that can be easily divided into single fibers. The mouth was possible.

  In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change. Although the optical fiber drop cable 1 has been described as an example of the optical fiber cable, an indoor optical fiber cable having only the optical element portion from which the cable support line portion 33 is removed can be used.

It is sectional drawing of the optical fiber drop cable as an optical fiber cable of this invention, for example. It is sectional drawing of the optical fiber drop cable as a conventional optical fiber cable, for example.

Explanation of symbols

1 Optical fiber drop cable (optical fiber cable)
3 4-core optical fiber ribbon (optical fiber core)
5 Tensile Body 7 Sheath 9 Optical Element Part 11 First Plane 13 Second Plane 15 Third Plane 17 Fourth Plane 19 Fifth Plane 21 Sixth Plane 23 Notch 25 Opening 27 Side 29 Side 31 Neck 33 Hanging Line (Support Line) )
35 Sheath 37 Cable support line

Claims (2)

An optical fiber core, a pair of strength members disposed on both sides in parallel in the vicinity of the optical fiber core, and the center of the optical fiber core and the center of the strength body are covered so as to pass through the first plane. A long optical fiber element portion is constituted by the flat-shaped sheath and a pair of notches for tearing the sheath provided on both side surfaces of the long side of the sheath,
The notch is disposed at a diagonal position with respect to the center of the optical fiber element portion, the cross section has an obtuse triangular shape, and the notch tip of the notch should be positioned near the end of the optical fiber core wire. The two sides excluding the opening of the notch are located outside the long side direction of the optical fiber element part from the notch tip,
The distance between the outer position in the long side direction of the optical fiber core on the first plane and the position of the intersection of the perpendicular drawn from the tip of the notch with the first plane is within 0.15 mm. Fiber optic cable. The optical fiber element unit, according to claim 1 Symbol placement of the optical fiber cable cable support wire portion of the elongated coated support wire with a sheath is characterized in that it is parallel to integrated with each other.

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