JP4141924B2 - Fiber optic cable - Google Patents

Description

The present invention relates to an optical fiber cable.

  For the realization of FTTH, optical wiring to medium to small-scale areas is being advanced. The key point is how to construct a network economically and efficiently for users who are scattered across the board. Recently, in order to increase the efficiency of use of the core wire, a PDS system using a PON (Passive Optical Network) system represented by E-PON is increasing. The requirements for fiber optic cables include a core number series that can support the network system as described above, ease of cable laying and intermediate post branching, It is possible to cover the area of the access system and the vertical system in the campus.

  In order to satisfy the above requirements, there are required performances such as a small diameter / light weight structure, intermediate post-branching workability, and prevention of core movement.

  More specifically, in order to efficiently construct a network, it is effective to make the cable as thin as possible and increase the density. By reducing the diameter of the cable, the fiber mounting density in the pipe line can be increased in the underground area, and more cables can be hung together in the aerial area. Furthermore, these cable installation operations can be facilitated by reducing the weight of the cable.

  In the intermediate post-branching method, the existing cable is rear-branched at an arbitrary location near the new user, and the core wire is taken out. When taking out the core, it is important not to damage other cores. Therefore, an aerial cable for an access system is required to have a structure that allows easy post-branching work and good core wire takeout.

  Also, in cables installed in the aerial area, the core wire may move as the ambient temperature fluctuates, which may cause an increase in transmission loss at the terminal, so the overhead cable must have a certain amount of core wire binding force. There is.

  In recent years, as an optical fiber cable structure that meets the above requirements, a structure generally called a slotless structure has become widespread (see, for example, Patent Document 1).

  An optical fiber cable 101 having a slotless structure shown in FIG. 8 is an aerial round type SM4 core tape core type 24 core cable. In the center of the optical fiber cable 101, six four-core optical fiber ribbons 103 are laminated, and a PP (polypropylene) yarn inclusion 105 is disposed around these four-fiber ribbons 103. After that, it is wound horizontally on the outer periphery of the interposition body 105 by a presser winding tape 107 such as a water absorbing tape.

  Further, two strength members 109 (tension members) and two tear strings 111 are vertically attached to the outer side of the press-wound tape 107, and the above-described six four-core optical fiber ribbons 103 and the interposer 105 are provided. Two strength members 109, two tear strings 111, and a cable sheath 113 covering them are extruded together.

  The above-described four-core optical fiber ribbon 103 has an optical fiber strand 119 having a diameter of 250 μm by covering the outer periphery of a quartz optical fiber 115 having a diameter of 125 μm with a sheath 117 of UV resin as shown in FIG. The four optical fiber strands 119 are covered with a collective UV resin having a thickness of 0.48 mm and a width of 1.22 mm.

In the optical fiber cable 101 of FIG. 8, two strength members 109 are arranged on both sides (up and down in FIG. 8) in the stacking direction (Y-axis direction) of the six four-core optical fiber ribbons 103. Two tear strings 111 are disposed on both sides (left and right sides in FIG. 8) in the X-axis direction orthogonal to the stacking direction (Y-axis direction) of the four-core optical fiber ribbon 103, and the cable sheath 113 Ribs 121 are formed on the outer sides of the two tear strings 111.
JP 2001-201675 A

  Incidentally, the conventional optical fiber cable 101 has a problem that it is difficult to obtain stable transmission characteristics when a single-core optical fiber 119 is used as an optical fiber to be applied. One of the factors is that when the optical fiber cable 101 is manufactured or handled, the optical fiber tape core wire 103 enters a gap between the interposition bodies 105 forming the inner core, which causes an increase in transmission loss. . Furthermore, as another factor, since the optical fiber ribbon 103 is not rigid, microbending occurs due to the mutual interference of the optical fiber ribbon 103, resulting in an increase in transmission loss. In particular, as the number of the cores of the optical fiber ribbon 103 increases, the latter factor becomes more prominent.

  Referring to FIG. 10, it is assumed that the direction connecting the two strength members 109 of the conventional optical fiber cable 101 is the Y axis, and the optical fiber cable 101 is bent in the Y axis direction with a point O on the Y axis as the bending center. Then, since the longitudinal direction of the optical fiber ribbon 103 is oriented in the X-axis direction orthogonal to the Y axis, the optical fiber strands 119 of the optical fiber ribbon 103 do not expand or contract. However, due to the relationship between the two strength members 109, it is difficult for bending in the Y-axis direction to actually occur, and as shown in FIG. It will be bent in the axial direction.

  When bent in the X-axis direction, in the cross-sectional direction, the optical fiber strand 119 on the side with the larger bend R (outside of the bend) extends, and conversely, the optical fiber strand 119 on the side with the smaller bend R (outside of the bend) As a result, the optical fiber strands 119 gather near the Y axis as shown in FIGS. 11B and 11C, and the optical fiber strands 119 buckle depending on the case. There was a problem. Further, in the longitudinal direction, there is a problem that the optical fiber strand 119 in the contracted portion is undulated in a ramen shape (wave shape), causing transmission loss due to microbending.

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

An optical fiber cable according to the present invention is an optical fiber including a single optical fiber array layer composed of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires arranged in parallel in the first direction. An element part,
Tensile bodies (19) disposed on both sides on a straight line of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires (3) arranged vertically in parallel in the first direction;
A tape-like inclusion disposed so as to be sandwiched from both sides in the second direction orthogonal to the first direction between the one optical fiber array layer and the cable sheath in the optical element portion;
Each of the strength members is arranged on a straight line of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires arranged vertically in parallel in the first direction. is there.

An optical fiber cable according to the present invention includes one optical fiber array layer composed of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires arranged vertically in parallel in a first direction and An optical element portion composed of a plurality of optical fiber array layers arranged in a second direction perpendicular to the first direction;
Tensile bodies (19) disposed on both sides on a straight line of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires (3) arranged vertically in parallel in the first direction;
A cable sheath covering the optical element part and the tensile body;
Between the outermost layer of the plurality of optical fiber arrangement layers in the optical element portion and the cable sheath, in the second direction orthogonal to the first direction, which prevents thermal fusion and further prevents core wire movement. A tape-like interposed body is provided so as to be sandwiched from both sides, and an interlayer interposed body is disposed between the plurality of optical fiber array layers.

  As can be understood from the means for solving the above-described problems, according to the present invention, the optical fiber cable is orthogonal to the first direction that reliably connects the two strength members due to the relationship between the two strength members. A bending in the second direction is made with one point in the second direction as the bending center. Therefore, since the parallel direction of the plurality of optical fiber strands constituting the optical fiber array layer is the first direction, each optical fiber does not expand or contract.

As a result, the optical fiber cable can reliably reduce the difference in optical fiber length when the cable is bent, and can prevent an increase in transmission loss due to the cable bending. In addition, since the tape-like inclusion is disposed so as to sandwich the optical fiber array layer composed of a plurality of optical fibers from the second direction, mutual interference between the plurality of optical fibers can be reduced. Further, the tape-like inclusions and the interlayer inclusions have an effect of preventing thermal fusion between the optical fiber and the cable sheath, and further preventing the movement of the core wire.

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

  Referring to FIG. 1, an optical fiber cable 1 according to this embodiment includes, for example, a plurality of optical fiber strands 3 as a plurality of optical fibers arranged in parallel substantially in a straight line, for example, in the X-axis direction as a first direction. The optical fiber array layer 5 is vertically added to form, for example, a laminate tape 7 as a tape-like interposition, and the plurality of optical fiber strands 3 as a second direction perpendicular to the X-axis direction, for example, Y The optical element section 9 is composed of the optical fiber array layer 5 and the two laminated tapes 7 arranged so as to be sandwiched from both sides in the axial direction.

  As shown in FIG. 2 (A), each optical fiber 3 is formed to have a diameter of 250 μm by covering the outer periphery of a 125 μm diameter quartz optical fiber 11 with a UV resin sheath 13. In this embodiment, 24 optical fiber strands 3 are vertically attached in parallel.

  Further, as shown in FIG. 2 (B), the laminate tape 7 has, for example, a metal thin film 15 as a tape base material and, for example, water absorption as a buffer material that contacts the 24 optical fiber strands 3 described above. The nonwoven fabric 17 is laminated with an adhesive. Accordingly, the two laminated tapes 7 are configured to be sandwiched so that the water-absorbing nonwoven fabric 17 side abuts the 24 optical fiber strands 3 respectively.

  Further, in the optical fiber cable 1, two strength members 19 are arranged on both sides on the straight line of the 24 optical fiber wires 3. In other words, the 24 optical fiber strands 3 are vertically attached in parallel on the X axis connecting the two strength members 19. Each strength member 19 is made of a 0.7 mmφ single steel wire.

  In addition, for example, a tear string 21 as two tear filaments is vertically arranged near both sides in the X-axis direction of the 24 optical fiber strands 3. In other words, it is arranged in the vicinity of each of the strength members 19. Each tear string 21 in this embodiment is a 3000 denier Tetron string.

  The 24 optical fiber wires 3, the two laminate tapes 7, the two strength members 19, and the two tear strings 21 are covered with a cable sheath 23 made of resin, and the long optical fiber cable 1. Configure. The cable sheath 23 is formed with rib portions 25 located outside the two tear strings 21.

  The optical fiber cable 1 configured as described above has an outer diameter of 9.5 mm and a mass of 70 kg / km.

  Note that, for example, the laminate tape 7 as the tape-like inclusion prevents heat fusion between the 24 optical fiber strands 3 and the cable sheath 23, and further moves the core wire (24 optical fiber strands 3). This prevents the movement of

  With this configuration, referring to FIG. 3, this optical fiber cable 1 actually has a point O on the Y-axis orthogonal to the X-axis direction connecting the two strength members 19 in relation to the two strength members 19. It becomes a bending in the Y-axis direction with respect to the bending center. When the optical fiber cable 1 is bent in the Y-axis direction in this way, the straight line direction of the optical fiber array layer 5 in which the plurality of optical fiber strands 3 are arranged in parallel is the X-axis direction. There will be no expansion and contraction.

  That is, as shown in FIG. 4, when bent in the X-axis direction with a point O on the X-axis as the bending center, the optical fiber 3 on the side with the larger bending R (outside of bending) in the cross-sectional direction. Conversely, the optical fiber 3 on the side with the smaller bending R (outside of the bending) contracts, so that microbending occurs and transmission loss increases. However, in reality, the bending in the state of FIG. 4 hardly occurs due to the relationship between the two strength members 19.

  Therefore, this optical fiber cable 1 reliably reduces the optical fiber line length difference when the cable is bent. Further, since the tape-like inclusions of the laminate tape 7 are arranged in the Y-axis direction of the plurality of optical fiber strands 3, mutual interference of the optical fiber strands 3 is alleviated.

  When the optical fiber cable 1 is taken out from the optical fiber cable 1 in order to branch the optical fiber cable 1 in the middle, the two tear strings 21 are arranged on both sides of the plurality of optical fiber strands 3 in the X-axis direction. Since it is arranged in the vicinity, if a part of the rib portion 25 of the cable sheath 23 is shaved, the tear string 21 can be taken out, and the cable sheath 23 can be easily torn by grasping the taken tear string 21. The optical fiber 3 can be taken out at an arbitrary place.

  Below, the manufacturing method of the optical fiber cable 1 shown in FIG. 1 is demonstrated.

Referring to FIG. 5, as an optical cable manufacturing apparatus 27 used in this embodiment, 24 optical fiber delivery bobbins 29 for feeding out the optical fiber 3 and a laminate tape 7 are wound. Two delivery bobbins 31 for tape-like intervening bodies, two delivery bobbins 33 for strength members around which the tensile body 19 is wound up, and two tear filaments around which the tear string 21 is wound up A delivery bobbin 35 is provided.

  Further, the optical cable manufacturing apparatus 27 includes an optical element portion 9 composed of the 24 optical fiber wires 3 and the two laminated tapes 7, two strength members 19, and two tear strings 21. Further, an optical cable extruder 37 for extruding the optical fiber cable 1 by covering the resin of the cable sheath 23 is provided.

  The optical cable extruder 37 is provided with a nipple portion 41 as shown in FIG. 6 at the center of the extrusion head 39, and a flow through which the resin of the cable sheath 23 is pushed out to the outer periphery of the nipple portion 41. A die portion 43 having a die hole (not shown) having substantially the same shape as the outer peripheral shape of the cross section of the optical fiber cable 1 of FIG. 1 is provided via a path (not shown).

  As shown in FIG. 6, the nipple portion 41 has, for example, 24 nipple holes 45 each having a substantially circular cross section as a through hole through which the 24 optical fiber strands 3 pass substantially straight on the X axis. It is formed in a shape. Further, nipple holes 47 through which the laminate tape 7 passes are formed on both outer sides in the Y-axis direction with respect to the 24 nipple holes 45 so as to have a substantially rectangular cross section. On the outside, a nipple hole 49 having a substantially circular cross section through which the tensile strength member 19 passes is provided on the X axis, and a nipple hole 51 through which the tear string 21 passes is formed in the vicinity of the nipple hole 49.

  With the above configuration, in FIG. 5, the 24 optical fiber wires 3 wound around the delivery bobbins 29, 31, 33, 35, the two laminate tapes 7, the two strength members 19, and the two tears The strings 21 are pulled out and sent into the extrusion head 39. The 24 optical fiber strands 3 pass through the nipple holes 45, the two laminate tapes 7 pass through the nipple holes 47, the two strength members 19 pass through the nipple holes 49, and two tears. While the string 21 travels through the nipple hole 51 and the molten resin P of the cable sheath 23 is pushed out from the flow path of the die part 43, the optical fiber cable 1 as shown in FIG. Obtainable.

  That is, this manufacturing method includes the following steps.

(1) Step of pulling out 24 optical fiber wires 3 from 24 nipple holes 45
(2) Pulling out two laminate tapes 7 from two nipple holes 47
(3) Step of pulling out the two strength members 19 from the two nipple holes 49
(4) Step of pulling out the two tear strings 21 from the two nipple holes 51
(5) Extruding the resin P of the cable sheath 23 together with the 24 optical fiber wires 3 and the two laminate tapes 7 from the die portion 43
(6) In front of the die portion 43 in the extrusion direction, the resin P of the cable sheath 23 is composed of the optical element portion 9 composed of 24 optical fiber strands 3 and two laminate tapes 7 and two strength members 19. The step of solidifying the resin P and integrating the optical element portion 9 and the strength member 19 in the state of surrounding the optical fiber portion 9 and the step of drawing the optical fiber 3 from the nipple hole 45 and the step of laminating the laminate tape 7 from the nipple hole 47 The drawing process, the drawing process of the tear string 21 from the nipple hole 49, and the extrusion process of the resin P or the like from the die portion 43 are performed almost simultaneously.

  Moreover, according to the said manufacturing method, the optical fiber cable 1 provided with the optical fiber strand 3, the tensile strength body 19, and the cable sheath 23 can be rapidly manufactured in a series of continuous processes.

  Based on the manufacturing method of the optical fiber cable 1 as described above, various optical fiber cables 1 were manufactured by changing the number of cores of the optical fiber 3, and the transmission characteristics were evaluated.

  As a result, the optical fiber cable 1 having an eight-core × one-row structure had a transmission loss of 0.25 dB / km or less, and an increase in loss when bent with a curvature radius R of 10 mm was 0.01 dB or less.

  Similarly, the 16-fiber × 1-row optical fiber cable 1 had a transmission loss of 0.25 dB / km or less and a loss increase of 0.01 dB or less when bent with a radius of curvature R of 10 mm.

  Similarly, the optical fiber cable 1 having a 24-core × 1-row structure had a transmission loss of 0.25 dB / km or less and a loss increase of 0.01 dB or less when bent with a radius of curvature R of 10 mm.

  Therefore, in the optical fiber cable 1 of the present invention, the difference in optical fiber length when the cable is bent is surely reduced, and the tape shape of the laminate tape 7 arranged in the Y-axis direction of the plurality of optical fiber strands 3 is obtained. Mutual interference between the optical fiber strands 3 is mitigated by the intervening body.

  In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change.

  The optical fiber cable 1 according to the above-described embodiment has been described as a single-layer structure of the optical fiber array layer 5 in which a plurality of optical fiber strands 3 are arranged in parallel as a plurality of optical fibers. As shown in FIG. 7, the optical fiber cable 1 may have a structure in which optical fiber array layers 5 including a plurality of optical fiber wires 3 are stacked in a plurality of layers in the Y-axis direction. In FIG. 7, three optical fiber array layers 5 are laminated.

  In the case where a plurality of optical fiber array layers 5 are stacked in this way, by inserting an interlayer intervening body 53 between the stacks of the optical fiber array layers 5 in the Y-axis direction, Mutual interference can be mitigated. In addition, between the outermost layer of the optical fiber array layer 5 and the cable sheath 23, as in the above-described embodiment, a laminate tape 7 that is a tape-like interposition is provided with a plurality of optical fiber array layers from both sides in the Y-axis direction. It is desirable to arrange so as to sandwich 5.

  Moreover, as the optical fiber cable 1 of other embodiment, the some optical fiber which comprises the optical fiber arrangement | sequence layer 5 may be a some optical fiber core wire. Alternatively, the plurality of optical fibers may be optical fiber ribbons.

It is sectional drawing of the optical fiber cable of embodiment of this invention. (A) is sectional drawing of the optical fiber strand of FIG. 1, (B) is a fragmentary sectional view of the tape-shaped intermediate body of FIG. It is a perspective view explaining the state in which the optical fiber cable of FIG. 1 was actually bent in the Y-axis direction. FIG. 2 is a perspective view illustrating a state in which the optical fiber cable of FIG. 1 is bent in the X-axis direction, although it is actually difficult to bend. It is a schematic explanatory drawing of the manufacturing apparatus of the optical fiber cable of embodiment of this invention. It is sectional drawing of a nipple part. It is sectional drawing of the optical fiber cable of other embodiment of this invention. It is sectional drawing of the conventional optical fiber cable. It is sectional drawing of the 4-core optical fiber tape core wire of FIG. FIG. 10 is a perspective view illustrating a state in which a conventional optical fiber cable is bent in the Y-axis direction, although it is actually difficult to occur. (A) is a perspective view for explaining a state in which a conventional optical fiber cable is actually bent in the X-axis direction, and (B) and (C) are plural when bent as shown in (A). It is sectional drawing which shows an example of the state of this optical fiber strand.

Explanation of symbols

1 Optical fiber cable 3 Optical fiber strand (optical fiber)
5 Optical fiber array layer 7 Laminate tape (tape inclusion)
9 Optical element 15 Metal thin film (tape base material)
17 Water-absorbing nonwoven fabric (buffer material)
19 Tensile body 21 Tear string (Tear line)
23 Cable sheath 25 Rib portion 27 Optical cable manufacturing apparatus 37 Optical cable extruder 39 Extrusion head 41 Nipple portion 43 Die portion 53 Interlayer inclusion

Claims (2)

An optical element section including one optical fiber array layer (5) composed of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires (3) arranged vertically in parallel in the first direction (9) and
Tensile bodies (19) disposed on both sides on a straight line of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires (3) arranged vertically in parallel in the first direction;
A cable sheath (23) covering the optical element part (9) and the tensile body (19);
Tape-like inclusions arranged so as to be sandwiched between the one optical fiber array layer (5) and the cable sheath (23) in the optical element section (9) from both sides in the second direction orthogonal to the first direction. An optical fiber cable comprising (7). A first optical fiber array layer (5) comprising a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires (3) arranged vertically in parallel in the first direction, and the first An optical element section (9) composed of a plurality of optical fiber array layers (5) arranged in a second direction orthogonal to the direction;
Tensile bodies (19) disposed on both sides on a straight line of a plurality of optical fiber strands, optical fiber core wires, or optical fiber tape core wires (3) arranged vertically in parallel in the first direction;
A cable sheath (23) covering the optical element part (9) and the tensile body (19);
In the optical element section (9), between the outermost layer of the plurality of optical fiber array layers (5) and the cable sheath (23), heat fusion is prevented, and further, the core wire movement is prevented . A tape-like inclusion (7) arranged so as to be sandwiched from both sides in a second direction orthogonal to one direction and an interlayer inclusion (53) arranged between the plurality of optical fiber array layers (5) An optical fiber cable characterized by that.

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