JP3854164B2 - Fiber optic drop cable - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aerial optical fiber drop cable used when an optical fiber is pulled from an optical fiber cable to a house or the like.
[0002]
[Prior art]
Conventionally, in order to be able to send and receive high-speed broadband information such as ultra-high-speed data at FTTH (Fiber to the Home), that is, at home or in the office, an optical fiber cable extended from a telephone station is sent to a subscriber's house such as a general house An optical fiber drop cable suitable for wiring the optical fiber cable core wire is used. In other words, an optical fiber drop cable (outdoor line) is a cable used when an optical fiber is drawn into the home from a utility pole.
[0003]
This type of optical fiber drop cable is disclosed in Japanese Patent Laid-Open No. 2001-83385. That is, as shown in FIG. 2, the structure of the optical fiber drop cable 101 has a pair of conductive metal wires such as steel wires, FRP, tensile strength on both sides of the optical fiber core wire or the optical fiber tape core wire 103. A tensile member 105 (tension member; TM for short) made of fiber or the like is attached. An optical element portion 109 that is collectively covered with a thermoplastic resin cable sheath 107, and a cable support in which a thermoplastic resin sheath 113 is covered with a support wire 111 (TM) made of a metal wire, for example, a steel wire. In general, an SSD structure in which the line portion 115 is integrally connected to each other via a neck portion 117 that is parallel to and constricted with each other.
[0004]
Referring also to FIG. 3, when the optical fiber ribbon 103 is pulled from the optical fiber cable 119 extended from the telephone office to each home, the optical fiber drop cable 101 is used, and the drop cable 101 is used. The optical element portion 109 and the cable support wire portion 115 are separated by partially cutting off the neck portions 117 at both end portions, and the end portion 115A of the one cable support wire portion 115 thus separated is an outdoor line retainer for the utility pole 121. 123, and the other end 115B is fixed to a part of the house via the pulling fastener 123.
[0005]
One end 109A of the optical element 109 is connected to a cable branch box 125 (cable closure) on the utility pole 121, and the other end 109B is connected to an indoor OE converter or termination box 127. .
[0006]
[Problems to be solved by the invention]
By the way, in the conventional optical fiber drop cable 101, it is desirable that the height HA of the optical element portion 109 and the height HB of the cable support line portion 115 are the same. The reason is that if the height HA and the height HB are different from each other, the optical fiber drop cable 101 may be bent at the neck 117 when it is wound around a bobbin or the like. Therefore, the thickness of the sheath 113 of the cable support line portion 115 needs to be increased in accordance with the height HA of the optical element portion 109.
[0007]
In general, the cable support wire portion 115 has a sheath 113 coated concentrically with respect to the support wire 111. That is, in FIG. 2, the height HB and the width WB of the cable support line portion 115 are covered in substantially the same state. However, when the sheath 113 is thickly coated in this way, the long diameter WC of the optical fiber drop cable 101, that is, the entire long diameter WC in the connecting direction of the optical element portion 109 and the cable support line portion 115 (the width of the optical element portion 109). The dimension WA + the width dimension WB of the cable support line portion 115 is increased. In the case of an aerial cable, there is a problem that the wind pressure load applied to the cable 101 increases as the cable major axis WC increases, which is disadvantageous in terms of cable strength.
[0008]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical fiber drop cable that achieves both a reduction in wind pressure load in a cable erected state and a stable cable manufacturability. is there.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an optical fiber drop cable according to a first aspect of the present invention comprises an optical fiber core wire and at least a pair of first strength members arranged in parallel on both sides of the optical fiber core wire. In an optical fiber drop cable in which a long optical element portion covered with a cable sheath and a long cable support line portion covered with a sheath of a second strength member are fixed in parallel to each other,
Of the outer diameter of the sheath of the cable support line part, the height difference in the direction orthogonal to the connecting direction of the optical element part and the cable support line part is within ± 10% of the dimensional difference from the height dimension of the optical element part. In addition, the width dimension in the same direction as the connecting direction is smaller than the height dimension of the cable support line portion.
[0010]
Accordingly, since the height dimension of the cable support line portion is almost the same as the height dimension of the optical element portion, the winding state of the cable is good and the cable manufacturability is stabilized, and the optical element portion and the cable support line portion are also achieved. Since the major axis of the cable, which is the entire length in the connecting direction, becomes smaller, the wind pressure load applied to the cable in the installed state is reduced. In addition, in terms of cable manufacturability that makes the cable wound around a bobbin or the like, the dimensional difference between the height dimensions of the cable support line portion and the optical element portion is ± 10. If it is within%, cable manufacturability can be stabilized with almost no trouble.
[0011]
An optical fiber drop cable according to a second aspect of the present invention is the optical fiber drop cable according to the first aspect, wherein the sheath thickness in the width direction of the cable support line portion is 0.1 mm or more. is there.
[0012]
Therefore, the thinner the sheath thickness in the width direction of the cable support wire portion, the more advantageous the wind pressure load applied to the cable. However, the cable thickness and the sheath thickness can be improved by having the sheath thickness in the width direction of 0.1 mm or more. Reliability is ensured.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0014]
Referring to FIG. 1, an optical fiber drop cable 1 according to this embodiment includes a single optical fiber or an optical fiber ribbon (hereinafter collectively referred to as an optical fiber 5) in a sheath 3. From the embedded long optical element part 7 and the long cable support line part 11 fixed integrally continuously or intermittently via a neck part 9 constricted in parallel to the optical element part 7 It has an SSD structure.
[0015]
The optical element unit 7 includes, for example, at least a pair of long first strength members, eg, strength members 13 arranged in parallel on both sides of the optical fiber core 5. The optical fiber core wire 5 and the strength member 13 are covered with a cable sheath 3 of a thermoplastic resin such as polyethylene or polyvinyl chloride (PVC), so that a long optical element portion 7 is formed. In addition, as the said tensile body 13, the steel wire, FRP, a tensile fiber etc. as a metal wire are used, for example. Further, a notch portion 15 for tearing the cable is provided on the side surface of the cable sheath 3 in the vertical direction in FIG. 1 in order to take out the optical fiber core wire 5.
[0016]
In addition, the long cable support line portion 11 is configured by, for example, supporting wire 17 serving as a second strength member covered with a sheath 19 of thermoplastic resin. It is integrally connected via a neck portion 9 which is constricted in parallel. The support wire 17 is made of a metal wire such as a steel wire.
[0017]
The outer diameter of the sheath 19 of the cable support line portion 11 constituting the main part of the embodiment of the present invention is such that the height dimension HB in the direction perpendicular to the connecting direction of the optical element portion 7 and the cable support line portion 11 is the optical element. The dimensional difference with the height dimension HA of the portion 7 is within ± 10% , and the width dimension WB in the same direction as the connecting direction is smaller than the height dimension HB. As a result, the long diameter WC of the optical fiber drop cable 1, that is, the cable long diameter WC in the entire connecting direction of the optical element portion 7 and the cable support wire portion 11 (the width dimension WA of the optical element portion 7 + the width dimension WB of the cable support wire portion 11). ) Is reduced, the wind pressure load applied to the optical fiber drop cable 1 is reduced.
[0018]
Therefore, the sheath 19 of the cable support wire portion 11 has a thinner sheath thickness in the width direction (WB direction) than the sheath thickness in the height direction (HB direction), and the sheath thickness in the width direction (WB direction). The thinner the cable, the more advantageous the wind pressure load applied to the cable 1, but considering the cable manufacturability and the reliability of the sheath, the sheath thickness in the width direction (WB direction) is at least 0.1 mm. It is desirable that the degree is more than about.
[0019]
In addition, the fact that the above-described height dimensions HA and HB are exactly the same is best in terms of improving the state in which the cable 1 is wound around a bobbin or the like. It was confirmed that the dimensional difference between the dimensions HA and HB is almost no problem up to about ± 10%.
[0020]
By the way, in the optical fiber drop cable 1 of this embodiment, the support wire 17 is a 1.2 mmφ steel wire, and the optical fiber core wire 5 is 0.3 mm high × 1.1 mm wide four-core optical fiber tape core wire. The height HB of the cable support line 11 is 2.6 mm, the width WB is 1.8 mm, the height HA of the optical element 7 is 2.6 mm, and the width WA is 3. 8 mm.
[0021]
In order to compare with the optical fiber drop cable 1 of the above embodiment, a conventional optical fiber drop cable shown in FIG. 2 as a comparative example was manufactured as shown below.
[0022]
In the optical fiber drop cable of the comparative example, the members corresponding to the optical fiber core wire 5, the tensile body 13, and the support wire 17 are the same as those of the optical fiber drop cable 1 of the above-described embodiment, and the cable support wire portion is supported. A sheath is applied concentrically to the wire. That is, the height dimension HB and the width dimension WB of the cable support line portion are both 2.6 mm.
[0023]
When the side pressure characteristics, bending characteristics, and loss temperature characteristics of the above comparative example and the optical fiber drop cable 1 of this embodiment were evaluated, the same characteristics as any of the characteristics were obtained. Therefore, in the optical fiber drop cable 1 of this embodiment, the height dimension HB of the cable support line portion 11 is substantially the same as the height dimension HA of the optical element portion 7 without impairing various characteristics of the conventional cable. As a result, the winding state of the cable is good, and the long diameter WC of the optical fiber drop cable 1 is reduced, so that both reduction in wind pressure load in the installed state and stable cable manufacturability can be achieved.
[0024]
In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change.
[0025]
【The invention's effect】
As can be understood from the description of the embodiment of the invention as described above, according to the invention of claim 1, since the height dimension of the cable support line portion is substantially the same as the height dimension of the optical element portion, Winding pressure on the cable in the erected state is small because the cable length, which is the overall length in the connecting direction between the optical element part and the cable support line part, is small because the winding condition is good and the cable manufacturability can be stabilized. The weight can be reduced. Moreover, if the dimensional difference between the height dimension of the cable support line portion and the height dimension of the optical element portion is within ± 10%, the cable manufacturability for improving the condition in which the cable is wound around the bobbin or the like. In this respect, stability can be achieved with almost no hindrance.
[0026]
According to the invention of claim 2, the thinner the sheath thickness in the width direction of the cable support wire portion, the more advantageous the wind pressure load applied to the cable, but the sheath thickness in the width direction is 0.1 mm or more. This ensures cable manufacturability and reliability as a sheath.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an optical fiber drop cable according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a conventional optical fiber drop cable.
FIG. 3 is an explanatory diagram showing an implementation status of a conventional cable.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical fiber drop cable 3 Sheath 5 Optical fiber core wire 7 Optical element part 9 Neck part 11 Cable support line part 13 Strength body (1st strength body)
17 Support line (second tensile body)
19 Sheath HA Height dimension WA of optical element part 7 Width dimension H of optical element part 7 Height dimension WB of cable support line part 11 Width dimension WC of cable support line part 11 Long diameter of optical fiber drop cable 1

Claims (2)

A long optical element unit in which an optical fiber core and at least a pair of first tensile members disposed in parallel on both sides of the optical fiber are covered with a cable sheath, and a second tensile member are covered with the sheath. In the optical fiber drop cable formed by fixing the coated long cable support line part in parallel with each other,
Of the outer diameter of the sheath of the cable support line part, the height difference in the direction orthogonal to the connecting direction of the optical element part and the cable support line part is within ± 10% of the dimensional difference from the height dimension of the optical element part. The optical fiber drop cable is characterized in that the width dimension in the same direction as the connecting direction is smaller than the height dimension of the cable support line portion.   The optical fiber drop cable according to claim 1, wherein a sheath thickness in a width direction of the cable support line portion is 0.1 mm or more.

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