JPH08262288A - Aerial optical cable - Google Patents

Abstract

PURPOSE: To provide an aerial optical cable which allows the easy conduction of a branching and dropping operation from an aerial optical cable and necessitates a smaller branching part. CONSTITUTION: A central member 2 is circumferentially inscribed with S-twist slots 3 into which a small number of optical fiber cables 1 are respectively removably mounted. Each optical fiber cable 1 has a cylindrical metallic pipe 6 in a sheath 5 and has one or two coated optical fibers 7 in the space of the metallic pipe 6. The sectional shape of the S-twist slots 3 is approximately U-shaped. Plural number of optical fiber cables 1 are strongly pressed in the central direction of the central member 2 when the aerial optical cable is installed. The optical fiber cables 1 to be branched are cut at the point of the place extended a prescribed distance from a branching point at the time of branching and dropping the cables. The cables are then pulled apart from the slots 3, are taken out to the branch point, are fixed by fixing parts and are used as they are as outdoor optical cables.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead optical cable having a plurality of minority optical cables.

[0002]

2. Description of the Related Art Conventionally, when a few-core optical cable containing one or two optical fibers is branched and dropped from an overhead optical cable, the jacket of the overhead optical cable is peeled off, and a small number of a plurality of optical fibers contained inside the overhead optical cable are removed. I took out what should be branched from the optical fiber cable, cut it, and connected it to the branch optical fiber cable. However, the complicated work of attaching the branch box to the branch section is required, and there are problems that the branch box and the branch work are too expensive, and the branch section becomes large.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an overhead optical cable which can easily perform branching and dropping work from an overhead optical cable and which requires a small branch portion. It is intended to be provided.

[0004]

According to a first aspect of the present invention, in an aerial optical cable, a plurality of minority-core optical cables and a central member are provided, and the minority-core optical cables have tensile strength members. It is characterized in that it is attached to the outer periphery of the central member so as to be individually and independently removable.

According to a second aspect of the present invention, in the aerial optical cable according to the first aspect, the central member has a plurality of slots, and each of the plurality of minority optical cables has a part in the slot. It is characterized in that it is fitted.

According to a third aspect of the present invention, in the aerial optical cable according to the first or second aspect, a fixing portion is provided, and the fixing portion has a low strength, and the central member is provided with the fixing portion. It is characterized by fixing the minority optical cable.

[0007]

According to the invention described in claim 1, since the minority optical fiber cable has a tensile strength member and is attached to the outer periphery of the central member so as to be individually and independently removable, the minority optical fiber cable is taken out. Will be easier.

According to the invention of claim 2, claim 1
In the aerial optical cable described in (1), since the central member has a plurality of slots and a part of each of the plurality of minority optical cables is fitted into the slot, the structure for mounting the minority optical cable to the central member can be simplified. Become.

According to the invention of claim 3, claim 1
Alternatively, the aerial optical cable according to claim 2 has a fixing portion, and the fixing portion has a low strength and fixes the minority optical cable to the central member, so that the aerial optical cable is wound on a drum. In some cases, the minority optical cable is less likely to come off the slot.

[0010]

1 is an explanatory view for explaining a first embodiment of the present invention, FIG. 1 (A) is a perspective view of an overhead optical cable, and FIG. 1 (B) is a sectional view of a minority optical cable. . 1 is a minority optical cable, 2 is a central member, 3 is an S twist slot,
Reference numeral 4 is a support wire, 5 is a sheath, 6 is a metal tube, and 7 is an optical fiber core wire. In this overhead optical cable,
As shown in (A), a plurality of, for example, eight S twist slots 3 are provided on the outer peripheral surface of one central member 2 having a circular cross section.
Is engraved, and a part of the minority optical cable 1 is fitted into each S twisted slot 3 and individually attached so as to be taken out independently. The other part of the minority optical cable 1 slightly projects from the outer peripheral surface of the central member 2 and is exposed at the outer periphery of the central member 2. No coating is provided to cover the minority optical cable 1 and the central member 2. At the center of the central member 2, there is a support wire 4 made up of one or more tensile strength wires.

As shown in FIG. 1B, the minority optical cable 1 has a circular cross section, has a cylindrical metal tube 6 in a sheath 5, and has an optical fiber in the space of the metal tube 6. It has one or two fiber core wires 7. The metal tube 6 has high lateral pressure resistance and also functions as a tensile strength member. Therefore, the minority optical fiber cable 1 is one in which the strength member and the optical fiber core wire 5 are integrated.

Returning to FIG. 1 (A) again, the S-twisted slot 3 has a cross-sectional shape that is rounded at the bottom of the slot and has a substantially U-shape in which the inner wall surface rises vertically. , Shorter than the diameter of the minority optical cable 1. When the overhead optical cable is in a tension-free state, the minority optical cable 1
Is loosely wrapped around the S twist slot 3. Since the S twist slot 3 is carved in one direction, the minority optical cable 1 housed in the slot 3 is twisted around the center member 2. When the overhead optical cable is bridged, the minority optical cable 1 is strongly pressed toward the center of the center member 2 due to the bridge tension. Therefore, in the crossover state, the minority optical cable 1 does not jump out from the slot 3. Since the minority optical fiber cable 1 has the metal tube 6 having high lateral pressure resistance, even if it is strongly pressed, the metal tube 6 is
There is no adverse effect on the optical fiber core wire 5 inside.

At the time of branching and withdrawing, a minority optical fiber cable to be branched is selected from the overhead optical cables at a point extended by a predetermined distance from the branching point, this is cut, and this is cut from the slot 3 to the branching point. The part is taken out, and at a branch point, a branch fixing part described later with reference to FIG. The minority optical cable 1 is a part of which is fitted into the slot 3 and is slightly protruded from the slot 3 and exposed from the outer periphery of the center member 2, so that it can be easily cut. Since the tightening tension on the central member 2 is loosened by cutting, the minority optical cable to be branched can be easily taken out from the slot 3. The extracted minority optical fiber cable has the metal tube 6 as a strength member, and thus can be used as it is as an outdoor optical cable. Therefore, it is not necessary to attach a branch box to the branch portion, and the branch work is easy.

A specific example of this embodiment will be shown. The sheath 5 of the minority optical fiber cable 1 is polyethylene and has an outer diameter of 3 m.
m. The metal tube 6 is a so-called SUS tube which is a kind of stainless steel, and has an inner diameter of 0.9 mm and an outer diameter of 1.2 m.
m. The optical fiber core wire is a UV (ultraviolet curable resin coated) optical fiber core wire and has a diameter of 0.25 mm. The central member 2 has weather resistance, for example,
It is black polyethylene.

2A and 2B are explanatory views for explaining a second embodiment of the present invention. FIG. 2A is a perspective view of an overhead optical cable and FIG. 2B is a sectional view of a minority optical cable. . In the figure, 11 is a minority optical fiber cable, 12 is a central member, 13
Is an S twist slot, 14 is a support wire, 15 is a sheath, 15
a is an optical fiber core side sheath, 15b is a tensile strength body side sheath, 16 is a tensile strength body, and 17 is an optical fiber core wire. As shown in FIG. 2 (A), in this overhead optical cable, a plurality of, for example, four S twist slots 13 are engraved on the outer peripheral surface of one central member 12 having a circular cross section. Minority optical cable 11 in each slot 13
Is partially inserted, and the minority optical cables 11 are individually and detachably attached. The other part of the minority optical cable 11 is exposed on the outer periphery of the central member 2. No coating is provided to cover the minority optical cable 1 and the central member 2. At the center of the central member 2, there is a support wire 4 made up of one or more tensile strength wires.

As shown in FIG. 2B, in this minority optical cable 11, a sheath 15 is composed of a portion on the optical fiber core side and a portion on the tensile strength body side, which are joined together. The wire-side sheath 15a has a substantially circular cross section. The tensile strength body side sheath 15b is smaller than the optical fiber core side sheath 15a and is a portion fitted into the S twist slot 13, and the shape of this cross section substantially corresponds to the shape of the cross section of the S twist slot 13. The optical fiber core side sheath 15a has a space inside and accommodates one or two optical fiber cores 17. Tensile body side sheath 1
A tensile strength member 16 is provided at 5b. Therefore, the minority optical cable 11 is also one in which the strength member and the optical fiber core wire 5 are integrated.

Returning to FIG. 2A again, the S-twisted slot 13 has a substantially U-shaped cross section similar to that of the first embodiment, and the S-twisted slot 3 is provided with a minority optical fiber cable. Eleven tensile strength member side sheaths 15b are stored.
Therefore, in the minority optical cable 1, the optical fiber core side sheath 15a projects from the outer peripheral surface of the central member 12.
As in the first embodiment, the minority optical cable 11 is loosely wound around the S-twisted slot 13 when the overhead optical cable is in a tension-free state, and does not jump out from the S-twisted slot 3 in the crossed state. The minority optical fiber cable 11 has an optical fiber core wire side sheath 15a.
Is attached with a degree of freedom, so that the optical fiber core wire 17 will not be adversely affected even if it is strongly pressed toward the center of the center member 12. The method of branching and withdrawing is the same as in the first embodiment.

A specific example of this embodiment will be shown. The sheath 15 of the minority optical cable 11 is black PVC (polyvinyl chloride), and the outer diameter of the optical fiber core side sheath 15a is 4
mm, the inner diameter of the space portion is 2 mm, and the lateral width of the tensile strength body side sheath 15b is 1.2 mm. The strength member is a piano wire having an outer diameter of 0.7 mm. Optical fiber core 17
Are a pair of UV (ultraviolet ray curable resin coated) optical fiber core wires and have a diameter of 0.25 mm. Center member 12
Is weather resistant, for example, black polyethylene.

FIG. 3 is an explanatory view for explaining a third embodiment of the present invention. FIG. 3 (A) is a perspective view of an overhead optical cable, and FIG. 3 (B) is a sectional view of a minority optical cable. Three
(C) is sectional drawing explaining the modification of a center member.
In the figure, 21 is a minority optical fiber cable, 22 is a central member, 2
3 is a straight slot, 24 is a support wire, 25 is a sheath, 25a is an optical fiber core side sheath, 25b is a tensile strength body side sheath, 25c is a neck sheath, 26 is a tensile strength body, 2
Reference numeral 7 is an optical fiber core wire, 28 is a central member, 28a is a central member main body portion, 28b is a central member supporting wire portion, and 28c is a central member neck portion.

As shown in FIG. 3A, in this overhead optical cable, one central member 2 having a circular cross section is used.
A plurality of, for example, four straight slots 23 are engraved on the outer peripheral surface of 2, and the tensile strength body side sheath 25b which is a part of the minority optical cable 21 is fitted into each of the straight slots 23, and the minority optical cables 21 are individually It is attached so that it can be taken out independently. The other part of the minority optical cable 21 is exposed at the outer periphery of the central member 22. No covering is provided to cover the minority optical cable 21 and the central member 22. At the center of the central member 22, there is a support wire 24 composed of one or more tensile strength wires.

As shown in FIG. 3B, in the minority optical cable 21, the sheath 25 is composed of an optical fiber core side sheath 25a and a tensile strength body side sheath 25b connected by a narrow neck sheath 25c. The optical fiber core side sheath 25a has a substantially circular cross section. The tensile strength body side sheath 15b also has a substantially circular cross section, but has an outer diameter smaller than that of the optical fiber core side sheath 25a and is fitted into the straight slot 13. The optical fiber core side sheath 25a has a space inside, and accommodates one or two optical fiber cores 27. Tensile body side sheath 2
5b has a tensile strength member 26. Therefore, the minority optical fiber cable 21 also has the strength member 26 and the optical fiber core wire 27.
Are integrated. The shape may be such that the optical fiber core side sheath 25a and the tensile strength body side sheath 25b are directly coupled without forming the neck sheath 25c. The optical fiber core side sheath 25a is made larger than the strength member side sheath 25b so as to improve the utilization efficiency of the space around the central member 22.

Returning to FIG. 3A again, the shape of the cross section of the straight slot 23 is different from that of the first embodiment.
It has a substantially circular shape, and has a shape in which, on the outer peripheral surface of the central member 22, this circular portion forms a central angle and is less than 180 ° at most. In this straight slot 23, the tensile strength side sheath 25b of the minority optical cable 21 is inserted.
The optical fiber core side sheath 25a and the neck sheath 25c, depending on the design, the tensile strength body side sheath 25
The vicinity of the neck portion of b is also exposed on the outer peripheral surface of the central member 22.
Since the straight slot 23 is a straight slot, the minority optical cable 21 is easily detached from the straight slot 23 even in the crossing state. However, since the cross-sectional shape of the slot 23 is as described above, the minority optical fiber cable 21 is engaged by the portion near the outer peripheral surface of the straight slot 23 and does not come off from the straight slot 23 unless force is applied. Has been

As a modified example of the central member, the one shown in FIG. 3C may be used. This central member 28
Has a central member main body 28a substantially similar to the central member 22 shown in FIG.
A center member support wire portion 28b having a circular cross section is connected to a through a narrow center member neck portion 28c. That is, the strength member 24 is not provided in the central portion of the central member 28, but is provided in the central member support wire portion 28b. In the case of FIG. 3C, the number of straight slots 23 is reduced by one from that of FIG. 3A, and the center member neck portion 28c is provided. However, the center member neck portion 28 is formed between the adjacent straight slots 23 in FIG.
c may be provided. Further, the strength member 24 may be left in the center of the center member 28.

This embodiment is simple to manufacture,
When branching and dropping is performed in the same manner as in the first embodiment, the minority optical cable 21 can be smoothly detached from the straight slot 23 simply by pulling the cut minority optical cable 21 from the ground, so that branch and pulling work can be performed. It will be easier.

A specific example of this embodiment will be shown. The sheath 25 of the minority optical cable 21 is black PVL (polyvinyl chloride), and the outer diameter of the optical fiber core side sheath 15a is 4
mm, the inner diameter of the space is 2 mm, and the outer diameter of the tensile strength body side sheath 15b is 1.2 mm. The strength member is a piano wire having an outer diameter of 0.7 mm. Optical fiber core 17
Is a UV (ultraviolet curable resin coated) optical fiber core wire and has a diameter of 0.25 mm. The center member 12 has weather resistance, for example, black PE (polyethylene).

FIG. 4 is a perspective view for explaining a modification of the third embodiment of the present invention. In the figure, the same parts as those in FIG. 32 is a central member, 33
Is an SZ twist slot. In this aerial optical cable, a plurality of, for example, four SZ twist slots 33 are engraved on the outer peripheral surface of one center member 32 having a circular cross section, and each SZ twist slot 33 is shown in FIG. 3 (B). The tensile strength body-side sheath 25b of the minority optical cable 21 similar to the one described above is fitted, and the minority optical cables 21 are individually and detachably attached. The other part of the minority optical cable 21 is exposed at the outer periphery of the central member 22. No coating is provided to cover the minority optical cable 1 and the central member 2. At the center of the central member 22, there is a support wire 24 composed of one or more tensile strength wires. The cross-sectional shape of the SZ twist slot 23 is
It is similar to the third embodiment.

In the SZ twist slot 23, the twist direction periodically changes to S twist or Z twist. Therefore, the minority optical cable 21 is easily disengaged from the SZ twisted slot 33 even in the crossing state. However, SZ twist slot 3
Since the cross-sectional shape of 3 is similar to that of the third embodiment, the minority optical cable 21 is engaged with the SZ twisted slot 33 regardless of whether the overhead optical cable is in the tension-free state or the crossover state. , It is designed so that it will not come off unless force is applied. The specific example of this embodiment and the branch withdrawal method are the same as those in the second embodiment. Also,
With respect to the center point of the center member 32, the minority optical cable 21
Since the optical fiber core wire 27 of FIG. 2 passes through the outer periphery of the strength member 26, it is easy to secure the extra length of the optical fiber core wire 27.

The third embodiment shown in FIG. 3 and the modification of the third embodiment shown in FIG. 4 are the embodiments in which the straight slot or the SZ twisted slot in which the minority optical cable is easily detached is used. there were. However, the slot may be the S twist slot used in the first and second embodiments.

FIG. 5 is an explanatory view for explaining a measure for making the minority optical cable hard to come off in each embodiment. In the figure, the same parts as those in FIG. 41 is an adhesive layer. The embodiments described above, in particular the first,
In the second embodiment, the minority optical cable may come out of the slot when the overhead optical cable is wound on a drum. In such a case, measures are taken to prevent the minority optical cable from coming off the slot. The second embodiment will be described on the premise, but the same can be applied to other embodiments.

An adhesive layer 41 is provided on the inner surface of the slot 13 of the central member 12, and the tensile strength body side sheath 15b of the minority optical fiber cable 11 is fitted therein.
Are fixed to the slot 13 by the adhesive layer 41. The adhesive layer 41 may be provided on the surface of the tensile strength member side sheath 15b, or may be provided on both surfaces. The adhesive force of the adhesive layer 41 is weakened in advance so that it can be taken out from the slot 13 after the minority optical cable 11 is cut at the time of branching and withdrawing. Specifically, for example, low-strength PVC (polyvinyl chloride) is used, and in this heating and melting state, the tensile strength body side sheath 15b is attached to the slot 13.

FIG. 6 is an explanatory view for explaining another measure for making the minority optical cable hard to come off. In the figure, the same parts as those in FIG. 51 is a wire. The second embodiment will be described on the premise, but the same can be applied to other embodiments. In the overhead optical cable of the second embodiment shown in FIG. 2, the wire 51 is wound in the Z twist direction opposite to the S twist of the slot. Minority optical fiber cable 1 at the time of branch withdrawal
When this wire 51 is cut together with 1, the minority optical cable 11 can be taken out from the slot 13. Note that the wire 51 once cut after the completion of the withdrawal work
May be reconnected at a disconnection or another wire may be wound, but if there is no risk of the minority optical cable 11 jumping out of the slot 13 during the crossing, the wire 51 may be removed thereafter. . The wire 51 needs to be easily cut, but specifically, for example, a lashing wire which is a nylon-coated steel wire is used.

FIG. 7 is an explanatory view for explaining a branch portion when the overhead optical cable of the present invention is branched and pulled down. In the figure, the same parts as those in FIG. Reference numeral 11a is a minority optical cable for branching and dropping, 61 is a branch fixing part, and 61a is a through hole. Second
However, the present invention can be similarly applied to other embodiments. A branch fixing part 61 is used for the branch part. The branch fixing component 61 is a substantially cylindrical member having a notch (not shown), and the notch is first pushed open to surround the aerial optical cable for one round. The optical cable may be formed in a band shape so as to be fastened, or a circular member may be formed by cutting one or two or more places, and the flange provided on the cut portion may be fixed to surround the optical cable. The branch fixing part 61 is provided with a through hole 61a. The through hole 61a is formed so as to be cut out in a U shape, but the through hole may not necessarily be provided. By using such a branch fixing component 61, it is possible to prevent the minority optical cable 11a branched from the slot 13 of the branch portion from coming off.

FIG. 8 is an explanatory view for explaining a work method for branching down the overhead optical cable of the present invention. In the figure,
Reference numeral 71 is an overhead optical cable, 72 and 73 are overhead equipment, 74 is a subscriber's house, and 75 is a minority optical cable. The aerial optical cable 71 is extended to aerial equipment 72, 73 such as a utility pole. In FIG. 8A, first, the minority optical cable to be branched and dropped to the subscriber's house 74 is identified. It is assumed that the optical fiber core wire in the minority optical fiber cable is connected to a communication equipment center such as an exchange on the side of the overhead equipment 72.

The branch point is A, and the distance from the branch point A to the subscriber's home 74 is L. A point downstream from the branch point A by a distance L + α on the side of the overhead equipment 73 is designated as B, and at this point B, the minority optical fiber cable 7 to be branched and dropped
5 is cut out, taken out from the slot of the center member, pulled out to the branch point A, passed through the through hole 61a of the branch fixing part 61 shown in FIG. 7, and dropped to the subscriber's house 74. Note that α is an extra length for connection and the like at the subscriber's home 74.

Since the overhead optical cable of the present invention is not covered with a coating, the minority optical cable 75 to be branched and drawn can be pulled out from the slot by a predetermined length, and the minority optical cable 75 has a tensile strength member. Therefore, it can be used as it is as a drop line.

At each subscriber's home 74, a minority optical fiber cable 7
One of the optical fibers 5 is withdrawn, and one or two optical fiber core wires are supplied. Alternatively, all the minority optical cables 75 may be collectively branched from the branch point A, and one minority optical cable 75 may be supplied to each of a plurality of subscriber homes. The branch and withdrawal work can be performed after the aerial optical cable is crossed, but can also be performed before the crossover.

In each of the embodiments described above, for example, FIG.
Although the center member 2 has a circular cross section in (A), it may have any shape such as an ellipse or a rectangle. In the case of a circular shape, the minority optical cable 1 to be arranged on the outer circumference of the central member 2
The number of can be increased. Further, a plurality of center members 2 each having a circular cross section, which serve as a unit, may be provided, and the center members 2 may be connected to each other by a connecting portion.

In each of the embodiments described above, for example, FIG.
In FIG. 2B, the optical fiber core wire 7 is housed in the space inside the metal tube 6, and in FIG. 2B, the optical fiber core wire 17 is housed in the space inside the sheath 15. . It is desirable to store the optical fiber core wire in the space with an extra length so that the optical fiber core wire does not extend even if the minority optical cable is stretched under tension in the longitudinal direction. The space may also be filled with a filling material, for example yarn, jelly-like material.

[0039]

As is apparent from the above description, according to the present invention, the work of branching and dropping from an overhead optical cable is easy, the branch box and the work for branching are inexpensive, and the branching portion is small. It has the effect of ending.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a first embodiment of the present invention, FIG. 1 (A) is a perspective view of an overhead optical cable, and FIG. 1 (B).
FIG. 4 is a cross-sectional view of a minority optical cable.

FIG. 2 is an explanatory view for explaining a second embodiment of the present invention, FIG. 2 (A) is a perspective view of an overhead optical cable, and FIG.
(B) is a cross-sectional view of the minority optical cable.

FIG. 3 is an explanatory view illustrating a third embodiment of the present invention, FIG. 3 (A) is a perspective view of an overhead optical cable, and FIG.
FIG. 3B is a cross-sectional view of the minority optical cable, and FIG. 3C is a cross-sectional view illustrating a modified example of the central member.

FIG. 4 is a perspective view illustrating a modification of the third embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a measure for making the minority optical cable hard to come off in each embodiment.

FIG. 6 is an explanatory diagram for explaining another measure for making the minority optical cable hard to come off.

FIG. 7 is an explanatory view for explaining a branching portion when the overhead optical cable of the present invention is branched and pulled down.

FIG. 8 is an explanatory view illustrating a work method for branching down the overhead optical cable of the present invention.

[Explanation of symbols]

1, 11, 21, 75 ... Minority optical fiber cable, 2, 12,
22, 28, 32 ... Central member, 3, 13 ... S twist slot, 4, 14, 24 ... Support wire, 5, 15, 25 ... Sheath, 6 ... Metal tube, 7, 17, 27 ... Optical fiber core wire, 1
6, 26 ... Strength member, 23 ... Straight slot, 33
... SZ twist slot, 41 ... Adhesive layer, 51 ... Wire, 6
1 ... Branch fixing parts, 71 ... Aerial optical cable, 72, 73
… Fictitious equipment, 74… Subscriber's house.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shigeru Tanaka 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Kazuo Hokari 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corp. (72) Inventor Osamu Kawada 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corp.

Claims (3)

[Claims] 1. A plurality of minority-core optical cables and a center member, wherein the minority-core optical cable has a tensile strength member and is attached to the outer periphery of the center member so as to be individually and independently removable. An aerial optical cable characterized by that. 2. The aerial optical cable according to claim 1, wherein the central member has a plurality of slots, and each of the plurality of minority optical cables is one part of which is fitted into the slot. . 3. The fixing member according to claim 1 or 2, wherein the fixing member has a low strength and fixes the minority optical fiber cable to the central member. The aerial optical cable described.