JP2004037970A - Optical fiber cable, and method for branching optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the reinforcing box of the entire cable is large-sized, expensive and hard to handle, an airtight sealing performance is lowered and reliability is lowered since a part to remove a jacket at the time of a branching construction becomes long for an optical fiber cable. <P>SOLUTION: The lengths of a plurality of tape core wires 11-1 to 11-5 housed inside a slot 13 are made shorter as they get closer to the jacket 10. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical fiber cable used for FTTH (Fiber To The Home) or the like.
[0002]
[Prior art]
In a spacer covered with the outer sheath of an optical fiber cable used in a conventional FTTH (Fiber To The Home) or the like, a groove called a slot is provided meandering in a direction perpendicular to the extending direction of the optical fiber cable. I have. A plurality of tape cores in which a plurality of optical fiber cores are bundled in parallel are stored in this slot. At the center of the cable, a metal wire called a tension member for supporting the tension of the optical fiber cable is arranged.
[0003]
When branching the optical fiber cable, first, the outer skin is cut off, the spacer is stripped, and the optical fiber core wire to be branched is taken out. Since the slot is meandering, the optical fiber core wire can be easily pulled out by exposing the spacer. Then, the taken-out optical fiber core wire is cut so that one end of the optical fiber core wire is pulled out.
[0004]
Next, the optical fiber core wire of the optical fiber cable to be connected is pulled out. Then, the two optical fiber core wires are connected using a connection device called a splicer. Further, the portion of the optical fiber cable where the outer sheath is cut off and the spacer is exposed and the connection portion between the two optical fibers are reinforced in a reinforcing box.
[0005]
The reinforcing box not only has a role of responding to an external force applied to the optical fiber cable, but also has a role of shielding the connected portion from the outside to suppress the effect of the optical fiber from the weather and the like.
[0006]
In a general splicer used for branching a cable, the optical fiber core wire needs to be pulled out by about 30 cm to 50 cm, and therefore, the outer sheath of the cable also needs to be removed by about 30 cm to 50 cm.
[0007]
[Problems to be solved by the invention]
In general, the reliability of quartz fiber strongly depends on moisture, and the reliability is significantly reduced in places with a lot of moisture. (1) The portion where the outer sheath of the cable is removed is long, the airtight sealing performance of the cable is poor, and moisture enters. There is a problem that it becomes easy to do.
[0008]
Further, the reinforcing box of the entire cable needs to be large enough to completely cover the portion from which the outer skin has been removed, so that the size of the reinforcing box is about 50 to 70 cm. Therefore, (2) there is a problem that the reinforcement box is expensive because of its large size, and that the work time for the construction is long.
[0009]
Further, among the optical fiber cores pulled out at the time of connection, the optical fiber core not used for connection is left unused without being utilized, and thus (3) there is a problem that there are many wasteful optical fiber cores.
[0010]
Among them, the problem (3) is disclosed in Japanese Patent Application Laid-Open No. H8-220389, in which a method is proposed in which a plurality of lengths of optical fiber core wires are accommodated in a cable to save the optical fiber core wires. However, in this method, since there is no proposal on how to accommodate the core wire and no reinforcement at the time of connection, the problems (1) and (2) remain unsolved.
[0011]
In other words, in the conventional optical fiber cable, the length of removing the outer sheath of the cable at the time of branching work becomes longer, so that the hermetic sealing performance of the cable is reduced and the optical fiber core wire is easily deteriorated, and the reliability of the cable is reduced. There was a problem of lowering.
[0012]
In addition, since the removed portion of the outer sheath of the cable is long, the reinforcing box that covers the vicinity of the branch point of the cable is large, expensive, and difficult to handle, so that the time, labor, and cost required for branching work become enormous. There was a problem.
[0013]
These problems are factors that make the branching of optical fiber cables difficult, and are also responsible for the last mile problem that is known as an obstacle to the spread of FTTH.
[0014]
Therefore, an object of the present invention is to provide an optical fiber cable that can easily perform branching work, and a method of branching the optical fiber cable.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, an optical fiber cable according to the present invention includes a spacer having a groove-shaped slot on its surface, a plurality of fiber cores accommodated in the slot, each having a different length, and the spacer and the fiber core. And the fiber core wire is housed in the slot such that the closer to the outer skin the shorter the length.
[0016]
Further, the optical fiber cable of the present invention may be characterized in that a mark indicating a position of the slot is marked on the outer sheath.
[0017]
Further, the optical fiber cable of the present invention may be characterized in that a mark for identifying a length of a fiber core wire accommodated in the slot is marked on the outer sheath.
[0018]
Further, in the optical fiber cable of the present invention, the spacer has at least a first slot and a second slot, and at least a combination of the lengths of a plurality of fiber core wires accommodated in the first slot is different. , May be different from the combination of lengths in the second slot.
[0019]
Further, the optical fiber cable of the present invention may be characterized in that a lubricant is applied to the surface of the fiber core wire.
[0020]
In the optical fiber cable according to the present invention, the slot may meander in a direction perpendicular to a direction in which the spacer extends.
[0021]
Further, the optical fiber cable of the present invention may be characterized in that the wall surface of the slot is uneven in a bellows shape.
[0022]
The method for branching an optical fiber according to the present invention includes the steps of sequentially cutting a part of the outer sheath of the optical fiber cable from a position near a starting point of laying the optical fiber cable of the present invention, and removing a plurality of fiber core wires accommodated in slots. The fiber core wire closest to the outer sheath is drawn out, connected to the branch optical fiber at the branch destination, and the connecting portion between the optical fiber cable and the branch fiber is reinforced by a reinforcing member.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0024]
(Structure of Optical Fiber Cable) FIG. 1 shows the structure of an optical fiber cable according to an embodiment of the present invention. The optical fiber cable 1 includes an outer sheath 10, a spacer 12 covered with the outer sheath 10, and made of resin or the like, and a tension member 14 made of metal such as iron or stainless steel at the center of the spacer 12.
[0025]
In the spacer 12, a slot 13 which is a groove for accommodating the fiber core wire is formed. In the slot 13, tape core wires 11-1, 11-2, 11-3, 11-4, and 11-5 in which a plurality of optical fiber core wires are bundled in parallel are accommodated as fiber core wires. The tape core is obtained by covering a plurality of optical fiber cores by arranging them on a flat surface. When the optical fiber core wires are bundled normally, the cross section becomes circular, but when the tape core wire is used, the cross section is flat, so that the connectivity is excellent, for example, by splicing all together.
[0026]
In the present embodiment, the fiber cores accommodated in each slot are assumed to be tape cores in which optical fiber cores are bundled in parallel.However, a plurality of optical fiber cores, or a plurality of optical fiber cores are used. A plurality of bundles may be stored.
[0027]
Although only one slot 13 is shown in FIG. 1 to simplify the description of the structure of the optical fiber cable 1 here, the optical fiber cable of this embodiment is the same as the optical fiber cable 1 of FIG. Thus, it is assumed that there are a plurality of slots 13 (slots 13-1, 13-2, 13-3, 13-4).
[0028]
The tape cores 11-1 to 11-5 are arranged such that the tape core 11-5 is disposed at the innermost side of the slot 13 (on the center side of the optical fiber cable 1), and the tape cores 11-4, 11-3, and 11-2. And the tape core wire 11-1 is disposed on the outermost side (on the outer sheath 10 side of the optical fiber cable 1). Further, the outermost tape core 11-1 is the shortest, and becomes longer as the tape cores 11-2 and 11-3 are formed. The innermost tape core 11-5 is the longest. However, since one end of each of the tape core wires 11-1 to 11-5 is required at the point where the laying of the optical fiber cable 1 is started (laying start point), one end of the optical fiber cable 1 (hereinafter referred to as a first end). Be prepared.
[0029]
The difference between the lengths of the tape core wires 11-1 to 11-5 is about 10 to 100 m. The difference in the length between the tape core wires changes depending on the place where the optical fiber cable 1 is used, and the closer the distance to the area where the frequency of branching the optical fiber cable 1 is expected to increase, such as a densely populated house, the closer to the area. It is better to reduce the difference.
[0030]
The material of the outer cover 10 is made of polyethylene in the present embodiment, but other commonly used vinyl chloride may be used. The outer sheath 10 encloses the entire optical fiber cable 1, and FIG. 1 shows a state in which the outer sheath 10 is cut off and the spacer 12 is stripped from the middle.
[0031]
A lubricant is applied to the surfaces of the tape core wires 11-1 to 11-5. This makes the tape cores 11-1 to 11-5 slippery, and makes it easier to pull out the tape core 11-1 during branching work.
[0032]
(Procedure of Branching Method) A procedure for branching the branch optical fiber cable 17 from the optical fiber cable 1 will be described with reference to FIG.
[0033]
The optical fiber cable 1 of the present embodiment has its first end laid at a laying start point such as a station or a base point, and is sequentially branched from a place near the laying start point. Here, the "station" refers to a station, such as a telephone station, a communication station, or a switching center, which is a starting point when communication is performed using an optical fiber cable.
[0034]
The outline of the branching work is as follows. The tape core wire 11 drawn from the optical fiber cable 1 is connected to the branch optical cable 17, and the connection portion and the surrounding optical fiber cable 1 and the branch optical cable are housed in the reinforcing box 22 to shield the connection portion from the outside. It is to do.
[0035]
In branching work, first, a part of the outer sheath 10 of the optical fiber cable 1 is cut out and a hole 16 is opened. As for the size of the hole 16, the width may be about the width of the slot 13-1, and the length may be about several cm. Then, the uppermost tape core wire 11-1 of the plurality of tape core wires accommodated in the slot 13-1 is pulled out from the hole 16, and the tape core wire 20 drawn from the branch optical fiber cable 17 and the splicer (the inside of the splice reinforcing portion 21). (Not shown), and the connection is reinforced by using the splice reinforcement 21. A heat-shrinkable tube is used for the splice reinforcement 21.
[0036]
Then, the optical fiber cable 1 and the branch optical fiber cable 17 are housed in the reinforcing box 22, and the tension member 18 of the branch fiber cable is fixed to the fixing portion 19 of the reinforcing box 22 with a screw or the like. Then, while being reinforced by the reinforcing box 22, the portion of the optical fiber cable 1 and the branch optical fiber cable 17 from which the outer sheath is removed is shielded from the outside to protect the portion from the weather. Although only one side is illustrated in the drawing, the reinforcing box 22 is of a type in which the optical fiber cable 1 and the branch optical fiber cable 17 are sandwiched between two boxes from above and below to shield them.
[0037]
By sealing the hole 16 and the exposed portion of the branch optical fiber cable 17 (particularly, the portion where the tape core wire 20 protrudes from the branch optical fiber cable 17) with resin, it is possible to further suppress the deterioration of the hermetic sealing performance. it can.
[0038]
According to the present embodiment, the portion where the outer skin 10 is to be removed is limited to a limited range of about the hole 16, so that the amount of outer skin that needs to be removed when branching can be reduced. Therefore, it is possible to suppress a decrease in the hermetic sealing performance of the optical fiber cable 1 due to the branching work, and to thereby suppress a decrease in the reliability of the optical fiber cable 1.
[0039]
Further, by reducing the amount of the outer skin to be removed, the size of the reinforcing box 22 can be reduced to a size that can accommodate the connection portion between the hole 16 and the branch optical fiber cable 17. Therefore, it is smaller and easier to handle than the conventional reinforcing box, and the labor, time and cost required for branching work can be reduced. In addition, since the size of the reinforcing box is reduced, the cost of the reinforcing box itself can be reduced.
[0040]
Here, the case where the tape core 11 of the optical fiber cable 1 is connected to the tape core 20 of the branch optical fiber cable 17 has been described as an example. That is, the connection between the tape cores has been described as an example, but the connection is also made in the same procedure in the connection between the optical fiber cores and the connection between the tape core and a plurality of optical fiber cores. Also, the number of branch optical fiber cables is not limited to one, and when branching to a plurality of branch optical fiber cables at the same time, branching is performed in the same procedure.
[0041]
(Modification of the structure of the optical fiber cable) By changing the combination of the lengths of the tape core wires accommodated in the slots 13-1, 13-2, 13-3 and 13-4 of the optical fiber cable 1 of FIG. Good to put.
[0042]
For example, slot 13-1 accommodates 500 m, 550 m, 600 m, 650 m, and 700 m long tape cores, and slot 13-2 accommodates 750 m, 800 m, 850 m, 900 m, and 950 m tape cores. If it does, it will be able to cover a wide range as a whole.
[0043]
Marks 15-1 and 15-2 are provided on the outer skin 10 corresponding to the positions where the slots are provided, so that the slots can be determined from the outside without removing the outer skin 10. , Workability can be improved.
[0044]
For example, the mark 15-1 which is a mark corresponding to the slot 13-1 is distinguished from a red triangle, and the mark 15-2 which is a mark corresponding to the slot 13-2 is distinguished from a blue circle by color or shape. By doing so, the slots can be easily identified, and the work efficiency can be improved. Alternatively, the length of the tape core wire accommodated in the slot at the position of the mark may be displayed in a list on the outer skin 10 in addition to the simple color coding.
[0045]
In order to improve the workability of the branching work, it is very useful to devise the optical fiber cable as shown in FIG. The optical fiber cable shown in FIG. 3A is provided with a plurality of grooves 23 extending across the wall surface of the slot 13, that is, in a direction perpendicular to the extending direction of the slot 13, as shown in FIG. When an optical fiber cable designed as shown in FIG. 3A is used, a jig 24 having a shape easily hooked with a fiber core wire as shown in FIG. 4 is inserted into the groove 23, and the tape core wire 11 is easily taken out. This makes it possible to improve the workability of branching work.
[0046]
Although the groove 23 is provided here, the width of the slot 13 is sufficiently larger than the width of the tape core wire 11, and a convex portion is provided instead of the groove 23 so as to cross the wall surface of the slot 13. Is also good. That is, if the wall surface of the slot 13 is uneven in the form of a bellows, whether it is the groove 23 or the convex portion, there is a gap between the wall surface of the slot 13 and the tape core wire 11 such that the jig 24 can pass through. good.
[0047]
Further, if the slot 13 is meandered in a direction perpendicular to the extending direction of the spacer 12 as shown in FIG. 5, a conventional reinforcing box can be used. For example, when branching work is performed for a new subscriber who has appeared during the operation of the system, the tape core near the outer skin in the slot may have already been used.
[0048]
In such a case, as shown in FIG. 6, the outer sheath 10 is removed by about 30 cm to 50 cm, the unused tape core wire accommodated in the slot 13 is pulled out, and connected to the tape core wire 20 of the branch optical fiber cable 17. What is necessary is just to shield the connection part from the external world using the reinforcing box 25.
[0049]
By using both reinforcing boxes in this way, it is possible to use the fiber core wire without waste.
[0050]
【The invention's effect】
As described above, according to the present invention, a plurality of fiber cores are accommodated in the slot, and the lengths of the plurality of fiber cores are shortened as the core wire is closer to the outer sheath, so that the optical fiber cable can be easily branched.
[Brief description of the drawings]
FIG. 1 is a structural diagram of an optical fiber cable according to an embodiment of the present invention.
FIG. 2 is a perspective view when branching work is performed using the optical fiber cable according to the embodiment of the present invention.
FIG. 3A is a structural view of an optical fiber cable according to an embodiment of the present invention.
(B) An enlarged view of a slot and a groove.
FIG. 4 is a diagram showing a state when branching work is performed using the optical fiber cable of FIG. 3;
FIG. 5 is a structural diagram of the optical fiber cable according to the embodiment of the present invention in which a slot is meandering.
FIG. 6 is a perspective view when branching work is performed using the optical fiber cable of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical fiber cable 10 Outer sheath 11 Tape core wire 12 Spacer 13 Slot 14 Tension member 15 Mark 16 Hole 17 Branch optical fiber cable 18 Tension member 19 Fixing part 20 Branch tape core wire 21 Strong member 22 Reinforcement box 23 Groove 24 Jig 25 Conventional reinforcement box

Claims (8)

A spacer having on the surface a groove-like slot extending in the stretching direction,
A plurality of fiber core wires accommodated in the slot and having different lengths,
Having an outer cover for covering the spacer and the fiber core wire,
The fiber core,
An optical fiber cable which is housed in the slot such that a cable closer to the outer cover has a shorter length. In the outer skin,
2. The optical fiber cable according to claim 1, wherein a mark indicating the position of the slot is marked. In the outer skin,
3. The optical fiber cable according to claim 1, further comprising a mark for identifying a length of the fiber core wire accommodated in the slot. The slot has at least a first slot and a second slot,
4. The light according to claim 1, wherein a combination of lengths of the plurality of fiber core wires accommodated in the first slot is different from a combination of lengths in the second slot at least. Fiber cable. The optical fiber cable according to claim 1, wherein a lubricant is applied to a surface of the fiber core wire. The optical fiber cable according to claim 1, wherein the slot is meandering in a direction perpendicular to a direction in which the spacer extends. The optical fiber cable according to claim 1, wherein a wall surface of the slot has a corrugated shape. The method of branching an optical fiber cable according to claim 1, wherein a part of an outer sheath of the optical fiber cable is cut off sequentially from a position near a starting point of laying the optical fiber cable,
Of the plurality of fiber cores accommodated in the slot, pull out the fiber core closest to the outer skin and connect it to the branch optical fiber at the branch destination,
A method for branching an optical fiber, wherein a connecting portion between the optical fiber cable and the branch fiber is reinforced by a reinforcing member.

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