JP3602478B2 - How to extend the lower part of the optical cable - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lower extended working methods and closure to use it after mid-span of the optical cable.
[0002]
[Prior art]
If wiring to new subscribers becomes necessary in an area where optical fiber trunks have been laid, work to connect a drop optical fiber, etc., to the trunk optical cable for branch wiring in the middle of the optical cable trunk is performed. Is
This method is called the intermediate branching method, and is performed, for example, in the following procedure.
{Circle around (1)} The sheath of a portion of the trunk optical cable which requires branching is stripped for a predetermined length.
{Circle around (2)} A predetermined coated optical fiber branched from the stripped portion of the main optical cable is pulled out, and the drawn coated optical fiber is cut near the center.
{Circle around (3)} The drop optical fiber having the predetermined length and the outer sheath peeled off and exposing the tension member and the coated optical fiber is drawn into the closure from the tip thereof, and the tension member of the drop optical fiber is inserted into the predetermined inside the closure. To the position. (To protect the fusion spliced part of optical fiber from external force)
{Circle around (4)} One end of the coated optical fiber on one side cut out near the center and one end of the coated optical fiber of the drop optical fiber are fusion-spliced.
(The fusion splicing is performed by exposing the ends of the two coated optical fibers to be connected to expose the optical fiber core.)
{Circle around (5)} A portion of the trunk optical cable in which the sheath has been peeled off, a portion of the cut coated optical fiber which is not connected to the drop optical fiber on one side, and the fusion spliced portion, and the fusion spliced portion Each of them is mounted inside the closure to protect each of the drop optical fibers leading to.
[0003]
In the operation (4), that is, the fusion splicing, the coated optical fiber needs to be at least 20 cm in length from the time of peeling the sheath of the optical cable to the fusion machine. Further, if the connection operation is failed once and the connection operation is restarted, a loss of the coated optical fiber having a length of 3.5 cm occurs. Therefore, for example, when the sheath stripping length is 50 cm and the coated optical fiber is cut in the vicinity of the center, the length of one side is 25 cm, the extra length for re-connection is 5 cm, and the length of the connection operation is 5 cm. You can only start over once.
[0004]
[Problems to be solved by the invention]
Recently, the frequency of subscriber changes has increased, and despite the premature branching method, branch wiring became unnecessary due to cancellation of subscriber contracts, etc. The frequency of the operation of reconnecting the optical fiber from which the branch wiring has been cut off to the optical fiber of the original trunk line (referred to as lowering work) has been increasing.
By the way, the locations where the branch wirings are taken out are not predetermined, and the main optical cable cannot have an extra length for the branch wiring connection work at each location where the branch wirings are taken out. .
For this reason, it is usually difficult to take a sufficient extra length in connection work using branch wiring. And if the extra length is small, it is very difficult to carry out the work of extending the lower part.
[0005]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a work method of a lower extension that can be made easier after an intermediate rear branch in consideration of facilitating the operation of a lower extension, and a closure used therefor. In the middle post-branch method, the length of the stripping of the sheath of the optical cable should be increased, the extra length should be taken in the drop optical fiber for branching, and In the work, to remove the drop optical fiber, cut the coated optical fiber near the stripped end of the drop optical fiber instead of cutting the fusion spliced part of the optical fiber at the middle rear branch. A cable having a sleeve long enough to accommodate the stripped portion of the sheath of the optical cable with the stripped length of the sheath removed. The jars and main features.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, the intermediate post-branch is implemented, for example, as follows.
In FIG. 1 (A), the length of the stripped portion 13 of the sheath of the optical cable is set to be longer than the conventional 50 cm, 75 cm, and the branched coated optical fiber is taken out and cut near the center thereof. The length of the coated optical fiber taken out and cut is 37.5 cm on both the local side 14 and the other loop side 15.
In this case, there is an extra length of 17.5 cm compared to the minimum required of 20 cm for the fusion splicing operation, so that there is a margin.
The longer the stripping length of the sheath of the optical cable, the longer the length of the sheathed optical fiber can be obtained in the fusion splicing work as the length is increased.However, after the fusion work, in order to accommodate the stripped portion of the sheath of the optical cable. In addition, the length of the closure sleeve also needs to be increased.
It is possible to increase the length of the closure sleeve to some extent, but there is also a manufacturing problem, and in practice, the upper limit seems to be about 120 cm.
[0007]
In addition to increasing the stripping length of the sheath of the optical cable, if the extra length is taken for the drop optical fiber for branching, more room can be provided. The main optical cable has already been laid, and it is difficult to take extra length. However, since the drop optical fiber for branching has a relatively high degree of freedom, it is easy to take extra length of 50 cm or more, for example.
In FIG. 1 (B), the coated optical fiber 14 connected to the office and the coated optical fiber 18 from the drop optical fiber 17 are fusion spliced at 16 locations with the coated optical fiber from the main optical cable. After that, the extra length of the dropped optical fiber is rounded into a ring shape, and the extra length portion 18, the fusion spliced portion 19 of the optical fiber, and the portion 13 of which the sheath of the optical cable is peeled are mounted in the closure. In addition, the side 15 which is a coated optical fiber from the main optical cable and which is not spliced and is connected to another loop is also mounted in the closure.
[0008]
As the closure, a closure as shown in FIG. 2 can be used.
That is, the tubular sleeve 1 has a structure in which a hinge 12 is provided at an upper part, a lower engaging part 6 is removed, and the sleeve is divided into two parts in a vertical direction, so that the hinge 12 can be opened. ing. There are end plates 5 at both ends, and the end plate 5 is provided with a hole 10 for passing a trunk optical cable and a hole 11 for passing a drop optical fiber. When attaching the main optical cable 8 to the closure, the sheath of the unstripped portion of the optical cable is gripped, and the optical cable 8 is fixed to the closure by being sandwiched by the cable grip 7 fixed to the inner wall of the sleeve 1.
In the case where the sheath length of the sheath of the optical cable is 75 cm, the length L of the closure sleeve is required to be 80 cm or more in consideration of the margin.
The fusion spliced portion of the optical fiber is accommodated in a tray 3 provided in the closure. In addition, the entire closure is gripped by the support bar 4 with a clip and fixed to an overhead wire suspension line (not shown).
[0009]
By performing the intermediate post-branching as described above, when the branch wiring becomes unnecessary, the lower extension operation can be easily performed by, for example, the following procedure.
{Circle around (1)} A portion where the sheath of the optical cable mounted in the closure is stripped, the extra length portion of the drop optical fiber, a portion where the jacket of the drop optical fiber is stripped, and a fusion splicing portion of the optical fiber Each of the cut coated optical fibers on the other side is taken out of the closure.
{Circle around (2)} The fusion spliced portion of the optical fiber core is not cut, but the coated optical fiber is cut near the peeled end of the drop optical fiber (near 19 in FIG. 1B), and the drop optical fiber is removed.
{Circle around (3)} The coated optical fiber taken out from the trunk optical cable, the other end cut off at the time of the middle rear branch and connected to another loop (15 in FIG. 1), and the fusion spliced portion. The end portion of the coated optical fiber is fusion-spliced.
{Circle around (4)} The part where the sheath of the optical cable is peeled, the extra length part of the drop optical fiber, the fusion splicing part, and the newly fusion spliced part are respectively mounted in the closure.
[0010]
In the case where the stripped length of the sheath of the optical cable is 75 cm, the length of the coated optical fiber taken out of the optical cable, the other side cut at the time of the middle rear branch and connected to the other loop is 37 as described above. Although it is 0.5 cm, a sufficient length is provided on the side of the drop optical fiber, and that part is also mounted in the closure, so that it can be taken out and extended and used. At the time of work, a sufficient length can be taken, and work can be facilitated.
[0011]
【The invention's effect】
As described above, if the intermediate post-branching method of the present invention is carried out, the branch wiring becomes unnecessary, and this work can be performed very easily when performing the lower extension work.
[Brief description of the drawings]
FIG. 1 is a schematic view conceptually showing a procedure of an intermediate rear branching method which is a premise of the present invention.
FIG. 2 shows an example of an intermediate rear branch obtained by the intermediate rear branch method which is a premise of the present invention. (A) is a side vertical cross-sectional view, (B) is a plan vertical cross-sectional view, and (C) is a view of the closure viewed from the direction of C1-C2 in (A).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sleeve 2 Frame 3 Tray 4 Support rod 5 End plate 6 Engaging part 7 Cable gripper 8 Optical cable 9 Stripping portion of optical cable sheath 10 Hole for optical cable 11 Hole for drop optical fiber 12 Hinge 13 Skin of optical cable sheath Stripped part 14 Coated optical fiber (station side)
15 Coated optical fiber (other loop side)
16 fusion splicing point 17 drop optical fiber 18 stripped portion of drop optical fiber jacket 19 drop optical fiber stripped end

Claims (1)

When the branch wiring branched off by the intermediate rear branch becomes unnecessary,
The stripped portion of the optical cable, the extra length of the drop optical fiber, the stripped portion of the drop optical fiber, the fusion spliced portion, and the cut coated optical fiber on the other side, which are mounted in the closure by the intermediate rear branch. , Each taking out process,
The fusion spliced portion of the optical fiber core is not cut, and in the vicinity of the stripped end of the drop optical fiber, cutting the coated optical fiber on the drop optical fiber side, removing the drop optical fiber,
One end of the coated optical fiber having the fusion spliced portion, and the step of fusion splicing one end of the coated optical fiber on the other side cut at the time of the intermediate rear branch,
A method of extending the lower part, comprising:

Images