JP2006171362A - Connecting part of optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting part of an optical fiber cable, which can protect an optical fiber therein against external forces, so that microbending is produced and transmission loss is not increased, and which can be bent more easily than conventional ones, so that winding on a drum is facilitated to eliminate problems in the manufacturing process thereafter. <P>SOLUTION: This is a connecting part for a slot-type optical fiber cable. In the connecting part of the optical fiber cable where this connecting part is covered with a flexible protective tube 21, a tension member 1 is connected, with a resin coating 11 removed for a prescribed length at the connecting end. Also, in the longitudinal direction of the exposed tension member 1, there are intermittently mounted a plurality of disk-like spacers 13, having an outer diameter not larger than the bore of the flexible protective tube 21 and having an optical fiber through hole 17 prepared in the circumferential direction for an optical fiber 2 to pass through. The optical fiber 2 is held, in a state of possessing an excess length by means of the spacers 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a tension member disposed in the center is provided with a resin coating having a spiral groove on the outer surface or a reverse spiral groove in which the direction of the spiral is reversed at an appropriate interval. The present invention relates to an improvement in a connection portion of a so-called slot type optical fiber cable in which an optical fiber is accommodated.

2. Description of the Related Art Conventionally, in a cable such as a power / optical composite submarine cable in which, for example, a submarine power cable and an optical fiber cable are combined, the optical fiber cable is often stored in a gap between the power cables.
Since this type of optical fiber cable is easily subjected to a large water pressure or a side pressure from a power cable, a structure having a stronger resistance to the side pressure is required. As a typical structure corresponding to this requirement, there is an optical fiber cable having a structure called a so-called slot-type optical fiber cable (hereinafter simply referred to as an optical fiber cable).

This optical fiber cable is obtained by extrusion-coating a resin coating having a substantially circular cross section on a tension member such as a steel wire arranged at the center, and an optical fiber is loosely fitted on the outer surface of the resin coating. In other words, a spiral groove that is accommodated with a surplus length, or a reverse spiral (usually called SZ type) groove in which the groove reverses its direction at a predetermined pitch, and the optical fiber is provided with the groove. It is stored inside.
Since the optical fiber is stored with a surplus length in the groove provided on the resin-coated surface in this way, the optical fiber is not easily subjected to side pressure and tension from the outside of the cable, and is therefore resistant to external force. It has characteristics.

By the way, when optical fiber cables having such a structure are connected to each other, a length that cannot be accommodated in the groove provided in the resin coating is necessarily generated in the vicinity of the connected optical fibers including the connecting portion. End up.
The reason is that when connecting optical fiber cables, in order to connect a tension member or optical fiber at the connection end, the tension member can be exposed by removing the resin coating from the connection end by a predetermined length. This is because the required length of the optical fiber must be secured.

For the predetermined length from which the resin coating has been removed, the optical fiber is in an idle state because there is no groove for storing the optical fiber after connection.
Therefore, if the optical fiber after connection is left as it is, adjacent optical fibers get entangled with each other, or the connection part hangs down due to its own weight, causing microbending, which increases the transmission loss of the optical fiber. There was a problem such as.

As one method for dealing with this problem, there is a method in which a spacer as described in Patent Document 1 is applied to this connecting portion, although the purpose of use is different.
As shown in FIG. 6 and FIG. 7, the portion of the tension member 1 of the optical fiber cables 10 and 10 from which the resin coating 11 has been removed is divided into two cylinders that match the length of the resin coating 11 just removed. A spacer 3 is prepared, and this is used by fitting the convex part 4 and the concave part 5 provided on the half-split surface of the cylindrical spacer 3 to the tension member 1.

A groove 6 for accommodating the optical fiber 2 after connection is provided on the outer surface of the cylindrical spacer 3, and a groove 8 for accommodating the tension member 1 and its connection portion 7 is provided at the center.
Incidentally, the groove 6 provided on the outer surface of the columnar spacer 3 is substantially continuous with the groove 9 provided on the outer surface of the resin coating 11 of the optical fiber cables 10 and 10 as shown in FIG. Is formed. In addition, when the outer diameter of the cylindrical spacer 3 is finished to be substantially the same as or slightly smaller than the outer diameter of the resin coating 11 covered with the tension member 1, and the protective sleeve 20 is covered over the entire connecting portion, the optical fiber The outer diameter of the cable 10 and the outer diameter of the connecting portion are substantially equal.
Here, reference numeral 12 in FIG. 7 denotes a sheath provided in the optical fiber cable 10.

JP-A-6-214131

By the way, when the cylindrical spacer 3 shown in FIGS. 6 and 7 is used for the connecting portion of the optical fiber cable 10, there is no problem if the connecting portion is always present in the straight portion of the optical fiber cable 10. However, when this connecting portion comes to the bent portion of the cable laying path, for example, there is a problem that laying becomes extremely difficult because the columnar spacer 3 acts as a force to prevent bending.
In addition, when this connection portion is formed at an early stage of cable manufacturing, when the optical fiber cable 10 with this connection portion is assembled with, for example, a power cable, it is necessary to wind it around a drum and carry it to a subsequent assembly step. When the columnar spacer 3 described above is used for the connecting portion, there is a problem that the connecting portion is difficult to bend and drum winding is not easy. If it is intended to be wound around the drum, an unexpectedly large drum is required, and as a result, the capacity of the post-process equipment needs to be changed.

  Therefore, an object of the present invention is to protect the optical fiber in the connection portion from external force so as not to cause microbending and increase in transmission loss, and to bend more easily than the conventional one. An object of the present invention is to provide a connection portion of an optical fiber cable that does not cause a problem in the manufacturing process.

  In order to achieve the above object, the optical fiber cable connection portion according to claim 1, wherein a tension member is arranged at the center, and a spiral or inverted spiral groove is formed on the surface of the resin coating coated on the outside of the tension member. An optical fiber cable connecting portion provided by connecting optical fiber cables each having an optical fiber accommodated in the groove, wherein the connecting portion is covered with a flexible protective tube. In the connecting portion, the tension member is connected in a state where the resin coating is removed by a predetermined length at the connection end portion and exposed, and in the length direction of the exposed tension member, the flexible protection is provided. A plurality of disc-like spacers having an outer diameter equal to or smaller than the inner diameter of the tube and a groove or hole through which the optical fiber passes in the circumferential direction are intermittently mounted. , In which the optical fiber is characterized in that it is held in a state having the extra length by the spacer.

According to the optical fiber cable connecting portion according to claim 1, the spacer for storing or holding the optical fiber after connection is not a columnar one but a thin disc-like spacer. In addition, since the protective layer covering the connection portion is formed of a flexible protective tube, it is easy to wind the optical fiber cable having the connection portion formed in this way around the drum, and therefore extremely large. There is no need to use a drum, and there is no hindrance to the production of the subsequent process.
Of course, by attaching a plurality of the disk-shaped spacers to the tension member intermittently, the optical fiber in the connecting portion has an extra length, and the optical fiber is housed in a groove or a through hole provided in the spacer. By further covering the outside of the connecting portion with a flexible protective tube, it is possible to prevent external force such as side pressure, tension or bending from being applied directly to the optical fiber, and increase the transmission loss of the optical fiber due to microbending. Can be prevented.

The optical fiber cable connecting portion according to claim 2 is the optical fiber cable connecting portion according to claim 1, wherein the plurality of spacers are intermittently provided at intervals of 100 mm to 200 mm in the length direction of the tension member. It is characterized by being mounted.
According to the connecting portion of the optical fiber cable according to claim 2, the plurality of disc-shaped spacers have a relatively short pitch in the length direction of the tension member from which the resin coating is peeled off. Since it is mounted intermittently at an interval of 100 mm to 200 mm, the extra length of the optical fiber can be secured sufficiently, and even if this connection part is wound around a drum or bent, the optical fiber is protected flexibly. There is no risk of contact with the inside of the tube and rubbing to cause an increase in transmission loss or damage.

  Furthermore, the connection part of the optical fiber cable according to claim 3 of the present invention is the connection part of the optical fiber cable according to claim 1 or 2, wherein the tension member and the optical fiber among the plurality of spacers. The spacers mounted on both sides of each connection part are fixed spacers that cannot rotate with respect to the tension member, and the spacers that are mounted closest to the exposure start end of the tension member are the tension members. In the other range, the fixed spacer and the rotatable spacer are alternately mounted.

According to the connecting portion of the optical fiber cable according to claim 3, the fixing members are arranged on both sides of the connecting portions between the tension members and the optical fibers in the connecting portion, and the connecting portions of the tension members are arranged. The optical fiber connection part is protected from vibrations and damage to the connection part, and the spacer mounted at the furthest position from the tension member connection part is a rotatable spacer, and other ranges Then, the extra length of the optical fiber can be easily adjusted by alternately mounting the fixed spacer and the rotatable spacer.
Moreover, since the movement of the rotatable spacer can be moderately attached to the movement of the optical fiber, bending and pulling applied to the optical fiber stored in the groove or through hole of the spacer can be relaxed, Accordingly, an increase in transmission loss of the optical fiber can be suppressed.

  As described above, according to the present invention, the optical fiber in the connection portion can be protected from external force so as not to cause an increase in transmission loss due to microbending, and is easier to bend than the conventional one. Thus, it is possible to provide a connection portion of an optical fiber cable that does not cause a problem in the manufacturing of the subsequent process.

  Examples of the connecting portion of the optical fiber cable according to the present invention will be described below in detail with reference to FIGS.

1 and 2 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a connecting portion of an optical fiber cable according to the present invention. FIG. 2 is a plan view showing an embodiment of the spacer shown in FIG. is there.
As shown in FIG. 1, the groove 9 provided on the outer surface of the resin coating 11 covered with the tension member 1 is formed with the sheath 12 at the connection end of the slot-type optical fiber cables 10 and 10 to be connected. The optical fiber 2 housed inside was peeled off by a predetermined length, here about 1000 mm, taking care not to damage the optical fiber 2. The stripping length varies depending on the outer diameter of the entire cable and the like, but is generally in the range of 400 mm to 1000 mm.
Next, the resin coating 11 coated on the tension member 1 is also peeled off by about 950 mm while taking care not to damage the optical fiber 2, and the tension member 1 is about 1900 mm in total at the connection terminals of both cables 10 and 10. Exposed. That is, the end of the sheath 12 was set to a position slightly retracted from the end of the resin coating 11.

When the sheath 12 and the resin coating 11 are stripped to the required length in this way, a flexible protective tube that finally covers the entire connection portion of the optical fiber cable, for example, a metal interlock tube 21 is preliminarily attached to one optical fiber. The cable 10 is passed through.
Next, the ends of the tension members 1 and 1 facing each other were cut off by, for example, 100 mm each to produce a length necessary for connecting the optical fiber 2 and a necessary extra length. Of course, this cut-off length is adjusted each time in consideration of how much extra length is put into this connecting portion.

  Subsequently, each of the tension members 1 and 1 in an exposed state is provided with a plurality of resin-made disc-like spacers 13 shown in FIG. 2 and spacer fixing members 18 shown in FIG. 18, the tension member 1 was passed through the tension member through holes 16 and 19 of the spacer 13 and the spacer fixing member 18, and the optical fiber 2 was passed through the optical fiber through hole 17. Here, it is assumed that the spacers 13 will eventually have a mounting interval of 100 mm to 200 mm, and the necessary number is passed through both tension members 1.

Thereafter, the ends of the tension members 1 and 1 were inserted facing the metal sleeve or the like, and the metal sleeve was swaged to form the connection portion 7 of the tension members 1 and 1.
Each optical fiber 2 was fused and connected using, for example, a general-purpose fusion splicer, and a reinforcing sleeve or the like was attached to the fusion spliced portion to form an optical fiber connecting portion 15. Incidentally, although only one optical fiber 2 is depicted in FIG. 1, this does not complicate the drawing, and other optical fibers are omitted. In practice, there are generally a plurality of optical fibers.

When the connection between the tension member 1 and the optical fiber 2 is completed, the spacer 13 previously passed through the tension members 1 and 1 is attached to the tension member 1 using the spacer fixing member 18 and an adhesive as shown in FIG.
Here, when mounting the spacer 13, the fixed spacer 13 a that is mounted so as not to rotate with respect to the tension member 1 and the rotatable spacer 13 b that can rotate with respect to the tension member 1 are mounted according to a predetermined rule.
Here, for example, being rotatable with respect to the tension member 1 means being able to rotate around the axis of the tension member 1.

The predetermined rules described above are as follows.
The spacers 13 mounted on both sides of the connection part 7 of the tension member 1 and each connection part 15 of the optical fiber 2 are fixed spacers 13a that cannot rotate with respect to the tension member 1, and are located at the exposure start end of the tension member 1. The spacer 13 that is mounted at a close position, that is, a position closest to the left and right ends of the tension member 1 exposed in FIG. 1 is a rotatable spacer 13b that is rotatable with respect to the tension member 1, and in other ranges. The fixed spacer 13a and the rotatable spacer 13b are alternately mounted.
In FIG. 1, a fixed spacer 13a with hatching and a rotatable spacer 13b without hatching are attached to the tension member 1 at substantially equal intervals in the range of 100 mm to 200 mm according to this rule.

The fixed spacer 13a is fixed to the tension member 1 so as not to rotate with an adhesive or the like.
On the other hand, the rotatable spacer 13b is sandwiched from the left and right by the spacer fixing member 18 shown in FIG. 3 so as not to move in the length direction of the tension member 1 after mounting.
Further, the rotatable spacer 13b has an appropriate clearance between the tension member through-hole 16 and the tension member 1 so that the spacer 13 itself can be rotated with the spacer 13 still attached to the tension member 1. Used as the universal spacer 13b. The rotatable spacer 13b is configured so that when tension is applied to the optical fiber 2 passed through the optical fiber through-hole 17, the tension of the rotatable spacer 13b rotates around the axis of the tension member 1 in a direction that relaxes the tension. It is attached to member 1.

The fixed spacer 13a and the rotatable spacer 13b are disk-shaped made of metal or resin, and have an outer diameter slightly smaller than the inner diameter of the flexible protective tube 21. Designed so that the outer diameter of the entire connecting portion covered with the flexible protective tube 21 does not become too large, and when the bending is applied to the connecting portion, the flexible protective tube 21 can move in accordance with the bending. Has been.
Furthermore, the mounting interval of the fixed spacer 13a and the rotatable spacer 13b is set to 100 mm to 200 mm, but this interval is independent of the pitch of the grooves 9 formed on the outer surface of the resin coating 11 of the optical fiber cables 10 and 10. It is.
Incidentally, when the distance between the spacers 13 is 100 mm or less, the connection portions are difficult to bend because there are too many spacers 13. There is a high risk that the optical fiber 2 in the vicinity of the portion 15 will rub against the inner surface of the flexible protective tube 21 and be rubbed.

  By the way, when passing the optical fiber 2 through the optical fiber through hole 17 of the spacer 13, if only one optical fiber 2 is accommodated in the groove 9 of the resin coating 11, one optical fiber through hole is provided. When one optical fiber 2 is passed through 17 and two or more optical fibers 2 are accommodated, they are combined into one optical fiber through hole 17 and in different grooves 9. It penetrates so that it may not cross the set of optical fiber 2 stored.

As the spacer 13 to be used, a spacer having a number of optical fiber through holes 17 equal to or greater than the number of grooves 9 provided on the outer surface of the resin coating 11 of the optical fiber cable 10 in the circumferential direction. use. Basically, a spacer 13 is used in which optical fiber through holes 17 equal in number to the grooves 9 formed in the outer surface of the resin coating 11 are provided in the circumferential direction.
That is, when there are two grooves 9 drilled on the outer surface of the resin coating 11, in principle, the spacer 13 shown in FIG. 2A is used, and when there are three grooves 9, FIG. If the groove 9 has four grooves, the spacer 13 shown in FIG. 2C is used.

By the way, a necessary extra length must be given to the optical fiber 2 at this connecting portion. Specifically, it is necessary to provide at least a surplus length that can cope with the pulling force and bending that the optical fiber 2 receives in connection with cable post-processing and cable laying. Therefore, as schematically shown in FIG. 1, for example, both fixed spacers 13a through which any one optical fiber 2 penetrates adjacent rotatable spacers 13b and fixed spacers 13a, and optical fiber through holes of the rotatable spacer 13b. When the position 17 is viewed from the central axis of the tension member 1 as a rotation axis, the rotatable spacer 13b side is rotated and positioned with respect to the fixed spacer 13a so as to shift within a range of 90 ° to 270 °.
Preferably, as shown in FIG. 1, after any one optical fiber 2 passes through the optical fiber through hole 17 of the rotatable spacer 13b, the light of the rotatable spacer 13b provided in the adjacent fixed spacer 13a. The rotatable spacer 13b side is rotated around the axis of the tension member 1 and adjusted so as to pass through the optical fiber through hole 17 provided at a position shifted from the fiber through hole 17 by 180 °.

Of course, it is needless to say that the length of the optical fiber 2 before connection must be secured in advance so that the fixed spacer 13a and the rotatable spacer 13b can be positioned in this way.
Incidentally, if the deviation angle of each optical fiber through-hole 17 between the fixed spacer 13a and the rotatable spacer 13b is 90 ° or less, the optical fiber 2 cannot have a sufficient extra length. When the fiber 2 is entangled with the tension member 1 to cause microbending, increasing transmission loss, or when the rotatable spacer 13b tries to rotate to alleviate the external force applied to the optical fiber 2, this rotation is the tension member. This is because the optical fiber 2 entangled with 1 may be obstructed.

By the way, in the description of FIG. 1 described above, necessary work such as positioning of each spacer 13 is performed in advance after connecting the optical fiber 2, but after positioning each spacer 13 properly in the tension member 1, There is also a method of forming the connection portion of the optical fiber cable 10 in a procedure reverse to the above description, in which the connection portion 15 is formed at a necessary portion, that is, at least between the fixed spacers 13a. In the connection part of the optical fiber cable 10 of the present invention, it does not ask in which procedure it is formed.
In addition, in the plurality of optical fibers 2, the positions of the optical fiber connection portions 15 were connected appropriately shifted in the length direction of the tension member 1 so that the positions of the optical fiber connection portions 15 were not gathered between the pair of fixed spacers 13a.

According to the connecting portion of the optical fiber cable shown in FIG. 1, the fixing spacers 13a are mounted on both sides of the connecting portion 7 of the tension member 1 and the connecting portion 15 of the optical fiber 2, so that it is particularly suitable for the optical fiber 2. As a result, it is possible to prevent the connecting portion 15 from being shaken by vibration or the like and twisting the connecting portion 15 to damage it.
In addition, since the rotatable spacer 13b is also mixed, the extra length of the optical fiber 2 required at the connection portion of the optical fiber cable can be adjusted by adjusting the angle of the fixed spacer 13a adjacent to the rotatable spacer 13b. Convenient.
In addition, even if an external force is applied to the connecting portion and a tension is applied to the optical fiber 2, the external spacer is not directly applied to the optical fiber 2 because the rotatable spacer 13 b rotates in a direction that relaxes the tension. It is also like.

Incidentally, as the spacer 13 to be used, in addition to the spacer 13 shown in FIG. 2, for example, the spacers 13 shown in FIGS. 4A to 4C and FIGS. 5A to 5C can also be used.
The spacer 13 shown in FIG. 4 is of a type that can be divided into two at the dotted line. In each spacer 13 shown in FIG. 4, the outer ring portion is first separated from the central portion by a portion indicated by a dotted line, and when a predetermined optical fiber 2 is arranged in each optical fiber through hole 17, the outer ring portion is arranged. Is attached to the central portion and, if necessary, bonded to each other with an adhesive so that the optical fiber 2 does not come out of the optical fiber through hole 17.

Further, as shown in FIG. 5, the spacer 13 may be further finely divided at the portion indicated by the dotted line, and the through hole 16 of the tension member 1 may be divided.
Dividing the through hole 16 of the tension member 1 in this way has an advantage that the spacer 13 can be attached to the tension member 1 after the tension member 1 and the optical fiber 2 are connected. When mounting, the separated portions are bonded and integrated using an adhesive or the like.
Incidentally, in the case of the split type spacer 13 shown in FIGS. 4 and 5, when finally integrated, it may be integrated with an adhesive as described above, but it is fitted to each other in advance on the mating surfaces. An integration method such as a method of providing unevenness to be combined can be employed.

  In the case of each of the spacers 13 shown in FIGS. 2, 4, and 5 described above, since the optical fiber 2 is housed in the optical fiber through hole 17 of the spacer 13, it does not jump out of the spacer 13. There is an advantage that the forming operation of the connecting portion of the fiber cable is facilitated. Needless to say, the spacer 13 may be provided with grooves in the circumferential direction of the surface of the spacer 13 other than the one provided with the optical fiber through hole 17. However, when such a spacer 13 is used, when the optical fiber 2 is accommodated in each groove of the spacer 13, the outer side thereof is covered with restraining winding so that the optical fiber 2 does not jump out of the groove of the spacer 13. To do.

Moreover, although the example of the metal interlock pipe | tube is shown as the flexible protective tube 21 in the said Example, a metal corrugated pipe | tube, a plastic corrugated pipe | tube, etc. can also be used.
When this optical fiber cable is used in combination with a power cable so as to be a power / light composite submarine cable, the flexible protective tube 21 is an interlock tube, which is a metal tube, or a metal corrugated tube. Is used.

  Further, in the above-described embodiment, the description has been made on the assumption that the optical fiber cable is applied to the structure in which the optical fiber cable is accommodated in the gap of the power cable for laying the seabed. The application is not limited only to such a composite cable with a power cable, and any optical fiber cable can be applied as long as the optical fiber cable is simply a slot type optical fiber cable.

  As described above, according to the connection portion of the optical fiber cable of the present invention, the optical fiber in the connection portion can be protected from external force so as not to cause microbending and increase in transmission loss, and more easily bent than the conventional one. As a result, it is possible to provide a connecting portion of an optical fiber cable that can be easily wound around a drum and does not cause a problem in subsequent manufacturing processes.

It is a longitudinal cross-sectional schematic diagram which shows one Example of the connection part of the optical fiber cable of this invention. It is an example of the spacer used for this invention, Comprising: It is a top view which shows what is provided with 2-4 optical fiber through-holes. It is a top view which shows an example of the spacer fixing member for fixing a spacer to a tension member. It is a top view which shows another example of the spacer used for this invention, Comprising: Each is provided with 2-4 through-holes of the optical fiber. It is a top view which shows another example of the spacer used for this invention, Comprising: Each is provided with 2-4 through-holes of the optical fiber. It is a partial cross section perspective view of the conventional cylindrical spacer. It is a longitudinal cross-sectional schematic diagram which shows the example which applied the conventional cylindrical spacer which FIG. 6 shows to the connection part of an optical fiber cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tension member 2 Optical fiber 3 Cylindrical spacer 6 Groove 7 Tension member connection part 9 Groove 10 Slot type optical fiber cable 11 Resin coating 12 Sheath 13 Spacer 16 Tension member through-hole 17 Optical fiber through-hole 18 Spacer fixing member 20 Protective sleeve 21 Flexible protective tube

Claims (3)

  A tension member is arranged at the center, and a spiral or inverted spiral groove is provided on the surface of the resin coating coated on the outside of the tension member, and optical fiber cables in which optical fibers are accommodated in the groove are connected to each other. A connected portion of a connected optical fiber cable, wherein the connected portion is covered with a flexible protective tube, and the tension member is connected to each end of the tension member at a predetermined length. In the length direction of the exposed tension member removed and exposed, the outer diameter of the flexible protective tube is equal to or smaller than the inner diameter and the optical fiber provided in the circumferential direction thereof. A plurality of disc-shaped spacers having grooves or holes to be passed are intermittently mounted, and the optical fiber is held in a state having an extra length by the spacers. Connection of the optical fiber cable, characterized in that there.   2. The optical fiber cable connection portion according to claim 1, wherein the plurality of spacers are intermittently mounted at intervals of 100 mm to 200 mm in the length direction of the tension member.   Among the plurality of spacers, spacers mounted on both sides of each connection portion of the tension member and the optical fiber are fixed spacers that cannot rotate with respect to the tension member, and are provided at an exposure start end of the tension member. The spacer mounted at the closest position is a rotatable spacer that is rotatable with respect to the tension member, and in other ranges, fixed spacers and rotatable spacers are alternately mounted. The connection part of the optical fiber cable in any one of Claim 1 or Claim 2.

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