JPH0753042Y2 - Optical fiber cable with gas dam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cable with a gas dam in which a gas dam portion is formed in an optical fiber cable having an optical fiber tape core.

[Prior Art] Japanese Patent Laid-Open No. 60-16690 discloses a conventional gas dam structure.
There is one disclosed in No. 8. FIG. 5 shows the case where the gas dam forming portion 10 is provided in the middle of the optical fiber cable 1, and FIG. 6 shows the gas dam forming portion 10 at the end of the optical fiber cable 1.
Indicates the case with.

First, the outer cover of the optical fiber cable 1 is stripped at a required length in the dam formation portion 10 to expose a plurality of optical fiber cores 2, and then the tension member 3 provided for improving the tensile characteristics of the cable is dammed. After cutting in the forming section,
After a spacer (separation holding material) 5 having a shape as shown in FIGS. 7A and 7C and having a through hole 4 is inserted into the tension member 3 and fixed, the tension member connecting sleeve 6 is again provided.
Connect with. The reason for this is to prevent the gas path generated along the tension member 3.

Next, the optical fiber core wire 2 in the dam forming portion 10 is attached to the spacer 5
The optical fiber core wires 2 are separated from each other by arranging the optical fiber core wires 2 through or inserting the through holes 4 into a cage shape.

Finally, a dam portion forming filler 7 made of urethane resin or the like is filled so as to cover the dam forming portion 10 to form a gas dam portion.

[Problems to be Solved by the Invention] However, the conventional structure of the gas dam forming portion has the following problems in the case of an optical fiber cable having a high-density optical fiber tape core. That is, in the structure of the spacer 5 shown in FIG. 7, the (a) shaped spacer 5 is a complete through hole 4, and therefore, when forming the gas dam portion 10, the tape cores are provided to the plurality of through holes 4. It is not easy to pass it through,
There is also a risk of damaging the optical fiber when it is passed.

Further, as shown in FIGS. 7 (b) and (c), even if the through hole 4 is a spacer 5 having an opening, it is arranged in a state of being twisted to the through hole 4 at an angle (θ °). There is a problem that

Further, as shown in FIGS. 8A and 8B, at the boundary (point A) where the optical fiber tape core 20 is exposed from the spacer groove (slot) 8a of the tape core housing spacer 8, the tape core is In some cases, 20 is bent and the cores of the tape intersect.

Therefore, when the filling material 7 for forming the dam portion is filled in such a state, the thermal expansion (volume expansion) of the filling material causes the microbend (small bend) of the optical fiber due to the non-uniform stress in the gas dam forming portion. ) Is likely to occur, and there is a problem of degrading transmission characteristics.

An object of the present invention is to provide an optical fiber cable having a gas dam, which is excellent in gas tightness and transmission characteristics of the cable.

[Means for Solving the Problems] In the present invention, a plurality of optical fiber tape cores are housed in a spacer groove formed in an outer periphery of a tension member in a radial direction so as to be stacked in a radial direction. An optical fiber cable having a sheath on the outer periphery of the core accommodating spacer has an exposed portion formed by removing a part of the sheath and the tape wire core accommodating spacer by a predetermined length, and the entire exposed portion is a dam portion. An optical fiber cable with a gas dam in which a gas dam is formed so as to be covered with a protective case filled with a forming filler, and a separation holding shelf formed in multiple stages in a radial direction and the optical fiber tape held on the separation holding shelf One end of the spacer with shelves having separation preventing means for preventing separation of the wire core is attached to the tension member of the exposed portion, and is attached to the separation holding shelf of the spacer with shelves. Note that a plurality of optical fiber tape cores are held so as to be separated from each other so as to maintain their laminated arrangement. [Operation] The spacer having a vertical structure is used in the exposed portion of the optical fiber tape cores. The optical fiber tape core is isolated and held in the vertical structure in the same manner as the tape core is accommodated in the structure.
Therefore, the respective tape cores are separated from each other without being twisted or bent. For this reason, it is possible to prevent bending or twisting of the optical fiber core wire, which is likely to occur during the work of forming the dam portion.

[Embodiment] An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention in which a gas dam portion is provided in the middle of the cable.

The configuration of the intermediate gas dam portion 10 is different from that of FIG. 5 in that instead of the disc-shaped spacer 5, a spacer 11 with a shelf extending from the tension member 3 in the radial direction is used. That is,
In order to isolate the tape cores 20 at the exposed portions of the tape cores, the tape cores 20 have a vertical structure as shown in FIGS. 2 (a) and 2 (c).
Several spacers 11 for accommodating the above are attached to the gas dam forming portion so that the optical fiber tape core is not bent or twisted as much as possible.

More specifically, the spacer 11 shown in FIG. 2A has a base portion 13 having an insertion hole 12 for the tension member 3, an arm 15 having a multistage separation holding shelf 14 extending radially from the base portion, and a separation holding member. U-shaped lid plate that covers the shelf 14 and both ends fit to the arm 15
16 and. The spacer 11 shown in FIG. 2 (b) has a structure in which a plurality of the arms 15 are provided radially, and FIG.
Instead of the U-shaped cover plate 16 described above, the spacer 11 is a separate holding shelf 14
It has a structure in which the edge 17 of is started up.

First, the outer cover of the optical fiber cable 1 is stripped at a required length in the dam forming portion 10 to expose a plurality of optical fiber tape cores 20, and then the tension member 3 provided for improving the tensile characteristics of the cable is attached. Cut inside the dam formation section. After that, the insertion hole 12 of the spacer 11 having the separation holding shelf 14 having the shape shown in FIGS. 2A and 2C is inserted into the tension member 3 and fixed. At this time, the spacer 11 is fixed to the tension member 3 in advance by an adhesive or the like to prevent rotation, but the position in the rotation direction where the spacer 11 is fixed is the same as that in the tape core accommodation state of the separation holding shelf 14 in the cable structure. It has a vertical structure and is positioned so that the tape core is not twisted or bent.

Further, in this embodiment, the grooved protective guide sleeve 18 is applied to the boundary portion where the tape core is exposed from the accommodation groove (slot type spacer groove) of the optical fiber tape core to accommodate the tape core in the spacer. We are trying to prevent local bending when doing. As shown in FIGS. 4 (a) and 4 (b), this grooved protective guide sleeve 18 has a plurality of grooves 18 extending in the circumferential axis direction.
and a tension member insertion hole 19 in the center.

After the guide sleeve 18 and a proper number of spacers 11 are provided, the tension member 3 is connected again by the connection sleeve 6.

Next, the optical fiber ribbon 20 in the dam forming portion 10 is placed on the separation holding shelf 14 of the spacer 11 or further pressed by the U-shaped lid plate 16 so as not to be separated from the shelf, and each optical fiber ribbon 20 is attached. Isolate from each other. FIG. 3 shows a state in which the optical fiber ribbon 20 is isolated and held by the spacer 11.

Finally, a dam portion forming filler 7 made of urethane resin or the like is filled so as to cover the dam forming portion 10 to form a gas dam portion.

According to the above-mentioned embodiment, in the exposed portion of the tape core, since each tape core 20 is isolated in the same manner as the cable structure by the spacer 11 with the vertical structure, it is likely to occur at the time of forming the dam portion. In addition, it is possible to provide an optical fiber cable with a gas dam that can prevent bending and twisting of the optical fiber core wire, thus taking measures against microbending and not deteriorating transmission characteristics.

In addition, a protective guide sleeve is interposed at the boundary between the optical fiber cable core receiving groove and the tape core exposed portion where stress due to thermal expansion of the dam portion forming filler tends to concentrate. Therefore, it is possible to avoid an increase in loss of transmission characteristics due to microbends caused by thermal expansion of the filling material for forming the dam portion.

[Advantages of the Invention] As described above, according to the present invention, it is possible to obtain an optical fiber cable with a gas dam that does not impair the transmission path characteristics of the optical fiber and is highly reliable in terms of airtightness.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an optical fiber cable with an intermediate gas dam according to the present invention, FIG. 2 is a diagram showing a configuration example of a fiber-optic cable core wire accommodating spacer having a vertical structure, and FIG. FIG. 4 is a view showing an isolated holding state of a fiber tape core wire, FIG. 4 is a view showing a configuration example of a grooved protective guide sleeve, FIG. 5 is a structural view of a conventional optical fiber cable with an intermediate gas dam, and FIG. Fig. 7 is a structural diagram of an optical fiber cable with a terminating gas dam, Fig. 7 is a structural diagram of a conventional spacer for separating the optical fiber core, and Fig. 8 is a tape slot type spacer groove accommodated in the tape optical fiber core. It is a figure which shows the structural example. In the drawing, 1 is an optical fiber cable, 3 is a tension member, 6 is a tension member adhesive sleeve, 7 is a filling material for forming a dam portion, 8 is a spacer for accommodating a tape core, 9 is a protective case for a gas dam forming portion, and 10 is a gas dam forming Part, 11 is a vertical spacer with a shelf, 12 is a tension member insertion hole, 13 is a base part, 14 is a separate holding shelf, 15 is an arm, 16 is a grooved protective guide sleeve, 16 is a U-shaped lid plate, 17 Is the edge of a separate holding shelf, 18
Is a grooved protective guide sleeve, 18a is a groove, 19 is a tension member insertion hole, and 20 is an optical fiber tape core.

Claims (1)

[Scope of utility model registration request] 1. A plurality of optical fiber tape cores are housed in a spacer groove formed in the outer periphery of a tension member in a radial direction in a spacer groove, and the outer periphery of the tape core accommodating spacer is covered. In the optical fiber cable provided with the protection, a part of the outer sheath and the tape wire core accommodating spacer is removed by a predetermined length to form an exposed portion, and the entire exposed portion is filled with a dam portion forming filler. In an optical fiber cable with a gas dam in which a gas dam is formed by being covered with a case, a separation holding shelf formed in multiple stages in the radial direction and the optical fiber tape core held on the separation holding shelf are prevented from separating. One end of the spacer with shelves having a prevention means is attached to the tension member of the exposed portion, and the plurality of optical fiber tape wires are attached to the separation holding shelf of the spacer with shelves. A fiber optic cable with a gas dam, characterized in that the cores are held separate from each other so as to maintain their laminated arrangement.