JPH0331928Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a flat cable using a tape-type optical core.

Background of the invention As is well known, a tape-type optical fiber is made by arranging a plurality of optical fibers in a horizontal line and providing a common coating on the outside. When constructing an optical fiber cable by using a plurality of such tape-shaped optical fibers, conventionally, as shown in Figure 1, a tape-shaped optical fiber was used to imitate the case of a round optical fiber. line 10
The common sheath 20 was applied loosely on top of the two, or these were further assembled.

By the way, the tape-type optical fiber 10 is generally weak against lateral pressure, and when a force is applied in the X direction in FIG. Sometimes it can buckle.

In the case of FIG. 1, since each tape-type optical fiber 10 is loosely inserted into the sheath 20, it may be twisted by 90 degrees in the middle, as shown in the imaginary line. Then, for example, even if the tape-shaped optical fiber 10 is wound around a drum so as to bend in the Y direction, it will bend in the X direction at a point where it is twisted by 90 degrees in the middle.
The above problem occurs.

Therefore, it is conceivable to completely eliminate the gap between the tape-type optical fiber 10 and the sheath 20, but in this case, when the sheath 20 contracts during manufacturing or use, the optical fiber 12 Compressive stress is added and transmission loss increases. Furthermore, when such a cable is bent, a tensile force acts on the internal tape-shaped optical fiber 10 at the bending part, resulting in poor reliability in terms of breakage of the optical fiber, and compressive stress acts on the inside of the bend. However, transmission loss also increases.

Furthermore, each tape type optical fiber 10 has a sheath 20
Because the fibers are loosely housed inside the sheath, the top and bottom may change midway, and the tape-shaped optical fibers may forcibly cross each other at various locations within the sheath, exerting lateral pressure on each other in the longitudinal direction of the cross section, resulting in loss. It may also lead to an increase.

The object of this invention is to provide a flat cable using a tape-type optical core that can solve the above problems.

Embodiment In "Fig. 2", numeral 10 indicates the entire tape-type optical core wire. This is, for example, a structure in which a buffer layer 14 such as silicone rubber is provided on the optical fiber 12.
Books are arranged horizontally in one row, a common coating 16 is provided thereon, and a low wear layer 18 is further provided thereon.

The coating 16 is made by extruding nylon through a pipe, and covers each buffer layer 14 only so as to circumscribe it and not to enter into the gaps, thereby facilitating the opening of each core wire. Furthermore, coating 16
The buffer layer 14 prevents lateral pressure from being applied to the optical fiber 12 during extrusion coating.

Furthermore, the low-wear layer 18 is made of a material that has both slippery properties and high tensile strength. Specifically, Kevlar (trade name) fiber is suitable.

When such a material is used, the low friction layer 18 has
It can also serve as a tension member.

For example, the tape type optical fiber 10 described above is
The sheets are lined up in a row in the longitudinal direction of the cross section at appropriate intervals, and a common sheath 20 is placed over them. Further, a slight gap 30 is provided between each tape-type optical fiber 10 and the sheath 20. That is, each tape-shaped optical fiber 10 is not placed on top of or sandwiched between other tape-shaped optical fibers 10 as in the conventional case shown in FIG. (However, with a gap 30 in between).

As mentioned above, since the outermost layer of the tape-type optical core 10 is composed of the low friction layer 18,
The frictional force generated between the sheath 20 and the tape-shaped optical fiber 10 is alleviated to prevent tensile or compressive force from being applied to the tape-type optical fiber 10.

Further, a tension member can be inserted into the sheath 20 located between the tape-type optical fibers 10, if necessary.

Furthermore, it is more convenient to use the drum for this flat cable as shown in Figures 3 and 4. This drum 40 has a plurality of winding drums 44 partitioned by ribs 42, and each winding drum 44 has a gap 4.
6 is provided. flat cable 5
The beginning of winding 0 is located inside the winding drum 44 as shown in FIG. 4, and is pulled out through the gap 46 and wound outside the winding drum 44.

By using this drum 40, a plurality of flat cables 50 can be extended simultaneously.
Therefore, even if only flat cables 50 of the same structure are used, changes in the required transmission capacity can be handled by changing the number of cables to be extended at the same time, and the structure of the flat cable can be changed depending on the transmission capacity. No need to change.

Incidentally, this invention can also be applied to a case where there is only one tape-type optical core wire 10 as shown in "Fig. 5".

Effects (1) Since the outer periphery of the tape-shaped optical fiber 10 faces the sheath 20 on its entire surface, the tape rotates midway through winding in the Y direction as shown in Figure 1. Problems such as winding in the X direction do not occur.

(2) Since there is a slight gap 30 between the tape-shaped optical core 10 and the sheath 20, and the outermost layer of the tape-shaped optical core 10 is the low-friction layer 18, the tape-shaped optical core is The line 10 can slide freely. Therefore, when the cable is bent, no tensile force or compressive force is exerted on the tape-shaped optical fiber 10 due to the sheath 20 pulling it.

If there is only a gap 30 and no slippery low friction layer 18, then the tape type optical fiber 1
0 and the sheath 20 (generally, the weight of the tape-shaped optical fiber 10 causes the lower surface to touch the sheath 2).
(However, if the sheath shrinks, only the tape-shaped optical core 10 may curve greatly and the top surface may touch.) In such a part, when the flat cable 50 is bent, the tape-shaped optical fiber 10 There is a concern that a problem may arise in which the core wire 10 is stretched or compressed by the sheath 20 at a bend.

(3) The cable structure has less empty space than a round cable structure, making it easier to increase density.

(4) Compared to a round shape, it is much easier to bend in the short direction of the cross section, so it has good flexibility.

(5) Even high-capacity cables are extremely thin compared to round cables because they simply spread out laterally.

(6) The tapes are lined up in order, making connection work easier.

(7) Since the low-friction layer of the tape-type optical core is made of a resistant material, there is no need to provide a tension member within the cable unless particularly excessive tension is expected. This contributes to miniaturization of the cable.

Furthermore, when branching into tape-shaped optical fibers in a central office, for example, the low friction layer of each tape-shaped optical fiber acts as a tension member, so that no undue force is applied to the optical fiber.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the prior art, FIGS. 2 and 5 are sectional views of different embodiments of the present invention, and FIG. 3 is an elevational view of a drum 40 suitable for winding the flat cable 50 of the present invention. In the figure, the - cross section is shown in FIG. 10: Tape type optical core wire, 12: Optical fiber, 1
4: Buffer layer, 16: Coating, 18: Low friction layer, 2
0: sheath, 30: gap.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of optical fibers provided with a buffer layer are lined up horizontally in a row, and a common coating extruded from a pipe is provided on the outside, and a tensile strength A sheath is provided on the outside of at least one tape-shaped optical core provided with a low-friction layer made of a material, and the outer periphery of the tape-shaped optical core is connected to the sheath through a slight gap over its entire surface. A flat cable using tape-type optical fibers, which is characterized by facing each other. (2) A flat cable using a tape-shaped optical fiber according to claim 1 of the utility model registration claim, characterized in that a plurality of tape-shaped optical fibers are lined up in the longitudinal direction of the cross section. .