JPS60177309A - Optical cable - Google Patents

Abstract

PURPOSE:To improve flexibility with thin, simple structure by storing one optical fiber in each of plural cavities provided independently in an S-Z twist state at specific pitch in the axial direction of a columnar insulator without contacting. CONSTITUTION:One optical fiber 2 is stored in each of plural cavity 6 provided independently in the S-Z twist state at specific pitch in the axial direction of the columnar insulator 4 without contacting. The columnar insulator 4 is made of synthetic resin, and protects the optical fibers 2 against external force and also serves as an insulator when a bare conductor 3 is stored in a cavity. The number of the cavities 6 is >=2 and determined optionally. Further, a tension member 1 may be embedded in the columnar insulator 4. Thus, the flexibility is improved with the thin and simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical cable made up of a collection of optical fibers.

When making optical cables by assembling optical fibers, how to prevent microbending loss is an important design issue. In conventional optical cables, optical fibers 323t, . . . are attached to tape folding spacers 2t, 2t, .
(see Figure 1) and an optical fiber 3/ in the recess of the extrusion type spacer 4'.
/, . . . are inserted and the outside is covered with a restraining tape 5' (see FIG. 2), which is cited as a method for preventing microbending loss.

However, in the former case, the electric wire 17°1',
It has the disadvantage that it becomes thicker by the outer diameter of..., and even when only the optical fibers 3' are assembled, it is necessary to use a protective material 6' to protect the optical fibers from external pressure, which increases the cost and time. There is. On the other hand, in the latter case, the spacer 4' must be significantly enlarged to accommodate the electrical wire covered with an insulator (not shown), resulting in an imbalance compared to the diameter of the optical fiber 3'. Therefore, the bare conductors 7/, 7/, . There is a risk of a short circuit occurring between 7' and 7'.

The present invention provides an optical cable that eliminates the above-mentioned drawbacks of conventional products, and its structure is such that a number of silks ΦS are arranged independently at a constant pitch without contacting each other in the axial direction of a cylindrical insulator 4. -2 Each of the plurality of twisted cavities 6 accommodates one optical fiber 2, 2, . . . .

The cylindrical insulator 4 used in the present invention is made of synthetic resin such as polyolefin, vinyl chloride, or fluororesin, and serves to protect the optical fiber 2 from external forces, and also accommodates the bare conductor 3 in the cavity. In some cases, it also serves as an insulator. Note that the number of cavities 6 is 2.
It goes without saying that the diameter of the cavity 6 should be determined as long as the diameter of the optical fiber 2 is equal to or larger than the diameter of the optical fiber 2.

In the present invention, the optical fiber 2 is not particularly limited and may be any fiber used for the purpose of guiding light. Examples of this include quartz fiber, plastic fiber, and the like.

In addition, in the present invention, as described above, bare (metal)
The conductor 3 may be housed in the cavity 6. Examples of the bare conductor 3 used include single wires and twisted wires such as copper wires and aluminum wires.

In addition, if necessary, the tension member 1 can be replaced with a cylindrical insulator 4.
It can also be embedded in . Ten used, John member 1
Examples include single wires and stranded wires such as plastic wires, copper wires, steel wires, and other metal wires, and the wires may be selected so as to have the strength to withstand the tensile force required during use.

The insulator 4 may be provided with an outer cover 5 if necessary. Examples of the materials used include synthetic resins such as polyolefin, vinyl chloride, and fluororesin, and rubber materials.

Furthermore, a layer of metal shield, plastic tape, or paper tape may be formed between the insulator 4 and the outer cover 5 for the purpose of shielding (all are omitted from the figure).

Next, the manufacturing process of the optical cable according to the present invention will be explained.

First, the optical fiber 2, the tension member 1 if necessary, and the bare conductor 3 are wound from the bobbin 7 and brought to the point 8a of the crosshead 8 of the drawer 3606, which rotates back and forth.

These optical fibers 2 and the like are twisted while rotating reciprocatingly to form a t1R÷s-2 twisted shape with a constant pitch. This product is brought to a crosshead 8, and an extruder 9 attached thereto.
The optical fiber 2 is injected and extruded into the cavity 6.
2. ..., if necessary, connect the bare conductors 3 to S- at a constant pitch.
A Z-twisted optical cable is formed. Further, at this time, if necessary, the tension member 1 may be embedded in the cylindrical insulator 4 at the same time.

The optical cable of the present invention described above has the following advantages.

(1) Although it has an extremely thin shape, the cavities are independent without contacting each other, so that the bare conductors are sufficiently insulated, especially in the case of composite cables consisting of optical fibers and bare conductors.0 (2) Possible Excellent flexibility. S with constant pitch of cavities
- Since it has a Z-twist structure, it can have the same effect as the twisting effect of ordinary optical cables.

(3) Manufacture is simple and inexpensive. Since only the point of the crosshead needs to be rotated back and forth in the direction of 360a, production can be achieved by simply modifying conventional equipment in this way.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of a conventional optical cable, Figure 3 is a cross-sectional view of the optical cable of the present invention, Figure 4 is a partially cutaway perspective view of the same, and Figure 5 shows the twisted state of the cavity. The schematic diagram, FIG. 6, is a perspective view showing the manufacturing state of the optical cable of the present invention. In the figure, 1 is a tension member, 2 is an optical fiber, 3 is a bare (metallic) conductor, 4 is an insulator, 6 is a cavity, 8 is a crosshead, 8a is a point, and 9 is an extrusion type.

Claims (1)

[Claims] An optical cable characterized in that one optical fiber is housed in each of a plurality of cavities that are arranged in an S-2 twisted manner at a constant pitch in the axial direction of a cylindrical insulator, so that they are arranged independently without contacting each other and arranged in an S-2 twist. .