JPS6344810Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an optical fiber cable.

Multi-stranded type and spacer type are commonly used for optical fiber cables, and the former is superior to the latter in terms of space factor, and the latter is superior to the former in terms of avoiding stress on the optical fiber. There is.

Therefore, the latter spacer type is often used in applications where tension or the like may be applied to the optical fiber.

As shown in FIG. 1, the spacer type optical fiber cable has a spacer 1 in which a spiral groove 10 is provided on the outer periphery of a rod-shaped body such as plastic or metal, and an optical fiber 2 is accommodated in the spiral groove 10.
A sheath 3 is provided on the outside.

In some cases, the helical direction of the spiral groove 10 is unidirectional, but there is also a so-called inverted helical type (SZ type) spacer type optical fiber cable in which the direction is periodically reversed.

In such a spacer-type optical fiber cable, the size of the helical groove 10 is configured to be slightly larger than the outer diameter of the optical fiber 2 to provide a margin for the optical fiber 2 and prevent tension from being applied to the optical fiber 2. ing.

However, the spiral groove 10
If the size of the spiral groove 10 is too large, the mechanical strength will be weakened, so the size of the spiral groove 10 and the spacer 1
A certain relationship is required in design with the outer diameter of. Needless to say, as the outer diameter of the spacer 1 increases, the cost of the entire cable increases, so it is desirable to keep the dimensions of the helical groove 10 as small as possible.

On the other hand, considering the reliability of the optical fiber 2, if the spiral groove 10 becomes small, stress is likely to be applied to the optical fiber 2, so it is desirable to make it as large as possible to give the optical fiber 2 some margin.

In view of this situation, the present invention aims to provide an optical fiber cable that reduces cost by reducing the size of the spacer as much as possible, and improves reliability by minimizing tension on the optical fiber.

The configuration of the present invention will be specifically explained with reference to the drawings showing one embodiment.

The elements necessary for the construction of the present invention are completely the same as those of the conventional example shown in FIG. 1, and the cross section thereof is as shown in FIG.

That is, a spiral groove 10 is provided on the outer periphery of the spacer 1, an optical fiber 2 is housed in the spiral groove 10, and a sheath 3 is provided on the outside.

This spiral groove 10 is formed so that its direction is periodically reversed.

FIG. 2 is a front view showing a reversed portion of the spiral groove 10, and the depth of the spiral groove 10 is larger in the reversed portion A than in the other portion B.

When the spiral groove 10 is inverted, the optical fiber 2
Since expansion and contraction occurs first in the inverted part A, if the depth of the groove is made large so that there is room for the optical fiber 2 in the inverted part A, the depth of the groove in the other part B can be reduced. There is no problem in practice even if the size is small and there is little room for it.

Therefore, if the mechanical strength of the inverted portion A is designed to be the minimum allowable strength, sufficient mechanical strength can be obtained in the other portion B.

Further, when the mechanical strength is set to the minimum allowable strength, the outer diameter of the spacer in the other portion B can be reduced, resulting in a significant cost reduction.

At this time, only the reversed portion A has a large diameter. The inverted portion A is also made small in diameter and provided with a reinforcing layer or the like on the outer periphery. The problem can be solved by such methods.

As explained above, the optical fiber cable of the present invention has the following remarkable effects.

(1) Since the depth of the groove is large in the inverted part that contributes to the expansion and contraction of the optical fiber, the optical fiber moves within this groove and no tension is applied to the optical fiber, resulting in high reliability.

(2) Since the spiral groove can be made smaller in other parts of the inverted part, the outer diameter of the spacer can be made smaller, which is economical. Further, when the outer diameter of the spacer is the same as that of the conventional spacer, mechanical strength is excellent.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a spacer-type optical fiber cable, and FIG. 2 is a front view showing the appearance of a spacer in an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Spacer, 2... Optical fiber, 3... Sheath, 10... Spiral groove, A... Reversed part, B...
other parts.

Claims (1)

[Scope of utility model registration request] A spiral groove 10 is provided on the outer periphery of the rod-shaped spacer 1, and the spiral direction of the spiral groove 10 is periodically reversed. In the optical fiber cable in which the sheath 3 is applied to the helical groove 1
An optical fiber cable characterized in that the depth of the spiral groove 10 is greater in a portion of the fiber 0 where the direction of the spiral is reversed than in other portions.