Coated optical fiber cable structure which prevents longitudinal

Details Coated optical fiber cable structure which prevents longitudinal Coated optical fiber cable structure which prevents longitudinal

1984-06-05

1986-12-16

Lee, John

350 9610, 350 9633, G02B 644

Patent

active

046292861

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a coated optical fiber in which a reinforcing coated layer formed on the outer periphery of the optical fiber is formed of an FRP and a layer for improving the mechanical and light transmission characteristics (which will be merely termed "transmission characteristics") is interposed between the optical fiber and the FRP coated layer.


BACKGROUND ART

A general coated optical fiber has as a coated layer at the stage of its strands a primary coated layer and a buffer layer, or a buffer layer used also as the primary coated layer, and a reinforcing coated layer on the outer periphery of the buffer layer.
With respect to the reinforcing coated layer, the layer has already formed of an FRP, and when the reinforcing coated layer is made of the FRP, the mechanical characteristics of the coated optical fiber can be largely improved, it is known that an increase in its transmission loss under the using conditions upon variation in the temperature becomes smaller than a general nylon coated optical fiber.
The above-described FRP reinforcing coated layer (which will be termed "an FRP layer") is, as already known, composed of a glass reinforced fiber material disposed along the longitudinal direction of the optical fiber, and thermosetting resin immersed with the material and cured, and the FRP layer is formed in a pipe shape directly above the buffer layer.
However, the FRP layer has only one disadvantage as will be described below.
In other words, when a compression force, twisting, or bending is acted on the FRP layer formed in the pipe shape from the side face, the layer is deformed in a direction that the pipe shape is flattened so that a longitudinal crack may occur along the longitudinal direction of the reinforced fiber material.
This is caused by the buffer layer, which is soft and lack of the above deformation preventing effect, with the result that the longitudinal crack of the FRP layer is produced.
In addition, in case of the coated optical fiber which has the FRP layer, there are still rooms for improving to enhance the transmission characteristics.
A main object of this invention is to prevent the aforementioned longitudinal crack and to also secure high transmission characteristics.


DISCLOSURE OF INVENTION

In this invention, a buffer layer is formed on the outer periphery of an optical fiber, and in a coated optical fiber in which a reinforced resin layer formed of a reinforced fiber material and thermosetting resin immersed with the material and cured is formed on the outer periphery of the buffer layer, a resin layer having no fiber material is advantageously interposed between the buffer layer and the reinforced coated layer.
In the coated optical fiber of this invention, the resin layer supports the reinforced coated layer and suppress the deformation of the reinforced coated layer. Thus, the mechanical characteristics can be improved, and the rate of producing the aforementioned longitudinal crack can be reduced.
As the foregoing description, when the resin layer is further bonded to the reinforced coated layer, the rate of producing the longitudinal crack of the reinforced coated layer can be reduced by the integration of the reinforced coated layer with the resin layer, thereby enhancing the protecting effect of the optical fiber.
Since a microbend of the optical fiber caused by the reinforced coated layer can be prevented by the resin layer, high transmission characteristic of the coated optical fiber can be secured.


BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are sectional views showing the representative construction of a coated optical fiber according to the present invention,
FIG. 3 is an enlarged sectional view of the reinforced fiber material, and
FIGS. 4 and 5 are explanatory views schematically showing a method of fabricating the coated optical fiber.


BEST MODE OF CARRYING OUT THE INVENTION

A coated optical fiber according to this invention will be described in detail with reference to the accompanying drawings.
In FIGS. 1 and 2,

REFERENCES:
patent: 4072400 (1978-02-01), Claypoole et al.
patent: 4105284 (1978-08-01), Olshansky
patent: 4113349 (1978-09-01), Stiles
patent: 4114981 (1978-09-01), Ishida et al.
patent: 4334733 (1982-06-01), Takeshima et al.
patent: 4504112 (1985-03-01), Gould et al.
patent: 4522464 (1985-06-01), Thompson
patent: 4523804 (1985-06-01), Thompson
patent: 4552433 (1985-11-01), Titchmarsh et al.
Foord et al., "Principles of Fibre-Optical Cable Design" Pro. of IEE, vol. 123 No. 6, 6/76, pp. 597-602.

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