JPH11223752A - Fiber optic cable - Google Patents

Abstract

(57) [Problem] To provide a transmission loss in an optical fiber cable used in an optical communication device due to bending of a fiber. Therefore, it is necessary to wire the fiber so that the bending of the fiber does not become smaller than a certain allowable bending radius. A clad (2) is formed on a core (1), and a sheath (3) and a bending prevention coating (4) are further provided thereon. Due to the circumferential irregularities applied to the bend preventing coating 4, adjacent bends come into contact with each other when bent, thereby preventing bending of a fiber having a bend radius or more. The anti-bending coating 4 may be used as a substitute for the sheath 3, and a protective coating for wire application may be provided on the anti-bending coating 4 for smoothing the application.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable used for an optical communication device for performing communication using light as a medium.

[0002]

2. Description of the Related Art Conventionally, in order to prevent transmission loss due to bending when an optical fiber cable is routed in a vehicle or an apparatus, an optical fiber cable for bending prevention described in Japanese Patent Application Laid-Open No. 61-240211 is used. Are known. This conventional bending-prevention optical fiber cable is configured so that a bending-preventing wire, which is a linear body having high bending rigidity, is twisted between a plurality of optical fibers to form a cable to prevent excessive bending.

[0003]

However, the conventional optical fiber cable for preventing bending has the following problems. 1. The bending prevention line may exceed the allowable bending radius when a load exceeding a certain force is applied. 2. The anti-bending wire has a structure that is twisted together with the fiber, and is advantageous when a plurality of fibers are housed in the same cable. However, in the case of a single fiber, the bending prevention effect is low because the structure is complicated.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and is an excellent optical fiber cable capable of preventing bending beyond an allowable bending radius without using a structure made of a special material such as a bending prevention line. The purpose is to provide.

[0005]

In order to solve the above-mentioned problems, the present invention provides an ordinary sheath material provided with an anti-bending coating having irregularities on the surface so that adjacent convex portions come into contact with each other. Is to prevent the optical fiber from bending,
Thus, the allowable bending radius can be maintained by using the unevenness of the covering material without using a structure made of a special material such as a bending prevention line.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a core for transmitting light, a clad for refracting light and transmitting light into the core, a sheath for protecting the core and the clad, An optical fiber cable further provided outside the sheath and provided with an anti-bending coating for preventing the cladding and the core from bending beyond a certain bending radius,
This has the effect that the optical fiber does not bend beyond the allowable bending radius.

According to a second aspect of the present invention, the anti-bending coating has a large number of convex portions and concave portions on its surface in the circumferential direction, and the adjacent convex portions come into contact with each other to prevent bending. The optical fiber cable according to claim 1, wherein the optical fiber does not bend beyond an allowable bending radius.

According to a third aspect of the present invention, there is provided the optical fiber cable according to the first or second aspect, wherein the sheath is not provided and the anti-bending coating is used in place of the sheath. It has the function of realizing a bending prevention function.

According to a fourth aspect of the present invention, there is provided the optical fiber according to any one of the first to third aspects, further comprising a wire protection coating on the outside of the anti-bending coating for smoothing the wire. It is a cable and has an effect of preventing obstacles such as catching when a fiber cable is routed in a narrow space such as in a vehicle.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a sectional view of an optical fiber cable according to Embodiment 1. In FIG. 1, the core 1 is made of an acrylic resin or a polycarbonate resin. The clad 2 is made of a similar resin having a refractive index slightly lower than that of the core 1, and propagates light having a wavelength of about 660 nm in the core. Sheath 3
Is made of an elastic resin such as polyethylene resin or vinyl chloride resin, and protects the core 1 and the clad 2. The anti-bending coating 4 is made of a resin equivalent to that of the sheath 3 and has a shape in which a large number of annular slits are formed along the circumference of the surface so as to have irregularities.
The annular slit may be a V-groove.

In the first embodiment, when the optical fiber is bent due to the irregularities formed on the circumference of the surface of the anti-bending coating 4, the adjacent convex portions come into contact with each other,
Bending more than a certain angle can be prevented. The bendable radius can be adjusted by changing the interval between the projections.

FIG. 2 is a sectional view of an optical fiber cable according to a second embodiment. In FIG. 2, the core 1 is made of an acrylic resin or a polycarbonate resin. The clad 2 is made of a similar resin having a refractive index slightly lower than that of the core 1, and propagates light having a wavelength of about 660 nm in the core. The bending prevention coating 4 also serving as a sheath is made of an elastic resin such as polyethylene resin or vinyl chloride resin, and protects the core 1 and the clad 2.

In the second embodiment, the first embodiment
In addition to the effects described above, since the bending prevention coating 4 also serves as a sheath, it is possible to realize an optical fiber cable having a simple structure and low cost and having a bending prevention function.

(Embodiment 3) FIG. 3 is a sectional view of an optical fiber cable according to Embodiment 3. In FIG. 3, the core 1 is made of an acrylic resin or a polycarbonate resin. The clad 2 is made of a similar resin having a refractive index slightly lower than that of the core 1, and propagates light having a wavelength of about 660 nm in the core. The sheath 3 is made of an elastic resin such as polyethylene resin or vinyl chloride resin, and protects the core 1 and the clad 2. The anti-bending coating 4 is made of a resin equivalent to that of the sheath 3 and has a shape in which a large number of annular slits are formed along the circumference of the surface so as to have irregularities. This annular slit may be a V-groove. The wire protective coating 5 is made of a vinyl chloride resin or the like.
The unevenness of the bending prevention coating 4 is prevented from causing an obstacle such as catching.

In the third embodiment, the first embodiment
In addition to the effects described above, since the outermost protective coating is provided, it is possible to prevent an obstacle such as catching when the fiber cable is wired in a narrow space such as in a vehicle. In the third embodiment, the configuration of the first embodiment is provided with a protective coating for wiring. However, the present invention can be implemented by applying the protective coating for a wire to the configuration of the second embodiment. is there.

[0016]

As described above, according to the present invention, the following effects can be obtained by providing the anti-bending coating and the protective coating for wire application. 1. The twisting of the anti-bending wires is not required, and the allowable bending radius can be maintained by using the outer cover of the optical fiber. 2. By configuring the bending prevention coating with the same material as the sheath material that is a normal outer sheath used for an optical fiber, an optical fiber cable that maintains a permissible bending radius with a simple structure can be realized. 3. By using a protective coating for wiring as the outermost skin,
In a narrow space such as in a vehicle, there is no obstacle such as the fiber cable being caught, and the optical fiber cable can be smoothly wired.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical fiber cable according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view of an optical fiber cable according to Embodiment 2 of the present invention.

FIG. 3 is a sectional view of an optical fiber cable according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core 2 Clad 3 Sheath 4 Bending prevention coating 5 Protective coating for wiring

Claims (4)

[Claims] 1. A core for transmitting light, a clad for refracting light and transmitting light into the core, a sheath for protecting the core and the clad, and further provided outside the sheath,
An optical fiber cable having an anti-bending coating for preventing a clad and a core from bending beyond a certain bending radius. 2. The optical fiber according to claim 1, wherein the bend preventing coating has a plurality of protrusions and recesses on its surface in the circumferential direction, and the adjacent protrusions contact each other to prevent bending. cable. 3. The optical fiber cable according to claim 1, wherein the sheath is not provided, and the anti-bending coating is used instead of the sheath. 4. The optical fiber cable according to claim 1, further comprising a wire protective coating on the outside of the anti-bending coating for smoothing the wiring.