JPH02108008A - Leak light fiber cable - Google Patents

Abstract

PURPOSE:To decrease the number of optical fibers and to allow arbitrary setting of light emitting parts without being limited by changing the outside diameter of a central tension member around which optical fibers are doubled and twisted. CONSTITUTION:A piece or plural pieces of the optical fibers 1 are doubled and twisted around the tension member 2 which is varied in the outside diameter in the longitudinal direction, by which the bending radius of the optical fibers 1 is changed and the quantity of the visible light transmitting in cores 11 and leaking to the outside is controlled. The transmission loss, i.e. the leak light from the cores 11 increase as the bending radius is smaller at this time. The bending radius of the optical fibers 1 is changed by changing the outside diameter of the central tension member 2. The quantity of the visible light transmitting in the cores 11 and leaking to the outside is controlled in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a leaky optical fiber cable used for display purposes.

(Prior Art) FIG. 4 is an explanatory diagram of an example of a conventional art that uses optical fibers for display purposes.

In the drawing, (21) is a plurality of optical fibers (23)
(22) is a light source, (24) is a light emitting display section. As shown in the drawing, a light source (
22), the light is input to the optical fiber (23). This incident light is transmitted through the optical fiber (23) and is emitted from the other end. This emitted light was used as a display.

(Problem to be Solved) In the above-mentioned conventional technology, the light emitting display section (24) is an aggregate of the end faces of the optical fibers (23). There was a problem that optical fiber was required.

(Means for Solving the Problems) The present invention solves the above-mentioned problems and provides a leaky optical fiber cable that uses a small number of optical fibers and enables selective luminescence display. , one or more optical fibers with a coating layer made of a material that is transparent to the wavelength of visible light transmitted through the core of the optical fiber, with a central tension that has an outer diameter that varies along its length. This is a leaky optical fiber cable that changes the bending radius of the optical fiber by twisting it around the members, thereby controlling the amount of visible light transmitted through the core that leaks to the outside.

As shown in FIG. 3(A), when the optical fiber (+) is in a straight state, light is transmitted within the core (II). However, in a bent state as shown in FIG. At this time, when a material that transmits radiation light is used as the covering layer (I3) on the cladding (12), the radiation passes through the covering layer (13) and leaks to the outside.

The present invention takes advantage of such properties of optical fibers, and FIG. FIG. 2 is a cross-sectional view of an optical fiber.

As shown in the drawing, the outer diameter was varied in the length direction (d
+>d2) The bending radius of the optical fiber (1) is changed by twisting one or more optical fibers (1) around the central tensilon member (2).

As the optical fiber (1), as shown in the same figure (b),
A covering layer (13) made of a material transparent to the wavelength of visible light transmitted through the core (11) is provided on the cladding (12).

In this way, by twisting the optical fiber (+) around the central tensilon member (2), bending is imparted to the optical fiber (1). At this time, by varying the outer diameter of the central tension member (2) in the length direction, the bending radius of the optical fiber (+) is changed and the amount of visible light transmitted through the core leaking to the outside is controlled.

(Function) In a general optical fiber, the bending radius and the amount of light loss have a relationship in which the transmission loss is proportional to the square of the bending radius. The smaller the bending radius, the greater the transmission loss, that is, the more light leaks from the core.

On the other hand, the bending radius of the optical fibers twisted around the central tension member is given by the following equation.

R = (P'/4πtr) + r where R: bending radius P: v alignment pitch r: rl+r2 rI = center tension member radius r2: optical fiber radius Therefore, change the outer diameter of the center tension member (2) This allows the bending radius of the optical fiber (1) to be changed.

Utilizing this relationship, as shown in Figure 1, the amount of light leaking can be adjusted by twisting optical fibers (+) around the central tension member (2), which has different outer diameters in the length direction. becomes possible.

(Embodiment) FIG. 2 is a cross-sectional view of an embodiment of the leaky optical fiber cable of the present invention.

Optical fibers (1) shown in Figure 1 (b) are placed around the central tension member (2) with different outer diameters in the length direction.
Six fibers are twisted together and a sheath (3) made of a material that is transparent to the wavelength of visible light that transmits the core (11) of the optical fiber (+) is provided on the outside to form a cable.

The outer diameter of the tension member (2) at the center is small in the part where the optical fiber (+) is made to emit light for display purposes, and large in the part where it is not necessary to make it emit light.

(Effects of the Invention) As explained above, according to the leaky optical fiber cable of the present invention, it is possible to selectively display light emission by changing the outer diameter of the central tensilon member around which optical fibers are twisted. Therefore, the number of optical fibers is smaller than the conventional method in which optical fibers emit light from their end faces, and the light emitting portion is not limited and can be set arbitrarily.

Furthermore, since the outer diameter of the tensile member is changed as a means for selectively emitting light, it is easy to manufacture without requiring new equipment for manufacturing.

[Brief explanation of the drawing]

FIG. 1(a) is a side view of a specific example of the leaky optical fiber cable of the present invention, and FIG. 1(b) is a cross-sectional view of the optical fiber. FIG. 2 is a cross-sectional view of an embodiment of the leaky fiber optic cable of the present invention. FIG. 3(A) is an explanatory diagram of optical transmission in an optical fiber, and FIG. 3(B) is an explanatory diagram of optical leakage in the optical fiber. FIG. 4 is an explanatory diagram of an example of a conventional technique using optical fibers for display purposes. DESCRIPTION OF SYMBOLS 1... Optical fiber, II... Core, 12... Clad, 13... Covering JiJ, 2... Tension member, 3... Sheath.

Claims (2)

[Claims] (1) One or more optical fibers are coated with a coating layer made of a material that is transparent to the wavelength of visible light that is transmitted through the core of the optical fiber. A leaky optical fiber cable characterized in that the bending radius of the optical fiber is changed by twisting it around a tension member, thereby controlling the amount of visible light transmitted through the core that leaks to the outside. (2) Multiple optical fibers are twisted around a central tension member with different outer diameters in the length direction, and a sheath made of a material transparent to the wavelength of visible light that transmits the core of the optical fiber is placed on the outside. Claim (1)
)Leaky fiber optic cable.