JPH07151615A - Optical-fiber sensor - Google Patents

Abstract

PURPOSE:To obtain an optical-fiber sensor which does not cause any performance deterioration nor insufficient insulation and can detect external forces from all directions by using silicone rubber for the core of its detection optical fiber and elastomer for the clad of the fiber. CONSTITUTION:The core 2 of the optical fiber 1 for detection of an optical-fiber sensor is made of silicone rubber composed of dimethyl siloxane polymer, etc., and the clad 3 of the fiber 1 is made of elastomer which is composed of a thermoplastic fluoroplastic elastomer, etc., and has a refractive index lower than that of the silicone rubber. The reflecting member 4 of the fiber 1 is composed of an aluminum plate, etc. When no external force is applied to the fiber 1, light emitted from a light source 7 is directed to the core through an optical fiber 5 for input and reflected by the reflecting member 4 while being refracted through the core 2. The reflected light is directed to a photodetector 8 through an optical fiber 6 for reception while being refracted through the fiber 1. When an external force is applied to the fiber 1, the core 2 and clad 3 are deformed and the light leaks out from the fiber 1. Therefore, the external force can be detected from a decrease in detected light quantity of the photoreceptor 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber sensor which can be used as a pressure switch or the like.

[0002]

2. Description of the Related Art Conventionally, a switch having a mechanical movable contact structure such as a micro switch or a tape-like switch has been widely used in various mechanical devices, automobiles and the like.

A pressure conductive switch in which conductive rubber is interposed between a pair of electrodes has also been proposed (Japanese Patent Laid-Open No. 61-61).
143913).

[0004]

In such a conventional pressure switch, when it is used outdoors, in water, or when it is splashed with water, the electrodes and contacts are oxidized to deteriorate the performance and cause insulation failure. There was a problem.

Further, if waterproofing is applied to prevent the influence of water, the structure of the switch becomes complicated and the size becomes large.

Further, the conventional pressure switch operates only by the pressure in a fixed direction, and the switch cannot be operated by detecting an external force from any direction.

An object of the present invention is to solve the above-mentioned problems of the conventional pressure switch, and to prevent the deterioration of performance and insulation failure due to water, and to detect an external force from any direction. To provide.

[0008]

As a result of intensive studies to achieve the above object, the present inventor has noticed that the amount of light transmission changes when an elastic optical fiber is deformed. Considering using it as a pressure sensor,
The present invention has been completed.

That is, in the present invention, the core is silicone rubber,
The cladding is made of an elastomer having a refractive index lower than that of the silicone rubber, and at the other end of the detection optical fiber having a reflecting member provided at one end of the core, a light receiving optical fiber connected to a light source and a light receiving optical fiber connected to a light receiving body are provided. The optical fiber sensor is characterized in that and are provided.

[0010]

The present invention takes advantage of the phenomenon that the amount of light transmission in the optical fiber changes when the elastic optical fiber is deformed.

Since the core of the optical fiber for detection used in the present invention is made of silicone rubber and the clad is made of an elastomer having a lower refractive index than the silicone rubber, it is extremely elastic and easily deformed by an external force.

Due to this deformation, the amount of light passing through the optical fiber, that is, the output of the light beam is reduced. Therefore, if light is sent from the light source provided at one end of the optical fiber to another photodetector located on the same side as the light source via the reflection plate in the detection fiber, the photodetector receives light due to deformation of the photodetector. It detects that the amount has changed and an external force has been applied to the optical fiber. The switch may be operated according to the change in the amount of light received by the light receiver.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of the optical fiber sensor of the present invention, and FIG. 2 is a transverse sectional view showing an example of the detection optical fiber used in the present invention.

In FIG. 1, 1 is an optical fiber for detection,
2 is a core, 3 is a clad, 4 is a reflecting member, 5 is an optical fiber for receiving light, 6 is an optical fiber for receiving light, 7 is an LED, L
A light source such as D, 8 is a light receiving body such as a photodiode or a phototransistor, 9 is a detection circuit, and 10 is a connector.

As shown in FIG. 1 or 2, the detection optical fiber 1 is composed of a core 2 and a clad 3. The core 2 is made of silicone rubber, and the clad 3
Is made of an elastomer having a lower refractive index than the silicone rubber of the core 2. Examples of the silicone rubber used for the core 2 include dimethyl siloxane polymer, phenyl group- or naphthyl group-containing siloxane polymer, and methyl vinyl siloxane polymer.

For the clad 3, an elastomer such as a fluorine elastomer having a refractive index lower than that of the silicone rubber used for the core 2 is used.

The fluoroelastomer used for the clad 3 may be, for example, a fluororesin thermoplastic elastomer. In particular, a fluororesin portion (hard segment, for example, ethylene-tetrafluoroethylene copolymer) and a fluororesin are particularly preferable. A fluoroelastomer composed of a rubber portion (soft segment, for example, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer) is preferably used. An aluminum plate, a stainless steel rod, or the like is used for the reflecting member 4.

In order to manufacture the optical fiber for detection 1 used in the present invention, first, a tube having a diameter of 1 to 50 mm and a thickness of 0.2 to 2.5 mm is molded with an elastomer serving as a clad component, and then. An aluminum plate or a stainless rod (having a thickness of about 0.2 mm to 2.5 mm) as a reflecting member having a diameter slightly larger than the inner diameter of the tube is inserted.

Next, a liquid silicone rubber precursor may be injected therein, and the silicone rubber precursor may be polymerized and cured by any means such as heating, ultraviolet rays or radiation to form a core component. It is also possible to perform extrusion molding by co-extruding the core component and the clad component.

In the present invention, the detection optical fiber 1
It is preferable that the core 2 and the clad 3 are not in close contact with each other and the interface is separated because the change in the amount of light transmission becomes large when deformed.

Next, the operation of the sensor of the present invention will be described. First, the case of FIG. 1 in which an external force is not applied to the detection optical fiber 1 will be described.

Light emitted from the light source (LED) 7 of FIG. 1 is guided to the core 2 of the detection optical fiber 1 by the light entering optical fiber 5, and is reflected by the reflecting member 4 while being refracted inside the core. Further, the reflected light is refracted inside the core, is incident on the light receiving optical fiber 6, and is then guided to the light receiving body (photodiode) 8.

Next, the case of FIG. 3 in which an external force is applied to the detection optical fiber 1 will be described. In this case, the core 2 and the clad 3 of the detector are deformed by an external force,
Light leaks inside the core. As a result, the amount of light detected by the light receiver (photodiode) 8 is reduced as compared with the case of FIG.

The detection circuit 9 compares the difference in the amount of light between the case of FIG. 1 in which no external force is applied to the detection optical fiber 1 and the case of FIG. Is being detected.

Further, although FIG. 3 shows the case where an external force is applied to the detection optical fiber 1 from one direction, it is possible to detect similarly when an external force is applied from both sides as shown in FIG.

In the present invention, for example, the diameters of the light entering optical fiber 5 and the light receiving optical fiber 6 are each 0.
5 mm, the diameter of the core 2 is 1 mm, and the thickness of the cladding is 0.
5 mm, the reflecting member can be a cylindrical object having a diameter of 1 mm and a thickness of 0.5 mm.

Further, here, the core 2 of the optical fiber 1 for detection, the optical fiber 5 for receiving light, and the optical fiber 6 for receiving light are joined by the connector 10, but they may be joined by means such as a cylindrical cap. it can.

[0028]

According to the optical fiber sensor of the present invention,
Since the signal medium is light rather than electricity, external force detection can be performed outdoors, in water, or in a place where water is splashed, without the influence of water. Moreover, since the optical fiber is deformed by an external force applied from any direction, the external force from any direction can be detected.

Further, since it is excellent in elasticity and flexibility, it can be easily used even in a complicated installation place.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an optical fiber sensor of the present invention.

FIG. 2 is a cross-sectional view showing an example of a detection optical fiber used in the present invention.

FIG. 3 is a state diagram when an external force is applied to the detection optical fiber used in the present invention.

FIG. 4 is a state diagram when an external force is applied to the detection optical fiber from both sides.

[Explanation of symbols]

 1 Optical Fiber for Detection 2 Core 3 Clad 4 Reflecting Member 5 Optical Fiber for Light Input 6 Optical Fiber for Light Reception 7 Light Source 8 Photoreceptor 9 Detection Circuit 10 Connector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G02B 6/12 6/42 7139-2K H01H 13/20 9177-5G

Claims (1)

[Claims] 1. A light inputting device, wherein a core is made of silicone rubber, a clad is made of an elastomer having a refractive index lower than that of the silicone rubber, and a reflection member is provided at one end of the core, and the other end of the detection optical fiber is connected to a light source. An optical fiber sensor provided with an optical fiber and a light receiving optical fiber connected to a light receiver.