JPS63163236A - Optical temperature sensor - Google Patents

Abstract

PURPOSE:To improve the reliability of a sensor and to reduce its size by providing a control member for light which varies in light transmissivity greatly at constant temperature and an optical filter which passes light with specific wavelength in front of a reflecting part. CONSTITUTION:The reflection part 9 is constituted by arranging plural reflection parts composed of three mutually right-angled reflecting planes on the same plane and reflects incident light 13 in the opposite direction at nearly the same angle as shown by 14. A liquid crystal plate 8 is formed by charging a liquid crystal material in a glass plate and becomes opaque below the constant temperature and the incident light 13 is absorbed and scattered in the liquid crystal plate 8 and can not be transmitted through the liquid crystal plate 8. The liquid crystal plate 8 becomes transparent above the constant temperature and the incident light 13 is passed through the liquid crystal plate 8 and reflected by the reflecting plate 9 to become reflected light 14. The optical filter 10 cuts off ambient external light and passes only the light (wavelength) from a light emission part 11. Thus, the sensor is constituted and a light reception part 12 detects whether or not there is the reflected light 14 of the light 13 incident from a projection part 11 to detect the temperature of a body to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a temperature sensor for remotely detecting heating temperature.

2. Description of the Related Art Conventionally, this type of optical temperature sensor has had a configuration as shown in FIG. In FIG. 5, la.

1b is an optical fiber, 2a+2b is a rod lens, 3 is a light shielding plate, 4 is a coil-shaped shape memory alloy, and 5 is a spring. In the figure, light emitted from an optical fiber la is converted into parallel light rays 6 by a rod lens 2a, and a shielding plate 3
After passing through the hole 7 provided in the hole 7, the light is again focused by the rod lens 2b and enters the optical fiber 1b. When the measurement temperature rises, the spring 4 made of a shape memory alloy contracts, for example, so the shielding plate 3 blocks the parallel light rays 6 and no light enters the optical fiber Ib. When the measurement temperature falls, the shrinking force of the shape memory alloy spring 4 disappears, and the spring 5 contracts, causing the shielding plate 3 to return to its original position, so that the parallel light ray 6 passes through the hole 7 again and enters the optical fiber 1b. incident.

Problems to be Solved by the Invention In such a conventional configuration, in order to detect the temperature of the object to be measured at a remote location, it is necessary to wire an optical fiber between the object and the object to be measured. When measuring the temperature of the voltage section, there is a problem in that electricity leaks through the outer sheath of the optical fiber. The present invention has been made to solve these problems, and aims to provide an optical temperature sensor that can detect the temperature of an object to be measured in a simple and non-contact manner.

Means for Solving the Problems In order to solve the above problems, the present invention has a structure in which light passes through the front surface of a reflecting part that reflects light in approximately the same direction as the incident light, with the temperature reaching a certain value as a boundary. A temperature sensor is constructed by providing a light control member whose rate changes greatly (changes from transparent to opaque) and an optical filter that selects and passes only light of a specific wavelength.

Effect: With the above-described configuration, the present invention allows light of a specific wavelength emitted from a light source located at a remote location to enter, and detects whether or not the light is reflected by the reflecting section of the optical temperature sensor using the light receiving section located near the light source. This allows it to detect a constant temperature state and functions as an excellent optical temperature sensor.

Embodiment FIG. 1 is a configuration diagram of an optical temperature sensor according to an embodiment of the present invention. In Figure 1, 8 is a liquid crystal plate with a liquid crystal material sealed in a glass plate, 9 is a light reflecting plate, 10 is an optical filter that allows only light of a specific wavelength to pass through, and 1) is provided at a remote location. A light emitting section that emits light of a specific wavelength; 13 is an arrow indicating light emitted from the light emitting section 1); 12 is a light receiving section; 14 is an arrow indicating reflected light incident on the light receiving section 12.

Hereinafter, its configuration and operation will be explained with reference to FIGS. 2 and 3. The liquid crystal plate 8 and the optical filter 10 are a reflection plate 9
is located in front of the. The reflecting plate 9 has a function of reflecting light in the opposite direction at almost the same angle as the incident light. FIG. 2 shows an explanatory diagram of the structure of this reflecting plate 9. The same figure (al
1 shows a diagram of the reflecting surface of the reflecting plate 9, in which a plurality of reflecting parts 15 each consisting of three reflecting planes perpendicular to each other are arranged on the same plane. The same figure (bl is a diagram showing how the light is reflected by the reflecting section 15. The incident light 13 is completely reflected three times inside the reflecting section 15, and is emitted at a polarization angle of 180 degrees with respect to the incident light 13. The reflected light becomes reflected light 14.

This operation is completely independent of the angle of incidence of the incident light 13, and the light is always reflected in the direction of incidence.

Next, the liquid crystal plate 8 is a glass plate in which a liquid crystal material is sealed inside which allows light to pass through with almost no loss. It has the characteristic that the light transmittance changes greatly at the border, and functions as a member that controls the passage of light.

Returning to FIG. 1 again, the explanation will be continued. When the temperature of the liquid crystal plate 8 is below a certain temperature 16 shown in FIG. After passing through, the light is absorbed or scattered within the liquid crystal plate 8 and cannot pass through the liquid crystal plate 8.

When the temperature of the liquid crystal plate 8 exceeds a certain value, the liquid crystal plate 8 becomes transparent, and the light 13 emitted from the light emitting part 1) passes through the optical filter 10 and the liquid crystal plate 8, is reflected by the reflector plate 9, and becomes reflected light 14. Then, the liquid crystal plate 8 and the optical filter 10 are connected again.
and enters the light receiving section 12 provided near the light emitting section 1).

Here, the optical filter IO is provided to block out various external light in the surroundings and select only the light from the light emitting section 1).

From the above operations, the optical filter 10. The temperature of the object to be measured can be detected by using the light receiving section 12 to detect whether or not light incident from the outside is reflected by the temperature sensor composed of the liquid crystal plate 8 and the reflection plate 9.

FIG. 4 shows a block diagram according to another embodiment of the present invention. In FIG. 4, 18 is a liquid crystal material whose light transmittance changes greatly after reaching a certain temperature, and 19 is a liquid crystal material 18 contained therein.
A glass plate that allows light to pass through with almost no loss.
17 is an optical filter formed by vapor deposition on one side of the glass plate 19 and allows only light of a specific wavelength to pass through; 13 and 14 are arrows representing incident light and reflected light, respectively; 20 is the other side of the glass plate 19; This is a light reflecting section integrally provided with a prism (corner cube) section having one or more prisms (corner cubes) having three planes perpendicular to each other.

After passing through the optical filter 17, the incident light 13 having a specific wavelength is reflected by the reflecting section 20 and becomes reflected light 14 in accordance with the temperature-dependent change in the light transmittance of the liquid crystal material 18.

The basic operation of this embodiment is the same as the embodiment shown in FIG. The difference is that the optical filter 17, liquid crystal 18, and reflection section 20 are integrated, and the space between them is filled with glass, and there is no air layer, so there is a loss (Fresnel) caused by light reflection at the boundary between air and glass. There is no loss) and the light can be used effectively, and the total reflection of the prism is used as the light reflection function.

As described above, this embodiment can detect a rise in temperature above a certain value with a simple configuration based on the presence or absence of reflected light, and functions as an excellent optical temperature sensor.

In this example, a liquid crystal whose light transmittance becomes high (becomes transparent) at a temperature above a certain value was used as a member for controlling the light incident on the reflecting part. Any material and property may be used as long as it controls the passage of the material. In addition, we used glass as a material to encapsulate the liquid crystal whose light transmittance changes greatly after reaching a certain temperature, but if it is a material that allows light to pass through with almost no loss,
Any resin may be used.

Furthermore, in this example, an optical filter that selects light of a specific wavelength was provided in front of the liquid crystal whose light transmittance changes after reaching a certain temperature, but an optical filter was provided between the liquid crystal and the reflective section. Good too. In addition, in this example, as a reflection part that reflects light,
We have explained using three planes that intersect at right angles to each other and using total reflection and complete reflection of light, but what kind of reflecting part can be used as long as it reflects light in almost the same direction as the incident light? Needless to say, it's a good thing.

Effects of the Invention As described above, according to the present invention, the temperature of the object to be measured is detected based on the presence or absence of reflected light using a light reflecting section. It has an effect you don't need.

Furthermore, since a reflective part that reflects in almost the same direction as the incident light is used as a light reflecting part, there are fewer restrictions on the position of the light emitting part for the light to enter the reflective part, and there is no need for optical axis adjustment. . In addition, as the light blocking function uses a material (liquid crystal) that controls the passage of light at a certain temperature, the structure is simple, highly reliable, and can be miniaturized. , it is possible to provide an optical temperature sensor that is superior to conventional ones.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an optical temperature sensor according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the configuration of a reflecting section in an embodiment of the present invention, and FIG. 3 is an explanation of the characteristics of a liquid crystal in an embodiment. figure,
FIG. 4 is a configuration diagram of an optical temperature sensor according to another embodiment of the present invention, and FIG. 5 is an explanatory diagram of a conventional optical temperature sensor. 8...Liquid crystal plate, 9...Light reflecting plate, 1
0... Optical filter, 1)... Light emitting section, 12... Light receiving section, 13... Arrow indicating emitted light, 14...・Arrow indicating reflected light, 15・
...Reflector, 16...Arbitrary constant temperature,
17... Optical filter, 18... Liquid crystal material, 19... Glass plate, 20... Light reflecting section. Name of agent: Patent attorney Toshio Nakao 1 person 8-Night crystal plate q--Ikkou's 301) anti-7o--1 optical folder 1/-Light emitting part 12- Light receiving part 13-11 light emitting part 14 - Arrow showing m - Arrow showing reflected light Figure 1 q - M - Light counter plate 13 - 1 Arrow showing incident light / 4 - M - Arrow showing reflected light 15 - Reflection part No. Figure 2 Figure 3 1111 Liquid crystal user friend (°C) f8-11 Liquid crystal #condensation/9--Ichiriki゛°Last version 2D--Ikkou's reflection section Figure 4 Figure 5

Claims (3)

[Claims] (1) A reflecting section that reflects light in substantially the same direction as the incident light; a light control member that controls the amount of light that enters the reflecting section when a temperature reaches a certain value; An optical temperature sensor comprising an optical filter that selects a wavelength. (2) The optical temperature sensor according to claim (1), wherein the light control member is composed of a liquid crystal that transmits or blocks light at a certain temperature. (3) The optical temperature sensor as set forth in claim (1), wherein the reflecting section is comprised of one or more sets of three light reflecting surfaces that intersect at right angles to each other.