JP3024516B2 - Temperature detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device for detecting an abnormal temperature of an object to be measured.

[0002]

2. Description of the Related Art When detecting the temperature of an object to be measured, it has been conventionally considered to use an optical fiber as an effective means, particularly in a noisy environment or in a place where there is a risk of explosion. As described in JP-A-92737, a temperature indicator such as a thermal paint is used as a temperature sensor of a measured portion, and the temperature indicator is irradiated with a light beam from a light source via an optical fiber for illumination. The reflected light, whose color changes based on the change, is guided to the color identification light-receiving element via the optical fiber for light reception, and the identification signal of the color identification light-receiving element is processed and processed as color data in response to the alarm signal by the alarm generator. The sensor has a structure in which the temperature indicator attached to the measurement unit is covered with the sensor unit cover housing or the temperature indicator is attached to the bottom inside the sensor head housing. Those having a part or the real No. 3-51
As described in Japanese Patent Publication No. 338, a device has been proposed in which a temperature rise is detected by a color change of a thermo label.

[0003]

However, when the temperature indicator is used as described above, the reflected light due to the color change of the temperature indicator is received by the optical fiber for light reception. Since the light cannot be received by the fiber, there is a possibility that the color discrimination of the reflected light by the color discrimination light-receiving element may be unreliable. In the case of using a thermo label, the chemical substances that can be used as the thermo label are limited.

An object of the present invention is to enable an abnormal temperature of an object to be measured to be easily and more reliably detected with a simple configuration.

[0005]

[0006]

[0007]

Means for Solving the Problems The invention 請 Motomeko 1 described,
A light source, a light receiving element, first and second optical fibers connected to the light source and the light receiving element, respectively, and a third optical fiber connected to the first and second optical fibers via an optical coupler. An optical fiber, a temperature sensor provided at the tip of the third optical fiber, and an identification circuit for detecting a change in intensity of the reflected light received by the light receiving element, wherein the temperature sensor has an open end. And a waterproof cap into which the tip of the third optical fiber is inserted through the opening of the container and inserted into the inside of the container through a through hole at the center, and the third optical fiber inside the container. A temperature-sensitive element is provided in a space between the light reflector provided at a position facing the distal end face and reflecting light from the third optical fiber toward the third optical fiber and the waterproof cap inside the container. Filled with discoloring material Is characterized in that the light absorption and scattering with respect to light in a specific wavelength is constituted by a thermosensitive part changes color easily change color by.

Accordingly, the return of the reflected light by the light reflector to the third optical fiber is greatly increased as compared with the case without the light reflector, and this increase causes the temperature-sensitive portion of the temperature-sensitive part due to the temperature rise of the object to be measured. Since the color change of the reflected light due to the color change of the thermosensitive color change material can be reliably detected and the temperature rise of the measured object can be detected, the abnormal temperature of the measured object can be detected with a simple configuration without complicating the configuration. Detection can be performed easily and reliably.

[0009] At this time, since the provided an air layer temperature sensing portion of the temperature sensor, can alleviate the volume expansion of the temperature sensing portion due to temperature rise, thermochromic in the space between the container interior of the waterproof cap As in the case where the material is completely filled, it is possible to prevent the temperature-sensitive portion from being damaged due to expansion.

Further, as in claim 2, wherein, when cutting the tip of the third optical fiber introduced into the temperature sensing portion at an angle,
The reflection at the end face of the third optical fiber can be suppressed.

By the way, as described in claim 3 , the first,
The third optical fiber or the second and third optical fibers are one optical fiber, and the one optical fiber is connected to the remaining second optical fiber or the first optical fiber in the optical branching coupler. may ends are welded, as claimed in claim 4, wherein the optical branching coupler may be an optical waveguide type or beam splitter type.

[0012]

FIG. 1 is a partial sectional view of an embodiment of the present invention, and FIG. 2 is a schematic view.

The schematic configuration of the entire apparatus will be described.
As shown in FIG. 2, a first optical fiber 2 is connected to a light source 1 composed of an LED or other monochromatic light source or a white light source,
A second optical fiber 4 is connected to a light receiving element 3 composed of a phototransistor, a photodiode, and the like.
The second optical fibers 2 and 4 and the third optical fiber 5 are connected by an optical branching coupler (hereinafter referred to as an optical coupler) 6,
A temperature sensor 7 provided at the tip of the third optical fiber 5 is provided.

Here, the first, second, and third optical fibers 2, 4, and 5 are referred to for convenience.
The optical fibers 2 and 5 or the second and third optical fibers 4 and 5 are one optical fiber. In the optical coupler 6, the one optical fiber and the remaining second optical fiber 4 or The end of one optical fiber 2 is welded. When the optical coupler 6 is of an optical waveguide type or a beam splitter type, the three optical fibers 2 described above are used.
The optical couplers 4 and 5 are connected via the optical coupler 6, and it is a matter of course that such an optical coupler 6 may be used.

The light from the light source 1 is incident on the incident end of the first optical fiber 2 and is guided to the temperature sensor 7 via the optical coupler 6 and the third optical fiber 5, and is stored in a container 9 described later. The light reflected by the light reflector 14 is received by the light receiving element 3 via the third optical fiber 5, the optical coupler 6, and the second optical fiber 4, and the intensity change of the reflected light received by the identification circuit 8 is identified. , A temperature rise of the object to be measured is detected.

At this time, the return light to the third optical fiber 5 due to the reflection at the light reflector 14 increases, and the increase in the temperature of the object to be measured causes the temperature sensing portion 13 in the temperature sensor 7 to be described later to increase. An abnormal temperature of the measured object can be detected by reliably detecting a change in the intensity of the reflected light due to a color change of the thermosensitive color changing material.

As shown in FIG. 1, the temperature sensor 7 has a container 9 having an opening at one end and made of a metal such as copper or aluminum, and a through hole 10 at the center, and is provided inside the opening of the container 9. A waterproof cap 11 made of rubber or the like inserted therein, and a thermo-sensitive discoloration made of PSD-RR (fluoran leuco compound), stearyl acid phosphate, and Smithope, which change color from red to black at 70 ° C. for white light, for example. The material is filled in the space between the waterproof cap 11 and the inside of the container 9 while leaving the air layer 12, leaving the air layer 12 discolored to a density at which light absorption and scattering easily change with respect to light of a specific wavelength due to a rise in temperature. The temperature control section 13 includes a heating section 13 and a light reflector 14 provided at a position facing the distal end face of the third optical fiber 5 inside the container 9.
Is reflected by the light reflector 14 to the distal end surface of the third optical fiber 5.

Here, the combination of the light from the light source 1 and the thermochromic material is desirably as shown in Table 1, for example. The light source 1 may be white light or monochromatic light such as red light, green light or yellow light. It is preferable to use a thermosensitive color-changing material that changes color, discolors, or loses color when heated to a high temperature as shown in Table 1.

[0019]

[Table 1]

Table 1 shows the color of the emitted light before and after the color change and the amount of the emitted light when the color of the thermosensitive color changing material changes (for example, from colorless to red) in a state where the incident light of each color is used. In particular, the amount of emitted light indicates a change in the amount of light after the color change with reference to the state before the change in color. For example, “green small” indicates that the light amount of the green component is smaller than before the change, and “green large”. "Indicates that the light amount of the green component increases from before the change. In Table 1, “before discoloration” means a state at normal temperature, and “after discoloration” means a state at a high temperature of, for example, 60 ° C. or more.

As the thermosensitive color changing material, a material whose light absorption changes before and after the color change in relation to the light source 1 may be selected.
For example, when red light is used as the light source 1, the colorless or red color that normally has no absorption in the wavelength region and has transparency is used.
Desirably, the material reversibly changes to green, black, or another color in which red light is easily absorbed. Specifically, materials other than those described above may be used as shown in Table 2, and as shown in Table 2, As a material that changes color from colorless to red as a result, PSD-R (fluoran leuco compound), lauryl gallate, and toluene may be used, but the materials are not particularly limited to those shown in Table 2.

[0022]

[Table 2]

Therefore, the third light reflected by the light reflector 14 is
Return to the optical fiber 5 greatly increases as compared with the case where the light reflector 14 is not provided. Due to this increase, the reflection due to the color change of the thermosensitive coloring material of the thermosensitive part 13 due to the temperature rise of the measured object. Since the temperature rise of the object to be measured can be detected by reliably detecting the change in the intensity of light, the abnormal temperature of the object to be measured can be easily and reliably detected with a simple configuration without complicating the configuration. Can be.

Further, since the air layer 12 is provided in the temperature sensing portion 13, the volume expansion of the temperature sensing portion 13 due to a temperature rise can be reduced, and the temperature sensing space in the space between the inside of the container 9 and the waterproof cap 11 can be reduced. As in the case where the discoloring material is completely filled, it is possible to prevent the temperature-sensitive portion 13 from being damaged due to expansion.

Further, by cutting the tip of the third optical fiber 5 introduced into the temperature sensing section 13 obliquely, reflection at the end face of the third optical fiber 5 can be suppressed.

The container 9 may be made of glass or plastic, in addition to the above-described metals, and does not chemically react with the thermochromic material, but chemically with the fluid to be measured. Any material that does not react and satisfies the condition that it can be used within the detection temperature range may be used.For example, when glass is used, the thermal conductivity is lower than that of metal, so that a gradual response to temperature rise is required. Suitable for the case.

When the container 9 is transparent, the temperature sensing part 13
The color change of the thermochromic material can be visually observed from the outside,
On the other hand, if the container 9 is opaque, disturbance light from the outside can be blocked, so that the detection accuracy can be improved.

Furthermore, the container 9 may have a shape having a concave curved bottom surface. In this case, the third optical fiber is formed by a light reflector 14 provided along the concave curved bottom surface of the container 9. There is an advantage that the reflected light can be effectively condensed on the tip end surface of the light emitting element 5.

[0029]

[0030]

As it is evident from the foregoing description, according to the first aspect of the invention, a significant increase compared with the case back portion of the third optical fiber of the reflected light by the light reflector without light reflector Because of this increase, it is possible to reliably detect a change in the intensity of reflected light due to a color change of the thermosensitive coloring material in the temperature-sensitive part due to a rise in the temperature of the DUT, thereby detecting the rise in the temperature of the DUT, thus complicating the configuration. , The abnormal temperature of the measured object can be easily and reliably detected with a simple configuration.

[0031] At this time, since the provided an air layer temperature sensing portion of the temperature sensor, can alleviate the volume expansion of the temperature sensing portion due to temperature rise, thermochromic in the space between the container interior of the waterproof cap As in the case where the material is completely filled, it is possible to prevent the temperature-sensitive portion from being damaged due to expansion. In this case,
As described in claim 3, the first and third optical fibers or the
2. The third optical fiber is one optical fiber,
This one optical fiber is connected to the second
The end of the optical fiber or the first optical fiber is welded.
The optical branching / coupling coupler may be configured as described in claim 4.
Optical waveguide type or beam splitter type
Is also good.

Further, as described in claim 2 , by cutting the tip of the third optical fiber introduced into the temperature sensing portion obliquely, reflection at the end face of the third optical fiber can be suppressed.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an embodiment of the present invention.

FIG. 2 is a schematic diagram of one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 light source 2, 4, 5 first, second, third optical fiber 3 light receiving element 6 optical coupler (optical branching coupler) 7 temperature sensor 8 identification circuit 9 container 10 through hole 11 waterproof cap 12 air layer 13 temperature sensitivity Part 14 Light reflector

Claims (4)

(57) [Claims] A light source, a light receiving element, the light source, and the light receiving element;
First and second optical fibers connected to respective light receiving elements
And the first and second optical fibers via an optical branching coupler.
A third optical fiber connected to the
A temperature sensor provided at the tip of the
An identification circuit that detects changes in the intensity of reflected light
The temperature sensor comprises a container having an open end, and an inside of the container through an opening of the container.
The third optical fiber is inserted into the
A waterproof cap into which the tip of the bath is introduced, and the inside of the container
The third optical fiber is provided at a position facing the distal end face of the third optical fiber.
The light from the third optical fiber is transmitted to the third optical fiber.
A light reflector that reflects toward the base, and the waterproof key inside the container.
The space between the cap and the thermosensitive coloring material is filled
Changes in light absorption / scattering for light of specific wavelength due to increase in degree
An air layer is provided in the temperature- sensitive portion of the temperature sensor.
A temperature detecting device. 2. A temperature sensing device according to claim 1, wherein the distal end of said introduced into the temperature sensing portion the third optical fiber is cut diagonally. 3. The optical fiber according to claim 1, wherein the first or third optical fiber or the second or third optical fiber is a single optical fiber. 3. The temperature detecting device according to claim 1, wherein an end of the optical fiber or the first optical fiber is welded. 4. An assembly as claimed in claim 1 or 2, wherein said optical branching coupler is an optical waveguide type or beam splitter type.