JPH0566159A - Temperature measuring device - Google Patents

Abstract

PURPOSE:To stabilize temperature measurement and improve the precision of temperature measurement. CONSTITUTION:In a temperature sensitive element 7 adhered to the end surface of a light emitting optical fiber 2, the wavelength transmittance of a transmitted light is changed by a temperature change. A reflecting film 8 evaporated on the back surface of the temperature sensitive element 7 reflects the emitted light from the light emitting optical fiber 2. The reflected emitted light forms an incident light and enters to two incident optical fibers 3, 4. Since the incident optical fibers 3, 4 are provided in the optical path area of the incident light, the transmitted light of the same intensity enters to the optical fibers 3, 4. The transmitted lights are collected to one by an optical binder, and received by a photodiode, and the temperature is measured by its optical quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection / transmission system in which an outgoing optical fiber and an incoming optical fiber are arranged in parallel and outgoing light transmitted through a temperature sensitive element is reflected by a reflecting member and introduced into the incoming optical fiber. Temperature measuring device.

[0002]

2. Description of the Related Art A conventional reflection / transmission type temperature measuring device will be described with reference to the drawings. FIG. 7 is an external perspective view of a conventional temperature measuring device, FIG. 8 is a conceptual diagram for explaining a measuring method by the device, FIG. 9 is a side sectional view of the same, and FIG. 10 is a front view of the same. In these figures, 2 is an output optical fiber, 3 is an input optical fiber, 7 is a temperature-sensitive element in which the wavelength of transmitted light changes with temperature change, which is joined to the end faces of these fibers, and 8 is a temperature-sensitive element. 7 is a reflective film deposited on the back surface of 7. LED at the entrance end of the output optical fiber 2
A (light emitting diode) is provided, and the emitted light L emitted from this LED passes through the emitting fiber 2 and is emitted into the temperature sensitive element 7. The emitted light L emitted into the temperature sensitive element is reflected by the reflection film 8 to become incident light 1 which is introduced into the incident optical fiber 3. Outgoing light L and incident light l in the temperature sensitive element 7
The wavelength of the transmitted light changes depending on the temperature change. Along with this change in the transmitted light wavelength, the relationship between the emitted light intensity and the incident light intensity at a certain temperature is determined. Therefore, the photodiode PD arranged at the exit end of the incident optical fiber 3
The temperature is measured by detecting the intensity of light received at.

[0003]

By the way, a light ray incident on the boundary surface of a medium having a different refractive index is refracted according to the so-called Snell's law. The refraction angle is determined by the refraction indexes of both. From the fiber core 2a of the emitting optical fiber 2 to the temperature sensitive element 7 made of semiconductor-doped glass
The emitted light L emitted inward has a refraction angle θ and is diffused as shown in FIG. This refraction angle θ has a refractive index of 1.59.
When the fiber core 2a and the semiconductor-doped glass having a refractive index of 1.55 are used, the angle is 18.82 °. When the outgoing light L ₂ diffused at the refraction angle θ reaches the reflective film 8, it becomes an optical path region having an area α. On the other hand, the area of the optical path region of the outgoing light L _{2 in} the reflection film 8 is β, which corresponds to the area of the optical path region of the outgoing light L ₁ that enters the optical fiber 3 for incidence as the incoming light l ₁ . Therefore, the amount of incident light incident on the incident optical fiber 3 is extremely smaller than the amount of emitted light emitted from the emitting optical fiber 2, which reduces the transmitted light intensity of the incident light. As a result, the sensitivity of the transmitted light received by the photodiode PD also decreases, and the temperature measurement accuracy decreases. In order to make up for this drawback, it has been proposed to increase the number of optical fibers for emission and accordingly increase the number of LEDs to increase the amount of emitted light. It has the drawback that it cannot measure temperature. The present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a temperature measuring device with high accuracy and capable of stable temperature measurement.

[0004]

In order to achieve this object, the present invention is directed to an output optical fiber and an input optical fiber arranged in parallel, and to a temperature change bonded to the end faces of these fibers. A temperature-sensitive element whose transmitted light wavelength changes,
A temperature measuring device, which is disposed on the back surface of the temperature-sensitive element and includes a reflecting member that introduces the light emitted from the emission optical fiber into the incident optical fiber as the incident light, and measures the temperature from the change in the output of the incident light. A plurality of incident optical fibers are arranged in the optical path region of the incident light, and a coupling means for optically coupling the plurality of incident lights guided to the plurality of incident optical fibers is provided. ..

[0005]

In the present invention, a plurality of incident optical fibers are arranged in the optical path region of the incident light, and a coupling means for optically coupling the plurality of incident light guided to the plurality of incident optical fibers is provided. Therefore, a large amount of incident light is guided.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an external perspective view of a temperature measuring device according to the present invention,
FIG. 2 is a conceptual diagram for explaining a measuring method for measuring with the same device, FIG. 3 is a front view of the same, and FIG. 4 is a comparison diagram of incident light amounts in a conventional device and a device according to the present invention. In these figures, the same components as those of the conventional technique are designated by the same reference numerals, and detailed description thereof will be omitted. The feature of the present invention resides in that, in addition to the conventional incident optical fiber 3, an incident optical fiber 4 having the same function and shape is arranged in parallel with the incident optical fiber 3 and the outgoing optical fiber 2. .. These three optical fibers 2, 3 and 4 are bundled by a sleeve 5. The newly arranged incident optical fiber 4 is arranged in the optical path region where the outgoing light from the outgoing optical fiber 2 is reflected by the reflective film 8 and becomes incident light. That is, β ₂ in the drawing, which is the optical path region on the reflection film 8 corresponding to the incident light introduced into the incident optical fiber 4, is positioned within α which is the optical path region on the reflection film 8 for the outgoing light. An incident optical fiber 4 is provided.

The incident light reflected by the reflecting film 8 is introduced into both the incident optical fibers 3 and 4 arranged as described above. The optical fibers 3 and 4 for both incidences are guided to the photodiode PD as one fiber by the optical coupler 9. Therefore, as for the transmission intensity of the incident light guided to the photodiode PD, as shown in FIG. 4, about twice the sensitivity is obtained as compared with the conventional one using one incident fiber.
FIG. 4 is a diagram for comparison between the conventional example and this example, in which the vertical axis represents the light intensity of incident light and the horizontal axis represents temperature.
The broken line 16 shows the conventional one, and the solid line 15 shows the light intensity characteristic with respect to the temperature change of this embodiment. Further, by using three optical fibers and bundling them with a sleeve, the mechanical strength is increased, and the temperature-sensitive element is easily joined vertically to the bunched fibers, so that the workability is also improved.

FIG. 5 is a front view showing a second embodiment of the temperature measuring device according to the present invention. In this embodiment, the use of two incident optical fibers 3 and 4 is the same as in the first embodiment. In this embodiment, three fibers are arranged in a row and the optical fiber 2 for emission is arranged at the center and bundled by a sleeve 20 having a rectangular cross section. By doing so, it is possible to appropriately select when the installation condition of the fiber changes. FIG. 6 is a front view showing a third embodiment of the temperature measuring device according to the present invention. In this embodiment, six incident optical fibers 30 are used, and these incident optical fibers 30 are annularly arranged around the emission optical fiber 2 and bundled by a sleeve 31. By increasing the number of the incident optical fibers 30, the transmission intensity of the incident light is increased in proportion to the increased number of the fibers 30, and the mechanical strength of the entire fiber is also increased. Although the number of the incident optical fibers is two and six in these examples, the number of the incident optical fibers is not limited to this, and the number of the incident optical fibers may be appropriately selected within the range of the optical path region of the incident light. The required light intensity of the incident light can be obtained.

[0009]

As described above, according to the present invention, a plurality of incident optical fibers are arranged in the optical path region of the incident light, and a plurality of incident light guided to the plurality of incident optical fibers are provided. Since it is optically coupled, the intensity of the incident light can be increased while the structure is simple, and since all of these incident lights pass through the temperature sensitive element, the sensitivity of the incident light is improved. To do. Further, since only one light source for incident light is used, fluctuations in the light amount of the emitted light due to instability of the light source are small, and therefore the light amount of the incident light is not affected so that stable temperature measurement is possible. Further, by using a plurality of fibers, the mechanical strength can be maintained, and at the same time, it becomes easy to join the temperature-sensitive element vertically, and therefore, the workability is also excellent.

[Brief description of drawings]

FIG. 1 is an external perspective view of a first embodiment of a temperature measuring device according to the present invention.

FIG. 2 is a conceptual diagram illustrating a measuring method according to a first embodiment of a temperature measuring device according to the present invention.

FIG. 3 is a front view of the essential portions of the first embodiment of the temperature measuring device according to the present invention.

FIG. 4 is a comparison diagram of the amount of incident light in the conventional device and the device according to the present invention.

FIG. 5 is a front view of a second embodiment of the temperature measuring device according to the present invention.

FIG. 6 is a front view of a third embodiment of the temperature measuring device according to the present invention.

FIG. 7 is an external perspective view of a conventional temperature measuring device.

FIG. 8 is a conceptual diagram for explaining a measuring method using a conventional temperature measuring device.

FIG. 9 is a side sectional view of a main part of a conventional temperature measuring device.

FIG. 10 is a front view of a main part of a conventional temperature measuring device.

[Explanation of symbols]

 2 Optical fiber for emission 3 Optical fiber for incidence 4 Optical fiber for incidence 7 Thermosensitive element 8 Reflective film 9 Optical coupler 30 Optical fiber for incidence

Claims (1)

[Claims] 1. An outgoing optical fiber and an incoming optical fiber arranged in parallel, and a temperature sensitive element which is joined to the end faces of these fibers and whose transmitted light wavelength changes with temperature change.
A temperature measuring device, which is disposed on the back surface of the temperature-sensitive element and includes a reflecting member that introduces the light emitted from the emission optical fiber into the incident optical fiber as the incident light, and measures the temperature from the change in the output of the incident light. In the above, a plurality of incident optical fibers are arranged in the optical path region of the incident light, and a coupling means for optically coupling the plurality of incident lights guided to the plurality of incident optical fibers is provided. Temperature measuring device.