JPS5839365B2 - Temperature/humidity detection device - Google Patents

Description

[Detailed description of the invention] This invention relates to a temperature/humidity sensing device.

6 Conventionally, as a sensor for humidity measuring devices and humidity regulating devices,
Moisture-sensitive resistors, which are mainly composed of metal oxides with excellent water absorption properties such as Fe2O3 and Al2O, and whose resistance value changes in response to humidity to detect humidity have been commonly used.

However, in general, there are more cases in which it is required to detect humidity and temperature together than to detect humidity alone, for example in air conditioning systems where temperature control is performed at the same time as humidity control. In order to meet this demand, for example, the humidity sensing resistor is used separately for detecting humidity, and the thermistor is used for temperature sensing. I had to take it.

This has resulted in a disadvantage that the circuit configuration becomes complicated and the manufacturing cost of the device also increases.

Therefore, an object of the present invention is to provide a temperature/humidity detection device that can detect both temperature and humidity with a simple and inexpensive circuit configuration.

Embodiments of the present invention will be described below based on the drawings.

First, an example of a temperature/humidity sensing element used in this temperature/humidity sensing device will be explained in detail with reference to FIG. 1.

First, as starting materials, Cab and TiO2 are wet mixed and then dried to form a dry powder.

Next, this powder raw material is molded into a size of 4×4×0.25 mat (molding pressure: 750 Ky/crit) to produce CaTiO3 oxide porcelain as a sintered body 1.

Further, a Ru 02-based electrode paste is applied to the sintered body 1 and baked at 800° C. to form an electrode 2 to constitute a temperature/humidity sensing element.

As the electrode material, Ag is used in addition to Ru02 type.

Ni, Zn, Cr*Pd5AunPt*5ntCus
Similar effects can be obtained by applying A l p I n by an electrode paste baking method, thermal spraying method, vapor deposition method, or the like.

Electrodes made of metal oxides and semiconductors whose main components are nickel oxide, zinc oxide, and indium oxide can also be formed by such a method.

Regarding the characteristics of the temperature/humidity sensing element having the above configuration,
This will be explained below based on the experimental results.

The graph shown in FIG. 2 shows that both electrodes 2 and 2 at a temperature of 20°C
This shows the change in electrical impedance of the temperature/humidity sensing element as the relative humidity changes when a 10 Hz-IV low frequency power source is applied between the two, and as the humidity increases, the electrical impedance decreases. I know what you're doing.

Furthermore, in an experiment on the above characteristics conducted at a temperature of 80°C under the same applied power supply conditions, it was found that there was almost no effect due to temperature differences;
It was found that the change in electrical impedance of the humidity sensing element depends only on humidity under conditions where a low frequency power source is applied.

The graph shown in Figure 3 shows the humidity of 50φRH (1 to 95℃)
This shows the change in electrical impedance of the temperature/humidity sensing element due to temperature change when a 1000 KHz-IV high frequency power source is applied between both electrodes 2 and 2. It can be seen that the is changing.

In addition, under the same applied power condition, the relative humidity can be increased by 10,
It was found that there was almost no change in the above characteristics even when the temperature was 99.

The graph shown in FIG. 4 shows frequency-electrical impedance characteristics at a temperature of 20° C. when humidity is used as a parameter, where A is a humidity of 20% RH and B is a humidity of 40% RH.

C is the characteristic when the humidity is 60% RH, and D is the characteristic when the humidity is 80% RH, but it can be seen that high frequencies are not affected by humidity changes at all.

From the above experimental results, it is clear that the change in electrical impedance of this temperature/humidity sensing element depends on humidity under low frequency power supply conditions, and that the change in electrical impedance depends on temperature under high frequency power supply conditions. It can be seen that it has dependent properties.

The structure of this temperature/humidity sensing element is not limited to the above-mentioned CaTiO3 component;
3p S rT t 03 s PbT 103Pb
ZrO, KNbO3, NaNbO3 L i Nb 03 s L I T R03* P
b Even if one or more compounds such as (Mgx/5Nb2/5)Os and other perovskite types, tungsten bronze types, pyrochlore types, spinel types, and even metal oxides are added, the response is fast and there is no characteristic deterioration. It is possible to obtain an element with extremely low sensitivity and excellent separation of temperature and humidity when detecting temperature and humidity.

Further, by adding other additives, the characteristics can be controlled to achieve high sensitivity within a certain limited humidity or temperature detection range.

This temperature/humidity sensing element also has excellent heat resistance, so even if the element becomes contaminated with airborne particles, it can be returned to its original state by heating and cleaning. .

Note that the dimensions, shape, and structure of this element are not limited to those in the example above, and may be of various dimensions, shapes, and structures.
Any shape is possible.

FIG. 5 shows an embodiment of a temperature/humidity detection device using the temperature/humidity detection element, in which a 60Hz-1V oscillator 08C-1 and a 500 KHz-IV oscillator 08 are used.
The temperature/humidity sensing element S and the resistor (IOKΩ) R8 are connected to a power supply which is configured with C-2 in parallel and can be switched and connected to each of the oscillators 0sC-1 and 08C-2 using a changeover switch SW. Configure by connecting in series.

With this configuration, for example, when the changeover switch SW is turned to the a side, it is connected to the oscillator 08C-1, and an output signal corresponding to the humidity change is obtained at the resistor R8.
Also, when the changeover switch SW is turned to the b side, the oscillator 08
C-2, and an output signal corresponding to temperature change is obtained from resistor R8.

In addition, when using the configuration of this embodiment, the temperature is 1°C to 25°C.
Detection is possible over the range of 0° C. and humidity of 10% RH to 100% RH.

As described above, this temperature/humidity detection device can detect temperature and humidity with a single circuit configuration, and can be used for temperature/humidity control in fields such as air conditioning management, meteorology, food industry, medical chemistry, etc. The configuration of the device for this purpose can be simplified, and the cost of the device can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of a temperature/humidity sensing element used in an embodiment of the present invention, Fig. 2 is a diagram showing humidity versus impedance characteristics of the temperature/humidity sensing element, and Fig. 3 is a diagram showing temperature/humidity sensing elements. A diagram showing the temperature vs. impedance characteristics of the sensing element,
FIG. 4 is a diagram showing the frequency versus impedance characteristics of the temperature/humidity sensing element, and FIG. 5 is a circuit diagram showing one embodiment of the temperature/humidity sensing device. 1... Sintered body (oxide porcelain), 2... Electrode, 08C
-1,08C-2...Oscillator, SW...Changing switch, S...Temperature/humidity detection element, R8...Resistor.

Claims (1)

[Claims] 1. A temperature/humidity detection device characterized by connecting a temperature/humidity detection element having an electrode surface on oxide porcelain whose main component is CaTt03 and a power supply circuit whose frequency can be selectively changed.