JPS5839368B2 - Temperature/humidity detection device - Google Patents

Description

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

Conventionally, F has been used as a sensor for humidity measuring devices and humidity regulating devices.
Humidity-sensitive resistors, which are mainly composed of metal oxides with excellent water absorption properties such as e2O3 and Al2O3, and whose resistance value changes in response to humidity to detect humidity have been generally 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 a temperature button 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, PbO and Ta205 are wet mixed and then dried to form a dry powder.

Next, this powder raw material is molded into 4X4X0.25mm (
The molding pressure was 750 kg/ff1), and PbT was used as the sintered body 1.
Produces A206 oxide porcelain.

Furthermore, 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.

The electrode material may include Ag in addition to RuO2.

Ni, Zn, CrtPdtAu, Pt, Sn, CutA
Similar effects can be obtained by applying I and In 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 low frequency power source of 10 Hz -IV is applied between the two.As the humidity increases, the electrical impedance decreases. I know that there is.

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;
The humidity sensing element, under the condition of applying low frequency power,
It was found that the change in electrical impedance depends only on humidity.

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

Also, under the same applied power supply conditions, the relative humidity was 10%,
It was found that there was almost no change in the above characteristics even when the number of particles was increased to 99.

The graph shown in Figure 4 shows the frequency-electrical impedance characteristics at a temperature of 20°C when humidity is used as a parameter, where A is humidity 20%RH, B is humidity 40φRH, C is humidity 60%RH, and D is humidity 80%RH. It can be seen that high frequencies are not affected by humidity changes at all, which is a characteristic of a multi-plate case.

From the above experimental results, it is clear that the change in electrical impedance of this humidity/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 PbTa206 component, but also BaTt03. 5rTt03-PbTtO3Ca
TiO3・PbZrO3・KNbO3・NaNbO3・
LiNLiNb03-LiTa03-Pb(/lNb2
/) 03 and other perovskite types, tungsten bronze types, pyrochlore types, spinel types, and even when one or more compounds such as metal oxides are added, the response is quick and the characteristics are highly sensitive with very little deterioration. An element with excellent separation of temperature and humidity when detecting temperature and humidity can be obtained.

Furthermore, by adding more additives, the characteristics can be controlled to achieve high sensitivity within a limited humidity or temperature sensing 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 described above, and various dimensions and shapes are possible.

FIG. 5 shows an embodiment of a temperature/humidity detection device using the temperature/humidity detection element, in which a 60Hz-1 oscillator 08C-1 and a 500KHz-IV oscillator 08C are used.
-2 in parallel and can be connected to each of the oscillators O8C-1 and 08C-2 using a changeover switch SW. are configured by connecting them 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 to the resistor, and the changeover switch SW is turned to the b side. When defeated, oscillator 08C
-2, and an output signal corresponding to the temperature change is obtained from the resistor island.

Note that when using the configuration of this embodiment, the temperature is 0°C to 25°C.
Detection is possible over a range of 0°C and humidity of 10φRH.

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 drawings]

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 humidity 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 sensing element, Bird...Resistor.

Claims (1)

[Claims] 1. A temperature/humidity sensing device characterized in that a temperature/humidity sensing element having an electrode surface provided on oxide porcelain whose main component is PbTa20a is connected to a power supply circuit whose frequency can be selectively changed.