JPS5839366B2 - 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 detection devices and humidity adjustment devices.
Moisture-sensitive resistors, which are mainly composed of metal oxides with excellent water absorption properties such as e 203 and A 12 o3, 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 a starting material, KOO; 3 y Nb2o is wet mixed and then dried to form a dry powder.

Next, this powder raw material is molded into a size of 4 x 4 x 0.25 mm (
Molding pressure 750 ky/cd! ) 'L,, KNbO3 oxide porcelain is produced as the sintered body 1.

Further, a RuO2-based electrode paste is applied to the sintered body 1 and baked at 800°C to form an electrode 2 to form a temperature/humidity sensing element.

The electrode material may be Ag in addition to RuO□.

Ni Zn Cr Pd Au Pt Sn
A similar effect can be obtained by applying CuAlIn by electrode paste baking, irradiation, vapor deposition, 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
When a low frequency power supply of 1 OHZ-IV is applied between 2,
This figure shows the change in electrical impedance of the humidity sensing element as the relative humidity changes, and it can be seen that the electrical impedance decreases as the humidity increases.

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 is based on humidity 50% R, H (1-95℃
) shows the change in electrical impedance of the temperature/humidity sensing element due to temperature change when a high frequency electrode of 1000 KHzlv is applied between both electrodes 2 and 2. The electrical impedance changes in response to temperature change. 6 It was also found that there was almost no change in the above characteristics even when the relative humidity was set to 10% and 99% under the same applied power supply conditions.

The graph shown in Fig. 4 shows the frequency-electrical impedance characteristics at a temperature of 20°C when humidity is used as a parameter. %RH, it can be seen that high frequencies are not affected by temperature 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 configuration of this temperature/humidity sensing element is not limited to that of KNbO3, but also BaTiO3,
5rTi03, PbTiO3, 0aTi03.

PbZrO3, NaNb0a, LiNbO3, LiT
Even when one or more compounds such as aO3゜Pb(Mg, /3Nb2i)03 and other peropskite types, tungsten bronze types, pyrochlore types, spinel types, and metal oxides are added, the response is fast. It is possible to obtain a highly sensitive element with extremely low characteristic deterioration and excellent separation of humidity and temperature and humidity during humidity detection.

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 humidity/humidity detection device using the temperature/humidity detection element, in which a 60Hz IV oscillator OS O-1 and a 500 KHz-IV oscillator 080 are used.
-2 in parallel and connected to each of the oscillators 080-1. 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 osc-i, 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
0-2, and an output signal corresponding to temperature change is obtained from the resistor R8.

In addition, when using the configuration of this embodiment, the temperature is 0°C to 15°C.
Detection is possible over the range of 0° C. and humidity of 10% RH to 100% RH.

As described above, according to this temperature and humidity detection device, temperature and humidity detection can be performed with one circuit configuration, and temperature and humidity control in fields such as air conditioning management, meteorology, food industry, medical and chemical related fields can be performed. 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 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
I, 08C-2... Oscillator, SW... Changeover 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 KNbO3 and a power supply circuit capable of selectively converting the frequency.