JPS5839371B2 - Temperature/humidity detection device - Google Patents

Description

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

Conventionally, F has been used as a sensor for humidity measuring devices and humidity adjusting devices.
Moisture-sensitive resistors, such as E203tA1203, which are mainly composed of metal oxides with excellent water absorption properties and whose resistance value changes in response to humidity, and are used to detect humidity, have generally been used.

However, in general, it is better 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, it is often necessary to make the humidity detection circuit and temperature detection circuit independent, for example by separately using the humidity-sensitive resistor for detecting humidity and using a sensor for detecting temperature. However, this method has the drawback that it requires a two-system circuit configuration, which complicates the circuit configuration and increases the manufacturing cost of the device.

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.

1. As a starting material, LiC03y 'l'a2 o5
are wet mixed and then dried to form a dry powder.

Next, this powder raw material is molded into 4 x 4 x 0.25 mm (
Molding pressure: 750 kq/crtt) L, oxide porcelain of LiTaO3 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 constitute a temperature/humidity sensing element.

As the electrode material, in addition to RLI02 type, Ag tN
i, Zn, Cr, Pd yAu, pt, S
n, Cu.

Similar effects can be obtained by applying Al t In by an electrode paste baking method, thermal spraying method, vapor deposition method, or the like.

Electrodes made of metal oxides, semiconductors, etc. whose main components are nickel oxide, zinc oxide, and indium oxide can also be formed by this 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 Figure 2 shows that both electrodes 2,
When a 10Hz-IV low frequency power source is applied between the two,
This figure shows the change in electrical impedance of the temperature/humidity sensing element as the relative humidity changes, and it can be seen that the electrical impedance decreases as the humidity increases.

In addition, in an experiment on the above-mentioned 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 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 1000 KHz-IVO high frequency power source is applied between both electrodes 2 and 2. You can see that things are changing.

The relative humidity was increased by 10% under the same applied power condition.
It was found that even when the ratio was set to 99%, there was almost no change in the above characteristics.

The graph shown in FIG. 4 is a frequency-electrical impedance characteristic at a temperature of 20° C. when humidity is used as a parameter, where A is a humidity of 20 da RH and B is a humidity of 40 phi 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 the high frequency is not affected by humidity changes to a large extent.

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 LiTaO3 component, but also includes BaTiO3.
*5rTi03, PbTiO3, CaTiO3Pb
ZrO3, KNbO3, NaNbO3tLiNb03
.

Even if one or more compounds such as Pb (Mg1/s Nb 2 /s) Os button and other peropskite types, tungsten bronze types, pyrochlore types, spinel types, and metal oxides are added,
It is possible to obtain an element with fast response, high sensitivity with extremely low characteristic deterioration, 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.

In addition, this temperature/humidity sensing element also has excellent heat resistance, so even if this element becomes contaminated with airborne substances, it can be returned to its original state by heating and cleaning. You can also do it.

Regarding the dimensions, shape, and structure of this element,
It is not limited to the above example, and various sizes 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-1V oscillator osc-i and a 500KH2-1v oscillator 08C are used.
-2 in parallel, and the temperature/humidity sensing element S and the resistor (10Ω) are connected to the power supply, which can be connected to each of the oscillators 08C-1, 08C-2 by using a changeover switch SW. Consists of horses connected 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 to the resistor salt, and when the changeover switch SW is turned to the b side. When you turn it down, oscillator 08C
-2, and an output signal corresponding to temperature change is obtained to the resistor.

Among them, when using the configuration of this embodiment, the temperature is 0°C to 30°C.
Detection is possible at 0°C and humidity ranging from 10 to 100 RH.

As described above, this temperature/humidity detection device can detect temperature and humidity with a single circuit configuration, and is useful for temperature/humidity detection in fields such as air conditioning management, meteorology, food industry, and medical and chemical fields. The configuration of the device for humidity control 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 two embodiments 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... Changeover switch, S... Temperature/humidity detection element, R9... Resistor.

Claims (1)

[Claims] A temperature/humidity detection device characterized by connecting a temperature/humidity detection element having an electrode surface on oxide porcelain whose main component is ILiTaO3 and a power supply circuit whose frequency can be selectively changed.