JPS5848841A - Temperature compensating circuit of ceramic moisture sensing element - Google Patents

Abstract

PURPOSE:To take out the output of a moisture sensing element without reference to temp., by using a product obtained by heating a sintered material consisting of the same or the nearly same composition as a moisture sensing element for removing moisture and sealing it under vacuum, as a temp. compensating element. CONSTITUTION:A moisture sensing element and a temp. element are composed of 80-99.5mol% ZnO and 0.5-20mol% LiZnVO4 or 80-99.5mol% MgCr2O4 and 0.5-20mol% SnO2. These are sintered at 1,300 deg.C and fitted to an electrode to obtain the moisture sensing element and at the same time the temp. compensating element is housed in a metallic case which is possible to be soldered and is heated at 200 deg.C in 1Torr vacuum for removing moisture in the element and is sealed by winding solder between the case and a cap. Output voltage obtained from the moisture detecting circuit in which the moisture sensing element 2 and the moisture compensating element 3 constituted in such a way are connected in series, has no relation with temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a ceramic humidity sensing element and performs temperature compensation in order to detect humidity with high precision, so that the humidity sensing element outputs a nearly constant output for each relative humidity regardless of the temperature. That's what you're trying to get.

But in any case? There was a problem that it had M skin characteristics and could not be used for high-precision humidity detection. In order to reduce the variation in output due to temperature, attempts have been made to connect a thermistor in series with the sensor to correct the output of moisture-sensitive confectionery and reduce the variation due to temperature, but it has not been possible to make sufficient compensation. There were drawbacks.

The present invention has been made in view of the above points, and is designed to make the output of the Kansei Kaoruko a constant value regardless of the temperature! The aim is to provide a circuit that performs compensation.

Example 1 will be explained below.

Example 1 The composition of a ceramic moisture-sensitive element was 80 to 99.5 mol% of Zn0 and 5 to 20 mol% of LiZnVO40. This was molded and then sintered at 1300' (l) to a thickness of 8.5 u x 0.25 mm. Make a coin-shaped body of M. Au
Apply an electrode material such as paste or Run2 to both sides of the self-assembly and dry to form an electrode with a diameter of 7 mm;
Connect the lead wire to the 11L pole and create a moisture sensitive female Lfco
*7i Also, make the same or the same thing as the moisture-sensitive girl described in 1jlJ and use it as a sensual temple and store it in a button 11-s that can be soldered with 1 torr. To seal the case, wrap solder between the metal case and the metal case.
This is done by removing the moisture in the solder and then melting the solder by heating. The feeling created in this way 7IIl! The element and the temperature compensation element are connected in series as shown in FIG. That is, AC ゛tun source (1), feeling IM
Omoteko (2), Chidochi Ikeko (3).

The terminal (5) is being pulled out. The curve η) in FIG. 2 shows the output voltage at each temperature when the relative humidity is 60% using this humidity detection circuit. As is clear from the figure, the output voltage remains at a nearly constant value regardless of the temperature. Conventionally, a thermistor was used in place of the temperature compensator (3) in the circuit shown in Figure 1. I was doing it, but
The output voltage of this conventional example is as shown in the J curve in Figure 2, and is clearly different from the present invention. The characteristics (temperature and resistance value of the sensitizer) are as shown in the curve shown in FIG.

Example 2 The composition of the humidity sensitive element and temperature compensation element was MgCr5048.
0 to 99.5 mol%, 5n820.5 to 20 mol%, and the other characteristics were the same as in Example 1 described in IIU. As shown in curve (8), although the levels are higher than those of each curve (1) of Example 1, it is clear that excellent temperature compensation is achieved.

The table below shows the results of measuring the temperature characteristics of the temperature compensation element itself used in Example 1 and Example 2 written by TJll.

In addition, in FIG. 3, the thermistor indicated by 4* (C) and the inert gas sealed in Invention 1 are also shown as 18 examples.

Non-invention l According to the present invention, a person who is the same as a moisture-sensitive girl or who is bald according to the present invention By using a temperature compensating element made of the same composition, heated to remove moisture, and sealed in vacuum, the output of the humidity sensor can be taken out at a constant value regardless of the temperature. This is because the temperature gauge is vacuum-sealed, so in a circuit like the one shown in Figure 1, only the change in resistance due to temperature is compensated for.For example, when using a thermistor, select the optimal type of thermistor. Even so, since the temperature characteristic of the humidity sensing element, that is, the resistance value is considerably different from the resistance value at each temperature, the temperature-output voltage characteristic curve wt:
The inclination will be served. In this respect, if a vacuum-sealed device with the same or the same composition as the IeA wet bulking element is used as a temperature compensation element, the output voltage can be kept constant for each relative IM and u. This provides an effect that can be extracted as an output voltage.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of the humidity detection circuit; Fig. 2 is a curve diagram showing the relationship between temperature and output voltage of the non-inventive and conventional examples;
FIG. 3 shows 1! of the temperature compensation element according to the present invention. FIG. 3 is a curve diagram showing the relationship between resistance and resistance value. (1)------One current source (2),---One sense humidity Sumireko (3)---One temperature element (4)---One one resistance (5) -------One Output Terminal Patent Applicant Marukon Electronics Co., Ltd.

Claims (2)

[Claims] (1) A temperature compensation circuit having the same composition as that of the ceramic humidity-sensing element or having the desired composition and sealed by heating in a vacuum is connected in series to the ceramic humidity-sensing element. Temperature compensation circuit for ceramic humidity sensing element. (2) The composition of the ceramic moisture sensitive element is Zn080-99.
5 mol% and LiZnVo, 0.5-20 mol% or M
gcr2ot 80-99.5 mol% Hi5no20.
The temperature compensation circuit for a ceramic humidity sensing element according to claim (1), wherein the content is 5 to 20 mol%. Claim (1) characterized in that the soldering process uses a temperature compensating element vacuum-sealed in a flat metal case.
(1) The temperature compensation circuit for the ceramic moisture-sensitive element according to (1) above.