JPH0194256A - Humidity sensor - Google Patents

Abstract

PURPOSE:To measure humidity with high accuracy, by connecting a humidity- sensitive element and a temp. correcting element in series and correcting the temp. error of the humidity-sensitive element caused by the change in the circumferential temp. by the temp. correction element. CONSTITUTION:A humidity-sensitive element 1 and a temp. correcting element 2, which is composed of a resistor formed from the same material quality as the humidity-sensitive element 1 sealed in a humidity resistant sealing member 3 such as glass and made equal to the humidity-sensitive element 1 in heat capacity, are connected in series and constant voltage is applied to both elements 1, 2 from a power supply. Then, by connecting both terminals of the temp. correcting element 2 to a voltmeter, humidity can be detected as a change in voltage. Since the temp. correcting element 2 is blocked from the outside by a means such as glass sealing and receives no effect of steam in the atmosphere at all, there is no sensitivity to humidity. By this method, humidity can be measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a humidity sensor used in humidity detection systems and the like in various types of equipment.

<Prior Art> Various humidity sensors using ceramic semiconductors are known.

Since this known humidity sensor uses an i-humidity probe whose resistance value changes with changes in humidity, humidity can be determined by a circuit that measures changes in resistance value.

<Problems to be Solved by the Invention> Since the humidity sensing element used in the conventional humidity sensor described above detects temperature and is also sensitive to temperature, it may be affected by temperature in an environment where temperature changes with humidity. There was a problem in that accurate humidity detection was not possible due to the high humidity.

In order to solve such problems, temperature correction is necessary, and an element with the same temperature coefficient as the humidity element and not affected by humidity is needed, but it is necessary to find such an element. This is not easy, and even if an excellent moisture-sensitive element was found, it was difficult to put it into practical use.

<Means for Solving the Problems> The present invention was made to solve the above-mentioned problems, and includes a moisture-sensitive element and a resistor made of the same material as the moisture-sensitive element, sealed in a moisture-resistant material such as glass. A temperature correction element is encapsulated with a material and has the same heat capacity as the active element, and the humidity sensing element and the temperature correction element are connected in series to correct humidity errors in the humidity sensing element due to changes in ambient temperature. is corrected by the temperature correction element.

<Embodiment> An embodiment of the present invention will be described based on FIGS. 1 to 3 of the accompanying drawings.

In FIG. 1, 1 is a humidity sensing element, and 2 is a temperature correction element made of the same material as the humidity sensing element, both of which are resistors. For example, (Ba Ce ) o, y
f'Jdo, +03 is used.

Such an element is made into a molded body using a normal ceramic method and fired at 1450°C for 2 hours to form a 10mm x 10mt
A fired body of n x 1 rRtn is made, and after applying I○t paste as an electrode forming material to this fired body and baking it at 850°C, it is cut.

The dimensions of the moisture sensitive element 1 in the example are 1.411+1
1X 1.41 rRy+X 1 ram.

Further, the same material is sliced to a thickness of 0.125 mm to form the temperature correction element 2. Its dimensions are 0.5rtrtn
It is in the form of a chip of 0.5mtnx 0.125111#I.

The temperature correction element 2 includes a glass tube 3 as shown in FIG.
Lead electrodes 4.5 inserted from both ends of the tube 3 are electrically connected to electrodes at both ends of the temperature correction element 2.

Then, both ends of the glass tube 3 are sealed by means such as heating and melting.

However, it may be sealed with a material other than glass, such as synthetic resin. A lead electrode 6 connected to one electrode of the humidity sensing element 1 is connected to the lead electrode 5.

7 is a lead electrode connected to the other electrode of the humidity sensing element 1.

In the circuit diagram of FIG. 3, the humidity sensing element 1 and the temperature correction element 2 are connected in series, and a constant voltage is applied from a power source 8 to this pixel element 1.2. By connecting both ends of the temperature correction element 2 to a voltmeter 9, humidity is detected as a change in voltage.

<Effects> As described above, the present invention includes a humidity sensing element and a resistor made of the same material as the humidity sensing element sealed in glass, and which has the same heat capacity as the humidity sensing element as a temperature correction element. , the humidity sensing element and the temperature correction element are connected in series so that the humidity error of the humidity sensing element due to changes in ambient temperature is compensated for by the temperature correction element. Since the correction element uses a resistor made of the same material, the 8 constants are obviously equal. Moreover, since the temperature correction element is sealed from the outside by means such as glass encapsulation so as to be completely unaffected by water vapor in the atmosphere, it is not sensitive to humidity.

Therefore, the temperature compensation element completely eliminates the influence of temperature on the humidity sensing element, making it possible to measure humidity with extremely high accuracy without being affected by changes in ambient temperature. There is no need for assembly, and there are advantages such as humidity detection being possible with a simple series circuit as shown in the embodiment.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the main parts showing one embodiment of the present invention;
The figure is an enlarged longitudinal cross-sectional side view of the temperature correction element used in the above, and the third figure is
The figure is a circuit diagram showing an example of the circuit. 1...Moisture sensing element 2...Temperature correction element 3.
・Encapsulating material

Claims (1)

[Claims] A humidity sensing element and a resistor made of the same material as the humidity sensing element are encapsulated in a moisture resistant enclosing member such as glass, and the temperature correction element is made to have the same heat capacity as the humidity sensing element, and the humidity sensing element and A humidity sensor characterized in that the temperature correction element is connected in series so that the temperature error of the humidity sensing element due to a change in ambient temperature is corrected by the temperature correction element.