| 摘要 |
In order to provide a humidity sensor of a heat conduction type which enables the humidity measurement by a single temperature sensing resistor so as to reduce the change in characteristic depending on the temperature change of the measurement atmosphere and to reduce the cost, a temperature sensing resistor 1 and three fixed resistors R1, R2, and R3 form a Wheatstone bridge circuit. The humidity is measured by utilizing the fact that the heat radiation of the temperature sensing resistor 1 changes depending on the humidity. The temperature sensing resistor 1 is heated by a heat generator 2 for self-radiation of Joule heat so that the temperature of the temperature sensing resistor 1 is controlled to a constant temperature of 300.degree.C or more. The output voltage value of the Wheatstone bridge circuit is corrected with reference to the variation of the output voltage value depending on the ambient temperature of the temperature sensing resistor 1.
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