초록 ▼

A humidity sensor of a heat conduction type which enables a humidity measurement to be produced by a single temperature sensing resistor so as to reduce a change in characteristic depending on a temperature change of the measurement atmosphere and to reduce the cost, comprises a temperature sensing

A humidity sensor of a heat conduction type which enables a humidity measurement to be produced by a single temperature sensing resistor so as to reduce a change in characteristic depending on a temperature change of the measurement atmosphere and to reduce the cost, comprises a temperature sensing resistor 1 and three fixed resistors R.sub.1, R.sub.2 and R.sub.3 which form a Wheatstone bridge circuit. The humidity is measured by utilizing the fact that the heat dissipation 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 be at a constant temperature of 150.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.

대표청구항 ▼

[ We claim:] [1.] A humidity sensor for measuring humidity by utilizing the fact that the heat dissipation of a temperature sensing resistor changes depending on the humidity, said humidity sensor comprising:a heating control unit which includes a heat generator for self-radiation of Joule heat and

[ We claim:] [1.] A humidity sensor for measuring humidity by utilizing the fact that the heat dissipation of a temperature sensing resistor changes depending on the humidity, said humidity sensor comprising:a heating control unit which includes a heat generator for self-radiation of Joule heat and being arranged to heat said temperature sensing resistor, said heat generator being controlled by said heating control unit to heat said temperature sensing resistor to control the temperature of said temperature sensing resistor to be at a constant temperature as a constant first temperature, wherein said constant first temperature is more than 150.degree. C.;an electrical circuit for producing an output voltage relating to voltage drop across said temperature sensing resistor at said first temperature; andcorrecting means for correcting the output voltage value of the output voltage of said electrical circuit with reference to a variation in output voltage value of the output of said electrical circuit depending on the ambient temperature of said temperature sensing resistor.