Patent ID: 8224198

Claim:
A humidity detecting device comprising: a humidity sensor that detects a humidity based on a change in an impedance, and that generates a humidity detection signal based on an applied alternating current (AC) voltage; an applying unit that applies the AC voltage to the humidity sensor; a detecting unit that detects a first impedance of the humidity sensor based on a first frequency of the AC voltage, and that detects a second impedance of the humidity sensor based on a second frequency of the AC voltage, wherein the first frequency and the second frequency are different; a switching unit that switches a frequency of the AC voltage to one of the first frequency and the second frequency; a temperature sensor that detects an ambient temperature of the humidity sensor; a processor; and memory operatively coupled to the processor and storing computer readable instructions that, when executed by the processor, cause the humidity detecting device to function as: a calculating unit that calculates one of a difference and a change rate between the detected first impedance and the detected second impedance; a discriminating unit that discriminates a kind of the humidity sensor based on the one of the difference and the change rate between the detected first impedance and the detected second impedance, wherein the humidity sensor corresponds to one of a plurality of kinds of humidity sensors; and a control unit that performs processing corresponding to the discriminated kind of the humidity sensor when the humidity detecting device detects the humidity.