HUMIDITY MEASURING INSTRUMENT

摘要

PURPOSE:To increase a detection signal even at low humidity and to easily measure the low humidity by applying a 1st voltage which causes the electrolysis of water and a 2nd voltage which does not cause the electrolysis of water alternately between electrodes. CONSTITUTION:An oxygen sensor 8 has the electrodes 3 and 4 arranged opposite each other across a solid-state electrolyte layer 1 having oxygen ion conductivity and a voltage application part 16 applies the 1st voltage 10 which causes the electrolysis of water and the 2nd voltage 11 which does not cause the electrolysis of water alternately between the electrodes 3 and 4. An amplifier 14 amplifies a signal current outputted by the sensor 8 and outputs a detection signal. Then an arithmetic part 18 outputs a 1st signal 19a which is the result of arithmetic based upon the 1st voltage 10 and 2nd voltage 11 as a measurement signal when the absolute humidity is low and outputs a 2nd signal 20a which is the result of arithmetic corresponding to the 2nd voltage 11 when the absolute humidity is high.