| 摘要 |
<p>An output of a direct current power supply is divided with a pair of resistors, and applied to any of electrodes of an electrochemical gas sensor provided with a detection electrode, a counter electrode and a solid electrolyte membrane through a buffer amplifier. Impedance of the gas sensor is measured by switching with a switch the connection destination of one electrode of the electrochemical gas sensor between a current amplification circuit and an impedance measurement circuit. The impedance measurement circuit is formed of an alternating current power supply that switches a potential of a resistor on a side of one end connected to the switch and a potential on a side of the other end of the resistor, between the output potential and the ground potential of the direct current power supply. Gas concentration is determined by storing humidity dependency and temperature dependency of the electrochemical gas sensor, and correcting the output of the current amplification circuit based on measured impedance and ambient temperature.</p> |
