Patent ID: 6055849
Filing Date: 2000-05-02
Classification: G01N

Abstract:
A gas detector detecting a gas by subjecting a metal oxide semiconductor gas sensor to a temperature change, a resistance of said gas sensor changing with the gas, said gas detector comprising:a non-volatile memory means for storing a standard signal being linear to logarithms of resistance values of said metal oxide semiconductor in combination with plural points on a waveform of the resistance of the gas sensor according to the temperature change;a ladder resistance being connected as a load resistance in series with said gas sensor, a ratio of its resistance to that of the metal oxide semiconductor being arranged to be within a specified range at said plural points;a power source for applying a detecting voltage to said ladder resistance and said metal oxide semiconductor;a sampling means for sampling measurement data being linear to the logarithm of the resistance value of said metal oxide semiconductor by sampling an output linear to an output voltage to said ladder resistance at each of said plural points; anda gas detecting means for detecting the gas by comparing combinations of measurement data at said plural points with said standard signal.