Patent ID: 6128945
Filing Date: 2000-10-10
Classification: G01N

Abstract:
A method of detecting a gas by subjecting a metal oxide semiconductor gas sensor to a temperature change pattern, a resistance of said gas sensor changing with the temperature, said method of detecting a gas comprising:(a) defining a phase space, first and second coordinates of said phase space respectively representing magnitudes of first and second gas sensor signals, said first and second gas sensor signals respectively being responsive to the resistance of said gas sensor at first and second times after a start of the temperature change pattern;(b) for each concentration of plural concentrations of the gas to be detected, measuring at least said first and second gas sensor signals to thereby determine a first data point in said phase space;(c) storing data representing a locus in said phase space as a function of each first data point determined in step (b);(d) measuring at least said first and second gas sensor signals for determining a measurement point in said phase space at a time of measurement; and(e) determining a gas concentration from one of a projection along an axis from said measurement point to said locus and a distance between said locus and said measurement point.