Patent ID: 6623618
Filing Date: 2003-09-23
Classification: G01N

Abstract:
A gas sensor comprising:a main pumping means for pumping-processing oxygen contained in a measurement gas introduced from an external space, comprising a solid electrolyte contacting with said external space, and an inner pumping electrode and an outer pumping electrode formed on inner and outer surfaces of said solid electrolyte; and a measuring pumping means for decomposing a predetermined gas component contained in said measurement gas after being pumping-processed by said main pumping means by the aid of a catalytic action and/or electrolysis, and pumping-processing oxygen produced by said decomposition via said outer pumping electrode of said main pumping means, wherein: a concentration of oxygen is controlled and/or the predetermined gas component is measured by allowing a pulse-shaped current to flow through said measuring pumping means; the gas sensor further comprising: an electromotive force-measuring circuit for constantly measuring the electromotive force corresponding to a difference between an amount of oxygen produced by said decomposition of said predetermined gas component and an amount of oxygen contained in a reference gas; a duty ratio control means for controlling a duty ratio of said pulse-shaped current corresponding to a difference between an the electromotive force measured by said electromotive force-measuring circuit and a comparing voltage; and a measuring circuit for at least converting the duty ratio of the pulse-shaped current into a concentration of said predetermined gas component.