Abstract: A sensor control device for controlling a current application state of a gas sensor element when measuring a specific gas component concentration in a gas to be measured using the gas sensor element, which sensor control device includes: at least one cell having a solid electrolyte body and a pair of electrodes; a sensor heating unit as defined herein; an oxygen reference pole generating unit as defined herein; a damage avoidance time elapse determining unit as defined herein; and a reference generation current application permitting unit as defined herein.

Abstract: Using a gas detection voltage Vs output from a terminal CU, a determination is made at to whether, after startup of an air-fuel ratio detection apparatus (1), a full-range air-fuel ratio sensor (10) has reached a semi-activated state in which a determination can be made as to whether the air-fuel ratio is on the rich or lean side based on a change in a gas detection signal Vic. After determining that the sensor has reached the semi-activated state, the signal Vic is compared with a threshold to determine whether the air-fuel ratio is on the rich or lean side. In the apparatus (1), the potential difference between an outer pump electrode of a pump cell (14) and a reference electrode of an oxygen concentration measurement cell (24) is obtained via a first differential amplification circuit (53) as the gas detection signal Vic, the signal Vic being highly responsive to a change in air-fuel ratio of exhaust gas.

Abstract: A sensor control device for controlling a current application state of a gas sensor element when measuring a specific gas component concentration in a gas to be measured using the gas sensor element, which sensor control device includes: at least one cell having a solid electrolyte body and a pair of electrodes; a sensor heating unit as defined herein; an oxygen reference pole generating unit as defined herein; a damage avoidance time elapse determining unit as defined herein; and a reference generation current application permitting unit as defined herein.

Abstract: Using a gas detection voltage Vs output from a terminal CU, a determination is made at to whether, after startup of an air-fuel ratio detection apparatus (1), a full-range air-fuel ratio sensor (10) has reached a semi-activated state in which a determination can be made as to whether the air-fuel ratio is on the rich or lean side based on a change in a gas detection signal Vic. After determining that the sensor has reached the semi-activated state, the signal Vic is compared with a threshold to determine whether the air-fuel ratio is on the rich or lean side. In the apparatus (1), the potential difference between an outer pump electrode of a pump cell (14) and a reference electrode of an oxygen concentration measurement cell (24) is obtained via a first differential amplification circuit (53) as the gas detection signal Vic, the signal Vic being highly responsive to a change in air-fuel ratio of exhaust gas.