| 摘要 |
PROBLEM TO BE SOLVED: To substantially eliminate periodical calibration operation by outputting a electromotive force generated by an oxygen concentration cell system based on the oxygen partial pressure difference between a gas to be measured and a reference gas in the state of constantly being calibrated. SOLUTION: While a first electromotive force V1 by an oxygen concentration cell between a first reference gas and a gas to be measured with a certain oxygen partial pressure P1 which exists in a first reference room 4 being provided in a sensor element 2, a second electromotive force V2 due to the oxygen concentration cell between a second reference gas and the gas to be measured of a certain oxygen partial pressure P2 which is different from the first reference gas being present in a second reference room 6 which is provided in the sensor element 2 separately from the first reference room 4 is measured. Further, a third electromotive force V3 due to the oxygen concentration cell between the first reference gas and the second reference gas is measured and a first or a second electromotive force is calibrated based on those obtained three electromotive force values (V1 , V2 , and V3 ), thus obtaining the oxygen partial pressure within the gas to be measured from the calibrated electromotive force value. |
