| 摘要 |
Present invention provides a method and device for measuring an oxygen and a nitrogen oxide concentration comprising the steps of causing a small current to flow across an oxygen concentration measuring cell, and a first current to flow in a first oxygen pumping cell so that an output voltage of said oxygen concentration measuring cell will be of a pre-set value; and applying a constant voltage across a second oxygen pumping cell, thereby decomposing nitrogen oxide contained in said second measurement chamber, wherein said nitrogen oxide concentration is measured based on a value of a second current flowing in said second oxygen pumping cell, and said oxygen concentration is measured based on a value of said first current, wherein said temperature detection means is adapted to periodically interrupt said connection between said pump current control means and said oxygen concentration measuring cell and to cause, during such interruption, an amount of current to flow in a direction opposite to a direction of said small current for detecting an internal resistance of said oxygen concentration measuring cell from a voltage generated during said interruption between said electrodes of said oxygen concentration measuring cell. <IMAGE> |
