| 摘要 |
<p>A control circuit unit 31 for use connected to an NOx sensor 1 is disclosed. A first pump element control circuit 56 controls a voltage applied to a first pump element 3 so as to control the level of a partial pressure of oxygen contained in a first processing chamber 9 such that an output voltage of an oxygen concentration detection element becomes substantially constant. A first pump current is detected through use of a current detection resistor 101 and is then output via an A/D converter circuit 65. A second pump element control circuit 57 applies a constant voltage to a second pump element 5 in such a direction as to pump out oxygen from a second processing chamber 10. A second pump current is detected through use of a current detection resistor 107 and is then output via an A/D converter circuit 65. A detection signal indicative of the first pump current is used for determination of the oxygen concentration of a measurement gas. The detection signal indicative of the first pump current and a detection signal indicative of the second pump current are used for determination of the nitrogen oxides concentration of the measurement gas.</p> |
