| 摘要 |
PURPOSE:To enable the measurement of concn. with high accuracy, by varying the monitor voltage of a limit current type oxygen sensor corresponding to the concn. of oxygen. CONSTITUTION:The internal resistor Rs of a limit current type oxygen sensor S is substantially the resistor of an oxygen ion conductive plate and variable by the concn. of oxygen to be measured and voltage to be applied. A resistor R7 converts a limit current to a voltage value to allow said voltage value to be fed back to an initial stage OP amplifier 10 through an OP amplifier 11. Further, reference voltage is determined by a variable voltage source 5 and a constant voltage diode D. When the concn. of oxgen is high, the output of the amplifier 10 becomes large and high monitor voltage is set. Contrarily, when the concn. of oxygen is low, low monitor voltage is set. Therefore, optimum monitor voltage corresponding to the concn. of oxygen in gas to be measured is automatically applied and the concn. oxygen can be measured with high accuracy. |
