| 摘要 |
PURPOSE:To accurately detect the concn. of oxygen by connecting a series circuit consisting of a resistor and a capacitative impedance element to the phase correction resistor of the voltage dividing circuit in a current/voltage converter circuit and setting the junction point of the resistor and the element to a conversion output terminal. CONSTITUTION:A solid electrolyte material 1 and an electrode pair 5a, 5b act as an oxygen pump element 7 and the electrolyte material 1 and an electrode pair 6a, 6b act as a battery element 8. A series circuit of a resistor 12 for correcting a phase and a resistor 13 for detecting a current is connected between the reversal input terminal and output terminal of an operational amplifying circuit 11 and the frequency characteristics of the output terminal of a current/voltage converter circuit 20 are set to high-pass characteristics. The AC resistance of a battery 22 becomes low in a high frequency region and the voltage Vb at a conversion output terminal becomes almost equal to the connection line resistance of the resistors 12, 13 and the detection gain of an oxygen concn. detection element is secured by the resistor 12. The AC resistance of the battery 22 becomes high in a low frequency region and the voltage Vb becomes equal to voltage Va and the voltage drop due to the resistor 12 can be prevented and the voltage corresponding to the generated voltage Vs of the element 8 is obtained from a differential amplifying circuit 15. |
