| 摘要 |
PURPOSE:To obtain a self-diagnosis circuit which achieves self-diagnosis of a sensor without requiring an expensive calibration gas and without adversely influencing the actual measurement of a gas. CONSTITUTION:This circuit is provided with a reference resistance 3, a reference power source 4, a capacitor 5, a first-a fifth switches 6a-6e, an operational amplifier 7, an A/D converter 8a, a central processing unit 8b and an operating part 8 etc. The capacitor 5 is discharged to make the circuit conductive only for a fixed time. The value of the internal resistance 1 of the sensor is obtained by an operation with the use of the voltage before and after the connection and the capacity of the capacitor 5 and the like. |
