| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect an impedance with an excellent sensitivity and with safety confirming type structure in a direction that a detection output increases when an impedance change is on a safe side. SOLUTION: One end of an object of detection 12 is connected to a power source 11 and the other end is connected to the common contact of a change- over switch 13. To the change-over contact (a) of the change-over switch 13, one end of a first reference impedance element 14 of a large intrinsic impedance is connected. And to its change-over contact b one end of a second reference impedance element 15 of a small intrinsic impedance is connected, and the other ends of the first and second reference impedance elements 14, 15 are connected in common to the power source 11. When the impedance increasing side of the object of detection 12 is a safe side, the impedance is detected on the basis of the terminal-to-terminal voltage of the object of detection 12. And, when the impedance decreasing side of the object of detection 12 is the safe side, the impedance is detected on the basis of the terminal-to-terminal voltage of the second reference impedance element 15.</p> |
