| 摘要 |
In a capacity type sensor including a guard electrode which is disposed between a first electrode and a second electrode, an alternating current potential difference between the first electrode and the guard electrode is made substantially close to zero by a potential equalizing means, and impedance change between the first electrode and the second electrode is detected by a capacity type sensor detecting means, parasitic capacity does not function as capacitor, and the effect of the parasitic capacity to detected capacity can be cancelled in appearance, by making the potential difference at both ends of the parasitic capacity which arises between the first electrode and the guard electrode, smaller in appearance or substantially zero, resultantly, only amount of capacity change can be detected. |
