| 摘要 |
PURPOSE:To considerably decrease noise by independently applying the voltages at which respective potential difference become zero between a detecting electrode and plural conductor parts existing around the same. CONSTITUTION:Lead wires l1-l4 are connected respectively and discretely to an aperture plate AP, an electric field modulator 2, a detecting electrode supporting table 4, a casing 1 and a substrate 6 which are the conductor parts existing around a detecting electrode 3. Prescribed voltages are applied respectively and discretely from a voltage regulator VX to these lead wires l1-l4 and are so set that the potentials between the detecting electrode 3 and the respective conductor parts become zero. Since the contact potential differences produced between the respective parts and the potential differences owing to other causes are negated in this way, the noise produced based on this is considerably reduced. |
