| 摘要 |
PURPOSE:To enable a posture of a movable electrode to be controlled stably and obtain a stable output characteristic by specifying so that the dimensions, shape, etc., of the movable electrode and a cantilever satisfy certain conditions. CONSTITUTION:A cantilever 2 is deformed when a servo system does not operate and fixed electrodes 3 and 4 can be displaced up and down. A difference C=C1-C2 between electrostatic capacities C1 and C2 between the electrodes 3 and 4 and a movable electrode 1 is measured by a C detection circuit 5, thus enabling a position of the electrodes 3 and 4 for the electrode 1 to be detected. Also, a pulse width modulation circuit 7 controls a duty ratio D of a pulse voltage which is applied to the electrodes 3 and 4 so that C=0 can be obtained and an inverter 8 applies an inverted pulse voltage of the pulse voltage to be applied to the electrode 3 to the electrode 4. Then, shape, dimensions, and application voltage of the electrodes 1, 3, and 4 and the lever 2 are set so that a posture where a sum of a change in electrostatic energy and change in elastic energy due to deformation of the lever 2 always becomes positive for an arbitrary fine change of the posture of the electrode 1. |
