| 摘要 |
An electrostatic actuator includes a movable piece provided on a substrate via supporting beams such that the movable piece can be displaced in the Y-axial direction. The movable piece is displaced by an electrostatic force between movable and stationary electrodes to drive a mirror, so that an optical path of an optical device is switched over. The electrode plates of the movable electrode have lengths in the Y-axial direction which are stepwise decreased in order from the electrode plate nearest to the movable piece to the electrode plate farthest from the movable piece. Thus, the total overlapping length of the electrode plates of the stationary and movable electrodes is reduced to a minimum smallest value. Therefore, even if the sizes of the electrode plates are varied, the movable piece is prevented from being displaced and inclined due to electrostatic forces in the X-axial direction. Thus, the movable piece is stably operated.
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