PROBLEM TO BE SOLVED: To provide a structure that can suppress pull-in of an elastic part even when a drive voltage is increased in order to increase a movable amount, in an actuator including a comb electrode or a variable shape mirror using the same.SOLUTION: An electrostatic comb actuator has a support part 105, a plurality of stationary comb electrodes 108 extending from the support part, a movable part 103, an elastic part 104 connecting the support part and the movable part, and a plurality of movable comb electrodes 106 extending from the movable part in substantially parallel to the stationary comb electrodes, and arranged alternately with the stationary comb electrodes. The movable part is driven by an electrostatic force which acts between the stationary comb electrodes and the movable comb electrodes. The same voltage as for the movable comb electrodes is applied to the elastic part when the movable part is driven. Between the elastic part and a portion closest to the elastic part in a direction perpendicular to a direction in which the elastic part extends as viewed from a moving direction of the movable part, out of portions having the same potential as the support part when the movable part is driven, a structure 140 is arranged where the same voltage as for the elastic part is applied.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2017,JPO&INPIT【課題】櫛歯電極を含むアクチュエータやそれを用いる可変形状ミラー等で、可動量を大きくする為に駆動電圧を大きくするときにも弾性部のプルインを抑制できる構造を提供する。【解決手段】静電櫛歯アクチュエータは、支持部105と、支持部から延出する複数の固定櫛歯電極108と、可動部103と、支持部と可動部とを繋ぐ弾性部104と、可動部から固定櫛歯電極と略平行に延出しかつ固定櫛歯電極と交互に配置された複数の可動櫛歯電極106と、を有する。可動部は、固定櫛歯電極と可動櫛歯電極との間に働く静電気力によって駆動され、弾性部は、可動部の駆動時において可動櫛歯電極と同じ電圧が印加される。可動部の駆動時に支持部と同電位となる部分のうち、可動部の可動方向から見たときに弾性部の延びる方向に垂直な方向において弾性部に最も近い部分と、弾性部と、の間に、弾性部と同じ電圧が印加される構造部140が配置される。【選択図】図1
