Patent ID: 7091648
Filing Date: 2006-08-15
Classification: H02K,H02N

Abstract:
1. An electrostatic actuator comprising: a movable element which is provided with electrodes; and a stator which is provided with driving electrodes and inductive electrodes for generating electrostatic induction in the electrodes of the movable element, wherein the electrodes of the movable element includes a driven electrode part provided at a position opposite to the driving electrodes of the stator, and an induced electrode part provided at a position opposite to the inductive electrodes of the stator; and the movable element is displaced relatively to the stator by generating electrostatic force between the driving electrodes of the stator and the driven electrode part in the movable element in which the electrostatic induction is generated, by applying a voltage to the driving electrodes of the stator, while generating electrostatic induction in the electrodes of the movable element through the induced electrode part by applying a voltage to the inductive electrode of the stator; wherein the electrodes of the movable element includes a first electrode and a second electrode which are shaped substantially comb-like and interdigitated; the induced electrode part corresponds to the base of the substantially comb-like electrode; and the driven electrode part corresponds to the comb tooth including the comb tooth end of the substantially comb-like electrode; wherein the movable element is placed on the front surface of the stator and the movable element which has no electrical connection is displaced by applying a first AC voltage to the inductive electrodes of the stator and a second AC voltage to the driving electrodes of the stator; and wherein the stator has the inductive electrodes and the driving electrodes connected and placed by four pieces with a predetermined cycle; the movable element has the first electrode and the second electrode which are interdigitated; the arrangement pitch of the first and second electrodes of the movable element is double the arrangement pitch of the driving electrodes of the stator; and a first traveling wave is generated in the electrode array of the movable element by generating electric charges in the first and second electrodes of the movable element by applying the first AC voltage to the inductive electrode of the stator, and a second traveling wave is generated in the driving electrode array by applying the four-phase second AC voltage to the driving electrodes of the stator, and the movable element is displaced according to the change with time of the first and second traveling waves.