Patent ID: 6181050
Filing Date: 2001-01-30
Classification: H02N

Abstract:
An electrostatic actuator comprising:a rotor having a plurality of rotor electrodes, a first DC rotor signal combined with a first AC dither signal provided to a first subset of the rotor electrodes and a second DC rotor signal combined with a second AC dither signal provided to a second subset of the rotor electrodes;a stator having a plurality of stator electrodes;a plurality of crossover networks coupled to the stator electrodes, with each crossover network of the plurality of crossover networks coupled to a different one of the stator electrodes;a plurality of demodulators, coupled to the plurality of crossover networks, with each of the plurality of demodulators coupled to a different one of the crossover networks; anda closed loop controller coupled to each of the demodulators and each of the crossover networks wherein said closed loop controller establishes an alternating variable voltage pattern on the array of drive electrodes to laterally move the rotor, determines the position of the rotor from the demodulated first and second dither signals sensed on the plurality of stator electrodes, and provides a common bias voltage to the drive electrodes when the rotor is in an unstable position to reduce the out of plane forces to zero.