Patent ID: 8716919
Filing Date: 2014-05-06
Classification: H02N

Abstract:
1. A drive apparatus comprising: a movable unit configured to include a first sliding surface and rotatably move about an axis of rotation; a vibration generating unit configured to generate vibrations; a vibration transmitting unit configured to include a second sliding surface in contact with the first sliding surface of the movable unit, and transmit the vibrations generated by the vibration generating unit to the movable unit via the first and second sliding surfaces; a pre-pressure applying unit configured to apply pre-pressure to the movable unit via the vibration transmitting unit; and a driving force generating unit configured to generate a driving force for driving the movable unit in a predetermined direction, the driving force being greater than a friction force between the first sliding surface and the second sliding surface when the vibrations are being transmitted to the vibration transmitting unit, the driving force being smaller than the friction force when the vibrations are not being transmitted to the vibration transmitting unit, wherein the pre-pressure applying unit includes an electromagnet, a closed-loop magnetic flux generated by the electromagnet forming a magnetic path, the magnetic path magnetically connecting the pre-pressure applying unit and the vibration transmitting unit, the magnetic path magnetically connecting the vibration transmitting unit and the movable unit, the vibration transmitting unit includes a permanent magnet, a closed-loop magnetic flux generated by the permanent magnet forming a magnetic path, the magnetic path magnetically connecting the vibration transmitting unit and the pre-pressure applying unit, the magnetic path magnetically connecting the vibration transmitting unit and the movable unit, and the drive apparatus further comprises an electromagnet driver that adjusts first pre-pressure and second pre-pressure through an excitation current of the electromagnet, the first pre-pressure being generated between the vibration transmitting unit and the pre-pressure applying part, the second pre-pressure being generated between the vibration transmitting unit and the movable unit.