Patent ID: 8415903
Filing Date: 2013-04-09
Classification: H02N,Y10T

Abstract:
1. An ultrasonic motor in which driving signals of two phases are applied to a vibrator having a driving member in contact with a driven member to simultaneously generate a longitudinal vibration and a flexural vibration, thereby generating an elliptic vibration in the vibrator, and the driving member frictionally drives the driven member upon obtaining a driving force from the elliptic vibration, the motor comprising a driving phase difference switching unit which switches a driving phase difference serving as a phase difference between the driving signals of the two phases, and changes a switching cycle of the driving phase difference, wherein the driving phase difference switching unit switches between a first driving phase difference for obtaining a desired driving speed, and a second driving phase difference for generating a speed of a flexural vibration higher than a speed of a flexural vibration upon driving using the driving signals of the two phases corresponding to the first driving phase difference, the motor further comprises: a storage unit which stores a plurality of driving phase differences set in advance, and in which the driving phase difference switching unit switches between at least two driving phase differences among the plurality of driving phase differences, wherein the driving phase difference switching unit switches the driving phase difference in a cleaning mode in which the ultrasonic motor is reciprocally driven in a predetermined driving range by a plurality of number of times, and the ultrasonic motor includes a driving range enlarging unit which enlarges the driving range in driving in the cleaning mode.