| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor that can efficiently generate a torsional resonance vibration by positively using the flexural vibration of a piezo-electric element. <P>SOLUTION: An ultrasonic motor comprises at least: a vibrator whose cross section perpendicular to a central axis has a rectangular length ratio; and a rotor which is rotationally driven as a rotational axis using a central axis which contacts an oval vibration generation surface of the vibrator and is orthogonal to the oval vibration generation surface of the vibrator. The ultrasonic motor forms an oval vibration by combining a longitudinal primary resonant vibration expanding/contracting in the rotational axis direction of the vibrator and a torsional secondary resonant vibration using the rotational axis as a torsional axis or a torsional tertiary resonant vibration. The rectangular length ratio of the vibrator is set such that the resonant frequencies approximately correspond with each other among the longitudinal primary resonant vibration expanding/contracting in the rotational axis direction of the vibrator and the torsional secondary resonant vibration using the rotational axis as the torsional axis or the torsional tertiary resonant vibration. The vibrator comprises two polarization axes in two respective polarization directions each of which forms a sharp angle against the rotational axis. <P>COPYRIGHT: (C)2013,JPO&INPIT |
