Patent ID: 6882085

Claim:
An ultrasonic motor comprising: a generally cylindrical stator that has first and second axial ends and includes: at least one piezoelectric element that generates a longitudinal vibration upon application of a high frequency voltage to the at least one piezoelectric element; and a plurality of metal blocks that are connected to the at least one piezoelectric element, wherein one of the metal blocks includes: a plurality of vibration converting portions that generate a torsional vibration in response to the longitudinal vibration and are arranged in an outer peripheral surface of the one of the metal blocks at generally equal angular intervals, wherein each vibration converting portion has first and second axial ends, which are opposed to one another in a direction generally parallel to an axial direction of the stator and are oriented toward the first and second axial ends, respectively, of the stator; and a plurality of securing projections that engage with an external member and are arranged in the outer peripheral surface of the one of the metal blocks at generally equal angular intervals, wherein each securing projection is circumferentially located between corresponding two of the vibration converting portions and has first and second axial ends, which are opposed to one another in a direction generally parallel to the axial direction of the stator and are oriented toward the first and second axial ends, respectively, of the stator, and the first axial end of each securing projection is axially positioned within an axial extent of the vibration converting portions, which is measured in the axial direction of the stator, in such a manner that the first axial end of the securing projection is axially spaced away from one axial end of the axial extent of the vibration converting portions, at which the second axial ends of the vibration converting portions are located; and a generally cylindrical rotor that is slidably and rotatably urged against the stator, wherein the rotor is rotated upon application of the longitudinal vibration and the torsional vibration to the rotor.