Patent ID: 7999439
Filing Date: 2011-08-16
Classification: H02N

Abstract:
1. A linear drive ultrasonic motor comprising at least: an ultrasonic vibrator having a piezoelectric element; a driven member which is driven by a frictional force between the driven member and the ultrasonic vibrator; a pressing member which presses the ultrasonic vibrator such that a frictional force is generated between the ultrasonic vibrator and the driven member; a case member which accommodates the ultrasonic vibrator and the pressing member; and a base member which movably supports the driven member; wherein the case member is assembled with the base member, in a state of a central portion of the pressing member making a contact with the ultrasonic vibrator, and two end portions sandwiching at least the central portion, from among the end portions of the pressing member making a contact with the case member; a distance (A) in a direction of height from a surface of the case member in contact with the pressing member, up to a fixing or a latching surface with the base member, a distance (B) in a direction of height from a surface of the pressing member in a natural state without being bent, in contact with the case member, up to a surface of contact with the ultrasonic vibrator, a distance (C) in a direction of height from a surface of the ultrasonic vibrator in contact with the pressing member, up to a surface of contact with the driven member, a distance (D) in a direction of height from a surface of the driven member in contact with the ultrasonic vibrator, up to a surface of the base member fixing or latching with the case member, and an amount of deformation by bending (X) in a direction of height which generates a desired thrust of the pressing member satisfy a relationship (A)=(B)+(C)+(D)−(X).