Vibration actuator and lens barrel

摘要

A vibration actuator drive device using a linear type of ultrasonic actuator to drive a rotary member with high accuracy and good efficiency. The vibration actuator drive device includes an ultrasonic actuator which, by applying drive signals, produces longitudinal vibration and bending vibration to generate a drive force, and a rotary member in contact with the ultrasonic actuator. The combination of longitudinal vibration and bending vibration in the ultrasonic actuator generates relative motion in the rotary member having a circular locus of predetermined width. A compression mechanism causes compressive contact of the ultrasonic actuator with the rotary member. The longitudinal vibration vibrates in a direction about parallel to the direction of the drive force, and the bending vibration vibrates in a direction intersecting the longitudinal vibration. A drive force is transmitted to the rotary member at the inner circumferential side of the circular locus, and greatly differs from the drive force which is transmitted to the rotary member at the outer circumferential side. A lens barrel including a vibration actuator drive device drives a focus adjustment lens group in the optical axis direction by the conversion of the rotary motion of the rotary member to linear motion.