A micro ultrasonic motor fabricated by hydrothermal method (1.4 mm in diameter and 5 mm in length stator transducer)

We succeeded in operating a micro ultrasonic motor whose cylindrical stator transducer was 1.4 [mm] in diameter and 5.0 [mm] long. A PZT thin film was deposited on the side wall of the stator transducer by improved hydrothermal method. This motor may be one of the smallest ultrasonic motors at this stage. The starting torque was 0.67 [/spl mu/Nm] with the conditions of 5.3 [mN] pre-load and 20 [Vp-p] input voltage. With the same conditions, maximum revolution speed was 680 [rpm].