Piezoelectric ultrasonic motor by co-extrusion process

A miniaturized piezoelectric ultrasonic motor (USM) composed of four rectangular piezoelectric plates (PZN-PZT) and a stator (PZN-PZT/Ag) was developed using a co-extrusion process. Two facing neighboring piezoelectric layers were poled in the outer direction of the stator, while two other layers were poled in the inward direction. The USM generated elliptical motion at its ends by combining the bending motions in the x- and y-axis of the stator when two voltage signals that were phase shifted by π/2 were applied at the electro-mechanical resonance frequency. The USM was operated at the first bending vibration mode (∼51 kHz) at 30 Vp-p. The maximum displacement of the x- and y-axis were 1.5 μm and 0.5 μm, respectively, which were high enough for use as a stator in USM applications.