1. General

1.1 Historical background. Benefits of the piezoelectric motor

The ancestor of the piezoelectric motor is perhaps the tuning fork watch motor developed by Bulova Watch Co. Ltd in the 60s, in which the vibration of a U-shaped resonator, excited by windings, is harnessed to rotate a finely toothed wheel. In 1973, H.V. Barth first described an electric motor based on piezoelectrically excited mechanical vibration in the IBM Technical Disclosure Bulletin. The relatively severe contact conditions involved in this motor led T. Sashida to propose, in 1982, the progressive wave structure that is still the most technically advanced solution today. This motorization was industrialized by Shinsei Co. Ltd in the late '80s, while Canon Co. Ltd marketed an autofocus lens with a motor of the same...