Piezoelectric drive device for electric shaver, has drive circuit that specifies stimulation voltage amplitude so that effective electrical power taken up does not decrease with increasing load

摘要

The device has a drive circuit for supplying at least one piezoelectric resonator (10) with at least one stimulation a.c. voltage to stimulate mechanical vibrations and a unit for determining the effective power fed to the resonator from the stimulation voltage and the current through the resonator. The drive circuit specifies the stimulation voltage amplitude so the effective electrical power taken up does not decrease with increasing load Independent claims are also included for the following: an electric shaver for an inventive device and a control method for an inventive device.