Patent ID: 7667372
Filing Date: 2010-02-23
Classification: H02N

Abstract:
1. An apparatus comprising two piezo-element driving units, each of the two piezo-element driving units comprising at least: an output connectable to a piezo-element, a voltage step-up module having a node wherein a voltage of said node is adapted to be an alternating voltage whose maximum is higher than a voltage of a power supply, said at least one capacitor being adapted to be disconnected from said node during said charging, and said second switch being adapted to transfer charge from said piezo-element to said at least one capacitor and back from said at least one capacitor to said piezo-element such that said at least one capacitor is disconnected from said voltage step-up module during the charge transfer in both directions; wherein the outputs of the two piezo-element driving units are in different phases.