Patent ID: 7474040

Claim:
A method for driving a dual-output piezoelectric transformer, comprising: providing a dual-output piezoelectric transformer, which comprises a rectangular piezoelectric piece with a first and second main faces, a pair of input electrodes mounted centrally on the first and the second main faces of the piece, which defines a input section with polarization direction along a thickness direction of the piece of the dual-output piezoelectric transformer, and a first and a second output electrodes mounted around surfaces of two ends of the piece, which defines the first and second output sections with polarization direction being a longitudinal direction of the piece of the dual-output piezoelectric transformer along with the pair of input electrodes; driving the dual-output piezoelectric transformer to its third mode resonance through backward piezoelectric effect by providing an alternating voltage of the third mode resonant frequency to the input electrodes of the dual-output piezoelectric transformer; and deriving driving signals for at least two loads respectively from the first and second output electrodes of the dual-output piezoelectric transformer through forward piezoelectric effect, wherein each the input electrode is a modal electrode, and A(x), a configuration of each the modal electrode, is configured as the following equation: A ⁡ ( x ) = sin ⁡ ( 3 ⁢ ⁢ π ⁢ ⁢ x L ) ⁢ { H ⁡ [ x - L 3 ] - H ⁡ [ x - 2 ⁢ L 3 ] } , wherein L, H and x are a length, a width and a coordinate along the longitudinal direction of the dual-output piezoelectric transformer respectively, and x has a value in the range of [0, L] and counting from one of the two ends.