PIEZOELECTRIC TRANSFORMER

摘要

A piezoelectric transformer has a piezoelectric substrate having first and second main faces. The substrate has first and second primary-side regions and a secondary-side region in its longitudinal direction in this order. The first region has a length of a half wavelength of stress distribution at the time of resonance in the longitudinal direction and has either positive or negative stress. The second region has a length of a half wavelength or less of the stress distribution and has either positive or negative stress. First and second electrode are respectively disposed on the first and second main faces in the first primary-side region, and the substrate between the first and second electrodes is polarized in the thicknesswise direction. Third and fourth electrodes are respectively disposed on the first and second main faces in the second primary-side region, and the substrate between the third and fourth electrodes is polarized in the thicknesswise direction. A secondary-side electrode is disposed in the secondary-side region, and the secondary-side region is polarized in the longitudinal direction. Directions of polarization and stress of the first and second regions and the electrical connection among the first to fourth electrode are determined in order for the second region to enhance the resonance of the substrate excited by the first region.