Piezoelectric inverter using thin plate transformer

Abstract

In order to apply a piezoelectric transformer to back lighting fluorescence lamp in a liquid crystal display, asymmetric extension vibration mode of a piezoelectric rectangular plate has been investigated with special reference to the power transfer efficiency upon electrically loaded by the fluorescence lamp. In spite of a simple and thin monolithic structure, the optimum transformer, 21.3 × 11 × 0.5 mm in size, indicated 96% power efficiency as well as up to 30 step-up ratio which corresponds to more than 4 times that of the conventional Rosen-type transformer. The transformer has been successfully incorporated into a small size inverter unit together with a newly developed IC element for controlling frequency to the resonance, with less than 2.2 mm total thickness.

Keywords:

• Piezoelectric Transformer
• Inverter
• Back light inverter
• Cold fluorescent lamp
• Asymmetric extension mode