Alternately poled piezoelectric transformers using rectangular ceramic plates

In order to apply a piezoelectric transformer to an LCD backlight inverter, piezoelectric transformers are investigated [1, 2]. The load is a cold cathode fluorescent lamp (CCFL), whose impedance is low, about 100 kΩ. But the step-up ratio of the conventional Rosen-type piezoelectric transformer is small and inadequate for this application. We have developed a new piezoelectric transformer structure which has an alternately poled structure in a rectangular single-layer piezoelectric ceramic plate. Its step-up ratio is twice that of the Rosen-type transformer. Two types of samples were fabricated and analyzed using equivalent circuits, and the vibration characteristics and the electrical characteristics were evaluated. © 1998 Scripta Technica, 81(12): 29–36, 1998