Electrical characteristics of the contour-vibration-mode piezoelectric transformer with ring/dot electrode area ratio

Contour-vibration-mode Pb(Sb1/2Nb1/2)O-3-Pb(Zr, Ti)O-3 [PSN-PZT] piezoelectric transformers with different ring/dot electrode area ratios were fabricated to the size of 27.5 x 27.5 x 2.5 mm(3) by cold isostatic pressing. The electrical properties and characteristic temperature rises caused by the vibration were measured at various load resistances. Efficiencies above 90% with load resistance were obtained from all the transformers. The voltage step-up ratio appeared to be proportional to the dot electrode area. A 14 W fluorescent lamp, T5, was successfully driven by all of the fabricated transformers. The transformer with ring/dot electrode area ratio of 4.85 exhibited the best properties in terms of output power, efficiency and characteristic temperature rise, 14.88 W, 98% and 5 degrees C, respectively.