A bilayer piezoelectric transformer operating in a bending vibration mode

A thin rectangular bar-shaped bilayer piezoelectric step-up transformer operating in the bending vibration mode is described and its characteristics are investigated. It consists of two lead zirconate titanate ceramic plates (32×8×1.5 mm3) with a high mechanical quality factor. The transformer has a symmetric structure in the length direction with the polarization aligned in the thickness direction. It has 2 input parts and 1 output part. The inputs are located at both ends of the length of the transformer with bilayer structures and the output is located at the centre portion with a single layer structure. When connecting a matching load resistance of 1.2 kΩ to the output terminal, the efficiency reaches 85% and the voltage gain is 5.5 at a driving frequency of 205 kHz. By using this bilayer structure, a piezoelectric transformer with bending vibration mode has been realized.