Patent ID: 7492078

Claim:
A circular piezoelectric apparatus, comprising: an electrode assembly which has an independent electrode located on a perimeter side wall of the circular piezoelectric apparatus and two separated electrodes located respectively at two opposite surfaces of the circular piezoelectric apparatus; a first structure which is located between the two separated electrodes and has a polarized direction coinciding with a first axial direction directing from one electrode of the two separated electrodes to the other electrode thereof; and a second structure surrounding the first structure about the first axial direction and having another polarized direction coincided with a radial direction of the perimeter; wherein one of the three electrodes is electrically connected to a ground electrode to provide a voltage source for supplying an input voltage and a load through at least a conductive wire, another electrode is electrically connected to an input electrode through another conductive wire, and the remaining one electrode becomes an output electrode by stepping-up or stepping-down of an input voltage of the voltage source through the input electrode and the polarized directions of the first and second structures, the output and input electrodes being located respectively on the first and second structures, the ground electrode being one of the two separated electrodes; and wherein the first structure and the second structure form an arched portion abutting the edge of a polarized spot thereof to suppress waveform interference.