Patent ID: 7202592

Claim:
A piezoelectric transformer comprising: a piezoelectric ceramic disc which has one face and the other face opposite to each other in a thickness direction; a pair of low-impedance portions which are disposed in the piezoelectric ceramic disc symmetrically with respect to a central axis of the piezoelectric ceramic disc so as to act as one of a driving portion and a generator portion; and a pair of high-impedance portions which are disposed in the piezoelectric ceramic disc symmetrically with respect to the central axis so as to be electrically separated from the low-impedance portions and act as the other of the driving portion and the generator portion; and an electrode member and a further electrode member which are, respectively, provided on the one face and the other face of the piezoelectric ceramic disc such that the piezoelectric ceramic disc is polarized only in the thickness direction between said electrode member and said further electrode member; wherein the piezoelectric transformer is adapted to be driven in a radial extensional vibration mode of the piezoelectric ceramic disc.