Piezoelectric ceramic transformer, with the suppression of the 2nd harmonic vibration.

Development of compact airborne ultrasonic emitter with an annular piezoelectric ceramic

“…Based on the above, we aim to develop an ultrasonic emitter with a resonance frequency of about 40 kHz and a diameter of 4 mm. To drive a vibration plate a few millimeters in diameter at a resonance frequency as 40 kHz, the thickness of the piezoelectric ceramics would have to be less than a few tens of micrometers, which is impractical [8]. Therefore, our ultrasonic emitter uses a thin metal film that is attached to annular piezoelectric ceramics, a technique that has been previously reported [9,10].…”

Modeling of a Disk-Type Piezoelectric Transformer

“…In the literature [2]- [10], many piezoelectric transformers have been proposed and a few of them have found practical applications. Apart from a switching power supply system, a Rosen-type PT has been adopted in cold cathode fluorescent lamp inverters for liquid-crystal display.…”