Piezoelectric transformer inverter

摘要

A piezoelectric transformer inverter can be driven in wide ranges of input voltages and output currents so that a wide range of dimming can be achieved. Furthermore, the piezoelectric transformer inverter can maintain high efficiency in the overall driven ranges thereof so as to yield stable luminance. The above piezoelectric transformer inverter includes a piezoelectric transformer drive unit having conductive elements, switching elements, and a phase drive circuit to convert an inputted AC voltage into an AC voltage having a substantially constant frequency which is lower than the inputted AC voltage and output to a piezoelectric transformer, a phase-difference detecting unit for detecting the phase difference between a drive controlling signal of one of the switching elements and an output current or output voltage of the piezoelectric transformer to output a control voltage corresponding to the phase difference, and a frequency control circuit for outputting a pulse voltage signal of a frequency based on the control voltage to the phase drive circuit of the piezoelectric transformer drive unit.