Patent ID: 6134133
Filing Date: 2000-10-17
Classification: H02M

Abstract:
A piezoelectric transformer inverter comprising:an inverter unit including a ceramic piezoelectric transformer whose secondary terminal is to be connected to a fluorescent tube, a drive unit which is connected to a primary terminal of the ceramic piezoelectric transformer, and an inverter control circuit for controlling luminance of the fluorescent tube to a desired value;a step-down chopper unit for inputting a signal to the drive circuit of the inventor unit, the chopper unit including a switching device which is connected between an input voltage and a free wheeling device, and a pulse width modulation feedback control circuit connected to the switching device for providing feedback control thereto to maintain an average voltage of a rectangular-wave output voltage of the switching device constant; andmeans for restricting the duty cycle of the chopper unit so that it is not greater than a given amount.