DRIVE CIRCUITS FOR CAPACITIVE LOADS

摘要

A drive circuit for driving electroluminescent (EL) segments and polymer dispersed liquid crystal (PDLC) segment of a display. The circuit comprises a flyback converter (11) for generating an A. C. output voltage, a first switching circuit (12) for selectively connecting the output voltage to the EL segments and a second switching circuit (13) for selectively connecting the output voltage to the PDLC segments. In order to drive the EL segments and PDLC segments at the required frequencies, the polarity of the output voltage applied to the PDLC segments is swapped at a frequency lower than the frequency at which the polarity of the output voltage is swapped for the EL segments. In this way, only a single high voltage power supply is required to drive both the EL and PDLC segments.