Abstract: An electroluminescent circuit for driving an electroluminescent display having a plurality of segment electrodes and a common electrode. The circuit comprises a DC power supply, an output terminal for each of the segments and common electrodes and at least one supply half H-bridge for connecting at least one of each of the segment electrodes and the common electrode selectively to one of the DC supply and a reference voltage. Each supply half H-bridge comprises a top switch and a bottom switch in series having a junction between them. The top switch is connected to the DC supply and the bottom switch is connected to a reference voltage. A discharge circuit is provided for selectively discharging the electroluminescent display, the discharge circuit comprising a discharge half H-bridge in which a top switch is connected to the DC supply and to a discharge path.

Abstract: A drive circuit for driving electroluminescent (EL) segments and polymer dispersed liquid crystal (PDLC) segment of a display. The circuit may include a flyback converter for generating an A.C. output voltage, a first switching circuit for selectively connecting the output voltage to the EL segments, and a second switching circuit 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.