LCD driver with adjustable contrast

摘要

An LCD display driver provides adjustable contrast independent of multiplexing requirements by generating each COM signal in a time slot of a repeating signal frame, with each COM signal containing one or more active periods and one or more inactive periods. The relative time proportions of these periods are adjustable. Corresponding SEGMENT signals turn on/off required segments while maintaining an essentially zero DC component. The logic levels and the relative active time and inactive times of the COM and segment signals being adjustable for increasing or decreasing the RMS voltage levels across the LCD element as desired.