Trapezoidal and triangular waveform profiles for reducing power dissipation in liquid crystal displays

Abstract

We propose to replace the rectangular select pulses in all the conventional addressing techniques with either trapezoidal or triangular select waveforms to reduce the power dissipated in rms responding liquid crystal displays. A realistic analysis that includes the distortion in the addressing waveforms is presented for trapezoidal, triangular profiles, as well as their equivalents in discrete domain viz. the multi-step profiles and the results are compared. Good brightness uniformity among pixels that are driven to same state is achieved as a spinoff of the analysis and application of a correction voltage at the end of the select pulses. Increase in hardware complexity and the cost is minimal because just the voltage level generator circuit is modified to achieve reduction in power dissipation with new waveform profiles.