Gray shades in LCDs using amplitude modulation

Abstract

Gray shades are essential to reproduce images on displays. Amplitude modulation technique allows a large number of gray shades to be displayed in liquid crystal displays (LCDs). Number of voltage levels in the addressing waveforms of amplitude modulation is at least twice the desired number of gray shades. Hence, hardware complexity of the column driver is high as compared to other techniques for displaying gray shades. We propose a technique to reduce hardware complexity of the column driver for amplitude modulation by about 50%. The design of a controller for amplitude modulation based on line-by-line addressing is also discussed.