Chapter 6 - Improvement of Image Quality in AMLCDs

Abstract

The purpose of his chapter is to discuss improvement of image quality in active matrix liquid crystal display (AMLCD). Over the past 15 years, the performance of AMLCDs has radically improved. Depending on the requirements for a particular application, characteristics such as power consumption for portable devices, viewing angle for desktop monitors and televisions, contrast ratio, brightness, color gamut, and video response times for LCD televisions, have been optimized. Many efforts have gone into the development and commercialization of AMLCDs with application-specific optimization of the viewing characteristics. These improvements are described in this chapter. The brightness of transmissive LCDs depends to a large extent on the backlight intensity. The simplest way to increase display luminance is therefore to turn up the backlight or to design brighter backlights. A unique feature of LCDs is their potential for very low reflectance as compared to emissive displays such as plasma displays and electroluminescent displays. More saturated colors can be obtained with denser color filters, at the expense of luminance. A more attractive approach is to use a backlight with narrower peaks matching color filters with equally narrow width. To combat the peril of poor video quality in LCDs, two solutions are: response time compensation by overdrive techniques and emulation of impulse-type operation in an LCD.