US Patent 7110062 LCD with power saving features

Energy efficient transmissive and transreflective display devices use ambient light from a natural or artificial source to supplement light supplied by a backlight. Ambient light passes through a transmissive diffuser to a rear surface of a transmissive display panel. Additional energy efficiency is achieved by using one or more photo-sensors to detect the amount of ambient light and automatically adjusting the backlight intensity as a function of photo-sensor output. As a result, backlight intensity and power usage can be minimized while maintaining the viewability of images shown on the display.