The invention relates to an electrochromic contrast plate which is either arranged as a discrete unit in front of the screen or is connected to the outer surface of the screen through a common sheet, consisting of a pair of transparent glass or plastic sheets which are provided, on one side each, with...http://www.google.se/patents/US6344918?utm_source=gb-gplus-sharePatent US6344918 - Electrochromic contrast-plate
