A high contrast twisted nematic liquid crystal cell in which outgoing or reflected light is linearly polarized and has the same polarization angle as incoming or incident light when the cell is in an off state. Matching the polarization axes of incoming and outgoing light allows less light to pass through...http://www.google.com/patents/US6833894?utm_source=gb-gplus-sharePatent US6833894 - Enhanced contrast ratio for twisted nematic liquid crystal devices
