A coordinate position determining system and method includes a liquid crystal material separating first and second groups of conductors. The tablet is at least partially light transmissive, but may include a partially reflective layer. The first and second groups or conductors are sequentially scanned...http://www.google.com.tw/patents/US4977315?utm_source=gb-gplus-share專利 US4977315 - Liquid crystal position determining system and wand device
