A system for retrieving display data has a handheld device and a server. The handheld device includes an optical sensor for imaging an area of a printed substrate containing printed content; a processor for determining interaction data; a transceiver; and a touch-sensitive screen. The server is configured...http://www.google.se/patents/US8064092?utm_source=gb-gplus-sharePatent US8064092 - System for retrieving display data for handheld display device
