A processor (18) receives signals from an electronic tablet (10) that represent the positions of a stylus (12) on the tablet surface. The processor operates a cathode-ray tube (20) to display the locations represented by the tablet signals and present scales for interpreting the display as values of...http://www.google.com.tw/patents/US4555699?utm_source=gb-gplus-share專利 US4555699 - Data-entry system
