Data entry and display apparatus and methods that provide greater efficiency in data processing devices. The apparatus comprises a keypad with a plurality of first keys and plurality of secondary keys, the first keys each having at least one primary alphanumeric symbol and at least one of the first keys...http://www.google.com.hk/patents/US7113172?utm_source=gb-gplus-share專利 US7113172 - Alphanumeric keypad and display system and method
