A keyboard type input device has multiple key positions provided as character entry keys. Each key corresponds to one key in the selected row of the conventional QWERTY keyboard. A second set of control buttons provide for the selection of which row of a conventional QWERTY keyboard are represented by...http://www.google.com.hk/patents/US7439957?utm_source=gb-gplus-share專利 US7439957 - Compact universal keyboard
