1
Joseph E Phillips, John J Oskorep, Steven S Lee: Multiple key array. Susan L Lukasik, July 9, 1996: US05534860 (12 worldwide citation)

An apparatus for and method of scanning a key array (101-116) uses two or three scan lines (134 and 135 or 308, 309, and 310), thereby limiting the need for an excessive number of input/output lines of a processor (136). A separate resistor ladder (301,302, 303) is provided for each dimension of key ...


2
Qiu Quancheng, Wu Jinshan: Key input device for inputting characters with direction key and character inputting method. Inventec, Xu Zhiyong, Yan Tao, March 11, 2009: CN200710149557

The invention relates to a key input device which utilizes a direction key for inputting characters, and a character input method. The key input device comprises a mode key and a direction key. The character input method comprises the steps that the mode key is pressed successively to be used for ch ...