Keypad

Details Keypad Keypad

2006-11-07

2006-11-07

Chang, Kent (Department: 2629)

Computer graphics processing and selective visual display system

Display peripheral interface input device

Including keyboard

C345S170000, C713S184000

Reexamination Certificate

active

07133029

ABSTRACT:
A keypad is disclosed which has a plurality of keys (12) for the input of information. Each key has a first switch (80) and a second switch (90). The first switches (80) are all connected to a common electrical interconnection (120) and the second switches (90) are connected into a matrix electrical interconnection (62, 100). The microprocessor (66) detects a global signal on the common interconnection (120) and supplies scan signals to the matrix interconnection (62, 100) to enable detection of a particular key. The processor (66) may also selectively change the state of lines (62, 100) of the matrix and also maintain particular lines in a predetermined state by open drain ports of the processor to which the lines of the matrix are connected.

REFERENCES:
patent: 4926173 (1990-05-01), Frielink
patent: 5254989 (1993-10-01), Verrier et al.
patent: 5914677 (1999-06-01), Ahmadian
patent: 6040788 (2000-03-01), Chambers et al.
patent: 6054940 (2000-04-01), Greene
patent: 6424274 (2002-07-01), Schnizlein et al.
patent: 6426710 (2002-07-01), Chang et al.
patent: 2 223 115 (1990-03-01), None

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