Scanned switch matrix

Details Scanned switch matrix Scanned switch matrix

1993-04-12

1995-07-04

Groody, James J.

Coded data generation or conversion

Bodily actuated code generator

Including keyboard or keypad

341 26, H03M 1100, G06F 302

Patent

active

054304431

ABSTRACT:
A switch matrix circuit is described that facilitates unambiguous detection of all two key selections in a scanned matrix of switches without requiring diode based isolation of the switches, software based interpretation or timing delays. The switch matrix circuit is applicable to keypads and the like and includes a matrix of switches arranged in a plurality of electrically connected rows and columns. Each row has a driver that is capable of selectively outputting a high impedance state and an active state. Each row also has a row sense amplifier for detecting the state of its associated row. Similarly, each column has a column sense amplifier for detecting the state of its associated column.

REFERENCES:
patent: 4633228 (1986-12-01), Larson
patent: 4906993 (1990-03-01), Freeman et al.
patent: 5057836 (1991-10-01), Inaba
patent: 5081453 (1992-01-01), Endoh et al.
patent: 5220601 (1993-06-01), Gulick et al.
Volker Soffel, MF2 Compatible Keyboard with COP8 Microcontrollers, Application Note 734, 1991, National Semiconductor Corporation.

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