Switch matrix key closure validation device and method

Details Switch matrix key closure validation device and method Switch matrix key closure validation device and method

1983-03-11

1986-04-08

Caldwell, Sr., John W.

Communications: electrical

Audible indication

Percussion-type sound producer

340365R, 340365S, H04L 300, G08B 536

Patent

active

045816034

ABSTRACT:
A keyboard or switch matrix key closure validation device and method for a terminal, calculator, desktop computer, or the like is described. The keyboard or switch matrix consists of a matrix of momentary switching elements on "keys" whose number is larger than the number of rows or number of columns in the matrix. A microprocessor provides sequential scanning of the keys in the matrix. The microprocessor also provides detection of closed keys. Upon such detection the microprocessor performs a test for protection against pseudo keys, a debounce test and a detease test. Pseudo key protection is accomplished without each matrix key location having an associated isolation diode. Debounce testing is performed with an extendable bounce period.

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Bland and Bolt, "Phantom Key Detection/Phantom Key Scan Code", IBM Technical Disclosure Bulletin, vol. 27, No. 7A, Dec. 1984.

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