Key switch scanning and encoding system

Details Key switch scanning and encoding system Key switch scanning and encoding system

1974-10-29

1976-08-10

Yusko, Donald J.

Communications: electrical

Digital comparator systems

340365S, 340147P, G06F 302, H04Q 900

Patent

active

039744787

ABSTRACT:
In this key switch scanning and encoding system, open (OFF) switches may be scanned at a faster rate than closed (ON) switches, and a coded signal is produced indicative of each closed switch. The switches are arranged in a matrix of M groups each connected to N common output lines. The switch groups are enabled sequentially, one at a time. As each group of switches is enabled, the N output lines sequentially are gated to a coding matrix. If the gated line is associated with a closed switch in the enabled group, an output code is produced by the code matrix, which, together with a signal designating the enabled group, uniquely identifies the closed switch. Scanning is delayed briefly to permit utilization of the encoded output. If an open (OFF) switch is scanned, no code is produced by the code matrix. This no-code condition immediately causes the next switch matrix output line to be gated to the code matrix. In this way, open switches are "skipped over" or scanned at a rapid rate. The system is particularly useful in an electronic musical instrument.

REFERENCES:
patent: 3662378 (1972-05-01), MacArthur
patent: 3750160 (1973-07-01), Elzinga
patent: 3792466 (1974-02-01), Arnold et al.

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