Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1982-03-26
1985-09-24
Groody, James J.
Communications: electrical
Audible indication
Percussion-type sound producer
200DIG1, 340365S, 361287, G06F 302
Patent
active
045435642
ABSTRACT:
Apparatus for suppressing interference in a capacitive keyboard. Unconditioned operating signals from receiving lines are passed into a subtractor, which establishes the difference between the signal present on a reference line in the keyboard and supplies, at the output, a conditioned operating signal which is free from any unwanted electromagnetic component which may have entered the structure. In addition, in order to determine which of several keys is supplying the highest signal, operating signals corresponding to particular receiving lines are scanned in sequence to determine which has the highest amplitude. As the operating signal corresponding to each successive key is scanned, its voltage is compared with a previously-stored voltage for an earlier-scanned key. If a higher voltage is detected, the voltage and key address are stored in place of the previously-stored values.
REFERENCES:
patent: 4145748 (1979-03-01), Eichelberger
patent: 4211915 (1980-07-01), Miller
patent: 4257117 (1981-03-01), Besson
patent: 4291303 (1981-09-01), Cutler
patent: 4305135 (1981-12-01), Dahl
Audoin Marcel
Fedeli Jean-Marc
Poujois Robert
Commissariat a l''Energie Atomique
Groody James J.
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