The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 12, 1987
Filed:
Mar. 06, 1986
Clifford J Bader, West Chester, PA (US);
Systems Development Corporation, Camarillo, CA (US);
Abstract
The present disclosure describes circuit variants for reducing electromagnetic interference from saturable core keyboards to acceptable levels. The invention finds particular application in conjunction with capacitive-discharge scan techniques used in such keyboards. In order to attenuate the external field resulting from such techniques, a circuit is taught which effectively disconnects the scan line array from the capacitor charging circuit during the time between scans. A second variant, when added to the first, further reduces interference by disconnecting the entire scan circuit from the supply potential during the scan time thereby eliminating steady-state currents and turnoff oscillatory transients.