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:
Jan. 15, 1985
Filed:
Mar. 03, 1982
Antony J Wakeling, Fleet, GB;
Alan D Thompson, Fleet, GB;
Schlumberger Electronic (U.K.) Ltd., Farnborough, GB;
Abstract
A keyboard has tactile-feel keys (64-70) each with a grounded terminal (78) under an insulated touchable terminal (88) supplied with a square wave signal. Touching a key increases the capacitive delay of the square wave signal on that key, so it is retarded relative to first delayed clock pulse which then resets a bistable circuit (142) to stop a counter (152), which controls scanning of the keys, at a value indentifying the touched key. This enables selection of the touched key to be verified, for example on an associated video display, whereafter the key can be pressed to actuate it, thereby establishing contact between its terminals. The resulting grounding of the touchable terminal suppresses the square wave signal, resetting another bistable circuit (172) in response to another, more delayed, clock pulse to generate a signal indicating that the desired key function is to be implemented.