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:
Jul. 10, 2001
Filed:
Aug. 25, 1998
Donald P. Matthews, Jr., Morgan Hill, CA (US);
Compaq Computer Corp., Houston, TX (US);
Abstract
A keyboard input device includes a processor repeatedly executing a scan routine to detect key press events while masking the events from an external monitoring means. The keyboard input device has a number of finger-activatable keys, each connected at the intersection of row signal lines and column signal lines, which are in turn connected to the processor. The processor systematically activates the rows and randomly activates the columns. A key press event causes the key's associated row and column to create a closed switch. The processor monitors the columns for a signal forced on pairs of rows. Obfuscating signals forced onto the columns inhibit detection of the key press event signals by an external source.