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:
Feb. 23, 1993
Filed:
Oct. 16, 1990
David W Caldwell, Holland, MI (US);
Nicholas W Medendorp, Holland, MI (US);
Donnelly Corporation, Holland, MI (US);
Abstract
A circuit for detecting user contact of one of a plurality of touch pads includes a plurality of drive lines and a plurality of sense lines coupled with the touch pads. A sense circuit responsive to the signals on the sense lines produces a pulse having a width that is proportional to the amplitude of each of the sense signals. A control circuit measures the width of the pulses produced by the sense circuit and compares each measured pulse width to a reference pulse width to distinguish between a touch and no-touch condition for each touch pad. The sense circuit is illustrated in the form of a comparator having a threshold input that is always exceeded by the sense signal to produce the variable width pulse. Separate amplifiers may be provided for each sense line.