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:
Dec. 25, 1984
Filed:
Sep. 06, 1983
John C Echols, Ventura, CA (US);
Charles W Staufenberg, Santa Barbara, CA (US);
Essex-Tec Corporation, Carpinteria, CA (US);
Abstract
The high impedance output of a touch-sensitive piezoelectric sensor is coupled directly to the high impedance input of a CMOS (complementary metal oxide silicon field effect transistor pair). The CMOS is protected on its input side by clamps which restrict the voltage swing applied to the gates to within the range defined by the positive and negative CMOS bias supply (+V.sub.DD and -V.sub.SS). The sensor produces voltages of approximately equal magnitude in response to slow acting temperature changes and quicker acting manual touching. In order to distinguish piezoelectric from pyroelectric signals, the CMOS bias is periodically and briefly shorted, to ensure a brief return-to-zero of the sensor output, thereby effectively suppressing the slow acting pyroelectric signal without interfering with sensing of quick acting piezoelectric signals.