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:
Sep. 24, 2002
Filed:
Dec. 15, 2000
Christopher J. O'Connor, Northville, MI (US);
Stephen A. Hawley, Bedford, MA (US);
Prospects, Corp., Novi, MI (US);
Abstract
An object detection system employs a photo-emitter and photo-detector for synchronously detecting and processing an optical signal reflected from an object in a pinch zone of a window or door opening. A photo-emitter light signal is modulated by a modulation signal having an active phase and an inactive phase. The optical detector provides an optical detector signal that is a function of the intensity of the received light. The detected light signal is synchronously detected using a switching amplifier that multiplies the reflected modulated light signal by a first gain during the active phase and by a second gain during the inactive phase. The duration of the active and inactive phases and the first and second gains are selected such that the system gain will average to zero for ambient light when integrated over a predetermined measurement period. The synchronously detected signal is subtracted from a predetermined offset voltage, and this difference is then integrated over the measurement period. The output of the integrator is then compared to a predetermined threshold value.