Energy Conversion Devices, Inc.

Stanley Home Automation

Richard D Bates

A modulated light beam obstacle detector for use as a safety mechanism in an automatic closure operator which must operate in varying ambient light conditions. If the obstacle detector senses the interruption of the light beam, the motion of the door is arrested or reversed. The obstacle detector uses an auxiliary light source connected in a feedback circuit to maintain a constant background illumination on the light detector and thereby hold the light detector in conduction at all times. In this manner, the presence of the light beam can be sensed regardless of the ambient light conditions.

Method and apparatus for self-biasing a light beam obstacle detector

Disclosed is an image detection system having a photodetector, e.g. a photovoltaic cell, a photoconductor sheet, and a means, e.g., a liquid crystal light valve or an electrochromic light valve, matrix light valve having a plurality of individually addressable light valve cells. The image detection system also has means to identify the signal generated by the photodetector with the individual light cell switched to a light transmissive mode. Also disclosed is a method of detecting and updating an image using the image detection system.

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Ann Arbor, MI, United States of America

Richard D Bates