Operating optical sensor for detecting objects - using periodically transmitting light source and receiver, evaluation unit extracting useful signal from measurement signal using noise signal measurements

摘要

The method involves transmitting a light signal to a receiver which detects essentially no light when no object is present in a detection region. When an object is present, the receiver receives light by reflection or transmission from it and a connected receiver signal evaluation device produces an object detection signal. Before and/or after the light signal is transmitted, a noise signal is received by the receiver. The information derived from the resulting receiver signal is used to extract the useful signal from the measurement signal, e.g. using linear interpolation. ADVANTAGE - High noise immunity, esp. in presence of periodic noise, e.g. stray light or electromagnetic radiation.