A light curtain system and method of operation which detects the intrusion of objects into a protected zone. The system is characterized in having an inherent self-checking mode of operation by logic circuits which analyze data signals from both the LED light transmitters and phototransistor receiver...http://www.google.fr/patents/US5015840?utm_source=gb-gplus-shareBrevet US5015840 - Self-checking light curtain system and method of operation
Self-checking light curtain system and method of operation
