THERMAL RAY TYPE AUTOMATIC SWITCH

摘要

PROBLEM TO BE SOLVED: To avoid inconvenience due to sudden turn-out of a lighting load by making prediction till a holding time is expired. SOLUTION: When a pyroelectric sensor 1 detects a thermal ray emitted from a person in a sensing area, the inside of a microcomputer 2 generates a detection signal representing the presence of the person. The microcomputer 2 sets a holding time T2 and a prediction time T2 that is shorter than the holding time T2 on the occurrence of the detection signal and lights up a lighting load 5 entirely. When the prediction time T1 elapses, the microcomputer predicts it that the expiration of the holding time T2 is close by diminishing the optical output of the lighting load 5 for the prediction purpose. When the person moves for a period of the prediction diminish, another detection signal is generated and then the microcomputer sets again the prediction time T2 and the holding time T2 .