INFRARED RAY HUMAN BODY DETECTOR

PROBLEM TO BE SOLVED: To provide an infrared ray human body detector for eliminating the influence of external disturbances such as small animals, insects, the cold air and hot air of an air conditioning apparatus, sunlight, radio waves and mechanical noise, etc. SOLUTION: Plural optical systems for converging infrared ray energy are arrayed with prescribed intervals along the moving direction of a human body and the detection beams of the optical systems 1a and 1b to be one pair are set so as to make the edge parts of a surface where the human body crosses to be almost parallel to each other and to make a vertical direction to be different from each other for the angle of a detection axis. This detector is constituted of a time limit circuit 7 activated in the case that input fluctuation higher than a prescribed level is present in the respective optical systems 1a and 1b, a circuit 12 for making the activation time difference of the time limit circuit 7 in the pair of the optical systems 1a and 1b to pulses and discriminating the pulses of more than a fixed pulse width, a control circuit 16 and an alarming device 19.