AC TWOOWIRE TYPE TRANSMISSION PHOTOELECTRIC SWITCH

摘要

PURPOSE:To irradiate a pulse light having high peak value from a light emission unit by synchronizing the light emission unit through an AC power supply with a photodetector, setting the pulse light irradiated from the light emission unit at special phase of the frequency of the current from the AC power supply and improving the duty factor thereof. CONSTITUTION:An LED 128 in a light emission unit 100 is driven once per half wave at every half wave in predetermined phase in synchronization with the current from an AC power supply when full wave rectified waveform falls. A light receiving circuit 310 consists of a photodetector 311 and amplifying transistors 312, 313. When the pulse light is shielded by an article 200 to be detected, a SCR 332 is turned ON to thereby cause a load L to flow a current.