Monitoring system for presence of passengers on escalator - uses sequenced groups of IR emitters and photodetectors which are pulsed at same frequency by passenger

摘要

At least one transmission circuit (2) comprises several infrared emitters (25) distributed at regular intervals along one edge of the escalator, and operated in sequence by a control circuit (20). In the corresp. receiving circuit(s) several infrared detectors (35) are arranged facing them across the escalator, with a control circuit (30) which applies the detector outputs successively to a response line (103,203). - The emitters (25) are controlled in repetitive cycles at a predetermined rate. The detectors (35) are operated at the same frequency so that each can sense a pulse from the facing emitter, unless the path is blocked by a passenger. The detected outputs are evaluated by a processor and controller (1). Alternate emitters (25) and detectors (35) advantageously are connected in two independent gps. or channels with separate response lines.(1/5)