An array of infrared beams spanning the full height of the door opening that detects obstructions and reverses the closing door before contact.
Full Definition
A door light curtain (or multi-beam safety sensor) replaces or supplements the mechanical safety edge. Infrared transmitter LEDs on one door edge project beams across to receivers on the opposite edge, forming a detection grid typically with 50–70 mm beam spacing. Interruption of any beam triggers immediate door reversal. EN 81-20 §5.3 limits maximum kinetic energy during closing to 1.5 J; the light curtain ensures this limit is never approached with a person in the doorway. Full-height 3D curtain variants use multiple depth zones to detect objects partially protruding from the landing. Regular alignment and cleaning is required as contamination can cause false signals.
