Detection system sensing people on moving staircase - uses light source, parallel reflecting strips and photodetector, preventing restart after emergency stop

摘要

The detection system has two parallel reflecting strips located one each side of the stair treads just above their surface. A light source at, e.g. the bottom of the staircase, directs light at an angle onto one reflecting strip. This light is reflected alternately from one strip to the other, zig-zagging across the staircase, finally being received by a photodetector located at the top of the staircase. Any person on the staircase interrupts the light beam and causes the photodetector's output to change. The system prevents the staircase being started after an emergency stop. The staircase cannot be restarted if a person is on it and therefore likely to be in danger.