摘要 |
A photoelectric barrier provided with muting function comprises a plurality of light emitting diodes generating a set of beams (14) across a surveyed passage, for detection by respective photodiodes whose output signals are fed to a processing unit (UE). The barrier (10) also includes photoelectric sensors arranged inside an unsafe area (25) and comprising at least a pair of light emitters generating beams crossing the path of an object traveling through the passage, and detected by a pair of respective light receivers, whose output signals are fed to said processing unit (UE). The processing unit has timer means (T), exit time-out means (TO) and general time-out means (TOG), which cooperate to restore the barrier substantially immediately after the transit of articles authorized to transit. <IMAGE> |