Patent ID: 6091064
Filing Date: 2000-07-18
Classification: G01V

Abstract:
A photoelectric safety system for use with a mobile carriage having a top and opposed ends and moveable along a floor adjacent an aisle that opens and closes in response to movement of the mobile carriage comprising:a. a plurality of transmitters arranged solely in a closely spaced cluster at a single predetermined location on the mobile carriage, the transmitters emitting respective beams across the aisle;b. circuit means for controlling the transmitters to emit the beams therefrom intermittently at a predetermined frequency;c. a number of photoelectric receivers equal to at least one greater than the number of the photoelectric transmitters and located across the aisle from the mobile carriage, each receiver being located to detect the intermittent beam emitted from at least one transmitter; andd. control means for cooperating with the receivers to enable the mobile carriage to move so long as every receiver detects the intermittent beam from at least one transmitter at the predetermined frequency and to prevent the carriage from moving when any receiver does not detect a beam from at least one transmitter.