| 摘要 |
A security device for conveying systems with unmanned vehicles, for monitoring a given area. The security device comprises at least two oppositely directed light barriers associated with said given area and each of said at least two light barriers comprises means for emitting a light-beam, first means for reflecting said light-beam and means for receiving said reflected light-beam. The at least two light barriers are disposed such that their light-beams are interrupted by objects entering said given area. Second means for reflecting said light beams are arranged laterally on object which are allowed to enter said given area, thereby making these objects undetectable for the security device. |
