| 摘要 |
The barrier comprises several infrared emitting diodes 5, multiplexed and modulated at a predetermined frequency, a reception unit 6 having several photoreceivers 7, and an apparatus 8 for management of the signals generated by the photoreceivers. The apparatus 8 comprises means 14, 52 of calculating the number of photoreceivers that are considered to be in use, means 14, 56, 57 to verify the presence of a single one of the photoreceivers that is considered to be malfunctioning if it generates a signal of value less than a predetermined value for a time greater than a predetermined time, and means 14, 57 of controlling the exclusion of the malfunctioning photoreceiver. The apparatus can thus fulfil its functions even when the unit 6 is degraded in functionality, since the photoreceivers in use are fewer in number than the photoreceivers defined in the unit 6. <IMAGE> |
