| 摘要 |
Indication of whether separation from a vehicle 17 ahead is safe or otherwise is given to the driver of a following vehicle 10 by transmitting two light beams 14 forwardly from that vehicle 10 onto an elongate retro-reflector 1 mounted across the back of the vehicle 17 ahead. The reflector 1 has a central, red zone 2, two amber zones 3 flanking the red zone 1 and two outer, green zones 4, and the angular directions of the transmitted beams 14 are varied by a unit 15 according to the speed of the following vehicle 10 so that their points of incidence on the reflector 1, and therefore the colours reflected, are dependent upon both the speed of the following vehicle 10 and its separation from the vehicle 17 ahead. The beam angle may be varied in accordance with steering of the following vehicle 10. The light transmitted may be infra-red instead of visible, in which case the reflector may be replaced by a detector actuating a transmitter of visible or infra-red light (if infra-red, the following vehicle 10 has a detector actuating an indicator and/or alarm). <IMAGE> |
