| 摘要 |
There have been developed for railway and road traffic inter alia fibre-optic light signals in which the respectively visible signal image consists of a multiplicity of optical fibre bundles illuminated from the rear. Illumination of the signal-adjacent observation region outside a prescribed light beam region is mostly abandoned, because the number of optical fibres available overall is restricted, and this restricted number of optical fibres is required for the long-distance projection of the symbol. It is true that the use of diffusing screens provides illumination of the signal-adjacent observation space; however, it also leads to a limitation of the long-distance recognisability of the signal. The invention proposes that the optical fibres available overall for a light signal be combined on the output side to form bundles of different optical fibre density, and that the latter be distributed over the focal surface of the imaging lens (4) in such a way that the bundles of high optical fibre density serve for the long-distance projection and those of lower optical fibre density serve for the formation of scattered light in the near zone of the light signal. <IMAGE> |
