| 摘要 |
PROBLEM TO BE SOLVED: To set a light beam at an acute angle against a road face to increase the visibility from a far distance, by covering the upper face of an emitting device provided in a recess on the road face with a transparent plate to be flush with the ground face and using a lens lessening the diffusion of the luminous flux and preventing the radiating angle from getting wide. SOLUTION: A reflective film 7 is spread at the underface 5b of a tapered transparent plate 5 to reflect a part of incident beram from a light source 4 into the transparent plate 5 through the lens 6, at the upper face 5a of the transparent plate 5. In this case, the incident angle is made smaller than the angle before the reflection by the reflective film 7 of the underface 5b to radiate it to the outside. The transpatent plate 5 covering the upper part of the container case 3 for the light source 4 is put to be nearly flush with the road face G and prevent the diffusion of the luminous flux from the light source 4 by means of the lens 6 formed at the underface 5b of the transparent plate 5. And further, the beam is refracted at the upper face 5a to radiate it outward and the radiation angle of the luminous flux radiating from the upper face 5a is made even and the radiating beam from the transparent plate 5 is put in order to an acute angle against the road face G viewed from a far distance. In this way, the intensity of radiation of an acute angle required as rivets 1 for roads can be sufficiently secured. |
