| 摘要 |
A light retroreflective system comprises a primary focusing transparent body having an exposed surface adapted to project externally of the surface of a sign forming material and operative for refracting and focusing light beams impinging on portions of said exposed surface, and a reflecting arrangement adjacent to areas below said sign surface and where said beams are focused. The exposed surface has, in its cross-sections in planes perpendicular to said sign surface, portions adjacent to the sign surface having radii or curvature smaller than half of the distance between the portions and the locations below the sign surface wherein the refracted beams focus, so that a proper focalization is ensured within said primary body, the primary body consisting of a transparent material the index of refraction of which is considerably lower than 1.9. |
