| 摘要 |
Retroreflective glass or plastic beads (10, 160, 215, 220, 315, 320) have fluorescent properties when irradiated with light and are emplaced in signs (300, 350) in patterns (305, 310) indicative of alphanumeric characters, or embedded in a hot melt comprising road stripes (150, 225, 230) or embedded in the road asphalt (155) or aggregate (210) during construction of the road, to provide effectively bright and clear indications of signs or the extent and direction of the road. The glass beads comprise spherodized soda lime, borosilicate, phosphosilicate or aluminosilicate glasses with low levels of rare-earth dopants mixed therein, such as compounds containing one of the rare earths, or lanthanides. The plastic beads may have fluorescent materials mixed therein, typically organic pigments or dyes based on coumarin and rhodamine or the like. |
