RETROREFLECTIVE ARTICLES AND RETROREFLECTIVE ELEMENTS COMPRISING A SPHERICAL CORE AND TWO CONCENTRIC OPTICAL INTERFERENCE LAYERS

摘要

Retroreflective elements and articles that include such elements. The retroreflective elements (100) include a solid spherical core (110) having an outer surface. A first complete concentric optical interference layer (112) overlays the outer surface of the core providing a first interface between the core and the first optical interference layer, and a second complete concentric optical interference layer (122) overlays the first optical interference layer to provide a second interface between the first optical interference layer and the second optical interference layer. In some embodiments, a third complete concentric optical interference layer overlays the second optical interference layer to provide a third interface between the second optical interference layer and the third optical interference layer. The retroreflective articles include a substrate having a first major surface and a second major surface with a plurality of the retroref lective elements affixed along the first major surface of the substrate.