Retroreflectors having two optical surfaces and varying retroreflectivity

Abstract

Retroreflective articles provide varying retroreflection using a first surface that includes a plurality of light redirecting structures and a second surface that includes retroreflective areas and separation areas. The light redirecting structures on the first surface are preferably arranged relative to the retroreflective areas and the separation areas on the second surface such that a substantial portion of light incident on the light redirecting structures is superimposed on areas of the second surface. At some angles, it is preferred that substantially all of the light is superimposed on either the retroreflective areas or the separation areas, resulting in varying retroreflection from the retroreflective articles. Together, the two optical surfaces of the retroreflective articles provide varying retroreflection of incident light where the variations can be between, e.g., retroreflection or no retroreflection, retroreflection of different colors, retroreflection at different brightness levels, etc. In other words, when subjected to incident light from a steady light source, relative movement between the retroreflective article and the light source will result in variations in retroreflection. When retroreflective articles provide varying retroreflection, the variations or changes will tend to increase the conspicuity of an object or person on which the retroreflective article is located.