Color shifting retroreflective articles can provide features such as decorative effects, evidence of tampering, security authentication or positional information. In some embodiments, the color shifting retroreflective article includes a layer of microspheres, and a reflective coating that is disposed...http://www.google.fr/patents/US7140741?utm_source=gb-gplus-shareBrevet US7140741 - Color shifting retroreflector and method of making same
Color shifting retroreflector and method of making same
