The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 05, 1999
Filed:
Dec. 12, 1997
Yutaka Mori, Shizuoka pref., JP;
3M Innovative Properties Company, St. Paul, MN (US);
Abstract
A retroreflective sheet capable of exhibiting an excellent decorative effect during both daytime and nighttime, and particularly an excellent rainbow-colored decorative effect. The sheet comprises, in order, a binder in the back side of which a plurality of microspheres, arranged in a monolayer, are partially embedded, a focusing layer underlying some of the microspheres, and a reflective layer underlying the focusing layer and underlying microspheres which do not have a focusing layer therebehind. The focusing layer has a film thickness selection coefficient x in the range of 0.16 to 0.95 as defined by equation (II) of the following equations (I) and (II): ##EQU1## wherein f is the coefficient for the optimum layer thickness of the layer, d is the diameter of the microspheres, h is the thickness of the focusing layer, n.sub.b is the refractive index of the binder layer, n.sub.g is the refractive index of the microspheres, and n.sub.s is the refractive index of the focusing layer.