High efficiency retroreflective material
US4895428A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 26, 1988 |
| Grant date | Jan 23, 1990 |
| Priority date | — |
| Expiry date | Jul 26, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24521
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The present invention provides a retroreflective material which has improved retroreflectivity at high angles of incidence. The retroreflective material comprises a transparent surface layer and an array of reflecting elements, each of the reflecting elements including a rectangular base having a length L, two tetragonal faces nearly perpendicular to each other and having a line of intersection of length Y, the length Y being less than said length L, a triangular face nearly perpendicular to the tetragonal faces; and a non-perpendicular triangular face forming an angle alpha with the plane perpendicular to the base, the angle alpha being preferably about sin.sup.-1 (0.25/n) to sin.sup.-1 (l/n), and more preferably about sin.sup.-1 (0.35/n) to sin.sup.-1 (0.9/n), where n is the refractive index of the reflecting elements, the perpendicular triangular face and the tetragonal face defining an approximate cube corner therebetween and the non-perpendicular triangular face and the tetragonal faces forming a non-orthogonal corner therebetween, the reflecting elements arranged with their base adjacent the surface layer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.