Retroreflective sheeting
US4511210A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 16, 1983 |
| Grant date | Apr 16, 1985 |
| Priority date | — |
| Expiry date | Sep 16, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/128
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
New methods for making "embedded-lens" retroreflective sheeting, and new forms of such sheeting, are provided. The new methods involve embedding microspheres into a web by continuously presenting a mass of the microspheres against the moving web and heating the web so as to soften at least an exterior stratum of the web, and adding a spacing layer to the microsphere-covered surface of the web. The microspheres are embedded on the average to less than 50 percent of their diameter, which has been found to cause the spacing layer to conform around a greater proportion of the back surface of individual microspheres and thereby position a greater portion of the specularly reflective layer carried on the spacing layer at the approximate focal point for light passed through the microspheres. Use of a preformed spacing layer also contributes to maintaining the spacing layer at a constant thickness around the back surface of the microspheres.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.