Fresnel lens sheet, light-transmission screen, and projection image display apparatus
US7872801B2 · kind B2 · utility
24Cited by
3References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 23, 2008 |
| Grant date | Jan 18, 2011 |
| Priority date | — |
| Expiry date | Apr 25, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/045
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The Fresnel lens sheet according to the present invention has a plurality of prismatic Fresnel lens elements including a Fresnel facet, a riser facet, and a top facet crossing the facet and the riser facet on an entrance surface. An angle of the top facet of each Fresnel lens element constituting the lens relative to the an exit surface, δ1, is determined so that an exit angle of the light that has entered each of the top facets and exits from the exit surface, β, is greater than 35 degrees.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.