Surface light source device, liquid crystal display and asymmetric prism sheet
US5914759A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1997 |
| Grant date | Jun 22, 1999 |
| Priority date | — |
| Expiry date | Sep 30, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/0046
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A fluorescent lamp L is arranged in the vicinity of an incidence surface 2 of a light scattering guide plate 1. A prism sheet 4' having rows of prism elements and rows of lens elements on each side is arranged outside an exiting surface 5. The angles of inclination of slopes 4a and 4b satisfy a condition that .phi.a>.phi.b. The slopes 4a and 4b extend in the transverse direction of the light scattering guide plate 1, and slopes 4c and 4d extend in the longitudinal direction. A reflector 3 is arranged along a rear surface 6. Light emitted from the exiting surface 5 is efficiently propagated by an inner prism surface toward a forward direction, shifted in the transverse direction by an outer prism surface or the lens element surfaces 4c and 4d, and is then returned inwardly. The path histories of light emitted from the prism sheet 4' is diversified to improve visual characteristics. The peak level of brightness as viewed in the forward direction is improved and brightness is smoothly reduced according to deviation from the peak direction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.