Surface light source device and asymmetrical prism sheet
US6222689A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Oct 28, 1998 |
| Grant date | Apr 24, 2001 |
| Priority date | — |
| Expiry date | Oct 28, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/0053
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An asymmetric prism sheet, surface light source and LCD to which the asymmetric prism sheet is applied is provided. A cold cathode tube backed by a reflector supplies light to an incidence surface of a directional emission guide plate. A polarization separation sheet and a liquid crystal panel are disposed outside of the asymmetric prism sheet, with the reflector disposed along a back face. First and second slopes of each asymmetric prism element rows have inclination angles .phi.a, .phi.b which are selected as to allow a secondary ray to exist inside a main ray emitted from a frontal face in a manner such that the main ray is deflected toward a generally frontal direction by way of internal reflection of the second slope while the secondary ray is deflected toward a generally frontal direction by way of double internal reflection of the first and second slopes. An outer face provides an uneven face such as non-glare-processed face, orthogonal prismatic face or lens face. Outside of an outer face may be arranged elements such as additional prism sheet or lens sheet.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.