Efficient backlighting for a portable display
US6217185A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 1999 |
| Grant date | Apr 17, 2001 |
| Priority date | — |
| Expiry date | Mar 8, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/0046
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Efficiency in light transfer between a light source and a viewing screen is attained in the invention by positioning a small diameter source of light at a position of highest light transfer intensity within an essentially semicircular reflector interfacing at the wide portion of a wedge shaped light pipe light transfer member and minimizing reflection losses at every optical interface in the light path between the light source and the viewer. A wedge shaped light pipe light transfer member of the invention has attached a light source with unit diameter light bulb positioned off center of a four unit diameter semicircular solid reflector of a transparent material that is closely index of refraction matched with index of refraction of a wedge shaped light pipe light transfer member on the upper face of which is positioned the addressable viewing screen and, the portion of the wedge shape light pipe light transfer member being terminated in a reflection preventing face that is at about 45 degrees from the centerline of the wedge shaped member.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.