Diffusively reflecting shield optically, coupled to backlit lightguide, containing LED's completely surrounded by the shield
US5883684A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1997 |
| Grant date | Mar 16, 1999 |
| Priority date | — |
| Expiry date | Jun 19, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/0073
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An LCD backlight (30) comprises generally rectangular parallelepiped light guide (36) with an exit aperture (31) that is smaller than the surface area light guide (36) and illuminates a LCD (49). The light guide is illuminated by a plurality of Light Emitting Diodes (LED) dies (32) disposed along at least one edge of the light guide. A translucent fluorescent film (40) is disposed immediately above the exit aperture to diffuse the light exiting the exit aperture and also the change in the dominant wavelengths. Further, the light guide (36), the LEDs (32), fluorescent film (40), and additional light redirecting layers (42 and 44) are completely surrounded by and optically coupled to a diffusively reflective film (50), which covers the back surface, the edges, and the front surface of the light guide except for the exit aperture. This diffusively reflective shielding is covered by a conventional reflective material layer (51) to ensure no light escapes the backlight except through the exit aperture.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.