Lighting device for a free viewing mode and a restricted viewing mode
US12287506B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 2022 |
| Grant date | Apr 29, 2025 |
| Priority date | — |
| Expiry date | Mar 29, 2042 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/133626
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An illumination device for a display screen operable in an open-viewing mode B1 and a restricted-viewing mode B2 where light is emitted in a limited angular range. It includes a backlight emitting the limited-angular-range light, a plate-shaped light guide with large surfaces and narrow connecting sides in front of the backlight in a viewing direction. The light guide has outcoupling elements on the surfaces or within its volume, and is at least 50% transparent to backlight light. Outcoupling elements have a function surface for coupling out light guide light. Illuminants are arranged laterally of the narrow sides. The backlight is on and the illuminants off in mode B2, and the illuminants are on in mode B1. Some outcoupling elements have a structure causing scattering in a preferential direction that is stronger by a factor of at least 1.2 than in a direction perpendicular to the preferential direction, yielding anisotropic scattering.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.