Optical sheets suitable for spreading light
US6456437B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 14, 2000 |
| Grant date | Sep 24, 2002 |
| Priority date | — |
| Expiry date | Sep 14, 2020 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF21Y2101/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An optical sheet (25) for spreading light has a substantially smooth surface (27), and a structured surface (28) comprising an array of prisms (30, 31). A beam of light that is to be spread is directed through the film from the smooth surface. Some of the prisms (termed “refraction prisms”) deviate normally-incident light only by refraction at a prism facet as the light leaves the film while others (termed “reflection prisms”) deviates normally-incident light by total internal reflection within the prism before the light leaves the film. There are a plurality of reflection prisms (30) selected to deviate normally-incident light through different angles and a plurality of refraction prisms (31) selected to deviate the normally-incident light through different angles, and they are arranged, preferably in a non-ordered manner, so that successive reflection prisms are separated by at least one refraction prism. In alternative embodiments, the structured surface comprises a non-ordered arrangement of a plurality of reflection prisms selected to deviate normally-incident light through different angles, or a non-ordered arrangement of a plurality of refraction pris…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.