Flat light source using light-diffusing sheet with projections thereon
US5944405A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 1996 |
| Grant date | Aug 31, 1999 |
| Priority date | — |
| Expiry date | May 30, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/0053
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A flat light source used as back-lighting for a liquid crystal display device includes an optically conductive plate (1) having a light reflecting layer (2), and a light source (3). A light-diffusing sheet (8) is provided outside the optically conductive plate (1) opposite to the light reflecting layer (2). A lens sheet (4) is provided outside the light-diffusing sheet (8), with a transmission type of display element (6) provided on the outer side of the lens sheet (4). The light-diffusing sheet (8) is formed of a transparent material free from light-diffusing agent particles and has minute irregularities (41) formed at random on the front surface thereof. The irregularities are of a surface roughness that is at least the wavelength of the light from the light source, but is no more than 100 .mu.m. When the percentage of the cumulative frequency distribution of the heights of the minute irregularities are plotted along the Y-axis and the heights of these minute irregularities are plotted along the X-axis, the cumulative frequency distribution curve has a convex portion oriented towards the lower side of the coordinates and the average value of the heights of the minute irregulariti…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.