Variable contrast, wide viewing angle liquid crystal light attenuation filter
US8026998B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 9, 2006 |
| Grant date | Sep 27, 2011 |
| Priority date | — |
| Expiry date | Jul 20, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/13471
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A new concept of the LCD light-switching optical filter allowing for very high, electrically controlled, continuously variable light attenuation (up to ≧100.000) optimized/symmetrized for the light incidence along the normal to the LCD plane is proposed. The new LCD light-switching optical filter also exhibits very low light attenuation dependence for the oblique incidence of light within a limited cone of angles off the normal incidence direction in compliance with the international safety and quality regulation EN 379 for personal protection equipment.According to the invention the problem is solved by specific, novel modification of the general principle of highly twisted nematic LCDs, allowing for the adaptation of the light transmission/driving voltage characteristics to specific requirements of the driving electronics as well as “symmetrizing” the overall optical birefringent properties, which in turn results in a high degree of their angular compensation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.