Thin film compensators having planar alignment of polymerized liquid crystals at the air interface
US5995184A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 1998 |
| Grant date | Nov 30, 1999 |
| Priority date | — |
| Expiry date | Sep 28, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P20/582
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention relates to thin film retardation plates, such as cholesteric and A-plate compensators, for improving the viewing angle and contrast of liquid crystal displays. The A-plate is fabricated using a single substrate onto which a layer of polymerizable reactive mesogens (RMs) is solvent cast. Included in the RMs solution is an additive that migrates to the RM/air interface to lower the surface energy and generate an additive-rich surface layer, which in turn lowers the intrinsic tilt angle of the RMs at the air interface to between 25 degrees (25.degree.) and about zero degrees (0.degree.). The solvent is evaporated and the resulting film is polymerized in the liquid crystal phase to permanently orient the liquid crystal. The resulting film may be readily separated from the substrate and shaped into any desired pattern and combined to form novel compensators. In an alternative embodiment, a tilt may be provided by treating the substrate with an oblique alignment layer to form a compensator having a defined splay through the bulk of the thin film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.