Electro-optic passive display cell
US4277144A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 20, 1979 |
| Grant date | Jul 7, 1981 |
| Priority date | — |
| Expiry date | Mar 20, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/133742
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Electro-optic passive display cell constituted by a layer of a mixture of a nematic liquid crystal having a positive dielectric anisotropy, an optically active compound and dichroic molecules. The inner faces of the plates of the cell are covered with alignment layers such that, in the area situated outside the display zones or segments, the layer of the mixture has a homeotropic structure in its whole thickness. Opposite the segments the cell is arranged in such a way that the layer of the mixture has a helicoidal structure so that incident light is absorbed in these zones when the segments are not activated and that the layer of the mixture is orientated according to a homeotropic structure under the action of an electric field. Thus, when the cell is at rest, all its segments are visible. The display is effected by "cancelling" or "effacing" the segments which must not appear, so that only the non activated segments remaining visible in dark on a clear or transparent background.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.