Unipolar waveform drive method and apparatus for a bistable liquid crystal display
US6268840A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 21, 1998 |
| Grant date | Jul 31, 2001 |
| Priority date | — |
| Expiry date | Apr 21, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2310/06
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A flat-panel liquid crystal display having unipolar drive circuitry. The display includes a flat sheet of bistable chiral nematic liquid crystal material activated by a drive circuit that individually controls the display state of multiple picture elements at a refresh rate 1000 scan lines per second. The driver circuitry activates the liquid crystal domains into homeotropic states over a relatively long activation period and then, during a short (.about.1 msec.) selection period, either keeps the domains in a homeotropic state or initiate a transition to the transient twisted planar state. The drivers then activate the domains in an evolution phase to provide either focal conic or twisted planar end states across the two-dimensional array of picture elements. The drive circuitry includes a plurality of unipolar display drivers which generate substantially square wave, unipolar waveforms which are applied to row and column electro segments. The frequency and timing of the unipolar waveforms is controlled by the display driver circuitry to generate desired bi-polar voltages across picture elements or pixels of the display. A pipelining scheme wherein a number of pixel rows are addre…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.