Ferroelectric liquid crystal electro-optical device having half-select voltage to maximize contrast
US4762400A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 27, 1987 |
| Grant date | Aug 9, 1988 |
| Priority date | — |
| Expiry date | May 27, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G3/3629
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A ferroelectric liquid crystal electro-optical device driven in time-sharing comprising; a ferroelectric liquid crystal layer having bi-stable alignment characteristics, means for converting the bi-stable alignment state to optical ON state or optical OFF state, a matrix electrode and means for driving the liquid crystal layer by applying voltages to the liquid crystal layer through the matrix electrode. A voltage sufficient to change a stable alignment state of the ferro-electric liquid crystal molecular is applied to a selected pixel, a voltage insufficient to change a stable alignment state is applied to a non-selected pixel and an AC voltage for holding a stable alignment state is applied to a half-selected pixel. A bias value, which is the ratio of the amplitude of the voltage applied to the selected pixel to the amplitude of the AC voltage applied to the half-selected pixel, is set near the maximum value of B satisfying the following formula EQU B/(B-2).gtoreq.Vsat/Vth, wherein Vsat is the minimum value of voltage which enables to change a stable alignment state to the other state and Vth is the maximum value of voltage which enables to hold the stable alignment state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.