Multiplexed liquid crystal display having a gray scale image
US4427978A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 31, 1981 |
| Grant date | Jan 24, 1984 |
| Priority date | — |
| Expiry date | Aug 31, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2310/0289
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A field effect liquid crystal display is disclosed wherein an composite alternating voltage is successively produced across a matrix of pixels formed by crossed arrays of row and column electrodes of the display. The composite alternating voltage consists of a row driving alternating voltage component and a column driving alternating component voltage. The phases of the row and column alternating voltage components are relatively phased so as to produce the composite alternating voltage across the individual pixels. The column alternating voltage component includes a gray scale component having an (root mean square) RMS value variable in accordance with the gray scale of the image to be displayed on the liquid crystal display. Two systems are disclosed for deriving the composite RMS voltage having the gray scale component. In an analog system, an alternating square wave video signal is compared with a triangular wave to convert the gray scale video signal into a phase modulated square wave which is then fed to the column electrodes for summing with the row alternating voltage signals to derive a composite alternating voltage for energizing the respective pixels. In a second embodim…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.