Apparatus having a DAC-controlled ramp generator for applying voltages to individual pixels in a color electro-optic display device
US6462728B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 1999 |
| Grant date | Oct 8, 2002 |
| Priority date | — |
| Expiry date | Dec 21, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2310/027
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an electro-optic display device, such as a liquid crystal display device which serves as a modulator for projected light, a global DAC controlled ramp generator is used in conjunction with track and hold circuit for each column of the display to convert incoming digital display signals to analog signals for all columns. Row address circuitry addresses each row of the display, thereby to address the individual pixels of the display device with such analog signals. The limitation on an increase in frame rate, resulting from the finite conversion time (cycle time) of the DAC, is overcome by reducing the grey scale resolution, thus reducing the number of times that the DAC must convert a digital number to an analog voltage during each ramp cycle, and restoring the original resolution using temporal “dithering”—i.e., interpolation between the brightness levels of pixels in successive frames.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.