Method for multiplex driving a passive liquid crystal display (LCD) using modulated pulse widths
US6127994A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1997 |
| Grant date | Oct 3, 2000 |
| Priority date | — |
| Expiry date | Apr 30, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G3/2018
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The method of the present invention produces a plurality of bi-level waveforms on the ROW/common lines and COLUMN/segment lines of a passive multiplexed liquid crystal display (LCD). These waveforms drive the LCD display using binary data from display memory locations. At periodic intervals a counter is incremented while the counter value is then used to 1) look-up in a table the bi-level data to output on the ROW/commons; 2) look-up memory locations associated with the active COLUMN/segments; and 3) to provide inverted COLUMN/segments data before sending the bi-level data to the COLUMN/segment lines of the LCD. The counter increments from zero to four times the number of ROW/commons before being reset to zero and the waveforms repeated. Thus, an algorithm produces one ON/select voltage and one OFF/non-select voltage that are provided to the LCD.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.