Fed display row driver with chip-to-chip settling time matching and phase detection circuits used to prevent uneven or nonuniform brightness in display
US6040809A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 30, 1998 |
| Grant date | Mar 21, 2000 |
| Priority date | — |
| Expiry date | Jan 30, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2320/02
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A device for and method of eliminating objectionable bands of uneven brightness in flat panel field emission displays (FEDs). Within the FED screen, a matrix of rows and columns is provided and emitters are situated within each row-column intersection. Rows are activated sequentially by row drivers and discrepancies in row driver settling times among the row drivers cause bands of uneven brightness on the display screen. The present invention normalizes row settling time of row driver integrated circuits that can be variant due to differences in semiconductor processing and manufacturing. The present invention includes specialized circuitry coupled to the row drivers for sensing an output of the row driver and determining a difference between the output and a threshold at a particular time before the output has completely settled to a target voltage. In response to the difference, gate voltages of output transistors within the row driver are altered in order to adjust the settling time of the row driver to match a target settling time. As a result, the settling times of all the row drivers in the FED screen are matched. Consequently, the brightness variation problem is eliminated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.