TFT pixel threshold voltage compensation circuit using a variable capacitor
US11069292B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 2020 |
| Grant date | Jul 20, 2021 |
| Priority date | — |
| Expiry date | Apr 23, 2040 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2320/045
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A pixel circuit for driving a light-emitting device for a display device is operable in an initialization phase, a compensation phase, a data programming phase, and an emission phase. The one horizontal time is minimized while maintaining accurate compensation of the threshold voltage of the drive transistor, and the pixel circuit further employs a varactor to compensate for variations in the threshold voltage of the drive transistor and for parasitic capacitances that arise within the pixel circuit. A capacitance of the varactor varies with a voltage at a node N1 constituting an electrical connection during the compensation phase of the drive transistor, the light-emitting device, a storage capacitor, and the varactor. The use of the capacitance variation of the varactor accounts for a variation in the threshold voltage of the drive transistor and for parasitic capacitances in the pixel circuit. The varactor may be implemented as a thin film transistor that operates as a variable capacitor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.