Abstract
The pixel circuit of an active matrix organic light-emitting diode (AMOLED) is composed of a capacitor and thin-film transistors (TFTs). As a result of differentfabrication processes, components characteristics such as TFT threshold voltage shift and OLED degradation will vary, indicating that an increase in OLED threshold voltage leads to non-uniformity luminance in panels. Additionally, aperture ratio also influences emitting
efficiency. Therefore, this study adopts a top emission structure to improve the aperture ratio and maintain uniform brightness.
This work proposes three novel pixel circuits to overcome problems associated with threshold voltage shift and OLED degradation. The first pixel circuit with 4T1C compensates for TFT threshold voltage variations and OLED degradation; however this circuit has complex control signal lines. The second circuit, composed of 4T1C, simplifies the control signals and effectively maintains uniform brightness. The third circuit with few elements in the pixel circuit reduces fabrication cost and compensates for material
variations via an external driving circuit. The proposed circuits improve brightness non-uniformity and enhance emitting efficiency. These circuits will contribute to
AMOLED applications in the future.
| Date of Award | 2008 |
|---|---|
| Original language | Chinese (Traditional) |
| Supervisor | Chih-Lung Lin (Supervisor) |