OLED Pixel Circuit Threshold Compensation for Brightness Uniformity
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Solution Overview
Problem
The threshold voltage drift of the driving transistor in OLED display panels affects the light emitting brightness, leading to uneven brightness during the light emitting process, which adversely impacts the display effect.
Innovation Solution
A pixel circuit comprising a data writing circuit, a light emitting control circuit, a threshold compensation circuit, a first storage circuit, a second storage circuit, and a driving circuit, where the driving current is independent of the threshold voltage, achieved through specific signal input stages and capacitor coupling, ensuring stable brightness and reducing IR Drop effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the driving transistor is used to control light emitting brightness, then the display device can achieve different brightness levels, but threshold voltage drift causes uneven brightness and affects display quality
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation before the light emitting operation. The compensation circuit pre-adjusts the gate voltage of the driving transistor to offset the threshold voltage drift, ensuring that the transistor operates at the correct voltage level throughout the light emitting process, thereby maintaining brightness uniformity across all pixels
Solution Approach 2:
The patent implements feedback through the compensation circuit that monitors and corrects the threshold voltage drift of the driving transistor. The circuit uses the stored voltage information to continuously adjust and compensate for threshold variations, creating a closed-loop control system that maintains stable brightness output despite transistor parameter variations
2Reliability
If more TFTs and signal lines are added to the pixel circuit to improve brightness stability, then threshold voltage compensation can be achieved, but the aperture ratio decreases and device complexity increases
Solution Approach 1:
The patent merges multiple functions into the existing pixel circuit structure. The compensation circuit shares signal lines and transistor components with the driving circuit, combining threshold compensation, data writing, and light emitting control functions into a unified circuit architecture. This integration approach achieves brightness stability without proportionally increasing the total component count or aperture ratio
Solution Approach 2:
The patent applies multi-functionality by designing circuit components that serve multiple purposes. The same signal lines are used for both data writing and threshold compensation operations, and the compensation circuit utilizes existing transistor structures to perform dual functions of voltage storage and threshold correction, thereby improving brightness stability without significantly increasing device complexity
Data Source
AI summary
The present disclosure relates to a pixel circuit and a method of driving the pixel circuit, and a display device. A pixel circuit, including: a light emitting device; a driving circuit; a data writing circuit; a light emitting control circuit; a threshold compensation circuit; a first storage circuit; and a second storage circuit.