OLED Pixel Driving Circuit Threshold Voltage Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In OLED display panels, the driving transistors exhibit unevenness and instability in threshold voltage due to production difficulties, leading to unpredictable current output and uneven brightness over time, degrading display quality.
Innovation Solution
A pixel driving circuit with a voltage holding sub-circuit, data writing sub-circuit, conversion sub-circuit, and switch sub-circuit is implemented to maintain voltage and provide illumination power supply, independent of the threshold voltage of the driving transistor, ensuring consistent current output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional driving transistors are used in OLED display panels, then the display can be manufactured with standard processes, but the threshold voltage of driving transistors varies unevenly and unstably across different sub-pixels and over time
Solution Approach 1:
The patent introduces an intermediary compensation circuit that includes a capacitor connected between the source and gate of the driving transistor. This capacitor acts as a mediator to store and compensate for threshold voltage variations, allowing the main driving transistor to operate with standard manufacturing processes while achieving uniform threshold voltage across different sub-pixels through the compensation mechanism.
Solution Approach 2:
The patent changes the electrical parameters of the driving transistor by introducing a compensation capacitor that modifies the voltage relationship between the source and gate. This parameter change enables the system to compensate for threshold voltage variations without changing the physical structure of the transistor itself, thus maintaining ease of manufacture while improving threshold voltage uniformity.
2Device complexity
If conventional driving transistors are used without compensation, then the circuit structure remains simple, but the current output becomes unpredictable and unstable over time
Solution Approach 1:
The compensation capacitor serves as an intermediary element that stabilizes the current output by storing voltage variations caused by threshold voltage changes. This adds minimal complexity to the circuit while significantly improving current output stability and reliability over time.
Solution Approach 2:
The capacitor is pre-connected between the source and gate to cushion against future threshold voltage variations. This beforehand cushioning mechanism ensures that even if threshold voltage changes occur over time, the current output remains stable because the capacitor has already been positioned to compensate for such variations.
3Manufacturing precision
If threshold voltage compensation is implemented, then the uniformity and reliability of display brightness improve, but the circuit structure becomes more complex
Solution Approach 1:
The compensation capacitor is a simple intermediary component that achieves brightness uniformity through a straightforward voltage compensation mechanism. By connecting the capacitor between the source and gate, the circuit achieves uniform brightness across different sub-pixels without requiring complex control systems or multiple active components.
Solution Approach 2:
The patent achieves improved brightness uniformity by changing the electrical parameter relationship in the driving transistor through the compensation capacitor. This parameter change approach allows for uniform brightness without requiring complex circuit restructuring, as the compensation is achieved through voltage modification rather than structural complexity.
Data Source
AI summary
The present disclosure provides a pixel driving circuit, a driving method thereof, and a display device. In one example, the pixel driving circuit includes: a driving transistor; a voltage holding sub-circuit, the first end of the voltage holding sub-circuit connected to the gate of the driving transistor; a data writing sub-circuit configured to supply a data voltage to the driving transistor when the first scanning line is at a first level, and connect the gate of the driving transistor and a second electrode; a converting sub-circuit configured to supply illumination power voltage to a second end of the voltage holding sub-circuit when the second scanning line is at the first level, and connect the second end of the voltage holding sub-circuit to the second end of the driving transistor when the third scanning line is at the first level; and a switch sub-circuit configured to supply illumination power voltage to the first end of the driving transistor when the third scanning line is at the first level, and connect the second end of the drive transistor to the current output end of the pixel drive circuit. The present disclosure can achieve threshold voltage compensation for the drive transistor.