OLED Pixel Driving Circuit Threshold Voltage Drift Compensation
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Solution Overview
Problem
Threshold voltage drift in transistors used in OLED displays leads to unstable current flow, resulting in non-uniform luminance in OLED panels.
Innovation Solution
A pixel driving circuit with a control circuit that outputs a compensation current to counteract threshold voltage drift, combined with a storage unit to store and apply compensation voltage, ensuring stable current flow through the OLED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transistor is used as a driving transistor to control current through the OLED, then the structure remains simple, but threshold voltage drift occurs causing unstable current and non-uniform luminance
Solution Approach 1:
The pixel driving circuit is segmented into multiple functional modules: a driving transistor for current control, a compensation circuit for threshold voltage correction, and a storage unit for voltage retention. This segmentation allows each module to perform its specific function independently, improving current stability while keeping the overall circuit design systematic and manageable
Solution Approach 2:
A compensation circuit is introduced as an intermediary component between the driving transistor and the OLED. This compensation circuit generates a compensation current that counteracts the threshold voltage drift of the driving transistor, thereby stabilizing the current flowing through the OLED without requiring fundamental changes to the driving transistor itself
2Reliability
If threshold voltage compensation is implemented, then current stability improves, but the circuit complexity increases due to additional compensation components
Solution Approach 1:
The compensation function is merged with the existing pixel driving circuit by utilizing the gate terminal of the driving transistor as part of the compensation mechanism. The storage unit is also integrated into the circuit node structure, combining multiple functions (compensation, storage, and driving) into a unified circuit architecture that minimizes additional components
Solution Approach 2:
The driving transistor's own gate terminal is utilized as part of the compensation mechanism. By applying compensation current to the gate terminal, the circuit performs self-correction of threshold voltage drift using the transistor's existing structure, reducing the need for entirely separate compensation components
Data Source
AI summary
A pixel driving circuit is disclosed, including: a driving switch, connected between a driving power source and an OLED; a first switch, connected between the drain of the driving switch and the driving power source for inputting a first control signal; a control circuit, connected between the drain and gate of the driving switch, for inputting a second control signal and outputting a compensation current to compensate threshold voltage drift of the driving switch; a storage unit, connected between the source of a second switch and gate of the first switch, for storing a compensation voltage of compensation current compensating the driving switch. A display panel and pixel driving method are also disclosed.