OLED Pixel Driving Circuit Alternating Transistor Segmentation
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Solution Overview
Problem
The threshold voltage drift of driving transistors in OLED display panels causes afterimage problems when attempting high-brightness displays due to limitations in TFT mobility and OLED luminous efficiency.
Innovation Solution
A pixel driving circuit utilizing two sets of transistors and storage capacitors, where the first and third transistors provide driving currents to the OLED alternately, with both sets activated during high-brightness displays to reduce the duration of high voltage exposure to the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the voltage of the data signal is increased to achieve high-brightness display, then the screen brightness is improved, but the threshold voltage of the driving transistor drifts causing afterimage problems
Solution Approach 1:
The patent divides the driving function into multiple transistors (first driving transistor and second driving transistor) that alternately drive the OLED in different frames. This segmentation allows the original driving transistor to rest periodically, preventing continuous high-voltage exposure and threshold voltage drift, thereby maintaining both high brightness and voltage stability.
Solution Approach 2:
The patent implements periodic switching between two driving transistors on a frame-by-frame basis. By alternating the driving duty between T1 and T2, each transistor experiences periodic rest periods during which it is not subjected to high gate voltages, thus preventing cumulative threshold voltage drift while maintaining high average brightness output.
2Power
If the data signal voltage is increased to improve OLED luminous efficiency, then the current through OLED increases, but the driving transistor threshold voltage drifts due to prolonged high voltage exposure
Solution Approach 1:
The driving function is segmented between two transistors, so that while one transistor is actively driving the OLED at high current, the other is in a low-voltage rest state. This segmentation reduces the duration of high-voltage exposure for each individual transistor, preventing threshold voltage drift while maintaining the required OLED current for high brightness.
Solution Approach 2:
The patent employs periodic alternation between two driving transistors on a frame-by-frame basis. This periodic action ensures that each transistor spends only half the time in high-voltage driving mode, significantly reducing cumulative exposure duration and preventing threshold voltage drift while maintaining adequate OLED current drive capability.
Data Source
AI summary
The present disclosure provides a pixel driving circuit and a pixel driving method. The pixel driving circuit includes a first transistor, a second transistor, a third transistor, a fourth transistor, and an organic light-emitting diode. When a first scan signal is at a high voltage potential, the second transistor transmits a data signal voltage to a gate of the first transistor. A driving current flows through the organic light-emitting diode to emit light.