OLED Pixel Circuit Hysteresis Control via Reset Pulse
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Solution Overview
Problem
OLED displays face issues with afterimages due to hysteresis phenomena in driving transistors, which occur because the gate electrode of the driving transistor is under a certain voltage for a long time, causing voltage delays and non-uniform display.
Innovation Solution
A pixel circuit comprising a reset circuit, data writing circuit, driving transistor, and light emitting device, where the reset circuit provides an excitation pulse followed by a preset voltage to the control electrode of the driving transistor, and the data writing circuit provides a data signal under a scanning signal, helping to alleviate hysteresis by resetting the voltage and maintaining a stable voltage difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the driving transistor drives the light emitting device for a long time period, then the light emitting device can maintain continuous illumination, but the gate electrode is under voltage for a long time causing hysteresis phenomenon and afterimage
Solution Approach 1:
The patent applies preliminary action by providing an excitation pulse to the gate electrode before the main driving voltage is applied. This excitation pulse pre-activates the driving transistor and reduces the hysteresis effect that would otherwise occur during prolonged operation, thereby maintaining display uniformity while enabling continuous illumination.
Solution Approach 2:
The patent implements periodic action by periodically refreshing the excitation pulse to the gate electrode during the light emission period. This periodic excitation counteracts the hysteresis phenomenon that accumulates during long-duration operation, preventing afterimage effects while maintaining continuous light output.
2Stability of the object's composition
If a stable voltage is applied to the gate electrode, then the driving transistor operates continuously, but the voltage fails to reach predetermined voltage in time causing afterimage
Solution Approach 1:
The excitation pulse is applied in advance to prepare the gate electrode and driving transistor for the upcoming voltage transition. This preliminary action ensures that when the main driving voltage is applied, the system responds faster and reaches the predetermined voltage level without delay, eliminating afterimage while maintaining voltage stability.
Solution Approach 2:
The patent maintains continuous useful action by overlapping the excitation pulse with the driving voltage application. This ensures that the gate electrode is continuously active and ready to respond, preventing voltage delays while maintaining stable operation throughout the light emission period.
Data Source
AI summary
A pixel circuit, a display panel, a display device and a driving method are provided. The pixel circuit provides an initial signal having an excitation pulse to a control electrode of a driving transistor through a reset circuit in advance; and the initial signal having a preset voltage is provided to the control electrode of the driving transistor after a preset duration.