Pixel Circuit Reset Transistor for Low-Frequency Display Hysteresis
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Solution Overview
Problem
Display devices driven at low frequencies face inefficiencies in driving and increased power consumption due to hysteresis deviations and motion blur caused by gray scale differences between pixel circuits, leading to flicker and image blur.
Innovation Solution
A pixel circuit design that includes a second transistor which is cutoff during the display scan period and turned on during the self scan period to apply a reset voltage, using a time voltage signal to reset the first transistor, thereby compensating for hysteresis deviations and minimizing power consumption without requiring additional high-frequency driving signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the display device is driven at low frequency to improve driving efficiency and minimize power consumption, then power consumption is reduced, but hysteresis deviations and motion blur increase causing flicker and image blur
Solution Approach 1:
The patent applies preliminary action by introducing a reset transistor that actively resets the storage capacitor before the data writing period. This preliminary reset action eliminates hysteresis deviations and ensures consistent pixel circuit states at low driving frequencies, preventing flicker and image blur while maintaining low power consumption operation
Solution Approach 2:
The patent implements feedback by using the reset transistor to monitor and correct the voltage level on the storage capacitor. The reset mechanism provides feedback control to ensure the capacitor is properly initialized, compensating for any voltage drift or hysteresis effects that occur during low-frequency driving cycles
2Reliability
If additional high-frequency driving signals are used to compensate for hysteresis deviations, then image quality is improved, but driving efficiency decreases and power consumption increases
Solution Approach 1:
The patent extracts the hysteresis compensation function from the main data writing process and separates it into a dedicated reset operation. By taking out the compensation function and implementing it through the reset transistor, the system can maintain image quality without requiring additional high-frequency driving signals, thus preserving driving efficiency
3Stability of the object's composition
If the first transistor is continuously turned on to maintain driving current, then light emission is stable, but power consumption increases
Solution Approach 1:
The patent applies periodic action by using the reset transistor to periodically reset the storage capacitor at specific intervals during the frame period. This periodic resetting maintains the stability of light emission by preventing voltage drift and hysteresis effects, while allowing the first transistor to remain off during most of the frame period, thus reducing power consumption
Data Source
AI summary
A pixel circuit, a display device, and a method of driving the same are provided. The pixel circuit includes a light emitting element, a first transistor, and a second transistor. In response to a time voltage signal provided by a time voltage line RST, the second transistor T2 is turned off during a display scan period of one frame period and is turned on during a self scan period of one frame period to reset the first transistor T1 during the self scan period of one frame period.