OLED Pixel Circuit Scanning to Reduce Transistor Hysteresis Flicker
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Solution Overview
Problem
OLED display panels suffer from screen flickering due to the hysteresis effect in the driving transistor's channel, which reduces display quality, particularly when switching between high and low frequency displays.
Innovation Solution
The display panel incorporates multiple shift registers and sub-circuits, including bias, data writing, compensation, leakage prevention, reset, and light-emission control sub-circuits, to manage scanning signals and voltages, mitigating the hysteresis effect in the driving transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single shift register is used to control pixel circuits, then the device structure is simple, but screen flickering occurs due to hysteresis effect in the driving transistor
Solution Approach 1:
The patent divides the single shift register into multiple shift registers (first, second, third, and fourth shift registers), each responsible for different scanning signal functions. This segmentation allows independent control of bias, data writing, compensation, and light emission phases, eliminating the hysteresis effect that causes screen flickering while maintaining manageable system complexity through functional specialization.
2Reliability
If multiple shift registers are used to control pixel circuits, then screen flickering is reduced, but the device complexity increases
Solution Approach 1:
Each shift register is designed with multi-functional capabilities to control multiple pixel circuits simultaneously. The first shift register controls both bias and reset operations, while the second shift register handles both data writing and compensation. This universality reduces the total number of shift registers needed, thereby limiting the increase in device complexity while achieving reliable flicker-free display.
3Speed
If the driving transistor operates at high frequency, then the response speed is fast, but hysteresis effect intensifies causing screen flickering
Solution Approach 1:
The patent implements periodic action by separating the driving transistor operation into distinct phases controlled by different shift registers: bias phase (first shift register), data writing phase (second shift register), compensation phase (second shift register), and light emission phase (fourth shift register). This periodic segmentation allows the transistor to operate at high frequency within each phase while maintaining overall display stability by preventing hysteresis accumulation across phase transitions.
Data Source
AI summary
A display panel includes pixel circuits, first shift register(s), second shift register(s), third shift register(s), and fourth shift register(s). A pixel circuit includes a driving transistor, a bias sub-circuit, a data writing sub-circuit, a compensation sub-circuit, a leakage prevention sub-circuit, a reset sub-circuit, and a light-emission control sub-circuit. The bias sub-circuit is electrically connected to a first shift register, which transmits a first scanning signal to the bias sub-circuit. The data writing and compensation sub-circuits are electrically connected to a second shift register, which transmits a second scanning signal to the data writing and compensation sub-circuits. The leakage prevention sub-circuit is electrically connected to a third shift register, which transmits a third scanning signal to the leakage prevention sub-circuit. The light-emission control sub-circuit is electrically connected to a fourth shift register, which transmits a fourth scanning signal to the light-emission control sub-circuit.