Pixel Circuit Compensation for Display Flicker at Variable Refresh Rates
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Solution Overview
Problem
Display panels exhibit flicker due to the hysteresis effect in driving transistors, causing residual images and increased perceptibility of screen flicker, especially at lower frame rates.
Innovation Solution
A pixel circuit design incorporating a driving sub-circuit, compensation sub-circuit, reset sub-circuit, and storage sub-circuit, along with a leakage prevention sub-circuit, to stabilize node voltages and mitigate hysteresis effects, including storage capacitors to maintain stable potentials and transistors to control circuit branches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional pixel circuit with driving transistor is used, then the display can operate at variable refresh rates, but hysteresis effect causes flicker and residual images
Solution Approach 1:
The pixel circuit is divided into multiple functional sub-circuits: driving sub-circuit, compensation sub-circuit, reset sub-circuit, and storage sub-circuit. Each sub-circuit performs a specific function to collectively solve the hysteresis problem while maintaining variable refresh rate capability
Solution Approach 2:
The compensation sub-circuit uses feedback mechanisms to detect and correct voltage deviations caused by hysteresis effect. By continuously monitoring and adjusting the gate voltage of the driving transistor, the circuit compensates for residual charges and stabilizes the display output at variable refresh rates
2Reliability
If storage capacitors are added to stabilize node voltages, then hysteresis effect is mitigated, but circuit complexity increases
Solution Approach 1:
The storage capacitors are integrated with existing circuit nodes and transistors. The first storage capacitor is formed between the gate of the driving transistor and the source electrode, and the second storage capacitor is formed between the gate and drain electrode, merging storage function with the driving transistor structure to minimize additional complexity
Solution Approach 2:
The gate electrode of the driving transistor serves multiple functions: it controls the driving current, stores voltage to compensate for hysteresis, and acts as one electrode of the storage capacitors. This multi-functionality reduces the need for separate dedicated storage components
Data Source
AI summary
A pixel circuit includes a driving sub-circuit, a compensation sub-circuit, a reset sub-circuit and a storage sub-circuit. The driving sub-circuit is configured to control a circuit brand between a second node and a third node to be closed and opened under control of a voltage of a first node. The compensation sub-circuit is configured to control a circuit branch between the first node and the third node to be closed and opened in response to a first scanning signal received at a first scanning signal terminal. The reset sub-circuit is configured to transmit a first initialization signal received at a first initialization signal terminal to the first node in response to a reset signal received at a reset signal terminal. The storage sub-circuit is configured to store voltages of the first node and the second node.