N-Type Oxide TFT Pixel Circuit for OLED Flicker Reduction
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Solution Overview
Problem
OLED display panels experience screen flicker due to the hysteresis effect of driving transistors made with low-temperature polysilicon semiconductors, leading to display errors and reduced image quality.
Innovation Solution
The pixel circuit incorporates N-type oxide thin film transistors in the driving circuit, data writing circuit, and reset circuits to initialize and reset the transistors, reducing hysteresis and maintaining voltage stability, thereby alleviating flicker and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-temperature polysilicon semiconductors are used in driving transistors, then the OLED display panel can be manufactured with simpler processes and lower costs, but screen flicker occurs due to hysteresis effect leading to display errors and reduced image quality
Solution Approach 1:
The patent changes the material parameter of the transistor from low-temperature polysilicon semiconductor to oxide semiconductor, which fundamentally alters the electrical characteristics including threshold voltage stability and hysteresis behavior, thereby eliminating flicker while maintaining manufacturing feasibility
Solution Approach 2:
The patent employs a composite transistor structure combining oxide semiconductor channel layer with other functional layers (gate electrode, source/drain electrodes, insulating layers) to create a transistor with superior electrical stability that resolves the hysteresis issue while integrating into the existing OLED manufacturing process
2Stability of the object's composition
If N-type oxide thin film transistors are used in the pixel circuit, then voltage stability is improved and hysteresis is reduced, but the device complexity increases due to additional reset circuits and initialization voltages
Solution Approach 1:
The patent extracts the hysteresis effect from the system by removing the problematic low-temperature polysilicon material and replacing it with oxide semiconductor, which inherently lacks the hysteresis behavior, thereby simplifying the overall system behavior despite adding reset functionality
Solution Approach 2:
The patent applies preliminary initialization voltages through reset circuits before the main driving operation to pre-establish stable voltage conditions in the oxide semiconductor transistor, preventing hysteresis-related issues before they occur and ensuring consistent display performance
Data Source
AI summary
A pixel circuit and a display panel. The pixel circuit includes a driving circuit, a data write circuit, a storage circuit, and a first reset circuit; the driving circuit includes a control end, a first end, and a second end, and is configured to control a driving current flowing through the first end and the second end for driving a light-emitting element to emit light; the first reset circuit is configured to apply a first initialization voltage to the control end of the driving circuit under the control of a first reset control signal; and the first reset circuit includes an N-type oxide thin film transistor; where the pixel circuit further includes a third reset circuit configured to apply a holding voltage to the first terminal of the driving circuit under a control of a third reset control signal.