Dual-Gate Pixel Circuit for TFT Threshold Voltage Stability
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Solution Overview
Problem
Existing display apparatuses face issues with deterioration of display quality due to shifts in the threshold voltage of thin-film transistors, which affect image quality.
Innovation Solution
A pixel circuit design incorporating a driving thin-film transistor with a dual-gate structure, a storage capacitor, and bias and initialization thin-film transistors to stabilize the threshold voltage by applying bias and initialization voltages, thereby reducing image degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thin-film transistor structure is used in the pixel circuit, then the device complexity is low, but the threshold voltage shifts over time causing display quality deterioration
Solution Approach 1:
The gate electrode is segmented into two separate electrodes (first gate electrode and second gate electrode) that can be independently controlled. This segmentation allows the first gate electrode to receive data signals while the second gate electrode receives bias voltages, preventing threshold voltage shifts and improving display quality stability without requiring complex circuitry
Solution Approach 2:
A storage capacitor is introduced to store bias voltages before they are applied to the second gate electrode. This preliminary storage mechanism ensures that the bias voltages are consistently applied to compensate for threshold voltage shifts, maintaining stable display quality over time
2Reliability
If bias voltage is continuously applied to stabilize threshold voltage, then display quality is maintained, but energy consumption increases
Solution Approach 1:
The bias voltage is applied periodically rather than continuously. The storage capacitor stores the bias voltage and releases it at appropriate intervals to compensate for threshold voltage shifts. This periodic application of bias voltage maintains threshold voltage stability while significantly reducing energy consumption compared to continuous application
Data Source
AI summary
A pixel circuit includes: a driving thin-film transistor including a 1a gate electrode, a 1b gate electrode, and a first semiconductor layer between the 1a gate electrode and the 1b gate electrode in a cross-sectional view; a storage capacitor including a first electrode electrically connected to the 1a gate electrode, and a second electrode spaced from the first electrode; a bias thin-film transistor including a 7a source-drain electrode electrically connected to the 1b gate electrode, and a 7b source-drain electrode configured to receive a bias voltage; and a light-emitting diode including an anode electrically connected to the driving thin-film transistor.