OLED Pixel Circuit Brightness Uniformity via Transistor Mode Control
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Solution Overview
Problem
Existing OLED and AMOLED display panels face issues with non-uniform brightness and ghosting due to complex drive architectures and compensation problems, particularly in large-size displays.
Innovation Solution
A pixel circuit design incorporating a first transistor, a third transistor, a storage capacitor, and a light-emitting element, with additional transistors and a resistor to optimize the drive architecture, ensuring the second transistor and third transistor operate in the active region, maintaining equal voltages and currents, thereby controlling the light-emitting element's brightness uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more thin film transistors are disposed in the pixel unit to drive the light-emitting element, then the brightness uniformity and ghosting issues are improved, but the drive architecture complexity increases
Solution Approach 1:
The patent changes the operating parameters of transistors from conventional modes to specific modes (first transistor in deep linear mode, second transistor in active mode). This parameter change enables the circuit to achieve compensation functionality with fewer transistors, resolving the contradiction between reliability improvement and complexity reduction.
Solution Approach 2:
The patent applies different operating modes to different transistors within the same pixel circuit based on their specific functions. The first transistor operates in deep linear mode while the second operates in active mode, optimizing each component's performance for its specific role in achieving brightness uniformity.
2Reliability
If more thin film transistors are disposed in the pixel unit to drive the light-emitting element, then the ghosting issues are improved, but the drive architecture complexity increases
Solution Approach 1:
By changing the operating parameters of the transistors to specific modes (deep linear mode for first transistor, active mode for second transistor), the patent achieves ghosting prevention through optimized current control rather than simply adding more transistors, thus reducing drive architecture complexity.
Solution Approach 2:
The patent implements a feedback mechanism where the second transistor's gate is connected to the drain of the first transistor, creating a self-regulating circuit that compensates for threshold voltage drift and prevents ghosting effects through automatic adjustment of operating parameters.
3Reliability
If compensation problems are addressed to improve brightness uniformity, then the display quality is improved, but the drive architecture becomes more complex
Solution Approach 1:
The patent achieves compensation for brightness uniformity by changing transistor operating parameters to deep linear mode and active mode, which enables the circuit to automatically compensate for variations without requiring additional compensation circuits or transistors.
Solution Approach 2:
The first transistor serves multiple functions simultaneously: it acts as both a switching element and a compensation element through its operation in deep linear mode. This multi-functionality eliminates the need for separate compensation circuits, reducing overall drive architecture complexity while maintaining brightness uniformity.
Data Source
AI summary
A pixel circuit, a display panel, and a display device are provided in the disclosure. A first transistor of the pixel circuit receives a data signal and a first scan signal, and the first scan signal controls the first transistor to be turned on or turned off. A first terminal of a third transistor receives a second power supply voltage, a second terminal of the third transistor is electrically connected to a first terminal of a light emitting element, and a second terminal of the light emitting element receives a first power supply voltage. A first terminal of a storage capacitor is electrically connected to a second terminal of the first transistor and a control terminal of the third transistor. The pixel circuit further includes a second transistor.