Inorganic LED Pixel Circuit for Peak Black Gradation Control
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Solution Overview
Problem
Existing display devices using inorganic LEDs face issues with image quality deterioration due to uniform driving methods, leading to increased power consumption and inadequate expression of peak black gradation.
Innovation Solution
A display device design incorporating transistors with oxide-based and low-temperature polysilicon semiconductor layers, utilizing pulse width modulation and constant current generation to control light-emitting elements, reducing transistor and signal line count, and employing a sweep signal with a linear voltage pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If inorganic LEDs are driven using the same method as OLEDs (adjusting driving current magnitude), then brightness control is achieved, but image quality deteriorates due to wavelength variation with driving current
Solution Approach 1:
The patent implements dynamic driving methods where the driving current magnitude is adjusted based on the desired brightness level. For high brightness, higher current is applied; for low brightness, lower current is applied. This dynamic adjustment compensates for the wavelength shift issue by optimizing the current level for each display state, thereby maintaining image quality while achieving brightness control.
Solution Approach 2:
The patent changes the driving current parameter dynamically based on brightness requirements. By selecting different current magnitudes corresponding to different brightness levels, the system maintains stable wavelength emission characteristics. This parameter change approach resolves the contradiction by adapting the driving condition to match the display state.
2Reliability
If conventional display device architecture is used, then basic display function is achieved, but power consumption increases and peak black gradation expression is inadequate
Solution Approach 1:
The patent segments the pixel circuit into distinct functional units: a first transistor for controlling drive current based on brightness, and a second transistor for maintaining voltage during emission. This segmentation allows independent optimization of each component's operation, enabling lower power consumption while maintaining display reliability and improving peak black gradation expression through dedicated control paths.
3Manufacturing precision
If more transistors and signal lines are added to improve driving control, then driving precision is improved, but device complexity increases
Solution Approach 1:
The patent designs transistors with multi-functionality to reduce overall device complexity. For example, the first transistor serves both as a drive current control element and as part of the voltage maintenance circuit. The second transistor performs both voltage holding and emission control functions. This multi-functionality achieves precise driving control with fewer components, resolving the contradiction between precision and complexity.
Data Source
AI summary
A display device includes a first transistor controlling a control current based on a voltage of a first node, a second transistor electrically connecting a second node to a data line based on a first scan write signal, a third transistor electrically connecting a third node to the first node based on the first scan write signal, a fourth transistor controlling a driving current supplied to the light-emitting element based on a voltage of a fourth node that receives the control current, a fifth transistor electrically connecting a fifth node to the data line based on a second scan write signal, and a sixth transistor t electrically connecting a sixth node to the fourth node based on the second scan write signal.