Segmented Pixel Electrodes Reduce Leakage Current in Display Devices
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Solution Overview
Problem
Display devices using poly silicon thin film transistors suffer from high leakage current, leading to cross-talk between pixels, which complicates manufacturing and affects image quality.
Innovation Solution
The design incorporates a display device with multiple switching transistors connected in series, featuring sub-pixel and main pixel electrodes with varying capacitances and areas, and semiconductor layers made of amorphous or micro-silicon, eliminating the need for a lightly doped drain structure and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If poly silicon is used as the semiconductor layer to achieve high field-effect mobility, then the electrical characteristics are improved, but leakage current increases causing cross-talk between pixels
Solution Approach 1:
The pixel electrode is divided into multiple sub-pixel electrodes (first sub-pixel electrode, second sub-pixel electrode, third sub-pixel electrode). Each sub-pixel electrode is controlled by its own switching transistor, distributing the voltage control function across multiple smaller units. This segmentation reduces the leakage current impact on each individual electrode while maintaining overall pixel performance.
2Object-generated harmful factors
If a lightly doped drain structure is used to reduce leakage current and prevent cross-talk, then the harmful effects are minimized, but the manufacturing complexity increases due to requiring two ion-doping processes
Solution Approach 1:
The invention extracts and removes the complex lightly doped drain structure from the device. Instead of using ion-doping processes to create LDD regions, the patent achieves leakage current reduction through the segmented pixel electrode configuration and capacitor-based voltage maintenance, simplifying the manufacturing process while maintaining effectiveness.
3Illumination intensity
If the pixel electrode area is increased to improve image brightness, then the illumination intensity is improved, but the leakage current increases leading to more cross-talk
Solution Approach 1:
The large pixel electrode is segmented into multiple smaller sub-pixel electrodes. This allows the total area to remain large for sufficient brightness while each individual sub-pixel electrode has reduced leakage current. The segmentation maintains overall illumination intensity while minimizing the harmful leakage effects.
4Object-generated harmful factors
If amorphous silicon is used as the semiconductor layer to reduce leakage current, then the harmful factors are reduced, but the field-effect mobility decreases affecting device performance
Solution Approach 1:
The invention applies different material properties to different parts of the device. The switching transistors use amorphous silicon semiconductor layers where low leakage current is critical, while other components can use materials with higher mobility. This local differentiation allows each component to have optimal material properties for its specific function.
Data Source
AI summary
A display device includes a first switching transistor, a first driving transistor connected to the first switching transistor, a second switching transistor including an input terminal connected to an output terminal of the first switching transistor, a second driving transistor connected to the second switching transistor, and a pixel unit comprising a sub-pixel electrode connected to the first driving transistor and a main pixel electrode separated from the sub-pixel electrode and connected to the second driving transistor.