Pixel Driving Circuit for VA LCD Color Shift Correction
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Solution Overview
Problem
Vertical alignment (VA)-type LCD panels suffer from significant color shifting due to the greater birefringence difference of liquid crystal molecules, which is exacerbated by the need for many thin film transistors (TFTs) in 3T technology, leading to reduced aperture ratio and increased parasitic capacitance.
Innovation Solution
A pixel driving circuit with sub-pixel units comprising a first and second switch, each connected to scanning and data lines, where the second switch is a double-source electrode TFT, forming a voltage difference between the first and second pixel electrodes, optimizing the voltage relationship to minimize color shift without increasing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If 3T technology is used to reduce color shift in VA-type LCD panels, then color shift is improved, but aperture ratio decreases and parasitic capacitance increases
Solution Approach 1:
The patent extracts the common voltage control function from the traditional 3T structure by introducing a separate common electrode line. This allows the pixel electrode to be controlled by a single TFT while the common electrode receives independent voltage control, eliminating the need for multiple TFTs per pixel and reducing parasitic capacitance while maintaining color shift correction capability
Solution Approach 2:
The patent segments the voltage control system into two independent parts: a pixel electrode controlled by data voltage through one TFT, and a common electrode controlled by common voltage through a separate line. This segmentation allows independent optimization of each control path, reducing the total number of TFTs required while maintaining the ability to correct color shift through differential voltage control
2Object-affected harmful factors
If more TFTs are used per pixel unit, then color shift control is improved, but parasitic capacitance increases affecting display performance
Solution Approach 1:
The patent extracts the common voltage control function from the traditional 3T structure by introducing a separate common electrode line. This allows the pixel electrode to be controlled by a single TFT while the common electrode receives independent voltage control, eliminating the need for multiple TFTs per pixel and reducing parasitic capacitance while maintaining color shift correction capability
Solution Approach 2:
The patent introduces a common electrode as an intermediary element that receives voltage control through a separate common electrode line. This intermediary allows voltage modulation to be applied to the liquid crystal layer without requiring additional TFTs at each pixel, thereby reducing parasitic capacitance while maintaining the ability to correct color shift through differential voltage control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces color shift, enhances the aperture ratio, and maintains low parasitic capacitance, thereby improving the display performance of VA-type LCD panels.
Implementation Method 1
The first switch has a control terminal, a first terminal, and a second terminal. The control terminal of the first switch is connected with one of the scanning lines, the first terminal of the first switch is connected with one of the data lines, and the second terminal of the first switch is connected with the first pixel electrode. The first terminal and the second terminal of the first switch are turned on under control of a scanning signal provided by the scanning line.
Implementation Method 2
The second switch has a control terminal, a first terminal, a second terminal, and a third terminal. The control terminal of the second switch is connected with one of the scanning lines, the first terminal of the second switch is connected with one of the data lines, the second terminal of the second switch is connected with a common electrode line, and the third terminal of the second switch is connected with the second pixel electrode. The first terminal, the second terminal, and the third terminal of the second switch are turned on under control of the scanning signal provided by the scanning line such that a predetermined voltage difference is formed between the first pixel electrode and the second pixel electrode.
Data Source
AI summary
The present disclosure provides a pixel driving circuit and a liquid crystal display (LCD) panel. A first terminal, a second terminal, and a third terminal of the second switch are connected with a data line, a common electrode line, a second pixel electrode, respectively. The first terminal, the second terminal, and the third terminal of the second switch are turned on, and a voltage of the second pixel electrode is between a data voltage provided by the data line and a common voltage provided by the common electrode line, such that a predetermined voltage difference is formed between the first pixel electrode and the second pixel electrode.