Fringe Field Switching LCD Slit Electrode Aperture Ratio
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Solution Overview
Problem
Conventional fringe field switching (FFS) mode liquid crystal display devices face issues with reduced aperture ratio, light leakage, and internal reflection due to cross-talk, disclination, and the need for a minimum black matrix, which limits higher resolution and external visibility.
Innovation Solution
The FFS mode LCD design eliminates contact holes and includes a transparent common electrode with slits angled 5 to 10° relative to gate lines, a reflective structure under data lines, and a rubbing direction parallel to gate lines to enhance aperture ratio and prevent light leakage, while maintaining high resolution and internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black matrix is used to cover cross-talk and disclination regions, then light leakage is prevented, but the aperture ratio decreases
Solution Approach 1:
The invention extracts and removes the black matrix component entirely from the display structure. Instead of using a black matrix to cover cross-talk and disclination regions, the patent redesigns the electrode configuration and liquid crystal alignment to eliminate these defects at their source, thereby preventing light leakage without sacrificing aperture ratio.
Solution Approach 2:
The invention converts the harmful effects of cross-talk and disclination into beneficial outcomes by redesigning the system. The slanted slit configuration and specific rubbing direction (5-10 degrees relative to gate lines) transform potential defect regions into areas that contribute to overall display performance, eliminating the need for light-blocking black matrix structures.
2Measurement precision
If the unit pixel size is reduced to achieve higher resolution, then resolution is improved, but the aperture ratio may be reduced due to minimum contact hole size constraints
Solution Approach 1:
The invention segments the common electrode into multiple slits with specific orientations (5-10 degrees relative to gate lines). This segmentation allows the electrode structure to function effectively at smaller pixel sizes without requiring proportionally smaller contact holes, thereby maintaining aperture ratio while enabling higher resolution through reduced unit pixel dimensions.
Solution Approach 2:
The invention changes the geometric parameters of the electrode structure, specifically introducing slanted slits at 5-10 degree angles and optimizing their dimensions. These parameter changes allow the common electrode to maintain its functionality and electrical performance even as pixel size is reduced for higher resolution displays, preventing aperture ratio degradation.
3Stability of the object's composition
If rubbing is performed at a predetermined angle with respect to the data line, then alignment is achieved, but light leakage due to rubbing failures is caused around one side of the data line
Solution Approach 1:
The invention introduces asymmetric elements into the alignment configuration by setting the rubbing direction at a specific angle (5-10 degrees) relative to the gate lines rather than parallel or perpendicular. This asymmetric angle optimizes the liquid crystal alignment to prevent disclination and eliminates rubbing-related light leakage around data lines while maintaining proper alignment stability.
4Area of stationary object
If contact holes are removed to increase aperture ratio, then aperture ratio is improved, but the fabrication process becomes more complex
Solution Approach 1:
The invention segments the common electrode into slits that can be formed using standard photolithography and etching processes. This segmentation approach allows the electrode pattern to be created without requiring contact hole formation steps, thereby increasing aperture ratio while maintaining compatibility with conventional fabrication processes and avoiding excessive process complexity.
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
This design increases the aperture ratio, reduces light leakage, and improves internal reflection, enabling better external visibility and higher resolution without the need for a black matrix, thus addressing the limitations of conventional FFS mode LCDs.
Implementation Method 1
a liquid crystal layer disposed between the substrates... to adjust optical transmittance by applying a voltage to the liquid crystal layer
Implementation Method 2
a gap between the common electrode and the pixel electrode is smaller than a gap between upper and lower glass substrates so that a fringe field can be formed between the common electrode and the pixel electrode
Implementation Method 3
improving internal reflection... enabling better external visibility
Data Source
AI summary
Provided is a liquid crystal display including a transparent pixel electrode and a transparent common electrode in a pixel region to drive liquid crystals. The transparent common electrode includes a plurality of slits and is configured to open at least a portion of a switching device to connect unit pixels, the slits have an angle of 5 to 10° with respect to a gate line, and a rubbing direction of a liquid crystal layer is substantially parallel to a gate direction. Therefore, it is possible to provide the liquid crystal display capable of removing factors decreasing an aperture ratio, preventing light from leaking, and further improving internal reflection.