FFS Array Substrate Segmented Electrode Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fringe field switching (FFS) mode liquid crystal display devices face challenges with high storage capacitor capacitance, which hinders charging in high definition or high frequency models, leading to decreased aperture ratio and transmittance.
Innovation Solution
The array substrate design includes a pixel electrode with two parts and an opening portion between them, a first common electrode on the same layer as the pixel electrode, and a second common electrode connected through a common contact hole, with specific openings to minimize capacitance and maintain a strong fringe field, while ensuring the pixel and common electrodes are on the same layer to reduce overlapping area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional FFS mode array substrate is used, then the liquid crystal molecules can be driven by a horizontal electric field to achieve wide viewing angles, but the storage capacitor has high capacitance which hinders charging in high definition or high frequency models
Solution Approach 1:
The pixel electrode is divided into two separate parts (first pixel electrode and second pixel electrode) instead of a single continuous electrode. This segmentation reduces the overlapping area with the common electrode, thereby decreasing the storage capacitor capacitance while maintaining the horizontal electric field configuration needed for wide viewing angles
Solution Approach 2:
The patent extracts or removes portions of the pixel electrode to create a non-contact region between the pixel electrode and common electrode. This extraction reduces the overlapping area specifically to lower capacitance while preserving the essential fringe field switching functionality
2Reliability
If the overlapping area between pixel electrode and common electrode is increased to improve capacitance, then charging may be improved, but the aperture ratio and transmittance decrease
Solution Approach 1:
By segmenting the pixel electrode into two parts, the patent achieves sufficient capacitance for charging performance while minimizing the overlapping area with the common electrode. This segmentation allows the electrode to be strategically positioned to maintain necessary capacitance without excessive overlap that would reduce aperture ratio
Solution Approach 2:
The patent applies different configurations to different regions: the pixel electrode parts are positioned to overlap with the common electrode in regions where capacitance is needed, while creating non-contact regions where aperture ratio should be maximized. This local differentiation optimizes both charging performance and aperture ratio
3Reliability
If the pixel electrode and common electrode are placed on different layers to increase overlapping area, then capacitance increases, but the manufacturing complexity and layer structure become more complicated
Solution Approach 1:
The patent merges the pixel electrode and common electrode onto the same layer, eliminating the need for additional layer structures. This same-layer configuration simplifies the device structure while the segmented design of the pixel electrode ensures sufficient overlapping area for adequate capacitance without requiring complex multi-layer arrangements
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 decreases the capacitance of the storage capacitor, improving charging properties, increasing aperture ratio and transmittance, and minimizing color shift and brightness variation, especially applicable to large-sized LCD devices.
Implementation Method 1
a horizontal electric field that is parallel to the substrate is induced between the pixel electrode and the common electrode. Liquid crystal molecules are driven by the horizontal electric field
Implementation Method 2
Liquid crystal display (LCD) devices are driven based on optical anisotropy and polarization characteristics of a liquid crystal material
Implementation Method 3
Light passes through the LCD device along the long and thin shape of the liquid crystal molecules
Implementation Method 4
Fringe field switching (FFS) mode liquid crystal display devices face challenges with high storage capacitor capacitance, which hinders charging
Data Source
AI summary
An array substrate for a wide viewing angle liquid crystal display device includes a gate line on a substrate, a data line crossing the gate line to define a pixel region, a thin film transistor electrically connected to the gate and data lines, a pixel electrode in the pixel region and connected to a drain electrode of the thin film transistor, the pixel electrode including two parts and an opening portion therebetween, a first common electrode in the opening portion, the first common electrode disposed on a same layer as the pixel electrode, a passivation layer on the pixel electrode and the first common electrode, the passivation layer having a common contact hole exposing the first common electrode, and a second common electrode on the passivation layer and connected to the first common electrode through the common contact hole, the second common electrode including first openings corresponding to the pixel electrode and a second opening corresponding to the opening portion.