FFS Liquid Crystal Display Common Electrode for High Aperture Ratio
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Solution Overview
Problem
Conventional liquid crystal display devices face issues with reduced contrast and aperture ratio due to insufficient common electrode potential, particularly in larger panels, caused by high resistance in transparent electrodes like ITO, and the presence of auxiliary common electrode lines within the display region which create light-shielding regions.
Innovation Solution
The liquid crystal display device incorporates a common electrode extending over all pixels connected to a peripheral common electric potential line on the display region's periphery, eliminating the need for auxiliary common electrode lines, ensuring sufficient common electric potential supply while maintaining high aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transparent electrodes like ITO are used for common electrode, then electrical conductivity is improved, but resistance increases causing insufficient common electrode potential in larger panels
Solution Approach 1:
The common electrode is divided into multiple segments (first common electrode and second common electrode) separated by a non-common electrode region. This segmentation reduces the overall resistance by creating multiple parallel conduction paths, ensuring sufficient common electrode potential is maintained across larger panel areas without requiring high-resistance transparent electrodes throughout the entire region.
2Reliability
If auxiliary common electrode lines are added within display region, then common electrode potential supply is improved, but aperture ratio decreases due to light-shielding regions
Solution Approach 1:
The auxiliary common electrode lines are extracted from the display region and relocated to the non-common electrode region surrounding the display area. This extraction eliminates the light-shielding problem within the display region while still providing adequate common electrode potential supply through the peripheral non-common electrode region, thereby maintaining high aperture ratio.
3Stability of the object's composition
If common electrode extends over all pixels, then lateral electric field uniformity is improved, but resistance increases causing potential drop
Solution Approach 1:
The common electrode is segmented into multiple regions (first common electrode region and second common electrode region) separated by non-common electrode regions. This segmentation maintains electric field uniformity within each pixel area while reducing overall resistance by creating multiple independent conduction paths, preventing potential drops across large panel areas.
Solution Approach 2:
The common electrode structure transitions from a single continuous planar layer to a multi-dimensional segmented structure with both horizontal extension across pixels and vertical separation through multiple layers/regions. This dimensional change allows the electrode to maintain uniformity in the display region while reducing resistance through alternative conduction paths in the non-common electrode regions.
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 ensures adequate common electric potential supply to the common electrode through low resistance, enhancing display quality by improving aperture ratio and reducing light-shielding, thus achieving brighter and more efficient display performance.
Implementation Method 1
an alignment direction of liquid crystal molecules is controlled by a lateral electric field generated between a pixel electrode and a common electrode
Data Source
AI summary
A liquid crystal display device according to FFS technology is provided, which sufficiently provides a common electrode with common electric potential and improves an aperture ratio of pixels. A pixel electrode is formed of a first layer transparent electrode. A common electrode made of a second layer transparent electrode is formed above the pixel electrode interposing an insulation film between them. The common electrode in an upper layer is provided with a plurality of slits. The common electrode extends over all the pixels in a display region. An end of the common electrode is disposed on a periphery of the display region and connected with a peripheral common electric potential line that provides a common electric potential Vcom. There is provided neither an auxiliary common electrode line nor a pad electrode, both of which are provided in a liquid crystal display device according to a conventional art.