FFS LCD Transparent Common Electrode Segmentation
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Solution Overview
Problem
Fringe Field Switching (FFS) mode Liquid Crystal Displays face challenges in achieving high aperture ratio and transmittance while minimizing the shading region, which affects contrast ratio and picture quality due to light leakage.
Innovation Solution
The solution involves forming a transparent common electrode with bars that cover and insulate data lines, adjusting the slit distance and arrangement of electrodes, and incorporating a low-resistance metal line to reduce the common electrode load, allowing for efficient reduction or removal of the shading region and enhancing transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shading region is formed on the data line to block light, then light leakage is prevented and contrast ratio is improved, but aperture ratio is reduced
Solution Approach 1:
The common electrode is segmented into multiple bars arranged in parallel, creating multiple electric fields between the bars. This segmentation allows the electric field to be concentrated in specific regions (between bars) while leaving other regions (above bars) with reduced electric field strength, thereby reducing light leakage without requiring a shading region that would block light
Solution Approach 2:
The patent creates different electric field characteristics in different regions: strong electric fields in the spaces between common electrode bars for effective liquid crystal switching, and weak electric fields directly above the bars to minimize light leakage. This local differentiation of electric field quality replaces the need for uniform shading regions
2Area of stationary object
If the shading region is removed to improve aperture ratio, then aperture ratio increases, but light leakage occurs and contrast ratio deteriorates
Solution Approach 1:
By segmenting the common electrode into multiple bars, the patent creates a patterned electric field distribution that provides sufficient field strength for switching in pixel regions while minimizing field strength in data line regions, achieving both high aperture ratio and good contrast ratio without shading regions
Solution Approach 2:
The patent changes the spatial distribution parameters of the electric field by adjusting the width, spacing, and arrangement of common electrode bars. This parameter optimization allows the electric field to be strong where needed (for switching) and weak where not needed (above data lines), eliminating the need for shading regions
3Area of stationary object
If transparent electrodes are used to increase aperture ratio and transmittance, then aperture ratio and transmittance are improved, but resistance of the common electrode increases causing Vcom load problems
Solution Approach 1:
The patent uses a composite structure combining transparent conductive material (for the common electrode bars) with opaque conductive material (for the low-resistance metal line). This composite approach maintains the transparency needed for high aperture ratio while adding a low-resistance pathway to reduce Vcom load and eliminate picture quality issues
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 approach increases the aperture ratio, reduces light leakage, and improves picture quality by minimizing the common electrode load, thereby achieving high-brightness and efficient operation without additional processing costs.
Implementation Method 1
a space between the common electrode and the pixel electrode is formed narrower than that between upper and lower glass substrates to form a fringe field between the common electrode and the pixel electrode and drive all liquid crystal molecules existing in upper parts of the electrodes
Implementation Method 2
drive all liquid crystal molecules existing in upper parts of the electrodes, thereby obtaining improved transmittance
Implementation Method 3
forming a low-resistance metal line on a transparent common electrode in a non-opening region through which a gate line and a data line pass to make current flow between the metal line and the transparent common electrode and reduce resistance of the transparent common electrode
Data Source
AI summary
Disclosed is a Fringe Field Switching (FFS) mode Liquid Crystal Display (LCD) including lower substrate, an upper substrate and a liquid crystal layer interposed between the substrates. Each pixel region is defined by gate lines and data lines formed to cross each other on the lower substrate. Switching devices are disposed at intersections of the gate lines and the data lines. The FFS mode LCD includes a transparent pixel electrode, and a transparent common electrode disposed apart from the transparent pixel electrode by an insulating layer interposed therebetween to adjust a transmittance by applying an electric field to the liquid crystal layer. A metal line of a specific thickness is formed to be electrically connected with the transparent common electrode on or under the transparent common electrode of a non-opening region in which the gate lines and the data lines are formed.