LCD Aperture Ratio via Extended Common Electrode
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Solution Overview
Problem
In liquid crystal display (LCD) devices with a double reduced data (DRD) pixel structure, light leakage occurs around contact holes due to non-uniform alignment layers, reducing transmittance and aperture ratio, which is exacerbated by the need for a black matrix to cover these areas, thereby limiting image quality.
Innovation Solution
The LCD device features alternately formed gate lines and data lines with TFTs positioned between them, forming pixel areas where the common electrode line perpendicularly crosses the gate lines, and a pixel electrode is coupled to the TFTs through contact holes, with a common electrode extending beyond the gate lines to reduce light leakage and increase aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black matrix is used to cover light leakage around contact holes, then light leakage is reduced, but the aperture ratio decreases
Solution Approach 1:
The patent extracts the light leakage problem from the contact hole area by forming the common electrode to extend beyond the gate line, effectively removing the need for black matrix coverage in those regions. This separates the light leakage issue from the active pixel area, allowing the aperture ratio to increase while still addressing light leakage where necessary.
Solution Approach 2:
The patent changes the dimensional arrangement by extending the common electrode in a direction beyond the gate line, creating an overlapping region that addresses light leakage from a different spatial perspective. This dimensional extension allows light leakage control without sacrificing aperture ratio in the pixel area.
2Illumination intensity
If the common electrode is extended beyond gate lines to reduce light leakage, then transmittance increases, but device complexity increases
Solution Approach 1:
The common electrode serves multiple functions: it generates the electric field for liquid crystal switching and simultaneously acts as a light leakage prevention structure by extending beyond the gate line. This multi-functionality increases transmittance without requiring additional dedicated structures, thereby limiting the increase in device complexity.
3Ease of manufacture
If DRD pixel structure is used to reduce data lines, then manufacturing cost decreases, but light leakage increases due to non-uniform alignment layers
Solution Approach 1:
The extended common electrode acts as an intermediary structure between the gate line and the pixel area, providing a transition zone that prevents light leakage caused by non-uniform alignment layers. This mediator approach maintains the cost benefits of the DRD structure while addressing the light leakage issue without requiring additional complex components.
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 configuration enhances the aperture ratio by reducing the length of the black matrix needed to cover light leakage, increasing transmittance by approximately 30% compared to traditional DRD structures, thereby improving image quality.
Implementation Method 1
a voltage is applied to the electrodes, the liquid crystal molecules are driven by an electric field generated with the voltage
Implementation Method 2
an image is displayed based on a light transmittance which is changed according to movements of the liquid crystal molecules
Implementation Method 3
the common electrode and the pixel electrode are arranged in parallel on one substrate to generate a lateral electric field
Implementation Method 4
the common electrode and the pixel electrode are alternately arranged on different layers on one substrate to generate a fringe field
Data Source
AI summary
Disclosed is a liquid crystal display (LCD) device. The LCD device include first and second gate lines, data lines, a common electrode line formed between adjacent data lines and configured to perpendicularly cross the plurality of first and second gate lines and divide the plurality of pixel areas into first and second areas, first and second thin film transistors (TFTs) formed between a corresponding first gate line and a second gate line adjacent to the corresponding first gate line, a protective layer configured to include a first contact hole and a second contact hole, a common electrode formed on the protective layer and coupled to the common electrode line through the first contact hole, an insulation layer formed on the protective layer to cover the common electrode and a pixel electrode formed on the insulation layer.