Liquid Crystal Display Dual Common Electrode Lateral Visibility
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Solution Overview
Problem
Liquid crystal display (LCD) devices face a challenge in achieving high aperture ratio and improved lateral visibility due to the need for multiple wirings and thin-film transistors, which reduces transmittance and complicates the application of different voltages to sub-electrodes.
Innovation Solution
The design includes a first and second common electrode configuration with an opening in each pixel, where the second common electrode protrudes along the boundary between adjacent pixel electrodes and has an increased area from the central part towards the boundary, allowing for a single TFT to apply different electric fields across distinct regions, enhancing lateral visibility without compromising aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple wirings and TFTs are used to apply different voltages to sub-electrodes, then lateral visibility is improved, but aperture ratio decreases and device complexity increases
Solution Approach 1:
The common electrode is divided into two separate common electrodes (first common electrode and second common electrode) positioned at different heights. This segmentation allows different voltages to be applied to different regions of the pixel, achieving improved lateral visibility without requiring multiple TFTs per pixel, thus maintaining a high aperture ratio.
Solution Approach 2:
The patent introduces a vertical dimension by stacking the first and second common electrodes at different heights above the pixel electrode. This three-dimensional arrangement enables multiple voltage applications without increasing the planar footprint, thereby preserving the aperture ratio while achieving the desired lateral visibility improvement.
2Ease of operation
If multiple wirings and TFTs are used to apply different voltages to sub-electrodes, then lateral visibility is improved, but device complexity increases
Solution Approach 1:
The common electrode is divided into two separate common electrodes (first common electrode and second common electrode) positioned at different heights. This segmentation allows different voltages to be applied to different regions of the pixel, achieving improved lateral visibility without requiring multiple TFTs per pixel, thus maintaining a high aperture ratio.
Solution Approach 2:
The stacked common electrode structure serves multiple functions: it enables different voltage applications for lateral visibility improvement, maintains a simple TFT configuration (one TFT per pixel), and preserves the aperture ratio. This multi-functional design reduces overall device complexity while achieving the desired performance improvement.
3Ease of operation
If the second common electrode area increases from central part toward boundary, then lateral visibility is improved, but manufacturing precision requirements increase
Solution Approach 1:
The second common electrode is designed with a non-uniform area distribution that increases from the central part toward the boundary of the pixel. This local variation in electrode area creates optimized electric field distribution in different regions, improving lateral visibility. The gradual transition in area reduces manufacturing precision requirements compared to abrupt changes.
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 improves lateral visibility by generating varying electric fields across different regions of the pixel, achieving similar results to splitting the pixel electrode into sub-electrodes while maintaining a high aperture ratio and reducing the complexity of multiple TFTs.
Implementation Method 1
main directors of liquid crystal molecules are aligned perpendicular to upper and lower display substrates when no electric field is applied
Implementation Method 2
voltages are applied to electric field generating electrodes to generate an electric field. Accordingly, the alignment of liquid crystal molecules of a liquid crystal layer is determined, and polarized light of incident light is controlled
Implementation Method 3
an electric field generated between the pixel electrode and the second common electrode in the second region may be greater than an electric field generated between the pixel electrode and the first common electrode in the first region
Data Source
AI summary
Liquid crystal display includes a first substrate which includes a pixel electrode disposed in each pixel, a second substrate which faces the first substrate and includes a common electrode and an insulating layer, and a liquid crystal layer which is disposed between the first substrate and the second substrate, where the common electrode includes a first common electrode which is disposed on the whole surface defining the second substrate and a second common electrode which is disposed on the first common electrode with the insulating layer interposed therebetween and includes an opening defined in each pixel, and each pixel includes a first region in which the pixel electrode and the first common electrode face each other through the opening and a second region in which the pixel electrode and the second common electrode face each other.