Cross-Shaped Pixel Electrodes for Wide Viewing Angle LCDs
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in achieving a wide viewing angle and high display quality, particularly in maintaining brightness at intermediate gray levels and preventing gray level inversion, due to limitations in electric field distribution and pixel electrode design.
Innovation Solution
The liquid crystal display device incorporates a specific configuration of pixel and common electrodes on substrates, with a main pixel electrode and sub-pixel electrode forming a cross shape, and common electrodes extending in specific directions on both substrates, creating an oblique electric field that aligns liquid crystals horizontally, allowing for four domains per pixel and uniform transmittance across a wide viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional lateral electric field configuration (IPS or FFS mode) is used, then the viewing angle is improved, but the brightness at intermediate gray levels deteriorates and gray level inversion occurs
Solution Approach 1:
The pixel electrode is divided into a main pixel electrode and multiple sub-pixel electrodes. The sub-pixel electrodes are positioned between the main pixel electrode and the common electrodes, creating segmented regions that generate multiple distinct electric field domains within each pixel. This segmentation enables four-domain configuration that maintains uniform transmittance across wide viewing angles while preventing gray level inversion.
Solution Approach 2:
The patent transitions from conventional two-electrode configurations to a multi-electrode three-dimensional arrangement. Sub-pixel electrodes are positioned at different spatial locations between the array substrate and counter substrate, creating oblique electric fields that extend in multiple dimensions. This dimensional expansion enables uniform liquid crystal alignment across wide viewing angles while maintaining accurate gray level control.
2Device complexity
If pixel electrodes and common electrodes are arranged in conventional configurations, then the device structure is simple, but the electric field distribution is insufficient to prevent gray level inversion
Solution Approach 1:
Different electrode regions are assigned specific functions: the main pixel electrode provides primary voltage application, while sub-pixel electrodes positioned at specific locations create localized electric field domains. Common electrodes are arranged to work cooperatively with sub-pixel electrodes. This local functional differentiation ensures uniform electric field distribution and prevents gray level inversion while maintaining reasonable structural complexity.
3Ease of manufacture
If conventional electrode arrangements are used, then manufacturing is easier, but display quality and uniformity deteriorate
Solution Approach 1:
Multiple electrode functions are merged into a coordinated system. The main pixel electrode and sub-pixel electrodes work together to create the desired electric field pattern, while common electrodes provide cooperative voltage application. This merged electrode system achieves uniform display quality and wide viewing angles through coordinated operation, while all electrodes can be fabricated using standard thin-film deposition techniques on the array substrate and counter substrate.
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 viewing angle, maintains high brightness at intermediate gray levels, and prevents gray level inversion, resulting in improved display quality with wider viewing angles and reduced influence from misalignment between substrates.
Implementation Method 1
liquid crystal molecules are switched by a lateral electric field which is substantially parallel to a major surface of the array substrate
Implementation Method 2
a liquid crystal layer which includes liquid crystal molecules held between the array substrate and the counter substrate
Data Source
AI summary
A liquid crystal display device includes a first substrate including gate lines and a storage capacitance line, a first source line and a second source line, a main pixel electrode which has a strip shape, a sub-pixel electrode which is continuous with the main pixel electrode and has a strip shape extending toward the first source line and the second source line, and a first alignment film, a second substrate including second main common electrodes extending on both sides of the main pixel electrode, second sub-common electrodes which are continuous with the second main common electrodes and extend on both sides of the sub-pixel electrode, and a second alignment film, and a liquid crystal layer held between the first substrate and the second substrate.