Liquid Crystal Display with Cross-Shaped Common Electrode Cutouts
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Solution Overview
Problem
Liquid crystal displays (LCDs) face a reduction in aperture ratio while attempting to achieve a wide viewing angle and fast response speed, particularly in vertical alignment (VA) mode LCDs, due to the use of minute slits in field-generating electrodes which affect the tilt directions of liquid crystal molecules.
Innovation Solution
The design incorporates a common electrode with cross-shaped openings that protrude beyond the edges of the pixel electrode, dividing the pixel electrode into sub-regions and using photoreactive materials in alignment layers to achieve pretilt angles, allowing liquid crystal molecules to be aligned vertically and tilted in specific directions for improved viewing angles and transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If minute slits are formed in the pixel electrode to create multiple branch electrodes for wide viewing angle, then the viewing angle is improved, but the aperture ratio is reduced
Solution Approach 1:
The common electrode is segmented into multiple regions separated by protrusions, creating distinct sub-regions that generate different tilt directions for liquid crystal molecules. This segmentation allows wide viewing angle without requiring slits in the pixel electrode, thus maintaining high aperture ratio
Solution Approach 2:
The invention moves the electrode structure modification from the pixel electrode plane to the common electrode plane with three-dimensional protrusions. By creating vertical protrusions that extend into the liquid crystal layer, the patent achieves multi-directional tilt control without reducing the horizontal aperture area
2Speed
If multiple branch electrodes are formed by cutting the pixel electrode to achieve fast response speed, then the response speed is improved, but the aperture ratio is reduced
Solution Approach 1:
The common electrode is divided into multiple isolated regions by protrusions, creating electric field segments that independently control liquid crystal molecules in different sub-regions. This enables fast response through localized field control without reducing the overall pixel aperture area
Solution Approach 2:
The protrusions act as intermediary structures that extend from the common electrode into the liquid crystal layer, serving as field-generating elements without requiring modifications to the pixel electrode. These protrusions mediate the electric field distribution to achieve fast response while preserving aperture ratio
3Adaptability or versatility
If the common electrode has cross-shaped openings with protruding edges to divide pixel electrode into sub-regions, then the viewing angle and transmittance are improved, but the device complexity is increased
Solution Approach 1:
The protrusions on the common electrode serve multiple functions simultaneously: they define sub-region boundaries, generate electric fields for tilt control, and act as alignment references for liquid crystal molecules. This multi-functionality achieves wide viewing angle without proportionally increasing device complexity
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, response speed, and visibility of the LCD while increasing the aperture ratio and transmittance, compared to conventional designs with minute branch electrodes.
Implementation Method 1
At least one of the liquid crystal layer, the first alignment layer, and the second alignment layer includes a photoreactive material
Implementation Method 2
An LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer that determines the orientations of LC molecules therein
Data Source
AI summary
A liquid crystal display according to an exemplary embodiment of the present invention includes: a first substrate; a pixel electrode disposed on the first substrate; a first alignment layer disposed on the first substrate and the pixel electrode; a second substrate facing the first substrate; a common electrode disposed on the second substrate; a second alignment layer disposed on the second substrate and the common electrode; and a liquid crystal layer disposed between the first substrate and the second substrate, wherein the common electrode has a plurality of cutouts having a cross shape, and when viewing the first substrate and the second substrate upward, the edge of the cutout is protruded from the edge of the pixel electrode.