LCD Sub-Pixel Electrode Segmentation for Viewing Angle and Aperture Ratio
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Solution Overview
Problem
Liquid crystal display (LCD) in vertical alignment mode faces issues with reduced aperture ratio, slow response speed, and side visibility due to the formation of domains and texture caused by cutouts in field-generating electrodes, and light alignment methods that can lead to different alignment directions of LC molecules, resulting in texture and decreased transmittance.
Innovation Solution
The LCD is designed with one pixel divided into two sub-pixels, where a shielding member is used to overlap the gap between the sub-pixel electrodes, and the LC layers are aligned in multiple domains to reduce texture generation, improving aperture ratio and response time, and by using a light alignment method to control LC molecule alignment, ensuring uniform voltage application and enhanced side visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cutouts are formed in field-generating electrodes to create multiple domains, then viewing angle is improved, but aperture ratio decreases and response speed becomes slow
Solution Approach 1:
The pixel electrode is divided into multiple sub-pixel electrodes (first, second, third, and fourth sub-pixel electrodes) arranged in a specific pattern. This segmentation creates multiple domains within the pixel without requiring cutouts in the electrode structure, thereby maintaining high aperture ratio while achieving wide viewing angle through the coordinated arrangement of these segmented electrodes
Solution Approach 2:
The sub-pixel electrodes are arranged asymmetrically with different spacing relationships - the first and second sub-pixel electrodes are spaced by a first gap, while the third and fourth sub-pixel electrodes are spaced by a second gap. This asymmetric arrangement optimizes the fringe field distribution to create multiple domains for wide viewing angle without sacrificing aperture area
2Productivity
If light alignment method is used to control LC molecule alignment, then aperture ratio increases and response time improves, but texture is generated at sub-pixel gaps causing decreased transmittance
Solution Approach 1:
The pixel is segmented into multiple sub-pixels with different alignment directions. By dividing the pixel into first, second, third, and fourth sub-pixel electrodes, each can have optimized alignment without causing texture at the center, as the multiple segments distribute the alignment variations across different regions rather than concentrating them at a single gap
Solution Approach 2:
Different regions of the alignment layer are given different alignment characteristics through selective light alignment treatment. The alignment directions are locally optimized for each sub-pixel region, creating pre-tilt angles that are uniform within each sub-pixel but vary between sub-pixels, thereby eliminating texture while maintaining fast response
3Adaptability or versatility
If one pixel is divided into two sub-pixels with different voltages to improve side visibility, then viewing angle is improved, but texture is generated due to different alignment directions
Solution Approach 1:
The pixel is divided into four sub-pixel electrodes rather than two, with each sub-pixel having specific alignment directions. This finer segmentation allows for more precise control of the fringe fields and LC molecule alignment, creating multiple domains that improve side visibility while the coordinated arrangement prevents texture formation
Solution Approach 2:
The sub-pixel electrodes are arranged with asymmetric spacing (first gap between first and second sub-pixels, second gap between third and fourth sub-pixels). This asymmetric configuration optimizes the voltage distribution and fringe field patterns to create uniform domain structures that eliminate texture while enhancing side visibility
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, response time, and side visibility of the LCD by reducing texture and improving transmittance, while maintaining high contrast ratio and wide viewing angles.
Implementation Method 1
the alignment direction of the LC molecules and the alignment angle may be controlled by irradiating light onto the alignment layer
Implementation Method 2
the plurality of domains may be formed by aligning the LC molecules vertically with respect to the fringe field generated between the edges of the cutout and the field generating electrodes facing the edges
Implementation Method 3
The LCD displays images when voltages are applied to the field-generating electrodes to generate an electric field in the LC layer that determines the orientations of LC molecules therein to adjust polarization of incident light
Data Source
AI summary
A liquid crystal display includes a first substrate and a second substrate facing each other, a pixel electrode disposed on the first substrate and including a first sub-pixel electrode and a second sub-pixel electrode spaced apart from the first sub-pixel electrode by a gap, a common electrode disposed on the second substrate, a shielding member disposed on the first substrate or the second substrate and overlapping the gap between the first sub-pixel electrode and the second sub-pixel electrode, an alignment layer disposed on at least one of the pixel electrode and the common electrode, and a liquid crystal layer disposed between the first substrate and the second substrate.