Liquid Crystal Display Pixel Electrode Segmentation for Viewing Angle and Transmittance
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Solution Overview
Problem
The pixel division driving technique in liquid crystal display devices reduces viewing angle dependence but decreases aperture ratio and optical transmittance, particularly in high-definition displays with small pixels due to the need for multiple subpixel electrodes and switching elements.
Innovation Solution
A liquid crystal display device with an active-matrix substrate and counter substrate, featuring a thin-film transistor, upper and lower electrodes, and a dielectric layer, where the upper electrode has first and second regions with different electrode structures and a third region connecting them, allowing for symmetrical alignment controlling forces and reduced need for multiple TFTs, thereby increasing optical transmittance and maintaining excellent viewing angle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pixel division driving technique is adopted to reduce viewing angle dependence, then viewing angle characteristic is improved, but aperture ratio and optical transmittance decrease
Solution Approach 1:
The pixel electrode is divided into multiple regions (first region, second region, third region) with different electrode structures. The first and second regions have different patterns that create different electric field distributions, while the third region connects them. This segmentation allows different parts of the same pixel to contribute to reducing viewing angle dependence without requiring multiple separate subpixels with their own TFTs.
Solution Approach 2:
Different regions of the pixel electrode are given different local structures: the first region has a specific electrode pattern, the second region has a different pattern, and the third region has a connecting structure. This local differentiation creates spatially varying electric fields that improve viewing angle characteristics while maintaining a single TFT per pixel, thus preserving aperture ratio.
2Reliability
If multiple subpixel electrodes and switching elements are provided to reduce viewing angle dependence, then viewing angle characteristic is improved, but device complexity increases
Solution Approach 1:
Multiple electrode regions with different structures are merged into a single pixel electrode that is controlled by one TFT. The first, second, and third regions are electrically connected and form one integrated electrode structure, eliminating the need for multiple separate switching elements while still achieving the functional equivalent of multiple subpixels for viewing angle improvement.
Solution Approach 2:
The single pixel electrode with its multiple regions serves multiple functions: it creates different electric field distributions for viewing angle improvement, maintains aperture ratio by avoiding multiple TFTs, and provides a unified control interface through a single TFT. This multi-functionality resolves the contradiction between performance improvement and 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
The solution enhances viewing angle characteristics and maintains high optical transmittance in each pixel, reducing the viewing angle dependence of the gamma characteristic and increasing aperture ratio without the need for multiple switching elements, especially beneficial in high-definition displays.
Implementation Method 1
a liquid crystal layer which is interposed between the active-matrix substrate and the counter substrate
Implementation Method 2
an alignment control structure is provided on each of the two substrates... so as to contact with the liquid crystal layer, thereby forming multiple liquid crystal domains
Implementation Method 3
a dielectric layer which is arranged between the upper and lower electrodes
Data Source
AI summary
The TFT substrate (10) of this liquid crystal display device (100) includes: a TFT (11) which is provided for each pixel; an upper electrode (12) which is electrically connected to the TFT's drain electrode (11d); a lower electrode (13) which is arranged under the upper electrode; and a dielectric layer (14) which is arranged between the upper and lower electrodes. Its counter substrate (20) includes a counter electrode (21) which faces the upper electrode. The upper electrode has first and second regions (R1, R2) which have mutually different electrode structures, and a third region (R3) which electrically connects the first and second regions to the drain electrode. The third region of the upper electrode includes a symmetrical connecting portion (12c) that is a conductive film pattern, of which the shape is substantially symmetrical with respect to a virtual line (L1) that splits each pixel into two adjacent regions in a row direction.