Cross-Shaped Pixel Electrode and Dopant for LCD Transmittance
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Solution Overview
Problem
As liquid crystal display devices are miniaturized, reduced aperture ratio due to driving components and smaller pixels lead to decreased transmittance and side visibility issues, particularly causing grey level differences when viewed from different angles.
Innovation Solution
The design includes a pixel electrode with a stem electrode forming a cross shape dividing the pixel into quadrants, with branch electrodes in each quadrant tilted at specific angles to intersect each other, and a liquid crystal mixture containing a dopant that adjusts the pitch of liquid crystals, optimizing transmittance and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of switching elements and contact holes is reduced to improve transmittance, then transmittance is improved, but grey level difference occurs between front and side viewing, degrading side visibility
Solution Approach 1:
The pixel electrode is divided into multiple domains (first, second, third, and fourth domains) with branch electrodes extending in different tilted directions. This segmentation allows each domain to control liquid crystal orientation independently, enabling optimized transmittance from multiple viewing angles simultaneously while maintaining uniform grey levels across the pixel.
Solution Approach 2:
Branch electrodes are configured with asymmetric tilted directions relative to the first and second directions. Specifically, branch electrodes in different domains extend at different angles, creating asymmetric field patterns that compensate for viewing angle dependencies and eliminate grey level differences between front and side views.
2Measurement precision
If pixels are made smaller to achieve high resolution, then resolution is improved, but aperture ratio is reduced causing decreased transmittance
Solution Approach 1:
The pixel electrode structure utilizes tilted branch electrodes extending in directions between the first and second directions. This dimensional approach creates electric field components that orient liquid crystal molecules at optimized angles, improving light transmission through the pixel aperture without increasing the pixel footprint area.
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 transmittance and side visibility by optimizing the alignment of liquid crystal molecules and minimizing grey level differences across viewing angles.
Implementation Method 1
a vertically aligned mode liquid crystal display device, in which the major axes of the liquid crystal molecules are aligned vertical to upper and lower substrates in the absence of electric field
Implementation Method 2
apply voltages to the electric field generating electrodes to generate an electric field in the liquid crystal layer
Implementation Method 3
control the polarization of incident light
Data Source
AI summary
A liquid crystal display device includes: first and second substrates facing each other and including a plurality of pixels; a liquid crystal layer between the first and second substrates and including a liquid crystal mixture. The first substrate includes a pixel electrode in each pixel. The pixel electrode includes a stem electrode extending in a first direction and a second direction in a cross shape and dividing the pixel into first to fourth domains; and branch electrodes disposed in the first to fourth domains and extending from the stem electrode in a tilted direction to the first and second directions. The branch electrodes disposed in two adjacent domains extend to have angles different from each other with respect to the first direction and the second direction. The liquid crystal mixture includes liquid crystals, and a dopant which adjusts a pitch of the liquid crystals.