Liquid Crystal Display Pixel Region Cell-Gap and Threshold Voltage Control
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Solution Overview
Problem
MVA type liquid crystal displays often exhibit higher brightness when viewed obliquely compared to when viewed frontally, leading to uneven display quality and potential color distortion due to differences in cell-gaps and alignment control structures across pixel regions.
Innovation Solution
The liquid crystal display is designed with specific thickness and cell-gap configurations in different pixel regions, along with proportional alignment control blank patterns and electric field control structures, to maintain equal threshold voltages across regions, preventing excessive transmittivity and chromaticity changes when viewed from different angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the cell-gap is increased in certain pixel regions to improve response time, then the response speed is improved, but the threshold voltage becomes uneven across pixel regions causing brightness and color distortion
Solution Approach 1:
The patent applies local quality by introducing higher threshold regions with different threshold voltages in specific pixel regions where the cell-gap is larger. This local variation compensates for the threshold voltage reduction caused by increased cell-gap, ensuring uniform display characteristics across all pixel regions while maintaining improved response speed in the targeted areas.
Solution Approach 2:
The patent changes the threshold voltage parameter in higher threshold regions to be higher than in surrounding regions. This parameter modification compensates for the effect of varied cell-gaps, allowing different pixel regions with different cell-gap thicknesses to achieve uniform threshold voltages and consistent display performance.
2Productivity
If alignment control structures are used to control liquid crystal alignment, then productivity is improved by eliminating rubbing, but brightness becomes higher when viewed obliquely compared to frontal viewing
Solution Approach 1:
The patent modifies the threshold voltage parameter in higher threshold regions to control the transmittivity characteristics. By adjusting the threshold voltage, the patent suppresses excessive transmittivity changes when viewed obliquely, thereby achieving uniform brightness across different viewing angles while maintaining the alignment control structure configuration that eliminates rubbing and improves productivity.
3Speed
If the liquid crystal layer thickness is varied across pixel regions to improve response time, then response speed is improved, but chromaticity changes due to gradation and visual angle changes cause coloring
Solution Approach 1:
The patent introduces higher threshold regions with modified threshold voltage parameters in specific pixel regions where the liquid crystal layer thickness is increased. This local quality adjustment compensates for the chromaticity changes that would otherwise occur due to thickness variations and viewing angle changes, preventing coloring while maintaining improved response time.
Solution Approach 2:
By changing the threshold voltage parameter in higher threshold regions, the patent compensates for the optical path differences caused by varied liquid crystal layer thicknesses. This parameter modification ensures uniform chromaticity across different pixel regions and viewing angles, eliminating coloring effects.
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 ensures consistent brightness and color balance when viewed from various angles, preventing the occurrence of brightness disparities and color distortion, thereby enhancing display quality and simplifying the fabrication process.
Implementation Method 1
alignment directions of the liquid crystal molecules are controlled by the alignment control blank pattern or alignment control structure
Implementation Method 2
changes of the transmittivity for applied voltage changes can be gentle
Data Source
AI summary
The liquid crystal display comprises a first substrate including a first pixel electrode and a second pixel electrode, a second substrate with an opposed electrode formed on, and a liquid crystal layer sealed between the first substrate and the second substrate. The thickness d1 of the liquid crystal layer on the first pixel electrode in the first pixel region is larger than the thickness d2 of the liquid crystal layer on the second pixel electrode in the second pixel region. The first pixel region includes a first partial region and a second partial region where the threshold voltage is higher than in the first partial region. The second pixel region includes a third partial region and a fourth partial region where the threshold voltage is higher than in the third partial region. The threshold voltage in the first partial region and the threshold voltage in the third partial region are equal to each other, and the threshold voltage in the second partial region and the threshold voltage in the fourth partial region are equal to each other. Thus, it is possible to prevent large changes in the chromaticity due to gradation and visual angle changes, which lead to the prevention of the occurrence of the coloring. Thus, it is possible to provide a liquid crystal display having good display quality.