Liquid Crystal Display Device Impurity Migration Control
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Solution Overview
Problem
Liquid crystal display devices face issues with display defects such as missing dots, alignment variation, and ghosting due to impurities in the liquid crystal layer, which are affected by the voltage holding ratio (VHR) and ion density (ID) decreases, despite existing techniques not adequately addressing these problems.
Innovation Solution
A liquid crystal display device incorporating a specific liquid crystal composition and a color filter with a pigment having controlled water soluble matter and electrical conductivity, where the liquid crystal composition contains compounds represented by general formulas (LC1) to (LC4) and the pigment has a water soluble matter of 0% to 1.5% by mass and electrical conductivity of 10 μS/cm to 150 μS/cm, preventing impurity migration and maintaining VHR and ID.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a color filter layer is disposed between the alignment film and the liquid crystal layer, then the color filter can provide color display function, but impurities in the color filter may migrate through the alignment film and transparent electrode to cause display defects
Solution Approach 1:
The patent changes the chemical composition parameters of the liquid crystal material by incorporating specific compounds (cyclic carbonate compounds and cyclic carboxylate compounds) with particular molecular structures. These compositional changes increase the liquid crystal's resistance to impurity migration from the color filter, thereby preventing display defects while maintaining color display functionality.
Solution Approach 2:
The patent uses a composite liquid crystal composition comprising multiple specific compounds (cyclic carbonate compounds, cyclic carboxylate compounds, and other liquid crystal compounds). This composite material approach creates synergistic effects that enhance the liquid crystal layer's stability and resistance to impurity contamination from the color filter layer.
2Ease of operation
If conventional liquid crystal materials are used, then the liquid crystal layer can function normally, but voltage holding ratio decreases and ion density increases due to impurity migration
Solution Approach 1:
The patent modifies the physical and chemical parameters of the liquid crystal material by selecting compounds with specific molecular weights, polar groups, and structural characteristics. These parameter changes result in improved voltage holding ratio and reduced ion density by preventing impurity migration from the color filter through the alignment film and transparent electrode.
3Speed
If the thickness of the alignment film and transparent electrode is reduced to improve response time, then the device response speed increases, but the isolation between color filter and liquid crystal layer becomes insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the liquid crystal material to compensate for the reduced physical barrier (thinner alignment film and transparent electrode). The modified liquid crystal composition has enhanced resistance to impurity migration, allowing the device to maintain reliability even with reduced thickness for faster response time.
Data Source
AI summary
The present invention relates to a liquid crystal display device that uses a particular liquid crystal composition and a color filter that uses a particular pigment.The present invention provides a liquid crystal display device that prevents a decrease in voltage holding ratio (VHR) and an increase in ion density (ID) of a liquid crystal layer and resolves the problems of display defects, such as missing dots, alignment variation, and ghosting.Since the liquid crystal display device of the present invention prevents a decrease in voltage holding ratio (VHR) and an increase in ion density (ID) of a liquid crystal layer and resolves the problems of display defects, such as ghosting, it is particularly useful for active matrix drive VA-mode and PSVA-mode liquid crystal display devices and can be applied to liquid crystal display devices such as liquid crystal televisions, monitors, cellular phones, and smart phones.