Polymerizable Compound for Fast LCD Response and High VHR
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Solution Overview
Problem
Conventional liquid crystal displays (LCDs) face challenges with narrow viewing angles and slow response times, particularly in TN mode LCDs, and high voltage holding ratio (VHR) degradation when exposed to energy such as ultraviolet rays.
Innovation Solution
A liquid crystal composition comprising 100 parts by mass of a nematic liquid crystal with negative dielectric anisotropy and 0.01 to 3 parts by mass of a polymerizable compound represented by a specific general formula, which is sandwiched between substrates and polymerized using energy rays to enhance response speed and maintain VHR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a liquid crystal material is given energy such as light or heat to polymerize, then the alignment direction of liquid crystal molecules can be controlled, but the compound deteriorates to cause reduction in voltage holding ratio
Solution Approach 1:
The patent changes the chemical parameters of the polymerizable compound by selecting specific compounds with (meth)acryloyl groups that have different polymerization reactivities and solubilities. This allows optimization of both alignment control and voltage holding ratio maintenance by choosing compounds that polymerize efficiently while maintaining compatibility with the liquid crystal composition
Solution Approach 2:
The patent creates a composite liquid crystal composition containing multiple components including nematic liquid crystal compounds with negative dielectric anisotropy and specific polymerizable compounds. This composite approach allows the system to achieve both good alignment properties through controlled polymerization and maintained voltage holding ratio through careful selection of compatible materials
2Device complexity
If conventional liquid crystal materials are used in TN mode LCDs, then the display structure is simple, but the viewing angle is narrow
Solution Approach 1:
The patent changes the dielectric anisotropy parameter from positive (conventional TN mode) to negative, enabling VA mode operation with perpendicular molecular alignment. This parameter change fundamentally improves viewing angle characteristics while maintaining a relatively simple display structure through the use of polymerizable compounds for alignment control
3Adaptability or versatility
If liquid crystal materials are used to improve viewing angle characteristics, then the viewing angle increases, but the response speed becomes slow
Solution Approach 1:
The patent optimizes the molecular parameters of the liquid crystal compounds and polymerizable additives to achieve fast response speeds while maintaining negative dielectric anisotropy for good viewing angle characteristics. The specific selection of compounds with appropriate molecular weights and structures enables both wide viewing angles and rapid response
Solution Approach 2:
The patent employs a composite liquid crystal composition combining multiple nematic liquid crystal compounds with negative dielectric anisotropy and specific polymerizable compounds. This composite formulation achieves synergistic effects that provide both wide viewing angles through VA mode operation and fast response speeds through optimized material properties and controlled polymerization
4Speed
If a polymerizable compound is added to liquid crystal composition, then the response speed increases, but the solubility and polymerization reactivity must be optimized
Solution Approach 1:
The patent optimizes the chemical parameters of the polymerizable compound by selecting specific compounds with (meth)acryloyl groups that have balanced solubility and polymerization reactivity. The molecular structure parameters are carefully chosen to ensure adequate solubility in the liquid crystal composition while maintaining high polymerization reactivity for efficient alignment control
Solution Approach 2:
The patent applies local quality optimization by selecting polymerizable compounds with specific functional groups and molecular structures that provide the desired balance of solubility and reactivity. The local chemical characteristics of the polymerizable compound are tailored to work optimally with the specific liquid crystal composition
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 achieves high-speed response and maintains a high voltage holding ratio, improving display performance and reliability, especially in VA mode LCDs, by using a polymerizable compound that enhances solubility and polymerization reactivity.
Implementation Method 1
irradiating the liquid crystal composition with energy rays, such as ultraviolet rays, to make the polymerizable compound represented by general formula (I) polymerize
Implementation Method 2
molecules of a liquid crystal material having negative dielectric anisotropy between two substrate are aligned perpendicular to the substrates and, with a voltage applied, the tilt direction of the liquid crystal directors are controlled
Implementation Method 3
liquid crystal displays (LCDs) utilizing optical (refractive index) anisotropy (Δn) and dielectric anisotropy (Δ∈) characteristic of liquid crystal compounds
Data Source
AI summary
A liquid crystal composition includes 100 parts by mass of a nematic liquid crystal composition having negative dielectric anisotropy and 0.01 to 3 parts by mass of a polymerizable compound of general formula (I). On being irradiated with an energy ray, such as UV rays, the liquid crystal composition provides an LCD capable of high-speed response without undergoing reduction in reliability (voltage holding ratio).In formula (I), rings C1-3 are benzene, cyclohexane or naphthalene; M1-2 are hydrogen or methyl; Z1 is a direct bond, -L1-, -L1O—, etc.; Z4 is a direct bond, -L2-, —OL2-, etc.; at least one of Z1 and Z4 is not a direct bond; L1,2 are C1-C10 alkylene; when Z1═Z4, one or more hydrogen atoms of the rings C1, C2, and C3 are substituted; Z2 and Z3 are each a direct bond, an ester bond, etc.; p and q are each 0 or 1, provided that p+q≧1.