Nematic Liquid Crystal Composition for High-Speed Response and Stability
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Solution Overview
Problem
Liquid crystal display devices face challenges in maintaining high display quality and stability due to issues like ghosting and drop marks, particularly in large-size displays, where the one-drop-fill method leads to non-uniformity and contrast failures, and there is a need for a composition with positive dielectric anisotropy, low viscosity, and high resistivity.
Innovation Solution
A liquid crystal composition comprising specific compounds represented by formulas (26.2) and (2.5), along with other compounds from general formulas (IV), (L), and (I), which are optimized for low-temperature solubility, transition temperature, and electrical reliability, ensuring high dielectric anisotropy and low viscosity, thereby improving display performance and production yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the one-drop-fill method is used to inject liquid crystal composition into large-size substrates, then the injection process becomes simpler and faster, but display quality degrades due to drop marks and non-uniformity
Solution Approach 1:
The patent modifies the chemical composition parameters of the liquid crystal mixture, specifically incorporating compounds with particular molecular structures (cyclic compounds with specific ratios of 15-30% and compounds of formula (1) at 70-85%) to alter physical properties such as viscosity and surface tension, enabling stable dropping without degradation of display quality
Solution Approach 2:
The patent creates a composite liquid crystal composition by combining multiple compounds with different molecular structures and properties, including cyclic compounds, compounds of formula (1), and other liquid crystal compounds, to achieve a balanced formulation that maintains both injectability and display performance
2Quantity of substance
If the liquid crystal injection amount increases beyond the optimum value, then the substrate is fully filled, but display defects occur due to loss of balance between refractive index and driving electric field
Solution Approach 1:
The patent adjusts the refractive index parameter of the liquid crystal composition by selecting specific compounds with appropriate anisotropic properties, allowing optimization of the Δn×d product to match cell gap requirements while maintaining electrical characteristics for high-speed response
3Productivity
If liquid crystal composition is dropped repeatedly over a long period, then production volume increases, but dropping stability decreases due to sensitivity to impacts and pressure changes
Solution Approach 1:
The patent modifies the viscosity and surface tension parameters of the liquid crystal composition through careful selection of compounds with specific molecular structures, creating a formulation that resists impacts and pressure changes during repeated dropping operations while maintaining other required properties
Solution Approach 2:
The patent formulates a composite liquid crystal mixture combining compounds with complementary properties, where the synergistic interaction between different molecular structures provides both the required functional characteristics and enhanced stability against mechanical disturbances during production
4Speed
If liquid crystal compound with positive Δ∈ and —CF2O— structure is used to achieve high-speed response, then rotational viscosity decreases, but dielectric anisotropy control becomes more difficult
Solution Approach 1:
The patent combines liquid crystal compounds with positive dielectric anisotropy featuring —CF2O— structures (for high-speed response) with compounds having neutral dielectric anisotropy and alkenyl groups, creating a balanced composition that achieves both high response speed and controlled dielectric properties
Solution Approach 2:
The patent adjusts the ratio and molecular structure parameters of the constituent compounds to simultaneously optimize multiple parameters including dielectric anisotropy, refractive index anisotropy, and rotational viscosity, achieving a balanced formulation that meets multiple performance requirements
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 composition achieves high-speed response, stability under heat and light, and suppresses display failures like ghosting and drop marks, enabling high-yield production of liquid crystal display devices with improved quality.
Implementation Method 1
a liquid crystal composition having positive dielectric anisotropy (Δ∈) useful as a liquid crystal display material
Implementation Method 2
the nematic phase-isotropic liquid phase transition temperature (Tni) is required to be high
Data Source
AI summary
The inventor of the present invention has investigated various liquid crystal compounds and various chemical substances and found that the object can be achieved by using a combination of particular liquid crystal compounds, thereby making the present invention.In other words, provided are a liquid crystal composition having positive dielectric anisotropy, comprising compounds represented by formula (26.2) and formula (2.5) and one or more compounds represented by general formula (IV), an active matrix driving-liquid crystal display device using the liquid crystal composition, and a liquid crystal display using the active matrix-driving liquid crystal display device:(In the formula, R41 and R42 each independently represent an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 4 or 5 carbon atoms and X41 and X42 each independently represent a hydrogen atom or a fluorine atom.)