Dibenzofuran Derivatives for Liquid Crystal Viewing Angle
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Solution Overview
Problem
Existing liquid-crystal displays face challenges with strong viewing-angle dependence, requiring improvements in dielectric anisotropy and molecular orientation to enhance imaging quality and comfort.
Innovation Solution
Development of dibenzofuran and dibenzothiophene derivatives with specific substitution patterns that exhibit neutral to positive dielectric anisotropy, allowing for improved molecular orientation and reduced viewing-angle dependence in liquid-crystal displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid crystals with larger dipole moment parallel to longitudinal axis are used, then dielectric anisotropy is improved, but viewing-angle dependence increases
Solution Approach 1:
The patent changes the dielectric parameter by introducing compounds with negative dielectric anisotropy (Δε < 0), specifically targeting ε∥ < ε⊥. This parameter inversion allows the liquid crystal molecules to orient perpendicular to the substrate in the field-free state, fundamentally altering the viewing-angle characteristics while maintaining adequate dielectric response.
Solution Approach 2:
The patent inverts the conventional approach by using liquid crystals where the dielectric constant perpendicular to the director (ε⊥) is larger than parallel to it (ε∥), rather than the traditional ε∥ > ε⊥. This inversion enables vertical alignment and improves viewing angles, directly addressing the contradiction between dielectric anisotropy and viewing-angle dependence.
2Speed
If mixtures of 5 to 20 components are used, then response time is reduced, but device complexity increases
Solution Approach 1:
The patent focuses on optimizing the dielectric parameter (Δε) and clearing point (Tcp) through careful selection of molecular structures and substituents. By targeting specific parameter ranges (Δε between -5 and +5, Tcp between 50°C and 150°C), the invention achieves good display performance with simpler mixtures, reducing the need for complex 5-20 component formulations.
3Temperature
If clearing point is increased, then temperature range is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent establishes a target clearing point range of 50°C to 150°C that balances temperature performance with manufacturability. This parameter optimization allows sufficient temperature operating range while avoiding the difficulties associated with high-clearing-point materials, such as processing challenges and compatibility issues with standard display components.
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 compounds achieve high clearing points, large positive dielectric constants perpendicular to the field director, and good compatibility with conventional substances, leading to improved brightness, transmission, and low response times in liquid-crystal displays.
Implementation Method 1
the dielectric constant ε of the liquid-crystalline medium has different values for the two orientations. Substances whose dielectric constant is larger when the longitudinal axes of the molecules are oriented perpendicular to the capacitor plates than when they are oriented parallel are known as being dielectrically positive
Implementation Method 2
Of particular importance for use in liquid-crystal displays are the optical, dielectric and elasto-mechanical anisotropies
Implementation Method 3
This alignment layer serves to bring the longitudinal axes of the adjacent crystalline molecules into a preferential direction through surface forces
Data Source
AI summary
Compounds of the general formula (I) in which the occurring groups and parameters have the meanings indicated in claim 1, to the use thereof in liquid-crystalline or mesogenic media and to liquid-crystalline media comprising these derivatives. It can be used in liquid crystal displays of the FFS type and other applications. The compounds are helpful for energy-saving displays.