Liquid-Crystalline Medium for Low-Voltage Switching Elements
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Solution Overview
Problem
There is a need for liquid-crystalline media with improved chemical, physical, and electro-optical properties, particularly for use in switching elements and window elements, that can provide uniform scattering with low voltage and energy consumption, while maintaining reliability and stability against electrical breakdown and light exposure.
Innovation Solution
A liquid-crystalline medium comprising one or more mesogenic compounds of a specific formula, with a concentration of at least 15% by weight, which enhances optical anisotropy, voltage holding ratio, and clearing point, and includes chiral compounds for cholesteric liquid crystal devices, along with a polymeric component for improved stability and scattering efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid-crystalline media are used in switching elements, then the devices can operate, but they exhibit insufficient optical anisotropy and poor voltage holding ratio
Solution Approach 1:
The patent employs composite liquid-crystalline media comprising multiple mesogenic compounds with specific molecular structures (formulae I, II, III, IV) combined in optimized ratios. This composite approach allows synergistic enhancement of optical anisotropy and voltage holding ratio, as each compound contributes different properties that collectively improve device performance
Solution Approach 2:
The patent systematically varies compositional parameters (concentrations of different mesogens), structural parameters (molecular shapes and functional groups), and physical parameters (clearing points, viscosity) to optimize the balance between optical anisotropy and voltage holding ratio, achieving superior performance through parameter optimization
2Manufacturing precision
If scattering-type liquid crystal devices are used for privacy windows, then uniform scattering can be achieved, but energy consumption and operating voltage increase
Solution Approach 1:
The patent optimizes the liquid-crystalline medium composition to achieve uniform scattering at lower operating voltages by adjusting mesogen ratios, molecular structures, and physical parameters such as birefringence and viscosity, reducing the energy required for switching while maintaining scattering uniformity
Solution Approach 2:
The patent replaces high-voltage electrical switching mechanisms with optimized liquid-crystalline materials that achieve scattering transitions at lower voltages through enhanced optical anisotropy and improved electro-optical response characteristics
3Productivity
If switching elements operate at high voltage for efficient scattering, then scattering efficiency improves, but reliability against electrical breakdown decreases
Solution Approach 1:
The patent uses composite liquid-crystalline media with multiple mesogenic compounds that provide both high scattering efficiency and improved electrical stability, where the combination of different compounds enhances breakdown resistance while maintaining optical performance
Solution Approach 2:
The patent employs stable liquid-crystalline compositions that maintain their properties over extended operation, effectively creating long-lasting switching elements that resist electrical breakdown while delivering efficient scattering performance
4Temperature
If liquid-crystalline media with high clearing point are used, then thermal stability improves, but low-temperature performance and phase broadness worsen
Solution Approach 1:
The patent combines multiple mesogenic compounds with different clearing points and molecular structures to create a composite medium with broad liquid-crystalline phase range that maintains high thermal stability at elevated temperatures while ensuring proper phase behavior at low temperatures
Solution Approach 2:
The patent uses mesogenic compounds with specific local molecular structures and functional groups that contribute differently to thermal properties, allowing optimization of both high-temperature clearing point and low-temperature phase stability through selective component inclusion
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 medium achieves high optical anisotropy, favorable voltage holding ratio, and long-term light stability, enabling efficient and uniform scattering in switching elements, particularly in cholesteric liquid crystal devices, with reduced energy consumption and enhanced reliability.
Implementation Method 1
The objects are solved by the subject-matter defined in the independent claims, while preferred embodiments are set forth in the respective dependent claims and are further described below. The present invention in particular provides the following items including main aspects, preferred embodiments and particular features
Implementation Method 2
LC-based light shutters using light scattering include so-called polymer dispersed liquid crystal (PDLC), polymer network liquid crystal (PNLC) and cholesteric liquid crystal (CLC) devices. These scattering-type devices can be switched between transparent and translucent states.
Implementation Method 3
LC-based light shutters using light scattering include so-called polymer dispersed liquid crystal (PDLC), polymer network liquid crystal (PNLC) and cholesteric liquid crystal (CLC) devices.
Data Source
AI summary
The present invention relates to liquid-crystalline media comprising one or more mesogenic compounds of formula I as set forth hereinafter, wherein the one or more compounds of formula I are contained in the medium in an amount, based on the overall contents of the medium, of at least 15% by weight. The present invention further relates to a switching layer, a switching element and a window element containing the liquid-crystalline medium.