Bistable Liquid Crystal Modulator for Privacy and Solar Control
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Solution Overview
Problem
Existing liquid crystal light modulating technologies struggle to provide both privacy protection and dynamic modulation of light effectively, with issues such as slow switching times, high production costs, and limited control over solar radiation energy, particularly in glass doors and windows.
Innovation Solution
A liquid crystal light modulating device with a liquid crystal layer comprising nematic liquid crystal composition, chiral compounds, bimesogenic compounds, and dichroic dyes, allowing for stable states with varying molecular arrangements under different voltages, enabling rapid switching between transparent, tinted, and scattering states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional PDLC technology is used for privacy protection, then privacy protection is achieved, but clarity in transparent state is lost due to haze
Solution Approach 1:
The patent uses liquid crystal molecules that can change their orientation state in response to applied voltage, transitioning from a disordered state (scattering light for privacy) to an ordered state (transmitting light clearly). This parameter change in molecular arrangement enables dynamic switching between privacy protection and clear transparency without permanent haze.
Solution Approach 2:
The invention employs a composite liquid crystal composition containing multiple components including nematic liquid crystal compounds, chiral compounds, and bimesogenic compounds. This composite material system enables both privacy protection and clarity by combining the properties of different liquid crystal components that work synergistically to achieve rapid switching and stable states.
2Strength
If electrochromic devices are used for light modulation, then mechanical properties are excellent, but switching time is too slow (minutes to hours)
Solution Approach 1:
The patent replaces the slow electrochemical ion transport mechanism of electrochromic devices with a faster liquid crystal reorientation mechanism. Liquid crystal molecules can change their orientation almost instantaneously in response to electric fields, achieving switching times in the range of milliseconds rather than minutes or hours, while maintaining the solid-state mechanical advantages.
3Object-affected harmful factors
If suspended particle devices are used for light blocking, then light blocking state is achieved when power is off, but privacy protection state is not available when external ambient light is darker
Solution Approach 1:
The patent implements a dynamic liquid crystal system that can actively switch between different optical states (transparent, scattering, tinted) in response to user control and environmental conditions. Unlike static suspended particle devices, the liquid crystal system provides adaptable privacy protection that works effectively in various lighting conditions by actively adjusting the molecular arrangement to control light scattering and transmission.
4Device complexity
If conventional dye doped liquid crystal devices are used for light modulation, then a single device modulates only for a kind of polarized light, but dynamic modulation range and solar radiation energy control are narrower
Solution Approach 1:
The patent employs a specially designed liquid crystal composition with optimized molecular structures and additives that enable broad-spectrum light modulation. The composition parameters (molecular types, ratios, and additives) are tuned to achieve effective scattering and absorption across the entire solar spectrum, not just for a single polarization, thereby expanding the dynamic modulation range while maintaining single-device simplicity.
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 device achieves stable, rapid switching between clear and tinted states with low power consumption, providing effective privacy protection and solar radiation control, outperforming conventional technologies in transmittance contrast and energy efficiency.
Implementation Method 1
a liquid crystal layer between the first and second transparent conductive substrates, wherein the first transparent conductive substrate comprises a first transparent substrate and a first transparent conductive layer positioned adjacent to the liquid crystal layer, and the second transparent conductive substrate comprises a second transparent substrate and a second transparent conductive layer adjacent to the liquid crystal layer. The arrangement of liquid crystal molecules in the liquid crystal layer is varied depending on the voltage applied between the first conductive substrate and second conductive substrate
Implementation Method 2
The liquid crystal layer comprises a liquid crystal composition and dichroic dyes. The liquid crystal composition comprises a nematic liquid crystal composition, chiral compounds and bimesogenic compounds
Data Source
AI summary
A liquid crystal light modulating device includes substrates coated with a transparent conductive layer and a liquid crystal composition sandwiched between the substrates with a dichroic dye added; the resulting liquid crystal light modulating device can exist in at least two stable states that remain substantially stable after removal of a voltage. At least one of them is the liquid crystal molecules arranged in a substantially ordered manner, and at least one of them is the liquid crystal molecules arranged in a multi-domain and disordered manner; the applied voltage makes the arrangement of liquid crystal molecules can be quickly switched between the above stable states, and different liquid crystal molecule arrangements from the stable states can be obtained.