Cholesteric Liquid Crystal Windows With Three Stable Optical States
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Solution Overview
Problem
Bistable cholesteric liquid crystal windows lack the ability to switch between three or more stable states without the application of a driving voltage, which is energy inefficient, and there is a need for improved energy efficiency and optical effectiveness.
Innovation Solution
A liquid crystal window comprising at least one cholesteric liquid crystal layer with at least three stable states, including a planar, focal conic, and grayscale state, achieved without applied voltage, and switching methods using voltage pulses with varying RMS voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a driving voltage is applied to switch the cholesteric liquid crystal into an intermediate or grayscale state, then the optical effectiveness is improved, but the energy efficiency deteriorates
Solution Approach 1:
The liquid crystal window transitions from a static bistable system to a dynamic multistable system where the liquid crystal molecules can be switched between multiple stable orientations (planar, focal conic, and intermediate grayscale states) through controlled voltage pulses. The dynamic switching capability allows the system to achieve different optical states while maintaining stability without continuous power consumption.
Solution Approach 2:
The invention changes the physical parameters of the cholesteric liquid crystal system by introducing specific helical pitch values and molecular orientations that enable multiple stable states. By controlling the helical pitch and molecular alignment through voltage pulses, the system achieves distinct stable states with different light transmittance properties without requiring continuous energy input.
2Adaptability or versatility
If the cholesteric liquid crystal window is designed with only two stable states, then the device complexity is reduced, but the adaptability deteriorates
Solution Approach 1:
The invention exploits changes in the helical pitch parameter of the cholesteric liquid crystal to create multiple stable states. By controlling the molecular orientation and pitch through voltage application, the system achieves planar, focal conic, and intermediate grayscale states without adding complex mechanical or electronic components.
Solution Approach 2:
The system introduces dynamic switching capability between multiple stable states through voltage pulse control. The liquid crystal molecules can be temporarily reoriented during switching and then stabilize in different configurations, enabling versatile optical control while maintaining inherent stability in each state without continuous power consumption.
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
Enables multiple stable states with varying light transmittance and haze levels, enhancing energy efficiency and optical effectiveness by eliminating the need for continuous power application.
Implementation Method 1
a cholesteric liquid crystal layer disposed between the first and second glass substrates and in electrical contact with the electrode pair, wherein the cholesteric liquid crystal layer comprises at least three stable states
Implementation Method 2
The window can be switched from the first stable state to the second stable state and vice versa via a voltage pulse
Implementation Method 3
The second stable state is a focal conic state that is opaque for visible light
Implementation Method 4
The first stable state is a planar state that can be transparent or reflective for visible light
Data Source
AI summary
Disclosed are liquid crystal devices including at least one cholesteric liquid crystal layer and having multiple stable states. Also disclosed are liquid crystal windows having at least three stable states in the absence of voltage.