Switchable Window Light Regulation Using Thermal-Electrical LC Switching
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Solution Overview
Problem
Existing switchable windows face challenges in achieving uniform and efficient light regulation due to temperature gradients and non-uniform thermal switching, leading to aesthetic issues and reduced effectiveness.
Innovation Solution
A switchable window element with a liquid-crystalline medium having a clearing point within its working temperature range, enabling both thermal and electrical switching, where electrical switching complements thermal switching to ensure uniformity and efficiency, using a single switchable layer with dichroic dyes and electrodes on opposing substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermal switching alone is used, then the device can operate without additional control systems, but the switching uniformity and efficiency deteriorate due to temperature gradients
Solution Approach 1:
The patent combines thermal switching and electrical switching mechanisms into a single window element system. The liquid-crystalline medium responds to both temperature changes and electric fields, allowing the device to leverage both thermal diffusion (for simplicity) and electrical control (for uniformity), thereby resolving the contradiction between ease of operation and switching uniformity
Solution Approach 2:
The patent utilizes the clearing point temperature parameter of the liquid-crystalline medium as a critical threshold. By designing the system so that thermal diffusion naturally brings the medium close to its clearing point, and then using electrical switching to trigger the phase transition, the system achieves efficient and uniform switching while maintaining operational simplicity
2Device complexity
If a single switchable layer is used, then the device complexity is reduced, but achieving uniform switching across the window area becomes more difficult
Solution Approach 1:
The patent exploits the phase transition of the liquid-crystalline medium at its clearing point. The transition from nematic to isotropic phase creates a sharp, uniform optical change across the entire window area. This phase transition mechanism allows a single layer to achieve uniform switching without requiring multiple layers or complex structures
Solution Approach 2:
The patent replaces complex multi-layer mechanical structures with a single layer that utilizes electromagnetic field interactions. The liquid-crystalline medium's response to electric fields and thermal energy substitutes for what would otherwise require multiple mechanical switching layers, reducing device complexity while maintaining switching uniformity
3Productivity
If the clearing point is set within the working temperature range, then switching efficiency is improved, but the device may exhibit non-uniform optical states at varying temperatures
Solution Approach 1:
The patent implements a control system that monitors the optical state and temperature of the window element. Based on this feedback, the controller adjusts the electrical switching signals to compensate for temperature variations. This feedback mechanism ensures that the window maintains uniform optical states across different operating temperatures while preserving high switching efficiency
Solution Approach 2:
The patent dynamically adjusts the electrical field parameters (voltage, pulse duration) based on the operating temperature. When the temperature is below the clearing point, stronger or longer electrical pulses are applied to ensure complete phase transition. This dynamic parameter adjustment compensates for temperature variations and maintains optical state uniformity while preserving switching efficiency
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 solution provides reliable, uniform, and energy-efficient light regulation with high contrast between states, allowing rapid transitions and addressing non-uniformity issues, suitable for various applications including buildings and vehicles.
Implementation Method 1
Based in principle on a change in phase and optical state by changing the temperature across a phase transition temperature, in particular the clearing point and especially the nematic-isotropic phase transition temperature
Implementation Method 2
liquid crystal-based devices may adopt the different optical states using electrical switching, where the application of voltage controls the switching. Such liquid crystal-based devices in principle employ a change in the orientation of liquid crystal (LC) molecules between two conductive electrodes by applying an electric field which results in a change of the transmittance
Data Source
AI summary
A polymerizable LC material containing one or more reactive mesogenic compounds, one or more chiral compounds and one or more compounds of formula I,wherein the individual radicals have one of the meaning as defied herein, is suitable for use in in optical, electro-optical, decorative or security devices. Polymer films with improved thermal and UV stability are obtainable from the polymerizable LC material.