Smart Window Liquid Crystal Switching for Energy-Efficient Light Control
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Solution Overview
Problem
Conventional smart windows are limited in functionality, unable to switch effectively between light transmission, heat insulation, and privacy protection, and require continuous voltage to maintain switched states, leading to energy inefficiency and increased production costs.
Innovation Solution
A smart window with two transparent substrates and a liquid crystal layer containing nematic liquid crystals and photochromic dye, which can switch between transparent and scattering states using pulse voltages and light illumination, allowing for multi-functional control of light transmittance and heat insulation without continuous voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional smart windows use electrochromic technology or suspended particle devices to adjust light transmittance, then heat insulation effect is achieved, but the window can only switch between light transmission state and light absorption state, resulting in limited functions
Solution Approach 1:
The patent combines multiple functional materials (nematic liquid crystal, cholesteric liquid crystal, and photochromic dye) into a single liquid crystal layer, enabling the window to simultaneously achieve light transmission control, heat insulation, and privacy protection functions without requiring separate layers for each function.
Solution Approach 2:
The invention uses a composite liquid crystal material system comprising nematic liquid crystal molecules for light scattering control, cholesteric liquid crystal molecules for structural phase transitions, and photochromic dye molecules for light absorption, creating a multi-functional material that resolves the contradiction between functional versatility and structural complexity.
2Adaptability or versatility
If conventional smart windows use liquid crystal materials to adjust light scattering for ground glass effect, then privacy protection is achieved, but the window can only switch between light transmission state and light scattering state, reducing consumer interest
Solution Approach 1:
The patent merges light scattering control (via nematic liquid crystal), light absorption (via photochromic dye), and heat insulation functions into a single integrated liquid crystal layer, allowing the window to achieve multiple states including transparent, scattering, and absorbing states without requiring separate functional layers.
Solution Approach 2:
The liquid crystal layer serves multiple functions simultaneously: it controls light transmission, provides heat insulation through selective wavelength absorption, and enables privacy protection through scattering effects, making one component perform multiple roles that previously required separate systems.
3Ease of operation
If conventional smart windows use thermochromic or photochromic technology to adjust light transmittance, then automatic light control is achieved, but the window lacks active switching capability between multiple states
Solution Approach 1:
The patent applies dynamic control by using voltage-responsive liquid crystal phase transitions to actively switch between different optical states (transparent, scattering, absorbing). The liquid crystal molecules can be dynamically reoriented by applying voltage, enabling rapid and reversible switching between multiple functional states rather than passive response to environmental conditions.
Solution Approach 2:
The invention uses periodic voltage application to control the liquid crystal phase transitions, where alternating voltage cycles switch the liquid crystal between different orientations and optical states, enabling rhythmic switching between transparent and scattering modes for active privacy control.
4Use of energy by moving object
If smart window states are maintained without continuous voltage supply, then energy saving is achieved, but the switching speed may be affected
Solution Approach 1:
The patent employs periodic voltage pulses to switch the liquid crystal between states, where brief voltage applications trigger rapid phase transitions. The liquid crystal maintains its switched state without continuous voltage due to the stability of the reoriented molecular configuration, enabling energy-efficient holding of states while achieving fast switching during transition periods.
Solution Approach 2:
The invention exploits phase transitions of liquid crystal molecules between different orientational states (nematic to cholesteric phases) that can be rapidly induced by voltage and then maintained stably without continuous energy input, as the reoriented molecular structure remains in a metastable state that preserves the optical properties without requiring ongoing power supply.
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 smart window achieves efficient switching between light transmission, heat insulation, and privacy protection, with high transmittance and dichroic absorption, maintaining states stably without continuous power, reducing production complexity and energy consumption.
Implementation Method 1
The liquid crystal material has a pitch of at most 250 nanometers or at least 500 nanometers. The liquid crystal material includes a nematic liquid crystal, a rotatory molecule, and a photochromic dye mixed with each other. The liquid crystal material changes a transmittance corresponding to a specific light wavelength range when receiving a light.
Implementation Method 2
the smart window hardly absorbing the visible light while not being irradiated by light and having dichroic absorption effect while being irradiated by light
Implementation Method 3
The liquid crystal material is switched between a planar texture and a focal-conic texture respectively according to the first pulse voltage and the second pulse voltage
Data Source
AI summary
A smart window includes two transparent substrates and a liquid crystal layer. The two transparent substrates are opposite to each other and are electrically connected to a voltage supply. A first pulse voltage or a second pulse voltage is provided between the two transparent substrates by the voltage supply. The liquid crystal layer is located between the two transparent substrates and has a liquid crystal material. The liquid crystal material has a pitch of at most 250 nanometers or at least 500 nanometers. The liquid crystal material includes a nematic liquid crystal, a rotatory molecule, and a photochromic dye mixed with each other. The liquid crystal material changes a transmittance corresponding to a specific light wavelength range when receiving a light. The liquid crystal material is switched between a planar texture and a focal-conic texture respectively according to the first pulse voltage and the second pulse voltage.