Multistable Light Modulation via Phase Transition
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Solution Overview
Problem
Conventional switchable glazings, such as SPD and PDLC, require continuous electrical power to maintain transparency and have low operating reliability due to sudden darkening upon voltage failure, with switching times that are too long for many applications, especially in the automotive sector.
Innovation Solution
A planar light modulation apparatus with a dielectric material and particles that remain aligned at normal operating temperatures, allowing stable transmittance or opacity without electrical voltage, and can be rapidly switched by altering the particle alignment with temperature and electric field control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switchable glazings (SPD or PDLC) are used to achieve light transmission control, then transparency can be switched, but continuous electrical power is required to maintain transparency and operating reliability is low due to sudden darkening upon voltage failure
Solution Approach 1:
The patent changes the physical state of the dielectric material from liquid to solid by cooling it below its freezing point. This parameter change allows the suspended particles to become fixed in their random orientation, maintaining opacity without requiring continuous electrical power. The material transitions from a state requiring active control (liquid with applied voltage) to a passive stable state (solid with fixed particle arrangement), thereby improving reliability and eliminating continuous power consumption.
Solution Approach 2:
The patent utilizes the phase transition of the dielectric material from liquid to solid state. By cooling the material below its freezing point, the particles become immobilized in their random orientation, automatically maintaining the opaque state without electrical power. This phase transition creates a bistable system where the solid state represents a stable, power-free condition, resolving the contradiction between reliability and continuous power consumption.
2Productivity
If conventional switchable glazings (SPD or PDLC) are used to achieve light transmission control, then transparency can be switched, but switching times are too long for many applications
Solution Approach 1:
The patent changes the temperature parameter of the dielectric material to control switching speed. By heating the material above its freezing point, the particles gain mobility and can rapidly reorient themselves in response to applied electric fields. This parameter change enables fast switching between opaque and transparent states, improving productivity while minimizing time loss through thermal control of particle mobility.
3Stability of the object's composition
If particles are suspended in a liquid dielectric material, then rapid switching is possible, but the particles cannot maintain stable alignment without continuous electrical voltage
Solution Approach 1:
The patent employs phase transition of the dielectric material from liquid to solid to stabilize particle alignment. When cooled below the freezing point, the liquid medium solidifies and immobilizes the particles in their current orientation, maintaining stability without requiring continuous electrical voltage. This creates a power-free stable state that eliminates energy consumption while preserving alignment stability.
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
Achieves stable multistable transmittance and scattering properties without continuous electrical power, enhancing operating reliability and allowing rapid switching, suitable for applications like motor vehicles.
Implementation Method 1
a heating device configured to heat the dielectric material to a second temperature, which is higher than the first temperature
Implementation Method 2
the particles are enabled to alter an alignment thereof in the dielectric material based on Brownian motion
Implementation Method 3
transparent, electrically conductive coatings respectively disposed on mutually facing sides of the first and second substrates; electrical contacts for connecting the transparent, electrically conductive coatings to an electrical voltage source
Data Source
AI summary
A planar light modulation apparatus includes first and second planar, transparent substrates, each with a transparent, electrically conductive coating. The coatings are connectable to an electrical voltage source. A light modulation element in the space between the coatings includes a first dielectric material with a predefinable concentration of particles dispersed therein. While the particles are randomly arranged in the first dielectric material they render the light modulation element substantially nontransmissive for light impinging thereon or cause the light modulation element to appear opaque. Up to about 25° C. or higher and at atmospheric pressure, the first dielectric material is solid or has a viscosity that does not allow the particles to change their alignment based on Brownian motion. The material can be heated with a heating device to lower the viscosity and to allow the particles to alter their alignment in the first dielectric material on the basis of Brownian motion.