Glazing with Reflective Stack for Projection Image Contrast
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Solution Overview
Problem
Electrically controllable glazing systems with variable optical properties, such as liquid crystal and optical valve systems, are inadequate for projection applications when spectators are on the side of the projector, as they fail to provide sufficient image intensity and contrast in the scattering state while maintaining transparency.
Innovation Solution
A glazing with electrically controllable optical transmission properties, featuring a stack of thin layers with a metallic functional layer and a high optical index dielectric coating, exhibiting three reflection peaks at visible wavelengths, ensuring a light transmission of at least 60% and maintaining color neutrality in both transparent and diffusing states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If electrically controllable glazing systems (liquid crystal or optical valve) are used for projection, then the system can switch between transparent and scattering states, but the image intensity and contrast are insufficient when spectators are on the side of the projector
Solution Approach 1:
The patent introduces a reflective dimension by adding a stack of reflective and transparent layers behind the active system. This creates a cavity that reflects light back through the active system, effectively adding a return path for light that enhances image intensity and contrast for front-viewing spectators while maintaining the transparent/scattering switching capability
Solution Approach 2:
The patent nests multiple functional layers within the glazing structure: the active system (liquid crystal or optical valve) is positioned between glass sheets, with a stack of reflective and transparent layers nested behind it. This nested configuration allows the light to pass through multiple functional layers, be reflected, and return through the active system, enhancing projection quality without compromising the switching function
2Reliability
If the glazing is made more reflective to improve projection image quality, then image contrast improves, but the light transmission in transparent state decreases
Solution Approach 1:
The patent makes the glazing dynamically controllable by using an electrically switchable active system that can transition between transparent and scattering states. When in the transparent state, light passes through with minimal interference; when in the scattering state, the same structure provides enhanced reflection for projection. This dynamic switching allows the system to adapt its optical properties based on the viewing mode, maintaining high light transmission in transparent state while providing high contrast in projection mode
Solution Approach 2:
The patent changes the optical parameters of the glazing by using an active system that can alter its transmission and scattering properties electrically. The active system's ability to change its optical state allows the glazing to provide high light transmission when transparent and high image contrast when in scattering state for projection, resolving the contradiction between these two requirements
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 effective projection with good image quality and contrast in the diffusing state without compromising the transparent functionality, achieving light transmission of at least 60% and color neutrality in the transparent state.
Implementation Method 1
a coating of dielectric material of high optical index and of sufficient optical thickness for the glazing to exhibit three reflection peaks at three visible wavelengths
Implementation Method 2
a stack of thin layers transparent and reflective comprising: a metallic functional layer; and a coating of dielectric material of high optical index
Implementation Method 3
The liquid crystals, when the film is put under tension, are oriented along a privileged axis, which allows vision
Implementation Method 4
liquid crystal droplets, in particular nematics with positive dielectric anisotropy
Implementation Method 5
microdroplets containing particles capable of being placed in a preferred direction under the action of an electric or magnetic field
Implementation Method 6
particles capable of being placed in a preferred direction under the action of an electric or magnetic field
Implementation Method 7
electrically controllable systems with variable optical properties, and more specifically systems of the glazing type whose light diffusion can be modified under the effect of an appropriate electrical power supply
Data Source
Figure 1A~1D
Figure 2~3
AI summary
A glazing having electrically controllable optical transmission properties having, in at least one electrically controllable state, a light transmission TL greater than or equal to 60%, the glazing comprising: - two sheets having a glass function (2A, 2B); and - between the two sheets having a glass function, an active system (4) having electrically controllable optical transmission properties, in which the glazing further comprises a transparent and reflective stack of thin layers (6) comprising: - a functional metal layer; and - a coating made from a dielectric material with a high optical index and a sufficient optical thickness for the glazing to have three reflection peaks at three visible wavelengths.