Silver Dielectric Stack for Low Solar Factor Glazing
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Solution Overview
Problem
Current glazing materials fail to achieve a solar factor of less than 20% with a light transmission of around 40% while maintaining high selectivity and low exterior reflection, which is essential for regions with strong sunlight and energy efficiency.
Innovation Solution
A transparent substrate coated with a stack of thin layers comprising three functional silver layers and four dielectric coatings, where the thicknesses of the metal layers and dielectric coatings are optimized to achieve the desired optical properties, allowing for a solar factor of less than 20% and high selectivity, while maintaining sufficient light transmission and low exterior reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a stack comprising three functional silver-based layers is used to reduce solar factor, then solar protection is improved, but the solar factor remains above 20% which is too high for certain countries
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of each functional layer (first layer: 5-15 nm, second layer: 15-25 nm, third layer: 15-25 nm) and the optical thickness of each dielectric coating (M1: 80-140 nm, M2: 100-170 nm, M3: 120-240 nm, M4: 70-120 nm). This optimization of dimensional parameters enables the stack to achieve a solar factor below 20% while maintaining light transmission around 40%, resolving the contradiction between solar protection performance and actual solar factor values.
Solution Approach 2:
The patent uses a composite structure consisting of three functional silver-based layers alternating with four dielectric coatings. This composite material approach allows each layer to contribute specific properties: the silver layers provide solar reflection and the dielectric coatings provide optical interference effects. The combination achieves superior solar control with selectivity greater than 2.0, overcoming the limitation of single-material approaches that cannot simultaneously achieve low solar factor and high selectivity.
2Object-affected harmful factors
If the thicknesses of functional layers are increased to reduce solar factor, then solar control is improved, but light transmission decreases below acceptable levels
Solution Approach 1:
The patent optimizes the thickness parameters within specific ranges rather than simply increasing them. The first functional layer is kept thinner (5-15 nm) compared to the second and third layers (15-25 nm each), creating a non-uniform thickness distribution. The dielectric coatings are optimized with specific optical thicknesses (M1: 80-140 nm, M2: 100-170 nm, M3: 120-240 nm, M4: 70-120 nm) to create constructive interference for visible light transmission while maintaining solar reflection, achieving solar factor below 20% with light transmission around 40%.
Solution Approach 2:
The patent applies local quality by giving different thickness characteristics to different functional layers. The first functional layer has smaller thickness to allow more light transmission, while the second and third layers have larger thickness to enhance solar reflection. Each dielectric coating also has specifically optimized optical thickness to create local optical interference effects that favor visible light transmission while blocking solar energy, resolving the contradiction between solar control and light transmission.
3Object-affected harmful factors
If selectivity is increased to improve solar control, then solar factor is reduced, but exterior reflection increases affecting aesthetic appearance
Solution Approach 1:
The patent optimizes the optical thickness parameters of the dielectric coatings to control the wavelength-dependent interference effects. By carefully selecting the optical thickness of each dielectric layer (M1: 80-140 nm, M2: 100-170 nm, M3: 120-240 nm, M4: 70-120 nm), the stack achieves high selectivity (greater than 2.0) that preferentially reflects solar infrared radiation while allowing visible light transmission. This parameter optimization reduces exterior reflection in the visible range, maintaining aesthetic appearance while achieving solar factor below 20%.
4Object-affected harmful factors
If the stack complexity is increased to improve thermal performance, then solar control is enhanced, but manufacturing difficulty and cost increase
Solution Approach 1:
The patent maintains a fixed three-layer silver and four-layer dielectric structure, optimizing the parameters within specific ranges rather than increasing complexity. The thickness of each functional layer (first: 5-15 nm, second: 15-25 nm, third: 15-25 nm) and optical thickness of each dielectric coating are precisely controlled to achieve the desired performance. This parameter optimization approach within a fixed structural framework enhances thermal performance while avoiding the manufacturing complexity and cost increases associated with more complex multi-layer designs.
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 excellent solar control properties, maintaining energy efficiency and aesthetic appeal by achieving a solar factor of less than 20% with a selectivity greater than 2.0 and low exterior reflection, suitable for regions with high sunlight levels.
Implementation Method 1
a stack of thin layers comprising successively, starting from the substrate, an alternation of three functional metallic layers based on silver and four dielectric coatings
Implementation Method 2
functional metallic layers based on silver... capable of acting on solar radiation and/or infrared radiation
Implementation Method 3
to have low emissivity to reduce heat loss by infrared radiation from long wavelength
Data Source
Figure 1
AI summary
The invention relates to a material comprising a transparent substrate coated with a stack of thin layers comprising, starting at the substrate, three functional metallic silver-based layers and four dielectric coatings which are disposed alternately in such a way that every functional metallic layer is positioned between two dielectric coatings. The thicknesses of the three functional layers and the thicknesses of the dielectric coatings are selected such that they confer upon the materials a solar gain value lower than 20% for a light transmittance in the order of 40%.