Solar-Control Glazing Unit with Multilayer Stack
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Solution Overview
Problem
Current solar protection glazing technologies fail to achieve a balance between optimal optical and thermal properties and manufacturing stability, often resulting in low selectivity and unstable tint reflections, which are sensitive to thickness variations and lack of transverse uniformity.
Innovation Solution
A transparent substrate with a multilayer solar control stack comprising three functional layers based on infrared radiation reflecting materials and four dielectric coatings, where the geometric thickness of each layer is carefully optimized to ensure stability and selectivity, with specific thickness ratios and materials like silicon nitride, zinc oxide, silver, and nickel-chromium oxide, to maintain optical and thermal performance during heat treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the glass sheet is heated to high temperature (above 560°C) for thermal toughening or bending treatment, then the mechanical resistance and shape adaptability are improved, but the functional layer based on silver deteriorates and loses its optical properties and infrared radiation reflection properties
Solution Approach 1:
A protective layer is deposited on the functional layer before heat treatment to prevent oxidation and deterioration of the silver-based functional layer during the thermal toughening or bending process. This preliminary protective action allows the glass to undergo high-temperature treatment while preserving the optical properties of the functional layer.
Solution Approach 2:
An intermediary protective layer is introduced between the functional layer and the oxidizing atmosphere during heat treatment. This intermediary layer acts as a barrier that prevents direct interaction between oxygen and the silver-based functional layer, thereby maintaining its infrared reflection properties while allowing the glass to be thermally treated.
2Reliability
If the functional layer based on silver is used to reflect infrared radiation, then the solar protection performance is improved, but the layer is sensitive to thickness variations and lacks transverse uniformity during manufacturing
Solution Approach 1:
The patent optimizes the thickness parameters of the functional layer and surrounding dielectric layers to create a design that is less sensitive to manufacturing variations. By carefully selecting specific thickness ranges and ratios, the system maintains stable optical properties even when minor thickness variations occur during deposition.
Solution Approach 2:
The patent uses composite structures combining silver-based functional layers with dielectric materials having specific refractive indices. This composite approach creates a system where the optical properties are determined by the combined effect of multiple layers, making the overall performance more robust against variations in individual layer thicknesses.
3Loss of energy
If the solar control stack is designed with high selectivity to reduce solar factor, then the thermal insulation performance is improved, but the light transmission is reduced
Solution Approach 1:
The patent applies the principle of local quality by designing the solar control stack to have different optical properties at different wavelength ranges. The functional layers are specifically optimized to reflect infrared radiation (thermal energy) while allowing visible light to pass through, achieving high selectivity where different parts of the electromagnetic spectrum are treated differently.
Solution Approach 2:
The patent utilizes optical interference effects in the dielectric layers to create wavelength-selective transmission and reflection. By controlling the thickness and refractive index of dielectric layers, the system can selectively reflect infrared wavelengths while transmitting visible wavelengths, effectively separating thermal and visual functions.
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 high selectivity, color stability, and aesthetic appeal, minimizing detrimental fluctuations in optical properties during industrial production, while allowing for heat treatment without compromising the stack's performance, thus achieving a balance between solar protection and manufacturing stability.
Implementation Method 1
functional layers that reflect infrared radiation, such as silver-based layers
Implementation Method 2
anti-reflective dielectric coatings which serve to reduce the light reflection
Implementation Method 3
thermal toughening of the glass sheet or sheets, to improve the resistance to mechanical stresses
Implementation Method 4
The quenching treatment then consists in suddenly cooling the surface of the vitreous sheet
Implementation Method 5
give a more or less complex curvature to the glass sheets for particular applications, using a bending operation at high temperature
Data Source
AI summary
The present invention relates to a substrate bearing a multilayer solar-control stack, and to a multiple glazing unit and a laminated glazing unit incorporating at least one such substrate bearing a solar-control stack. The multilayer stack comprises three functional layers of increasing thickness starting from the substrate, and four transparent dielectric coatings. The ratio of the optical thickness of the third dielectric coating to the optical thickness of the final dielectric coating is between 2 and 3.2, and the ratio of the optical thickness of the third dielectric coating to the optical thickness of the second dielectric coating is either between 0.6 and 0.91, or between 1.15 and 1.7. The invention is particularly applicable to the production of highly selective solar-control glazing units.