Multilayer Silver Coating for Neutral Color and Thermal Performance

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Solution Overview

Problem

Functionalized glass surfaces struggle to achieve a balance between high thermal performance and aesthetic appearance, as increasing the thickness of metallic functional layers enhances external reflection but reduces light transmission and selectivity, leading to poor thermal performance and non-neutral color.

Innovation Solution

A stack of layers comprising three silver-based metallic functional layers and four dielectric sets, with specific thickness ratios and optical thicknesses, is deposited on a transparent substrate, optimizing physical and optical thicknesses to achieve high external reflection, light transmission, and selectivity while maintaining a neutral color.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the thickness of metallic functional layers is increased, then external reflection is enhanced, but light transmission is reduced and selectivity decreases

Engineering Contradiction:
Improveexternal reflectionVSAvoidselectivity
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent divides the single metallic functional layer into three separate silver-based metallic functional layers (F1, F2, F3) with different thicknesses. This segmentation allows each layer to contribute differently to the overall optical properties, enabling simultaneous optimization of external reflection, light transmission, and selectivity that cannot be achieved with a single thick layer.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each metallic functional layer is assigned a specific local thickness (EF1, EF2, EF3) tailored to its position in the stack. The first layer (F1) has thickness EF1, the second layer (F2) has thickness EF2, and the third layer (F3) has thickness EF3, where these thicknesses are specifically optimized to achieve the desired balance between reflection, transmission, and selectivity.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If the thickness of metallic functional layers is increased, then external reflection is enhanced, but thermal performance deteriorates

Engineering Contradiction:
Improveexternal reflectionVSAvoidthermal performance
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The segmentation of the metallic functional layers into three distinct layers with specific thicknesses allows for optimized thermal performance. The distributed structure of multiple thinner layers compared to one thick layer creates different optical interference patterns that reduce heat transmission while maintaining aesthetic reflection properties.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a composite structure by combining three silver-based metallic functional layers with four dielectric sets of layers. This composite material system leverages the complementary properties of metals (high reflectivity) and dielectrics (optical interference control) to achieve both aesthetic appearance and thermal performance.

Inventive Principle:
Principle #40Composite materials

3Illumination intensity

If the thickness of metallic functional layers is increased, then external reflection is enhanced, but aesthetic appearance deteriorates

Engineering Contradiction:
Improveexternal reflectionVSAvoidcolor neutrality
Core Design Contradiction:
Illumination intensityVSShape

Solution Approach 1:

Dividing the metallic functional layer into three segments with different thicknesses (EF1, EF2, EF3) allows each segment to contribute to different aspects of the optical response. This segmentation enables the stack to maintain neutral color appearance while achieving the desired level of external reflection, avoiding the color distortion that occurs with single thick metallic layers.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent optimizes specific parameters including the thicknesses of metallic layers (EF1, EF2, EF3) and dielectric layers (EO1, EO2, EO3, EO4), as well as the ratio EF1/EF2 between 0.95 and 1.05. By precisely controlling these parameters, the system achieves neutral color appearance with high external reflection, transforming the optical characteristics to meet aesthetic requirements.

Inventive Principle:
Principle #35Parameter changes

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 achieves an external light reflection of at least 25%, light transmission of at least 48%, a solar factor of at least 25, and a selectivity of at least 1.8, providing both high thermal performance and an aesthetically pleasing neutral color in external reflection.

Implementation Method 1

The functionalized glass surfaces and the glazing that includes them ideally have functions such as: the light transmission is the highest, at least 45%, or even 50%; the solar factor, g, of at most 30%; the selectivity, s, is equal to or greater than 1.5, or even 1.7.

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

A stack of layers comprising three silver-based metallic functional layers and four dielectric sets, with specific thickness ratios and optical thicknesses, is deposited on a transparent substrate, optimizing physical and optical thicknesses to achieve high external reflection, light transmission, and selectivity while maintaining a neutral color.

Methodology Applied
Scientific EffectOptical interference: Interference

Data Source

PatentEP3807225B1Material comprising a stack with thermal and aesthetic properties
Publication Date: 2022.08.10 SAINT GOBAIN VITRAGE SA
  • EP3807225B1 patent drawingFigure 1
  • EP3807225B1 patent drawingFigure 2
  • EP3807225B1 patent drawingFigure 3

AI summary

The invention relates to a material comprising a transparent substrate, on the surface of which a stack of layers is deposited which comprises a plurality of functional layers making it possible to act on the solar and/or infrared radiation likely to strike said surface. The material of the invention has a high thermal performance and, aesthetically, a neutral-color glossy surface appearance.