Low-Emissivity Coating with Dielectric Layers for Window Transmittance
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Solution Overview
Problem
Low-emissivity glass coatings face a challenge in maintaining high visible light transmittance while achieving the necessary thickness for reduced emissivity, which typically results in decreased lighting properties.
Innovation Solution
A low-emissivity coating structure comprising a first dielectric layer with a high-refractive metal oxide, a low-emissivity layer, and a second dielectric layer with silicon aluminum nitride, along with deposition auxiliary layers, is used to enhance visible light transmittance and durability, maintaining low emissivity and neutral color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the low-emissivity layer is increased in thickness to decrease emissivity, then emissivity is reduced, but visible light transmittance is decreased
Solution Approach 1:
The patent employs a composite low-emissivity coating structure consisting of multiple dielectric layers with different refractive indices (first dielectric layer with refractive index 1.8-2.2, second dielectric layer with refractive index 2.4-2.8, and third dielectric layer with refractive index 1.8-2.2) stacked on both sides of the low-emissivity layer. This composite structure optimizes optical interference to maintain high visible light transmittance while preserving low emissivity performance.
Solution Approach 2:
The patent optimizes specific parameter ranges including the thickness of each dielectric layer (first dielectric layer: 50-150 nm, second dielectric layer: 20-80 nm, third dielectric layer: 50-150 nm), refractive indices of materials, and the thickness of the low-emissivity layer (5-25 nm) to achieve the balance between visible light transmittance and emissivity reduction.
2Loss of energy
If the low-emissivity layer is increased in thickness to decrease emissivity, then emissivity is reduced, but lighting property is decreased
Solution Approach 1:
The patent employs a composite low-emissivity coating structure consisting of multiple dielectric layers with different refractive indices (first dielectric layer with refractive index 1.8-2.2, second dielectric layer with refractive index 2.4-2.8, and third dielectric layer with refractive index 1.8-2.2) stacked on both sides of the low-emissivity layer. This composite structure optimizes optical interference to maintain high visible light transmittance while preserving low emissivity performance.
Solution Approach 2:
The patent optimizes specific parameter ranges including the thickness of each dielectric layer (first dielectric layer: 50-150 nm, second dielectric layer: 20-80 nm, third dielectric layer: 50-150 nm), refractive indices of materials, and the thickness of the low-emissivity layer (5-25 nm) to achieve the balance between visible light transmittance and emissivity reduction.
3Reliability
If dielectric layers are added to prevent oxidation, then oxidation resistance is improved, but coating complexity is increased
Solution Approach 1:
The patent employs a composite low-emissivity coating structure consisting of multiple dielectric layers with different refractive indices (first dielectric layer with refractive index 1.8-2.2, second dielectric layer with refractive index 2.4-2.8, and third dielectric layer with refractive index 1.8-2.2) stacked on both sides of the low-emissivity layer. This composite structure optimizes optical interference to maintain high visible light transmittance while preserving low emissivity performance.
Solution Approach 2:
The patent optimizes specific parameter ranges including the thickness of each dielectric layer (first dielectric layer: 50-150 nm, second dielectric layer: 20-80 nm, third dielectric layer: 50-150 nm), refractive indices of materials, and the thickness of the low-emissivity layer (5-25 nm) to achieve the balance between visible light transmittance and emissivity reduction.
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 coating achieves excellent visible light transmittance and neutral color while maintaining low emissivity, improving insulation and lighting properties without excessive thickness, and enhancing durability through controlled refractive index and layer thickness ratios.
Implementation Method 1
each of the first metal oxide and the second metal oxide has a refractive index in the range of about 2.2 to about 2.6 with regard to a wavelength of about 550 nm
Implementation Method 2
The low-emissivity glass is a functional material having an energy saving effect of a building structure by reflecting radiant rays in the infrared region to block outdoor solar radiant heat in summer and to preserve indoor heating radiant heat
Implementation Method 3
Silver (Ag) used for the low-emissivity layer is oxidized when being exposed in the air, such that dielectric layers are deposited as oxidation prevention layers on an upper part and a lower part of the low-emissivity layer
Data Source
AI summary
Provided is a low-emissivity coating comprising successively: a first dielectric layer comprising a first metal oxide; a low-emissivity layer; and a second dielectric layer having first and second layers stacked on each other, the first layer comprising a second metal oxide, and the second layer comprising a silicon aluminum nitride, wherein each of the first and second metal oxides has a refractive index ranging from about 2.2 to about 2.6 with regard to a wavelength of about 550 nm.