Low-Emissivity Coating Resolves Color Shift at Acute Angles

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Solution Overview

Problem

Current glass coatings, such as triple silver coatings, suffer from color inconsistency when viewed at acute angles, leading to undesirable green or blue appearances, which affects the performance and aesthetic appeal of light transmissive substrates.

Innovation Solution

A coating comprising 7 to 20 discrete layers, including three reflective layers, an alloy layer of Ni, Cr, and Mo, and oxide layers, applied in a specific configuration to maintain infrared reflectivity while minimizing color shift at various viewing angles, is used to improve color control and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If triple silver coatings are used to increase infrared reflection, then infrared reflection is improved, but color inconsistency occurs when viewed at acute angles

Engineering Contradiction:
Improveinfrared reflectionVSAvoidcolor consistency
Core Design Contradiction:
Loss of energyVSStability of the object's composition

Solution Approach 1:

The coating is divided into multiple discrete layers (7-20 layers) with different materials and functions. Instead of using a simple triple silver structure, the patent segments the coating into reflective layers, oxide layers, and alloy layers, each contributing to different optical properties. This segmentation allows independent optimization of infrared reflection and color consistency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses composite material structures combining metals (silver, aluminum), metal oxides (zinc oxide, tin oxide), and alloys (Ni-Cr-Mo). These composite layers work together to achieve both high infrared reflection and consistent color appearance across different viewing angles, resolving the contradiction between energy reflection and visual stability.

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If multiple reflective metal layers are added to improve infrared reflection, then infrared reflection performance is enhanced, but coating complexity increases

Engineering Contradiction:
Improveinfrared reflectionVSAvoidcoating structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The coating is divided into multiple discrete layers (7-20 layers) with different materials and functions. Instead of using a simple triple silver structure, the patent segments the coating into reflective layers, oxide layers, and alloy layers, each contributing to different optical properties. This segmentation allows independent optimization of infrared reflection and color consistency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses composite material structures combining metals (silver, aluminum), metal oxides (zinc oxide, tin oxide), and alloys (Ni-Cr-Mo). These composite layers work together to achieve both high infrared reflection and consistent color appearance across different viewing angles, resolving the contradiction between energy reflection and visual stability.

Inventive Principle:
Principle #40Composite materials

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 reduces color inconsistency across different viewing angles, maintaining consistent color coordinate values from normal to acute angles, and provides improved solar heat gain and visible light transmission ratios, enhancing the usability of light transmissive substrates in various applications.

Implementation Method 1

The coatings generally have a high reflectance in the thermal infrared (IR) and a high transmittance in the visible spectrum. Thus, they are low-emissive of thermal infrared.

Methodology Applied
Scientific EffectInfrared reflection: Reflection

Implementation Method 2

The dielectric materials allow transmission of IR and visible light and control other properties and characteristics of the coating

Methodology Applied
Scientific EffectDielectric transmission: Dielectric

Implementation Method 3

The coating comprises a plurality of layers. In embodiments, the coating comprises at least seven (7) layers and as many as twenty (20) layers

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentEP3445732B1Coated glass surfaces and method for coating a glass substrate
Publication Date: 2021.06.09 APOGEE ENTERPRISES INC
  • EP3445732B1 patent drawingFigure 1
  • EP3445732B1 patent drawingFigure 2
  • EP3445732B1 patent drawingFigure 3

AI summary

A coated substrate having a coating and method of forming the same is disclosed, wherein the coating includes a plurality of discrete layers. The coating includes three reflective layers, an alloy layer disposed between two of the reflective layers, and two oxide layers and has a total thickness of 4000 Å or less.