Blue Low-E Coated Glass with Optimized Dielectric Thickness
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Solution Overview
Problem
Existing coated glass articles, such as those with the glass/SiN/NiCr/Ag/NiCr/SiN structure, do not effectively achieve a strong blue glass side reflective color while maintaining desired solar characteristics, with prior coatings only achieving color values that are not blue enough for certain applications.
Innovation Solution
Adjusting the thicknesses of the layers in the coating, specifically thickening the bottom silicon nitride layer and optionally the top silicon nitride layer, to achieve glass side reflective color values of about -15 to -25 for b* and about -4 to +4 for a*, while maintaining good solar control characteristics like low sheet resistance and emissivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If standard thicknesses of SiN/NiCr/Ag/NiCr/SiN layers are used, then good solar control characteristics are achieved, but the glass side reflective color is not blue enough
Solution Approach 1:
The patent changes the thickness parameters of the dielectric layers to achieve the desired optical effect. Specifically, the bottom dielectric layer is thickened to 80-110 nm and the top dielectric layer to 50-70 nm, which modifies the optical interference conditions to produce stronger blue coloration while preserving solar control properties.
Solution Approach 2:
The patent uses a composite multilayer structure combining metal layers (NiCr, Ag) with dielectric layers (SiN, SiO2) in specific thickness ratios. This composite structure enables simultaneous achievement of solar control characteristics and enhanced blue reflective color through optical interference effects between the layers.
2Illumination intensity
If the bottom dielectric layer is thickened to increase blue coloration, then glass side reflective b* color value improves, but manufacturing complexity increases
Solution Approach 1:
The patent modifies specific thickness parameters within defined ranges (bottom dielectric: 80-110 nm, top dielectric: 50-70 nm) to achieve the desired blue coloration. These parameter changes are implemented within the existing coating process framework, avoiding fundamental structural changes while achieving the optical enhancement goal.
3Illumination intensity
If layer thicknesses are adjusted to achieve strong blue color, then color characteristics improve, but solar control characteristics may deteriorate
Solution Approach 1:
The patent employs a composite multilayer structure where metal layers (NiCr, Ag) provide solar control functionality through their inherent optical and electrical properties, while dielectric layers (SiN, SiO2) tuned to specific thicknesses provide optical interference for blue coloration. This composite approach allows independent optimization of solar control and color characteristics.
Solution Approach 2:
The patent applies different thickness values to different dielectric layers within the same coating structure. The bottom dielectric layer is thicker (80-110 nm) to enhance blue coloration, while the top dielectric layer is thinner (50-70 nm) to maintain solar control performance. This local differentiation of layer qualities enables simultaneous achievement of both goals.
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 adjusted layer thicknesses enable the realization of a strong blue glass side reflective color in combination with excellent solar control characteristics, including low emissivity and sheet resistance, both before and after heat treatment.
Implementation Method 1
a multiple layer coating on a surface of the glass substrate, the coating comprising at least the following layers from the glass substrate outwardly: a first layer comprising silicon nitride; a first contact layer comprising Ni and/or Cr; an infrared (IR) reflecting layer comprising silver located over and directly contacting the first contact layer comprising Ni and/or Cr; a second contact layer comprising Ni and/or Cr located over and directly contacting the IR reflecting layer; a second layer comprising silicon nitride
Implementation Method 2
an infrared (IR) reflecting layer comprising silver located over and directly contacting the first contact layer comprising Ni and/or Cr
Implementation Method 3
Good solar control characteristics (e.g., fairly low sheet resistance and/or emissivity) can also be achieved
Implementation Method 4
The coated article may or may not be heat treated in different example embodiments of this invention
Data Source
Figure 1~2
AI summary
A coated article is provided with at least one infrared (IR) reflecting layer, and is designed so as to realize good blue glass side reflective coloration in combination with desired solar control characteristics. In certain example embodiments, the coated is designed to realize rather negative glass side reflective b* values, in combination with fairly neutral glass side reflective a* color values and good sheet resistance and/or emissivity. The coated article may be used in the context of architectural or other types of window units in certain example embodiments of this invention.