Temperable Three-Layer Antireflective Coating for Glass
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Solution Overview
Problem
Existing antireflective (AR) coatings for glass are not adequately temperable, leading to undesirable optical flaws and degradation in spectral response when exposed to heat treatment temperatures, resulting in color shifts and mechanical instability.
Innovation Solution
A three-layer antireflective coating comprising a medium index layer of silicon oxynitride (SiOxNy), a high index layer of titanium oxide (TiOx), and a low index layer of silicon oxide (SiOx), with specific refractive indices and thicknesses, that maintains compressive residual stress after heat treatment, reducing tensile stress and promoting a net compressive residual stress for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass is coated with antireflective coating and then tempered, then the coating provides antireflective properties, but the tempering process produces undesirable optical flaws and color shifts in the glass product
Solution Approach 1:
The patent modifies the chemical composition parameters of the antireflective coating by incorporating specific metal oxides (TiO2, ZnO, SnO2) and metal oxynitrides (TiOxNy, ZnOxNy, SnOxNy) with controlled ratios. This compositional parameter change enables the coating to withstand tempering temperatures without producing optical flaws or color shifts, resolving the contradiction between coating durability and optical quality.
Solution Approach 2:
The patent creates a composite antireflective coating material combining multiple metal oxides and oxynitrides with specific refractive indices. This composite structure provides both the necessary antireflective properties and thermal stability during tempering, eliminating optical flaws while maintaining coating functionality.
2Strength
If tempering is performed before coating, then the glass achieves desired mechanical strength, but the subsequent coating process becomes complex and may compromise optical quality
Solution Approach 1:
The patent applies the antireflective coating to the glass substrate before the tempering process. The coating is designed with thermal stability to withstand the subsequent tempering temperatures, eliminating the need for post-tempering coating operations and simplifying the overall manufacturing process while maintaining optical quality.
Solution Approach 2:
The coating composition is specifically engineered with metal oxides and oxynitrides that maintain their structural integrity and optical properties through the tempering temperature range, enabling the coating to be applied before heat treatment without compromising performance.
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 effectively minimizes color shift and maintains optical and mechanical properties after heat treatment, ensuring a durable and aesthetically pleasing tempered glass product with reduced reflection and increased transmission.
Implementation Method 1
the medium index layer has compressive residual stress after heat treatment
Implementation Method 2
A temperable three layer antireflective coating, coated article including temperable three layer antireflective coating, and/or method of making the same
Data Source
AI summary
A coated article includes a temperable antireflection (AR) coating that utilizes medium and low index (index of refraction “n”) layers having compressive residual stress in the AR coating. In certain example embodiments, the coating may include the following layers from the glass substrate outwardly: silicon oxynitride (SiOxNy) medium index layer/high index layer/low index layer. In certain example embodiments, depending on the chemical and optical properties of the high index layer and the substrate, the medium and low index layers of the AR coating are selected to cause a net compressive residual stress and thus optimize the overall performance of the antireflection coating when the coated article is tempered and/or heat-treated.