Scratch-Resistant Anti-Reflective Optical Coatings
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Solution Overview
Problem
Existing anti-reflective coatings for cover articles are susceptible to abrasion and scratch damage, compromising their optical performance and durability, as they lack the necessary mechanical properties and transmittance for applications in mobile devices, architectural, and transportation articles.
Innovation Solution
Development of durable and scratch-resistant anti-reflective articles with a substrate and optical coating that includes a scratch-resistant layer and anti-reflective coating, featuring a high refractive index layer with a hardness of 12 GPa or greater and an abrasion resistance measured by a Taber Test, maintaining low reflectivity and transmittance while minimizing color shift with viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If known anti-reflective coatings are used to improve optical performance, then light transmittance and reflectance are improved, but scratch resistance and abrasion resistance deteriorate
Solution Approach 1:
The patent applies composite materials by combining multiple coating layers with different properties: a hard undercoat layer (5-15 nm thick) made from materials like silicon oxide, silicon nitride, or silicon oxynitride provides scratch and abrasion resistance, while upper anti-reflective layers provide optical performance. This composite structure resolves the contradiction by integrating materials with complementary functions.
Solution Approach 2:
The patent implements local quality by giving different regions of the coating different properties: the undercoat layer near the substrate has high hardness for mechanical protection, while the upper layers have optimized refractive indices for anti-reflective optical performance. This spatial differentiation of material properties allows simultaneous achievement of durability and optical quality.
2Strength
If hard materials like nitrides and diamond-like coatings are used to improve scratch resistance, then hardness is improved, but light transmittance deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the coating into distinct functional layers: a thin hard undercoat layer (5-15 nm) provides scratch resistance, while separate upper layers with optimized thickness and refractive index provide light transmittance. This segmentation allows each layer to specialize in one function without compromising the other.
Solution Approach 2:
The patent uses parameter changes by precisely controlling the thickness (5-15 nm) and composition of the hard undercoat layer to achieve optimal balance between hardness and transmittance. By adjusting these parameters, the hard layer provides protection while remaining thin enough to allow sufficient light transmission to subsequent optical layers.
3Illumination intensity
If anti-reflective coatings are applied to improve optical performance, then reflectance is reduced, but durability against abrasion damage deteriorates
Solution Approach 1:
The patent applies beforehand cushioning by placing a hard protective undercoat layer between the substrate and the softer anti-reflective coating layers. This undercoat acts as a cushion that absorbs abrasion damage before it reaches the optical layers, preventing flaking and degradation while maintaining optical performance.
Solution Approach 2:
The patent uses composite materials with the undercoat layer made from abrasion-resistant materials (silicon oxide, silicon nitride, or silicon oxynitride) and upper layers optimized for optical performance. This composite structure provides both durability against abrasion and reduced reflectance simultaneously.
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 provides enhanced scratch and abrasion resistance, maintaining superior optical performance with high transmittance and low reflectance, and minimal color shift, addressing the limitations of existing coatings in durability and optical performance.
Implementation Method 1
an optical coating disposed on the major surface forming an anti-reflective surface
Data Source
AI summary
Embodiments of articles with optical coatings are described herein. According to one embodiment, an article may comprise a substrate having a major surface, and an optical coating disposed on the major surface and forming an anti-reflective surface, the optical coating comprising an anti-reflective coating. The article may exhibit a maximum hardness of about 12 GPa or greater as measured on the anti-reflective surface by a Berkovich Indenter Hardness Test along an indentation depth of about 100 nm or greater. The article may exhibit a single side average light reflectance measured at the anti-reflective surface of about 8% or less over an optical wavelength regime in the range from about 400 nm to about 800 nm. The article may exhibit an average light transmission of about 90% or greater over an optical wavelength regime in the range from about 400 nm to about 800 nm.