Multi-Layer Anti-Reflective Coating for Scratch Resistance
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Solution Overview
Problem
Existing anti-reflective coatings for cover articles are susceptible to wear, abrasion, and scratch damage, compromising their optical performance and durability.
Innovation Solution
The development of durable and scratch-resistant anti-reflective articles featuring a substrate with an optical coating that includes a multi-layer anti-reflective coating, providing enhanced hardness, abrasion resistance, and improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional anti-reflective coatings are applied to improve optical performance, then light transmittance and reflectance are improved, but the coating becomes susceptible to wear and abrasion
Solution Approach 1:
The patent applies composite materials by combining multiple dielectric layers with different refractive indices (e.g., silicon dioxide, silicon nitride, silicon oxynitride) to create an anti-reflective coating that simultaneously achieves superior optical performance and enhanced mechanical durability. The multi-layer structure allows optimization of both optical properties and hardness/scratch resistance
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the thickness, refractive index, and composition of each layer in the multi-layer coating system. By adjusting these parameters during deposition processes, the coating achieves optimal balance between anti-reflective performance and mechanical properties such as hardness and abrasion resistance
2Strength
If hard coatings like nitrides or diamond-like coatings are used to increase hardness, then scratch resistance is improved, but transmittance performance deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the coating into multiple functional layers, where different layers provide different properties. Softer dielectric layers maintain optical transmittance while harder layers provide scratch resistance, and the layered structure allows each material to perform its optimal function without compromising the other
Solution Approach 2:
The patent implements local quality by assigning different materials and properties to different layers of the coating system. Each layer is optimized for specific local requirements - some layers prioritize optical transmittance while others prioritize hardness and scratch resistance, creating a spatially differentiated structure that satisfies multiple conflicting requirements
3Reliability
If abrasion-resistant coatings are applied to prevent wear, then durability is improved, but the coating becomes more susceptible to scratch damage
Solution Approach 1:
The patent uses composite materials combining multiple dielectric compounds with complementary properties. The combination of materials such as silicon dioxide, silicon nitride, and silicon oxynitride in a multi-layer configuration provides both wear resistance from the durable dielectric structure and scratch resistance from the optimized hardness distribution across layers
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 achieves a maximum hardness of 12 GPa or greater, excellent abrasion resistance as measured by a 500-cycle Taber Test, and superior optical performance with low reflectivity and colorlessness, maintaining performance even at varying viewing angles.
Implementation Method 1
an optical coating disposed on the major surface forming an anti-reflective surface
Data Source
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AI summary
Embodiments of durable, anti-reflective articles are described. In one or more embodiments, the article includes a substrate and an optical coating disposed on the major surface. The optical coating includes an anti-reflective coating and a scratch-resistant coating forming an anti-reflective surface. The article exhibits a maximum hardness of 12 GPa or greater, as measured on the anti-reflective surface by a a Berkovich Indenter Hardness Test along an indentation depth of about 100 nm or greater. The articles of some embodiments 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 and a reference point color shift in transmittance or reflectance of less than about 2. In some embodiments, the article exhibits an angular color shift of about 5 or less at all angles from normal incidence to an incident illumination angle that is 20 degrees or greater.