Scratch-Resistant Optical Film Structure for Displays
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Solution Overview
Problem
Existing cover articles for electronic and architectural applications face challenges in providing both scratch resistance and maintaining optical properties, particularly in preventing microductile scratches and abrasion damage without compromising light transmittance and reflectance.
Innovation Solution
The development of an article with an optical film structure disposed on a substrate, featuring a layered structure with specific materials like silicon-containing oxides and aluminum-containing nitrides, which provides a hardness of 12 GPa or greater and a coefficient of friction less than 0.3, ensuring scratch resistance while maintaining high light transmittance and constant reflectance across the visible spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard coating is applied to provide scratch resistance, then scratch resistance is improved, but optical properties (light transmittance and reflectance) are compromised
Solution Approach 1:
The coating is divided into multiple layers with different functions: a first layer (e.g., silicon-containing oxide) providing scratch resistance and a second layer (e.g., aluminum-containing nitride) optimized for optical properties. This segmentation allows each layer to specialize, with the first layer protecting against scratches and the second layer maintaining high light transmittance and constant reflectance across the visible spectrum
Solution Approach 2:
The patent uses composite material structures combining different ceramic materials (silicon-containing oxide, aluminum-containing nitride) in a layered configuration. This composite approach enables the coating to simultaneously achieve high hardness (12 GPa or greater) for scratch resistance and optimal optical properties (85% or more average light transmittance), as each material contributes its superior properties to the overall coating system
2Duration of action of stationary object
If abrasion resistance is enhanced through multiple contact event protection, then durability is improved, but optical clarity is degraded
Solution Approach 1:
The first layer acts as a sacrificial cushioning layer that absorbs the damage from multiple contact events and abrasion before they can reach and damage the second optical layer. This prior cushioning protects the optically critical second layer from degradation, maintaining optical clarity while providing enhanced durability against abrasion from sand, gravel, and other environmental factors
Data Source
AI summary
One or more aspects of the disclosure pertain to an article including an optical film structure disposed on a substrate, which may include a strengthened or non-strengthened substrate that may be amorphous or crystalline, such that the article exhibits scratch resistance and retains the same or improved optical properties as the substrate, without the optical film structure disposed thereon. In one or more embodiments, the article exhibits an average transmittance of 85% or more, over the visible spectrum (e.g., 380 nm-780 nm). Embodiments of the optical film structure include aluminum-containing oxides, aluminum-containing oxy-nitrides, aluminum-containing nitrides (e.g., AlN) and combinations thereof. The optical film structures disclosed herein also include a transparent dielectric including oxides such as silicon oxide, germanium oxide, aluminum oxide and a combination thereof. Methods of forming such articles are also provided.