Scratch-resistant optical film with refractive index gradient
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Solution Overview
Problem
Existing cover substrates for consumer electronic devices face challenges in maintaining scratch resistance and optical performance, particularly experiencing color shift and reduced brightness due to scratches, which compromise the display quality and durability.
Innovation Solution
A substrate with an optical film having a refractive index gradient and a scratch-resistant layer, where the optical film includes materials like Al2O3, Nb2O5, and SiOxNy, and a porosity gradient to minimize reflectance oscillations and enhance durability, while maintaining high transmittance and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a scratch-resistant coating is applied to glass cover substrate, then scratch resistance is improved, but color shift and optical performance deteriorate
Solution Approach 1:
The patent applies a gradient refractive index structure where the optical film has varying refractive index from bottom to top, creating local property variations that minimize reflectance oscillations and color shift while maintaining scratch resistance. The gradient transitions from higher refractive index at the substrate interface to lower refractive index at the exposed surface.
Solution Approach 2:
The patent uses a composite structure combining glass substrate, optical film with gradient refractive index, and scratch-resistant coating. This multi-layer composite approach allows each layer to perform its specific function: the glass provides structural support, the gradient optical film minimizes optical interference, and the top coating provides scratch resistance.
2Strength
If traditional scratch-resistant materials are used, then hardness is improved, but optical transmittance and color stability worsen
Solution Approach 1:
The patent changes the refractive index parameter through the thickness of the optical film, creating a gradient that optimizes both optical performance and mechanical properties. By controlling the refractive index profile, the patent achieves high light transmittance while maintaining compatibility with scratch-resistant materials.
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 effectively reduces color shift and maintains high optical performance and scratch resistance, ensuring the display quality and durability of consumer electronic devices, even under harsh conditions.
Implementation Method 1
The optical film has a refractive index gradient, where the refractive index varies from the first surface to the second surface
Implementation Method 2
minimize reflectance oscillations and enhance durability, while maintaining high transmittance
Data Source
AI summary
Embodiments of this disclosure pertain to articles that exhibit scratch-resistance and improved optical properties. In some examples, the article exhibits a color shift of about 2 or less, when viewed at an incident illumination angle in the range from about 0 degrees to about 60 degrees from normal under an illuminant. In one or more embodiments, the articles include a substrate, and an optical film disposed on the substrate. The optical film includes a scratch-resistant layer and a refractive index gradient. In one or more embodiments, the refractive index includes a refractive index that increases from a first surface at the interface between the substrate and the optical film to a second surface. The refractive index gradient may be formed from a compositional gradient and/or a porosity gradient.