Sol-Gel Antireflective Coating for Touch Screens

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Solution Overview

Problem

Existing antireflective coatings for touch screen displays and optical articles are costly to produce and pose environmental and processing challenges due to the use of vacuum deposition techniques and corrosive chemicals, and alternative methods for reducing reflection without compromising visibility are needed.

Innovation Solution

A multi-layer antireflective coating stack comprising two sol-gel coating layers with different refractive indices and thicknesses, applied directly to a substrate, along with an anti-fouling coating, to reduce reflection and enhance visibility without the drawbacks of existing methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If vacuum deposition techniques such as sputtering are used to deposit interference coatings, then reflection reduction is achieved, but manufacturing cost increases and processing complexity increases

Engineering Contradiction:
ImprovereflectionVSAvoidmanufacturing cost
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The invention changes the deposition method from vacuum deposition to sol-gel dip coating, altering the processing parameters to achieve the same antireflective function through a different mechanism that is less costly and more environmentally friendly

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses inexpensive sol-gel materials and simple dip coating equipment instead of expensive vacuum deposition systems, achieving comparable or superior performance with lower-cost components

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If chemical etching is used to diffuse light and reduce glare, then reflection is reduced, but handling and storage of corrosive compounds becomes problematic

Engineering Contradiction:
ImproveglareVSAvoidcorrosive compounds
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The invention converts the potentially harmful chemical etching process into a beneficial sol-gel coating process that achieves the same light diffusion effect without using corrosive compounds, thereby eliminating the harmful side effects while maintaining the desired optical performance

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent replaces the chemical etching mechanism with a physical sol-gel coating process, substituting chemical action with a material deposition approach that achieves similar optical effects without the associated hazards

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If sandblasting is used to etch the substrate surface, then light diffusion is achieved, but additional costly processing operations are required

Engineering Contradiction:
ImprovereflectionVSAvoidprocessing operations
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention combines the antireflective and anti-glare functions into a single sol-gel coating layer, eliminating the need for separate etching and coating operations, thereby reducing processing complexity while maintaining both functions

Inventive Principle:
Principle #5Merging (Combining)

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 significantly reduces reflectance and increases transmittance, improving visibility in touch screen displays and other optical articles, while being more environmentally friendly and cost-effective than existing technologies.

Implementation Method 1

An exemplary method involves depositing a light interference coating stack on the substrate that reduces reflection by exploiting the optical interference within adjacent thin films

Methodology Applied
Scientific EffectOptical interference: Interference

Implementation Method 2

a first coating layer applied to at least one surface of the substrate, wherein the first coating layer has a dry film thickness of 90 to 150 nm and is formed from a sol-gel composition

Methodology Applied
Scientific EffectSol-gel process: Gel

Data Source

PatentEP3658517B1Multi-layer antireflective coated articles
Publication Date: 2022.09.14 PPG INDUSTRIES OHIO INC

AI summary

Coated articles demonstrating antireflective properties are provided. Exemplary coated articles comprise a substrate and two or three coating layers applied to at least one surface of the substrate; the coatings are deposited from sol-gel compositions comprising a silane. Each adjacent coating layer demonstrates a different refractive index. The coated article further comprises an outermost anti-fouling coating layer applied to at least one surface of a coating layer. Processes for forming the coated articles are also provided.