Multi-Layer Antireflection Film for Optical Substrates

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Solution Overview

Problem

Existing optical substrates for portable electronic and telecommunications equipment suffer from significant changes in reflected color with incident light angle and insufficient transmittance, along with issues of fingerprint and dust adhesion, due to inadequate antireflection and antifouling properties.

Innovation Solution

A multi-layer antireflection film with specific refractive index and thickness combinations, combined with an antifouling layer using silicone or fluorine-series substances, is applied to a reinforced glass substrate to minimize color change and adhesion, while maintaining high transmittance and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a conventional antireflection film is used, then transmittance is improved, but reflected color changes significantly with incident light angle

Engineering Contradiction:

Improvelight transmittanceVSAvoidreflected color stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent divides the antireflection film into multiple layers with different refractive indices and thicknesses. Each layer is designed with specific optical characteristics to control light reflection and transmission. By segmenting the film structure, the invention achieves broad-spectrum antireflection while minimizing color shift across different incident angles, resolving the contradiction between high transmittance and color stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different layers of the antireflection film are assigned different local qualities in terms of refractive index and thickness. The first layer has different properties than the second layer, allowing each layer to perform its specific optical function. This local differentiation enables the film to maintain consistent optical performance across varying light angles while achieving high transmittance.

Inventive Principle:

Principle #3Local quality

2Strength

If an antifouling film is made thick to improve abrasion durability, then durability is improved, but optical characteristics of the antireflection film are affected

Engineering Contradiction:

Improveabrasion durabilityVSAvoidlight transmittance

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The patent merges the antireflection film and antifouling film into a single integrated multi-layer structure. The antifouling layer is incorporated as part of the overall film system rather than being a separate thick coating. This integration allows the antifouling function to be achieved with minimal thickness, preserving the optical characteristics of the antireflection film while providing adequate abrasion durability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention uses thin film technology to achieve antifouling protection without compromising optical performance. The antifouling layer is designed as a thin coating that provides protective functionality while maintaining the transparency and optical properties of the underlying antireflection film, thus avoiding the trade-off between thickness and optical characteristics.

Inventive Principle:

Principle #30Flexible shells and thin films

3Use of energy by moving object

If the antifouling film is made thin to preserve optical characteristics, then transmittance is maintained, but abrasion durability is reduced

Engineering Contradiction:

Improvelight transmittanceVSAvoidabrasion durability

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The patent employs composite material structure where multiple layers with different properties are combined. The antifouling layer is formulated with materials that provide both protective functionality and adequate mechanical strength in a thin configuration. This composite approach allows the thin film to maintain both optical transparency and sufficient abrasion durability simultaneously.

Inventive Principle:

Principle #40Composite 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 change with incident angle, enhances visibility, and provides robustness against external forces and adhesion, ensuring a clear and durable optical surface for portable devices.

Implementation Method 1

a reinforcement layer, which is intended to prevent cracking, formed on a glass substrate

Methodology Applied

Scientific EffectReinforcement treatment:

Implementation Method 2

has an antiglare layer such as a microstructure formed on the reinforcement layer

Methodology Applied

Scientific EffectAntiglare microstructure:

Implementation Method 3

has a tone-adjustment antireflection film formed on the antiglare layer

Methodology Applied

Scientific EffectAntireflection: Anti-Reflective Coating

Implementation Method 4

As an antifouling film, a water-repellent and oil-repellent film is well known

Methodology Applied

Scientific EffectWater-repellent and oil-repellent: Hydrophobe

Data Source

PatentUS8882280B2Optical substrate

Publication Date: 2014.11.11 TOPCON CORPORATION

AI summary

An optical substrate such as a cover glass which effects only a small change in a reflected color dependent on an incident angle, or more particularly, an optical substrate such as a cover glass for displays includes a reinforcement layer intended to prevent cracking, an antiglare layer formed on the reinforcement layer, a tone-adjustment antireflection film formed on the antiglare layer, and an antifouling layer formed on the antireflection film intended to minimize fingerprint adhesion. The antireflection film includes at least nine layers.