Foldable Display Hydrophobic Layer Stress Management

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Solution Overview

Problem

Flexible display devices face issues with protection films detaching from the surface at folding portions due to repeated stress, leading to potential damage and fingerprint stains.

Innovation Solution

A foldable display device with a hydrophobic anti-fingerprint layer and a hard coating layer, including polyimide, is designed to maintain adhesion and prevent delamination, featuring specific opening widths and curvature radii to manage stress and protect against fingerprints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an additional protection film is attached to the display surface, then the display surface is protected, but the protection film may detach from the surface at folding portions due to repeated stress

Engineering Contradiction:
Improveprotection film adhesionVSAvoidresistance to repeated stress
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies different properties to different regions of the protection film. Specifically, hydrophobic regions are created at the folding portions where stress concentration occurs, while other regions maintain standard protective properties. This local differentiation allows the film to better withstand repeated folding stress without detaching.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent modifies the surface energy parameters of the protection film by applying a hydrophobic coating at specific regions. This changes the wettability and adhesion characteristics locally, enabling the film to maintain stronger bonding at folding portions where stress is applied repeatedly.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the display device is made flexible to be folded, then portability is improved, but fingerprint stains occur on the display surface

Engineering Contradiction:
Improvefolding capabilityVSAvoidfingerprint stains
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies hydrophobic regions specifically at the folding portions of the display surface, creating a localized solution to the fingerprint problem. These hydrophobic regions repel oils and contaminants from fingerprints, preventing stains while maintaining the overall flexibility and display functionality of the device.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent converts the potentially harmful effect of folding (which causes stress and contamination) into a beneficial feature by applying hydrophobic coating at folding portions. This coating transforms the high-stress folding areas into regions that actively repel fingerprints and stains, turning a vulnerability into an advantage.

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

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 prevents delamination of protection films and reduces fingerprint stains by maintaining adhesion and distributing stress across the display device's surface, enhancing durability and usability.

Implementation Method 1

a second layer disposed on the first layer, the second layer including a hydrophobic material

Methodology Applied
Scientific EffectHydrophobic effect: Hydrophobe

Data Source

PatentEP3680694B1Foldable display device
Publication Date: 2021.08.18 SAMSUNG DISPLAY CO LTD
  • EP3680694B1 patent drawingFigure 1
  • EP3680694B1 patent drawingFigure 2A
  • EP3680694B1 patent drawingFigure 2B

AI summary

A display device including: a display panel configured to be folded about a first bending axis; a window member disposed on the display panel, the window member including a transparent material; and a functional layer disposed on the window member, the functional layer including a hydrophobic material and a first opening at a region corresponding to the first bending axis.