Foldable Display Air Gap Stress Mitigation

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Solution Overview

Problem

Conventional foldable display devices face reliability issues due to stress-induced damage in the folding areas, affecting light emitting quality and properties of thin film transistors (TFTs).

Innovation Solution

A foldable electronic device design featuring a display panel with a cover layer connected through an intermediate layer, which includes at least one air gap across the folding line to mitigate stress, optimizing the width and length of the air gap for effective stress release and adhesion performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the cover layer is directly connected to the display panel without air gaps, then the adhesion strength is improved, but the stress-induced damage to electrodes, TFTs and capacitors increases during folding

Engineering Contradiction:

Improveadhesion strengthVSAvoidstability during folding

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

An intermediate layer is introduced between the cover layer and the display panel to act as a stress-absorbing intermediary. This intermediate layer contains air gaps that compress during folding, preventing direct stress transmission to the electrodes, TFTs and capacitors, while still maintaining adequate adhesion strength through the intermediate layer's bonding capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The physical state of the intermediate layer is changed by incorporating air gaps, which alter its compressibility and stress-absorption characteristics. The air gaps provide a cushioning effect that changes how the intermediate layer responds to folding stress, protecting the underlying electronic components while maintaining structural integrity.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If air gaps are introduced between the cover layer and display panel, then the stress during folding is reduced, but the adhesion strength between cover layer and display panel decreases

Engineering Contradiction:

Improvestability during foldingVSAvoidadhesion strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The intermediate layer's physical properties are optimized by controlling the size, distribution and volume of air gaps. By adjusting these parameters, the layer achieves a balance between stress absorption (through air gap compression) and adhesion maintenance (through the intermediate layer's bonding surfaces), resolving the contradiction between protection and attachment.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the intermediate layer is made thicker to provide better stress absorption, then the protection against folding stress is improved, but the device overall thickness increases

Engineering Contradiction:

Improveprotection against folding stressVSAvoiddevice thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The intermediate layer is designed with a porous structure containing air gaps, which provides excellent stress absorption capability per unit thickness. The air gaps act as cushioning elements that compress under stress, enabling effective protection against folding damage while maintaining a thin overall profile, thus avoiding the need for excessive thickness.

Inventive Principle:

Principle #31Porous materials

Data Source

PatentUS10534400B2Foldable electronic device

Publication Date: 2020.01.14 INNOLUX CORP

AI summary

A foldable electronic device includes an electronic element including a folding line and a cover layer connected to the electronic element through an intermediate layer. The electronic element, the cover layer and the intermediate layer form at least one air gap across the folding line.