Hybrid Adhesive Layer for Foldable Display Stress Distribution

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Solution Overview

Problem

Conventional foldable display apparatuses suffer from wrinkles, scratches, or ruptures due to repeated folding, damaging the touch panel's transparent conductive film and affecting its input function.

Innovation Solution

A hybrid adhesive structure with multiple adhesive units made of different materials, arranged in a planar pattern, is used to distribute stress evenly, preventing damage from folding pressure by acting as a pressure release layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single-material adhesive layer is used, then the structure is simple and easy to manufacture, but stress concentrates in the deformed central portion causing wrinkles or cracks

Engineering Contradiction:

Improveadhesive layer fabrication simplicityVSAvoidresistance to folding-induced stress concentration

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The adhesive layer is divided into multiple adhesive units with different materials arranged in a specific pattern. This segmentation allows different regions to have different mechanical properties, with softer units absorbing stress and harder units providing structural support, thereby preventing stress concentration and cracking during folding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different adhesive units are assigned different material properties tailored to their specific locations. The adhesive units have different viscoelastic moduli, with softer materials positioned in areas prone to stress concentration and harder materials in areas requiring structural stability, optimizing the overall performance of the adhesive layer.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the adhesive layer is made uniform throughout, then manufacturing is simplified, but the adhesive cannot effectively release stress during folding

Engineering Contradiction:

Improveadhesive layer uniformityVSAvoidstress release capability during folding

Core Design Contradiction:

Ease of manufactureVSStress or pressure

Solution Approach 1:

The uniform adhesive layer is replaced with a segmented hybrid adhesive layer consisting of multiple adhesive units with different materials. This segmentation enables the adhesive layer to release stress effectively during folding by allowing different units to deform and absorb stress differently, preventing crack formation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The adhesive layer uses a composite structure with multiple adhesive materials having different viscoelastic moduli. This composite approach combines the advantages of different materials - softer materials for stress absorption and harder materials for structural integrity - enabling effective stress release during folding while maintaining manufacturing feasibility.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If repeated folding is performed, then the display apparatus achieves its foldable function, but the transparent conductive film and adhesive layer suffer damage

Engineering Contradiction:

Improvefoldable functionalityVSAvoidintegrity of transparent conductive film and adhesive layer

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The hybrid adhesive layer is designed beforehand to provide stress absorption and distribution capabilities. By positioning softer adhesive units in areas prone to stress concentration, the structure is pre-configured to cushion against folding-induced stresses, preventing damage to the transparent conductive film and adhesive layer during repeated folding operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

Different adhesive units are strategically positioned with specific material properties to address local stress patterns during folding. This localized optimization ensures that areas most susceptible to damage receive the appropriate level of stress absorption and protection, maintaining the integrity of the transparent conductive film and adhesive layer during repeated folding.

Inventive Principle:

Principle #3Local quality

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 hybrid adhesive structure effectively reduces stress concentration, preventing wrinkles and cracks, ensuring the longevity and functionality of foldable display devices by distributing pressure across different adhesive units with varying viscoelastic properties.

Implementation Method 1

The different adhesive materials have at least one different property selected from a group including viscoelastic, Young's modulus, adhesion strength, elongation, hardness

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Data Source

PatentUS9333725B2Adhesive structure with hybrid adhesive layer

Publication Date: 2016.05.10 HANNSTAR DISPLAY CORP

AI summary

An adhesive structure is disclosed. The adhesive structure includes a first layer, a second layer, and a hybrid adhesive layer for adhering the first layer to the second layer. The hybrid adhesive layer includes two or more adhesive units made of different adhesive materials, and the two or more adhesive units are arranged in a planar pattern.