Interpenetrating Polymer Hydrogel Encapsulation for Flexible Displays

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Solution Overview

Problem

Flexible rollable and foldable display devices face defects due to stress caused by flexing, rolling, or folding, primarily resulting from differences in shear strain between inner and outer layers, leading to potential separation of encapsulation layers.

Innovation Solution

A display device design featuring a second encapsulation layer made of interpenetrating polymer hydrogel over a first encapsulation layer, with an elastic connection layer in between, to absorb and distribute stress, preventing layer separation and damage. The interpenetrating polymer hydrogel includes materials like polyacrylamide and alginate, and the elastic connection layer uses organopolysiloxane for enhanced adhesion and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a flexible display device is rolled or folded, then the device achieves portability and flexibility, but stress is applied to the display device causing defects and layer separation

Engineering Contradiction:

ImproveflexibilityVSAvoidlayer adhesion

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

An elastic material layer is introduced between the first and second encapsulation layers to provide beforehand cushioning against stress. This elastic layer absorbs and distributes the stress generated during rolling or folding operations, preventing the stress from concentrating at the interfaces between encapsulation layers and causing separation. The elastic material acts as a pre-positioned protective element that mitigates damage before it occurs.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The encapsulation structure employs composite materials including an elastic material (such as polyurethane, polyacrylate, or silicone-based materials) combined with the first and second encapsulation layers. This composite structure combines the protective barrier function of the encapsulation layers with the stress-absorbing properties of the elastic material, creating a multi-functional system that maintains both flexibility and layer adhesion.

Inventive Principle:

Principle #40Composite materials

2Volume of moving object

If the display device is made thinner by using flexible materials, then the device achieves reduced thickness, but the device becomes more susceptible to stress-induced defects

Engineering Contradiction:

ImprovethicknessVSAvoidstress concentration

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent employs flexible encapsulation layers and an elastic material layer that can bend and deform without breaking. These flexible thin-film structures maintain the reduced thickness requirement while inherently accommodating the stress generated during rolling or folding, thereby preventing stress concentration and the associated defects.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The elastic material layer changes its physical parameters (such as thickness, elasticity modulus, or material composition) to optimize the balance between maintaining thin overall device profile and providing sufficient stress absorption capability. By adjusting these parameters, the design achieves both reduced thickness and resistance to stress-induced defects.

Inventive Principle:

Principle #35Parameter changes

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 or eliminates defects in flexible display devices by absorbing stress and maintaining layer adhesion, even under external forces, enhancing the device's toughness and flexibility, allowing for reliable operation when rolled or folded.

Implementation Method 1

The second encapsulation layer comprises an interpenetrating polymer hydrogel... effectively reduces or eliminates defects in flexible display devices by absorbing stress and maintaining layer adhesion

Methodology Applied

Scientific EffectStress absorption: Elasticity

Implementation Method 2

a first connection layer disposed between the first encapsulation layer and the second encapsulation layer, the first connection layer connecting the first encapsulation layer and the second encapsulation layer together

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10256435B2Display device

Publication Date: 2019.04.09 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a substrate including a display area and a non-display area, a pixel part in the display area of the substrate to display an image, a first encapsulation layer disposed over and covering at least part of the pixel part, and a second encapsulation layer disposed over the first encapsulation layer and substantially covering the entire extent of the first encapsulation layer, wherein the second encapsulation layer comprises an interpenetrating polymer hydrogel.