Flexible Display Crack Prevention via Organic-Inorganic Encapsulation

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Solution Overview

Problem

Flexible display devices with inorganic films in non-display areas are prone to cracking when curved or bent, leading to moisture permeation and reduced reliability.

Innovation Solution

Incorporating a crack preventing portion in the non-display area of the flexible display device, formed from organic insulating materials, to mitigate stress concentrations in inorganic films and prevent cracks, thereby enhancing the device's reliability by sealing the inorganic films with organic films alternately deposited in the encapsulation layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an inorganic film is used in the encapsulation layer to protect the thin film transistor and organic light emitting device, then the protection against external shocks and moisture permeation is improved, but the film is prone to cracking when the device is curved or bent

Engineering Contradiction:

Improveprotection against moisture permeationVSAvoidcrack resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The encapsulation layer is designed as a composite structure with alternating inorganic and organic films. The inorganic film provides moisture barrier protection while the organic film provides flexibility and stress relief, preventing cracks when the device is bent. This composite structure combines the advantages of both material types to resolve the contradiction between protection and crack resistance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The organic film in the encapsulation layer acts as a flexible component that can accommodate bending and curving of the device. This flexible film absorbs the mechanical stress that would otherwise concentrate on and crack the rigid inorganic film, allowing the device to maintain both protection and flexibility.

Inventive Principle:

Principle #30Flexible shells and thin films

2Area of stationary object

If the inorganic film extends from the upper side of the organic light emitting device to the outermost region, then the coverage and protection area is improved, but the stress concentration during bending increases

Engineering Contradiction:

Improvecoverage area of encapsulation layerVSAvoidstress concentration

Core Design Contradiction:

Area of stationary objectVSStress or pressure

Solution Approach 1:

The extended encapsulation layer uses alternating inorganic and organic films, where the organic films distributed throughout the extended area provide stress relief at multiple locations. This prevents stress concentration even though the coverage area is enlarged to the outermost region.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The organic films serve as intermediary layers between the inorganic films in the extended region. These intermediary organic layers absorb and distribute the mechanical stress during bending, preventing stress concentration at any single point in the extended encapsulation area.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10135028B2Flexible display device including the crack preventing portion

Publication Date: 2018.11.20 LG DISPLAY CO LTD

AI summary

A flexible display device includes a base substrate defining a display area and a non-display area; a thin film transistor in the display area of the base substrate; an organic light emitting diode on and connected with the thin film transistor; an encapsulation layer on the organic light emitting diode; and a crack preventing portion in the non-display area defined by the base substrate.