Flexible Display Structure With Elastic Folding Zones

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Solution Overview

Problem

Existing foldable and rollable display devices face structural and material limitations that lead to damage and reduced durability during bending or rolling, particularly due to increased bending curvature and stress concentration on inorganic layers.

Innovation Solution

A novel structure for flexible display devices is introduced, featuring etched first regions along bending axes filled with an elastic filling layer, where thin-film transistors, organic light-emitting elements, and functional layers are removed, and replaced by a filling layer with sufficient elasticity to withstand stress, thereby enhancing durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If thin-film transistors, organic light-emitting elements and functional layers are removed from first regions to enable folding, then flexibility and foldability are improved, but structural strength and durability are worsened

Engineering Contradiction:
ImprovefoldabilityVSAvoidstructural strength
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies local quality by creating first regions with different structural characteristics from the second regions. The first regions have removed thin-film transistors, organic light-emitting elements and functional layers, making them thinner and more flexible. The second regions retain the full stack structure for display functionality. This local differentiation enables the display device to fold at specific locations while maintaining structural integrity where elements are present.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the display device into first regions and second regions along bending axes. This segmentation allows the device to be divided into flexible folding areas and rigid functional areas, enabling controlled bending while protecting the light-emitting elements from damage during folding operations.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If folding radius is reduced to improve flexibility, then adaptability is improved, but stress concentration and durability are worsened

Engineering Contradiction:
ImproveflexibilityVSAvoiddurability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements beforehand cushioning by providing support structures in the first regions where elements are removed. These support structures prevent excessive stress concentration during bending by distributing the mechanical load. The etched first regions act as cushioning zones that absorb bending stress while the support structures maintain overall structural integrity, preventing damage to the light-emitting elements in the second regions.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If elements are removed from first regions to enable bending, then ease of operation is improved, but manufacturing complexity is worsened

Engineering Contradiction:
Improvebending capabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by removing the thin-film transistors, organic light-emitting elements and functional layers from the first regions during the manufacturing process before final assembly. This preliminary removal creates the flexible folding zones in advance, simplifying the subsequent folding operation. The etching process is performed as a preliminary step to prepare the first regions for bending while the second regions are simultaneously prepared with the full element stack.

Inventive Principle:
Principle #10Preliminary action

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 proposed structure reduces folding radius without weakening the display device's strength, improving durability and enabling reliable operation when folded or rolled.

Implementation Method 1

the filling layer may be a material having an elastic modulus of 50 MPa to 200 MPa

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3644370B1Flexible display device
Publication Date: 2025.07.23 LG DISPLAY CO LTD
  • EP3644370B1 patent drawingFigure 1
  • EP3644370B1 patent drawingFigure 2A
  • EP3644370B1 patent drawingFigure 2B

AI summary

This present disclosure discloses a display device (100) . The display device (100) may include a bending area and a non-bending area. A structure for improving durability may be included in the bending area. The display device (100) may include a base layer (101) having one or more first regions (B) that can be folded along a predetermined axis, and a second region (C) adjacent to the first regions (B); and thin-film transistors 102, 104, 106, 108, organic light-emitting elements (112, 114, 116) and functional layers stacked in the second region (C) of the base layer (101) . The thin-film transistors 102, 104, 106, 108, the organic light-emitting elements (112, 114, 116) and the functional layers stacked in the second regions (C) are not disposed in the first regions (B). Instead, the space otherwise occupied by the elements is filled with the filling layer (130).