Flexible Display Edge Lifting Prevention via TFT Extension

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Solution Overview

Problem

Flexible display panels in mobile terminals are prone to lifting at curved edges due to their elasticity, which is not adequately addressed by existing technologies.

Innovation Solution

A mobile terminal design that includes a display panel with a support plate surrounding a curved edge, featuring a protective film structure composed of stacked layers such as colorless polyimide, polyethylene terephthalate, and hard coating films, with an anti-fingerprint film, and a thin-film transistor film extended to the rear face of the curved edge to prevent lifting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a flexible protective film is used to enable the display panel to be folded or rolled, then the adaptability and flexibility of the display panel are improved, but the protective film is lifted at the curved edge due to its elasticity and lack of fixed shape

Engineering Contradiction:
Improveflexibility of display panelVSAvoidshape stability of protective film
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by stacking multiple protective films with different properties (CPI film for flexibility, PET film for shape fixation, HC film for hardness, AF film for fingerprint resistance). This composite structure combines the advantages of each material to achieve both flexibility and shape stability, preventing the protective film from lifting at curved edges while maintaining the display panel's foldable or rollable capability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by extending the TFT film to the rear face of the curved edge to surround the curved edge. This localized extension provides additional support and shape fixation specifically at the curved edge region where lifting occurs, without affecting the overall flexibility of the display panel in other areas

Inventive Principle:
Principle #3Local quality

2Device complexity

If a single-layer protective film is used to maintain simplicity, then the device complexity is reduced, but the protective film cannot simultaneously provide flexibility, shape fixation, and resistance to fingerprints

Engineering Contradiction:
Improvestructure of protective filmVSAvoidfunctional performance of protective film
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent uses a multi-layer composite structure where each layer provides a specific function: CPI film for flexibility, PET film for shape fixation, HC film for hardness and scratch resistance, and AF film for fingerprint resistance. This composite approach allows a single protective film assembly to deliver multiple functions that would be difficult to achieve with a single material

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The protective film is segmented into multiple functional layers, with each layer responsible for a specific property. This segmentation allows independent optimization of each layer's characteristics while maintaining overall system performance, and the layered structure can be applied as a unified component to the display panel

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3945711B1Mobile terminal
Publication Date: 2023.07.12 LG ELECTRONICS INC
  • EP3945711B1 patent drawingFigure 1
  • EP3945711B1 patent drawingFigure 2(a)~2(b)
  • EP3945711B1 patent drawingFigure 3(a)~3(b)

AI summary

A mobile terminal according to an embodiment includes a display panel having flexibility, and a support plate configured to support the display panel and to include a curved edge, at least a part of which is surrounded by the display panel. The display panel includes a base substrate, a light-emitting layer provided on the base substrate and configured to include a light-emitting element, a thin-film encapsulation layer configured to seal the light-emitting element, and a thin-film transistor (TFT) film configured to supply a signal to the light-emitting element, a polarizing film provided on the light-emitting layer, and a protective film provided on the polarizing film. The TFT film is extended from the base substrate at the curved edge to cover an edge of the base substrate.