Flexible Display Substrate Buffer Layer for Cutting Defect Prevention

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Solution Overview

Problem

The manufacturing process of flexible display devices using flexible substrates often results in defects due to excitation and side permeability issues during the cutting process, which are caused by differences in margins between cutting the flexible and base substrates.

Innovation Solution

A display device design that includes a buffer layer surrounding the front and side surfaces of a first substrate, with a passivation film on the same layer as the substrate, and an encapsulation layer covering the pixel array layer, along with a method of forming substrates on a supporting substrate, followed by cutting to minimize excitation and side permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a flexible substrate is used to achieve thin profile and light weight, then flexibility and weight are improved, but excitation and side permeability defects occur during cutting due to margin differences

Engineering Contradiction:
ImproveweightVSAvoiddefect rate
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by forming the buffer layer on the flexible substrate before the cutting process. This buffer layer is extended to the side surfaces of the substrate in advance, creating a protective structure that prevents excitation and side permeability defects during subsequent cutting operations. The buffer layer acts as a pre-prepared protective barrier that eliminates the harmful effects of margin differences between substrate and base substrate cutting.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the buffer layer is extended to surround the side surfaces of the substrate, then side permeability is prevented, but device complexity increases

Engineering Contradiction:
Improveside permeability preventionVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The buffer layer in this patent serves multiple functions simultaneously: it provides electrical insulation, prevents side permeability of moisture and oxygen, and acts as a mechanical support during cutting operations. By making the buffer layer multi-functional and extending it to cover side surfaces, the patent achieves reliable protection without requiring additional separate protective components, thus avoiding increased device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the flexible substrate is cut separately from the base substrate, then flexibility is maintained, but margin differences cause excitation and side permeability defects

Engineering Contradiction:
ImproveflexibilityVSAvoidcutting alignment
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent introduces the buffer layer as an intermediary element that extends from the flexible substrate to cover the side surfaces. This intermediary structure acts as a bridge that compensates for margin differences between substrate and base substrate cutting. The buffer layer absorbs the misalignment effects and prevents excitation and side permeability defects, allowing independent cutting of the flexible substrate while maintaining manufacturing precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3439054B1Display device and method for manufacturing the same
Publication Date: 2025.08.27 LG DISPLAY CO LTD
  • EP3439054B1 patent drawingFigure 1
  • EP3439054B1 patent drawingFigure 2~4
  • EP3439054B1 patent drawingFigure 5A~5C

AI summary

A display device and a method for manufacturing the same are disclosed, in which excitation and side permeability of a flexible substrate are minimized to prevent defects of a display panel from occurring. The display device comprises a first substrate (110); a buffer layer (120) arranged on the first substrate; a pixel array layer (130) arranged on the buffer layer; and an encapsulation layer (140) covering the pixel array layer, wherein the buffer layer surrounds a front surface and a side of the first substrate. The method for manufacturing a display device comprises the steps of (A) preparing a supporting substrate; (B) forming a plurality of first substrates spaced apart from one another on the supporting substrate; (C) forming a buffer layer covering the plurality of first substrates; (D) forming a pixel array layer on areas of the buffer layer that overlap with each of the plurality of first substrates; (E) forming an encapsulation layer covering the pixel array layer; and (F) forming a plurality of display panels by cutting the supporting substrate (100) and the buffer layer along at least one cutting line defined between the plurality of first substrates.