Flexible OLED Edge Bending Trenches for Stress Reduction

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Solution Overview

Problem

Existing flexible flat panel displays face challenges in maintaining display functionality and preventing damage from bending stress at the boundaries between display and non-display areas, particularly due to differences in stack structures and stress distribution during bending or folding.

Innovation Solution

The implementation of a flexible organic light emitting diode display with trenches formed by removing specific layers at the bending portions between the display and non-display areas, which reduces bending stress and allows for seamless bending without damaging the display elements, while maintaining a similar stack structure for pad areas to prevent defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the display area and non-display area are formed with different stack structures to accommodate bending portions, then the bending stress is reduced, but the manufacturing complexity increases due to multiple etching processes

Engineering Contradiction:
Improvebending stress resistanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent applies local quality by forming a bending portion with a different stack structure (removing the second inorganic insulating layer) only in the specific edge bending area, while maintaining the complete stack structure in other areas. This localized modification reduces bending stress at the edge without requiring complete restructuring of the entire device, thus balancing stress resistance with manufacturing feasibility.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the device into different structural zones: a first area with the complete stack structure (substrate, first inorganic insulating layer, organic insulating layer, second inorganic insulating layer, gate electrode, source/drain electrodes) and a second area (edge bending area) with a modified structure where the second inorganic insulating layer is removed. This segmentation allows differential stress management across different functional regions.

Inventive Principle:
Principle #1Segmentation

2Shape

If the non-display area is bent to the rear side to achieve seamless display, then the display aesthetics are improved, but the display elements may be damaged due to bending stress

Engineering Contradiction:
Improvedisplay seamless bendingVSAvoiddisplay element integrity
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

The patent creates a localized flexible zone at the edge by removing the second inorganic insulating layer only in the edge bending area, allowing this specific region to accommodate bending stresses while the rest of the device maintains its structural integrity for reliable display element protection.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent proactively designs the edge bending area with a modified stack structure before the bending operation, creating a stress-absorbing zone that prevents damage to the display elements during subsequent bending or folding operations.

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

3Strength

If multiple etching processes are used to form different stack structures in different areas, then the bending stress distribution is optimized, but the manufacturing time and cost increase

Engineering Contradiction:
Improvestress distribution optimizationVSAvoidmanufacturing efficiency
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The patent merges the formation of the first inorganic insulating layer and the second inorganic insulating layer into a single etching process by using a combined mask pattern that defines both layers simultaneously. This approach maintains the differentiated stack structures needed for stress optimization while reducing the number of separate etching steps required.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3188269B1Flexible organic light emitting diode display having edge bending structure
Publication Date: 2022.06.08 LG DISPLAY CO LTD
  • EP3188269B1 patent drawingFigure 1
  • EP3188269B1 patent drawingFigure 2
  • EP3188269B1 patent drawingFigure 3

AI summary

The present disclosure relates to a flexible organic light emitting diode display having edge bending structure. The present disclosure suggests an organic light emitting diode display comprising: a flexible plate (SUF) including a display area (AA), a non-display area (NA) surrounding the display area (AA), and an edge bending area (EBA) near the display area (AA) in the non-display area (NA); a first line (L1) disposed in the non-display area (NA) on the flexible plate (SUF); a first buffer layer (BF1) covering the first line (L1); a second line (L2) on the first buffer layer (BF1) in the non-display area (NA); a second buffer layer (BF2) covering the second line (L2); gate elements (GL, SG, DG, GP) disposed on the second buffer layer (BF2); an intermediate insulating layer (ILD) covering the gate elements (GL, SG, DG, GP); data elements (SS, SD, DS, DD, DL, DP, VDD, VDP), and a connecting electrode (CN) connecting the first line (L1) to the second line (L2) on the intermediate insulating layer (ILD); and a plurality of trenches (TR) disposed at the edge bending area (EBA) and penetrating the intermediate insulating layer (ILD), the second buffer layer (BF2) and the first buffer layer (BF1).