Flexible Display Bridge Wire Traces for Inactive Area Reduction

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Solution Overview

Problem

Flexible displays face challenges in minimizing inactive areas, which contribute to bulkiness and aesthetic issues, while also being fragile due to small component dimensions and mechanical stresses during bending, leading to potential component failure and performance issues.

Innovation Solution

A flexible display apparatus with a base layer featuring thin-film transistors (TFTs) for OLED elements, conductive lines separated into parts with a bridge in a non-display area to suppress corrosion and provide electrical connection, and strain-reducing trace designs for conductive lines to manage bend stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If components are placed on the display panel in the inactive area, then functionality is provided, but the inactive area size increases making the display bulky and aesthetically unappealing

Engineering Contradiction:
ImprovefunctionalityVSAvoidinactive area size
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent moves components from the two-dimensional plane of the display panel surface to a three-dimensional configuration by bending the flexible substrate. The inactive area is folded underneath the active area, effectively hiding it from the front view and reducing its visible footprint while maintaining all necessary functional components.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The flexible substrate is bent into a curved or folded configuration, transforming the flat inactive area into a three-dimensional structure that can be positioned behind the active area. This curvature allows the inactive area to be concealed while preserving component functionality.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Shape

If the flexible display is bent to reduce inactive area visibility, then aesthetic appearance improves, but mechanical stress causes component failure and reliability issues

Engineering Contradiction:
Improveaesthetic appearanceVSAvoidcomponent reliability
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

The conductive lines are divided into multiple separate segments rather than continuous traces. This segmentation allows each segment to independently accommodate bending stress without transmitting mechanical strain across the entire conductive path, thereby preventing crack formation and maintaining electrical connectivity during flexing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Insulation layers are introduced as intermediary structures between conductive elements and the bending interface. These insulation layers act as protective mediators that cushion mechanical stress and prevent direct contact between conductive lines and sources of mechanical degradation, thereby enhancing component reliability during bending operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If conductive lines are made thin to reduce mechanical stress during bending, then flexibility improves, but corrosion resistance decreases leading to electrical connectivity failures

Engineering Contradiction:
ImproveflexibilityVSAvoidcorrosion resistance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs composite material structures for conductive lines, combining multiple materials with complementary properties. This composite construction provides both the flexibility needed for bending and the corrosion resistance required for long-term reliability, resolving the trade-off between thin-line flexibility and corrosion protection.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

Insulation layers serve as protective intermediaries that shield thin conductive lines from corrosive environments. These intermediary layers prevent direct exposure of the thin conductive traces to moisture and oxygen, thereby maintaining electrical connectivity without requiring thicker, less flexible conductive structures.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Area of stationary object

If the inactive area is minimized by bending, then screen-to-bezel ratio improves, but manufacturing precision requirements increase due to small component dimensions

Engineering Contradiction:
Improvevisible inactive areaVSAvoidcomponent placement precision
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The display structure is segmented into distinct functional zones (active area, inactive area, bending zones) with clearly defined boundaries. This segmentation allows for modular manufacturing and assembly, reducing the overall precision requirements by enabling separate fabrication of components that are later integrated through standardized connection interfaces.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3231013B1Flexible display device with briged wire traces
Publication Date: 2022.03.16 LG DISPLAY CO LTD
  • EP3231013B1 patent drawingFigure 1
  • EP3231013B1 patent drawingFigure 2
  • EP3231013B1 patent drawingFigure 3A

AI summary

There is provided a flexible display having a plurality of innovations configured to allow bending of a portion or portions to reduce apparent border size and/or utilize a side surface of an assembled flexible display. A flexible display apparatus comprises a flexible base layer, a plurality of thin-film transistors (TFTs) on the flexible base layer configured to activate a plurality of organic light-emitting diode (OLED) elements in a display area of the flexible display apparatus, a conductive line having a first part extended to a scribed or a chamfered edge of the flexible base layer and a second part connected to at least one of the plurality of TFTs on the flexible base layer, wherein the first part and the second part of the conductive line are separated from each other within a first metal layer, and a bridge connecting the first part and second part of the conductive line, wherein the bridge is provided in a second metal layer at a non-display area of the flexible display apparatus and in contact with the first and second parts of the conductive line through contact holes in one or more insulation layers disposed between the first metal layer and the second metal layer.