Flexible Touch Panel Wiring Stress Distribution

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Solution Overview

Problem

Flexible organic light emitting display devices face issues with touch panel wiring cracks and reliability due to bending or folding, leading to defects in touch sensing.

Innovation Solution

A flexible touch panel structure featuring a mesh-type wiring arrangement with transparent capping electrodes covering multiple intersection points, bridge electrodes, and connection electrodes, which distributes stress and prevents cracking, ensuring reliable touch detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the organic light emitting display device is implemented as a flexible device, then the device achieves bendability and slim thickness, but electrodes or wirings corresponding to a folding or bending axis may be cut and thereby defects in sensing touch are observed

Engineering Contradiction:

ImproveflexibilityVSAvoidtouch sensing reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The touch panel is divided into multiple blocks (first block array and second block array) with bridge electrodes connecting adjacent blocks. This segmentation allows the structure to accommodate bending without continuous wiring across the fold, preventing wire cuts while maintaining touch sensing functionality across segmented regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The wiring structure transitions from a planar two-dimensional arrangement to a three-dimensional configuration with bridge electrodes positioned at facing parts of adjacent blocks and connection electrodes in different layers. This vertical stacking and spatial distribution prevent wiring interference during folding by utilizing the third dimension.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If the touch panel is located on a surface of the organic light emitting display device that a user contacts, then the device provides touch detection function, but the touch panel becomes vulnerable to impact

Engineering Contradiction:

Improvetouch detection functionVSAvoidimpact vulnerability

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent employs a flexible base substrate with a mesh-type wiring structure that can deform under impact without cracking. The transparent capping electrodes and bridge electrodes are designed to flex with the substrate, distributing impact stress across the flexible structure rather than concentrating it on rigid wiring, thereby maintaining touch detection capability after impact.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS10168813B2Flexible touch panel and organic light emitting display device using the same

Publication Date: 2019.01.01 LG DISPLAY CO LTD

AI summary

Disclosed are a flexible touch panel, a structure of which is changed to prevent cracks in touch wirings, and an organic light emitting display device using the same. The flexible touch panel includes transparent capping electrodes including at least three intersection points between first wirings and second wirings in each of adjacent first blocks and thus overlapping bridge electrodes.