Touch Panel Sensing Electrode with Buffer Layers

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Solution Overview

Problem

Indium tin oxide (ITO) used in touch panels is costly, prone to physical damage, and unsuitable for flexible devices due to its characteristics, and mesh electrodes made of fine conductive wires are visible, leading to visibility issues and high resistance, especially in large-size touch panels.

Innovation Solution

A touch panel design featuring a sensing electrode with a conductive pattern hidden in the active area, utilizing a first and second buffer layer to prevent over-etching and delamination, reduce visibility, and improve adhesive strength, while maintaining low resistance and high printing quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If mesh electrodes made of fine conductive wires are used, then the electrode pattern visibility is reduced, but the resistance increases especially in large-size touch panels

Engineering Contradiction:
Improveelectrode pattern visibilityVSAvoidelectrode resistance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent uses a composite structure combining metal electrode layer with buffer layers (organic material layer and inorganic material layer). This composite material approach allows the metal to provide low resistance while the buffer layers and overlying layers hide the pattern visibility, achieving both low resistance and pattern hiding in large-size touch panels

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent introduces buffer layers as intermediary elements between the metal electrode layer and the environment. These buffer layers (organic and inorganic materials) act as mediators that prevent direct light reflection from the metal wires while maintaining electrical conductivity, thus reducing visibility without significantly increasing resistance

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If ITO is used as transparent electrode, then the fabrication is simple and sensing power is good, but the cost is high and the electrode is easily damaged by bending

Engineering Contradiction:
Improvefabrication simplicityVSAvoidelectrode durability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces expensive ITO with metal materials that can be deposited more cheaply. While metal alone would be damaged by bending, the patent uses the metal in conjunction with buffer layers that protect it, effectively creating a durable composite structure that is both cost-effective and reliable

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent employs thin film structures with buffer layers that provide flexibility and protection. The organic material layer and inorganic material layer act as flexible protective shells that allow the metal electrode to bend without damage, making the touch panel suitable for flexible devices

Inventive Principle:
Principle #30Flexible shells and thin films

3Object-affected harmful factors

If additional antireflection layers are applied to mesh electrodes, then the pattern visibility is reduced, but the device complexity increases

Engineering Contradiction:
Improvelight reflectionVSAvoidlayer structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The buffer layers in the patent serve multiple functions simultaneously: they act as adhesion promoters between layers, provide pattern hiding by reducing light reflection, and protect the metal electrode from oxidation and damage. This multi-functionality reduces the need for separate dedicated antireflection layers, thereby limiting the increase in device complexity

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

Data Source

PatentEP2784639B1Touch panel and touch device with the same
Publication Date: 2021.06.30 LG INNOTEK CO LTD
  • EP2784639B1 patent drawingFigure 1
  • EP2784639B1 patent drawingFigure 2~3
  • EP2784639B1 patent drawingFigure 4~6

AI summary

A touch panel (10) includes a substrate (100); and a sensing electrode (200;201) with a conductive pattern on the substrate (100), wherein the sensing electrode (200;201) includes: an electrode layer (211;222); and a first buffer layer (223;312;400;12) on the electrode layer (211;222).