Transparent Conductive Sheet Lattice for Fast Large Touch Panels

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Solution Overview

Problem

Conventional touch panels with ITO electrodes face issues of high resistance and low current transfer rates, leading to slow response times, especially in larger devices, and those using thin metal wires suffer from opacity and visibility problems.

Innovation Solution

A touch panel design featuring conductive patterns formed on transparent substrates with thin metal wires arranged in specific lattice patterns and connections to reduce resistance and improve visibility, allowing for larger, more responsive capacitive touch panels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If ITO electrodes are used in touch panels, then transparency is maintained, but electrical resistance is high and response speed is slow

Engineering Contradiction:
ImprovetransparencyVSAvoidresponse speed
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The electrode is divided into multiple thin metal wire segments arranged in a lattice pattern, where each wire segment is connected to form a grid structure. This segmentation allows the electrode to achieve lower resistance through multiple parallel conduction paths while maintaining transparency through the spaces between the thin wire segments.

Inventive Principle:
Principle #1Segmentation

2Reliability

If thin metal wires are used to form electrodes, then electrical resistance is lowered, but transparency and visibility are compromised

Engineering Contradiction:
Improveresponse speedVSAvoidtransparency
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The metal wires are made sufficiently thin at the local level to allow light transmission, while the overall lattice structure provides adequate conductivity. The local wire diameter is optimized to balance transparency requirements with the need for sufficient conductive cross-section.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The electrode structure transitions from a conventional planar continuous film to a three-dimensional lattice structure with vertical spacing between wires. This dimensional change allows light to pass through the gaps while maintaining electrical conductivity through the wire network.

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

3Area of stationary object

If larger touch panel sizes are implemented, then device applicability is improved, but current transfer rate decreases and response speed slows

Engineering Contradiction:
Improvescreen sizeVSAvoidresponse speed
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The large-area electrode is segmented into multiple lattice units with interconnected thin metal wires. This creates numerous parallel current transfer paths across the large area, ensuring that current can be efficiently distributed and collected even over extended distances, thereby maintaining response speed despite increased panel size.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design achieves lower electrical resistance and improved visibility, enabling faster response times and larger screen sizes while maintaining transparency, addressing the limitations of previous technologies.

Implementation Method 1

A large number of lattices composed of thin wires of a metal (thin metal wires) can be arranged to form an electrode with a lowered surface resistance

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

the conductive pattern formed on the substrate can exhibit a lowered resistance and an improved visibility

Methodology Applied
Scientific EffectLight transmission: Light

Data Source

PatentEP2530560B1Conductive sheet, method for using conductive sheet, and touch panel
Publication Date: 2019.06.19 FUJIFILM CORP
  • EP2530560B1 patent drawingFigure 1
  • EP2530560B1 patent drawingFigure 2
  • EP2530560B1 patent drawingFigure 3

AI summary

A conductive sheet, method for using conductive sheet and touch panel, having a base substance (14A) and conductive parts (13A) formed on one of the principal surfaces of the base substance (14A). The conductive parts (13A) respectively extend in primary directions, and have two or more conductive patterns (26A) made from metal wires arranged in a second direction that is perpendicular to the first direction. The conductive pattern (26A) is constituted by serially connecting two or more large gratings (16A) in the first direction, and each of the large gratings (16A) is constituted by combining two or more small gratings (18). Around the edges of the large grating (16A), non-connective patterns (20A) are formed from metal wires which are not connected with the large gratings (16A).