Touch Sensor External Connection Terminals for Spark Failure Prevention

Solution Overview

Problem

The existing touch sensor films face failures due to spark generation during manufacturing, particularly in narrow frame patterns, where the high surface pressure during rolling leads to peeling charging and potential differences in conductive patterns, causing disconnections between the external connection terminals and the FPC.

Innovation Solution

A touch sensor pattern with external connection terminals having a first fine metal wire with a smaller line width than the lead wires, and an area per unit length that is 5.5 times or less than the lead wires, along with a second fine metal wire of 5 μm or more, forming a mesh-like or linear pattern to reduce the contact area and improve connection reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the line width of lead wires and the interval between adjacent lead wires are reduced to reduce the area of the bundle of lead wires, then the area of the decorative printing portion is reduced and the area of the image display unit is widened, but the surface pressure during rolling increases leading to peeling charging and spark generation causing conductive pattern break

Engineering Contradiction:

Improvearea of decorative printing portionVSAvoidspark generation causing conductive pattern break

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by making the external connection terminal have a different line width (5 μm or more) than the lead wires (narrower line width). This local differentiation allows the terminal portion to have higher surface pressure resistance while maintaining overall frame narrowing. The external connection terminal is specifically designed with greater line width to prevent peeling charging and spark generation during rolling, while other portions can maintain reduced dimensions for frame narrowing.

Inventive Principle:

Principle #3Local quality

2Area of stationary object

If the line width of lead wires is reduced to reduce the area of the bundle of lead wires, then the area of the decorative printing portion is reduced, but the connection reliability between external connection terminal and FPC deteriorates

Engineering Contradiction:

Improvearea of decorative printing portionVSAvoidconnection reliability between external connection terminal and FPC

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent applies local quality by making the external connection terminal have a different line width (5 μm or more) than the lead wires (narrower line width). This local differentiation allows the terminal portion to have higher surface pressure resistance while maintaining overall frame narrowing. The external connection terminal is specifically designed with greater line width to prevent peeling charging and spark generation during rolling, while other portions can maintain reduced dimensions for frame narrowing.

Inventive Principle:

Principle #3Local quality

3Area of stationary object

If the interval between adjacent lead wires is reduced to reduce the area of the bundle of lead wires, then the area of the decorative printing portion is reduced, but the insulation between adjacent lead wires becomes insufficient increasing the risk of electrical interference

Engineering Contradiction:

Improvearea of decorative printing portionVSAvoidelectrical interference between adjacent lead wires

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by making the external connection terminal have a different line width (5 μm or more) than the lead wires (narrower line width). This local differentiation allows the terminal portion to have higher surface pressure resistance while maintaining overall frame narrowing. The external connection terminal is specifically designed with greater line width to prevent peeling charging and spark generation during rolling, while other portions can maintain reduced dimensions for frame narrowing.

Inventive Principle:

Principle #3Local quality

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

This configuration suppresses spark failures and enhances the connection reliability between the external connection terminals and the FPC, reducing the likelihood of disconnections and improving rub resistance during the manufacturing process.

Implementation Method 1

the high surface pressure during rolling leads to peeling charging and potential differences in conductive patterns, causing disconnections

Methodology Applied

Scientific EffectPeeling charging: Triboelectric Effect

Implementation Method 2

Due to this potential difference, spark is generated in the conductive patterns

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentUS11635864B2Touch sensor pattern

Publication Date: 2023.04.25 FUJIFILM CORP

AI summary

A touch sensor pattern includes: a plurality of detection electrodes; a plurality of lead wires that are connected to the plurality of detection electrodes and a plurality of external connection terminals that are connected to the plurality of lead wires, in which each of the plurality of external connection terminals includes a first fine metal wire having a smaller line width than each of the plurality of lead wires, and an area per unit length of at least a part of each of the plurality of external connection terminals in an extension direction in a plan view is 5.5 times or less an area per unit length of each of the plurality of lead wires in a plan view.