Flexible Circuit Board Shielding for Touch Display Ghost Points

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Solution Overview

Problem

The FMLOC technology in touch display devices experiences interference issues, leading to 'ghost points' due to parasitic capacitance changes between the flexible circuit board and the chip on film, which affects signal transmission and display quality.

Innovation Solution

A flexible circuit board design with a first shielding layer electrically connected to the shielding lines, positioned on a side of the first routing portion distal to the base plate, and a second shielding layer connected to the ground line, both with insulating layers to prevent signal interference and maintain stable parasitic capacitance, reducing 'ghost points' and enhancing signal integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the flexible circuit board is positioned close to the chip on film to reduce distance, then signal transmission efficiency is improved, but parasitic capacitance changes occur causing ghost points

Engineering Contradiction:

Improvesignal transmission efficiencyVSAvoidsignal stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

A shielding layer is introduced as an intermediary component between the flexible circuit board and the chip on film. This shielding layer acts as a mediator that blocks electromagnetic interference and stabilizes parasitic capacitance, allowing the flexible circuit board to remain close to the chip for efficient signal transmission while preventing ghost points caused by capacitance fluctuations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful effect of parasitic capacitance into a beneficial shielding mechanism. By introducing a grounded shielding layer, the parasitic capacitance is stabilized and controlled, transforming the potential source of ghost points into a protective element that improves signal integrity while maintaining close proximity between components.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Volume of moving object

If the flexible circuit board is positioned close to the chip on film, then device thickness is reduced, but electromagnetic interference increases causing signal distortion

Engineering Contradiction:

Improvedevice thicknessVSAvoidelectromagnetic interference

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If shielding layers are added to reduce interference, then signal integrity is improved, but device complexity increases

Engineering Contradiction:

Improvesignal integrityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shielding layer is merged with the flexible circuit board structure, forming an integrated design where the shielding function is incorporated into the existing circuit board layers. This combination approach improves signal integrity while minimizing the increase in device complexity by reusing existing structural elements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shielding layer serves multiple functions simultaneously: it provides electromagnetic shielding, stabilizes parasitic capacitance, and acts as a structural support element. This multi-functionality reduces the need for additional separate components, thereby improving signal integrity without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution effectively reduces signal interference and maintains stable parasitic capacitance, preventing 'ghost points' and improving the touch display panel's performance by providing electromagnetic shielding and protecting against short circuits.

Implementation Method 1

a first shielding layer electrically connected to the shielding lines and insulated and spaced from the touch lines, wherein the first shielding layer is in the first routing region and arranged on a side of the first routing portion distal to the base plate

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

touch lines and shielding lines on the base plate and insulated and spaced from each other

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS11592928B2Flexible circuit board, driving structure and display device

Publication Date: 2023.02.28 CHENGDU BOE OPTOELECTRONICS TECH CO LTD

AI summary

The present disclosure provides a flexible circuit board, a driving structure and a display device. The flexible circuit board includes: a base plate, including a bonding region and a first routing region between the bonding region and the first edge, touch lines and shielding lines on the base plate and insulated and spaced from each other, and the touch lines includes a first routing portion in the first routing region; wherein the flexible circuit board further includes: a first shielding layer electrically connected to the shielding lines and insulated and spaced from the touch lines, wherein the first shielding layer is in the first routing region and on a side of the first routing portion distal to the base plate, and an orthographic projection of the first shielding layer on the base plate covers an orthographic projection of the first routing portion on the base plate.