Chip on Film with Electromagnetic Wave Blocking Layer

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Solution Overview

Problem

Flexible display devices face challenges with electromagnetic interference (EMI) due to high-speed data transferring wires, which are difficult to manage with existing chip on film (COF) technologies, and the use of electromagnetic interference prevention tapes increases device thickness.

Innovation Solution

A chip on film with a metal-plated electromagnetic wave blocking layer, including a mesh portion at bending areas, is designed to minimize EMI by blocking electromagnetic waves and improving impedance matching, while maintaining flexibility and reducing thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If electromagnetic interference prevention tape is used to block electromagnetic waves, then electromagnetic interference is reduced, but device thickness is increased

Engineering Contradiction:
Improveelectromagnetic interferenceVSAvoiddevice thickness
Core Design Contradiction:
Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The patent applies a thin film electromagnetic wave blocking layer formed by metal plating on the COF substrate. This thin film structure provides electromagnetic interference blocking functionality while maintaining the flexibility and thinness of the flexible display device, avoiding the thickness increase associated with traditional electromagnetic interference prevention tapes.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the physical state and properties of the blocking layer by using metal plating to create a conductive electromagnetic wave blocking layer. This parameter change enables the layer to effectively block electromagnetic waves while maintaining a thin profile, resolving the contradiction between EMI protection and device thickness.

Inventive Principle:
Principle #35Parameter changes

2Speed

If wire layer is formed to transfer high-speed data, then data transfer speed is improved, but electromagnetic interference is increased

Engineering Contradiction:
Improvedata transfer speedVSAvoidelectromagnetic interference
Core Design Contradiction:
SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an electromagnetic wave blocking layer as an intermediary between the high-speed data transferring wire layer and the surrounding environment. This blocking layer acts as a shield that contains electromagnetic emissions from the high-speed wires while allowing the data transfer function to operate at high speeds without interference.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Length of stationary object

If single layer wire structure is used to maintain thin COF, then COF thickness is reduced, but impedance matching adjustment is limited

Engineering Contradiction:
ImproveCOF thicknessVSAvoidimpedance matching adjustment
Core Design Contradiction:
Length of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent employs a composite structure combining the wire layer with a metal-plated electromagnetic wave blocking layer on the COF substrate. This composite material approach enables both thin profile maintenance and improved impedance matching capability, as the metal plating provides additional degrees of freedom for impedance control while keeping the overall structure thin.

Inventive Principle:
Principle #40Composite materials

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 minimizes electromagnetic interference and improves electromagnetic susceptibility, allowing for thinner, more flexible display devices by blocking electromagnetic waves and alleviating tension at bending portions.

Implementation Method 1

forming an electromagnetic wave blocking layer under a driving film by a metal-plated layer to block an electromagnetic wave occurring in a wire layer

Methodology Applied
Scientific EffectElectromagnetic wave blocking: Faraday Cage

Implementation Method 2

The mesh portion may be formed on a bending portion of the driving film... alleviate tension of a bending portion and improve electromagnetic susceptibility

Methodology Applied
Scientific EffectStress distribution through mesh pattern:

Data Source

PatentEP2725881B1Chip on film and display device including the same
Publication Date: 2015.06.24 SAMSUNG DISPLAY CO LTD
  • EP2725881B1 patent drawingFigure 1
  • EP2725881B1 patent drawingFigure 2
  • EP2725881B1 patent drawingFigure 3

AI summary

A chip on film according to an exemplary embodiment includes: a driving film (10), a wire layer (20) formed on a first surface of the driving film (10), a driving chip (30) connected to the wire layer (20), and an electromagnetic wave blocking layer (50) formed on a second surface of the driving film (10), in which a mesh portion (51) may be formed on a portion of the electromagnetic wave blocking layer (50).