Flexible Display EMI Shielding Tape for Narrow-Bezel Bending

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Solution Overview

Problem

Existing flexible electroluminescent display devices face challenges in reducing bezel area while maintaining display performance and preventing cracks due to bending, and require costly EMI shielding structures with inaccurate position alignment.

Innovation Solution

A flexible display device design incorporating a functional tape with EMI shielding and adhesive functions, applied between a cushion tape and a back plate, to reduce bezel width and improve EMI shielding efficiency at a lower cost, while securing the driver integrated circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If wirings and driving circuit are disposed in the bezel area, then the display device can be driven, but the bezel area cannot be reduced

Engineering Contradiction:

Improvebezel areaVSAvoiddriving function

Core Design Contradiction:

Area of stationary objectVSEase of operation

Solution Approach 1:

The patent moves the driving circuit from the traditional planar bezel area into the display area by utilizing the third dimension (depth/thickness) through a bent configuration. The circuit board is bent at a specific angle to fit within the display area, effectively transitioning the spatial arrangement from 2D to 3D, thereby reducing the bezel area while maintaining the driving function

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The driving circuit is nested within the display area by bending the circuit board to fit inside the display region. This nesting approach allows the driving circuit to occupy space that would otherwise be unused, eliminating the need for a separate bezel area while keeping both functions integrated

Inventive Principle:

Principle #7Nested doll (Nesting)

2Area of stationary object

If a flexible substrate is bent to reduce bezel area, then the bezel area is reduced, but cracks may occur in insulating layers and wirings

Engineering Contradiction:

Improvebezel areaVSAvoidcrack prevention

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

A cushion tape is placed at the bending position before the actual bending occurs. This cushioning element prevents cracks from forming in the insulating layers and wirings by absorbing the stress concentrated at the bending location, thereby maintaining reliability while enabling the flexible substrate to be bent for bezel reduction

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The cushion tape acts as an intermediary element between the flexible substrate and the bending stress. It mediates the mechanical stress distribution, preventing direct stress concentration on the insulating layers and wirings, thus avoiding crack formation while allowing the bending necessary for bezel area reduction

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a micro-coating layer is applied to adjust the neutral surface, then crack prevention is improved, but the thickness of the bending area increases

Engineering Contradiction:

Improvecrack preventionVSAvoidthickness of bending area

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Instead of applying a micro-coating layer to adjust the neutral surface, the patent uses a cushion tape placed beforehand at the bending position. This alternative approach provides crack prevention through mechanical cushioning rather than through neutral surface adjustment, thereby avoiding the increase in thickness that would result from adding a micro-coating layer

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Object-affected harmful factors

If an additional EMI shielding sheet is applied, then EMI shielding is provided, but position alignment becomes inaccurate and costs increase

Engineering Contradiction:

ImproveEMI shieldingVSAvoidposition alignment

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The EMI shielding function is merged with the existing cushion tape by forming a conductive layer on the cushion tape itself. This integration eliminates the need for a separate EMI shielding sheet, thereby maintaining accurate position alignment while providing effective EMI shielding and reducing overall cost

Inventive Principle:

Principle #5Merging (Combining)

5Object-affected harmful factors

If an expensive material is used for EMI shielding, then EMI shielding performance is improved, but component and module costs increase

Engineering Contradiction:

ImproveEMI shielding performanceVSAvoidcost

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

Instead of using expensive materials for EMI shielding, the patent employs a cost-effective conductive material formed on the cushion tape. This approach provides sufficient EMI shielding performance while significantly reducing the cost of components and modules by avoiding expensive shielding materials

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS12183727B2Flexible display device

Publication Date: 2024.12.31 LG DISPLAY CO LTD

AI summary

A flexible display device may include a display panel including a display area and a bending area extending from one side of the display area to be bent, a back plate disposed on a rear surface of the display panel, a cushion tape disposed on a rear surface of the back plate, a driver integrated circuit (IC) disposed in a pad portion extending from the bending area, and a functional tape adhered between the cushion tape and the back plate and disposed to face the driver integrated circuit, so that effects capable of improving an EMI shielding function with a low cost, together with an adhesive function, and deriving an optimum efficiency, may be provided.