LED Display Overcoat Layer Scratch Prevention

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Solution Overview

Problem

The manufacturing process of LED display panels faces issues such as scratches and static electricity due to the tight attachment of a mask plate and TFT backplane during evaporation, leading to short circuits and damage to the circuit.

Innovation Solution

The implementation of an overcoat (OC) layer made from conductive materials like ITO, which is electrically connected to the cathode, shields the TFT backplane from scratches and reduces internal resistance, preventing short circuits and static electricity, and can also function as a light shield in top-emission mode to eliminate the need for black matrices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a mask plate is tightly attached to the TFT backplane during evaporation, then the light-emission layer can be precisely deposited, but scratches and static electricity damage occur to the circuit

Engineering Contradiction:
Improvelight-emission layer deposition precisionVSAvoidscratches and static electricity damage
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

An overcoat layer is introduced as an intermediary protective layer between the mask plate and the TFT backplane. This overcoat layer prevents direct contact and mechanical damage while still allowing the light-emission layer to be deposited through it, thus resolving the contradiction between precise deposition and preventing scratches/static electricity damage

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The overcoat layer is applied in advance before the evaporation process to provide protective cushioning to the TFT backplane. This pre-established protective layer absorbs mechanical stresses and prevents static electricity discharge during the subsequent mask evaporation process

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Manufacturing precision

If multiple evaporation and CVD processes are used to form the light-emission layer, then the light-emitting structure can be precisely formed, but strong static electricity is produced to damage the circuit

Engineering Contradiction:
Improvelight-emitting structure formation precisionVSAvoidstatic electricity
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The overcoat layer serves as a mediator that reduces friction and charge accumulation during the evaporation and CVD processes. By providing a protective interface, it prevents the generation of strong static electricity while maintaining the precision of the light-emitting structure formation

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The overcoat layer converts the potentially harmful evaporation and CVD processes into a beneficial outcome by controlling the deposition while minimizing static electricity generation. The process that could cause damage is transformed into a controlled manufacturing step with the protective overcoat in place

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

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 OC layer effectively prevents scratches and static electricity, reduces internal resistance, and in top-emission mode, saves manufacturing steps by eliminating the need for black matrices, enhancing the manufacturing process and reducing costs.

Implementation Method 1

an overcoat (OC) layer which is disposed between the TFT backplane and the light-emitting structure. The OC layer is configured to cover gate lines and data lines in a display area of the LED display panel

Methodology Applied
Scientific EffectElectrostatic shielding: Electrostatics

Implementation Method 2

The OC layer is made from crystallized ITO and electrically connected with the cathode

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3166148B1Light-emitting diode display panel and manufacturing method therefor, and display device
Publication Date: 2021.10.13 BOE TECHNOLOGY GROUP CO LTD
  • EP3166148B1 patent drawingFigure 1~2
  • EP3166148B1 patent drawingFigure 3

AI summary

A light-emitting diode (LED) display panel, a manufacturing method thereof and a display device are disclosed. The LED display panel comprises a thin-film transistor (TFT) backplane, a light-emitting structure and an overcoat (OC) layer (10). The OC layer (10) is disposed between the TFT backplane and the light-emitting structure and configured to cover gate lines (21) and data lines (22) in a display area of the LED display panel. The manufacturing process of the LED display panel adds the process of the OC layer (10) and hence can effectively avoid the scratches onto the TFT backplane caused by an evaporation mask plate when the light-emitting structure is formed and prevent the caused electrostatic problem.