OLED Protection Layer Corner Radius Design

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Solution Overview

Problem

In organic light emitting diode (OLED) devices, the small radius of the corner portion of the protection layer allows moisture to permeate into the display area, reducing the device's lifetime and increasing the bezel size when attempting to prevent defects.

Innovation Solution

The OLED features a protection layer with a round corner, where the maximum radius of the corner is determined based on the distance between the protection layer and the display region, set to at least 0.1 mm, ensuring effective moisture blocking while minimizing the bezel size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the radius of the corner portion of the protection layer is increased to prevent moisture permeation, then the reliability of the OLED is improved, but the bezel size increases

Engineering Contradiction:
Improvemoisture protectionVSAvoidbezel size
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The protection layer is designed with different corner radius values for different corners. Specifically, the first and second corners have a first radius, while the third and fourth corners have a second radius that is smaller than the first radius. This local differentiation allows optimal moisture protection at critical corners while minimizing the overall extension into the non-display region, thus reducing bezel size.

Inventive Principle:
Principle #3Local quality

2Length of stationary object

If the radius of the corner portion of the protection layer is decreased to reduce bezel size, then the manufacturing cost is reduced, but moisture permeation occurs causing element defects

Engineering Contradiction:
Improvebezel sizeVSAvoidelement protection
Core Design Contradiction:
Length of stationary objectVSReliability

Solution Approach 1:

Different corners of the protection layer are assigned different radius values based on their specific positions and moisture exposure risks. The first and second corners have a larger first radius to provide enhanced protection, while the third and fourth corners have a smaller second radius. This localized quality adjustment ensures adequate protection where needed while minimizing unnecessary extension in other areas.

Inventive Principle:
Principle #3Local quality

3Reliability

If the extension width of the protection layer is increased to ensure complete coverage, then the moisture blocking performance is improved, but the area of the non-display region increases

Engineering Contradiction:
Improvemoisture blockingVSAvoidnon-display region area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The protection layer employs asymmetric corner radii where the first radius at certain corners provides extended coverage for enhanced moisture blocking, while the smaller second radius at other corners reduces the overall area occupation. This local differentiation optimizes the balance between moisture blocking performance and non-display region area.

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS9385344B2Organic light emitting diode device and method of manufacturing the same
Publication Date: 2016.07.05 LG DISPLAY CO LTD

AI summary

An organic light emitting diode device includes an array substrate including a display region where a plurality of pixel regions each include a light emitting diode, and a non-display region surrounding the display region; and a protection layer covering the display region, extending to the non-display region, and including a round corner, wherein a maximum of a radius of the corner of the protection layer is determined according to a distance between a side of the protection layer and a side of the display region corresponding to the side of the protection layer, and the radius of the corner is at least 0.1 mm.