OLED Encapsulation with Graded Refractive Index

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Solution Overview

Problem

OLED display panels face interference from ambient light due to reflection, which reduces light extraction efficiency and makes it difficult to achieve a thin display panel, as traditional polarizers increase thickness and affect light extraction.

Innovation Solution

A display panel with an encapsulation structure featuring a first encapsulation film layer composed of inorganic layers with sequentially increasing refractive indices, which adjusts the angle of ambient light to reduce reflection, eliminating the need for a polarizer and maintaining light extraction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a polarizer is used to reduce ambient light reflection, then ambient light interference is reduced, but the display panel thickness increases and light extraction efficiency decreases

Engineering Contradiction:

Improveambient light interferenceVSAvoiddisplay panel thickness

Core Design Contradiction:

Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The encapsulation structure is divided into multiple inorganic layers with different refractive indices (first, second, and third inorganic layers). Each layer segment handles a portion of the light reflection reduction function, collectively achieving the anti-reflection effect without requiring a thick polarizer layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the refractive index parameter across different layers of the encapsulation structure. By creating a gradient of refractive indices from the first to the third inorganic layer, the structure optimizes light extraction and reduces ambient light reflection without increasing overall thickness.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If a polarizer is used to reduce ambient light reflection, then ambient light interference is reduced, but light extraction efficiency decreases

Engineering Contradiction:

Improveambient light interferenceVSAvoidlight extraction efficiency

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

Different inorganic layers are positioned at specific locations within the encapsulation structure based on their refractive index properties. The first inorganic layer with higher refractive index is positioned closer to the light-emitting device, while layers with lower refractive indices are positioned outward, creating an optimized gradient structure for both light extraction and reflection reduction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The encapsulation structure uses a composite of multiple inorganic materials with different refractive indices. This composite structure combines the benefits of each material's optical properties to achieve superior light extraction efficiency while maintaining effective ambient light rejection.

Inventive Principle:

Principle #40Composite materials

3Reliability

If traditional encapsulation structures are used, then the display panel is protected, but ambient light reflection interference remains high

Engineering Contradiction:

Improveprotection functionVSAvoidambient light reflection

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The encapsulation structure serves multiple functions simultaneously: it provides mechanical and environmental protection for the light-emitting device while also functioning as an optical management layer that reduces ambient light reflection and enhances light extraction. This multi-functionality eliminates the need for separate polarizer components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The multiple inorganic layers act as intermediary structures between the light-emitting device and the external environment. These layers mediate the interaction between emitted light and ambient light, optimizing both protection and optical performance through their graded refractive index structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 ambient light interference on OLED display panels without a polarizer, ensuring high light extraction efficiency and achieving a thinner display panel design.

Implementation Method 1

refractive indexes of the at least two inorganic layers sequentially increase in a direction close to the light-emitting device, the first encapsulation film layer is configured to adjust an angle of an ambient light incident on the light-emitting device

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS11581507B2Display panel and method for manufacturing same, and display apparatus

Publication Date: 2023.02.14 BOE TECHNOLOGY GROUP CO LTD

AI summary

A display panel is provided, which includes a base substrate, and a light-emitting device and an encapsulation structure sequentially arranged on the base substrate. The encapsulation structure includes at least one first encapsulation film layer, the first encapsulation film layer includes at least two inorganic layers arranged in a stack, and refractive indexes of the at least two inorganic layers sequentially increase in a direction close to the light-emitting device. The first encapsulation film layer is configured to adjust an angle of an ambient light incident on the light-emitting device to reduce the ambient light reflected from the display panel.