Bonding Layer Refractive Index for Display Light Extraction

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Solution Overview

Problem

Existing display apparatuses face challenges in achieving high light extraction efficiency while maintaining a large size and small thickness, which is crucial for providing precise and vivid colors.

Innovation Solution

The display apparatus incorporates a substrate with a pixel layer, an encapsulating member, a light modulating layer, a functional layer, and a bonding layer. The bonding layer, with a higher refractive index than the light modulating layer, fills openings in the light modulating layer and includes high refractive particles and scattered particles, enhancing light extraction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the display apparatus is made larger and thinner, then the display size increases while maintaining a compact profile, but the light extraction efficiency deteriorates

Engineering Contradiction:
Improvedisplay sizeVSAvoidlight extraction efficiency
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent changes the refractive index parameter by introducing a bonding layer with a higher refractive index than the light modulating layer. This parameter change creates a refractive index gradient that improves light extraction efficiency while allowing the display to maintain a thin profile and large size

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The bonding layer is formed as a composite material containing high refractive particles (such as metal oxides or nitrides) dispersed in a matrix material. This composite structure achieves the desired refractive index enhancement while maintaining mechanical compatibility and bonding functionality

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If the bonding layer has a higher refractive index to improve light extraction, then light extraction efficiency improves, but the device complexity increases

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoidstructure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The bonding layer serves multiple functions simultaneously: it bonds the light modulating layer to the functional layer, fills the openings in the light modulating layer, and provides refractive index enhancement for light extraction. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

By adjusting the refractive index parameter of the bonding layer through particle concentration and size control, the patent optimizes light extraction efficiency without requiring complex multi-layer structures or additional optical components

Inventive Principle:
Principle #35Parameter changes

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

This configuration significantly improves light extraction efficiency, leading to better color precision and vividness, while maintaining the desired size and thickness characteristics.

Implementation Method 1

the bonding layer has a refractive index that is greater than a refractive index of the light modulating layer

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

a lower end that is rounded to have a concave shape at a point at which a side surface of the light modulating layer meets an upper surface of the encapsulating member

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3836224B1Display apparatus
Publication Date: 2025.05.07 SAMSUNG DISPLAY CO LTD
  • EP3836224B1 patent drawingFigure 1
  • EP3836224B1 patent drawingFigure 2
  • EP3836224B1 patent drawingFigure 3

AI summary

A display apparatus includes a substrate, a pixel layer including a plurality of display devices on the substrate, an encapsulating member encapsulating the pixel layer, a light modulating layer on the encapsulating member, a functional layer on the light modulating layer, and a bonding layer located between the light modulating layer and the functional layer and to bond the light modulating layer and the functional layer, where the light modulating layer has openings corresponding to the plurality of display devices, and where the bonding layer fills the openings and has a refractive index that is greater than a refractive index of the light modulating layer.