Wavelength Conversion Layer Filling Particles Adhesion

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Solution Overview

Problem

The adhesion between the wavelength conversion layer and the light emitting element in existing light emitting devices is poor due to variations in particle size and aspect ratio of wavelength conversion particles, leading to potential peeling and reduced light extraction efficiency.

Innovation Solution

A light emitting device with a wavelength conversion layer comprising first and second wavelength conversion particles and filling particles, where the filling particles have smaller sizes and aspect ratios than the conversion particles, and are dispersed among them to improve adhesion, using an electrodeposition method with aluminum-containing materials to enhance bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wavelength conversion particles are used to form a wavelength conversion layer, then wavelength conversion function is achieved, but adhesion between the layer and light emitting element deteriorates due to particle size variations

Engineering Contradiction:

Improveadhesion between wavelength conversion layer and light emitting elementVSAvoidparticle size uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by introducing filling particles with specific properties (smaller size, spherical shape, aluminum content) into specific regions (gaps between larger wavelength conversion particles) to locally enhance adhesion and fill voids, while maintaining the overall wavelength conversion function of the larger particles

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining two types of particles with different properties: larger wavelength conversion particles (for optical function) and smaller filling particles (for adhesion and gap filling). This composite structure creates a more robust wavelength conversion layer with improved adhesion to the light emitting element

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If larger wavelength conversion particles are used, then light extraction efficiency improves, but adhesion deteriorates due to fewer contact points

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidadhesion strength

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies the nested doll principle by placing smaller filling particles into the gaps and voids between larger wavelength conversion particles, creating a nested hierarchical structure that maximizes space utilization, increases contact points, and enhances adhesion while preserving the light extraction efficiency of the larger particles

Inventive Principle:

Principle #7Nested doll (Nesting)

3Adaptability or versatility

If wavelength conversion particles with varying aspect ratios are used, then manufacturing flexibility improves, but layer density and adhesion worsen

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidwavelength conversion layer density

Core Design Contradiction:

Adaptability or versatilityVSVolume of stationary object

Solution Approach 1:

The patent applies parameter changes by controlling the aspect ratio of filling particles to be smaller than that of wavelength conversion particles, and by adjusting the aluminum content parameters of both particle types, to optimize the packing density and adhesion properties of the composite wavelength conversion layer

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

The configuration improves the adhesion between the wavelength conversion layer and the light emitting element, reducing the risk of peeling and enhancing light extraction efficiency by increasing the number of contact points and density of the wavelength conversion layer.

Implementation Method 1

light emitted from the light emitting element is subject to wavelength conversion by the fluorescent material layer

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 2

fluorescent material particles are deposited on a light emitting element to form a fluorescent material layer by a so-called electrodeposition method

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Data Source

PatentUS10230025B2Light emitting device having wavelength conversion layer with filling particles

Publication Date: 2019.03.12 NICHIA CORP

AI summary

A light emitting device includes a light emitting element and a wavelength conversion layer covering the light emitting element. The wavelength conversion layer includes first wavelength conversion particles, second wavelength conversion particles, and filling particles. The first wavelength conversion particles contains aluminum. The second wavelength conversion particles have outer surfaces covered with covering material which contains aluminum. The filling particles contain aluminum. The filling particles are provided among the first wavelength conversion particles and the second wavelength conversion particles. The filling particles have particle sizes smaller than particle sizes of the first wavelength conversion particles and particle sizes of the second wavelength conversion particles. The filling particles have aspect ratios smaller than aspect ratios of the first wavelength conversion particles and aspect ratios of the second wavelength conversion particles.