Centrifugal Sedimentation for LED Phosphor Layering

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Solution Overview

Problem

Conventional light emitting devices with fluorescent materials dispersed in resin suffer from reduced light extraction efficiency and color unevenness due to excessive wavelength conversion and varying resin amounts, leading to inconsistencies in light emission.

Innovation Solution

A light emitting device design where fluorescent material particles coated with inorganic particles are mixed with fillers and resin, and then centrifugally sedimented to form distinct layers, reducing excessive wavelength conversion and enhancing light extraction efficiency while minimizing color unevenness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If fluorescent material is dispersed in resin to convert wavelength, then white light emission is achieved, but light extraction efficiency decreases and color unevenness occurs

Engineering Contradiction:

Improvewhite light emissionVSAvoidlight extraction efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent divides the resin into multiple layers with different fluorescent material concentrations. The first resin layer has a higher concentration of fluorescent material than the second resin layer, creating a gradient structure that optimizes both wavelength conversion and light extraction efficiency, preventing color unevenness while maintaining brightness

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the resin are assigned different fluorescent material concentrations tailored to local optical requirements. The region closer to the light emitting element has higher concentration for effective wavelength conversion, while outer regions have lower concentration to minimize light attenuation and maintain extraction efficiency

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If fluorescent material concentration is increased to enhance wavelength conversion, then emission intensity improves, but light extraction efficiency and color uniformity deteriorate

Engineering Contradiction:

Improveemission intensityVSAvoidcolor uniformity

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The resin is segmented into multiple layers with progressively decreasing fluorescent material concentrations. This segmentation allows each layer to contribute optimally to emission intensity while the gradient structure prevents color unevenness, achieving both high brightness and uniform color distribution

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fluorescent material concentration parameter is varied systematically across different resin layers. By creating a concentration gradient from high near the light emitting element to low in outer layers, the patent achieves optimal wavelength conversion efficiency while maintaining color uniformity and preventing excessive light attenuation

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If resin amount varies in sealing process, then manufacturing flexibility is improved, but light emission consistency deteriorates

Engineering Contradiction:

Improvesealing flexibilityVSAvoidlight emission consistency

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The resin sealing is divided into multiple layers with controlled thicknesses and fluorescent material concentrations. This layered structure compensates for variations in total resin amount, ensuring consistent optical performance across different devices even when manufacturing conditions vary

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each resin layer is optimized with specific local properties (concentration, thickness) that compensate for overall resin amount variations. The gradient structure ensures that optical path differences are minimized, maintaining light emission consistency across devices with varying total resin quantities

Inventive Principle:

Principle #3Local quality

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 suppresses excessive wavelength conversion and color unevenness, improving light extraction efficiency and maintaining consistent color hue by controlling the deposition of fluorescent materials and fillers, thus enhancing the overall performance of the light emitting device.

Implementation Method 1

applying a centrifugal force to the sealed package so that the fluorescent powders and the fillers are pushed toward a bottom of the recess

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

a fluorescent material for converting it to light having a different wavelength may be used in combination with the light emitting element

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS8827759B2Method of manufacturing light emitting device

Publication Date: 2014.09.09 NICHIA CORP

AI summary

To make a light emitting device, a light emitting element is placed in a recess of a package, powders having a fluorescent material and coated with inorganic particles are provided, the fluorescent powders, fillers and a resin are mixed, the light emitting element placed in the recess of the package is sealed with the resin, and a centrifugal force is applied to the sealed package so that the fluorescent powders and the fillers sediment are pushed toward a bottom of the recess.