LED Surface Light Source with Phosphor Laminate

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Solution Overview

Problem

Conventional surface light source devices using LEDs with a single phosphor, such as YAG:Ce, exhibit low color rendering properties due to limited wavelength distribution, which restricts the achievement of natural white light.

Innovation Solution

A surface light source device employing a color conversion laminate with multiple phosphor-mixed resin layers, including blue, green, and red emitting phosphors, strategically deposited to enhance color rendering index and conversion efficiency, utilizing phosphors like (Sr,Ca)5(PO4)3Cl:Eu2+, (Ba,Sr)2SiO4:Eu, and K5EuS(WO4)2.5+1.5S:Sm, mixed with epoxy or silicone resin, to produce white light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single phosphor (e.g., YAG:Ce) is used for wavelength conversion, then the device structure is simple, but the color rendering properties are poor due to limited wavelength distribution

Engineering Contradiction:

Improvecolor conversion structureVSAvoidcolor rendering properties

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The color conversion layer is segmented into multiple phosphor-mixed resin layers, each containing different phosphors with different wavelengths. This segmentation allows each layer to convert light at specific wavelengths, collectively achieving a broad spectrum with excellent color rendering properties while maintaining structural organization

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple phosphors with different emission characteristics are combined in a laminate structure, creating a composite color conversion system. This composite approach enables simultaneous conversion at multiple wavelengths, achieving both high color rendering index and efficient light conversion

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If multiple phosphor-mixed resin layers are deposited, then color rendering properties are improved, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvecolor rendering indexVSAvoiddeposition process

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

Phosphors are pre-mixed with resin materials to form phosphor-mixed resin layers before deposition. This preliminary preparation simplifies the deposition process, as pre-mixed layers can be applied more efficiently while ensuring uniform phosphor distribution, thereby reducing manufacturing complexity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention optimizes deposition parameters such as layer thickness, phosphor concentration, and deposition sequence to improve color rendering while controlling manufacturing complexity. By carefully adjusting these parameters, the system achieves high color rendering index without excessive process complexity

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If phosphor layers are strategically deposited based on wavelength conversion efficiency, then color conversion efficiency is improved, but the deposition process requires precise control

Engineering Contradiction:

Improvecolor conversion efficiencyVSAvoiddeposition order control

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

Different phosphor-mixed resin layers are deposited in specific sequences and positions based on their wavelength conversion characteristics. Each layer is placed optimally to maximize conversion efficiency of incident light, with lower wavelength phosphors positioned to convert first, creating local optimization throughout the laminate structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The optimal deposition sequence and layer configuration are predetermined based on wavelength conversion efficiency calculations. This preliminary design of the deposition process allows for systematic control, reducing the need for complex real-time adjustments during manufacturing while maintaining high conversion efficiency

Inventive Principle:

Principle #10Preliminary action

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 device achieves improved color rendering properties and increased color conversion efficiency by optimizing the deposition order of phosphor layers based on wavelength conversion efficiency and excitability, resulting in enhanced light intensity and overall brightness.

Implementation Method 1

a color conversion laminate formed by depositing a plurality of phosphor-mixed resin layers containing phosphors, the layers disposed at a top of the opening of the housing and providing light having different wavelengths

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 2

The color conversion layer 17 provides yellow light Y by converting a part of blue light B emitted from the LEDs 15

Methodology Applied

Scientific EffectWavelength conversion: Photoluminescence

Data Source

PatentUS7654681B2Surface light source device using light emitting diodes

Publication Date: 2010.02.02 SAMSUNG ELECTRONICS CO LTD

AI summary

A surface light source device using light emitting diodes, the device including: a housing having a top opening to emit light; a light emitting diode board disposed on an inner bottom surface of the housing, the board on which a plurality of light emitting diodes are arranged; and a color conversion laminate formed by depositing a plurality of phosphor-mixed resin layers containing phosphors, the layers disposed at a top of the opening of the housing and providing light having different wavelengths.