Light Emitting Device Stacked Wavelength Conversion Layers
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Solution Overview
Problem
Existing light emitting devices face challenges in improving light extraction efficiency while minimizing leakage of unconverted wavelength light and color unevenness.
Innovation Solution
A light emitting device design featuring a base member, a light emitting element, a light reflecting member, and a light-transmissive stacked layer with alternating first and second light-transmissive layers and wavelength conversion layers, which reduces unconverted light leakage and color unevenness by optimizing light extraction and wavelength conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single wavelength conversion layer is used, then the device structure is simple, but light extraction efficiency is insufficient and color unevenness occurs
Solution Approach 1:
The wavelength conversion layer is divided into multiple stacked layers (first wavelength conversion layer and second wavelength conversion layer) with different phosphor materials and conversion characteristics. This segmentation allows each layer to convert specific wavelength ranges independently, improving overall light extraction efficiency while maintaining uniform color distribution across the emission surface.
Solution Approach 2:
The patent transitions from a single-layer to a multi-layer stacked structure, adding the vertical dimension to the wavelength conversion process. By stacking multiple wavelength conversion layers with different phosphor compositions at different heights above the LED chip, the device achieves superior light extraction efficiency and color uniformity without significantly increasing lateral device complexity.
2Productivity
If multiple wavelength conversion layers are stacked, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
Multiple wavelength conversion layers are merged into a single integrated stacked structure that functions as one unified optical component. The first and second wavelength conversion layers are combined with the light-transmissive layer to form an integrated assembly that achieves enhanced light extraction efficiency while presenting a compact, manageable structure rather than separate complex components.
Solution Approach 2:
The patent employs composite phosphor materials with different conversion characteristics in each wavelength conversion layer. By using composite materials with complementary emission spectra and conversion efficiencies, the stacked structure achieves superior overall performance while managing the complexity through material science rather than purely structural complexity.
3Productivity
If wavelength conversion layers are optimized for efficiency, then light flux improves, but leakage of unconverted light increases
Solution Approach 1:
Each wavelength conversion layer is designed with localized optical properties tailored to its specific position and function. The first wavelength conversion layer contains phosphors optimized for converting blue light to green wavelengths, while the second layer contains phosphors optimized for converting to red or yellow wavelengths. This local optimization of conversion characteristics ensures efficient light flux generation while minimizing unconverted light leakage by matching each layer's conversion profile to the spectral requirements at that position.
Solution Approach 2:
The patent optimizes parameters such as phosphor concentration, particle size distribution, and layer thickness for each wavelength conversion layer to maximize conversion efficiency. By carefully controlling these parameters, each layer achieves high conversion efficiency that increases overall light flux while minimizing the amount of unconverted light that would otherwise leak from the device.
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 enhances light extraction efficiency and reduces color unevenness, improving light flux and chromaticity distribution, allowing for more efficient and uniform light emission.
Implementation Method 1
a light reflecting member disposed at a side surface side of the light emitting element
Implementation Method 2
a first wavelength conversion layer disposed on the first light-transmissive layer, a second light-transmissive layer disposed on the first wavelength conversion layer, and a second wavelength conversion layer disposed on the second light-transmissive layer
Data Source
AI summary
Provided is a light emitting device capable of further improving light extraction efficiency while reducing leakage of wavelength unconverted light or color unevenness of the light. The light emitting device includes: a base member; a light emitting element mounted on the base member; a light reflecting member disposed at a side surface side of the light emitting element; and a light-transmissive stacked layer covering at least an upper surface of the light emitting element, wherein the light-transmissive stacked layer includes a first light-transmissive layer, a first wavelength conversion layer disposed on the first light-transmissive layer, a second light-transmissive layer disposed on the first wavelength conversion layer, and a second wavelength conversion layer disposed on the second light-transmissive layer.