Wavelength Conversion Structure With Dual Phosphor Layers
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Solution Overview
Problem
Conventional wavelength conversion structures in LED lighting, such as those using conformal and remote phosphor methods, face issues with light absorption by the LED chip and substrate, leading to reduced luminous efficiency and phosphor degradation due to high temperatures, as well as inefficient light emission directionality.
Innovation Solution
A wavelength conversion structure comprising a first phosphor layer with specific particle sizes and a second phosphor layer of different particle sizes, separated by a glue layer, which reduces light absorption and enhances light extraction efficiency by minimizing total internal reflection and scattering, and is designed to be thermally stable by not directly contacting the LED chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conformal coating method is used to coat phosphor directly on LED chip, then uniform thickness of phosphor layer is achieved, but light emitted from phosphor layer is absorbed by LED chip and support substrate reducing luminous efficiency
Solution Approach 1:
A transparent adhesive layer is introduced as an intermediary between the LED chip and the phosphor layer. This adhesive layer with optimized refractive index reduces light absorption by the LED chip and support substrate, thereby improving light extraction efficiency while maintaining the uniform thickness advantage of conformal coating.
2Manufacturing precision
If conformal coating method is used to coat phosphor directly on LED chip, then uniform thickness of phosphor layer is achieved, but high temperature during LED operation degrades phosphor layer affecting conversion efficiency
Solution Approach 1:
The transparent adhesive layer serves as a thermal buffer between the LED chip and phosphor layer, reducing direct thermal exposure to the phosphor particles and minimizing temperature-induced degradation of conversion efficiency.
3Ease of manufacture
If single layer phosphor structure is used, then simple manufacturing process is maintained, but light extraction efficiency is insufficient
Solution Approach 1:
The phosphor structure is divided into multiple layers with different particle sizes (e.g., first layer with smaller particles, second layer with larger particles). This segmentation improves light extraction efficiency through optimized light scattering and reduced total internal reflection, while still using straightforward deposition processes for each layer.
Solution Approach 2:
The multi-layer phosphor structure combines different particle sizes and compositions in specific arrangements, creating a composite system that enhances light extraction efficiency. The combination of smaller and larger particles in different layers provides complementary optical functions.
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 proposed structure increases light extraction efficiency by up to 4% compared to traditional methods, while maintaining phosphor stability and reducing thermal degradation, thereby improving the overall performance of light-emitting diodes.
Implementation Method 1
The phosphor absorbs the light emitted from the LED chip and is excited to emit a light having a wavelength different from that of the light emitted from the LED chip
Implementation Method 2
increases light extraction efficiency by up to 4% compared to traditional methods, while maintaining phosphor stability and reducing thermal degradation
Data Source
AI summary
A wavelength conversion structure comprises a first phosphor layer and a second phosphor layer formed on the first phosphor layer, wherein the first phosphor layer comprises a plurality of first phosphor particles, and the second phosphor layer comprises a plurality of second phosphor particles. The average particle size of the second phosphor particles is not equal to that of the first phosphor particles.