Light Extracting Structure for White LED Phosphor Uniformity
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Solution Overview
Problem
Existing white LED packages suffer from non-uniform phosphor distribution and light reflection issues, leading to wide color temperature variations and reduced efficiency due to the phosphor's larger distribution area and total reflection of converted light.
Innovation Solution
A light emitting device with a fluorescent layer and a light extracting structure that includes periodic or non-periodic patterns, using materials with different refractive indices to enhance light extraction efficiency and adjust emission distribution, thereby reducing color temperature variations and improving the efficiency of the white LED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the phosphor distribution area is made larger to cover the LED, then the LED area is improved, but the phosphor distribution uniformity deteriorates
Solution Approach 1:
The patent divides the phosphor layer into multiple discrete phosphor particles or granules distributed across the LED surface, rather than using a continuous phosphor coating. This segmentation allows each phosphor particle to be positioned independently, improving distribution uniformity while covering the required area. The phosphor particles are spaced apart to prevent aggregation and ensure even light conversion across the entire LED chip surface.
Solution Approach 2:
The patent applies different phosphor materials or concentrations to different regions of the LED chip based on local requirements. By tailoring the phosphor composition and distribution to specific areas, the patent achieves uniform color temperature across the entire LED while maintaining adequate coverage area. This local optimization allows different zones to contribute appropriately to the overall light output and color consistency.
2Ease of manufacture
If a flat phosphor layer is used to simplify manufacturing, then the ease of manufacture is improved, but the color temperature uniformity deteriorates
Solution Approach 1:
The patent introduces a convex curved surface to the phosphor layer structure, which can be fabricated using standard semiconductor processing techniques such as reflow processing or forming a convex lens structure on the substrate before phosphor deposition. This curved geometry naturally promotes uniform light distribution and consistent color temperature across the LED output, while the fabrication process remains compatible with existing manufacturing capabilities, thus maintaining ease of manufacture.
3Loss of energy
If the phosphor is positioned closer to the LED chip to improve light conversion, then the light conversion efficiency is improved, but the heat management deteriorates
Solution Approach 1:
The patent positions discrete phosphor particles on the LED chip surface with spacing between them, creating a segmented phosphor layer architecture. This segmentation provides air gaps or low thermal conductivity regions between phosphor particles, facilitating heat dissipation from the LED chip while maintaining sufficient proximity for effective light conversion. The spaced arrangement allows heat to conduct through multiple paths rather than being concentrated in a continuous phosphor layer, thus managing thermal load while preserving optical efficiency.
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 improves light extraction efficiency and reduces color temperature variations by directing emission in the vertical direction, enhancing the performance of white LEDs by ensuring uniform phosphor distribution and minimizing light reflection losses.
Implementation Method 1
A light emitting device (LED) includes a p-n junction diode having a characteristic of converting electric energy into light energy
Implementation Method 2
the yellow phosphor (YAG or TAG) is added to the blue LED, or red/green/blue phosphors are employed in the UV LED
Implementation Method 3
the light extracting structure extracts light, which is generated in the light emitting structure and incident into an interfacial surface between the fluorescent layer and the light extracting structure
Implementation Method 4
the light converted by the phosphor is total-reflected from a boundary surface of the background material
Data Source
AI summary
Disclosed are a light emitting device, a method of manufacturing the same and a light emitting device package. The light emitting device of the embodiment includes a light emitting structure including a first conductive semiconductor layer, a second conductive semiconductor layer and an active layer between the first and second conductive semiconductor layers; a fluorescent layer on the light emitting structure; and a light extracting structure on the fluorescent layer. The light extracting structure extracts light, which is generated in the light emitting structure and incident into an interfacial surface between the fluorescent layer and the light extracting structure, to an outside of the light emitting structure.