Light Emitting Device With Segmented Phosphor Layers
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Solution Overview
Problem
Conventional white-color Light Emitting Devices (LEDs) face efficiency degradation due to thermal quenching and reabsorption issues, particularly when using multiple phosphors in close proximity, which affects luminous efficiency and color rendering.
Innovation Solution
The design incorporates separate fluorescent layers with sialon green and red phosphors, spaced apart by a gas gap, and includes a blue LED chip with a transparent resin layer to minimize reabsorption and thermal quenching, maintaining high packaging density and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple phosphors are placed close together to achieve high packaging density, then the device size is reduced, but reabsorption between phosphors increases and luminous efficiency degrades
Solution Approach 1:
The patent divides the phosphor arrangement into separate fluorescent layers (first fluorescent layer with green phosphor, second fluorescent layer with red phosphor) instead of mixing phosphors together. This segmentation reduces reabsorption between different phosphors while maintaining high packaging density, as each layer can be optimized independently for its specific phosphor type.
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional stacked structure with multiple fluorescent layers separated by gas gaps. This vertical stacking in the third dimension allows closer overall packaging while maintaining sufficient separation distance between different phosphor types to minimize reabsorption.
2Volume of moving object
If phosphors are placed close together to improve packaging density, then manufacturing complexity is reduced, but thermal quenching increases at high temperatures
Solution Approach 1:
By separating phosphors into distinct fluorescent layers with gas gaps between them, the patent reduces thermal interaction between different phosphor materials. This segmentation allows each phosphor layer to be optimized for thermal stability independently, improving overall reliability at high operating temperatures.
Solution Approach 2:
The patent introduces gas gaps as intermediary spaces between fluorescent layers. These gas gaps act as thermal insulators, reducing heat transfer between adjacent phosphor layers and minimizing thermal quenching effects while maintaining compact device dimensions.
3Device complexity
If a single fluorescent layer with multiple phosphors is used, then device structure is simplified, but reabsorption between phosphors degrades luminous efficiency
Solution Approach 1:
The patent segments the fluorescent structure into multiple separate layers, each containing a specific phosphor type. While this increases structural complexity compared to a single layer, the segmentation eliminates reabsorption losses by preventing photons from one phosphor type from being absorbed by another, thereby improving overall luminous efficiency.
Solution Approach 2:
The patent employs composite fluorescent layer structures where each layer contains specific phosphor materials optimized for particular wavelength ranges. This composite approach allows tailored optimization of each layer's optical and thermal properties, achieving high efficiency while managing the complexity through systematic material organization.
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
This configuration effectively suppresses reabsorption between phosphors, enhancing luminous efficiency and color rendering while maintaining high packaging density, even at high temperatures.
Implementation Method 1
a first light emitting element that is mounted on the board to emit light having a wavelength of 250 nm to 500 nm
Implementation Method 2
a first fluorescent layer that is formed on the first light emitting element, the first fluorescent layer including a green phosphor
Implementation Method 3
a second fluorescent layer that is formed on the second light emitting element, the second fluorescent layer including a red phosphor
Data Source
AI summary
A light emitting device according to one embodiment includes: a board; plural first light emitting units each including a first light emitting element and a first fluorescent layer formed on the first light emitting element having a green phosphor; plural second light emitting units each including a second light emitting element and a second fluorescent layer formed on the second light emitting element having a red phosphor; the second fluorescent layers and the first fluorescent layers being separated in a non-contact manner with gas interposed there between; and plural third light emitting units each including a third light emitting element and a resin layer formed on the third light emitting element having neither a green phosphor nor the red phosphor, the third light emitting units being disposed between the first light emitting units and the second light emitting units.