LED Phosphor Segmentation for Thermal Quenching
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Solution Overview
Problem
Conventional white-color Light Emitting Devices (LEDs) face efficiency degradation due to thermal quenching, especially at high temperatures, which affects their luminous efficiency and color rendering performance.
Innovation Solution
The use of a combination of sialon and silicate phosphors in separate fluorescent layers on LEDs, where the sialon phosphor maintains efficiency at high temperatures and the silicate phosphor enhances efficiency at low temperatures, ensuring consistent luminous performance across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single phosphor is used in conventional white-color LEDs, then the structure is simple, but the luminous efficiency degrades at high temperatures due to thermal quenching
Solution Approach 1:
The patent divides the phosphor system into multiple separate fluorescent layers, each containing a different phosphor material optimized for specific temperature ranges. This segmentation allows each layer to maintain high luminous efficiency under different thermal conditions, resolving the contradiction between structural simplicity and efficiency maintenance.
Solution Approach 2:
The patent employs composite phosphor systems with different materials (e.g., yellow phosphor, red phosphor, green phosphor) having complementary temperature-dependent characteristics. By combining materials with opposite thermal quenching behaviors, the system achieves stable overall luminous efficiency across wide temperature ranges while maintaining reasonable structural complexity.
2Power
If high-power LED is used to increase output, then the light output is improved, but heat generation increases causing thermal quenching and efficiency degradation
Solution Approach 1:
The patent changes the thermal response parameters of the phosphor system by selecting materials with different thermal quenching characteristics. This allows the system to maintain efficient light conversion across varying temperature conditions generated by high-power operation, decoupling power output from efficiency degradation.
3Loss of energy
If multiple phosphors with different temperature characteristics are combined, then luminous efficiency is maintained across temperature ranges, but the device structure becomes more complex
Solution Approach 1:
The patent segments the phosphor system into distinct fluorescent layers mounted on separate heat-generating structures. This segmentation strategy manages complexity by organizing multiple phosphors into modular units, each optimized for specific temperature ranges, while maintaining clear functional separation and independent thermal management pathways.
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 maintains excellent luminous efficiency from low to high temperatures, improving color rendering and reducing thermal quenching effects, thus enhancing the overall performance of white-color LEDs.
Implementation Method 1
a first fluorescent layer formed on each of the first light emitting elements, the first fluorescent layer including a first phosphor
Implementation Method 2
a second fluorescent layer formed on each of the second light emitting elements, the second fluorescent layer including a second phosphor
Implementation Method 3
plural first light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm
Data Source
AI summary
A light emitting device according to one embodiment includes a board; plural first light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm; plural second light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm; a first fluorescent layer formed on each of the first light emitting elements, the first fluorescent layer including a first phosphor; and a second fluorescent layer formed on each of the second light emitting elements, the second fluorescent layer including a second phosphor. The second phosphor is higher than the first phosphor in luminous efficiency at 50° C., and is lower than the first phosphor in the luminous efficiency at 150° C.