White Light Emitting Device Segmented Fluorescent Materials
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Solution Overview
Problem
Existing white light emitting devices using LEDs struggle to achieve high color rendering properties and luminescent efficiency while maintaining low power consumption, particularly in high-temperature operations.
Innovation Solution
A white light emitting device configuration utilizing a blue LED chip combined with two SION-based fluorescent materials of different peak wavelengths and a red fluorescent material, where the SION materials have specific compositions and structures to optimize color rendering and efficiency, including (Sr (1-x-y-z) Ba x Ca y Eu z )Si 2 O 2 N 2, and Ca 2 Si y Al (12-y) O z N :Eu, to achieve balanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a combination of blue LED chip and yellow fluorescent material is used to create white light, then the device can achieve white light emission, but the color rendering properties and luminescent efficiency are insufficient
Solution Approach 1:
The patent segments the yellow fluorescent material into two distinct materials with different peak wavelengths (first yellow fluorescent material and second yellow fluorescent material). This segmentation allows each material to contribute differently to the overall spectrum, improving color rendering while maintaining efficiency by avoiding the trade-off inherent in using a single yellow fluorescent material.
Solution Approach 2:
The patent employs a composite fluorescent layer containing multiple fluorescent materials (two yellow fluorescent materials and one red fluorescent material) combined with a blue LED chip. This composite structure enables simultaneous optimization of color rendering properties and luminescent efficiency by carefully selecting materials with complementary emission characteristics.
2Illumination intensity
If the fluorescent materials are optimized for high color rendering index, then the average color rendering index improves, but the luminescent efficiency decreases
Solution Approach 1:
The patent optimizes specific parameters of the fluorescent materials including peak wavelengths (first peak wavelength and second peak wavelength both in yellow region), full width at half maximum (FWHM) ratios, and intensity ratios. By carefully controlling these parameters, the patent achieves high color rendering index while minimizing energy loss through efficient blue light absorption and conversion.
3Illumination intensity
If multiple fluorescent materials with different peak wavelengths are used to improve color rendering, then the color rendering index improves, but the device complexity increases
Solution Approach 1:
The patent applies local quality by assigning specific functional roles to different fluorescent materials within the composite layer. The first yellow fluorescent material and second yellow fluorescent material each have optimized peak wavelengths and FWHM characteristics suited to their specific positions in the spectrum, allowing complex color rendering requirements to be met through localized material optimization rather than uniform complexity throughout.
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 device achieves high average color rendering index and luminescent efficiency, with minimal color deviations at high temperatures, and maintains high performance by adjusting the peak wavelengths and intensity ratios of the fluorescent materials to match incandescent lamp colors.
Implementation Method 1
a first fluorescent material which emits light with a first peak wavelength of 525 nm or more and 560 nm or less, with use of light emitted from the light emitting element as excitation light
Implementation Method 2
a fluorescent material that absorbs at least some of the light emitted from the semiconductor light emitting element
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A white light emitting device according to an embodiment includes: a light emitting element having a peak wavelength in a wavelength range of 430 nm or more and 470 nm or less; a first fluorescent material emits light with a first peak wavelength of 525 nm or more and 560 nm or less; a second fluorescent material emits light with a second peak wavelength longer than the first peak wavelength; and a third fluorescent material emits light with a third peak wavelength of 620 nm or more and 750 nm or less, which is longer than the second peak wavelength. The first fluorescent material and the second fluorescent material has a composition of MSiαOβNγ, and when the first peak wavelength is denoted by λ1 (nm), whereas the second peak wavelength is denoted by λ2 (nm), 100 ≤ λ1 + λ2 and λ2 - λ1 ≤ 60 are satisfied.