Triple Phosphor LED for High Color Rendering
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Solution Overview
Problem
Existing light emitting devices using LEDs and phosphors struggle to achieve high luminous efficiency and color rendering properties, particularly in the blue-green and red ranges, due to sharp emission peaks and limited color mixing capabilities.
Innovation Solution
A light emitting device incorporating a light emitting element with a peak emission wavelength of 430-470 nm, combined with a fluorescent member containing specific phosphors such as silicate, aluminate, and silicon nitride, which emit green, yellow, and red light, respectively, to create a continuous emission spectrum and enhance color rendering properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If blue LEDs and yellow phosphors are used in combination, then high luminous efficiency is achieved, but sufficient radiant intensity in blue-green range and red range cannot be obtained
Solution Approach 1:
The patent segments the yellow phosphor emission into two separate phosphors: one emitting in the blue-green range (480-530 nm) and another emitting in the red range (600-680 nm). This segmentation allows each phosphor to be optimized for its specific wavelength range, ensuring sufficient radiant intensity in both regions while maintaining high luminous efficiency through targeted energy conversion.
Solution Approach 2:
The patent uses a composite phosphor system combining multiple phosphor materials with complementary emission characteristics. The composite includes a blue-green emitting phosphor (such as beta-SiAlON:Eu or Sr2Si5N8:Eu) and a red emitting phosphor (such as CaAlSiN3:Eu or Sr2Si5N8:Eu), which together with the blue LED create a comprehensive spectrum with high efficiency and balanced radiant intensity across desired wavelength ranges.
2Illumination intensity
If three LEDs of different colors are used, then wide color reproduction range is achieved, but sufficient color mixing and continuous emission spectrum are difficult to obtain
Solution Approach 1:
The patent introduces phosphors as intermediary materials that convert the sharp spectral lines of individual LEDs into broader, more continuous emission bands. The phosphors absorb energy from the LEDs and re-emit it across wider wavelength ranges, acting as mediators that blend the discrete LED emissions into a continuous spectrum, thereby achieving smooth color mixing and eliminating the gaps between spectral peaks.
Solution Approach 2:
The patent changes the emission spectrum parameters by using phosphors with controlled half-bandwidths and peak wavelengths. By selecting phosphors with appropriate spectral characteristics (such as half-bandwidths of 80-120 nm for blue-green emitters and 60-100 nm for red emitters), the system transforms the sharp emission peaks of LEDs into broader, overlapping spectra that mix continuously, achieving smooth color transitions and comprehensive spectral coverage.
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 luminous efficiency and color rendering indices of 80 or greater, with adjustable correlated color temperature and improved R9 values, suitable for various applications requiring high color fidelity.
Implementation Method 1
light emitting devices using light emitting elements which are called light emitting diodes (hereinafter may be referred to as LEDs)
Implementation Method 2
phosphors to emit yellow light... phosphors that emit light upon being excited by the blue light
Data Source
AI summary
A light emitting device includes a light emitting element of a peak emission wavelength in a range of 430 nm to 470 nm and a fluorescent member. The fluorescent member includes a first phosphor including a silicate having a composition that contains at least one element selected from the group consisting of Ca, Sr, and Ba, at least one element selected from the group consisting of Cl, F, and Br, and Mg and Eu, a second phosphor including an aluminate that has a composition containing Lu and Ce, and a third phosphor having emission spectrum with a half bandwidth of 86 nm or less and including a silicon nitride that has a composition containing at least one of Sr or Ca, and containing Al and Eu.