Broadband Blue LED Phosphor Stack for Sunlight-Like White Light
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Solution Overview
Problem
Current full spectrum LEDs sacrifice efficacy to achieve high Color Rendering Index (CRI) Ra of 100, and existing white LEDs with CRI80 devices face challenges in generating full spectrum white light that closely resembles natural sunlight, particularly in the blue to cyan region, which is crucial for human non-visual perception and circadian rhythm regulation.
Innovation Solution
The development of broadband solid-state excitation sources, such as InGaN/GaN blue LEDs with multiple quantum wells, generate broadband blue light with a dominant wavelength between 420 nm to 480 nm, combined with photoluminescence materials that produce light in the green and red regions, to create full spectrum white light emitting devices that closely resemble natural sunlight in the blue to cyan spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional white LEDs with CRI80 are used, then efficacy is maintained at high levels, but the spectral content does not closely resemble natural sunlight particularly in the blue to cyan region
Solution Approach 1:
The patent changes the spectral parameters of the LED by using broadband blue LEDs with dominant wavelengths between 420-480nm and FWHM of 25-50nm, combined with specific photoluminescence materials (yellow phosphor with 560-580nm peak, red phosphor with 610-650nm peak) to achieve full spectrum white light that resembles natural sunlight while maintaining high efficacy
Solution Approach 2:
The patent uses a composite approach by combining broadband blue LED material with multiple photoluminescence materials (yellow and red phosphors) to create a composite light emitting system that produces full spectrum white light with enhanced color rendering and natural sunlight resemblance
2Illumination intensity
If full spectrum LEDs are designed to achieve CRI Ra of 100, then color rendering is improved, but efficacy is sacrificed
Solution Approach 1:
The patent applies partial action by selectively enhancing specific spectral regions (blue-cyan 430-520nm, yellow 560-580nm, red 610-650nm) rather than uniformly across all wavelengths, achieving CRI Ra of 90 or higher while maintaining efficacy through targeted spectral optimization rather than full-spectrum enhancement
3Illumination intensity
If blue light content is increased to improve circadian stimulus, then non-visual perception is enhanced, but harmful effects on human physiology may increase
Solution Approach 1:
The patent optimizes the blue light parameters by using broadband blue LEDs with dominant wavelengths of 420-480nm and FWHM of 25-50nm, which provides sufficient circadian stimulus (CAF values) while the broad spectrum distribution reduces the concentration of harmful narrowband blue light, balancing physiological benefits with safety
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
These devices improve efficacy while maintaining spectral content similar to natural light, reducing the red spectral content to enhance color rendering properties and circadian stimulus, resulting in a more effective and human-friendly lighting solution.
Implementation Method 1
broadband solid-state excitation sources, such as InGaN/GaN blue LEDs with multiple quantum wells, generate broadband blue light
Implementation Method 2
InGaN/GaN blue LEDs with multiple quantum wells, generate broadband blue light with a dominant wavelength between 420 nm to 480 nm
Implementation Method 3
combined with photoluminescence materials that produce light in the green and red regions
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
There is provided a white light emitting device comprising: a chip scale packaged broadband LED flip chip for generating broadband light of dominant wavelength from about 420 nm to about 480 nm and a FWHM from 25 nm to 50 nm; and at least one photoluminescence layer covering a light emitting face of the broadband LED flip chip; wherein the broadband LED flip chip comprises a broadband InGaN/GaN LED chip having an active region for directly generating blue light emissions of at least three different wavelengths using different quantum wells in a multiple-quantum well (MQW) structure, and wherein the at least one photoluminescence material layer comprises a first photoluminescence material for generating light with a peak emission wavelength from 490 nm to 550 nm; and a second photoluminescence material for generating light with a peak emission wavelength from 600 nm to 680 nm.