Broadband White LED Phosphor Design for High CRI and Low Blue Harm
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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 disrupt human physiology and psychology due to high color temperature and blue light emission, which can be detrimental to health.
Innovation Solution
Development of full spectrum white light emitting devices using broadband solid-state excitation sources with a dominant wavelength in the blue region, combined with photoluminescence materials that generate light in the blue to cyan spectrum, optimizing the spectral content to resemble natural sunlight and reducing deep red emission for improved efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full spectrum LEDs use conventional phosphor materials to achieve high CRI Ra of 100, then color rendering properties are improved, but luminous efficacy deteriorates
Solution Approach 1:
The patent changes the spectral parameters by using a broadband blue excitation source (420-480nm dominant wavelength) instead of conventional narrowband blue LEDs, and selects photoluminescence materials with specific emission characteristics (yellow-green 520-560nm and red 600-680nm) to optimize the balance between color rendering and efficacy. This parameter optimization allows achieving CRI Ra≥90 while maintaining high luminous efficacy≥100 lm/W
Solution Approach 2:
The patent employs composite photoluminescence materials comprising multiple phosphor types (yellow-green emitting phosphor and red emitting phosphor) excited by broadband blue light. This composite approach creates a full spectrum white light with enhanced color rendering properties while maintaining high efficacy through synergistic material combination
2Use of energy by moving object
If white LEDs emit high color temperature light with strong blue light, then luminous efficacy is improved, but harmful effects on human physiology worsen
Solution Approach 1:
The patent applies local quality by selectively enhancing specific wavelength regions (yellow-green 520-560nm and red 600-680nm) while maintaining moderate blue content. The broadband blue excitation (420-480nm) provides sufficient blue light for efficacy but the photoluminescence conversion distributes energy across beneficial wavelengths, reducing excessive blue light exposure that causes melatonin suppression while maintaining overall luminous efficacy≥100 lm/W
Solution Approach 2:
The patent converts the potentially harmful concentrated blue light emission into beneficial full spectrum white light through photoluminescence wavelength conversion. The broadband blue excitation source is transformed by phosphor materials into a balanced spectrum with enhanced yellow-green and red components, maintaining efficacy while reducing harmful blue light exposure
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 solution generates white light with enhanced color rendering properties, reduced melatonin suppression, and improved efficacy, closely resembling natural light in the blue to cyan region, benefiting human well-being while maintaining high luminous efficiency.
Implementation Method 1
full spectrum white light emitting devices comprising photoluminescence wavelength conversion materials
Implementation Method 2
photoluminescence materials (typically inorganic phosphor materials), which absorb a portion of the blue light emitted by the LED and re-emit visible light of a different color (wavelength)
Data Source
AI summary
There is provided a full spectrum white light emitting device comprising: a broadband LED flip chip that generates 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 multiple quantum wells LED chip comprising multiple different wavelength quantum wells in its active region that generate multiple narrowband light emissions of multiple different wavelengths and wherein broadband light generated by the broadband LED flip chip is composed of a combination of the multiple narrowband light emissions, and wherein the at least one photoluminescence material layer comprises a first photoluminescence material which generates light with a peak emission wavelength from 490 nm to 550 nm; and a second photoluminescence material which generates light with a peak emission wavelength from 600 nm to 680 nm.