Multi-Wavelength LED Lighting Device for High CRI Illumination
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Solution Overview
Problem
Conventional solid state light emitters, such as LEDs, struggle to provide white light with high energy efficiency, good color rendering index (CRI Ra), and long duration, particularly in applications requiring accurate color rendition like general illumination, where existing solutions often fall short in rendering red and green colors effectively.
Innovation Solution
A lighting device comprising a combination of solid state light emitters emitting light in specific wavelength ranges (430 nm to 480 nm, 555 nm to 585 nm, and 600 nm to 630 nm) with lumiphors, which produce a mixture of light that achieves high CRI Ra values and efficient illumination by aligning with the blackbody locus on the CIE Chromaticity Diagram, ensuring accurate color representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional solid state light emitters (LEDs) are used to provide white light, then energy efficiency is improved compared to incandescent bulbs, but color rendering index (CRI Ra) deteriorates particularly in red and green color ranges
Solution Approach 1:
The patent segments the white light generation into multiple independent wavelength components by using separate LED chips for blue (430-480 nm), yellow-green (555-585 nm), and red (600-630 nm) regions, each with optimized phosphors, rather than relying on a single LED type with compromised color rendering
Solution Approach 2:
The patent employs composite phosphor materials including yellow phosphors (Y3Al5O12:Ce, Lu3Al5O12:Ce), red phosphors (CaAlSiN3:Eu, Sr2Si5N8:Eu), and green phosphors (β-SiAlON:Eu, SrSi2O2N2:Eu) combined with specific LED chips to create a composite light source that achieves both high energy efficiency and high CRI Ra values
2Loss of energy
If fluorescent light bulbs are used instead of incandescent bulbs, then energy efficiency is improved by a factor of about ten, but color reproduction deteriorates with typical CRI Ra of 70-80
Solution Approach 1:
The patent changes the spectral parameters by using LED excitation sources with specific wavelength ranges (430-480 nm blue, 555-585 nm yellow-green) paired with phosphors having optimized emission characteristics, achieving CRI Ra values of 90 or higher while maintaining energy efficiency superior to fluorescent lighting
3Manufacturing precision
If solid state light emitters are designed to achieve high CRI Ra values, then color rendering is improved, but energy efficiency deteriorates
Solution Approach 1:
The patent applies local quality optimization by selecting phosphors with specific emission characteristics for each wavelength region: yellow phosphors with 560-580 nm peak for high efficiency, red phosphors with 610-630 nm peak for accurate red rendering, and green phosphors with 520-540 nm peak for complete spectral coverage, achieving both high CRI Ra and energy efficiency
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 achieves high CRI Ra values of at least 80, with efficacy of 25 lumens per watt or more, providing a wide gamut and simple control circuitry, effectively addressing the limitations of existing LED lamps in color rendition and efficiency.
Implementation Method 1
a first group of solid state light emitters, the first group of solid state light emitters including at least one solid state light emitter; a first group of lumiphors, the first group of lumiphors including at least one lumiphor; a second group of solid state light emitters, the second group of solid state light emitters including at least one solid state light emitter
Implementation Method 2
each of the first group of lumiphors, if excited, would emit light having a dominant wavelength in the range of from about 555 nm to about 585 nm
Data Source
AI summary
A lighting device comprising first and second groups of solid state light emitters, which emit light having wavelength in ranges of from 430 nm to 480 nm and from 600 nm to 630 nm, respectively, and a first group of lumiphors which emit light having dominant wavelength in the range of from 555 nm to 585 nm. If current is supplied to a power line, a combination of (1) light exiting the lighting device which was emitted by the first group of emitters, and (2) light exiting the lighting device which was emitted by the first group of lumiphors would, in an absence of any additional light, produce a sub-mixture of light having x, y color coordinates within an area on a 1931 CIE Chromaticity Diagram defined by points having coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), (0.36, 0.38). Also provided is a method of lighting.