Solid State Lighting Device Near Ultraviolet LEDs Phosphors
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Solution Overview
Problem
Conventional solid state light emitters, such as LEDs, struggle to provide white light efficiently with high energy efficiency, acceptable color temperature, and good color rendering index (CRI Ra) for general illumination, often resulting in poor color rendition of objects and increased complexity and cost due to the need for various LEDs with different efficiencies.
Innovation Solution
A lighting device comprising a group of solid state light emitters emitting near ultraviolet light and lumiphors emitting light in the range of 555 nm to 585 nm, combined to achieve a CRI Ra of at least 85, with the mixture of light from these components defining a point within specific areas on the CIE Chromaticity Diagram, and optionally combined with orange or red light to produce perceived white light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
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 lacking in rendering red and green colors
Solution Approach 1:
The patent combines multiple solid state light emitters with different emission characteristics (blue LED at 440-480nm, green LED at 500-560nm, red LED at 610-750nm, and yellow phosphor at 560-590nm) to create a composite light source that achieves both high energy efficiency and high CRI Ra (≥85). This merging of multiple light sources with complementary spectral characteristics resolves the contradiction between energy efficiency and color rendering.
Solution Approach 2:
The patent uses composite luminescent materials including yellow phosphors (Y3Al5O12:Ce, Lu3Al5O12:Ce, YAG:Ce), red phosphors (CaAlSiN3:Eu, Sr2Si5N8:Eu), and green phosphors (β-SiAlON:Eu, SrSi2O2N2:Eu) combined with LED emitters to create a composite lighting system that maintains high energy efficiency while achieving excellent color rendering across the visible spectrum.
2Use of energy by moving object
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 merges multiple solid state light emitters (blue, green, red LEDs) with various phosphors to create a composite light source that achieves both high energy efficiency (comparable to or better than fluorescent) and superior color reproduction (CRI Ra ≥85, exceeding fluorescent's 70-80). This combination allows precise spectral control to render all colors accurately.
Solution Approach 2:
The patent changes the spectral parameters by using multiple LED emitters with different peak wavelengths and combining them with phosphors having specific emission characteristics. This allows precise control over the spectral power distribution to achieve high CRI Ra while maintaining high energy efficiency, improving upon fluorescent lighting's color reproduction.
3Use of energy by moving object
If solid state light emitters are used to provide white light, then energy efficiency is improved, but device complexity increases due to the need to combine multiple emitters and phosphors to achieve high CRI Ra
Solution Approach 1:
The patent merges multiple solid state light emitters and phosphors into a single integrated lighting device, combining blue LEDs, green LEDs, red LEDs, and yellow phosphors in one unit. This integration achieves high energy efficiency and high CRI Ra while managing complexity through unified device architecture rather than separate components.
Solution Approach 2:
The patent creates a multi-functional solid state lighting device that simultaneously provides high energy efficiency, high CRI Ra, and long lifetime in a single unit. The device performs multiple functions (energy-efficient illumination, accurate color rendering, long-duration operation) without requiring multiple separate systems, thereby managing complexity through universal design.
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 efficiency, long life, and improved color rendering with a wide gamut, simplifying control circuitry and reducing the complexity and cost of systems by using a combination of near ultraviolet LEDs and lumiphors to produce white light with enhanced color accuracy.
Implementation Method 1
Light emitting diodes are semiconducting devices that emit light (ultraviolet, visible, or infrared) when a potential difference is applied across a p-n junction structure
Implementation Method 2
exciting a first group of lumiphors, such that each of the first group of lumiphors emits 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 one or more solid state light emitters which emit near ultraviolet light and one or more lumiphors which emit light having a wavelength in the range of from 555 nm to 585 nm, which in the absence of other light would produce a mixture of light within an area defined by x, y coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), and (0.36, 0.38). The lighting device may further comprise one or more 600 nm to 630 nm light emitters, and a mixture of light emitted from the lighting device may be within ten MacAdam ellipses of the blackbody locus. Also, packaged solid state light emitters and methods of lighting.