LED Lighting Device with Phosphor Conversion for High CRI White Light
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Solution Overview
Problem
Conventional lighting technologies, such as incandescent and fluorescent lights, are inefficient and have limitations in color rendering index (CRI Ra) and lifespan, necessitating the development of more energy-efficient and long-lasting solid state light emitters like LEDs, which struggle to produce white light effectively.
Innovation Solution
A lighting device comprising a combination of solid state light emitters emitting in the near ultraviolet range and luminescent materials that emit light in specific wavelength ranges, when excited, to achieve a combined illumination with improved CRI Ra and color temperature, positioned within defined MacAdam ellipses on the CIE Chromaticity Diagram, effectively producing white light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If solid state light emitters (LEDs) are used to improve energy efficiency and lifespan, then energy efficiency and duration of service are improved, but the ability to produce white light with high color rendering index deteriorates
Solution Approach 1:
The patent combines multiple solid state light emitters with different emission characteristics (violet LED at 405nm, blue LED at 450nm, and cyan LED at 495nm) with phosphor materials to create a composite lighting system that achieves high CRI Ra (95-100) while maintaining LED energy efficiency. This merging of multiple light sources and phosphors resolves the contradiction by pooling their individual strengths to produce superior white light with full spectral coverage.
Solution Approach 2:
The patent employs composite phosphor materials including yellow phosphor (Y3Al5O12:Ce), orange phosphor (CaAlSiN3:Eu), red phosphor (CaAlSiN3:Eu), and green phosphor (β-SiAlON:Eu) in combination with multiple LED types. This composite material approach enables the system to achieve broad spectral emission covering all visible wavelengths, thereby achieving high color rendering index while maintaining the energy efficiency of solid state lighting.
2Reliability
If conventional light bulbs are used to achieve high color rendering index, then color rendering is improved, but energy efficiency and lifespan deteriorate
Solution Approach 1:
The patent changes the fundamental parameters of light generation by using solid state LED technology with specific wavelength emissions (405nm violet, 450nm blue, 495nm cyan) combined with phosphor down-conversion, replacing traditional incandescent or fluorescent mechanisms. This parameter change enables simultaneous achievement of high energy efficiency (LED technology) and high color rendering index (broad spectral output through phosphor combination).
3Duration of action of stationary object
If solid state light emitters are used to extend lifespan, then duration of service is improved, but the complexity of achieving high color rendering index increases
Solution Approach 1:
The patent segments the lighting device into multiple independent LED modules (violet, blue, cyan LEDs) and separate phosphor components. This segmentation allows each component to be optimized for its specific function while maintaining the overall system's high CRI Ra performance. The modular approach manages complexity by organizing multiple elements into distinct, manageable units that can be independently controlled and replaced.
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 provides a lighting device with enhanced energy efficiency, improved color rendering index, and extended lifespan, capable of producing white light with a CRI Ra of at least 85, 90, or 95, suitable for various applications.
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
a luminescent material (e.g., a phosphor) that emits yellow light in response to excitation by light emitted by the light emitting diode
Data Source
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AI summary
A method of selecting tints for a colored coating composition is disclosed. The method includes (a) providing a plurality of tints, each tint comprising a pigment dispersed in a resinous carrier binder; (b) preparing a plurality coating composition, each coating compositions comprising a resinous coating binder and at least one of the tints, the total binder content being the amount of carrier binder and coating binder; (c) determining the absorbance of radiation in a wavelength band of each coating composition; (d) identifying coating compositions of step (b) having a maximum weight ratio of pigment to total binder and a maximum amount of resinous carrier binder and exhibiting a minimum absorbance in the wavelength band; and (e) selecting the tints from the coating compositions identified in step (d) for use in preparing a colored coating composition.