Solid State Lighting Device for High CRI White Light
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Solution Overview
Problem
Conventional solid state light emitters, such as LEDs, struggle to produce white light efficiently while maintaining high energy efficiency, good color rendering index (CRI Ra), and long duration, particularly in applications requiring accurate color rendition like human complexion, food, and natural scenes, where current solutions often fall short in rendering red and green colors effectively.
Innovation Solution
A lighting device comprising multiple solid state light emitters and lumiphors, emitting light within specific wavelength ranges (430-480 nm and 555-585 nm) to achieve a mixed illumination with CRI Ra of at least 85, 90, or 95, and combining these with orange or red light to produce perceived white light, ensuring accurate color representation on a 1931 CIE Chromaticity Diagram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional solid state light emitters (LEDs) are used to produce white light, then energy efficiency is improved compared to incandescent and fluorescent lights, but color rendering index (CRI Ra) deteriorates, particularly in rendering red and green colors
Solution Approach 1:
The patent combines multiple solid state light emitters with different emission characteristics (blue LEDs at 430-480nm, green LEDs at 500-550nm, and red LEDs at 600-650nm) with luminescent materials to create a composite light source that achieves both high energy efficiency and high CRI Ra (≥85, preferably ≥90). This merging of multiple light sources with complementary spectral characteristics resolves the contradiction by providing full spectrum coverage while maintaining LED energy efficiency.
Solution Approach 2:
The patent uses composite luminescent materials including phosphors and luminescent down-converting (LDC) materials that convert blue LED light into yellow, green, and red wavelengths. This composite approach creates a full-spectrum white light source with high CRI Ra while maintaining the energy efficiency of blue LED excitation, thereby resolving the contradiction between energy efficiency and color rendering.
2Loss of energy
If conventional light bulbs (incandescent or fluorescent) are replaced with solid state light emitters, then energy efficiency is improved, but the ability to render natural colors (especially red and green) deteriorates
Solution Approach 1:
The patent merges blue, green, and red solid state light emitters in specific combinations to produce white light with complete spectral coverage. This combining approach ensures that all three primary color regions are represented, enabling accurate rendering of natural colors including reds and greens while maintaining the energy efficiency of solid state lighting.
Solution Approach 2:
The patent enhances specific wavelength regions by incorporating dedicated green LEDs (500-550nm) and red LEDs (600-650nm) in addition to blue LEDs. This local quality enhancement ensures that previously deficient spectral regions (green and red) are adequately represented, improving color accuracy while maintaining overall energy efficiency.
3Productivity
If solid state light emitters are designed to emit specific wavelengths for high efficiency, then energy efficiency is improved, but the spectral coverage needed for high CRI Ra deteriorates
Solution Approach 1:
The patent combines multiple solid state light emitters operating at different wavelengths (blue 430-480nm, green 500-550nm, red 600-650nm) to achieve comprehensive spectral coverage. This merging strategy maintains the high energy efficiency of individual LED wavelengths while collectively providing the full spectrum needed for high CRI Ra.
Solution Approach 2:
The patent uses luminescent materials as intermediaries that convert blue LED light into yellow, green, and red wavelengths. These intermediary materials expand the spectral output without requiring direct blue LED emission at all visible wavelengths, thereby maintaining energy efficiency while achieving broad spectral coverage.
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 high-efficiency white light source with improved color rendering, long lifespan, and simplified control circuitry, effectively addressing the limitations of current LED lamps by achieving high CRI Ra values and maintaining energy efficiency.
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 first group of lumiphors, wherein each of the first group of lumiphors, when excited, emits light having a dominant wavelength in the range of from about 555 nm to about 585 nm
Data Source
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AI summary
A lighting device comprises: a first group of solid state light emitters comprising at least one solid state light emitter; and a second group of solid state light emitters comprising at least one solid state light emitter; wherein: if said first group of solid state light emitters is illuminated and said second group of solid state light emitters is illuminated, a mixture of (1) light emitted from said lighting device which was emitted by said first group of solid state light emitters and (2) light emitted from said lighting device which was emitted by said second group of solid state light emitters would, in the absence of any additional light, have a mixed illumination having x, y color coordinates which define a point which is within an area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, said first line segment connecting a first point to a second point, said second line segment connecting said second point to a third point, said third line segment connecting said third point to a fourth point, said fourth line segment connecting said fourth point to a fifth point, and said fifth line segment connecting said fifth point to said first point, said first point having x, y coordinates of 0.32, 0.40, said second point having x, y coordinates of 0.36, 0.48, said third point having x, y coordinates of 0.43, 0.45, said fourth point having x, y coordinates of 0.42, 0.42, and said fifth point having x, y coordinates of 0.36, 0.38.