High Color-Saturation Lighting Devices Using Composite Phosphors
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Solution Overview
Problem
Conventional solid state lighting devices struggle to provide high color-quality light that balances high color fidelity, high color saturation, and high efficiency, particularly in achieving enhanced vividness while maintaining high color rendering suitable for general illumination.
Innovation Solution
A lighting device comprising an electrically activated solid state emitter with a dominant wavelength in the blue range, a lumiphoric material emitting light in the green or yellow-green range, and another emitter with a dominant wavelength in the red or red-orange range, where the blue light source has a sufficiently short wavelength and the lumiphoric material includes sufficient green content to achieve increased saturation, along with a mixture of multiple lumiphoric materials to produce a specific color point within the 1931 CIE Chromaticity Diagram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional solid state lighting devices use a combination of blue LED and yellow phosphor to produce white light, then the device achieves high efficiency and long service life, but the color saturation is insufficient and the light appears under-saturated with certain colors
Solution Approach 1:
The patent applies local quality by using multiple phosphor materials with different emission characteristics (yellow, green, red) to selectively enhance specific wavelength regions. Each phosphor contributes to saturating particular color bands, creating localized spectral enhancement while maintaining overall white light output and high luminous efficacy.
Solution Approach 2:
The invention uses composite phosphor materials including yellow phosphor (e.g., YAG:Ce), green phosphor (e.g., Lu3Al5O12:Ce), and red phosphor (e.g., CaAlSiN3:Eu) in combination with blue LED. This composite approach fills spectral gaps and creates over-saturated colors by combining emissions from multiple phosphors with different peak wavelengths, achieving both high efficacy and enhanced color saturation.
2Productivity
If conventional solid state lighting devices mix relatively narrow wavelength bands from LEDs and lumiphors to create white light, then the device achieves high efficiency, but the resulting light has spectral gaps that cause under-saturation or over-saturation with certain colors
Solution Approach 1:
The patent employs parameter changes by carefully selecting the peak wavelengths, emission widths, and relative intensities of multiple phosphor materials. By adjusting these parameters, the invention fills spectral gaps between narrow LED and phosphor emission bands, creating a more uniform spectral distribution that prevents both under-saturation and over-saturation while maintaining high luminous efficacy.
3Temperature
If conventional solid state lighting devices add red-emitting LED or red lumiphoric material to increase warmth and approximate incandescent light, then the color temperature is reduced and warmth is improved, but the overall color saturation and vividness decrease
Solution Approach 1:
The patent applies local quality by using multiple phosphor materials with different emission characteristics (yellow, green, red) to selectively enhance specific wavelength regions. Each phosphor contributes to saturating particular color bands, creating localized spectral enhancement while maintaining overall white light output and high luminous efficacy.
Solution Approach 2:
The invention uses composite phosphor materials including yellow phosphor (e.g., YAG:Ce), green phosphor (e.g., Lu3Al5O12:Ce), and red phosphor (e.g., CaAlSiN3:Eu) in combination with blue LED. This composite approach fills spectral gaps and creates over-saturated colors by combining emissions from multiple phosphors with different peak wavelengths, achieving both high efficacy and enhanced color saturation.
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 color fidelity, high color saturation, and high efficiency, with a color rendering index (CRI Ra) of at least 85, a relative gamut area (Qg) value of 116.5 minus the product of 0.003 times the correlated color temperature (CCT) value, and a luminous efficacy of at least 80 lumens per watt, effectively providing a more vivid and efficient lighting experience.
Implementation Method 1
at least one first electrically activated solid state emitter arranged to generate first emissions comprising a dominant wavelength in a blue range
Implementation Method 2
at least one lumiphoric material arranged to receive at least a portion of the first emissions and produce lumiphor emissions comprising a dominant wavelength in a green or yellow-green range
Data Source
AI summary
A lighting device including a blue solid state emitter, at least one yellow-green or green lumiphoric material, and at least one red or red-orange solid state emitter can simultaneously provide high color fidelity (e.g., high CRI Ra), high color saturation (e.g., high Qg), and high efficiency (e.g., lumens per watt). A subcombination of blue and yellow-green emissions is provided within one or more specified regions of a 1931 CIE chromaticity diagram. By providing sufficient green content, increased saturation can be active with relatively a short wavelength red or red-orange source while maintaining high color fidelity and efficacy. A mixture of green and yellow lumiphoric materials may be provided.