Narrow Band Phosphor Warm White LED
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Solution Overview
Problem
Warm white phosphor-converted LEDs have low lumen equivalents due to broad emission spectra, making it difficult to produce efficient warm white light using a blue LED and cerium-containing garnet, necessitating the use of multiple luminescent materials, which complicates production and reproducibility.
Innovation Solution
A warm white LED with a narrow band yellow emitting phosphor material, specifically Ba2Si5N8:Eu, is used, which provides a peak emission in the 570-580 nm range with a spectral width of 2000-2100 cm−1, allowing for a single phosphor to produce warm white light with high efficacy and stability, combining with a blue LED to achieve a correlated color temperature of 2700K and increased light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If broad emission spectrum phosphors are used to achieve warm white light, then the color temperature can be maintained at 2700K, but the lumen equivalent decreases to 280-340 lm/Wopt
Solution Approach 1:
The patent changes the spectral parameters of the phosphor by using a narrow band yellow emitting phosphor with peak emission at 570-580 nm and FWHM of 2000-2100 cm−1, combined with a blue LED at 440-460 nm. This parameter optimization achieves warm white light at 2700K with lumen equivalents exceeding 410 lm/Wopt, resolving the contradiction between color temperature and luminous efficiency.
2Productivity
If multiple luminescent materials are used to achieve efficient warm white light, then the lumen equivalent can be improved, but the production complexity and reproducibility worsen
Solution Approach 1:
The patent merges the functions of multiple phosphors into a single narrow band yellow emitting phosphor material (Ba2Si5N8:Eu). This single phosphor combines the advantages of both yellow and red emission components, simplifying the device structure to just the blue LED and one phosphor layer, thereby reducing production complexity while maintaining high lumen equivalents above 410 lm/Wopt.
3Productivity
If high lumen equivalent is achieved through narrow band phosphor, then the light output increases by >20%, but the manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the phosphor concentration parameter to achieve maximum luminous efficiency. By controlling the Eu concentration in Ba2Si5N8:Eu at optimal levels and maintaining FWHM of 2000-2100 cm−1, the system achieves >20% increase in light output while establishing clear manufacturing specifications for precision control.
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 results in a >20% increase in light output compared to prior art, reducing costs by allowing for smaller optics and minimizing cooling needs, while providing warm white light with high efficiency and cost-effective designs.
Implementation Method 1
a luminescent material element, configured to absorb at least part of the blue light source light and to convert into luminescent material light
Data Source
AI summary
The invention provides a lighting device configured to provide white lighting device light, the lighting device comprising (i) a light source, configured to provide blue light source light, and (ii) a luminescent material element, configured to absorb at least part of the blue light source light and to convert into luminescent material light, wherein the luminescent material element comprises a luminescent material which consists for at least 80 wt. % of a M2-2xEu2xSi5-yAlyOyN8-y phosphor, wherein M comprises one or more of Mg, Ca, Sr, Ba, with a molar ratio of (Mg+Ca+Sr)/(Ba)≤0.1, wherein x is in the range of 0.001-0.02, wherein y is in the range of ≤0.2, and wherein the white lighting device light comprises said blue light source light and said luminescent material light.