White LED Spectrum Mixing With Pass-Through Violet for High CRI
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Solution Overview
Problem
Conventional light emitting devices, such as LEDs, face challenges in achieving high luminous efficiency and improved color rendering, particularly in reproducing red hues and providing accurate color representation across a wide range of colors, which is essential for general illumination applications.
Innovation Solution
The use of a light emitting device configuration that includes a first group of blue LEDs and a second group of LEDs emitting light in the range of 390 nm to 415 nm, combined with luminescent materials like YAG:Ce and K2SiF6:Mn4+ phosphors, to enhance color rendering and luminous flux efficiency, with the UV contribution between 2% and 15% of the spectral power, effectively increasing saturation in various color ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LEDs use blue LED with yellow phosphor (YAG:Ce) for high luminous efficiency, then luminous flux efficiency is improved, but color rendering index deteriorates due to poor red hue reproduction
Solution Approach 1:
The patent segments the color rendering function by introducing a separate red LED component (620-680 nm) alongside the blue LED-YAG:Ce phosphor system. This segmentation allows the blue LED to maintain high luminous efficiency while the red LED specifically addresses the poor red hue reproduction, achieving CRI≥94 without sacrificing luminous flux efficiency.
Solution Approach 2:
The patent creates a composite light source by combining multiple LED types (blue LED, red LED) with phosphor materials (YAG:Ce). This composite approach merges the high efficiency of blue LED-YAG:Ce with the superior red hue reproduction of red LED, resolving the contradiction between luminous flux efficiency and color rendering index.
2Use of energy by moving object
If conventional LEDs use narrow spectral power distribution for high efficiency, then energy conversion is improved, but color saturation deteriorates
Solution Approach 1:
The patent merges narrowband blue LED emission with narrowband red LED emission to create a combined spectrum that maintains the energy efficiency of narrow spectral distributions while achieving high color saturation. The combination of these two narrow bands produces vivid blue and red hues that would be difficult to achieve with broader spectral sources.
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
This configuration achieves a luminous flux efficiency of 100 to 140 lumens per watt and a color rendering index (CRI) of at least 94, significantly improving color rendering and saturation across the visible spectrum, particularly in the green-yellow and violet color ranges, while maintaining high luminous efficiency.
Implementation Method 1
a first luminophoric medium that includes at least a first luminescent material that, when excited by light from the first blue LED, emits light having a peak wavelength in a green color range or a yellow color range
Implementation Method 2
a second LED that, when excited, emits light having a peak wavelength in a range between about 390 nm and about 415 nm, where between about 2% and about 15% of a spectral power of light emitted from the light emitting device is light having wavelengths in the range between about 390 nm and about 415 nm
Implementation Method 3
a second luminescent material that, when excited by light from the first blue LED, emits light having a peak wavelength in an orange color range or a red color range
Data Source
AI summary
A lighting apparatus a first group of at least one first solid state emitter, each first solid state emitter including a first light emitting diode (“LED”) that, when excited, emits light having a peak wavelength in a range between about 440 nm and about 475 nm, and a second group of at least one second solid state emitter, each second solid state emitter comprising a second LED that, when excited, emits light having a peak wavelength in a range between about 390 nm and about 415 nm. Between about 2% and about 15% of a spectral power of light emitted from the lighting apparatus is light having wavelengths in the range between about 390 nm and about 415 nm.