White LED Spectral 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 color rendering performance and luminous flux efficiency while maintaining a desirable color temperature and saturation across various color ranges, particularly in reproducing red hues and providing improved perceived color rendering.
Innovation Solution
The implementation of a light emitting device configuration that includes a first group of blue LEDs and a second group of LEDs emitting light in the 390 nm to 415 nm range, combined with luminescent materials like YAG:Ce and K2SiF6: Mn4+ phosphors, which enhance the saturation of green, yellow, and red color ranges, and increase the UV contribution to the spectral power distribution, thereby improving color rendering and luminous flux efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED configurations are used, then device simplicity is maintained, but color rendering performance and luminous flux efficiency deteriorate
Solution Approach 1:
The LED device is segmented into multiple independent light emitting groups, each configured to emit light in specific wavelength ranges. This segmentation allows each group to be optimized for particular spectral contributions, enabling high color rendering performance through coordinated emission from multiple specialized groups rather than relying on a single conventional LED structure.
Solution Approach 2:
The device employs composite luminescent materials including YAG:Ce phosphor and K2SiF6: Mn4+ phosphor in different groups. These composite material configurations enable simultaneous achievement of high luminous flux efficiency and superior color rendering by combining the advantageous spectral characteristics of different phosphor materials in a multi-group architecture.
2Reliability
If luminescent materials are added to convert wavelengths, then color rendering improves, but luminous flux efficiency deteriorates
Solution Approach 1:
Different luminescent material configurations are applied locally to different groups based on their specific functions. Some groups use YAG:Ce phosphor for high efficiency yellow conversion, while other groups incorporate K2SiF6: Mn4+ phosphor for enhanced red emission. This localized optimization allows each group to achieve maximum efficiency for its specific spectral role, preventing overall luminous flux efficiency deterioration.
Solution Approach 2:
The patent applies luminescent materials selectively in specific groups rather than uniformly across all groups. By applying phosphor conversion only where needed for specific wavelength ranges and leaving other groups as direct blue or violet emitters, the device achieves necessary color rendering enhancement while minimizing the cumulative efficiency loss that would result from universal phosphor application.
3Reliability
If multiple LED groups are implemented, then color rendering and luminous flux efficiency improve, but device complexity increases
Solution Approach 1:
Multiple LED groups are merged into a single integrated device structure with shared control and mounting infrastructure. The groups are combined in a way that allows coordinated operation to achieve high CRI and luminous flux efficiency, while the merging approach reduces overall device complexity compared to operating multiple separate LED devices independently.
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 color rendering index (CRI) of at least 94 and luminous flux efficiency between 100 and 140 lumens per watt, with increased saturation in specific hue angle bins, resulting in improved perceived color rendering and a more natural color representation.
Implementation Method 1
a first blue light emitting diode ("LED") that, when excited, emits light having a peak wavelength in a blue color range
Implementation Method 2
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 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
Implementation Method 4
a second LED that, when excited, emits light having a peak wavelength in a range between about 390 nm and about 415 nm
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.