Multi-Phosphor LED Light Emission for Circadian and Color Rendering
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Solution Overview
Problem
Existing lighting technologies fail to effectively consider circadian rhythm and color rendering properties, as evidenced by insufficient melanopic ratio (MR) and color rendering indices, which are crucial for human health and comfort in indoor environments.
Innovation Solution
A light emitting device that combines multiple light sources with different emission spectra, including nitride semiconductors and various fluorescent materials, to achieve a wide range of correlated color temperatures, MR values, and color rendering indices, thereby optimizing illumination for circadian rhythm and visual comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple LED structure with single phosphor is used, then device complexity is reduced, but melanopic ratio and color rendering properties deteriorate
Solution Approach 1:
The patent divides the light emission system into multiple independent LED chips with different wavelengths (blue, cyan, green, yellow-green) and assigns different phosphors to each chip. This segmentation allows each component to be optimized for specific spectral contributions, achieving high melanopic ratio and color rendering properties without requiring a completely complex device architecture.
Solution Approach 2:
The patent employs composite phosphor materials including yellow phosphor (Y3Al5O12:Ce), red phosphor (CaAlSiN3:Eu), and green phosphor (β-SiAlON:Eu) in specific combinations on different LED chips. These composite phosphor layers transform the LED emission spectra to achieve the desired high melanopic ratio and excellent color rendering properties while maintaining manageable device complexity.
2Reliability
If multiple LED chips with different phosphors are combined, then melanopic ratio and color rendering properties are improved, but device complexity increases
Solution Approach 1:
The patent segments the lighting function across multiple LED chips, with each chip handling specific spectral tasks. For example, blue LED chips with yellow and red phosphors handle melanopic stimulation, while cyan and green LED chips contribute to color rendering. This functional segmentation achieves high performance without requiring all possible components to operate simultaneously.
Solution Approach 2:
The patent designs the LED chip arrangement to serve multiple functions simultaneously: the same structural configuration can adjust correlated color temperature from 2000K to 10000K, control melanopic ratio for circadian rhythm regulation, and maintain high color rendering properties. This multi-functionality reduces the need for separate specialized components.
3Adaptability or versatility
If correlated color temperature is adjusted across wide range, then adaptability to different lighting conditions is improved, but control precision requirements increase
Solution Approach 1:
The patent implements dynamic control of LED chip activation and phosphor layer illumination ratios to achieve continuous adjustment of correlated color temperature from 2000K to 10000K. By dynamically controlling which LED chips are active and at what intensity levels, the system adapts to different lighting conditions while maintaining manageable control precision through progressive illumination ratios.
Solution Approach 2:
The patent changes the illumination ratios and activation states of different LED chips and phosphors to achieve wide correlated color temperature adjustment. By varying parameters such as the ratio of blue to cyan LED output and the intensity distribution across different phosphor layers, the system achieves adaptability across lighting conditions without requiring excessive control precision.
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 device enhances melanopic ratio (MR) and color rendering indices, providing improved synchronization with human circadian rhythms and better visual comfort across a broad range of correlated color temperatures.
Implementation Method 1
a light emitting element 12 which is a nitride semiconductor and has a light emission peak in a range of 410 nm or more and 490 nm or less
Implementation Method 2
a first fluorescent material 14 having a composition represented by a formula of Y3(Al,Ga)5O12:Ce and having a light emission peak in the vicinity of 496 nm as a main fluorescent material
Data Source
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AI summary
A light emitting device comprises one or a plurality of light emitting elements and a plurality of fluorescent materials, and emits a first light, a second light, and a third light from one or a plurality of light emitting elements and one or a plurality of fluorescent materials, wherein the first light has a correlated color temperature in a range of 1,500 K or more and 3,500 K or less, and has a color rendering index R9 of 50 or more, the second light has a correlated color temperature in a range of 3,500 K or more and 5,500 K or less, and has a color rendering index R9 of 50 or more, the third light has values of X and Y coordinates in the chromaticity diagram of the CIE1931 color system that are smaller than the values of X and Y coordinates at a color temperature of 5,500 K on the black body radiation locus, and a light having a correlated color temperature of 6,500 K has a color rendering index R9 of 50 or more and a melanopic ratio of 1.0 or more.