White Light Emission Spectrum Tuning for Low Melanopic Ratio
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Solution Overview
Problem
Current white light emitting devices for human-centric lighting struggle to balance melanopic photopic ratio and color rendering index, often compromising on circadian rhythm optimization and color accuracy.
Innovation Solution
A white light emitting device incorporating a blue LED with specific wavelength conversion materials, such as β-SiAlON and red phosphors, to emit white light with a melanopic photopic ratio of 0.65 or less and a color rendering index of 80 or more, optimizing circadian rhythms while maintaining high color accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wavelength conversion materials are used in white light emitting devices, then color rendering index can be improved, but melanopic photopic ratio increases compromising circadian rhythm optimization
Solution Approach 1:
The patent applies parameter changes by precisely controlling the peak wavelengths of wavelength conversion materials (green: 535-550nm, red: 620-660nm) and the blue LED excitation wavelength (440-455nm). By adjusting these spectral parameters and their relative intensities, the device achieves a color rendering index of 80 or more while maintaining melanopic photopic ratio at 0.65 or less, resolving the contradiction between color accuracy and circadian rhythm optimization.
Solution Approach 2:
The patent uses composite materials by combining multiple wavelength conversion materials with specific characteristics - including green phosphors (β-SiAlON, silicate), red phosphors (K2SiF6:Mn4+, CaAlSiN3:Eu), and yellow phosphors (YAG:Ce). This composite approach allows simultaneous optimization of color rendering properties and melanopic photopic ratio through synergistic spectral distribution control.
2Measurement precision
If blue light intensity is increased to improve color rendering, then color accuracy improves, but melanopic sensitivity band intensity increases affecting circadian rhythms
Solution Approach 1:
The patent applies local quality by creating non-uniform spectral distribution with enhanced intensity in specific wavelength regions (green 535-550nm and red 620-660nm) while suppressing the melanopic-sensitive blue region (465-495nm). This localized spectral enhancement achieves high color rendering index through targeted wavelength optimization rather than uniform blue light intensity increase.
3Measurement precision
If wavelength conversion materials with broad emission spectrum are used, then color rendering index improves, but spectral precision deteriorates affecting melanopic ratio control
Solution Approach 1:
The patent applies segmentation by dividing the wavelength conversion spectrum into distinct segments - green emission (535-550nm, FWHM 60nm or less), yellow emission, and red emission (620-660nm). This segmented spectral approach allows precise control of each wavelength region's intensity, enabling simultaneous achievement of high color rendering index and accurate melanopic photopic ratio control through independent optimization of each spectral segment.
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 effectively lowers melanopic sensitivity band intensity to optimize circadian rhythms and achieves a high color rendering index, providing human-centric lighting that enhances both circadian rhythm adjustment and color rendering performance.
Implementation Method 1
a blue light emitting diode configured to emit blue light having a peak wavelength in a first range of 440 nm to 455 nm
Implementation Method 2
a first wavelength conversion material, based on being excited by the blue light, emits first light having a peak wavelength in a second range of 535 nm to 550 nm
Implementation Method 3
a second wavelength conversion material, based on being excited by the blue light, emits second light having a peak wavelength in a third range of 620 nm to 660 nm
Data Source
AI summary
A white light emitting device is provided. The white light emitting device includes a blue light emitting diode configured to emit blue light having a peak wavelength in a first range of 440 nm to 455 nm; a first wavelength conversion material, based on being excited by the blue light, emits first light having a peak wavelength in a second range of 535 nm to 550 nm and a full width at half maximum (FWHM) of 60 nm or less; and a second wavelength conversion material, based on being excited by the blue light, emits second light having a peak wavelength in a third range of 620 nm to 660 nm, wherein a melanopic photopic ratio of white light emitted from the white light emitting device is 0.65 or less, and a color rendering index (CRI) of the white light is 80 or more.