Light-Emitting Spectrum Design for Low-Melanopic Warm Lighting
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Solution Overview
Problem
Current light-emitting devices do not effectively promote melatonin secretion, which is important for circadian rhythm regulation and sleep induction, as they often stimulate intrinsically photosensitive Retinal Ganglion Cells (ipRGCs) excessively.
Innovation Solution
A light-emitting device with a light-emitting element having an emission peak wavelength between 400 nm to 490 nm and a phosphor with an emission peak wavelength between 570 nm to 680 nm, specifically designed to emit light with a correlated color temperature of 1950 K or less, a narrow full width at half maximum of the emission spectrum, and a melanopic ratio of 0.233 or less, to minimize stimulation of ipRGCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional light-emitting devices are used, then general lighting function is provided, but excessive stimulation of ipRGCs occurs which inhibits melatonin secretion
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the emission peak wavelengths of the blue light-emitting element (400-490 nm) and red phosphor (570-680 nm), along with controlling the correlated color temperature (1950K or less) and melanopic ratio (0.233 or less). These parameter adjustments optimize the spectral composition to minimize ipRGC stimulation while maintaining effective lighting output.
Solution Approach 2:
The patent uses a composite light-emitting system combining a blue light-emitting element with red phosphor materials. This composite approach creates a synergistic effect where the blue light excites the red phosphor to emit red light, producing a combined spectrum that achieves warm white light with reduced melanopic stimulation compared to conventional white LED sources.
2Object-affected harmful factors
If light with low correlated color temperature is emitted to promote melatonin secretion, then circadian rhythm regulation is improved, but color rendering may be compromised
Solution Approach 1:
The patent controls the correlated color temperature parameter at 1950K or less to promote melatonin secretion, while simultaneously adjusting the emission peak wavelengths and spectral distribution to maintain adequate color rendering (Ra ≥ 40). This dual parameter optimization resolves the contradiction between circadian rhythm regulation and color rendering quality.
3Object-affected harmful factors
If narrow spectral width is used to reduce ipRGC stimulation, then melanopic ratio is controlled, but luminance efficiency may be reduced
Solution Approach 1:
The patent combines blue light-emitting materials with red phosphor materials to create a composite light source. The blue light at 400-490 nm has inherently lower melanopic stimulation, and when combined with red phosphor emission at 570-680 nm, the overall spectrum achieves a low melanopic ratio (≤0.233) while maintaining high luminance efficiency through the high quantum efficiency of the phosphor conversion process.
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 emits light that promotes melatonin secretion and induces sleep naturally, providing a relaxing atmosphere suitable for indoor and in-vehicle lighting applications without reducing luminance.
Implementation Method 1
a light-emitting element having an emission peak wavelength in a range of 400 nm to 490 nm
Implementation Method 2
a first phosphor having an emission peak wavelength in a range of 570 nm to 680 nm
Data Source
AI summary
Provided are a light-emitting device, a lighting appliance, and a lighting fixture that emit light that tends to promote melatonin secretion. The light-emitting device, the lighting appliance, and the lighting fixture include a light-emitting element having an emission peak wavelength in a range of 400 nm to 490 nm and a first phosphor having an emission peak wavelength in a range of 570 nm to 680 nm. The emitted light has a correlated color temperature that is 1950 K or less, an average color rendering index Ra that is 40 or greater, a full width at half maximum of an emission spectrum indicating a maximum emission intensity in an emission spectrum of the light-emitting device that is 110 nm or less, and a melanopic ratio MR derived from Equation (1) that is 0.233 or less.