White Light Source Matching Natural Spectra
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Solution Overview
Problem
Current white light sources, particularly those using LEDs, have light emission spectra significantly different from natural light, which can adversely affect human circadian rhythms with prolonged exposure.
Innovation Solution
A white light source is designed to have a light emission spectrum that closely matches natural light by adjusting the light emission spectrum to satisfy a specific relational equation, using a combination of LEDs and phosphors to achieve a difference in spectral luminous efficiency within a narrow range, thereby replicating natural light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional white LEDs use blue LEDs with strong emission peaks (400-530 nm) combined with YAG phosphors to achieve white light, then energy saving and long service life are improved, but the light emission spectrum deviates significantly from natural light, causing adverse effects on human circadian rhythms
Solution Approach 1:
The patent applies parameter changes by carefully selecting and adjusting the peak wavelengths of multiple LEDs (blue, cyan, green, yellow-green, yellow, orange, red) and the emission characteristics of phosphors to reshape the overall light emission spectrum. This ensures the spectral power distribution closely matches natural sunlight across the visible range, eliminating the harmful blue light dominance while maintaining energy efficiency and long service life of LED technology.
Solution Approach 2:
The patent uses composite materials by combining multiple types of LEDs with different peak wavelengths and various phosphors (including yellow phosphor, orange phosphor, red phosphor, and green phosphor) to create a multi-component light emission system. This composite approach enables the synthesis of a balanced white light spectrum that mimics natural light, resolving the contradiction between LED durability and circadian rhythm health.
2Illumination intensity
If blue LED peak height is made at least 1.5 times the yellow phosphor peak height to achieve conventional white light, then white light is successfully generated, but the strong blue light emission creates significant deviation from natural light spectrum
Solution Approach 1:
The patent segments the white light generation process into multiple independent wavelength components using separate LEDs (blue, cyan, green, yellow-green, yellow, orange, red) and phosphors. Instead of relying on a single blue LED dominating the spectrum, each segment contributes to a balanced spectral distribution that collectively produces natural-like white light without excessive blue light concentration.
Solution Approach 2:
The patent applies local quality by optimizing the emission characteristics in different wavelength regions independently. The spectral power distribution is designed to match natural light locally across the entire visible spectrum (380-780 nm), with specific attention to reducing blue light intensity while enhancing other wavelength regions to achieve overall spectral balance and natural light reproduction.
3Object-affected harmful factors
If four types of light emission peaks are combined as suggested in Patent Document 2 to control blue light (420-490 nm), then melatonin secretion is normalized, but the light emission spectrum still does not fully match natural light across the complete visible range
Solution Approach 1:
The patent applies dynamics by enabling independent control of multiple LED channels and phosphor combinations, allowing dynamic adjustment of the spectral power distribution. This dynamic control system can adaptively optimize the light emission spectrum to precisely match natural light characteristics across different conditions, while simultaneously controlling blue light exposure to normalize melatonin secretion.
Solution Approach 2:
The patent achieves universality by designing a multi-functional light emission system that simultaneously accomplishes multiple objectives: controlling blue light to regulate melatonin secretion, matching the complete visible spectrum (380-780 nm) of natural light, maintaining energy efficiency, and ensuring long service life. The system performs multiple spectral optimization functions through coordinated LED and phosphor combinations.
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 suppresses adverse effects on human circadian rhythms by mimicking natural light spectra, providing a healthier lighting environment that supports normal melatonin secretion and reduces sleep disorders.
Implementation Method 1
white light sources including light emitting diodes (LEDs)
Implementation Method 2
blue LEDs each having a light emission peak wavelength in a range of 400 to 530 nm
Implementation Method 3
YAG phosphors are excited using blue LEDs
Implementation Method 4
the blue light emitted from the LEDs and the yellow light emitted from the YAG phosphors are mixed
Data Source
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AI summary
The present invention provides a white light source comprising an LED (8, 8a, 8b, 8c) having an emission peak wavelength of 350 to 420 nm; and a phosphor having an emission peak wavelength in the range of 420 to 700 nm, wherein the phosphor (9, 9a, 9b, 9c) is a mixture of at least three of a blue phosphor, a blue-green phosphor, a green phosphor, a yellow phosphor and a red phosphor, adjacent peak wavelengths of the phosphors being deviated to each other by 10 to 100 nm. It is assumed that a light emission spectrum of a white light source is P(X); a light emission spectrum of black-body radiation having a same color temperature as that of the white light source is B(X); a spectrum of a spectral luminous efficiency is V(X) ; a wavelength at which P(X) x V(X) becomes largest is Xmax1; and a wavelength at which B(X) x V(X) becomes largest is Xmax2, a white emission with a color temperature of 2,500 to 7,000 K, satisfying a following relational expression: -0.2 < [(P(X) x V(X)) / (P(Xmax1) x V(Xmax1)) - (B(X) x V(A,) ) / (B(Xmax2) x V(Amax2))] < +0.2, is shown, and any color temperature that the sun shows in a day is reproduced by changing a mixing ratio of the phosphors. According to the above white light source, there can be provided a white light source capable of reproducing the same light emission spectrum as that of natural light.