White Light Emitting Device with Sunlight-Like Spectrum
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Solution Overview
Problem
Current light-emitting devices that aim to mimic sunlight spectra often have discontinuities, particularly at wavelengths between 460 nm-480 nm, and excessive blue light emission, failing to achieve a high degree of similarity with natural sunlight.
Innovation Solution
A white light emitting device is developed with a spectrum similarity of over 90% to sunlight in the visible range (430 nm-650 nm) by combining blue chips with specific phosphors, such as blue, green, and red phosphors, and area normalization techniques to ensure spectral continuity and reduced blue light glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-intensity spectral energy is output at wavelengths in the range of 440 nm-460 nm to match sunlight spectrum, then the degree of similarity with sunlight is improved, but blue light hazard radiation increases causing blue light glare
Solution Approach 1:
The patent changes the spectral distribution parameters by using multiple phosphors with different emission characteristics (yellow phosphor with 560-580nm peak, red phosphor with 610-650nm peak, green phosphor with 520-540nm peak) to reshape the overall spectrum. This redistributes the energy across wavelengths to match sunlight while reducing the harmful 440-460nm blue light intensity, achieving both high spectrum similarity and reduced blue light hazard
Solution Approach 2:
The patent employs a composite phosphor system combining multiple phosphor materials (yellow phosphor, red phosphor, green phosphor) excited by a blue LED chip. This composite approach creates a synergistic effect where each phosphor contributes specific wavelength ranges, collectively producing a continuous spectrum that mimics sunlight while controlling blue light emission through the dominance of yellow and red phosphor emissions
2Measurement precision
If the spectrum is made continuous across all visible wavelengths to match sunlight, then the degree of similarity is improved, but the device complexity increases due to multiple phosphors required
Solution Approach 1:
The patent segments the visible spectrum into three distinct wavelength ranges, each covered by a specific phosphor: yellow phosphor for 560-580nm, red phosphor for 610-650nm, and green phosphor for 520-540nm. This segmentation allows each phosphor to be optimized for its specific range while collectively achieving continuous spectrum coverage, simplifying the overall design compared to attempting to cover all wavelengths with a single phosphor
Solution Approach 2:
The blue LED chip serves as a universal excitation source that simultaneously activates all three phosphor types (yellow, red, and green). This multi-functional approach allows a single excitation source to drive the entire phosphor system, reducing the need for multiple separate light sources and simplifying the device structure while achieving continuous spectrum emission
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 provides a light apparatus with a spectrum that closely resembles sunlight, offering excellent spectral continuity and reduced blue light glare, enhancing lighting effects for indoor activities.
Implementation Method 1
combining blue chips with phosphors
Implementation Method 2
The phosphors have a scheme consisting of three kinds of phosphors or a scheme consisting of four kinds of phosphors
Data Source
AI summary
A white light emitting device, a light bar and a light apparatus. A relative spectrum of the white light emitting device is ϕ(λ). A relative spectrum of a black body radiation with a corresponding color temperature is S(λ). An area normalization is performed on ϕ(λ) and S(λ) to convert an equal energy spectrum ϕ′(λ) of the white light emitting device and an equal energy spectrum S′(λ) of the black body radiation with the corresponding color temperature. A degree of similarity R of the equal energy spectrum of the white light emitting device and the equal energy spectrum of the black body radiation satisfies the following formula:R=1-ΣλiλnS′(λ)-Φ′(λ)ΣλiλnS′(λ),when λi is 380 nm, λn is 680 nm, R≥85%.