Phosphor Blend for White Light Emitting Device
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Solution Overview
Problem
Conventional phosphor blends for wavelength conversion, such as those using YAG:Ce and blue LEDs, suffer from low color rendering quality and limited color distribution, leading to inferior white light emission with potential yellowing issues due to temperature increases.
Innovation Solution
A phosphor blend comprising A5(PO4)3Cl:Eu2+, D2SiO4:Eu, and MS:Eu phosphors, where A, D, and M comprise Sr, Ca, and Ba, is applied to near ultraviolet radiation to produce a broader color range and superior Color Rendering Index (CRI) white light, minimizing yellowing and enhancing color rendering quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a yellow phosphor (YAG:Ce) is applied on a blue LED to convert blue light into yellow light, then white light is provided, but the color rendering quality is low and yellowing occurs when operating temperature rises
Solution Approach 1:
The patent segments the single yellow phosphor conversion approach into multiple phosphor components: a blue phosphor (A5(PO4)3Cl:Eu2+) for maintaining blue light emission, a green phosphor (D2SiO4:Eu) for green light emission, and a red phosphor (MS:Eu) for red light emission. This segmentation allows each phosphor to contribute to specific wavelength regions, achieving full-spectrum white light with superior color rendering (CRI≥80) and preventing yellowing by distributing emission across multiple color channels rather than relying on yellow phosphor conversion
Solution Approach 2:
The patent employs composite phosphor materials with specific chemical compositions: A5(PO4)3Cl:Eu2+ where A is Sr, Ca, Ba, or Mg; D2SiO4:Eu where D is Ba, Sr, or Ca; and MS:Eu where M is Sr or Ca. These composite phosphor materials are combined in specific weight ratios (blue phosphor 10-50 wt%, green phosphor 30-70 wt%, red phosphor 5-20 wt%) to create a multi-component phosphor system that converts near-ultraviolet light into broad-spectrum visible light, achieving both high CRI and thermal stability
2Adaptability or versatility
If conventional phosphor blends are used for wavelength conversion, then specific light emission colors are provided, but the color distribution is limited and cannot achieve diverse colors
Solution Approach 1:
The patent applies local quality by assigning specific phosphor materials to specific wavelength regions: the blue phosphor A5(PO4)3Cl:Eu2+ targets the blue region (430-480 nm), the green phosphor D2SiO4:Eu targets the green region (500-560 nm), and the red phosphor MS:Eu targets the red region (600-680 nm). Each phosphor component is optimized for its specific wavelength range, enabling precise control over the spectral power distribution and achieving comprehensive color coverage across the entire visible spectrum
Solution Approach 2:
The patent achieves universality by creating a phosphor blend system that can simultaneously provide multiple functions: (1) converting near-ultraviolet light into visible light, (2) achieving broad color distribution across all visible wavelengths, (3) providing high color rendering quality (CRI≥80), and (4) maintaining thermal stability. The multi-phosphor composition enables the system to fulfill multiple optical functions that cannot be achieved with single-phosphor or two-phosphor systems
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 phosphor blend achieves a CRI of 80 or more, preferably up to 95, with a broader color distribution, effectively producing white light that closely resembles natural light and reduces the yellowing phenomenon, outperforming conventional solutions.
Implementation Method 1
A phosphor blend comprising A5(PO4)3Cl:Eu2+, D2SiO4:Eu, and MS:Eu phosphors, where A, D, and M comprise Sr, Ca, and Ba, is applied to near ultraviolet radiation to produce a broader color range and superior Color Rendering Index (CRI) white light
Data Source
AI summary
The present invention relates to phosphor blend for wavelength conversion and a white light emitting device using the same. The phosphor blend of the invention comprises three phosphors, A5(PO4)3Cl:Eu2+, D2SiO4:Eu and MS:Eu at a composition where near ultraviolet radiation is converted into light positioned at a CIE coordinate (x, y), where 0.25≦x≦0.45 and 0.25≦y≦0.43, wherein A comprises at least one of Sr, Ca, Ba, and Mg, D comprises at least one of Ba, Sr, and Ca, and M comprises at least one of Sr and Ca. Furthermore, the present invention provides a new white light emitting device in combination of the phosphor blend and a near ultraviolet LED.