Europium Phosphor for Balanced White Light in LED Illumination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing white light illumination systems using light-emitting diodes (LEDs) struggle to produce a well-balanced color rendition, particularly in the red spectrum, leading to difficulties in distinguishing between white and yellow lane markings, which is crucial for safety, especially in traffic and tunnel lighting.
Innovation Solution
The use of a europium(II)-activated halogeno-oxonitridosilicate phosphor, which absorbs blue light and emits a broad band of yellow to red light, enhancing the red component in the output spectrum, thereby improving color rendering index (CRI) and providing a more balanced white light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a blue LED combined with a yellow phosphor is used to generate white light, then the illumination system can provide high luminance and energy efficiency, but the color rendering index deteriorates due to deficiency in the red region of the visible light spectrum
Solution Approach 1:
The patent uses a composite phosphor system consisting of multiple phosphor materials with different emission characteristics. Specifically, it combines phosphors that emit in the yellow-green region with phosphors that emit in the red region, creating a composite fluorescent material that converts blue LED light into a broader spectrum white light with improved color rendering properties while maintaining energy efficiency.
Solution Approach 2:
The patent segments the white light generation process into multiple wavelength components by using different phosphor materials for different spectral regions. Instead of relying on a single yellow phosphor, the invention divides the conversion task among multiple phosphors - one for yellow-green conversion and another for red conversion - thereby achieving both efficiency and color accuracy.
2Device complexity
If conventional phosphors are used in LED illumination systems, then the device complexity remains low, but the manufacturing precision of color rendering deteriorates due to inability to produce well-balanced red spectrum
Solution Approach 1:
The patent changes the spectral parameters of the illumination system by selecting phosphor materials with specific emission peak wavelengths and bandwidths. It carefully chooses phosphors whose emission characteristics complement each other to achieve a balanced spectrum, particularly enhancing the red region while maintaining overall color rendering precision without increasing device complexity.
3Illumination intensity
If a blue LED with yellow phosphor is used, then the illumination intensity is high, but the ability to distinguish red colors deteriorates due to deficiency in red spectrum emission
Solution Approach 1:
The patent introduces a red-emitting phosphor as an intermediary component that bridges the spectral gap between blue LED emission and the red region of the visible spectrum. This intermediary phosphor absorbs blue light and re-emits in the red region, thereby restoring red color information that would otherwise be lost in a simple blue-yellow LED system while preserving high luminance.
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 europium(II)-activated halogeno-oxonitridosilicate phosphor significantly improves the color rendering index, ensuring better recognition of red colors and providing a high-quality white light with enhanced red intensity, suitable for applications like traffic lighting and security lighting.
Implementation Method 1
a europium(II)-activated halogeno-oxonitridosilicate phosphor, which absorbs blue light and emits a broad band of yellow to red light
Implementation Method 2
for the generation of specific, colored light, including white light, by luminescent down conversion
Data Source
AI summary
The invention concerns an illumination system comprising a radiation source and a fluorescent material comprising at least one phosphor capable of absorbing part of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said at least one phosphor is a yellow to red-emitting europium(II) activated halogeno-oxonitridosilicate of the general formula EaxSiyN2/3X+4/3y:EuzOaXb, wherein 1≦x≦2; 3≦y≦7; 0.001≦z≦0.09, 0.005<a≦5 0.05, 0.01<b≦0.3, EA is at least one earth alkaline metal chosen from the group of calcium, barium and strontium and X is at least one halogen chosen from the group of fluorine, chlorine, bromine and iodine. The invention is also concerned with a red to yellow-emitting europium(II)-activated halogeno-oxonitridosilicate of the general formula EaxSiyN2/3x+4/3y:EuzOaXb, wherein 1≦x≦2; 3≦y≦≦7; 0.001<z≦0.09, 0.005<a≦0.05, 0.01<b≦0.3, EA is at least one earth alkaline metal chosen from the group of calcium, barium and strontium and X is at least one halogen chosen from the group of fluorine, chlorine, bromine and iodine, and a method of manufacturing same.