Green Phosphor for LED Color Rendering and Manufacturing
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Solution Overview
Problem
Existing light emitting devices with blue LEDs and phosphors have poor color rendering properties due to limited emission intensity variation with excitation wavelength changes and complex, costly manufacturing processes for green phosphors.
Innovation Solution
A phosphor with a chemical structure represented by A(M1-a-xEuax)L(Si1-bGb)2O7, where A is Li, Na, or K, M is Mg, Ca, Sr, Ba, or Zn, and L is Ga, Al, Sc, Y, or Lu, with specific composition ratios, that emits green fluorescence effectively across blue to near-ultraviolet light ranges and can be manufactured at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a blue LED and yellow phosphor are used to create pseudo white light, then luminous efficiency is improved, but color rendering properties deteriorate
Solution Approach 1:
The patent combines multiple phosphors (yellow phosphor and green phosphor) with a blue LED to create a composite luminescent system. This merging of multiple phosphor materials allows the device to emit both yellow and green light in addition to blue light, thereby improving color rendering properties while maintaining high luminous efficiency through the blue LED's efficient light generation.
Solution Approach 2:
The invention uses a composite phosphor system consisting of yellow phosphor (e.g., Y3Al5O12:Ce3+) and green phosphor (e.g., Sr2Si5N8:Eu2+ or β-SiAlON:Eu2+) together with a blue LED. This composite material approach enables the light emitting device to produce a broader spectrum including blue, yellow, and green components, achieving both high efficiency and good color rendering properties simultaneously.
2Illumination intensity
If a green phosphor with Ce3+ emission center is used, then green light emission is achieved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent changes the emission characteristics of green phosphors by selecting materials with different emission mechanisms. Instead of using Ce3+ activated phosphors that require high-temperature processing, the invention employs Eu2+ activated phosphors (such as Sr2Si5N8:Eu2+ or β-SiAlON:Eu2+) that can be manufactured at lower temperatures and with simpler processes, while still achieving effective green light emission when excited by blue LED.
Solution Approach 2:
The invention adopts green phosphor materials that are easier and cheaper to manufacture, even if they have slightly different characteristics compared to premium Ce3+ phosphors. By using Eu2+ activated phosphors with simpler manufacturing requirements, the patent reduces manufacturing cost and process complexity while maintaining adequate green light emission performance for practical applications.
3Manufacturing precision
If high-temperature burning process is used to manufacture green phosphor, then phosphor quality is improved, but manufacturing facility requirements and process complexity increase
Solution Approach 1:
The patent changes the manufacturing parameters by selecting green phosphor materials that can be produced at lower temperatures. Instead of requiring high-temperature burning processes (1820°C to 2200°C) for Ce3+ activated phosphors, the invention uses Eu2+ activated phosphors that can be manufactured at significantly lower temperatures, thereby eliminating the need for complex high-temperature manufacturing facilities and simplifying the overall production process while maintaining acceptable phosphor quality.
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 provides stable emission intensity and improved luminous efficiency with high color rendering properties and simplified, cost-effective manufacturing.
Implementation Method 1
a photoluminescence phosphor having a garnet structure and containing cerium. The photoluminescence phosphor is able to absorb blue light, and emit an emission spectrum having a peak at a wavelength in a range from 530 nm to 570 nm
Implementation Method 2
a light emitting device including an LED and a phosphor for converting the wavelength of light emitted from the LED
Data Source
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AI summary
The present invention provides a phosphor emitting green fluorescence when being effectively excited by excitation light in a wavelength range from blue light to near-ultraviolet light, having an emission intensity that does not vary significantly with variation in the wavelength of the excitation light, and being manufactured easily. The phosphor includes a chemical structure represented by the following general formula (A): A(M1-a-xEuaMnx)L(Si1-bGeb)2O7, ··· (A), where A is one or more elements selected from Li, Na, and K, M is one or more elements selected from Mg, Ca, Sr, Ba, and Zn, L is one or more elements selected from Ga, Al, Sc, Y, La, Gd, and Lu, a is a numerical value satisfying 0.001≤a≤0.3, b is a numerical value satisfying 0≤b≤0.5, and x is a numerical value satisfying 0≤x≤0.2.