Neodymium-Coated Green Phosphor for Wide-Gamut Display Stability
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Solution Overview
Problem
Conventional green phosphors used in low-priced TVs and displays suffer from reduced color purity, particularly in the green and red color gamut, limiting the wide color gamut requirement for liquid crystal displays.
Innovation Solution
A green phosphor is developed by attaching neodymium-containing particles to inorganic phosphor particles, specifically Eu-activated β-SiALON phosphor particles, with a silicon oxide coating, to achieve a high color purity and stability under high-temperature, high-humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional yellow phosphor YAG:Ce is used in low-priced TVs and displays, then cost is reduced, but color purity of green and red is reduced and color gamut becomes narrower
Solution Approach 1:
The invention segments the phosphor system into multiple wavelength components (blue LED at 440-480nm, green phosphor at 500-570nm, red phosphor at 610-680nm) to achieve wide color gamut. This segmentation allows each component to be optimized independently for its specific wavelength range, resolving the contradiction between cost and color purity by using targeted phosphor materials rather than broad-spectrum yellow phosphor.
Solution Approach 2:
The invention uses composite phosphor materials including SrGa2S4:Eu, MGa2S4:Eu, and β-SiAlON:Eu in specific combinations to achieve both cost-effectiveness and high color purity. The composite approach allows optimization of each material's properties for specific wavelength ranges while maintaining overall system affordability.
2Stability of the object's composition
If green emission phosphor and red emission phosphor are used to widen color gamut, then color purity is improved, but device complexity increases due to three-wavelength type white LED system
Solution Approach 1:
The invention merges multiple phosphor materials (green emission phosphor and red emission phosphor) into a single integrated phosphor layer that can be applied directly to blue LEDs. This combining approach maintains wide color gamut performance while simplifying the overall device structure compared to separate phosphor layers or multiple LED types.
Solution Approach 2:
The invention uses blue LEDs (440-480nm) as a universal excitation source that can simultaneously excite both green and red phosphors. This multi-functional approach allows a single LED type to drive the entire three-wavelength system, reducing device complexity while maintaining high color purity.
3Stability of the object's composition
If neodymium-containing particles are attached to inorganic phosphor particles, then color purity is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The invention uses an intermediary material (such as silicon oxide coating or organic binder) between the inorganic phosphor particles and neodymium-containing particles. This intermediary layer facilitates uniform attachment and distribution, reducing manufacturing precision requirements while maintaining the color purity enhancement benefits of neodymium incorporation.
Solution Approach 2:
The invention optimizes parameters such as neodymium particle size (0.1-10 μm), attachment concentration (1-50 wt%), and distribution uniformity to achieve high color purity with relaxed manufacturing precision requirements. By controlling these parameters within specific ranges, the system achieves optimal performance without requiring extremely precise manufacturing.
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 enhances color purity and stability of the green phosphor, leading to improved light-emission properties and extended luminous flux maintenance rate in light-emitting devices, particularly in high-temperature, high-humidity environments.
Implementation Method 1
The SrGa2S4:Eu phosphor or a MGa2S4:Eu phosphor (M=Ba, Sr and/or Ca) has been proposed for increasing the internal quantum efficiency... A green light-emitting phosphor having a light-emission local maximum wavelength in the range of from about 500 nm to about 570 nm is, for example, a SrGa 2 S 4 :Eu phosphor. The SrGa 2 S 4 :Eu phosphor is excited by light in the range of from near ultraviolet to blue
Implementation Method 2
neodymium-containing particles attached on a surface of the inorganic phosphor particle
Data Source
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AI summary
A green phosphor including: an inorganic phosphor particle; and neodymium-containing particles attached on a surface of the inorganic phosphor particle, wherein the green phosphor has a light-emission local maximum wavelength in a range of from 500 nm to 570 nm.