Blue-Green Phosphor Composition for LED Color Rendering
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Solution Overview
Problem
Conventional white LED backlights using blue LEDs and yellow phosphors suffer from quantum deficits, efficiency reduction, and poor color rendering due to the lack of green and red color ingredients, limiting their application and requiring a large amount of red phosphor, which reduces luminous intensity.
Innovation Solution
A bluish green phosphor with a specific composition ratio, represented by Ba x Mg y Si b O c N d F e :Eu g, is developed, which has a single phase crystal structure and improved thermal stability, enhancing the luminance and color rendering index when combined with green and red phosphors in a light emitting device package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional blue LED with yellow phosphor is used, then easy driving and low price are achieved, but quantum deficits occur, efficiency is reduced, and color rendering is poor due to lack of green and red ingredients
Solution Approach 1:
The patent changes the phosphor material parameters from conventional yellow phosphor to a combination of green phosphor (β-SiAlON:Eu) and red phosphor (CaAlSiN3:Eu), fundamentally altering the spectral output parameters to include green and red wavelength components while maintaining manufacturing feasibility
Solution Approach 2:
The patent employs a composite phosphor system combining multiple phosphor materials (green phosphor and red phosphor) with the blue LED chip, creating a multi-component light conversion system that achieves superior color rendering and efficiency compared to single-phosphor systems
2Ease of manufacture
If conventional blue LED with yellow phosphor is used, then easy driving and low price are achieved, but color rendering is unnatural due to deficiency of green and red color ingredients
Solution Approach 1:
The patent fundamentally changes the spectral output parameters by selecting phosphor materials with specific emission wavelengths - green phosphor emitting at 520-560 nm and red phosphor emitting at 610-670 nm - to achieve natural color rendering while maintaining manufacturing simplicity
Solution Approach 2:
The patent creates a composite lighting system combining blue LED chip with green and red phosphors, where each component contributes specific wavelength ranges to produce a complete spectrum that renders colors naturally
3Illumination intensity
If large amount of red phosphor is used to improve color rendering, then color rendering is improved, but luminous intensity is lowered
Solution Approach 1:
The patent optimizes the composition parameters of the red phosphor (CaAlSiN3:Eu) and green phosphor (β-SiAlON:Eu) to achieve high color rendering index while maintaining high luminous efficiency, eliminating the need to use excessive amounts of red phosphor
Solution Approach 2:
The patent employs a balanced composite phosphor system where green and red phosphors work synergistically with the blue LED excitation source, achieving both excellent color rendering and high luminous intensity through optimized material combinations rather than relying on large amounts of a single phosphor type
4Illumination intensity
If phosphors are combined to generate three primary color ingredients, then color rendering may be improved, but it is not easy to maintain color rendering of 90 or more and luminous intensity may be lowered
Solution Approach 1:
The patent optimizes the emission wavelength parameters of the green phosphor (520-560 nm) and red phosphor (610-670 nm) to achieve a color rendering index of 90 or higher while maintaining high luminous intensity, simplifying the design process compared to conventional multi-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 bluish green phosphor improves light intensity and thermal stability, resulting in enhanced luminance and color rendering index for white LED devices, reducing the need for excessive red phosphor and maintaining high luminous intensity.
Implementation Method 1
a phosphor emitting blue light as an excitation source to yellow light is coated over a device emitting blue light, to realize white light by mixing blue light emitted from the device and yellow light emitted from the phosphor
Implementation Method 2
phosphors having reduced luminance deterioration and using silicon nitride-related ceramics as a host crystal, nitrides or phosphors which have a stable crystal structure and may shift excitation light or luminescence to a longer wavelength
Data Source
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AI summary
Embodiments of the present invention provide a bluish green phosphor represented by Formula 1 below. In particular, the bluish green phosphor and a light emitting device package including the same may have superior luminescence characteristics and improved temperature stability by selecting composition ratios of each ingredients included in a composition formula and ions and thereby minimizing lattice defects in a crystal structure: [Formula 1] AaBbOcNdCe:REh wherein A is at least one selected from the group consisting of Be, Mg, Ca, Sr, Ba and Ra elements, B is at least one selected from the group consisting of Si, Ge and Sn elements, C is any one of C, Cl, F and Br elements, RE is at least one selected from the group consisting of Eu, Ce, Sm, Er, Yb, Dy, Gd, Tm, Lu, 0<a≤15, 0<b≤15, 0<c≤15, 0<d≤20, 0<e≤10, and 0<h≤10.