Oxynitride Phosphor Blend for High CRI White LEDs
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Solution Overview
Problem
Current white LED lighting systems based on blue-emitting InGaN chips with YAG:Ce phosphors fail to meet the color requirements for general illumination, particularly in achieving low correlated color temperatures (CCTs) and high color rendering indices (CRIs), necessitating the development of new phosphor compositions.
Innovation Solution
A blend of oxynitride phosphors is used in conjunction with semiconductor light sources, specifically designed to produce white light by combining blue or UV light with additional phosphors, allowing for customization of color output and enhancing color rendering capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If YAG:Ce phosphor is used with blue LED, then high quantum efficiency is achieved, but color rendering index and correlated color temperature are insufficient for general illumination
Solution Approach 1:
The patent uses a composite phosphor system combining YAG:Ce phosphor with other phosphors (such as red phosphors like CaAlSiN3:Eu2+ or green phosphors like β-SiAlON:Eu2+) to create a multi-component phosphor blend. This composite approach allows the system to maintain the high quantum efficiency of YAG:Ce while adding spectral components that improve color rendering index and adjust correlated color temperature, thereby resolving the contradiction between efficiency and color quality.
2Device complexity
If single phosphor system is used, then device complexity is low, but adaptability to different color requirements is limited
Solution Approach 1:
The patent employs dynamic phosphor blends where the composition, ratios, and particle size distributions of multiple phosphors can be adjusted to achieve different color outputs and correlated color temperatures. This dynamic formulation approach allows a single LED chip design to serve multiple lighting applications (warm white, cool white, tunable white) without changing the LED chip itself, thereby improving adaptability while managing complexity through standardized phosphor combination protocols.
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 oxynitride phosphor blend enables the production of white LEDs with higher color rendering indices and lower correlated color temperatures, effectively addressing the limitations of existing systems by providing a wider range of color options and improved lighting quality.
Implementation Method 1
A phosphor is a luminescent material that absorbs radiation energy in a portion of the electromagnetic spectrum and emits energy in another portion of the electromagnetic spectrum
Data Source
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AI summary
An oxynitride phosphor is presented. The oxynitride phosphor has a formula: ApBqOrNs: R such that A is barium or a combination of barium with at least one of Li, Na, K, Y, Sc, Be, Mg, Ca, Sr, Ba, Zn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu; B is silicon or a combination of silicon with at least one of Al, B, Ga, and Ge; R is europium or a combination of europium with at least one of Ce, Pr, Sm, Nd, Tb, Dy, Yb, Tm, Er, Ho, and Mn. p, q, r, s are numbers such that p is greater than about 2 and less than about 6, q is greater than about 8 and less than about 10, r is greater than about 0.1 and less than about 6, and s is greater than about 10 and less than about 15. The method of preparing the oxynitride phosphors and light emitting apparatus including the oxynitride phosphors are included.