LED Package Fluoride Phosphors for Color Rendering
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Solution Overview
Problem
White LED packages using yellow phosphors have low color rendering due to spectrum deficiencies in green and red zones, making it difficult to achieve natural colors, especially when used as backlight units, and existing phosphors with narrower full width at half maximum (FWHM) are vulnerable to moisture and heat, reducing reliability.
Innovation Solution
A light-emitting diode (LED) package incorporating a blue LED chip and phosphors that emit green and red light, with fluoride-based phosphors having a narrow FWHM, specifically a chemical formula of A2MF6:Mn4+, where A is Li, Na, K, Rb, Ce, and M is Si, Ti, Nb, and Ta, and Mn4+ within a molar range of 0.02 to 0.035 times M, to stabilize against moisture and heat, ensuring high reliability and color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If yellow light-emitting phosphor is used in white LED package, then the LED package can be manufactured, but color rendering is poor due to spectrum deficiency in green and red zones
Solution Approach 1:
The patent divides the single phosphor approach into multiple phosphors with different emission wavelengths. Specifically, it uses a blue LED chip (430-470nm) combined with yellow phosphor (560-580nm), green phosphor (500-560nm), and red phosphor (610-650nm) to segment the spectrum coverage, achieving comprehensive color rendering while maintaining manufacturability.
2Reliability
If multiple phosphors are used to improve color rendering, then color coordinates can be controlled, but device complexity increases
Solution Approach 1:
The patent combines multiple phosphors into a single integrated LED package structure. The blue LED chip is packaged with yellow, green, and red phosphors in one housing, merging the functions of wavelength conversion and light emission into a unified device. This approach controls color coordinates effectively while avoiding the complexity of separate light sources.
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 LED package achieves high color rendering with minimal change in light intensity and color coordinates, maintaining reliability under various environmental conditions, including high temperature and humidity, by using fluoride-based phosphors with controlled manganese content, enhancing the overall performance and stability of the LED package.
Implementation Method 1
A light-emitting diode (LED) package incorporating a blue LED chip and phosphors that emit green and red light
Data Source
AI summary
A light-emitting diode package includes a light-emitting diode chip disposed in a housing, a first phosphor configured to emit green light, and a second and a third phosphor configured to emit red light. White light is configured to be formed by a synthesis of light emitted from the light-emitting diode chip, the first phosphor, the second phosphor, and the third phosphor. At least one of the second and third phosphor is a nitride based phosphor that includes at least one of MSiN2, MSiON2, and M2Si5N8, where M is one of Ca, Sr, Ba, Zn, Mg, and Eu.