Violet-UV LED Pumping Multiple Phosphors for Green Light
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Solution Overview
Problem
Existing high-intensity, high-efficiency InGaN-based green LEDs are difficult to produce on a wide scale and have limitations in achieving high intensity and efficiency, with conventional LED lighting systems facing challenges in maintaining performance at high current densities and temperatures.
Innovation Solution
The use of LEDs emitting radiation at violet and ultraviolet wavelengths to pump phosphor materials, with a peak emission wavelength of 405 to 430 nm, combined with multiple phosphors to enhance light-output efficiency and maintain high internal quantum efficiency at high current densities and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If InGaN-based green LEDs are used to achieve high intensity and efficiency, then light output performance is improved, but manufacturing difficulty and production cost increase significantly
Solution Approach 1:
The patent uses violet/UV LEDs as an intermediary light source to pump phosphor materials, which then emit the desired green light. This indirect approach avoids the difficulty of directly manufacturing high-performance green InGaN LEDs, while still achieving high intensity and efficiency through the phosphor conversion process.
Solution Approach 2:
The patent changes the wavelength parameter of the LED from green (difficult to manufacture) to violet/UV (easier to manufacture with high efficiency), and uses phosphor materials to convert this light to the desired green spectrum. This parameter substitution resolves the manufacturing difficulty while maintaining performance.
2Power
If conventional LED lighting systems operate at high current densities, then light output increases, but internal quantum efficiency decreases due to performance degradation
Solution Approach 1:
By introducing phosphor materials as an intermediary between the violet/UV LED and the final light output, the system decouples the high current density operation from the light emission process. The phosphor converts the LED light efficiently, maintaining high internal quantum efficiency even when the LED operates at high power levels.
3Power
If conventional LED lighting systems operate at elevated temperatures, then operational stability is challenged, but light output must be maintained
Solution Approach 1:
The phosphor materials serve as a thermal buffer, absorbing the violet/UV LED light and converting it to longer wavelengths. This conversion process is less sensitive to temperature variations, allowing the system to maintain stable light output even when operating at elevated temperatures, as the phosphor conversion efficiency remains relatively stable.
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
This approach results in high-performance white LED light sources with improved light-extraction efficiency, color stability, and tunable color gamut, while reducing Stokes loss and operational voltage, and maintaining high internal quantum efficiency even at elevated temperatures.
Implementation Method 1
The LED includes a gallium and nitrogen containing substrate having a surface region and a gallium and nitrogen containing buffer layer overlying the surface region. An active region emits electromagnetic radiation with peak wavelengths in a range from about 405 nm to about 430 nm
Implementation Method 2
The mixture of phosphor materials is disposed within a vicinity of the LED interacts with the electromagnetic radiation from the LED to convert the electromagnetic radiation to a wavelength range between about 440 to 650 nanometers
Data Source
AI summary
An LED pump light with multiple phosphors is described. LEDs emitting radiation at violet and/or ultraviolet wavelengths are used to pump phosphor materials that emit other colors. The LEDs operating in different wavelength ranges are arranged to reduce light re-absorption and improve light output efficiency.