LED and Phosphor Combinations for High Luminous Efficacy Lighting
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Solution Overview
Problem
Existing LED systems face inefficiencies in combining light from direct emitting LEDs and phosphor converted LEDs to achieve desired white light with specific color points and correlated color temperatures, due to interactions between phosphors and differing drive current and temperature behaviors.
Innovation Solution
A light emitting device comprising three groups of LEDs configured to emit blue, cyan/yellow, and red color points, with some LEDs being phosphor converted to improve efficiency and tunability, allowing for desaturation of primary colors to achieve a desired white light output by varying drive currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple phosphors are combined with a single blue emitting LED, then white light with desired color point can be achieved, but efficiency is reduced due to phosphor interactions and absorption
Solution Approach 1:
The patent divides the single phosphor conversion system into multiple independent phosphor conversion paths, each with its own blue LED excitation source. This segmentation eliminates harmful phosphor-phosphor absorption interactions while maintaining the ability to achieve desired white light color points through independent control of each phosphor group's emission characteristics.
2Illumination intensity
If light from direct emitting LEDs and phosphor converted LEDs is combined, then desired white light color point can be achieved, but efficiency is reduced due to differing drive current and temperature behaviors
Solution Approach 1:
The patent merges multiple phosphor conversion systems into a unified white light generation architecture where all phosphor groups are excited by blue LEDs. This integration allows for coordinated control of all light emission paths, achieving desired white light color points while improving overall efficiency by eliminating the need to combine light from directly emitting LEDs with different drive and temperature characteristics.
3Loss of energy
If primary colors are desaturated to improve efficiency, then luminous efficacy is enhanced, but color tunability is reduced
Solution Approach 1:
The patent implements dynamic control of multiple phosphor groups with different emission characteristics (cyan, yellow, red). By independently adjusting the excitation intensity of each phosphor group, the system can dynamically tune the output color point and correlated color temperature while maintaining high luminous efficacy, even when individual phosphors are operated in a desaturated regime for efficiency.
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 the luminous efficacy and color tunability of the light emitting device by optimizing the combination of LEDs and phosphors, allowing for precise control over the white light output and improved color rendering indices.
Implementation Method 1
An LED combined with one or more wavelength converting materials may be used to create white light or monochromatic light of other colors
Implementation Method 2
Combining multiple phosphors with a single blue emitting LED can result in interactions between the phosphors, for example absorption by one phosphor of light emitted by another
Data Source
AI summary
A light emitting device comprises a first group of one or more LEDs each configured to emit light having a blue color point in the 1931 CIE x,y Chromaticity Diagram, a second group of one or more LEDs each configured to emit light having a cyan or yellow color point in the 1931 CIE x,y Chromaticity Diagram, and a third group of one or more LEDs each configured to emit light having a red color point in the 1931 CIE x,y Chromaticity Diagram.