LED Illumination Module with Wavelength Converting Materials
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Solution Overview
Problem
Light Emitting Diodes (LEDs) typically exhibit low Color Rendering Index (CRI) values, which limits their ability to faithfully reproduce colors compared to natural light sources, making it difficult to achieve high CRI values in illumination modules.
Innovation Solution
An illumination module with a light mixing cavity coated with wavelength converting materials, including Lutetium Aluminum Garnet doped with Cerium (LuAG:Ce), and photo-luminescent materials with specific peak emission wavelengths, is designed to convert LED light to approximate the spectral response of a blackbody radiator, achieving high CRI values by mixing light within the cavity and directing it through an output window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LEDs are used as illumination sources, then energy efficiency and longevity are improved, but color rendering index deteriorates
Solution Approach 1:
The illumination module segments the color conversion function by using multiple discrete phosphor materials (yellow phosphor, red phosphor, green phosphor) with distinct peak emission wavelengths. Each phosphor converts a portion of the blue LED light to a specific color range, collectively achieving a comprehensive spectral distribution that approximates blackbody radiation and delivers high CRI values while maintaining LED energy efficiency.
Solution Approach 2:
The patent employs composite phosphor materials with specific characteristics: yellow phosphor with peak wavelength 560-580nm, red phosphor with peak wavelength 610-650nm, and green phosphor with peak wavelength 520-540nm. These composite phosphor materials are applied to the cavity interior surfaces and output window to convert LED light into a multi-component spectral distribution that achieves both high energy efficiency and high color rendering index.
2Reliability
If wavelength converting materials are added to improve color rendering, then device complexity increases
Solution Approach 1:
The patent merges multiple phosphor materials into a unified illumination system where yellow phosphor, red phosphor, and green phosphor are applied to the cavity interior surfaces and output window. These separate phosphor materials work together in combination to convert blue LED light into a comprehensive spectral distribution, achieving high CRI values while maintaining a relatively simple overall device structure.
Solution Approach 2:
The cavity interior surfaces and output window serve multiple functions: they act as structural boundaries of the illumination module, reflectors for light direction, and substrates for phosphor material application. By integrating the phosphor conversion function into existing structural components, the patent avoids adding separate complex conversion devices, thereby improving color rendering while minimizing increases in device complexity.
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 module achieves CRI values close to those of a blackbody radiator, with a color conversion efficiency ratio greater than 130 lm/W, significantly improving color rendering across the visible spectrum.
Implementation Method 1
A portion of the window is coated with a first wavelength converting material and a portion of the interior surface area is coated with a second wavelength converting material
Implementation Method 2
a second photo-luminescent material with a peak emission wavelength between 615 and 655 nanometers
Implementation Method 3
a first photo-luminescent material with a peak emission wavelengths between 508 and 528 nanometers
Implementation Method 4
The LED may emit a first colored light that is converted by the light mixing cavity to a second color light
Data Source
AI summary
An illumination module includes a light mixing cavity with an interior surface area and window that are physically separated from an LED. A portion of the window is coated with a first wavelength converting material and a portion of the interior surface area is coated with a second wavelength converting material. The window may be coated with LuAG:Ce. The window may also be coated with a third wavelength converting material with a peak emission wavelength between 615-655 nm where the spectral response of light emitted from the window is within 20% of a blackbody radiator at the same CCT. The LED may emit a light that is converted by the light mixing cavity with a color conversion efficiency ratio greater than 130 lm/W where the light mixing cavity includes two photo-luminescent materials with a peak emission wavelengths between 508-528 nm and 615-655 nm.