Eu3+-Doped Ceramic Converter for Laser-Excited Red Light
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Solution Overview
Problem
Modern LED-based light sources with cerium-doped YAG converters have poor color rendering index and efficiency due to limited blue light absorption, leading to low luminance and luminous efficacy.
Innovation Solution
A light source using an Eu3+-doped inorganic phosphor excited by a narrowband laser at 465 nm, which enhances absorption and emission of red light, improving luminance and color rendering index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a red emitting converter is used to improve color rendering index, then color rendering is improved, but blue light absorption is insufficient leading to poor efficiency
Solution Approach 1:
The patent changes the excitation wavelength parameter from broadband LED emission to narrowband laser emission at 465 nm, which precisely matches the absorption peak of Eu3+ ions. This parameter change enables the red converter to absorb excitation light efficiently while maintaining improved color rendering index
Solution Approach 2:
The patent introduces a laser as an intermediary device between the electrical power source and the red converter. The laser converts electrical energy to narrowband optical energy at 465 nm, which then efficiently excites the Eu3+ ions in the red converter, solving the absorption efficiency problem
2Device complexity
If a broadband LED is used to excite the red phosphor, then the device is simple, but the narrow absorption line width of the phosphor results in poor efficiency
Solution Approach 1:
The patent changes the spectral width parameter of the excitation source from broadband (LED) to narrowband (laser). This parameter change enables precise matching with the narrow absorption line width of the red phosphor, dramatically improving luminous efficacy despite increased device complexity
3Illumination intensity
If high power is used to achieve high luminance, then luminance is improved, but thermal management becomes more difficult
Solution Approach 1:
The patent converts the harmful thermal effect into a beneficial selection criterion by choosing a laser excitation source that operates at 465 nm, which matches the absorption peak of Eu3+ ions. This precise matching maximizes energy transfer efficiency and minimizes waste heat generation, enabling high luminance with improved thermal management
Solution Approach 2:
The patent changes the excitation wavelength parameter to 465 nm, which optimizes the absorption efficiency of the red converter. This parameter change reduces the energy mismatch between excitation and absorption, thereby reducing waste heat and improving thermal management while maintaining high luminance
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 achieves higher luminance and luminous efficacy compared to LED-based systems, with improved color rendering and thermal management through the use of ceramic converters and heat spreaders.
Implementation Method 1
a laser that is operable to emit laser light at a wavelength in the range from 460 nanometers to 470 nanometers
Implementation Method 2
a converter assembly which is adapted so as to absorb the laser light emitted by the laser and to emit photoluminescent light produced by the laser light and having a longer wavelength than the laser light
Implementation Method 3
the converter element may also be referred to as a luminescent inorganic element... under irradiation of the laser light the converter emits photoluminescent light in the red spectral range
Data Source
AI summary
A light source is provided that includes a laser operable to emit laser light at a wavelength in a range from 460 nanometers to 470 nanometers and a converter assembly arranged so as to absorb the laser light emitted by the laser and to emit photoluminescent light produced by the laser light and having a longer wavelength than the laser light. The converter assembly has a converter element with a ceramic doped with Eu3+ such that under irradiation of the laser light the converter assembly emits photoluminescent light in the red spectral range.