Lighting Device Phosphor Segmentation for Deep-Red Emission
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Solution Overview
Problem
Existing lighting technologies face challenges in achieving deep-red lighting with high efficiency and stability, as conventional phosphors require high concentrations leading to brightness losses and instability when exposed to radiation and temperature, and high phosphor concentrations result in scattering effects and processing difficulties.
Innovation Solution
A lighting device comprising a radiation source emitting primary radiation in the 300 nm to 570 nm range, a first phosphor converting this radiation into secondary radiation in the orange to red range, and filter particles, particularly ground glass filters, that absorb the secondary radiation, allowing for adjustable concentrations and reduced scattering, thereby achieving a deeper red emission with improved brightness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high concentrations of conventional phosphors are used to achieve deep-red emission, then the emission wavelength shifts toward longer wavelengths, but brightness losses occur due to high self-absorption and scattering effects
Solution Approach 1:
The patent segments the wavelength conversion process into two distinct stages: first phosphor particles convert blue light to orange-red light, and second phosphor particles convert orange light to deep-red light. This segmentation allows each phosphor to operate at optimal concentrations without excessive self-absorption, resolving the contradiction between achieving deep-red emission and maintaining brightness.
Solution Approach 2:
The first phosphor acts as an intermediary that converts blue LED light to orange-red light, which then serves as the excitation source for the second phosphor to produce deep-red emission. This intermediary conversion process enables deep-red generation without requiring excessively high concentrations of a single phosphor material.
2Illumination intensity
If high concentrations of phosphors are used to achieve deep-red lighting, then the emission shifts toward longer wavelengths, but processing becomes difficult
Solution Approach 1:
By dividing the phosphor system into two separate phosphor types with different concentration requirements, the patent enables independent optimization of each phosphor's concentration and distribution. This segmentation simplifies processing compared to attempting to achieve deep-red emission with a single high-concentration phosphor.
3Illumination intensity
If high fractions of strontium and europium are used in phosphors to achieve deep-red emission, then deep-red lighting is realized, but stability decreases when exposed to radiation and temperature
Solution Approach 1:
The patent employs a composite phosphor system combining two different phosphor materials: CaAlSiN3 phosphor for blue-to-orange-red conversion and M2(Al,Si)5(N,O)8 phosphor for orange-to-deep-red conversion. This composite approach distributes the functional requirements across materials with complementary stability profiles, improving overall system reliability while achieving deep-red emission.
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 enables a lighting device with enhanced color purity, increased light flux, and radiation power, while allowing for precise adjustment of color locations, particularly suitable for automotive applications, by effectively absorbing short-wave radiation and shifting the emission towards longer wavelengths.
Implementation Method 1
a first phosphor arranged in a beam path of the primary radiation source that converts at least part of the primary radiation into secondary radiation in an orange to red wavelength range of 570 nm to 800 nm
Implementation Method 2
filter particles arranged in a beam path of the secondary radiation that absorb at least part of the secondary radiation
Data Source
AI summary
A lighting device includes a radiation source that emits primary radiation in the wavelength range of 300 nm to 570 nm, a first phosphor arranged in a beam path of the primary radiation source that converts at least part of the primary radiation into secondary radiation in an orange to red wavelength range of 570 nm to 800 nm, and filter particles arranged in a beam path of the secondary radiation that absorb at least part of the secondary radiation.