Phosphor Converted LED Stability and Lumen Equivalent
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Solution Overview
Problem
Phosphor converted LEDs face stability issues while maintaining a high lumen equivalent and color rendering index, with quantum dot materials having environmental compatibility problems and limited lifespan, and existing red emitting phosphors experiencing stability problems.
Innovation Solution
A phosphor converted LED design incorporating two luminescent materials that convert blue light into orange/red and red light, with one material emitting in the deep red range minimized to prevent lumen equivalent reduction and the other providing broad red and orange spectral emission, using a hybrid approach with quantum dots and Eu2+ phosphors to maintain high color rendering index and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If quantum dot materials are used to improve lumen equivalent by limiting deep red light emission, then lumen equivalent increases, but reliability and lifespan deteriorate due to instability and environmental compatibility issues
Solution Approach 1:
The patent combines quantum dots with conventional phosphors (YAG:Ce for green, CaAlSiN3:Eu for red) to create a composite phosphor system. This composite approach allows the quantum dots to provide narrow-band red emission for high lumen equivalent while the stable conventional phosphors ensure long-term reliability and compensate for quantum dot instability.
2Loss of energy
If narrow band red emitting luminescent materials are used to improve lumen equivalent, then lumen equivalent increases, but reliability deteriorates due to stability problems
Solution Approach 1:
The patent merges narrow-band red emitting quantum dots with broad-band red emitting CaAlSiN3:Eu phosphor. The quantum dots contribute to high lumen equivalent through their narrow emission spectrum, while the CaAlSiN3:Eu phosphor provides stability and additional red light coverage, creating a synergistic effect that resolves the contradiction between lumen equivalent and reliability.
3Reliability
If deep red light emission is increased to improve color rendering index, then color rendering index improves, but lumen equivalent decreases due to reduced eye sensitivity in deep red region
Solution Approach 1:
The patent applies local quality by using quantum dots with specifically tuned emission wavelengths (610-620 nm) that target the optimal red region for both color rendering and human eye sensitivity. This localized spectral optimization ensures adequate color rendering without excessive deep red emission that would reduce lumen equivalent.
4Loss of energy
If quantum dot materials are used to achieve narrow emission spectrum, then lumen equivalent improves, but environmental compatibility deteriorates due to Cadmium and Selenide content
Solution Approach 1:
The patent uses conventional phosphors (CaAlSiN3:Eu, YAG:Ce) as intermediary materials that can be mixed with quantum dots. These intermediaries provide a stable matrix that contains the quantum dots, allowing the system to achieve high lumen equivalent while the overall composite material can be designed to meet environmental standards through proper encapsulation and material selection.
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 a stable phosphor converted LED with a high lumen equivalent and color rendering index, reducing the amount of quantum dots required and minimizing environmental impact, while enhancing the lifespan and stability of the LED.
Implementation Method 1
The first luminescent material absorbs a portion of the light of the first spectral distribution and converts at least a portion of the absorbed light towards light of a second spectral distribution
Implementation Method 2
The second luminescent material absorbs a portion of the light of the first spectral distribution and converts at least a portion of the absorbed light towards lights of a third spectral distribution
Implementation Method 3
The third luminescent material absorbs a portion of the light of the first spectral distribution and converts at least a portion of the absorbed light towards light of a fourth spectral distribution
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 3a~3b
AI summary
A phosphor converted Light Emitting Diode (LED), a lamp and a luminaire are provided. The phosphor converted LED 106 comprises a LED 102, a first luminescent material166, a second luminescent material 164 and a third luminescent material 162. The LED 102 emits a first spectral distribution having a first peak wavelength in the blue spectral range. The first luminescent material 166 absorbs a portion of the light of the first spectral distribution and converts at least a portion of the absorbed light towards light of a second spectral distribution. The second spectral distribution has a second peak wavelength in the green spectral range. The second luminescent material 164 absorbs absorbing a portion of the light of the first spectral distribution and/or a portion of the second spectral distribution. The second luminescent material 164 converts at least a portion of the absorbed light towards lights of a third spectral distribution. The third spectral distribution has a third spectral width and has a third peak wavelength. The third luminescent material 162 absorbs a portion of the light of at least one of the first spectral distribution,second spectral distribution, and the third spectral distribution. The third luminescent material 162 converts at least a portion of the absorbed light towards light of a fourth spectral distribution. The fourth spectral distribution has a fourth spectral width and has a fourth peak wavelength. The third peak wavelength and the fourth peak wavelength are in the orange/red spectral range. The third peak wavelength is smaller than the fourth peak wavelength and the third spectral width is larger than the fourth spectral width.