Phosphor Separation in LED Packages to Reduce Re-absorption
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Solution Overview
Problem
Conventional LED packages with mixed phosphors suffer from significant 'cross-talk' or 'overlap' between the emission and excitation spectra, leading to reduced color rendering index (CRI) and efficiency losses due to re-absorption of light, which distorts the resulting white light emission.
Innovation Solution
The solution involves separating the phosphor components to minimize the interaction between different phosphors, ensuring that re-emitted light from one phosphor does not encounter the other, thereby reducing re-absorption and maintaining higher CRI and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple phosphors are mixed in a conventional LED package, then color rendering can be improved, but cross-talk between phosphors causes re-absorption of light and reduces CRI and efficiency
Solution Approach 1:
The patent divides the phosphor conversion system into separate, spatially distinct phosphor layers or particles rather than mixing them together. Each phosphor is separated to prevent optical interaction, eliminating cross-talk and re-absorption losses while maintaining the beneficial color rendering properties of multiple phosphors.
Solution Approach 2:
The patent introduces an intermediary medium (such as a transparent matrix or carrier material) that holds separate phosphor particles or layers in spatial separation. This intermediary structure prevents direct optical interaction between phosphors while allowing each to function independently for color conversion.
2Loss of energy
If phosphors are separated to reduce cross-talk, then efficiency and CRI improve, but device structure becomes more complex
Solution Approach 1:
The patent combines multiple separated phosphor elements into a single integrated structure, such as a unified phosphor carrier or substrate that holds multiple phosphor types in separate regions. This merging approach maintains separation benefits while simplifying the overall device structure and manufacturing process.
Solution Approach 2:
The patent applies different phosphor materials to different local regions or zones within the LED package, with each region optimized for specific wavelength conversion. This localized approach allows phosphor separation to prevent cross-talk while maintaining a relatively simple overall structure through spatial differentiation rather than complex multi-component assembly.
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
This separation approach results in a higher CRI and improved phosphor efficiency, producing a more stable and efficient white light emission with reduced thermal and optical quenching, leading to cost savings and longer lamp life.
Implementation Method 1
Light emitted by the LED at a first wavelength may be absorbed by the phosphor, which may responsively emit light at a second wavelength
Data Source
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AI summary
LED packages, and LED lamps (340) and bulbs, are disclosed that are arranged to minimize the CRI and efficiency losses resulting from the overlap of conversion material emission and excitation spectrum. In different devices having conversion materials with this overlap, the present invention arranges the conversion materials to reduce the likelihood that re-emitted light from a first conversion materials will encounter the second conversion material to minimize the risk of re-absorption. In some embodiments this risk is minimized by different arrangements where there is separation between the two phosphors (342, 344). In some embodiments this separation results less than 50% of re- emitted light from the one phosphor passing into the phosphor where it risks re-absorption.