Layered Phosphor Conversion for LED Spectral Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LED packages with mixed phosphor components suffer from significant 'cross-talk' or 'overlap' between emission and excitation spectrums, leading to reduced color rendering index (CRI) and efficiency due to re-absorption of light, which distorts the white light output and results in additional efficiency losses.
Innovation Solution
The use of separate, layered phosphor configurations where each phosphor type is applied in a specific order, with the longest emission wavelength phosphor first, to minimize overlap between emission and excitation spectrums, allowing light to be emitted without re-absorption, thereby enhancing CRI and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If mixed phosphor components are used in conventional LED packages, then color rendering index (CRI) and efficiency are improved, but significant cross-talk or overlap between emission and excitation spectrums occurs causing re-absorption of light
Solution Approach 1:
The phosphor conversion layer is divided into multiple separate layers, each containing a different phosphor material with distinct emission and excitation spectra. This segmentation prevents spectral overlap and re-absorption between different phosphor components, thereby reducing energy loss while maintaining high emission intensity and CRI.
2Illumination intensity
If mixed phosphor components are used in conventional LED packages, then color rendering index (CRI) is improved, but re-absorption of light distorts white light output
Solution Approach 1:
Different phosphor materials are separated into distinct layers, each optimized for specific wavelength conversion. This prevents the spectral mixing and re-absorption that causes white light distortion, while maintaining accurate color rendering through controlled emission from each layer.
3Loss of energy
If separate, layered phosphor configurations are used, then re-absorption is minimized and CRI is enhanced, but device complexity increases
Solution Approach 1:
The patent transitions from horizontal mixing of phosphors in a single layer to vertical stacking of multiple phosphor layers. This dimensional change allows efficient spectral management without increasing lateral complexity, as each layer can be applied sequentially using standard coating processes.
4Illumination intensity
If more conversion material is used to compensate for re-absorption losses, then emission intensity is maintained, but cost increases
Solution Approach 1:
By separating phosphor materials into distinct layers with non-overlapping spectra, the patent eliminates re-absorption losses. This allows achieving high emission intensity with optimized quantities of each phosphor material, reducing total conversion material requirements compared to mixed-phosphor approaches that require excess material to compensate for losses.
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 approach results in improved emission intensity, higher CRI, and reduced need for costly conversion materials, achieving enhanced emission efficiency and cost savings by minimizing re-absorption and maintaining high CRI across various temperature ranges.
Implementation Method 1
different conversion material layers, each of which absorbs light from the LED chip and reemits light in a different wavelength spectrum
Data Source
Figure 1~3
Figure 4~7
Figure 8~11
AI summary
Light emitting diodes are disclosed that utilize multiple conversion materials in the conversion process in order to achieve the desired emission color point. Embodiments of the present invention comprise different phosphor types in separate layers (56a, 56b), on or above one or a plurality of LED chips (52), to achieve a desired light conversion. The LEDs can then emit a desired combination of light from the LED chips and conversion material. Conversion materials can be applied as layers of different phosphor types in order of longest emission wavelength phosphor first, followed by shorter emission phosphors in sequence as opposed to applying in a homogeneously mixed phosphor converter. The conversion material layers can be applied as a blanket over the LED chips and the area surrounding the chip, such as the surface of a submount holding the LED chips.