Luminescence Conversion LED With Segmented Phosphor Layers
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Solution Overview
Problem
Conventional luminescence conversion LEDs face a trade-off between high efficiency and good color rendering due to the mutual absorption of phosphors, where using multiple phosphors in a homogeneous resin mixture leads to reduced efficiency and poorer color rendering.
Innovation Solution
A thin-film LED configuration where a red phosphor is applied directly onto the chip as a thin layer, followed by a separate layer of green or yellow phosphor in the encapsulation resin, minimizing mutual absorption and enhancing efficiency and color rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two phosphors are distributed homogeneously in the resin, then the manufacturing process is simplified, but mutual absorption between phosphors increases leading to reduced efficiency and poorer color rendering
Solution Approach 1:
The patent divides the phosphor layer into two distinct layers: a first phosphor layer directly on the chip and a second phosphor layer in the encapsulation resin. This segmentation reduces mutual absorption between phosphors while maintaining manufacturing feasibility, as each layer can be applied using standard techniques but with improved spatial separation.
Solution Approach 2:
The patent transitions from a homogeneous three-dimensional mixture of phosphors in resin to a stratified two-layer structure. This dimensional reorganization separates the phosphors in the vertical dimension (distance from chip), reducing their mutual absorption while preserving the simplicity of resin-based application methods.
2Ease of manufacture
If two phosphors are distributed homogeneously in the resin, then the manufacturing process is simplified, but color rendering quality deteriorates due to phosphor absorption interference
Solution Approach 1:
By segmenting the phosphor distribution into two separate layers, the patent eliminates the spectral interference that occurs in homogeneous mixtures. The first phosphor layer converts blue light to its emission wavelength, and the second phosphor layer converts the remaining blue light plus some first phosphor emission, achieving accurate color rendering without mutual absorption shifts.
Solution Approach 2:
The vertical stratification allows each phosphor to operate in its optimal spectral region without interference from the other phosphor's absorption bands, enabling precise color rendering while maintaining ease of manufacture through sequential application.
3Manufacturing precision
If phosphor layer thickness is increased to improve color rendering, then more phosphor material is available for conversion, but absorption losses increase reducing overall efficiency
Solution Approach 1:
The patent applies the segmentation principle to phosphor layer thickness by distributing the total phosphor material into two layers with optimized individual thicknesses. The first layer has sufficient thickness for effective conversion without being so thick as to cause excessive absorption, while the second layer provides additional conversion capability with reduced mutual absorption interference.
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 highly efficient LEDs with improved color rendering indices and homogeneous emission characteristics, increasing the LED's overall efficiency while maintaining high color quality.
Implementation Method 1
a first, thin layer (11) of red phosphor is applied directly onto the short-wave emitting chip... first phosphor layer (11), which is applied directly to the chip 2, while the second phosphor (6), which emits green, on the first narrow layer as a second, more distant layer is applied
Implementation Method 2
second phosphor (6), which emits green, on the first narrow layer as a second, more distant layer is applied in the casting resin (5)
Implementation Method 3
a design in which a thin-film chip is used is preferred, this being equipped with an integrated reflector so that backscattered radiation is not lost
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a luminescence conversion of LED which uses a blue emitting chip and two illuminating substances, whereby one emits a red and the other a yellow to green. Both illuminating substances are separated upstream from the chip.