LED Package Non-Uniform Phosphor Distribution Yellow Halo
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Solution Overview
Problem
White-light LED light-emitting devices often exhibit a yellow halo due to the LED package structure, which degrades illumination effects, especially at cold color temperatures, as the current uniform phosphor distribution leads to inadequate blue light excitation in edge portions, resulting in unexcited phosphors and a decrease in color temperature.
Innovation Solution
A non-uniform wavelength converting layer with a lower amount of red phosphor in the edge portion compared to the center portion is used, ensuring adequate blue light excitation and reducing red light generation, thereby maintaining a higher color temperature and alleviating the yellow halo issue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform amount of red phosphor is distributed across the LED chip, then the manufacturing process is simple, but the edge portion generates excessive red light causing yellow halo and degraded illumination effects
Solution Approach 1:
The patent applies local quality by creating a non-uniform phosphor distribution where the edge portion has a different phosphor amount compared to the center portion. Specifically, the edge portion is designed to have either a lower amount of red phosphor or a higher amount of blue phosphor, depending on the embodiment, to locally adjust the light emission characteristics and eliminate the yellow halo effect that occurs with uniform distribution.
2Temperature
If the red phosphor amount is decreased in the edge portion, then the color temperature is maintained higher and yellow halo is reduced, but the manufacturing precision requirement increases
Solution Approach 1:
The patent applies segmentation by dividing the phosphor distribution into distinct regions: a center portion and an edge portion. This segmentation allows independent control of phosphor characteristics in each region, with the edge portion being further divided into different angular ranges (first, second, and third emitting angle ranges) with progressively varying phosphor amounts, enabling precise control over color temperature and elimination of yellow halo.
3Illumination intensity
If the phosphor distribution is adjusted to improve light emission uniformity, then the illumination effects are enhanced, but the device complexity increases
Solution Approach 1:
The patent implements local quality by configuring different phosphor compositions in different spatial regions of the edge portion. The first, second, and third emitting angle ranges within the edge portion each have tailored phosphor distributions, allowing precise control of light emission characteristics in different directions while maintaining a relatively simple overall package structure.
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 effectively stabilizes the dominant wavelength and color temperature across various emitting angles, improving the uniformity and quality of light emission by adjusting the red phosphor distribution, thus enhancing illumination effects.
Implementation Method 1
the wavelength converting layer includes a red phosphor
Implementation Method 2
direct or indirect excitation for generating red light in an edge portion of the LED chip may be avoided
Data Source
AI summary
The present disclosure provides a LED package structure and a LED light-emitting device. The LED package structure comprises a LED chip and a wavelength converting layer covering the LED chip. The wavelength converting layer contains red phosphor, which has lower amount in edge portion than in center portion. It is possible to avoid direct or indirect excitation for generating red light in edge portion of the LED chip by adjusting the amount of red phosphor in edge portion to be lower, so that the color temperature in edge portion may be adjusted toward to high color temperature, and thus the phenomenon of yellow halo may be alleviated.