Chromaticity Adjusting Layer for LED Color Breakup
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Solution Overview
Problem
Semiconductor light-emitting devices that emit white light using a nitride semiconductor layer and a fluorescent material layer suffer from directional chromaticity differences due to varying intensity distributions of blue and yellow light, leading to color breakup issues.
Innovation Solution
Incorporating a chromaticity adjusting layer with a lower concentration of fluorescent material around the peripheral portion of the semiconductor light-emitting device, which helps in correcting the chromaticity by reducing excessive absorption of light and enhancing light extraction efficiency, thereby minimizing color breakup and improving light emission uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a fluorescent material layer with high concentration is used to enhance yellow light emission, then light extraction efficiency is improved, but chromaticity uniformity deteriorates due to excessive absorption in certain directions
Solution Approach 1:
The patent applies local quality by creating a chromaticity adjusting layer with a specific fluorescent material concentration distribution. The layer has a first region with a first concentration and a second region with a second concentration, where the concentration ratio varies spatially. This non-uniform concentration distribution allows different regions to have different light absorption characteristics, compensating for directional intensity differences and achieving uniform chromaticity while maintaining high light extraction efficiency.
2Illumination intensity
If the fluorescent material concentration is increased to improve light emission intensity, then light extraction efficiency is enhanced, but color breakup increases due to directional intensity differences
Solution Approach 1:
The patent employs parameter changes by systematically varying the fluorescent material concentration in different regions of the chromaticity adjusting layer. The concentration ratio between the first and second regions is specifically controlled within a certain range, and the absolute concentration is optimized. This parameter optimization allows the device to achieve high light emission intensity while maintaining uniform color appearance by compensating for directional intensity differences through controlled concentration variations.
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 chromaticity adjusting layer effectively suppresses color breakup and enhances light extraction efficiency by adjusting the fluorescent material concentration and refractive index, ensuring more uniform light emission across directions.
Implementation Method 1
a fluorescent material layer containing a fluorescent material to absorb the blue light and radiate yellow light
Data Source
AI summary
A semiconductor light-emitting device includes a semiconductor light-emitting layer, a pair of electrodes, a fluorescent material layer and a chromaticity adjusting layer. The semiconductor light-emitting layer emits first light. The pair of electrodes is connected to the semiconductor light-emitting layer. The fluorescent material layer covers at least a center portion of the semiconductor light-emitting layer, and contains a fluorescent material to absorb the first light and radiate second light. The chromaticity adjusting layer covers at least a peripheral portion of the semiconductor light-emitting layer, is exposed to outside, and contains a fluorescent material with a concentration lower than a concentration of the fluorescent material in the fluorescent material layer.