White LED Phosphor Resin Layer for Uniform Light Emission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
White LED lamps using ultraviolet emitting diodes and multiple phosphors suffer from unevenness in emitted and projected light, leading to nonuniformity and color differences, which are undesirable in lighting applications.
Innovation Solution
A light emitting device incorporating a light source with a plurality of phosphors of different emission colors, where the phosphors are integrated using an inorganic binder and optimized particle size distribution to ensure uniform dispersion, reducing the color difference between emission chromaticity measured directly above the light source and that measured for front and side leakage lights, with Δx and Δy values less than 0.05.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an ultraviolet emitting LED chip and multiple phosphors are combined, then white light can be emitted, but unevenness in emitted light and projected light occurs
Solution Approach 1:
The patent applies local quality by creating a gradient structure where phosphor concentration varies spatially. The resin layer has higher phosphor concentration near the ultraviolet LED chip and lower concentration toward the emission surface, which compensates for the non-uniform light distribution and achieves uniform white light emission.
Solution Approach 2:
The patent changes the concentration parameter of phosphors within the resin layer to optimize light uniformity. By adjusting phosphor concentration distribution and resin composition, the patent achieves both white light emission and uniformity without requiring additional optical components.
2Adaptability or versatility
If phosphors with different emission colors are used, then color reproduction is improved, but color difference between emission chromaticity and projected light increases
Solution Approach 1:
The patent uses local quality by positioning different phosphor types (yellow, orange, red) at different depths within the resin layer. This spatial arrangement allows each phosphor to contribute optimally to the overall color output, achieving accurate color reproduction while maintaining chromaticity uniformity in the emitted white light.
Solution Approach 2:
The patent employs composite materials by combining multiple phosphor types (Y3Al5O12:Ce, CaAlSiN3:Eu, Sr2Si5N8:Eu) with a transparent resin matrix. This composite structure enables broad spectrum coverage for accurate color reproduction while the resin matrix ensures uniform light transmission and chromaticity consistency.
3Illumination intensity
If blue emitting LED chip and yellow phosphor are combined, then brightness is improved, but emitted light appears yellowish and unevenness occurs
Solution Approach 1:
The patent extracts the yellowish appearance problem by introducing additional phosphors (orange and red emitting phosphors) that compensate for the excessive yellow component. This multi-phosphor approach extracts the harmful yellow bias while maintaining the brightness advantage of the blue LED chip.
Solution Approach 2:
The patent uses composite materials by combining yellow, orange, and red phosphors in a transparent resin matrix. This composite phosphor system balances the spectral output to eliminate yellowish appearance while preserving high brightness, producing true white light emission.
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 achieves improved light uniformity and quality by minimizing color differences, enhancing reproducibility and brightness, and maintaining emission efficiency and chromaticity stability over time, making it suitable for use in lighting devices and liquid crystal displays.
Implementation Method 1
a light emitting part including a plurality of phosphors different in emission color and emitting visible light when excited by light from the light source
Data Source
AI summary
A light emitting device 1 has, as a light source, a light emitting semiconductor element such as a light emitting diode 2. Light radiated from the light emitting diode 2 is converted to visible light in a light emitting part 8 having a plurality of phosphors 9 different in emission color, and the visible light is emitted. In such a light emitting device 1, a maximum value (Δx, Δy) of color difference (absolute value) between emission chromaticity (x, y) and emission chromaticity (x1, y1) satisfies conditions of Δx<0.05 and Δy<0.05, where (x, y) is emission chromaticity measured directly above the light source and (x1, y1) is emission chromaticity measured for each of front lights and side leakage lights in all directions from the light emitting device 1.