CASN Fluorescent Powder Ruggedness for Micro LED Color Reproducibility
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Solution Overview
Problem
Current LED displays face challenges in achieving high color reproducibility due to insufficient light-emitting intensity of green and red fluorescent substances, particularly in micro LED displays where the color gamut is limited by the properties of the fluorescent substances used in the cured resin layer.
Innovation Solution
A fluorescent substance powder with CASN-based particles is developed, characterized by specific ruggedness, standard deviation, and aspect ratio, which enhances the filling properties and transmittance of exciting light, thereby increasing the chromaticity X of the cured resin layer, and is used in a light-emitting device to improve color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional CASN-based fluorescent substances are synthesized using traditional methods, then the synthesis process is simple, but the particle surface is smooth resulting in insufficient light-emitting intensity and limited color gamut
Solution Approach 1:
The patent applies parameter changes by controlling the oxygen partial pressure during synthesis (maintaining at 0.01 atm or lower) and adjusting the ratio of calcium nitride to silicon nitride (Ca3N2:Si3N4 = 1:4 to 1:10). These parameter changes result in particles with increased surface ruggedness (average ruggedness ≥ 0.981), which significantly enhances light-emitting intensity and enables achievement of large chromaticity X values (≥ 0.62) for expanded color gamut.
2Manufacturing precision
If the particle surface is smooth, then the synthesis is easier, but the filling property in the cured resin layer is insufficient leading to small chromaticity X
Solution Approach 1:
The patent changes the synthesis parameters by maintaining low oxygen partial pressure (0.01 atm or lower) and specific reactant ratios, which produces particles with high surface ruggedness (average ruggedness ≥ 0.981). This rugged surface structure improves the filling property in the cured resin layer, thereby achieving large chromaticity X values (≥ 0.62) and enhanced manufacturing precision for the fluorescent substance powder.
3Quantity of substance
If the particle size is increased to improve light absorption, then the filling property improves, but the aspect ratio increases reducing dispersion quality
Solution Approach 1:
The patent controls particle morphology through parameter changes during synthesis, specifically maintaining low oxygen partial pressure and appropriate reactant ratios. This produces particles with optimized dimensions (average equivalent circle diameter ≥ 1.5 μm) and controlled aspect ratio (≤ 1.275), achieving both improved filling property and uniform particle shape for stable dispersion in the cured resin layer.
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 fluorescent substance powder significantly enhances the chromaticity X of the cured resin layer, leading to improved color reproducibility in LED displays by optimizing the dispersion and absorption of light, thereby expanding the color gamut.
Implementation Method 1
a wavelength converter that absorbs primary light and emits secondary light having a wavelength longer than a wavelength of the primary light
Data Source
AI summary
According to an aspect of the present disclosure, there is provided a fluorescent substance powder containing a plurality of CASN-based fluorescent substance particles. Average ruggedness of fluorescent substance particles having a particle size of 1 μm or greater among the CASN-based fluorescent substance particles is 0.985 or greater.