Fluorescent Layer Coating for LED Uniformity
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Solution Overview
Problem
Conventional light-emitting devices face issues with light output deterioration due to fluorescent substance sedimentation, irregular coloration, and non-uniform optical characteristics, primarily caused by the high specific gravity of fluorescent substances and difficulties in achieving uniform dispersion and large particle diameter coatings.
Innovation Solution
A method involving a fluorescent layer with a particle diameter of 20 to 45 μm and a concentration of 40 to 60 wt % dispersed in a light-transmitting member, applied to a light-emitting device, where the layer is thermally cured to a thickness of 80 to 240 μm, preventing sedimentation and enhancing light conversion efficiency and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorescent substance of large particle diameter is used, then light conversion efficiency is improved, but the fluorescent substance becomes more liable to sediment
Solution Approach 1:
The patent specifies precise parameter ranges for particle diameter (20-45 μm) and concentration (40-60 wt%) to optimize both light conversion efficiency and dispersion stability. This parameter optimization resolves the contradiction by finding the optimal balance point where large particles provide good efficiency while maintaining sufficient stability.
Solution Approach 2:
The patent employs preliminary dispersing treatments and specific processing steps before final curing to ensure uniform distribution of fluorescent particles. This preliminary action prevents sedimentation issues that would otherwise occur with large particle diameter materials.
2Stability of the object's composition
If a fluorescent substance of small particle diameter is used, then sedimentation is inhibited, but light extraction efficiency and light absorption efficiency deteriorate
Solution Approach 1:
The patent establishes a minimum particle diameter threshold (20 μm) to ensure sufficient light extraction efficiency while accepting the need for enhanced dispersing measures. This parameter setting resolves the contradiction by defining the smallest acceptable particle size that maintains efficiency.
Solution Approach 2:
The patent implements preliminary dispersing treatments and viscosity control measures to prevent sedimentation of smaller particles. These preliminary actions enable the use of smaller particles (20-45 μm range) without suffering from sedimentation problems.
3Reliability
If a high concentration of fluorescent substance is used, then light conversion efficiency is improved, but the viscosity of the raw material increases making coating difficult
Solution Approach 1:
The patent optimizes the concentration parameter to a specific range (40-60 wt%) that provides sufficient light conversion efficiency while maintaining manageable viscosity. This parameter optimization resolves the contradiction by finding the highest acceptable concentration that remains processable.
Solution Approach 2:
The patent employs viscosity control measures and temperature management during the coating process to maintain processability at high concentrations. These dynamic adjustments enable coating of high-concentration materials without excessive viscosity problems.
4Ease of manufacture
If a low concentration of fluorescent substance is used, then the viscosity of the raw material is reduced improving coating ease, but light conversion efficiency deteriorates
Solution Approach 1:
The patent establishes a minimum concentration threshold (40 wt%) that ensures sufficient light conversion efficiency while accepting the need for viscosity management. This parameter setting resolves the contradiction by defining the lowest acceptable concentration that maintains efficiency.
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 method results in improved light extraction efficiency, uniform light emission, and prevention of irregular coloration, enhancing the optical output and manufacturing yield of light-emitting devices.
Implementation Method 1
a wavelength conversion member placed in the cup so as to cover the light-emitting element, the wavelength conversion member comprising a light-transmitting material containing a fluorescent substance (phosphor)
Implementation Method 2
the material thus placed in the recess being subsequently thermally cured
Data Source
AI summary
A method of manufacturing a light-emitting device includes disposing a light-emitting element on a supporting member, dispersing a fluorescent substance having a particle diameter of 20 to 45 μm in a material of the light-transmitting member at a concentration of 40 to 60 wt %, dripping raw material for the fluorescent layer on the light-emitting element while lowering the viscosity of the raw material, and thermally curing the coated layer.