Stereolithography Wavelength Conversion for LED Uniformity
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Solution Overview
Problem
Conventional broad spectrum light emitting semiconductor devices face variations in emitted light wavelength and intensity due to manufacturing tolerances and defects, leading to uneven color emission and inconsistent white light production.
Innovation Solution
The solution involves forming a wavelength conversion structure on light emitting elements using stereolithography, where the amount and shape of luminescent material are tailored based on measured light output, allowing for custom-designed phosphor layers with varying compositions, thicknesses, and shapes to ensure uniform light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional coating methods are used to apply luminescent material, then the fabrication process is simple, but the color emission is uneven and manufacturing precision is poor
Solution Approach 1:
The patent measures the light output characteristics of each LED device before applying the luminescent material, and uses this measurement data to guide the selective formation process. This preliminary measurement and planning enables precise control over the final color emission uniformity across the wafer.
Solution Approach 2:
The patent applies luminescent material with locally optimized properties to different regions of the wafer based on measured LED variations. By forming wavelength conversion structures with spatially varying thicknesses, compositions, or patterns, each local region is tailored to compensate for its specific LED's characteristics, achieving uniform overall emission.
2Manufacturing precision
If uniform luminescent material is applied to all devices, then the fabrication process is simple, but variations in LED output cause inconsistent white light production
Solution Approach 1:
The patent varies multiple parameters of the wavelength conversion structure including thickness, luminescent material composition, concentration, and spatial distribution. These parameter changes are systematically adjusted based on measured LED characteristics to compensate for manufacturing variations and achieve consistent white light output across all devices.
Solution Approach 2:
The patent implements a feedback loop where LED light output is measured, and this measurement information is used to control the selective formation process. The system continuously monitors and adjusts the luminescent material application based on actual LED performance, ensuring consistent final output despite initial variations.
3Manufacturing precision
If stereolithography is used to selectively form wavelength conversion structures, then manufacturing precision and uniformity are improved, but device complexity and process time increase
Solution Approach 1:
The patent replaces conventional mechanical coating methods with stereolithography, an additive manufacturing technique that uses light to selectively cure photopolymer resin. This substitution enables precise digital control over structure formation, allowing complex 3D wavelength conversion structures to be built layer by layer with high accuracy based on measured LED data.
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
This approach ensures more consistent and uniform broad spectrum light output by customizing wavelength conversion structures to match individual light emitting elements' properties, improving color temperature and rendering index.
Implementation Method 1
exposing the liquid polymer to light for a time sufficient to at least partially cure the liquid polymer
Implementation Method 2
an amount of luminescent material on the light emitting element... wavelength conversion structure... that emits yellow light in response to stimulation with blue light
Data Source
AI summary
Methods of forming a light emitting device include selectively forming a wavelength conversion structure on a light emitting element using stereolithography. Selectively forming the wavelength conversion structure may include covering the light emitting element with a photo-curable liquid polymer containing a luminescent material, and exposing the liquid polymer to light for a time sufficient to at least partially cure the liquid polymer. Multiple layers of polymer can be selectively built up to form a wavelength conversion structure having a custom shape on the light emitting element.