Selective Photocurable Coating for LED Phosphor Uniformity
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Solution Overview
Problem
Conventional methods for coating light emitting devices, such as LEDs, face challenges in achieving uniform and efficient phosphor coating, particularly for white LEDs and edge LEDs, with limitations in precision and productivity.
Innovation Solution
A method utilizing a microfluidic technique to coat light emitting devices with photocurable liquids, allowing for selective exposure of light to form multiple layers of phosphor coatings on the devices, enabling uniform and precise application of phosphors, including on lateral surfaces, and facilitating the fabrication of light couplers with integrated lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional direct coating method is used, then coating process is simple, but coating uniformity is poor
Solution Approach 1:
The patent segments the coating process into multiple sequential steps: applying a transparent resin layer, forming a phosphor paste layer, and applying additional resin layers. This segmentation allows each layer to be optimized independently, achieving uniform phosphor distribution and consistent coating thickness while maintaining a manageable process structure.
Solution Approach 2:
The patent applies a transparent resin layer before applying the phosphor paste layer. This preliminary action creates a base layer that ensures uniform phosphor distribution and prevents phosphor aggregation, thereby improving coating uniformity without significantly complicating the overall process.
2Productivity
If individual LED coating is performed, then each LED can be coated separately, but productivity is low
Solution Approach 1:
The patent merges multiple LED coating operations into a single batch process where multiple LEDs are coated simultaneously using the same multi-layer coating method. This combining approach maintains coating consistency across all LEDs while significantly improving productivity through parallel processing.
3Reliability
If single layer phosphor coating is applied, then fabrication process is simple, but white LED performance is insufficient
Solution Approach 1:
The patent uses composite material structure with multiple phosphor layers containing different phosphor types and compositions. The first phosphor paste layer and second phosphor paste layer use different phosphor formulations to achieve complementary color rendering, improving white LED performance while organizing the complexity into a structured multi-layer composite system.
Solution Approach 2:
The patent applies different phosphor compositions and concentrations in different layers. The first phosphor paste layer contains specific phosphors optimized for certain wavelength conversions, while the second layer contains different phosphors for other wavelength ranges. This local quality differentiation achieves superior overall white LED performance through targeted phosphor distribution.
4Reliability
If lateral surface coating is not performed, then coating process is simple, but edge LED performance is reduced
Solution Approach 1:
The patent applies the same multi-layer coating methodology to both the upper surface and lateral surfaces of the edge LED. This universal application of the coating process ensures consistent phosphor distribution and optimal light conversion across all LED emission surfaces, improving edge LED performance without requiring fundamentally different coating techniques.
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 method allows for economic and precise coating of phosphors on light emitting devices, enabling the production of white LEDs and improving productivity through batch processing, while ensuring uniformity and control over the thickness and pattern of the coating layers.
Implementation Method 1
a plurality of light emitting devices are coated with a first photocurable liquid. first light is selectively exposed to the first photocurable liquid to form a first coating layer
Implementation Method 2
The plurality of light emitting devices are dipped in a plurality of photocurable liquids using a microfluidic channel through which the plurality of photocurable liquids flow
Data Source
AI summary
A method of coating a light emitting device is provided. The method includes preparing a plurality of light emitting devices. The plurality of light emitting devices are coated with a first photocurable liquid. First light is selectively exposed to the first photocurable liquid to form a first coating layer on at least a partial region of a surface of each of the plurality of light emitting devices. The plurality of light emitting devices on which the first coating layer is formed are coated with a second photocurable liquid. Second light is selectively exposed to the second photocurable liquid to form a second coating layer on at least a partial region of the surface of each of the plurality of light emitting devices or a surface of the first coating layer. The first coating layer corresponds to the cured first photocurable liquid, while the second coating layer corresponds to the cured second photocurable liquid.