LED Package Light-Scattering Structure for Uniform Dispersion
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Solution Overview
Problem
Liquid crystal display (LCD) devices using cold cathode fluorescent lamps (CCFLs) face issues with non-uniform luminance and deteriorated color purity, especially on larger screens, and semiconductor nanocrystals in LED backlight units have low thermal stability, leading to reliability concerns.
Innovation Solution
An LED package with a light-scattering structure and a light conversion layer including semiconductor nanocrystals, separated from the LED light source by a distance, to achieve uniform light dispersion and improved color reproducibility, using materials like polymethyl(meth)acrylate and a polymer matrix with a glass transition temperature above 85°C, and an organic or inorganic barrier layer for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If semiconductor nanocrystals are used in LED backlight units for improved color purity, then color reproducibility is enhanced, but thermal stability deteriorates leading to reliability concerns
Solution Approach 1:
A light-scattering structure is introduced as an intermediary component positioned between the LED light source and the light conversion layer containing semiconductor nanocrystals. This structure scatters the emitted light to uniformly distribute thermal energy, preventing localized overheating that would otherwise degrade the nanocrystals and compromise reliability while maintaining color reproduction quality.
Solution Approach 2:
The light-scattering structure creates local variations in light distribution and thermal exposure across different regions of the light conversion layer. By controlling the spatial distribution of scattered light, the structure ensures that semiconductor nanocrystals in different positions experience optimized thermal conditions, preventing hot spots that would lead to degradation while maintaining overall color purity.
2Power
If LED light source is placed close to light conversion layer for efficient light conversion, then luminance efficiency is improved, but uniform light dispersion deteriorates
Solution Approach 1:
The light-scattering structure serves as a mediating element positioned between the LED light source and the light conversion layer. It receives concentrated light from the LED, scatters it in multiple directions, and then allows the scattered light to reach the light conversion layer. This intermediary action maintains close proximity for efficient energy transfer while achieving uniform light dispersion across the conversion layer.
Solution Approach 2:
The light-scattering structure transforms the one-dimensional concentrated light path from the LED into multi-directional scattered light distribution. By introducing spatial dimensionality through scattering, the structure converts concentrated light energy into uniformly distributed illumination across the light conversion layer, maintaining efficiency while achieving uniformity.
3Illumination intensity
If light-scattering structure is placed close to LED light source for effective light scattering, then uniform light dispersion is improved, but heat exposure to semiconductor nanocrystals increases
Solution Approach 1:
The light-scattering structure is positioned at an optimized distance from the LED light source to create local quality variations in light scattering. By controlling the proximity and scattering characteristics, the structure achieves uniform light dispersion in the light conversion layer while allowing sufficient thermal distance to reduce heat exposure to the semiconductor nanocrystals, preventing thermal degradation.
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 provides uniform light dispersion, enhanced color purity, and high reliability by preventing semiconductor nanocrystal degradation, maintaining luminance and color stability over time even under high temperature conditions.
Implementation Method 1
a light-scattering structure, spaced apart from the LED light source, and a light conversion layer, disposed on an outer surface of the light-scattering structure
Implementation Method 2
a light conversion layer... configured to convert light emitted from the LED into white light
Implementation Method 3
an organic barrier layer... disposed on a surface of the light conversion layer
Data Source
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AI summary
A light emitting diode (LED) package includes: an LED; a stack structure including a light-scattering structure spaced apart from the LED, and a light conversion layer disposed on at least one surface selected from an inner surface and an outer surface of the light-scattering structure and configured to convert light emitted from the LED into white light, wherein the light conversion layer includes a semiconductor nanocrystal; and an organic barrier layer disposed on a surface of the light conversion layer.