LED Photonic Crystal Structure for Narrow-Angle Light Extraction
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Solution Overview
Problem
Existing light-emitting diode (LED) elements face challenges in securing space for sensors due to their parallel arrangement, and they suffer from light loss due to Lambertian light emission distribution, which spreads light and deviates from the lens in headlamps.
Innovation Solution
A light-emitting diode element is designed with a substrate having a moth-eye nano pattern and a photonic crystal layer, which narrows the light emission distribution in angle, enhancing light extraction efficiency without increasing the lens aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If LED elements are arranged in parallel to increase output, then the light output increases, but the space required for installing sensors and other components decreases
Solution Approach 1:
The patent changes the light emission parameter by introducing a photonic crystal layer that modifies the emission angle. This allows a single LED element to achieve higher effective output in the desired direction without requiring parallel arrangement of multiple elements, thereby preserving space for sensors.
2Power
If the lens aperture ratio is increased to reduce light loss, then the amount of light taken in increases, but the space required for the headlamp increases
Solution Approach 1:
The patent changes the emission angle parameter of the LED itself through the photonic crystal layer, allowing the existing lens aperture to capture more light without increasing the lens size or headlamp space.
3Power
If the light emission distribution is narrowed in angle, then the light extraction efficiency increases, but the manufacturing complexity increases due to the need for photonic crystal structures
Solution Approach 1:
The patent segments the LED structure into distinct functional layers, with the photonic crystal layer separated from the active light-emitting layer. This segmentation allows the photonic crystal to be optimized for angle control while the active layer remains optimized for light generation, potentially simplifying the overall manufacturing process.
Solution Approach 2:
The patent introduces the photonic crystal layer as an intermediary between the active layer and the external environment. This intermediary structure controls the light emission angle without requiring direct modification of the active light-emitting materials, thereby reducing manufacturing complexity.
4Illumination intensity
If a photonic crystal layer is added to narrow light emission angle, then the light distribution characteristic improves, but the device complexity increases
Solution Approach 1:
The patent segments the device into functionally distinct layers: the active layer for light generation and the photonic crystal layer for angle control. This segmentation allows each layer to be independently optimized and manufactured, reducing overall device complexity despite the additional functional 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 proposed solution achieves a highly efficient light-emitting diode element with a significantly narrowed light distribution angle, leading to improved light extraction and increased output without the need for larger lenses or additional space for sensors.
Implementation Method 1
a first semiconductor layer formed on the moth-eye nano pattern and having a photonic crystal layer
Data Source
AI summary
A substrate has a moth-eye nano pattern on a surface of the substrate in which cone-shaped protrusions are periodically formed, a first semiconductor layer on the moth-eye nano pattern and having a photonic crystal layer, an active layer on the first semiconductor layer and having a light-emitting layer, and a second semiconductor layer on the active layer.