Polygonal LED Shape for Light Extraction Efficiency
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Solution Overview
Problem
Conventional light emitting devices face inefficiencies in light output and uniformity, with a significant portion of emitted light being internally reflected rather than escaping, due to the geometry of their surfaces, leading to reduced reliability and market competitiveness.
Innovation Solution
The design of light emitting elements with polygonal or polyhedral shapes, featuring multiple planar surfaces and escape zones, increases the likelihood of light escape by reducing the incidence of total internal reflection, while also providing more uniform current injection and reduced mechanical stress compared to rectangular surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional rectangular light emitting devices are used, then manufacturing is simple, but light extraction efficiency is low due to total internal reflection
Solution Approach 1:
The patent applies asymmetry by changing the light emitting device shape from a conventional rectangular form to a polygonal form with non-orthogonal sides. This asymmetric geometry creates varied surface orientations that reduce total internal reflection and improve light extraction efficiency while maintaining manufacturing feasibility through standard semiconductor fabrication processes
Solution Approach 2:
The patent introduces dimensional change by transitioning from a two-dimensional rectangular planar surface to a multi-dimensional polygonal structure with multiple facets and angles. This dimensional complexity creates additional light escape pathways and reduces internal reflection, thereby improving light extraction efficiency without compromising manufacturing simplicity
2Device complexity
If rectangular light emitting surfaces are used, then device structure is simple, but light output uniformity is poor
Solution Approach 1:
The asymmetric polygonal geometry with non-orthogonal sides creates more uniform current distribution across the active region, leading to improved light output uniformity. The varied angles and orientations of the polygonal facets help distribute electrical fields and current flow more evenly compared to rectangular structures
Solution Approach 2:
The patent applies local quality by creating different surface orientations and angles at different regions of the light emitting device. Each polygonal facet has specific local geometric properties that optimize light extraction in particular directions, collectively achieving uniform overall light output
3Ease of manufacture
If rectangular light emitting elements are used, then mechanical stress is concentrated, but manufacturing is easier
Solution Approach 1:
The asymmetric polygonal shape with non-orthogonal sides distributes mechanical stress more uniformly across the device structure. The varied angles and geometries prevent stress concentration at specific corners or edges, improving device reliability and reducing the risk of mechanical failure during operation and handling
Solution Approach 2:
While not fully spherical, the polygonal design with multiple angled facets approximates a more rounded, stress-distributing geometry compared to sharp rectangular corners. This curved-like distribution of angles helps reduce stress concentration points, improving mechanical reliability
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 enhances light extraction efficiency, improves light output uniformity, and increases the reliability of light emitting devices by optimizing the escape zones and current distribution, allowing for more efficient light emission and reduced material waste during manufacturing.
Implementation Method 1
Light traveling outside the escape zone is totally internally reflected (TIR) at the surface. By increasing the number of surfaces on the light emitting element, the number of escape zones may be increased, with a corresponding increase in the likelihood of light escaping the surface.
Data Source
Figure 1A~3B
Figure 4A~6D
Figure 7A~8B
AI summary
The shape of a light emitting element (400;500) is designed to increase the amount of light that is able to escape from the surfaces of the light emitting element (400;500). The indices of refraction of the light emitting element (400;500) and the surrounding environment define an escape zone through which light may escape through a surface of the light emitting element (400;500). Light traveling outside the escape zone is totally internally reflected (TIR) at the surface. By increasing the number of surfaces on the light emitting element (400;500), the number of escape zones (410a- f,411a-f;510a-h,511a-h) may be increased, with a corresponding increase in the likelihood of light escaping the surfaces. A light emitting element (400;500) comprising a polygonal surface area with more than four sides (402a-f;502a-h) exhibits a higher light extraction efficiency, and also allows a more uniform current injection, and experiences reduced mechanical stress, compared to one comprising a rectangular surface area.