LED with Concave-Convex Substrate for AC Drive
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) with multiple units have relatively low luminous efficacy due to optical losses, particularly when driven by high voltage AC sources, and existing techniques for improving light extraction efficiency, such as patterned sapphire substrates, have limitations.
Innovation Solution
A light emitting diode design featuring a substrate with a concave-convex pattern, including parallelogram-shaped and triangular light emitting units, and an insulation layer over interconnection wires, which reduces optical loss by optimizing the shape and arrangement of light emitting units and interconnection wires to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a plurality of light emitting units are connected in series to enable high voltage AC operation, then the LED can be driven by AC sources, but light extraction efficiency deteriorates due to optical losses from interconnection wires and components
Solution Approach 1:
The patent positions interconnection wires in the vertical dimension by embedding them within recesses of the convex-concave pattern, removing them from the horizontal light propagation path. This dimensional relocation eliminates wire blockage of light while maintaining electrical connectivity between series-connected LED units.
Solution Approach 2:
The convex-concave pattern acts as an intermediary structure that simultaneously provides mechanical support, electrical isolation, and optical management. The pattern's geometry mediates between the conflicting requirements of wire placement and light extraction, allowing wires to be positioned in concave regions while convex regions maintain optimal light extraction pathways.
2Reliability
If interconnection wires are placed to connect light emitting units, then electrical connectivity is achieved, but light extraction efficiency deteriorates due to wire blockage
Solution Approach 1:
The substrate surface is segmented into convex regions and concave regions. Convex regions are dedicated to light emission and extraction, while concave regions are dedicated to wire placement. This spatial segmentation separates the optical and electrical functions, allowing each to optimize its performance without compromising the other.
Solution Approach 2:
Interconnection wires are relocated from the horizontal plane to vertical recesses within the convex-concave pattern. This dimensional change removes wires from the light extraction path while maintaining electrical connectivity, effectively resolving the conflict between wire placement and light extraction efficiency.
3Ease of manufacture
If conventional flat substrate structure is used, then manufacturing is simple, but light extraction efficiency is limited
Solution Approach 1:
The substrate employs a convex-concave pattern with curved surfaces instead of a flat plane. The convex regions with their curved geometries enhance light extraction through increased light-matter interaction and reduced total internal reflection, while the overall pattern can be fabricated using standard semiconductor processing techniques.
Solution Approach 2:
The substrate surface morphology is changed from flat to convex-concave pattern, modifying the physical parameters of light extraction. This geometric parameter change increases the extraction efficiency by altering light propagation paths and reducing reflective losses, while remaining compatible with existing manufacturing processes.
Data Source
AI summary
A light emitting diode includes a substrate including a concave-convex pattern having concave portions and convex portions, a first light emitting unit disposed on the substrate, a second light emitting unit disposed on the substrate, a first wire connecting the first light emitting unit to the second light emitting unit over the concave-convex pattern, and an insulation layer disposed between the concave-convex pattern and the wire. The insulation layer has a shape corresponding to the concave-convex pattern.