Stacked LED Structure for AC Power Operation
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Solution Overview
Problem
Conventional Light Emitting Diodes (LEDs) face difficulties in continuously emitting light when connected to AC power due to rectification characteristics, leading to damage from reverse current, necessitating the development of a solution that allows LEDs to function efficiently with AC power without requiring separate rectification circuits.
Innovation Solution
A light emitting device with a specific semiconductor structure that includes a support member, buffer layers, and electrodes configured to enable efficient light emission under both forward and reverse biases, eliminating the need for a separate rectifier circuit and enhancing thermal stability and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LED is connected to AC power source, then power supply flexibility is improved, but LED suffers damage from reverse current and cannot continuously emit light
Solution Approach 1:
The LED structure is segmented into multiple independent light emitting units (first and second light emitting units) with different polarities. Each unit has its own light emitting layer and electrode structure, allowing them to operate independently under different bias conditions. This segmentation enables the overall device to function continuously on AC power by switching between units.
Solution Approach 2:
The patent inverts the conventional single-polarity LED structure by creating a dual-polarity device where the first light emitting unit has a first polarity and the second light emitting unit has a second polarity opposite to the first. This inversion allows each unit to emit light during opposite half-cycles of AC power, eliminating the reverse current damage problem.
2Ease of manufacture
If conventional LED structure is used, then manufacturing simplicity is maintained, but light emission efficiency and thermal management are insufficient
Solution Approach 1:
The patent merges multiple light emitting units into a single integrated device structure shared on a common substrate. The first and second light emitting units share common electrodes and substrate infrastructure, reducing overall device complexity and manufacturing steps while achieving high light emission efficiency through multiple active regions.
Solution Approach 2:
The patent transitions from a planar single-layer LED structure to a three-dimensional stacked configuration where light emitting units are arranged in vertical layers. This dimensional change increases the effective light emitting area and improves thermal dissipation pathways without significantly increasing the device footprint.
3Device complexity
If single light emitting unit is used, then device complexity is reduced, but continuous light emission under AC power is not achieved
Solution Approach 1:
The patent implements periodic action by designing the dual-polarity structure to alternate between the first and second light emitting units during different half-cycles of AC power input. This periodic switching ensures continuous light emission as one unit operates while the other is in reverse bias, and vice versa, achieving uninterrupted illumination.
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 device achieves enhanced light emission efficiency, reduced risk of damage from Electro Static Discharge (ESD), and improved thermal management, allowing for efficient operation with AC power while maintaining reliability and efficiency.
Implementation Method 1
Light Emitting Diodes (LEDs) are a representative example of light emitting devices, which convert electric signals into infrared light or visible light using characteristics of compound semiconductors
Implementation Method 2
improved thermal management
Data Source
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AI summary
A light emitting device (100) is disclosed. The light emitting device (100) comprises a first section (120) and a second section (130), wherein the first section (120) comprises a first semiconductor layer (122) doped with a first dopant, a second semiconductor layer (126) doped with a second dopant, and a first active layer (124) between the first and second semiconductor layers (122, 126), and wherein the second section (130) comprises a third semiconductor layer (132) disposed on the first section (120), and the third semiconductor layer (132) having an exposed region, a fourth semiconductor layer (136) disposed on the third semiconductor layer (132) except for the exposed region, and a second active layer (134) between the third and fourth semiconductor layers (132, 136), a first electrode (142) disposed on the first semiconductor layer (122), a second electrode (144) disposed on the fourth semiconductor layer (136) and a third electrode (146) inserted into a hole in the exposed region so as to be disposed on the exposed region and the second semiconductor layer (126), the third electrode (146) electrically connected to the second and third semiconductor layers (126, 132).