Parallel Electrode Structure for Uniform Current Distribution in LED Arrays

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Solution Overview

Problem

High current application in large area light emitting devices leads to a current bottleneck phenomenon, causing non-uniform emission strength and degradation of the Epi layer, especially under high temperature conditions.

Innovation Solution

A parallel type electrode structure is implemented, where the pad electrode is positioned over a first insulating layer and the first electrodes are distributed over the light emitting surface in a grid pattern, allowing current to flow in parallel and ensuring uniform current density across the emitting surfaces, thereby preventing the current bottleneck and enhancing heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If high current is applied to large area light emitting devices, then the light output increases, but current bottleneck phenomenon occurs causing non-uniform emission strength and degradation of the Epi layer

Engineering Contradiction:
Improvelight outputVSAvoidEpi layer degradation
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent divides the light emitting device into multiple separate light emitting elements arranged in an array, with each element having its own current path through trenches filled with insulating material. This segmentation prevents current bottleneck by distributing current flow across multiple independent elements, thereby maintaining reliability while achieving high total light output.

Inventive Principle:
Principle #1Segmentation

2Power

If high current is applied to large area light emitting devices, then the light output increases, but non-uniform emission strength occurs

Engineering Contradiction:
Improvelight outputVSAvoidemission uniformity
Core Design Contradiction:
PowerVSManufacturing precision

Solution Approach 1:

By segmenting the device into multiple independent light emitting elements with separate current paths, the patent ensures uniform current distribution across all elements. This prevents current bottleneck and achieves uniform emission strength while maintaining high total light output.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If monolithic arrays of light emitting elements are formed on a common electrode layer, then device integration is achieved, but current bottleneck phenomenon occurs

Engineering Contradiction:
Improvedevice integrationVSAvoidcurrent bottleneck
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent uses trenches extending through the light emitting layers to separate adjacent light emitting elements electrically, while all elements share a common second electrode layer. This segmentation approach maintains device integration through the common electrode while preventing current bottleneck by creating independent current paths for each element.

Inventive Principle:
Principle #1Segmentation

4Reliability

If trenches are used to separate adjacent light emitting elements, then current distribution is improved, but device structure becomes more complex

Engineering Contradiction:
Improvecurrent distributionVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements trenches filled with insulating material to separate adjacent light emitting elements, creating independent current paths that improve current distribution and prevent bottleneck. The segmented structure achieves reliable current distribution while maintaining manageable device complexity through systematic arrangement.

Inventive Principle:
Principle #1Segmentation

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 parallel electrode structure achieves uniform emission strength and improved high-temperature reliability by ensuring smooth current spreading and effective heat dissipation, addressing the current bottleneck issue and enhancing the performance of large area light emitting devices.

Implementation Method 1

allowing current to flow in parallel and ensuring uniform current density across the emitting surfaces

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

A light emitting device is a semiconductor device that converts current into light

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2221873B1Light emitting device
Publication Date: 2020.04.08 LG INNOTEK CO LTD
  • EP2221873B1 patent drawingFigure 1~2
  • EP2221873B1 patent drawingFigure 3A~3B
  • EP2221873B1 patent drawingFigure 4

AI summary

A light emitting device is provided. The light emitting device may include a plurality of light emitting elements formed on a first common electrode (142), each light emitting element having a first conductive layer (130) formed over the first common electrode. The light emitting device may also include an active layer (120) formed over the first conductive layer (130), a second conductive layer (110) formed over the active layer, and an insulator (150) formed between adjacent light emitting elements. A plurality of electrodes (160) may be respectively formed on the plurality of light emitting elements, and a second common electrode (170) may couple the plurality of electrodes. Such a light emitting structure may improve emission characteristics, heat dissipation and high temperature reliability.