LED Module Asymmetric Circuit Thermal Load Distribution

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Solution Overview

Problem

LED modules with LEDs arranged in a regular grid on flat carrier boards experience uneven thermal load distribution, with more effective heat dissipation at edge areas, leading to increased cooling demands for central LEDs, which is inefficient and requires additional cooling measures.

Innovation Solution

The LEDs are connected in parallel circuits with a higher number of series circuits at the edge areas and fewer in the central area, allowing for a heavier current load and thus more heat generation at the edges, balancing thermal load across the board without additional cooling measures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If LEDs are arranged equidistantly on a circuit board in a regular grid, then the arrangement is simple and manufacturing is easy, but the thermal load is unevenly distributed with edge areas dissipating heat more effectively than central areas

Engineering Contradiction:
ImproveLED arrangement simplicityVSAvoidthermal load distribution
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The patent applies asymmetry by creating unequal series circuits in different spatial regions of the LED array. Specifically, edge regions contain series circuits with fewer LEDs (allowing higher current and heat generation) while central regions contain series circuits with more LEDs (allowing lower current and heat generation). This asymmetric current distribution compensates for the asymmetric heat dissipation characteristics of the board, achieving uniform thermal load across the entire LED array while maintaining the simple regular grid physical arrangement.

Inventive Principle:
Principle #4Asymmetry

2Temperature

If more cooling measures are implemented in central areas to compensate for poor heat dissipation, then thermal load on central LEDs is reduced, but device complexity and cooling costs increase

Engineering Contradiction:
Improvecentral LED thermal loadVSAvoidcooling system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent changes the electrical parameters (current load and series circuit configuration) rather than thermal parameters (cooling system design). By adjusting the number of LEDs in series circuits across different regions, the patent modifies the heat generation parameters to match the heat dissipation capabilities of each region. This allows standard uniform cooling measures to be used throughout the device while achieving appropriate thermal management, avoiding the need for complex region-specific cooling systems.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If parallel circuits are designed with equal number of LEDs in each series connection, then circuit design is simple and uniform, but thermal imbalance requires heavier cooling in central areas

Engineering Contradiction:
Improvecircuit design simplicityVSAvoidthermal load balance
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The patent applies local quality by making different spatial regions have different electrical characteristics. Edge regions are designed with series circuits containing fewer LEDs (e.g., 2-3 LEDs per series circuit) to generate more heat locally where dissipation is efficient, while central regions are designed with series circuits containing more LEDs (e.g., 4-5 LEDs per series circuit) to generate less heat where dissipation is poor. This local differentiation in circuit design achieves uniform thermal distribution across the entire array.

Inventive Principle:
Principle #3Local quality

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 design achieves a more uniform thermal load distribution, reducing the need for enhanced cooling in central areas and enhancing luminous flux homogeneity, potentially extending LED service life and reducing cooling costs.

Implementation Method 1

an arrangement of electronically connected LEDs (3) in parallel circuits (6) of series circuits (6) of the LEDs

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

the LEDs generate a not inconsiderable amount of heat during operation

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2965358B1LED module and lighting assembly having a corresponding module
Publication Date: 2018.05.09 ZUMTOBEL LIGHTING GMBH
  • EP2965358B1 patent drawingFigure 1~2
  • EP2965358B1 patent drawingFigure 3~4

AI summary

The invention relates to an LED module (1) having an arrangement of electronically connected LEDs (3) and a carrier (2) for the LEDs (3), wherein a parallel connection of series circuits (6) of LEDs (3) is present. The parallel connection is selected in such a manner that the thermal load on the carrier (2) caused by the operation of the LEDs (3) is distributed substantially evenly across the carrier (2).