LED Junction Temperature Measurement via Remote Sensor and Calculation

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Solution Overview

Problem

High operating temperatures in LEDs accelerate light output degradation, shortening their lifespan and reducing light output, necessitating effective temperature monitoring to ensure adequate heat dissipation.

Innovation Solution

A temperature measurement system for LEDs that includes a temperature sensor connected to a remote location from the LED junction, a temperature calculation module to determine the junction temperature based on measured temperatures, and optional components like thermal pads and signal conditioning modules for accurate temperature monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a temperature sensor is placed directly at the LED junction to measure junction temperature, then measurement precision is improved, but device complexity and difficulty of implementation increase due to the small size and high-temperature environment of the junction

Engineering Contradiction:
Improvejunction temperature measurementVSAvoidsensor placement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a thermal pad as an intermediary element between the LED junction and the temperature sensor. The thermal pad conducts heat from the junction to the sensor location, allowing temperature measurement without direct contact with the junction. This mediator enables accurate temperature monitoring while avoiding the complexities of placing a sensor directly in the high-temperature, small-scale junction environment

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transitions from attempting to measure temperature in the spatial dimension of the junction itself to measuring temperature at a different spatial location (the thermal pad or heat sink) that is thermally coupled to the junction. This dimensional shift in measurement location allows for practical sensor placement while maintaining measurement relevance through thermal conduction

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Duration of action of stationary object

If heat dissipation structures (heat sink, fan) are added to reduce operating temperature, then LED lifespan and light output are improved, but device complexity and cost increase

Engineering Contradiction:
ImproveLED lifespanVSAvoidheat dissipation system complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent employs a heat sink that utilizes passive thermal conduction and natural convection to dissipate heat from the LED junction. The heat sink structure itself serves the cooling function without requiring active control systems, making the LED assembly self-cooling. This approach extends LED lifespan through effective heat management while avoiding the added complexity of active cooling systems

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the thermal parameters of the LED assembly by introducing a heat sink with high thermal conductivity materials and optimized surface area. This parameter change (increasing heat dissipation capability) allows the system to operate at lower temperatures, extending LED lifespan without requiring complex active cooling mechanisms

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a temperature sensor and calculation module are used to monitor junction temperature remotely, then reliability of temperature monitoring is improved, but device complexity increases due to additional components

Engineering Contradiction:
Improvetemperature monitoring reliabilityVSAvoidtemperature measurement system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a temperature monitoring system that provides feedback about the LED junction temperature through a temperature sensor and calculation module. This feedback mechanism allows the system to monitor temperature conditions and potentially trigger protective actions or adjustments, improving reliability by enabling proactive temperature management while using relatively simple sensor and computation components

Inventive Principle:
Principle #23Feedback

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

Enables effective monitoring of LED junction temperatures, helping to prevent excessive heat buildup and thus prolonging the lifespan and maintaining light output by ensuring sufficient heat dissipation.

Implementation Method 1

a temperature sensor operatively connected to the LED assembly at a remote location that is remote from the LED junction. The temperature sensor is configured to measure a temperature of the LED assembly at the remote location

Methodology Applied
Scientific EffectThermal energy detection:

Implementation Method 2

The temperature calculation module is configured to determine a junction temperature at the LED junction based on the measured temperature at the remote location

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2392903B1Temperature measurement system for a light emitting diode (led) assembly
Publication Date: 2018.05.02 TE CONNECTIVITY CORP
  • EP2392903B1 patent drawingFigure 1~3
  • EP2392903B1 patent drawingFigure 4~5
  • EP2392903B1 patent drawingFigure 6~7

AI summary

A temperature measurement system (100) is provided for a light emitting diode (LED) assembly (10) that includes an LED (14) having two semiconductors joined together at an LED junction. The system (100) includes a temperature sensor (102) operatively connected to the LED assembly (10) at a remote location that is remote from the LED junction. The temperature sensor (102) is configured to measure a temperature of the LED assembly (10) at the remote location. A temperature calculation module (106) is operatively connected to the temperature sensor (102) for receiving the measured temperature at the remote location from the temperature sensor (102). The temperature calculation module (106) is configured to determine a junction temperature at the LED junction based on the measured temperature at the remote location.