LED Voltage Monitoring for Junction Temperature Tracking

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Solution Overview

Problem

In UV curing applications using LED arrays, thermal management is inadequate, leading to potential catastrophic cooling system failures and significant degradation due to delayed temperature detection by thermal switches, which are often placed far from LEDs, causing lag in response and compromising module effectiveness.

Innovation Solution

Implementing a voltage monitoring system where a controller, connected to a voltage sensor, tracks the relationship between voltage and junction temperature of LEDs, allowing for faster and more accurate detection of overheating, enabling timely shutdown of the lighting module to prevent degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a thermal switch is placed near the LED to quickly detect temperature, then temperature detection speed improves, but the light module design flexibility deteriorates and the module may become ineffective

Engineering Contradiction:

Improvetemperature detection speedVSAvoidlight module design flexibility

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical thermal switch with an electrical voltage monitoring system. The controller monitors the voltage across the LED, which changes predictably with temperature, allowing temperature detection without physical proximity to the LED. This substitution of mechanical thermal detection with electrical measurement resolves the contradiction by enabling fast temperature monitoring while preserving design flexibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a thermal switch is placed far from the LED, then design flexibility improves, but temperature detection lag increases causing significant degradation

Engineering Contradiction:

Improvedesign flexibilityVSAvoidtemperature detection lag

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The voltage monitoring system replaces the mechanical thermal switch, eliminating the need for physical proximity to the LED. The controller can be positioned anywhere in the electrical circuit and still detect temperature changes through voltage measurements, thereby eliminating detection lag while maintaining design flexibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses voltage as an intermediary parameter to detect LED temperature. Instead of directly measuring temperature, the system monitors voltage changes that correlate with temperature, allowing remote temperature detection without time lag. This intermediary measurement approach resolves the contradiction between remote positioning and fast detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If voltage monitoring is implemented, then temperature detection speed improves, but device complexity increases

Engineering Contradiction:

Improvetemperature detection speedVSAvoidmonitoring system complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The controller performs multiple functions including power management, intensity control, and temperature monitoring. By integrating temperature detection into the existing controller's voltage sensing capability, the system achieves fast temperature monitoring without adding separate dedicated hardware components, thereby minimizing the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the existing voltage measurement infrastructure of the LED driver circuitry to detect temperature. The controller already measures voltage for other operational purposes, and this same voltage information is utilized for temperature monitoring, allowing the system to serve itself and avoid additional complexity.

Inventive Principle:

Principle #25Self-service

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 solution provides a faster and stronger signal for temperature monitoring compared to traditional thermal switches, effectively preventing LED module degradation and extending its useful lifetime by promptly interrupting power when high temperatures are detected.

Implementation Method 1

a relationship between a voltage across the LED and a junction temperature of the LED is determined

Methodology Applied

Scientific EffectVoltage-temperature relationship in LEDs:

Data Source

PatentUS8330377B2Monitoring voltage to track temperature in solid state light modules

Publication Date: 2012.12.11 SILICON VALLEY BANK

AI summary

An illumination system has a lighting module, a microcontroller electrically connected to the lighting module and arranged to control the lighting module, and a transistor electrically connected to the lighting module and the microcontroller arranged to allow the microcontroller to monitor a voltage of one of either the transistor or lighting module. A method of controlling a lighting module including powering on the lighting module, providing a current to the lighting module, wherein the current is determined by a global intensity setting for the lighting module, monitoring a voltage provided to the lighting module, and shutting the lighting module down if the voltage reaches a pre-determined level.