LED Thermal Management via Selective Current Interruption

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Solution Overview

Problem

Current solid state lighting systems face challenges in maintaining stable junction temperatures, which can lead to reduced LED lifetime and color shifts in light output, particularly in applications where thermal management solutions are inadequate or unascertainable for third-party products.

Innovation Solution

A solid state lighting apparatus comprising multiple LEDs with a thermal sensor and control circuit that selectively interrupts electrical current to specific LEDs when a high temperature limit is exceeded, changing the visible light appearance and resuming current when the temperature drops below a restore function temperature, thereby managing thermal conditions and maintaining stable light output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If passive thermal management systems with exposed heat sinks are used, then heat dissipation efficiency is improved, but device complexity and integration flexibility deteriorate

Engineering Contradiction:
Improvejunction temperatureVSAvoidthermal management system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The control circuit automatically monitors temperature via the thermal sensor and selectively interrupts current to specific LEDs when temperature thresholds are exceeded, enabling the system to self-regulate thermal conditions without requiring complex external thermal management infrastructure

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system dynamically changes the operational parameters of the LED array by selectively de-activating specific LEDs based on real-time temperature readings, thereby adjusting the thermal load and light output to maintain safe operating temperatures

Inventive Principle:
Principle #35Parameter changes

2Temperature

If active thermal management systems with fans are used, then heat dissipation efficiency is improved, but device complexity and reliability deteriorate

Engineering Contradiction:
Improvejunction temperatureVSAvoidsystem reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The system uses an integrated control circuit that automatically responds to temperature conditions by selectively interrupting current to specific LEDs, eliminating the need for external active cooling components like fans that would reduce reliability

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent extracts the thermal management function from external active cooling systems and implements it within the LED control circuitry itself, removing vulnerable external components while maintaining effective temperature control

Inventive Principle:
Principle #2Taking out (Extraction)

3Adaptability or versatility

If thermal management solutions are integrated into third-party fixtures, then adaptability is improved, but manufacturing precision and thermal control effectiveness deteriorate

Engineering Contradiction:
Improvefixture compatibilityVSAvoidthermal sensor positioning precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The control circuit is designed to work with multiple LED configurations and fixture types, providing universal thermal management that adapts to different third-party fixtures without requiring precise thermal sensor positioning or custom integration

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system automatically adapts to different thermal conditions in various fixtures by using the thermal sensor to monitor actual operating temperatures and dynamically adjusting current distribution, eliminating the need for precision-engineered thermal pathways

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 effectively manages thermal conditions to extend LED lifetime and maintain stable color output by adjusting the light appearance in response to temperature changes, ensuring reliable performance even under conditions exceeding design standards.

Implementation Method 1

a thermal sensor that is configured to provide a temperature signal corresponding to an operating condition of the solid state lighting apparatus

Methodology Applied
Scientific EffectThermal sensing: Thermistor

Implementation Method 2

receiving electrical current into the apparatus to drive multiple light emitting diodes (LEDs)

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2486775B1Solid state lighting devices including thermal management and related methods
Publication Date: 2019.06.12 WOLFSPEED INC
  • EP2486775B1 patent drawingFigure 1~2A
  • EP2486775B1 patent drawingFigure 2B~3B
  • EP2486775B1 patent drawingFigure 4

AI summary

Provided is a solid state lighting apparatus that includes multiple light emitting diodes (LEDs) including at least a first LED and a second LED. The apparatus includes a thermal sensor that is configured to provide a temperature signal corresponding to an operating condition of the solid state lighting apparatus and a control circuit that is configured to receive the temperature signal and to selectively interrupt electrical current to a portion of the plurality of light emitting diodes responsive to the temperature signal including a value that exceeds a high temperature limit.