LED Junction Temperature Control via Periodic Current Interruption
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Solution Overview
Problem
Solid state lighting systems face challenges in maintaining optimal junction temperatures, leading to reduced lifetime and color shifts, especially in varied applications and environmental conditions, as current thermal management solutions are inadequate and often require specific fixtures or environments.
Innovation Solution
A solid state lighting apparatus that includes a control circuit configured to temporarily interrupt electrical current to LEDs, creating a flashing light pattern detectable by the human eye when operating conditions exceed a threshold, thereby reducing junction temperatures and providing a visible indicator of detrimental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If continuous electrical current is provided to LEDs for general illumination, then light output is maintained, but junction temperature increases reducing LED lifetime and causing color shifts
Solution Approach 1:
The control circuit temporarily interrupts electrical current to the LED array at repeating intervals, creating a periodic on-off action. This allows the LED junction temperature to decrease during off-intervals while maintaining illumination during on-intervals, resolving the contradiction between continuous light output and temperature control
2Temperature
If thermal management systems are designed for specific fixtures and environments, then junction temperature control is improved, but device complexity and adaptability are reduced
Solution Approach 1:
The LED array itself provides thermal management by generating visible alert signals when junction temperature exceeds thresholds. The system self-regulates without requiring external thermal management infrastructure, enabling adaptability to any fixture or environment while maintaining temperature control
3Productivity
If junction temperature is allowed to exceed recommended levels, then productivity and light output are maintained, but LED lifetime is reduced
Solution Approach 1:
The control circuit continuously monitors junction temperature and provides feedback by generating visible alert signals when thresholds are exceeded. This feedback mechanism allows the system to maintain productivity during normal operation while preventing excessive temperature accumulation that would reduce LED lifetime
Data Source
Figure 1~2A
Figure 2B~3B
Figure 4
AI summary
A solid state lighting apparatus includes a plurality of light emitting diodes, a sensor configured to output a sensor signal indicative of at least one operating condition of the solid state lighting apparatus, and a control circuit coupled to the sensor. The control circuit is configured to temporarily interrupt electrical current to ones of the plurality of light emitting diodes at respective intervals responsive to the sensor signal indicating that the operating condition does not meet a desired operating threshold to provide a visible indicator thereof in light emitted by the apparatus. Related devices and methods of operation are also discussed.