LED Street Light Thermal Protection via NTC Resistor
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Solution Overview
Problem
Existing street lamp heads designed for incandescent lamps fail to effectively manage the increased temperature of LED-based lamps, leading to reduced LED lifespan due to active electronic thermal protection devices that limit temperature to 85°C, resulting in decreased light output and shortened bulb life.
Innovation Solution
A thermally protected lighting system featuring an LED bulb with a negative temperature coefficient resistor (NTC) connected in parallel, regulated by a power management device with a central processing unit that adjusts current supply based on temperature measurements, allowing operation above 85°C and extending LED bulb life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If active electronic thermal protection devices are used to limit temperature to 85°C, then the temperature is controlled within safe limits, but the light output decreases and the device complexity increases
Solution Approach 1:
The patent introduces an NTC resistor as an intermediary sensing element that indirectly measures LED temperature through its resistance-temperature characteristic. This allows thermal monitoring without directly controlling temperature through active components in the LED compartment, thereby maintaining light output while providing thermal protection through the power management device that reads the NTC resistance value.
2Reliability
If active electronic thermal protection devices are integrated into the LED compartment, then temperature protection is provided, but the device complexity increases and ruggedized electronics are required
Solution Approach 1:
The patent extracts the active electronic thermal protection components from the LED compartment and relocates them to a separate power management device. Only a passive NTC resistor remains in the LED compartment for temperature sensing, while the complex processing and control functions are performed externally, reducing the electronic complexity and ruggedization requirements within the LED compartment.
3Duration of action of stationary object
If the housing is sealed to retain heat from incandescent lamps, then the lifespan of incandescent lamps is extended, but the temperature increase reduces LED lifespan
Solution Approach 1:
The patent changes the thermal management approach by transitioning from passive heat retention (sealed housing) to active thermal monitoring and adaptive control. The NTC resistor enables real-time temperature parameter monitoring, and the power management device adjusts operating parameters based on temperature feedback, allowing the sealed housing to maintain its protective function while preventing excessive temperature buildup that would harm LED lifespan.
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
The system effectively prolongs the lifespan of LED bulbs by automatically regulating current to prevent overheating, ensuring safe and consistent operation while maintaining high light output without the need for rugged electronics, and allowing temperatures above 85°C, thus enhancing safety and performance.
Implementation Method 1
a negative temperature coefficient (NTC) resistor mounted in parallel with the LED(s), the current supplied to the LED bulb being regulated according to the temperature of the LED(s) measured using the NTC resistor
Data Source
Figure 1~2
AI summary
The invention relates to a thermally protected lighting system (2), characterized in that it comprises a light-emitting diode (LED) bulb (3) comprising one or more LEDs (3a) mounted in series and a negative temperature coefficient (NTC) resistor (11) mounted in parallel with the LED(s) (3a), the thermally protected lighting system (2) further comprising a power management device (4) comprising a current regulator (16) and a central processing unit (17) configured to control the current regulator (16) so as to regulate the current supplied to the LED bulb (3) as a function of the temperature of the LED(s) (3a) measured by the central processing unit (17) using the NTC resistor (11).