LED Lamp Active Cooling Fan Reduces Convective Thermal Resistance
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Solution Overview
Problem
Solid state lamps using LEDs face challenges with heat dissipation, particularly due to high convective thermal resistance, which leads to elevated operating temperatures and reduced efficiency, especially in compact designs where natural convection is inadequate.
Innovation Solution
Incorporating active elements such as fans to agitate air and reduce convective thermal resistance, combined with heat sinks and diffuser structures that promote omnidirectional light emission and effective thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If compact LED lamp design is used, then space efficiency is improved, but convective thermal resistance increases leading to elevated operating temperatures
Solution Approach 1:
The patent introduces an active cooling fan that dynamically adjusts air flow through the heat sink to compensate for the reduced natural convection in compact designs. The fan speed can be modulated based on thermal conditions to maintain effective heat dissipation despite the smaller form factor limiting passive cooling capability.
Solution Approach 2:
The patent introduces an active cooling fan as an intermediary device to facilitate heat dissipation. The fan acts as a mediator between the heat sink and the surrounding air, forcing air flow through the heat sink fins to overcome the limited natural convection available in compact lamp designs, thereby enabling effective thermal management in small form factors.
2Illumination intensity
If higher current is applied to LEDs, then luminous output is improved, but heat generation increases leading to efficiency degradation
Solution Approach 1:
The patent converts the harmful effect of increased heat generation into a beneficial outcome by using the heat-driven air flow to enhance cooling. The active cooling system transforms the thermal challenge into an opportunity to drive forced convection through the heat sink, improving heat dissipation efficiency and enabling sustained high-current operation without degradation.
Solution Approach 2:
The patent changes the thermal management parameters by transitioning from passive natural convection to active forced convection. By controlling fan speed and air flow rate, the system can optimize the balance between heat generation and heat dissipation, allowing operation at higher currents while maintaining temperature within efficient ranges.
3Device complexity
If natural convection is used for cooling, then device complexity is reduced, but convective thermal resistance is too high for compact designs
Solution Approach 1:
The patent transitions from static passive cooling to dynamic active cooling. The fan enables the cooling system to adapt to varying thermal loads and environmental conditions, adjusting air flow to maintain effective heat dissipation. This dynamic capability ensures reliable thermal management across different operating conditions while the control system can optimize fan operation to minimize complexity.
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 solution significantly reduces convective thermal resistance, allowing LEDs to operate at lower temperatures, enhancing efficiency, reliability, and enabling higher current driving without degradation, thus improving luminous output and cost-effectiveness.
Implementation Method 1
Incorporating active elements such as fans to agitate air and reduce convective thermal resistance
Implementation Method 2
heat sinks and diffuser structures that promote omnidirectional light emission and effective thermal management
Implementation Method 3
heat sinks and diffuser structures that promote omnidirectional light emission and effective thermal management
Implementation Method 4
Light emitting diodes generally comprise one or more active layers of semiconductor material sandwiched between oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active layer where they recombine to generate light.
Implementation Method 5
The reflective cup may be filled with an encapsulant material 16 which may contain a wavelength conversion material such as a phosphor. Light emitted by the LED at a first wavelength may be absorbed by the phosphor, which may responsively emit light at a second wavelength.
Data Source
AI summary
Solid state lamp or bulb structures are disclosed that can provide an essentially omnidirectional emission pattern from directional emitting light sources, such as forward emitting light sources. The present invention is also directed to lamp structures using active elements to assist in thermal management of the lamp structures and in some embodiments to reduce the convective thermal resistance around certain of the lamp elements to increase the natural heat convection away from the lamp. Some embodiments include integral fans or other active elements that move air over the surfaces of a heat sink, while other embodiments comprise internal fans or other active elements that can draw air internal to the lamp. The fan's movement of the air over these surfaces can agitate otherwise stagnant air to decrease the convective thermal resistance and increasing the ability of the lamp to dissipate heat generated during operation.