Lighting Device Thermal Management with Segmented Fan Control
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Solution Overview
Problem
Conventional semiconductor lighting devices face challenges with cooling due to constrained air flow and non-uniform heat generation and transfer, leading to temperature excursions and potential malfunctions, as existing control methods fail to account for these non-uniformities.
Innovation Solution
The method involves conductively coupling heat sinks to light-emitting elements, directing air flow from cooling fans to heat sinks, measuring temperatures, and adjusting fan speeds to reduce temperature deviations from a target temperature, while adjusting the target temperature based on aggregate characteristics of cooling fan speeds, thereby addressing non-uniform cooling demands across the lighting device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional closed loop feedback control is used to operate cooling fans, then fan noise and power consumption are optimized, but temperature excursions and device malfunction risk increase due to non-uniform cooling demand
Solution Approach 1:
The patent divides the cooling system into multiple independently controllable cooling fans, each associated with specific heat-generating components. Instead of using a single aggregated feedback control for all fans, the system segments the control to address local cooling demands, thereby preventing temperature excursions in high-heat regions while maintaining overall energy efficiency.
Solution Approach 2:
The patent implements differentiated cooling control by assigning different target temperatures and control parameters to different cooling fans based on their local thermal conditions. High-heat components receive aggressive cooling with lower target temperatures, while low-heat components receive moderate cooling, thereby achieving uniform temperature distribution and improving device reliability without excessive power consumption.
2Volume of moving object
If cooling fans are arranged in constrained air flow environment, then device size is reduced, but overall cooling capacity is reduced due to fans competing for restricted air flow
Solution Approach 1:
The patent dynamically adjusts the operating speed of each cooling fan based on real-time temperature measurements and thermal conditions. By modulating fan speeds rather than operating all fans at maximum speed, the system optimizes air flow distribution within the constrained volume, ensuring adequate cooling capacity is achieved without increasing device size.
Solution Approach 2:
The patent changes the operational parameters of cooling fans, specifically their rotational speeds, to optimize cooling performance within the constrained air flow environment. By varying fan speed parameters dynamically, the system achieves effective heat dissipation in a compact form factor.
3Device complexity
If uniform cooling control is applied across all cooling fans, then control simplicity is maintained, but temperature uniformity deteriorates due to non-uniform heat generation and air flow distribution
Solution Approach 1:
The patent implements a feedback control mechanism where temperature sensors continuously monitor thermal conditions at different locations, and this information is fed back to adjust the speed of individual cooling fans. This closed-loop feedback ensures temperature uniformity across the device while maintaining manageable control complexity through standardized control algorithms.
Solution Approach 2:
The patent applies preliminary cooling action to components known to generate higher heat or located in regions with poorer air flow. By pre-cooling these high-demand areas more aggressively, the system compensates for non-uniform heat generation and air flow distribution before temperature excursions occur, thereby maintaining temperature uniformity without excessive control 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
This approach reduces overall temperatures and increases the reliability of the lighting device by ensuring adequate cooling where needed and minimizing it where less necessary, compared to conventional methods.
Implementation Method 1
conductively coupling each of the heat sinks to the corresponding light-emitting element
Implementation Method 2
directing air flow from each of the cooling fans to the corresponding heat sink
Data Source
AI summary
Methods and systems for operating a lighting device are provided. In one example, a method of operating a lighting device including an array of light-emitting elements, an array of heat sinks, and an array of cooling fans, wherein each of the heat sinks corresponds to one of the light-emitting elements, and each of the cooling fans corresponds to one of the heat sinks, includes conductively coupling each of the heat sinks to the corresponding light-emitting element, directing air flow from each of the cooling fans to the corresponding heat sink, measuring heat sink temperatures corresponding to each of the heat sinks with a temperature sensor positioned at the heat sinks, adjusting a speed of each of the cooling fans to reduce a deviation of the corresponding heat sink temperature from a target temperature, and adjusting the target temperature based on an aggregate characteristic of the cooling fan speeds.