Pixelated Vehicle Headlight LED Control for Thermal Aging Compensation
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Solution Overview
Problem
The inhomogeneous stressing of light-emitting diodes in pixelated light sources used in motor vehicle headlights leads to inhomogeneous thermal aging and performance degradation, resulting in visible light inhomogeneities and potential inability to perform regulatory light functions due to different light functions being performed by the same source.
Innovation Solution
A method and control device that adapt the initial light setpoints of each light-emitting diode based on performance degradation indicators such as usage duration, electrical current intensity, voltage, and temperature, ensuring uniform behavior among the diodes by adjusting the pulse-width modulation control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple lighting functions are performed by the same pixelated light source, then lighting versatility is improved, but inhomogeneous thermal aging occurs among different LEDs
Solution Approach 1:
The patent applies local quality by individually monitoring and controlling each LED's performance based on its specific aging characteristics. Each LED is assigned a unique set of parameters (usage duration, current intensity, voltage, temperature) that are tracked separately, allowing tailored compensation strategies for each element rather than uniform treatment of the entire array.
Solution Approach 2:
The system implements feedback by continuously monitoring LED performance parameters and using this information to dynamically adjust control signals. The adaptation unit receives real-time data on LED aging and modifies the drive parameters accordingly, creating a closed-loop control system that compensates for thermal aging effects and maintains uniform lighting output.
2Productivity
If frequent use of the light source is allowed, then productivity is improved, but performance degradation accumulates leading to visible light inhomogeneities
Solution Approach 1:
The patent applies preliminary action by proactively monitoring LED performance parameters before significant degradation occurs. The system tracks usage duration, current intensity, voltage, and temperature from the outset, enabling early detection of aging trends and preemptive adjustment of control parameters to prevent visible inhomogeneities from developing.
Solution Approach 2:
The system implements feedback by continuously monitoring LED performance parameters and using this information to dynamically adjust control signals. The adaptation unit receives real-time data on LED aging and modifies the drive parameters accordingly, creating a closed-loop control system that compensates for thermal aging effects and maintains uniform lighting output.
3Manufacturing precision
If all LEDs are calibrated during assembly, then initial uniformity is improved, but uniformity is compromised by repeated use and thermal aging
Solution Approach 1:
The patent applies preliminary action by proactively monitoring LED performance parameters before significant degradation occurs. The system tracks usage duration, current intensity, voltage, and temperature from the outset, enabling early detection of aging trends and preemptive adjustment of control parameters to prevent visible inhomogeneities from developing.
Solution Approach 2:
The system transitions from static calibration during manufacturing to dynamic adjustment during operation. The adaptation unit continuously modifies LED drive parameters based on real-time aging data, allowing the system to adapt to changing conditions over time and maintain uniform performance throughout the LED array's service life.
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 compensates for performance losses, ensuring homogeneous light output and extending the operational lifespan of pixelated light sources, reducing maintenance costs and ensuring consistent regulatory light functions.
Implementation Method 1
A light-emitting diode, or LED, is a semiconductor component that emits light when a current flows through it at least equal to a threshold current. Above this threshold current, the brightness emitted by an LED is generally dependent on the current flowing through it.
Implementation Method 2
The junction temperature of the semiconductor component affects the LED's luminous performance, and thermal aging due to repeated use can also negatively impact its performance.
Data Source
Figure 1~2b
AI summary
The invention provides a method and device for controlling a pixelated light source in a motor vehicle. The invention is remarkable in that it compensates for inhomogeneities in the brightness of a pixelated light source, resulting from the non-homogeneous use of individual pixels within said light source.