Optical Fiber Coupled ADAS Illumination for Thermal and Mass Reduction
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Solution Overview
Problem
The integration of active illumination systems in Advanced Driver Assistance Systems (ADAS) is hindered by size, weight, and thermal management constraints, particularly when trying to minimize pedestrian injuries in car accidents, as conventional designs require large heat sinks and are prone to electromagnetic compatibility issues.
Innovation Solution
The system separates the light source and its driver electronics from the projection optics using optical fibers, allowing the light source to be placed remotely, which reduces size and weight constraints and improves thermal management, while also simplifying electromagnetic compatibility through distributed placement and combined processing units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the complete illumination unit including light source, driver electronics and heat sink is built into the car front, then the illumination function is achieved, but the size, mass and hardness of the construction increase, making it non-compliant with pedestrian safety design requirements
Solution Approach 1:
The illumination system is divided into separate components: the light source with driver electronics is separated from the projection optics, connected via optical fibers. This segmentation allows the heavy heat sink to be positioned separately from the front-mounted projection optics, reducing the mass and hardness at the car front while maintaining full illumination functionality.
Solution Approach 2:
The heat sink is extracted from the front-mounted illumination unit and repositioned to a different location within the vehicle where thermal management is more effective. This extraction removes the primary source of mass and hardness from the pedestrian-contact area while preserving the illumination function through optical fiber transmission.
2Adaptability or versatility
If the illumination unit is positioned in the top-middle part or upper corner areas of the windshield, then integration is attempted, but the available space is very limited and heat sinking becomes extremely difficult given the tens of watts of waste heat
Solution Approach 1:
By segmenting the illumination system into light source/electronics and projection optics components connected by optical fibers, the patent enables independent positioning of each component. The projection optics can be integrated into the windshield area while the light source and heat sink are located in spaces with better thermal management capabilities, such as the engine compartment or dedicated cooling zones.
Solution Approach 2:
Optical fibers serve as an intermediary medium that decouples the thermal management requirements from the optical projection requirements. This allows the projection optics to be positioned in space-constrained windshield areas while the heat-generating light source and heat sink are positioned in thermally favorable locations, effectively mediating between spatial and thermal constraints.
3Illumination intensity
If high power semiconductor light sources like LEDs or diode lasers are used, then illumination intensity is improved, but electrical-to-optical power conversion efficiency decreases at elevated temperatures and device lifetime is shortened
Solution Approach 1:
The heat sink is extracted and positioned away from the light source location, enabling superior thermal management in a dedicated cooling location. This separation allows the high-power semiconductor light sources to operate at lower temperatures, maintaining high electrical-to-optical conversion efficiency and extending device lifetime while preserving the required illumination intensity.
Solution Approach 2:
The system incorporates temperature monitoring and active thermal management that provides feedback control to maintain optimal operating conditions for the semiconductor light sources. By continuously managing the thermal environment through the separated heat sink system, the light sources operate within their optimal temperature range, preserving efficiency and reliability.
4Object-affected harmful factors
If additional components like RF chokes and HF shielding sheets are incorporated for electromagnetic compatibility, then electromagnetic disturbances are reduced, but size and weight restrictions become more severe
Solution Approach 1:
The light source with its electromagnetic-generating driver electronics is extracted from the front-mounted projection optics and positioned in a separate location. This spatial separation inherently reduces electromagnetic coupling and interference, allowing for reduced electromagnetic shielding requirements at the projection optics location and overall reduction in the mass and volume of EMI protection components needed.
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 configuration enables more flexible and efficient placement of the illumination system, reduces the risk of pedestrian injuries, and enhances the reliability and accuracy of ADAS functions by optimizing thermal management and electromagnetic compatibility.
Implementation Method 1
a light source for converting electrical energy into light
Implementation Method 2
one or more optical fibers for transport of light generated by the light source to the projection optics
Implementation Method 3
The light source is thermally connected to a heat sink for evacuating heat produced by the light source
Implementation Method 4
a heat sink for evacuating heat produced by the light source
Data Source
AI summary
A driver assistance system (12) comprises an optical detector (14) with active scene illumination. The optical detector includes at least one of a stereoscopic imager, a time-of-flight imager, a structured-light imager and a night vision system. The optical detector includes a light source (16) for converting electrical energy into light, projection optics (18) for illuminating a scene with light generated by the light source and one or more optical sensors (20) for detecting light returned from the scene in response to the scene being illuminated. The light source is thermally connected to a heat sink (30) for evacuating heat produced by the light source and the projection optics are optically connected to the light source with one or more optical fibers (22) for transport of light generated by the light source to the projection optics.