Sensor Cover Panel Contaminant Detection via Total Internal Reflection
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Solution Overview
Problem
Existing sensor devices with cover panels struggle to continuously detect and differentiate types of contaminants, such as water and oil, which impede the functionality of sensor elements due to wear and limited operational capabilities.
Innovation Solution
A sensor device with a detection system that uses an emitter to couple light into the cover panel at multiple angles, utilizing total reflection principles to identify contaminants by detecting changes in refractive indices, allowing for the determination of contaminant type and triggering appropriate countermeasures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover panel protects the sensor element from environmental influences, then the sensor element is protected from damage, but contaminants accumulate on the cover panel and impair sensor functionality
Solution Approach 1:
The sensor device performs self-diagnosis by using the sensor element to detect contaminants on its own cover panel. The sensor element alternates between measurement mode (detecting external targets) and self-diagnosis mode (detecting contaminants), enabling the system to monitor its own functionality without external intervention.
Solution Approach 2:
The system continuously monitors the cover panel condition and provides feedback about contaminant presence. Based on this feedback, the system can determine when cleaning is required and assess whether measurement values are reliable, creating a closed-loop control system for maintaining sensor performance.
2Reliability
If cleaning devices are used to remove contaminants, then sensor functionality is restored, but the cleaning devices wear out and cannot operate continuously
Solution Approach 1:
The system performs preliminary detection of contaminants before they significantly degrade sensor performance. By detecting contaminants early and triggering cleaning operations proactively, the system prevents severe soiling that would require more aggressive (and wear-prone) cleaning methods.
Solution Approach 2:
Instead of continuous operation, the cleaning device operates periodically based on detected contaminant levels. The sensor periodically assesses cover panel condition and triggers cleaning only when necessary, reducing overall wear on cleaning components while maintaining sensor functionality.
3Ease of operation
If rain sensors detect moisture on the cover panel, then cleaning can be triggered, but the type of contaminant cannot be characterized
Solution Approach 1:
The system measures multiple parameters of light interaction with the cover panel, including reflectance, transmittance, and absorption at different wavelengths. By analyzing changes in these optical parameters, the system can characterize contaminant type (e.g., water, oil, dust) in addition to detecting their presence.
Solution Approach 2:
The sensor element acts as an intermediary that indirectly characterizes contaminants by measuring how they modify light propagation. Instead of directly analyzing contaminant composition, the sensor measures optical property changes caused by the contaminants, enabling type identification through physical property analysis.
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
Enables continuous assessment of sensor functionality, differentiation between various contaminants, and targeted cleaning operations, ensuring optimal performance even in safety-critical applications like autonomous vehicles.
Implementation Method 1
light is coupled into the cover panel at a plurality of angles and, due to total reflection within the cover panel, is propagated up to the decoupling means
Implementation Method 2
the total reflection for light that has been coupled in at an angle within an extinction range, which is a function of the refractive index of the contaminants, is at least partially extinguished
Implementation Method 3
the detection device is configured to deduce the type of contaminant from the angles for which the total reflection has been extinguished
Data Source
AI summary
A sensor device including a sensor element, a cover panel, and a detection device detecting contaminants on the cover panel. The detection device includes an emitter emitting light, a coupling-in device coupling light into the cover panel, a decoupling device decoupling light from the cover panel, and a detector. The emitter and the coupling-in device couple light into the cover panel at a plurality of angles, and due to total reflection within the cover panel, the light propagates to the decoupling device and reaches the detector. If contaminants are on the cover panel, the total reflection for light coupled in at an angle within an extinction range is at least partially extinguished, and the detector is configured to detect the extinguishing of the total reflection for these angles. The detection device is configured to deduce the type of contaminant from the angles for which the total reflection has been extinguished.