Capacitance Rain Detector for Automotive Windshield
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Solution Overview
Problem
Existing automatic windshield wiper systems for automotive vehicles are costly and consume excessive power due to their reliance on complex optical processing techniques, making them less acceptable for medium and economy-priced vehicles, and manual adjustments are distracting and pose safety hazards for drivers.
Innovation Solution
A capacitance sensor with conductive traces on a polymeric sheet attached to the windshield, connected to a microcontroller that determines capacitance changes caused by raindrops, triggering the windshield wipers and adjusting their speed and pause duration based on rain intensity, using a programmable microcontroller and resistor-capacitor network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical processing techniques are used to detect raindrops, then rain detection accuracy is improved, but system cost and power consumption increase
Solution Approach 1:
The patent replaces complex optical processing systems with a simple capacitance sensing system. The capacitance sensor detects raindrops through electrical field changes rather than optical processing, dramatically reducing power consumption and system cost while maintaining effective rain detection capability.
Solution Approach 2:
The invention changes the detection parameter from optical properties to electrical capacitance. By measuring capacitance changes between conductive traces on the windshield, the system achieves rain detection with minimal power consumption and simple circuitry, avoiding the high energy requirements of optical systems.
2Measurement precision
If optical processing techniques are used to detect raindrops, then rain detection accuracy is improved, but system cost increases
Solution Approach 1:
The patent replaces complex optical processing systems with a simple capacitance sensing system. The capacitance sensor detects raindrops through electrical field changes rather than optical processing, dramatically reducing power consumption and system cost while maintaining effective rain detection capability.
Solution Approach 2:
The invention uses inexpensive conductive traces printed on a polymeric sheet as the sensing element, replacing expensive optical components. This capacitive sensing approach provides cost-effective rain detection suitable for medium and economy-priced vehicles.
3Device complexity
If manual wiper control adjustment is used, then wiper system simplicity is maintained, but driver safety is compromised due to distraction
Solution Approach 1:
The patent implements automatic windshield wiper control through capacitance sensing. The system automatically detects raindrops and activates/adjusts wiper operation without driver intervention, eliminating the distraction of manual adjustment while maintaining simple wiper mechanism design.
Solution Approach 2:
The invention creates a closed-loop system where capacitance sensors continuously monitor windshield conditions and provide feedback to the wiper control system. This automatic feedback mechanism eliminates the need for manual driver adjustment while keeping the overall system simple and reliable.
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 provides a cost-effective and power-efficient rain detection system that automatically controls windshield wiper speed and pause duration, reducing driver distraction and improving safety without the need for manual adjustments.
Implementation Method 1
the capacitance sensor may be of any construction, but preferably comprises a polymeric sheet having at least two conductive traces formed on the sheet
Implementation Method 2
the capacitance between the two traces on the polymeric substrate increases due to the conductivity of the water
Data Source
AI summary
A rain detector for use with an automotive vehicle. The rain detector includes a capacitance sensor mounted to the inside surface of a windshield. The sensor includes at least two output lines which vary in capacitance as the function of magnitude of rain on the outside surface of the windshield. A programmed microcontroller receives the sensor output lines as analog input signals and then compares the magnitude of the capacitance with a threshold capacitance. In the event that the sensed capacitance exceeds the threshold capacitance, indicative of raindrops on the outside surface of the windshield, the microcontroller generates an output signal to the wiper control circuitry of the vehicle to activate the windshield wiper system.