Dual-Electrode Door Handle Sensing to Prevent False Triggering
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Solution Overview
Problem
Capacitive sensors for motor vehicle doors are sensitive to environmental conductive elements and weather conditions, leading to incorrect triggering of locking or unlocking actions due to variations in capacitance caused by external factors like rain or conductive decorative parts.
Innovation Solution
A dual-electrode sensor system where the first and second electrodes are arranged to overlap partially or not at all, with each electrode connected to a processing unit to differentiate capacitance variations due to hand approach from those caused by external environments, using a guard plane to minimize crosstalk and enhance signal processing, and positioning potentials alternately between electrodes to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single capacitive electrode is used for door locking/unlocking, then the device is simple and easy to manufacture, but it is highly sensitive to environmental factors like rain and conductive decorative parts causing false triggering
Solution Approach 1:
The patent divides the single electrode into two separate electrodes (first electrode and second electrode) with offset detection zones. This segmentation allows the system to distinguish between genuine hand approaches and environmental interference by comparing capacitance variations from different spatial locations, thereby improving reliability without significantly increasing complexity.
Solution Approach 2:
The patent introduces a processing unit that acts as an intermediary between the electrodes and the door actuation system. This processing unit analyzes capacitance variations from both electrodes, determines whether they represent genuine user intent or environmental noise, and only triggers door locking/unlocking when genuine hand approach is detected, thus improving triggering accuracy.
2Area of stationary object
If the electrode detection zone covers the entire gripping lever surface, then detection coverage is maximized, but sensitivity to environmental interference like rain and conductive parts increases
Solution Approach 1:
The detection zone is segmented into two offset zones (first detection zone and second detection zone) that do not entirely overlap. This segmentation reduces the area susceptible to environmental interference while maintaining adequate coverage for genuine hand approaches, as rain or conductive parts would need to simultaneously affect both offset zones to cause false triggering.
Solution Approach 2:
The two detection zones are positioned asymmetrically with an offset between them. This asymmetric arrangement creates different spatial patterns for genuine hand approaches versus environmental interference, allowing the processing unit to distinguish between them by analyzing the pattern of capacitance variations across the asymmetric zones.
3Measurement precision
If capacitance threshold is set low to detect all hand approaches, then detection sensitivity is high, but false triggering from environmental factors increases
Solution Approach 1:
The system uses feedback from two electrodes to validate capacitance variations. The processing unit compares capacitance changes from both electrodes and only triggers door actions when the variations are consistent with genuine hand approach patterns. This feedback mechanism allows the system to maintain high detection sensitivity while filtering out environmental noise that would not produce consistent patterns across both offset zones.
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
Effectively differentiates genuine hand approaches from environmental influences, ensuring accurate triggering of door actions only when intended by the user, reducing false activations from rain or conductive external elements.
Implementation Method 1
a first capacitance measurement electrode E1 defining a first detection zone Z1 and a second capacitance measurement electrode E2 defining a second detection zone Z2
Implementation Method 2
variations in capacitance of the two electrodes E1, E2 and to generate a trigger action on the opening of the motor vehicle according to the signatures of the capacitance variations of each of the two electrodes E1, E2
Data Source
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AI summary
The invention concerns a device (1) for triggering an action on a door of a motor vehicle. The triggering device (1) comprises: a first capacitance measuring electrode (E1) defining a first detection area (Z1) and a second capacitance measuring electrode (E2) defining a second detection area (Z2), said first electrode (E1) and said second electrode (E2) being arranged in such a way that said first area (Z1) and said second area (Z2) are spatially offset, - a processing unit (UT) connected to said first electrode (E1) and to said second electrode (E2) to detect capacitance variations in the two electrodes (E1, E2) and to generate a triggering action on the door of the motor vehicle based on the signatures of the capacitance variations of each of the two electrodes (E1, E2) caused by a hand approaching the two detection areas (Z1, Z2). The invention is particularly applicable to the automobile field.