Capacitive sensor arrangement for switching a door opening in a motor vehicle and associated method
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Solution Overview
Problem
Capacitive sensor systems face detection accuracy issues due to varying environmental conditions such as salt encrustations, dirt, and moisture, leading to erroneous actuation requests.
Innovation Solution
A capacitive sensor arrangement with a controllable base load assembly that adjusts capacitance values by switching on or off additional capacitive loads, ensuring the total capacitance remains within a detectable range, thereby compensating for environmental changes and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive sensor electrode is used to detect objects, then detection capability is provided, but detection accuracy deteriorates due to varying environmental conditions such as salt encrustations, dirt, and moisture
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the base load capacitance value according to environmental conditions. The control unit modifies the base load parameter to compensate for changes in total capacitance caused by environmental factors such as salt encrustations, dirt, and moisture, thereby maintaining accurate detection capability despite varying environmental influences.
2Reliability
If the sensor electrode capacitance changes due to environmental factors, then false actuation requests occur, but adding base load adjustment increases device complexity
Solution Approach 1:
The patent introduces a base load assembly as an intermediary element between the sensor electrode and the evaluation unit. This base load assembly, controlled by a control unit, acts as a mediator that compensates for environmental influences by adjusting the base load capacitance, thereby reducing false actuation requests while managing the increase in device complexity through a modular approach.
3Measurement precision
If additional capacitive loads are switched to adjust base load, then detection sensitivity is improved, but energy consumption increases
Solution Approach 1:
The patent applies dynamics by making the base load capacitance adjustable rather than fixed. The control unit dynamically switches additional capacitive loads based on the detected environmental conditions and total capacitance measurements. This dynamic adjustment improves detection sensitivity by optimizing the base load to match current environmental conditions while minimizing energy consumption by only activating additional capacitance when necessary.
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 enhances detection accuracy by maintaining the sensor system within a target capacitance range, reducing false actuation requests and increasing sensitivity by dynamically adjusting the base load in response to environmental influences.
Implementation Method 1
the capacitance of a capacitor depends on the distance between its plates. As a rule, its capacitance increases as the object gets closer to the sensor electrode
Implementation Method 2
The parameter of a current or voltage profile dependent on the periodic charging and discharging of the sensor electrode is a voltage measurable across a capacitor, which depends on the charge accumulated on the capacitor
Data Source
Figure 1~2
Figure 3
AI summary
A sensor arrangement for detecting motion gestures in a motor vehicle, having at least one capacitive sensor electrode (2, 3) and a control and evaluation device (4) coupled to the sensor electrode. Said control and evaluation device records a time sequence of capacitance values of the sensor electrode, wherein the control and evaluation device outputs an actuation signal on the basis of the time sequence. Coupled to the control and evaluation device is a controllable basic load subassembly (11, 12) which can be used to couple a capacitive basic load to the capacitive measurement load formed by the sensor electrode (2, 3) or to decouple said basic load from said measurement load on the basis of control, with the result that the connected basic load can be recorded, together with the measurement load, as a capacitive total load in the control and evaluation device (4). The basic load subassembly (11, 12) is controlled by the control and evaluation device on the basis of the recorded total load.