Capacitive Vehicle Switch for Detecting Minimal Key Travel
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Solution Overview
Problem
Existing operating devices for vehicle components face challenges in detecting small movement strokes of key-type operating elements with high system stiffness, requiring precise measurement of minimal displacements to determine correct actuation.
Innovation Solution
An operating device with an elastically mounted operating element and a capacitor comprising a rigid first carrier body and an elastically bendable second carrier body, where the capacitor electrodes are arranged to change capacitance from high to low values upon actuation, allowing for capacitive detection of minimal displacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the system stiffness is increased to reduce movement stroke, then the movement stroke becomes smaller and more compact, but the measurement precision of the displacement deteriorates
Solution Approach 1:
The patent changes the measurement parameter from direct displacement measurement to capacitance measurement. By using a capacitive sensor that measures the change in capacitance caused by the displacement of the operating element, the system can accurately detect very small movements (in the micrometer range) even when the physical displacement is minimal. This parameter transformation resolves the contradiction by enabling precise measurement of small strokes.
2Reliability
If the movement stroke is reduced to be imperceptible to the user, then the device becomes more compact and secure, but the detection of correct actuation becomes more difficult
Solution Approach 1:
The patent replaces the mechanical detection system with an electrical capacitive detection system. Instead of relying on mechanical switches or sensors that require larger displacements, the capacitive sensor detects the electric field changes caused by the operating element's movement. This substitution enables reliable detection of imperceptibly small movements, resolving the contradiction between actuation security and detection difficulty.
3Measurement precision
If the distance between capacitor electrodes is reduced to increase capacitance sensitivity, then the measurement sensitivity improves, but the risk of electrical breakdown and manufacturing precision requirements increase
Solution Approach 1:
The patent employs a flexible membrane as one of the capacitor electrodes, which dynamically changes its position in response to the operating element's displacement. This dynamic configuration allows the electrode distance to vary with the measurement quantity, maximizing capacitance change sensitivity. The flexible membrane compensates for manufacturing tolerances through its elastic deformation, resolving the contradiction between sensitivity and manufacturing precision.
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 reliable detection of small movement strokes and actuating force with enhanced accuracy by utilizing a significant drop in capacitance, reducing the need for maintaining minimum distances between electrodes and providing tactile feedback.
Implementation Method 1
use is made of a capacitive sensor having two electrodes for detecting the movement stroke
Implementation Method 2
the second carrier body on its second end opposite to the first end is in operative connection with the counter-element, for movement of the second end of the elastically bendable second carrier body away from the first carrier body performed upon actuation of the at least one operating element
Data Source
AI summary
The operating device for an electrical apparatus or a system, in particular for a vehicle component, is provided with at least one elastically mounted operating element (12), a counter-element (14), relative to which the at least one operating element (12) is movable when actuated, thereby varying the distance, namely as seen in the movement direction, and at least one capacitor (38) which comprises a first carrier body (20) with a first capacitor electrode (34) and an elastically bendable second carrier body (22), designed as a bending bar, having a first end (26) and a second end (32) opposite said first end and having a second capacitor electrode (36) opposite the first capacitor electrode (34). Connected to the first and second capacitor electrode (34, 36) is an evaluation unit (42) for determining the capacitance and/or a change in the capacitance of the at least one capacitor (38) upon actuation of the at least one operating element (12).