Door Handle Sensor Electrode Layout for Low-Interference NFC
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Solution Overview
Problem
Existing sensor devices for motor vehicle door handles face challenges in reducing installation space while maintaining sensitivity and minimizing interference between capacitive sensors and inductive near-field transmission devices.
Innovation Solution
A sensor device design featuring a capacitive sensor electrode surrounded by an inductive near-field transmission coil, with sensor sections arranged in a planar manner and inclined relative to coil sections, minimizing mutual inductance and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sensor electrode is placed inside the near-field transmission coil to save space, then the installation space is reduced, but the field strength of the near-field transmission coil is reduced due to mutual inductance
Solution Approach 1:
The sensor electrode is arranged inside the near-field transmission coil, nesting the capacitive sensor within the inductive transmission structure. This nesting reduces the overall installation space while maintaining both functional areas, resolving the space constraint contradiction.
Solution Approach 2:
The sensor electrode is designed with specific geometric characteristics (straight interconnected sections forming angles) that create regions of low magnetic flux density. This local optimization minimizes mutual inductance effects in critical areas, preserving field strength while maintaining the nested compact layout.
2Measurement precision
If larger sensor elements are used to increase sensitivity, then the sensitivity is improved, but the installation space requirement increases
Solution Approach 1:
By nesting the sensor electrode within the near-field transmission coil, the patent achieves overlapping spatial arrangement that allows both sensor elements to have large surface areas for high sensitivity while occupying minimal overall installation space.
Solution Approach 2:
The patent transitions from planar side-by-side arrangement to three-dimensional nested arrangement, utilizing the vertical dimension to accommodate both large sensor elements without increasing the horizontal footprint, thus maintaining sensitivity while reducing installation space.
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
Achieves a compact design with minimal field strength reduction and user-friendly operation by ensuring the capacitive sensor and near-field transmission coil operate independently with minimal interference.
Implementation Method 1
The capacitive sensor comprises a sensor electrode and a control and evaluation circuit. When, for example, an operator's hand approaches the sensor, the capacitance of the sensor electrode changes.
Implementation Method 2
A near-field communication (NFC) device can be provided, enabling communication between the vehicle and, for example, a mobile phone at close range. Such a NFC device can be based on the international Near Field Communication (NFC) transmission standard.
Implementation Method 3
placing the sensor electrode inside the near-field transmission coil, which serves as an antenna, reduces the field strength of the near-field transmission coil, since the electric field of the near-field transmission coil couples into the sensor electrode and thereby creates a mutual inductance that opposes and reduces the field strength of the near-field transmission coil.
Data Source
Figure 1~2
AI summary
The invention relates to a sensor device (1) for a motor vehicle, comprising a substrate (2) on which a sensor electrode (3) of at least one capacitive sensor and a near-field transmission coil (4) with at least one turn of at least one inductive near-field transmission device are arranged in a planar manner, wherein the sensor electrode (3) is at least partially surrounded by the near-field transmission coil (4), wherein the sensor electrode (3) has a plurality of straight-running and interconnected sensor sections (5), wherein the sensor sections (5) of the plurality of sensor sections (5) are connected in series and directly to each other, such that a first sensor section transitions directly into a directly following second sensor section, wherein the first sensor section and the second sensor section enclose an angle between them.