Vehicle Presence Antenna Layout to Reduce Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing capacitive type presence sensors for motor vehicles face challenges in achieving both compactness and optimal sensitivity for user detection due to parasitic capacitance issues when integrating a capacitive electrode with a radiofrequency antenna.
Innovation Solution
A system comprising a capacitive electrode surrounded by a transmitting and receiving antenna with an electrically conductive line between them, which is not in direct contact, reduces parasitic capacitance by isolating the capacitive coupling and enhances sensitivity through a microcontroller-controlled charge transfer mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the radiofrequency antenna surrounds the capacitive electrode to achieve compactness, then the device compactness is improved, but the sensitivity of capacitive detection is reduced due to parasitic capacitance
Solution Approach 1:
An electrically conductive line is introduced as an intermediary element positioned between the capacitive electrode and the radiofrequency antenna. This conductive line acts as a mediator that manages the electromagnetic field distribution and reduces parasitic capacitance coupling between the electrode and antenna, thereby maintaining detection sensitivity while allowing the antenna to surround the electrode for compactness.
2Ease of manufacture
If the capacitive electrode and radiofrequency antenna are produced side-by-side on the same substrate, then the manufacturing process is simplified, but the spatial requirement increases
Solution Approach 1:
The capacitive electrode is positioned inside the loop of the radiofrequency antenna, creating a nested configuration where one component is embedded within the spatial envelope of the other. This nesting approach maximizes the use of available space on the substrate, reducing the overall area occupied by both components while maintaining their functional integrity and simplifying the manufacturing process.
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 system achieves high compactness and optimal sensitivity for approach detection by minimizing parasitic capacitance, allowing for reliable presence detection at increased distances and improved user recognition.
Implementation Method 1
The proximity of part of the human body increases the electrical charge in the vicinity of the capacitive electrode, and therefore the capacitance value of the measurement capacitor
Implementation Method 2
a transmitting and receiving antenna, configured to transmit and receive a radiofrequency signal in order to identify a user
Implementation Method 3
an electrically conductive line, located between the capacitive electrode and the transmitting and receiving antenna, without direct physical contact with either the capacitive electrode or the transmitting and receiving antenna
Data Source
AI summary
A system intended to be installed on a motor vehicle, comprising:a capacitive electrode (110), for implementing capacitive type presence detection;a transmitting and receiving antenna (120), surrounding the capacitive electrode (110);an electrically conductive line (130), located between the capacitive electrode and the transmitting and receiving antenna;a reference capacitor, connected between the capacitive electrode (110) and the electrically conductive line (130); anda microcontroller, configured to measure a voltage representing the capacitance of the measurement capacitor.The invention allows the sensitivity of presence detection by the capacitive electrode to be improved.