Vehicle Capacitive Activation Sensing With Synchronous Rectification
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Solution Overview
Problem
Capacitive detection systems in vehicles face interference issues due to disruptive emissions and environmental influences, such as parasitic capacitances, which affect the accuracy of detecting activation actions for activating vehicle functions.
Innovation Solution
An arrangement with a sensor element, control arrangement, and rectifier arrangement that generates and evaluates electrical control signals to manage charge transfers, using synchronized rectification and filtering to isolate specific harmonics and reduce interference, allowing precise detection of activation actions for activating vehicle functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If charge transfer is used for capacitive sensing, then sensor evaluation is enabled, but interfering emissions are generated
Solution Approach 1:
The patent applies periodic action by using synchronous rectification that operates at the same frequency as the sensor excitation signal. The rectifier is controlled to switch periodically in sync with the excitation signal, allowing the sensor signal to be separated from interfering emissions through frequency-based discrimination. This periodic synchronization enables accurate capacitive detection while filtering out non-synchronized interference.
2Reliability
If synchronous rectification is used, then interference suppression is improved, but device complexity increases
Solution Approach 1:
The patent merges the rectifier control with the existing sensor evaluation timing signals. The rectifier is controlled using the same clock or timing signals that already drive the sensor excitation, eliminating the need for separate control circuits. This integration reduces device complexity while maintaining the benefits of synchronous rectification for interference suppression.
3Measurement precision
If multiple rectifiers are used for harmonic suppression, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses periodic action with multiple rectifiers operating at different phases or frequencies to selectively suppress harmonic components. Each rectifier is synchronized to specific frequency components of the sensor signal, allowing fundamental frequency detection while filtering out harmonic interference. The periodic switching of multiple rectifiers enables precise signal separation without requiring complex continuous processing circuits.
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 the accuracy and reliability of capacitive detection by minimizing interference, enabling precise detection of activation actions and improving electromagnetic compatibility, thus effectively activating vehicle functions such as unlocking or starting the engine.
Implementation Method 1
a sensor element, such as a sensor electrode, can provide a variable capacitance that is specific to changes in the environment of the sensor element
Implementation Method 2
a rectifier arrangement, which is connected for rectifying the electrical sensor signal between an electrical storage arrangement and the transmission arrangement
Implementation Method 3
a control arrangement for generating an electrical control signal for carrying out repeated charge transfers at the sensor element
Data Source
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AI summary
The invention relates to an assembly (10) for a vehicle (1) for detecting an activation handling process for activating a function on the vehicle (1), in particular for detecting an activation handling process in a front, lateral, and/or rear region (1.7, 1.4, 1.2) of the vehicle (1) for activating an opening and/or unlocking procedure of a hatch (1.3, 1.6) on the vehicle (1), having: - at least one sensor element (20) for detecting a change, in particular the approach of an activation means (3), in the surroundings of the sensor element (20), - a monitoring assembly (100) in order to generate an electric actuation signal for carrying out repeated charge transfers in the sensor element (20) and for a capacitive sensor analysis of the sensor element (20), - a transmission assembly (170, 210) for providing an electric sensor signal using the repeated charge transfers and using the actuation signal, - a rectifier assembly (220) which is connected between an electric storage assembly (250) and the transmission assembly (170, 210) in order to rectify the electric sensor signal so as to transmit the sensor signal to the storage assembly (250) in a rectified state while analyzing the sensor, and - a monitoring device (300) for repeatedly ascertaining at least one parameter specific to the detection, in particular a variable capacitance (CS), of the sensor element (20) using an analysis in the storage assembly (250), in particular of the charge quantity stored therein, in order to carry out the detection of the activation handling process using the charge transfers for the sensor analysis.