Capacitive Sensor Field Shaping via Insulated Conductor
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Solution Overview
Problem
Existing contactless vehicle door actuation systems face challenges in distinguishing between intended foot movements for door opening and other movements due to spatial constraints and reduced sensitivity caused by shielding electrodes, which complicates the arrangement and sensitivity of capacitive proximity sensors.
Innovation Solution
The use of an insulated electrical conductor, which forms an equipotential surface and shapes the detection field without weakening it, allowing for precise separation and alignment of detection fields and maintaining sensor sensitivity, is employed to improve the reliability and simplicity of contactless vehicle door actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shielding electrodes are used to separate detection fields, then spatial separation is improved, but sensor sensitivity deteriorates due to offset capacitance
Solution Approach 1:
The patent introduces a dielectric body as an intermediary element positioned between the sensor electrode and the vehicle body. This dielectric body shapes the detection field to improve separation between multiple sensors while avoiding the harmful offset capacitance that would result from direct electrical connection. The dielectric material modifies the electric field distribution without creating a conductive path to ground, thus maintaining sensor sensitivity while achieving field separation.
2Measurement precision
If sensor electrodes are arranged at large distance, then detection field separation is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by positioning dielectric bodies at specific locations between the sensor electrodes and the vehicle body. Rather than requiring all sensors to be spaced far apart, the dielectric elements are strategically placed in the regions where field separation is most needed. This allows for closer electrode spacing while achieving the required detection field separation through localized field modification.
3Object-affected harmful factors
If shielding electrodes are used for electrical shielding, then electromagnetic interference is reduced, but additional circuitry complexity increases
Solution Approach 1:
The patent extracts the shielding function from the traditional electrical/conductive approach and implements it through dielectric materials instead. By removing the need for conductive shielding electrodes and their associated grounding circuits, the solution eliminates the additional circuitry complexity while still achieving electromagnetic interference reduction through the field-shaping properties of the dielectric bodies.
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
This solution enables reliable differentiation of intended foot movements from other movements, enhances sensor sensitivity, and simplifies the system design by eliminating the need for shielding electrodes, thus improving the accuracy and flexibility of contactless door operation.
Implementation Method 1
a capacitive proximity sensor with at least one sensor electrode for emitting an electric detection field in a detection space in front of the sensor electrode
Implementation Method 2
emitting an electric detection field in a detection space
Implementation Method 3
the insulated conductor forms an equipotential surface in the electrical detection field of the sensor electrode. Charge transfer inside the conductor deforms the field lines of the detection field in the vicinity of the conductor in such a way that the field lines hit the surface of the conductor everywhere perpendicularly
Data Source
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AI summary
The invention relates to a device (3) for actuating a door (2) of a vehicle (1) in a contact-free manner. Said device (3) comprises a capacitive proximity sensor (5) which comprises at least one sensor electrode (6) for emitting an electric detection field (F1 ) in a detection area (10) upstream of the sensor electrode (6). An insulated electric conductor (25) is arranged upstream of the sensor electrode (6) for forming the detection area (F1).