Iee International Electronics and Engineering S.a.

David Hoyer

Michael Virnich

Laurent Lamesch

Thomas Meyers

Michael Puetz

Martin Thinnes

Frank Althaus

Andreas Petereit

Bogdan Serban

Aloyse Schoos

Philippe Boyer

Erik Holzapfel

Micheal Puetz

A capacitive seat occupancy detection and classification system with a capacitive sensor having at least two distinct antenna electrodes and a method of operating is proposed to reduce an impact of the sensor-to-object impedance Zon an object-to-ground impedance Zmeasurement that the system performs. By measuring the impedance between the different antenna electrodes by the system, additional information is obtainable that can be used to compensate the impact of the sensor-to-object impedance Zon the object-to-ground impedance. As one effect of combining both impedance measurement results, the proposed system is able to determine the object-to-ground impedance Zcompletely independent from wear of ISOFIX anchorages or human objects touching the electric ground of the vehicle, thus ensuring a stable classification of the object over the entire vehicle lifetime. The method further enables high-resolution seat occupancy classification.

Capacitive occupant detection system with improved discrimination capability

A combined heating and capacitive seat occupant sensing system comprises a common mode choke configured so as to satisfy at least one of a plurality of conditions, which is taken into account by a decision unit of the system in such a way that an influence of the common mode choke on the decision is compensated.

Combined heating and capacitive seat occupant sensing system

A capacitive occupancy or proximity detector () comprises a heating circuit, an impedance measurement circuit () and a diagnostic circuit. The heating circuit includes a heating element (). The impedance measurement circuit is connected to the heating element so as to measure impedance between the heating element and a node at ground potential. The diagnostic circuit is configured for measuring electrical resistance across the heating circuit and includes a heating current sensor (), configured for sensing a heating current across the heating circuit, a current supply device () for driving a diagnostic current across the heating circuit and a current limiting ground path (), configured for draining the diagnostic current and for blocking the heating current.

Diagnostic capacitive occupancy or proximity detector

A capacitive sensor for a vehicle seat comprises an antenna electrode and a control and evaluation circuit operatively connected to the antenna electrode. The control and evaluation circuit is configured to operate in a first mode of operation, during which it measures alternating electrical current flowing between the antenna electrode and ground. The capacitive sensor comprises a seat frame connector for connecting the control and evaluation circuit to the seat frame of the vehicle seat. The control and evaluation circuit is configured to operate in a second mode of operation, during which it measures electrical current flowing into the seat frame connector.

Capacitive sensor

A capacitive sensing system for a heating element comprises a capacitive detector connectable to the heating element and a common mode choke for connecting the heating element with a heating current supply. The detector drives an alternating current into the heating element and produces an output depending on the capacitive load, which the alternating current is subject to. Depending on the object sensed, the load varies in a range between a minimum and a maximum value. The choke represents an inductive load in parallel of the capacitive load. The capacitive load and the inductive load contribute to a complex impedance dominated by the inductive load. A compensation capacitor arranged parallel to the choke represents an additional capacitive load also contributing to the complex impedance. The compensation capacitor is dimensioned such that the sum of additional capacitive load and maximum value amounts to at least 50% of the inductive load.

Capacitive sensing system configured for using heating element as antenna electrode

A capacitive sensing system for being connected to a heating element comprises a capacitive detector connectable to the heating element and a common mode choke for essentially preventing alternating current from flowing from the heating element to the heating current supply. The capacitive detector is configured for driving an alternating current into the heating element and for producing an output indicative of capacitance based upon the alternating current. The choke has a first and a second winding for connecting the heating element with the heating current supply. The choke comprises a third winding connected in parallel of the first and/or second winding. The capacitive detector is configured for measuring a portion of the alternating current flowing across the third winding and for taking into account the measured portion of alternating current when producing the output.

Capacitive sensing system able of using heating element as antenna electrode

A plural-frequency capacitive occupancy sensing system comprises an antenna electrode and a detection circuit, which is configured to drive the antenna electrode at least with a first and a second signal at a first and a second frequency, respectively, so as to obtain at least a first and a second measurement value indicative of at least one of conductance, susceptance, resistance, reactance and capacitance between the antenna electrode and a reference node, at the first frequency and the second frequency, respectively. The detection circuit compares the capacitance between the antenna electrode and the reference node with a threshold capacitance, the threshold capacitance being derived from a difference between the first and second measurement values and/or the capacitance between the antenna electrode and the reference node being corrected based upon the difference between the measurement values. The detection circuit outputs an occupancy state signal depending on the comparison.

Plural-frequency capacitive occupancy sensing system

A method for capacitive sensing comprises the steps of tagging a transmitting signal by modulating a sub-carrier on said signal using state of the art modulation techniques; demodulating said subcarrier out of useful/received signal to prove validity of said signal.

Capacitive measurement system with increased robustness against electro-magnetic interference

A capacitive occupant detection system comprises at least one antenna electrode to be arranged in a seat and an evaluation unit operatively coupled to said at least one antenna electrode, said evaluation unit being configured for applying, during operation, an alternating voltage signal to said antenna electrode and for detecting an amplitude and/or phase of a displacement current flowing from said antenna electrode towards ground. According to the invention said antenna electrode comprises an antenna electrode conductor and at least one dedicated ground electrode, said ground electrode being arranged at a predetermined distance of said antenna electrode conductor and extending along said antenna electrode conductor.

Capacitive occupant detection system

A touchpad with an input area having a straight or curved main line of extension comprises a support element, a cover having a first surface facing away from the support element and a second surface facing towards the support element and one or more spacers arranged at a periphery of the input area. The one or more spacers mount the cover on the support element in such a way that the cover spans over the support plate in the input area while it is depressible towards the support element by a force acting on the input area of the touchpad. A resistive trace is so arranged on the support element that it extends along the main line of extension of the input area. At least one terminal contacts the resistive trace at a particular point of the main line of extension of the input area and a set of detection electrodes is arranged on the second surface of the cover in facing relationship with the resistive trace. The detection electrodes are configured and arranged for capacitively detecting a position of a user's finger or stylus when the user's finger or stylus is in proximity of or in light touch with the first surface of the cover, and for resistively detecting a position of a user's finger or stylus when the user's finger or stylus depresses the cover and so brings at least one of the detection electrodes into electrical contact with the resistive trace.

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Ayl, Germany

David Hoyer