Iee International Electronics and Engineering S.a.

Daimler Chrysler Ag

Michael Virnich

Laurent Lamesch

David Hoyer

Michael Puetz

Thomas Meyers

Martin Thinnes

Aloyse Schoos

Frank Althaus

Andreas Petereit

Kurt Maute

Michael Pütz

Jochen Landwehr

Frank Kirschbaum

Madhukar Pandit

Micheal Puetz

A capacitive sensor configured for connection between a heating element and a heating current supply comprises a common mode choke (CMC) for AC-decoupling the heating element from the heating current supply. The CMC comprises first and second inductively coupled windings, the first winding for connection between a first terminal of the heating current supply and a first terminal of the heating element and the second winding for connection between a second terminal of the heating element and a second terminal of the heating current supply. The capacitive sensor further comprises a control and evaluation circuit for injecting an AC signal into the heating element via a measurement node, measuring a voltage on and/or a current across the measurement node, and to derive an impedance between the heating element and a counter electrode from the measurement. The CMC comprises a third winding inductively coupled with the first and second windings, the third winding being operatively coupled with the measurement node.

Capacitive sensor configured for using heating element as antenna electrode

A capacitive occupancy or proximity detector includes a heating circuit, an impedance measurement circuit connected to the heating element, and a diagnostic circuit configured for determining integrity of the heater element. The heating circuit includes a heating element, a heating current source and a common mode choke having a first and a second winding, the heating element being connectable to the heating current source via the first and second windings. The diagnostic circuit includes at least one controllable switching element coupled across the second winding, circuitry for injecting a DC current into a series connection formed by the first winding the heating element and a parallel connection of the second winding and the at least one controllable switching element, and at least one detection circuit for detecting a voltage variation across the second winding.

Capacitive occupancy or proximity detector

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 combined seat heater and capacitive occupancy sensor comprises a heater network and a capacitive sensing network. The heater network includes a heating element () connected between a first node () and a second node () to dissipate heat. The capacitive sensing network is connected to the heating element to apply an oscillating current thereto and to derive a capacitive load of the heating element from the voltage resulting on the heating element. The heater network comprises a common mode choke () connecting the first and the second node to a third () and a fourth () node, respectively. The capacitive sensing network further comprises means to sustain the oscillating current in or to drive the oscillating current into the heating element as well as a high-impedance amplifier () having an input node operatively connected to the heating element to probe the resulting voltage, and an output node () to provide an output signal indicative of the voltage.

Seat heater and capacitive occupancy sensor combination

In the case of known electromagnetic actuators each with at least one electromagnet acting on an armature, operational fluctuations of system parameters can lead to incorrect functioning, in particular to increased wear of the actuator, undesired noise generation, and excessive power consumption. In the new method, which is preferably used for operating gas change valves in internal combustion engines, the impact velocity of the armature on the electromagnet is automatically adjusted to a preset value. For this purpose, a controlled variable that depends on a change of inductance of the electromagnet is created as a measure of the impact velocity of the armature on The electromagnet and the controlled variable is adjusted by controlling the energy supply To the electromagnet to provide a setpoint value that the controlled variable adopts at a preset value of the impact velocity of the armature on the electromagnet. This permits reliable continuous duty with the new method.

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Korlingen, Germany

Michael Virnich