Iee International Electronics and Engineering S.a.

Christoph Wendt

Laurent Lamesch

Michael Puetz

Andreas Petereit

Christian Urig

Thomas Faber

Gianluca Favalli

Stephen Fuks

Tobias Justinger

Claus-Christian Kedenburg

Ingrid Scheckenbach

Frank Althaus

Michael Pütz

Baptiste Anti

Thomas Schleeh

Darren Khan

Harald Clos

Emmanuel Huegens

Heinrich Gierens

Dirk Johannes Thomas

Lukas Hillay

Jan Liptak

Johnny Lorang

Attila Konfar

Bernd Farsch

Thomas Krautheim

Marc Tonteling

An impedance measurement circuit for determining a complex impedance of a capacitive sensor having at least one sense electrode operable in loading mode and at least one guard electrode. The measurement circuit includes: a pulse generator unit for providing a periodic electric measurement signal and a periodic electric guard signal; a signal sensing circuit for sensing a sense current flowing through the at least one sense electrode or the sense electrodes in response to the pulse generator unit measurement signal; and a control and evaluation unit. The control and evaluation unit is configured for determining a complex impedance from the determined sense currents with reference to a complex reference potential.

Low-cost, high measurement speed capacitive sensing circuit for loading mode operation of capacitive sensors

An impedance measurement circuit for determining a complex impedance of a capacitive sensor that is configured for employing at least one electric heater member as an electrode to be operated in loading mode. The measurement circuit includes: a signal generating unit for providing an electric measurement signal; a signal sensing circuit measuring current through the at least one electric heater member; an electric heater member connection circuit comprising a plurality of MOSFETs for selectively electrically connecting the electric heater member either to the signal sensing circuit for complex impedance measurement or to a DC electric power unit for heating purposes; and a control and evaluation unit that is configured for controlling a switching status of the plurality of MOSFETs according to a predefined sequence, and for determining a complex impedance from the determined currents with reference to a complex reference potential during predefined stages of the predefined sequence.

Low-cost, protected capacitive sensing circuit for loading mode operation of capacitive sensors employing heater members

A capacitance measurement circuit for determining complex electric currents in a multi-channel capacitive sensing device includes a first sensing circuit for selectively connecting one of a plurality of sense electrodes to a common sense node and for connecting a corresponding guard electrode of the sense electrode to a common guard node, and at least a second sensing circuit. A measurement signal voltage source provides an alternating measurement voltage to the common guard node in a remotely controllable manner. A diagnostic signal voltage source provides an alternating diagnostic voltage to the common guard node in a remotely controllable manner. A current measurement circuit is connected with a signal input port to the common sense node and with a reference input port to the output port of the measurement signal voltage source.

Multi-channel capacitance sensing measurement circuit

A method of operating a capacitive measurement system for compensation of temperature influence is described. The capacitive measurement system includes at least one capacitive sensor member in an installed state and a capacitive measurement circuit for determining a complex impedance of an unknown capacitance from a complex sense current through the at least one capacitive sensor member. In the method, a calibration measurement is carried out to obtain temperature characteristics of both the real part and the imaginary part of determined impedances. In following impedance measurements of the unknown capacitance at a current temperature, the real part and the imaginary part of the measured impedance is determined, and based on the real part determined at the current temperature and the determined temperature characteristics of both the real part and the imaginary part, the imaginary part of the impedance determined at the current temperature is corrected.

Method of compensating temperature influence in capacitive measurements

A capacitive sensor system that includes: a sensor arrangement with a plurality of capacitive electrodes, each being connected to a corresponding detector line; and a detector device connected to each detector line and configured to detect the capacitance of each electrode by applying a detector signal. The sensor arrangement includes: at least one electrode group having at least two electrodes, each electrode of an electrode group being connected to another electrode via a resistive element so that all electrodes of this electrode group are connected in series; and a diagnose device that is connected, for each electrode group, at least to a first detector line of a first electrode and to a second detector line of a second detector electrode and is configured to apply a diagnose signal via the first and second detector lines and to detect a conductor break based on a response to the diagnose signal.

Capacitive sensor system

A capacitive sensor that includes: a sensing electrode having a capacitance to be measured; an alternating voltage source, configured to apply an alternating voltage to the sensing electrode; a capacitive first transfer device; a measurement circuit configured to measure the capacitance of the sensing electrode; and a switching arrangement. The switching arrangement is configured to alternately, in a first switching state, connect the first transfer device to the sensing electrode to enable a charge transfer from the sensing electrode to the first transfer device and, in a second switching state, connect the first transfer device to the measurement circuit to enable a charge transfer from the first transfer device to the measurement circuit.

Switching arrangement and method for a capacitive sensor

A capacitance measurement circuit for determining a sense current of a capacitive sensor which includes at least one electrically conductive sense electrode and at least one electrically conductive guard electrode. The measurement circuit includes at least one switch member that is remotely controllable by a switch remote control unit, wherein the at least one switch member in at least one closed state is configured to provide an additional electrical path between the at least one guard electrode and a reference potential.

Capacitive sensing system with hardware diagnostics concept for detection of sensor interruption

An automotive vehicle has arranged therein a vehicle seat and is equipped with an occupant detection system for detecting whether an occupant is present on the vehicle seat, the system including a first antenna electrode arranged in the seat and a sensing circuit associated with the seat where the sensing circuit includes an oscillation circuit connected to the first antenna electrode for applying to the first antenna electrode a first oscillating signal and a current detection circuit also connected to the first antenna electrode for determining a first current flowing in the first antenna electrode in response to the first oscillating signal being applied, the first current indicating whether an occupant is present on the vehicle seat, where the vehicle is further equipped with an appliance including an appliance control device arranged in the vehicle compartment at a location where it can be operated by an occupant of the seat and the occupant detection system is configured for detecting whether the occupant attempts to interact with the appliance control device, in particular, the occupant detection system includes a second antenna electrode arranged together with the appliance control device, and an oscillator is operatively connected to the second antenna electrode for applying a second oscillating signal to the second antenna electrode and the current detection circuit is configured for determining a second current flowing in the first antenna electrode in response to the second oscillating signal being applied to the second antenna electrode where the second current thus indicates whether an occupant of the vehicle seat has a part of their body proximate to the appliance control device.

Automotive vehicle with occupant detection system

An automotive vehicle has arranged therein a vehicle seat and is equipped with an occupant detection system for detecting whether an occupant is present on the vehicle seat, the system including a first antenna electrode arranged in the seat and a first sensing circuit associated with the seat, where the first sensing circuit includes an oscillation circuit operatively connected to the first antenna electrode for applying to the first antenna electrode a first oscillating signal and a first current detection circuit connected to the first antenna electrode for determining a current flowing into the first antenna electrode in response to the first oscillating signal being applied thereto, where the current flowing in the first antenna electrode indicates whether an occupant is present on the vehicle seat, and when in operation, the first sensing circuit codes the information whether an occupant is present on the vehicle seat into a first output signal which is output and which may be supplied to a restraint system control unit, the vehicle being further equipped with an appliance including an appliance control device arranged in the vehicle compartment at a location where an occupant of the seat can interact with it, a second antenna electrode is arranged with the appliance control device and a second sensing circuit is associated therewith, where the second sensing circuit is separate from the first sensing circuit and includes an electric signal detection circuit connected to the second antenna electrode and configured for determining an electric signal induced in the second antenna electrode in response to an electric field, which is radiated from an antenna electrode in the vehicle seat, being capacitively coupled into the second antenna electrode, the electric signal induced in the second antenna electrode indicates whether an occupant of the vehicle seat has a part of their body proximate to the appliance control device, and, when in operation, the second sensing circuit codes the information whether an occupant of the vehicle seat has a part of their body proximate to the appliance control device into a second output signal and outputs the second output signal.

Automotive vehicle with system for detecting the proximity of an occupant

A capacitive occupant detection system () comprises a sine signal generator () to apply a sine voltage signal to an antenna electrode () and a current measurement circuit () to measure current signals, based upon which a control and evaluation unit determines and outputs an occupancy state. The signal generator () is coupled to the antenna electrode via an amplitude adjustment stage (), configured to adjust the amplitude of said sine voltage signal applied to said antenna electrode to an amplitude selected among at least two discrete amplitudes. The control and evaluation circuit selects one of the discrete amplitudes at a time and causes the amplitude adjustment stage to adjust the amplitude of said the voltage signal applied to the antenna electrode accordingly. The control and evaluation circuit carries out an interference detection mode and an occupant detection mode. In interference detection mode, the current signals are measured while a low one of the at least two discrete amplitudes is selected and it is determined whether the antenna electrode is exposed to interference. In occupant detection mode, the current signals are measured while a high one of the at least two discrete amplitudes is selected and occupancy state is determined based upon the current signals thus measured.

Capacitive occupant detection system with interference detection

A vehicle seat is provided in combination with a seat heater and a capacitive occupant detection system. The seat heater comprises a seat heating element disposed in the vehicle seat while the capacitive occupant detection system comprises a measurement circuit and an electrode arrangement, which is also disposed in the vehicle seat. The electrode arrangement includes a sensing electrode and a shielding electrode. The measurement circuit is operatively connected to the sensing electrode and to the shielding electrode and configured to keep the sensing electrode and the shielding electrode at substantially the same electric potential during the capacitive measurement. Of the seat heating element, the sensing electrode and the shielding electrode, the seat heating element is closest to a seating region of the vehicle seat and the sensing electrode is arranged between the seat heating element and the shielding electrode.

Vehicle seat with capacitive occupant detection system

A transmitter electrode () for a capacitive sensing device comprises a conductive sheet material (), said conductive sheet material comprising a first connecting point () for connecting the electrode to an electronic sensing unit. According to the invention the conductive sheet material comprises at least one second connecting point for connecting the electrode to an electronic sensing unit, said second connecting point (') being arranged at a certain distance from said first connecting point so that said conductive sheet material forms a conductive path between said first and second connecting point. The first and second connecting point (&#x2032;), which in use are both connected to the electronic sensing unit, enable to check the integrity of the transmitter electrode and the connection lines used to connect the transmitter electrode to the electronic sensing unit.

Capacitive transmitter electrode

A capacitive occupant detection system has an oscillator and an electrode operatively coupled to the oscillator, to which the oscillator applies an oscillating voltage signal. In response to the oscillating voltage being applied, an electric current is caused to flow in the electrode, the current being responsive to an electric-field-influencing property of an object or occupant proximate to the electrode. The current caused to flow in the electrode has a first current component in phase with the oscillating voltage signal and a second current component 90&#xb0;-phase-offset with respect to the oscillating voltage signal. A sensing circuit is operatively coupled to the electrode and to the oscillator so as to generate a first signal indicative of the first current component and a second signal indicative of the second current component. The first signal indicative of the first current component and the second signal indicative of the second current component are provided to a processor, which is operatively coupled to the sensing circuit and which determines an occupancy state based upon the first and second signals indicative of the first and second current components, respectively, and outputs an output signal indicative of the occupancy state.

Capacitive occupant detection system

The capacitive coupling of at least two electrodes with an electrically conductive body may be determined when an AC voltage is applied to each of the electrodes and the currents flowing from each of the electrodes are measured. The currents flowing from each of the electrodes are measured n times, when n&gE;2, while different AC voltages are applied to the electrodes for each of the measurements. The coupling capacitances are calculated in a network analysis using the respective current and voltage values of the n measurements.

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Trier, Germany

Christoph Wendt