Abstract: A method of operating a capacitive sensing device that includes a capacitive sensor having at least one sense electrode, a measurement signal source for providing an alternating electric measurement signal with at least three fixed predefined signal frequencies to the at least one sense electrode, and an impedance measurement circuit for determining an unknown complex impedance of the at least one sense electrode from a response to the provided electric measurement signal.

Abstract: A capacitive detection device includes a capacitive sensor having a sense electrode and an auxiliary electrode that are arrangeable in the vicinity of an electric heater member for mutual capacitive coupling. The capacitive detection device has a signal voltage source providing an alternating measurement voltage, a complex impedance measurement circuit for measuring complex sense currents and for determining a complex impedance based on the measured complex sense current, and for electrically connecting the auxiliary electrode either with the reference voltage or with the guard signal.

Abstract: A capacitive detection device includes a capacitive sensor having a sense electrode and an auxiliary electrode that are arrangeable in the vicinity of an electric heater member for mutual capacitive coupling. The capacitive detection device has a signal voltage source providing an alternating measurement voltage, a complex impedance measurement circuit for measuring complex sense currents and for determining a complex impedance based on the measured complex sense current, and for electrically connecting the auxiliary electrode either with the reference voltage or with the guard signal.

Abstract: A method of operating a capacitive sensing device for diagnosing a galvanic connection of at least one guard electrode. The capacitive sensing device includes at least one sense-guard capacitive sensor and a capacitive measurement circuit. The sense-guard capacitive sensor includes a first electrically conductive sense electrode and a first electrically conductive guard electrode and at least a second electrically conductive sense electrode, which is galvanically separated from the first sense electrode, and at least a second electrically conductive guard electrode. Each of the guard electrodes is proximally arranged to at least one of the sense electrodes and is galvanically separated from each of the sense electrodes. The method uses a calculated difference of imaginary parts of complex sense currents resulting from coupling mode measurements between at least two of the sense electrodes for assessing a status of the galvanic connection of the guard electrodes.

Abstract: A multi-electrode capacitive sensor is introduced to measure a spatial distribution of impedances to ground. The sensor can be used to identify the location of the highest impedance on the seating surface and can be a two-electrode sensor with a first electrode covering a central zone of a seat cushion and a second electrode with two galvanically connected electrode members, wherein each electrode member covers one side region of the seat cushion such that the first antenna electrode is arranged between the two electrode members of the second antenna electrode, or a two-electrode sensor with a left and right design. By measuring the difference of the impedance to ground between the two zones the system can get a simplified picture of the impedance distribution on the seating surface. This information can be used to distinguish between grounded structures such as (ISOFIX) child restraint systems and human occupants.

Abstract: A method of operating a capacitive sensing device for diagnosing a galvanic connection of at least one guard electrode. The capacitive sensing device includes at least one sense-guard capacitive sensor and a capacitive measurement circuit. The sense-guard capacitive sensor includes a first electrically conductive sense electrode and a first electrically conductive guard electrode and at least a second electrically conductive sense electrode, which is galvanically separated from the first sense electrode, and at least a second electrically conductive guard electrode. Each of the guard electrodes is proximally arranged to at least one of the sense electrodes and is galvanically separated from each of the sense electrodes. The method uses a calculated difference of imaginary parts of complex sense currents resulting from coupling mode measurements between at least two of the sense electrodes for assessing a status of the galvanic connection of the guard electrodes.

Abstract: A multi-electrode capacitive sensor is introduced to measure a spatial distribution of impedances to ground. The sensor can be used to identify the location of the highest impedance on the seating surface and can be a two-electrode sensor with a first electrode covering a central zone of a seat cushion and a second electrode with two galvanically connected electrode members, wherein each electrode member covers one side region of the seat cushion such that the first antenna electrode is arranged between the two electrode members of the second antenna electrode, or a two-electrode sensor with a left and right design. By measuring the difference of the impedance to ground between the two zones the system can get a simplified picture of the impedance distribution on the seating surface. This information can be used to distinguish between grounded structures such as (ISOFIX) child restraint systems and human occupants.

Abstract: 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 ZSO on an object-to-ground impedance ZOG measurement 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 ZSO on 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 ZOG completely 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.

Abstract: A sensor arrangement for capacitive position detection of an object. In order to provide means for hand detection on a steering wheel which are reliable and have a low complexity, the sensor arrangement includes: a sensor line with a plurality of sensor electrodes connected in series, wherein at least one resistive element is effectively connected in series between each two consecutive sensor electrodes, a measurement device connected via a linear, unbranched first connection to a first terminal of the sensor line, wherein the measurement device is configured to apply a time-dependent first signal to the first terminal and to identify an activated sensor electrode, with an object in its proximity, at least partially based on a first voltage-current relation at the first terminal.

Abstract: 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 ZSO on an object-to-ground impedance ZOG measurement 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 ZSO on 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 ZOG completely 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.

Abstract: A capacitive detection device and capacitive detection system for use in a vehicle interior includes at least one electrically conductive wire, at least partially attached to a component of the vehicle interior, and at least one electrically conductive layer that is arranged in close proximity to the at least one electrically conductive wire, compared to a potential minimum distance to a vehicle occupant, wherein a galvanic connection between the at least one electrically conductive layer and the at least one electrically conductive wire is avoided.

Abstract: In addition to the loading mode of a capacitive sensing device of a seat occupancy detection and classification system, a second measurement mode is introduced, which allows a discrimination of objects (CRS or human) with and without grounding condition. Depending on the value of the new measurement, the data is allocated to different groups which are subject to different thresholds in the loading mode. This means that if the new measurement indicates a grounding condition of the object, a higher threshold in the loading mode will be applied. In this way CRS with grounding condition will be classified by means of the higher threshold, resulting in a robustness increase. Typical human sitting positions do not show a grounding condition and will be classified by the lower threshold.

Abstract: A capacitive detection device and capacitive detection system for use in a vehicle interior includes at least one electrically conductive wire, at least partially attached to a component of the vehicle interior, and at least one electrically conductive layer that is arranged in close proximity to the at least one electrically conductive wire, compared to a potential minimum distance to a vehicle occupant, wherein a galvanic connection between the at least one electrically conductive layer and the at least one electrically conductive wire is avoided.

Abstract: A vehicle seat occupancy classification system having at least one weight-responsive sensor, including a supporting plate, a collecting plate, a hinge member mechanically connecting the supporting plate and the collecting plate, at least one elastic spring member, and a position sensor that is configured to determine a gap dimension between the supporting plate and the collecting plate. The occupancy seat classification system includes an evaluation unit that is configured to receive the output signal from the position sensor and to provide a seat occupant classification based on a level of the received output signal and at least a first pre-determined threshold value of the output signal.

Abstract: A capacitive occupancy or proximity detector (10) comprises a heating circuit, an impedance measurement circuit (34, 36, 40) and a diagnostic circuit. The heating circuit includes a heating element (12). 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 (42), configured for sensing a heating current across the heating circuit, a current supply device (48) for driving a diagnostic current across the heating circuit and a current limiting ground path (50), configured for draining the diagnostic current and for blocking the heating current.

Abstract: 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.

Abstract: A capacitive sensor (12) for a vehicle seat (10) comprises an antenna electrode (16) and a control and evaluation circuit (14) 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 (38) for connecting the control and evaluation circuit to the seat frame (20) 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.

Abstract: A capacitive occupancy or proximity detector (10) comprises a heating circuit, an impedance measurement circuit (34, 36, 40) and a diagnostic circuit. The heating circuit includes a heating element (12). 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 (42), configured for sensing a heating current across the heating circuit, a current supply device (48) for driving a diagnostic current across the heating circuit and a current limiting ground path (50), configured for draining the diagnostic current and for blocking the heating current.

Abstract: 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°-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.

Abstract: 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°-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.