Abstract: A capacitive measurement circuit for a capacitive sensing device having a plurality of antenna electrodes includes: a measurement signal voltage source, a remotely controllable switching unit, and a current measurement circuit. The switching unit includes a plurality of ports and switching members that are configured to provide connections between selected ports. The measurement signal voltage source and the current measurement circuit are operatively connected to a distinct port. Each antenna electrode is individually connectable to a distinct port. The switching unit is configured to connect, within a same measurement cycle, each of the antenna electrodes to the voltage output port and the current measurement circuit for loading mode operation. The switching unit is further configured to connect at least one of the antenna electrodes to the voltage output port and at least one other antenna electrode of the antenna electrodes to the current measurement circuit for coupling mode operation.

Abstract: A method of operating a capacitive sensing device that includes exactly two electrically conductive antenna electrodes, which are placeable in two layers at a vehicle steering wheel rim, and a current measurement circuit for determining complex electric currents in the antenna electrodes. The method includes at least the following steps for constituting a measurement cycle: operating each one of the exactly two antenna electrodes in loading mode and determine the complex impedance of the respective antenna electrode; and generating a classification signal that is indicative of a present scenario, based on a fulfillment of at least one predetermined condition concerning at least one characteristic quantity of the first complex impedance as well as of the second complex impedance.

Abstract: A sensor arrangement for capacitive position detection of a hand on a steering wheel. The sensor arrangement includes: a plurality of capacitive sensors disposed along a detection surface, which is an outer surface of the steering wheel, each sensor having at least one sensor electrode; and a measurement device electrically connected to the sensors. In order to increase the reliability of capacitive hand detection on a steering wheel, the measurement device is adapted to perform a sequence of detection operations, and in each detection operation, to activate at least one sensor by applying a detection signal to its at least one sensor electrode in order to capacitively detect the hand while grounding at least one other sensor by connecting at least one of its sensor electrodes to ground, and to activate different sensors in consecutive detection operations.

Abstract: 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.

Abstract: A vehicle seat occupant classification system for use in a vehicle seat includes a weight-responsive sensor, at least one bracket member serving as a holder for the weight-responsive sensor, and an evaluation unit configured to evaluate a status of the at least one weight-responsive sensor. The bracket member is fixedly attached to the seat base. If a mechanical load at least corresponding to a first pre-determined threshold value is applied by a seat occupant, a portion of the vehicle seat comes into mechanical interaction with the at least one weight-responsive sensor, and is configured to change a status of the at least one weight-responsive sensor if a mechanical load at least corresponding to a second pre-determined threshold value is applied. Relative movement between the seat base and the at least one weight-responsive sensor is at least excluded for applied mechanical loads that are smaller than the first pre-determined threshold value.

Abstract: A capacitive occupant detection system (10) comprises a sine signal generator (12) to apply a sine voltage signal to an antenna electrode (14) and a current measurement circuit (18, 20, 28, 30, 40) to measure current signals, based upon which a control and evaluation unit determines and outputs an occupancy state. The signal generator (12) is coupled to the antenna electrode via an amplitude adjustment stage (13), 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.

Abstract: A capacitive occupant detection system (10) comprises a sine signal generator (12) to apply a sine voltage signal to an antenna electrode (14) and a current measurement circuit (18, 20, 28, 30, 40) to measure current signals, based upon which a control and evaluation unit determines and outputs an occupancy state. The signal generator (12) is coupled to the antenna electrode via an amplitude adjustment stage (13), 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.