In one embodiment, an apparatus includes a sensor, a button, a conductor between the button and the sensor, and a controller connected to the sensor. The sensor includes first and second electrode tracks. The button includes an electrically isolating material and is configured to capacitively couple with an object. The conductor is configured to capacitively couple with the sensor and form a galvanic connection between the first and second electrode tracks when the conductor comes into contact with the sensor. The controller is configured to measure a value associated with an amount of capacitive coupling between the conductor and the sensor and to detect first and second states of the button based on the value, the first state indicating that the object is in contact with the button and that the conductor is not contacting the sensor, and the second state indicating that the conductor is not contacting the sensor.

A sensor device for a motor vehicle includes a multi-layer circuit board on which a plurality of metallized planes are formed. A capacitive sensor electrode is formed on one of the planes for detection by capacitive approachment sensing. A control device controls the sensor electrode as a capacitive sensor electrode in order to detect approaches of a user towards the sensor electrode via an evaluation device. At least one planar electrode region is formed on each of the metallized planes, wherein each of the electrode regions is coupled to the control device. At least two of the electrode regions on different metallized planes are activated and evaluated as sensor electrodes and at least two of the electrode regions on different planes are activated and evaluated as the ground in a temporally offset manner.

In the present invention, a capacitance-type switch is provided with an operation plate and an electrode plate. The operation plate forms operation surfaces operated by the touch of a fingertip F (operation body) of a user. The electrode plate is disposed on the side of the operation plate opposite the operation surfaces. Furthermore, the capacitance-type switch is turned on and off in response to the change in capacitance caused between the fingertip F and the electrode plate. In addition, a high-permittivity material is disposed in an outer circumferential section of the electrode plate, the high-permittivity material having a higher permittivity than the operation plate. It is possible to improve the sensitivity of the capacitance-type switch while minimizing malfunctioning.

The present disclosure addresses methods and apparatus facilitating capacitive sensing using a conductive surface, and facilitating the sensing of proximity to the conductive surface. The sensed proximity will often be that of a user, but can be another source of a reference voltage potential. In some examples, the described systems are capable of sensing capacitance (including parasitic capacitance) in a circuit that includes the outer conductive surface, and where that outer conductive surface is at a floating electrical potential. In some systems, the systems can be switched between two operating modes, a first mode in which the system will sense proximity to the conductive surface, and a second mode in which the system will use a capacitance measurement to sense contact with the conductive surface.

In one embodiment, an apparatus includes a sensor, a button, a conductor between the button and the sensor, and a controller connected to the sensor. The sensor includes first and second electrode tracks. The button includes an electrically isolating material and is configured to capacitively couple with an object. The conductor is configured to capacitively couple with the sensor and form a galvanic connection between the first and second electrode tracks when the conductor comes into contact with the sensor. The controller is configured to measure a value associated with an amount of capacitive coupling between the conductor and the sensor and to detect first and second states of the button based on the value, the first state indicating that the object is in contact with the button and that the conductor is not contacting the sensor, and the second state indicating that the conductor is not contacting the sensor.

A capacitive sensing circuit is disclosed, wherein the mixer is directly connected to the sense electrode. The AC transimpedance amplifier in front of the mixer in prior art is removed and replaced by a differential DC transimpedance amplifier respectively integrator. The mixer DC offset voltage or current together with the large amplification factor required after the mixer now would result in an inacceptable DC offset at the output of the signal chain. In order to eliminate the effect of the mixer offset, the amplifying stages after the mixer are AC coupled to the mixer output and one of the signals entering the mixer is phase modulated or amplitude modulated with a known low frequency signal. An additional mixer after the AC coupled amplifying stages is driven with the same low frequency modulating signal, resulting in the wanted DC output signal responsive to the capacitance to be measured.

A capacitive button capable of improving tolerance to electrostatic discharge is provided. The capacitive button includes: a pair of sensor electrodes which are provided side by side; a floating electrode which is arranged on a front side of the pair of sensor electrodes via an insulating layer; and a ground electrode which is arranged so as to surround the floating electrode, and is grounded without being electrically connected with the pair of sensor electrodes and the floating electrode. By providing the configuration, the tolerance to the electrostatic discharge of the capacitive button can be improved.