| 摘要 |
A capacitive sensor array comprises a sensor electrode by which the intrusion of an object into a space in front of the sensor electrode is detected, a shield electrode and a background electrode. A control and evaluation circuit is coupled with the sensor electrode. This control and evaluation circuit detects a change in the capacitance of the sensor electrode in comparison to a reference potential, in that the sensor electrode, at a given frequency, periodically and repeatedly couples with a given first potential evaluates at least one parameter of a current and voltage profile dependent on the periodic charging and discharging of the sensor electrode in order to detect the capacitance change, The background electrode is arranged at a distance behind the sensor electrode. The shield electrode is arranged between the sensor electrode and the background electrode and coupled with the sensor electrode through the control and evaluation circuit such that it has no influence on the capacitance measured in comparison to the reference potential and its potential is essentially adjusted to the potential of the sensor electrode. The background electrode is controlled by the control and evaluation circuit such that its potential is periodically switched, at the given frequency, between the reference potential and a second potential that has the same polarity as the first potential in comparison to the reference potential. At least during part of those times in which the sensor electrode is coupled with the first potential, the background electrode is located on the reference potential. At least during part of those times in which the sensor electrode is not coupled with the first potential, the background electrode is located on the second potential.
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