Circuit for capacitative touch-contact switch used in diverse household appliances, includes filter eliminating drift in working point of sensor circuit

摘要

The evaluation circuit (AS) includes a filter (TP1, S). This filters-out drift in the working point of the sensor circuit (KSS), in the absence of capacitative sensor operation. The evaluation circuit also includes a comparator (V). This compares the output signal (Out) of the sensor circuit with a threshold value (SW), after filtering out the drift in the working point. The threshold value is a relative value, i.e. it is related to the working point of the sensor circuit in the absence of capacitative sensor operation. Low pass filters and a subtracter are also included in the circuitry. An independent claim is included for the corresponding control method.