Patent ID: 9593932
Date: 2017-03-14
CPC Classifications: E05F,E05Y,G01B,G01V,H03K

Claim:
1. A method for detecting a capacitance of a sensor electrode, comprising the steps: charging a sensor electrode by coupling the sensor electrode to an operating voltage, decoupling the sensor electrode from the operating voltage and coupling the sensor electrode to a compensation capacitor, in order to bring about a charge compensation between the compensation capacitor and the sensor electrode, wherein the compensation capacitor is formed by one or more capacitors, and is adapted to be selectively coupled, via a switch device, to a compensation voltage, a ground, or in a floating manner, in relation to the sensor electrode, discharging a remaining charge of the sensor electrode via a first current path of a current mirror, wherein a corresponding current is generated in a second current path of the current mirror, and wherein a support capacitor is coupled to the second current path and is recharged by means of the generated current, wherein the preceding steps are repeated and a charge state of the support capacitor is evaluated as a measure of the capacitance of the sensor electrode wherein the compensation voltage is variable and is defined, dependent on the determined charge state of the support capacitor; and wherein the coupling of the individual capacitors to the sensor electrode is carried out depending on the determined charge state of the support capacitor.