Patent ID: 7851720

Claim:
A capacitive touch switch and circuit configuration, comprising: a sensor circuit supplying an output signal, said sensor circuit including: a capacitive touch switch having a measuring electrode and an additional electrode; a first voltage source for supplying an operating voltage having positive and negative poles; a first pnp transistor having a base, an emitter and a collector, a first resistor connected between the base of said first pnp transistor and said measuring electrode, a second resistor connected between the base of said first pnp transistor and the positive pole of the operating voltage, and a third resistor connected between the emitter of said first pnp transistor and the positive pole of the operating voltage, the collector of said first pnp transistor being connected to said additional electrode; a second voltage source for supplying a pulse voltage, said second voltage source connected between the collector of said first pnp transistor and a reference potential connected to the negative pole of the operating voltage; a second pnp transistor having a base, an emitter and a collector, the base of said second pnp transistor being connected with the emitter of said first pnp transistor, the collector of said second pnp transistor being connected with the reference potential, and a parallel circuit connected between the emitter of said second pnp transistor and the positive pole of the operating voltage, said parallel circuit having a fourth resistor and a capacitance; the output signal of said sensor circuit being present between the emitter of said second pnp transistor and the reference potential connected to the negative pole of the operating voltage; and an evaluation circuit receiving the output signal of said sensor circuit for determining whether or not said capacitive touch switch is actuated.