Capacitive proximity switch and domestic appliance equipped therewith
AssigneeBSH Bosch und Siemens Hausgeraete GmbH
InventorWilfried Klopfer
Life of this patent
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Abstract
A capacitive proximity switch has an electrically conductive sensor surface, which is covered by an electrically non-conductive covering plate and which serves as a part of a capacitor having a capacitance that varies with proximity. The sensor surface is connected to a control input of a semiconductor switch that has a signal input with a clock signal and a signal output. A household appliance is equipped with the capacitive proximity switch. The signal output of the semiconductor switch has an output signal, which follows the clock signal and which has signal portions that are proportional to the capacitance of the capacitor formed with the sensor surface.
Claims48
A capacitive proximity switch, comprising:
- an electrically insulating cover plate;
- an electrically conductive sensor surface covered by said electrically insulating cover plate and serving as part of a capacitor having a capacitance that varies with proximity;
- a semiconductor switch having a control input connected to said sensor surface, a signal input having a clock signal, and a signal output carrying an output signal following the clock signal, the output signal having signal components proportional to the capacitance of the capacitor formed with said sensor surface;
- a microprocessor having an analog input connected to said signal output of said semiconductor switch for evaluating the output signal, said microprocessor being configured to evaluate a change over time of signal components of the output signal, and to detect an actuation of the proximity switch in dependence on how quickly the signal components of the output signal of successive clock periods change.
A capacitive proximity switch, comprising:
- an electrically insulating cover plate and an electrically conductive sensor surface covered by said cover plate and forming a part of a capacitor having a capacitance that varies with proximity;
- a semiconductor switch having a control input connected to said sensor surface, a signal input having a clock signal, and a signal output carrying an output signal following the clock signal, the output signal having signal components proportional to the capacitance of the capacitor formed with said sensor surface;
- said sensor surface having active screening formed by a screening surface carrying the clock signal simultaneously with said sensor surface.
Dependencies are inferred from the claim text.