Capacitive sensor
OwnerGeorge Axel Krugerinventor
Life of this patent
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Abstract
A capacitive sensor system for detecting an object. The capacitive sensing system includes a capacitive sensing pad, a conductive discriminating pad, a switch, a capacitance measurement circuit and a controller. The conductive discriminating pad is in proximity to the capacitive sensing pad. The switch includes an input terminal coupled to the discriminating pad. The switch selectively couples the discriminating pad to a voltage potential of the capacitive sensing pad or to a ground potential. The capacitance measurement circuit detects a capacitance value of the capacitive sensing pad. The controller is operable to measure the capacitance value of the capacitive sensing pad when the discriminating pad is coupled to the capacitive sensing pad voltage potential or to the ground potential.
Claims14
A capacitive sensor system for detecting an object, comprising:
- a capacitive sensing pad;
- a conductive discriminating pad in proximity to the capacitive sensing pad;
- a switch having an input terminal coupled to the discriminating pad, the switch selectively coupling the discriminating pad to a voltage potential of the capacitive sensing pad or to a ground potential;
- a capacitance measurement circuit that detects a capacitance value of the capacitive sensing pad;
- and
- a controller operable to measure the capacitance value of the capacitive sensing pad when the discriminating pad is coupled to the capacitive sensing pad voltage potential and when the discriminating pad is coupled to the ground potential.
A method of identifying an object or substance, comprising:
- providing a capacitive sensing pad and n conductive discriminating pads where n≥1;
- providing a shield driver that provides a voltage potential of the capacitive sensing pad;
- providing n switches that each have an input terminal coupled to one of the n discriminating pads and have two switch connection states which selectively couple the input terminal to the capacitive sensing pad voltage potential or to the ground potential, wherein the n switches are operable to provide 2nd unique connection states for the n discriminating pads;
- placing the object in proximity to the capacitive sensing pad;
- measuring up to 2nd capacitance values of the capacitive sensing pad that each correspond to one of the 2n unique connection states for the n discriminating pads;
- determining a capacitance value for the object or substance by comparing a first set of the 2n capacitance values and a second set of the 2n capacitance values;
- and
- identifying the object or substance by comparing the capacitance value to one or more reference capacitance values for reference objects or substances having the same and/or different material properties as the object or substance.
A method of identifying an object or substance, comprising:
- providing a capacitive sensing pad and n conductive discriminating pads where n≥1;
- providing a shield driver that provides a voltage potential of the capacitive sensing pad;
- providing n switches that each have an input terminal coupled to one of the n discriminating pads and have two switch connection states which selectively couple the input terminal to the capacitive sensing pad voltage potential or to the ground potential, wherein the n switches are operable to provide 2n unique connection states for the n discriminating pads;
- placing the object or substance in proximity to the capacitive sensing pad;
- and
- taking capacitive measurement sets of the object or substance, each measurement set corresponding to 2n capacitance values measured using the capacitive sensing pad for the 2n unique connection states for the n discriminating pads;
- determining a mathematical relationship between the capacitive measurement sets and known dielectric constants or dipole moments of the object or substance;
- identifying the object or substance based on the mathematical relationship and the known dielectric constants or dipole moments of the object or substance.
Dependencies are inferred from the claim text.