Capacitive sensing system and method
First Claim
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1. A capacitive sensing system for a vehicle, comprising:
- a capacitive sensing element;
a circuit configured to provide measurements related to an occupant of the vehicle based on a sensing current sent to the capacitive sensing element, the circuit located remote from the capacitive sensing element;
a switch configured to selectively couple the capacitive sensing element to the circuit, the switch being located proximate to the capacitive sensing element;
a harness configured to carry an electrical conductor that electrically couples the switch and the circuit and wherein the electrical conductor carries a first sensing signal from the circuit to the capacitive sensing element when the switch is closed and a second sensing signal from the circuit when the switch is open; and
electronics configured to receive measurements of the first and second sensing signals and to calculate a difference between the first and second sensing signals.
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Abstract
A capacitive sensing system includes a conductive sensing element and a circuit configured to provide measurements related to a sensing current sent to the sensing element. The circuit is located remote from the sensing element. The system also includes a switch configured to selectively couple the sensing element to the circuit. The switch is located proximate to the sensing element. The system also includes an electrical conductor that electrically couples the switch and the circuit. The conductor carries sensing signals from the circuit to the sensing element when the switch is closed.
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Citations
19 Claims
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1. A capacitive sensing system for a vehicle, comprising:
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a capacitive sensing element; a circuit configured to provide measurements related to an occupant of the vehicle based on a sensing current sent to the capacitive sensing element, the circuit located remote from the capacitive sensing element; a switch configured to selectively couple the capacitive sensing element to the circuit, the switch being located proximate to the capacitive sensing element; a harness configured to carry an electrical conductor that electrically couples the switch and the circuit and wherein the electrical conductor carries a first sensing signal from the circuit to the capacitive sensing element when the switch is closed and a second sensing signal from the circuit when the switch is open; and electronics configured to receive measurements of the first and second sensing signals and to calculate a difference between the first and second sensing signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A capacitive sensing system, comprising:
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a conductive sensing element; a circuit configured to provide measurements related to a sensing current sent to the conductive sensing element, the circuit located remote from the conductive sensing element; a switch configured to selectively couple the conductive sensing element to the circuit, the switch being located proximate to the conductive sensing element; an electrical conductor that electrically couples the switch and the circuit and wherein the electrical conductor carries a first sensing signal from the circuit to the conductive sensing element when the switch is closed and a second sensing signal from the circuit when the switch is open; and electronics configured to receive measurements of the first and second sensing signals and to calculate a difference between the first and second sensing signals. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for measuring a change in capacitance at a vehicle sensor, comprising the steps of:
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closing a switch located proximate to the capacitive sensing element using a control signal from a circuit; transmitting a first signal from the circuit to the capacitive sensing element over a conductor in a harness when the switch is closed; generating an electric field at a capacitive sensing element; providing a measurement based on the first signal using the circuit; measuring a capacitance between the harness and ground when the switch is open using the circuit to determine a second signal; and calculating a difference between the first signal and the second signal using the circuit. - View Dependent Claims (19)
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Specification