Plural-frequency capacitive occupancy sensing system
First Claim
1. Plural-frequency capacitive occupancy sensing system, comprising an antenna electrode and a detection circuit, said detection circuit being configuredto drive said antenna electrode at least with a first and a second signal at a first and a second frequency, respectively;
- to obtain at least a first and a second measurement value indicative of at least one of conductance, susceptance, resistance, reactance and capacitance between said antenna electrode and a reference node, at said first frequency and said second frequency, respectively, the first frequency selected from a first frequency range and the second frequency selected from a second frequency range, said second frequency range being different from and non-overlapping with the first frequency range;
to compare a measured value between said antenna electrode and said reference node with a threshold value, said threshold value being derived from a difference between said first and second measurement values; and
to output an occupancy state signal depending on an outcome of said comparison.
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Abstract
A plural-frequency capacitive occupancy sensing system comprises an antenna electrode and a detection circuit, which is configured to drive the antenna electrode at least with a first and a second signal at a first and a second frequency, respectively, so as to obtain at least a first and a second measurement value indicative of at least one of conductance, susceptance, resistance, reactance and capacitance between the antenna electrode and a reference node, at the first frequency and the second frequency, respectively. The detection circuit compares the capacitance between the antenna electrode and the reference node with a threshold capacitance, the threshold capacitance being derived from a difference between the first and second measurement values and/or the capacitance between the antenna electrode and the reference node being corrected based upon the difference between the measurement values. The detection circuit outputs an occupancy state signal depending on the comparison.
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Citations
18 Claims
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1. Plural-frequency capacitive occupancy sensing system, comprising an antenna electrode and a detection circuit, said detection circuit being configured
to drive said antenna electrode at least with a first and a second signal at a first and a second frequency, respectively; -
to obtain at least a first and a second measurement value indicative of at least one of conductance, susceptance, resistance, reactance and capacitance between said antenna electrode and a reference node, at said first frequency and said second frequency, respectively, the first frequency selected from a first frequency range and the second frequency selected from a second frequency range, said second frequency range being different from and non-overlapping with the first frequency range; to compare a measured value between said antenna electrode and said reference node with a threshold value, said threshold value being derived from a difference between said first and second measurement values; and to output an occupancy state signal depending on an outcome of said comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification