METHOD AND SYSTEM FOR DETECTING AN OCCUPANT IN A VEHICLE SEAT
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Abstract
An occupant detection system comprises an electrode arrangement for placement into a seat of an automotive vehicle and an evaluation circuit operatively connected to the electrode arrangement. The latter includes a first electrode for emitting an electric field into a detection region above the vehicle seat, a second electrode and an electric insulator layer sandwiched between the first and second electrodes. When the electrode arrangement is in place in the seat, the first electrode forms with vehicle ground a first capacitor having a first capacitance, which is influenceable by an occupying item in the detection region through interaction of the occupying item with the electric field, the first electrode forms with the second electrode a second capacitor having a second capacitance and the second electrode forms with at least one of vehicle ground and a third electrode a third capacitor having a third capacitance. As a first indicator of the seat occupancy state, a measure of the first capacitance is determined while the first electrode is caused to emit an electric field into said detection region and the second electrode is operated as a driven shield for the first electrode. The fluctuations of at least one of the first, second and third capacitances are measured and the frequency spectrum of the measured fluctuations is analysed, which yields a second indicator of the occupancy state. The derivation of the occupancy state of the seat is then based on both the first indicator and the second indicator.
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Citations
48 Claims
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1-24. -24. (canceled)
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25. A method of detecting an occupancy state of a vehicle seat using an occupant detection system comprising an electrode arrangement for placement into the vehicle seat, said electrode arrangement including a first electrode to emit an electric field into a detection region above said vehicle seat, a second electrode and an electric insulator layer sandwiched between said first and second electrodes;
- wherein, during use of said occupant detection system, said first electrode forms with vehicle ground a first capacitor having a first capacitance, which is influenceable by an occupying item in said detection region through interaction of said occupying item with said electric field, said first electrode forms with said second electrode a second capacitor having a second capacitance and said second electrode forms with at least one of a third electrode and vehicle ground a third capacitor having a third capacitance;
said method comprising; determining, as a first occupancy state indicator, a measure of said first capacitance in a time interval during which said first electrode is caused to emit an electric field into said detection region and said second electrode is operated as a driven shield for said first electrode; measuring fluctuations of at least one of said first, second and third capacitance; determining a second occupancy state indicator through analysing a frequency spectrum of said measured fluctuations; and
deriving an occupancy state of said seat based on both said first and said second occupancy state indicators, i.e. on both said measured first capacitance and said frequency spectrum. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
- wherein, during use of said occupant detection system, said first electrode forms with vehicle ground a first capacitor having a first capacitance, which is influenceable by an occupying item in said detection region through interaction of said occupying item with said electric field, said first electrode forms with said second electrode a second capacitor having a second capacitance and said second electrode forms with at least one of a third electrode and vehicle ground a third capacitor having a third capacitance;
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37. An occupant detection system, comprising
an electrode arrangement for being placed into the seat of an automotive vehicle, said electrode arrangement including a first electrode to emit an electric field into a detection region above said vehicle seat, a second electrode and an electric insulator layer sandwiched between said first and second electrodes; - wherein, during use of said occupant detection system, said first electrode forms with vehicle ground a first capacitor having a first capacitance, which is influenceable by an occupying item in said detection region through interaction of said occupying item with said electric field, said first electrode forms with said second electrode a second capacitor having a second capacitance and said second electrode forms with at least one of a third electrode and vehicle ground a third capacitor having a third capacitance;
an evaluation circuit operatively connected to said first and second electrodes, wherein said evaluation circuit is configured and arranged so as to determine, as a first occupancy state indicator, a measure of said first capacitance in a time interval during which it causes said first electrode to emit an electric field into said detection region and operates said second electrode as a driven shield for said first electrode;
wherein said evaluation circuit is further configured and arranged so as to measure fluctuations of at least one of said first, second and third capacitance, to determine a second occupancy state indicator through analysing a frequency spectrum of said measured fluctuations and to derive an occupancy state of said seat based on both said first and said second occupancy state indicators, i.e. on both said measured first capacitance and said frequency spectrum. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
- wherein, during use of said occupant detection system, said first electrode forms with vehicle ground a first capacitor having a first capacitance, which is influenceable by an occupying item in said detection region through interaction of said occupying item with said electric field, said first electrode forms with said second electrode a second capacitor having a second capacitance and said second electrode forms with at least one of a third electrode and vehicle ground a third capacitor having a third capacitance;
Specification