Occupant detection system and method of determining occupant

• US 20070182553A1
• Filed: 02/06/2007
• Published: 08/09/2007
• Est. Priority Date: 02/07/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kamizono, Tsutomu, Nishio, Eiichi
• Granted Patent: US 7,701,338 B2
• Time in Patent Office: Days
• US Class Current: 340/561
• CPC Class Codes: B60R 21/01534 using electromagneticwaves, e.g. infrared
• CPC Class Codes: B60R 21/01554 Seat position sensors
• CPC Class Codes: B60R 21/01556 Child-seat detection systems

Abstract

An occupant detection system for detecting an occupant on a seat of a vehicle includes an antenna electrode in a seat bottom of the seat, and an electronic unit connected to the antenna electrode and the vehicle. The electronic unit applies a load current to the antenna electrode so as to generate a weak electric field, and detects a potential current passing through the antenna electrode. The electronic unit detects an occupant based on an impedance and a phase difference, which are based on the load current and the potential current.

Claims

1. An occupant detection system for detecting an occupant on a seat of a vehicle, the system comprising:

an antenna electrode in a seat bottom of the seat; and

an electronic unit connected to the antenna electrode and the vehicle, wherein

the electronic unit applies a load current to the antenna electrode so as to generate a weak electric field, and detects a potential current passing through the antenna electrode, and

the electronic unit detects an occupant based on a first impedance and a first phase difference, which are based on the load current and the potential current.

2. The occupant detection system according to claim 1, wherein:

the electronic unit detects the occupant by comparing the first impedance and a threshold corresponding to the first phase difference.

3. The occupant detection system according to claim 1, wherein:

the antenna electrode includes a proximity electrode for a proximity detection in the seat bottom; and

the electronic unit detects the occupant based on a second impedance and a second phase difference of the proximity detection.

4. The occupant detection system according to claim 1, wherein:

the electronic unit includes a signal source for applying the load current; and

the potential current is measured in a shunt of the signal source.

5. An occupant detection system for detecting an occupant on a seat of a vehicle, the system comprising:

an antenna electrode in a seat bottom of the seat; and

an electronic unit connected to the antenna electrode and the vehicle, wherein

the electronic unit applies a load current to the antenna electrode so as to generate a weak electric field, and detects a potential current passing through the antenna electrode, and

the electronic unit detects an occupant based on a conductance and a susceptance of a first admittance, which is based on the load current and the potential current.

6. The occupant detection system according to claim 5, wherein:

the electronic unit detects the occupant by comparing the susceptance and a threshold corresponding to the conductance.

7. The occupant detection system according to claim 5, wherein:

the antenna electrode includes a proximity electrode for a proximity detection in the seat bottom; and

the electronic unit detects the occupant based on a second admittance of the proximity detection.

8. The occupant detection system according to claim 5, wherein:

the electronic unit includes a signal source for applying the load current; and

the potential current is measured in a shunt of the electronic unit.

9. A method of determining an occupant on a seat of a vehicle, the method comprising:

applying a load current to an antenna electrode in the seat so as to generate a weak electric field, wherein the load current is varied by the occupant;

detecting a potential current generated by the electric field, wherein the potential current is varied by the occupant;

calculating at least one of a set of an impedance and a phase difference, and a conductance and a susceptance of an admittance, based on the load current and the potential current; and

comparing the impedance and a threshold corresponding to the phase difference, or the susceptance and a threshold corresponding to the conductance.