System and method for detecting seat occupancy in a vehicle

• US 7,298,262 B2
• Filed: 11/18/2003
• Issued: 11/20/2007
• Est. Priority Date: 11/20/2002
• Status: Expired due to Fees

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Hofbeck, Klaus, Rosel, Birgit
• Primary Examiner(s): La; Anh V.
• Application Number:
  US10/536,041
• Publication Number:
  US 20060061470A1
• Time in Patent Office: 1,463 Days
• Field of Search: 340/436, 340/438, 340/561, 340/5.61, 340/5.72, 340/553, 340/501, 340/541, 340/667, 340/562, 280/734, 280/735, 701 45- 47, 342/72, 180/271, 180/273, 180/274
• US Class Current: 340/553
• CPC Class Codes: B60R 21/01534 using electromagneticwaves, e.g. infrared

Abstract

A system for determining seat occupancy in a motor vehicle includes a microwave transmitter, a microwave receiver and preferably a reflector. If a person is between those appliances, the microwave radiation is attenuated. The reflector can be a backscattering device, such that the radiation received by the receiver is unequivocally associated with the reflector. Furthermore or alternatively, the transit time of the microwaves can be measured, to be subsequently processed in combination with an analysis of the seated position of passengers. In preferred embodiments, the microwave radiation diffraction properties around an object are also used to obtain the seated position of passengers. The determination of a seat occupancy and optionally of seat occupancy mode can be advantageously used for locking or on the other hand releasing an airbag.

Claims

1. A system for determining seat occupancy in a vehicle, comprising:

at least one microwave transmitter, a plurality of reflectors stationarily disposed in predetermined locations at a seat of the vehicle, and at least one microwave receiver, commonly arranged;

to define between said microwave transmitter and said microwave receiver a radiation path divided into at least one first radiation path and at least one second radiation path;

wherein microwave radiation emitted by said microwave transmitter can reach at least one of said reflectors along the at least one first radiation path when the seat is unoccupied;

wherein the microwave radiation, after reflection by said at least one reflector can reach said microwave receiver via the at least one second radiation path;

wherein, depending on the seat occupancy, an object may be located in at least one of the first radiation path and the second radiation path and the radiation received by the microwave receiver may be influenced in dependence on the seat occupancy; and

wherein said reflectors are modulating backscattering devices.

2. The system according to claim 1, wherein said at least one microwave transmitter and said at least one microwave receiver are disposed spatially separate from one another.

3. The system according to claim 1, wherein:

said at least one microwave transmitter and said at least one microwave receiver are implemented in at least one microwave transmitting and receiving device comprising a transmitting and receiving antenna; and

the at least one first radiation path and the at least one second radiation path are identical.

4. The system according to claim 1, which comprises a control unit configured to selectively trigger, block, or enable functions in the vehicle depending on the radiation received by said microwave receiver.

5. The system according to claim 1, wherein said reflectors are formed of electrically conductive foil.

6. The system according to claim 1, wherein said reflectors are backscatter devices selected from the group consisting of passive devices, semi-passive devices, semi-active devices, and active devices.

7. The system according to claim 1, wherein said at least one microwave transmitter and/or said at least one microwave receiver are components of an access control and ignition system of the vehicle.

8. The system according to claim 1, wherein the signals received by said microwave receiver are processed for evaluation with means used in an access control and ignition system installed in the vehicle.

9. The system according to claim 1, wherein said reflectors are differently modulating backscattering devices.

10. The system according to claim 1, wherein the first and second radiation paths follow a straight line.

11. The system according to claim 1, wherein the at least one first radiation path and/or the at least one second radiation path follow a roundabout route.

12. The system according to claim 1, wherein:

a position of the object in the radiation path influences an intensity of a signal received by said microwave receiver due to a diffraction of microwaves about the object; and

the intensity of the received signal provides information about the position of the object.

13. A method of determining seat occupancy in a vehicle, which comprises the following steps:

defining a radiation path with at least one first radiation path and at least one second radiation path;

emitting microwave radiation to propagate along the at least one first radiation path;

reflecting the microwave radiation from a defined location at the seat of the vehicle with a modulating backscattering process to form reflected microwave radiation, and causing the reflected radiation to propagate along the at least one second radiation path;

receiving the reflected microwave radiation; and

determining a seat occupancy and deducing whether or not an object is located in at least one of the first radiation path and the second radiation path, where the radiation received by a microwave receiver is influenced depending on the seat occupancy.

14. The method according to claim 13, which comprises placing the at least one microwave transmitter and the at least one microwave receiver spatially separate from one another.

15. The method according to claim 13, wherein the at least one first radiation path and the at least one second radiation path are identical.

16. The method according to claim 13, which comprises selectively triggering, locking, or releasing functions in the vehicle in dependence on the radiation received.

17. The method according to claim 13, which comprises reflecting the radiation with an electrically conductive foil.

18. The method according to claim 13, which comprises implementing the backscattering process with a passive, a semi-active, a semi-passive, or an active backscattering device.

19. The method according to claim 13, which comprises emitting and/or receiving with an access control and ignition control system installed in the vehicle.

20. The method according to claim 13, which comprises carrying out or supporting an evaluation of the received signals within a framework of an access control and ignition system installed in the vehicle.

21. The method according to claim 13, which comprises effecting the backscattering process with a plurality of differently modulating backscattering devices.

22. The method according to claim 13, wherein the at least one first radiation path and/or the at least one second radiation path follow a straight-line route.

23. The method according to claim 13, wherein the at least one first radiation path and/or the at least one second radiation path follow a roundabout diversion route.

24. The method according to claim 13, wherein a position of the object in the radiation path influences an intensity of a received signal due to a diffraction of microwaves;

and the method comprises deducing information about the position of the object from the intensity of the received signal.