Passenger detection system and method

• US 6,329,913 B1
• Filed: 10/06/1999
• Issued: 12/11/2001
• Est. Priority Date: 10/05/1999
• Status: Expired due to Term

• Current Assignee: Nidec Elesys Americas Corporation (Nidec Corporation)
• Original Assignee: NEC Technologies Incorporated
• Inventors: Shinmura, Masanobu, Shieh, Shiuh-An, Kirksey, James Frederick
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US09/413,099
• Time in Patent Office: 797 Days
• Field of Search: 340/425.5, 340/436, 340/438, 340/551, 340/552, 340/561, 340/562, 340/573.1, 180/271, 180/273, 280/728.1, 280/728.2, 280/734, 280/735
• US Class Current: 340/561
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors

Abstract

A passenger detection system is provided. The passenger detection system utilizes an oscillation circuit that causes an antenna electrode to emit an electric field that is disrupted by the electrical characteristics of an object placed on the seat. This disruption alters the current and phase of the signal in the antenna electrode. By comparing the current flowing in the antenna electrode and/or the difference between the phase of the signal in the antenna electrode and the oscillation circuit output signal with predetermined threshold values, it is possible to detect the presence of a passenger in a reliable and inexpensive manner.

Claims

1. A vehicle passenger detection system for sensing a characteristic of a passenger in a passenger seating area, the system comprising:

a vehicle seat having an outer surface adjacent to the passenger seating area;

a first electrode connected with a first portion of the vehicle seat a first distance from the outer surface;

a second electrode connected with the first portion of the vehicle seat at a second, different distance from the outer surface, the second electrode adjacent to the first electrode; and

a controller connected to receive data from both of the first and second electrodes.

2. The system of claim 1 wherein the first portion comprises a seat base.

3. The system of claim 1 further comprising at least third and fourth electrodes connected with the first portion at the first and second distances, respectively.

4. The system of claim 1 wherein the controller is operative to determine the characteristic of the passenger as a function of data from the first and second electrodes.

5. The system of claim 4 wherein the controller is operative to determine the characteristic as a function of a difference between the first and second distances.

6. The system of claim 5 wherein the difference between the first and second distances is operable to vary in response to the passenger.

7. The system of claim 1 further comprising an insulator between the first and second electrodes.

8. The system of claim 1 further comprising an AC source operable to be coupled with at least one of the first and second electrodes, an electric field generated in response to coupling.

9. The system of claim 8 further comprising a detector operable to be coupled with the second electrode to receive information wherein the first electrode is operable to be coupled to the AC source to transmit.

10. The system of claim 8 further comprising a detector operable to be coupled with the first electrode wherein the AC source is operable to be coupled with the first electrode, the detector for measuring a loading current.

11. The system of claim 4 wherein the controller is operable to determine the presence of a child.

12. The system of claim 4 wherein the controller is operative to determine the characteristic as a function of time wherein classification of the characteristic can change only after a time period.

13. The system of claim 11 wherein the controller is operative to lock a classification of the characteristic as the child.

14. The system of claim 4 wherein the controller is operative to more easily change a classification from adult to child than from child to adult.

15. The system of claim 4 wherein the controller is operative to determine the characteristic in response to an average of the data as a function of time.

16. The system of claim 1 further comprising first and second shielded cables operatively connected with the first and second electrodes respectively.

17. A vehicle passenger detection method for sensing a characteristic of a passenger in a passenger seating area, the method comprising the acts of:

(a) generating an electric field with at least one of (1) a first electrode connected with a first portion of a vehicle seat a first distance from an outer surface of the vehicle seat and (2) a second electrode connected with the first portion of the vehicle seat a second, different distance from the outer surface, the second electrode adjacent to the first electrode;

(b) measuring a signal from the first electrode; and

(c) measuring a signal from the second electrode.

18. The method of claim 17 wherein (a) comprises generating from the first portion comprising a seat base.

19. The method of claim 17 further comprising:

(d) sequentially generating electric fields from at least third and fourth electrodes connected with the first portion at the first and second distances, respectively.

20. The method of claim 17 further comprising:

(d) determining the characteristic of the passenger as a function of (b) and (c).

21. The method of claim 20 wherein (d) comprises determining the characteristic as a function of a difference between the first and second distances.

22. The method of claim 21 further comprising:

(e) varying the difference between the first and second distances in response to the passenger.

23. The method of claim 17 wherein (a) comprises coupling an AC source with the at least one electrode.

24. The method of claim 23 wherein (a) comprises generating the electric field with the first electrode and (b) is performed at a different time than (a).

25. The method of claim 23 wherein (a) comprises generating the electric field with the first electrode and (b) is performed at a same time as (a).

26. The method of claim 20 wherein (d) comprises determining the presence of a child in response to (b) and (c).

27. The method of claim 20 wherein (d) comprises repeatedly determining the characteristic;

and

further comprising;

(e) limiting a change (d) in response to a change in one of (b) and (c) as a function of a time period.

28. The method of claim 26 further comprising:

(e) locking a classification of the characteristic as the child.

29. The method of claim 20 further comprising:

(e) changing more easily a classification from adult to child than from child to adult.

30. The method of claim 20 further comprising:

(e) averaging the measurements of (b) and (c) as a function of time.

31. A vehicle passenger detection system for sensing a characteristic of a passenger in a passenger seating area, the system comprising:

a plurality of electrodes arranged in at least two layers, each layer a different distance from the passenger seating area;

a controller operable to receive information from the plurality of electrodes and operable to determine the characteristic as a function of the information and the different distance.

32. The system of claim 31 further comprising an insulator wherein a first layer of electrodes is positioned on a first side of the insulator and a second layer of electrodes is positioned on a second, different side of the insulator.