Occupant sensor and method for seat belt or other monitoring

• US 20080084290A1
• Filed: 10/12/2005
• Published: 04/10/2008
• Est. Priority Date: 10/12/2005
• Status: Active Grant

• Current Assignee: Nidec Elesys Americas Corporation (Nidec Corporation)
• Original Assignee: Elesys North America Incorporated (Nidec Corporation)
• Inventors: Hawkins, Eric T.
• Granted Patent: US 7,830,246 B2
• Time in Patent Office: Days
• US Class Current: 340/457.1
• CPC Class Codes: B60R 2021/01088 wireless
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/0152 using strain gauges
• CPC Class Codes: B60R 21/01546 using belt buckle sensors

Abstract

An occupant sensor with a complex arrangement of antenna or a simple single antenna determines a charge or discharge characteristic of the antenna. By determining the change in voltage or current of the antenna as a function of time, any occupant may be detected or characterized. The sensor restricts air bag activation or is used for another purpose. The same or different occupant sensor is used for seat belt warnings. A seat belt latch sensor determines whether a seat belt is being used. The occupant sensor determines whether the seat belt should be used. A driver is warned when a seat belt should be used by an occupant, but is not.

Claims

1. A sensor system for seat belt monitoring, the sensor system comprising:

a seat belt latch sensor;

an occupant sensor with an antenna; and

a processor operable to generate a seat belt warning in response to detection of an occupant by the occupant sensor and detection of lack of seat belt latching by the seat belt latch sensor.

2. The sensor system of claim 1 wherein the occupant sensor comprises an electric field or capacitive sensor.

3. The sensor system of claim 2 wherein the antenna is on flexible circuit material.

4. The sensor system of claim 1 wherein the antenna is on or in a seat.

5. The sensor system of claim 4 wherein the antenna is adjacent a seating surface on a base of the seat.

6. The sensor system of claim 1 wherein the antenna comprises an only single antenna of the occupant sensor.

7. The sensor system of claim 2 wherein the occupant sensor comprises an occupant detection circuit, the occupant detection circuit operable to detect the occupant as a function of a response of the antenna to a change in voltage or current.

8. The sensor system of claim 7 wherein the change in voltage or current is a change in discharge voltage or current.

9. The sensor system of claim 2 wherein the occupant sensor comprises a waveform generator operable to apply a gradually increasing voltage or current magnitude to the antenna and comprises an occupant detection circuit operable to integrate a voltage or current discharge.

10. The sensor system of claim 1 wherein the occupant sensing system is operable to distinguish between occupants of at least two different sizes, the processor operable to generate the seat belt warning for one and not the other of the at least two different sizes.

11. A method for seat belt monitoring, the method comprising:

detecting whether a seat belt is latched;

detecting whether an occupant is present with an electric field; and

generating a seat belt warning if the seat belt is not latched and an occupant is present.

12. The method of claim 11 wherein detecting whether the seat belt is latched comprises detecting with a seat belt sensor.

13. The method of claim 11 detecting with the electric field comprises detecting with an antenna on or in a seat.

14. The method of claim 13 wherein detecting with the antenna comprises detecting with the antenna adjacent a seating surface on a base of the seat.

15. The method of claim 13 wherein the antenna is an only antenna for detecting the occupant of a seating area.

16. The method of claim 11 wherein detecting whether the occupant is present comprises measuring a change in voltage or current.

17. The method of claim 16 wherein measuring the change in voltage or current comprises measuring a discharge response of an antenna.

18. The method of claim 11 wherein detecting whether the occupant is present comprises applying a gradually increasing voltage magnitude to an antenna until the antenna is fully charged, removing the voltage source and measuring a voltage discharge characteristic of the antenna.

19. The method of claim 11 wherein detecting whether the occupant is present comprises distinguishing between at least two size ranges of occupants, and wherein generating the seat belt warning comprises generating the seat belt for one of the size ranges and not for another of the size ranges.

20. An occupant sensor for detecting an occupant or characteristic, the occupant sensor comprising:

an antenna positioned by an occupant space;

a voltage or current source connected with the antenna; and

a measurement circuit operable to measure a response on the antenna as a function of time to a first change in the voltage or current supplied by the voltage or current source.

21. The occupant sensor of claim 20 further comprising:

a processor operable to characterize the occupant as a function of the response.

22. The occupant sensor of claim 20 wherein the antenna comprises a flexible circuit material in a seat.

23. The occupant sensor of claim 20 wherein the antenna, voltage or current source and measurement circuit comprises a flexible circuit.

24. The occupant sensor of claim 20 wherein the antenna is on or in a base portion of a vehicle seat adjacent the occupant space and a back of the vehicle seat.

25. The occupant sensor of claim 20 wherein the response is a second change in voltage or current on the antenna as a function of time

26. The occupant sensor of claim 25 wherein the second change in voltage or current on the antenna comprises a discharge of the antenna.

27. The occupant sensor of claim 25 wherein the voltage or current source is operable to repeat the first change, and wherein the measurement circuit is operable to sample the second change over repetitions of the first change.

28. The occupant sensor of claim 25 wherein the measurement circuit is operable to integrate the second change as a function of time.

29. The occupant sensor of claim 20 wherein the voltage or current source is operable to apply a gradually increasing voltage magnitude to the antenna and more rapidly discharge the voltage, and wherein the measurement circuit is operable to measure a voltage discharge characteristic of the antenna.

30. The occupant sensor of claim 21 wherein the processor is operable to distinguish between at least two size ranges of occupants.

31. The occupant sensor of claim 21 wherein the processor is operable to generate a seat belt warning as a function of the characterization.

32. A method for sensing an occupant, the method comprising:

applying a change in voltage or current to an antenna adjacent an occupant space;

measuring a response as a function of time to the change of the voltage or current by the antenna; and

classifying any occupant as a function of the response.

33. The method of claim 32 wherein applying and measuring comprise applying and measuring with the antenna in a vehicle seat.

34. The method of claim 32 wherein measuring the response comprises measuring a voltage or current on the antenna as a function of time.

35. The method of claim 32 wherein applying the change comprises reducing the voltage or current applied from a waveform generator and wherein measuring the response comprises measuring a discharge of the antenna.

36. The method of claim 32 further comprising repeating application of the change, wherein measuring comprises sampling the response over repetitions of the change.

37. The method of claim 32 wherein measuring comprises integrating the response as a function of time.

38. The method of claim 32 further comprising:

charging the antenna gradually;

wherein applying comprises more rapidly discharging the antenna, and wherein measuring comprises measuring a voltage discharge characteristic of the antenna.

39. The method of claim 32 wherein classifying comprises distinguishing between at least two size ranges of occupants.

40. The method of claim 32 further comprising:

generating a seat belt warning as a function of the classification.