Occupant sensor

• US 6,563,231 B1
• Filed: 12/29/1999
• Issued: 05/13/2003
• Est. Priority Date: 12/30/1998
• Status: Expired due to Term

• Current Assignee: Joyson Safety Systems Acquisition, LLC
• Original Assignee: Automotive Systems Laboratory, Incorporated (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Stanley, James G., McDonnell, Judson G., Stopper, Robert A. Jr.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/474,469
• Time in Patent Office: 1,231 Days
• Field of Search: 307/9.1, 307/10.1, 340/438, 340/457.1, 340/665, 340/666, 340/667, 280/734, 280/735
• US Class Current: 307/10.1
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60N 2/28 Seats readily mountable on, and dismountable from, existing seats or other parts of the vehicle
• CPC Class Codes: B60N 2/286 forward facing B60N2/2866 takes precedence
• CPC Class Codes: B60N 2/2863 backward facing
• CPC Class Codes: B60R 2021/0034 lying down
• CPC Class Codes: B60R 2021/0037 standing
• 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 21/01532 using electric or capacitive field sensors
• CPC Class Codes: B60R 21/01534 using electromagneticwaves, e.g. infrared
• CPC Class Codes: B60R 21/01536 using ultrasonic waves
• CPC Class Codes: B60R 21/01556 Child-seat detection systems
• CPC Class Codes: G01V 3/088 operating with electric fields G01V3/082 takes precedence

Abstract

An occupant sensor comprises an electric field sensor comprising a plurality of first electrodes mountable within a vehicle seat, wherein the plurality of first electrodes are disposed on a common surface and are non-overlapping with one another. The electric field sensor further comprises at least one second electrode, wherein the first and second electrodes are proximate to one another. A sensing circuit is operatively coupled to the first and second electrodes so as to control the level of capacitance between an occupant on said vehicle seat and the circuit ground. In a second aspect, the electric field sensor incorporates a lattice electrode with a ground plane. In a third aspect, the electric field sensor incorporates a receive electrode that receives a signal from a sensing electrode for purposes of mitigating the effects of a seat wetting condition.

Claims

1. An occupant sensor, comprising:

a. a first electric field sensor comprising;

(i) a plurality of first electrodes mountable within a vehicle seat, wherein said plurality of first electrodes are disposed on a common surface and are non-overlapping with one another; and

(ii) at least one second electrode, wherein said at least one second electrode is proximate to at least one said first electrode; and

b. a first sensing circuit operatively coupled to at least one said first electrode and to at least one second electrode, wherein said first sensing circuit applies a first applied signal to said at least one said first electrode, said first sensing circuit applies a second applied signal to said at least one said second electrode, said second applied signal is selected from the group consisting of a circuit ground, said first applied signal, a signal switched between a floating level and a circuit ground, and a potential between said first applied signal and said circuit ground, so as to control the level of capacitance between an occupant on said vehicle seat and said circuit ground, and said first sensing circuit generates a first signal responsive to at least one electric field influencing property of an object proximate to said first electric field sensor.

2. An occupant sensor as recited in claim 1, wherein at least one said second electrode is operatively coupled to said circuit ground.

3. An occupant sensor as recited in claim 1, wherein at least one said second electrode is disposed on said common surface.

4. An occupant sensor as recited in claim 1, wherein at least one said second electrode is non-overlapping with at least one said first electrode.

5. An occupant sensor as recited in claim 1, wherein at least one said second electrode overlaps at least one said first electrode.

6. An occupant sensor as recited in claim 1, wherein at least one said second electrode extends beyond at least one said first electrode.

7. An occupant sensor as recited in claim 6, wherein at least one said second electrode surrounds at least one said first electrode.

8. An occupant sensor as recited in claim 7, wherein at least one said second electrode surrounds at least one said first electrode on said common surface.

9. An occupant sensor as recited in claim 1, wherein said first electric field sensor further comprises at least one third electrode, wherein at least one said third electrode is proximate to at least one said second electrode and said at least one second electrode isolates at least one said first electrode from said at least one third electrode, and said first sensing circuit is operatively coupled to at least one of said at least one third electrode.

10. An occupant sensor as recited in claim 9, wherein at least one said third electrode is operatively coupled to said circuit ground.

11. An occupant sensor as recited in claim 9, wherein at least one said third electrode is disposed on said common surface.

12. An occupant sensor as recited in claim 9, wherein at least one said third electrode is non-overlapping with said at least one said first electrode.

13. An occupant sensor as recited in claim 9, wherein at least one said third electrode overlaps at least one said first electrode.

14. An occupant sensor as recited in claim 9, wherein at least one said third electrode is non-overlapping with at least one said second electrode.

15. An occupant sensor as recited in claim 9, wherein at least one said third electrode overlaps at least one said second electrode.

16. An occupant sensor as recited in claim 9, wherein at least one said third electrode extends beyond at least one said second electrode.

17. An occupant sensor as recited in claim 16, wherein at least one said third electrode surrounds at least one said second electrode.

18. An occupant sensor as recited in claim 17, wherein at least one said third electrode surrounds at least one said second electrode on said common surface.

19. An occupant sensor mountable in a vehicle seat, comprising:

a. a first electric field sensor comprising at least one first electrode mountable within a vehicle seat, wherein said at least one first electrode comprises a lattice, and said at least one first electrode comprising said lattice is connected to a terminal; and

b. a first sensing circuit operatively coupled to said terminal, wherein said first sensing circuit generates a first signal responsive to at least one electric field influencing property of an object proximate to said first electric field sensor.

20. An occupant sensor as recited in claim 19, wherein a surface area of said lattice is adapted so that a capacitance between an occupant on said vehicle seat and said first electrode is substantially less than a capacitance between said occupant and said circuit ground.

21. An occupant sensor mountable in a vehicle seat, comprising:

a. a first electric field sensor comprising at least one first electrode mountable within a vehicle seat, wherein said at least one first electrode comprises a lattice;

b. at least one second electrode, wherein at least one said second electrode is disposed within said lattice of said fist electrode; and

c. a first sensing circuit operatively coupled to at least one said first electrode wherein said first sensing circuit generates a first signal responsive to at least one electric field influencing property of an object proximate to said first electric field sensor.

22. An occupant sensor as recited in claim 21, wherein said at least one second electrode is isolated from said first electrode.

23. An occupant sensor as recited in claim 21, wherein said at least one second electrode is positioned relative to a seat bottom of said vehicle seat at a location proximate to an object selected from the group consisting of an infant seat on said vehicle seat, a child seat on said vehicle seat, and a booster seat on said vehicle seat.

24. An occupant sensor, comprising:

a. a first electric field sensor comprising;

(i) at least one first electrode mountable within a vehicle seat; and

(ii) at least one second electrode, wherein said at least one second electrode is isolated from said first electrode and is adapted to receive a first signal from said at least one first electrode; and

b. a first sensing circuit operatively coupled to at least one said first electrode and to said at least one second electrode wherein said first sensing circuit generates a second signal responsive to at least one electric field influencing property of an object proximate to said first electric field sensor.

25. An occupant sensor as recited in claim 24, wherein said second electrode is located within said vehicle seat.

26. An occupant sensor as recited in claim 24, wherein said second electrode capacitively couples to an occupant seated in said vehicle seat.

27. An occupant sensor as recited in claim 24, wherein at least one said first electrode and at least one said second electrode are on a common surface.

28. An occupant sensor as recited in claim 24, wherein a magnitude of said first signal is responsive to a wetness condition of said vehicle seat.

29. An occupant sensor as recited in claim 28, wherein said first sensing circuit measures said magnitude at a plurality of frequencies.

30. An occupant sensor as recited in claim 29, wherein said plurality of frequencies comprises first and second frequencies.

31. An occupant sensor as recited in claim 30, wherein said first frequency is less than 100 kilohertz and said second frequency is greater than 800 kilohertz.

32. An occupant sensor as recited in claim 30, wherein said magnitude at said first frequency is greater than said magnitude at said second frequency when said vehicle seat is wetted by a liquid, and said magnitude at said second frequency for an occupant in said vehicle seat is greater than said magnitude at said second frequency when an occupant is not seated in said vehicle seat.

33. An occupant sensor as recited in claim 28, wherein said first sensing circuit measures said magnitude at a plurality of different pulse widths.

34. An occupant sensor as recited in claim 28, wherein said magnitude of said first signal is responsive to the presence of an occupant on said vehicle seat.

35. An occupant sensor as recited in claim 24, wherein said first electric field sensor further comprises at least one third electrode, and at least one said third electrode is located between at least one said first electrode and at least one said second electrode.

36. An occupant sensor as recited in claim 35, wherein said at least one third electrode is operatively coupled to said circuit ground.