Method and apparatus for detecting the utilization of a vehicle safety belt

• US 3,874,474 A
• Filed: 11/12/1973
• Issued: 04/01/1975
• Est. Priority Date: 11/12/1973
• Status: Expired due to Term

• Current Assignee: Norman G. Quantz
• Original Assignee: Norman G. Quantz
• Inventors: Quantz, Norman G.
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Siemens, Terrance L.
• Application Number:
  US05/414,867
• Time in Patent Office: 505 Days
• Field of Search: 180/82C 280/15SB 200/DIG.1 307/1SB 340/52E,278
• US Class Current: 180/270
• CPC Class Codes: B60R 2022/4816 for sensing locking of buckle
• CPC Class Codes: B60R 2022/4858 for sensing pressure on seat
• CPC Class Codes: B60R 2022/4891 preventing use of the vehicle when the seatbelt is not fastened
• CPC Class Codes: B60R 22/48 Control systems, alarms, or interlock systems, for the correct application of the belt or harness

Abstract

An apparatus for detecting the proper utilization of a safety belt of a vehicle by a vehicle occupant which includes a high frequency oscillator and a sensing foil connected to the oscillator which is positioned in the seat of the vehicle. The oscillator is in a non-oscillating condition prior to the presence of the occupant in the seat, begins to oscillate when the occupant is positioned in the seat due to capacitive interaction between the occupant and the sensing foil in the seat, and stops oscillating upon buckling of the seat belt. Advantageously, the oscillator of the present apparatus has a power supply input impedance of large value so that the apparatus may be connected to the vehicle battery even when the ignition switch is turned off without detrimentally-high battery drain. Consequently, occupants who occupy the seat and fasten the safety belt prior to the closing of the ignition switch will be given credit for such action. This high power supply input impedance which results in low power drain is accomplished without sacrificing the efficiency and detection capability of the system and without sacrificing the protection of the system against voltage transients which may occur during periods of momentary heavy loads such as during the starting of the vehicle.

Claims

1. In a vehicle for an occupant having an ignition switch and a power supply including a battery, an apparatus comprising:

conductor means positioned to be proximate said occupant when said occupant is in a predetermined relationship with said vehicle;

oscillating means connected to said conductor means for supplying oscillating electrical energy to said conductor means and for supplying an output signal when said occupant is in said predetermined relationship with said vehicle; and

input means for said oscillating means connecting said oscillating means to said power supply so that said oscillating means remains connected to said battery when said ignition switch is opened to provide an indication when said occupant is in said predetermined relationship with said vehicle even when said ignition switch is opened, said input means providing a relatively high input impedance to said oscillating means from said supply means for providing sufficient power to said oscillating means for operation of said oscillating means but limiting said power to said oscillating means to a level which allows operation of said oscillating means for long periods of time without excessive drain on said battery.

2. An apparatus according to claim 1 wherein said vehicle includes a seat and wherein said conductor means is associated with said seat.

3. An apparatus according to claim 1 wherein said vehicle includes a safety belt and wherein said conductor means is associated with said safety belt.

4. An apparatus according to claim 1 wherein said input means includes resistor means connected intermediate said oscillating means and said power supply which has a relatively high value of resistance for providing said relatively high input impedance.

5. An apparatus according to claim 1 wherein said conductor means provides a capacitance for said oscillating means and wherein said capacitance is changed from a first value when said occupant is not in said predetermined relationship with said vehicle to a second value when said occupant is in said predetermined relationship with said vehicle with said change in capacitance influencing the oscillation of said oscillating means.

6. An apparatus according to claim 5 wherein said change in capacitance causes said oscillating means to oscillate.

7. An apparatus according to claim 1 wherein said oscillating means includes a transistor and bias means for said transistor for biasing said transistor partly on when said occupant is not in said predetermined relationship with said vehicle, and wherein said conductor means provides a capacitance for said bias means which changes from a first value of capacitance when said occupant is not in said predetermined relationship with said vehicle to a second valUe when said occupant is in said predetermined relationship with said vehicle for causing said transistor to oscillate.

8. An apparatus according to claim 1 wherein said input impedance is at least approximately 33 Kohms.

9. An apparatus according to claim 1 wherein said input means provides a sufficiently high input impedance so that said power provided to said oscillating means is less than about 4 milliamps.

10. An apparatus according to claim 9 wherein said input impedance is at least approximately 33 Kohms.

11. In a vehicle for an occupant having an ignition switch and a power supply including a battery, an apparatus, comprising:

conductor means positioned to be proximate said occupant when said occupant is in a predetermined relationship with said vehicle;

oscillating means connected to said conductor means for supplying oscillating electrical energy to said conductor means and for supplying an output signal when said occupant is in said predetermined relationship with said vehicle; and

input means for said oscillating means including capacitor means for protecting said oscillating means from current or potential transients from said power supply being connected to receive and dissipate said transients, said input means further including impedance means connecting said oscillating means to said power supply so that said oscillating means remains connected to said battery when said ignition switch is opened to provide an indication when said occupant is in said predetermined relationship with said vehicle even when said ignition switch is opened, said impedance means providing a relatively high input impedance to said oscillating means from said supply means for providing sufficient power to said oscillating means for operation of said oscillating means but limiting said power to said oscillating means to a level which allows operation of said oscillating means for long periods of time without excessive drain on said battery.

12. An apparatus according to claim 11 wherein said vehicle includes a seat and wherein said conductor means is associated with said seat.

13. An apparatus according to claim 11 wherein said vehicle includes a safety belt and wherein said conductor means is associated with said safety belt.

14. An apparatus according to claim 11 wherein said vehicle has ground means providing a ground potential and wherein said capacitor means is connected between said power supply and said ground means.

15. An apparatus according to claim 11 wherein said input impedance is at least approximately 33 Kohms.

16. An apparatus according to claim 11 wherein said input means provides a sufficiently high input impedance so that said power provided to said oscillating means is less than about 4 milliamps.

17. An apparatus according to claim 16 wherein said input impedance is at least approximately 33 Kohms.

18. In a vehicle for an occupant having safety belt means adapted to be secured for restraining said occupant, an apparatus comprising first conductor means positioned to be proximate said occupant when said occupant is in a predetermined relationship with said vehicle;

oscillating means connected to said first conductor means for providing oscillating electrical energy when said occupant is in said predetermined relationship with said vehicle;

output means for receiving at least a portion of said oscillating electrical energy and being responsive to said received portion of said oscillating electrical energy for supplying an output signal indicating said occupant is in said predetermined relationship with said vehicle; and

second conductor means associated with said safety belt means for diverting said oscillating electrical energy away from said output means when said safety belt means is secured for restraining said occupant to reduce the oscillating electrical energy received by said output means sufficiently to terminate said output sIgnal.

19. An apparatus according to claim 18 wherein said vehicle includes a seat and wherein said first conductor means is associated with said seat.

20. An apparatus according to claim 18 wherein said vehicle includes a safety belt and wherein said second conductor means is associated with said safety belt.

21. An apparatus according to claim 18 wherein said vehicle has a power supply and said oscillating means has input means which includes resistor means connected intermediate said oscillating means and said power supply which has a relatively high value of resistance for providing a relatively high input impedance to said oscillating means.

22. An apparatus according to claim 21 wherein said first conductor means provides a capacitance for said oscillating means and wherein said capacitance is changed from a first value when said occupant is not in said predetermined relationship with said vehicle to a second value when said occupant is in said predetermined relationship with said vehicle with said change in capacitance influencing the oscillation of said oscillating means.

23. An apparatus according to claim 22 wherein said change in capacitance causes said oscillating means to oscillate.

24. An apparatus according to claim 18 wherein said oscillating means includes a transistor and bias means for said transistor for biasing said transistor partly on when said occupant is not in said predetermined relationship with said vehicle, and wherein said conductor means provides a capacitance for said bias means which changes from a first value of capacitance when said occupant is not in said predetermined relationship with said vehicle to a second value when said occupant is in said predetermined relationship with said vehicle for causing said transistor to oscillate.

25. An apparatus according to claim 18 wherein said vehicle includes ground means providing a ground potential and wherein said second conductor is operative to divert said oscillating electrical energy to said ground means when said safety belt means is secured.

26. An apparatus according to claim 12 further including switch means associated with said second conductor means which is closed when said safety belt means is secured.

27. An apparatus according to claim 26 wherein said vehicle includes ground means providing a ground potential and wherein said second conductor means is operative to divert said oscillating electrical energy to said ground means through said switch means when said safety belt means is secured.