Device for detecting the presence of a user by a vehicle

• US 9,082,240 B2
• Filed: 09/18/2008
• Issued: 07/14/2015
• Est. Priority Date: 10/03/2007
• Status: Active Grant

• Current Assignee: Valeo Securite Habitacle (Valeo SE)
• Original Assignee: Valeo Securite Habitacle (Valeo SE)
• Inventors: Cara, Herve, Violleau, Stephane, Bocage, Frederic, Nguyen, Van-Quyn
• Primary Examiner(s): Assouad, Patrick
• Assistant Examiner(s): BROWN, LAMARR A
• Application Number:
  US12/681,268
• Publication Number:
  US 20100253141A1
• Time in Patent Office: 2,490 Days
• Field of Search: 324658-690, 345/174, 345/173, 178/18.06
• US Class Current: 1/1
• CPC Class Codes: E05B 81/77 comprising sensors detecting the presence of the hand of a user
• CPC Class Codes: E05B 81/78 as part of a hands-free locking or unlocking operation
• CPC Class Codes: G07C 2009/00373 whereby the wake-up circuit is situated in the lock
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2209/65 using means for sensing the user's hand
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks
• CPC Class Codes: H01Q 1/3241 particular used in keyless entry systems
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe

Abstract

The invention relates to a device for detecting (CAPT) the presence of an object, that comprises at least one detection member (EA, EB) to which is associated a physical value that varies based on the environment in which said detection member (EA, EB) is located. The invention is characterised in that the physical value provides a variable reference level corresponding to the absence of an object and in that it further comprises a saving device (LOG IC) for saving, upon the emission of a low-frequency signal, a value of the reference level measured before the emission of said low-frequency signal.

Claims

1. A device for detecting the presence of an object, the device comprising:

at least one detection member which has an associated physical quantity that varies according to an environment in which said at least one detection member is located, wherein, in the absence of the object, a variable reference level associated with the physical quantity is generated; and

a saving device for;

periodically saving the variable reference level at a predetermined timing;

measuring the physical quantity associated with the at least one detection member during the emission of a low-frequency signal; and

comparing the physical quantity to the saved value of the reference level obtained prior to the emission of the low-frequency signal,

wherein the saving device facilitates;

suspending the periodic saving of the variable reference level as soon as presence of an object is detected or as soon as a low-frequency signal is emitted, and

resuming the periodic saving of the variable reference level after the emission of the low-frequency signal, when the presence of the object is no longer detected, or after a set period of time.

2. The detection device as claimed in claim 1, wherein the physical quantity is a capacitance.

3. The detection device as claimed in claim 1, wherein the physical quantity is a light flux.

4. The detection device as claimed in claim 1, further comprising:

a low-frequency detection element configured to detect the start of emission of a low-frequency signal.

5. The detection device as claimed claim 1, wherein the device is powered by a power supply common to an antenna for emitting a low-frequency signal.

6. The detection device as claimed in claim 1, wherein the device is powered, during the emission of a low-frequency signal, by an antenna excitation voltage, wherein said antenna is used to emit the low-frequency signal.

7. The detection device as claimed in claim 4, wherein the device is powered by an input voltage and further comprises an input capacitor for storing energy from the input voltage.

8. The detection device as claimed in claim 4, further comprising:

measuring means associated with the at least one detection member for generating an output electrical quantity when said detection member detects the presence of an object.

9. The detection device as claimed in claim 8, further:

inhibition means for inhibiting the measuring means so that the measuring means no longer generates the output electrical quantity.

10. The detection device as claimed in claim 8, wherein the measuring means comprise a current generator associated with each of the at least one detection member, and wherein the output electrical quantity is a generator output current.

11. The detection device as claimed in claim 8, wherein the measuring means comprise a single current generator associated with the at least one detection member, and wherein the output electrical quantity is a generator output current.

12. The detection device as claimed in claim 8, wherein the measuring means comprise a switch connected to ground associated with each of the at least one detection member, and wherein the output electrical quantity is a generator output voltage.

13. The detection device as claimed in claim 8, wherein the measuring means comprise a single switch connected to ground associated with the at least one detection member, and wherein the output electrical quantity is a generator output voltage.

14. The detection device as claimed in claim 9, wherein the low-frequency detection element comprises a comparator for detecting a break in a power supply to said detection device.

15. The detection device as claimed in claim 14, wherein the comparator compares a voltage measured at terminals of the input capacitor with an input voltage associated with the power supply.

16. The detection device as claimed in claim 15, wherein the inhibition means is configured to inhibit measuring means when a break in the power supply to said detection device is detected.

17. The detection device as claimed in claim 16, wherein the inhibition means is configured to inhibit measuring means when the input voltage is less than the voltage measured at the terminals of the input capacitor minus a first threshold.

18. The detection device as claimed in claim 17, wherein the saving device saves the value of the reference level measured before the emission of a low-frequency signal, until the input voltage is greater than the voltage at the terminals of the input capacitor minus a second threshold.

19. The detection device as claimed in claim 15, further comprising:

a first time filter for measuring a duration of the break in power supply and allowing the value of the reference level measured before the emission of the low-frequency signal to be saved only if said duration is greater than a first predetermined time.

20. The detection device as claimed in claim 19, further comprising:

a second time filter for releasing the saved value of the reference level measured before the emission of the low-frequency signal, when the input voltage is equal to the voltage at the terminals of the input capacitor for a duration greater than a second predetermined time.

21. The detection device as claimed in claim 9, wherein the low-frequency detection element comprises a comparator for detecting a resonant signal representative of the emission of a low-frequency signal.

22. The detection device as claimed in claim 21, wherein the low-frequency detection element comprises a peak level detector to allow for a peak level detection from the resonant signal.

23. The detection device as claimed in claim 22, wherein the comparator compares a resonant voltage generated by an antenna and a reference voltage, wherein said antenna emits the low-frequency signal.

24. The detection device as claimed in claim 22, wherein the resonant signal is an image voltage of a resonant current circulating in an antenna configured to emit the low-frequency signal.

25. The detection device as claimed in claim 24, wherein the inhibition means inhibit measuring means when the emission of a low-frequency signal is detected.

26. The detection device as claimed in claim 9, wherein the low-frequency detection element comprises a comparator for detecting a pulsed input signal representative of the emission of a low-frequency signal.

27. The detection device as claimed in claim 26, wherein the low-frequency detection element comprises a peak level detector to allow for a peak level detection from the pulsed input signal.

28. The detection device as claimed in claim 26, wherein the low-frequency detection element also comprises an additional capacitor.

29. The detection device as claimed in claim 26, wherein the low-frequency detection element also comprises an additional resistor that is associated with a capacitor, and which allows for the detection to be restarted after the emission of a low-frequency signal.

30. The detection device as claimed in claim 27, wherein the peak level detector comprises a time constant defined to:

minimize the time to detect the emission of a low-frequency signal by controlling the charging time of said peak level detector.

31. The detection device as claimed in claim 27, wherein the peak level detector comprises a time constant defined to:

avoid transient spurious disturbance peaks on the pulsed input signal when charging said peak level detector.

35. The detection device as claimed in claim 1, wherein resuming the periodic saving of the variable reference level occurs only when the presence of the object is no longer detected.

36. The detection device as claimed in claim 1, wherein the resuming of the periodic saving of the variable reference level occurs only after the set period of time, even in the presence of the object.

32. A unit for detecting the presence of an object, comprising:

a detection device comprising;

at least one detection member which has an associated physical quantity that varies according to an environment in which said at least one detection member is located, wherein, in the absence of the object, a variable reference level associated with the physical quantity is generated;

a saving device for periodically saving a value of the variable reference level at a predetermined timing,

wherein the saving device measures the physical quantity associated with the at least one detection member during the emission of a low-frequency signal; and

compares the physical quantity to the saved value of the reference level obtained prior to the emission of the low-frequency signal;

wherein the saving device facilitates;

suspending the periodic saving of the variable reference level as soon as presence of an object is detected or as soon as a low-frequency signal is emitted, and

resuming the periodic saving of the variable reference level after the emission of the low-frequency signal;

an antenna for emitting the low-frequency signal.

33. A method for detecting the presence of an object by means of a physical quantity, associated with a detection member, which varies according to an environment in which said detection member is located, the method comprising:

periodically saving a variable reference level of the physical quantity corresponding to the absence of the object at a predetermined timing;

measuring the physical quantity associated with the at least one detection member during the emission of a low-frequency signal; and

comparing the physical quantity to the saved value of the reference level obtained prior to the emission of the low-frequency signal,

wherein the saving device facilitates;

suspending the periodic saving of the variable reference level as soon as presence of an object is detected or as soon as a low-frequency signal is emitted, and

resuming the periodic saving of the variable reference level after the emission of the low-frequency signal, when the presence of the object is no longer detected, or after a set period of time.

34. A computer program product comprising one or more sequences of instructions that are executed by an information processing unit, the execution of said sequences of instructions resulting in the execution of a method for detecting the presence of an object by means of a physical quantity, associated with a detection member, which varies according to an environment in which said detection member is located, the method comprising:

periodically saving a variable reference level of the physical quantity corresponding to the absence of the object at a predetermined timing; and

measuring the physical quantity associated with the at least one detection member during the emission of a low-frequency signal; and

comparing the physical quantity to the saved value of the reference level obtained prior to the emission of a low-frequency signal,

wherein the saving device facilitates;

suspending the periodic saving of the variable reference level as soon as presence of an object is detected or as soon as a low-frequency signal is emitted, and

resuming the periodic saving of the variable reference level after the emission of the low-frequency signal, when the presence of the object is no longer detected, or after a set period of time.