Deactivator using resonant recharge

• US 7,106,200 B2
• Filed: 06/10/2004
• Issued: 09/12/2006
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Sensormatic Electronics LLC (Johnson Controls International plc)
• Original Assignee: Sensormatic Electronics Corporation (Johnson Controls International plc)
• Inventors: Drew, Douglas A., Hall, Stewart E.
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US10/865,020
• Publication Number:
  US 20050275507A1
• Time in Patent Office: 824 Days
• Field of Search: 340/572.3, 340/572.5, 340/572.7
• US Class Current: 340/572.3
• CPC Class Codes: G08B 13/2411 Tag deactivation

Abstract

A method and apparatus to perform resonant recharge transfers energy from an AC power source (e.g., a power line) or from a DC power source or from bulk capacitors to a deactivation capacitor. The resonant recharge occurs faster than conventional techniques without the need for dissipative current limiting control elements. Through the employment of a resonant approach, the natural impedance of the resonant circuit limits the current without high resistive losses of a limiting resistor or other current limiting regulator. This may increase the efficiency of the recharge circuit and may charge the deactivation capacitor to a voltage that is higher than the voltage of the power source.

Claims

1. An apparatus, comprising:

a power source; and

a deactivator to connect to said power source, said deactivator having a deactivation antenna coil and an energy storage capacitor, said deactivator to use an impedance formed by a resonant impedance of said deactivator antenna coil and a capacitance of said energy storage capacitor to limit an amplitude and duration of an input charge current pulse derived from said power source.

2. The apparatus of claim 1, wherein said power source is a direct current power source.

3. The apparatus of claim 2, wherein said direct current power source comprises at least one of a direct current power supply, a direct current power supply with at least one capacitor, a bank of at least one battery, a bank of at least one battery and at least one capacitor, and a bank of at least one charged capacitor.

4. The apparatus of claim 1, wherein said power source is an alternating current power source.

5. The apparatus of claim 4, wherein said alternating current power source comprises at least one of a non-rectified alternating current source, a half wave rectified alternating current source, and a full wave rectified alternating current source.

6. The apparatus of claim 4, wherein said deactivation antenna coil and said energy storage capacitor are arranged to form an inductor-capacitor resonant tank circuit.

7. The apparatus of claim 6, wherein said deactivation antenna coil has an inductance of between approximately 100 microhenry to 100 millihenry, and said energy storage capacitor has a capacitance of between approximately 10 microfarad and 10 millifarad.

8. The apparatus of claim 6, wherein a frequency for a resonance formed by said LC resonant tank circuit ranges from a frequency that is approximately equal to a frequency for an alternating current source voltage of said alternating current power source to approximately one hundred times greater than a frequency for said alternating current source voltage.

9. The apparatus of claim 6, further comprising a charging circuit having an electronic control and charge switch, said charging circuit to control a direction of power flow from said power source into and out of said inductor-capacitor resonant tank circuit.

10. The apparatus of claim 9, wherein said charging circuit comprises at least one of a uni-directional charging circuit and a bi-directional charging circuit.

11. The apparatus of claim 4, further comprising a charging circuit having an electronic control and charge switch, said charging circuit to control timing of current flow with respect to an alternating current source voltage for said alternating current power source.

12. The apparatus of claim 11, wherein said charging circuit charges said energy storage capacitor during a positive excursion of said alternating current source voltage.

13. The apparatus of claim 11, wherein said charging circuit provides a full charge for said energy storage capacitor during a single positive excursion of said alternating current source voltage.

14. The apparatus of claim 11, wherein said charging circuit provides a partial charge for said energy storage capacitor during each of two or more successive positive excursions of said alternating current source voltage.

15. The apparatus of claim 11, wherein said charging circuit charges said energy storage capacitor during a negative excursion of said alternating current source voltage.

16. The apparatus of claim 11, wherein said charging circuit provides a full charge for said energy storage capacitor during a single negative excursion of said alternating current source voltage.

17. The apparatus of claim 11, wherein said charging circuit provides a partial charge for said energy storage capacitor during each of two or more successive negative excursions of said alternating current source voltage.

18. The apparatus of claim 11, wherein said charging circuit charges said energy storage capacitor during both positive and negative excursions of said alternating current source voltage.

19. The apparatus of claim 11, wherein said charging circuit provides a partial charge for said energy storage capacitor during each of a series of successive positive and negative excursions of said alternating current source voltage.

20. A deactivator, comprising:

a current power source; and

a resonant recharge circuit having a recharge switch coupled between said current power source and a deactivation capacitor through a deactivation coil, and a deactivation control coupled to said recharge switch and a deactivation switch, said deactivation control to turn said recharge switch on and said deactivation switch off to charge said deactivation capacitor with a resonant charge pulse, and said deactivation control to turn said recharge switch off and said deactivation switch on to send current from said deactivation capacitor to said deactivation coil to create a deactivation field.

21. The deactivator of claim 20, wherein said deactivation coil receives said current and generates said deactivation field in accordance with a current waveform, said current waveform having an initial current pulse to form said resonant charge pulse flowing through said deactivation coil into said deactivation capacitor to charge said deactivation capacitor.

22. The deactivator of claim 20, wherein said recharge switch comprises one of a silicon controlled rectifier, parallel inverted silicon controlled rectifier, bipolar transistor, insulated gate bipolar transistor, metal oxide semiconductor field effect transistor with a series diode, and relay.

23. The deactivator of claim 20, wherein said deactivation switch comprises one of a Triac, parallel inverted silicon controlled rectifier, insulated gate bipolar transistor, metal oxide semiconductor field effect transistor, and relay.

24. The deactivator cit claim 20, wherein said power source comprises a direct current power source and a set of bulk capacitors coupled to said recharge switch.

25. The deactivator of claim 24, wherein a capacitance for said bulk capacitors is greater than or equal to a capacitance for said deactivation capacitor.

26. The deactivator of claim 24, wherein said resonant recharge circuit generates a resonant frequency substantially equal to or greater than a resonant frequency for said deactivation field.

27. The deactivator of claim 24, wherein said deactivation control operates in accordance with a timing waveform, with a first pulse of said timing waveform to turn on said recharge switch, and a second pulse of said timing waveform to turn on said deactivation switch.

28. The deactivator of claim 24, wherein said deactivation control operates in accordance with a timing waveform, with a first pulse of said timing waveform to turn on said deactivation switch, and a second pulse of said timing waveform to turn on said recharge switch.

29. The deactivator of claim 20, wherein said power source comprises an alternating current power source coupled to said recharge switch.

30. The deactivator of claim 29, wherein said resonant recharge circuit generates a resonant frequency higher than a frequency for said alternating current power source.

31. The deactivator of claim 29, wherein said deactivation control controls a voltage on said deactivation capacitor by adjusting when said recharge switch is turned on.

32. The deactivator of claim 31, wherein said deactivation control turns on said recharge switch in accordance with a phase angle for a voltage waveform for said alternating current power source.

33. The deactivator of claim 32, wherein a positive zero crossing of said voltage waveform is referenced to be zero degrees, and said deactivation control turns on said recharge switch when said voltage for said alternating current power source is positive.

34. The deactivator of claim 32, wherein a positive zero crossing of said voltage waveform is referenced to be zero degrees, and said deactivation control turns on said recharge switch when said voltage for said alternating current power source is positive and has a phase angle of approximately 90 degrees.

35. The deactivator of claim 32, wherein said deactivation control adjusts phase angle during a positive alternating current voltage to allow control of deactivation capacitor voltage or charge current.

36. The deactivator of claim 32, wherein said deactivation control adjusts phase angle during a positive alternating current voltage to compensate for changes in said alternating current source voltage.

37. The deactivator of claim 32, wherein a negative zero crossing of said voltage waveform is referenced to be zero degrees, and said deactivation control turns on said recharge switch when said voltage for said alternating currant power source is negative.

38. The deactivator of claim 32, wherein a negative zero crossing of said voltage waveform is referenced to be zero degrees, and said deactivation control turns on said recharge switch when said voltage for said alternating current power source is negative and has a phase angle of approximately 90 degrees.

39. The deactivator of claim 32, wherein said deactivation control adjusts phase angle during a negative alternating current voltage to allow control of deactivation capacitor voltage or charge current.

40. The deactivator of claim 32, wherein said deactivation control adjusts phase angle during a negative alternating current voltage to compensate for changes in said alternating current source voltage.

41. The deactivator of claim 32, wherein said deactivation control turns on said deactivation switch once a current has dropped to zero in said recharge switch and said recharge switch has been turned off.

42. The deactivator of claim 41, wherein said deactivation controls turns on said deactivation switch at a subsequent zero crossing of said voltage waveform for said alternating current power source.

43. The deactivator of claim 29, wherein said resonant recharge circuit charges said deactivation capacitor during a positive excursion of said alternating current source voltage.

44. The deactivator of claim 29, wherein said resonant recharge circuit provides a full charge for said deactivation capacitor during a single positive excursion of said alternating current source voltage.

45. The deactivator of claim 29, wherein said resonant recharge circuit provides a partial charge for said deactivation capacitor during each of two or more successive positive excursions of said alternating current source voltage.

46. The deactivator of claim 29, wherein said resonant recharge circuit charges said deactivation capacitor during a negative excursion of said alternating current source voltage.

47. The deactivator of claim 29, wherein said resonant recharge circuit provides a full charge for said deactivation capacitor during a single negative excursion of said alternating current source voltage.

48. The deactivator of claim 29, wherein said resonant recharge circuit provides a partial charge for said deactivation capacitor during each of two or more successive negative excursions of said alternating current source voltage.

49. The deactivator of claim 29, wherein said resonant recharge circuit charges said deactivation capacitor during bath positive and negative excursions of said alternating current source voltage.

50. The deactivator of claim 29, wherein said resonant recharge circuit provides a partial charge for said deactivation capacitor during each of a series of successive positive and negative excursions of said alternating current source voltage.

51. A method, comprising:

receiving a signal to deactivate a marker at a deactivator;

creating a deactivation field to deactivate said marker during a deactivation cycle for said deactivator, said deactivation field to generate a resonant charge pulse; and

charging said deactivator using said resonant charge pulse during a recharge cycle for said deactivator.

52. The method of claim 51, wherein said creating comprises:

turning off a recharge switch to disconnect a power source from a deactivation capacitor;

turning on a deactivation switch to send current from said deactivation capacitor to a deactivation coil; and

generating an alternating current magnetic field by said deactivation coil in accordance with a current waveform, with said current waveform having an initial negative current pulse to form said resonant charge pulse.

53. The method of claim 52, wherein said charging comprises:

turning on said recharge switch to connect said deactivation capacitor to said power source; and

turning off said deactivation switch to send said resonant charge pulse to said deactivation capacitor.

54. The method of claim 53, further comprising generating control signals by a deactivation control to control said recharge switch and said deactivation switch.