Controlling power supplied to a circuit using an externally applied magnetic field

• US 20050093374A1
• Filed: 10/31/2003
• Published: 05/05/2005
• Est. Priority Date: 10/31/2003
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Pradhan, Salil, Lyon, Geoffrey Martin, Connors, Timothy
• Granted Patent: US 7,250,695 B2
• Time in Patent Office: Days
• US Class Current: 307/126
• CPC Class Codes: G06K 19/0705 the battery being connected to a power saving arrangement
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

A power control circuit is used to control the power supplied to a circuit from a power source. The power control circuit is operable to connect and disconnect the power source from the circuit. The power control circuit connects the power source to the circuit in response to an externally applied magnetic field.

Claims

1. An apparatus comprising:

a power control circuit operable to connect and disconnect a power source from a circuit, the power source supplying power to the circuit,

wherein the power control circuit connects the power source to the circuit in response to an externally applied magnetic field.

2. The apparatus of claim 1, further comprising a passive tag connected to the power control circuit, wherein the passive tag transmits a signal to the power control circuit in response to the magnetic field being applied to the passive tag and the power control circuit connects the power source to the circuit in response to receiving the signal from the passive tag.

3. The apparatus of claim 2, wherein the power control circuit comprises a switch operable to connect and disconnect the power source, wherein the switch has a high off state resistance minimizing leakage current from the power source when the switch disconnects the power source from the circuit.

4. The apparatus of claim 3, wherein the switch comprises a MOSFET semiconductor switching device.

5. The apparatus of claim 3, wherein the signal from the passive tag drives the switch to an on state connecting the power source to the circuit.

6. The apparatus of claim 5, wherein the power control circuit is operable to receive a signal from the circuit for driving the switch to maintain the on state.

7. The apparatus of claim 3, wherein the power control circuit further comprises an OR logic circuit having a first input connected to the passive tag, a second input connected to the circuit and an output connected to the switch, wherein one or more of the signal from the passive tag and a signal from the circuit is operable to place or maintain the switch in the on state.

8. The apparatus of claim 1, wherein the power control circuit is operable to substantially disconnect the power source from the circuit such that an insufficient amount of power is available to allow the circuit to be operational.

9. A system comprising:

a reader operable to generate a magnetic field;

a passive tag operable to generate a signal in response to the magnetic field being applied to the passive tag; and

a power control circuit operable to connect and substantially disconnect a power source from a device, wherein the power control circuit connects the power source to the device in response to receiving the signal from the passive tag.

10. The system of claim 9, wherein the power control circuit is operable to substantially disconnect the power source from the device such that an insufficient amount of power is available to allow the device be operational.

11. The system of claim 9, wherein the power control circuit comprises a switch operable to connect and disconnect the power source, wherein the switch has a high off state resistance minimizing leakage current from the power source when the switch disconnects the power source from the device.

12. The system of claim 11, wherein the switch comprises a MOSFET semiconductor switching device.

13. The system of claim 11, wherein the signal from the passive tag drives the switch to an on state connecting the power source to the device.

14. The system of claim 13, wherein the power control circuit is operable to receive a signal from the device for driving the switch to maintain the on state.

15. The system of claim 11, wherein the power control circuit further comprises an OR logic circuit having a first input connected to the passive tag, a second input connected to the device and an output connected to the switch, wherein one or more of the signal from the passive tag and a signal from the device is operable to place or maintain the switch in the on state.

16. The system of claim 9, wherein the device comprises an active tag placed in an off mode when the power control circuit substantially disconnects the power source from the device, wherein the active tag is inoperable in the off mode to perform a function.

17. The system of claim 16, wherein the active tag is awakened from the off mode in response to the reader generating the magnetic field in the presence of the passive tag.

18. The system of claim 9, wherein the device comprises an appliance placed in an off mode when the power control circuit substantially disconnects the power source from the appliance, wherein the appliance is non-functional in the off mode.

19. The system of claim 16, wherein the appliance is awakened from the off mode in response to the reader generating the magnetic field in the presence of the passive tag, the reader being provided in a remote control operable for the appliance.

20. A method of conserving power in a device comprising:

receiving an externally applied magnetic field; and

awakening the device from an off mode in response to receiving the externally applied magnetic field, wherein the device is substantially disconnected from a power source in the off mode such that the device is inoperable to perform a function in the off mode.

21. The method of claim 20, wherein the step of awakening comprises controlling a power control circuit to connect a power source to the device in response to receiving the magnetic field.

22. The method of claim 21, further comprising controlling a power control circuit to maintain a connection between the power source and the device in response to receiving a signal from the device.

23. The method of claim 22, further comprising controlling the power control circuit to substantially disconnect the power source from the device such that the device reenters the off mode.

24. An apparatus comprising:

a power source means for supply power to a device;

a power control circuit means for connecting and substantially disconnecting the power source means from the device; and

a tag means for generating a signal directing the power control circuit means to connect the power source means to the device in response to the magnetic field being applied to the tag means.

25. The apparatus of claim 24 further comprising a reader means for generating the magnetic field.

26. An apparatus controlling power supplied to a power consuming circuit, the apparatus comprising:

a circuit operable to generate a signal in response to being within a proximity of an external device; and

a power control circuit operable to connect and substantially disconnect a power source from the power consuming circuit, wherein the power control circuit connects the power source to the power consuming circuit in response to receiving the signal from the circuit.

27. The apparatus of claim 26, wherein the circuit is included in a receiver operable to receive a control signal from a transmitter for invoking the circuit to generate the signal.

28. The apparatus of claim 27, wherein the receiver includes a passive tag and the control signal is a magnetic field inducing a current in the passive tag.

29. The apparatus of claim 26, wherein the power consuming circuit is included in one of an active tag and an appliance.

30. The apparatus of claim 26, wherein the power control circuit is operable to substantially disconnect the power source from the power consuming circuit such that an insufficient amount of power is available to allow the power consuming circuit to be operational.