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

• US 7,250,695 B2
• Filed: 10/31/2003
• Issued: 07/31/2007
• Est. Priority Date: 10/31/2003
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Sherry; Michael
• Assistant Examiner(s): Deschere; Andrew M.
• Application Number:
  US10/697,686
• Publication Number:
  US 20050093374A1
• Time in Patent Office: 1,369 Days
• Field of Search: 307/414, 307/117, 335/205, 340/527.1, 340/527.3, 340/825.72, 340/825.69
• US Class Current: 307/117
• 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, and the power control circuit is operable to receive a signal from the circuit for directing the power control circuit to maintain the connection of the power source to the circuit after a removal of the externally applied magnetic field, wherein the connection of the power source to the circuit is otherwise severed after the removal of the externally applied magnetic field and without the signal from the circuit.

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 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.

7. 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.

8. A system comprising:

a device having at least a passive tag, a power control circuit, a device circuitry different from the passive tag, and a power source;

a reader operable to generate a magnetic field;

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

the power control circuit operable to connect and substantially disconnect the power source from the device circuitry, wherein the power control circuit connects the power source to the device circuitry in response to receiving the signal from the passive tag, and the power control circuit is operable to receive a signal from the device circuitry for directing the power control circuit to maintain the connection of the power source to the device circuitry after a removal of the magnetic field.

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

10. The system of claim 8, wherein die 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 circuitry.

11. The system of claim 10, wherein the switch comprises a MOSFET semiconductor switching device.

12. The system of claim 10, wherein the signal from the passive tag drives the switch to an on state connecting the power source to the device circuitry.

13. The system of claim 10, 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.

14. The system of claim 8, wherein the device circuitry comprises an active tag placed in an off mode when the power control circuit substantially disconnects the power source from the device circuitry, wherein the active tag is inoperable in the off mode to perform a function.

15. The system of claim 14, 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.

16. The system of claim 8, wherein the device comprises an appliance placed in an off mode when the power control circuit substantially disconnects the power source from the device circuitry, wherein the appliance is non-functional in the off mode.

17. 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.

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

receiving an externally applied magnetic field;

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, 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; and

subsequent to a removal of the externally applied magnetic field, 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 that directs the power control circuit to maintain the connection, the signal is separate from any signal that is generated in response to the externally applied magnetic field.

19. The method of claim 18, further comprising controlling the power control circuit to substantially disconnect the power source from the device such that the device reenters the off mode.

20. 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; and

wherein the power control circuit is operable to receive a signal from the circuit for directing the power control circuit to maintain the connection of the power source to the device after a removal of the applied magnetic field, wherein the signal is separate from any signal that is generated in response to the applied magnetic field.

21. The apparatus of claim 20 further comprising a reader means for generating the magnetic field.

22. 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, and the power control circuit is further operable to receive a signal from the power consuming circuit for directing the power control circuit to maintain the connection of the power source to the power consuming circuit after a removal of the circuit from the proximity of the external device, wherein the signal from the circuit is separate from any signal that is generated in response to the circuit being within a proximity of the external device.

23. The apparatus of claim 22, 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.

24. The apparatus of claim 23, wherein the receiver includes a passive tag and the control signal is a magnetic field inducing a current in the passive tag.

25. The apparatus of claim 22, wherein the power consuming circuit is included in one of an active tag and an appliance.

26. The apparatus of claim 22, 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.