Operating an Inductive Energy Transfer System

• US 20160064992A1
• Filed: 07/09/2015
• Published: 03/03/2016
• Est. Priority Date: 09/02/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Herbst, Steven G., Alves, Jeffrey M., Hwang, Jim C., Morrison, Scott D., Garbus, Brandon R., Parnell, Robert S., Tikalsky, Terry L.
• Granted Patent: US 10,193,372 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices

Abstract

A receiver device in an inductive energy transfer system can include a touch sensing device. If the input surface of the touch sensing device is touched, a transmitter device can periodically stop transferring energy to allow the touch sensing device to sense touch samples while inductive energy transfer is inactive. Additionally or alternatively, a transmitter device can produce an averaged duty cycle by transferring energy to the receiver device for one or more periods at a first duty cycle step and for one or more periods at different second first duty cycle step. Additionally or alternatively, a transmitter device can reduce a current level received by a DC-to-AC converter if the current received by the DC-to-AC converter equals or exceeds a threshold. Additionally or alternatively, a transmitter device can ping a receiver device and transfer energy only after a response signal is received from the receiver device.

Claims

1. A method for operating an inductive energy transfer system that includes a transmitter device and a receiver device, the transmitter device including a current sense circuit operatively connected to an input of a DC-to-AC converter and a processing device operatively connected to the current sense circuit, the method comprising:

during inductive energy transfer from the transmitter device to the receiver device, the current sense circuit measuring a current input into the DC-to-AC converter;

the processing device determining if the measured current equals or exceeds a threshold; and

if the measured current equals or exceeds the threshold, reducing the current input into the DC-to-AC converter by modifying an operation of the DC-to-AC converter.

2. The method as in claim 1, wherein modifying an operation of the DC-to-AC converter comprises decreasing a duty cycle of the energy transfer.

3. The method as in claim 1, wherein modifying an operation of the DC-to-AC converter comprises decreasing a voltage level input into the DC-to-AC converter.

4. The method as in claim 1, wherein modifying an operation of the DC-to-AC converter comprises decreasing an operating frequency of the DC-to-AC converter.

5. The method as in claim 1, further comprising not responding to a request to increase the duty cycle.

6. The method as in claim 3, further comprising changing a sampling time of the current measurement.

7. The method as in claim 2, further comprising changing the given amount used to decrease the duty cycle of the energy transfer.

8. A transmitter device for an inductive energy transfer system, comprising:

a DC-to-AC converter operatively connected between a current sense circuit and a transmitter coil; and

a processing device operatively connected to the current sense circuit, wherein the processing device is configured to periodically receive a current measurement from the current sense circuit and configured to reduce a current level input into the DC-to-AC converter if the current measurement equals or exceeds a threshold by modifying an operation of the DC-to-AC converter.

9. The transmitter device as in claim 8, wherein modifying an operation of the DC-to-AC converter comprises reducing an energy transfer duty cycle.

10. The transmitter device as in claim 8, wherein modifying an operation of the DC-to-AC converter comprises reducing a voltage level input into the DC-to-AC converter.

11. The transmitter device as in claim 8, wherein modifying an operation of the DC-to-AC converter comprises modifying an operating frequency of the DC-to-AC converter.

12. A method for operating an inductive energy transfer system that includes a transmitter device and a receiver device, the receiver device including a touch sensing device, the method comprising:

detecting if an input surface of the touch sensing device is touched while the transmitter device is transferring energy inductively to the receiver device; and

if the input surface is touched, the transmitter device transferring energy inductively only during a first time period and the touch sensing device obtaining touch samples only during a different second time period.

13. The method as in claim 12, further comprising determining if the input surface is being touched prior to the transmitter device transferring energy inductively to the receiver device.

14. The method as in claim 12, further comprising transferring energy inductively if a touch is not detected on the input surface of the touch sensing device.

15. The method as in claim 12, wherein the input surface of the touch sensing device comprises a cover glass disposed over a display.

16. The method as in claim 15, wherein the receiver device comprises a wearable communication device.

17. A method for operating an inductive energy transfer system that includes a transmitter device and a receiver device, the receiver device including a touch sensing device, the method comprising:

detecting if an input surface of the touch sensing device is touched while the transmitter device is transferring energy inductively to the receiver device;

if the input surface is touched, the receiver device transmitting a signal to the transmitter device;

the transmitter device turning off for a given period of time based on the signal received from the receiver device;

the touch sensing device obtaining touch samples while the transmitter device is turned off; and

at the end of the given time period, the transmitter device turning on and transferring energy inductively to the receiver device.

18. The method as in claim 17, further comprising the receiver device suspending signal transmission to the transmitter device during the time period the transmitter device is turned off.

19. The method as in claim 17, wherein the input surface of the touch sensing device comprises a cover glass disposed over a display.

20. The method as in claim 19, wherein the receiver device comprises a wearable communication device.

21. A method for operating an inductive energy transfer system that includes a transmitter device and a receiver device, the method comprising:

the transmitter device transferring energy inductively to the receiver device for one or more periods at a first duty cycle step; and

the transmitter device transferring energy inductively to the receiver device for one or more periods at different second first duty cycle step, wherein a duty cycle of the energy transfer is averaged over the multiple periods.

22. The method as in claim 21, further comprising changing a total number of periods to adjust the averaged duty cycle, wherein the total number of periods is comprised of the one or more periods energy is transferred inductively at the first and second duty cycle steps.

23. The method as in claim 21, further comprising changing at least one of the first duty cycle step and the second duty cycle step to adjust the averaged duty cycle.

24. The method as in claim 21, wherein the receiver device transmits the signal over a communication channel that is separate from inductive energy transfer.

25. A method for operating an inductive energy transfer system that includes a transmitter device and a receiver device, the method comprising:

the transmitter device transmitting a ping during a first time period;

within a second time period after the first time period, the transmitter device determining whether the receiver device is transmitting a signal;

if the transmitter device detects the signal transmission, within a third time period after the second time period the transmitter device determining if a complete signal is received from the receiver device; and

if the complete signal is received from the receiver device, the transmitter device transferring energy inductively to the receiver device based on the receipt of the complete signal.

26. The method as in claim 25, wherein the signal comprises a preamble packet that is included in a communication protocol.

27. The method as in claim 25, further comprising the transmitter device entering a low power state if the transmitter device does not detect the signal transmission.

28. The method as in claim 25, further comprising the transmitter device entering a low power state if the transmitter device does not receive the complete signal from the receiver device within the third time period.