System and Method for a Variable Impedance Transmitter Path for Charging Wireless Devices

• US 20130181517A1
• Filed: 10/10/2012
• Published: 07/18/2013
• Est. Priority Date: 01/12/2012
• Status: Active Grant

• Current Assignee: Meta Platforms, Inc. (f/k/a Facebook, Inc.)
• Original Assignee: Meta Platforms, Inc. (f/k/a Facebook, Inc.)
• Inventors: Maguire, Yael
• Granted Patent: US 9,748,790 B2
• Time in Patent Office: Days
• US Class Current: 307/11
• CPC Class Codes: H02J 50/00 Circuit arrangements or systems for wireless supply or distribution of electric power
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

In one embodiment, a method includes wirelessly coupling a transmitter to the wireless device; determining a first power transfer value of a signal transmitted from the transmitter to the wireless device with a first transmit impedance; determining a second power transfer value of the signal transmitted from the transmitter to the wireless device with a second transmit impedance; and selecting one of the first transmit impedance and the second transmit impedance based on the first power transfer value and the second power transfer value.

Claims

1. A method comprising:

wirelessly coupling a transmitter to a wireless device;

determining a first power transfer value of a signal transmitted from the transmitter to the wireless device with a first transmit impedance;

determining a second power transfer value of the signal transmitted from the transmitter to the wireless device with a second transmit impedance; and

selecting one of the first transmit impedance and the second transmit impedance based on the first power transfer value and the second power transfer value.

2. The method of claim 1, wherein the selected transmit impedance corresponds to the higher power transfer value between the first power transfer value and the second power transfer value.

3. The method of claim 1, further comprising

re-determining the first power transfer value of the signal transmitted from the transmitter to the wireless device with the first transmit impedance;

re-determining the second power transfer value of the signal transmitted from the transmitter to the wireless device with the second transmit impedance; and

re-selecting one of the first transmit impedance and the second transmit impedance based on the re-determined first power transfer value and the re-determined second power transfer value.

4. The method of claim 3, wherein re-selecting one of the first transmit impedance and the second transmit impedance based on the re-determined first power transfer value and the re-determined second power transfer value comprises

re-selecting one of the first transmit impedance and the second transmit impedance based on information about power transfer values shared between the wireless device and a communications device having the transmitter.

5. The method of claim 1, further comprising

wirelessly charging the wireless device using the selected one transmit impedance.

6. The method of claim 1, wherein:

the transmitter is a part of a communications device; and

the communications device further comprises a plurality of electrical paths each having a different impedance.

7. The method of claim 1, wherein:

the transmitter is a part of a communications device; and

the communications device further comprises an electrical path having a continuously-controllable impedance.

8. A communications device comprising:

a transmitter configured to transmit a wireless signal to a wireless device; and

processing circuitry coupled to the transmitter and configured to;

determine a first power transfer value of the wireless signal transmitted using a first transmit impedance,

determine a second power transfer value of the wireless signal transmitted using a second transmit impedance, and

select one of the first transmit impedance and the second transmit impedance based on the first power transfer value and the second power transfer value.

9. The communications device of claim 8, wherein:

the selected transmit impedance corresponds to the higher power transfer value between the first power transfer value and the second power transfer value; and

the processing circuitry is further configured to wirelessly charge the wireless device using the selected one transmit impedance.

10. The communications device of claim 8, further comprising:

a printed wiring board etched with a plurality of electrical paths, each electrical path having a different transmit impedance, the plurality of electrical paths including one or more passive components for altering the transmit impedance of each electrical path; and

a switch for selecting, from the plurality of electrical paths, a specific electric path.

11. The communications device of claim 8, wherein the transmitter comprises:

a first digital-to-analog converter configured to convert a real digital signal to a real analog signal;

a second digital-to-analog converter configured to convert an imaginary digital signal to an imaginary analog signal;

a first mixer configured to convert the real analog signal into a radiofrequency (RF) domain for controlling the RF phase of the wireless signal transmitted to the wireless device; and

a second mixer configured to convert the imaginary analog signal into the RF domain for controlling the RF phase of the wireless signal transmitted to the wireless device.

12. The communications device of claim 8, further comprising

one or more antennas for coupling the transmitter to the wireless device,

wherein the one or more antennas are shared with other communications functions of the communications device.

13. A method comprising:

wirelessly coupling a transmitter to one or more first wireless devices; and

for each first wireless device,

sending a plurality of signals using a plurality of transmit impedances, respectively, from the transmitter to the first wireless device;

determining a plurality of power transfer values for the plurality of signals, respectively; and

selecting, from the plurality of transmit impedances, a specific transmit impedance based on the plurality of power transfer values.

14. The method of claim 13, wherein for each first wireless device, the specific transmit impedance corresponds to a specific signal sent from the transmitter to the first wireless device that has the best power transfer value among the plurality of power transfer values.

15. The method of claim 13, further comprising

for each first wireless device,

re-sending the plurality of signals using the plurality of transmit impedances, respectively, from the transmitter to the first wireless device;

re-determining the plurality of power transfer values for the plurality of signals, respectively; and

re-selecting, from the plurality of transmit impedances, the specific transmit impedance based on the plurality of power transfer values.

16. The method of claim 13, further comprising

for each first wireless device, wirelessly charging the first wireless device by a second wireless device having the transmitter using the specific transmit impedance selected for the first wireless device.

17. The method of claim 16, wherein the second wireless device further comprises:

a plurality of electrical paths each having a different transmit impedance;

a printed wiring board etched with the plurality of electrical paths; and

a switch for selecting, from the plurality of electrical paths, a specific electric path.

18. The method of claim 16, wherein the second wireless device further comprises an electrical path having a continuously-controllable transmit impedance.

19. The method of claim 13, wherein a time allocated to each first wireless device for charging is equal.

20. The method of claim 13, wherein a time allocated to each first wireless device for charging is determined based on a weighted list.