Wireless power system with capacitive proximity sensing
This disclosure provides systems, methods and apparatus for tuning a transmit coil for operation in a plurality of frequency bands. In one aspect, a method of wireless power transmission is provided. The method includes exciting a first part of a wireless power transmission system, via a wireless power transmitter. The method further includes detecting, in the presence of a non-charging object, a first change in a first parameter. The first parameter is indicative of a coupling between the non-charging object and the first part. The method further includes varying a characteristic of the wireless power transmission based on said first change.
1. A method of wireless power transmission comprising:
exciting a first part of a wireless power transmission system, via a wireless power transmitter;
detecting, in the presence of a non-charging object, a first change in a first parameter indicative of a capacitive coupling between the non-charging object and the first part; and
varying a characteristic of the wireless power transmission based on said first change.
2. The method of claim 1 , wherein the wireless power transmitter excites the first part via an antenna capacitively coupled with the first part.
3. The method of claim 1 , wherein the first part comprises a conducting plate.
4. The method of claim 3 , wherein the conducting plate comprises a metal.
5. The method of claim 1 , wherein the non-charging object comprises a living object.
6. The method of claim 1 , wherein the non-charging object comprises a parasitic receiver.
7. The method of claim 1 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
8. The method of claim 7 , wherein said varying comprises reducing the transmit power when the first change is detected.
9. The method of claim 7 , wherein said varying comprises increasing the transmit power when the first change is detected.
10. The method of claim 1 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
11. A method of determining a distance of an object from a transmit antenna comprising:
exciting, via the transmit antenna, a first and second part of a wireless power transmission system, the second part being displaced from the first part;
detecting, in the presence of a non-charging object, a first change in a first parameter indicative of a coupling between the non-charging object and the first part;
detecting, in the presence of the non-charging object, a second change in a second parameter indicative of a coupling between the non-charging object and the second part; and
comparing said first and second changes to determine a location of said object.
12. The method of claim 11 , wherein the coupling comprises a capacitive coupling.
13. The method of claim 11 , wherein the first and second parts each comprise a conducting plate.
14. The method of claim 13 , wherein each conducting plate comprises a metal.
15. The method of claim 11 , wherein the non-charging object comprises a living object.
16. The method of claim 11 , wherein the non-charging object comprises a parasitic receiver.
17. The method of claim 11 , further comprising varying a characteristic of the wireless power transmission based on the determined location of said object.
18. The method of claim 17 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
19. The method of claim 18 , wherein said varying comprises reducing the transmit power based on the determined location.
20. The method of claim 18 , wherein said varying comprises increasing the transmit power based on the determined location.
21. The method of claim 17 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
22. The method of claim 11 , further comprising controlling a device input based on the determined location.
23. The method of claim 22 , wherein the device input comprises at least one of: a charging rate, a music control, a data synchronization, and a power control.
24. The method of claim 11 , further comprising determining an orientation of the object.
25. A system configured to provide wireless power transmission comprising:
a first metal plate;
a transmit antenna configured to provide wireless power and to excite the first metal plate; and
a circuit configured to detect a first change in capacitance between said transmit antenna and said first metal plate.
26. The system of claim 25 , further comprising a controller configured to vary a characteristic of the wireless power transmission based on the detected first change.
27. The system of claim 26 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
28. The system of claim 27 , wherein said varying comprises reducing the transmit power when the first change is detected.
29. The system of claim 27 , wherein said varying comprises increasing the transmit power when the first change is detected.
30. The system of claim 26 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
31. A system configured to determine a location of a foreign object in a vicinity of a wireless charging system comprising:
a first metal plate;
a second metal plate displaced from the first metal plate;
a transmit antenna configured to provide wireless power and to excite the first and second metal plates;
a circuit configured to detect a first change in capacitance between said transmit antenna and said first metal plate;
a circuit configured to detect a second change in capacitance between said transmit antenna and said second metal plate; and
a circuit configured to compare said first change to said second change to determine the location of said foreign object.
32. The system of claim 31 , further comprising a controller configured to vary a characteristic of the wireless power transmission based on the determined location of said object.
33. The system of claim 32 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
34. The system of claim 33 , wherein said varying comprises reducing the transmit power based on the determined location.
35. The system of claim 33 , wherein said varying comprises increasing the transmit power based on the determined location.
36. The system of claim 32 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
37. The system of claim 31 , further comprising a controller configured to control a device input based on the determined location.
38. The system of claim 37 , wherein the device input comprises at least one of: a charging rate, a music control, a data synchronization, and a power control.
39. The system of claim 31 , further comprising a circuit configured to determine an orientation of the object.
40. An apparatus for wireless power transmission comprising:
means for transmitting wireless power and for exciting a first part of a wireless power transmission system;
means for detecting, in the presence of a non-charging object, a first change in a first parameter indicative of a capacitive coupling between the non-charging object and the first part; and
means for varying a characteristic of the wireless power transmission based on said first change.
41. The apparatus of claim 40 , wherein the means for transmitting excites the first part via an antenna capacitively coupled with the first part.
42. The apparatus of claim 40 , wherein the first part comprises a conducting plate.
43. The apparatus of claim 42 , wherein the conducting plate comprises a metal.
44. The apparatus of claim 40 , wherein the non-charging object comprises a living object.
45. The apparatus of claim 40 , wherein the non-charging object comprises a parasitic receiver.
46. The apparatus of claim 40 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
47. The apparatus of claim 46 , further comprising means for reducing the transmit power when the first change is detected.
48. The apparatus of claim 46 , further comprising means for increasing the transmit power when the first change is detected.
49. The apparatus of claim 40 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
50. An apparatus for determining a distance of an object from a transmit antenna comprising:
means for transmitting wireless power and for exciting a first and second part of a wireless power transmission system, the second part being displaced from the first part;
means for detecting, in the presence of a non-charging object, a first change in a first parameter indicative of a coupling between the non-charging object and the first part;
means for detecting, in the presence of the non-charging object, a second change in a second parameter indicative of a coupling between the non-charging object and the second part; and
means for comparing said first and second changes to determine a location of said object.
51. The apparatus of claim 50 , wherein the coupling comprises a capacitive coupling.
52. The apparatus of claim 50 , wherein the first and second parts each comprise a conducting plate.
53. The apparatus of claim 52 , wherein each conducting plate comprises a metal.
54. The apparatus of claim 50 , wherein the non-charging object comprises a living object.
55. The apparatus of claim 50 , wherein the non-charging object comprises a parasitic receiver.
56. The apparatus of claim 50 , further comprising means for varying a characteristic of the wireless power transmission based on the determined location of said object.
57. The apparatus of claim 56 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
58. The apparatus of claim 57 , further comprising means for reducing the transmit power based on the determined location.
59. The apparatus of claim 57 , further comprising means for increasing the transmit power based on the determined location.
60. The apparatus of claim 56 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
61. The apparatus of claim 50 , further comprising means for controlling a device input based on the determined location.
62. The apparatus of claim 61 , wherein the device input comprises at least one of: a charging rate, a music control, a data synchronization, and a power control.
63. The apparatus of claim 50 , further comprising means for determining an orientation of the object.
64. A non-transitory computer-readable medium comprising code that, when executed, causes an apparatus to:
excite a first part of a wireless power transmission system, via a wireless power transmitter;
detect, in the presence of a non-charging object, a first change in a first parameter indicative of a coupling between the non-charging object and the first part; and
vary a characteristic of the wireless power transmission based on said first change.
65. The medium of claim 64 , wherein the coupling comprises a capacitive coupling.
66. The medium of claim 64 , wherein the first part comprises a conducting plate.
67. The medium of claim 66 , wherein the conducting plate comprises a metal.
68. The medium of claim 64 , wherein the non-charging object comprises a living object.
69. The medium of claim 64 , wherein the non-charging object comprises a parasitic receiver.
70. The medium of claim 64 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
71. The medium of claim 70 , further comprising code that, when executed, causes the apparatus to reduce the transmit power when the first change is detected.
72. The medium of claim 70 , further comprising code that, when executed, causes the apparatus to increase the transmit power when the first change is detected.
73. The medium of claim 64 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
74. A non-transitory computer-readable medium comprising code that, when executed, causes an apparatus to:
excite, via a transmit antenna, a first and second part of a wireless power transmission system, the second part being displaced from the first part;
detect, in the presence of a non-charging object, a first change in a first parameter indicative of a coupling between the non-charging object and the first part;
detect, in the presence of the non-charging object, a second change in a second parameter indicative of a coupling between the non-charging object and the second part; and
compare said first and second changes to determine a location of said object.
75. The medium of claim 74 , wherein the coupling comprises a capacitive coupling.
76. The medium of claim 74 , wherein the first and second parts each comprise a conducting plate.
77. The medium of claim 76 , wherein each conducting plate comprises a metal.
78. The medium of claim 74 , wherein the non-charging object comprises a living object.
79. The medium of claim 74 , wherein the non-charging object comprises a parasitic receiver.
80. The medium of claim 74 , further comprising code that, when executed, causes the apparatus to vary a characteristic of the wireless power transmission based on the determined location of said object.
81. The medium of claim 80 , wherein the varied characteristic of the wireless power transmission comprises a transmit power.
82. The medium of claim 81 , further comprising code that, when executed, causes the apparatus to reduce the transmit power based on the determined location.
83. The medium of claim 81 , further comprising code that, when executed, causes the apparatus to increase the transmit power based on the determined location.
84. The medium of claim 80 , wherein the varied characteristic of the wireless power transmission comprises a transmit frequency.
85. The medium of claim 74 , further comprising code that, when executed, causes the apparatus to control a device input based on the determined location.
86. The medium of claim 85 , wherein the device input comprises at least one of: a charging rate, a music control, a data synchronization, and a power control.
87. The medium of claim 74 , further comprising code that, when executed, causes the apparatus to determine an orientation of the object.