Systems, methods, and apparatus for increased foreign object detection loop array sensitivity

Patent metadata

Field	Value
Publication number	US-9921045-B2
Application number	US-201414218516-A
Country	US
Kind code	B2
Filing date	Mar 18, 2014
Priority date	Oct 22, 2013
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

An apparatus for detecting a presence of an object can include a plurality of electrically conductive loops arranged in an array. The apparatus includes a sensor circuit configured to determine a characteristic associated with each of the plurality of loops. The apparatus includes a hardware processor configured to, for each loop of the plurality of loops, determine a parameter based on the characteristic associated with the loop and the characteristic associated with at least one adjacent loop. The hardware processor may be further configured to determine the presence of the object based on the parameter. The parameter may comprise a sum of a difference between the characteristic associated with the loop and a reference value for the characteristic, and a difference between the characteristic associated with each of the at least one adjacent loop and the reference value.

First claim

What is claimed is:

1. An apparatus for detecting a presence of an object, comprising:
a plurality of electrically conductive loops arranged in an array;
a sensor circuit configured to determine a characteristic comprising a loop resonance frequency associated with each of the plurality of loops;
a hardware processor configured to:
for each loop of the plurality of loops, determine a parameter comprising a sum of a deviation of the characteristic associated with the loop from a reference value and a deviation of the characteristic associated with at least one adjacent loop from the reference value, wherein the parameter for at least two of the plurality of loops includes a deviation of the characteristic associated with the same adjacent loop; and
determine the presence of the object based on the parameter.

2. The apparatus of claim 1 , wherein the characteristic further comprises loop impedance.

3. The apparatus of claim 1 , wherein the hardware processor is further configured to apply a weighting factor to each of the deviations based on a geometrical arrangement of the plurality of loops.

4. The apparatus of claim 1 , wherein the hardware processor is further configured to compensate for a drift in the characteristic associated with each of the plurality of loops due to temperature by determining the parameter as a difference between the deviation of the characteristic associated with the loop from the reference value for the characteristic, and the deviation of the characteristic associated with the adjacent loop from the reference value.

5. The apparatus of claim 4 , wherein lead lines for the loop and for the adjacent loop are physically routed substantially together.

6. The apparatus of claim 4 , wherein the hardware processor is configured to cancel out common drift in the characteristic associated with the loop and the adjacent loop.

7. The apparatus of claim 1 , wherein the plurality of loops do not overlap.

8. The apparatus of claim 1 , wherein the plurality of loops overlap.

9. A method for detecting a presence of an object, comprising:
determining a characteristic comprising a loop resonance frequency associated with each of a plurality of electrically conductive loops arranged in an array;
for each loop of the plurality of loops, determining a parameter comprising a sum of a deviation of the characteristic associated with the loop from a reference value and a deviation of the characteristic associated with at least one adjacent loop from the reference value, wherein the parameter for at least two of the plurality of loops includes a deviation of the characteristic associated with the same adjacent loop; and
determining the presence of the object based on the parameter.

10. The method of claim 9 , wherein the characteristic further comprises a loop impedance.

11. The method of claim 9 , wherein determining the parameter comprises applying a weighting factor to each of the deviations based on a geometrical arrangement of the plurality of loops.

12. The method of claim 9 , wherein determining the parameter comprises compensating for a drift in the characteristic associated with each of the plurality of loops due to temperature by determining the parameter as a difference between the deviation of the characteristic associated with the loop from the reference value for the characteristic, and the deviation of the characteristic associated with the adjacent loop from the reference value.

13. The method of claim 12 , wherein lead lines for the loop and for the adjacent loop are physically routed substantially together.

14. The method of claim 12 , wherein compensating for the drift cancels out common drift in the characteristic associated with the loop and the adjacent loop.

15. The method of claim 9 , wherein the plurality of loops do not overlap.

16. The method of claim 9 , wherein the plurality of loops overlap.

17. An apparatus for detecting a presence of an object, comprising:
means for determining a characteristic comprising a loop resonance frequency associated with each of a plurality of loops of a loop array;
means for, for each loop of the plurality of loops, determining a parameter comprising a sum of a deviation of the characteristic associated with the loop from a reference value and a deviation of the characteristic associated with at least one adjacent loop from the reference value, wherein the parameter for at least two of the plurality of loops includes a deviation of the characteristic associated with the same adjacent loop; and
means for determining the presence of the object based on the parameter.

18. The apparatus of claim 17 , wherein the characteristic further comprises a loop impedance.

19. The apparatus of claim 17 , further comprising means for compensating for a drift in the characteristic associated with each of the plurality of loops due to temperature by determining the parameter as a difference between the deviation of the characteristic associated with the loop from the reference value for the characteristic, and the deviation of the characteristic associated with the adjacent loop from the reference value.

20. The apparatus of claim 19 , wherein compensating for the drift in the characteristic comprises cancelling out common drift in the characteristic associated with the loop and the adjacent loop.

21. The apparatus of claim 19 , wherein the plurality of loops do not overlap.

22. A non-transitory computer-readable medium for detecting a presence of an object having encoded thereon instructions that when executed cause an apparatus to:
determine a characteristic comprising a loop resonance frequency associated with each of a plurality of electrically conductive loops arranged in an array;
for each loop of the plurality of loops, determine a parameter comprising a sum of a deviation of the characteristic associated with the loop from a reference value and a deviation of the characteristic associated with at least one adjacent loop from the reference value, wherein the parameter for at least two of the plurality of loops includes a deviation of the characteristic associated with the same adjacent loop; and
determine the presence of the object based on the parameter.

23. The non-transitory computer-readable medium of claim 22 , wherein the characteristic further comprises a loop impedance.

24. The non-transitory computer-readable medium of claim 22 , wherein determining the parameter comprises compensating for a drift in the characteristic associated with each of the plurality of loops due to temperature by determining the parameter as a difference between the deviation of the characteristic associated with the loop from the reference value for the characteristic, and the deviation of the characteristic associated with the adjacent loop from the reference value.

25. The non-transitory computer-readable medium of claim 24 , wherein compensating for the drift comprises cancelling out common drift in the characteristic associated with the loop and the adjacent loop.

26. The non-transitory computer-readable medium of claim 24 , wherein the plurality of loops do not overlap.

Assignees

• Qualcomm Inc

Inventors

• Sieber Lukas
• Fischer Marcel
• Widmer Hanspeter

Classifications

• H02J50/90

  involving detection or optimisation of position, e.g. alignment · CPC title

• H02J50/12

  of the resonant type · CPC title

• H02J50/60

  responsive to the presence of foreign objects, e.g. detection of living beings · CPC title

• B60L53/122

  Circuits or methods for driving the primary coil, e.g. supplying electric power to the coil · CPC title

• B60L53/36

  by positioning the vehicle · CPC title