Patent 9985463 was granted and assigned to Panasonic on May, 2018 by the United States Patent and Trademark Office.
A controller of a mobile terminal charging device compares a resonance frequency or a resonance voltage of each of a plurality of foreign object detection coils with a reference resonance frequency or a reference resonance voltage of each foreign object detection coil, stored in a memory, corresponding to a position of a charging coil. The controller performs a safety operation on the basis of a comparison result.