Free positioning charging pad

Abstract

Systems, methods and apparatus for wireless charging are disclosed. An apparatus has a wireless charging apparatus has a battery charging power source coupled to a charging circuit, a plurality of charging cells configured to provide a charging surface, and a controller. The controller may be configured to provide a pulse to the charging circuit, detect a frequency of oscillation of the charging circuit responsive to the pulse or a rate of decay of the oscillation of the charging circuit, and determine that a chargeable device has been placed in proximity to a coil of the charging circuit based on changes in a characteristic of the charging circuit. The pulse may have a duration that is less than half the period of a nominal resonant frequency of the charging circuit.

What is claimed is: 
     
         1 . A method for detecting an object, comprising:
 searching a charging surface of a wireless charging device, including:
 providing pulses to a plurality of power transmitting coils in the charging surface, wherein each pulse is configured to cause an oscillation of a charging circuit coupled to one or more of the plurality of power transmitting coils; 
 determining a rate of decay of the oscillation of the charging circuit or a frequency of the oscillation of the charging circuit; and 
 determining that one or more power transmitting coils are proximate to one or more chargeable devices based on the rate of decay of the oscillation or the change in the frequency of the oscillation of a corresponding charging circuit; 
   transmitting digital pings to the one or more power transmitting coils in accordance with standards-defined specifications for wireless charging after determining that the one or more power transmitting coils are proximate to the one or more chargeable devices; and   determining a charging configuration for the one or more chargeable devices based on information encoded in a modulated signal received from the one or more chargeable devices in response to the digital pings sent to the one or more chargeable devices.