Wireless load modulation

Abstract

Techniques of wireless power transmission are described herein. An example wireless power transmitting apparatus may include a coil and control circuitry. The control circuitry is configured to apply a first signal to the coil and measure a change in a current in the coil to discover presence of an object. The control circuitry is also configured to provide a second signal to the coil, subsequent to discovering presence of the object. The control circuitry is also configured to detect whether the object is a Power Receiver based on whether a load modulated signal is received from the object subsequent to providing the second signal. The control circuitry is also configured to perform power transfer to the object subsequent to detection that the object is a Power Receiver.

What is claimed is: 
     
         1 . An apparatus for a wireless power transmitter, the apparatus comprising:
 a coil; and   control circuitry to:   apply a first signal to the coil and measure a change in a current in the coil to discover presence of an object;   provide a second signal to the coil, subsequent to discovering presence of the object;   detect whether the object is a Power Receiver based on whether a load modulated signal is received from the object subsequent to providing the second signal; and   perform power transfer to the object subsequent to detection that the object is a Power Receiver.   
     
     
         2 . The apparatus of  claim 1 , wherein the first signal is applied to the coil through application of pulses at regular intervals. 
     
     
         3 . The apparatus of  claim 1 , wherein the control circuitry is configured to decode the load modulated signal to collect charging information about the Power Receiver. 
     
     
         4 . The apparatus of  claim 1 , further comprising measurement circuitry to measure power reflected from the Power Receiver. 
     
     
         5 . The apparatus of  claim 4 , wherein the control circuitry is configured to decode an indication from the Power Receiver as to whether the Power Receiver has been charged to a sufficient power level. 
     
     
         6 . The apparatus of  claim 1 , wherein the control circuitry is further configured to encode data for transmission on the coil. 
     
     
         7 . The apparatus of  claim 1 , further comprising:
 a power amplifier and an oscillator to oscillate power for power transfer.   
     
     
         8 . An apparatus for a wireless power receiver, the apparatus comprising:
 a coil; and   control circuitry coupled to the coil, the control circuitry to be configured to:   detect a signal at the coil to determine that the coil has coupled to a wireless power transmitter;   encode a load modulated message for transmission by the coil, responsive to detecting the signal at the coil; and   control the power reception circuitry to receive power from the wireless power transmitter.   
     
     
         9 . The apparatus of  claim 8 , wherein the load modulated signal includes charging information about the apparatus. 
     
     
         10 . The apparatus of  claim 9 , wherein the charging information includes an indication as to whether the apparatus has been charged to a sufficient power level. 
     
     
         11 . The apparatus of  claim 8 , wherein the power reception circuitry includes a rectifier circuit and a voltage regulator. 
     
     
         12 . A method for wireless power transmission, the method comprising:
 applying a first signal to a coil and measuring a change in a current in the coil to discover presence of an object;   providing a second signal to the coil, subsequent to discovering presence of the object;   detecting whether the object is a Power Receiver based on whether a load modulated signal is received from the object subsequent to providing the second signal; and   performing power transfer to the object subsequent to detection that the object is a Power Receiver.   
     
     
         13 . The method of  claim 12 , wherein the first signal is applied to the coil through application of pulses at regular intervals. 
     
     
         14 . The method of  claim 12 , further comprising:
 decoding the load modulated signal to collect charging information about the Power Receiver.   
     
     
         15 . The method of  claim 14 , further comprising:
 determining whether the Power Receiver has been charged to a sufficient power level based on information provided in the load modulated signal.   
     
     
         16 . The method of  claim 12 , further comprising:
 removing current from the coil upon detecting that the object is not a Power Receiver.