WIRELESS CHARGER WITH COMBINED ELECTRIC RADIATION SHIELDING AND CAPACITIVE SENSING FUNCTIONS

1 . A wireless charger for charging an electronic device with a second coil, comprising:

a charging module, comprising a first coil electromagnetically coupled to the second coil, a placing area for the electronic device to be placed on opposite to the first coil, and a comb-shaped shielding located between the placing area and the first coil;

a capacitive sensor, which is connected to the comb-shaped shielding to detect the capacitance varient between the comb-shaped shielding and the environment; and

a control unit, which is connected to the comb-shaped shielding and the capacitive sensor and records the capacitance varient;

wherein, when the capacitance varient exceeds a predefined threshold, the control unit sends a ping signal to the electronic device, and if the electronic device responds, the control unit switches the charging module from a standby mode to a charging mode to wireless charge the electronic device and switches the comb-shaped shielding to be connected to a ground.

2 . The wireless charger of claim 1 , wherein the control unit further comprises a switch, which is electrically connected between the ground and the comb-shaped shielding.

3 . The wireless charger of claim 2 , wherein the switch is a transistor.

4 . The wireless charger of claim 1 , wherein the ping signal is sending from the control unit via the first coil.

5 . The wireless charger of claim 1 , wherein the comb-shaped shielding comprises a plurality of parallel segments.

6 . The wireless charger of claim 1 , wherein the comb-shaped shielding is printed as a circuit path on a PCB board.

7 . The wireless charger of claim 1 , wherein at least two comb-shaped shieldings are used, positioned with different directions against each other and located in different layers of the wireless charger.

8 . The wireless charger of claim 1 , wherein the comb-shaped shielding is used as a capacitive sensor electrode when the wireless charger is in the stanby mode.

9 . A method for combing electric radiation shielding and capacitive sensing functions to a wireless charger, comprising:

(a) detecting a capacitance varient between a comb-shaped shielding of the wireless charger and the environment via a capacitive sensor connected to the comb-shaped shielding in a standby mode;

(b) transmitting a ping signal to confirm an electronic device is to be charged when the capacitance varient exceeds a predefined threshold by a controller;

(c) switching the comb-shaped shielding to be connected to a ground and powering on the wireless charger to perform wireless charging when a response to the ping signal is received in a charging mode; and

(d) switching the wireless charger back to the standby mode when the capacitance varient is under the predefined threshold.

10 . The method of claim 9 , wherein the wireless charger is connected to a controller to record the capacitance varient and to perform the switch between the standby mode and the charging mode.

11 . The method of claim 9 , wherein the capacitive sensor is a capacitive sensor integrated circuit.

12 . The method of claim 9 , wherein the control unit further comprises a switch, which is electrically connected between the ground and the comb-shaped shielding.

13 . The method of claim 12 , wherein the switch is a transistor.

14 . The method of claim 9 , wherein the comb-shaped shielding comprises a plurality of parallel segments.

15 . The methof of claim 9 , wherein the comb-shaped shielding is printed as a circuit path on a PCB board.

16 . The method of claim 9 , wherein at least two comb-shaped shieldings are used, positioned with different directions against each other and located in different layers of the wireless charger.