Wireless power transmitter

1. A wireless power transmitter comprising:

a transmission antenna comprising a resonance capacitor and a transmission coil coupled in series;

a driver comprising a bridge circuit structured to apply a driving voltage across the transmission antenna; and

a power transmission control circuit structured to control the driver,

wherein the power transmission control circuit comprises a wireless device detector structured to detect a neighboring wireless device before electric power transmission is started.

2. The wireless power transmitter according to claim 1 , wherein the wireless device detector detects the wireless device based on an electrical state of the transmission antenna in a state in which the driver suspends a switching operation thereof.

3. The wireless power transmitter according to claim 1 , wherein the wireless device detector detects the wireless device based on an electrical state of a power supply line of the driver in a state in which a supply of power to the driver is suspended.

4. The wireless power transmitter according to claim 1 , further comprising a reception coil,

wherein the wireless device detector detects the wireless device based on an electrical state of the reception coil before electric power transmission is started.

5. The wireless power transmitter according to claim 1 , wherein the wireless device detector detects the wireless device based on an electrical state of the reception coil after electric power transmission is started.

6. The wireless power transmitter according to claim 1 , wherein, when the wireless device is detected, the power transmission control circuit does not transmit electric power.

7. The wireless power transmitter according to claim 1 , wherein the power transmission control circuit comprises a notification unit structured to notify an external circuit of a detection of the wireless device.

8. The wireless power transmitter according to claim 1 , that conforms to at least one from among the Qi standard and the PMA standard.

9. A charger comprising the wireless power transmitter according to claim 1 .

10. A power transmission control circuit structured to control a wireless power transmitter, wherein the wireless power transmitter comprises:

a transmission antenna comprising a resonance capacitor and a transmission coil coupled in series; and

a driver comprising a bridge circuit structured to apply a driving voltage across the transmission antenna,

and wherein the power transmission control circuit comprises:

a demodulator structured to demodulate a control signal received by the transmission antenna;

an electric power controller and a pre-driver structured to control the driver according to the control signal; and

a wireless device detector structured to detect a neighboring wireless device before electric power transmission is started.

11. The power transmission control circuit according to claim 10 , wherein the wireless device detector detects the wireless device based on an electrical state of the transmission antenna in a state in which switching of the driver is suspended.

12. The power transmission control circuit according to claim 10 , wherein the wireless device detector detects the wireless device based on an electrical state of a power supply line of the driver in a state in which a supply of power to the driver is suspended.

13. The power transmission control circuit according to claim 10 , wherein the wireless power transmitter further comprising a reception coil,

and wherein the wireless device detector detects the wireless device based on an electrical state of the reception coil before electric power transmission is started.

14. The power transmission control circuit according to claim 10 , wherein the wireless device detector detects the wireless device based on an electrical state of the reception coil after electric power transmission is started.

15. The power transmission control circuit according to claim 10 , wherein, upon detecting the wireless device, the electric power controller and the pre-driver suspend a driving operation of the driver.

16. The power transmission control circuit according to claim 10 , further comprising a notification unit structured such that, upon detecting the wireless device, the notification unit notifies an external circuit of a detection result.

17. The power transmission control circuit according to claim 10 , monolithically integrated on a single semiconductor substrate.

18. A control method for a wireless power transmitter, wherein the wireless power transmitter comprises:

a transmission antenna comprising a resonance capacitor and a transmission coil coupled in series;

a driver comprising a bridge circuit structured to apply a driving voltage across the transmission antenna; and

a power transmission control circuit structured to control the driver, and wherein the control method comprises:

judging the presence or absence of a neighboring wireless device before electric power transmission is started; and

starting electric power transmission when the wireless device has not been detected.

19. The control method according to claim 18 , wherein the presence or absence of the wireless device is judged based on an electrical state of the transmission antenna in a state in which switching of the driver is suspended.

20. The control method according to claim 18 , wherein the presence or absence of the wireless device is judged based on an electrical state of a power supply line of the driver in a state in which the supply of power to the driver is suspended.

21. The control method according to claim 18 , wherein the wireless power transmitter further comprises a reception coil,

and wherein the presence or absence of the wireless device is judged based on an electrical state of the reception coil.