Method and apparatus for optical wireless charging

• US 20070114967A1
• Filed: 11/18/2005
• Published: 05/24/2007
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Peng, Chen
• Granted Patent: US 7,514,899 B2
• Time in Patent Office: Days
• US Class Current: 320/101
• CPC Class Codes: H02J 50/30 using light, e.g. lasers
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y10S 136/291 Applications

Abstract

A portable electronic device is recharged by generating light from a light source of a wireless optical charger, converting the light from the charger into an electrical signal using a photovoltaic cell of the portable electronic device and charging the portable electronic device using the electrical signal. The wireless optical charger may include a proximity sensor that switches on the light source when a portable electronic device is close to the light source.

Claims

1. An optical charger comprising:

a light source operable to emit light; and

a proximity sensor coupled to the light source and operable to detect a portable electronic device in proximity to the light source;

wherein the light source is activated to emit light that falls on a photovoltaic cell of the portable device if the portable electronic device is in proximity to the light source.

2. An optical charger in accordance with claim 1, further comprising:

a light source driving circuit operable to power the light source; and

a micro-controller responsive to the proximity sensor and operable to control the light source driving circuit.

3. An optical charger in accordance with claim 1, further comprising:

a wireless communication circuit operable to communicate with the portable electronic device.

4. An optical charger in accordance with claim 1, wherein the light source comprises an array of light emitting diodes.

5. An optical charger in accordance with claim 4, wherein a light emitting diode of the array of light emitting diodes is operable to generate light having wavelengths in the range 700nm to 1000 nm.

6. An optical charger in accordance with claim 4, wherein a light emitting diode of the array of light emitting diodes is operable to generate infra-red light.

7. An optical charger in accordance with claim 1, further comprising:

a solar cell operable to receive ambient light;

a charge storage device; and

a charge converter coupled to the solar cell and operable to charge the charge storage device;

wherein the light source is powered from the charge storage device.

8. An optical charger in accordance with claim 1, wherein the at least one light source is powered from a power line.

9. An optical charger in accordance with claim 1, wherein the proximity sensor comprises:

a light emitter; and

a photo-detector operable to sense light emitted from the light emitter and reflected from the portable electronic device.

10. An optical charger in accordance with claim 1, wherein the intensity of the light emitter of the proximity sensor is modulated in a first frequency band and wherein the photo-detector comprises:

a photovoltaic cell operable to produce a voltage output signal;

a filter circuit operable to filter the voltage output signal to remove frequency components of the signal not in the first frequency band.

11. An optical charger in accordance with claim 1, wherein the proximity sensor comprises:

the light source; and

a photo-detector;

wherein the photo-detector is shielded from light transmitted on a direct path from the light source.

12. An optical charger in accordance with claim 1, wherein the light source and the proximity sensor are located on the surface of a pad.

13. An electronic device comprising:

a photovoltaic cell operable to generate and electrical signal in response to light received from an optical charger;

a charge storage device; and

a charging circuit operable to receive the electrical signal from the photovoltaic cell and charge the charge storage device.

14. An electronic device in accordance with claim 13, wherein the photovoltaic cell is responsive to infra-red light.

15. An electronic device in accordance with claim 13, wherein the photovoltaic cell has a peak sensitivity to light having a wavelength in the range 700 nm to 1000 nm.

16. An electronic device in accordance with claim 13, wherein the photovoltaic cell is located on the exterior of the electronic device.

17. An electronic device in accordance with claim 13, further comprising a wireless communication device operable to communicate with an optical charger.

18. A method for charging a portable electronic device, the method comprising:

generating light from a light source of a charger;

converting the light from the charger into an electrical signal using a photovoltaic cell of the portable electronic device; and

charging the portable electronic device using the electrical signal.

19. A method in accordance with claim 18, wherein generating light from the light source of the charger comprises activating at least one light emitting diode of the charger.

20. A method in accordance with claim 18, wherein generating light from the light source of the charger comprises:

detecting the proximity of the portable device to the charger;

activating the light source if the portable device is close to the charger; and

deactivating the light source if the portable device is not close to the charger.

21. A method in accordance with claim 20, wherein detecting the proximity of the portable device to the charger comprises:

generating a signal from the charger;

reflecting the signal from the portable electronic device; and

detecting the signal reflected from the portable electronic device.

22. A method in accordance with claim 21, wherein generating a signal from the charger comprises generating a modulated light signal from the charger.

23. A method in accordance with claim 18, further comprising the portable electronic device communication with the optical charger over a wireless communication link.

24. A method in accordance with claim 23, further comprising the portable electronic device signaling the charger to stop charging when the portable electronic device is fully charged.

25. A system for transferring charge from a charger to a portable device, comprising:

a first conversion means, mounted in the charger, for receiving a first electrical signal and converting it into an optical signal; and

a second conversion means, mounted on the portable device, for receiving the optical signal and converting it to a second electrical signal for charging the portable device.

26. A system for transferring charge to a portable device in accordance with claim 25, further comprising

a means for detecting if the portable device is close to the first conversion means;

and

a means for disabling the first conversion means if no portable device is close to the charger.

27. A system for transferring charge to a portable device in accordance with claim 25, further comprising a means for detecting if the portable device is close to charger.