Wireless power transmission

• US 6,633,026 B2
• Filed: 10/31/2001
• Issued: 10/14/2003
• Est. Priority Date: 10/24/2001
• Status: Expired due to Fees

• Current Assignee: Ailocom OY
• Original Assignee: Patria Ailon Oy (Almare Systems Oy)
• Inventors: Tuominen, Juha
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US09/999,412
• Publication Number:
  US 20030075670A1
• Time in Patent Office: 713 Days
• Field of Search: 250/205, 250/206, 250/214.R, 250/214.PR, 359/152, 359/154, 359/187, 359/189, 359/117, 455/69, 455/522, 455/523, 455/70, 455/92
• US Class Current: 250/205
• CPC Class Codes: H02J 50/30 using light, e.g. lasers
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• 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: H04B 10/807 Optical power feeding, i.e. transmitting power using an optical signal

Abstract

A method for wireless power transmission in a system comprising a power transmitter which in turn comprises a first light source and means for directing the light emitted by the first light source to a desired direction, and at least one power receiver comprising a first photo-detector for receiving the emitted light and for converting it into electric current. A second light source included in the power transmitter is used for transmitting light around the light emitted by the first light source and substantially parallel to it, the intensity of the light being lower than that of the light emitted by the first light source. A second photo-detector included in the power receiver is used for detecting the light emitted by the second light source and for transmitting a control signal to the power transmitter in response to a successful reception of the light emitted by the second light source. The first light source of the power transmitter is switched on in response to the reception of the control signal from the power receiver informing of the reception of the light emitted by the second light source.

Claims

1. A method for wireless power transmission in a system comprising a power transmitter which in turn comprises a first light source and means for directing the light emitted by the first light source to a desired direction, and at least one power receiver which comprises a first photo-detector for receiving the emitted light and for converting it into electric current, the method comprising the steps of

transmitting light around the light emitted by the first light source and substantially parallel to it using a second light source included in the power transmitter, the intensity of the light being substantially lower than that of the light emitted by the first light source;

detecting the light emitted by the second light source with a second photo-detector included in the power receiver;

transmitting a control signal from the power receiver to the power transmitter in response to the reception of the light emitted by the second light source; and

switching on the first light source of the power transmitter in response to the reception of the control signal from the power receiver informing of the reception of the light emitted by the second light source.

2. A method according to claim 1, comprising transmitting the control signal informing of the reception of the light emitted by the second light source from the power receiver to the power transmitter on a continuous basis,

stopping the transmission of the control signal in response to a disturbance detected in the light emitted by the second light source, and

switching off the first light source of the power transmitter.

3. A method according to claim 1, comprising transmitting the light emitted by the second light source in pulses,

stopping the transmission of the control signal in response to a time interval between two subsequent pulses received by the power receiver being equal to substantially at least twice the inverse value of the transmission frequency of the pulses.

4. A method according to claim 1, wherein the second light source comprises a plural number of separate light sources arranged substantially in a circle around the first light source.

5. A method according to claim 4, comprising combining at the power receiver the light signals emitted by the plural number of separate light sources,

stopping the transmission of the control signal in response to at least one of the light signals emitted by the separate light sources missing from the signal combined by the power receiver.

6. A method according to claim 5, wherein the combining at the power receiver is carried out as a logical AND operation.

7. A method according to claim 1, comprising

expanding the light emitted by the second light source with a beam expander.

8. A method according to claim 1, comprising deflecting the light emitted by the second light source of the power transmitter along a predetermined path in the space surrounding the power-transmitter to locate the power receivers.

9. A method according to claim 1, comprising transmitting the light of the second light source at an intensity which is substantially so low that it does not damage the eye.

10. A method according to claim 1, comprising connecting the power receiver to an external power-consuming device or charging means, such as a battery, and

conducting the electric current generated by the first photo-detector to the external power-consuming device or charging means.

11. A wireless power transmission system comprising a power transmitter, which in turn comprises a first light source and means for directing the light emitted by the first light source to a desired direction, and at least one power receiver, Which in turn comprises a first photo-detector for receiving the emitted light and for converting it into electric current, wherein

the power transmitter further comprises a second light source emitting light of a substantially lower intensity than the light emitted by the first light source, the light being arranged to be transmitted around the light emitted by first light source and substantially parallel to it;

the power receiver further comprising a second photo-detector for detecting the light emitted by the second light source and transmission means which are responsive to the detection and configured to transmit a control signal to the power transmitter in response to the reception of the light emitted by the second light source,

the power transmitter being configured to switch on the second light source first and, in response to the reception of the control signal from the power receiver informing of the reception of the light emitted by the second light source, the power transmitter is configured to switch on the first light source.

12. A system according to claim 11, wherein the power receiver is configured to transmit the control signal informing of the reception of the light emitted by the second light source to the power transmitter on a continuous basis, to stop the transmission of the control signal in response to a disturbance detected in the light emitted by the second light source, and

to switch off the first light source.

13. A system according to claim 11, wherein the light emitted by the second light source is arranged to be transmitted in pulses,

the power receiver is configured to stop the transmission of the control signal in response to the time interval between two subsequent pulses received by the power receiver being equal to at least twice the inverse value of the transmission frequency of the pulses.

14. A system according to claim 11, wherein the second light source comprises a plural number of separate light sources arranged substantially in a circle around the first light source.

15. A system according to claim 14, wherein the power receiver is configured to combine the light signals emitted by the plural number of separate light sources,

to stop the transmission of the control signal in response to at least one of the light signals emitted by the separate light sources missing from the signal combined by the power receiver.

16. A system according to claim 15, wherein the power receiver is configured to carry out the combining as a logical AND operation.

17. A system according to claim 11, wherein the light emitted by the second light source is arranged to be expanded by a beam expander.

18. A system according to claim 11, wherein the power transmitter comprises deflection means for deflecting the light emitted by the second light source along a predetermined path in the space surrounding the power transmitter to locate the power receivers.

19. A system according to claim 11, wherein the intensity of the light emitted by the second light source is substantially so low that it does not damage the eye.

20. A system according to claim 11, wherein the power receiver is configured to be connected to an external power-consuming device or charging means, such as a battery, and

the power receiver comprises conducting means for conducting the electric current generated at the first photo-detector to the external power-consuming device or charging means.

21. A system according to claim 11, wherein the light sources are lasers or light emitting diodes (LED).

22. A power transmitter for wireless power transmission, the transmitter comprising a first light source, means for directing the light emitted by the first light source to a desired direction, and a second light source, the light emitted by which is of a substantially lower intensity than that emitted by the first light source and arranged to be transmitted around the light emitted by the first light source and substantially parallel with it, wherein

the power transmitter is configured to receive an indication from the power receiver informing of the reception of the light emitted by the second light source,

the power transmitter is configured to switch on the second light source first and, in response to an indication received from the power receiver informing of the reception of the light emitted by the second light source, the power transmitter is configured to switch on the first light source.

23. A power receiver which comprises a first photo-detector for receiving light emitted by a first light source and for converting it into electric current, a second photo-detector for detecting the light emitted by a second light source, and transmission means which are responsive to said detection and configured to transmit to the power transmitter an indication informing of the reception of the light emitted by the second light source.