Systems and methods for visible light communication

• US 20110069960A1
• Filed: 08/05/2010
• Published: 03/24/2011
• Est. Priority Date: 09/05/2008
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Ketra, Inc. (Lutron Electronics)
• Inventors: Ho, Horace C., Knapp, David J.
• Granted Patent: US 8,521,035 B2
• Time in Patent Office: Days
• US Class Current: 398/103
• CPC Class Codes: H04L 12/43 with synchronous transmission, e.g. time division multiplex [TDM], slotted rings
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085
• CPC Class Codes: H04L 2012/40273 the transportation system being a vehicle

Abstract

Systems and methods for visible light communication are disclosed. In part, illumination devices and related systems and methods are disclosed that can be used for general illumination, lighting control systems, or other applications. The illumination devices synchronize preferentially to the AC mains to produce time division multiplexed channels in which control information can be communicated optically by the same light source that is producing illumination. Such illumination devices preferentially comprise LEDs for producing illumination, transmitting data, detecting ambient light, and receiving data, however, other light sources and detectors can be used. The physical layer can be used with a variety of protocols, such as ZigBee, from the Media ACcess (MAC) layer and higher.

Claims

1. An illumination device, comprising:

a light source;

a light detector; and

a controller configured to receive data optically in synchronization with a second illumination device using the light detector.

2. The illumination device as recited in claim 1, wherein the controller is further configured to transmit data optically in synchronization with the second illumination device.

3. The illumination device as recited in claim 2, wherein the light source comprises one or more light source LEDs, and wherein at least one of the light source LEDs is configured to be used to transmit data optically.

4. The illumination device as recited in claim 3, wherein the light detector comprises one or more detector LEDs, and wherein at least one of the detector LEDs is configured to be used to receive data.

5. The illumination device as recited in claim 4, wherein at least one of the light source LEDs is also configured to be used as a detector LED.

6. The illumination device as recited in claim 1, wherein the illumination device is coupled to an AC mains and wherein the illumination device is configured to synchronize with the second illumination device using the AC mains.

7. The illumination device as recited in claim 6, wherein the light source is configured to periodically turned off in synchronization with the AC mains to produce a time slot for communicating data.

8. The illumination device as recited in claim 7, wherein the light source comprises one or more LEDs.

9. The illumination device as recited in claim 8, wherein at least one of the one or more LEDs is also configured to receive optical data during the time slot as the light detector.

10. The illumination device as recited in claim 7, further comprising a silicon photodiode, the silicon photodiode being configured to receive optical data during the time slot as the light detector.

11. The illumination device as recited in claim 8, wherein the controller is further configured to transmit data optically in synchronization with the second illumination device using the light source, and wherein at least one of the one or more LEDs is also configured to be used to transmit data optically during the time slot.

12. The illumination device as recited in claim 7, wherein the light detector is configured to be used to measure ambient light during the time slot.

13. The illumination device as recited in claim 12, wherein a plurality of ambient light measurements are made in a plurality of time slots, and wherein ambient light measurements from previous time slots are subtracted from current measurements.

14. The illumination device as recited in claim 12, wherein a brightness of the light source is configured to be adjusted based upon the ambient light measurements.

15. The illumination device as recited in claim 7, further comprising a phase locked loop (PLL) configured to phase lock to the AC mains.

16. The illumination device as recited in claim 15, wherein the PLL is configured to produce a bit clock, the bit block being used to provide timing for communicating data in the time slot.

17. The illumination device as recited in claim 16, further comprising a physical layer interface (PLI) configured to transmit data, the PLI being further configured to transmit data bits in synchronization with the bit clock during the time slot.

18. The illumination device as recited in claim 16, further comprising a physical layer interface (PLI) configured to receive data, the PLI being further configured to receive data bits in synchronization with the bit clock during the time slot.

19. The illumination device as recited in claim 7, wherein the light source is further configured to be turned off in synchronization with the AC mains with a phase different from the time slot to produce a second communication channel.

20. The illumination device as recited in claim 19, wherein the light source is further configured to be turned off in synchronization with the AC mains with different phase differences from the time slot so as to produce three or more different communication channels with phases relative to the AC mains different from each other.

21. The illumination device as recited in claim 9, further comprising a resistor coupled across a cathode and an anode for the at least one LED, the resistor being configured to produce a voltage from incident light.

22. The illumination device as recited in claim 21, further comprising a plurality of serially connected LEDs and resistors configured to provide a larger magnitude voltage from incident light than would be produced by a single LED and resistor.

23. The illumination device as recited in claim 22, wherein the incident light is ambient light.

24. The illumination device as recited in claim 22, wherein the incident light comprises light modulated with data.

25. A system, comprising:

a first illumination device having a controller configured to communicate data optically; and

a second illumination device having a controller configured to communicate data optically;

wherein the first and second illumination devices are configured to communicate data optically in synchronization with each other.

26. The system as recited in claim 25, wherein the first and second illumination devices are coupled to an AC mains, wherein the first illumination device comprises a first light source, wherein the second illumination device comprises a second light source, and wherein the first and second illumination devices are configured to periodically turn off the first light source and the second light source in synchronization with the AC mains to produce a first time slot for communicating data.

27. The system as recited in claim 26, wherein at least the first light source or the second light source comprises an LED.

28. The system as recited in claim 27, wherein the LED is also configured to transmit data.

29. The system as recited in claim 28, wherein at least the first illumination device or the second illumination device further comprises a photodiode, the photodiode being configured to receive optically transmitted data.

30. The system as recited in claim 27, wherein the LED is configured to receive optically transmitted data.

31. The system as recited in claim 26, further comprising a first phase locked loop (PLL) within the first illumination device and a second PLL in the second illumination device, the first and second PLLs being configured to lock to the AC mains.

32. The system as recited in claim 26, wherein the first and second illumination devices are each configured to synchronize bit timing of data communications to the AC mains.

33. The system as recited in claim 26, further comprising a third illumination device and a fourth illumination device configured to communicate data optically in synchronization with each other, wherein the third and fourth illumination devices are coupled to an AC mains, wherein the third illumination device comprises a third light source, wherein the fourth illumination device comprises a fourth light source, and wherein the third and fourth illumination devices are configured to periodically turn off the third light source and the fourth light source in synchronization with the AC mains to produce a second time slot for communicating data that is non-overlapping with the first time slot.

34. The system as recited in claim 33, wherein the first and second illumination devices are configured to communicate optical data during the first time slot and the third and fourth illumination devices are configured to communicate optical data during the second time slot.

35. A method for data communication between illumination devices, comprising:

providing a first illumination device and a second illumination device;

optically communicating data between the first illumination device and the second illumination device in synchronization with each other.

36. The method as recited in claim 35, periodically turning off a first light source within the first illumination device and a second light source within the second illumination device in synchronization with the AC mains to produce a first time slot for communicating data between the first and second illumination devices.

37. The method as recited in claim 36, wherein at least the first light source or the second light source comprises an LED.

38. The method as recited in claim 37, further comprising transmitting data with the LED.

39. The method as recited in claim 38, wherein at least the first light source or the second light source comprises a photodiode, and further comprising receiving optically transmitted data using the photodiode.

40. The method as recited in claim 37, further comprising receiving optically transmitted data using the LED.

41. The method as recited in claim 36, further comprising utilizing a first phase locked loop (PLL) within the first illumination device to lock to the AC mains and utilizing a second PLL within the second illumination device to lock to the AC mains.

42. The method as recited in claim 36, further comprising synchronizing bit timing of data communications between the first and second illumination devices to the AC mains.

43. The method as recited in claim 36, further comprising providing a third illumination device and a fourth illumination device, optically communicating data between the third illumination device and the fourth illumination device in synchronization with each other, and periodically turning off a third light source within the third illumination device and a fourth light source within the fourth illumination device in synchronization with the AC mains to produce a second time slot for communicating data that is non-overlapping with the first time slot.

44. The method as recited in claim 43, further comprising communicating optical data between the first and second illumination devices during the first time slot and communicating optical data between the third and fourth illumination devices during the second time slot.