Light Emitting Diode Based Lighting System With Time Division Ambient Light Feedback Response

• US 20100171442A1
• Filed: 06/30/2009
• Published: 07/08/2010
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Draper, William A., Melanson, John L.
• Granted Patent: US 8,362,707 B2
• Time in Patent Office: Days
• US Class Current: 315/297
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/28 using temperature feedback
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: H05B 47/175 by remote control
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A lighting system includes time division light output sensing and adjustment for ambient light. In at least one embodiment, time division light output sensing involves modulating power to a light emitting diode (LED) set, and the set of LEDs includes one or more LEDs. In at least one embodiment, each LED in the LED set is included in a single lamp, and, in at least one embodiment, the set of LEDs is contained in multiple lamps. In at least one embodiment, for each lamp, a controller modulates power to the LED set by selectively reducing power to the LED set using time division algorithm to allow a light sensor to sense the brightness of ambient light with a reduced contribution from the LED set. In at least one embodiment, a lighting system also includes time division light output sensing and adjustment for different spectra LEDs.

Claims

1. An apparatus comprising:

a controller configured to couple to a sensor and a first light emitting diode (LED) of a lamp, wherein the controller is further configured to;

i. reduce power to a first light emitting diode (LED) coupled to the controller;

ii. receive a signal from a sensor indicating a brightness of light received by the sensor while the power to the first LED is reduced; and

iii. adjust the brightness of the first LED in accordance with a brightness related target value.

2. The apparatus of claim 1 wherein the controller is configured to reduce the power to the first LED to zero.

3. The apparatus of claim 1 wherein the controller is configured to reduce the power to the first LED to a value greater than zero.

4. The apparatus of claim 1 wherein reducing power to the first LED comprises reducing current to the first LED.

5. The apparatus of claim 1 wherein the controller is further configured to synchronize multiple controllers, wherein each of the multiple controllers is configured to:

i. reduce power to an LED coupled to the controller during a same period of time as a reduction in power to LEDs coupled to each of the other controllers;

ii. receive a signal from a sensor indicating a brightness of light received by the sensor while the power to the LED coupled to the controller is reduced; and

iii. adjust the brightness of the LED coupled to the controller in accordance with a brightness related target value.

6. The apparatus of claim 1 wherein the controller is further configured to:

i. receive a first signal indicating a brightness of received light at a first time;

ii. receive a second signal indicating a brightness of the received light at a second time, wherein a relative contribution to the brightness from the first and second LEDs is different for the first and second times and wherein the light emitted from the first LED has a different spectrum than the light emitted from the second LED;

iii. determine the brightness of light emitted from the first LED and the brightness of light emitted from the second LED using information from the signals; and

iv. adjust the brightness of the light emitted from the first LED and the brightness of the light emitted from the second LED in accordance with one or more brightness related target values.

7. The apparatus of claim 6 wherein the first and second LEDs are members of groups consisting of:

red and green, red and yellow, amber and blue, green and blue, and red and blue.

8. The apparatus of claim 6 wherein the first LED is a member of a first set of multiple LEDs having approximately identical spectra and the second LED is a member of a second set of multiple LEDs having approximately identical spectra.

9. The apparatus of claim 6 wherein the controller is further configured to:

adjust the brightness of the first and second LEDs to compensate for at one of (a) LED heating and (b) light output changes over time.

10. The apparatus of claim 6 wherein at least one of the sensors is a broad spectrum sensor.

11. The apparatus of claim 10 wherein a single, broad spectrum sensor provides the signals indicating brightness at the first and second times.

12. The apparatus of claim 6 wherein the controller is further configured to:

modulate current to the first and second LEDs so that the relative contribution to the brightness of the light received by the one or more sensors is different for the first and second times.

13. The apparatus of claim 12 wherein to modulate current to the first and second LEDs comprises:

reducing current to the first LED to zero while providing current to the second LED during the first time; and

reducing current to the second LED to zero while providing current to the first LED during the second time.

14. The apparatus of claim 12 wherein to modulate current to the first and second LEDs comprises:

providing less average current to the first LED than the second LED during the first time and providing less average current to the first LED than the second LED during the first time.

15. The apparatus of claim 12 wherein to modulate current to the first and second LEDs comprises:

modulating current to the first and second LEDs during sequential times.

16. The apparatus of claim 12 wherein to modulate current to the first and second LEDs comprises:

interspersing reductions in current to the first and second LEDs over time.

17. An apparatus comprising:

a lamp having at least a first light emitting diode (LED);

a sensor to sense brightness of received light; and

a controller coupled to the lamp and the sensor, wherein the controller is configured to;

i. reduce power to the first LED;

ii. receive a signal from the sensor indicating the brightness of light received by the sensor while the power to the first LED is reduced; and

iii. adjust the brightness of the first LED in accordance with a brightness related target value.

18. The apparatus of claim 17 wherein the controller is configured to reduce the power to the first LED to zero.

19. The apparatus of claim 17 wherein the controller is configured to reduce the power to the first LED to a value greater than zero.

20. The apparatus of claim 17 wherein reducing power to the first LED comprises reducing current to the first LED.

21. The apparatus of claim 17 wherein the controller is further configured to synchronize multiple controllers, wherein each of the multiple controllers is configured to:

i. reduce power to an LED coupled to the controller during a same period of time as a reduction in power to LEDs coupled to each of the other controllers;

ii. receive a signal from a sensor indicating a brightness of light received by the sensor while the power to the LED coupled to the controller is reduced; and

iii. adjust the brightness of the LED coupled to the controller in accordance with a brightness related target value.

22. The apparatus of claim 17 wherein the controller is further configured to:

i. receive a first signal indicating a brightness of received light at a first time;

ii. receive a second signal indicating a brightness of the received light at a second time, wherein a relative contribution to the brightness from the first and second LEDs is different for the first and second times and wherein the light emitted from the first LED has a different spectrum than the light emitted from the second LED;

iii. determine the brightness of light emitted from the first LED and the brightness of light emitted from the second LED using information from the signals; and

iv. adjust the brightness of the light emitted from the first LED and the brightness of the light emitted from the second LED in accordance with one or more brightness related target values.

23. A method for light harvesting, the method comprising:

reducing power to a first light emitting diode (LED);

receiving a signal indicating a brightness of light while the power to the first LED is reduced; and

adjusting the brightness of the first LED in accordance with a brightness related target value.

24. The method of claim 23 wherein the controller is configured to reduce the power to the first LED to zero.

25. The method of claim 23 wherein the controller is configured to reduce the power to the first LED to a value greater than zero.

26. The method of claim 23 wherein reducing power to the first LED comprises reducing current to the first LED.

27. The method of claim 23 further comprising:

operating multiple controllers in synchronization, wherein operating multiple controllers in synchronization comprises;

reducing power to an LED coupled to the controller during a same period of time as a reduction in power to LEDs coupled to each of the other controllers;

receiving a signal from a sensor indicating a brightness of light received by the sensor while the power to the LED coupled to the controller is reduced; and

adjusting the brightness of the LED coupled to the controller in accordance with a brightness related target value.

28. The method of claim 23 further comprising:

receiving a first signal indicating a brightness of received light at a first time;

receiving a second signal indicating a brightness of the received light at a second time, wherein a relative contribution to the brightness from the first and second LEDs is different for the first and second times and wherein light emitted from the first LED has a different spectrum than the light emitted from the second LED;

determining the brightness of light emitted from the first LED and the brightness of light emitted from the second LED using information from the signals; and

adjusting the brightness of the light emitted from the first LED and the brightness of the light emitted from the second LED in accordance with one or more brightness related target values.

29. The method of claim 28 wherein the first and second LEDs are members of groups consisting of:

red and green, red and yellow, amber and blue, green and blue, and red and blue.

30. The method of claim 28 wherein the first LED is a member of a first set of multiple LEDs having approximately identical spectra and the second LED is a member of a second set of multiple LEDs having approximately identical spectra.

31. The method of claim 28 further comprising:

adjusting the brightness of the first and second LEDs to compensate for at one of (a) LED heating and (b) light output changes over time.

32. The method of claim 28 wherein at least one of the sensors is a broad spectrum sensor.

33. The method of claim 32 wherein a single, broad spectrum sensor provides the signals indicating brightness at the first and second times.

34. The method of claim 28 further comprising:

modulating current to the first and second LEDs so that the relative contribution to the brightness of the light received by the one or more sensors is different for the first and second times.

35. The method of claim 34 wherein modulating current to the first and second LEDs comprises:

reducing current to the first LED to zero while providing current to the second LED during the first time; and

reducing current to the second LED to zero while providing current to the first LED during the second time.

36. The method of claim 34 wherein modulating current to the first and second LEDs comprises:

providing less average current to the first LED than the second LED during the first time and providing less average current to the first LED than the second LED during the first time.

37. The method of claim 34 wherein modulating current to the first and second LEDs comprises:

modulating current to the first and second LEDs during sequential times.

38. The method of claim 34 wherein to modulate current to the first and second LEDs comprises:

interspersing reductions in current to the first and second LEDs over time.

39. An apparatus for light harvesting comprising:

means for reduce power to a first light emitting diode (LED);

means for receiving a signal indicating a brightness of light while the power to the first LED is reduced; and

means for adjusting the brightness of the first LED in accordance with a brightness related target value.