Methods and apparatus for lifetime extension of LED-based lighting units
Methods and apparatus for lighting control. One or more properties of light output of one or more LEDs ( 124 A, 124 B, 124 C, 124 N) of an LED node ( 120 A, 120 B, 120 C, 120 N) of an LED-based lighting unit ( 110 ) are controlled to extend the lifetime of the LED-based lighting unit. For example, an LED node controller controlling an LED may determine whether the LED will be operated in the active light emitting state based on an LED activation probability. Thus, based on the LED activation probability the LED may at some times be in the active light emitting state and provide light output and may at other times be prevented from being in the active light emitting state and prevented from providing light output.
1. A lighting system, comprising:
a plurality of LED nodes, each of the LED nodes including an LED node controller and at least one LED controlled by the LED node controller,
each said LED node controller:
selectively enabling the at least one controlled LED to be in an active light emitting state and selectively preventing the at least one controlled LED from being in the active light emitting state;
controlling the at least one controlled LED based on control parameters, the control parameters including an LED activation probability and at least one first parameter assigned to the at least one controlled LED, and the controlling including determining whether the at least one LED is in the active light emitting state based on the LED activation probability;
configured to receive an external light level input providing an indication of a desired level of light output; and
determining at least one of the control parameters based on the external light level input,
wherein each of said LED controllers is configured to perform said selectively enabling in response to determining that said at least one first parameter matches a randomized parameter that is provided by at least one random parameter generator, wherein a probability that the at least one first parameter matches the randomized parameter is said LED activation probability.
2. The system of claim 1 , wherein the at least one of the control parameters determined based on the light level input includes the LED activation probability and the at least one first parameter.
3. The system of claim 2 , wherein the LED activation probability is proportional to the desired level of light output indicated by the light level input.
4. The system of claim 2 , wherein the light level input is pulse width modulated input and the indication of the desired level of light output is based on the duty cycle of the pulse width modulated input, wherein the system further comprises an LED driver providing the pulse width modulated input to each said LED node controller.
5. The system of claim 2 , wherein one or more said LED node controllers each further:
determines, based on the light level input, a number of LED nodes in an LED node cluster including the LED node of the LED node controller and one or more additional LED nodes;
determines, based on the light level input, a number of LEDs in the LED node cluster to activate; and
ensures the number of LEDs in the LED node cluster are activated.
6. The system of claim 5 , wherein the number of the one or more LEDs of the LED node cluster to activate is proportional to the desired level of light output.
7. The system of claim 1 , wherein the at least one of the control parameters determined based on the light level input includes an LED light output level of the at least one controlled LED.
8. The system of claim 1 , wherein each LED node controller determines each time the external light level input is cycled, whether the at least one controlled LED will be in the active light emitting state based on the LED activation probability.
9. The system of claim 1 , wherein the light level input is provided via a power input utilized to power the LEDs of the LED nodes.
10. A method of controlling an LED of an LED node, comprising:
receiving an external light level input providing an indication of a desired level of light output;
determining one or more control parameters of the LED of the LED node based on the light level input;
determining an LED activation probability of the control parameters, the LED activation probability indicative of a probability the LED of the LED node will be in a light-emitting state;
assigning at least one first parameter to the LED; and
controlling the LED of the LED node based on the control parameters, the controlling including determining whether the LED will be in the light-emitting state based on the LED activation probability, wherein the controlling includes activating the LED in response to determining that said at least one first parameter matches a randomized parameter that is provided by at least one random parameter generator, wherein a probability that the at least one first parameter matches the randomized parameter is said LED activation probability.
11. The method of claim 10 , wherein determining one or more control parameters of the LED of the LED node based on the light level input includes determining the LED activation probability and the at least one first parameter based on the light level input.
12. The method of claim 11 , wherein the determined LED activation probability is proportional to the desired level of light output indicated by the light level input.
13. The method of claim 11 , wherein the light level input is pulse width modulated input and the indication of the desired level of light output is based on the duty cycle of the pulse width modulated input.
14. The method of claim 11 , further comprising:
determining, based on the light level input, a number of LED nodes in an LED node cluster including the LED node and one or more additional LED nodes;
determining, based on the light level input, a number of LEDs in the LED node cluster to activate; and
ensuring the number of the LEDs of the LED node cluster are activated.
15. The method of claim 14 , wherein the determined number of the one or more LEDs in the LED node cluster to activate is inversely proportional to the desired level of light output.
16. The method of claim 10 , wherein determining one or more control parameters of the LED of the LED node based on the light level input includes determining an LED light output level of the at least one controlled LED based on the light level input.
17. The method of claim 16 , wherein the LED activation probability is a fixed probability.
18. The method of claim 10 , further comprising determining, each time the external light level input is cycled, whether the at least one controlled LED will be in the active light emitting state based on the LED activation probability.
19. The method of claim 10 , further comprising determining, each time an occurrence is received, whether the at least one controlled LED will be in the active light emitting state based on the LED activation probability.
20. A lighting system, comprising:
a plurality of LED nodes, each of the LED nodes including an LED node controller and at least one LED controlled by the LED node controller,
each said LED node controller:
selectively enabling the at least one controlled LED to be in an active light emitting state and selectively preventing the at least one controlled LED from being in the active light emitting state:
controlling the at least one controlled LED based on one or more control parameters, the control parameters including an LED activation probability and the controlling including determining whether the at least one LED is in the active light emitting state based on the LED activation probability;
configured to receive an external light level input providing an indication of a desired level of light output; and
determining at least one of the control parameters based on the external light level input,
wherein at least a subset of said LED node controllers are configured to alternately activate same LEDs of said controlled LEDs multiple times to implement a same total light level output by the system.