Systems and methods for dimming control using TRIAC dimmers

1. A system for dimming control of one or more light emitting diodes, the system comprising:

one or more signal processing components configured to receive a first signal associated with a TRIAC dimmer, process information associated with the first signal, determine whether the TRIAC dimmer is in a first condition, a second condition, or a third condition based on at least information associated with the first signal, generate a second signal based on at least information associated with the first signal, and send the second signal to a switch;

wherein the one or more signal processing components are further configured to:

if the TRIAC dimmer is determined to be in the first condition, generate the second signal to cause the switch to be opened and closed corresponding to a modulation frequency;

if the TRIAC dimmer is determined to be in the second condition, generate the second signal to cause the switch to remain closed for a first period of time until at least the TRIAC dimmer changes from the second condition to the first condition, the first period of time being larger than a modulation period corresponding to the modulation frequency; and

if the TRIAC dimmer is determined to be in the third condition, generate the second signal to cause the switch to remain open for a second period of time, the second period of time being larger than the modulation period.

2. The system of claim 1 wherein the one or more signal processing components are further configured to generate a third signal based on at least information associated with the first signal, process information associated with the third signal, and generate the second signal based on at least information associated with the third signal.

3. The system of claim 2 wherein the one or more signal processing components are further configured to, if a duty cycle of the third signal is larger than a threshold value and if the first signal is larger than a threshold signal in magnitude, determine the TRIAC dimmer to be in the first condition.

4. The system of claim 3 wherein the one or more signal processing components are further configured to, if a duty cycle of the third signal is larger than the threshold value and if the first signal is smaller than the threshold signal in magnitude, determine the TRIAC dimmer to be in the second condition.

5. The system of claim 3 wherein the one or more signal processing components are further configured to, if a duty cycle of the third signal is smaller than the threshold value, determine the TRIAC dimmer to be in the third condition.

6. The system of claim 1 wherein the one or more signal processing components include:

a first comparator configured to receive a first threshold signal and the first signal and generate a comparison signal based on at least information associated with the first threshold signal and the first signal; and

a driving component configured to receive the comparison signal, generate the second signal based on at least information associated with the comparison signal, and output the second signal to the switch.

7. The system of claim 6 wherein the one or more signal processing components further include:

a modulation component configured to receive a current sensing signal associated with a primary current flowing through a primary winding of a transformer and a third signal associated with the first signal and output a modulation signal to the driving component based on at least information associated with the current sensing signal and the third signal, the transformer further including a secondary winding and an auxiliary winding;

wherein the modulation component is further configured to:

if the current sensing signal is larger than the third signal in magnitude, generate the modulation signal at a first logic level to cause the switch to be opened; and

if the current sensing signal is smaller than the third signal in magnitude, generate the modulation signal at a second logic level to cause the switch to be closed.

8. The system of claim 7 wherein the one or more signal processing components further include:

a multiplexer configured to receive the first signal and a fourth signal and generate a fifth signal based on at least information associated with the first signal and the fourth signal; and

an offset component configured to receive the fifth signal and output the third signal by adding a predetermined offset to the fifth signal to keep the third signal no smaller than the current sensing signal in magnitude when the TRIAC dimmer is in the second condition.

9. The system of claim 7 wherein the one or more signal processing components further include:

a second comparator configured to receive the current sensing signal and a second threshold signal and output a fourth signal to the driving component based on at least information associated with the current sensing signal and the second threshold signal;

wherein the second comparator is further configured to, if the current sensing signal is smaller than the second threshold signal in magnitude, generate the fourth signal at a third logic level to cause the switch to be closed.

10. The system of claim 7 wherein the one or more signal processing components further include a multiplexer configured to receive the first signal and a fourth signal and output the third signal to the modulation component based on at least information associated with the first signal and the fourth signal.

11. The system of claim 10 wherein the one or more signal processing components further include a current regulation component configured to receive the current sensing signal and output a processed signal to the multiplexer based on at least information associated with the current sensing signal.

12. The system of claim 7 wherein the one or more signal processing components further include a second comparator configured to receive a fourth signal associated with the auxiliary winding and a second threshold signal and output a fifth signal to the driving component based on at least information associated with the fourth signal and the second threshold signal, the fifth signal indicating whether a demagnetization process associated with the transformer has completed.

13. A method for dimming control of one or more light emitting diodes, the method comprising:

receiving a first signal associated with a TRIAC dimmer;

processing information associated with the first signal;

determining whether the TRIAC dimmer is in a first condition, a second condition, or a third condition based on at least information associated with the first signal;

generating a second signal based on at least information associated with the first signal; and

outputting the second signal to a switch;

wherein the process for generating a second signal based on at least information associated with the first signal includes:

if the TRIAC dimmer is determined to be in the first condition, generating the second signal to cause the switch to be opened and closed corresponding to a modulation frequency;

if the TRIAC dimmer is determined to be in the second condition, generating the second signal to cause the switch to remain closed for a first period of time until at least the TRIAC dimmer changes from the second condition to the first condition, the first period of time being larger than a modulation period corresponding to the modulation frequency; and

if the TRIAC dimmer is determined to be in the third condition, generating the second signal to cause the switch to remain open for a second period of time, the second period of time being larger than the modulation period.

14. The method of claim 13 , and further comprising:

generating a third signal based on at least information associated with the first signal;

processing information associated with the third signal; and

generating the second signal based on at least information associated with the third signal.

15. The method of claim 14 wherein the process for determining whether the TRIAC dimmer is in a first condition, a second condition, or a third condition includes, if a duty cycle of the third signal is larger than a threshold value and if the first signal is larger than a threshold signal in magnitude, determining the TRIAC dimmer to be in the first condition.

16. The method of claim 15 wherein the process for determining whether the TRIAC dimmer is in a first condition, a second condition, or a third condition includes, if a duty cycle of the third signal is larger than the threshold value and if the first signal is smaller than the threshold signal in magnitude, determining the TRIAC dimmer to be in the second condition.

17. The method of claim 16 wherein the process for determining whether the TRIAC dimmer is in a first condition, a second condition, or a third condition includes, if a duty cycle of the third signal is smaller than the threshold value, determining the TRIAC dimmer to be in the third condition.