Dimmable light emitting diode lighting system

• US 8,860,326 B2
• Filed: 03/12/2013
• Issued: 10/14/2014
• Est. Priority Date: 03/21/2012
• Status: Active Grant

• Current Assignee: Electronic Theatre Controls Incorporated
• Original Assignee: Electronic Theatre Controls Incorporated
• Inventors: Cahalane, David J., Bokelman, Joseph R.
• Primary Examiner(s): TRAN, THUY V
• Application Number:
  US13/795,233
• Publication Number:
  US 20130249405A1
• Time in Patent Office: 581 Days
• Field of Search: 315/185.R, 315/246, 315/291
• US Class Current: 315/291
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/60 Circuit arrangements for operating LEDs comprising organic material, e.g. for operating organic light-emitting diodes [OLED] or polymer light-emitting diodes [PLED]

Abstract

An LED lighting system including a first group of LEDs, a second group of LEDs, and a controller. The first group of LEDs and the second group of LEDs are configured to be independently driven by a first LED drive signal and a second LED drive signal, respectively. The controller is configured receive a dimming signal from a dimmer having a preheat function. The controller is also configured to compensate the dimming signal for the preheat function of the dimmer to generate a compensated dimming signal, generate the first LED drive signal based on the compensated dimming, and generate the second LED drive signal based on the compensated dimming signal. The first LED drive signal is then transmitted the first group of LEDs and the second LED drive signal is transmitted to the second group of LEDs.

Claims

1. A light-emitting diode (“

LED”

) lighting system comprising;

a dimmer having a preheat function and configured to generate a dimming signal;

a first group of LEDs and a second group of LEDs, the first group of LEDs and the second group of LEDs configured to be independently driven by a first LED drive signal and a second LED drive signal, respectively;

a dimming controller configured to

receive the dimming signal from the dimmer, and

generate a first pulse-width modulated (“

PWM”

) signal based on the dimming signal, the first PWM signal having a first duty cycle;

a software controller in electrical communication with the dimming controller, the software controller configured to

receive the first PWM signal from the dimming controller,

compensate the first PWM signal for the preheat function of the dimmer to generate a second PWM signal, the second PWM signal having a second duty cycle, the second duty cycle being different than the first duty cycle; and

an LED driver module configured to

receive the second PWM signal,

generate the first LED drive signal based on the second PWM signal, the first LED drive signal associated with a drive level of the first group of LEDs,

generate the second LED drive signal based on the second PWM signal, the second LED drive signal associated with a drive level of the second group of LEDs, and

transmit the first LED drive signal to the first group of LEDs and the second LED drive signal to the second group of LEDs.

2. The lighting system of claim 1, wherein the first group of LEDs and the second group of LEDs are located in a first lighting fixture.

3. The lighting system of claim 1, wherein the second duty cycle is lower than the first duty cycle.

4. The lighting system of claim 1, wherein the LED drive module is further configured to determine whether the second PWM signal corresponds to a dimming level above a threshold dimming level.

5. The lighting system of claim 4, wherein the first LED drive signal and the second LED drive signal are different when the second PWM signal corresponds to a dimming level above the threshold dimming level.

6. A light-emitting diode (“

LED”

) lighting system comprising;

a first group of LEDs and a second group of LEDs, the first group of LEDs and the second group of LEDs configured to be driven by a first LED drive signal and a second LED drive signal, respectively; and

a controller in electrical communication with the first group of LEDs and the second group of LEDs, the controller configured to

receive a dimming signal associated with a dimmer, the dimmer having a preheat function,

compensate the dimming signal for the preheat function of the dimmer to generate a compensated dimming signal,

generate the first LED drive signal based on the compensated dimming signal, the first LED drive signal associated with a drive level of the first group of LEDs,

generate the second LED drive signal based on the compensated dimming signal, the second LED drive signal associated with a drive level of the second group of LEDs, and

transmit the first LED drive signal to the first group of LEDs and the second LED drive signal to the second group of LEDs.

7. The lighting system of claim 6, wherein the first group of LEDs and the second group of LEDs are located in a first lighting fixture.

8. The lighting system of claim 6, wherein the controller is further configured to determine whether the compensated dimming signal corresponds to a dimming level above a threshold dimming level.

9. The lighting system of claim 8, wherein the first LED drive signal and the second LED drive signal are different when the compensated dimming signal corresponds to a dimming level above the threshold dimming level.

10. The lighting system of claim 8, wherein the threshold dimming level is between approximately 80% dimming and 100% dimming.

11. The lighting system of claim 6, wherein the controller includes a first LED drive module and a second LED drive module.

12. The lighting system of claim 11, wherein the first LED drive module generates the first LED drive signal and the second LED drive module generates the second LED drive signal.

13. A method of controlling dimming in a light-emitting diode (“

LED”

) lighting system, the method comprising;

receiving a dimming signal;

generating a first pulse-width modulated (“

PWM”

) signal based on the dimming signal, the first PWM signal having a first duty cycle;

compensating the first PWM signal for a preheat function of a dimmer to generate a second PWM signal, the second PWM signal having a second duty cycle, the second duty cycle being different than the first duty cycle;

generating a first LED drive signal based on the second PWM signal, the first LED drive signal associated with a drive level of a first group of LEDs;

generating a second LED drive signal based on the second PWM signal, the second LED drive signal associated with a drive level of a second group of LEDs; and

transmitting the first LED drive signal to the first group of LEDs and the second LED drive signal to the second group of LEDs.

14. The method of claim 13, wherein the dimming signal includes a first half-cycle and a second half-cycle, and wherein the first half-cycle and the second half-cycle are independently controlled.

15. The method of claim 13, wherein the second duty cycle is lower than the first duty cycle.

16. The method of claim 13, further comprising determining whether the second PWM signal corresponds to a dimming level above a threshold dimming level.

17. The method of claim 16, wherein the first LED drive signal and the second LED drive signal are different when the second PWM signal corresponds to a dimming level above the threshold dimming level.

18. The method of claim 16, wherein the threshold dimming level is between approximately 80% dimming and 100% dimming.

19. The method of claim 13, further comprising generating a third LED drive signal based on the second PWM signal, the third LED drive signal associated with a drive level of a third group of LEDs.

20. The method of claim 19, further comprising transmitting the third LED drive signal to the third group of LEDs, the third group of LEDs located in the first lighting fixture.