System and Method For Controlling an Output Illumination Level of a Lighting System

• US 20110001435A1
• Filed: 04/09/2010
• Published: 01/06/2011
• Est. Priority Date: 04/09/2009
• Status: Active Grant

• Current Assignee: USAI, LLC
• Original Assignee: USAI, LLC
• Inventors: Wray, Donald L.
• Granted Patent: US 8,525,432 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A method of controlling a brightness level of an LED by supplying power to an LED in series with a field effect transistor and a resistor. A first voltage is supplied from a digital potentiometer to an operational amplifier. The field effect transistor is activated based on the first voltage from the operational amplifier and a second voltage is varied across the resistor when the field effect transistor is activated. The varying of the second voltage across the resistor causes a change in the brightness level of the LED.

Claims

1. A system for controlling a brightness level of a Light Emitting Diode comprising:

a Light Emitting Diode (LED);

said LED connected in series with a field effect transistor and a resistor;

a digital potentiometer;

said digital potentiometer supplying a variable output voltage to an operational amplifier;

said operational amplifier connected to said field effect transistor to activate said field effect transistor;

a power supply connected to said LED;

wherein said activation of said field effect transistor by said operational amplifier varies a voltage across said resistor adjusting the brightness level of said LED.

2. The system of claim 1, wherein said variable output voltage of said digital potentiometer can be varied by up to 256 steps.

3. The system of claim 2, wherein a microcontroller varies said output steps of said digital potentiometer.

4. The system of claim 3, wherein said microcontroller is connected to a transceiver.

5. The system of claim 4, wherein said microcontroller includes an EEPROM which can be programmed by said transceiver.

6. The system of claim 4, wherein said transceiver is connected to a network to allow remote control of said transceiver.

7. The system of claim 6, wherein a remote user can update a program or a firmware installed in said microcontroller.

8. The system of claim 1 wherein a DMX control protocol is used to control said brightness of said LED

9. The system of claim 1 further comprising a further LED.

10. The system of claim 9 further comprising a further field effect transistor, resistor, operational amplifier and digital potentiometer.

11. The System of claim 1, wherein said digital potentiometer is connected to a negative side of said resistor and to an output of a second operational amplifier to swamp an error of said digital potentiometer.

12. A method of controlling a brightness level of an LED comprising the steps of:

supplying power to an LED;

the LED being in series with a field effect transistor and a resistor;

supplying a first voltage from a digital potentiometer to an operational amplifier;

activating the field effect transistor based on the first voltage from the operational amplifier;

varying a second voltage across the resistor when the field effect transistor is activated;

wherein the varying of the second voltage across the resistor changes the brightness level of the LED.

13. The method of claim 12, wherein the first voltage from the digital potentiometer can vary by up to 256 steps.

14. The method of claim 13, wherein a microcontroller varies the voltage steps from the digital potentiometer.

15. The method of claim 14, wherein the microcontroller is connected to a transceiver.

16. The method of claim 15, wherein the transceiver is connected to a network to allow remote control of the transceiver.

17. The method of claim 16, wherein a remote user can update a program or a firmware installed in the microcontroller.

18. The method of claim 12, wherein the operational amplifier compares the first voltage from the digital potentiometer to a voltage supplied from a source of the field effect transistor to provide a stabilized output of the operational amplifier.

19. The method of claim 12 further comprising controlling a brightness of a further LED.

20. The method of claim 19 further comprising a further field effect transistor, resistor, operational amplifier and digital potentiometer.

21. The method of claim 12, wherein a DMX control protocol is used to control the brightness of the LED

22. A method of controlling a brightness level of an LED comprising the steps of:

supplying power to an LED;

the LED being in series with a field effect transistor and a resistor;

supplying a first voltage from a digital potentiometer to a first operational amplifier;

activating the field effect transistor based on the first voltage from the first operational amplifier;

wherein the varying of the second voltage across the resistor changes the brightness level of the LED.

varying a second voltage across the resistor when the field effect transistor is activated;

outputting a third voltage from a second operational amplifier and a voltage from a negative side of the resistor to an input of the digital potentiometer to swamp the error of the digital potentiometer.

23. The method of claim 22, wherein the first voltage from the digital potentiometer can vary by up to 256 steps.

24. The method of claim 23, wherein a microcontroller varies the voltage steps from the digital potentiometer.

25. The method of claim 24, wherein the microcontroller is connected to a transceiver.

26. The method of claim 25, wherein the transceiver is connected to a network to allow remote control of the transceiver.

27. The method of claim 26, wherein a remote user can update a program or a firmware installed in the microcontroller.

28. The method of claim 22 further comprising controlling a brightness of a further LED.

29. The method of claim 28 further comprising a further field effect transistor, resistor, operational amplifier and digital potentiometer.

30. The method of claim 22, wherein a DMX control protocol is used to control the brightness of the LED

31. The method of claim 22, wherein the operational amplifier compares the first voltage from the digital potentiometer to a voltage supplied from a source of the field effect transistor to provide a stabilized output of the operational amplifier.

32. A system for controlling an output illumination level of a lighting system comprising:

a power source;

an illumination device coupled to said power source;

a voltage converter coupled to said illumination device;

a load coupled to said voltage converter;

a controller coupled to said power source and said switching device;

said controller providing a variable voltage to said load such that a total current passing through said illumination device varies; and

wherein the output illumination level of said illumination device varies according to the variable current passing through said illumination device.

33. The system according to claim 32, wherein said illumination device is an LED.

34. The system according to claim 32, wherein said load is a resistor.

35. The system according to claim 32, wherein said switch is one of at least a Bipolar transistor, JFET, MOSFET, DEPFET, DGMOSFET, DNAFET, FREDFET, HEMT, IGBT, ISFET, MESFET, MODFET, NOMFET and a OFET.

36. The system according to claim 32, wherein said controller is a microcontroller.

37. The system according to claim 36, further comprising a digital potentiometer coupled to said microcontroller.

38. The system according to claim 32 wherein said voltage converter comprises a voltage to current converter.