Control system for fluorescent light fixture

• US 20060232213A1
• Filed: 07/26/2005
• Published: 10/19/2006
• Est. Priority Date: 04/18/2005
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell Semiconductor (Marvell Technology Group Limited)
• Inventors: Sutardja, Sehat
• Granted Patent: US 7,414,369 B2
• Time in Patent Office: Days
• US Class Current: 315/46
• CPC Class Codes: H05B 41/046 using controlled semiconductor devices
• CPC Class Codes: H05B 41/295 with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps

Abstract

A control system comprises a switch and a control module that communicates with the switch and that samples a filament resistance of a fluorescent light when the switch is off and that selectively increases current supplied to the fluorescent light above a nominal current value during turn on based on the filament resistance.

Claims

1. A control system comprising:

a switch; and

a control module that communicates with said switch and that samples a filament resistance of a fluorescent light when said switch is in a first state and that selectively increases current supplied to the fluorescent light above a nominal current value when said switch transitions to a second state based on said filament resistance.

2. The control system of claim 1 wherein said control module determines a steady-state filament resistance value when said switch is in said first state and monitors changes in said steady state filament resistance value.

3. The control system of claim 2 further comprising an indicator that communicates with said control module and that indicates an operational state of said fluorescent light.

4. The control system of claim 3 wherein said control module compares changes in said steady state filament resistance value to a predetermined filament resistance change threshold and changes a state of said indicator when said changes in said steady state filament resistance value exceed said predetermined filament resistance change threshold.

5. The control system of claim 2 wherein said control module compares said steady state filament resistance value to a predetermined filament resistance threshold and changes a state of said indicator when said steady state filament resistance value exceeds said predetermined filament resistance threshold.

6. The control system of claim 1 wherein said control module increases at least one of current and voltage to said filament by a first amount above said nominal current level when said switch turns on based on a stored filament resistance value of said filament that is stored before said switch turns on.

7. The control system of claim 6 wherein said control module determines and stores a steady-state filament resistance value when said switch is in said first state and wherein said control module increases at least one of current and voltage to said filament by a first amount above said nominal level when said switch transitions to said second state based on a difference between a stored filament resistance value that is stored before said switch transitions to said second state and said stored steady state filament resistance value.

8. The control system of claim 4 further comprising an ambient temperature estimator that estimates ambient temperature.

9. The control system of claim 8 wherein said changes in said steady state filament resistance value are adjusted based on said ambient temperature.

10. The control system of claim 8 wherein said ambient temperature estimator includes a temperature sensor.

11. The control system of claim 8 wherein said ambient temperature estimator estimates said ambient temperature based on a filament resistance measured after said fluorescent light has been in said first state for a predetermined period.

12. The control system of claim 1 further comprising:

a ballast module comprising

an electrolytic capacitance element; and

a temperature sensor that senses a temperature of said electrolytic capacitance element, wherein said control module communicates with said temperature sensor and adjusts power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

13. The control system of claim 12 wherein said control module modulates said power output based on said sensed temperature.

14. The control system of claim 12 further comprising a rectifier module having an input that selectively communicates with a voltage source, wherein said electrolytic capacitance element and said control module communicate with an output of said rectifier module.

15. The control system of claim 12 further comprising:

a first electrical component; and

a temperature sensor that senses a temperature of said first electrical component, wherein said control module communicates with said temperature sensor and adjusts power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

16. The control system of claim 15 further comprising a rectifier module having an input that selectively communicates with a voltage source, wherein said control module communicate with an output of said rectifier module.

17. A method for operating a fluorescent light, comprising:

sampling a filament resistance of a fluorescent light when said fluorescent light is off; and

selectively increasing current supplied to the fluorescent light above a nominal current value during turn on based on said filament resistance.

18. The method of claim 17 further comprising:

determining a steady-state filament resistance value when said fluorescent light is off; and

monitoring changes in said steady state filament resistance value.

19. The method of claim 18 further comprising indicating an operational state of said fluorescent light based on said filament resistance.

20. The method of claim 19 further comprising:

comparing changes in said steady state filament resistance value to a predetermined filament resistance change threshold; and

changing a state of an indicator when said changes in said steady state filament resistance value exceed said predetermined filament resistance change threshold.

21. The method of claim 18 further comprising:

comparing said steady state filament resistance value to a predetermined filament resistance threshold; and

changing a state of said indicator when said steady state filament resistance value exceeds said predetermined filament resistance threshold.

22. The method of claim 17 further comprising increasing at least one of current and voltage to said filament by a first amount above said nominal current level when said fluorescent light turns on based on a stored filament resistance value of said filament that is stored before said fluorescent light turns on.

23. The method of claim 22 further comprising determining and storing a steady-state filament resistance value when said fluorescent light is off and wherein said control module increases at least one of current and voltage to said filament by a first amount above said nominal level when said fluorescent light is turned on based on a difference between a stored filament resistance value that is stored before said switch turns on and said stored steady state filament resistance value.

24. The method of claim 20 further comprising estimating ambient temperature.

25. The method of claim 24 further comprising adjusting changes in said steady state filament resistance value based on said ambient temperature.

26. The method of claim 24 further comprising estimating said ambient temperature based on a filament resistance measured after said fluorescent light has been in an off state for a predetermined period.

27. The method of claim 17 further comprising:

sensing a temperature of an electrolytic capacitance element; and

adjusting power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

28. The method of claim 27 further comprising modulating said power output based on said sensed temperature.

29. The method of claim 17 further comprising:

sensing a temperature of a first electrical component; and

adjusting power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

30. A control system comprising:

switch means for switching; and

control means that communicates with said switch means for sampling a filament resistance of a fluorescent light when said switch means is in a first state and for selectively increasing current supplied to the fluorescent light above a nominal current value when said switch means transitions to a second state based on said filament resistance.

31. The control system of claim 30 wherein said control means determines a steady-state filament resistance value when said switch means is in said first state and monitors changes in said steady state filament resistance value.

32. The control system of claim 31 further comprising indicating means that communicates with said control means for indicating an operational state of said fluorescent light.

33. The control system of claim 32 wherein said control means compares changes in said steady state filament resistance value to a predetermined filament resistance change threshold and changes a state of said indicator when said changes in said steady state filament resistance value exceed said predetermined filament resistance change threshold.

34. The control system of claim 31 wherein said control means compares said steady state filament resistance value to a predetermined filament resistance threshold and changes a state of said indicator when said steady state filament resistance value exceeds said predetermined filament resistance threshold.

35. The control system of claim 30 wherein said control means increases at least one of current and voltage to said filament by a first amount above said nominal current level when said switch means transitions to said second state based on a stored filament resistance value of said filament that is stored before said switch means transitions to said second state.

36. The control system of claim 35 wherein said control means determines and stores a steady-state filament resistance value when said switch means is in said first state and wherein said control means increases at least one of current and voltage to said filament by a first amount above said nominal level when said switch means transitions to said second state based on a difference between a stored filament resistance value that is stored before said switch means transitions to said second state and said stored steady state filament resistance value.

37. The control system of claim 32 further comprising ambient temperature estimating means for estimating ambient temperature.

38. The control system of claim 37 wherein said changes in said steady state filament resistance value are adjusted based on said ambient temperature.

39. The control system of claim 37 wherein said ambient temperature estimating means includes temperature sensing means for sensing temperature.

40. The control system of claim 37 wherein said ambient temperature estimating means estimates said ambient temperature based on a filament resistance measured after said fluorescent light has been in said first state for a predetermined period.

41. The control system of claim 30 further comprising:

electrolytic capacitance means for providing capacitance;

temperature sensing means for sensing a temperature of said electrolytic capacitance means, wherein said control means communicates with said temperature sensor and adjusts power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

42. The control system of claim 41 wherein said control means modulates said power output based on said sensed temperature.

43. The control system of claim 41 further comprising rectifier means for rectifying and having an input that selectively communicates with a voltage source, wherein said electrolytic capacitance means and said control means communicate with an output of said rectifier means.

44. The control system of claim 41 further comprising:

a first electrical component; and

temperature sensing means for sensing a temperature of said first electrical component, wherein said control means communicates with said temperature sensor and adjusts power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

45. The control system of claim 44 further comprising rectifier means for rectifying and having an input that selectively communicates with a voltage source, wherein said control means communicates with an output of said rectifier means.