Current Regulator for Multimode Operation of Solid State Lighting

• US 20110115411A1
• Filed: 11/05/2010
• Published: 05/19/2011
• Est. Priority Date: 02/06/2006
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Exclara, Inc. (Million Star Technology Ltd.)
• Inventors: Rodriguez, Harry, Shteynberg, Anatoly
• Granted Patent: US 8,803,443 B2
• Time in Patent Office: Days
• US Class Current: 315/302
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An exemplary apparatus embodiment provides a plurality of operating modes for solid state lighting, such as a flash mode and a constant or background lighting mode for use with devices such as cameras. An exemplary apparatus comprises a memory adapted to store a plurality of average current parameters; and a controller adapted to modulate an energizing cycle time period (“T”) for providing power to the solid state lighting as proportional to the product of the selected average current parameter (“α”) and a reset time period (“T_R”) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝α·T_R). The average current parameter is predetermined as substantially proportional to a ratio of a peak inductor current level (“I_P”) to an average output D.C. current level (“I_O”)(α∝I_P/I_O).

Claims

1. A current regulator for providing a plurality of operating modes for solid state lighting, the current regulator couplable to a DC power supply, the current regulator comprising:

a memory adapted to store a plurality of average current parameters; and

a control circuit coupled to the memory, the control circuit adapted to modulate an energizing cycle time period for providing power to the solid state lighting in response to a selected average current parameter of the plurality of average current parameters.

2. The current regulator of claim 1, wherein each average current parameter of the plurality of average current parameters corresponds to a selected operating mode of the plurality of operating modes.

3. The current regulator of claim 1, wherein the plurality of operating modes comprises a flash mode and a constant mode.

4. The current regulator of claim 1, wherein the control circuit is further adapted to determine the energizing cycle time period (“

T”

) as proportional to the product of the selected average current parameter (“

α

”

) and a reset time period (“

T_R”

) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝

α

·

T_R).

5. The current regulator of claim 4, wherein each average current parameter (“

α

”

) of the plurality of average current parameters is predetermined as substantially equal to one-half of a ratio of a peak inductor current level (“

I_P”

) to an average output D.C. current level (“

I_O”

)

6. The current regulator of claim 4, wherein each average current parameter (“

α

”

) of the plurality of average current parameters is predetermined as substantially proportional to a ratio of a peak inductor current level (“

I_P”

) to an average output D.C. current level (“

I_O”

)

7. The current regulator of claim 6, wherein the peak inductor current level (I_P) and the average output D.C. current level (I_O) are predetermined and correspond to a selected operating mode of the plurality of operating modes.

8. The current regulator of claim 4, wherein the control circuit further comprises:

a first counter to provide a count corresponding to the energizing cycle time period (T_n); and

a second counter to provide a count corresponding to the reset time period (T_R).

9. The current regulator of claim 8, wherein the control circuit is further adapted to provide a next energizing cycle when a count T_n of the first counter is equal to the energizing cycle time period T.

10. The current regulator of claim 1, further comprising:

an inductor coupled to the DC power supply and coupled to the solid state lighting;

a switch coupled to the inductor and to the control circuit;

a current sensor coupled to the switch; and

a first comparator coupled to the current sensor and the control circuit;

wherein the control circuit is further adapted to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has reached a predetermined peak level.

11. The current regulator of claim 10, further comprising:

a voltage sensor; and

a second comparator coupled to the voltage sensor and to the control circuit;

wherein the control circuit is further adapted to determine the reset time period (T_R) when the second comparator indicates that a voltage level corresponding to the inductor current has decreased substantially to a zero level.

12. A method of providing power to a solid state lighting system for a selected operating mode of a plurality of operating modes, the method comprising:

starting an energizing cycle by providing current through an inductor until a predetermined peak inductor current level is reached;

transferring energy stored in the inductor to the solid state lighting;

determining a reset time period as a time duration for the inductor current to decrease substantially to a zero level from the peak inductor current level;

determining an energizing cycle time period based on the reset time period and a predetermined average current parameter; and

commencing a next energizing cycle when the energizing cycle time period has elapsed.

13. The method of claim 12, wherein the predetermined average current parameter corresponds to a selected operating mode of the plurality of operating modes.

14. The method of claim 12, wherein the plurality of operating modes comprises a flash mode and a constant mode.

15. The method of claim 12, wherein the determination of the energizing cycle time period further comprises determining the energizing cycle time period (“

T”

) as proportional to the product of the predetermined average current parameter (“

α

”

) and a reset time period (“

T_R”

) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝

α

·

T_R).

16. The method of claim 15, wherein the predetermined average current parameter (“

α

”

) is determined as substantially equal to one-half of a ratio of a peak inductor current level (“

I_P”

) to an average output D.C. current level (“

I_O”

)

17. The method of claim 15, wherein the predetermined average current parameter (“

α

”

) is determined as substantially proportional to a ratio of a peak inductor current level (“

I_P”

) to an average output D.C. current level (“

I_O”

)

18. The method of claim 17, wherein the peak inductor current level (I_P) and the average output D.C. current level (I_O) are predetermined and correspond to a selected operating mode of the plurality of operating modes.

19. The method of claim 17, wherein the predetermined average current parameter is selected from a plurality of predetermined average current parameters, each predetermined average current parameter corresponding to a selected operating mode of the plurality of operating modes and determined by a corresponding peak inductor current level (I_P) of a plurality of peak inductor current levels (I_P) and an average output D.C. current level (I_O) of a plurality of and average output D.C. current levels (I_O).

20. The method of claim 12, further comprising:

providing a first count corresponding to the energizing cycle time period; and

providing a second count corresponding to the reset time period.

21. The method of claim 20, wherein the next energizing cycle is commenced when the first count is equal to the energizing cycle time period.

22. An apparatus for providing a plurality of operating modes for solid state lighting, the apparatus comprising:

a memory adapted to store a plurality of average current parameters; and

a controller coupled to the memory, the controller adapted to modulate an energizing cycle time period for providing power to the solid state lighting in response to a selected average current parameter of the plurality of average current parameters.

23. The apparatus of claim 22, wherein each average current parameter of the plurality of average current parameters corresponds to a selected operating mode of the plurality of operating modes.

24. The apparatus of claim 22, wherein the plurality of operating modes comprises a flash mode and a constant mode.

25. The apparatus of claim 22, wherein the controller is further adapted to determine the energizing cycle time period (“

T”

) as proportional to the product of the selected average current parameter (“

α

”

) and a reset time period (“

T_R”

) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝

α

·

T_R).

26. The apparatus of claim 25, wherein each average current parameter (“

α

”

) of the plurality of average current parameters is predetermined as substantially equal to one-half of a ratio of a peak inductor current level (“

I_P”

) to an average output D.C. current level

27. The apparatus of claim 25, wherein each average current parameter (“

α

”

) of the plurality of average current parameters is predetermined as substantially proportional to a ratio of a peak inductor current level (“

I_P”

) to an average output D.C. current level (“

I_O”

)

28. The apparatus of claim 27, wherein the peak inductor current level (I_P) and the average output D.C. current level (I_O) are predetermined and correspond to a selected operating mode of the plurality of operating modes.

29. The apparatus of claim 27, wherein each predetermined average current parameter is determined by a corresponding peak inductor current level (I_P) of a plurality of peak inductor current levels (I_P) and an average output D.C. current level (I_O) of a plurality of and average output D.C. current levels (I_O).

30. The apparatus of claim 25, wherein the controller further comprises:

a first counter to provide a count corresponding to the energizing cycle time period (T_n); and

a second counter to provide a count corresponding to the reset time period (T_R).

31. The apparatus of claim 30, wherein the controller is further adapted to provide a next energizing cycle when a count T_n of the first counter is equal to the energizing cycle time period T.

32. The apparatus of claim 22, further comprising:

an inductor coupled to the DC power supply and coupled to the solid state lighting;

and wherein the controller further comprises;

a control circuit;

a switch coupled to the inductor and to the control circuit;

a current sensor coupled to the switch; and

a first comparator coupled to the current sensor and the control circuit;

wherein the control circuit is adapted to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has reached a predetermined peak level.

33. The apparatus of claim 32, wherein the controller further comprises:

a voltage sensor; and

a second comparator coupled to the voltage sensor and to the control circuit;

wherein the control circuit is further adapted to determine the reset time period (T_R) when the second comparator indicates that a voltage level corresponding to the inductor current has decreased substantially to a zero level.

34. A current regulator for providing a plurality of operating modes for solid state lighting, the current regulator couplable to a DC power supply, the current regulator comprising:

an inductor coupled to the DC power supply and coupled to the solid state lighting;

a switch coupled to the inductor;

a current sensor coupled to the switch;

a first comparator coupled to the current sensor;

a voltage sensor coupled to the inductor;

a second comparator coupled to the voltage sensor;

a memory adapted to store a plurality of average current parameters; and

a control circuit coupled to the memory and to the first and second comparators, the control circuit adapted to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has reached a predetermined peak level, to determine a reset time period when the second comparator indicates that a voltage level corresponding to the inductor current has decreased substantially to a zero level, and to determine an energizing cycle time period for providing power to the solid state lighting as proportional to a selected average current parameter of the plurality of average current parameters and the reset time period.