Multiple voltage ballast

Abstract

A ballast and method for operating a ballast includes a switch or other circuit for connecting and disconnecting a voltage multiplier to a rectifier circuit. A control circuit for controlling the switch senses an input voltage and connects the voltage multiplier to the rectifier circuit when an input voltage falls below a selected voltage level.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic and block diagram of a ballast and a driving circuit for a light source and a method for driving a load such as a light source.

FIG. 2 is a schematic of a voltage doubling circuit.

FIG. 3 is a schematic of a full wave bridge circuit.

FIG. 4 is a schematic of a circuit having a control and a circuit changing element in the form of a switch operated by the control.

FIG. 5 is a detailed circuit diagram in accordance with one example of the present inventions.

Claims

1. A ballast comprising: a rectifier circuit;a multiplier component;a switch for coupling and decoupling the multiplier component from the rectifier circuit;an input circuit wherein the switch is configured to operate in conjunction with a voltage change at the input; anda load driver coupled for receiving current from the rectifier.

2. The ballast of claim 1 wherein the rectifier is a full wave rectifier and wherein the switch is coupled to the rectifier circuit in such a way that when the multiplier component is coupled to the rectifier circuit, the rectifier circuit is converted to a voltage doubler circuit.

3. The ballast of claim 1 wherein the multiplier component is a voltage doubler circuit.

4. The ballast of claim 1 wherein the load driver is an inverter circuit configured to drive a fluorescent lamp.

5. The ballast circuit of claim 1 further including a control circuit for the switch wherein the control circuit for the switch is configured to open and close the switch.

6. The ballast of claim 5 wherein the control circuit is configured to open the switch when the input voltage increases past a predetermined level.

7. The ballast of claim 5 wherein the control circuit is configured to open when the input voltage is higher than 180 volts

8. The ballast of claim 1 further including a control circuit coupled between the input circuit and the switch.

9. The ballast of claim 8 wherein the control circuit includes a coupling circuit.

10. The ballast of claim 9 wherein the coupling circuit includes an optical isolator.

11. The ballast of claim 9 wherein the coupling circuit includes a TRIAC.

12. The ballast of claim 9 wherein the control circuit includes an inverter.

13. The ballast of claim 9 wherein the control circuit includes a delay circuit.

14. The ballast of claim 9 wherein the control circuit includes a rectifier.

15. The ballast of claim 9 wherein the control circuit includes a coupling capacitor as a coupler.

16. The ballast of claim 9 wherein the control circuit includes a magnetic coupler.

17. The ballast of claim 1 wherein the switch is a TRIAC.

18. The ballast of claim 17 wherein the TRIAC is a first TRIAC and the switch includes a second TRIAC coupled to the first TRIAC.

19. The ballast of claim 18 wherein the second TRIAC is configured to be turned on by an optical signal.

20. A ballast circuit comprising: a full wave bridge circuit;a voltage multiplier component coupled to the bridge circuit;a switch for changing the full wave bridge circuit to a half wave bridge circuit; anda control circuit coupled to the switch for changing a configuration of the switch at a selected voltage.

21. The ballast circuit of claim 20 wherein the switch is coupled to the voltage multiplier.

22. The ballast circuit of claim 21 further including a drive circuit for driving a load and wherein the switch is configured to couple the multiplier to the drive circuit substantially when the switch changes the full wave bridge to a half wave bridge.

23. The ballast circuit of claim 21 wherein the switch is a TRIAC.

24. The ballast circuit of claim 23 wherein the TRIAC is a first TRIAC and further including a second TRIAC wherein the second TRIAC is configured to be activated by an optical signal.

25. The ballast circuit of claim 20 wherein the control circuit is a voltage sensing circuit.

26. The ballast circuit of claim 25 wherein the voltage sensing circuit includes a capacitor.

27. The ballast circuit of claim 25 wherein the voltage sensing circuit includes a delay circuit.

28. The ballast circuit of claim 25 wherein the voltage sensing circuit includes an inverter to turn the switch on when the voltage sensed by the voltage sensing circuit is lower than a threshold voltage input to the full wave bridge circuit.

29. The ballast circuit of claim 20 further including a drive circuit for driving a load and wherein the control circuit is coupled to a circuit in the drive circuit.

30. The ballast circuit of claim 29 wherein the control circuit is coupled to a switch in an inductor circuit.

31. The ballast circuit of claim 20 wherein the switch includes a TRIAC.

32. The ballast circuit of claim 31 wherein the TRIAC is a first TRIAC and further including a second TRIAC wherein the second TRIAC is configured to be activated by an optical signal.

33. The ballast circuit of claim 31 wherein the optical signal is turned on or off as a function of the voltage level at an input to the bridge circuit.

34. A ballast comprising: an input circuit;a full wave bridge rectifier circuit coupled to the input circuit;a voltage multiplier component coupled to the input circuit;a connecting circuit between the full wave bridge rectifier circuit and the voltage multiplier component for electrically connecting the full wave bridge rectifier circuit to the voltage multiplier component and configured such that when the full wave bridge rectifier circuit is connected to the voltage multiplier component, the full wave bridge rectifier circuit becomes a half wave rectifier circuit;a load driving circuit coupled to the voltage multiplier component; anda voltage sensing circuit between the input circuit and the connecting circuit.

35. A method of controlling a ballast circuit the method comprising: applying an AC voltage to an input circuit, rectifiying the AC voltage to a DC signal, changing a switch configuration when the AC voltage passes a first voltage level so that the DC signal is applied to a multiplier circuit.

36. The method of claim 35 wherein changing the switch configuration includes changing the AC voltage when the AC voltage is greater than 180 volts.

37. The method of claim 35 further including opening the switch when the AC voltage is greater than 180 volts.

38. The method of claim 35 further including rectifying AC voltage with a full wave rectifier circuit when the voltage is at a first level and the switch is in a first configuration, and rectifying an AC voltage with a half wave rectifier when the voltage is at a second level different from the first level, and the switch is in a second configuration.

39. The method of claim 35 further including changing the switch configuration using an optical input signal.

40. The method of claim 35 further including changing the switch configuration by changing the state of a TRIAC.

41. The method of claim 35 further including changing the switch configuration by changing the state of an optical TRIAC.

42. The method of claim 35 further including sensing a voltage level of the AC voltage at the input circuit.

43. A method of controlling a ballast circuit, the method comprising applying an AC voltage to an input circuit of a normal power factor ballast coupled to a load, sensing the level of the AC voltage and changing a configuration of the ballast between the input circuit and the load as a function of the AC voltage level.

44. The method of claim 43 further including activating a multiplier circuit.

45. The method of claim 44 wherein activating the multiplier circuit deactivates a portion of a rectifier circuit.

46. A ballast circuit comprising: an AC voltage input circuit;a voltage multiplier coupled to the AC voltage input;a sensor coupled to the AC voltage input circuit;a coupler controlled by the sensor and configured to couple and decouple the voltage multiplier from at least a portion of the AC voltage input; anda driver circuit for driving a load coupled the AC voltage input circuit.