Ballast circuit with independent lamp control

• US 6,222,326 B1
• Filed: 09/03/1999
• Issued: 04/24/2001
• Est. Priority Date: 10/16/1998
• Status: Expired due to Fees

• Current Assignee: Chicago Miniature Optoelectronic Technologies, Inc.
• Original Assignee: Electro-Mag International, Inc.
• Inventors: Moisin, Mihail S.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): TRAN, THUY V
• Application Number:
  US09/390,073
• Time in Patent Office: 599 Days
• Field of Search: 315/209.R, 315/160, 315/161, 315/189, 315/224, 315/225, 315/226, 315/291, 315/307, 315/DIG.5, 315/DIG.7, 315/205
• US Class Current: 315/209.00R
• CPC Class Codes: H02J 9/02 in which an auxiliary distribution system and its associated lamps are brought into service
• CPC Class Codes: H05B 41/36 Controlling

Abstract

A ballast circuit independently energizes first and second lamps. In one embodiment, an inverter provides a drive signal for energizing the first and second lamps. A first signal detection circuit detects a first AC input signal and a second signal detection circuit detects a second AC input signal, each of which energizes a respective one of first and second lamps. A first lamp control circuit receives a signal from the first signal detector such that the first lamp is energized by the drive signal when the first AC input signal is present. Similarly, a second lamp control circuit receives a signal from the second signal detector such that the second lamp is energized by the drive signal when the second AC input signal is present.

Claims

1. A method of energizing first and second lamps by two AC input signals, comprising:

coupling a first AC input signal to a ballast;

coupling a second AC input signal to the ballast;

energizing a first lamp when the first AC input signal is present regardless of whether the second AC input signal is present; and

energizing the second lamp when the second AC input signal is present regardless of whether the first AC input signal is present.

2. The method according to claim 1, further including energizing the first and second lamps with a common inverter.

3. The method according to claim 1, further including controlling the first AC input signal with a first switch.

4. The method according to claim 3, further including controlling the second AC input signal with a second switch.

5. The method according to claim 1, further including detecting the first AC input signal with an optocoupler.

6. The method according to claim 5, further including optically coupling the optocoupler to a control circuit connected to the first lamp for selectively energizing the first lamp.

7. A method of energizing first and second lamps, comprising:

coupling a first AC input signal to a ballast by receiving the first AC input signal on first and second input terminals

coupling a second AC input signal to the ballast by receiving the second AC input signal on the second input terminal and a third input terminal;

coupling a first inductor to the first input terminal;

coupling a second inductor to the second input terminal;

energizing a first lamp when the first AC input signal is present regardless of whether the second AC input signal is present; and

energizing the second lamp when the second AC input signal is present regardless of whether the first AC input signal is present;

wherein said steps of energizing said first and second lamps include the step of;

coupling a third inductor to a switching element, wherein the first, second and third inductors are inductively coupled such that flux generated by the first and second inductors cancels each other when the first AC input signal is present, and wherein a signal on the third inductor, when the second AC input signal is present and the first AC input signal is not present, prevents the first lamp from being energized.

8. A ballast, comprising:

first, second and third input terminals;

a first signal detector coupled to the first input terminal for detecting a first AC input signal on the first terminal;

a second signal detector coupled to the third input terminal for detecting a second AC input signal on the third terminal;

a drive circuit for receiving the first and second AC input signals and providing an AC drive signal to first and second lamps;

a first lamp control circuit for coupling to the first lamp;

a second lamp control circuit for coupling to the second lamp;

a first signal path connecting the first lamp control circuit to the first signal detector for carrying a first signal corresponding to a presence of the first AC input signal; and

a second signal path connecting the second lamp control circuit to the second signal detector for carrying a second signal corresponding to a presence of the second AC input signal,

wherein the first lamp is energized when the first AC input signal is present independently of whether of the second AC input signal is present, and wherein the second lamp is energized when the second AC input signal is present independently of whether the first AC input signal is present.

9. The ballast according to claim 8, wherein the drive circuit includes an inverter that provides the AC drive signal to the first and second lamps.

10. The ballast according to claim 9, wherein the drive circuit includes a rectifier circuit for receiving the first and second AC input signals and providing DC energy to the inverter.

11. The ballast according to claim 10, wherein the rectifier includes first, second, third and fourth diodes coupled in a full bridge configuration so as to provide first and second rectifier AC input terminals and first and second rectifier DC output terminals, and wherein the first signal detector is coupled to the first AC rectifier input terminal and to the second signal detector.

12. The ballast according to claim 11, wherein the second AC input terminal is coupled to the second AC rectifier input terminal.

13. The ballast according to claim 8, wherein the drive circuit includes a rectifier coupled to the second terminal and to the first and second signal detectors.

14. The ballast according to claim 8, wherein the drive circuit includes first and second output terminals on which the AC drive signal is provided, and wherein a first series circuit path between the first and second drive circuit output terminals includes a first capacitor, a first set of lamp terminals for receiving the first lamp, and the first lamp control circuit.

15. The ballast according to claim 14, wherein the first lamp control circuit includes a diode for providing a current path for current flowing from the drive circuit second output terminal to the first set of lamp terminals and a control switching element for providing a current path for current flowing from the first set of lamp terminals to the drive circuit second output terminal.

16. The ballast according to claim 15, wherein the first lamp control circuit further includes a first coupling switching element coupled to the first signal detector via the first signal path for controlling a conduction state of the first control switching element.

17. The ballast according to claim 16, wherein the first signal path between the first coupling switching element and the first signal detector circuit is an optical signal path.

18. The ballast according to claim 16, wherein the first signal detector and the first coupling switching element form part of an optocoupler.

19. The ballast according to claim 16, wherein the second lamp control circuit includes a second diode and a second control switching element, the second signal path between the second switching element and the second signal detector being an optical path.

20. The ballast according to claim 14, wherein a second series circuit path between the drive circuit first and second output terminals includes a second capacitor, a second set of lamp terminals, and the second lamp control circuit.

21. The ballast according to claim 20, wherein the first and second capacitors are effective to buffer current to the first and second lamps such that a first one of the first and second lamps to light is inhibited from drawing excessive current that prevents lighting of the other of the first and second lamps.

22. The ballast according to claim 8, wherein a first circuit loop includes a first capacitor, a first set of lamp terminals for receiving the first lamp, the first lamp control circuit, the second lamp control circuit, a second set of lamp terminals for receiving the second lamp, and a second capacitor.

23. The ballast according to claim 8, wherein the first signal path comprises an optical path.

24. The ballast according to claim 8, wherein the first signal detector includes an optocoupler.

25. A ballast circuit, comprising:

first, second and third AC input terminals, the first and second AC input terminals being adapted for receiving a first AC input signal and the second and third AC input terminals being adapted for receiving a second AC input signal;

a rectifier circuit for receiving the first and second AC input signals and providing a DC output signal;

an inverter circuit for receiving the DC output signal and providing a drive signal for energizing first and second lamps;

a first signal detector coupled to the first AC input terminal and to the rectifier;

a second signal detector coupled to the third AC input terminal and to the rectifier at a point in common with first signal detector;

a first lamp control circuit for coupling to the first lamp, the first lamp control circuit being optically coupled to the first signal detector; and

a second lamp control circuit for coupling to the second lamp, the second lamp control circuit being optically coupled to the second signal detector,

wherein the first lamp control circuit allows the AC drive signal to energize the first lamp when the first AC input signal is present independently of whether the second AC input signal is present, and the second lamp control circuit allows the AC drive signal to energize the second lamp when the second AC input signal is present independently of whether the first AC input signal is present.

26. The ballast according to claim 25, wherein the inverter provides the AC drive signal on first and second output terminals, and wherein the ballast includes first and second series circuit paths between the first and second inverter output terminals, the first series circuit path including a first capacitor, a first set of lamp terminals, and the first lamp control circuit, the second series circuit path including a second capacitor, a second set of lamp terminals, and the second lamp control circuit.

27. The ballast according to claim 26, wherein the first lamp control circuit includes a control switching element for providing a path for current to flow from the first lamp to the second inverter output terminal and a diode for providing a path for current to flow from the second inverter output terminal to the first lamp.

28. The ballast according to claim 27, wherein the first lamp control circuit includes a further switching element for controlling a conduction state of the control switching element, wherein the further switching element receives an optical signal from the first signal detector such that the presence of the first AC input signal determines the conduction state of the control switching element.

29. A ballast for energizing first and second lamps, comprising:

first, second, and third AC input terminals, wherein the first and second AC input terminals are adapted for receiving a first AC input signal and the second and third AC input terminals are adapted for receiving a second AC input signal;

a first circuit coupled to the first and second AC input terminals for receiving the first AC input signal and providing a first drive signal for energizing the first lamp, the first circuit including a first inverter controlled by a first inverter disable circuit;

a second circuit coupled to the second and third AC input terminals for receiving the second AC input signal and providing a second drive signal for energizing the second lamp, the second circuit including a second inverter controlled by a second inverter control circuit;

a first inductor coupled to the first AC input terminal;

a second inductor coupled to the second AC input terminal; and

a third inductor inductively coupled to the first and second inductors, the third inductor forming a part of the first inverter disable circuit,

wherein a signal generated on the third inductor when the second AC input signal is present and the first AC input signal is not present is effective to disable the first inverter.

30. The ballast according to claim 29, further including

a fourth inductor coupled to the second AC input terminal;

a fifth inductor coupled to the third AC input terminal; and

a sixth inductor inductively coupled to the fourth and fifth inductors, the sixth inductor forming a part of the second inverter disable circuit,

wherein a signal generated on the sixth inductor when the first AC input signal is present and the second AC input signal is not present is effective to disable the second inverter.

31. The ballast according to claim 29, further including a first capacitor coupled to the fourth inductor such that a voltage on the first capacitor generated by the sixth inductor above a predetermined level is effective to disable the first inverter.

32. The ballast according to claim 31, further including a first diac coupled to the first capacitor.

33. A ballast for energizing first and second lamps, comprising:

first, second and third AC input terminals, the first and second AC input terminals for receiving a first AC input signal, and the second and third AC input terminals for receiving a second AC input signal;

a drive circuit for receiving the first and second AC input signals and energizing the first and second lamps, wherein the drive circuit energizes the first lamp when the first AC input signal is present at the first and second input terminals independently of whether the second AC input signal is present, and wherein the drive circuit energizes the second lamp when the second AC input signal is present independently of whether the first AC input signal is present.

34. A method of energizing first and second lamps, comprising:

coupling a first AC input signal to first and second AC input terminals of a ballast;

coupling a second AC input signal to a third terminal and the second terminal of the ballast;

energizing the first lamp when the first AC input signal is present on the first and second AC input terminals of the ballast; and

energizing the second lamp when the second AC input signal is present on the second and third AC input terminals of the ballast.