Self-regulating, no load protected electronic ballast system

• US 4,733,135 A
• Filed: 05/06/1986
• Issued: 03/22/1988
• Est. Priority Date: 06/01/1983
• Status: Expired due to Fees

• Current Assignee: Intent Patent AG
• Original Assignee: Intent Patent AG
• Inventors: Hanlet, Jacques M.
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): Razavi, Michael
• Application Number:
  US06/860,200
• Time in Patent Office: 686 Days
• Field of Search: 315/224, 315/221, 315/278, 315/DIG. 7, 315/DIG. 4, 315/95, 315/219, 315/209 R, 315/205, 315/274, 315/297, 315/200 R
• US Class Current: 315/224
• CPC Class Codes: H05B 41/2821 by means of a single-switch converter or a parallel push-pull converter in the final stage H05B41/285 takes precedence
• CPC Class Codes: H05B 41/295 with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

A self-regulating, no load protected electronic ballast system (10) is provided which includes a power source (12) for actuating at least one gas discharge tube (66) with a regulated current and limited voltage to maintain the gas discharge tubes (66) input and output power at a predetermined value. The self-regulating, no load protected electronic ballast system (10) includes a filter circuit (11) coupled to the power source (12) with an induction circuit (15) coupled to the filter circuit (11). The induction circuit (15) has a tapped primary winding (42) providing an auto-transformer configuration for establishing the magnitude of the regulated current. The induction circuit (15) includes a trigger control winding (48) for generating a control current and further includes a no-load protection circuit (99) for generating a voltage across the gas discharge tube (66) responsive to the regulated current and for maintaining the output voltage at a predetermined value when the gas discharge tube (66) is decoupled from the electronic ballast system (10). In this manner, the output voltage of the ballast system (10) is substantially reduced when the gas discharge tube (66) is electrically decoupled from the overall circuit resulting in a higher reliability and extended life of a particular gas discharge tube (66).

Claims

1. A self-regulating, no load protected electronic ballast system having a power source for actuating at least one gas discharge tube with a regulated current and limited voltage to maintain said gas discharge tube input and output power at predetermined values, comprising:

(a) filter means connected to said power source for (1) maintaining a substantially smooth direct current voltage signal, and (2) suppressing harmonic frequencies generated by said electronic ballast system;

(b) induction means coupled to said filter means and having a tapped primary winding providing an auto-transformer configuration for establishing the magnitude of said regulated current, said induction means having a trigger control winding for generating a control current, said induction means further including no-load protection means for generating a voltage across said gas discharge tube responsive to said regulated current and for maintaining said output voltage at a predetermined value when said gas discharge tube is decoupled from said electronic ballast system, said no-load protection means having a transformer with a primary winding coupled in series relation with said filter means and said tapped primary winding of said induction means, said transformer including a multiplicity of secondary windings, said primary winding forming a variable inductance for reducing said regulated current when said gas discharge tube is decoupled from said ballast system;

(c) switching means being feedback coupled to said induction means for establishing said regulated current, said switching means including regulation means for maintaining said power output of said gas discharge tube at a predetermined and substantially constant value, said regulation means including a toroidal transformer having (1) a first winding coupled in series relation with said trigger control winding and said switching means for modifying said control current, and, (2) a second winding coupled to said tapped primary winding of said induction means and said filter means in series relation for feedback to said first winding of said toroidal transformer.

2. The self-regulating, no load protected electronic ballast system as recited in claim 1 where said multiplicity of secondary windings includes a tuned high voltage output secondary winding and a pair of filament excitation windings, each of said filament excitation windings being coupled to respective filaments of said gas discharge tube.

3. The self-regulating, no load protected electronic ballast system as recited in claim 2 where said tuned high voltage secondary winding is coupled in parallel relation to both a tuning capacitor and said gas discharge tube, said tuned high voltage secondary winding generating said limited voltage for input to said gas discharge tube, said limited voltage being reduced responsive to said reduced regulated current when said gas discharge tube is decoupled from said electronic ballast system.

4. The self-regulating, no load protected electronic ballast system as recited in claim 3 where said transformer includes a core ferrite material for generating said voltage input to said gas discharge tube, said transformer core saturating when said power source rises above a predetermined value.

5. The self-regulating, no load protected electronic ballast system as recited in claim 1 where said switching means includes transistor means for cycling said regulated current, said transistor means including a base element, a collector element, and an emitter element coupled to said power source.

6. The self-regulating, no load protected electronic ballast system as recited in claim 5 where said toroidal transformer second winding is connected to said induction means tapped primary winding and said emitter element of said transmitter means in series relation each with respect to the other.

7. The self-regulating, no load protected electronic ballast system as recited in claim 5 where said regulation means is coupled to said induction means and said transistor means in series relation.

8. The self-regulating, no load protected electronic ballast system as recited in claim 7 where said toroidal transformer provides a predetermined variable inductance for regulating a power output to said gas discharge tube, said toroidal transformer having a first toroidal transformer winding and a second toroidal transformer winding.

9. The self-regulating, no load protected electronic ballast system as recited in claim 6 where said regulation means includes a base coupling capacitor connected on opposing ends thereof to said toroidal transformer first winding and said trigger control winding of said induction means for substantially blocking a direct current component signal.

10. The self-regulating, no load protected electronic ballast system as recited in claim 4 where said regulation means includes a current limiting resistor coupled on opposing ends thereof in parallel relation with said toroidal transformer first winding and said emitter element of said transistor means.

11. The self-regulating, no load protected electronic ballast system as recited in claim 6 where said current limiting resistor limits a current value input to said base element of said transistor means when said toroidal transformer first winding inductance is at a substantially minimum value.

12. The self-regulating, no load protected electronic ballast system as recited in claim 5 where said trigger control winding of said induction means generates a switching control signal, said trigger control winding being coupled to said base coupling capacitor on a first end and to said base element of said transistor means on a second end thereof.

13. The self-regulating, no load protected electronic ballast system as recited in claim 12 where said induction means includes a capacitor in series relation to said tapped primary winding and said power source on opposing ends thereof, said capacitor for discharging energy, stored in said induction means during a first half of said regulated current cycle, during a second half of said regulated current cycle.

14. The self-regulating, no load protected electronic ballast system as recited in claim 13 where said tap of said primary winding is coupled to said collector element of said transistor means.

15. The self-regulating, no load protected electronic ballast system as recited in claim 8 where said toroidal transformer of said regulation means provides a predetermined variable inductance to regulate said power input to said gas discharge tube.

16. The self-regulating, no load protected electronic ballast system as recited in claim 15 where said toroidal transformer includes a toroid core configuration of ferrite material for varying the inductance in said first winding of said toroidal transformer responsive to a particular gain value of said transistor means.

17. The self-regulating, no load protected electronic ballast system as recited in claim 15 where said first and second toroidal transformer windings each of which having a predetermined number of turns are wound in a manner that the respective magnetic flux of said first and second toroidal transformer windings is additive within said toroid core, said first and second winding magnetic fluxes being generated by said base element current and said collector element current.

18. The self-regulating, no load protected electronic ballast system as recited in claim 16 where said first winding of said toroidal transformer has a greater number of turns than said second winding of said toroidal transformer.

19. The self-regulating, no load protected electronic ballast system as recited in claim 15 where said second winding of said toroidal transformer couples a variable inductance control current signal to said first winding of said toroidal transformer responsive to a predetermined value of a magnetic flux component in said toroidal core of said toroidal transformer.

20. The self-regulating, no load protected electronic ballast system as recited in claim 19 where said first winding of said toroidal transformer couples a variable inductance control current signal to said toroidal core of said toroidal transformer.

21. The self-regulating, no load protected electronic ballast system as recited in claim 1, said filter means includes:

(a) harmonic filter means for substantially reducing harmonic frequencies generated by said induction means; and

,

(b) smoothing filter means coupled in parallel relation to said harmonic filter means for maintaining said substantially smooth direct current voltage signal, said smoothing filter means including a rectification means for providing full wave rectification of said power source AC voltage.

22. The self-regulating, no load protected electronic ballast system as recited in claim 21 where said smoothing filter means includes a series inductor coupled in series relation to said power source and said rectification means.

23. The self-regulating, no load protected electronic ballast system as recited in claim 22 where said smoothing filter means includes a shunt capacitor coupled to said rectification means and said power source, said shunt capacitor being coupled in parallel relation with an output of said filter means.

24. The self-regulating, no load protected electronic ballast system as recited in claim 23 where said harmonic filter means includes a harmonic filter capacitor, said harmonic filter capacitor being coupled to said series inductor and said power source.

25. The self-regulating, no load protected electronic ballast system as recited in claim 5 where said switching means includes a diode coupled in parallel relation to said transistor base element and said emitter.

26. The self-regulating, no load protected electronic ballast system as recited in claim 25 where said switching means diode includes a polarity opposite to a polarity of a junction of said transistor base element and transistor emitter element.

27. The self-regulating, no load protected electronic ballast system as recited in claim 1 where said power source is an AC power source.

28. The self-regulating, no load protected electronic ballast system as recited in claim 21 where said rectification means includes a full wave bridge circuit.

29. A no load over voltage protection circuit including a tuned transformer series coupled to a current driven inverter circuit for preventing the generation of voltages above a predetermined value, said current driven inverter having a transformer through which inverter current is switched to deliver power to a load, said tuned transformer having a primary winding and at least one secondary winding, said primary winding being series coupled to said inverter circuit transformer through which said inverter current is switched, said primary winding forms a variable inductance which is inversely proportional to the magnitude of said power delivered to said load.

30. The no load over voltage protection circuit as recited in claim 29 where said secondary winding includes a tuning capacitor forming an inductive-capacitive tank circuit for generating said power to said load responsive to said switched inverter current.

31. The no load over voltage protection circuit as recited in claim 30 where said tank circuit is coupled in parallel relation to said load for coupling said generated power to said load, said load forming part of a complex impedance in combination with said tank circuit.

32. The no load over voltage protection circuit as recited in claim 31 where said complex impedance is reflected in said primary winding of said tuned transformer for control of said switched inverter current by said variable inductance of said primary winding.