Circuit for synchronizing the ignition of electronic ballast...

Details Circuit for synchronizing the ignition of electronic ballast... Circuit for synchronizing the ignition of electronic ballast...

2000-06-23

2001-06-05

Philogene, Haissa (Department: 2821)

Electric lamp and discharge devices: systems

Periodic switch in the supply circuit

Impedance or current regulator in the supply circuit

C315S219000, C315S282000, C315S2090SC, C315SDIG007

Reexamination Certificate

active

06242867

ABSTRACT:

TECHNICAL FIELD
The present invention relates to the art of igniting discharge lamps, and more particularly, to a circuit for synchronizing the ignition of electronic ballast discharge lamps.
The invention is especially useful for igniting high intensity discharge (HID) lamps, e.g., high pressure sodium (HPS) lamps, while protecting the ballast circuits against damage when the lamp does not ignite and repeated attempts to do so are performed.
BACKGROUND ART
A great number of electronic ballast circuits for igniting HID lamps are known and utilized. All known half-bridge ballasts suffer from the drawback of their failure to protect the ballast against damage during the starting or striking period of the lamp when the lamp is out of order and will not ignite.
For the sake of completeness and better understanding, a typical prior art HPS ballast circuit such as those referred to above, is shown in FIG.
1
. The circuit is illustrated and described in detail in an article by Peter N. Wood, entitled “Electronic Ballasts Using the Cost-Saving IR2155 Driver,”
MOS
-
Gate Driver Data Book
, E50161, International Rectifier Application Notes (1995).
DISCLOSURE OF THE INVENTION
It is therefore a broad object of the present invention to provide an electronic ballast circuit for HID lamps which is capable of protecting the ballast against damage during attempts to ignite it, when the lamp is not susceptible to striking.
Therefore, in accordance with the present invention, there is provided a circuit for synchronizing the ignition in electronic ballast discharge lamps, including a half-bridge output stage of the electronic ballast having a upper switch and a lower switch, said lower switch being connected to a common wire of a power supply, in which circuit a high voltage impulse for igniting the lamp is only generated when the lower switch is open, said circuit comprising a transformer including a first winding and a second winding magnetically coupled to each other, said second winding having a lower number of turns than said first winding; one lead of said first winding being connectable to an electrode of a discharge lamp and a second lead thereof being connectable to the common wire of said power supply; a diode connected with its anode to one lead of said second winding and with its cathode to the junction between said upper and lower switches; a second lead of said second winding connected to a symmetrical diode thyristor, said thyristor being connected to the first plate of a discharge capacitor and the second plate of said capacitor being connected to said common wire; whereby discharge current of said capacitor flows through said second winding only when said lower switch is open.
The invention further provides a circuit for synchronizing the ignition in electronic ballast discharge lamps, including a half-bridge output stage of the electronic ballast having a upper switch and a lower switch, said lower switch being connected to a common wire of a power supply, in which circuit a high voltage impulse for igniting the lamp is only generated when the lower switch is open, said circuit comprising a transformer including a first winding and a second winding magnetically coupled to each other, said second winding having a lower number of turns than said first winding; one lead of said first winding being connectable to an electrode of a discharge lamp and a second lead thereof being connected to the junction between said upper and lower switches through a separating capacitor; a diode connected with its anode to one lead of said second winding through a thyristor, and with its cathode to the junction between said first and second power switches; a second lead of said second winding being connected to said common wire through a discharge capacitor; whereby discharge current of said capacitor flows through said second winding only when said lower switch is open.
The invention still further provides a circuit for synchronizing the ignition in electronic ballast discharge lamps, including a half-bridge output stage of the electronic ballast having a upper switch and a lower switch, said lower switch being connected to a common wire of a power supply, in which circuit a high voltage impulse for igniting the lamp is only generated when the lower switch is open, said circuit comprising a transformer including a first winding and a second winding magnetically coupled to each other, said second winding having a lower number of turns than said first winding; one lead of said first winding being connectable to an electrode of a discharge lamp and a second lead thereof being connectable to the common wire of said power supply; a diode connected with its anode to one lead of said second winding through a thyristor, and with its cathode to the junction between said first and second power switches; a second lead of said second winding being connected to said common wire through a discharge capacitor; whereby discharge current of said capacitor flows through said second winding only when said lower switch is open.


REFERENCES:
patent: 4291254 (1981-09-01), Arlt et al.
patent: 4484108 (1984-11-01), Stupp et al.
patent: 5233273 (1993-08-01), Waki et al.
patent: 5384518 (1995-01-01), Kido et al.
patent: 5739644 (1998-04-01), Bernitz et al.
patent: 5945786 (1999-08-01), Jurek

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