Patent ID: 6242867
Filing Date: 2001-06-05
Classification: H05B,Y02B,Y10S

Abstract:
A circuit for synchronizing the ignition of an electronic ballast discharge lamp, 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 the 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 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.