Patent ID: 7034465

Claim:
A device for operating a first discharge lamp ( 71 ) and a second discharge lamp ( 72 ), the device comprising: first and second terminals ( 20 , 21 ) for coupling to a first filament ( 711 ) of the first lamp ( 71 ); third and fourth terminals ( 22 , 23 ) for coupling to a second filament ( 712 ) of the first lamp ( 71 ); fifth and sixth terminals ( 24 , 25 ) for coupling to a first filament ( 721 ) of the second lamp ( 72 ); seventh and eighth terminals ( 26 , 27 ) for coupling to a second filament ( 722 ) of the second lamp ( 72 ); a resonance inductor (LRes) coupled to the seventh terminal ( 26 ); a resonance capacitor (CRes) coupled between the first terminal ( 20 ) and the seventh terminal ( 26 ); a current control device (PTC); a secondary coil (La) magnetically coupled to the resonance inductor (LRes) and electrically coupled series with the current control device (PTC); and a heating transformer comprising a primary coil (L hp ), a first secondary coil (L hs1 ), a second secondary coil (L hs2 ), and a third secondary coil (L hs3 ), wherein: the primary coil (L hp ) is coupled in series with the current control device (PTC) and the secondary coil (La); the first secondary coil (L hs1 ) is coupled between the first and second terminals ( 20 , 21 ); the second secondary coil (L hs2 ) is coupled between the fourth and sixth terminals ( 23 , 25 ); and the third secondary coil (L hs3 ) is coupled between the seventh and eighth terminals ( 26 , 27 ).