Patent ID: 7385358

Claim:
A power supply circuit for a first lamp and a second lamp, the power supply circuit comprising: a driving circuit for outputting an alternative voltage; and a transformer receiving the alternative voltage for driving the first lamp and the second lamp, the transformer comprising: a magnetic core; a primary coil set wound on the magnetic core and coupled to the driving circuit for receiving the alternative voltage; a primary coil set wound on the magnetic core and coupled to the driving circuit for receiving the alternating voltage a secondary coil wound on the magnetic core and having a positive high voltage end and a negative high voltage end; and a first coil, a second coil, a third and a fourth coil, all wound on the magnetic core, and the turns thereof being equal; wherein the positive high voltage end is coupled to one ends of the first and the third coils in parallel, the negative high voltage end is coupled to one ends of the second coil and the fourth coil in parallel, the first lamp is coupled between the other ends of the first and the second coils, and the second lamp is coupled between the other ends of the third and fourth coils respectively.