Patent ID: 8013543

Claim:
A backlight control circuit comprising: a transformer, a control circuit, and a lamp, the control circuit and the transformer forming an inverter circuit capable of providing an alternating current (AC) voltage for driving the lamp, wherein the transformer comprises a primary winding and a secondary winding, two terminals of the primary winding are coupled to the control circuit, and the AC voltage is outputted from the secondary winding; and a first capacitor, a reactance element, and a first switching element; wherein when the backlight control circuit works in a startup mode, the backlight control circuit defines a first current path comprising the lamp and the first current path forms a first resonant circuit, the first resonant circuit being formed by the lamp, the secondary winding and the first capacitor; and when the backlight control circuit works in an operation mode, the backlight control circuit defines a second current path comprising the lamp and the second current path forms a second resonant circuit, the second resonant circuit being formed by the lamp, the secondary winding, the first switching element, the reactance element and the first capacitor, the first and second resonant circuits having different resonant frequencies from each other.