Patent ID: 7436129

Claim:
A driver circuit for providing a lamp drive current from a power source to a fluorescent lamp producing a light having a brightness, the circuit comprising: a transformer having a primary winding and a secondary winding, wherein each of the primary and secondary windings have a first and a second end and are configured to conduct an electrical current having a polarity, and wherein the ends of the secondary winding are coupled to provide the lamp drive current to the fluorescent lamp; a current steering module configured to provide a drive output from the power source to the transformer in response to a current steering input; a current control loop configured to adjust the current steering input in response to the current in one of the windings of the transformer; a luminance control loop configured to adjust the current steering input in response to the brightness of the light; and a lamp frequency control loop configured to adjust the polarity of the electrical current in the primary winding in response to a signal received from the transformer to thereby adjust the frequency of the lamp drive current applied to the fluorescent lamp.