Patent ID: 7446750

Claim:
An inverter comprising: a voltage converter that converts a DC voltage from an external device into an AC voltage to drive at least a lamp and includes a primary coil and first and second secondary coils connected in series; a current sensor that senses at least a current flowing in the first or second secondary coil and generates at least a sensing signal based on the sensed at least a current, wherein the current sensor comprises first and second resistors connected in series between the first secondary coil and the second secondary coil, and a third resistor connected between a predetermined constant voltage and a first node between the first resistor and the second resistor, and further wherein a voltage at the first node is different from the predetermined constant voltage; a feedback signal generator that generates a feedback signal based on the at least a sensing signal from the current sensor; and a controller that controls the voltage converter based on the feedback signal such that a tube current flowing in the at least a lamp keeps substantially constant.