Patent ID: 8030858

Claim:
An inverter circuit comprising: an inverter transformer which supplies a high AC voltage to a plurality of discharge tubes; a filter circuit connected to an output terminal of the inverter transformer to pass a current signal having a high frequency component of the high AC voltage; and an abnormal discharge detection circuit connected to the filter circuit to receive the current signal and detect an abnormal discharge current based on the current signal, wherein the abnormal discharge detection circuit comprises: a differential circuit connected to an output terminal of the filter circuit to output a differential signal based on the current signal having the high frequency component of the high AC voltage; a serial resonant circuit connected to an output terminal of the differential circuit to amplify the differential signal and output an amplified differential signal; a detection circuit connected to an output terminal of the serial resonant circuit to receive the amplified differential signal therefrom and output a detection signal based on the amplified differential signal; a peak hold circuit connected to an output terminal of the detection circuit to maintain a peak level of the detection signal; and a level detection circuit connected to an output terminal of the peak hold circuit to detect the peak level maintained by the peak hold circuit.