Patent ID: 8436547

Claim:
A multi-lamp driving system, to drive a plurality of lamps, comprising a filter circuit, a switch circuit, a pulse width modulation (PWM) controller, and a protection circuit, wherein the multi-lamp driving system further comprises: a plurality of transformers, each of the plurality of transformers comprising a primary winding and a secondary winding, wherein the primary windings of the plurality of transformers are connected to the switch circuit in parallel, and high voltage terminals of the secondary windings of the plurality of transformers are connected to the plurality of lamps, respectively; an abnormity detection circuit, connected to the plurality of transformers and the protection circuit, the abnormity detection circuit comprising: a signal converting circuit, connected to low voltage terminals of the secondary windings of the plurality of transformers, to convert current signals flowing through the plurality of lamps into voltage signals; a highest current retrieving circuit, connected to the signal converting circuit, to retrieve a highest voltage signal corresponding to a highest current signal flowing through the plurality of lamps from the voltage signals; a lowest current retrieving circuit, connected to the signal converting circuit, to retrieve a lowest voltage signal corresponding to a lowest current signal flowing the plurality of lamps; and a comparison circuit, connected to the highest current retrieving circuit and the lowest current retrieving circuit, to determine if a difference between the highest voltage signal and the lowest voltage signal exceeds a predetermined value, and to generate a trigger signal if the difference between the highest voltage signal and the lowest voltage signals exceeds the predetermined value; wherein upon receiving the trigger signal, the protection circuit controls the PWM controller to stop outputting PWM signals to the switch circuit.