Patent ID: 7423384

Claim:
A method for detecting an open lamp condition or a shorted lamp condition in a discharge lamp system, comprising: providing a DC bias, V bias , from a DC bias source to an OR gate detector circuit that is coupled to a plurality of discharge lamps, said OR gate detector circuit including: a plurality of sensing capacitors being coupled to said DC bias source and said plurality of discharge lamps, wherein one sensing capacitor corresponds to one discharge lamp; and a plurality of diodes being coupled to said plurality of sensing capacitors, wherein one diode corresponds to one sensing capacitor; and deriving a voItage signal from said OR detector circuit; if said voltage signal satisfies an open lamp condition, triggering an open lamp protection process; and if said voltage signal satisfies a shorted lamp condition, triggering a shorted lamp protection process, wherein said voltage signal is related to a maximum sensing capacitor voltage of said plurality of discharge lamps at any given moment.