Patent ID: 8115402
Filing Date: 2012-02-14
Classification: H05B,Y02B

Abstract:
1. An apparatus for driving multiple discharge lamps, comprising a switching circuit having at least one switch; an open lamp detection circuit, electrically coupled to said discharge lamps, detecting whether the open lamp condition exists and generating an open lamp signal; a frequency sweeping circuit, electrically coupled to said open lamp detection circuit, that increases the switching frequency of the at least one switch when the open lamp condition is detected; and a current sensing circuit, electrically coupled to said multiple discharge lamps, sensing the current flowing through said discharge lamps and generating current sensing signals representative of them, wherein said open lamp detection circuit is electrically coupled to said current sensing circuit to receive said current sensing signals and detect whether the open lamp condition exists based on them, wherein said discharge lamps are in parallel, and a capacitor is serially connected to each discharge lamp, wherein the switching frequency is held by said frequency sweeping circuit when an output voltage of the driving apparatus reaches a striking voltage, wherein said open lamp detection circuit comprises: