Patent ID: 6828732
Filing Date: 2004-12-07
Classification: H05B

Abstract:
A fluorescent lamp end-of-life protection circuit, comprising:a lamp tube rectifying effect protection circuit for shorting both ends of a fluorescent lamp when rectifying effect occurs in its lamp tube; and a lamp tube overvoltage protection circuit for shorting both ends of the fluorescent lamp when overvoltage occurs in its lamp tube; wherein said lamp tube rectifying effect protection circuit includes two series resistors, a capacitor, a trigger diode, and a triac; said lamp tube overvoltage protection circuit includes a transient voltage suppresser, a diode, one of two series resistors connected to said capacitor, said capacitor, said trigger diode, and said triac; and wherein, a circuitry of said two series resistors and said capacitor in series is connected in parallel with the lamp tube; a cathode of said transient voltage suppresser is connected to one end of the lamp tube, its anode is connected to a anode said diode, and a cathode of the diode is connected to a common node of said two series resistors; one end of said trigger diode is connected to a connection node between the capacitor and the resistors, and the other end thereof is connected to a gate terminal of said triac; other two electrodes of the triac are connected to two ends of the lamp tube respectively.