Patent ID: 6515431
Filing Date: 2003-02-04
Classification: H05B

Abstract:
A multi-lamp protection circuit for an electronic ballast comprising:a rectifying and filtering circuit; an inverter circuit; a plurality of lamp circuits; a plurality of abnormality detect circuits; and, characterized by every said lamp circuit connected to said inverter circuit, a current or voltage signal taken out of every said lamp circuit and sent to relative said abnormality detect circuit, a control signal and calculation by a plurality of AND gates controlling operation of a plurality of switches of said inverter circuit and indirectly checking out abnormal disorder signal of a lamps, then said lamp circuit(s) automatically cut off, and a control circuit needs only one gate signal control unit for controlling switches of an upper arm and lower arm(s) of half-bridge inverter(s), and the gate signals of upper and lower arms are out-phase.