Patent ID: 7126289

Claim:
A cold cathode fluorescent lamp driving circuit with protection function for driving a plurality of cold cathode fluorescent lamps comprising: a first transformer coupled to said plurality of cold cathode fluorescent lamps; a switching network coupled to said first transformer which delivers power to said first transformer; a sensing circuit coupled to said plurality of cold cathode fluorescent lamps which detects disconnection if one cold cathode fluorescent lamp is disconnected, wherein said sensing circuit comprises a first end sensing circuit for detecting disconnection if said one cold cathode fluorescent lamp is disconnected on one end, and wherein said first end sensing circuit comprises a first sensing resistance and a second sensing resistance, wherein said first end sensing circuit senses a first voltage on said first sensing resistance and a second voltage on said second sensing resistance and detects disconnection if a sum of said first voltage and said second voltage exceeds a first predetermined level; and a controller coupled to said switching network which controls said switching network to reduce the total current supplied to the cold cathode fluorescent lamps which remain connected if said sensing circuit detects that said one cold cathode fluorescent lamp is disconnected.