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US 6,781,325 B2Granted
Circuit structure for driving a plurality of cold cathode fluorescent lamps
AssigneeO2Micro International Limited
InventorSheng Tai Lee
Life of this patent
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Abstract
A DC/AC converter circuit structure for driving a plurality of cold cathode fluorescent lamps is described. A common-mode choke is used between the cold cathode fluorescent lamps. The common-mode choke balances the currents respectively flowing through the cold cathode fluorescent lamps.
Claims32
A DC/AC converter circuit structure for driving a plurality of the cold cathode fluorescent lamps, said circuit structure comprising:
- a power circuit;
- an isolated transformer connected to said power circuit, wherein said isolated transformer changes a voltage transferred from said power circuit;
- a plurality of capacitors, including a first to an Nth capacitor, respectively receiving the changed voltage;
- a plurality of loads, including a first to an Nth load, respectively connected to said corresponding plurality of capacitors;
- a plurality of common-mode choke, including a first to an (N−1)th common-mode choke, wherein each common-mode choke has two input ends, a grounded end and a non-grounded end, wherein the two input ends of said first common-mode choke are respectively connected to said first load and a second load, and the two input ends of a Kth common-mode choke are respectively connected to a (K+1)th load and the non-grounded end of a (K−1)th common-mode choke, where K=2, 3 . . . , N−1;
- and
- a dual diode connected to the non-grounded end of said (N−1)th common-mode choke to feed back a signal to said power circuit.
4 more elements
A DC/AC converter circuit structure for driving a plurality of the cold cathode fluorescent lamps, said circuit structure comprising:
- a power circuit;
- an isolated transformer connected to said power circuit, wherein said isolated transformer changes a voltage transferred from said power circuit;
- a plurality of capacitors, including a first to an Nth capacitor, respectively receiving a changed voltage;
- a plurality of common-mode chokes, including a first to an (N−1)th common-mode choke, each common-mode choke having two input ends, a first and a second output ends, wherein the two input ends of a (N−1)th common-mode choke are respectively connected to said Nth capacitor and a (N−1)th capacitor, and two input ends of a Kth common-mode choke are respectively connected to a Kth capacitor and the first output end of said (K+1)th common-mode choke, where K=1, 2 . . . , N−2;
- a plurality of loads, including a first to an Nth load, wherein said first load and a second load are respectively connected to the first and the second output ends of said first common-mode choke, and an Mth load is connected to a second output of an (M−1)th common-mode choke, where M=3, 4 . . . , N;
- and
- a dual diode connected to said Nth load to feed back a signal to said power circuit.
4 more elements
An DC/AC converter circuit structure for driving a plurality of the cold cathode fluorescent lamps, said circuit structure comprising:
- a power circuit;
- an isolated transformer connected to said power circuit, wherein said isolated transformer changes a voltage transferred from said power circuit;
- a capacitor receiving a changed voltage;
- a plurality of loads, including a first to an Nth load, connected to said capacitor;
- a plurality of common-mode chokes, including a first to an (N−1)th common-mode choke, each common-mode choke having two input ends, a grounded end and a non-grounded end, wherein the two input ends of said first common-mode choke are respectively connected to said first load and a second load, and the two input ends of a Kth common-mode choke are respectively connected to a (K+1)th load and the non-grounded end of a (K−1)th common-mode choke, where K=2, 3 . . . , N−1;
- and
- a dual diode connected to the non-grounded end of said (N−1)th common-mode choke to feed back a signal to said power circuit.
4 more elements
A DC/AC converter circuit structure for driving a plurality of cold cathode fluorescent lamps, said circuit structure comprising:
- a power circuit;
- an isolated transformer connected to said power circuit, wherein said isolated transformer changes a voltage transferred from said power circuit;
- a capacitor receiving a changed voltage;
- a plurality of common-mode chokes, including a first to an (N−1)th common-mode choke, said each common-mode choke having two input ends, including a first and a second output end, wherein the two input ends of said (N−1)th common-mode choke are connected to said capacitor, and the two input ends of a Kth common-mode choke are respectively connected to said capacitor and the first output end of a (K+1)th common-mode choke, and K=1, 2 . . . , N−2;
- a plurality of loads, including a first to an Nth load, wherein said first load and a second load are respectively connected to the first and the second output ends of said first common-mode choke, and an Mth load is connected to the second output of an (M−1)th common-mode choke, and M=3, 4 . . . , N;
- and
- a dual diode connected to said Nth load to feed back a signal to said power circuit.
4 more elements
Dependencies are inferred from the claim text.