COLD CATHODE FLUORESCENT LAMP INVERTER APPARATUS

• US 20080150444A1
• Filed: 12/12/2007
• Published: 06/26/2008
• Est. Priority Date: 12/26/2006
• Status: Active Grant

• Current Assignee: Sanken Electric Company Limited
• Original Assignee: Sanken Electric Company Limited
• Inventors: Ashikaga, Toru, Usui, Hiroshi, Cho, Jaehee
• Granted Patent: US 7,994,736 B2
• Time in Patent Office: Days
• US Class Current: 315/219
• CPC Class Codes: H05B 41/2858 for protecting the lamp against abnormal operating conditions
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A cold cathode fluorescent lamp inverter apparatus includes a series circuit connected to a DC power source and including first and second switching elements, a series circuit connected between a connection point of the first and second switching elements and the DC power source and including a primary winding of a transformer, a reactor, and a capacitor, a cold cathode fluorescent lamp connected to a secondary winding of the transformer, a current detector connected to the cold cathode fluorescent lamp and to the secondary winding, to detect a value of a current passed through the cold cathode fluorescent lamp, and a controller to turn on/off the first and second switching elements alternately with each other according to the detected current value. The current detector detects a ripple component in the DC power source, and corrects the current of the cold cathode fluorescent lamp according to the detected ripple component.

Claims

1. A cold cathode fluorescent lamp inverter apparatus comprising:

a DC power source configured to rectify an AC voltage of an AC power source;

a first series circuit connected to both ends of the DC power source and including a first switching element and a second switching element;

a second series circuit connected between a connection point of the first and second switching elements and one of the ends of the DC power source and including a primary winding of a transformer, a reactor, and a capacitor;

at least one cold cathode fluorescent lamp having a first end connected to a first end of a secondary winding of the transformer;

a current detector having a first end connected to a second end of the at least one cold cathode fluorescent lamp and a second end connected to a second end of the secondary winding of the transformer, the current detector being configured to detect a value of a current passing through the at least one cold cathode fluorescent lamp; and

a controller configured to turn on/off the first and second switching elements alternately with each other according to the current value detected by the current detector so that the current passing through the at least one cold cathode fluorescent lamp may have a predetermined value, wherein

at least one of the current detector and controller is configured to detect a ripple component in the DC power source, and correct a detected value of the current passing through the at least one cold cathode fluorescent lamp according to the detected ripple component.

4. The apparatus of claim 1, wherein

the reactor is a leakage inductance between the primary and secondary windings of the transformer.

7. The apparatus of claim 1, wherein

the reactor is an inductance connected in series with the primary winding of the transformer and/or the secondary winding of the transformer.

2. A cold cathode fluorescent lamp inverter apparatus comprising:

a DC power source configured to rectify an AC voltage of an AC power source;

a first series circuit connected to both ends of the DC power source and including a first switching element and a second switching element;

a second series circuit connected between a connection point of the first and second switching elements and one of the ends of the DC power source and including a primary winding of a transformer, a reactor, and a capacitor;

at least one cold cathode fluorescent lamp having a first end connected to a first end of a secondary winding of the transformer;

a current detector having a first end connected to a second end of the at least one cold cathode fluorescent lamp and a second end connected to a second end of the secondary winding of the transformer, the current detector being configured to detect a value of a current passing through the at least one cold cathode fluorescent lamp; and

a controller configured to turn on/off the first and second switching elements alternately with each other according to the current value detected by the current detector so that the current passing through the at least one cold cathode fluorescent lamp may have a predetermined value, wherein

at least one of the current detector and controller is configured to detect a DC voltage value of the DC power source, and correct a detected value of the current passing through the at least one cold cathode fluorescent lamp according to the detected DC voltage value.

5. The apparatus of claim 2, wherein

the reactor is a leakage inductance between the primary and secondary windings of the transformer.

8. The apparatus of claim 2, wherein

the reactor is an inductance connected in series with the primary winding of the transformer and/or the secondary winding of the transformer.

3. A cold cathode fluorescent lamp inverter apparatus comprising:

a DC power source configured to rectify an AC voltage of an AC power source;

a DC-DC converter configured to receive power from the DC power source;

a first series circuit connected to both ends of the DC power source and including a first switching element and a second switching element;

a second series circuit connected between a connection point of the first and second switching elements and one of the ends of the DC power source and including a primary winding of a transformer, a reactor, and a capacitor;

at least one cold cathode fluorescent lamp having a first end connected to a first end of a secondary winding of the transformer;

a current detector having a first end connected to a second end of the at least one cold cathode fluorescent lamp and a second end connected to a second end of the secondary winding of the transformer, the current detector being configured to detect a value of a current passing through the at least one cold cathode fluorescent lamp; and

a controller configured to turn on/off the first and second switching elements alternately with each other according to the current value detected by the current detector so that the current passing through the at least one cold cathode fluorescent lamp may have a predetermined value, wherein

at least one of the current detector and controller is configured to detect a DC voltage value of the DC power source by detecting an output of the DC-DC converter, and correct a detected value of the current passing through the at least one cold cathode fluorescent lamp according to the detected DC voltage value.

6. The apparatus of claim 3, wherein

the reactor is a leakage inductance between the primary and secondary windings of the transformer.

9. The apparatus of claim 3, wherein

the reactor is an inductance connected in series with the primary winding of the transformer and/or the secondary winding of the transformer.