Electronic ballast

• US 20100102742A1
• Filed: 10/22/2009
• Published: 04/29/2010
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Feelux Company Limited
• Original Assignee: Feelux Company Limited
• Inventors: Park, Hyun Joo, Choi, Woo Sung
• Granted Patent: US 8,164,280 B2
• Time in Patent Office: Days
• US Class Current: 315/247
• CPC Class Codes: H05B 41/2885 Static converters especially adapted therefor; Control thereof H05B41/2882 takes precedence
• CPC Class Codes: H05B 41/42 in two steps only
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

Provided is an electronic ballast including: a rectifier which rectifies alternating current (AC) power into direct current (DC) power; a power factor compensator which improves a power face of the DC power; an inverter which inverts the DC current into high frequency square wave power; and a resonant circuit which receives the high frequency square wave power from the inverter, adjusts impedance, transforms the high frequency square wave power into high frequency sine wave power, and outputs the high frequency sine wave power.

Claims

1. An electronic ballast comprising:

a rectifier which rectifies alternating current (AC) power into direct current (DC) power;

a power factor compensator which improves a power face of the DC power;

an inverter which inverts the DC current into high frequency square wave power; and

a resonant circuit which receives the high frequency square wave power from the inverter, adjusts impedance, transforms the high frequency square wave power into high frequency sine wave power, and outputs the high frequency sine wave power.

2. The electronic ballast of claim 1, wherein the resonant circuit comprises an inductance adjuster and a capacitor.

3. The electronic ballast of claim 2, wherein when the inverter comprises first and second nodes as output nodes,

the resonant circuit comprises:

a first resonant capacitor which comprises an end connected to the first node and an other end connected to the inductance adjuster; and

a second resonant capacitor which comprises an end connected to the second node and an other end connected to the inductance adjuster, and

the inductance adjuster comprises;

a variable inductor which comprises an end connected to the another end of the first resonant capacitor; and

a switch which comprises an end selectively connected to one of a node and an other end of the variable inductor and an other end connected to the other end of the second resonant capacitor.

4. The electronic ballast of claim 2, wherein when the inverter comprises first and second nodes as output nodes,

the resonant circuit comprises:

a first resonant capacitor which comprises an end connected to the first node and an other end connected to the inductance adjuster; and

a second resonant capacitor which comprises an end connected to the second node and an other end connected to the inductance adjuster, and

the inductance adjuster comprises;

a first resonant inductor which comprises an end connected to the other end of the first resonant capacitor;

a second resonant inductor which comprises an end connected to an other end of the first resonant capacitor; and

a switch which comprises an end selectively connected to one of the other end of the first resonant inductor and an other end of the second resonant inductor and an other end connected to the other end of the second resonant capacitor.

5. The electronic ballast of claim 2, wherein when the inverter comprises first and second nodes as output nodes,

the resonant circuit comprises:

a first resonant capacitor which comprises an end connected to the first node and an other end connected to the inductance adjuster; and

a second resonant capacitor which comprises an end connected to the second node and an other end connected to the inductance adjuster, and

the inductance adjuster comprises;

first through n^th resonant inductors which comprise ends respectively connected to the other end of the first resonant capacitor in parallel; and

a switch which comprises ends selectively connected to other ends of the first through n_th resonant inductors and an other end connected to the other end of the second resonant capacitor.

6. The electronic ballast of claim 1, wherein when the inverter comprises first and second nodes as output nodes, the resonant circuit comprises a first resonant capacitor and an inductor which are sequentially connected to the first node and a capacitance adjuster which is connected between the inductor and the second node.

7. The electronic ballast of claim 6, wherein the capacitance adjuster comprises:

a second resonant capacitor which comprises an end connected to the second node;

a third resonant capacitor which comprises an end connected to the second node; and

a switch which comprises an end selectively connected to one of an other end of the second resonant capacitor and an other end of the third resonant capacitor and an other end connected to the inductor.

8. The electronic ballast of claim 6, wherein the capacitance adjuster comprises:

second through n^th resonant capacitors which comprise ends respectively connected to the second node in parallel; and

a switch which comprises ends selectively connected to other ends of the second through n^th resonant capacitors and an other end connected to the inductor.

9. The electronic ballast of claim 3, wherein the switch is connected to and controlled by a switch control which is positioned outside a fluorescent lamp case.