Floating drive circuit for cold cathode fluorescent lamp

• US 20060071615A1
• Filed: 10/01/2004
• Published: 04/06/2006
• Est. Priority Date: 10/01/2004
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Sun, Chia-Hung, Wey, Chin-Der, Li, Hsien-Jen, Chen, Kuei-Lin
• Granted Patent: US 7,309,964 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 41/282 with semiconductor devices H05B41/2806, H05B41/288, H05B41/295 take precedence
• CPC Class Codes: H05B 41/2827 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A floating driving device for illumination includes a illumination unit having a first terminal and a second terminal. A first driver is electrically coupled to the first terminal of the illumination unit, for applying AC voltages to the first terminal. A second driver is electrically coupled to the second terminal of the illumination unit, for applying AC voltages to the second terminal in such a manner that the AC voltages at the first terminal and the second terminal are out of phase.

Claims

1. A floating driving device for illumination comprising:

a illumination unit having a first terminal and a second terminal;

a first driver, electrically coupled to the first terminal of the illumination unit, for applying AC voltages to the first terminal; and

a second driver, electrically coupled to the second terminal of the illumination unit, for applying AC voltages to the second terminal in a manner that the AC voltages at the first terminal and the second terminal are out of phase.

2. The floating driving device of claim 1, wherein the illumination unit is a cold cathode florescent lamp.

3. The floating driving device of claim 1, wherein the first driver and the second driver are transformers.

4. The floating driving device of claim 1, wherein the AC voltages at the first terminal and the second terminal are 180 degrees out of phase.

5. The floating driving device of claim 4, wherein the AC voltages at the first terminal and the second terminal have the same magnitude and frequency.

6. The floating driving device of claim 1, further comprising an additional illumination unit having a third terminal connected to the first driver, and a fourth terminal connected to the second driver.

7. The floating driving device of claim 6, further comprising a balance circuit, connected to the first driver, for balancing output signals from the first driver to the illumination unit and the additional illumination unit.

8. The floating driving device of claim 7, wherein the illumination unit and the additional illumination unit are cold cathode florescent lamps.

9. The floating driving device of claim 7, wherein the first driver and the second driver are transformers.

10. A floating driving device for illumination comprising:

a plurality of illumination units, each of which has a first terminal and a second terminal, and the second terminals of the plurality of illumination units are electrically coupled together; and

a driver, electrically coupled to the first terminals of the plurality of illumination units, for applying AC voltages to the first terminals.

11. The floating driving device of claim 10, wherein the plurality of illumination units are cold cathode fluorescent lamps.

12. The floating driving device of claim 10, wherein the driver is a transformer.

13. The floating driving device of claim 10, wherein the AC voltages at the first terminal and the second terminal are 180 degrees out of phase.

14. The floating driving device of claim 13, wherein the AC voltages at the first terminal and the second terminal have the same magnitude and frequency.

15. The floating driving device of claim 10, further comprising at least one balance circuit, connected to the driver, for balancing output signals from the driver to the plurality of illumination units.

16. The floating driving device of claim 10, wherein the driver comprises a first driver unit and a second driver unit.

17. The floating driving device of claim 16, further comprising a first balance circuit connected to the first driver unit, and a second balance circuit connected to the second driver unit, for balancing output signals from the first driver unit and the second driver unit to the plurality of the illumination units.

18. The floating driving device of claim 17, wherein the illumination units are cold cathode florescent lamps.

19. The floating driving device of claim 17, wherein the first driver unit and the second driver unit are transformers.

20. A floating driving device for illumination comprising:

a plurality of illumination units, each of which has a first terminal and a second terminal;

a first driver, electrically coupled to the first terminals of the plurality of illumination units, for applying AC voltages to the first terminals;

a second driver, electrically coupled to the second terminals of the plurality of illumination units, for applying AC voltages to the second terminals in a manner that the AC voltages at the first terminal and the second terminal are out of phase; and

a balance circuit, connected to the first driver, having impedance that is adjusted to generate balancing output signals to the plurality of illumination units.

21. The floating driving device of claim 20, wherein the balance circuit is coupled between the plurality of illumination units and the first driver.

22. The floating driving device of claim 21, wherein the balance circuit is connected to the first driver through a parallel capacitor.

23. The floating driving device of claim 21, wherein the balance circuit comprises a first capacitor and a second capacitor connected, in parallel, to the first driver.

24. The floating driving device of claim 23, wherein the balance circuit further comprises a first inductor and a second inductor connecting the first capacitor and the second capacitor to the plurality of illumination units, respectively.

25. The floating driving device of claim 21, wherein the balance circuit comprises a first inductor and a second inductor connected, in parallel, to the first driver.

26. The floating driving device of claim 25, wherein the balance circuit further comprises a first capacitor and a second capacitor connecting the first inductor and the second inductor to the plurality of illumination units, respectively.

27. The floating driving device of claim 20, wherein the first driver is coupled between the plurality of illumination units and the balance circuit.

28. The floating driving device of claim 27, wherein the balance circuit comprises an inductor and a capacitor, the capacitor being coupled between the first driver and the inductor.

29. The floating driving device of claim 27, wherein the balance circuit comprises a first inductor and a second inductor coupled to the first driver in parallel.

30. The floating driving device of claim 29, wherein the balance circuit further comprises a first capacitor and a second capacitor coupled between the first driver and the first inductor and the second inductor, respectively.