Inverter circuit, fluorescent tube lighting apparatus, backlight apparatus, and liquid crystal display

• US 7,786,681 B2
• Filed: 09/14/2007
• Issued: 08/31/2010
• Est. Priority Date: 08/06/2002
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shimizu, Masaki, Inoue, Yutaka, Ohtani, Shuhki
• Primary Examiner(s): Owens; Douglas W
• Assistant Examiner(s): A; Minh D
• Application Number:
  US11/855,536
• Publication Number:
  US 20080012500A1
• Time in Patent Office: 1,082 Days
• Field of Search: 3151691-1693, 315/169.4, 315/312, 315/277, 315/185.R, 315/294, 345/76, 345/84, 345/104, 345/105
• US Class Current: 315/277
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H05B 41/2821 by means of a single-switch converter or a parallel push-pull converter in the final stage H05B41/285 takes precedence
• CPC Class Codes: H05B 41/2822 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 driving apparatus and a driving method are disclosed that are capable of uniformly lighting each entire fluorescent tube irrespective of the length or number of fluorescent tubes when simultaneously driving a plurality of fluorescent tubes in a fluorescent tube lighting apparatus. When two inverter circuits having respective transformers are provided at both ends of a fluorescent tube to light the fluorescent tube by push-pull driving, feedback windings of transformers not used in self-excited oscillation of each inverter circuit are connected together, with the transformer connection that connects together the feedback windings being either in-phase or in opposite phase, and the method of connection for fluorescent tubes connecting to secondary windings of each transformer can be changed in accordance with that connection method.

Claims

1. A backlight apparatus comprising:

a plurality of long-tubular-type fluorescent tubes disposed so that the longitudinal directions thereof are parallel to one another; and

first and second inverter transformers,

wherein the inverter transformers apply voltages having opposite phases to respective ends of each fluorescent tube for driving the plurality of fluorescent tubes simultaneously, and apply voltages having opposite phases to the respective adjacent ends of the plurality of fluorescent tubes, and

wherein a transformer having a single primary winding and a plurality of secondary windings that convert a voltage inputted to the primary winding into a high voltage and output the high voltage is used for each inverter transformer.

2. The backlight apparatus according to claim 1, wherein at least two of the plurality of secondary windings are wound reversely with each other.

5. The backlight apparatus according to claim 1 or 3, further comprising:

a pair of both-end fixtures for disposing the ends of each of the fluorescent tubes in predetermined positions; and

a fixture for fixing each of the fluorescent tubes between the both-end fixtures.

6. The backlight apparatus according to claim 5, wherein a plurality of the fixtures are provided between the both-end fixtures for at least one of the plurality of fluorescent tubes.

7. A liquid crystal display device comprising:

the backlight apparatus according to claim 1 or 3; and

a liquid crystal panel illuminated by the backlight apparatus for displaying video.

3. A backlight apparatus comprising:

a plurality of long-tubular-type fluorescent tubes disposed so that the longitudinal directions thereof are parallel to one another; and

first and second inverter transformers, each having a plurality of secondary windings each for increasing a voltage inputted to a primary winding and outputting the increased voltage,

wherein the voltage increased by one of the secondary windings of the first inverter transformer is applied to one-end side of the fluorescent tubes, and the voltage increased by one of the secondary windings of the other inverter transformer is applied to the other-end side of the fluorescent tubes, so as to drive the plurality of fluorescent tubes, and

wherein the number of windings of the first inverter transformer is the same as the number of windings of the second inverter transformer.

4. The backlight apparatus according to claim 3, wherein the magnitudes of the voltages applied to the ends of the fluorescent tubes are essentially same.

8. A backlight apparatus comprising,

a plurality of fluorescent tubes disposed so that the longitudinal directions thereof are substantially parallel to one another;

and

an inverter circuit having first and second inverter transformers,

wherein the inverter transformers apply voltages having opposite phases to respective ends of each fluorescent tube for driving the plurality of fluorescent tubes simultaneously, and apply voltages having opposite phases to the respective adjacent ends of the plurality of fluorescent tubes, and

wherein the inverter transformers each have a single primary winding and a plurality of secondary windings that convert a voltage inputted to the primary winding into a high voltage and output the high voltage.

9. A drive apparatus comprising:

first and second inverter transformers each having a primary winding and a plurality of secondary windings for increasing a voltage inputted to the primary winding, the apparatus driving a plurality of fluorescent tubes disposed so that the longitudinal directions thereof are substantially parallel to one another,

wherein, when the plurality of fluorescent tubes are driven, the voltage increased by one of the secondary windings of the first inverter transformer is applied to one-end of the fluorescent tubes, and the voltage increased by one of the secondary windings of the other inverter transformer is applied to the other-end of the fluorescent tubes, and

wherein the number of windings of the first inverter transformer, is the same as the number of windings of the second inverter transformer.

10. The drive apparatus according to claim 9, wherein the magnitudes of voltages applied to the ends of the fluorescent tubes are essentially same.

11. An inverter circuit comprising:

first and second inverter transformers each having a primary winding and a plurality of secondary windings for increasing a voltage inputted to the primary winding, the apparatus driving a plurality of fluorescent tubes disposed so that the longitudinal directions thereof are substantially parallel to one another,

wherein, when the inverter circuit is used for driving the plurality of fluorescent tubes, the voltage increased by one of the secondary windings of the first inverter transformer is applied to one-end of the fluorescent tubes, and the voltage increased by one of the secondary windings of the second inverter transformer is applied to the other-end of the fluorescent tubes, and

wherein the number of windings of the first inverter transformer, is the same as the number of windings of the second inverter transformer.

12. A backlight apparatus comprising:

a plurality of long-tubular-type fluorescent tubes disposed so that the longitudinal directions thereof are parallel to one another; and

an inverter transformer,

wherein the inverter transformer applies voltages having opposite phases to adjacent ends of each of the fluorescent tubes for driving the plurality of fluorescent tubes simultaneously, and

wherein a transformer having a single primary winding and a plurality of secondary windings that convert a voltage inputted to the primary winding into a high voltage and output the high voltage is used as the inverter transformer.

13. The backlight apparatus according to claim 12, wherein at least two of the plurality of secondary windings are wound reversely with each other.

16. The backlight apparatus according to claim 12 or 14, further comprising:

a pair of both-end fixtures for disposing the ends of each of the fluorescent tubes in predetermined positions; and

a fixture for fixing each of the fluorescent tubes between the both-end fixtures.

17. The backlight apparatus according to claim 16, wherein a plurality of the fixtures are provided between the both-end fixtures for at least one of the plurality of fluorescent tubes.

18. A liquid crystal display device comprising:

the backlight apparatus according to claim 12 or 14; and

a liquid crystal panel illuminated by the backlight apparatus for displaying video.

14. A backlight apparatus comprising:

a plurality of long-tubular-type fluorescent tubes disposed so that the longitudinal directions thereof are parallel to one another; and

a plurality of secondary windings each for increasing a voltage inputted to a primary winding and outputting the increased voltage,

wherein the voltage increased by one of the secondary windings is applied to one-end side of one of the fluorescent tubes, and the voltage increased by the other secondary winding is applied to a one-end side of a fluorescent tube adjacent to the on fluorescent tube, so as to drive the plurality of fluorescent tubes, and

wherein the number of windings of an inverter transformer which supplies the voltage to one-end side of the plurality of fluorescent tubes, is the same as the number of windings of an inverter transformer which supplies the voltage to the other-end side of the plurality of fluorescent tubes.

15. The backlight apparatus according to claim 14, wherein the magnitudes of the voltages applied to the ends of the fluorescent tubes are essentially same.

19. A backlight apparatus comprising:

a plurality of fluorescent tubes disposed so that the longitudinal directions thereof are substantially parallel to one another; and

an inverter circuit,

wherein the inverter circuit applies voltages having opposite phases to the adjacent ends of each of the fluorescent tubes for driving the plurality of fluorescent tubes simultaneously, and

wherein the inverter circuit is provided with a transformer having a single primary winding and a plurality of secondary windings that convert a voltage inputted to the primary winding into a high voltage and output the high voltage.

20. A drive apparatus comprising:

an inverter transformer having a primary winding and a plurality of secondary windings for increasing a voltage inputted to the primary winding, the apparatus driving a plurality of fluorescent tubes disposed so that the longitudinal directions thereof are substantially parallel to one another,

wherein, when the plurality of fluorescent tubes are driven, the voltage increased by one of the secondary windings is applied to one-end of one fluorescent tube of the plurality of fluorescent tubes, and the voltage increased by the other secondary winding is applied to an end of another fluorescent tube of the plurality of fluorescent tubes that is adjacent to the one-end of the one fluorescent tube, and

wherein the number of windings of an inverter transformer which supplies the voltage to one-end side of the plurality of fluorescent tubes, is the same as the number of windings of an inverter transformer which supplies the voltage to the other-end side of the plurality of fluorescent tubes.

21. The drive apparatus according to claim 20, wherein the magnitudes of voltages applied to the ends of the fluorescent tubes are essentially the same.

22. An inverter circuit comprising:

an inverter transformer having a primary winding and a plurality of secondary windings for increasing a voltage inputted to the primary winding, the apparatus driving a plurality of fluorescent tubes disposed so that the longitudinal directions thereof are substantially parallel to one another,

wherein, when the inverter circuit is used for driving the plurality of fluorescent tubes, the voltage increased by one of the secondary windings is applied to one-end of one fluorescent tube of the plurality of fluorescent tubes, and the voltage increased by the other secondary winding is applied to an end of another fluorescent tube of the plurality of fluorescent tubes that is adjacent to the one-end of the one fluorescent tube, and

wherein the number of windings of an inverter transformer which supplies the voltage to one-end side of the plurality of fluorescent tubes, is the same as the number of windings of an inverter transformer which supplies the voltage to the other-end side of the plurality of fluorescent tubes.