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

• US 7,936,136 B2
• Filed: 10/30/2007
• Issued: 05/03/2011
• 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:
  US11/979,039
• Publication Number:
  US 20080067958A1
• Time in Patent Office: 1,281 Days
• Field of Search: 315/276, 315/277, 315/312, 315/324, 315/278, 315/279, 315/282, 315/DIG.2, 315/DIG.5, 315/185.S, 345/55, 345/84, 345/87, 345/102
• US Class Current: 315/312
• 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 driving apparatus for driving a plurality of fluorescent tubes, comprising:

pairs of inverter circuits, each pair of inverter circuits supplying voltages to ends of a respective one of the fluorescent tubes, each inverter circuit comprising a plurality of transformers that step up an input voltage, wherein the pair of inverter circuits are synchronized via passive connection between one of the transformers of one inverter circuit of the pair of inverter circuits and one of the transformers of the other inverter circuit of the pair of inverter circuits.

2. The driving apparatus according to claim 1, wherein at least one set of transformers in each inverter circuit outputs voltages of opposite phases.

3. The driving apparatus according to claim 1, wherein the primary windings provided in at least one set of transformers in each inverter circuit are connected in parallel.

4. A backlight apparatus, comprising:

a plurality of fluorescent tubes; and

the driving apparatus according to claim 1.

5. A liquid crystal display apparatus, comprising:

a liquid crystal panel; and

the backlight apparatus according to claim 4.

6. A driving apparatus for driving a plurality of fluorescent tubes arranged in parallel in a substantially identical longitudinal direction, comprising:

circuitry that applies voltages of opposite phases to the respective ends of each fluorescent tube, wherein voltages supplied to adjacent ends of at least a pair of adjacent fluorescent tubes are also opposite in phase.

7. The driving apparatus according to claim 6, wherein stepping-up primary windings for two secondary windings that supply voltages to the adjacent ends of the pair of adjacent fluorescent tubes are wound in opposite directions.

8. The driving apparatus according to claim 6, wherein two secondary windings that supply voltages to the adjacent ends of the pair of adjacent fluorescent tubes are wound in opposite directions.

9. The driving apparatus according to claim 6, wherein the voltages applied to the respective ends of each of the plurality of fluorescent tubes are supplied by a pair of transformers, wherein each transformer of the pair of transformers comprises a plurality of secondary windings.

10. A backlight apparatus, comprising:

a plurality of fluorescent tubes; and

the driving apparatus according to claim 6.

11. A liquid crystal display apparatus, comprising:

a liquid crystal panel; and

the backlight apparatus according to claim 10.