CN101146390B - CCFL inverter with single transistor - Google Patents
CCFL inverter with single transistor Download PDFInfo
- Publication number
- CN101146390B CN101146390B CN2007101542479A CN200710154247A CN101146390B CN 101146390 B CN101146390 B CN 101146390B CN 2007101542479 A CN2007101542479 A CN 2007101542479A CN 200710154247 A CN200710154247 A CN 200710154247A CN 101146390 B CN101146390 B CN 101146390B
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- China
- Prior art keywords
- coupled
- switch
- power supply
- supply changeover
- changeover device
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
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- Dc-Dc Converters (AREA)
- Circuit Arrangements For Discharge Lamps (AREA)
- Inverter Devices (AREA)
Abstract
A power supply circuit for transforming a direct-current voltage into an alternating-current voltage for a light source is provided. The power supply circuit includes a drive circuit, a switch, a transformer and a capacitor. The switch has a control terminal coupled to the drive circuit and a ground terminal coupled to a ground. The transformer has a primary side and a secondary side, and a winding on the primary side is coupled between the direct-current voltage and a signal terminal of the switch to generate the alternating-current voltage on the secondary side. The capacitor is coupled between the ground terminal and the signal terminal of the switch.
Description
Technical field
The present invention relates to a kind ofly in order to direct voltage being converted into the power supply changeover device of alternating voltage, and be particularly related to a kind of cold cathode fluorescent lamp pipe (Cold Cathode Fluorescent Lamp, power supply changeover device CCFL).
Background technology
Generally speaking, common LCD has two kinds, and a kind of is reflective, and another kind is a penetration.In the LCD of penetration, need use backlight usually, and generally use cold cathode fluorescent lamp pipe (CCFL) as its backlight, its advantage such as: high-luminous-efficiency, life cycle are long ... Or the like.Yet, because the power supply changeover device of cold cathode fluorescent lamp pipe all comprises two or a plurality of transistor usually, so the problem that its power supply changeover device generally all has complex design and is difficult for making causes and can't reduce manufacturing cost and time effectively.
Therefore, be necessary to propose a kind of easy power supply changeover device, to reduce its manufacturing cost and time.
Summary of the invention
According to one embodiment of the invention, a kind of power supply changeover device is proposed, use for a light emitting source in order to direct voltage is converted into alternating voltage, and comprise one drive circuit, a switch, a transformer and an electric capacity.Switch has in order to being coupled to a control end of drive circuit, and in order to be coupled to an earth terminal of an earthed voltage.Transformer has a primary side and a secondary side, and wherein the coil on the primary side is coupled between the signal end of direct voltage and switch, makes alternating voltage result from secondary side.Electric capacity then is to be coupled between the earth terminal and signal end of switch.
The above embodiments can be known according to the present invention, and the more many known power supply changeover devices of this power supply changeover device are more simple in design, therefore can reduce its manufacturing cost and manufacturing time effectively.And more generally speaking this power supply changeover device can be controlled more simply, uses for cold cathode fluorescent lamp pipe (CCFL).
Description of drawings
For letting above-mentioned and other purposes of the present invention, characteristic, advantage and the embodiment can be more obviously understandable, the detailed description of accompanying drawing be following:
Fig. 1 illustrates a kind of sketch map that is used for the power supply changeover device of cold cathode fluorescent lamp pipe according to the embodiment of the invention.
The sketch map of power supply changeover device operation when Fig. 2 illustrates switch open as shown in Figure 1.
The sketch map of power supply changeover device operation when Fig. 3 illustrates switch as shown in Figure 1 and closes.
Fig. 4 A illustrates the sketch map of the primary side voltage of transformer.
Fig. 4 B illustrates the sketch map of the secondary side voltage of transformer
The main element symbol description:
100: power supply changeover device 106: drive circuit
102: dc voltage output circuit 108: switch
104: cold cathode fluorescent lamp pipe 110: transformer
Embodiment
Please, illustrate a kind of sketch map that is used for the power supply changeover device of cold cathode fluorescent lamp pipe (CCFL) according to the embodiment of the invention with reference to Fig. 1.This power supply changeover device 100 exchanges (AC) voltage in order to being converted into one by the direct voltage that direct current (DC) voltage follower circuit 102 produces, and uses for a cold cathode fluorescent lamp pipe (CCFL) 104.Power supply changeover device 100 comprises one drive circuit 106, a switch 108, a transformer 110, a capacitor C 1 and a decoupling capacitance C2.Switch 108 has a control end that is coupled to drive circuit 106, and an earth terminal that is coupled to an earthed voltage.(Pulse Width Modulation, PWM) signal is with control switch 108 in order to export a pulse width modulation for drive circuit 106.Transformer 110 has a primary side and a secondary side.Wherein, the coil on the primary side is coupled between the signal end of dc voltage output circuit 102 and switch 108, uses at secondary side and produces alternating voltage.Capacitor C 1 is coupled between the earth terminal and signal end of switch 108, and can interact with transformer 110, uses the resonance frequency (Resonant Frequency) of decision power supply changeover device 100, and thereby improves the operating efficiency of power supply changeover device 100.Decoupling capacitance C2 then is an end that is coupled to the secondary side of transformer 110, and output AC voltage cooling cathodouminescence fluorescent tube 104 uses.In addition, the other end of the secondary side of decoupling capacitance C2 and transformer 110 is respectively coupled to cold cathode fluorescent lamp pipe 104.
The sketch map of power supply changeover device operation when Fig. 2 illustrates switch open as shown in Figure 1.Fig. 4 A and 4B illustrate the primary side of transformer and the sketch map of secondary side voltage respectively.Please with reference to Fig. 2, Fig. 4 A and Fig. 4 B; When switch 108 (transistor M1) reception is opened by the signal of drive circuit 106 outputs; The voltage of being exported by dc voltage output circuit 102 can make the primary side of transformer 110 produce a positive voltage VAB; Therefore electric current 11 can flow to switch 108 from dc voltage output circuit 102 via transformer 110; And electric current I 2 also can produce at the secondary side of transformer 110, and the decoupling capacitance C2 that flows through, and this moment, the voltage VCD of cooling cathodouminescence fluorescent tube 104 uses also can produce by this.In addition, electric current can be flow to capacitor C 1 by the primary side of transformer 110, and therefore capacitor C 1 can charge and make its voltage increase in time.
The sketch map of power supply changeover device operation when Fig. 3 illustrates switch as shown in Figure 1 and closes.Please with reference to Fig. 3, Fig. 4 A and Fig. 4 B, when switch 108 (transistor M1) reception was closed by the signal of drive circuit 106 outputs, capacitor C 1 can be discharged, and the primary side of transformer 110 can produce a negative voltage VAB.Electric current I 1 can be flow to the primary side of transformer 110 by capacitor C 1 at this moment, and electric current I 2 also can produce at the secondary side of transformer 110, and the voltage VCD that cooling cathodouminescence fluorescent tube 104 uses also can produce by this.Therefore, the polarity of voltage of transformer 110 just can replace conversion by this, and the size of the electric current I 1 of the primary side of the transformer 110 of flowing through and secondary side and I2 and direction also can along with the time intercropping change.
Embodiment by the invention described above can know that the more many known power supply changeover devices of this power supply changeover device have less transistor, and simpler in design, so can reduce manufacturing cost and time.In addition, this power supply changeover device can only be controlled by a switch, to convert direct voltage into alternating voltage, therefore more generally speaking can control more simply, and cooling cathodouminescence fluorescent tube (CCFL) uses more easily.
Though the present invention discloses as above with embodiment; Right its is not in order to limit the present invention; Those of ordinary skill under any in the technical field; Do not breaking away from the spirit and scope of the present invention, when can doing various changes and retouching, so protection scope of the present invention is as the criterion when looking the accompanying Claim book person of defining.
Claims (7)
1. a power supply changeover device uses for a light emitting source in order to direct voltage is converted into alternating voltage, and this power supply changeover device comprises:
One drive circuit;
One switch has a control end that is coupled to this drive circuit, and an earth terminal that is coupled to an earthed voltage;
One transformer has a primary side and a secondary side, and wherein the coil on this primary side is coupled between the signal end of this direct voltage and this switch, makes this alternating voltage result from this secondary side;
One electric capacity is coupled between this earth terminal and this signal end of this switch; And
One uncoupling assembly is coupled to one first end of this secondary side of this transformer, and exports this alternating voltage, and wherein one second end of this secondary side of this uncoupling assembly and this transformer is respectively coupled to this light emitting source.
2. power supply changeover device as claimed in claim 1 is characterized in that, this switch more comprises:
One diode is coupled between this earth terminal and this signal end of this switch.
3. power supply changeover device as claimed in claim 2 is characterized in that, this diode is the body diode in this switch.
4. power supply changeover device as claimed in claim 1 is characterized in that, this drive circuit is exported a pulse width modulating signal to control this switch.
5. power supply changeover device as claimed in claim 1 is characterized in that, this switch comprises a metal oxide-semiconductor field-effect transistor.
6. power supply changeover device as claimed in claim 5, wherein this metal oxide-semiconductor field-effect transistor is a N type metal oxide-semiconductor field-effect transistor.
7. power supply changeover device as claimed in claim 6, wherein this metal oxide-semiconductor field-effect transistor comprises:
One grid is coupled to this drive circuit;
One first source-drain electrode is coupled to one first end of this primary side of this transformer; And
One second source-drain electrode is coupled to this earth terminal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US82544706P | 2006-09-13 | 2006-09-13 | |
| US60/825,447 | 2006-09-13 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101146390A CN101146390A (en) | 2008-03-19 |
| CN101146390B true CN101146390B (en) | 2012-02-15 |
Family
ID=39208612
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2007101542479A Expired - Fee Related CN101146390B (en) | 2006-09-13 | 2007-09-11 | CCFL inverter with single transistor |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN101146390B (en) |
| TW (1) | TW200814855A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1290991A (en) * | 1999-09-30 | 2001-04-11 | 索尼公司 | Switch power circuit and isolated variable transformer |
| CN1298223A (en) * | 1999-10-29 | 2001-06-06 | 索尼公司 | Secondary lateral parallel and series resonance power circuit for switch |
-
2007
- 2007-09-05 TW TW096133120A patent/TW200814855A/en unknown
- 2007-09-11 CN CN2007101542479A patent/CN101146390B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1290991A (en) * | 1999-09-30 | 2001-04-11 | 索尼公司 | Switch power circuit and isolated variable transformer |
| CN1298223A (en) * | 1999-10-29 | 2001-06-06 | 索尼公司 | Secondary lateral parallel and series resonance power circuit for switch |
Also Published As
| Publication number | Publication date |
|---|---|
| TW200814855A (en) | 2008-03-16 |
| CN101146390A (en) | 2008-03-19 |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120215 Termination date: 20190911 |
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| CF01 | Termination of patent right due to non-payment of annual fee |