CN1980507B - Starting circuit and back-light starting circuit - Google Patents
Starting circuit and back-light starting circuit Download PDFInfo
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- CN1980507B CN1980507B CN200510102305A CN200510102305A CN1980507B CN 1980507 B CN1980507 B CN 1980507B CN 200510102305 A CN200510102305 A CN 200510102305A CN 200510102305 A CN200510102305 A CN 200510102305A CN 1980507 B CN1980507 B CN 1980507B
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- circuit
- charging
- charging capacitor
- pulse
- width modulation
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Abstract
This start circuit consists of the 1st and the 2nd charging capacitors (CC), a current limited resistor (CLR) and a charging end (CE). One end of the 1st CC connects to ground and the other end to CE. CE also connects sequentially to CLR in series, to the 2nd CC and finally to ground. This start circuit solves the problem of starting too fast in existed start circuits.
Description
[technical field]
The present invention relates to a kind of start-up circuit, particularly a kind of back-light starting circuit that is used for liquid crystal indicator.
[background technology]
Characteristics such as LCD has frivolous, and low power consumption and radiation are few are widely used in electronic equipments such as monitor, LCD TV, mobile phone and notebook computer.Because the liquid crystal molecule itself in the LCD is not luminous, so LCD needs to show by the luminous image of realizing of a module backlight.Usually adopt cold cathode ray tube or light-emitting diode in the module backlight as its luminous light source.When adopting cold cathode ray tube as light source, because therefore needed driving voltage frequency when required driving voltage frequency was higher than operate as normal when cold cathode ray tube was lighted comprises that a back-light starting circuit provides the driving voltage of a upper frequency when being used to cold cathode ray tube to light in the drive circuit of module backlight.
Seeing also Fig. 1, is the schematic diagram of the disclosed a kind of back-light starting circuit of prior art.This back-light starting circuit 100 comprises a pulse-width modulation integrated circuit 120, a start-up circuit 130, a negative circuit 140 and a backlight 150.This pulse-width modulation integrated circuit 120 comprises that a start detection end 121 is used to control the startup of this pulse-width modulation integrated circuit 120.This start-up circuit 130 comprises a charging capacitor 131, and the start detection end 121 of this pulse-width modulation integrated circuit 120 is by these charging capacitor 131 ground connection.Produce some lamp voltage signal during these pulse-width modulation integrated circuit 120 normal startups, this lamp voltage signal drives this backlight 150 by this negative circuit 140.Wherein, the model of this pulse-width modulation integrated circuit 120 is OZ9901.This start detection end 121 is inputs of this pulse-width modulation integrated circuit 120.This backlight 150 be cold cathode ray tube (cold cathode fluorescent lamp, CCFL).The size of this charging capacitor is 0.1 μ F.
This back-light starting circuit 100 is used for the unlatching of this backlight liquid crystal display of LCD control.When pressing the mains switch of this LCD, the internal circuit of this pulse-width modulation integrated circuit 120 charges by 121 pairs of these start-up circuits 130 of this start detection end.After the voltage of this start detection end 121 surpassed a threshold voltage, this pulse-width modulation integrated circuit 120 normally started and produces some lamp voltage signal, and this lamp voltage signal drives this backlight 150, backlight lightening by this negative circuit 140.
But, this start-up circuit 130 only is made up of a charging capacitor, therefore the internal circuit of this width modulation integrated circuit 120 causes this pulse-width modulation integrated circuit 120 to start also too fast by the excessive velocities that 121 pairs of these start-up circuits 130 of this start detection end charge.So the duration of the some lamp voltage signal that this pulse-width modulation integrated circuit 120 produces when starting is also shorter, the waveform voltage signal figure that lights a lamp that this pulse-width modulation integrated circuit 120 produces can consult Fig. 2.Because of the duration of this lamp voltage signal shorter, when backlight 150 quantity can produce the problem that backlight can not normally start more for a long time, be embodied in that fluorescent tube is glittering just have been extinguished after once.
[summary of the invention]
Start too fast problem in order to solve start-up circuit of the prior art, be necessary to provide a kind of startup start-up circuit more stably.
Start too fast problem in order to solve back-light starting circuit of the prior art, be necessary to provide a kind of startup back-light starting circuit more stably.
A kind of start-up circuit, it comprises one first charging capacitor, one second charging capacitor, a current-limiting resistance and a charging end.One end ground connection of this first charging capacitor, the other end of this first charging capacitor is electrically connected to this charging end, this charging end is used to be connected to the start detection end of a pulse-width modulation integrated circuit, this start detection end is used to control the startup of this pulse-width modulation integrated circuit, after external circuit provides power supply for this pulse-width modulation integrated circuit, this pulse-width modulation integrated circuit charges to the charging end of this start-up circuit by this start detection end, when the voltage of this start detection end surpassed a threshold values, this pulse-width modulation integrated circuit normally started and produces some lamp voltage signal.This charging end is also by this current-limiting resistance and this second charging capacitor ground connection connected successively.
A kind of back-light starting circuit, it comprises a backlight, a negative circuit, a start-up circuit and a pulse-width modulation integrated circuit.This start-up circuit comprises one first charging capacitor, one second charging capacitor, a current-limiting resistance and a charging end.This pulse-width modulation integrated circuit comprises that one is used to control the start detection end that this pulse-width modulation integrated circuit starts.One end ground connection of this first charging capacitor, the other end of this first charging capacitor is electrically connected to this charging end, and this charging end is also by this current-limiting resistance and this second charging capacitor ground connection connected successively.This start detection end also is connected to the charging end of this start-up circuit.After external circuit provides power supply for this pulse-width modulation integrated circuit, this pulse-width modulation integrated circuit charges to the charging end of this start-up circuit by this start detection end, when the voltage of this start detection end surpassed a threshold values, this pulse-width modulation integrated circuit normally started and produces some lamp voltage signal.
Compared to prior art, increase by one second charging capacitor and a current-limiting resistance in the above-mentioned start-up circuit.This current-limiting resistance can limit the charging current to second charging capacitor, so the charge waveforms of the charging end of this start-up circuit is more steady.This back-light starting circuit comprises this start-up circuit, so this back-light starting circuit starts also more steady.
[description of drawings]
Fig. 1 is the schematic diagram of the disclosed a kind of back-light starting circuit of prior art.
Fig. 2 is the waveform voltage signal figure that lights a lamp that this pulse-width modulation integrated circuit produces among Fig. 1.
Fig. 3 is the schematic diagram of back-light starting circuit first execution mode of the present invention.
Fig. 4 is the waveform voltage signal figure that lights a lamp that this pulse-width modulation integrated circuit produces among Fig. 3.
Fig. 5 is the schematic diagram of back-light starting circuit second execution mode of the present invention.
[embodiment]
Seeing also Fig. 3, is the schematic diagram of back-light starting circuit first execution mode of the present invention.This back-light starting circuit 300 comprises a pulse-width modulation integrated circuit 320, a start-up circuit 330, a negative circuit 340 and a backlight 350.This pulse-width modulation integrated circuit 320 comprises that a start detection end 321 is used to control the startup of this pulse-width modulation integrated circuit 320.
This start-up circuit 330 comprises one first charging capacitor 331, one second charging capacitor 332 and a current-limiting resistance 333.One end ground connection of this first charging capacitor 331, the other end of this first charging capacitor 331 is as the charging end of this start-up circuit 330.This charging end is also by these current-limiting resistance 333 and these second charging capacitor, 332 ground connection connected successively.The capacitance of this first charging capacitor 331 is 0.068 μ F.The capacitance of this second charging capacitor 332 is 0.33 μ F.The resistance value of this current-limiting resistance 333 is 500 Ω.
The start detection end 321 of this pulse-width modulation integrated circuit 320 is connected to the charging end of this start-up circuit 330.Produce some lamp voltage signal during these pulse-width modulation integrated circuit 320 normal startups, this lamp voltage signal drives this backlight 350 by this negative circuit 340.Wherein, the model of this pulse-width modulation integrated circuit 320 is OZ9901.This start detection end 321 is inputs of this pulse-width modulation integrated circuit 320.This backlight 350 is cold cathode ray tubes.
This back-light starting circuit 300 is used for the unlatching of this backlight liquid crystal display of LCD control.When pressing the mains switch of this LCD, after an external circuit provided power supply for this pulse-width modulation integrated circuit 320, the internal circuit of this pulse-width modulation integrated circuit 320 charged by 321 pairs of these start-up circuits 330 of this start detection end.T1 is in the time period, and this charging end arrives one first scheduled voltage V1 with first charging rate.T2 is in the time period, and this charging end arrives one second scheduled voltage V2 with second charging rate.This V1 is determined by this current-limiting resistance 333, this second charging capacitor 332 and T1 time period length.This V2 is determined by this current-limiting resistance 333, this second charging capacitor 332 and T2 time period length.After the voltage of this start detection end 321 surpassed a threshold voltage, this pulse-width modulation integrated circuit 320 normally started and produces some lamp voltage signal, and this lamp voltage signal drives this backlight 350, backlight lightening by this negative circuit 340.
Compared to prior art, this start-up circuit 330 increases by one second charging capacitor 332 and a current-limiting resistance 333.This current-limiting resistance 333 can limit the charging current to second charging capacitor 332, prolong this charging end and reach the required time span of V2 voltage, so the charge waveforms of the charging end of this start-up circuit 330 is more steady.This back-light starting circuit 300 comprises this start-up circuit 330, so the some lamp voltage signal that this back-light starting circuit 300 produces when starting is also more steady.The point lamp voltage signal that this back-light starting circuit 300 produces when starting can be consulted Fig. 4.
But if in this back-light starting circuit 300, when these first charging capacitor, 331 capacity of this start-up circuit 330 were excessive, the electric charge of accumulation can't bleed off at short notice on this first charging capacitor 331.This stored charge can cause this pulse-width modulation integrated circuit 320 repeated primings even damage.
Seeing also Fig. 5, is the schematic diagram of back-light starting circuit second execution mode of the present invention.This back-light starting circuit 500 comprises a pulse-width modulation integrated circuit 520, a start-up circuit 530, a negative circuit 540 and a backlight 550.This pulse-width modulation integrated circuit 520 comprises that a start detection end 521 is used to control the startup of this pulse-width modulation integrated circuit 520.
This start-up circuit 530 comprises one first charging capacitor 531, one second charging capacitor 532, a current-limiting resistance 533 and a discharge resistance 534.This first charging capacitor 531 is in parallel with this discharge resistance 534, and the end ground connection after the parallel connection, and the other end is as the charging end of this start-up circuit 530.This charging end is also by these current-limiting resistance 533 and these second charging capacitor, 532 ground connection connected successively.The capacitance of this first charging capacitor 531 is 0.068 μ F.The capacitance of this second charging capacitor 532 is 0.33 μ F.The resistance value of this current-limiting resistance 533 is 500 Ω.The resistance value of this discharge resistance 534 is 1M Ω.
The start detection end 521 of this pulse-width modulation integrated circuit 520 is connected to the charging end of this start-up circuit 530.Produce some lamp voltage signal during these pulse-width modulation integrated circuit 520 normal startups, this lamp voltage signal drives this backlight 550 by this negative circuit 540.Wherein, these pulse-width modulation integrated circuit 520 models are OZ9901.This start detection end 521 is inputs of this pulse-width modulation integrated circuit 520.This backlight 550 is cold cathode ray tubes.
In this back-light starting circuit 500, this start-up circuit 530 comprises that further a discharge resistance 534 is connected in parallel with this first charging capacitor 531.This discharge resistance 534 can guarantee that this back-light starting circuit 500 bleeds off the electric charge of accumulation on this first charging capacitor 531 when quitting work, and makes this start detection end 521 of this pulse-width modulation integrated circuit 520 be low-voltage.
In addition, for the toggle speed of accelerating this back-light starting circuit 500 or further improve its driving force, one first charging capacitor, 531, one second charging capacitors 532, a current-limiting resistance 533 and a discharge resistance 534 in this start-up circuit also can be done further adjustment.Through experimental verification, the best adjusting range of this first charging capacitor 531 is (0.01 μ F～0.1 μ F).The best adjusting range of this second charging capacitor 532 is (0.1 μ F～1 μ F).The best adjusting range of this current-limiting resistance 533 is (200 Ω～1K Ω).The best adjusting range of this discharge resistance 534 is (1M Ω～2M Ω).
When the size of these one first charging capacitor, 531, one second charging capacitors 532, a current-limiting resistance 533 and a discharge resistance 534 was respectively 0.01 μ F, 0.1 μ F, 200 Ω and 1M Ω, this back-light starting circuit 500 had very fast toggle speed.
When the size of these one first charging capacitor, 531, one second charging capacitors 532, a current-limiting resistance 533 and a discharge resistance 534 was respectively 0.1 μ F, 1 μ F, 1K Ω and 2M Ω, this back-light starting circuit 500 had strong driving force.
Claims (10)
1. start-up circuit comprises:
One first charging capacitor and a charging end, one end ground connection of this first charging capacitor, the other end of this first charging capacitor is electrically connected to this charging end, this charging end is used to be connected to the start detection end of a pulse-width modulation integrated circuit, this start detection end is used to control the startup of this pulse-width modulation integrated circuit, after external circuit provides power supply for this pulse-width modulation integrated circuit, this pulse-width modulation integrated circuit charges to the charging end of this start-up circuit by this start detection end, when the voltage of this start detection end surpassed a threshold values, this pulse-width modulation integrated circuit normally started and produces some lamp voltage signal;
It is characterized in that: this start-up circuit further comprises one second charging capacitor and a current-limiting resistance, and this charging end is also by this current-limiting resistance and this second charging capacitor ground connection connected successively.
2. start-up circuit as claimed in claim 1 is characterized in that: this start-up circuit further comprises a discharge resistance, this discharge resistance and this first charging capacitor parallel connection.
3. start-up circuit as claimed in claim 1 or 2 is characterized in that: this start-up circuit further comprises a power supply, and this power supply is electrically connected to this charging end.
4. a back-light starting circuit comprises:
One start-up circuit, it comprises one first charging capacitor, one second charging capacitor, a current-limiting resistance and a charging end, one end ground connection of this first charging capacitor, this charging end that the other end of this first charging capacitor is electrically connected to, this charging end are also by this current-limiting resistance and this second charging capacitor ground connection connected successively; With
One pulse-width modulation integrated circuit, it comprises that one is used to control the start detection end that this pulse-width modulation integrated circuit starts, this start detection end is connected to the charging end of this start-up circuit, after external circuit provides power supply for this pulse-width modulation integrated circuit, this pulse-width modulation integrated circuit charges to the charging end of this start-up circuit by this start detection end, when the voltage of this start detection end surpassed a threshold values, this pulse-width modulation integrated circuit normally started and produces some lamp voltage signal.
5. back-light starting circuit as claimed in claim 4 is characterized in that: this back-light starting circuit further comprises a discharge resistance, this discharge resistance and this first charging capacitor parallel connection.
6. back-light starting circuit as claimed in claim 5 is characterized in that: the size of this first charging capacitor, this second charging capacitor, this current-limiting resistance and this discharge resistance is respectively 0.01 μ F, 0.1 μ F, 200 Ω and 1M Ω.
7. back-light starting circuit as claimed in claim 5 is characterized in that: the size of this first charging capacitor, this second charging capacitor, this current-limiting resistance and this discharge resistance is respectively 0.068 μ F, 0.33 μ F, 500 Ω and 1M Ω.
8. back-light starting circuit as claimed in claim 5 is characterized in that: this first charging capacitor, the size of this second charging capacitor, this current-limiting resistance and this discharge resistance is respectively 0.1 μ F, 1 μ F, 1K Ω and 2M Ω.
9. back-light starting circuit as claimed in claim 5 is characterized in that: this back-light starting circuit further comprises a backlight and a negative circuit, and this lamp voltage signal drives this backlight by this negative circuit.
10. back-light starting circuit as claimed in claim 9 is characterized in that: this backlight is a cold cathode ray tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200510102305A CN1980507B (en) | 2005-12-07 | 2005-12-07 | Starting circuit and back-light starting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200510102305A CN1980507B (en) | 2005-12-07 | 2005-12-07 | Starting circuit and back-light starting circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1980507A CN1980507A (en) | 2007-06-13 |
| CN1980507B true CN1980507B (en) | 2010-05-26 |
Family
ID=38131450
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200510102305A Expired - Fee Related CN1980507B (en) | 2005-12-07 | 2005-12-07 | Starting circuit and back-light starting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1980507B (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5350997A (en) * | 1992-12-16 | 1994-09-27 | International Business Machines Corporation | Step-up voltage converter with overcurrent protection |
| US6185082B1 (en) * | 1999-06-01 | 2001-02-06 | System General Corporation | Protection circuit for a boost power converter |
| CN1622438A (en) * | 2003-11-25 | 2005-06-01 | 夏普株式会社 | Power supply circuit |
-
2005
- 2005-12-07 CN CN200510102305A patent/CN1980507B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5350997A (en) * | 1992-12-16 | 1994-09-27 | International Business Machines Corporation | Step-up voltage converter with overcurrent protection |
| US6185082B1 (en) * | 1999-06-01 | 2001-02-06 | System General Corporation | Protection circuit for a boost power converter |
| CN1622438A (en) * | 2003-11-25 | 2005-06-01 | 夏普株式会社 | Power supply circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1980507A (en) | 2007-06-13 |
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Granted publication date: 20100526 Termination date: 20161207 |
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| CF01 | Termination of patent right due to non-payment of annual fee |