CN1543288A - current control device and method - Google Patents
current control device and method Download PDFInfo
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- CN1543288A CN1543288A CNA031250149A CN03125014A CN1543288A CN 1543288 A CN1543288 A CN 1543288A CN A031250149 A CNA031250149 A CN A031250149A CN 03125014 A CN03125014 A CN 03125014A CN 1543288 A CN1543288 A CN 1543288A
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- 238000012544 monitoring process Methods 0.000 claims abstract description 5
- 239000003990 capacitor Substances 0.000 claims 1
- 239000004973 liquid crystal related substance Substances 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 2
- 238000005286 illumination Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
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Abstract
The present invention is directed to a current control apparatus and method thereof, which mainly solves the problem that when the number of lamps in a backlight device of a liquid crystal display is multiple, the currents flowing through the lamps are not balanced, and the lamps are not equal in brightness. The current control device comprises a feedback device, a first switch, a second switch, a main control device, a resonance device, a transformer and a low-frequency switch control device. The low-frequency switch control device controls the plurality of lamp tubes to be lighted in a staggered mode, the feedback device is used for monitoring the current flowing through the plurality of lamp tubes respectively, and therefore the current flowing through the plurality of lamp tubes is balanced, and the plurality of lamp tubes are lighted.
Description
Technical field
The invention relates to a kind of current control device and method thereof, particularly about providing a kind of current control device and method thereof to solve when display backlight fluorescent tube number when being a plurality of the unbalanced problem of a plurality of lamp tube current of flowing through.
Background technology
Display is institute's role in computer, it is the output device of a performance picture and literal signal, traditional display mode such as cathode-ray tube display (CRT) and LED display panel or the like all are limited by factors such as the excessive or power consumption of volume is very huge, can't reach user's actual demand.And the image energy of LCD (LCD) has preferable contrast and reduces the state that blurs when picture moves, it no matter is little, the advantage such as the low radiation of tool also of right angle demonstration, low power consumption, volume, can both allow the user enjoy best visual environment, the development of LCD technology just in time suits user's demand.Demand along with the user, the size of liquid crystal display increases day by day, and its required backlight illumination also increases relatively, has saturated phenomenon but produce cold-cathode tube (CCFL) backlight in the LCD, can't increase brightness to increase electric current, the most direct method increases fluorescent tube quantity exactly always.
Fig. 1 is the line block diagram that expression one has two fluorescent tubes, to contain two tubes in the display backlight device is example, by electric current I 14 and the I14b of a feedback device 17 monitoring flow through the first fluorescent tube 14a and the second fluorescent tube 14b, and export a feedback signal S1 to main control unit 10, and supply city's voltage and give main control unit 10.Main control unit 10 is exported one first voltage to one resonant circuit 11 according to feedback signal S1, resonant circuit 11 outputs one voltage control signal, and transformer 12 improves the amplitude of voltage control signal to drive the first fluorescent tube 14a and the second fluorescent tube 14b, and then produce the electric current I 14a and the I14b of the flow through first fluorescent tube 14a and the second fluorescent tube 14b and balance, make the first fluorescent tube 514a and the second fluorescent tube 14b brightness identical.But in fact because the tube impedance characteristic difference of the first fluorescent tube 14a and the second fluorescent tube 14b, and the equiva lent impedance error in order to the first high-voltage capacitance 13a of isolated DC voltage and the second high-voltage capacitance 13b is big, cause the electric current I 14b imbalance of the electric current I 14a and the second fluorescent tube 14b of the first fluorescent tube 14a that flows through, produce fluorescent tube and do not wait bright problem, and make the brightness irregularities of display picture, problems such as lamp tube service life attenuating.
Fig. 2 is that expression one solves the line block diagram that electric current distributes unbalanced conventional art.In conventional art, be to solve the problem of current imbalance, with the electric current I 24b of the electric current I 24a of the first fluorescent tube 24a that flows through and the second fluorescent tube 24b that flows through respectively by feedback device 27a and feedback device 27b feedback.Accept feedback signal Sa2 and Sb2 by main control unit 20a and main control unit 20b, to control the flow through current value of electric current I 24b of the electric current I 24a of the first fluorescent tube 24a and the second fluorescent tube 24b of two fluorescent tubes respectively.But because two loop component erroi differences, and feedback point difference, conventional art cause the electric current of the flow through first fluorescent tube 24a and the second fluorescent tube 24b to have uneven slightly and to cause fluorescent tube not wait bright, so also can't solve the problem of the current imbalance of the flow through first fluorescent tube 24a and the second fluorescent tube 24b fully.It is more that the disadvantage of this conventional art is to use number of spare parts in addition, so cost is higher, and error amount also improves relatively.
Summary of the invention
In view of this, main purpose of the present invention is for a kind of current control device is provided, and it is mainly solving when display backlight device fluorescent tube number when being a plurality of, the unbalanced problem of a plurality of lamp tube current of flowing through, but and simplification device with the minimizing error that reduces cost.
In addition, another object of the present invention is, control a plurality of fluorescent tubes with a low frequency switch controlling device and make its staggered lighting, by a feedback device respectively monitoring flow and then make a plurality of lamp tube current of flowing through reach balance through a plurality of lamp tube current, and a plurality of fluorescent tubes etc. are bright.
For achieving the above object, the present invention proposes a kind of current control device, be arranged in the display, be provided with first fluorescent tube and second fluorescent tube in this display, this current control device is to be used for first electric current and second electric current of equiulbrium flow through this first fluorescent tube and this second fluorescent tube, and its current control device comprises feedback device, first switch, second switch, main control unit, resonance device, transformer and low frequency switch controlling device at least.
At first, apparatus of the present invention are utilized this first electric current and this second electric current of feedback device monitoring flow through first fluorescent tube and second fluorescent tube, and output feedback signal.Main control unit is exported first voltage according to feedback signal, and resonance device produces voltage control signal according to first voltage.Then, transformer is exported second voltage according to voltage control signal, and it is in order to offering first fluorescent tube and second fluorescent tube, and produces first electric current and second electric current.First switch and second switch see through the low frequency switch controlling device in different time conducting respectively, when first switch conduction, feedback device receives first electric current, if first electric current is not inconsistent the set current value of unification, then this main control unit changes first voltage according to feedback signal, and then changes first electric current.
In addition, the present invention more proposes a kind of current control method, is applicable to first fluorescent tube of equiulbrium flow in display and first electric current and second electric current of second fluorescent tube, and this first fluorescent tube and second fluorescent tube are by one first switch and a second switch conducting and open.This method at first applies driving voltage to the first fluorescent tube and second fluorescent tube, and with the opposite pulse signal of two phase place conducting first switch and second switch respectively, makes to light first fluorescent tube and second fluorescent tube respectively and produce first electric current separately and second electric current.Then, monitor first electric current and second electric current respectively,, then change above-mentioned driving voltage, so that change the above-mentioned set current value of the first electric current convergence when first electric current is not inconsistent the set current value of unification.
Description of drawings
Fig. 1 represents that one has the line block diagram of two fluorescent tubes.
Fig. 2 represents that one solves the line block diagram that electric current distributes unbalanced conventional art.
Fig. 3 represents the embodiments of the invention line block diagram.
Fig. 4 represents the sequential chart of lamp tube starting among the present invention.
Fig. 5 represents the sequential chart of lamp tube starting time control among the present invention.
Fig. 6 represents among the present invention tube impedance not simultaneously, and the magnitude of voltage of step-up side changes sequential chart.
Fig. 7 represents the sequential chart of feedback stability among the present invention.
Symbol description
10,20a, 20b, 30～main control unit;
11,21a, 21b, 31～resonance device;
12,22a, 22b, 32～transformer;
13a, 13b, 23a, 23b, 33～high-voltage capacitance;
14a, 14b, 24a, 24b, 34a, 34b～fluorescent tube;
17,27a, 27b, 37～feedback device;
35a, 35b～switch;
36～low frequency switch controlling device;
38～node;
I14a, I14b, I24a, I24b, I34a, I34b～electric current.
Embodiment
For above and other objects of the present invention, feature and advantage can be become apparent, cited below particularlyly go out preferred embodiment, and conjunction with figs., be described in detail below:
Embodiments of the invention are example with two fluorescent tubes, and Fig. 3 is expression embodiments of the invention line block diagrams.In the embodiment of current control device of the present invention, a line voltage is supplied to main control unit 30.Main control unit 30 changes first voltage of its output according to a feedback signal S3 who receives, and resonance device 31 produces a voltage control signal according to first voltage.Transformer 32 is serially connected between fluorescent tube 34a, 34b and the resonance device 31, in order to improve the amplitude of above-mentioned voltage control signal.Transformer 32 is to produce one to provide an enough voltage to fluorescent tube 34a and fluorescent tube 34b.Because fluorescent tube 34a and fluorescent tube 34b are driven by alternating voltage to light, thus between transformer and fluorescent tube 34a and fluorescent tube 34b, couple a high-voltage capacitance 33, with isolated direct voltage.Switch 35a and switch 35b are respectively coupled to fluorescent tube 34a and fluorescent tube 34b, produce the opposite pulse signal of two phase place with difference actuating switch 35a and switch 35b by a low frequency switch controlling device 36, and fluorescent tube 34a and fluorescent tube 34b are lighted in different time.When switch 35a conducting, light fluorescent tube 34a, the electric current I 34a fluorescent tube 34a that flows through, otherwise, when switch 35b conducting, light fluorescent tube 34b, the electric current I 34b fluorescent tube 34b that flows through.When fluorescent tube 34a and fluorescent tube 34b light, be serially connected with the feedback device 37 monitor current I34a and the I34b of the common node 38 of switch 35a and switch 35b.When switch 35a conducting, feedback device 37 receives above-mentioned electric current I 34a, if electric current I 34a is not inconsistent the set current value of unification, then feedback device 37 is exported above-mentioned feedback signal S3, and changes above-mentioned first voltage by main control unit 30, and then changes electric current I 34a.Otherwise, when switch 35b conducting, feedback device 37 received current I34b, if the I34B electric current does not meet above-mentioned set current value, then feedback device 37 is exported above-mentioned feedback signal S3, and changes above-mentioned first voltage by main control unit 30, and then changes electric current I 34b.So via feedback device 37 monitor current I34a and I34b, so that electric current I 34a and the I34b balance of flow through fluorescent tube 34a and fluorescent tube 34b, and make fluorescent tube 34a and fluorescent tube 34b etc. bright.
Above-mentioned low frequency switch controlling device 36 provides two phase place opposite pulse signal, and actuating switch 35a and switch 35b light fluorescent tube 34a and fluorescent tube 34b respectively respectively.Fig. 4 is the sequential chart of lamp tube starting, and preferable enforcement frequency is between the 200Hz to 500Hz, and wherein label SW1 and SW2 represent the opposite pulse signal of two phase place respectively, and high level represents with H, and low level represents with L.Label ACa and ACb are respectively the voltage that puts on fluorescent tube 34a and fluorescent tube 34b.When pulse signal SW1 is high level H, switch 35a conducting, a voltage ACa puts on fluorescent tube 34a producing an electric current I 34a, and electric current I 34a, and flow through fluorescent tube 34a and light fluorescent tube 34a, when pulse signal SW1 is low level H, not conducting of switch 35a.In like manner, when pulse signal SW2 is high level L, switch 35b conducting, a voltage ACb puts on fluorescent tube 34b to produce an electric current I 34b, and electric current I 34b flows through fluorescent tube 34b and lights fluorescent tube 34b, when pulse signal SW2 is low level L, not conducting of switch 35b.
Among the present invention the time of lamp tube starting can be by the two phase place that low frequency switch controlling device 36 produces the work ratio (DUTY) of opposite pulse signal control; Fig. 5 is the sequential chart of lamp tube starting time control among expression the present invention.When number in the figure AC1 is fluorescent tube 34a and the conducting of fluorescent tube 34b difference, put on the merging of two light tube electric voltage signals, the pulse signal that the two phase place that label SWn representative is produced by low audio-frequency control device is opposite merges, and a waveform represents that with solid line another waveform is represented by dotted lines.The time that time t51, t53 and t55 light for fluorescent tube 34a, the time that time t52 and t54 light for fluorescent tube 34b; The time of lamp tube starting can be controlled by the work ratio (DUTY) of the merging of switching signal.
In the embodiment of the invention, by feedback device 37 monitor current I34a and I34 and change above-mentioned first voltage.As shown in Figure 6, AC2 represents above-mentioned first voltage, and t61, t63 and t65 are the bigger lamp tube starting time of impedance, and t62 and t64 are the less lamp tube starting time of impedance.By among the figure as can be known, when the bigger lamp tube starting of impedance, the voltage amplitude of AC2 is bigger, on the contrary when the less lamp tube starting of impedance, the voltage amplitude of AC2 is less; So just can make two different lamp tube current balances of the impedance of flowing through, and then make two fluorescent tubes etc. bright.
Fig. 7 is the sequential chart of feedback stability among expression the present invention, is the voltage signal that the first fluorescent tube 34a puts on the first fluorescent tube 34a when lighting and closing among the figure.Put on the voltage signal of the second fluorescent tube 34b when similarly, this sequential figure representation second fluorescent tube 34b lights and closes.The opposite pulse signal of two phase place that produces by low audio-frequency control device 36 among the present invention, its frequency can be between 200Hz to 500Hz, and promptly the cycle is between 5000 to 2000 microseconds.Hence one can see that, and (t71～t72) is between 5000 to 2000 microseconds to T1 cycle time of the first fluorescent tube 34a and the second fluorescent tube 34b switch.(only about 10 microseconds of t72～t73) are so reach stable after having time enough by the loop switching for feedback stability time T 2 after medium and low frequency switch controlling device 36 phase places of the present invention are switched and switched.
In sum, the present invention have following some be better than conventional art shown in Figure 2:
One, simplification device of the present invention becomes single circuit controls, reduces the part number and then reduces cost and lower part error.
Two, device of the present invention is single circuit controls, and two fluorescent tube feedback points are identical, and via the same circuit control flows through lamp tube current, easily make two lamp tube current of flowing through level off to balance, and then make fluorescent tube etc. bright.
Though the present invention discloses as above with a preferred embodiment; right its is not in order to qualification the present invention, any insider, without departing from the spirit and scope of the present invention; but when this change and retouching, so protection scope of the present invention is as the criterion when looking the accompanying Claim book person of defining.
Claims (8)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA031250149A CN1543288A (en) | 2003-04-29 | 2003-04-29 | current control device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA031250149A CN1543288A (en) | 2003-04-29 | 2003-04-29 | current control device and method |
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| CN1543288A true CN1543288A (en) | 2004-11-03 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100414383C (en) * | 2005-08-16 | 2008-08-27 | 明基电通股份有限公司 | Multi-lamp tube lighting device |
| CN1770946B (en) * | 2004-11-05 | 2010-05-05 | 太阳诱电株式会社 | lighting device |
| CN101533607B (en) * | 2008-03-14 | 2011-03-30 | 原景科技股份有限公司 | Driving circuit of light emitting diode and driving method of light emitting diode |
| CN101206342B (en) * | 2006-12-22 | 2011-04-27 | 奇美电子股份有限公司 | Light tube drive circuit, backlight module group and LCD |
| US8164587B2 (en) | 2007-05-30 | 2012-04-24 | Himax Technologies Limited | LCD power supply |
-
2003
- 2003-04-29 CN CNA031250149A patent/CN1543288A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1770946B (en) * | 2004-11-05 | 2010-05-05 | 太阳诱电株式会社 | lighting device |
| CN100414383C (en) * | 2005-08-16 | 2008-08-27 | 明基电通股份有限公司 | Multi-lamp tube lighting device |
| CN101206342B (en) * | 2006-12-22 | 2011-04-27 | 奇美电子股份有限公司 | Light tube drive circuit, backlight module group and LCD |
| US8164587B2 (en) | 2007-05-30 | 2012-04-24 | Himax Technologies Limited | LCD power supply |
| CN101315751B (en) * | 2007-05-30 | 2012-05-30 | 奇景光电股份有限公司 | LCD screen power module |
| CN101533607B (en) * | 2008-03-14 | 2011-03-30 | 原景科技股份有限公司 | Driving circuit of light emitting diode and driving method of light emitting diode |
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