CN1925712A - Fluorescent light control circuit and system - Google Patents
Fluorescent light control circuit and system Download PDFInfo
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- CN1925712A CN1925712A CN 200510095825 CN200510095825A CN1925712A CN 1925712 A CN1925712 A CN 1925712A CN 200510095825 CN200510095825 CN 200510095825 CN 200510095825 A CN200510095825 A CN 200510095825A CN 1925712 A CN1925712 A CN 1925712A
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Abstract
This invention relates to fluorescence lamp control circuit, which uses one impulse generation unit to generate one impulse signals within one preset range to control A/D inverter to drive fluorescence lamp to improve fluorescence lamp control circuit visual interference.
Description
Technical field
The invention relates to a kind of fluorescent lamp control circuit, and particularly relevant for a kind of low vision noise fluorescent lamp control circuit.
Background technology
LCD (Liquid Crystal Display LCD) is widely used recently, with replace cathode-ray tube display (Cathode Ray Tube, CRT).Improvement along with semiconductor technology, make LCD have advantages such as low consumption of electric power, slim amount is light, resolution is high, color saturation is high, the life-span is long, thereby be widely used in digital camera, notebook computer, desktop display, mobile phone, personal digital assistant (Personal DigitalAssistant, PDA), automobile-used TV, GPS (Global Position System) (Global PositionSystem, GPS), the electronic products closely bound up such as hand held electronic game, translating machine and electronic watch with life.
The demand of LCD backlight, (ColdCathode Fluorescent Lamp is CCFL) as light emitting source generally all to adopt cathode fluorescent tube.When the cathode fluorescent tube stable operation, needed power supply is that frequency range does not contain direct current (Direct Current about 30 kilo hertzs of (KHz)～80KHz greatly, DC) the string ripple of composition, wherein the stable operation voltage of fluorescent tube is close in constant, and the brightness of fluorescent tube is determined by the tube current by fluorescent tube.
In the application of reality, in the mode of the fixing frequency of operation of fluorescent lamp because can be than being easier to grasp the noise that is created on the fluorescent lamp frequency of operation, so general being used.But in the application of large scale liquid crystal display floater, because the quantity of fluorescent lamp heightens, therefore the high frequency noise that is produced also increases thereupon.
For avoiding vertical, horizontal time-base in fluorescent lamp frequency of operation and the video signal shows signal to produce the problem that difference frequency disturbs, it is that frequency of operation or phase place with different fluorescent lamps staggers with different control circuits that a kind of practice is arranged, to reduce the noise power that is positioned in the frequency spectrum on the fluorescent lamp frequency of operation, but this practice needs the control circuit of many groups, and whole cost is higher.
The gesture of driving that past gradually maximization, low priceization development are arranged in LCD, and the power that fluorescent lamp consumed is increasing, but but the vision noise is required under the more and more stricter situation, low vision noise, fluorescent lamp control circuit also becomes increasingly difficult in actual production cheaply.
Summary of the invention
In view of this, the purpose of this invention is to provide a kind of fluorescent lamp control circuit,, improve the purpose that vision noise that fluorescent lamp produced disturbs to reach by the operating frequency that changes pulse wave signal.
A further object of the present invention provides a kind of fluorescent lamp control system, by according to fluorescent lamp conduction status and brightness adjusting signal, change the operating frequency of pulse wave signal, reaching the adjustment brightness of fluorescent lamp, and improve the purpose that vision noise that fluorescent lamp produces disturbs.
For reaching above-mentioned purpose, the invention provides a kind of low vision noise fluorescent lamp control circuit, applicable to the fluorescent lamp in the control LCD.This low vision noise fluorescent lamp control circuit comprises one first pulse wave generating unit and a DC/AC converter.Wherein, this first pulse wave generating unit is used for producing first triangular signal and first pulse wave signal with a change frequency.The DC/AC converter then couples this first pulse wave generating unit, and first triangular signal and first pulse wave signal in order to the foundation change frequency come driving fluorescent lamp.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, the first above-mentioned pulse wave generating unit comprises a digital counting device, one group of current source, and a triangular wave generator.Wherein, it is to be provided to the size of current of triangular wave generator by current source to be determined that the triangle that the triangular wave generator produces involves its frequency of operation of pulse wave signal, the digital counting device is then adjusted the electric current that flows into this triangular wave generator current source at any time, makes this triangular wave generator produce the triangle that changes frequency of operation in time and involves pulse wave signal.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, its frequency change mode of the above-mentioned triangular wave that pulse wave generating unit produced can be that linear change can also be accurate change at random.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, above-mentioned AC/DC inverter controller more comprises one first pulse wave width modulation (Pulse Width Modulation, PWM) controller, a drive circuit, and a commutation circuit.Wherein, first controller of pulse width modulation is to be used for according to the feedback signal and first triangular signal, exports one first pulse wave width modulation signal.And drive circuit is to be used for according to this first pulse wave width modulation signal and this first pulse wave signal, exports a switch controlling signal.In addition, commutation circuit is to be used for according to this switch controlling signal, and output voltage signal is with driving fluorescent lamp.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, above-mentioned commutation circuit comprises semibridge system power switch and push-pull type power switch.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, above-mentioned AC/DC inverter controller more comprises a circuit for detecting and a protective circuit.Wherein, this circuit for detecting is the conduction status that is used for detecting fluorescent lamp, and exports a detection signal.Protective circuit then is to be used for receiving this detection signal, and according to this detection signal, the reset signal.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, above-mentioned circuit for detecting comprises voltage detection circuit or current-sensing circuit, is used for detecting the voltage or the electric current of fluorescent lamp.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, above-mentioned AC/DC inverter controller more comprises a resonant circuit, and (Alternating Current, AC) signal is with driving fluorescent lamp in order to voltage signal is filtered into an interchange.
According to the described fluorescent lamp control circuit of preferred embodiment of the present invention, more comprise one second pulse wave generating unit and one second controller of pulse width modulation.Wherein, second pulse wave generating unit is to be used for producing one second triangular signal, and wherein the frequency of operation of this second triangular signal is to change in time.Second controller of pulse width modulation then is in order to according to a brightness adjusting signal and one second triangular signal, exports one second pulse wave width modulation signal, with control AC/DC inverter controller output voltage signal, driving fluorescent lamp.
The present invention proposes a kind of fluorescent lamp control system, is applicable to drive a fluorescent lamp, and this control system comprises one first pulse wave generating unit, second pulse wave generating unit, and an AC/DC inverter controller.Wherein, this first pulse wave generating unit is to be used for producing one first pulse wave signal and one first triangular signal, and wherein the frequency of operation of this first pulse wave signal and this first triangular signal is to change in time.Second pulse wave generating unit then is to be used for producing one second triangular signal, and wherein the frequency of operation of this second triangular signal is to change in time.In addition, the AC/DC inverter controller is in order to the feedback signal according to first pulse wave signal, first triangular signal, second triangle signal, indication fluorescent lamp conduction status, and a brightness adjusting signal, export a voltage signal, with driving fluorescent lamp.
According to the described fluorescent lamp control system of preferred embodiment of the present invention, above-mentioned AC/DC inverter controller more comprises one first controller of pulse width modulation, second controller of pulse width modulation, a drive circuit, and a commutation circuit.Wherein, first controller of pulse width modulation is in order to according to the feedback signal and first triangular signal, exports one first pulse wave width modulation signal.And second controller of pulse width modulation is in order to according to the brightness adjusting signal and second triangular signal, exports one second pulse wave width modulation signal.In addition, drive circuit is in order to according to this first pulse wave width modulation signal, this second pulse wave width modulation signal, and this first pulse wave signal, exports a switch controlling signal.Then, commutation circuit is just according to this switch controlling signal, and output voltage signal is with driving fluorescent lamp.
The present invention is because of the structure of the operating frequency that adopt to change pulse wave signal, and can adjust brightness of fluorescent lamp according to fluorescent lamp conduction status and brightness adjusting signal, and reaches and improve the purpose that vision noise that fluorescent lamp produces disturbs.
For above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, preferred embodiment cited below particularly, and cooperate appended graphicly, be described in detail below.
Description of drawings
Fig. 1 is a kind of low vision noise fluorescent lamp control circuit block schematic diagram that illustrates according to preferred embodiment of the present invention.
Fig. 2 is the pulse wave signal generation unit schematic diagram of Fig. 1 circuit of illustrating according to preferred embodiment of the present invention.
Fig. 3 is the sequential chart of coherent signal in Fig. 2 pulse wave signal generation unit that illustrates according to preferred embodiment of the present invention.
Fig. 4 is a kind of low vision noise fluorescent lamp control circuit schematic diagram that illustrates according to preferred embodiment of the present invention.
Fig. 5 is the sequential chart of coherent signal among the Fig. 4 that illustrates according to preferred embodiment of the present invention.
Fig. 6 is a kind of low vision noise fluorescent lamp control circuit schematic diagram that utilizes the beam density light modulation that illustrates according to preferred embodiment of the present invention.
Fig. 7 is the sequential chart of coherent signal among the Fig. 6 that illustrates according to preferred embodiment of the present invention.
Fig. 8 is the schematic diagram of a kind of push-pull type DC/AC converter of illustrating according to preferred embodiment of the present invention.
Fig. 9 is the schematic diagram of the DC/AC converter of a power switch design of a kind of usefulness illustrating according to preferred embodiment of the present invention.
100: low vision noise fluorescent lamp control circuit 110: pulse wave generating unit
120:DC/AC converter 130,430: fluorescent lamp
200: pulse wave generating unit 210: the triangular wave generator
211,212: comparator 213,214:NAND lock
215:PMOS switch 216:NMOS switch
220: controlled current source 230: digital counting device
400: low vision noise fluorescent lamp control circuit 410: pulse wave generating unit
420: semibridge system DC/AC converter 440:PWM controller
450: digital drive circuit 460: half-bridge power switch
470: resonant circuit 471: transformer
472,473,474: capacitor 480: voltage detection circuit
485: current-sensing circuit 490: protective circuit
600: utilize beam density to adjust the fluorescent lamp control circuit of brightness
610: pulse wave generating unit 620: low frequency light modulation pulse wave generating unit
621: pulse wave generating unit 630: the DC/AC converter of semibridge system
631:PWM controller 632: resonant circuit
810: inverter 820: the center tap transformer
830: capacitor
900: the DC/AC converter that has only N type MOSFET
Embodiment
Fig. 1 is a kind of low vision noise fluorescent lamp control circuit block schematic diagram that illustrates according to preferred embodiment of the present invention.Please refer to shown in Figure 1ly, this low vision noise fluorescent lamp control circuit 100 is applicable to the fluorescent lamp of control in the LCD.
As shown in the figure, this low vision noise fluorescent lamp control circuit 100 comprises: pulse wave generating unit 110, DC/AC converter 120 and fluorescent lamp 130.Wherein, pulse wave generating unit 110 is to be used for producing triangular signal RAMP and pulse wave signal CLK.120 triangular signal RAMP and pulse wave signal CLK that produced according to pulse wave generating unit 110 of DC/AC converter produce AC AC signal driving fluorescent lamp 130.In order to improve the vision noise interference that the DC/AC converter is produced, so the operating frequency of the triangular signal RAMP of pulse wave signal output and pulse wave signal CLK is controlled in the preset range changes, to avoid exporting the triangular signal RAMP and the pulse wave signal CLK of fixed frequency, and produce difference frequency and disturb with vertical, horizontal time-base in the video signal shows signal, cause so-called " fanning effect ", and on picture, form the ripples line that visually disturbs.
Fig. 2 is the pulse wave signal generation unit schematic diagram of Fig. 1 circuit of illustrating according to preferred embodiment of the present invention.Please refer to shown in Figure 2ly, this pulse wave generating unit 200 comprises that one is subjected to 210, one groups of controlled current sources 220 of triangular wave generator of Current Control frequency of operation, and a digital counting device 230.
As shown in Figure 2, the comparator 211 and 212 of the triangular wave generator 210 in this pulse wave generating unit 200 is to be used for comparison RAMP voltage, peak value (Peak) voltage, and valley (Valley) voltage, when RAMP＞Peak, open N type metal oxide semiconductor (N-TypeMetal Oxide Semiconductor, NMOS) switch 216 to be being connected the electric current of B end, and to electric capacity 217 discharges; When RAMP＜Valley, open PMOS switch 215 being connected the electric current of A end, and to electric capacity 217 chargings.Controlled current source 220 then is by a pair of main current source I0 and I0 ', and other controlled current source I1 that differs in size, I1 ', and I2, I2 ', I3, I3 ' ..., IN, IN ' (wherein N is any natural number greater than 3) forms.These controlled current sources I1, I1 ', I2, I2 ', I3, I3 ' ..., IN, IN ' are subjected to current supply switch SW1 respectively, SW1 ', and SW2, SW2 ', SW3, SW3 ' ..., SWN, SWN ' control its opportunity that flows into A end or B end.
In addition, 230 pulse wave signal CLK that receive 210 outputs of triangular wave generator of digital counting device are with the clock pulse of pulse wave signal CLK as digital counting device 230, to send different current switch control signal SWC and SWC ' at each different clock pulse.Make the controlled current source 220 can be, send the electric current that varies in size to A, the B two ends according to the variation of time.Triangular wave generator 210 is then according to the A that flows through, changing in time of B two ends and the electric current that changes produces triangular wave RAMP and pulse wave signal CLK that frequency changes in time.
Fig. 3 is the sequential chart of coherent signal in Fig. 2 pulse wave signal generation unit that illustrates according to preferred embodiment of the present invention.Please refer to Fig. 3, in the present embodiment, I1＜I2＜I3＜...＜IN, and I1 '＜I2 '＜I3 '＜...＜IN ', thus T1＞T2＞T3＞... TN.Digital counting device 230 is that unit progressive is opened SW1 ', SW1 with two pulse wave signal CLK clock times (Clock Time), then SW2 ', SW2 ... until SWN ', SWN after again from SWN-1, SWN-1 ' ... be opened to SW1 ', SW1 in proper order, continuous variation triangular wave RAMP that so goes round and begins again and the frequency of operation of pulse wave signal CLK.
This example can also utilize the digital counting device 230 that can be stylized to change these current supply switchs SW1, SW1 ', SW2, SW2 ' arbitrarily, SW3, SW3 ' ..., SWN, the switching sequence of SWN ' is designed to the frequency of any conversion, for example be known standard at random (Pseudorandom) change.
Present embodiment is used for cooperating the DC/AC converter, is unit so be set at the cycle of frequency change with two pulse wave signal CLK clock times (Clock Time).Can certainly set other arbitrary unit for, for example be that each clock time changes once.And the waveform of triangular wave RAMP also can by different current ratio (for example In＜＜In ', n=0,1,2,3 ..., N) waveform of change triangular wave for example is a sawtooth waveforms.
Fig. 4 is a kind of low vision noise fluorescent lamp control circuit 400 schematic diagrames that illustrate according to preferred embodiment of the present invention.Please refer to Fig. 4, this example comprises as shown in Figure 3 a pulse wave generating unit 410, wherein original capacitor 217 makes into to be made up of other circuit such as two different capacitor C 1, C2, also comprises the DC/AC converter 420 of a semibridge system in addition, and fluorescent lamp 430.
Wherein the DC/AC converter 420 of semibridge system comprises a direct current voltage source DC, 450, one groups of half-bridge power switches 460 of a PWM controller 440, one digital drive circuits, resonant circuit 470, voltage detection circuit 480, current-sensing circuit 485, and protective circuit 490.
Under general situation, after fluorescent lamp 430 starts, current-sensing circuit 485 is exported an indicating lamp tube Continuity signal ISEN ' via input signal ISEN, and produce a RUN signal by OR logic lock and make C1 C2 in parallel, and lower frequency before making the DC/AC converter 420 of semibridge system operate in to start than fluorescent lamp 430.The RUN signal is controlled pulse wave generating unit 410 simultaneously, system can be designed to start fluorescent lamp 430. and current-sensing circuit 485 provides an indicating lamp tube current signal FB to PWM controller 440 in addition with fixed frequency, 440 of PWM controllers are according to known negative feedback the control principle relatively FB and the first reference voltage VREF1, produce triangular wave RAMP that output CMP and pulse wave generating unit 410 produce by comparator C MP_PWM relatively after generation one pwm signal.According to known negative feedback principle, the work period of pwm signal (DutyCycle) can increase when FB＜VREF1, and reduces to stablize the operating current of fluorescent lamp 430 when FB＞VREF1.
Pwm signal inputs to a digital drive circuit 450 subsequently, digital drive circuit 450 cooperates pwm signal with generation power switch drive signal POUT and NOUT with the pulse wave signal CLK that is produced by pulse wave generating unit 410, is used for driving semiconductor switch P and N in the half-bridge power switch 460 respectively.Wherein semiconductor switch P and N take turns conducting and pulse wave signal so that direct voltage source is switched, and send into resonant circuit 470.
Inductance in the transformer 471 in the resonant circuit 470 and capacitor 472,473,474 constitutes a filter circuit, and from semiconductor switch P, the pulse wave signal that N sends into is sent in the fluorescent lamp 430 after filtering into the AC signal.
And protective circuit 490 preset through timer TIMER be used for starting the time of fluorescent lamp 430 after; to export timing end signal Time_out to start protective device; once (for example short circuit phenomenon of the arcing phenomenon of overtension, brownout or the open circuit phenomenon of not conducting of fluorescent tube) when unusual takes place in light tube electric voltage VSEN or indicating lamp tube conduction status signal ISEN; can detect via protective circuit 490; and stop imitating signal Disable according to the detection signal decision output one of input and stop semiconductor power switch P, N continues conducting.
Fig. 5 is the sequential chart of coherent signal among the Fig. 4 that illustrates according to preferred embodiment of the present invention.Please refer to Fig. 5 because the fixed amplitude of triangular wave RAMP, so the work period of PWM ripple also be fixing, therefore can obtain the stable signal AC of a size and output to fluorescent lamp 430.Wherein, the transverse axis in Fig. 5 is represented time shaft, and t1＞t2＞t3.
Fig. 6 is that illustrate according to preferred embodiment of the present invention a kind of utilizes beam density to adjust fluorescent lamp control circuit 600 schematic diagrames of brightness, and the embodiment of Fig. 6 can regard as and the low vision noise fluorescent lamp control circuit 400 among Fig. 4 be added another pulse wave generating unit 410 of operating with low frequency more again and suitable binding is constituted.
The fluorescent lamp control circuit 600 of Fig. 6 comprises that the DC/AC converter 630, of 640, one semibridge systems of a fluorescent lamp produces first pulse wave generating unit 610 of fluorescent lamp frequency of operation and the low frequency light modulation pulse wave generating unit 620 of a generation beam density light modulating frequency.In the application of reality, if the frequency of operation of fluorescent lamp 640 is set near the 50KHz, the frequency that then is used for being used as the beam density light modulation can be set near 200Hz～2KHz.
Comprise one second pulse wave generating unit 621 in the low frequency light modulation pulse wave generating unit 620 of the generation beam density light modulating frequency that increases newly among Fig. 6, this second pulse wave generating unit 621 can produce the triangular wave RAMP_DIM that frequency of operation changes in time.Triangular wave RAMP_DIM with control brightness input signal VDIM through comparator C MP_DIM relatively after, produce a pulse wave width modulation signal (Pulse Width Modulation Signal) PWM_DIM.On using, the user can utilize the brightness adjusting signal VDIM that varies in size and fixed amplitude and triangular wave RAMP_DIM that frequency changes in time, pulse wave width modulation signal PWM_DIM through relatively producing the different operating cycle exports with the semibridge system DC/AC converter 630 that produces different beams density, changes different brightness.
In the present embodiment, PWM_DIM is used for control switch SW1, when PWM_DIM output is logic " height ", opens switch SW 1; When output is logic " low ", off switch SW1 then.And switch SW 2 is with deciding the switch that when carries out light modulation.In the present embodiment, when indicating lamp tube Continuity signal ISEN ' indicating lamp tube conducting or timer TIMER time are sent timing end signal (Time_out), show the default starting time then, SW2 will be unlocked this moment, and open to make and carry out light modulation.In case SW2 is opened, to send the second reference voltage VREF2 or " open circuit (Floating) " signal by the switch SW 1 that PWM_DIM controlled, be sent to the inverting input INN of the error amplifier ERR_AMP of PWM controller 631 in the DC/AC converter 630 of semibridge system through resistance R DIM.
When VREF2 sent into the DC/AC converter 630 of semibridge system, if the VREF1 of inverting input INN＞non-inverting input of error amplifier ERR_AMP, the result can tie the only output of the DC/AC converter 630 of semibridge system; Otherwise if the VREF1 of inverting input INN＜non-inverting input of error amplifier ERR_AMP, the result can begin the output of the DC/AC converter 630 of semibridge system.And according to the negative feedback principle, the inverting input INN of the error amplifier ERR_AMP of the DC/AC converter 630 of semibridge system is the situation of non-inverting input VREF1 no better than, and continues the output of the DC/AC converter 630 of semibridge system.
Fig. 7 is the sequential chart of coherent signal among the Fig. 6 that illustrates according to preferred embodiment of the present invention.Please refer to Fig. 7, under normal circumstances, fluorescent lamp 640 is driven by fogdog (Bright), is as Fig. 5 at the AC signal among the Bright, and change in time and change (Fig. 7 only is that schematic diagram is not drawn waveform), and T1 '＞T2 '＞T3 '.
The variation pattern of present embodiment intermediate cam ripple RAMP_DIM also is to be that unit progressive changes with two clock times.This can certainly make other into and changes in time arbitrarily and the mode that changes, for example is to be that unit progressive changes or is the accurate change at random of unit with each clock time with each clock time.
In addition, in the application of other possible reality, two triangular wave RAMP and RAMP_DIM among Fig. 6, can all be that frequency of operation changes in time, also can have only one of them is that frequency of operation changes in time, for example be to have only RAMP_DIM to change in time, and RAMP is a fixed frequency.In addition, fluorescent lamp 640 can be one, also can be more than one with series connection, or in parallel, or the mode that connection in series-parallel mixes links.
And most important, the semibridge system DC/AC converter 420 and 630 among Fig. 4 and Fig. 6 can adopt various different driving structures.For instance, Fig. 8 is the schematic diagram of a kind of push-pull type DC/AC converter of illustrating according to preferred embodiment of the present invention.Please refer to Fig. 8, after power switch drive signal POUT added an inverter 810, drive two N type MOS field-effect transistors (Field-Efect Transistor, FET) N1 and N2, change center tap transformer 820 then, can constitute the push-pull type converter.
Fig. 9 is the schematic diagram of the DC/AC converter of a power switch design of a kind of usefulness illustrating according to preferred embodiment of the present invention.Please refer to Fig. 9, only utilize NOUT driving one to have only the DC/AC converter 900 of N type MOSFET.
These embodiment of Fig. 8 and Fig. 9 can utilize the pulse wave generating unit 200 among the embodiment of Fig. 2 of the present invention, are designed to that frequency of operation changes in time and the DC/AC converter that changes comes driving fluorescent lamp.
In sum, fluorescent lamp control circuit of the present invention is used a pulse wave generating unit, produce the pulse wave signal that frequency constantly changes in a preset range,, use and improve the vision noise interference that fluorescent lamp control circuit produces with control converter driving fluorescent lamp.
Though the present invention discloses as above with preferred embodiment; so it is not to be used for limiting the present invention; anyly have the knack of this skill person; without departing from the spirit and scope of the present invention; when can doing a little change and retouching, so protection scope of the present invention is as the criterion when looking accompanying the claim person of defining.
Claims (18)
1, a kind of fluorescent lamp control circuit is applicable to drive a fluorescent lamp, it is characterized in that this control circuit comprises:
One first pulse wave generating unit is used for producing one first pulse wave signal and one first triangular signal, and wherein the frequency of operation of this first pulse wave signal and this first triangular signal is to change in time; And
One AC/DC inverter controller is used for according to this first pulse wave signal, this first triangular signal, and a feedback signal of indicating this fluorescent lamp conduction status, exports a voltage signal, to drive this fluorescent lamp.
2, fluorescent lamp control circuit according to claim 1 is characterized in that wherein said first pulse wave generating unit more comprises:
One triangular wave generator is used for producing this first pulse wave signal and this first triangular signal;
One current source is used to provide this triangular wave generator one electric current; And
One digital counting device is used for adjusting the electric current that this current source offers this triangular wave generator, and this that makes this triangular wave generator produce to change frequency of operation in time first sent ripple signal and this first triangular signal.
3, fluorescent lamp control circuit according to claim 1 is characterized in that wherein said AC/DC inverter controller more comprises:
One first controller of pulse width modulation in order to according to this feedback signal and this first triangular signal, is exported one first pulse wave width modulation signal;
One drive circuit in order to according to this first pulse wave width modulation signal and this first pulse wave signal, is exported a switch controlling signal; And
One switches circuit, in order to according to this switch controlling signal, exports this voltage signal, to drive this fluorescent lamp.
4, fluorescent lamp control circuit according to claim 3 is characterized in that wherein said commutation circuit comprises the semibridge system power switch.
5, fluorescent lamp control circuit according to claim 3 is characterized in that wherein said commutation circuit comprises the push-pull type power switch.
6, fluorescent lamp control circuit according to claim 3 is characterized in that wherein said AC/DC inverter controller more comprises:
One circuit for detecting is used for detecting the conduction status of this fluorescent lamp, and exports a detection signal; And
One protective circuit is used for receiving this detection signal, and according to this detection signal, exports this feedback signal.
7, fluorescent lamp control circuit according to claim 6 is characterized in that wherein said circuit for detecting comprises a voltage detection circuit, is used for detecting the voltage of this fluorescent lamp.
8, fluorescent lamp control circuit according to claim 6 is characterized in that wherein said circuit for detecting comprises a current-sensing circuit, is used for detecting the electric current of this fluorescent lamp.
9, fluorescent lamp control circuit according to claim 1 is characterized in that wherein said AC/DC inverter controller more comprises:
One resonant circuit is used for this voltage signal is filtered into an AC signal, to drive this fluorescent lamp.
10, fluorescent lamp control circuit according to claim 1, the amplitude that it is characterized in that wherein said first triangular signal are a default constant.
11, fluorescent lamp control circuit according to claim 1, the frequency of operation that it is characterized in that wherein said voltage signal is to change in time.
12, fluorescent lamp control circuit according to claim 1 is characterized in that it more comprises:
One second pulse wave generating unit is used for producing one second triangular signal, and wherein the frequency of operation of this second triangular signal is to change in time; And
One second controller of pulse width modulation in order to according to a brightness adjusting signal and this second triangular signal, is exported one second pulse wave width modulation signal, exports this voltage signal to control this AC/DC inverter controller, drives this fluorescent lamp.
13, fluorescent lamp control circuit according to claim 12, the amplitude that it is characterized in that wherein said second triangular signal are a default constant.
14, fluorescent lamp control circuit according to claim 12, the work period that it is characterized in that wherein said second triangular signal is determined by this brightness adjusting signal, in case brightness is fixed, the work period is also fixing thereupon.
15, a kind of fluorescent lamp control system is applicable to drive a fluorescent lamp, it is characterized in that this control system comprises:
One first pulse wave generating unit is used for producing one first pulse wave signal and one first triangular signal, and wherein the frequency of operation of this first pulse wave signal and this first triangular signal is to change in time;
One second pulse wave generating unit is used for producing one second triangular signal, and wherein the frequency of operation of this second triangular signal is to change in time; And
One AC/DC inverter controller, in order to according to this first pulse wave signal, this first triangular signal, this second triangle signal, indicate a feedback signal of this fluorescent lamp conduction status, and a brightness adjusting signal, export a voltage signal, to drive this fluorescent lamp.
16, fluorescent lamp control system according to claim 15 is characterized in that wherein said AC/DC inverter controller more comprises:
One first controller of pulse width modulation in order to according to this feedback signal and this first triangular signal, is exported one first pulse wave width modulation signal;
One second controller of pulse width modulation in order to according to this brightness adjusting signal and this second triangular signal, is exported one second pulse wave width modulation signal;
One drive circuit, in order to according to this first pulse wave width modulation signal, this second pulse wave width modulation signal, and this first pulse wave signal, export a switch controlling signal; And varying signal, and this first pulse wave signal, export a switch controlling signal; And
One switches circuit, in order to according to this switch controlling signal, exports this voltage signal, to drive this fluorescent lamp.
17, fluorescent lamp control system according to claim 16 is characterized in that wherein said commutation circuit comprises the semibridge system power switch.
18, fluorescent lamp control system according to claim 16 is characterized in that wherein said commutation circuit comprises the push-pull type power switch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200510095825 CN1925712A (en) | 2005-09-02 | 2005-09-02 | Fluorescent light control circuit and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200510095825 CN1925712A (en) | 2005-09-02 | 2005-09-02 | Fluorescent light control circuit and system |
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| Publication Number | Publication Date |
|---|---|
| CN1925712A true CN1925712A (en) | 2007-03-07 |
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|---|---|---|---|
| CN 200510095825 Pending CN1925712A (en) | 2005-09-02 | 2005-09-02 | Fluorescent light control circuit and system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101754556A (en) * | 2008-12-05 | 2010-06-23 | 奇美电子股份有限公司 | Backlight module containing dimming control circuit, and display |
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- 2005-09-02 CN CN 200510095825 patent/CN1925712A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101754556A (en) * | 2008-12-05 | 2010-06-23 | 奇美电子股份有限公司 | Backlight module containing dimming control circuit, and display |
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