CN101056485A - Driving circuit of backlight device with the protection module group - Google Patents
Driving circuit of backlight device with the protection module group Download PDFInfo
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- CN101056485A CN101056485A CNA2006100724174A CN200610072417A CN101056485A CN 101056485 A CN101056485 A CN 101056485A CN A2006100724174 A CNA2006100724174 A CN A2006100724174A CN 200610072417 A CN200610072417 A CN 200610072417A CN 101056485 A CN101056485 A CN 101056485A
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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
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- 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
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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Abstract
A driving circuit of a light emitting diode includes transformer, driving module and protection module. The transformer has a primary side coil, and a secondary side coil, wherein, a first end of the primary side coil couples to the a voltage resource and a first end of the secondary side coil couples to the light emitting diode and the second end of the secondary side coil connects the ground. Furthermore, the second end of the transformer primary side coil couples to the driving module, and the driving module decides whether delivers the electric power to the transformer depending on the pulse width modulating signal and a wrong signal. However, the protection module couples to the secondary side coil in order to produce wrong signal to the driving module when the driving voltage emitting from the transformer to the light emitting diode is less than the first presetting voltage or more than the second presetting voltage.
Description
Technical field
The invention relates to a kind of Driving technique of light-emitting diode, and particularly relevant for a kind of Driving technique that is used for the light-emitting diode of back lighting device.
Background technology
In existing known back lighting device, adopt cathode fluorescent tube mostly as light source.But owing to the lifting of photoelectric cell technical level, light-emitting diode has plurality of advantages such as small size, low operating voltage, life-span length, color saturation height in recent years.Therefore, use the light source of light-emitting diode, become another kind of new selection as back lighting device.
Since the relation on the processing procedure, even if the light-emitting diode on same wafer all can have different electrical characteristics, so (in parallel) light-emitting diode is on reality is used, the drop of luminosity is very big.And in order to improve the yield of processing procedure, and reduce the cost of making, therefore the light-emitting diode that uses in the present LED backlight device, extremely mostly is to adopt the light-emitting diode of series connection to be used as light emitting source, the electric current equalization of feasible each light-emitting diode of flowing through is close to identical luminosity and have.
See also Fig. 1 and illustrate a kind of circuit diagram that has known LED backlight device now.See also Fig. 1, in existing known LED backlight device, have most the light-emitting diodes 101 that connect with series system and be used as light source, and these light-emitting diodes 101 can pass through resistance 103 ground connection at last.
Please continue to consult shown in Figure 1, the influence that changes in order to reduce light-emitting diode 101 luminous brightness to drift about in time, therefore in back lighting device, all can dispose pulse-width modulation (PWM) controller 105, control the brightness of light-emitting diode 101 in order to generation pulse-width modulation signal Vpwm.In existing known back lighting device, PWM controller 105 can be delivered to pulse-width modulation signal Vpwm the gate terminal of nmos pass transistor 107.Wherein, the drain electrode end of nmos pass transistor 107 is to be coupled to voltage source V DD by inductance 109, and is coupled to the light-emitting diode 101 of series connection by Schottky diode 111, and passes through electric capacity 113 ground connection.In addition, the source terminal of nmos pass transistor 107 then is a ground connection.
In addition, PWM controller 105 also is coupled to the node that light-emitting diode 101 and resistance 103 couple mutually, with the electric current of detecting light-emitting diode 101.Whereby, PWM controller 105 can decide the duty ratio of pulse-width modulation signal Vpwm according to the result of detecting, so that adjust the brightness of light-emitting diode 101.
Booster circuit as shown in Figure 1 produces an output dc voltage Vout higher than voltage source V DD, to drive each light-emitting diode 101.Yet along with the large scaleization of flat-panel screens, the size of back lighting device also needs to increase thereupon, cause required light-emitting diode 101 also more to be adopted the more, required driving voltage is also high more, and the multiplying power of boosting that the booster circuit of Fig. 1 can provide is not high, and so high driving voltage can't be provided.Therefore, the size of voltage source V DD certainly will be subject to as the circuit elements design of boosting, and the demand that light-emitting diode 101 series connection numbers continue to increase can't be more flexiblely satisfied with inductor 101.
In addition, after light-emitting diode 101 series connection numbers continued to increase, its driving voltage can raise, and makes that the demand of high voltage protective is arranged.Present LED backlight device only is clamped at driving voltage below a certain magnitude of voltage by Schottky diode.But when higher driving voltage, Schottky diode that must anti-more high pressure not only increases the element cost, and also still continues output HIGH voltage but not stop output, so also may cause the damage of other elements.
Summary of the invention
For this reason, the invention provides a kind of drive circuit of light-emitting diode, can drive the light-emitting diode of more series connection number, therefore can be useful in the display screen of many different sizes.
The drive circuit of diode provided by the present invention also has preferable protection module, can protect at the too high or too low driving voltage of drive circuit output of the present invention.
The drive circuit of light-emitting diode provided by the present invention comprises transformer, drives module and protection module.Wherein, transformer has first siding ring and second siding ring.In the present invention, first end of first siding ring is coupled to a voltage source, and first end of second siding ring is coupled to light-emitting diode, and the second end ground connection of second siding ring.In addition, second end of the first siding ring of transformer is coupled to the driving module, drives module and then determines whether transmitting electric power to this transformer according to a pulse-width modulation signal and a rub-out signal.The protection module then is to couple second siding ring, and during less than one first predeterminated voltage or greater than one second predeterminated voltage, the generation rub-out signal is to driving module, to stop the output of electric power with the driving voltage that exports light-emitting diode when transformer to.
In an embodiment of the present invention, above-mentioned protection module comprises one first comparator, one first counter and an original counter.First comparator is to be used for judging whether driving voltage is lower than first predeterminated voltage, and exports one first comparative result.First counter then is to receive first comparative result, and produces one first count signal when driving voltage continues to keep one first Preset Time less than first predeterminated voltage.And in the present invention, first counter is activated and also surpasses in the start Preset Time at drive circuit is disabled state.In addition, original counter is to be used for just producing an initial count signal and coming activation first counter after drive circuit is activated and passes through the start Preset Time.First count value that first counter is exported can be delivered to one and fasten the lock device, and delivers to a non-driving module that exports to behind the door by fastening the lock device.
In addition, the protection module more comprises one second comparator and one second counter.Second comparator is to be used for judging whether driving voltage is higher than second predeterminated voltage, and exports one second comparative result.Second counter then is to receive second comparative result, and produces one second count signal when driving voltage continues one second Preset Time greater than second predeterminated voltage.This second count signal can be sent to one or door, and this or door be except receiving second count signal, and receives first count signal.In addition, should or the door output be to deliver to fasten the lock device.
In other was selected embodiment, the second above-mentioned comparator was judged the size of the driving voltage and the one the second predeterminated voltages.Different is, second comparator has high magnetic hysteresis, and when driving voltage is above greater than second predeterminated voltage, one hysteresis voltage, then second comparator just can produce have a high-end trim export one or door to.And this or door also can receive above-mentioned output of fastening the lock device, and the output of this or door can be sent to above-mentioned not gate.
Back lighting device provided by the present invention has comprised a light source module.In addition, back lighting device of the present invention is to use above-mentioned drive circuit to come the driving light source module luminous.
Because the present invention has used transformer to convert voltage source to driving voltage and come driving light source, whereby, the present invention just can adjust the size of driving voltage according to the number of light-emitting diode series connection, and unrestricted.Therefore, the present invention in the use can be more flexible.
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 illustrates a kind of circuit diagram that has known LED backlight device now.
Fig. 2 A illustrates the circuit diagram according to a kind of back lighting device of the first embodiment of the present invention.
Fig. 2 B illustrates the circuit diagram of a kind of back lighting device of using protective circuit of the present invention.
Fig. 3 illustrates the circuit diagram according to a kind of back lighting device of the second embodiment of the present invention.
Fig. 4 illustrates the circuit diagram according to a kind of back lighting device of the third embodiment of the present invention
Fig. 5 illustrates according to a kind of dim signal of a preferred embodiment of the present invention and the sequential chart of pulse-width modulation signal.
101,212: light-emitting diode
103,272,292,294: resistance
105,280,380,480: pulse-width modulation (PWM) controller
107,224:NMOS transistor
109,236: inductance
111: Schottky diode
200A, 200B, 300,400: back lighting device
210,310,410: the light source module
222,422: with door
220,320,420: drive module
230,330,430: transformer
232: first siding ring
234: second siding ring
240,340,440: the protection module
246,248,342: comparator
250,252,260: counter
254: or door
256: fasten the lock device
258: not gate
276: electric capacity
290: the detecting voltage module
VDD: voltage source
Embodiment
Below with reference to appended drawing, describe preferred embodiment of the present invention in detail.Wherein those appended drawing illustrate the various preferred embodiments of the present invention.The present invention can also multitude of different ways realize the embodiment that it is not limited in this explanation.Have the knack of related art techniques person and fully understand category of the present invention for allowing in this purpose that embodiment is provided.Hereinafter, similar reference number is represented similar element.
Fig. 2 A illustrates the circuit diagram according to a kind of back lighting device of the first embodiment of the present invention.See also Fig. 2 A, back lighting device 200A provided by the present invention has comprised light source module 210 and the drive circuit of being made up of driving module 220, transformer 230 and protection module 240.In an embodiment of the present invention, light source module 210 can be made up of 212 series connection of most light-emitting diodes.Utilize transformer 220 that the higher multiplying power of boosting can be provided, and can provide higher driving DC voltage to drive the more light-emitting diode of series connection number.
In detail, the cathode terminal of each light-emitting diode 212 all is coupled to the anode tap of next light-emitting diode 212, and last light-emitting diode 212 then can pass through resistance 272 ground connection.Haveing the knack of this skill person should be known in and light-emitting diode 212 in back lighting device 200A can comprise white light emitting diode, red light-emitting diode, blue light-emitting diode and green light LED.
Please continue to consult Fig. 2, transformer 230 has first siding ring 232 and second siding ring 234, and the ratio of the two is 1 to compare n.In the present embodiment, first end of first siding ring 232 is coupled to voltage source V DD, and second end then is coupled to and drives module 220.In addition, first end of second siding ring 234 can be coupled to light source module 210 by a diode 274, for example is coupled to the anode tap of first light-emitting diode 212, and second end of second siding ring 234 then is a ground connection.In preferable situation, diode 274 can utilize Schottky diode to realize.
First end of second siding ring 234 also is coupled to protection module 240 except coupling light source module 210, and by electric capacity 276 ground connection.The output of protection module 240 is then delivered to and is driven module 220, makes the output that drives module 220 meeting foundation protection modules 240 determine whether stopping the electric power of output voltage source VDD to transformer 230.
In the present embodiment, pulse-width modulation signal Vpwm is produced by pulse-width modulation (PWM) controller 280.In addition, the voltage of the node that PWM controller 280 can detecting light source modules 210 couples with resistance 272, the electric current of light source module 210 of flowing through of detecting just.Whereby, pulse-width regulating device 280 just can be controlled the duty ratio of pulse-width modulation signal Vpwm according to the detection signal of light source module 210, makes light source module 210 that stable brightness can be arranged.Certainly, pulse-width modulation (PWM) controller 280 also can produce pulse-width modulation signal Vpwm according to the detection signal (for example: be coupled to detecting voltage module 290) of the voltage of light source module 210.
In detecting voltage module 290, comprised resistance 292 and 294, wherein first end of resistance 292 couples the cathode terminal of diode 274, and is coupled to first end of second siding ring 234 by diode 274.In addition, second end of resistance 292 then is by resistance 294 ground connection, and is coupled to the negative input end of comparator 246 and the positive input terminal of comparator 248.Driving module 220, protection module 240, PWM controller 280 and detecting voltage module 290 can be incorporated in the integrated circuit wafer.Perhaps, detecting voltage module 290 is independent outside the integrated circuit wafer, makes the designer of back lighting device can more freely distribute the ratio of resistance 292 and 294, and more can cooperate various back lighting device.
In addition, the positive input terminal of comparator 246 receives a predeterminated voltage Vr1, and the negative input end of comparator 248 then is to receive predeterminated voltage Vr2.Whereby, comparator 246 just can compare driving voltage VOUT and predeterminated voltage Vr1, and produces a comparative result R1 to counter 250.Similarly, comparator 248 can compare driving voltage VOUT and predeterminated voltage Vr2, and produces comparative result R2 to counter 252.In the present embodiment, comparator 246,248 is respectively to be used for detecting driving voltage VOUT whether low and too high phenomenon took place, so predeterminated voltage Vr1 is less than predeterminated voltage Vr2.
Next the operating process of back lighting device 200A is described.
In addition, counter 252 receives EA=1 and starts, and this moment, so comparator 248 output R2=0 were counter 252 output T2=0 because driving voltage VOUT is lower than predeterminated voltage Vr2.Therefore, or output low level signal behind door 254 reception T1=0 and the T2=0, and fasten that lock device 256 receives EA=1 and after starting, receive or the low level signal of door 254 and also export the low level signal, and through the high levle signal of the anti-phase back output E1=1 of not gate 258.Whereby, in start at back lighting device 200A initial the time, EA=1 and E1=1, will produce the switch that pulse-width modulation signal Vpwm control nmos pass transistor 224 according to PWM controller 280 with door 222, and transformer 230 just can convert voltage source V DD to driving voltage VOUT and comes driving light source module 210.
When timer after first scheduled time of 260 timing to, if EA also maintains the high levle signal of " 1 ", the high levle signal that timer 260 can output T0=1 then.Therefore, timer 250 can begin operation behind the signal of reception T0=1.The 260 first preferable scheduled times of timer are back lighting device 200A general required start-up time of length, enter normal running through light source module 210 after this first scheduled time.So when timer 250 came into operation, detecting voltage module 290 was exported greater than predeterminated voltage Vr1 less than the detection signal voltage of predeterminated voltage Vr2.Output signal R1, the R2 of comparator 246,248 is the low level signal behind the normal operation state so enter, and then the output signal T1 of timer 250,252 and T2 also are the low level signal.Therefore, the normal startup down fastened lock device 256 and keeps output low level signal, and make signal E1 maintain the low level of " 0 ".
Yet, cause driving voltage VOUT low excessively when starting failure or other error conditions, for example, when a user touches second siding ring 234 ends of transformer 230 accidentally, can cause driving voltage VOUT to discharge to formed discharge path between the ground connection by human body.At this moment, driving voltage VOUT can be lower than predeterminated voltage Vr1, and comparator 246 will be exported the output signal R1 of a high levle state to counter 250, makes counter 250 begin counting.
When driving voltage VOUT was lower than predeterminated voltage Vr1 and continues one second Preset Time, the count signal T1 that counter 250 will produce a high-end trim gave or door 254.Whereby, or the door 254 will send exporting to of high levle state fasten the lock device 256.Fasten the output of lock device 256 and pin in the output signal of a high levle state, then by after not gate 258 anti-phase, the rub-out signal E1 that can produce a low-end trim gives and door 222.Whereby, can be so that transistor 224 be closed (turn off), and cause transformer 230 stop supplies driving voltage VOUT to give light source module 210.And meeting of the present invention is excluded in this low power event, and the user restart back lighting device 200A make wrong reset signal EA=0 and reset with the door 222, counter 252, counter 260 and fasten the lock device 256 after, could continue to provide driving voltage VOUT to light source module 210.
On the other hand, yet, when some error conditions cause driving voltage VOUT too high, protect the comparator 248 of module 240 to detect the too high phenomenon of driving voltage VOUT generation.At this moment, driving voltage VOUT is during greater than predeterminated voltage Vr2, and what comparator 248 can produce the high levle states exports to counter 252, makes counter 252 begin counting.When driving voltage VOUT continued one the 3rd Preset Time greater than predeterminated voltage Vr2, the count signal T2 that counter 252 can produce high levles gave or door 254, and by or door 254 deliver to and fasten lock device 256.Then, fasten the output of lock device 256 and pin in the output signal of a high levle state, again via not gate 254 anti-phase after, the rub-out signal E1 that also can produce a low level state gives and door 222.Therefore, transistor 224 also can present closing state, gives the light source module and cause transformer 230 to be unable to supply driving voltage VOUT.Similarly, the present invention gets rid of in this high voltage incident, and starting back lighting device 200A by the user makes wrong reset signal EA=0 and resets with door 222, counter 252, counter 260 and after fastening lock device 256, could supply driving voltage VOUT again and give light source module 210.
As shown in the above description, when timer 260 after first scheduled time, the function of protection module 240 beginning execute protections.Cross low or the too high voltages phenomenon as long as driving voltage VOUT occurs, 240 controls of protection module are also pinned drive circuit 220 in the state of decommissioning, and make transformer 230 be unable to supply driving voltage VOUT and stop for the light source module.Unless the user restarts back lighting device 200A, otherwise back lighting device 200A can maintain the state that stops to export, and could normally start back lighting device 200A after this error event is got rid of.
Certainly, the T0 signal of counter 260 of the present invention also can be directly inputted to fastens lock device 256 but not timer 250, so at the signal of T0 after start-up course changes to 1 by 0, fasten lock device 256 and just begin to operate.Similarly, also can avoid back lighting device 200A as before when start just, because driving voltage VOUT crosses low and taken place when wrong situation.
In other selection embodiment, protective circuit of the present invention also can be used on existing known booster circuit except that being used in the back lighting device that boosts with transformer.Fig. 2 B for example, wherein transformer changes inductance 236 into.Detect driving voltage VOUT through protective circuit 240 by detecting voltage module 290; when driving voltage VOUT was too high or too low, counter 252 or 250 will pick up counting, through a scheduled time; this too high or too low voltage status still continues down, the output that will stop and pin driving voltage VOUT.After stopping and pinning the output of driving voltage VOUT, must restart back lighting device 200B again, make the EA signal be 0 low level signal to reset protective circuit and drive circuit, back lighting device 200B is operated again.
In addition, the wrong reset signal EA among the present invention is a control signal that need not stop the action of back lighting device power supply also can stopping back lighting device.Utilize this wrong reset signal EA, remove under back lighting device pins because of error condition, make in order to the replacement back lighting device outside it starts once more, the system that comprises back lighting device can control back lighting device by wrong reset signal EA and start running in appropriate time.So, system can arrange the startup opportunity of other devices in back lighting device and the system and reduce interference each other or reach preferable boot sequence.
Fig. 3 illustrates the circuit diagram according to a kind of back lighting device of the second embodiment of the present invention.See also Fig. 3, the back lighting device 200A that the back lighting device 300 and first embodiment are provided is similar substantially, has light source module 310, PWM controller 380, driving module 320, transformer 330 and protection module 340.And the relation of coupling and the operating principle of these members are had the knack of this skill person and can be consulted among first embodiment about light source module 210, PWM controller 280 voluntarily, drive the narration of module 220, transformer 230 and protection module 240.
Yet different is, in protection module 340, is to adopt the comparator 342 with high magnetic hysteresis to replace comparator 248 among first embodiment.In the present embodiment, comparator 342 equally also is that driving voltage Vout and predeterminated voltage Vr2 are compared.Yet as driving voltage Vout during greater than one of predeterminated voltage Vr2 (comparator 342) hysteresis voltage, comparator 342 can produce the output R3 of high-end trim.Therefore, in the present embodiment, protection module 340 can reduce by a counter.
During a hysteresis voltage, the output R3 that comparator 342 will produce the high levle state gives or door 344 more than driving voltage Vout is greater than predeterminated voltage Vr2.Wherein, or door another input of 344 be to receive the output of fastening lock device 256.Whereby, when comparator 342 produces the output R3 of high-end trim, will by or door 344 be sent to not gate 346, and via not gate 346 anti-phase after, the rub-out signal E2 that can produce a low-end trim gives and door 222.Specifically, because the output of comparator 342 can be via fastening the lock device, therefore as long as make comparator 342 export the output R3 of low level state once again when the voltage of driving voltage Vout is returned to normal condition, back lighting device 300 can reset automatically again, and does not need the user manually to come activation mistake reset signal EA.
Fig. 4 illustrates the circuit diagram according to a kind of back lighting device of the third embodiment of the present invention.See also Fig. 4, the back lighting device 400 that present embodiment provided is identical substantially with the back lighting device 200A that first embodiment is provided, and all has light source module 410, PWM controller 480, driving module 420, transformer 430 and protection module 440.And the relation of coupling and the operating principle of these members are had the knack of this skill person can consult voluntarily among first embodiment, about the narration of light source module 210, PWM controller 280, driving module 220, transformer 230 and protection module 240.
Different with first embodiment is that driving module more than 420 has received dim signal DIM, makes back lighting device 400 have the function of light modulation.In the present embodiment, drive module 420 comprised with door 222 and nmos pass transistor 224 outside, also have and door 422.Wherein, be used for receiving wrong reset signal EA and dim signal DIM, and the frequency of dim signal DIM is low than the frequency of pulse-width modulation signal Vpwm with door 422.By the duty ratio of control dim signal DIM, switching time that can controlling and driving module 420 and reach the effect of light modulation
Fig. 5 illustrates according to a kind of dim signal of a preferred embodiment of the present invention and the sequential chart of pulse-width modulation signal.Please merge and consult Fig. 4 and Fig. 5, in the present embodiment, when needs reduce the brightness of light source module 410, only need send than the low relatively dim signal DIM (as shown in Figure 5) of the frequency of pulse-width modulation signal Vpwm to the input of door 422.Then, just pulse-width modulation signal Vpwm and dim signal DIM can be carried out " AND " computing with door 222.Whereby, just can produce the gate terminal of output signal K1, to downgrade the brightness of light source module 410 to transistor 224.Relatively, when needs increase the brightness of light source module, then need to produce duty ratio bigger dim signal DIM get final product to input with door 422.
In sum, the present invention has following advantage at least:
1. because the present invention has adopted transformer to produce driving voltage, so the present invention can provide the driving voltage of big multiple to come driving light source, and therefore drive circuit provided by the present invention can be suitable for the back lighting device of various sizes.
2. also because the present invention has adopted transformer to produce driving voltage, so the present invention not only can boost and produce driving voltage, can also utilize the mode of step-down to produce driving voltage, makes the present invention more flexible in the use.
3. because the present invention has the protection module, therefore can protect light source in the operation of crossing under low-voltage or the too high voltages.
4. the present invention can also have the mechanism of light modulation, can allow the user adjust the brightness of back lighting device according to actual needs.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limit 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 when looking being as the criterion that aforementioned application patented technology scheme defined.
Claims (14)
1, a kind of drive circuit of light-emitting diode is characterized in that it comprises:
One transformer has one lateral coils and a second siding ring, and wherein first end of this first siding ring is coupled to a voltage source, and first end of this second siding ring is coupled to the light-emitting diodes of most series connection, and the second end ground connection of this second siding ring;
One PWM controller produces a pulse-width modulation signal in order to the detection signal according to those light-emitting diodes; And
One drives module, is coupled to second end of the first siding ring of this transformer, and transmits electric power to this transformer according to this pulse-width modulation signal.
2, the drive circuit of light-emitting diode according to claim 1; it is characterized in that it further comprises a protection module; couple this transformer; in order to the driving voltage that exports those light-emitting diodes when this transformer to during less than one first voltage or greater than one second voltage; then produce a rub-out signal and drive module to this, wherein this driving module stops to transmit electric power to this transformer according to this rub-out signal.
3, the drive circuit of light-emitting diode according to claim 2 is characterized in that wherein said driving module comprises:
One with door, in order to receive this pulse-width modulation signal and this rub-out signal; And
One nmos pass transistor, its gate terminal couple this and the output of door, and its drain electrode end couples second end of this first siding ring, and its source terminal ground connection.
4, the drive circuit of light-emitting diode according to claim 3, it is characterized in that wherein said driving module further receives a dim signal in order to adjust the brightness of those light-emitting diodes, wherein the frequency of this dim signal is different with the frequency of this pulse-width modulation signal.
5, the drive circuit of light-emitting diode according to claim 2 is characterized in that it further comprises a detecting voltage module, and producing a detecting voltage signal, and this protection module comprises according to this driving voltage:
One first comparator is in order to comparing this detecting voltage signal and one first predeterminated voltage, to judge that this driving voltage is whether less than first voltage and export one first comparative result;
One first counter receives this first comparative result, and produces one first count signal when this driving voltage continues one first Preset Time less than this first voltage; And
One fastens the lock device, receives this first count value.
6, the drive circuit of light-emitting diode according to claim 5; it is characterized in that wherein said protection module further comprises an original counter; in order to be activated at this drive circuit and through one the start Preset Time after; just produce an initial count signal, with this first counter of activation.
7, the drive circuit of light-emitting diode according to claim 5 is characterized in that wherein said protection module further comprises:
One second comparator is in order to comparing this detecting voltage signal and one second predeterminated voltage, to judge that this driving voltage is whether greater than second voltage and export one second comparative result;
One second counter receives this second comparative result, and produces one second count signal when this driving voltage continues one second Preset Time greater than this second voltage; And
One or door, receive this first count signal and this second count signal, and output is delivered to this fasten the lock device.
8, the drive circuit of light-emitting diode according to claim 5 is characterized in that wherein said protection module further comprises:
One hysteresis, second comparator in order to this detecting voltage signal and one second predeterminated voltage are compared, and is exported one second count signal according to comparative result; And
One or door, receive this and fasten the lock output signal of device and this second count signal.
9, a kind of back lighting device is characterized in that it comprises:
One light source module;
One stepup transformer is coupled to a voltage source and this light source module, drives this light source module to produce a direct current driving voltage;
One protection module couples this stepup transformer, in order to when this driving voltage during greater than a predetermined voltage, then produces a rub-out signal; And
One drives module, stops output power to this light source module according to this rub-out signal.
10, back lighting device according to claim 9 is characterized in that wherein said driving module comprises:
One with door, in order to receive pulse-width modulation signal and this rub-out signal produce according to the detection signal of this light source module; And
One nmos pass transistor, its gate terminal couple this and the output of door, and its drain electrode end couples this stepup transformer, and its source terminal ground connection.
11, back lighting device according to claim 10 is characterized in that wherein said driving module further receives a dim signal in order to adjust the brightness of those light-emitting diodes, and wherein the frequency of this dim signal is different with the frequency of this pulse-width modulation signal.
12, back lighting device according to claim 9 is characterized in that wherein said protection module comprises to fasten the lock device, in this driving voltage greater than this predetermined voltage and continue this Preset Time finger lock to continue to produce this rub-out signal.
13, back lighting device according to claim 9; it is characterized in that it further comprises a detecting voltage module; protect module to produce a detecting voltage signal to this according to this driving voltage, so that this protection module judges that whether this driving voltage is greater than this predetermined voltage.
14, back lighting device according to claim 9 is characterized in that wherein said driving module couples a reset signal, to determine whether output power is to this light source module.
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| CNB2006100724174A CN100463580C (en) | 2006-04-11 | 2006-04-11 | Driving circuit of backlight device with the protection module group |
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| CNB2006100724174A CN100463580C (en) | 2006-04-11 | 2006-04-11 | Driving circuit of backlight device with the protection module group |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102752902A (en) * | 2011-04-22 | 2012-10-24 | 登丰微电子股份有限公司 | Light-emitting diode (LED) driving circuit |
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| CN2168260Y (en) * | 1993-09-29 | 1994-06-08 | 邓进军 | High-voltage on-line detecting instrument |
| KR100471161B1 (en) * | 2003-05-28 | 2005-03-14 | 삼성전기주식회사 | Back-light inverter for lcd panel with self-protection function |
| US6995991B1 (en) * | 2004-07-20 | 2006-02-07 | System General Corp. | PWM controller for synchronous rectifier of flyback power converter |
| CN1731909A (en) * | 2004-08-06 | 2006-02-08 | 尼克森微电子股份有限公司 | Multi lamp tube control circuit |
| US7482048B2 (en) * | 2005-04-22 | 2009-01-27 | Azdel, Inc. | Composite thermoplastic sheets including an integral hinge |
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2006
- 2006-04-11 CN CNB2006100724174A patent/CN100463580C/en not_active Expired - Fee Related
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| CN101489335B (en) * | 2008-01-18 | 2012-12-19 | 尼克森微电子股份有限公司 | LED driving circuit and secondary side controller thereof |
| CN101605416B (en) * | 2008-06-13 | 2013-02-27 | 登丰微电子股份有限公司 | LED driving circuit and controller thereof |
| TWI451809B (en) * | 2010-12-22 | 2014-09-01 | Leadtrend Tech Corp | Light emitting module driving circuit and related method |
| CN102752902A (en) * | 2011-04-22 | 2012-10-24 | 登丰微电子股份有限公司 | Light-emitting diode (LED) driving circuit |
| US9101033B2 (en) | 2011-11-04 | 2015-08-04 | Leadtrend Technology Corp. | Short protection control circuits and related control methods |
| CN103249208A (en) * | 2012-02-14 | 2013-08-14 | 通嘉科技股份有限公司 | Short-circuit protection control circuit and relevant control method |
| CN104703318A (en) * | 2013-12-04 | 2015-06-10 | 亚硕绿能股份有限公司 | Light emitting diode driving integrated circuit and application circuit thereof |
| CN104091722A (en) * | 2014-07-22 | 2014-10-08 | 无锡中微爱芯电子有限公司 | Relay drive circuit |
| CN104091722B (en) * | 2014-07-22 | 2016-08-31 | 无锡中微爱芯电子有限公司 | Relay drive circuit |
| EP3460968A1 (en) * | 2017-09-13 | 2019-03-27 | NXP USA, Inc. | Digital control algorithm using only two target voltage thresholds for generating a pulse width modulated signal driving the gate of a power mos to implement a switch mode power supply |
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| CN100463580C (en) | 2009-02-18 |
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