CN101207958B - Driving circuit and related driving method for providing feedback control and open-circuit protection - Google Patents
Driving circuit and related driving method for providing feedback control and open-circuit protection Download PDFInfo
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- CN101207958B CN101207958B CN2007103018581A CN200710301858A CN101207958B CN 101207958 B CN101207958 B CN 101207958B CN 2007103018581 A CN2007103018581 A CN 2007103018581A CN 200710301858 A CN200710301858 A CN 200710301858A CN 101207958 B CN101207958 B CN 101207958B
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Abstract
A driving circuit includes a first light-emitting device, a first constant-current supplier, a voltage regulator circuit, an analysis and decision circuit, and a first switch. The first constant-current supplier provides a constant current to the first light-emitting device. The voltage regulator circuit provides a driving voltage to the first light-emitting device and adjusts driving voltage according to a feedback signal. The analysis and decision circuit is coupled to the voltage regulator circuit and the first light-emitting device. The analysis and decision circuit generates a first switch control signal. The first switch is coupled to the first light-emitting device, the analysis and decision circuit, and the voltage regulator circuit. The first switch is turned on and off according to the first switch control signal.
Description
Technical field
The present invention system a kind of providing is provided feedbacks drive circuit and the drive method thereof thereof of control with open-circuit-protection, refers to especially a kind ofly utilize one to analyze the state of detecting light-emitting device with decision circuitry and feedback drive circuit and the drive method thereof thereof of control with open-circuit-protection to provide.
Background technology
Because light-emitting diode (Light Emitting Diode, hereinafter to be referred as LED) have advantages such as the little and low power consumption of size, therefore light-emitting diode at present by development and application in backlight module, with be used for replacing traditional cold cathode-ray fluorescent tube (Cold Cathode F1uorescentLamp, CCFL).Extensively applied to consumption, advertisement, industry, military affairs etc. and used, become one of emphasis of electronic industry research and development.Light-emitting diode is a semiconductor device, directly converts electric energy to light, just as other electronic component, when bearing excessive electric current or voltage, very easily is subjected to destroy or damage.Therefore, when demand increases, the protective circuit that must design can bear excessive curtage.Light-emitting diode often is applied to luminous indication (Light Indicator), or the light emitting source of other portable electronic product, similarly be mobile phone, mobile computer, personal digital assistant (Personal Data Assistant, PDA) etc.Yet, use the demand of the giant display (for example large-scale neon light, LCD backlight plate) of light-emitting diode also to increase gradually, these application needs use a lot of light-emitting diodes to provide giant display enough light sources.Because the forward biased current of light-emitting diode can be the increase of exponential type along with its forward bias, generally can use current source to come the driven for emitting lights diode, so that different light-emitting diodes can reach consistent luminosity.
Please refer to Fig. 1, Fig. 1 is the schematic diagram of prior art one conventional ADS driving circuit 100.Drive circuit 100 comprises a voltage conversion circuit 110, a light-emitting device 120 and certain current supply 130.Wherein, voltage conversion circuit 110 has a first input end 112 and is used for receiving an input voltage V-IN, and one second input 114 is used for receiving a back coupling signal FB, and an output 116 is coupled to one of light-emitting device 120 input.Voltage conversion circuit 110 is to be used to provide a driving voltage VDD to give light-emitting device 120.Deciding current supply 130 provides certain electric current I c to come driven for emitting lights device 120.In other words, decide current supply 130 and can dynamically adjust the brightness value of light-emitting device 120 according to adjusting the current value of deciding electric current I c.
As shown in Figure 1, light-emitting device 120 comprises a plurality of light-emitting diodes 140.Note that each light-emitting diode 140 is called as a power source drive device, and, the brightness of light-emitting diode with decide electric current I c and be directly proportional.The brightness meeting that is to say each light-emitting diode 140 increases along with the increase of deciding electric current I c.Generally speaking, reach uniform brightness, depend on identical electric current to drive each light-emitting diode 140 in order to make a plurality of light-emitting diodes 140.In order to reach the consistent luminous requirement of measuring, a plurality of light-emitting diodes 140 must connect in the mode of series connection.That is to say that whenever couple a light-emitting diode 140, light-emitting device 120 needed forward bias voltage Vf will improve more.Therefore, voltage conversion circuit 110 must provide higher driving voltage VDD to supply with enough forward bias voltage Vf to light-emitting device 120.
Please refer to Fig. 2, Fig. 2 is the schematic diagram of another conventional ADS driving circuit 200 of prior art.Drive circuit 200 comprises a voltage conversion circuit 210, six light-emitting device 221-226, six to be decided current supply 231-236 and and selects circuit 250.Drive circuit 200 is similar to the drive circuit 100 among Fig. 1, and both differences are that drive circuit 200 is to be coupled to more light-emitting device, and comprises selection circuit 250 in addition.In present embodiment, only indicate six light-emitting device 221-226, but can extend to light-emitting device more or still less.Voltage conversion circuit 210 is to be used to provide driving voltage VDD to give light-emitting device 221-226.And first decides current supply 231 and provides one first to decide electric current I 1 and drive first drive unit 221, and by that analogy, deciding current supply 236 for the 6th provides one the 6th to decide electric current I 6 and drive the 6th drive unit 226.
Yet owing to be subject to the material and the processing procedure of light-emitting diode, each light-emitting diode 240 required forward bias voltage is also inequality.For instance, suppose that first light-emitting device 221 comprises three light-emitting diodes 240, and each light-emitting diode 240 needed forward bias voltage and inequality.Therefore, light-emitting device 221-226 has different forward bias voltage Vf1-Vf6.In this example, drive circuit 200 can use selects circuit 250 from choosing minimum voltage level in the middle of these six voltage level Vdrop1-Vdrop6 to export the input 214 of the accurate VN in a minimum voltage position to voltage conversion circuit 210.That is to say, decide the power dissipation of current supply 231-236 and guarantee that six light-emitting device 221-226 all can normal operation in order to reduce each, therefore, select circuit 250 to choose minimum voltage level in the middle of these six voltage level Vdrop1-Vdrop6 with as the accurate VN in minimum voltage position, and reset signal FB.Wherein, six central minimum voltage level systems of voltage level Vdrop1-Vdrop6 are corresponding to voltage level maximum in the middle of six forward bias voltage Vf1-Vf6.
Please continue with reference to figure 1 and Fig. 2, can adjust driving voltage VDD according to back coupling signal FB.If drive circuit need drive a plurality of light-emitting devices, select circuit 250 can choose minimum voltage level in the middle of six voltage level Vdrop1-Vdrop6 and be used as feedbacking signal FB.That is to say, can reduce the power dissipation that each decides current supply 231-236.Second light-emitting device 222 in the middle of supposing burns (perhaps being open circuit), selects circuit 250 always to select second voltage level Vdrop2 to be used as to feedback signal FB, and in this case, driving voltage VDD can constantly rise.Hypothesis driven voltage VDD greater than 200 of drive circuits can load maximum voltage the time, at this moment, whole drive circuit or its inner assembly may and then be damaged.
Summary of the invention
One of main purpose of the present invention is to disclose a kind of drive circuit of back coupling control with open-circuit-protection that provide, to improve the shortcoming in the prior art.
A kind of drive circuit of back coupling control with open-circuit-protection that provide is provided in the present invention system, and this drive circuit comprises at least one light-emitting device, a voltage conversion circuit one analysis and decision circuitry and one and selects circuit.This voltage conversion circuit system is coupled to this light-emitting device, is used to provide a driving voltage to drive this light-emitting device.This analysis and decision circuitry system are coupled to this light-emitting device, are used for judging whether this light-emitting device is that open circuit is to produce a judged result.This selection circuit system is coupled between this analysis and decision circuitry and this voltage conversion circuit, be used for according to this judged result with select this light-emitting device the maximum forward bias voltage of correspondence produce one and feedback signal, and should feedback signal and be sent to this voltage conversion circuit, wherein this voltage conversion circuit is adjusted this driving voltage according to this back coupling signal.
In an embodiment, this light-emitting device comprises at least one light-emitting diode.
In an embodiment, this analysis and decision circuitry comprise one second comparator, at least one open circuit detector and a control logic.This second comparator system is used for this dividing potential drop driving voltage and this second reference voltage are compared to produce one second comparison signal.This open circuit detector system is used for detecting one of this light-emitting device state.This control logic system is used for producing this judged result according to this second comparison signal and this first detection signal.
One of main purpose of the present invention is to disclose a kind of driving method of back coupling control with open-circuit-protection that provide, to improve the shortcoming in the prior art.
A kind of driving method of back coupling control with open-circuit-protection that provide is provided in the present invention system, and this driving method comprises: provide a driving voltage to drive at least one light-emitting device; Judge whether this light-emitting device is that open circuit is to produce a judged result; According to this judged result with select this light-emitting device the maximum forward bias voltage of correspondence produce one and feedback signal; And adjust this driving voltage according to this back coupling signal.
Description of drawings
Fig. 1 is the schematic diagram of prior art one conventional ADS driving circuit.
Fig. 2 is the schematic diagram of another conventional ADS driving circuit of prior art.
Fig. 3 is for one providing and feedback the schematic diagram of control with the drive circuit of open-circuit-protection among first embodiment one of according to the present invention.
Fig. 4 is the schematic diagram of the voltage conversion circuit among Fig. 3.
Fig. 5 is for one providing and feedback the schematic diagram of control with the drive circuit of open-circuit-protection among second embodiment one of according to the present invention.
Fig. 6 is for one providing and feedback the schematic diagram of control with the drive circuit of open-circuit-protection among the 3rd embodiment one of according to the present invention.
Fig. 7 is for one providing and feedback the schematic diagram of control with the drive circuit of open-circuit-protection among the 4th embodiment one of according to the present invention.
Fig. 8 provides for explanation among the embodiment one of according to the present invention is a kind of and feedbacks the schematic diagram of control with the flow process of the driving method of open-circuit-protection.
Embodiment
Please refer to Fig. 3, Fig. 3 is for one providing and feedback the schematic diagram of control with the drive circuit 300 of open-circuit-protection among first embodiment one of according to the present invention.Drive circuit 300 comprises a voltage conversion circuit 310, at least one light-emitting device 321-326 (in present embodiment, represent explanation with six light-emitting device 321-326), certain at least current supply 331-336 is (in present embodiment, decide current supply 331-336 with six and represent explanation), one select circuit 350, to analyze and decision circuitry 360 and at least one switch SW 1-SW6 (in present embodiment, representing explanation) with six switch SW 1-SW6.Voltage conversion circuit 310 has a first input end 312 and is used for receiving an input voltage VIN, and one second input 314 is used for receiving a back coupling signal FB, and an output 316 is coupled to six light-emitting device 321-326.Voltage conversion circuit 310 is to be used to provide a driving voltage VDD to give whole light-emitting device 321-326.Deciding current supply 331-336 for six is used to provide certain electric current respectively and drives corresponding light-emitting device.For instance, first decides current supply 331 provides one first to decide electric current I 1 to first light-emitting device 321, and the rest may be inferred.
In present embodiment, analysis comprises one second comparator C OMP2, six open circuit detector 381-386 with decision circuitry 360, and a control logic 370.The second comparator C OMP2 has the output 316 that a first input end 362 is coupled to voltage conversion circuit 310, is used for receiving driving voltage VDD, and one second input 364 is used for receiving one second reference voltage Vref 2.The second comparator C OMP2 compares the driving voltage VDD and second reference voltage Vref 2 to produce one second comparison signal Sc2.If greater than second reference voltage Vref 2, analyzing with decision circuitry 360, driving voltage VDD system can utilize these six open circuit detector 381-386 to detect the state of corresponding light-emitting device to produce this judged result.In other words, open circuit detector 381-386 detects the state of corresponding light-emitting device to produce corresponding detection signal Sd1-Sd6 to control logic 370.Then, control logic 370 can relatively signal Sc2 and six detection signal Sd1-Sd6 (that is this judged result) produce six switch controlling signal Ss1-Ss6 and control the unlatching of corresponding switch SW 1-SW6 or close according to second.
Consider following several situations; If driving voltage VDD system is less than second reference voltage Vref 2, then control logic 370 can according to second relatively signal Sc2 and six detection signal Sd1-Sd6 (that is this judged result) produce six switch controlling signal Ss1-Ss6 and open whole switch SW 1-SW6, whole voltage level Vdrop1-Vdrop6 delivered to and selected circuit 350 this moment.Then, select circuit 350 in the middle of these voltage levels Vdrop1-Vdrop6, to select minimum voltage level, and deliver to second input 314 of voltage conversion circuit 310 with the output minimum voltage accurate VN in position.Driving voltage VDD can adjust according to the accurate VN in minimum voltage position (back coupling signal FB).Because voltage level system minimum in the middle of the voltage level Vdrop1-Vdrop6 is corresponding to voltage level maximum in the middle of the forward bias voltage Vf1-Vf6, in other words, select circuit 350 in the middle of forward bias voltage Vf1-Vf6, to select the maximum to produce back coupling signal FB.
Hypothesis driven voltage VDD continues to rise and greater than second reference voltage Vref 2, then analyzes with decision circuitry 360 and can utilize open circuit detector 381-386 to detect the state of corresponding light-emitting device.If when having any one light-emitting device to be detected as open circuit, control logic 370 can be closed its corresponding switch.For instance, if the state of second light-emitting device 322 is an open circuit, then sees through second switch controlling signal Ss2 second switch SW2 is closed.In in such cases, will be sent to except other voltage level Vdrop1-Vdrop6 second voltage level Vdrop2 and select circuit 350.Then, circuit 350 can select in the middle of these five voltage levels minimum voltage level with as back coupling signal FB.Because second light-emitting device 322 is detected as open circuit, the second voltage level Vdrop2 (in being approximately 0V in such cases) is removed in the middle of the selection of selecting circuit 350, have influence on back coupling signal FB to avoid the second voltage level Vdrop2.Up to the present driving voltage VDD can not continue to rise always.Whole drive circuit 300 or its assembly will avoid being damaged.
In an embodiment, light-emitting device 321-326 can individual comprise at least one light-emitting diode (LED).Deciding current supply 331-336 can respectively be that an electric current attracts a source or an electric current source of supply.The second comparator C OMP2 can be a hysteresis comparator to avoid misoperation.In addition, the quantity of light-emitting device is not limited to six respectively, also can be other quantity.Each assembly in the foregoing description only is used for the present invention's the most example explanation, and those assemblies are not necessary restrictive condition of the present invention.
Please note, the second above-mentioned comparator C OMP2 is only for being used for illustrating one of execution mode of analyzing with decision circuitry 360, be not the present invention's restrictive condition, know this skill person and should understand, analysis all is feasible with the various variations of decision circuitry 360.
Please refer to Fig. 4 and Fig. 3.Fig. 4 is the schematic diagram of the voltage conversion circuit 310 among Fig. 3.Voltage conversion circuit 310 comprises one first a comparator C OMP1 and a voltage conversion unit 318.The first comparator C OMP1 has a first input end and is used for receiving back coupling signal FB, and one second input is used for receiving one first reference voltage Vref 1.The first comparator C OMP1 will feedback signal FB and first reference voltage Vref 1 and compare to export one first signal Sc1 relatively.Voltage conversion unit 318 is to be used to provide driving voltage VDD to give light-emitting device 321-326 (as shown in Figure 3), and dynamically adjusts driving voltage VDD according to the first comparison signal Sc1 that the first comparator C OMP1 is exported.For instance, if feedback signal FB system greater than first reference voltage Vref, 1, the first comparator C OMP1 can export first relatively signal Sc1 control voltage conversion unit 318 and equate with first reference voltage Vref 1 up to voltage level VN to reduce driving voltage VDD; If feedback signal FB system and can control voltage conversion unit 318 less than first reference voltage Vref, 1, the first comparator C OMP1 and increase driving voltage VDD and equate with first reference voltage Vref 1 up to voltage level VN.Generally speaking, voltage conversion circuit 310 can be realized by the chip for driving of any traditional power supply unit, pressurizer or light-emitting device, that is to say that voltage conversion circuit 310 can be exported the driving voltage VDD that wants according to an ac current source or a direct current current source.
Please refer to Fig. 5, Fig. 5 is for one providing and feedback the schematic diagram of control with the drive circuit 500 of open-circuit-protection among second embodiment one of according to the present invention.Drive circuit 500 is similar with the drive circuit 300 among Fig. 3, and both differences are, Fig. 5 produces a dividing potential drop driving voltage VM with driving voltage VDD after through the dividing potential drop of one first resistance R 1 and one second resistance R 2.Because driving voltage VDD has higher voltage usually, via can obtaining less dividing potential drop driving voltage VM after the dividing potential drop, and the second comparator C OMP2 ratio of low voltage is easier to implement.Note that the alternate embodiment of drive circuit 500 for drive circuit 300 shown in Figure 3, wherein first resistance R 1 and second resistance R 2 are not the assembly for necessity.Above embodiment only is used for illustrating the present invention, does not limit to the present invention's practical application.
Please refer to Fig. 6, Fig. 6 is for one providing and feedback the schematic diagram of control with the drive circuit 600 of open-circuit-protection among the 3rd embodiment one of according to the present invention.Drive circuit 600 is another alternate embodiment of drive circuit 300 shown in Figure 3, is that in previous alternate embodiment difference the control logic 370 of drive circuit 600 has an output in addition, is used for exporting an output signal So to control a switch 640.Wherein, when output signal So is high levels, represent that whole light-emitting device 321-326 all is detected as open circuit, at this moment, will feedback signal FB strangulation at the accurate VM in a fixed voltage position.In in such cases, driving voltage VDD can be clamped at a fixed voltage.Note that feedbacking signal FB can be clamped at any voltage level (visual user's demand and set), and voltage level VM is only for one of being used for illustrating embodiment.In addition,, know usually that by having in the affiliated technical field the knowledgeable is known, do not add to give unnecessary details at this about the execution mode of feedbacking signal FB and driving voltage VDD.
Please refer to Fig. 7 and Fig. 6.Fig. 7 is for one providing and feedback the schematic diagram of control with the drive circuit 700 of open-circuit-protection among the 4th embodiment one of according to the present invention.Drive circuit 700 is one of drive circuit 600 a shown in Figure 6 alternate embodiment, and both are described below difference.Drive circuit 700 comprise in addition one the start delayer 720 and one or the door 730.Start delayer 720 is to be used for confirming whether driving voltage VDD has arrived a normal voltage position standard.If the state of above-mentioned situation or all light-emitting device 321-326 that takes place is all open circuit, or door 730 can come control switch 640 by output one signal, to feedback signal FB is connected to voltage level VM, that is to say, if the state of all light-emitting device 321-326 is all open circuit, back coupling signal FB can be fixed on voltage level VM.In in such cases, driving voltage VDD can be clamped at a fixed voltage.Note that feedbacking signal FB can be clamped at any voltage level (visual user's demand and set), and voltage level VM is only for one of being used for illustrating embodiment.In addition,, know usually that by having in the affiliated technical field the knowledgeable is known, do not add to give unnecessary details at this about the execution mode of feedbacking signal FB and driving voltage VDD.
Please refer to Fig. 8, Fig. 8 provides for explanation among the embodiment one of according to the present invention is a kind of and feedbacks the schematic diagram of control with the flow process 800 of the driving method of open-circuit-protection.Flow process 800 comprises following step:
Step 8002: flow process begins.
Step 8004: provide electric current to whole light-emitting device 321-326.
Step 8006: provide driving voltage VDD to whole light-emitting device 321-326.
Step 8008: open whole switch SW 1-SW6.
Step 8010: in the middle of the pairing voltage level of the output of whole light-emitting devices, select wherein minimum voltage level with as back coupling signal FB.
Step 8012: FB adjusts driving voltage VDD according to the back coupling signal.
Step 8014: judge that whether driving voltage VDD is greater than second reference voltage Vref 2.If driving voltage VDD system is greater than second reference voltage Vref 2, execution in step 8016; Otherwise, execution in step 8010.
Step 8016: whether detecting has the state of which light-emitting device is open circuit.If it is open circuit that the state of any one light-emitting device is arranged, execution in step 8018; Otherwise, execution in step 8010.
Step 8018: the switch that will correspond to the light-emitting device that is detected as open circuit cuts out.
Step 8020: the state that judges whether whole light-emitting devices is all open circuit.If the state of whole light-emitting devices is all open circuit, execution in step 8022; Otherwise, execution in step 8010.
Step 8022: will feedback signal FB strangulation at driving voltage VDD.
Step 8024: flow process finishes.
Please contrast drive circuit 300 shown in Figure 3.In step 8004-8006, all light-emitting device 321-326 systems provide electric current by deciding current supply 331-336, and provide driving voltage VDD by drive circuit 310.In step 8008, at the beginning all switch SW 1-SW6 are opened.At this moment, all voltage level Vdrop1-Vdrop6 are sent to select circuit 350, the voltage level of selecting a minimum in the middle of the voltage level Vdrop1-Vdrop6 is with as back coupling signal FB (step 8010).Therefore, can adjust driving voltage VDD (step 8012) according to feedback voltage FB.Then, the second comparator C OMP2 begins the driving voltage VDD and second reference voltage Vref 2 are compared (step 8014), if driving voltage VDD system gets back to step 8010, and still all switch SW 1-SW6 opened less than second reference voltage Vref 2; If driving voltage VDD system is greater than second reference voltage Vref 2, the detector 381-386 that then opens a way can detect the state of its corresponding light-emitting device and check that the state whether any one light-emitting device is arranged is open circuit (step 8016).When the state that were it not for any one light-emitting device is open circuit, get back to step 8010; If when the state detecting of one of them light-emitting device is open circuit, its corresponding switch cuts out (step 8018).That is to say detecting its pairing voltage level of this light-emitting device for open circuit is removed from the option of selecting circuit 350.Then, select circuit 350 can from except detecting in the middle of other all voltage levels its pairing voltage level of this light-emitting device of open circuit, select minimum voltage level with as back coupling signal FB (getting back to step 8010).At last, adjust driving voltage VDD according to the back coupling signal FB after upgrading.Under another kind of situation,, then will feedback signal FB strangulation at driving voltage VDD (step 8020-8022) if all light-emitting devices all are detected as the open circuit device.At this moment, process ends.
In an embodiment, above-mentioned step 8012 can comprise several steps in addition:
Step 8102: will feedback the signal FB and first reference voltage Vref 1 compares.If feedback signal FB greater than first reference voltage Vref 1, execution in step 8104; Otherwise, execution in step 8106.
Step 8104: reduce driving voltage VDD.
Step 8106: supercharging driving voltage VDD.
In an embodiment, above-mentioned step 8014 can be replaced by following step:
Step 8202: driving voltage VDD is carried out dividing potential drop to produce a dividing potential drop driving voltage VM.
Step 8204: the dividing potential drop driving voltage VM and second reference voltage Vref 2 are compared.
Step 8206: judge that whether dividing potential drop driving voltage VM is greater than second reference voltage Vref 2.If dividing potential drop driving voltage VM system is greater than second reference voltage Vref 2, execution in step 8016; Otherwise, can arrive step 8014.
The order that note that each step among Fig. 8 is not unmodifiable, and for example, step 8004 can be merged into same step with step 8006.
Above-described embodiment only is used for illustrating the present invention, does not limit to the present invention's category.The light-emitting device 321-326 that is mentioned in the literary composition can comprise at least one light-emitting diode (LED), and the number of light-emitting device is not limited to six, and also extendible is other any number.Deciding current supply 331-336 can be the current supply of deciding that an electric current attracts source, an electric current source of supply or other pattern.The second comparator C OMP2 is not limited to a hysteresis comparator, also can be other comparator.In addition, voltage conversion circuit 310 can be realized by the chip for driving of any traditional power supply unit, pressurizer or light-emitting device.Please note, drive circuit 500 and drive circuit 400 only are the alternate embodiment of drive circuit 300 shown in Figure 3, wherein some assembly similarly is that first resistance R 1, second resistance R 2, start delayer 720 or door 730 and switch 640 only are the selectivity assembly.Above embodiment only is used for illustrating the present invention, does not limit to the present invention's practical application.In addition, the order of each step among Fig. 8 is adjustable.
As from the foregoing, the invention provides kind of a drive circuit and a drive method thereof thereof that back coupling control and open-circuit-protection can be provided.See through the drive circuit that the present invention disclosed, not only can control back coupling signal FB so that a suitable driving voltage VDD to be provided, and can detect the open-circuit condition of light-emitting device.Especially when one drive circuit need drive a large amount of light-emitting devices, the present invention can provide enough driving voltages (enough electric currents) to drive all light-emitting devices.In addition, select circuit 350 can choose minimum voltage level (that is from forward bias voltage Vf1-Vf6 in the middle of maximum voltage level) in the middle of the voltage level Vdrop1-Vdrop6 with as back coupling signal FB, thus, can reduce the power consumption that each decides current supply 331-336.If have any one light-emitting device to burn (perhaps being open-circuit condition), analysis can detect open-circuit condition with decision circuitry 360 and it is removed from the option of selecting circuit 350.Therefore, can avoid whole system and assembly thereof to be damaged.
The above only is the present invention's preferred embodiment, and all equalizations of being done according to the present patent application claim change and modify, and all should belong to the present invention's covering scope.
The primary clustering symbol description
100,200,300,500,600 drive circuits
110,210,310 voltage conversion circuits
120,221-226,321-326 light-emitting device
140,240 light emitting diodes
130,231-236,331-336 decide current supply
112,212,312,362 first input ends
114,214,314,364 second inputs
116,216,316 outputs
The V-IN input voltage
FB awards signal
The VDD driving voltage
Ic, I1-I6, I11-I66 decide electric current
Vf, Vf1-Vf6 forward bias voltage
Vdrop, Vdrop1-Vdrop6 voltage level
VN minimum voltage position standard
250,350 select circuit
360 analyze and decision circuitry
The 381-386 detector of opening a way
370 control logics
SW1-SW6,640 switches
The Sd1-Sd6 detection signal
Ss1-Ss6 switch controlling signal
COMP2 second comparator
Sc2 second is signal relatively
Vref2 second reference voltage
COMP1 first comparator
Sc1 first is signal relatively
Vref1 first reference voltage
318 voltage conversion units
R1 first resistance
R2 second resistance
The So output signal
VM dividing potential drop driving voltage
720 start delayers
730 or the door
800 flow processs
The 8002-8024 step
Claims (19)
1. one kind can provide the drive circuit of back coupling control with open-circuit-protection, and this drive circuit includes:
At least one light-emitting device;
One voltage conversion circuit is coupled to this light-emitting device, is used to provide a driving voltage to drive this light-emitting device;
One analyzes and decision circuitry, is coupled to this light-emitting device, is used for judging whether this light-emitting device is that open circuit is to produce a judged result;
At least one switch, it has output, one second end and the control end that one first end is coupled to this light-emitting device and is coupled to this analysis and decision circuitry, this open relation is controlled its open and close according to this judged result, whether exports one of the output voltage level of this light-emitting device with decision; And
One selects circuit, be coupled between this second end and this voltage conversion circuit of this analysis and decision circuitry, this switch, use from selecting a minimum voltage position standard in the received voltage level, and feedback signal to produce one according to selected this minimum voltage position standard that goes out, and should feedback signal and be sent to this voltage conversion circuit, wherein this voltage conversion circuit is adjusted this driving voltage according to this back coupling signal.
2. drive circuit according to claim 1, wherein this light-emitting device comprises at least one light-emitting diode.
3. drive circuit according to claim 1, wherein this voltage conversion circuit includes:
One first comparator is used for this back coupling signal and one first reference voltage are compared to export one first comparison signal; And
One voltage conversion unit is coupled to this first comparator, and this voltage conversion unit system is used for adjusting this driving voltage according to this first comparison signal.
4. as the drive circuit as described in the claim 3, wherein:
Feedback signal system during greater than this first reference voltage when this, and this first comparison signal that this first comparator is exported can be controlled this voltage conversion unit to reduce this driving voltage; And
Feedback signal system during less than this first reference voltage when this, and this first comparison signal that this first comparator is exported can be controlled this voltage conversion unit to increase this driving voltage.
5. drive circuit according to claim 1, wherein this drive circuit comprises in addition:
One first resistance is coupled to the output of this voltage conversion circuit; And
One second resistance is coupled to this first resistance in the mode of connecting;
Wherein, this first resistance and this second resistance system is used for this driving voltage is carried out dividing potential drop to produce a dividing potential drop driving voltage.
6. as the drive circuit as described in the claim 5, wherein this analysis and decision circuitry comprise:
One second comparator, it has the contact that a first input end is coupled to this first resistance and this second resistance, be used for receiving this dividing potential drop driving voltage, and one second input be used for receiving one second reference voltage, this second comparator system is used for this dividing potential drop driving voltage and this second reference voltage are compared to produce one second comparison signal;
At least one open circuit detector, this open circuit detector have an input and are coupled to this light-emitting device, and an output is used for exporting a detection signal, and this open circuit detector system is used for detecting one of this light-emitting device state; And
One control logic is coupled to the output of this second comparator and the output of this open circuit detector, this control logic system be used for according to this second relatively signal and this detection signal to produce this judged result.
7. as the drive circuit as described in the claim 6, wherein this second comparator is a hysteresis comparator.
8. as the drive circuit as described in the claim 6, wherein:
When this dividing potential drop driving voltage system during less than this second reference voltage, this second comparator export this second relatively signal can control this switch of unlatching; And
When this dividing potential drop driving voltage system was detected as open circuit greater than the state of this second reference voltage and this light-emitting device, this second comparison signal that this second comparator is exported can be controlled and close this corresponding switch.
9. as the drive circuit as described in the claim 7, wherein:
When the state of each light-emitting device all was detected as open circuit, this control logic can will should be feedback the signal strangulation in a fixed voltage position standard.
10. as the drive circuit as described in the claim 9, wherein the accurate system in this fixed voltage position comprises the voltage level of this driving voltage or this dividing potential drop driving voltage.
11. one kind can provide the driving method of back coupling control with open-circuit-protection, this driving method comprises:
Provide a driving voltage to drive at least one light-emitting device;
Judge whether this light-emitting device is that open circuit is to produce a judged result;
Control the open and close of at least one switch according to this judged result, whether export one of the output voltage level of this light-emitting device with decision;
In received voltage level, select a minimum voltage position standard, and feedback signal to produce one according to selected this minimum voltage position standard that goes out; And
Adjust this driving voltage according to this back coupling signal.
12. as the driving method as described in the claim 11, wherein this light-emitting device comprises at least one light-emitting diode.
13. as the driving method as described in the claim 11, wherein the step system that adjusts this driving voltage according to this back coupling signal comprises:
Should feedback signal and one first reference voltage compares to produce one first signal relatively; And
Adjust this driving voltage according to this first comparison signal.
14., wherein should feedback the step that signal and this first reference voltage compare to adjust this driving voltage to comprise in addition as the driving method as described in the claim 13:
Feedback signal system during greater than this first reference voltage when this, reduce this driving voltage; And
Feedback signal system during less than this first reference voltage when this, increase this driving voltage.
15. as the driving method as described in the claim 11, it comprises in addition:
This driving voltage is carried out dividing potential drop to produce a dividing potential drop driving voltage.
16. as the driving method as described in the claim 15, it comprises in addition:
This dividing potential drop driving voltage and one second reference voltage are compared, compare signal to produce one second;
Detect the state of this light-emitting device, to export a detection signal; And
Produce this judged result according to this second comparison signal and this detection signal.
17. as the driving method as described in the claim 16, wherein according to this second relatively signal and this detection signal step that produces this judged result comprise:
When this dividing potential drop driving voltage system during, open at least one switch corresponding to this light-emitting device less than this second reference voltage; And
When this dividing potential drop driving voltage system is detected as open circuit greater than the state of this second reference voltage and this light-emitting device, close this corresponding switch of this light-emitting device;
Wherein this switch has output, one second end and the control that one first end is coupled to this light-emitting device and brings in its open and close of control.
18. as the driving method as described in the claim 16, wherein:
When the state of each light-emitting device is detected as open circuit, should feedback the signal strangulation in a fixed voltage position standard.
19. as the driving method as described in the claim 18, wherein the accurate system in this fixed voltage position comprises the voltage level of this driving voltage or this dividing potential drop driving voltage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US87041006P | 2006-12-18 | 2006-12-18 | |
| US60/870,410 | 2006-12-18 |
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| CN101207958A CN101207958A (en) | 2008-06-25 |
| CN101207958B true CN101207958B (en) | 2011-06-29 |
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| TW (1) | TWI325285B (en) |
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| CN101562933B (en) * | 2009-05-04 | 2012-09-05 | 深圳华映显示科技有限公司 | Driving circuit of backlight module |
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| TW200829083A (en) | 2008-07-01 |
| CN101207958A (en) | 2008-06-25 |
| TWI325285B (en) | 2010-05-21 |
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