CN103957643B - Driving device of light emitting diode and driving method thereof - Google Patents
Driving device of light emitting diode and driving method thereof Download PDFInfo
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- CN103957643B CN103957643B CN201410203222.3A CN201410203222A CN103957643B CN 103957643 B CN103957643 B CN 103957643B CN 201410203222 A CN201410203222 A CN 201410203222A CN 103957643 B CN103957643 B CN 103957643B
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Abstract
The invention discloses a driving device of a light emitting diode and a driving method thereof. In the driving method, it is detected whether the driving device performs dimming or not. If detected that the driving device performs dimming, it is judged whether the duty factor of a dimming signal is smaller than a preset value or not. When the duty factor of the dimming signal is larger than the preset value, multiple driving currents are adjusted and output within a period, and the output time of the driving currents is equal to the period. When the duty factor of the dimming signal is smaller than the preset value, the driving currents are respectively output within the period, and the output time of the driving currents is smaller than the period. Therefore, voice frequency noise and electromagnetic interference caused by overlarge sum variation of the driving currents can be inhibited.
Description
Technical field
The present invention relates to a kind of driving method, and driving means and its driving side of more particularly to a kind of light emitting diode
Method.
Background technology
Light emitting diode (Light Emitting Diode, hereinafter referred to as：LED small volume), power saving and durable, and
With the maturation of processing procedure, prices are recently more and more universal as the product of light source with light emitting diode.Additionally, luminous two
Pole pipe operating voltage low (only 1.5-3V), can actively light and have certain brightness, brightness voltage available or electric current are adjusted, while tool
The characteristics of standby impact resistance, anti-vibration, life-span length (100,000 hours), so, light emitting diode is extensive in various terminal equipment
Use, from car headlamp, traffic lights, indicator by character, billboard and big screen video display, shine to common and building
Bright and liquid crystal display (Liquid Crystal Display, hereinafter referred to as:LCD) the field such as backlight.
For with light emitting diode drive device, one of conventional dimming mode is using PM (pulse-width
Modulation, hereinafter referred to as：PWM) the duty factor (duty) of technological adjustment pulse, adjusts output stage and exports to luminous with this
The equivalent current of diode is adjusting light-emitting diode luminance.However, when being dimmed using PM, its output stage is defeated
The current switching action for going out is as switch.And this current switching action can greatly be taken out load and be become to the voltage of output stage
Change, cause voltage to have the generation of excessive ripple (ripple).Meanwhile, excessive ripple can be caused greatly to the inductance in circuit
Changes of magnetic field, and electric capacity in circuit can cause tempestuously to vibrate (sharply because the voltage change of moment is excessive
Vibrate) deformation (shape-changing) is produced, therefore and produces audio-frequency noise (audio noise).
Figure 1A is the system schematic of the driving means of a conventional light emitting diodes.Figure 1A is refer to, in driving means 100
Driven including electric pressure converter 110, conversing circuits controller 120, amplifier 130, voltage selector 140 and by a plurality of electric currents
The current driver unit 150 that element is constituted.Electric pressure converter 110 receives supply voltage VDD, and electric pressure converter 110 according to turn
Change output generation and the supply voltage V of loop control unit 120DDOperating voltage V of different levelsCC.The positive input of amplifier 130
End receives reference voltage Vref, and the voltage that its negative input end receiving voltage selector 140 is exported, and according to this output voltage with
Control conversing circuits controller 120, wherein reference voltage Vref are a fixed value.Voltage selector 140 is sent out to select output
The voltage of optical diode tandem 50_1～50_n negative pole ends therein.The positive pole termination of LED serial 50_1～50_n
Receive operating voltage VCC, the negative pole end pole of LED serial 50_1～50_n drives list by switch S1～Sn with electric current respectively
Unit 150 couples, and by load current i1～inLED serial 50_1～50_n is driven to light, and it is same to switch S1～Sn
When the switching that switched according to dim signal, the action dimmed with this.
Figure 1B is the sequential chart of the driving current of Figure 1A.Figure 1A and Figure 1B is refer to, in light emitting diode drive device 100
In, conventional PM technology supplies load current i to adjust1～inTime t1To adjust the luminous bright of light emitting diode
Degree.In other words, in fixed cycle T, time t1The brightness of more long then light emitting diode can be higher；Conversely, time t1More it is short then
The brightness of light emitting diode can be lower.However, when being dimmed using PM, the switching action for switching S1～Sn is made
Into load current i1～inChange.Above-mentioned load current i1～inChange can make operating voltage VCCHaving greatly take out load
Change, operating voltage V for causing electric pressure converter 110 to exportCCHave the generation of excessive ripple.Meanwhile, electric pressure converter 110 is defeated
Enter electric current and also have great instantaneous variation, except the inductance allowed in electric pressure converter 110 causes great changes of magnetic field, also allow
Electric capacity of voltage regulation in electric pressure converter 110 tempestuously vibrates and produces deformation because transient voltage change is excessive, therefore and produces
Raw audio-frequency noise.Additionally, for driving means 100, when being dimmed, its switch S1～Sn can be switched over simultaneously, with
Make load current i simultaneously1～inSwitching action, and current switching action can cause serious electromagnetic interference
(Electromagnetic Disturbance, hereinafter referred to as：EMI).
The content of the invention
The present invention provides a kind of Drive And Its Driving Method of light emitting diode, can suppress audio-frequency noise and electromagnetism
Interference.
The present invention proposes a kind of driving method of light emitting diode, it is adaptable to a driving means.This driving method includes：Detect
Survey whether driving means are dimmed；If driving means are detected being dimmed, judging the duty factor of a dim signal is
It is no to be less than a preset value；When the duty factor of dim signal is more than or equal to preset value, the electric current for adjusting multiple driving currents is big
It is little, and these driving currents are exported in a cycle, wherein the output time of these driving currents is equal to the cycle；And, when
When the duty factor of dim signal is less than preset value, these driving currents, wherein these driving currents are exported in the cycle respectively
Output time be less than the cycle.
The present invention proposes a kind of driving method of light emitting diode, it is adaptable to a driving means.Driving method includes：Receive
One dim signal；Whether detecting driving means are dimmed；And, if driving means are detected being dimmed, according to light modulation
One duty factor of signal adjusts an other size of current in multiple driving currents, so that these driving currents in the cycle total
With the duty factor for being proportional to dim signal.
The present invention proposes a kind of drive circuit to drive multiple light emitting diodes, including multiple switch, and a light modulation is detectd
Survey device, and a current control unit.These switches are to couple these light emitting diodes.Light modulation detector is to receive a tune
Optical signal and foundation dim signal export a light-modulating mode signal.Current control unit is to according to light-modulating mode signal and light modulation
Signal output multiple control signal, wherein these control signals control respectively the conducting state of these switches.
Based on above-mentioned, the Drive And Its Driving Method of the light emitting diode of the present invention, when driving means are dimmed
And the duty factor of dim signal be less than preset value when, then evenly distribute output time of each driving current in a cycle, and
Accordingly adjust the size of current of each driving current.When driving means dimmed and dim signal duty factor be more than or wait
When preset value, the simultaneously output driving current in the cycle, and adjust the size of driving current according to dim signal.Thereby, may be used
The summation for suppressing driving current changes excessive caused audio-frequency noise and electromagnetic interference.
It is that the features described above and advantage of the present invention can be become apparent, special embodiment below, and it is detailed to coordinate accompanying drawing to make
Carefully it is described as follows.
Description of the drawings
Figure 1A is the system schematic of the driving means of a conventional light emitting diodes.
Figure 1B is the sequential chart of the driving current of Figure 1A.
Fig. 2A is the circuit diagram of the driving means of one embodiment of the invention.
Fig. 2 B are the current waveform schematic diagram of the LED serial of Fig. 2A.
Fig. 2 C are another current waveform schematic diagram of the LED serial of Fig. 2A.
Fig. 2 D are the driving means of Fig. 2A and the waveform diagram of LED serial.
Fig. 2 E dim the circuit diagram of detector for the current control unit coupling of Fig. 2A.
Fig. 2 F turn the circuit diagram of electric pressure converter for the duty factor of Fig. 2 E.
Fig. 2 G turn another circuit diagram of electric pressure converter for the duty factor of Fig. 2 E.
Fig. 2 H dim another circuit diagram of detector for the current control unit coupling of Fig. 2A.
Fig. 2 I dim another circuit diagram of detector for the current control unit coupling of Fig. 2A.
Fig. 3 A are the flow chart of the driving method of one embodiment of the invention.
Fig. 3 B are the flow chart of the driving method of another embodiment of the present invention.
Main element symbol description：
50_1～50_n：LED serial 100,200：Driving means
110、210：Electric pressure converter 120,220：Conversing circuits controller
130、230：Amplifier 140,240：Voltage selector
150、250：Current driver unit 260：Light modulation detector
261：Analog-digital converter 262：OR gate
270：Current control unit 271, mux1：Multiplexer
272、274、275：Dispersion delay cell 273,276：Duty factor turns electric pressure converter
D：Size of current S1～Sn, SW1～SWn：Switch
Scol：Control signal Smod：Light-modulating mode signal
Sdim：Dim signal t1、t2：Time
T：Cycle GN：Gain signal
i1～in：Load current VR：Reference voltage
VDD：Supply voltage VCC：Operating voltage
Vref：Reference voltage I1～In：Driving current
Vcol：Control voltage LPF1, LPF2：Low-pass filter circuit
R1、R2：Resistance C1, C2：Electric capacity
ML1：Analog multiplier S301, S302, S311～S313：According to this
The step of inventing the driving method of all embodiments
Specific embodiment
Fig. 2A is the circuit diagram of the driving means of one embodiment of the invention.Fig. 2A is refer to, driving means 200 include
Electric pressure converter 210, conversing circuits controller 220, amplifier 230, voltage selector 240, current driver unit 250, light modulation
Detector 260, current control unit 270 and switch SW1～SWn.Light modulation detector 260 receives dim signal Sdim, with foundation
Whether dim signal Sdim detectings driving means 200 carry out dimming and exporting accordingly light-modulating mode signal Smod.Current control list
Unit 270 exports multiple control signal Scol and control voltage Vcol according to light-modulating mode signal Smod and dim signal Sdim, with
Whether turned on using these control signals Scol difference controlling switch SW1～SWn, and by control voltage Vcol control electric current
Driver element 250 adjusts driving current I1～InSize.
Electric pressure converter 210 receives supply voltage VDD, and according to the adjustment signal generation of the output of conversing circuits controller 220
With supply voltage VDDOperating voltage V of different levelsCC.Conversing circuits controller 220 produces adjustment according to its voltage for being received
Signal.The positive input terminal of amplifier 230 receives reference voltage VR, and its negative input end receiving voltage selector 240 exported
Voltage, and according to this output voltage can be a fixed value to conversing circuits controller 220, wherein reference voltage Vref.Voltage is selected
Device 240 is selected to select the voltage of output light emitting diode tandem 50_1～50_n negative pole ends therein.Light emitting diode string
The positive terminal of row 50_1～50_n receives operating voltage VCC, the negative pole end pole of LED serial 50_1～50_n passes through respectively
Switch SW1～SWn is coupled with current driver unit 250, and by driving current I1～InDriving LED serial 50_1～
50_n lights.
When the duty factor of dim signal Sdim is 100%, representing driving means 200 will not be dimmed.Now, electricity
Flow control unit 270 can be according to light-modulating mode signal Smod generation control signal Scol controlling switch SW1～SWn in a cycle
Simultaneously turn on, and by control voltage Vcol adjustment control driving current I1～InSize of current D be current upper limit value.Work as tune
When the duty factor of optical signal Sdim is not 100%, representing driving means 200 can be dimmed.Now, current control unit
270 also according to light-modulating mode signal Smod produce control signal Scol with controlling switch SW1～SWn leading in a cycle
The logical time is equal or equalization, and adjusts driving current I by control voltage Vcol control electric current driver element 2501～InIt is big
Little, wherein current driver unit 250 can be made up of multiple voltage-controlled current sources, with simultaneously according to the adjustment drive of control voltage Vcol
Streaming current I1～InSize.It is noted that whether the duty factor of dim signal Sdim is adjusted with driving means 200
The relation of light is to illustrate, and visual actual demand and change.
The action that driving means 200 are dimmed is further illustrated, Fig. 2 B are the electricity of the LED serial of Fig. 2A
Stream waveform diagram.Fig. 2A and Fig. 2 B are refer to, when driving means 200 are dimmed and the duty factor of dim signal Sdim is big
When equal to preset value, current control unit 270 produces multiple according to light-modulating mode signal Smod and light-modulating mode signal Sdim
Control signal Scol and control voltage Vcol.These control signals Scol meeting controlling switch SW1～SWn is protected simultaneously in cycle T
Conducting is held, to provide driving current I simultaneously1～InTo LED serial 50_1～50_n.LED serial 50_1～
Electric current on 50_n can be because switch SW1～SWn be held on and direct current shape rather than pulse type is presented.Also, electric current drives single
Unit 250 adjusts driving current I according to control voltage Vcol1～InSize of current D, the wherein meeting of size of current D and dim signal
The duty factor of Sdim is related, and such as duty factor is 1/8, then size of current D can be equal to the 1/8 of current upper limit value.And it is above-mentioned
Preset value can be cycle T divided by driving current I1～InNumber n, number n of such as driving current is 8, then preset value is week
1/8 (i.e. the T/8) of phase.
Fig. 2 C are another current waveform schematic diagram of the LED serial of Fig. 2A.Fig. 2A and Fig. 2 C are refer to, works as drive
Dynamic device 200 dimmed and dim signal Sdim duty factor be less than preset value when, current control unit 270 also according to
Light-modulating mode signal Smod and dim signal Sdim produces multiple control signal Scol and control voltage Vcol.These control signals
Scol can ON time ts of the controlling switch SW1～SWn in cycle T2For equalization, with output driving current I respectively1～InExtremely send out
The quantity of optical diode tandem 50_1～50_n, such as switch is 8, then ON time t2For 1/8 cycle.Current driver unit
250 adjust driving current I according to control voltage Vcol1～InSize of current D, wherein size of current D can be with dim signal Sdim
Duty factor and preset value it is related, such as duty factor is 1/16, then size of current D can be equal to the 1/2 of current upper limit value, also
I.e. duty factor (i.e. 1/16) is multiplied by again current upper limit value divided by preset value (i.e. 1/8).And driving current I1～InOutput order
Can sequentially or random sequence.
Thereby, no matter switch SW1～SWn is simultaneously turned on according to the duty factor of light-modulating mode signal Sdim in cycle T
Or be respectively turned on, its driving current I1～InElectric current summation can generally be held in certain value, operating voltage V is greatly reducedCC
Take out load change, even except disappearing, to suppress the audio-frequency noise and the electromagnetic interference that therefore produce.
Fig. 2 D are the driving means of Fig. 2A and the waveform diagram of LED serial.Fig. 2A and Fig. 2 D are refer to,
In the present embodiment, it is assumed that driving means 200 drive LED serial 50_1 and 50_2, and received light modulation letter
The duty factor of number Sdim is 1/4.Now, switch SW1 and SW2 be controlled by received control signal Scol be respectively turned on and
ON time is respectively T/2.Also, current driver unit 250 is controlled by control voltage Vcol adjustment driving current I1～InElectricity
Stream size D is the half (i.e. 1/2) of current upper limit value H, and wherein current upper limit value H can be corresponded to the high level V of voltage signal.Mat
This, driving means 200 are capable of achieving 1/4 dimming effect, and size of current D can substantially be maintained at the 1/2 of current upper limit value H, with
Suppress audio-frequency noise and the electromagnetic interference for therefore producing.
Fig. 2 E dim the circuit diagram of detector for the current control unit coupling of Fig. 2A.Fig. 2 E are refer to, in this reality
In applying example, current control unit 270 includes that multiplexer 271, dispersion delay cell 272 and duty factor turn electric pressure converter
273.When driving means 200 dimmed and dim signal Sdim duty factor be more than or equal to preset value when, dim detector
260 light-modulating mode signal Smod can control multiplexer 271 be inputted the received dim signal Sdim in end by its
One output end is exported to duty factor and turns electric pressure converter 273, with according to the duty factor of dim signal Sdim adjustment control electricity
The size of pressure Vcol.Current driver unit 250 is then according to size synchronous adjustment driving current I of control voltage Vcol1～InElectricity
Stream size.Simultaneously as dispersion delay cell 272 does not receive dim signal Sdim, so the control of dispersion delay cell 272
Signal Scol can controlling switch SW1～SWn simultaneously turn on, to allow driving current I1～InExport to LED serial simultaneously
50_1～50_n.
When driving means 200 dimmed and dim signal Sdim duty factor be less than preset value when, dim detector
260 light-modulating mode signal Smod can control multiplexer 271 be inputted the received dim signal Sdim in end by its
Two output ends are exported to dispersion delay cell 272.Dispersion delay cell 272 after dim signal Sdim is received, its produce
Control signal Scol meeting controlling switch SW1～SWn can be respectively turned in a cycle, and switch the ON time of SW1～SWn
Can be identical.In general, these control signals Scol can in difference transfer pulse so that switch SW1～SWn in difference
When turn on.And but the ON time for switching SW1～SWn can separate mutually continue, that is, the pulse of conducting switch can be at this
A little corresponding end points of control signal Scol are continued output, and the effect of this output that continues by pulse as carrying out displacement.
Wherein, the function of pulse displacement can be completed by displacement buffer, that is, these control signals Scol are passed in difference
Sending the function of pulse can carry out displacement to pulse and export completing by multiple displacement buffers.
Meanwhile, received dim signal Sdim can be sent to duty factor and turn voltage conversion by dispersion delay cell 272
Device 273, and while export a gain signal GN turns electric pressure converter 273 to duty factor.Duty factor turns electric pressure converter
273 sizes that control voltage Vcol is adjusted according to the duty factor and gain signal GN of dim signal Sdim, with synchronous adjustment drive
Streaming current I1～InSize of current.Wherein, gain signal GN can transmit gain number, and gain signal GN transmits gain number can
Think driving current I1～InElectric current number, driving current I1～InElectric current number as a example by 8, then gain signal GN transmits increasing
Beneficial number is 8.For example, when the duty factor of dim signal Sdim is 1/16, driving current I1～InSize of current should
For the 1/16 of current upper limit value, but again according to gain signal GN adjustment after, driving current I1～InSize of current be adjusted to electricity
The 1/2 of stream higher limit, then coordinate driving current I1～InOutput time for the cycle 1/8, can reach 1/16 dimming effect.
It is noted that dispersion delay cell 272 is not when dim signal Sdim is received, it can be with output gain number
Gain signal GN for 1 or not output gain signal GN.Additionally, duty factor turns electric pressure converter 273 is not receiving gain
During signal GN, then corresponding control voltage Vcol is produced according to the duty factor of dim signal Sdim.
Fig. 2 F turn the circuit diagram of electric pressure converter for the duty factor of Fig. 2 E.Fig. 2 F are refer to, in the present embodiment,
Duty factor turns electric pressure converter 273 including low-pass filter circuit LPF1 and analog multiplier ML1, wherein low-pass filter circuit
LPF1 can be made up of resistance R1 and electric capacity C1, but with this not limit other embodiment.Low-pass filter circuit LPF1 can be by institute
The dim signal Sdim of reception is converted to a DC level, that is, low-pass filter circuit LPF1 can accounting for according to dim signal Sdim
The difference of empty factor exports different DC levels.Analog multiplier ML1 can be according to gain signal GN amplification low pass circuits
The DC level of LPF1 outputs is used as control voltage Vcol.When the gain number that gain signal GN is transmitted is 1, then control voltage
The level of Vcol can be same as the DC level of low-pass filter circuit LPF1 outputs.When the gain number that gain signal GN is transmitted is
When 2, then the DC level that level 2 times of low-pass filter circuit LPF1 of meeting of control voltage Vcol are exported, remaining is then by that analogy.
Fig. 2 G turn another circuit diagram of electric pressure converter for the duty factor of Fig. 2 E.Fig. 2 F and Fig. 2 G are refer to, its
Difference is multiplexer mux1.Multiplexer mux1 can determine LPF electricity according to light-modulating mode signal Smod
The DC level of road LPF1 outputs is exported to be sent to analog multiplier ML1 or direct.In other words, when driving means 200 are carried out
When the duty factor of light modulation and dim signal Sdim is more than or equal to preset value, can directly export low-pass filter circuit LPF1 and be exported
DC level as control voltage Vcol.When driving means 200 are dimmed and the duty factor of dim signal Sdim is less than
During preset value, the DC level of low-pass filter circuit LPF1 outputs is to be sent to analog multiplier ML1, with according to gain signal GN
Export as control voltage Vcol after amplification.
Fig. 2 H dim another circuit diagram of detector for the current control unit coupling of Fig. 2A.Refer to Fig. 2 E, figure
2H, its difference is dispersion delay cell 274, and omits multiplexer 271.When driving means 200 are dimmed
And the duty factor of dim signal Sdim, when being more than or equal to preset value, dispersion delay cell 274 can be according to light-modulating mode signal
The control signal Scol meeting controlling switch SW1～SWn of Smod is simultaneously turned on, and will not output gain signal GN or output gain
Number is 1 gain signal GN.In the case of dispersion delay cell 274 not output gain signal GN, duty factor turns voltage and turns
Parallel operation 273 can produce control voltage Vcol according to received dim signal Sdim.In the dispersion output gain of delay cell 274
In the case that number is 1 gain signal GN, duty factor turns electric pressure converter 273 can be according to received dim signal Sdim
And gain signal GN produces control voltage Vcol.
When driving means 200 are dimmed and the duty factor of dim signal Sdim is less than preset value, dispersion postpones single
Corresponding control signal Scol of the meeting foundation light-modulating mode signal Smod generations of unit 272 is with controlling switch SW1～SWn in a cycle
Can be respectively turned on, and export correspondence driving current I1～InElectric current number gain signal GN.Duty factor turns electric pressure converter
273 can produce control voltage Vcol according to received dim signal Sdim and gain signal GN.
Fig. 2 I dim another circuit diagram of detector for the current control unit coupling of Fig. 2A.Fig. 2 I are refer to, this
Driving current I of embodiment1～InElectric current number as a example by 8, that is, preset value be 1/8.Light modulation detector 260 includes low pass
Filter circuit LPF2, analog-digital converter 261 (analog-to-digital converter, hereinafter referred to as：ADC) with or
Door 262, wherein analog-digital converter 261 is by taking the converter of 4 bits as an example.If the duty factor of dim signal Sdim is 1/4
When, then analog-digital converter 261 can export " 0100 ", show to be exactly " 01000000 " with digital kenel.Preset value is with numeral
Kenel shows to be exactly " 00100000 ".
According to above-mentioned, if there is " 1 " and is more than in preset value in here first three highest bit, therefore can be by first three
Highest bit with or computing produce light-modulating mode signal Smod.And analog-digital converter 261 output " 01000000 " Jing or
After door 262 is to first three highest order n ary operation, the light-modulating mode signal Smod of high logic level can be produced, represent dim signal
The duty factor of Sdim is more than preset value.Then, multiplexer 271 according to light-modulating mode signal Smod by Analog-digital Converter
" 01000000 " of the output of device 261 exports to duty factor and turns electric pressure converter 276, and " 01000000 " of digital kenel is turned
The output of simulation kenel is changed to so that used as control voltage Vcol, wherein duty factor turns electric pressure converter 276 can include digital mould
Plan converter (digital-to-analog converter, hereinafter referred to as：DAC) with by digital kenel " 01000000 " conversion
To simulate kenel.Also, disperse delay cell 275 when the output of analog-digital converter 261 is not received, then correspond to and produce
Multiple control signal Scol is simultaneously turned on controlling switch SW1～SWn.
If the duty factor of dim signal Sdim is 1/16, analog-digital converter 261 can export " 00010000 ",
And or lock 262 first three highest bit is carried out after computing, the light-modulating mode signal Smod of low logic level can be produced.Then,
Multiplexer 271 exports " 00010000 " that analog-digital converter 261 is exported to accounting for according to light-modulating mode signal Smod
Empty factor turns electric pressure converter 276.Now, disperse delay cell 275 then to correspond to produce multiple control signal Scol to control out
Closing SW1～SWn can be respectively turned in a cycle.Also, disperse delay cell 275 to adjust Analog-digital Converter according to preset value
Device 261 output " 00010000 ", also will " 00010000 " be multiplied by 8 (equivalent moves to left three bits) and become
“10000000”.Using this " 10000000 " output as gain signal, then duty factor turn electric pressure converter 276 will
" 10000000 " are converted to simulation kenel and export as control voltage Vcol.It should be noted that in the present embodiment, duty because
Several electric pressure converters 276 that turn can not receive dim signal Sdim, to simplify the degree of difficulty of circuit design.
According to described above, it is method being applied to driving means 200 that can converge above-mentioned action whole.Fig. 3 A are according to this
Invent the flow chart of the driving method of an embodiment.Fig. 2A and Fig. 3 A are refer to, driving means 200 can receive dim signal
Sdim, can detect whether driving means 200 are being dimmed (step S301) according to dim signal Sdim.When driving means 200
When being dimmed, then driving current I is evenly distributed1～InOutput time (step S302) in a cycle, and drive dress
Putting 200 can output driving current I1～InTo drive LED serial 50_1～50_n respectively.When driving means 200 do not exist
When being dimmed, then terminate this driving method.
Fig. 3 B are the flow chart of the driving method of another embodiment of the present invention.Refer to Fig. 3 A and Fig. 3 B, its difference
It is step S311, S312 and S313.When driving means are when being dimmed, then judge whether the duty factor of dim signal is little
In preset value (step S311).When the duty factor of dim signal is not less than preset value, then exports simultaneously in a cycle and drive
Streaming current, and adjust the size of current (step S312) of driving current according to dim signal.When the duty factor of dim signal it is little
When preset value, then output time of the driving current in a cycle is evenly distributed, and accordingly adjust the electric current of driving current
Size (step S313).Wherein, step 312 and 313 explanations that can refer to above-described embodiment, are not then repeated here at this.
In sum, the Drive And Its Driving Method of the light emitting diode of all embodiments of the invention, works as driving means
Dimmed and dim signal duty factor be less than preset value when, then evenly distribute output of each driving current in a cycle
Time, and accordingly adjust the size of current of each driving current.When driving means dimmed and dim signal duty factor
During more than or equal to preset value, the simultaneously output driving current in the cycle, and adjust the size of driving current according to dim signal.
Thereby, the summation that can suppress driving current changes excessive caused audio-frequency noise and electromagnetic interference.
Finally it should be noted that：Above example only to illustrate technical scheme rather than be limited,
Although being described in detail to the present invention with reference to preferred embodiment, it will be understood by those within the art that：Its according to
So technical scheme can be modified or equivalent, and these modifications or equivalent also can not make to repair
Technical scheme after changing departs from the spirit and scope of technical solution of the present invention.
Claims (20)
1. a kind of driving method of light emitting diode a, it is adaptable to driving means, it is characterised in that the driving method includes：
Detect whether the driving means are dimmed；
If the driving means are detected being dimmed, judge the duty factor of a dim signal whether less than a preset value；
When the duty factor of the dim signal is more than or equal to the preset value, the size of current of multiple driving currents is adjusted, and
And those driving currents are exported in a cycle, the wherein output time of those driving currents is equal to the cycle；And
When the duty factor of the dim signal is less than the preset value, output in the difference time period different in this period should
A little driving currents, the wherein output time of those driving currents are less than the cycle.
2. the driving method of light emitting diode according to claim 1, it is characterised in that further include：
When the duty factor of the dim signal is more than or equal to the preset value, according to the dim signal those driving currents are adjusted
Other size of current.
3. the driving method of light emitting diode according to claim 2, it is characterised in that when the dim signal duty because
When number is more than or equal to the preset value, according to the duty factor of the dim signal other size of current of whole those driving currents.
4. the driving method of light emitting diode according to claim 1, it is characterised in that further include：
When the duty factor of the dim signal is less than the preset value, those driving currents are set according to the dim signal other
Size of current and in this period individual other output time.
5. the driving method of light emitting diode according to claim 4, it is characterised in that when the duty of the dim signal
Factor is less than the preset value, according to the duty factor of the dim signal arrange those driving currents other size of current and
Other output time in the cycle.
6. the driving method of light emitting diode according to claim 1, it is characterised in that further include：
No matter whether the output time of those driving currents is equal to the cycle, when the dim signal is identical duty factor,
Those driving currents summation in this period is a fixed value.
7. a kind of driving method of light emitting diode a, it is adaptable to driving means, it is characterised in that the driving method includes：
Receive a dim signal；
Detect whether the driving means are dimmed；And
If the driving means are detected being dimmed, adjust in multiple driving currents according to a duty factor of the dim signal
Individual other size of current, so that summation of those driving currents in a cycle is proportional to the duty factor of the dim signal,
Wherein when the duty factor of the dim signal is not less than a preset value, the size of current of those driving currents is electric equal to one
Stream higher limit is multiplied by the duty factor, when the duty factor of the dim signal is less than the preset value, those driving currents
Size of current be equal to the current upper limit value and be multiplied by after the number of the duty factor and those driving currents again divided by the cycle.
8. the driving method of light emitting diode according to claim 7, it is characterised in that if the driving means are detected
Dimmed, according to the duty factor of the dim signal the size of current and output time of those driving currents are adjusted.
9. the driving method of light emitting diode according to claim 7, it is characterised in that if the driving means are detected
Dimmed, the output time of those driving currents is equal to the cycle, or the output time of those driving currents is less than this week
Phase.
10. the driving method of light emitting diode according to claim 9, it is characterised in that when this of the dim signal is accounted for
When empty factor is not less than a preset value, the output time of those driving currents is equal to the cycle, when the duty of the dim signal
When factor is less than the preset value, the output time of those driving currents is less than the cycle.
The driving method of 11. light emitting diodes according to claim 9, it is characterised in that in the dim signal for identical
During duty factor, no matter those drive the output time of electricity to be less than or equal to the cycle, those driving currents are in this period
Summation is maintained at a fixed value.
12. a kind of drive circuits to drive multiple light emitting diodes, it is characterised in that include：
Multiple switch, to couple those light emitting diodes；
One light modulation detector, to receive a dim signal and export a light-modulating mode signal according to the dim signal；
One current control unit, according to the light-modulating mode signal and the dim signal output multiple control signal, wherein should
A little control signals control respectively those conducting states of the switch in a cycle；And
One current driver unit, couples those switches and the current control unit, and the current control unit is more according to the tune
Optical mode signal and the dim signal export a control voltage, and the wherein control voltage controls the current driver unit and adjusts multiple
Driving current to drive those light emitting diodes, and when the duty factor of the dim signal is not less than a preset value, those
The size of current of driving current is multiplied by the duty factor equal to a current upper limit value, when the duty factor of the dim signal it is little
When the preset value, the size of current of those driving currents is multiplied by the duty factor and drives with those equal to the current upper limit value
Again divided by the cycle after the number of electric current.
13. drive circuits according to claim 12, it is characterised in that the light modulation detector is according to the dim signal detecting
Whether light modulation is carried out, and exports light-modulating mode signal according to detecting result.
14. drive circuits according to claim 13, it is characterised in that the light modulation detector is detected according to the dim signal
Duty factor detecting light modulation whether carry out.
15. drive circuits according to claim 13, it is characterised in that the light modulation detector more exports the light-modulating mode letter
Number to the current control unit, and whether the duty factor of the dim signal is detected less than a preset value, with by the light modulation
Mode signal arranges the conducting state of those switches.
16. drive circuits according to claim 15, it is characterised in that the light modulation detector detects being somebody's turn to do for the dim signal
Whether duty factor is less than the preset value, and to control the current control unit by the light-modulating mode signal those driving electricity are adjusted
Flow to drive those light emitting diodes.
17. drive circuits according to claim 15, it is characterised in that detecting light modulation in the light modulation detector is carried out
And the duty factor of the dim signal is less than in the case of the preset value, the current control unit export those control signals with
Those switch ON times in this period are controlled for equalization and is divided equally the cycle.
18. drive circuits according to claim 15, it is characterised in that detecting light modulation in the light modulation detector is carried out
And the duty factor of the dim signal, more than or equal in the case of the preset value, the current control unit exports those control letters
Number it is equal to the cycle to control those switch ON times in this period.
19. drive circuits according to claim 16, it is characterised in that detecting light modulation in the light modulation detector is carried out
And the duty factor of the dim signal is less than in the case of the preset value, the current control unit export those control signals with
Each those switches of control are respectively turned in this period.
20. drive circuits according to claim 16, it is characterised in that no matter whether the duty factor of the dim signal
Less than the preset value, those driving currents are adjustment so that those driving currents summation in this period is proportional to the light modulation letter
Number the duty factor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410203222.3A CN103957643B (en) | 2009-09-23 | 2009-09-23 | Driving device of light emitting diode and driving method thereof |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910175152.4A CN102026439B (en) | 2009-09-23 | 2009-09-23 | Driving device and driving method for light emitting diode |
| CN201410203222.3A CN103957643B (en) | 2009-09-23 | 2009-09-23 | Driving device of light emitting diode and driving method thereof |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200910175152.4A Division CN102026439B (en) | 2009-09-23 | 2009-09-23 | Driving device and driving method for light emitting diode |
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| CN103957643A CN103957643A (en) | 2014-07-30 |
| CN103957643B true CN103957643B (en) | 2017-04-12 |
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| CN100553393C (en) * | 2006-11-06 | 2009-10-21 | 台湾类比科技股份有限公司 | The light-dimming method of light-emitting diode |
| JP4943892B2 (en) * | 2007-02-23 | 2012-05-30 | パナソニック株式会社 | Light control device and lighting fixture using the same |
| TW200842781A (en) * | 2007-04-16 | 2008-11-01 | Ze-Ru Lin | Asynchronous driving method and device of LED module |
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