CN101466186A - Drive method and drive device capable of regulating high-power LED lighteness - Google Patents

Drive method and drive device capable of regulating high-power LED lighteness Download PDF

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Publication number
CN101466186A
CN101466186A CNA2008101868641A CN200810186864A CN101466186A CN 101466186 A CN101466186 A CN 101466186A CN A2008101868641 A CNA2008101868641 A CN A2008101868641A CN 200810186864 A CN200810186864 A CN 200810186864A CN 101466186 A CN101466186 A CN 101466186A
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led
brightness
pwm
lighteness
power led
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韦自力
张家瑞
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Abstract

The invention provides a driving method and a device for adjusting LBD brightness with high power; the method can obtain the LBD brightness data through receiving the control information input from the outer side; the current flowing through the LBD can be set through a current adjusting unit connected with the driving unit, the LBD is lighted so as to lead the brightness to reach the target value; or the current flowing through the LBD can be set according to the method, the LBD brightness can be primarily adjusted, and then the signal dutyfactor of the PWM adjusting unit connected with the current adjusting unit in parallel is set, the LBD brightness is further adjusted to finally reach the target value; the LBD can be turned off through setting the dutyfactor of PWM adjusting unit signal to 0%. the technical proposal provided by the invention is utilized to dynamically adjust the LBD brightness in real time, and remarkably improve the EMC (electromagnetic compatibility) property of the device at the same time, and prolong the service life of the LED.

Description

A kind of driving method and the drive unit that can regulate high-power LED lighteness
Technical field
The present invention relates to a kind of great power LED, relate in particular to a kind of driving method and the drive unit that can regulate high-power LED lighteness.
Background technology
In the prior art, adopt the PWM mode to regulate the brightness of LED usually, for low power LED, because drive current is little, driving voltage is not high, and the PWM dimming mode is feasible.But for great power LED, because of drive current big (being generally hundreds of milliamperes), the driving voltage height is (when a plurality of great power LED polyphones drive, driving voltage often reaches tens of volts), this has just greatly limited the highest frequency that pwm signal can reach, so adopt the PWM mode not really desirable, show that mainly grey level and gray scale refreshing frequency are difficult to improve this two aspect to the dimming effect of great power LED light modulation.In addition, the PWM mode causes LED to drive the quick break-make of loop current, under the big high-tension situation of electric current, can form very strong electromagnetic radiation to surrounding environment, worsens the EMC (ElectromagneticCompatibility of device or equipment; Electromagnetic compatibility) performance.PWM cause flowing through LED electric current the utmost point in the short time from 0 to hundreds of milliamperes violent change, also can have influence on the working life of LED.
Summary of the invention
For solving existing in prior technology the problems referred to above, the invention provides a kind of real-time dynamic current and regulate the driving method of regulating the great power LED that combines with PWM, and a kind of drive unit of great power LED is provided.
The present invention adopts following technical scheme:
Receive the control signal of extraneous input, therefrom obtain the brightness data of LED, table look-up by computed in software or numerical value, obtain a value corresponding, this numerical value is defeated by a current regulation unit that is connected with a driver element, regulates the current value of LED of flowing through, thereby reach the purpose of regulating LED brightness; Perhaps as calculated or the corresponding numerical value separated into two parts of the gained of tabling look-up with this, part input current regulon, the electric current of regulating the LED that flows through is earlier tentatively regulated the brightness of described LED, i.e. " coarse adjustment ", the PWM regulon that another part input is connected with described driver element is provided with the duty ratio of its output signal, further regulates the brightness of described LED, i.e. " fine tuning ", the LED brightness regulation is to desired value the most at last; By the duty ratio that this PWM regulon output signal is set is 0%, with the pass described LED that goes out.
Described current regulation unit comprises a reference voltage generator, and the output of this reference voltage generator obtains a reference voltage after a digital regulation resistance dividing potential drop, and this reference voltage is input to the negative-phase input of described comparator; Described reference voltage can also be obtained after buffering, RC filtering by the output signal of a PWM generator, is input to the negative-phase input of described comparator then.
The input signal of described current regulation unit also comprises a sampled voltage, this sampled voltage is provided by a sampling resistor of described driver element, directly or input to the normal phase input end of a comparator of described current regulation unit after buffering is amplified, a logical circuit is received in the output of this comparator.
Described logical circuit is connected with oscillator;
Described PWM regulon and described current regulation unit are by a microprocessor controls.
A kind of drive unit that can regulate high-power LED lighteness, comprise the great power LED driver element, the PWM regulon that connect successively, and current regulation unit and microcontroller, this current regulation unit and described PWM regulon are connected in parallel between this microcontroller and the described driver element.
Described current regulation unit comprises digital regulation resistance, the comparator that connects successively, and logical circuit, and this logical circuit is connected with an oscillator.
Described driver element comprises and door, should be connected with described PWM regulon and described current regulation unit with door.
Described driver element comprises field-effect transistor, and an end of this field-effect transistor links to each other with sampling resistor with the normal phase input end of comparator, and the other end connects LED and Schottky diode, and the grid of field-effect transistor links to each other with door with described.
Described driver element also comprises sampling resistor, inductance, Schottky diode.
Technical scheme provided by the present invention has following advantage:
(1) adopt current regulation unit that great power LED is carried out the luminosity that dynamic current is regulated LED, when not changing LED brightness, the current constant of LED of flowing through is constant, LED brightness regulation technology with respect to the prior PWM mode, greatly improve the grey level and the gray scale refreshing frequency (the gray scale refreshing frequency of technical scheme provided by the present invention is equivalent to infinity) of LED brightness regulation, also can improve the Electro Magnetic Compatibility of system simultaneously, prolong the working life of LED;
(2) adopt microcontroller that the current parameters of current regulation unit is provided with in real time, can at any time the current value of the LED that flows through be adjusted according to external control signal;
(3) adopt the supplementary means of PWM technology as the LED brightness regulation, after " coarse adjustment " being carried out in LED brightness by current regulation unit, can also adopt PWM regulon in parallel with it further " fine tuning " to be carried out in LED brightness, to obtain more the grey level of horn of plenty (when using the red, green, blue three-color LED to carry out mixed light, colour mixture, abundant grey level makes the color that mixes out more true to nature).By being set, the PWM regulon can be set to go out entirely by LED.
Below with reference to accompanying drawing, give explained in detail to technical scheme of the present invention.
Description of drawings
Fig. 1 is according to a kind of schematic flow sheet that can regulate the driving method of high-power LED lighteness of the present invention;
Fig. 2 is according to a kind of block schematic diagram that can regulate the drive unit of high-power LED lighteness of the present invention;
Fig. 3 is according to a kind of structural representation that can regulate the drive unit of high-power LED lighteness of the present invention.
Among the figure, 10, microcontroller, 20, current regulation unit, 201, digital regulation resistance, 202, comparator, 203, logical circuit, 204, oscillator, 205, reference voltage generator, 30, PWM regulon/PWM generator, 40, driver element, 401, with door, 402, field-effect transistor, 403, Schottky diode, 404, inductance, 405, sampling resistor, 50, great power LED.
Embodiment
With reference to figure 1, the driving method that can regulate high-power LED lighteness provided by the present invention comprises following steps:
In step S1: receive the outside control signal of sending by microcontroller;
In step S2: microcontroller is differentiated the control signal of receiving.Differentiating external control signal is to extinguish LED fully, still LED will be adjusted to certain brightness, if will extinguish LED fully, execution in step S6 then is if will adjust to LED certain brightness value, then execution in step S3;
In step S6: by microcontroller the duty ratio of PWM regulon is made as 0%, turn-offs the LED driver element fully, LED extinguishes, and finishes the brightness regulation process one time to this;
In step S3: calculate according to the LED brightness target value in the external control signal of receiving or carry out software numerical value and table look-up by the software in the microcontroller, obtain data A that will the write current regulon and will write the data B of PWM regulon;
Then, in step S4: microcontroller is provided with the current value of the LED that flows through with data A write current regulon, the brightness of LED is reached or near desired value;
Follow, in step S5: microcontroller writes the PWM regulon with data B, and the duty ratio of PWM regulon is set again, and further the brightness of " fine tuning " LED reaches desired value.If do not need further " fine tuning " LED brightness, be made as 100% in this duty ratio with the PWM regulon.Finish one time the brightness regulation process to this;
With reference to figure 2, the invention provides a kind of drive unit that can regulate high-power LED lighteness according to said method, comprise the microcontroller 10, current regulation unit 20, PWM regulon 30, the driver element 40 that connect successively, and great power LED 50, described current regulation unit 20 and described PWM regulon 30 are connected in parallel between described microcontroller 10 and the described driver element 40.Described current regulation unit 20 is used for controlling the brightness of LED by the flow through current value of LED 50 of driver element 40 dynamic adjustments, controls the brightness of LED thereby PWM control unit 30 is used for changing LED 50 by the duty ratio that changes output signal in " the bright "/duration ratio of " going out " of a PWM in the cycle.And microcontroller 10 is used at any time the running parameter of current regulation unit 20 and PWM regulon 30 being set, and realizes the real-time control of this drive unit to LED 50 brightness.
Further with reference to figure 3, described current regulation unit 20 comprises digital regulation resistance 201, comparator 202, the logical circuit 203 that connects successively, oscillator 204, and reference voltage generator 205; The input of described digital regulation resistance 201 is directly connected in microcontroller 10, A, B end connects reference voltage generator 205 and ground (GND) respectively, tap W receives the negative-phase input of comparator 202, being connected in described logical circuit 203 and the driver element 40 with door 401, in other words, should directly be connected with described PWM regulon 30 with an input of door, another input directly is connected with described logical circuit 203 in the described current regulation unit 20; Described output with door 401 is connected N slot field-effect transistor 402, the S utmost point of this field-effect transistor 402 links to each other with sampling resistor 405 with the normal phase input end of comparator 202, the D utmost point connects inductance 404 and Schottky diode 403, and the G utmost point links to each other with output with door 401.Another termination great power LED 50 of inductance 404.
Described digital regulation resistance 201 is used for the output voltage dividing potential drop to reference voltage generator 205, obtains a reference voltage and is entered in the comparator 202.Described comparator 202 is used for the sampled voltage that relatively this reference voltage and sampling resistor 405 provide, and according to the different level of comparative result output.Described logical circuit 203 will decide the open and close time scale of field-effect transistor 402 in a cycle of oscillation according to the output signal of comparator 202 and oscillator 204, its function is: during electrification reset, output low level signal " 0 ", rising edge at the signal of oscillator 204 output, its output switching activity is high level signal " 1 ", at the rising edge of comparator 202 output signals, its output switching activity is low level signal " 0 "; The specific implementation method of this logical circuit is that the moderate technical staff of electronic circuit field is not difficult to realize, does not add at this and gives unnecessary details.In addition, the function of described comparator 202 and logical circuit 203 also can realize with a slice integrated circuit (IC) chip NE555, under the prerequisite of the working mechanism of understanding principle of the present invention and NE555, its specific implementation method is that the moderate technical staff of electronic circuit field is not difficult to realize, is therefore also no longer given unnecessary details at this.Described oscillator 204 is used to produce oscillator signal.Described field-effect transistor 402 is used for driving LED 50.
Refer again to Fig. 3, when the described drive unit that can regulate high-power LED lighteness is worked, microcontroller 10 is to digital regulation resistance 201 and PWM generator 30 input control datas, and the output signal duty ratio of for example setting PWM generator 30 this moment is 100%, and level is continuously " 1 "; Digital regulation resistance 201 is set provides suitable reference voltage to comparator 202; When logical circuit 203 finished in electrification reset, output low level signal " 0 " was with door 401 outputs " 0 ", field-effect transistor 402 turn-offs, the sampled voltage that sampling resistor 405 provides is 0, is lower than the reference voltage of comparator 202 negative phase ends, and comparator 202 is output as " 0 "; A rising edge arrival when oscillator 204 output signals, triggering logical circuit 203 output switching activities is " 1 ", cause and door 401 outputs " 1 ", field-effect transistor 402 conductings at this moment, have electric current flow through LED 50 and inductance 404 and through sampling resistor 405 to ground; Stagnant resistance characteristic because of inductance 404, current in loop will rise by the integral curve rule, the sampled voltage of sampling resistor 405 upper ends is also risen by integral curve, this sampled voltage direct (or through buffering amplification) is input to the normal phase input end of comparator 202, when this sampled voltage surpasses the reference voltage that comparator 202 provides by digital regulation resistance 201, the output of comparator 202 promptly is " 1 " by " 0 " upset, the rising edge that this level changes makes the output of logical circuit 203 be " 0 " by " 1 " upset, field-effect transistor 402 is turned off, inductance 404 is by Schottky diode 403 discharges, for LED 50 provides continuous current; Field-effect transistor 402 closes has no progeny, the voltage of sampling resistor 405 upper ends reduces to 0, comparator 202 outputs become " 0 ", and logical circuit 203 is waited for the arrival of the next signal rising edge that oscillator 204 produces, and then enters the work period that the next one repeats above-mentioned action;
Obviously, in technique scheme, the mean value of LED electric current of flowing through is directly proportional to the time span between the rising edge of comparator 202 output signals with the rising edge of oscillator 204 output signals, and this " time span " is by the reference level of comparator 202 and the resistance of sampling resistor 405, the inductance value decision of inductance 404, resistance at sampling resistor 405, under the situation that the inductance value of inductance 404 is fixed, reference level by comparator 202 is determined fully, so microcontroller 10 is by the reference level of control figure potentiometer 201 outputs, with regard to the average current size of controllable flow through LED 50, and then the brightness of control LED50.
In addition, also be provided with a PWM regulon 30 in the present embodiment, this PWM generator 30 by with door 401 break-make with the common controlling filed effect transistor 402 of output of logical circuit 203, so microcontroller 10 can also recently be adjusted the brightness of LED by the duty that PWM generator 30 output signals are set.Regulate the machine-processed different of LED brightness with current regulation unit 20 by the flow through size of current in LED loop of adjusting, PWM regulon 30 is the brightness of controlling LED by duration ratio that pwm signal LED " bright "/" going out " in the cycle is set, obviously, the frequency of the pwm signal that PWM regulon 30 produces will be far below the signal frequency of oscillator 204, and the Current Regulation function could normally play a role like this.In the present embodiment, PWM mechanism is to use as the supplementary means of LED brightness regulation.
Because current adjustment mechanism can not adjust to 0 with current in loop usually, so when will LED being set to go out entirely, must use PWM mechanism, at this moment the signal dutyfactor by microcontroller 10 PWM generators 30 is set to 0% and gets final product.
In the above-described embodiments, the reference voltage of comparator 202 is that tap W by digital regulation resistance 201 is provided.The scheme that another one can be selected is, PWM generator of microcontroller 10 controls, and the DC level that the pwm signal of this PWM generator output obtains after buffering, RC filtering is the reference voltage of device 202 as a comparison.
From above explanation to the embodiment of the invention as seen, the present invention provides two mechanism of relation in parallel for the control of LED brightness: real-time, dynamic current adjustment mechanism that plays a major role and the PWM mechanism that helps out.Microcontroller can take the appropriate software control strategy to use this two mechanism, makes the brightness regulation of great power LED reach optimum efficiency.The software controlling strategies of a success is, MCU receives external control signal, obtains the target brightness value of LED, with as the foundation that comparator reference voltage or PWM duty ratio are set.Except LED being adjusted to the very low brightness, generally only use current adjustment mechanism.In the time LED need being adjusted to very low brightness, with current adjustment mechanism electric current is transferred to minimum value (such as 2mA) earlier, it is lower to adopt PWM mechanism that LED brightness further is transferred to again, to obtain more grey level.Because under the small electric stream mode, use PWM, can not cause serious EMC (electromagnetic compatibility) problem usually.
Be noted that at last above embodiment only in order to a technical scheme of the present invention to be described, is not intended to limit.Detailed description with reference to above embodiment, those of ordinary skill in the art should understand and implement, simultaneously can also make amendment or carry out the replacement of same function the technical scheme of the foregoing description, but these modifications or replacement then mean not break away from the spirit and scope of the invention yet as if no significant technological progress.

Claims (12)

1. the driving method that can regulate high-power LED lighteness is characterized in that, this method comprises following step:
Receive the control signal of extraneous input, therefrom obtain the brightness data of LED, table look-up by computed in software or software numerical value, obtain a corresponding numerical value, this numerical value is input to a current regulation unit that is connected with a driver element, the flow through size of current of described LED of setting is lighted described LED and is made its brightness reach desired value;
The electric current of the LED that flows through perhaps is set earlier according to the method described above, tentatively regulates the brightness of described LED, and then the signal dutyfactor of the PWM regulon in parallel with described current regulation unit is set again, further regulate the brightness of LED, make it finally reach desired value;
By the duty ratio that PWM regulon signal is set is 0%, closes the described LED that goes out.
2. the driving method that can regulate high-power LED lighteness according to claim 1, it is characterized in that, described current regulation unit comprises a reference voltage generator, the output voltage of this reference voltage generator obtains a reference voltage after through a digital regulation resistance dividing potential drop, this reference voltage is connected to the input of a comparator of described current regulation unit, another input signal of this comparator is provided by a sampling resistor that is connected in the described LED loop, and the output of this comparator is connected to the input of a logical circuit.
3. want the 2 described driving methods that can regulate high-power LED lighteness according to right, it is characterized in that, described digital regulation resistance is subjected to a microprocessor controls.
4. want the 2 described driving methods that can regulate high-power LED lighteness according to right, it is characterized in that, the reference voltage that is input to described comparator is obtained after buffering, RC Filtering Processing by the output signal of a PWM generator, and this PWM generator is subjected to a microprocessor controls.
5. the driving method that can regulate high-power LED lighteness according to claim 2, it is characterized in that, an input of described logical circuit is connected to the output of an oscillator, and the output of described logical circuit is by the output of described oscillator and the output decision of described comparator.
6. the driving method that can regulate high-power LED lighteness according to claim 1, it is characterized in that, described PWM regulon and described current regulation unit are subjected to a microprocessor controls, and the external world regulates LED brightness by transmitting control signal to described microcontroller.
7. the drive unit that can regulate high-power LED lighteness, comprise the LED driver element, current regulation unit, PWM regulon and the microcontroller that connect successively, it is characterized in that described current regulation unit and described PWM regulon are connected in parallel between described microcontroller and the described driver element.
8. the drive unit that can regulate high-power LED lighteness according to claim 7 is characterized in that, described current regulation unit comprises digital regulation resistance, the comparator that connects successively, and logical circuit.
9. the drive unit that can regulate high-power LED lighteness according to claim 7 is characterized in that, described driver element comprises and door, two inputs of described and door respectively with described PWM regulon, and described current regulation unit connects.
10. the drive unit that can regulate high-power LED lighteness according to claim 9, it is characterized in that, described driver element also comprises field-effect transistor, one end of this field-effect transistor links to each other with a sampling resistor with the normal phase input end of comparator, the other end connects the LED loop, and the grid of this field-effect transistor links to each other with door with described.
11. the drive unit that can regulate high-power LED lighteness according to claim 9 is characterized in that described driver element comprises inductance, this inductance links to each other with described LED with field-effect transistor.
12. the drive unit that can regulate high-power LED lighteness according to claim 9 is characterized in that described driver element comprises Schottky diode, the anode of this Schottky diode links to each other with field-effect transistor with inductance, and negative electrode links to each other with power supply VCC.
CNA2008101868641A 2008-12-31 2008-12-31 Drive method and drive device capable of regulating high-power LED lighteness Pending CN101466186A (en)

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US8305013B2 (en) 2010-07-12 2012-11-06 O2Micro International Limited Circuits and methods for controlling dimming of a light source
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CN107592702A (en) * 2017-09-18 2018-01-16 佛山市国星光电股份有限公司 A kind of power conditioning circuitry and LED drive device
CN107592702B (en) * 2017-09-18 2024-04-09 佛山市国星光电股份有限公司 Power regulating circuit and LED lamp driving device
CN108174495A (en) * 2017-12-14 2018-06-15 浙江大华技术股份有限公司 The luminance regulating method and device of a kind of signal lamp
CN108174495B (en) * 2017-12-14 2021-06-15 浙江大华技术股份有限公司 Signal lamp brightness adjusting method and device
CN109413343A (en) * 2018-10-17 2019-03-01 黄秀瑜 A kind of LED video display system
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CN112863457A (en) * 2019-11-27 2021-05-28 深圳市万普拉斯科技有限公司 Display brightness adjusting method and device, electronic equipment and storage medium
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