CN103582226A - Dimming circuit and dimming method thereof - Google Patents
Dimming circuit and dimming method thereof Download PDFInfo
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- CN103582226A CN103582226A CN201210280561.2A CN201210280561A CN103582226A CN 103582226 A CN103582226 A CN 103582226A CN 201210280561 A CN201210280561 A CN 201210280561A CN 103582226 A CN103582226 A CN 103582226A
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Abstract
The embodiment of the invention provides a dimming circuit and a dimming method of the dimming circuit. The dimming method includes the steps of judging whether the duty ration of a first pulse width modulation signal is larger than a threshold duty ratio or not, conducting frequency conversion and phase displacement on the first pulse width modulation signal to form a second pulse width modulation signal according to a pulse wave information signal when the duty ration of the first pulse width modulation signal is smaller than the threshold duty ratio, and adjusting a preset dimming current according to the pulse wave information signal when the duty ration of the first pulse width modulation signal is larger than the threshold duty ratio, wherein the threshold duty ration is set according to the preset dimming current.
Description
Technical field
The present invention relates to a kind of light-dimming method, and be particularly related to a kind of light-dimming method that adopts combined type light modulation.
Background technology
In recent years, many electronic products have display screen, for example mobile phone, PDA (Personal Digital Assistant) (Personal Digital Assistant, PDA), digital music broadcasting machine and fascia.Although the kind of screen and size are normally according to application decision, design engineer is necessary for its design lighting circuit.Because comprise Thin Film Transistor-LCD, at interior most displays, all need back lighting, user just can see figure and the word on screen clearly like this.Light-emitting diode is the normal backlight module adopting of current electronic product.Uniform backlight with a chromatic liquid crystal screen curtain needs 3～4 or more light-emitting diode, and instrument board backlight may need 6 or more light-emitting diode.Due to increasing of light-emitting diode demand, effectively promoted the growth in LED drive market.
Yet; backlight module or backlight module that present many utilization Organic Light Emitting Diodes are used as light source often can produce some noises (acoustic noise); particularly using portable electronic devices (as mobile phone); chance near user's ear is more and more, therefore more and more easily experiences the impact of noise.Under prior art, the noise problem that often will produce for the product of various species goes to adjust or change, very labor intensive, time and money one by one.
Summary of the invention
The embodiment of the present invention provides a kind of light adjusting circuit, for driving light emitting diode.Light adjusting circuit comprises control unit, sample analysis unit, pulse width signal adjustment unit and simulation light modulation unit.Control unit judges whether the duty ratio of the first pulse width modulating signal is greater than critical duty ratio.Sample analysis unit receives and analyzes the first pulse width modulating signal, and exports pulse wave information signal.Pulse width signal adjustment unit is coupled between control unit and current regulation unit, receives pulse wave information signal.Simulation light modulation unit is coupled between control unit and current regulation unit, receives pulse wave information signal.
When the duty ratio of the first pulse width modulating signal is less than critical duty ratio, pulse width signal adjustment unit, according to pulse wave information signal, the first pulse width modulating signal is given to frequency conversion and phase shift is the second pulse width modulating signal, and the light modulation electric current presetting is exported in simulation light modulation unit.
When the duty ratio of the first pulse width modulating signal is greater than critical duty ratio, the light modulation electric current that simulation light modulation unit presets according to the adjustment of pulse wave information signal, and pulse width signal adjustment unit output one has the second pulse width modulating signal of 100% duty ratio.
The embodiment of the present invention provides again a kind of light-dimming method of light-emitting diode, and its step comprises as follows.Whether the duty ratio that judges the first pulse width modulating signal is greater than critical duty ratio; When the duty ratio of the first pulse width modulating signal is less than critical duty ratio, according to pulse wave information signal, the first pulse width modulating signal is given to frequency conversion and phase shift is the second pulse width modulating signal, and the light modulation electric current that presets of output; And when the duty ratio of the first pulse width modulating signal is greater than critical duty ratio, the light modulation electric current presetting according to the adjustment of pulse wave information signal.
In sum, the light adjusting circuit that the embodiment of the present invention proposes and light-dimming method thereof, according to the relatively judgement between the duty ratio of the first pulse width modulating signal and critical duty ratio, and then take different light modulation mechanism, the noise being produced to reduce backlight module.
For enabling further to understand feature of the present invention and technology contents, refer to following about detailed description of the present invention and accompanying drawing, but these explanations with appended graphic be only for the present invention is described, but not claim scope of the present invention is done to any restriction.
Accompanying drawing explanation
With reference to alterations, explain specific embodiments of the invention above, by this can be more clear to the present invention, in these are graphic:
Fig. 1 is the schematic diagram of backlight module according to an embodiment of the invention.
Fig. 2 is the thin portion schematic diagram according to the light adjusting circuit of the embodiment of the present invention.
Fig. 3 is according to the drive waveforms figure of the second pulse width modulating signal of the embodiment of the present invention.
Fig. 4 is according to the flow chart of the light-dimming method of the embodiment of the present invention.
[main element symbol description]
100: backlight module
110: light adjusting circuit
111: control unit
112: booster circuit
113: simulation light modulation unit
114: sample analysis unit
115: pulse width signal adjustment unit
1152: converter unit
1154: phase shift unit
120: light emitting diode
130: current regulation unit
CH1～CHN: passage
DS1～DSN: light-emitting diodes pipe string
I1～IN: output current
IF: feedback current
Iset: the light modulation electric current presetting
IOUT: output current
PIS: pulse wave information signal
PWMI: the first pulse width modulating signal
PWMO, PWMO1～PWMON: the second pulse width modulating signal
S410～S430: step
VLED: driving voltage
Embodiment
Below describing more fully various exemplary embodiments referring to alterations, in alterations, show some exemplary embodiments.Yet concept of the present invention may be with many multi-form embodiments, and should not be construed as and be limited to the exemplary embodiments set forth herein.Definite, provide these exemplary embodiments to make the present invention will be for detailed and complete, and will to those of ordinary skill in the art, fully pass on the category of concept of the present invention.All graphic in, can be for clear and lavish praise on oneself size and the relative size in Ceng Ji district.Similar numeral is indicated like all the time.
Although should be understood that herein and may describe various elements by term first, second, third, etc., these elements are not limited by these terms should.These terms are to distinguish an element and another element.Therefore the first element of, below discussing can be described as the second element and does not depart from the teaching of concept of the present invention.As used herein, term " and/or " comprise any one and one or many person's all combinations in project of listing that are associated.
(embodiment of backlight module)
Please refer to Fig. 1, Fig. 1 is the schematic diagram of backlight module according to an embodiment of the invention.Backlight module 100 comprises light adjusting circuit 110, light emitting diode 120 and current regulation unit 130.Light adjusting circuit 110 couples light emitting diode 120.Current regulation unit 130 couples between light emitting diode 120 and light adjusting circuit 110.Backlight module 100 can be the backlight module being used in general flat-panel monitor (as organic light emitting diode display), or the backlight module being used in portable electronic devices (as action circuit), but with cited person, is not limited.
Current regulation unit 130 in order to the light modulation electric current I set that receives the second pulse width modulating signal PWMO or preset to regulate an output current IO UT of light emitting diode 120.Next will further illustrate, be the relevant action about backlight module 100.
In the present embodiment, the light adjusting circuit 110 of backlight module 100 can drive light emitting diode 120 by output one driving voltage VLED, and in driving the process of light emitting diode 120, the feedback current IF that light adjusting circuit 110 meeting reception one current regulation units 130 are exported adjusts the size of driving voltage VLED, to can drive whole light emitting diode 120.Simultaneously, light adjusting circuit 110 can receive the first pulse width modulating signal PWMI, and for the first pulse width modulating signal PWMI, sample and analyze, to obtain the signal message of the first pulse width modulating signal PWMI, for example duty ratio (duty ratio) and frequency.Afterwards, light adjusting circuit 110 carries out a computing action of comparing by the duty ratio of the first pulse width signal PWMI and critical duty ratio, and according to comparative result, decide the follow-up mechanism of the light modulation to light emitting diode 120, to reduce the noise that backlight module 100 produces.
When the duty ratio of the first pulse width modulating signal PWMI is less than critical duty ratio, light adjusting circuit 110 the first pulse width modulating signal PWMI can be given to frequency conversion and phase shift is the second pulse width modulating signal PWMO, furthermore, light adjusting circuit 110 can be exported the second different pulse width modulating signal PWMO from frequency (the first pulse width modulating signal PWMI) according to different duty ratios.Then, the light modulation electric current I set that light adjusting circuit 110 can preset the second pulse width modulating signal PWMO and is sent to current regulation unit 130, to further regulate the output current IO UT of light emitting diode 120.
Above-mentioned critical duty ratio can be set according to the light modulation electric current I set presetting, for instance, the light modulation electric current I set presetting can be obtained to a current ratio divided by the rated current (as 20 milliamperes) of light-emitting diode, then with this current ratio, be multiplied by 100% and can obtain critical duty ratio.Those of ordinary skills should understand, the rated current of light-emitting diode after manufacturing the maximum that arrives by element (light-emitting diode) of measurement can operating current.In another preferred embodiment, the light modulation electric current I set that this presets can be set to the maximum light conversion efficiency electric current (as 5 milliamperes) of light-emitting diode, can be so that when light emitting diode 120 drives under the duty ratio of the first pulse width modulating signal PWMI is less than the condition of critical duty ratio, there is preferably drive efficiency.The maximum light conversion efficiency electric current of light-emitting diode can be determined by the data result after measuring.In another embodiment, critical duty ratio can further decide according to the number of light emitting diode 120 internal channels, for instance, critical duty ratio can be 100% to be multiplied by above-mentioned current ratio and divided by the number of light emitting diode 120 internal channels, according to this embodiment, can also guarantee that the second pulse width modulating signal PWMO after phase-shifted can not overlap each other.In other embodiments, except the number according to light emitting diode 120 internal channels decides critical duty ratio, also can select arbitrary number to replace according to product demand.
On the other hand, when the duty ratio of the first pulse width modulating signal PWMI is greater than critical duty ratio, light adjusting circuit 110 can be exported a second pulse width modulating signal PWMO with 100% duty ratio to current regulation unit 130.That is to say, light adjusting circuit 110 can be exported a direct voltage to current regulation unit 130.Meanwhile, light adjusting circuit 110 can be adjusted this light modulation electric current I set presetting, and then the light modulation electric current I set presetting after adjusting is sent to current regulation unit 130, to further regulate the output current IO UT of light emitting diode 120.In addition, when the duty ratio of the first pulse width modulating signal PWMI equals critical duty ratio, designer can be defined as this situation according to circuit design demand the light modulation mechanism that is greater than critical duty ratio as the duty ratio of the first pulse width modulating signal PWMI, or the duty ratio of the first pulse width modulating signal PWMI is less than the light modulation mechanism of critical duty ratio.According to the above description, the backlight module 100 of the present embodiment can utilize the combined type light modulation mechanism of light adjusting circuit 110 that interior the produced noise of backlight module 100 (acoustic noise) is reduced, and even in the ideal situation noise is eliminated completely.
It is worth mentioning that, the light modulation mechanism of the light adjusting circuit 110 of the present embodiment, applicable to the panel of different frequency range, that is to say, the light adjusting circuit 110 of this disclosure content can provide for panel miscellaneous the combined type light modulation mechanism of a reduction noise.
In order to illustrate in greater detail the operation workflow of light adjusting circuit 110 of the present invention, below by for one of at least doing further description in a plurality of embodiment.
In ensuing a plurality of embodiment, description is different to the part of above-mentioned Fig. 1 embodiment, and all the other clippeds are identical with the part of above-mentioned Fig. 1 embodiment.In addition,, for the purpose of facility is described, similar reference number or label are indicated similar element.
(embodiment of light adjusting circuit)
Please refer to Fig. 2, Fig. 2 is the thin portion schematic diagram according to the light adjusting circuit of the embodiment of the present invention.Different from above-mentioned Fig. 1 embodiment, light adjusting circuit 110 comprises control unit 111, booster circuit 112, simulation adjustment unit 113, sample analysis unit 114 and pulse width signal adjustment unit 115 in the present embodiment.Pulse width signal adjustment unit 115 comprises converter unit 1152 and phase shift unit 1154.Light emitting diode 120 comprises at least one light-emitting diodes pipe string, and in following examples, will organize light-emitting diodes pipe string DS1～DSN with N to describe, and wherein N is positive integer.
Afterwards, sample analysis unit 114 can be sent to control unit 111, simulation light modulation unit 113 and pulse width signal adjustment unit 115 with the pulse wave information signal PIS of the frequency signal that contains frequency information by the duty cycle signals that contains duty cycle information.Then, control unit 111 can carry out a computing action of comparing by the duty ratio of the first pulse width signal PWMI and critical duty ratio, and according to comparative result, decide the follow-up light modulation mechanism that light emitting diode 120 is adopted, to can further process the noise problem that backlight module produces.
In addition, in driving, respectively organize in the process of light-emitting diodes pipe string DS1～DSN, the feedback current IF that control unit 111 meeting received current regulons 130 are exported adjusts the size of driving voltage VLED, to can drive completely and respectively organize light-emitting diodes pipe string DS1～DSN in light emitting diode 120, but not be limited with the present embodiment.
Two kinds of comparative results and the light modulation mechanism of below mainly putting up with for control unit 111 are described further.
When the duty ratio of the first pulse width modulating signal PWMI is less than critical duty ratio, control unit 111 meeting control simulation light modulation unit 113 are to export a light modulation electric current I set who presets, and control unit 111 can be controlled pulse width signal adjustment unit 115, make the converter unit 1152 in pulse width signal adjustment unit 115, according to the pulse wave information signal PIS receiving, the first pulse width modulating signal PWMI be given to frequency conversion, and in the present embodiment, converter unit 1152 is to the frequency band between 20KHz～30KHz by the first pulse width modulating signal PWMI raising frequency.In another embodiment, if technology allows the frequency of operation of chip more than 30KHz, converter unit 1152 can, by the first pulse width modulating signal PWMI raising frequency to more than 30KHz, not be limited with the present embodiment.Then, phase shift unit 1154 receives the first pulse width modulating signal PWMI after the frequency conversion transmitting from converter unit 1152, and the first pulse width modulating signal PWMI after frequency conversion is carried out to phase shift (phase shift) usings as the second pulse width modulating signal PWMO.Afterwards, phase shift unit 1154 is sent to current regulation unit 130 to regulate the output current I1～IN that respectively organizes light-emitting diodes pipe string DS1～DSN by the second pulse width modulating signal PWMO.
Next, for convenience of description, please also refer to Fig. 2 and Fig. 3, Fig. 3 is according to the drive waveforms figure of the second pulse width modulating signal of the embodiment of the present invention.Converter unit 1152 is sent to phase shift unit 1154 by the first pulse width modulating signal PWMI after frequency conversion, after the first pulse width modulating signal PWMI of phase shift unit 1154 after receiving frequency conversion, the first pulse width modulating signal PWMI of frequency conversion is given to phase shift and becomes the second pulse width modulating signal PWMO, meaning be a plurality of second pulse width modulating signal PWMO1～PWMON(as shown in Figure 3).Furthermore, phase shift unit 1154 is sequentially sent to current regulation unit 130 by a plurality of second pulse width modulating signal PWMO1～PWMON, to regulate accordingly, respectively organizes light-emitting diodes pipe string DS1～DSN(or each channel C H1～CHN) output current I1～IN.Accordingly, the light adjusting circuit 110 of the present embodiment can make the moment of light emitting diode 120 take out that electric current diminishes and the piezoelectric effect that reduces change in voltage and electric capacity, and then reduces the noise that backlight module produces.
It should be noted that in one embodiment, second pulse width modulating signal PWMO1～PWMON in Fig. 3 is completely not overlapping to each other, and in another embodiment, second pulse width modulating signal PWMO1～PWMON in Fig. 3 partly overlaps to each other.In gross, in second pulse width modulating signal PWMO1～PWMON, adjacent two pulse width modulating signals at least have a phase difference to each other, to reduce the electric current of taking out of each channel C H1～CHN moment.
When the duty ratio of the first pulse width modulating signal PWMI is greater than critical duty ratio, it is a direct voltage to export a second pulse width modulating signal PWMO(meaning with 100% duty ratio that control unit 111 can be controlled pulse width signal adjustment unit 115) to current regulation unit 130, and control unit 111 can control simulation light modulation unit 113.The light modulation electric current I set that simulation light modulation unit 113 can come corresponding adjustment to preset according to the pulse wave information signal PIS receiving, and the light modulation electric current I set presetting after adjusting is sent to current regulation unit 130 to regulate the output current I1～IN that respectively organizes light-emitting diode DS 1～DSN in light emitting diode 120.In the present embodiment, the light modulation electric current I set presetting that simulation light modulation unit 113 is exported and the duty ratio of the first pulse width modulating signal PWMI present proportional relation, that is to say, the work period longer (meaning is that duty ratio is larger) of the first pulse width modulating signal PWMI, the value of the light modulation electric current I set presetting after adjusting also will be larger, and then make output current I1～IN of each light-emitting diodes pipe string DS1～DSN larger.
Above-mentioned critical duty ratio can be set according to the light modulation electric current I set presetting, for instance, the light modulation electric current I set presetting can be obtained to a current ratio divided by the rated current (as 20 milliamperes) of light-emitting diode, then with this current ratio, be multiplied by 100% and can obtain critical duty ratio.Those of ordinary skills should understand, the rated current of light-emitting diode after manufacturing the maximum that arrives by element (light-emitting diode) of measurement can operating current.In another preferred embodiment, the light modulation electric current I set that this presets can be set to the maximum light conversion efficiency electric current (as 5 milliamperes) of light-emitting diode, can be so that when light emitting diode 120 drives under the duty ratio of the first pulse width modulating signal PWMI is less than the condition of critical duty ratio, there is preferably drive efficiency.The maximum light conversion efficiency electric current of light-emitting diode can be determined by the data result after measuring.In another embodiment, critical duty ratio can further decide according to the number of light emitting diode 120 internal channels, for instance, critical duty ratio be for can be 100% to be multiplied by above-mentioned current ratio and divided by the number of light emitting diode 120 internal channels, according to this embodiment, can also guarantee that second pulse width modulating signal PWMO1 ~ PWMON after phase-shifted can not overlap each other.In other embodiments, except the number according to light emitting diode 120 internal channels decides critical duty ratio, also can select arbitrary number to replace according to product demand.
In addition, in the present embodiment, when the duty ratio of the first pulse width modulating signal PWMI equals critical duty ratio, designer can be defined as this situation according to circuit design demand the light modulation mechanism that is greater than critical duty ratio as the duty ratio of the first pulse width modulating signal PWMI, or the duty ratio of the first pulse width modulating signal PWMI is less than the light modulation mechanism of critical duty ratio.
In a word, not departing under the spirit of the light modulation electric current that presets according to the duty ratio adjustment of the first different pulse width signals and the second pulse width signal, all belong in the disclosed scope of the present invention.
(embodiment of light-dimming method)
Please refer to Fig. 4, Fig. 4 is according to the flow chart of the light-dimming method of the embodiment of the present invention.As shown in Figure 4, light-dimming method comprises that step is as follows.Whether the duty ratio that judges the first pulse width modulating signal is greater than a critical duty ratio (S410).When the duty ratio of the first pulse width modulating signal is less than critical duty ratio, according to pulse wave signal information, by the first pulse width modulating signal frequency conversion and phase shift, be the second pulse width modulating signal (S420).When the duty ratio of the first pulse width modulating signal is greater than critical duty ratio, the light modulation electric current (S430) presetting according to the adjustment of pulse wave information signal.It is worth mentioning that, critical duty ratio can be set by the light modulation electric current I set presetting.Each step correlative detail about the light-dimming method of light adjusting circuit describes in detail at above-mentioned Fig. 1～Fig. 3 embodiment, at this, does not repeat for this reason.At this, should be noted that, each step of Fig. 4 embodiment is needs for convenience of description only, and the embodiment of the present invention is not usingd each step order to each other as the restrictive condition of implementing each embodiment of the present invention.
(the possible effect of embodiment)
In sum, the light adjusting circuit that the embodiment of the present invention provides and light-dimming method thereof, according to the relatively judgement between the duty ratio of pulse width modulating signal and critical duty ratio, and then take different light modulations machine-processed, to can reduce noise, noise can be eliminated completely even in the ideal situation.Moreover, the combined type light modulation mechanism of the light adjusting circuit in this disclosure content is applicable to the panel of different frequency range, that is to say, the light adjusting circuit of this disclosure content can provide the combined type light modulation mechanism of a reduction noise for panel miscellaneous, can save significantly design time and design cost.
The foregoing is only embodiments of the invention, it is not in order to limit to the scope of the claims of the present invention.
Claims (16)
1. a light adjusting circuit, for driving light emitting diode, is characterized in that, described light adjusting circuit comprises:
Control unit, receives the first pulse width modulating signal and judges whether the duty ratio of described the first pulse width modulating signal is greater than critical duty ratio;
Sample analysis unit, receives described the first pulse width modulating signal and analyzes described the first pulse width modulating signal, and exporting pulse wave information signal;
Pulse width signal adjustment unit, is coupled between described control unit and current regulation unit, receives described pulse wave information signal; And
Simulation light modulation unit, is coupled between described control unit and described current regulation unit, receives described pulse wave information signal;
Wherein when the duty ratio of described the first pulse width modulating signal is less than described critical duty ratio, described pulse width signal adjustment unit, according to described pulse wave information signal, described the first pulse width modulating signal is given to frequency conversion and phase shift is at least one the second pulse width modulating signal, and the light modulation electric current presetting is exported in described simulation light modulation unit;
Wherein when the duty ratio of described the first pulse width modulating signal is greater than described critical duty ratio, the light modulation electric current that described simulation light modulation unit presets described in adjusting according to described pulse wave information signal, and the output of described pulse width signal adjustment unit has described second pulse width modulating signal of 100% duty ratio.
2. light adjusting circuit according to claim 1, is characterized in that, described pulse width signal adjustment unit also comprises:
Converter unit, couples described control unit, and described converter unit receives described pulse wave information signal and described the first pulse width modulating signal is given to frequency conversion; And
Phase shift unit, be coupled between described converter unit and described current regulation unit, in order to being described the second pulse width modulating signal by described the first pulse width modulating signal phase shift after frequency conversion, and sequentially described the second pulse width modulating signal is sent to corresponding at least one passage.
3. light adjusting circuit according to claim 1, is characterized in that, described pulse wave information signal also comprises duty cycle signals and frequency signal.
4. light adjusting circuit according to claim 1, is characterized in that, described critical duty ratio according to described in the light modulation electric current that presets and the rated current of the light-emitting diode in described light emitting diode determine.
5. light adjusting circuit according to claim 4, is characterized in that, described in the light modulation electric current that the presets maximum light conversion efficiency electric current that is described light emitting diode.
6. light adjusting circuit according to claim 4, is characterized in that, described critical duty ratio also determines according to the number of at least one passage in described light emitting diode.
7. light adjusting circuit according to claim 2, is characterized in that, described converter unit is between frequency band 20KHz to 30KHz by the frequency raising frequency of described the first pulse width modulating signal.
8. light adjusting circuit according to claim 1, it is characterized in that, described current regulation unit couples between described light emitting diode and described control unit, described current regulation unit receive described the second pulse width modulation signal or described in the light modulation electric current that presets to regulate the output current of described light emitting diode;
Described light adjusting circuit also comprises a booster circuit, is coupled between described control unit and described light emitting diode, is controlled by described control unit and drives described light emitting diode with outputting drive voltage.
9. light adjusting circuit according to claim 8, is characterized in that, described light emitting diode comprises:
At least one light-emitting diodes pipe string, is coupled between described booster circuit and described current regulation unit, and described light-emitting diode was ganged up described current regulation unit and adjusted described output current.
10. a light-dimming method, for light emitting diode, is characterized in that, described light-dimming method comprises:
Whether the duty ratio that judges the first pulse width modulating signal is greater than critical duty ratio;
When the duty ratio of described the first pulse width modulating signal is less than described critical duty ratio, according to pulse wave information signal, described the first pulse width modulating signal is given to frequency conversion and phase shift is at least one the second pulse width modulating signal, and the light modulation electric current that presets of output; And
When the duty ratio of described the first pulse width modulating signal is greater than described critical duty ratio, the light modulation electric current presetting described in adjusting according to described pulse wave information signal.
11. light-dimming methods according to claim 10, is characterized in that, described critical duty ratio according to described in the light modulation electric current that presets and the rated current of light-emitting diode determine.
12. light adjusting circuits according to claim 10, is characterized in that, described in the light modulation electric current that the presets maximum light conversion efficiency electric current that is light-emitting diode.
13. light-dimming methods according to claim 10, is characterized in that, according to described pulse wave information signal, described the first pulse width modulating signal being given to frequency conversion and phase shift is that the step of at least one the second pulse width modulating signal comprises:
The light modulation electric current presetting described in the output of control simulation light modulation unit.
14. light-dimming methods according to claim 10, is characterized in that, it is that the step of at least one the second pulse width modulating signal also comprises that the first pulse width modulating signal is given to frequency conversion and phase shift:
By the frequency raising frequency of described the first pulse width modulating signal, be between frequency band 20KHz to 30KHz.
15. light-dimming methods according to claim 10, is characterized in that, the step of the light modulation electric current presetting described in adjusting according to described pulse wave information signal comprises:
When the duty ratio of described the first pulse width modulating signal is greater than described critical duty ratio, output has described second pulse width modulating signal of 100% duty ratio.
16. light-dimming methods according to claim 10, is characterized in that, described light-dimming method also comprises:
Outputting drive voltage drives described light emitting diode;
Receive and analyze described the first pulse width modulating signal, and export the described pulse wave information signal that contains duty cycle signals and frequency signal; And
Receive described the second pulse width modulating signal or described in the light modulation electric current that presets with regulation output electric current.
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| CN107221293A (en) * | 2017-05-23 | 2017-09-29 | 广州视源电子科技股份有限公司 | Duty ratio regulating circuit and LED backlight brightness regulating circuit |
| CN110767180A (en) * | 2019-10-12 | 2020-02-07 | 昆山龙腾光电股份有限公司 | Backlight adjusting circuit and dimming method thereof |
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| CN102402953A (en) * | 2011-12-08 | 2012-04-04 | 深圳市华星光电技术有限公司 | Driving circuit and method of light-emitting diode and display device applying same |
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| CN107221293B (en) * | 2017-05-23 | 2019-09-03 | 广州视源电子科技股份有限公司 | Duty ratio regulating circuit and LED backlight brightness regulating circuit |
| CN110767180A (en) * | 2019-10-12 | 2020-02-07 | 昆山龙腾光电股份有限公司 | Backlight adjusting circuit and dimming method thereof |
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