CN102348303B - Driving circuit, light modulator and light modulating method of light-emitting diode - Google Patents
Driving circuit, light modulator and light modulating method of light-emitting diode Download PDFInfo
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- CN102348303B CN102348303B CN201010242192.9A CN201010242192A CN102348303B CN 102348303 B CN102348303 B CN 102348303B CN 201010242192 A CN201010242192 A CN 201010242192A CN 102348303 B CN102348303 B CN 102348303B
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Abstract
The invention provides a driving circuit, a light modulator and a light modulating method of a light-emitting diode. The driving circuit comprises a power supply unit which provides a voltage and a driving current to a string of light-emitting diodes, a light modulating unit which is used for regulating the work cycle of an original light modulating signal according to the driving current and an ideal current so as to generate a light modulating signal, and a current sink coupled to the string of light-emitting diodes, and the work cycle of the driving current is adjusted according to the light modulating signal. According to the invention, the brightness of the light-emitting diodes can be accurately controlled through adjusting the work cycle of the driving current, and the defects of the prior art that the brightness of the light-emitting diodes can not be accurately controlled and the picture quality of a display is poor are overcome.
Description
Technical field
The present invention has about a kind of drive circuit of the precisely light-emitting diode of light modulation, the precisely dimmer of light modulation and the method for light modulation, espespecially by adjusting work period of drive current of light-emitting diode, with the drive circuit of the light-emitting diode of accurate light modulation, the precisely dimmer of light modulation and the method for light modulation.
Background technology
In general, the mode of back light source in LED light modulation can be divided into burst mode (burst mode) and two kinds of continuous modes (continuous mode).Wherein the dimming mode of continuous mode is the peak value of adjusting LED current.But because the dimming mode of continuous mode can affect the optical characteristics of display screen, therefore the dimming mode of general light-emitting diode is taking burst mode as main.
The dimming mode of burst mode is mainly according to pulse width modulation light modulation (PWM dimming) signal, controls the open and close of the drive current that drives light-emitting diode, then according to the mean value of drive current, controls the brightness of light-emitting diode.Because the brightness of light-emitting diode and the mean value of drive current are directly proportional, thus the work period (duty cycle) of pulse width modulation dim signal adjusted ideally, can the linear brightness of adjusting light-emitting diode.But due to the genetic prerequisite of circuit and the design of electromagnetic interference consideration, in the time that drive current opens and closes, drive current can experience one period of rise time (rising time) and just reach stable state fall time (falling time).Please refer to Fig. 1, Fig. 1 is rise time and the fall time of explanation due to drive current, causes the actual mean value of drive current to be not equal to the schematic diagram of the mean value of ideal current.As shown in Figure 1, because the actual mean value of drive current is not equal to the mean value of ideal current, so the work period of the actual mean value of drive current and the dim signal of pulse width modulation is non-linear relation, the work period that results in the brightness of light-emitting diode and the dim signal of pulse width modulation is non-linear relation.Therefore, in the prior art, the brightness of light-emitting diode is precisely to control, and the image quality of display is poor.
Summary of the invention
The object of the present invention is to provide a kind of drive circuit of light-emitting diode, the brightness that is intended to solve the light-emitting diode existing in prior art is precisely to control, and the poor problem of the image quality of display.
The present invention is achieved in that a kind of drive circuit of light-emitting diode, and this drive circuit comprises an electric power supply unit, a string light-emitting diode, an electric current groove and a light modulation unit; This electric power supply unit has an input, and for receiving an alternating voltage/or direct voltage, an output, for providing a direct voltage and a drive current; This string light-emitting diode comprises the light-emitting diode of at least one series connection, has a first end and couple the output of this electric power supply unit, for receiving this direct voltage and this drive current, and one second end; This electric current groove is coupled to the second end of this string light-emitting diode, there is a brightness adjustment control end, be used for receiving a dim signal, there is a reference voltage input terminal, for input reference voltage, comprise a setting resistance, for generating ideal current with described reference voltage, there is a signal output part, for exporting described ideal current; And this light modulation unit for work period of adjusting an original dim signal according to this drive current and described ideal current to produce this dim signal, be specially, in the time that the mean value of drive current is less than the mean value of described ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of described ideal current, reduce the work period of drive current; This light modulation unit has a first input end, be coupled to the second end of this string light-emitting diode, for this drive current of sensing, one second input, for receiving this original dim signal, one the 3rd input, couple this signal output part, for this ideal current of sensing, and an output, for exporting this dim signal.
Another object of the present invention is to provide a kind of drive circuit of light-emitting diode, this drive circuit comprises an electric power supply unit, go here and there light-emitting diode, an electric current groove and a light modulation unit more; This electric power supply unit has an input, and for receiving an alternating voltage/or direct voltage, an output, for providing a direct voltage and a drive current; Every a string light-emitting diode in this many strings light-emitting diode comprises the light-emitting diode of at least one series connection, wherein this every a string light-emitting diode has a first end and couples the output of this electric power supply unit, be used for receiving this direct voltage and this drive current, and one second end; This electric current groove is coupled to the second end of this every a string light-emitting diode, there is a brightness adjustment control end, be used for receiving a dim signal, there is a reference voltage input terminal, for input reference voltage, comprise a setting resistance, for generating ideal current with described reference voltage, there is a signal output part, for exporting described ideal current; And this light modulation unit for work period of adjusting an original dim signal according to this drive current and described ideal current to produce this dim signal, be specially, in the time that the mean value of drive current is less than the mean value of described ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of described ideal current, reduce the work period of drive current; This light modulation unit has a first input end, be coupled to the second end of a string light-emitting diode, for this drive current of sensing, one second input, for receiving this original dim signal, one the 3rd input, couple this electric current groove, for this ideal current of sensing, and an output, for exporting this dim signal.
Another object of the present invention is to provide a kind of dimmer, this dimmer comprises one first sensing circuit, one second sensing circuit, an adder, a light modulation compensator and a pulse duration dim signal generator; This first sensing circuit, for according to a drive current, produces a virtual voltage mean value; This second sensing circuit, for according to an ideal current and an original dim signal, produces a desired voltage mean value; This adder is coupled to this first sensing circuit and this two sensing circuit, for generation of the difference between this desired voltage mean value and this virtual voltage mean value; This light modulation compensator is coupled to this adder, for according to this difference, produces a DC offset value; And this pulse duration dim signal generator is coupled to this light modulation compensator and this electric current groove, for according to this DC offset value, produce a dim signal; In the time that the mean value of drive current is less than the mean value of ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of ideal current, reduce the work period of drive current.
A kind of method that another object of the present invention is to provide light modulation, the method comprises the following steps: according to a drive current, produce a virtual voltage mean value; According to an ideal current and an original dim signal, produce a desired voltage mean value; According to this desired voltage mean value and this virtual voltage mean value, produce the difference between this desired voltage mean value and this virtual voltage mean value; According to after this difference, produce a DC offset value; According to after this DC offset value, produce a dim signal; And according to this dim signal, adjust the work period of this drive current, be specially, in the time that the mean value of drive current is less than the mean value of ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of ideal current, reduce the work period of drive current; Wherein this drive current is for driving a string light-emitting diode.
Drive circuit, the precisely dimmer of light modulation and the method for light modulation of a kind of precisely light-emitting diode of light modulation provided by the present invention, according to the drive current of a string light-emitting diode and an ideal current, adjust the work period of an original dim signal to produce a dim signal.Then, the switch of an electric current groove can, according to this dim signal, be adjusted the work period of this drive current.Therefore, drive circuit, the precisely dimmer of light modulation and the method for light modulation of the precisely light-emitting diode of light modulation provided by the invention can be by adjusting the work period of this drive current, precisely control the brightness of at least a string light-emitting diode, promote the image quality of display.
Brief description of the drawings
Fig. 1 is that prior art is rise time and the fall time of explanation due to drive current, causes the actual mean value of drive current to be not equal to the schematic diagram of the mean value of ideal current.
Fig. 2 is the precisely schematic diagram of the drive circuit of the light-emitting diode of light modulation of one embodiment of the invention explanation.
Fig. 3 A and Fig. 3 B illustrate in the time that the mean value of drive current is less than the mean value of ideal current, increase the schematic diagram of the work period of drive current.
Fig. 4 A and Fig. 4 B illustrate in the time that the mean value of drive current is greater than the mean value of ideal current, reduce the schematic diagram of the work period of drive current.
Fig. 5 is the precisely schematic diagram of the drive circuit of the light-emitting diode of light modulation of another embodiment of the present invention explanation.
Fig. 6 is the precisely schematic diagram of the dimmer of light modulation of another embodiment of the present invention explanation.
Fig. 7 is the precisely flow chart of the method for light modulation of another embodiment of the present invention explanation.
Embodiment
In order to make object of the present invention, technical scheme and beneficial effect clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
Please refer to Fig. 2, Fig. 2 is the precisely schematic diagram of the drive circuit 200 of the light-emitting diode of light modulation of one embodiment of the invention explanation.Drive circuit 200 comprises an electric power supply unit 202, a string light-emitting diode 204, an electric current groove (current sink) 206 and a light modulation unit 208.It is for receiving an alternating voltage V that electric power supply unit 202 has an input
aCan or direct voltage V
dC, an output is for a driving voltage V is provided
oan and drive current I
lED; A string light-emitting diode 204 comprises the light-emitting diode of at least one series connection, and light-emitting diode 204 has a first end and be coupled to the output of electric power supply unit 202, is for receiving direct voltage V
oan and drive current I
lED; Electric current groove 206 is coupled to the second end of light-emitting diode 204, and it is for receiving a dim signal D that electric current groove 206 has a brightness adjustment control end
lED, in addition, electric current groove 206 comprises a reference voltage V
refwith a setting resistance 2062, electric current groove 206 can be according to reference voltage V
refwith setting resistance 2062, produce an ideal current I
ideal.Light modulation unit 208 is for according to drive current I
lEDand ideal current I
idealadjust an original dim signal OD
lEDwork period (duty ratio) to produce dim signal D
lED.It is the second end that is coupled to light-emitting diode 204 that light modulation unit 208 has a first input end, for sensing drive current I
lED, one second input is for receiving original dim signal OD
lED, one the 3rd input couples electric current groove 206, for sensing ideal current I
ideal, and an output is used for exporting dim signal D
lED, wherein dim signal D
lEDwith original dim signal OD
lEDfor pulse width modulation signal, and drive current I
lEDit is a pulse width modulation electric current.
Light modulation unit 208 comprises one first sensing circuit 2082, one second sensing circuit 2084, an adder 2086, a light modulation compensator 2088 and a pulse duration dim signal generator 2090.The first sensing circuit 2082 comprises one first resistance 20822 and one first average circuit 20824, and wherein the first average circuit 20824 couples the first resistance 20822.The first sensing circuit 2082 is by the first input end sensing drive current I of light modulation unit 208
lEDafter, the first resistance 20822 is according to drive current I
lED, produce a virtual voltage V
lED(pulse width modulation voltage), and the first average circuit 20824 is according to virtual voltage V
lED, produce a virtual voltage mean value
the second sensing circuit 2084 comprises one second resistance 20842, a multiplier 20844 and one second average circuit 20846, and wherein multiplier 20844 is coupled to the second resistance 20842, the second average circuits 20846 and couples multiplier 20844.The second sensing circuit 2084 is by the 3rd input sensing ideal current I of light modulation unit 208
idealafter, the second resistance 20842 is according to ideal current I
ideal, produce a desired voltage V
ideal; Multiplier 20844 receives original dim signal OD by the second input of light modulation unit 208
lED, and according to desired voltage V
idealthe original dim signal OD of modulation (modulate)
lED, to produce a desirable dim signal; The second average circuit 20846 is coupled to multiplier 20844, according to desirable dim signal, produces desired voltage mean value
Adder 2086 is coupled to the first sensing circuit 2082 and the second sensing circuit 2084, for generation of desired voltage mean value
with virtual voltage mean value
between difference diff; Light modulation compensator 2088 is coupled to adder 2086, for produce a DC offset value C according to difference diff
pWM; Pulse duration dim signal generator 2090 is coupled to light modulation compensator 2088 and electric current groove 206, for according to DC offset value C
pWM, produce dim signal D
lED.The brightness adjustment control end of electric current groove 206 is coupled to the output of light modulation unit 208, for receiving dim signal D
lED, electric current groove 206 also comprises a switch 2064, for according to dim signal D
lED, adjust drive current I
lEDwork period.
Please refer to Fig. 3 A and Fig. 3 B, Fig. 3 A is explanation drive current I
lEDwork period before adjustment and ideal current I
idealthe schematic diagram of work period, Fig. 3 B is explanation drive current I
lEDwork period after adjustment and ideal current I
idealthe schematic diagram of work period.As shown in Figure 3A, electric current groove 206 is not also according to dim signal D
lED, adjust drive current I
lEDwork period time because drive current I
lEDimperfection (thering is rise time and fall time), so cause the mean value of ideal current
mean value with drive current
different.As shown in Figure 3 B, electric current groove 206 is according to dim signal D
lEDadjust drive current I
lEDwork period, make to adjust the mean value of drive current later
mean value with ideal current
identical.
In Fig. 3 A and Fig. 3 B, the mean value of drive current
be less than the mean value of ideal current
so increase drive current I
lEDwork period.Please refer to Fig. 4 A and Fig. 4 B, Fig. 4 A and Fig. 4 B are the mean value of explanation when drive current
be greater than the mean value of ideal current
time, reduce drive current I
lEDthe schematic diagram of work period.Therefore, by increasing or reduce drive current I
lEDwork period, can make the mean value of drive current identical with the mean value of ideal current, reach the object of the accurate light modulation of high linearity.
Please refer to Fig. 5, Fig. 5 is the precisely schematic diagram of the drive circuit 500 of the light-emitting diode of light modulation of another embodiment of the present invention explanation.Drive circuit 500 comprises an electric power supply unit 502, go here and there light-emitting diode 504, an electric current groove (current sink) 506 and a light modulation unit 508 more.Electric current groove 506 comprises a reference voltage V
ref, one set resistance 5062 and multiple switch 5064.Light modulation unit 508 comprises one first sensing circuit 5082, one second sensing circuit 5084, an adder 5086, a light modulation compensator 5088 and a pulse duration dim signal generator 5090.The first sensing circuit 5082 comprises one first resistance 50822 and one first average circuit 50824; The second sensing circuit 5084 comprises one second resistance 50842, a multiplier 50844 and one second average circuit 50846.The difference of drive circuit 500 and drive circuit 200 is that drive circuit 500 has many string light-emitting diodes 504, the corresponding switch 5064 of every a string light-emitting diode 504.Because material, the size of many string light-emitting diodes 504 are identical, therefore the rise time of the drive current of every a string light-emitting diode 504 is rough the same with fall time.So the first input end of light modulation unit 508 is only coupled to the second end of a string light-emitting diode 504, for sensing drive current I
lED, and the dim signal D of output
lEDbut be each switch 5064 being sent in multiple switches 5064 of electric current groove 506.5064, multiple switches are according to dim signal D
lED, adjust work period of the drive current of every a string light-emitting diode 504.In addition, all the other operating principles of drive circuit 500 are all identical with drive circuit 200, do not repeat them here.
Please refer to Fig. 6, Fig. 6 is the precisely schematic diagram of the dimmer 600 of light modulation of another embodiment of the present invention explanation.Dimmer 600 comprises one first sensing circuit 602, one second sensing circuit 604, an adder 606, a light modulation compensator 608 and a pulse duration dim signal generator 610.The first sensing circuit 602 comprises one first resistance 6022 and one first average circuit 6024; The second sensing circuit 604 comprises one second resistance 6042, a multiplier 6044 and one second average circuit 6046.The operating principle of dimmer 600 is all identical with light modulation unit 208,508, does not repeat them here.
Please refer to Fig. 7, Fig. 7 is the precisely flow chart of the method for light modulation of another embodiment of the present invention explanation.The method of Fig. 7 is to utilize the drive circuit 200 of Fig. 2 to illustrate, detailed step is as follows:
Step 70: start;
Step 72: the first sensing circuit 2082, according to drive current ILED, produces virtual voltage mean value
step 74: the second sensing circuit 2084 is according to ideal current I
idealand original dim signal OD
lED, produce desired voltage mean value
Step 76: adder 2086 is according to desired voltage mean value
with virtual voltage mean value
produce desired voltage mean value
with virtual voltage mean value
between difference diff;
Step 78: light modulation compensator 2088, according to difference diff, produces DC offset value C
pWM;
Step 80: pulse duration dim signal generator 2090 is according to DC offset value C
pWM, produce dim signal D
lED;
Step 82: the switch 2064 of electric current groove 206 is according to dim signal D
lED, adjust drive current I
lEDwork period;
Step 84: finish.
Wherein drive current I
lEDbe used for driving a string light-emitting diode 204.In addition, in step 72, also comprise that the first resistance 20822 is according to drive current I
lED, produce virtual voltage V
lED(pulse width modulation voltage), and the first average circuit 20824 is according to virtual voltage V
lED, produce virtual voltage mean value
in step 74, also comprise that the second resistance 20842 is according to ideal current I
ideal, produce desired voltage V
ideal; Multiplier 20844 receives original dim signal OD by the second input of light modulation unit 208
lED, and according to desired voltage V
idealthe original dim signal OD of modulation (modulate)
lED, to produce desirable dim signal; The second average circuit 20846, according to desirable dim signal, produces desired voltage mean value
In sum, drive circuit, the precisely dimmer of light modulation and the method for light modulation of the precisely light-emitting diode of light modulation provided by the invention, according to the drive current of light-emitting diode and an ideal current, adjust the work period (duty ratio) of an original dim signal to produce dim signal.Then, the switch of electric current groove can, according to dim signal, be adjusted the work period of drive current.So, drive circuit, the precisely dimmer of light modulation and the method for light modulation of the precisely light-emitting diode of light modulation provided by the invention can be by adjusting the work period of drive current, precisely control the brightness of light-emitting diode, improve in prior art, cannot precisely control the brightness of light-emitting diode, and the poor shortcoming of the image quality of display.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.
Claims (15)
1. a drive circuit for light-emitting diode, is characterized in that, described drive circuit comprises:
One electric power supply unit, has an input, and for receiving an alternating voltage/or direct voltage, an output, for providing a direct voltage and a drive current;
A string light-emitting diode, comprises the light-emitting diode of at least one series connection, has a first end and couple the output of described electric power supply unit, for receiving described direct voltage and described drive current, and one second end;
One electric current groove, be coupled to the second end of described a string light-emitting diode, there is a brightness adjustment control end, be used for receiving a dim signal, there is a reference voltage input terminal, for input reference voltage, comprise a setting resistance, for generating ideal current with described reference voltage, there is a signal output part, for exporting described ideal current; And
One light modulation unit, for work period of adjusting an original dim signal according to described drive current and described ideal current to produce described dim signal, be specially, in the time that the mean value of drive current is less than the mean value of described ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of described ideal current, reduce the work period of drive current; Described light modulation unit has a first input end, be coupled to the second end of described a string light-emitting diode, for drive current described in sensing, one second input, for receiving described original dim signal, one the 3rd input, couple described signal output part, for ideal current described in sensing, and an output, for exporting described dim signal.
2. drive circuit as claimed in claim 1, is characterized in that, described light modulation unit comprises:
One first sensing circuit, for according to described drive current, produces a virtual voltage mean value;
One second sensing circuit, for according to described ideal current and described original dim signal, produces a desired voltage mean value;
One adder, is coupled to described the first sensing circuit and described the second sensing circuit, for generation of the difference between described desired voltage mean value and described virtual voltage mean value;
One light modulation compensator, is coupled to described adder, for producing a DC offset value according to described difference;
And
One pulse duration dim signal generator, is coupled to described light modulation compensator and described electric current groove, for producing described dim signal according to described DC offset value.
3. drive circuit as claimed in claim 2, is characterized in that, described the first sensing circuit comprises:
One first resistance, for according to described drive current, produces a virtual voltage; And
One first average circuit, couples described the first resistance, for according to described virtual voltage, produces described virtual voltage mean value;
Described the second sensing circuit comprises:
One second resistance, for according to described ideal current, produces a desired voltage;
One multiplier, is coupled to described the second resistance, for according to original dim signal described in described desired voltage modulation, to produce a desirable dim signal; And
One second average circuit, couples described multiplier, for according to described desirable dim signal, produces described desired voltage mean value.
4. drive circuit as claimed in claim 1, is characterized in that, described dim signal and described original dim signal are pulse width modulation signal; Described drive current is a pulse width modulation electric current.
5. drive circuit as claimed in claim 1, is characterized in that, described electric current groove also comprises a reference voltage and a setting resistance, for according to described reference voltage and described setting resistance, produces described ideal current; Or described electric current groove also comprises a switch, for according to described dim signal, adjust the work period of described drive current.
6. a drive circuit for light-emitting diode, is characterized in that, described drive circuit comprises:
One electric power supply unit, has an input, and for receiving an alternating voltage/or direct voltage, an output, for providing a direct voltage and a drive current;
Many string light-emitting diodes, every a string light-emitting diode comprises the light-emitting diode of at least one series connection, described every a string light-emitting diode has a first end and couples the output of described electric power supply unit, for receiving described direct voltage and described drive current, and one second end;
One electric current groove, be coupled to the second end of described every a string light-emitting diode, there is a brightness adjustment control end, be used for receiving a dim signal, there is a reference voltage input terminal, for input reference voltage, comprise a setting resistance, for generating ideal current with described reference voltage, there is a signal output part, for exporting described ideal current; And
One light modulation unit, for work period of adjusting an original dim signal according to described drive current and described ideal current to produce described dim signal, be specially, in the time that the mean value of drive current is less than the mean value of described ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of described ideal current, reduce the work period of drive current; Described light modulation unit has a first input end, be coupled to the second end of a string light-emitting diode, for drive current described in sensing, one second input, for receiving described original dim signal, one the 3rd input, couple described signal output part, for ideal current described in sensing, and an output, for exporting described dim signal.
7. drive circuit as claimed in claim 6, is characterized in that, described light modulation unit comprises:
One first sensing circuit, for according to described drive current, produces a virtual voltage mean value;
One second sensing circuit, for according to described ideal current and described original dim signal, produces a desired voltage mean value;
One adder, is coupled to described the first sensing circuit and described the second sensing circuit, for generation of the difference between described desired voltage mean value and described virtual voltage mean value;
One light modulation compensator, is coupled to described adder, for according to described difference, produces a DC offset value; And
One pulse duration dim signal generator, is coupled to described light modulation compensator and described electric current groove, for according to described DC offset value, produces described dim signal.
8. drive circuit as claimed in claim 7, is characterized in that, described the first sensing circuit comprises:
One first resistance, for according to described drive current, produces a virtual voltage; And
One first average circuit, couples described the first resistance, for according to described virtual voltage, produces described virtual voltage mean value;
Described the second sensing circuit comprises:
One second resistance, for according to described ideal current, produces a desired voltage;
One multiplier, is coupled to described the second resistance, for according to original tune described in described desired voltage modulation
Light signal, to produce a desirable dim signal; And
One second average circuit, for according to described desirable dim signal, produces described desired voltage mean value.
9. drive circuit as claimed in claim 6, is characterized in that, described dim signal and described original dim signal are pulse width modulation signal; Described drive current is a pulse width modulation electric current.
10. drive circuit as claimed in claim 6, is characterized in that, described electric current groove also comprises a reference voltage and a setting resistance, for according to described reference voltage and described setting resistance, produces described ideal current; Or described electric current groove also comprises a switch, for according to described dim signal, adjust the work period of described drive current.
11. 1 kinds of dimmers, is characterized in that, described dimmer comprises:
One first sensing circuit, for according to a drive current, produces a virtual voltage mean value;
One second sensing circuit, for according to an ideal current and an original dim signal, produces a desired voltage mean value;
One adder, is coupled to described the first sensing circuit and described two sensing circuits, for generation of the difference between described desired voltage mean value and described virtual voltage mean value;
One light modulation compensator, is coupled to described adder, for according to described difference, produces a DC offset value; And
One pulse duration dim signal generator, is coupled to described light modulation compensator and described electric current groove, for according to described DC offset value, produces a dim signal;
In the time that the mean value of drive current is less than the mean value of ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of ideal current, reduce the work period of drive current.
12. dimmers as claimed in claim 11, is characterized in that, described the first sensing circuit comprises:
One first resistance, for according to described drive current, produces a virtual voltage; And
One first average circuit, couples described the first resistance, for according to described virtual voltage, produces described virtual voltage mean value;
Described the second sensing circuit comprises:
One second resistance, for according to described ideal current, produces a desired voltage;
One multiplier, is coupled to described the second resistance, for according to original dim signal described in described desired voltage modulation, to produce a desirable dim signal; And
One second average circuit, for according to described desirable dim signal, produces described desired voltage mean value.
13. dimmers as claimed in claim 11, is characterized in that, described dim signal and described original dim signal are pulse width modulation signal; Described drive current is a pulse width modulation electric current; Described dim signal is sent to the switch of an electric current groove, and described switch, according to described dim signal, is adjusted the work period of the described drive current for driving a string light-emitting diode.
The method of 14. 1 kinds of light modulations, is characterized in that, said method comprising the steps of:
According to a drive current, produce a virtual voltage mean value;
According to an ideal current and an original dim signal, produce a desired voltage mean value;
According to described desired voltage mean value and described virtual voltage mean value, produce the difference between described desired voltage mean value and described virtual voltage mean value;
According to after described difference, produce a DC offset value;
According to after described DC offset value, produce a dim signal; And
According to described dim signal, adjust the work period of described drive current; Be specially, in the time that the mean value of drive current is less than the mean value of ideal current, increase the work period of drive current, in the time that the mean value of drive current is greater than the mean value of ideal current, reduce the work period of drive current;
Described drive current is used for driving a string light-emitting diode.
15. methods as claimed in claim 14, is characterized in that, described method also comprises:
According to described drive current, produce a virtual voltage;
According to described virtual voltage, produce described virtual voltage mean value;
According to described ideal current, produce a desired voltage;
According to described desired voltage, original dim signal described in modulation, to produce a desirable dim signal; And according to described desirable dim signal, produce described desired voltage mean value.
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| CN201010242192.9A CN102348303B (en) | 2010-07-30 | 2010-07-30 | Driving circuit, light modulator and light modulating method of light-emitting diode |
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| CN201010242192.9A CN102348303B (en) | 2010-07-30 | 2010-07-30 | Driving circuit, light modulator and light modulating method of light-emitting diode |
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| CN101668363A (en) * | 2008-09-05 | 2010-03-10 | 艾默龙电子科技（嘉兴）有限公司 | High-efficiency drive control method for LED |
| TW201206235A (en) * | 2010-07-22 | 2012-02-01 | Chunghwa Picture Tubes Ltd | Light emitting diode driving circuit, dimmer and method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101668363A (en) * | 2008-09-05 | 2010-03-10 | 艾默龙电子科技（嘉兴）有限公司 | High-efficiency drive control method for LED |
| TW201206235A (en) * | 2010-07-22 | 2012-02-01 | Chunghwa Picture Tubes Ltd | Light emitting diode driving circuit, dimmer and method thereof |
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