CN105263209B - To dim the controller of light emitting diode and method - Google Patents
To dim the controller of light emitting diode and method Download PDFInfo
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- CN105263209B CN105263209B CN201410270531.2A CN201410270531A CN105263209B CN 105263209 B CN105263209 B CN 105263209B CN 201410270531 A CN201410270531 A CN 201410270531A CN 105263209 B CN105263209 B CN 105263209B
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Abstract
The invention discloses a kind of to dim the controller of light emitting diode and method.The controller includes pulse width modulation pin, low-pass filter, frequency detecting unit and control signal generator module.The pulse width modulation signal that the low-pass filter is generated according to microcontroller generates direct current signal.The frequency detecting unit generates logical value according to critical value and the pulse width modulation signal.The control signal generator module generates switch control signal to the first switch for the light emitting diode of connecting according to the direct current signal, the logical value, reference voltage and the pulse width modulation signal.When the frequency of the pulse width modulation signal is less than the critical value, the controller enters digital dimming mode；When the frequency of the pulse width modulation signal is higher than the critical value, the controller enters analog dimming mode.Therefore, the present invention, which is not necessary to accordingly to change printed circuit board and the present invention, will not increase additional burden.
Description
Technical field
The present invention relates to can be according to pulse width to dim the controller of light emitting diode and method more particularly to one kind
The frequency of modulating signal same pin realize digital dimming mode and analog dimming mode dimming light emitting diode
Controller and method.
Background technology
Digital dimming mode applied to dimming light-emitting diode is respectively provided with the advantages of respective with analog dimming mode.Example
Such as, analog dimming mode has following advantages：Firstth, the preferable color saturation of analog dimming mode；Secondth, simulation light modulation mould
The power consumption of formula is relatively good, so analog dimming mode has larger product design space for new energy regulation (level-6)；The
3rd, analog dimming mode will not generate water ripples, so analog dimming mode is more friendly to human eye, that is to say, that have marketing topic
Material；4th, the frequency of electromagnetic wave caused by analog dimming mode is fallen in career employee association of Sweden (Swedish
Federation of Professional Employees, TCO) institute's specification range (1Hz-30kHz)；And digital dimming mould
Formula has following advantages：Firstth, digital dimming mode has preferable contrast；Secondth, digital dimming mode is easier to control
Colour temperature and color Times；Third, the brightness of light emitting diode and driving current according to caused by digital dimming mode are linear changes
Change.
In the prior art, because the digital dimming mode applied to dimming light-emitting diode is distinguished with analog dimming mode
Have the advantages that it is respective, so while user can by external signal set light emitting diode driving circuit operation number adjust
Optical mode or analog dimming mode, but the driving circuit of light emitting diode must have different pins to receive corresponding to digital dimming mould
The external signal or printed circuit board of formula and analog dimming mode are accordingly changed, cause the prior art for user and
Speech is not a good selection.
Invention content
The first embodiment of the present invention discloses a kind of dimming the controller of light emitting diode.The controller includes one
Pulse width modulation pin, a low-pass filter, a frequency detecting unit and a control signal generator module.The pulse width
Modulation pin is to receive the pulse width modulation signal of microcontroller generation.The low-pass filter is to according to institute
Pulse width modulation signal is stated, generates a direct current signal.The frequency detecting unit is to according to a critical value and the arteries and veins
Width modulation signal is rushed, generates a logical value.It is described control signal generator module be coupled to the low-pass filter with it is described
Frequency detecting unit, to be believed according to the direct current signal, the logical value, a reference voltage and the pulse width modulation
Number, a switch control signal is generated to the first switch for the light emitting diode of connecting, wherein the first switch is according to institute
State switch control signal open and close.When the frequency of the pulse width modulation signal is less than the critical value, the control
Device processed is the institute into a digital dimming mode and when the frequency of the pulse width modulation signal is higher than the critical value
It is to enter an analog dimming mode to state controller.
The second embodiment of the present invention disclose it is a kind of to dim the method for light emitting diode, wherein applied to the method
A controller include a pulse width modulation pin, a low-pass filter, a frequency detecting unit and one control signal generate
Module.The method includes the pulse width modulation signals that the pulse width modulation pin receives microcontroller generation；Institute
Low-pass filter is stated according to the pulse width modulation signal, generates a direct current signal；The frequency detecting unit faces according to one
Dividing value and the pulse width modulation signal generate a logical value；It is described control signal generator module according to the direct current signal,
The logical value, a reference voltage and the pulse width modulation signal generate a switch control signal to described shine of connecting
The first switch of diode, wherein the first switch is opened and closed according to the switch control signal；When the pulse
When the frequency of width modulation signal is less than the critical value, the controller is into a digital dimming mode and when described
When the frequency of pulse width modulation signal is higher than the critical value, the controller is to enter an analog dimming mode.
The third embodiment of the present invention disclose it is a kind of to dim the method for light emitting diode, wherein the light emitting diode
It is that a controller applied to a liquid crystal display and applied to the method includes a pulse width modulation pin, one low
Bandpass filter, a frequency detecting unit and a control signal generator module, wherein the control signal generator module includes more than one
Task device, a logic unit, a transmission unit, a second switch and a comparator.The method includes the pulse width tune
Become pin and receive microcontroller pulse width modulation signal according to caused by the video signal that the liquid crystal display receives；
The low-pass filter generates a direct current signal according to the pulse width modulation signal；The frequency detecting unit is according to one
Critical value and the pulse width modulation signal generate a logical value；The control signal generator module is believed according to the direct current
Number, the logical value, a reference voltage and the pulse width modulation signal, generate a switch control signal to the hair of connecting
The first switch of optical diode, wherein the first switch is opened and closed according to the switch control signal；When the arteries and veins
When rushing the frequency of width modulation signal less than the critical value, the controller is into a digital dimming mode and works as institute
When stating the frequency of pulse width modulation signal higher than the critical value, the controller is to enter an analog dimming mode.
The present invention discloses a kind of dimming the controller of light emitting diode and method.The controller and the method are
According to pulse width modulation signal and a critical value that a microcontroller generates, determine the controller operation in a digital dimming
Pattern or an analog dimming mode, so the present invention only needs a pin to receive the pulse width modulation that the microcontroller generates
Signal, you can the controller is made to switch between the digital dimming mode and the analog dimming mode.Therefore, compared to
The prior art because the present invention is the pulse width modulation signal and the critical value generated according to the microcontroller, determines
The controller operation is in the digital dimming mode or the analog dimming mode, so the present invention is not necessary to accordingly change one
Printed circuit board.In addition, the present invention is the pulse width modulation signal and the critical value generated according to the microcontroller, certainly
The fixed controller operation is in the digital dimming mode or the analog dimming mode, so the present invention can't increase additionally
Burden.
Description of the drawings
It is a kind of dimming the schematic diagram of the controller of light emitting diode that Fig. 1 is that the first embodiment of the present invention discloses.
Fig. 2 is the relation schematic diagram for the driving current for illustrating pulse width modulation signal and flowing through light emitting diode.Fig. 3 A
It is a kind of dimming the flow chart of the method for light emitting diode to be that the second embodiment of the present invention discloses with Fig. 3 B.
It is a kind of dimming the flow of the method for light emitting diode that Fig. 4 A and Fig. 4 B are that the third embodiment of the present invention discloses
Figure.
Wherein, the reference numerals are as follows：
100 light emitting diodes
200 controllers
202 pulse width modulation pins
204 low-pass filters
206 frequency detecting units
208 control signal generator modules
210 microcontrollers
212 first switches
214 grid pins
216 power supply changeover devices
2082 multiplexers
2084 logic units
2086 transmission units
2088 second switches
2090 comparators
DS direct current signals
ILED driving currents
ILEDMAX maximum drive currents
LV logical values
First logical value
PWMS pulse width modulation signals
Rp pulse width modulation signal
SEC secondary sides
SCS switch control signals
SV sensing voltages
VOUT output voltages
VREF reference voltages
300-328,400-428 step
Specific embodiment
Please refer to Fig. 1, it is a kind of dimming the control of light emitting diode 100 that Fig. 1 is that the first embodiment of the present invention discloses
The schematic diagram of device 200, wherein the secondary side SEC of a power supply changeover device 216 is to generate an output voltage VO UT to send out to drive
Optical diode 100, and controller 200 is the secondary side SEC positioned at power supply changeover device 216.As shown in Figure 1, controller 200 includes
One pulse width modulation pin 202, a low-pass filter 204, a frequency detecting unit 206 and a control signal generator module
208.As shown in Figure 1, pulse width modulation pin 202 is to receive the pulse width modulation letter of a microcontroller 210 generation
Number PWMS.Low-pass filter 204 is coupled to pulse width modulation pin 202, to according to pulse width modulation signal PWMS,
Generate a direct current signal DS.Frequency detecting unit 206 is coupled to pulse width modulation pin 202, to according to a critical value
With pulse width modulation signal PWMS, a logical value LV is generated.For example, face when the frequency of pulse width modulation signal PWMS is less than
During dividing value, frequency detecting unit 206 generates a logical value " 0 " and faces when the frequency of pulse width modulation signal PWMS is higher than
During dividing value, frequency detecting unit 206 generates a logical value " 1 ".But the present invention is not limited to work as pulse width modulation signal
When the frequency of PWMS is less than critical value, frequency detecting unit 206 generates logical value " 0 " and works as pulse width modulation signal
When the frequency of PWMS is higher than critical value, frequency detecting unit 206 generates logical value " 1 ".Control signal generator module 208 is coupled to
In low-pass filter 204 and frequency detecting unit 206, to according to direct current signal DS, logical value LV, a reference voltage VREF and
Pulse width modulation signal PWMS generates the first switch 212 of a switch control signal SCS extremely series connection light emitting diodes 100,
Middle first switch 212 is to be opened and closed according to switch control signal SCS, and switch control signal SCS is connect by a grid
Foot 214 is sent to first switch 212.
As shown in Figure 1, control signal generator module 208 includes a multiplexer 2082, a logic unit 2084, one is transmitted
Unit 2086, a second switch 2088 and a comparator 2090.As shown in Figure 1, multiplexer 2082 is coupled to low-pass filter
204 with frequency detecting unit 206, to according to logical value LV, output reference voltage VREF or direct current signal DS, wherein working as pulse
When the frequency of width modulation signal PWMS is less than critical value, 2082 output reference voltage VREF of multiplexer and when pulse is wide
When spending the frequency of modulating signal PWMS higher than critical value, multiplexer 2082 exports direct current signal DS；Logic unit 2084 couples
It is wide to receive pulse width modulation signal PWMS and logical value LV and one rp pulse of output in frequency detecting unit 206
Spend modulating signalOr the first logical value with logical value LV reverse phasesWherein when pulse width modulation signal PWMS's
When frequency is less than critical value, logic unit 2084 exports rp pulse width modulation signalAnd when pulse width tune
When the frequency of varying signal PWMS is higher than critical value, logic unit 2084 exports the first logical valueTransmission unit 2086 is coupled to
Multiplexer 2082 and logic unit 2084, it is anti-to one of output reference voltage VREF and direct current signal DS and output
Phase pulse width modulation signalWith the first logical valueOne of them；Second switch 2088 is coupled to transmission unit
2086, to according to rp pulse width modulation signalOr first logical valueA corresponding action is performed, wherein
When second switch 2088 opens (ON), first switch 212 closes (OFF) and when second switch 2088 is closed, and first opens
212 are closed to open；Comparator 2090 is coupled to transmission unit 2086, to according to reference voltage VREF and direct current signal DS wherein it
One and one sensing voltage SV generates switch control signal SCS to first switch 212.
As shown in Figure 1, when the frequency of pulse width modulation signal PWMS is less than critical value, the output ginseng of multiplexer 2082
Voltage VREF and frequency detecting unit 206 are examined according to critical value and the frequency of pulse width modulation signal PWMS, generates logic
It is worth " 0 ".Logic unit 2084 is according to logical value " 0 " and pulse width modulation signal PWMS, output rp pulse width modulation letter
Number2086 output reference voltage VREF of transmission unit and output rp pulse width modulation signalSecond
Switch 2088 is according to rp pulse width modulation signalIt opens and closes, wherein when second switch 2088 is opened, the
One switch 212 is closed and when second switch 2088 is closed, and first switch 212 is opened；Comparator 2090 is according to reference voltage
VREF and sensing voltage SV generates switch control signal SCS to first switch 212.Because second switch 2088 is according to reverse phase
Pulse width modulation signalIt opens and closes, so first switch 212 also can be according to rp pulse width modulation signalIt opens and closes, controller 200 is caused to enter a digital dimming mode.Therefore, as pulse width modulation signal PWMS
Frequency be less than critical value when, controller 200 be enter digital dimming mode, that is to say, that when comparator 2090 according to reference to electricity
VREF and sensing voltage SV is pressed, when generating switch control signal SCS to first switch 212, controller 200 is to enter digital dimming
Pattern.
As shown in Figure 1, when the frequency of pulse width modulation signal PWMS is higher than critical value, multiplexer 2082 exports directly
Signal DS and frequency detecting unit 206 are flowed according to critical value and the frequency of pulse width modulation signal PWMS, generate logical value
“1”.Logic unit 2084 is according to logical value " 1 " and pulse width modulation signal PWMS, output and the first of logical value " 1 " reverse phase
Logical value " 0 "；Transmission unit 2086 exports direct current signal DS and the first logical value of output " 0 "；Second switch 2088 is according to first
Logical value " 0 " is closed, wherein when second switch 2088 is closed, first switch 212 is opened；Comparator 2090 is according to direct current signal
DS and sensing voltage SV generates switch control signal SCS to first switch 212.Because second switch 2088 is according to the first logic
Value " 0 " is continuously off, is opened so first switch 212 is sustainable according to switch control signal SCS (corresponding to direct current signal DS),
Controller 200 is caused to enter an analog dimming mode.Therefore, when the frequency of pulse width modulation signal PWMS is higher than critical value
When, controller 200 is to enter analog dimming mode, that is to say, that when comparator 2090 is according to direct current signal DS and sensing voltage
SV, when generating switch control signal SCS to first switch 212, controller 200 is to enter analog dimming mode.
Fig. 2 is please referred to, Fig. 2 is to illustrate pulse width modulation signal PWMS and flow through the driving current of light emitting diode 100
The relation schematic diagram of ILED.As shown in Fig. 2, when the frequency of pulse width modulation signal PWMS is less than critical value, controller 200
Into digital dimming mode.If the duty ratio (duty cycle) of pulse width modulation signal PWMS is 50%, electricity is driven
The duty ratio for flowing ILED is also 50%；When the frequency of pulse width modulation signal PWMS is higher than critical value, controller 200 enters
Analog dimming mode.If the duty ratio of pulse width modulation signal PWMS is 50%, driving current ILED will be maximum drive
The 50% of streaming current ILEDMAX
In addition, the present invention, which is not limited to controller 200, only has 2 kinds of light-modulating modes, that is to say, that frequency detecting unit 206
Can corresponding logical value be generated according to the critical value more than more than one and the frequency of pulse width modulation signal PWMS.For example, work as
When the frequency of pulse width modulation signal PWMS is less than first critical value, frequency detecting unit 206 can generate a logical value
“00”；When the frequency of pulse width modulation signal PWMS is between the first critical value and the second critical value, frequency detecting is single
Member 206 can generate a logical value " 01 "；And when the frequency of pulse width modulation signal PWMS is higher than second critical value, frequency
Rate detecting unit 206 can generate a logical value " 10 ".At this point, multiplexer 2082 and logic unit 2084 can be detected according to frequency
Logical value caused by unit 206 (" 00 ", " 01 ", " 10 ") is accordingly changed, so that there are three types of light modulation moulds for the tool of controller 200
Formula.
In addition, the present invention can be when controller 200 be switched on, controller 200 is that acquiescence enters digital dimming mode or simulation
Light-modulating mode or when 200 normal operation of controller, controller 200 are according to pulse width modulation signal PWMS, switching
Digital dimming mode is to analog dimming mode or switches analog dimming mode to digital dimming mode.
It is that the second embodiment of the present invention discloses one kind to dim to please refer to Fig. 1 and Fig. 3 A and Fig. 3 B, Fig. 3 A and Fig. 3 B
The flow chart of the method for light emitting diode.The method of Fig. 3 A and Fig. 3 B are to illustrate that detailed step is such as using the controller 200 of Fig. 1
Under：
Step 300：Start；
Step 302：Pulse width modulation pin 202 receives the pulse width modulation signal PWMS that microcontroller 210 generates；
Step 304：Low-pass filter 204 generates a direct current signal DS according to pulse width modulation signal PWMS；
Step 306：Frequency detecting unit 206 is generated according to a critical value and the frequency of pulse width modulation signal PWMS
One logical value LV；
Step 308：Whether the frequency of pulse width modulation signal PWMS is less than critical value；If so, carry out step 310；
If not, skip to step 320；
Step 310：Multiplexer 2082 exports a reference voltage VREF；
Step 312：Logic unit 2084 exports a rp pulse width modulation signal
Step 314：2086 output reference voltage VREF of transmission unit and rp pulse width modulation signal
Step 316：Second switch 2088 is according to rp pulse width modulation signalIt opens and closes；Step
318：Comparator 2090 generates a switch control signal SCS to first switch according to reference voltage VREF and a sensing voltage SV
212, skip to step 308；
Step 320：Multiplexer 2082 exports direct current signal DS；
Step 322：Logic unit 2084 exports the first logical value with logical value LV reverse phases
Step 324：Transmission unit 2086 exports direct current signal DS and the first logical value
Step 326：Second switch 2088 is according to the first logical valueIt closes；
Step 328：Comparator 2090 generates switch control signal SCS to the according to direct current signal DS and sensing voltage SV
One switch 212, skips to step 308.
Within step 306, frequency detecting unit 206 is according to a critical value and pulse width modulation signal PWMS, is generated
Logical value LV.For example, when the frequency of pulse width modulation signal PWMS is less than critical value, the generation of frequency detecting unit 206 is patrolled
Collect value " 0 " and when the frequency of pulse width modulation signal PWMS is higher than critical value, frequency detecting unit 206 generates logic
It is worth " 1 ".But the present invention is not limited to when the frequency of pulse width modulation signal PWMS is less than critical value, frequency detecting unit
206 generate logical value " 0 " and when the frequency of pulse width modulation signal PWMS is higher than critical value, frequency detecting unit 206
Generate logical value " 1 ".
In the step 310, when the frequency of pulse width modulation signal PWMS is less than critical value, multiplexer 2082 exports
Reference voltage VREF and frequency detecting unit 206 generate logical value according to critical value and pulse width modulation signal PWMS
“0”.In step 312, logic unit 2084 exports rp pulse according to logical value " 0 " and pulse width modulation signal PWMS
Width modulation signalIn step 316, second switch 2088 is according to rp pulse width modulation signalIt opens
It opens and closes, wherein when second switch 2088 is opened, first switch 212 closes and when second switch 2088 is closed, the
One switch 212 is opened；In step 318, comparator 2090 generates switch control according to reference voltage VREF and sensing voltage SV
Signal SCS is to first switch 212.Because second switch 2088 is according to rp pulse width modulation signalOpen with
It closes, so first switch 212 also can be according to rp pulse width modulation signalIt opens and closes, leads to controller
200 enter digital dimming mode.Therefore, when the frequency of pulse width modulation signal PWMS is less than critical value, controller 200 is
Into digital dimming mode, that is to say, that when comparator 2090 is according to reference voltage VREF and sensing voltage SV, generation switch control
When signal SCS processed is to first switch 212, controller 200 is to enter digital dimming mode.
In step 320, when the frequency of pulse width modulation signal PWMS is higher than critical value, multiplexer 2082 exports
Direct current signal DS and frequency detecting unit 206 generate logic according to critical value and the frequency of pulse width modulation signal PWMS
It is worth " 1 ".In step 322, logic unit 2084 is according to logical value " 1 " and pulse width modulation signal PWMS, output and logic
It is worth first logical value " 0 " of " 1 " reverse phase；In step 326, second switch 2088 is closed according to the first logical value " 0 ", wherein when
When second switch 2088 is closed, first switch 212 is opened；In step 328, comparator 2090 is according to direct current signal DS and sensing
Voltage SV generates switch control signal SCS to first switch 212.Because second switch 2088 continues according to the first logical value " 0 "
It closes, is opened so first switch 212 is sustainable according to switch control signal SCS (corresponding to direct current signal DS), cause to control
Device 200 enters analog dimming mode.Therefore, when the frequency of pulse width modulation signal PWMS is higher than critical value, controller 200
It is to enter analog dimming mode, that is to say, that when comparator 2090 is according to direct current signal DS and sensing voltage SV, generation switch control
When signal SCS processed is to first switch 212, controller 200 is to enter analog dimming mode.
It is that the third embodiment of the present invention discloses one kind to dim to please refer to Fig. 1 and Fig. 4 A and Fig. 4 B, Fig. 4 A and Fig. 4 B
The flow chart of the method for light emitting diode.The method of Fig. 4 A and Fig. 4 B are to illustrate that detailed step is such as using the controller 200 of Fig. 1
Under：
Step 400：Start；
Step 402：Pulse width modulation pin 202 receives microcontroller 210 and is believed according to the image that liquid crystal display receives
Pulse width modulation signal PWMS caused by number；
Step 404：Low-pass filter 204 generates a direct current signal DS according to pulse width modulation signal PWMS；
Step 406：Frequency detecting unit 206 is generated according to a critical value and the frequency of pulse width modulation signal PWMS
One logical value LV；
Step 408：Whether the frequency of pulse width modulation signal PWMS is less than critical value；If so, carry out step 410；
If not, skip to step 420；
Step 410：Multiplexer 2082 exports a reference voltage VREF；
Step 412：Logic unit 2084 exports a rp pulse width modulation signal
Step 414：2086 output reference voltage VREF of transmission unit and rp pulse width modulation signal
Step 416：Second switch 2088 is according to rp pulse width modulation signalIt opens and closes；
Step 418：Comparator 2090 generates a switch control signal according to reference voltage VREF and a sensing voltage SV
SCS skips to step 408 to first switch 212；
Step 420：Multiplexer 2082 exports direct current signal DS；
Step 422：Logic unit 2084 exports the first logical value with logical value LV reverse phases
Step 424：Transmission unit 2086 exports direct current signal DS and the first logical value
Step 426：Second switch 2088 is according to the first logical valueIt closes；
Step 428：Comparator 2090 generates switch control signal SCS to the according to direct current signal DS and sensing voltage SV
One switch 212, skips to step 408.
The embodiment of Fig. 4 A and Fig. 4 B and the embodiment of Fig. 3 A and Fig. 3 B are the difference is that in step 402, microcontroller
210 be the video signal received according to liquid crystal display, generates pulse width modulation signal PWMS, wherein pulse width modulation
Signal PWMS corresponds to various play mode possessed by liquid crystal display, various contrasts or various white balances, and liquid crystal
Various play mode possessed by display include a film mode, an electronic game pattern, three-dimensional (3D) pattern and a two dimension
(2D) pattern.In the embodiment of Fig. 4 A and Fig. 4 B, video signal that microcontroller 210 can be received according to liquid crystal display,
Generate pulse width modulation signal PWMS, that is to say, that the video signal that microcontroller 210 can be received according to liquid crystal display
The corresponding driving current ILED for flowing through light emitting diode 100 generates pulse width modulation signal PWMS.For example, work as liquid crystal
When the video signal that display is received needs larger driving current ILED, the pulse that microcontroller 210 can generate low frequency is wide
Spend modulating signal PWMS.In addition, embodiment phase of remaining operating principle of the embodiment of Fig. 4 A and Fig. 4 B all with Fig. 3 A and Fig. 3 B
Together, details are not described herein.
To dim the controller of light emitting diode and method it is according to microcontroller in conclusion disclosed in this invention
The pulse width modulation signal of generation and a critical value determine that controller is operated in digital dimming mode or analog dimming mode,
So the present invention only needs a pin to receive the pulse width modulation signal that microcontroller generates, you can controller is made to be adjusted in number
Switch between optical mode and analog dimming mode.Therefore, compared to the prior art, because the present invention is generated according to microcontroller
Pulse width modulation signal and critical value, determine controller operation in digital dimming mode or analog dimming mode, thus this
Invention is not necessary to accordingly change printed circuit board.In addition, the present invention is the pulse width modulation signal generated according to microcontroller
And critical value, controller operation is determined in digital dimming mode or analog dimming mode, so the present invention can't increase additionally
Burden.
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, for the skill of this field
For art personnel, the invention may be variously modified and varied.All within the spirits and principles of the present invention, that is made any repaiies
Change, equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.
Claims (12)
- It is 1. a kind of dimming the controller of light emitting diode, it is characterised in that including：One pulse width modulation pin, to receive the pulse width modulation signal of microcontroller generation；One low-pass filter, according to the pulse width modulation signal, to generate a direct current signal；One frequency detecting unit, according to a critical value and the pulse width modulation signal, to generate a logical value；AndOne control signal generator module, is coupled to the low-pass filter and the frequency detecting unit, to according to described straight Signal, the logical value, a reference voltage and the pulse width modulation signal are flowed, generates a switch control signal to connecting State the first switch of light emitting diode, wherein the first switch be according to the switch control signal open and close and The control signal generator module includes：One multiplexer is coupled to the low-pass filter and the frequency detecting unit, to according to the logical value, output The reference voltage or the direct current signal, wherein when the frequency of the pulse width modulation signal is less than the critical value, The multiplexer exports the reference voltage and when the frequency of the pulse width modulation signal is higher than the critical value When, the multiplexer exports the direct current signal；One logic unit is coupled to the frequency detecting unit, to receive the pulse width modulation signal and the logic Value and one rp pulse width modulation signal of output or the first logical value with the logical value reverse phase, wherein when the arteries and veins When rushing the frequency of width modulation signal less than the critical value, the logic unit exports the rp pulse width modulation letter Number and when the frequency of the pulse width modulation signal is higher than the critical value, logic unit output described first Logical value；One transmission unit is coupled to the multiplexer and the logic unit, to export the reference voltage with it is described straight Flow one of signal and output one of the rp pulse width modulation signal and first logical value；One second switch is coupled to the transmission unit, to according to the rp pulse width modulation signal or described first Logical value performs a corresponding action, wherein when the second switch is opened, the first switch closes and when described When second switch is closed, the first switch is opened；AndOne comparator is coupled to the transmission unit, to according to one of the reference voltage and the direct current signal and One sensing voltage generates the switch control signal to the first switch；Wherein when the comparator is according to the reference voltage and the sensing voltage, the switch control signal is generated to described During first switch, the controller be into a digital dimming mode and when the comparator according to the direct current signal with The sensing voltage,When generating the switch control signal to the first switch, the controller is to enter an analog dimming mode；Wherein when the frequency of the pulse width modulation signal is less than the critical value, the controller is to enter the number Light-modulating mode and when the pulse width modulation signal frequency be higher than the critical value when, the controller be enter institute State analog dimming mode.
- 2. controller as described in claim 1, it is characterised in that：When the controller is switched on, the controller is acquiescence Into the digital dimming mode or the analog dimming mode.
- 3. controller as described in claim 1, it is characterised in that：When the controller normal operation,The controller is according to the pulse width modulation signal and the critical value, switches the digital dimming mode to institute Analog dimming mode or the switching analog dimming mode are stated to the digital dimming mode.
- 4. controller as described in claim 1, it is characterised in that：The switch control signal is transmitted by a grid pin To the first switch.
- 5. it is a kind of to dim the method for light emitting diode, wherein the controller applied to the method includesOne pulse width modulation pin, a low-pass filter, a frequency detecting unit and a control signal generator module, wherein institute It states control signal generator module and includes a multiplexer, a logic unit, a transmission unit, a second switch and a comparator, The method is characterized in that including：The pulse width modulation pin receives the pulse width modulation signal that a microcontroller generates；The low-pass filter generates a direct current signal according to the pulse width modulation signal；The frequency detecting unit generates a logical value according to a critical value and the pulse width modulation signal；When the frequency of the pulse width modulation signal is less than the critical value, the multiplexer exports a reference voltage；When the frequency of the pulse width modulation signal is less than the critical value, it is wide that the logic unit exports a rp pulse Spend modulating signal；The transmission unit exports the reference voltage and the output rp pulse width modulation signal；The second switch opens and closes, according to the rp pulse width modulation signal wherein when the second switch is opened Qi Shi, the first switch for the light emitting diode of connecting are closed and when the second switch is closed, and the first switch is opened It opens；AndThe comparator generates a switch control signal to the first switch according to the reference voltage and a sensing voltage, Wherein described first switch is opened and closed according to the switch control signal；Wherein when the frequency of the pulse width modulation signal is less than the critical value, the controller is to enter a number to adjust Optical mode, when the frequency of the pulse width modulation signal is higher than the critical value, the controller is to enter a simulation to adjust Optical mode and when the comparator is according to the reference voltage and the sensing voltage, generates the switch control signal extremely During the first switch, the controller is to enter the digital dimming mode.
- 6. method as claimed in claim 5, it is characterised in that：When the controller is switched on, the controller be give tacit consent into Enter the digital dimming mode or the analog dimming mode.
- 7. method as claimed in claim 5, it is characterised in that：When the controller normal operation, the controller is root According to the pulse width modulation signal and the critical value, switch the digital dimming mode to the analog dimming mode or Switch the analog dimming mode to the digital dimming mode.
- 8. it is a kind of to dim the method for light emitting diode, wherein the controller applied to the method includesOne pulse width modulation pin, a low-pass filter, a frequency detecting unit and a control signal generator module, wherein institute It states control signal generator module and includes a multiplexer, a logic unit, a transmission unit, a second switch and a comparator, The method is characterized in that including：The pulse width modulation pin receives the pulse width modulation signal that a microcontroller generates；The low-pass filter generates a direct current signal according to the pulse width modulation signal；The frequency detecting unit generates a logical value according to a critical value and the pulse width modulation signal；When the frequency of the pulse width modulation signal is higher than the critical value, the multiplexer exports the direct current letter Number；When the frequency of the pulse width modulation signal is higher than the critical value, the logic unit output and the logical value First logical value of reverse phase；The transmission unit exports the direct current signal and output first logical value；The second switch is closed according to first logical value, wherein when the second switch is closed,Connect the light emitting diode first switch open；AndThe comparator generates a switch control signal to the first switch according to the direct current signal and a sensing voltage；Wherein when the comparator is according to the direct current signal and the sensing voltage, the switch control signal is generated to described During first switch, the controller is to enter an analog dimming mode, when the frequency of the pulse width modulation signal is less than institute When stating critical value, the controller is into a digital dimming mode and when the frequency of the pulse width modulation signal is high When the critical value, the controller is to enter the analog dimming mode.
- 9. it is a kind of to dim the method for light emitting diode, wherein the light emitting diode is to be applied to a liquid crystal display, with And the controller applied to the method includes a pulse width modulation pin, a low-pass filter, a frequency detecting unit And one control signal generator module, wherein it is described control signal generator module include a multiplexer, a logic unit, one transmission Unit, a second switch and a comparator, the method are characterized in that including：The pulse width modulation pin receives a microcontroller according to produced by the video signal that the liquid crystal display receives Pulse width modulation signal；The low-pass filter generates a direct current signal according to the pulse width modulation signal；The frequency detecting unit generates a logical value according to a critical value and the pulse width modulation signal；When the frequency of the pulse width modulation signal is less than the critical value, the multiplexer exports a reference voltage；When the frequency of the pulse width modulation signal is less than the critical value, it is wide that the logic unit exports a rp pulse Spend modulating signal；The transmission unit exports the reference voltage and the rp pulse width modulation signal；The second switch opens and closes, according to the rp pulse width modulation signal wherein when the second switch is opened Qi Shi, the first switch for the light emitting diode of connecting are closed and when the second switch is closed, and the first switch is opened It opens；AndThe comparator generates a switch control signal to the first switch according to the reference voltage and a sensing voltage, Wherein described first switch is opened and closed according to the switch control signal；Wherein when the comparator is according to the reference voltage and the sensing voltage, the switch control signal is generated to described During first switch, the controller is to enter a digital dimming mode, when the frequency of the pulse width modulation signal is less than institute When stating critical value, the controller is to enter the digital dimming mode and the frequency when the pulse width modulation signal During higher than the critical value, the controller is to enter an analog dimming mode.
- 10. method as claimed in claim 9, it is characterised in that：The pulse width modulation signal corresponds to the liquid crystal Various play mode, various contrasts or various white balances possessed by display.
- 11. method as claimed in claim 10, it is characterised in that：The various play mode include a film mode, an electricity Object for appreciation pattern, a three dimensional pattern and a two-dimensional model.
- 12. it is a kind of to dim the method for light emitting diode, wherein the light emitting diode is to be applied to a liquid crystal display, with And the controller applied to the method includes a pulse width modulation pin, a low-pass filter, a frequency detecting unit And one control signal generator module, wherein it is described control signal generator module include a multiplexer, a logic unit, one transmission Unit, a second switch and a comparator, the method are characterized in that including：The pulse width modulation pin receives a microcontroller according to produced by the video signal that the liquid crystal display receives Pulse width modulation signal；The low-pass filter generates a direct current signal according to the pulse width modulation signal；The frequency detecting unit generates a logical value according to a critical value and the pulse width modulation signal；When the frequency of the pulse width modulation signal is higher than the critical value, the multiplexer exports the direct current letter Number；When the frequency of the pulse width modulation signal is higher than the critical value, the logic unit output and the logical value First logical value of reverse phase；The transmission unit exports the direct current signal and first logical value；The second switch is closed according to first logical value, wherein when the second switch is closed,Connect the light emitting diode first switch open；AndThe comparator generates a switch control signal to the first switch according to the direct current signal and a sensing voltage；Wherein when the comparator is according to the direct current signal and the sensing voltage, the switch control signal is generated to described During first switch, the controller is to enter an analog dimming mode, when the frequency of the pulse width modulation signal is less than institute When stating critical value, the controller is into a digital dimming mode and when the frequency of the pulse width modulation signal is high When the critical value, the controller is to enter the analog dimming mode.
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| CN101902861A (en) * | 2010-08-10 | 2010-12-01 | 友达光电股份有限公司 | LED driving method and LED driving circuit |
| CN102196621A (en) * | 2010-03-19 | 2011-09-21 | 上海贝岭股份有限公司 | LED dimming circuit |
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| KR101289651B1 (en) * | 2010-12-08 | 2013-07-25 | 엘지디스플레이 주식회사 | Liquid crystal display and scanning back light driving method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102196621A (en) * | 2010-03-19 | 2011-09-21 | 上海贝岭股份有限公司 | LED dimming circuit |
| CN101902861A (en) * | 2010-08-10 | 2010-12-01 | 友达光电股份有限公司 | LED driving method and LED driving circuit |
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