CN105263209A - Controller for dimming light-emitting diode and method - Google Patents
Controller for dimming light-emitting diode and method Download PDFInfo
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- CN105263209A CN105263209A CN201410270531.2A CN201410270531A CN105263209A CN 105263209 A CN105263209 A CN 105263209A CN 201410270531 A CN201410270531 A CN 201410270531A CN 105263209 A CN105263209 A CN 105263209A
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Abstract
The invention discloses a controller for dimming a light-emitting diode and a method. The controller comprises a pulse width modulation pin, a low-pass filter, a frequency detection unit and a control signal generation module, wherein the low-pass filter generates a direct current signal according to a pulse width modulation signal generated by a microcontroller; the frequency detection unit generates a logic value according to a critical value and the pulse width modulation signal; the control signal generation module generates a switching control signal to a first switch which is connected with the light-emitting diode in series according to the direct current signal, the logic value, the reference voltage and the pulse width modulation signal; when the frequency of the pulse width modulation signal is lower than the critical value, the controller enters a digital dimming mode; and when the frequency of the pulse width modulation signal is higher than the critical value, the controller enters an analogue dimming mode. Therefore, a printed circuit board does not need to be correspondingly modified and the added burden is not increased.
Description
Technical field
The present invention relates to the controller in order to light modulation light-emitting diode and method, particularly relate to a kind of controller in order to light modulation light-emitting diode and the method that can realize digital dimming mode and analog dimming mode according to the frequency of pulse width modulation signal at same pin.
Background technology
The digital dimming mode and the analog dimming mode that are applied to dimming light-emitting diode have respective advantage respectively.Such as, analog dimming mode has following advantages: the first, the good color saturation of analog dimming mode; The second, the power dissipation ratio of analog dimming mode is better, so analog dimming mode is for new forms of energy regulation (level-6), has larger product design space; Three, analog dimming mode can not produce water ripples, so analog dimming mode is more friendly to human eye, that is has marketing subject matter; Four, the electromagnetic frequency that analog dimming mode produces drops on the scope (1Hz-30kHz) of institute of career employee association of Sweden (SwedishFederationofProfessionalEmployees, TCO) specification; And digital dimming mode has following advantages: the first, digital dimming mode has good contrast; The second, digital dimming mode is easier to control colour temperature and look Times; Brightness and the drive current of the light-emitting diode three, produced according to digital dimming mode are linear changes.
In the prior art, because the digital dimming mode and the analog dimming mode that are applied to dimming light-emitting diode have respective advantage respectively, so although the drive circuit that user sets light-emitting diode by external signal operates in digital dimming mode or analog dimming mode, but the external signal that the drive circuit of light-emitting diode must have different pin to receive corresponds to digital dimming mode and analog dimming mode or printed circuit board (PCB) are revised accordingly, prior art is caused to be not a good selection for user.
Summary of the invention
The first embodiment of the present invention discloses a kind of controller in order to light modulation light-emitting diode.Described controller comprises a pulse width modulation pin, a low pass filter, a frequency detecting unit and a control signal generation module.Described pulse width modulation pin is the pulse width modulation signal receiving a microcontroller generation.Described low pass filter is in order to according to described pulse width modulation signal, produces a direct current signal.Described frequency detecting unit is in order to according to a critical value and described pulse width modulation signal, produces a logical value.Described control signal generation module is coupled to described low pass filter and described frequency detecting unit, in order to according to described direct current signal, described logical value, a reference voltage and described pulse width modulation signal, produce first switch of a switch controlling signal to described light-emitting diode of connecting, wherein said first switch opens and closes according to described switch controlling signal.When the frequency of described pulse width modulation signal is lower than described critical value, described controller enters a digital dimming mode, and when the frequency of described pulse width modulation signal is higher than described critical value, described controller enters an analog dimming mode.
The second embodiment of the present invention discloses a kind of method in order to light modulation light-emitting diode, and the controller being wherein applied to described method comprises a pulse width modulation pin, a low pass filter, a frequency detecting unit and a control signal generation module.Described method comprises the pulse width modulation signal that described pulse width modulation pin receives a microcontroller generation; Described low pass filter, according to described pulse width modulation signal, produces a direct current signal; Described frequency detecting unit, according to a critical value and described pulse width modulation signal, produces a logical value; Described control signal generation module is according to described direct current signal, described logical value, a reference voltage and described pulse width modulation signal, produce first switch of a switch controlling signal to described light-emitting diode of connecting, wherein said first switch opens and closes according to described switch controlling signal; When the frequency of described pulse width modulation signal is lower than described critical value, described controller enters a digital dimming mode, and when the frequency of described pulse width modulation signal is higher than described critical value, described controller enters an analog dimming mode.
The third embodiment of the present invention discloses a kind of method in order to light modulation light-emitting diode, wherein said light-emitting diode is applied to a liquid crystal display, and the controller being applied to described method comprises a pulse width modulation pin, a low pass filter, a frequency detecting unit and a control signal generation module, wherein said control signal generation module comprises a multiplexer, a logical block, a transmission unit, a second switch and a comparator.Described method comprises described pulse width modulation pin and receives the pulse width modulation signal that a microcontroller produces according to the signal of video signal that described liquid crystal display receives; Described low pass filter, according to described pulse width modulation signal, produces a direct current signal; Described frequency detecting unit, according to a critical value and described pulse width modulation signal, produces a logical value; Described control signal generation module is according to described direct current signal, described logical value, a reference voltage and described pulse width modulation signal, produce first switch of a switch controlling signal to described light-emitting diode of connecting, wherein said first switch opens and closes according to described switch controlling signal; When the frequency of described pulse width modulation signal is lower than described critical value, described controller enters a digital dimming mode, and when the frequency of described pulse width modulation signal is higher than described critical value, described controller enters an analog dimming mode.
The present invention discloses a kind of controller in order to light modulation light-emitting diode and method.Described controller and described method be according to one microcontroller produce pulse width modulation signal and a critical value, determine that described controller operates in a digital dimming mode or an analog dimming mode, so the pulse width modulation signal that the present invention only needs a pin to receive described microcontroller to be produced, described controller can be made to switch between described digital dimming mode and described analog dimming mode.Therefore, compared to prior art, because the present invention is the pulse width modulation signal and described critical value that produce according to described microcontroller, determine that described controller operates in described digital dimming mode or described analog dimming mode, so the present invention must not revise a printed circuit board (PCB) accordingly.In addition, the present invention is the pulse width modulation signal and described critical value that produce according to described microcontroller, determines that described controller operates in described digital dimming mode or described analog dimming mode, so the present invention can't increase extra burden.
Accompanying drawing explanation
Fig. 1 is the schematic diagram that the first embodiment of the present invention discloses a kind of controller in order to light modulation light-emitting diode.
Fig. 2 is the relation schematic diagram of drive current pulse width modulation signal being described and flowing through light-emitting diode.
Fig. 3 A and Fig. 3 B is the flow chart that the second embodiment of the present invention discloses a kind of method in order to light modulation light-emitting diode.
Fig. 4 A and Fig. 4 B is the flow chart that the third embodiment of the present invention discloses a kind of method in order to light modulation light-emitting diode.
Wherein, description of reference numerals is as follows:
100 light-emitting diodes
200 controllers
202 pulse width modulation pins
204 low pass filters
206 frequency detecting units
208 control signal generation modules
210 microcontrollers
212 first switches
214 grid pins
216 power supply changeover devices
2082 multiplexers
2084 logical blocks
2086 transmission units
2088 second switches
2090 comparators
DS direct current signal
ILED drive current
ILEDMAX maximum drive current
LV logical value
first logical value
PWMS pulse width modulation signal
rp pulse width modulation signal
SEC secondary side
SCS switch controlling signal
SV sensing voltage
VOUT output voltage
VREF reference voltage
300-328,400-428 step
Embodiment
Please refer to Fig. 1, Fig. 1 is the schematic diagram that the first embodiment of the present invention discloses a kind of controller 200 in order to light modulation light-emitting diode 100, wherein the secondary side SEC of a power supply changeover device 216 produces an output voltage VO UT to drive light-emitting diode 100, and controller 200 is the secondary side SEC being positioned at power supply changeover device 216.As shown in Figure 1, controller 200 comprises pulse width modulation pin 202, low pass filter 204, frequency detecting unit 206 and a control signal generation module 208.As shown in Figure 1, pulse width modulation pin 202 is the pulse width modulation signal PWMS receiving microcontroller 210 generation.Low pass filter 204 is coupled to pulse width modulation pin 202, in order to according to pulse width modulation signal PWMS, produces a direct current signal DS.Frequency detecting unit 206 is coupled to pulse width modulation pin 202, in order to according to a critical value and pulse width modulation signal PWMS, produces a logical value LV.Such as, when the frequency of pulse width modulation signal PWMS is lower than critical value, frequency detecting unit 206 produces a logical value " 0 ", and when the frequency of pulse width modulation signal PWMS is higher than critical value, frequency detecting unit 206 produces a logical value " 1 ".But the present invention is not limited to when the frequency of pulse width modulation signal PWMS is lower than critical value, frequency detecting unit 206 produces logical value " 0 ", and when the frequency of pulse width modulation signal PWMS is higher than critical value, frequency detecting unit 206 produces logical value " 1 ".Control signal generation module 208 is coupled to low pass filter 204 and frequency detecting unit 206, in order to according to direct current signal DS, logical value LV, a reference voltage VREF and pulse width modulation signal PWMS, produce first switch 212 of a switch controlling signal SCS to series connection light-emitting diode 100, wherein the first switch 212 opens and closes according to switch controlling signal SCS, and switch controlling signal SCS is sent to the first switch 212 by a grid pin 214.
As shown in Figure 1, control signal generation module 208 comprises multiplexer 2082, logical block 2084, transmission unit 2086, second switch 2088 and a comparator 2090.As shown in Figure 1, multiplexer 2082 is coupled to low pass filter 204 and frequency detecting unit 206, in order to according to logical value LV, output reference voltage VREF or direct current signal DS, wherein when the frequency of pulse width modulation signal PWMS is lower than critical value, multiplexer 2082 output reference voltage VREF, and when the frequency of pulse width modulation signal PWMS is higher than critical value, multiplexer 2082 exports direct current signal DS; Logical block 2084 is coupled to frequency detecting unit 206, in order to received pulse width modulation signal PWMS and logical value LV, and exports a rp pulse width modulation signal
or first logical value anti-phase with logical value LV
wherein when the frequency of pulse width modulation signal PWMS is lower than critical value, logical block 2084 exports rp pulse width modulation signal
and when the frequency of pulse width modulation signal PWMS is higher than critical value, logical block 2084 exports the first logical value
transmission unit 2086 is coupled to multiplexer 2082 and logical block 2084, in order to output reference voltage VREF and direct current signal DS one of them, and output rp pulse width modulation signal
with the first logical value
one of them; Second switch 2088 is coupled to transmission unit 2086, in order to according to rp pulse width modulation signal
or first logical value
perform a corresponding action, wherein when second switch 2088 opens (ON), the first switch 212 cuts out (OFF), and when second switch 2088 is closed, the first switch 212 is opened; Comparator 2090 is coupled to transmission unit 2086, in order to according to reference voltage VREF and direct current signal DS one of them and a sensing voltage SV, produces switch controlling signal SCS to the first switch 212.
As shown in Figure 1, when the frequency of pulse width modulation signal PWMS is lower than critical value, multiplexer 2082 output reference voltage VREF, and frequency detecting unit 206 is according to the frequency of critical value and pulse width modulation signal PWMS, produces logical value " 0 ".Logical block 2084, according to logical value " 0 " and pulse width modulation signal PWMS, exports rp pulse width modulation signal
transmission unit 2086 output reference voltage VREF, and export rp pulse width modulation signal
second switch 2088 is according to rp pulse width modulation signal
open and close, wherein when second switch 2088 is opened, the first switch 212 cuts out, and when second switch 2088 is closed, the first switch 212 is opened; Comparator 2090, according to reference voltage VREF and sensing voltage SV, produces switch controlling signal SCS to the first switch 212.Because second switch 2088 is according to rp pulse width modulation signal
open and close, so the first switch 212 also can according to rp pulse width modulation signal
open and close, cause controller 200 to enter a digital dimming mode.Therefore, when the frequency of pulse width modulation signal PWMS is lower than critical value, controller 200 enters digital dimming mode, that is when comparator 2090 is according to reference voltage VREF and sensing voltage SV, when producing switch controlling signal SCS to the first switch 212, controller 200 enters digital dimming mode.
As shown in Figure 1, 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 is according to the frequency of critical value and pulse width modulation signal PWMS, produces logical value " 1 ".Logical block 2084, according to logical value " 1 " and pulse width modulation signal PWMS, exports first logical value " 0 " anti-phase with logical value " 1 "; Transmission unit 2086 exports direct current signal DS, and output first logical value " 0 "; Second switch 2088 is closed according to the first logical value " 0 ", and wherein when second switch 2088 is closed, the first switch 212 is opened; Comparator 2090, according to direct current signal DS and sensing voltage SV, produces switch controlling signal SCS to the first switch 212.Because second switch 2088 continues to close according to the first logical value " 0 ", open according to switch controlling signal SCS (corresponding to direct current signal DS) so the first switch 212 is sustainable, cause controller 200 to enter an analog dimming mode.Therefore, when the frequency of pulse width modulation signal PWMS is higher than critical value, controller 200 enters analog dimming mode, that is when comparator 2090 is according to direct current signal DS and sensing voltage SV, when producing switch controlling signal SCS to the first switch 212, controller 200 enters analog dimming mode.
Please refer to Fig. 2, Fig. 2 is the relation schematic diagram of drive current ILED pulse width modulation signal PWMS being described and flowing through light-emitting diode 100.As shown in Figure 2, when the frequency of pulse width modulation signal PWMS is lower than critical value, controller 200 enters digital dimming mode.If the duty ratio of pulse width modulation signal PWMS (dutycycle) is 50%, then the duty ratio of drive current 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%, then drive current ILED will be 50% of maximum drive current ILEDMAX
In addition, the present invention is not limited to controller 200 and only has 2 kinds of light-modulating modes, and that is frequency detecting unit 206 according to the frequency of the critical value more than more than and pulse width modulation signal PWMS, can produce corresponding logical value.Such as, when the frequency of pulse width modulation signal PWMS is lower than first critical value, frequency detecting unit 206 can produce 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 unit 206 can produce a logical value " 01 "; And when the frequency of pulse width modulation signal PWMS is higher than second critical value, frequency detecting unit 206 can produce a logical value " 10 ".Now, the logical value (" 00 ", " 01 ", " 10 ") that multiplexer 2082 and logical block 2084 can produce according to frequency detecting unit 206 is revised accordingly, has three kinds of light-modulating modes to make controller 200.
In addition, the present invention can when controller 200 be started shooting, controller 200 is that acquiescence enters digital dimming mode or analog dimming mode, or when described controller 200 normal operation, controller 200 is according to pulse width modulation signal PWMS, switch digital dimming mode to analog dimming mode, or switch analog dimming mode to digital dimming mode.
Please refer to Fig. 1 and Fig. 3 A and Fig. 3 B, Fig. 3 A and Fig. 3 B is the flow chart that the second embodiment of the present invention discloses a kind of method in order to light modulation light-emitting diode.The method of Fig. 3 A and Fig. 3 B utilizes the controller 200 of Fig. 1 to illustrate, detailed step is as follows:
Step 300: start;
Step 302: pulse width modulation pin 202 receives the pulse width modulation signal PWMS that microcontroller 210 produces;
Step 304: low pass filter 204, according to pulse width modulation signal PWMS, produces a direct current signal DS;
Step 306: frequency detecting unit 206, according to the frequency of a critical value and pulse width modulation signal PWMS, produces a logical value LV;
Whether the frequency of step 308: pulse width modulation signal PWMS is lower than critical value; If so, carry out step 310; If not, step 320 is skipped to;
Step 310: multiplexer 2082 exports a reference voltage VREF;
Step 312: logical block 2084 exports a rp pulse width modulation signal
Step 314: transmission unit 2086 output reference voltage VREF and rp pulse width modulation signal
Step 316: second switch 2088 is according to rp pulse width modulation signal
open and close; Step 318: comparator 2090, according to a reference voltage VREF and sensing voltage SV, produces switch controlling signal SCS to the first switch 212, skips to step 308;
Step 320: multiplexer 2082 exports direct current signal DS;
Step 322: logical block 2084 exports first logical value anti-phase with logical value LV
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 value
close;
Step 328: comparator 2090, according to direct current signal DS and sensing voltage SV, produces switch controlling signal SCS to the first switch 212, skips to step 308.
Within step 306, frequency detecting unit 206 is root one critical value and pulse width modulation signal PWMS, produces logical value LV.Such as, when the frequency of pulse width modulation signal PWMS is lower than critical value, frequency detecting unit 206 produces logical value " 0 ", and when the frequency of pulse width modulation signal PWMS is higher than critical value, frequency detecting unit 206 produces logical value " 1 ".But the present invention is not limited to when the frequency of pulse width modulation signal PWMS is lower than critical value, frequency detecting unit 206 produces logical value " 0 ", and when the frequency of pulse width modulation signal PWMS is higher than critical value, frequency detecting unit 206 produces logical value " 1 ".
In the step 310, when the frequency of pulse width modulation signal PWMS is lower than critical value, multiplexer 2082 output reference voltage VREF, and frequency detecting unit 206 is according to critical value and pulse width modulation signal PWMS, produces logical value " 0 ".In step 312, logical block 2084, according to logical value " 0 " and pulse width modulation signal PWMS, exports rp pulse width modulation signal
in step 316, second switch 2088 is according to rp pulse width modulation signal
open and close, wherein when second switch 2088 is opened, the first switch 212 cuts out, and when second switch 2088 is closed, the first switch 212 is opened; In step 318, comparator 2090, according to reference voltage VREF and sensing voltage SV, produces switch controlling signal SCS to the first switch 212.Because second switch 2088 is according to rp pulse width modulation signal
open and close, so the first switch 212 also can according to rp pulse width modulation signal
open and close, cause controller 200 to enter digital dimming mode.Therefore, when the frequency of pulse width modulation signal PWMS is lower than critical value, controller 200 enters digital dimming mode, that is when comparator 2090 is according to reference voltage VREF and sensing voltage SV, when producing switch controlling signal SCS to the first switch 212, controller 200 enters 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 is according to the frequency of critical value and pulse width modulation signal PWMS, produces logical value " 1 ".In step 322, logical block 2084, according to logical value " 1 " and pulse width modulation signal PWMS, exports first logical value " 0 " anti-phase with logical value " 1 "; In step 326, second switch 2088 is closed according to the first logical value " 0 ", and wherein when second switch 2088 is closed, the first switch 212 is opened; In step 328, comparator 2090, according to direct current signal DS and sensing voltage SV, produces switch controlling signal SCS to the first switch 212.Because second switch 2088 continues to close according to the first logical value " 0 ", open according to switch controlling signal SCS (corresponding to direct current signal DS) so the first switch 212 is sustainable, cause controller 200 to enter analog dimming mode.Therefore, when the frequency of pulse width modulation signal PWMS is higher than critical value, controller 200 enters analog dimming mode, that is when comparator 2090 is according to direct current signal DS and sensing voltage SV, when producing switch controlling signal SCS to the first switch 212, controller 200 enters analog dimming mode.
Please refer to Fig. 1 and Fig. 4 A and Fig. 4 B, Fig. 4 A and Fig. 4 B is the flow chart that the third embodiment of the present invention discloses a kind of method in order to light modulation light-emitting diode.The method of Fig. 4 A and Fig. 4 B utilizes the controller 200 of Fig. 1 to illustrate, detailed step is as follows:
Step 400: start;
Step 402: pulse width modulation pin 202 receives the pulse width modulation signal PWMS that microcontroller 210 produces according to the signal of video signal that liquid crystal display receives;
Step 404: low pass filter 204, according to pulse width modulation signal PWMS, produces a direct current signal DS;
Step 406: frequency detecting unit 206, according to the frequency of a critical value and pulse width modulation signal PWMS, produces a logical value LV;
Whether the frequency of step 408: pulse width modulation signal PWMS is lower than critical value; If so, carry out step 410; If not, step 420 is skipped to;
Step 410: multiplexer 2082 exports a reference voltage VREF;
Step 412: logical block 2084 exports a rp pulse width modulation signal
Step 414: transmission unit 2086 output reference voltage VREF and rp pulse width modulation signal
Step 416: second switch 2088 is according to rp pulse width modulation signal
open and close;
Step 418: comparator 2090, according to a reference voltage VREF and sensing voltage SV, produces switch controlling signal SCS to the first switch 212, skips to step 408;
Step 420: multiplexer 2082 exports direct current signal DS;
Step 422: logical block 2084 exports first logical value anti-phase with logical value LV
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 value
close;
Step 428: comparator 2090, according to direct current signal DS and sensing voltage SV, produces switch controlling signal SCS to the first switch 212, skips to step 408.
The difference of the embodiment of Fig. 4 A and Fig. 4 B and the embodiment of Fig. 3 A and Fig. 3 B is in step 402, microcontroller 210 is the signal of video signal received according to liquid crystal display, produce pulse width modulation signal PWMS, wherein pulse width modulation signal PWMS is the various play mode, various contrast or the various white balance that have corresponding to liquid crystal display, and the various play mode that liquid crystal display has comprise a film mode, an electronic game pattern, a three-dimensional (3D) pattern and a two dimension (2D) pattern.In the embodiment of Fig. 4 A and Fig. 4 B, the signal of video signal that microcontroller 210 can receive according to liquid crystal display, produce pulse width modulation signal PWMS, that is the microcontroller 210 drive current ILED flowing through light-emitting diode 100 corresponding to signal of video signal that can receive according to liquid crystal display, produces pulse width modulation signal PWMS.Such as, when the signal of video signal that liquid crystal display receives needs larger drive current ILED, microcontroller 210 can produce the pulse width modulation signal PWMS of low frequency.In addition, Fig. 4 A is all identical with the embodiment of Fig. 3 B with Fig. 3 A with all the other operating principles of the embodiment of Fig. 4 B, does not repeat them here.
In sum, controller in order to light modulation light-emitting diode disclosed in this invention and method be according to microcontroller produce pulse width modulation signal and a critical value, determine that controller operates in digital dimming mode or analog dimming mode, so the pulse width modulation signal that the present invention only needs a pin to receive microcontroller to be produced, controller can be made to switch between digital dimming mode and analog dimming mode.Therefore, compared to prior art because the present invention be according to microcontroller produce pulse width modulation signal and critical value, determine controller operate in digital dimming mode or analog dimming mode, so the present invention must not revise printed circuit board (PCB) accordingly.In addition, the present invention be according to microcontroller produce pulse width modulation signal and critical value, determine controller operate in digital dimming mode or analog dimming mode, so the present invention can't increase extra burden.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (15)
1., in order to a controller for light modulation light-emitting diode, it is characterized in that comprising:
One pulse width modulation pin, in order to receive the pulse width modulation signal that a microcontroller produces;
One low pass filter, in order to according to described pulse width modulation signal, produces a direct current signal;
One frequency detecting unit, in order to according to a critical value and described pulse width modulation signal, produces a logical value; And
One control signal generation module, be coupled to described low pass filter and described frequency detecting unit, in order to according to described direct current signal, described logical value, a reference voltage and described pulse width modulation signal, produce first switch of a switch controlling signal to described light-emitting diode of connecting, wherein said first switch opens and closes according to described switch controlling signal;
Wherein when the frequency of described pulse width modulation signal is lower than described critical value, described controller enters a digital dimming mode, and when the frequency of described pulse width modulation signal is higher than described critical value, described controller enters an analog dimming mode.
2. controller as claimed in claim 1, is characterized in that: described control signal generation module comprises:
One multiplexer, be coupled to described low pass filter and described frequency detecting unit, in order to according to described logical value, export described reference voltage or described direct current signal, wherein when the frequency of described pulse width modulation signal is lower than described critical value, described multiplexer exports described reference voltage, and when the frequency of described pulse width modulation signal is higher than described critical value, described multiplexer exports described direct current signal;
One logical block, be coupled to described frequency detecting unit, in order to receive described pulse width modulation signal and described logical value, and export a rp pulse width modulation signal or first logical value anti-phase with described logical value, wherein when the frequency of described pulse width modulation signal is lower than described critical value, described logical block exports described rp pulse width modulation signal, and when the frequency of described pulse width modulation signal is higher than described critical value, described logical block exports described first logical value;
One transmission unit, is coupled to described multiplexer and described logical block, in order to export described reference voltage and described direct current signal one of them, and export described rp pulse width modulation signal and described first logical value one of them;
One second switch, be coupled to described transmission unit, in order to according to described rp pulse width modulation signal or described first logical value, perform a corresponding action, wherein when described second switch is opened, described first switch cuts out, and when described second switch is closed, described first switch open; And
One comparator, is coupled to described transmission unit, in order to according to described reference voltage and described direct current signal one of them and a sensing voltage, produces described switch controlling signal to described first switch;
Wherein when described comparator is according to described reference voltage and described sensing voltage, when producing described switch controlling signal to described first switch, described controller enters described digital dimming mode, and when described comparator is according to described direct current signal and described sensing voltage, when producing described switch controlling signal to described first switch, described controller enters described analog dimming mode.
3. controller as claimed in claim 2, is characterized in that: when described controller start, and described controller is that acquiescence enters described digital dimming mode or described analog dimming mode.
4. controller as claimed in claim 2, it is characterized in that: when described controller normal operation, described controller is according to described pulse width modulation signal and described critical value, switch described digital dimming mode to described analog dimming mode, or switch described analog dimming mode to described digital dimming mode.
5. controller as claimed in claim 1, is characterized in that: described switch controlling signal is sent to described first switch by a grid pin.
6. the method in order to light modulation light-emitting diode, the controller being wherein applied to described method comprises a pulse width modulation pin, a low pass filter, a frequency detecting unit and a control signal generation module, wherein said control signal generation module comprises a multiplexer, a logical block, a transmission unit, a second switch and a comparator, and the feature of described method is to comprise:
Described pulse width modulation pin receives the pulse width modulation signal that a microcontroller produces;
Described low pass filter, according to described pulse width modulation signal, produces a direct current signal;
Described frequency detecting unit, according to a critical value and described pulse width modulation signal, produces a logical value; And
Described control signal generation module is according to described direct current signal, described logical value, a reference voltage and described pulse width modulation signal, produce first switch of a switch controlling signal to described light-emitting diode of connecting, wherein said first switch opens and closes according to described switch controlling signal;
Wherein when the frequency of described pulse width modulation signal is lower than described critical value, described controller enters a digital dimming mode, and when the frequency of described pulse width modulation signal is higher than described critical value, described controller enters an analog dimming mode.
7. method as claimed in claim 6, it is characterized in that: described control signal generation module, according to described direct current signal, described logical value, described reference voltage and described pulse width modulation signal, produces described switch controlling signal to described first switch and comprises:
When the frequency of described pulse width modulation signal is lower than described critical value, described multiplexer exports described reference voltage;
When the frequency of described pulse width modulation signal is lower than described critical value, described logical block exports a rp pulse width modulation signal;
Described transmission unit exports described reference voltage, and exports described rp pulse width modulation signal;
Described second switch, according to described rp pulse width modulation signal, opens and closes, and wherein when described second switch is opened, described first switch cuts out, and when described second switch is closed, described first switch open; And
Described comparator, according to described reference voltage and a sensing voltage, produces described switch controlling signal to described first switch;
Wherein when described comparator is according to described reference voltage and described sensing voltage, when producing described switch controlling signal to described first switch, described controller enters described digital dimming mode.
8. method as claimed in claim 6, it is characterized in that: described control signal generation module, according to described direct current signal, described logical value, described reference voltage and described pulse width modulation signal, produces described switch controlling signal to described first switch and comprises:
When the frequency of described pulse width modulation signal is higher than described critical value, described multiplexer exports described direct current signal;
When the frequency of described pulse width modulation signal is higher than described critical value, described logical block exports first logical value anti-phase with described logical value;
Described transmission unit exports described direct current signal, and exports described first logical value;
Described second switch is closed according to described first logical value, wherein when described second switch is closed, and described first switch open; And
Described comparator, according to described direct current signal and a sensing voltage, produces described switch controlling signal to described first switch;
Wherein when described comparator is according to described direct current signal and described sensing voltage, when producing described switch controlling signal to described first switch, described controller enters described analog dimming mode.
9. method as claimed in claim 6, is characterized in that: when described controller start, and described controller is that acquiescence enters described digital dimming mode or described analog dimming mode.
10. method as claimed in claim 6, it is characterized in that: when described controller normal operation, described controller is according to described pulse width modulation signal and described critical value, switch described digital dimming mode to described analog dimming mode, or switch described analog dimming mode to described digital dimming mode.
11. 1 kinds of methods in order to light modulation light-emitting diode, wherein said light-emitting diode is applied to a liquid crystal display, and the controller being applied to described method comprises a pulse width modulation pin, a low pass filter, a frequency detecting unit and a control signal generation module, wherein said control signal generation module comprises a multiplexer, a logical block, a transmission unit, a second switch and a comparator, and the feature of described method is to comprise:
Described pulse width modulation pin receives the pulse width modulation signal that a microcontroller produces according to the signal of video signal that described liquid crystal display receives;
Described low pass filter, according to described pulse width modulation signal, produces a direct current signal;
Described frequency detecting unit, according to a critical value and described pulse width modulation signal, produces a logical value; And
Described control signal generation module is according to described direct current signal, described logical value, a reference voltage and described pulse width modulation signal, produce first switch of a switch controlling signal to described light-emitting diode of connecting, wherein said first switch opens and closes according to described switch controlling signal;
Wherein when the frequency of described pulse width modulation signal is lower than described critical value, described controller enters a digital dimming mode, and when the frequency of described pulse width modulation signal is higher than described critical value, described controller enters an analog dimming mode.
12. methods as claimed in claim 11, it is characterized in that: described control signal generation module, according to described direct current signal, described logical value, described reference voltage and described pulse width modulation signal, produces described switch controlling signal to described first switch and comprises:
When the frequency of described pulse width modulation signal is lower than described critical value, described multiplexer exports described reference voltage;
When the frequency of described pulse width modulation signal is lower than described critical value, described logical block exports a rp pulse width modulation signal;
Described transmission unit exports described reference voltage and described rp pulse width modulation signal;
Described second switch, according to described rp pulse width modulation signal, opens and closes, and wherein when described second switch is opened, described first switch cuts out, and when described second switch is closed, described first switch open; And
Described comparator, according to described reference voltage and a sensing voltage, produces described switch controlling signal to described first switch;
Wherein when described comparator is according to described reference voltage and described sensing voltage, when producing described switch controlling signal to described first switch, described controller enters described digital dimming mode.
13. methods as claimed in claim 11, it is characterized in that: described control signal generation module, according to described direct current signal, described logical value, described reference voltage and described pulse width modulation signal, produces described switch controlling signal to described first switch and comprises:
When the frequency of described pulse width modulation signal is higher than described critical value, described multiplexer exports described direct current signal;
When the frequency of described pulse width modulation signal is higher than described critical value, described logical block exports first logical value anti-phase with described logical value;
Described transmission unit exports described direct current signal and described first logical value;
Described second switch is closed according to described first logical value, wherein when described second switch is closed, and described first switch open; And
Described comparator, according to described direct current signal and a sensing voltage, produces described switch controlling signal to described first switch;
Wherein when described comparator is according to described direct current signal and described sensing voltage, when producing described switch controlling signal to described first switch, described controller enters described analog dimming mode.
14. methods as claimed in claim 11, is characterized in that: described pulse width modulation signal is the various play mode, various contrast or the various white balance that have corresponding to described liquid crystal display.
15. methods as claimed in claim 14, is characterized in that: described various play mode comprises a film mode, an electronic game pattern, a three dimensional pattern and a two-dimensional model.
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| CN201410270531.2A CN105263209B (en) | 2014-06-17 | 2014-06-17 | To dim the controller of light emitting diode and method |
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| CN201410270531.2A CN105263209B (en) | 2014-06-17 | 2014-06-17 | To dim the controller of light emitting diode and method |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| US20120147062A1 (en) * | 2010-12-08 | 2012-06-14 | Bogun Seo | Liquid Crystal Display and Scanning Back Light Driving Method Thereof |
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Patent Citations (3)
| 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 |
| US20120147062A1 (en) * | 2010-12-08 | 2012-06-14 | Bogun Seo | Liquid Crystal Display and Scanning Back Light Driving Method Thereof |
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