CN104918386A - LED drive circuit and liquid crystal display device - Google Patents
LED drive circuit and liquid crystal display device Download PDFInfo
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- CN104918386A CN104918386A CN201510348881.0A CN201510348881A CN104918386A CN 104918386 A CN104918386 A CN 104918386A CN 201510348881 A CN201510348881 A CN 201510348881A CN 104918386 A CN104918386 A CN 104918386A
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Abstract
The embodiment of the invention provides an LED drive circuit and a liquid crystal display device, which can achieve accurate control on the current of an LED lamp string. The LED drive circuit comprises an LLC resonant circuit, a full bridge rectification and filtering module, an LED lamp string module, a current detection circuit module, a control circuit module and a drive transformer, and the output end of the LLC resonant circuit is connected with the input end of the full bridge rectification and filtering module; the output end of the full bridge rectification and filtering module is connected with the positive pole of the LED lamp string module; the negative pole of the LED string module is connected with the first end of the current detection circuit module; the first end of the current detection circuit module is connected with the first end of the control circuit module, and the second end of the current detection circuit module is grounded; the second end of the control circuit module is connected with the secondary first end of the drive transformer, the third end of the control circuit module is connected with the secondary second end of the drive transformer, and the primary winding of the drive transformer is connected with the LLC resonant circuit module. The LED drive circuit and the liquid crystal display device are applicable to the field of liquid crystal TVs.
Description
Technical field
The present invention relates to LCD TV field, particularly relate to a kind of LED (Light Emitting Diode, that is: light-emitting diode) drive circuit and liquid crystal indicator.
Background technology
Current LCD TV field, adopts LED-backlit to become industry main flow.As shown in Figure 1, a kind of LED drive circuit for providing in prior art.In this LED drive circuit, chip IC 914 is in high-pressure area, and LED string is in area of low pressure, in order to by the current feedback of LED string part to chip IC 914, need to use the opto-coupled feedback circuit in Fig. 1 to carry out current feedback.But, because opto-coupled feedback circuit needs the regular hour when carrying out opto-electronic conversion, like this, to certain delay be there is in the response of the current feedback signal of chip IC 914 pairs of LED string parts, thus make the control of chip IC 914 pairs of LED crosstalk streams become inaccurate, above-mentioned delay is easy to cause the LED crosstalk stream under dimming state to there is spike (as shown in Figure 2), is also easy to produce noise in the transformer T904 of LED string simultaneously.
Therefore, how realizing the accurate control to LED crosstalk stream, is the technical problem needing solution at present badly.
Summary of the invention
Embodiments of the invention provide a kind of LED drive circuit and liquid crystal indicator, can realize the accurate control to LED crosstalk stream.
For achieving the above object, embodiments of the invention adopt following technical scheme:
First aspect, provide a kind of LED drive circuit, described LED drive circuit comprises: LLC resonant circuit module, full-bridge rectifier filter module, LED string module, current detection circuit module, control circuit module and and driving transformer; Wherein,
The output of described LLC resonant circuit module is connected with the input of described full-bridge rectifier filter module;
The output of described full-bridge rectifier filter module is connected with the positive pole of described LED string module;
The negative pole of described LED string module is connected with the first end of described current detection circuit module;
The first end of described current detection circuit module is also connected with the first end of described control circuit module, the second end ground connection of described current detection circuit module;
Second end of described control circuit module is connected with the secondary first end of described driving transformer, 3rd end of described control circuit module is connected with secondary second end of described driving transformer, the elementary and described LLC resonant circuit model calling of described driving transformer.
Second aspect, present invention also offers a kind of liquid crystal indicator, is provided with above-mentioned LED drive circuit.
Based on the LED drive circuit that the above embodiment of the present invention provides, this LED drive circuit carries out the current feedback of LED string part by current detection circuit module, control circuit module and driving transformer, on the one hand, this driving transformer is used for the isolation of the high-voltage alternating signal of telecommunication, make LED string be in area of low pressure, ensure that the normal work of LED string.On the other hand, the negative pole of LED string module is connected with the first end of described current detection circuit module, and the first end of described current detection circuit module is also connected with the first end of described control circuit module, that is, feedback signal can be directly transferred to control circuit module by the LED string in this LED drive circuit, thus decrease the delay of signal, the control of control circuit module to LED crosstalk stream is made to become accurate, and then avoid the spike phenomenon of the LED crosstalk stream in Fig. 2, LED string current waveform figure as shown in Figure 6 can be obtained.
Accompanying drawing explanation
Fig. 1 is existing LED drive circuit schematic diagram;
Fig. 2 is LED string current waveform figure in existing LED drive circuit;
The LED drive circuit schematic diagram one that Fig. 3 (a) provides for the embodiment of the present invention;
The LED drive circuit schematic diagram two that Fig. 3 (b) provides for the embodiment of the present invention;
The LED drive circuit schematic diagram three that Fig. 4 provides for the embodiment of the present invention;
Fig. 5 is the working timing figure of LLC resonant circuit module in Fig. 4;
LED string current waveform figure in the LED drive circuit that Fig. 6 provides for the embodiment of the present invention;
The LED drive circuit schematic diagram four that Fig. 7 provides for the embodiment of the present invention;
The LED drive circuit schematic diagram five that Fig. 8 provides for the embodiment of the present invention;
The LED drive circuit schematic diagram six that Fig. 9 provides for the embodiment of the present invention;
Figure 10 is the connection diagram of under-voltage protecting circuit module in Fig. 9;
The LED drive circuit schematic diagram seven that Figure 11 provides for the embodiment of the present invention;
Figure 12 is the connection diagram of 3D control circuit module in Figure 11.
Embodiment
Referring now to accompanying drawing, multiple embodiment is described, wherein by identical Reference numeral instruction similar elements herein.In the following description, for ease of explaining, a large amount of detail is given, to provide the complete understanding to one or more embodiment.But, clearly, also described embodiment can be realized without these details.In other example, known features and equipment are shown in block diagram form, so that describe one or more embodiment.
Term " first ", " second " are only for describing object, and instruction or hint relative importance can not be interpreted as or imply the quantity indicating indicated technical characteristic, thus, be limited with " first ", the feature of " second " can express or impliedly comprise one or more these features.In following examples, " first " and " second " is only for difference, as first end and the second end, for another example: the first LED string, and the second LED string, etc.
Shown in Fig. 3 (a), the embodiment of the present invention provides a kind of LED drive circuit, comprising: LLC resonant circuit module 31, full-bridge rectifier filter module 33, LED string module 34, current detection circuit module 35, control circuit module 36 and driving transformer T1.Wherein,
The output of described LLC resonant circuit module 31 is connected with the input of described full-bridge rectifier filter module 33.
The output of described full-bridge rectifier filter module 33 is connected with the positive pole of described LED string module 34.
The negative pole of described LED string module 34 is connected with the first end V0 of described current detection circuit module 35.
The first end V0 of described current detection circuit module 35 is also connected with the first end V2 of described control circuit module 36, the second end V1 ground connection of described current detection circuit module 35.
Second end V3 of described control circuit module 36 is connected with the secondary first end of described driving transformer T1,3rd end V4 of described control circuit module 36 is connected with secondary second end of described driving transformer T1, and the elementary and described LLC resonant circuit module 31 of described driving transformer T1 is connected.
Wherein, the electric current of the LED string that described control circuit module 36 is fed back for received current testing circuit module 35, and transmit control signal to drive circuit module 37, via drive circuit module 37 by the current feedback of LED string to LLC resonant circuit module 31.
It should be noted that, in figure 3, the first end V0 of described current detection circuit module 35 is connected with the first end V2 of described control circuit module 36 respectively and the negative pole of described LED string module 34 connects, suppose the electric current of the first end V0 of current detection circuit module 35 (namely, the electric current of LED string) be I (V0), then described current detection and feedback circuit module 35 is for adjusting electric current I (V0).
It should be noted that, in the embodiment of the present invention, the negative pole of described LED string module 34 is connected with the first end V0 of described current detection circuit module 35, specifically refer to, in described LED string module 34, the negative pole of any paths of LEDs lamp string is connected with the first end V0 of described current detection circuit module 35, the minus earth of all the other LED strings.Certainly, the negative pole of described LED string module 34 is connected with the first end V0 of described current detection circuit module 35, also can refer to, in described LED string module 34, the negative pole of all LED strings is connected with the first end V0 of described current detection circuit module 35, and the embodiment of the present invention does not do concrete restriction to this.
Based on the LED drive circuit that the above embodiment of the present invention provides, this LED drive circuit carries out the current feedback of LED string part by current detection circuit module, control circuit module and driving transformer, on the one hand, driving transformer is used for the isolation of the high-voltage alternating signal of telecommunication, make LED string be in area of low pressure, ensure that the normal work of LED string.On the other hand, the negative pole of LED string module is connected with the first end of described current detection circuit module, and the first end of described current detection circuit module is also connected with the first end of described control circuit module, that is, feedback signal can be directly transferred to control circuit module by the LED string in this LED drive circuit, thus decrease the delay of signal, the control of control circuit module to LED crosstalk stream is made to become accurate, and then avoid the spike phenomenon of the LED crosstalk stream in Fig. 2, LED string current waveform figure as shown in Figure 6 can be obtained.
Further, shown in Fig. 3 (b), described LED string module 34 comprises the first LED string second LED string.
The output of described full-bridge rectifier filter module 33 is connected with the positive pole of described LED string module 34, comprising:
First output end vo ut31 of described full-bridge rectifier filter module 33 is connected with the positive pole of the first LED string in described LED string module 34, and the second output end vo ut41 of described full-bridge rectifier filter module is connected with the positive pole of the second LED string in described LED string module 34.
The negative pole of described LED string module 34 is connected with the first end V0 of described current detection circuit module 35, comprising:
The first LED string in described LED string module 34 or the negative pole of the second LED string are connected with the first end V0 of described current detection circuit module 35, the minus earth of all the other LED strings.
Described LED drive circuit also comprises: balance flow equalizing circuit module 32, described balance flow equalizing circuit module comprises the first electric capacity C11.Wherein,
The output of described LLC resonant circuit module 31 is connected with the input of described full-bridge rectifier filter module 33, comprising:
Be connected with the first input end Vin11 of described full-bridge rectifier filter module 33 after the described first electric capacity C11 of first output end vo ut11 series connection of described LLC resonant circuit module 31;
Second output end vo ut212 of described LLC resonant circuit module 31 is connected with the second input Vin21 of described full-bridge rectifier filter module 33.
Concrete, as shown in Figure 4, in a kind of possible implementation, LLC resonant circuit module 31 specifically can comprise:
Field-effect transistor Q1, field-effect transistor Q2, resonant capacitance C3, equivalent inductance Lr, magnetizing inductance Lm and resonance transformer T2.
Wherein, the grid of field-effect transistor Q1 is connected with the elementary first end of driving transformer T1, the grid of field-effect transistor Q2 is connected with elementary second end of driving transformer T1, the source electrode of field-effect transistor Q2 and the elementary three-terminal link of driving transformer T1, and the source ground of field-effect transistor Q2.Field-effect transistor Q1 and field-effect transistor Q2 forms half-bridge driven, be connected with the elementary first end of resonance transformer T2 after the output Vds2 series equivalent inductance L r of this half-bridge driven, and the output Vds2 of this half-bridge driven is connected with elementary 4th end of driving transformer T1.Be connected with elementary second end of resonance transformer T2 after the source series resonant capacitance C3 of field-effect transistor Q2, the first end of magnetizing inductance Lm is connected with the elementary first end of the T2 of described resonance transformer, and second end of magnetizing inductance Lm is connected with elementary second end of described resonance transformer T2.
Full-bridge rectifier filter module 33 specifically can comprise:
Diode VD11, its positive pole is connected with second pole of described first electric capacity C11, and negative pole is connected with the positive pole of described first LED string;
Diode VD21, its plus earth, negative pole is connected with second pole of described first electric capacity C11;
Diode VD31, its plus earth, negative pole is connected with secondary second end of described resonance transformer T2;
Diode VD41, its positive pole is connected with secondary second end of described resonance transformer T2, and negative pole is connected with the positive pole of described second LED string;
Electric capacity C11, its first pole ground connection, the second pole is connected with the positive pole of described first LED string;
Electric capacity C31, its first pole ground connection, the second pole is connected with the positive pole of described second LED string.
Current detection circuit module 35 specifically can comprise: resistance R1, like this, and the voltage/R1 of the first end V2 of I (V0)=control circuit module 36.
It should be noted that, control circuit module specifically can be made up of the peripheral circuit of a chip and this chip, and the embodiment of the present invention does not do concrete restriction to this.
In order to allow those skilled in the art better understand the present invention, below by as follows to the operation principle brief description of the partial circuit in the circuit shown in Fig. 4:
1) LLC resonant circuit module
The working timing figure of LLC resonant circuit module as shown in Figure 5, wherein,
In (t1, the t2) time period:
Q1 turns off, Q2 conducting, and inductance L r and C3 carries out resonance, and secondary VD11, VD31 turn off, VD41, VD21 conducting, and now energy is converted to secondary from C3, Lr, to the second LED statements based on collusion electricity, gives secondary capacitance C31 charging, until Q2 turns off simultaneously.
In (t2, the t3) time period:
Q1 and Q2 turns off simultaneously, is now in Dead Time.Secondary VD11, VD31, VD41, VD21 turn off, and secondary capacitance C11 and C31 gives the first LED string and the second LED statements based on collusion electricity respectively.Now inductance L r, Lm electric current charges to the output capacitance of Q2 (internal capacitance of Q2, not shown), to the output capacitance of the Q1 (internal capacitance of Q1, not shown) electric discharge, until the voltage of the output capacitance of Q2 (internal capacitance of Q2, not shown) equals DC.When Q1 conducting, this phase place terminates.
In (t3, the t4) time period:
Q1 conducting, Q2 turns off, VD11, VD31 conducting, and VD41, VD21 turn off, C3 and Lr resonance, energy is transformed into secondary to the first LED statements based on collusion electricity from C3, Lr, give secondary capacitance C11 charging, now the electric current of Lm turns back to DC by Q1, terminates until the electric current of Lr is zero this phase place simultaneously.
In (t4, the t5) time period:
Q1 conducting, Q2 turns off, VD11, VD31 conducting, and VD41, VD21 turn off, C3 and Lr resonance, and energy is transformed into secondary to the first LED statements based on collusion electricity from input, give secondary capacitance C11 charging simultaneously, terminate until Q1 turns off this phase place.
In (t5, the t6) time period:
Q1, Q2 turn off simultaneously, and VD11, VD31, VD41, VD21 turn off, and secondary capacitance C11 and C31 gives the first LED string and the second LED statements based on collusion electricity respectively.Primary current I (Lr+Lm) is to the output capacitance of the Q1 (internal capacitance of Q1, not shown) charging, to the output capacitance of the Q2 (internal capacitance of Q2, not shown) electric discharge, until the voltage of the output capacitance of Q2 (internal capacitance of Q2, not shown) is zero.Now Q2 starts conducting, and during Q2 conducting, this phase place terminates.
In (t6, the t7) time period:
Q1 turns off, Q2 conducting, inductance L r and C3 carries out resonance, and secondary VD11, VD31 turn off, VD41, VD21 conducting, now energy is from C3, Lr is converted to secondary, to the second LED statements based on collusion electricity, gives secondary capacitance C31 charging simultaneously, Lr electric current is oppositely got back to elementary through Q2, when Lr electric current is zero, this phase place terminates.
2) full-bridge rectification filter circuit module:
As mentioned above, when VD11, VD31 conducting, when VD41, VD21 turn off: electric current flows out after C21 and VD11 from the secondary first end of T2, charges to C11, and to the first LED statements based on collusion electricity, C21 is in charged state simultaneously, and its current potential is that the right side is just being born in a left side.
When VD41, VD21 conducting, when VD11, VD31 turn off: electric current flows out from secondary second end of T2 and charges to C31 through VD41, and after giving the second LED statements based on collusion electricity, then get back to the secondary first end of T2 through VD21 and C21, C21 electric discharge simultaneously.
When Q1 conducting, when Q2 turns off, T2 time level first end is just, the second end is negative, if its voltage difference is V
p; When Q2 conducting, when Q1 turns off, T2 time level first end is negative, and the second end is just, if its voltage difference is Vn; Direct voltage on C21 is V_C21, and the left side is just on the right of negative, and C11 both end voltage is V_C11, and C31 both end voltage is V_C31.Suppose that the work period of LLC resonant circuit is Ts; VD11, VD31 conducting, when VD41, VD21 turn off, the electric current flowing through T2 level is Isp (t), and ON time is t1; VD41, VD21 conducting, when VD11, VD31 turn off, the electric current flowing through T2 level is Isn (t), and ON time is t2, then:
Wherein, Io_LED1 represents the electric current of the first LED string, and Io_LED2 represents the electric current of the second LED string.
Because the electric quantity balancing of the discharge and recharge of C21, so Io_LED1=Io_LED2;
In the t1 time period, Vp-V_C21=V_C11;
Be interrupted when t2, Vn+V_C21=V_C31;
Because Q1 and Q2 does the open and close of half-bridge symmetry, that is the duty ratio of Q1 and Q2 is 0.5, therefore Vp=Vn, V_C21=(V_C11+V_C31)/2
Thus when the operating voltage of the first LED string and the second LED string is variant, C21 both can regulate the direct current (DC) bias on it automatically, and the volt-seconds value of T2 level can be made again to balance.And due to the charge volume of C21 equal with discharge capacity, so C21 can also make two paths of LED lamp string electric current realize balance.
Further, as shown in Figure 7, described LED drive circuit also comprises:
M group described full-bridge rectifier filter module 33 and M group described LED string module 34, M be not less than 1 positive integer.
Described balance flow equalizing circuit module 32 also comprises: balance inductance L1 and M described first electric capacity C11.
Wherein, other M the first output end vo ut11 of described LLC resonant circuit module M the first input end Vin11 of full-bridge rectifier filter module 33 described with M group respectively that respectively to connect after the first electric capacity C11 described in is connected; The other M of described LLC resonant circuit module 31 the second output end vo ut21 connects respectively after described balance inductance L1 and is connected with M the second input Vin21 of the described full-bridge rectifier filter module 33 of M group.
The the first output end vo ut31 often organizing full-bridge rectifier filter module 33 is connected with the positive pole often organizing the first LED string in LED string module 34, and the second output end vo ut41 often organizing full-bridge rectifier filter module is connected with the positive pole often organizing the second LED string in LED string module 34.
The first LED string often in group LED string module and the minus earth of the second LED string.
Wherein, the second output of described LLC resonant circuit module 31 is connected with the second input Vin21 of described full-bridge rectifier filter module 33, specifically can comprise:
Second output of described LLC resonant circuit module 31 is connected with the second input Vin21 of described full-bridge rectifier filter module 33 by described balance inductance L1.
Concrete, in embodiments of the present invention, because the charge volume of balance inductance L1 is equal with discharge capacity, therefore the current balance type between different LED string light module 34 can be realized by balance inductance L1, relative theory can illustrate with reference to the principle of current balance type between above-mentioned two paths of LED lamp string, repeats no more herein.Wherein, the electric current that current detection circuit 35 can choose wherein arbitrary paths of LEDs lamp string carries out detection feedback, and the embodiment of the present invention does not do concrete restriction to this.
Preferably, as shown in Figure 8, the LED drive circuit that the embodiment of the present invention provides also comprises: the second electric capacity C2; Wherein,
First pole of described second electric capacity C2 is connected with the secondary first end of described driving transformer T1, and second pole of described second electric capacity C2 is connected with the second end V3 of described control circuit module 36.
Wherein, this second electric capacity C2 is specially capacitance, the DC influence signal of driving transformer T1 level can be prevented to be converted into the elementary of driving transformer T1, and then cause LLC resonant circuit normally to work, play a protective role to this LED drive circuit.
Further, as shown in Figure 9, the LED drive circuit that the embodiment of the present invention provides also comprises: (M+1) organizes under-voltage protecting circuit module 38; Wherein,
The first input end Vin31 often organizing under-voltage protecting circuit module 38 is connected with the first output end vo ut31 often organizing full-bridge rectifier filter module 33; the the second input Vin41 often organizing under-voltage protecting circuit module 38 is connected with the second output end vo ut41 often organizing full-bridge rectifier filter module 33, and the output end vo ut51 often organizing under-voltage protecting circuit module 38 is connected with the under-voltage protection end V5 of described control circuit module 36.
Concrete, as shown in Figure 9, be the formation schematic diagram of one group of under-voltage protecting circuit module 38.This under-voltage protecting circuit module 38 specifically can comprise:
First resistance R11, its first end is connected with the first output end vo ut31 of full-bridge rectifier filter module 33, and the second end is connected with the first end of the second resistance R12;
Second resistance R12, its first end is connected with second end of the first resistance R11, the second end ground connection;
3rd resistance R21, its first end is connected with the second output end vo ut41 of full-bridge rectifier filter module 33, and the second end is connected with the first end of the 4th resistance R22;
4th resistance R22, its first end is connected with second end of the 3rd resistance R21, the second end ground connection;
First diode VD51, its positive pole is connected with second end of the first resistance R11, and negative pole is connected with the under-voltage protection end V5 of control circuit module 36;
Second diode VD61, its positive pole is connected with second end of the 3rd resistance R21, and negative pole is connected with the under-voltage protection end V5 of control circuit module 36.
The embodiment of the present invention increases under-voltage protecting circuit module 38 often organizing full-bridge rectifier filter module 33 and often organize between LED string module 34, and the output of under-voltage protecting circuit module 38 is connected with the under-voltage protection end of control circuit module, during due to the short circuit of LED string, LED string both end voltage is 0, and then cause Vin31 and Vin41 place voltage to be 0, Vout51 place voltage is also 0, therefore after Vout51 is connected with the under-voltage protection end V5 of described control circuit module 36, the voltage that can make the under-voltage protection end V5 of described control circuit module 36 is 0, and then the under-voltage protection function of flip chip inside, chip is quit work, thus can when the short circuit of LED string timely protecting control circuit module.
Optionally, as shown in figure 11, the LED drive circuit that the embodiment of the present invention provides also comprises: 3D control circuit module 39.
Wherein, the signal output part PWM of described 3D control circuit module 39 is connected with the five terminal V6 of described control circuit control module 36.
Concrete, as shown in figure 12, be the formation schematic diagram of 3D control circuit module 39.This 3D control circuit module 39 specifically can comprise:
3rd diode VD71, its positive pole is connected with the 2D signal input part 2D_PWM of described 3D control circuit mould 39 pieces, and negative pole is connected with the signal output part PWM of described 3D control circuit module 39;
The first transistor M1, its base stage is connected with the 3D signal Enable Pin 3D_ENA of described 3D control circuit module 39, and collector electrode is connected with the positive pole of described 3rd diode VD71, grounded emitter;
Transistor seconds M2, its base stage is connected with the collector electrode of third transistor M3, and emitter is connected with the 3D signal input part 3D_PWM of described 3D control circuit module 39, and collector electrode is connected with the signal output part PWM of described 3D control circuit module 39;
Transistor seconds M3, its base stage is connected with the 3D signal Enable Pin 3D_ENA of described 3D control circuit module 39, and its collector electrode is connected with the base stage of described transistor seconds M2, its grounded emitter; Wherein,
Described signal output part PWM is connected with the five terminal V6 of described control circuit control module 36.
Concrete, as shown in figure 12, described the first transistor and described third transistor are specifically as follows NPN pipe, and described transistor seconds is specifically as follows PNP pipe.
Wherein, in fig. 11, when 3D signal Enable Pin 3D_ENA has signal to input, the voltage of 2D signal input part 2D_PWM can be dragged down, M2 conducting, and then signal output part PWM can export the 3D signal of 3D signal input part 3D_PWM, thus realizes the object of 3D control.
Present invention also offers a kind of liquid crystal indicator, be provided with above-mentioned any LED drive circuit.
Because liquid crystal indicator comprises above-mentioned any LED drive circuit, therefore in liquid crystal indicator, the drive circuit of LED is while being in the place of safety of low-voltage by LED string module, make to become accurate to the control of LED crosstalk stream, and then avoid the spike phenomenon of the LED crosstalk stream in Fig. 2, LED string current waveform as shown in Figure 6 can be obtained.The backlight of liquid crystal indicator is exported more level and smooth, improve the display effect of liquid crystal indicator.
The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; change can be expected easily or replace, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should described be as the criterion with the protection range of claim.
Claims (10)
1. a LED drive circuit, is characterized in that, described LED drive circuit comprises: LLC resonant circuit module, full-bridge rectifier filter module, LED string module, current detection circuit module, control circuit module and driving transformer; Wherein,
The output of described LLC resonant circuit module is connected with the input of described full-bridge rectifier filter module;
The output of described full-bridge rectifier filter module is connected with the positive pole of described LED string module;
The negative pole of described LED string module is connected with the first end of described current detection circuit module;
The first end of described current detection circuit module is also connected with the first end of described control circuit module, the second end ground connection of described current detection circuit module;
Second end of described control circuit module is connected with the secondary first end of described driving transformer, 3rd end of described control circuit module is connected with secondary second end of described driving transformer, the elementary and described LLC resonant circuit model calling of described driving transformer.
2. LED drive circuit according to claim 1, is characterized in that, described LED string module comprises the first lamp string and the second LED string;
The output of described full-bridge rectifier filter module is connected with the positive pole of described LED string module, comprising:
First output of described full-bridge rectifier filter module is connected with the positive pole of the first LED string in described LED string module, and the second output of described full-bridge rectifier filter module is connected with the positive pole of the second LED string in described LED string module;
The negative pole of described LED string module is connected with the first end of described current detection circuit module, comprising:
The first LED string in described LED string module or the negative pole of the second LED string are connected with the first end of described current detection circuit module, the minus earth of all the other LED strings;
Described LED drive circuit also comprises: balance flow equalizing circuit module, and described balance flow equalizing circuit module comprises the first electric capacity; Wherein,
The output of described LLC resonant circuit module is connected with the input of described full-bridge rectifier filter module, comprising:
Be connected with the first input end of described full-bridge rectifier filter module after described first electric capacity of first output series connection of described LLC resonant circuit module;
Second output of described LLC resonant circuit module is connected with the second input of described full-bridge rectifier filter module.
3. LED drive circuit according to claim 2, is characterized in that, described LED drive circuit also comprises:
M group described full-bridge rectifier filter module and M group described LED string module, M be not less than 1 positive integer;
Described balance flow equalizing circuit module also comprises: balance inductance and M described first electric capacity;
Wherein, other M first output of described LLC resonant circuit module M first input end of full-bridge rectifier filter module described with M group respectively of respectively connecting after the first electric capacity described in one is connected; The other M of described LLC resonant circuit module the second output is connected respectively after described balance inductance and is connected with M the second input of the described full-bridge rectifier filter module of M group;
The first output often organizing full-bridge rectifier filter module is connected with the positive pole often organizing the first LED string in LED string module, and the second output often organizing full-bridge rectifier filter module is connected with the positive pole often organizing the second LED string in LED string module;
The first LED string often in group LED string module and the minus earth of the second LED string;
Wherein, the second output of described LLC resonant circuit module is connected with the second input of described full-bridge rectifier filter module, specifically comprises:
Second output of described LLC resonant circuit module is connected by second input of described balance inductance with described full-bridge rectifier filter module.
4. according to claim 1) LED drive circuit described in 3 any one, it is characterized in that, described current detection circuit module comprises: resistance.
5. according to claim 1) LED drive circuit described in 3 any one, it is characterized in that, described LED drive circuit comprises: the second electric capacity; Wherein,
First pole of described second electric capacity is connected with the secondary first end of described driving transformer, and the second pole of described second electric capacity is connected with the second end of described control circuit module.
6. LED drive circuit according to claim 3, is characterized in that, described LED drive circuit also comprises: (M+1) organizes under-voltage protecting circuit module; Wherein,
The first input end often organizing under-voltage protecting circuit module is connected with the first output often organizing full-bridge rectifier filter module; the second input often organizing under-voltage protecting circuit module is connected with the second output often organizing full-bridge rectifier filter module, and the output often organizing under-voltage protecting circuit module is connected with the under-voltage protection end of described control circuit module.
7. LED drive circuit according to claim 6, is characterized in that, described under-voltage protecting circuit module of often organizing comprises:
First resistance, its first end is connected with the first output of described full-bridge rectifier filter module, and the second end is connected with the first end of the second resistance;
Second resistance, its first end is connected with the second end of described first resistance, the second end ground connection;
3rd resistance, its first end is connected with the second output of described full-bridge rectifier filter module, and the second end is connected with the first end of the 4th resistance;
4th resistance, its first end is connected with the second end of described 3rd resistance, the second end ground connection;
First diode, its positive pole is connected with the second end of described first resistance, and negative pole is connected with the under-voltage protection end of described control circuit module;
Second diode, its positive pole is connected with the second end of described 3rd resistance, and negative pole is connected with the under-voltage protection end of described control circuit module.
8. according to claim 1) LED drive circuit described in 3 any one, it is characterized in that, described LED drive circuit also comprises: 3D control circuit module; Wherein,
The signal output part of described 3D control circuit module is connected with the five terminal of described control circuit control module.
9. LED drive circuit according to claim 8, is characterized in that, described 3D control circuit module comprises:
3rd diode, its positive pole is connected with the 2D signal input part of described 3D control circuit module, and negative pole is connected with the signal output part of described 3D control circuit module;
The first transistor, its base stage is connected with the 3D signal Enable Pin of described 3D control circuit module, and collector electrode is connected with the positive pole of described 3rd diode, grounded emitter;
Transistor seconds, its base stage is connected with the collector electrode of third transistor, and emitter is connected with the 3D signal input part of described 3D control circuit module, and collector electrode is connected with the signal output part of described 3D control circuit module;
Third transistor, its base stage is connected with the 3D signal Enable Pin of described 3D control circuit module, and collector electrode is connected with the base stage of described transistor seconds, grounded emitter; Wherein,
Described signal output part is connected with the five terminal of described control circuit control module.
10. a liquid crystal indicator, is characterized in that, comprises power 1) LED drive circuit described in 9 any one.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710960346.XA CN107635312A (en) | 2015-06-19 | 2015-06-19 | A kind of LED drive circuit and liquid crystal display device |
| CN201510348881.0A CN104918386A (en) | 2015-06-19 | 2015-06-19 | LED drive circuit and liquid crystal display device |
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| CN201510348881.0A CN104918386A (en) | 2015-06-19 | 2015-06-19 | LED drive circuit and liquid crystal display device |
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| CN201710960346.XA Pending CN107635312A (en) | 2015-06-19 | 2015-06-19 | A kind of LED drive circuit and liquid crystal display device |
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| CN113257198A (en) * | 2021-05-24 | 2021-08-13 | 四川长虹电器股份有限公司 | Driving circuit applied to backlight of LED television |
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