CN114783384A - Constant current drive circuit and display device - Google Patents

Constant current drive circuit and display device Download PDF

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Publication number
CN114783384A
CN114783384A CN202210394901.8A CN202210394901A CN114783384A CN 114783384 A CN114783384 A CN 114783384A CN 202210394901 A CN202210394901 A CN 202210394901A CN 114783384 A CN114783384 A CN 114783384A
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transformer
led channel
module
unit
diode
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CN114783384B (en
Inventor
周建华
李志杰
陈元晟
黄少华
王卫国
胡向峰
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Shenzhen Skyworth RGB Electronics Co Ltd
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Shenzhen Skyworth RGB Electronics Co Ltd
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/3413—Details of control of colour illumination sources
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current

Abstract

The invention discloses a constant current driving circuit and a display device, wherein the constant current circuit is applied to driving a plurality of LED channels in an LED channel group, and comprises: the device comprises an LLC module, a drive module and a power distribution module; the driving module is used for sampling the current of the LED channel through the power distribution module and outputting a driving signal to the LLC module according to a sampling result; the LLC module is electrically connected with the power distribution module and is used for converting the accessed direct current into alternating current according to the driving signal and outputting the alternating current to the power distribution module; the power distribution module is electrically connected with the plurality of paths of LED channels respectively and is used for conducting or disconnecting the corresponding LED channels according to the alternating current. According to the invention, the power distribution module is arranged, a plurality of constant current circuits in the traditional scheme are eliminated, primary energy conversion is omitted, and only the LLC module is required to directly convert input current into alternating current and then the corresponding LED channel is conducted through the power distribution module, so that constant current control is realized.

Description

Constant current drive circuit and display device
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a constant current driving circuit and a display device.
Background
With the increasing development of display technology, LED televisions are developed to large screen and high definition, and at present, because of the relationship between display area and resolution, the screen glass transmittance is low, the T-CON power is large, and the module power is increased by about 30% compared with that of common products.
In a television with large display area and high resolution in the market, the backlight power is large, and the LED channels generally adopt 6 channels and 8 channels, wherein a power supply and a constant current system are designed by a traditional scheme, and a plurality of paths of boost constant current circuits and the like need to be added, so that the scheme has low efficiency, high cost and the like.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the constant current driving circuit and the display device are provided to solve the problems of low efficiency and high cost of a constant current system.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a constant current driving circuit is applied to driving a plurality of LED channels in an LED channel group, and comprises: the device comprises an LLC module, a drive module and a power distribution module;
the driving module is respectively electrically connected with the LLC module and the power distribution module, and is used for sampling the current of the LED channel through the power distribution module and outputting a driving signal to the LLC module according to a sampling result;
the LLC module is electrically connected with the power distribution module and is used for converting the accessed direct current into alternating current according to the driving signal and outputting the alternating current to the power distribution module;
the power distribution module is electrically connected with the plurality of LED channels respectively, and is used for conducting or disconnecting the corresponding LED channels according to the alternating current.
Further, the LLC module includes an LLC unit and a first voltage transformation unit;
the LLC unit is electrically connected with the drive module and the first transformation unit respectively, and the LLC unit is used for converting the accessed direct current into alternating current according to the drive signal and outputting the alternating current to the first transformation unit;
the first voltage transformation unit is electrically connected with the power distribution module and is used for transforming the alternating current and outputting the alternating current to the power distribution module.
Further, the LLC unit includes a first field effect transistor and a second field effect transistor;
the grid electrode of the first field effect transistor is connected with the driving module, the drain electrode of the first field effect transistor is connected with the direct current, and the source electrode of the first field effect transistor is respectively connected with the driving module and the first voltage transformation unit;
the grid electrode of the second field effect transistor is connected with the driving module, the drain electrode of the second field effect transistor is connected with the source electrode of the first field effect transistor, and the source electrode of the second field effect transistor is connected with the first voltage transformation unit.
Further, the first voltage transformation unit comprises a first transformer, a second transformer and a first capacitor;
the primary end of the first transformer is respectively connected with the source electrode of the first field effect transistor and the drain electrode of the second field effect transistor, and the secondary end of the first transformer is connected with the power distribution module; one end of the first capacitor is connected with the source electrode of the second field effect transistor, and the other end of the first capacitor is connected with the primary end of the second transformer; the primary end of the second transformer is connected with the primary end of the first transformer in series, the secondary end of the second transformer is connected with the power distribution module, and the secondary end of the first transformer is connected with the secondary end of the second transformer in series.
Further, the LED channel group includes a first LED channel and a second LED channel, the first LED channel and the second LED channel are respectively connected in series with LED lamp beads, and the power distribution module includes a second capacitor, a first diode, a second diode, a third diode, and a fourth diode;
one end of the second capacitor is connected with the secondary end of the first transformer, and the other end of the second capacitor is connected with the anode of the first diode;
the cathode of the first diode is connected with the input end of the first LED channel, and the output end of the first LED channel is grounded;
the anode of the second diode is grounded, and the cathode of the second diode is respectively connected with the other end of the first capacitor and the anode of the first diode;
the anode of the third diode is connected with the secondary end of the second transformer, the cathode of the third diode is connected with the input end of the second LED channel, and the output end of the third diode is grounded;
and the anode of the fourth diode is grounded, and the cathode of the fourth diode is respectively connected with the secondary end of the second transformer and the anode of the third diode.
Further, the LED channel group further includes a third LED channel and a fourth LED channel;
the input end of the third LED channel is connected with the output end of the first LED channel and is grounded, and the output end of the third LED channel is connected with the anode of the second diode;
the input end of the fourth LED channel is connected with the output end of the second LED channel and is grounded, and the output end of the fourth LED channel is connected with the anode of the fourth diode.
Further, the driving module comprises a driving unit, a second voltage transformation unit and a sampling unit;
the sampling unit is electrically connected with the power distribution module and the driving unit respectively, and is used for sampling the current of the LED channel and outputting a corresponding sampling signal to the driving unit;
the driving unit is electrically connected with the second voltage transformation unit and is used for outputting the driving signal to the second voltage transformation unit according to the sampling signal;
the second voltage transformation unit is respectively electrically connected with the LLC unit, and the second voltage transformation unit is used for transforming the driving signal and outputting the transformed driving signal to the LLC unit.
Furthermore, the sampling unit includes sampling resistor, sampling resistor's one end is connected respectively the LED passageway and drive unit, sampling resistor's the other end ground connection.
Further, the second transforming unit comprises a third transformer and a third capacitor;
the first pin of the third transformer is connected with the source electrode of the first field effect transistor, the drain electrode of the second field effect transistor and the primary end of the first transformer, the second pin of the third transformer is connected with the grid electrode of the first field effect transistor, the fourth pin of the third transformer is connected with the grid electrode of the second field effect transistor, the fifth pin of the third transformer is connected with the source electrode of the second field effect transistor and one end of the first capacitor, the seventh pin of the third transformer is connected with the driving unit, the ninth pin of the third transformer is connected with one end of the third capacitor, and the other end of the third capacitor is connected with the driving unit.
A display device comprises the constant current driving circuit and an LED channel group, wherein the constant current driving circuit is electrically connected with the LED channel group.
The invention has the beneficial effects that: through setting up the power distribution module and having cancelled a plurality of constant current circuits that step up among the traditional constant current drive circuit, saved one-level energy conversion, only need the LLC module with input current direct conversion input rear end's LED passageway group, switch on the LED passageway that corresponds through the power distribution module to realize the constant current control of multichannel LED passageway, thereby raise the efficiency, reduce cost has optimized circuit structure.
Drawings
Fig. 1 is a circuit schematic block diagram of a constant current driving circuit of the prior art;
fig. 2 is a schematic circuit diagram of a first transforming unit of the prior art;
fig. 3 is a schematic circuit block diagram of a constant current driving circuit according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a constant current driving circuit according to an embodiment of the present invention;
fig. 5 is another circuit schematic diagram of the constant current driving circuit according to the embodiment of the invention;
fig. 6 is a schematic circuit diagram of a first transforming unit according to the present invention.
Description of reference numerals: 100. an LLC module; 110. an LLC unit; 120. a first voltage transformation unit; 200. a drive module; 210. a sampling unit; 220. a drive unit; 230. a second voltage transformation unit; 300. a power distribution module; 400. an LED channel group; 410. a first LED channel; 420. a second LED channel; 430. a third LED channel; 440. a fourth LED channel.
Detailed Description
In order to explain the technical contents, the objects and the effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
Examples
Referring to fig. 1, in a constant current driving circuit in the prior art, an LLC circuit boosts an input current and converts the boosted input current into a fixed voltage, and then a constant current is realized by a constant current circuit, which requires two stages of energy conversion; moreover, each path of LED channel needs to be matched with a constant current circuit and corresponding electrical components, so that the constant current driving circuit in the prior art is high in cost, low in efficiency and complex in circuit structure.
Referring to fig. 3 to 6, an embodiment of the present invention is:
a constant current driving circuit is applied to driving display devices such as an LED display screen, an LED touch screen and an LED all-in-one machine to display pictures.
Referring to fig. 3, the constant current driving circuit is electrically connected to an LED channel group 400, where the LED channel group 400 includes a plurality of LED channels; the constant current drive circuit includes: LLC module 100, driver module 200, and power distribution module 300; the driving module 200 is electrically connected to the LLC module 100 and the power distribution module 300, respectively, and the driving module 200 is configured to sample the current of the LED channel through the power distribution module 300, and output a driving signal to the LLC module 100 according to a sampling result; the LLC module 100 is electrically connected to the power distribution module 300, and the LLC module 100 is configured to convert the accessed direct current into alternating current according to the driving signal and output the alternating current to the power distribution module 300; the power distribution module 300 is electrically connected to a plurality of LED channels, respectively, and the power distribution module 300 is configured to turn on or off the corresponding LED channel according to the ac current.
The working principle of the constant current driving circuit in this embodiment is as follows: after a power supply is connected with high-voltage alternating current, high-voltage direct current is output after filtering and rectifying, the LLC module 100 is connected with the high-voltage direct current, the driving module 200 samples the current of the LED channel and outputs the driving signal to the LLC module 100, the LLC module 100 converts the direct current into alternating current according to the driving signal and outputs the alternating current to the power distribution module 300, and the power distribution module 300 conducts the corresponding LED channel according to the alternating current so as to light or extinguish the corresponding LED lamp bead.
It can be understood that the constant current driving circuit in this embodiment is provided with the power distribution module 300 and cancels a plurality of boost constant current circuits in the conventional constant current system, so that one-stage energy conversion is omitted, only the LLC module 100 directly converts the input current into the alternating current and inputs the alternating current to the LED channel group 400 at the rear end, and the corresponding LED channels are turned on by the power distribution module 300 to realize multi-channel constant current control, thereby improving efficiency, reducing cost, and optimizing the circuit structure.
In this embodiment, the LLC module 100 includes an LLC unit 110 and a first transforming unit 120; the LLC unit 110 is electrically connected to the driving module 200 and the first voltage transforming unit 120, respectively, and the LLC unit 110 is configured to convert the accessed direct current into alternating current according to the driving signal and output the alternating current to the first voltage transforming unit 120; the first transforming unit 120 is electrically connected to the power distribution module 300, and the first transforming unit 120 is configured to transform the ac power and output the transformed ac power to the power distribution module 300.
It can be understood that, in this embodiment, the LLC unit 110 converts the accessed direct current into an alternating current according to the driving signal, and outputs the alternating current to the first voltage transformation unit 120, and the first voltage transformation unit 120 steps down the alternating current to a power supply voltage required by the LED lamp bead, and turns on the corresponding LED channel through the power distribution module 300.
Referring to fig. 4, in detail, the LLC unit 110 includes a first fet Q1 and a second fet Q2; the gate of the first field effect transistor Q1 is connected to the driving module 200, the drain of the first field effect transistor Q1 is connected to the direct current HV _ DC, and the source of the first field effect transistor Q1 is connected to the driving module 200 and the first transforming unit 120 respectively; the gate of the second fet Q2 is connected to the driving module 200, the drain of the second fet Q2 is connected to the source of the first fet Q1, and the source of the second fet Q2 is connected to the first transforming unit 120. In this embodiment, when the driving signal is at a high level, the first field effect transistor Q1 is turned on, and the second field effect transistor Q2 is turned off; when the driving signal is at a low level, the first fet Q1 is turned off, and the second fet Q2 is turned on.
Further, the first transforming unit 120 includes a first transformer T1, a second transformer T2, and a first capacitor C1; the primary end of the first transformer T1 is respectively connected with the source electrode of the first field effect transistor Q1 and the drain electrode of the second field effect transistor Q2, and the secondary end of the first transformer T1 is connected with the power distribution module 300; one end of the first capacitor C1 is connected to the source of the second fet Q2, and the other end of the first capacitor C1 is connected to the primary end of the second transformer T2; the primary side of the second transformer T2 is connected in series with the primary side of the first transformer T1, and the secondary side of the second transformer T2 is connected to the power distribution module 300.
In this embodiment, when the driving signal is at a high level, the first fet Q1 is turned on, the second fet Q2 is turned off, the direct current HV _ DC supplies power to the first transformer T1, the second transformer T2 and the first capacitor C1 through the first field effect, and the secondary terminals of the first transformer T1 and the second transformer T2 are output to the power distribution module 300 to light the corresponding LED channels. When the driving signal is at a low level, the first fet Q1 is turned off, the second fet Q2 is turned on, the first transformer T1, the second transformer T2, the first capacitor C1, and the second fet Q2 form a playback circuit, and output current to the power distribution module 300 through the secondary terminal of the first transformer T1 and the secondary terminal of the second transformer T2, so as to light the corresponding LED channel.
Referring to fig. 2, in order to increase power, the prior art adopts a mode of connecting the primary side of a double transformer in series and connecting the secondary side of the double transformer in parallel to increase output power. Since the secondary side outputs are in parallel, Vout＝Vs1＝Vs2. And the primary terminals are connected in series, so Vin＝Vp1+Vp2. The transformer turns ratio is the ratio of the number of turns of the primary side to the number of turns of the secondary side, and is also equivalent to the ratio of the voltage of the primary side to the voltage of the secondary side, i.e. the ratio
Figure BDA0003598500930000071
(the turns ratio of the transformer is n) and can be derived
Figure BDA0003598500930000072
Illustratively, selecting two transformers of the same design results in
Figure BDA0003598500930000073
Then
Figure BDA0003598500930000074
Namely, it is
Figure BDA0003598500930000075
Therefore, the output power is increased by connecting the primary ends of the double transformers in series and connecting the secondary ends in parallel, but more secondary end coils are needed under high-voltage output, so that the double-transformer high-voltage transformer is not suitable for selecting a thin transformer and is not beneficial to reducing the internal occupied space of circuit components.
Referring to fig. 6, in the present embodiment, the secondary terminal of the first transformer T1 is connected in series with the secondary terminal of the second transformer T2, so as to obtain Vout＝Vs1+Vs2，Vin＝Vp1+Vp2. According to the formula of the turns ratio of the transformer
Figure BDA0003598500930000076
In the knowledge that,
Figure BDA0003598500930000077
illustratively, the first transformer T1 and the second transformer T2 are transformers of the same type and specification, and then
Figure BDA0003598500930000078
In a further aspect of the present invention,
Figure BDA0003598500930000079
namely that
Figure BDA00035985009300000710
Therefore, by means of the mode that the primary ends of the two transformers are connected in series and the secondary ends of the two transformers are connected in series, compared with the connection mode in the prior art, the output voltage is increased by two times, the occupied space of circuit components is reduced while the power is improved, and the circuit structure is optimized.
Referring to fig. 4, in the present embodiment, the LED channel group 400 includes a first LED channel 410 and a second LED channel 420, the first LED channel 410 and the second LED channel 420 are respectively connected in series with LED lamp beads, and the power distribution module 300 includes a second capacitor C2, a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4; one end of the second capacitor C2 is connected to the secondary end of the first transformer T1, and the other end of the second capacitor C2 is connected to the positive electrode of the first diode D1; the cathode of the first diode D1 is connected to the input terminal of the first LED channel 410, and the output terminal of the first LED channel 410 is grounded; the anode of the second diode D2 is grounded, and the cathode of the second diode D2 is respectively connected with the other end of the first capacitor C1 and the anode of the first diode D1; the anode of the third diode D3 is connected to the secondary terminal of the second transformer T2, the cathode of the third diode D3 is connected to the input terminal of the second LED channel 420, and the output terminal of the third diode D3 is grounded; the anode of the fourth diode D4 is grounded, and the cathode of the fourth diode D4 is connected to the secondary terminal of the second transformer T2 and the anode of the third diode D3, respectively.
In this embodiment, when the driving signal is at a high level, the first fet Q1 is turned on, the second fet Q2 is turned off, the direct current HV _ DC supplies power to the first transformer T1, the second transformer T2 and the first capacitor C1 through the first field effect, the secondary terminal of the first transformer T1 and the secondary terminal of the second transformer T2 output currents to the first diode D1 and the third diode D3, and the first LED channel 410 is turned on after passing through the first diode D1 and the second LED channel 420 is turned on through the third diode D3. When the driving signal is at a low level, the first fet Q1 is turned off, the second fet Q2 is turned on, the first transformer T1, the second transformer T2, the first capacitor C1, and the second fet Q2 form a playback circuit, but there is no LED channel that can flow through in a current loop formed by the secondary terminal of the first transformer T1 and the secondary terminal of the second transformer T2, and the first LED channel 410 and the second LED channel 420 are not turned on.
Referring to fig. 5, the present embodiment further discloses another circuit structure of a constant current driving circuit, and further, the LED channel group 400 further includes a third LED channel 430 and a fourth LED channel 440; the input end of the third LED channel 430 is connected to the output end of the first LED channel 410 and ground, and the output end of the third LED channel 430 is connected to the anode of the second diode D2; an input end of the fourth LED channel 440 is connected to the output end of the second LED channel 420 and ground, and an output end of the fourth LED channel 440 is connected to the anode of the fourth diode D4.
Specifically, when the driving signal is at a high level, the first fet Q1 is turned on, the second fet Q2 is turned off, the direct current HV _ DC supplies power to the first transformer T1, the second transformer T2 and the first capacitor C1 through the first field effect, the secondary terminal of the first transformer T1 and the secondary terminal of the second transformer T2 output current to the first diode D1 and the third diode D3, the first LED channel 410 is turned on through the first diode D1, the second LED channel 420 is turned on through the third diode D3, the second diode D2 and the fourth diode D4 are turned off, and no current flows through the third LED channel 430 and the fourth LED channel 440. When the driving signal is at a low level, the first fet Q1 is turned off, the second fet Q2 is turned on, the first transformer T1, the second transformer T2, the first capacitor C1, and the second fet Q2 form a playback circuit, the secondary terminal of the first transformer T1 and the secondary terminal of the second transformer T2 output a playback current to the second diode D2 and the fourth diode D4, the third LED channel 430 is turned on after passing through the second diode D2, the fourth LED channel 440 is turned on by the fourth diode D4, the first diode D1 and the third diode D3 are turned off, and no current passes through the first LED channel 410 and the second LED channel 420.
In this embodiment, the first fet Q1 and the second fet Q2 are sequentially turned on and off by the driving signal of the driving module 200, so as to convert the high-voltage direct current HV _ DC into a square wave current with high and low levels, drive the first transformer T1, the second transformer T2 and the first capacitor C1 to realize energy conversion, and realize energy distribution of each LED channel through each diode of the power distribution module 300. Further, in this embodiment, the 2-channel constant current driving circuit and the 4-channel constant current driving circuit are combined, so that constant current control can be performed on the 6-channel and 8-channel LED televisions.
Further, the driving module 200 includes a driving unit 220, a second transforming unit 230, and a sampling unit 210; the sampling unit 210 is electrically connected to the power distribution module 300 and the driving unit 220, respectively, and the sampling unit 210 is configured to sample the current of the LED channel and output a corresponding sampling signal ISEN to the driving unit 220; the driving unit 220 is electrically connected to the second transforming unit 230, and the driving unit 220 is configured to output the driving signal to the second transforming unit 230 according to the sampling signal ISEN; the second transforming units 230 are respectively electrically connected to the LLC unit 110, and the second transforming units 230 are configured to transform the driving signal and output the transformed driving signal to the LLC unit 110. The driving unit 220 includes a driving chip, and the driving chip is configured to output a corresponding driving signal to the voltage transformation module according to the sampling signal ISEN, and control an output voltage of the first voltage transformation unit 120 by adjusting on/off frequencies and duty ratios of the first field-effect transistor Q1 and the second field-effect transistor Q2, so as to implement constant current control on the plurality of paths of LED channels. The driving chip is also connected with an external mainboard, receives the enable signal and the dimming signal output by the mainboard and is controlled by the mainboard.
Specifically, the sampling unit 210 includes a sampling resistor R1, one end of the sampling resistor R1 is connected to the LED channel and the driving unit 220, and the other end of the sampling resistor R1 is grounded.
Specifically, the second transforming unit 230 includes a third transformer T3 and a third capacitor C3; a first pin of the third transformer T3 is connected to the source of the first fet Q1, the drain of the second fet Q2, and the primary terminal of the first transformer T1, a second pin of the third transformer T3 is connected to the gate of the first fet Q1, a fourth pin of the third transformer T3 is connected to the gate of the second fet Q2, a fifth pin of the third transformer T3 is connected to the source of the second fet Q2 and one end of the first capacitor C1, a seventh pin of the third transformer T3 is connected to the driving unit 220, a ninth pin of the third transformer T3 is connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is connected to the driving unit 220. It is understood that the primary side of the third transformer T3 is connected to the driving chip, and the first fet Q1 is controlled by the upper coil of the secondary side of the third transformer T3, and the second fet Q2 is controlled by the lower coil of the secondary side of the third transformer T3 according to the driving signal output by the driving chip.
The embodiment also discloses a display device, which comprises any one of the constant current driving circuit and the LED channel group, wherein the constant current driving circuit is electrically connected with the LED channel to drive LED lamp beads on the LED channel group to be lightened, so that the display device performs picture display.
In summary, the constant current driving circuit and the display device provided by the invention omit a plurality of boosting constant current circuits in the conventional constant current driving circuit by arranging the power distribution module, save primary energy conversion, only need the LLC module to directly convert the input current into the alternating current, input the alternating current into the LED channel group at the rear end, and conduct the corresponding LED channels through the power distribution module to realize the constant current control of the multiple LED channels, thereby improving the efficiency, reducing the cost, and optimizing the circuit structure. In addition, the double transformers are adopted, the primary ends of the two transformers are connected in series, and the secondary ends of the two transformers are connected in series, so that the output voltage is increased to be twice under the condition of the same turn ratio, and the occupied space of components in the constant current driving circuit is favorably optimized.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent modifications made by the contents of the present specification and the drawings, or applied to the related technical fields directly or indirectly, are included in the scope of the present invention.

Claims (10)

1. A constant current driving circuit is applied to driving a plurality of LED channels in an LED channel group, and is characterized by comprising: the device comprises an LLC module, a drive module and a power distribution module;
the driving module is electrically connected with the LLC module and the power distribution module respectively, and is used for sampling the current of the LED channel through the power distribution module and outputting a driving signal to the LLC module according to a sampling result;
the LLC module is electrically connected with the power distribution module and is used for converting the accessed direct current into alternating current according to the driving signal and outputting the alternating current to the power distribution module;
the power distribution module is electrically connected with the plurality of LED channels respectively, and is used for conducting or disconnecting the corresponding LED channels according to the alternating current.
2. The constant current driving circuit according to claim 1, wherein the LLC module includes an LLC unit and a first voltage transformation unit;
the LLC unit is electrically connected with the drive module and the first transformation unit respectively, and the LLC unit is used for converting the accessed direct current into alternating current according to the drive signal and outputting the alternating current to the first transformation unit;
the first voltage transformation unit is electrically connected with the power distribution module and is used for transforming the alternating current and outputting the alternating current to the power distribution module.
3. The constant current driving circuit according to claim 2, wherein the LLC unit comprises a first fet and a second fet;
the grid electrode of the first field effect transistor is connected with the driving module, the drain electrode of the first field effect transistor is connected with the direct current, and the source electrode of the first field effect transistor is respectively connected with the driving module and the first voltage transformation unit;
the grid electrode of the second field effect transistor is connected with the driving module, the drain electrode of the second field effect transistor is connected with the source electrode of the first field effect transistor, and the source electrode of the second field effect transistor is connected with the first voltage transformation unit.
4. The constant current drive circuit according to claim 3, wherein the first transforming unit includes a first transformer, a second transformer, and a first capacitor;
the primary end of the first transformer is respectively connected with the source electrode of the first field effect transistor and the drain electrode of the second field effect transistor, and the secondary end of the first transformer is connected with the power distribution module; one end of the first capacitor is connected with the source electrode of the second field effect transistor, and the other end of the first capacitor is connected with the primary end of the second transformer; the primary end of the second transformer is connected with the primary end of the first transformer in series, the secondary end of the second transformer is connected with the power distribution module, and the secondary end of the first transformer is connected with the secondary end of the second transformer in series.
5. The constant current driving circuit according to claim 4, wherein the LED channel group comprises a first LED channel and a second LED channel, the first LED channel and the second LED channel are respectively connected with LED beads in series, and the power distribution module comprises a second capacitor, a first diode, a second diode, a third diode and a fourth diode;
one end of the second capacitor is connected with the secondary end of the first transformer, and the other end of the second capacitor is connected with the anode of the first diode;
the cathode of the first diode is connected with the input end of the first LED channel, and the output end of the first LED channel is grounded;
the anode of the second diode is grounded, and the cathode of the second diode is respectively connected with the other end of the first capacitor and the anode of the first diode;
the anode of the third diode is connected with the secondary end of the second transformer, the cathode of the third diode is connected with the input end of the second LED channel, and the output end of the third diode is grounded;
and the anode of the fourth diode is grounded, and the cathode of the fourth diode is respectively connected with the secondary end of the second transformer and the anode of the third diode.
6. The constant current driving circuit according to claim 5, wherein the LED channel group further comprises a third LED channel and a fourth LED channel;
the input end of the third LED channel is connected with the output end of the first LED channel and is grounded, and the output end of the third LED channel is connected with the anode of the second diode;
the input end of the fourth LED channel is connected with the output end of the second LED channel and is grounded, and the output end of the fourth LED channel is connected with the anode of the fourth diode.
7. The constant current driving circuit according to claim 4, wherein the driving module comprises a driving unit, a second transforming unit and a sampling unit;
the sampling unit is electrically connected with the power distribution module and the driving unit respectively, and is used for sampling the current of the LED channel and outputting a corresponding sampling signal to the driving unit;
the driving unit is electrically connected with the second voltage transformation unit and is used for outputting the driving signal to the second voltage transformation unit according to the sampling signal;
the second voltage transformation unit is respectively electrically connected with the LLC unit, and the second voltage transformation unit is used for transforming the driving signal and outputting the transformed driving signal to the LLC unit.
8. The constant current driving circuit according to claim 7, wherein the sampling unit comprises a sampling resistor, one end of the sampling resistor is connected to the LED channel and the driving unit, and the other end of the sampling resistor is grounded.
9. The constant current drive circuit according to claim 7, wherein the second transforming unit includes a third transformer and a third capacitor;
the first pin of the third transformer is connected with the source electrode of the first field effect transistor, the drain electrode of the second field effect transistor and the primary end of the first transformer, the second pin of the third transformer is connected with the grid electrode of the first field effect transistor, the fourth pin of the third transformer is connected with the grid electrode of the second field effect transistor, the fifth pin of the third transformer is connected with the source electrode of the second field effect transistor and one end of the first capacitor, the seventh pin of the third transformer is connected with the driving unit, the ninth pin of the third transformer is connected with one end of the third capacitor, and the other end of the third capacitor is connected with the driving unit.
10. A display device comprising the constant current drive circuit according to any one of claims 1 to 9 and an LED channel group, the constant current drive circuit being electrically connected to the LED channel group.
CN202210394901.8A 2022-04-15 2022-04-15 Constant current driving circuit and display device Active CN114783384B (en)

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CN104254172A (en) * 2013-06-28 2014-12-31 三星电机株式会社 Light emitting diode power supply apparatus
CN104935843A (en) * 2015-06-16 2015-09-23 康佳集团股份有限公司 LED (Light-Emitting Diode) television two-in-one power supply circuit and LED television
CN110769173A (en) * 2019-10-18 2020-02-07 深圳创维－Rgb电子有限公司 Television power supply system and television
CN213073182U (en) * 2020-09-28 2021-04-27 深圳创维－Rgb电子有限公司 LED control circuit and display device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130007485A1 (en) * 2011-06-30 2013-01-03 Lg Innotek Co., Ltd. Standby power reducing apparatus
CN104254172A (en) * 2013-06-28 2014-12-31 三星电机株式会社 Light emitting diode power supply apparatus
CN104935843A (en) * 2015-06-16 2015-09-23 康佳集团股份有限公司 LED (Light-Emitting Diode) television two-in-one power supply circuit and LED television
CN110769173A (en) * 2019-10-18 2020-02-07 深圳创维－Rgb电子有限公司 Television power supply system and television
CN213073182U (en) * 2020-09-28 2021-04-27 深圳创维－Rgb电子有限公司 LED control circuit and display device

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