CN116453471A - Channel current control device and method for mini LED backlight source - Google Patents

Abstract

The application provides channel current control equipment and a channel current control method for a mini LED backlight source. The channel current control device includes: the control unit is used for providing corresponding reference voltage signals, pulse width modulation signals and digital current setting signals for each mini LED channel in the mini LED backlight source; and for each mini LED channel, the channel current control device comprises: the LED light source comprises a constant current control unit, a high-voltage transistor and a low-voltage transistor, wherein the high-voltage transistor is connected in series between a plurality of LEDs in a mini LED channel and the low-voltage transistor, a grid electrode of the high-voltage transistor receives a pulse width modulation signal, an input end of the constant current control unit receives a reference voltage signal, the pulse width modulation signal and a digital current setting signal, and an output end of the constant current control unit is connected with the low-voltage transistor so as to realize current regulation and constant current control on the mini LED channel.

Description

Channel current control device and method for mini LED backlight

technical field

The present application generally relates to the field of display devices, and more specifically relates to channel current control devices and methods for mini LED backlight sources.

Background technique

Among the backlights applied to display devices, the mini LED backlight is a new type of backlight. Compared with display devices using traditional backlights, display devices using mini LED backlights perform better in terms of dynamic contrast and brightness, and have the advantages of thinness, high image quality, low power consumption, and energy saving. Improved display device performance. The mini LED backlight can realize regional dimming, so it can dynamically adjust the overall picture displayed on the screen of the display device through fine partitioning, so as to achieve high dynamic contrast display.

FIG. 1 is a schematic diagram of a constant current control circuit of a conventional backlight source. As shown in Figure 1, Vout is the output voltage of the previous stage DC/DC or AC/DC. The control unit generates the reference voltage Vref signal and pulse width modulation PWM signal. The Vref signal generates a channel through the operational amplifier OP, the high-voltage transistor HM and the resistor R. The constant current, the PWM signal is the dimming signal. In PWM dimming, the traditional backlight adopts a unified dimming method, that is, the PWM1-PWMx signals of each channel are the same signal, and the LED lights of all channels are at the same brightness during adjustment. However, for a display device using a mini LED backlight, considering the requirement for local dimming, the current of each channel is different during dimming, so the PWM dimming signal obtained by each channel is also different. With the increase of the dimming area, the current matching problem between multiple LED channels of the mini LED backlight and the communication problem between each LED channel and the control unit have become problems that need to be solved urgently.

Contents of the invention

In view of the above problems, the present application provides a channel current control device and method for mini LED backlight sources.

According to one aspect of the present application, there is provided a channel current control device for mini LED backlight, including: a control unit, used to provide each mini LED channel in the mini LED backlight with a corresponding reference voltage signal, pulse A width modulation signal and a digital current setting signal; and for each mini LED channel, the channel current control device includes: a constant current control unit, a high-voltage transistor and a low-voltage transistor, wherein the high-voltage transistor is connected in series to a plurality of LEDs in the mini LED channel and the low-voltage transistor, and the gate of the high-voltage transistor receives the pulse width modulation signal, the input terminal of the constant current control unit receives the reference voltage signal, the pulse width modulation signal and the digital current setting signal, and the output terminal of the constant current control unit is connected with the low voltage Transistor connections for current regulation and constant current control of mini LED channels.

According to another aspect of the present application, there is provided a channel current control method for mini LED backlight, which is applied to the channel current control device as described above, and the method includes: sending each of the mini LED backlight through the control unit Each mini LED channel provides the corresponding reference voltage signal, pulse width modulation signal and digital current setting signal; use the high voltage transistor to control the dimming of each mini LED channel based on the pulse width modulation signal, use the constant current control unit and the low voltage transistor based on the reference The voltage signal, pulse width modulation signal and digital current setting signal realize the current regulation and constant current control of the miniLED channel.

According to yet another aspect of the present application, a display device is provided, including a mini LED backlight source and the above-mentioned channel current control device for the mini LED backlight source.

Description of drawings

The present application can be better understood from the following description of specific embodiments of the application in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a schematic diagram of a constant current control circuit of a conventional backlight source;

FIG. 2 shows a schematic diagram of a circuit of a channel current control device for a mini LED backlight according to an embodiment of the present application;

3 shows a schematic diagram of a current control circuit for each channel in a channel current control device for a mini LED backlight according to an embodiment of the present application;

FIG. 4 shows a schematic diagram of a circuit of each array unit in the decoder circuit shown in FIG. 3 according to an embodiment of the present application;

5 shows a schematic diagram of a current mirror control unit array according to an embodiment of the application; and

Fig. 6 shows a schematic diagram of a current mirror control unit array according to another embodiment of the present application.

Detailed ways

Features and exemplary embodiments of various aspects of the present application will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the application. It will be apparent, however, to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application. The application is in no way limited to any specific configuration presented below, but covers any modifications, substitutions and improvements of elements, components and algorithms without departing from the spirit of the application. In the drawings and the following description, well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the application.

This application proposes a channel current control device for mini LED backlight, which sets the maximum brightness current of each channel through the reference voltage signal, and realizes the dimming of each channel through the control of the high-voltage transistor by the PWM signal, and The channel current of each channel is adjusted by a digital current setting (ISET) signal. In addition, the entire display screen can be divided into N areas (that is, N channels), and the communication between the N areas and the control unit can be in a serial time-division multiplexing manner. Therefore, the channel current control device according to the present application can fully meet the demand for local dimming of mini LED backlight sources.

FIG. 2 shows a schematic diagram of a circuit of a channel current control device for a mini LED backlight according to an embodiment of the present application. As shown in Figure 2, the mini LED backlight includes multiple mini LED channels, and the channel current control device includes a control unit for providing corresponding control signals to each mini LED channel, such as reference voltage Vref signal, pulse width modulation PWM signal and digital ISET signal.

For each mini LED channel, the channel current control device includes: a constant current control unit, a high voltage transistor HM and a low voltage transistor LM. As shown in the figure, the high-voltage transistor is connected in series between multiple LEDs in the mini LED channel and the low-voltage transistor, and the gate of the high-voltage transistor is used to receive the PWM signal to dim the mini LED channel based on the PWM signal. ; The input terminal of the constant current control unit is used to receive the Vref signal, PWM signal and ISET signal, and its output terminal is connected to the low-voltage transistor to realize current regulation and constant current control of the mini LED channel together with the low-voltage transistor.

Compared with the constant current control circuit of the traditional backlight shown in FIG. 1, in the channel current control device according to the embodiment of the present application, the high-voltage transistor connected to each channel in FIG. 1 is replaced by a high-voltage transistor and a low-voltage transistor series. The high-voltage transistor is responsible for PWM dimming and high-voltage isolation of the channel, and the low-voltage transistor is used together with the constant current control unit to realize constant current control. In this way, the high-voltage transistor can be fully turned on when in use, and compared with the traditional architecture, a smaller high-voltage transistor can be used when the current on the channel is the same, thereby saving the chip area of the channel.

In addition, in the constant current control circuit of the traditional backlight source shown in FIG. 1 , the constant current control of each channel is realized through the operational amplifier OP, the high voltage transistor HM and the resistor R. The difference is that in the channel current control device according to the embodiment of the present application, a current mirror is used to replace the resistor in the constant current control circuit of the traditional backlight source, and the current current current of the channel is affected by the digital ISET signal received by the channel. For control, the number of transistors in the current mirror circuit is controlled through a simple decoder array, so as to control the channel current according to the number of current mirror units. In this way, the digital-to-analog conversion unit for digital-to-analog conversion of the digital ISET signal can be omitted, and precise channel current control can be realized at the same time. The principle of constant current control according to the embodiment of the present application will be explained below with reference to FIG. 3 .

Fig. 3 shows a schematic diagram of a current control circuit for each channel in the channel current control device for mini LED backlight according to an embodiment of the present application. As shown in Figure 3, the current control circuit of each channel includes a constant current control unit, a high voltage transistor and a low voltage transistor. The internal circuit structure of the constant current control unit is shown in the two dashed boxes. Specifically, the constant current control unit includes a current mirror circuit and a decoder circuit. The current mirror circuit includes an input-side transistor M0 and N output-side transistors M1 to M _N connected in parallel. The decoder circuit is used to generate The N current mirror control signals are respectively used to control the turn-on or turn-off of the corresponding output-side transistors among the N output-side transistors, so as to control the number of turn-on current mirror units.

The digital ISET signal may include n-bit binary codes, so as to control 2 ⁿ current mirrors to be turned on or off, that is, N is equal to 2 to the nth power. As shown in FIG. 3 , the ISET signal is, for example, ISET<10:0>. Correspondingly, this signal can be used to control the turn-on or turn-off of 2048 current mirror units. In this example, n=11 and N=2048. How to generate N current mirror control signals based on the digital ISET signal through the decoder circuit will be described in detail below with reference to FIGS. 4 to 6 .

In addition, as shown in Figure 3, the Vref signal is connected to the gate of the input-side transistor M0 through the first operational amplifier OP1, which is used to set the maximum brightness current of the mini LED channel, and the gate of the low-voltage transistor is connected through the second operational amplifier OP2 to the drain of the input-side transistor M0, and the source of the low-voltage transistor is connected to the drains of N output-side transistors in parallel.

It should be noted that, according to some embodiments of the present application, the low-voltage transistor may include a plurality of low-voltage transistors connected in parallel, and the constant current control unit may also include a logic control circuit for a predetermined number of high voltage transistors based on the PWM signal and the digital ISET signal. A plurality of low-voltage transistor control signals are generated bit by bit, so as to respectively control the turn-on or turn-off of corresponding low-voltage transistors in the plurality of low-voltage transistors. For example, FIG. 3 shows three low voltage transistors and corresponding three low voltage transistor control signals a, b, c. Actually, each low voltage transistor may also be a parallel connection of a predetermined number of low voltage transistors. For example, m=1 shown in FIG. 3 indicates that the first low-voltage transistor may include one low-voltage transistor, m=3 indicates that the second low-voltage transistor may include three low-voltage transistors connected in parallel, and m=5 indicates that the third low-voltage transistor Three low voltage transistors connected in parallel may be included. That is, each channel shown in FIG. 3 may include 9 low-voltage transistors connected in parallel.

As shown in FIG. 3 , for example, the logic control circuit can receive the highest three bits of the digital ISET signal to generate low-voltage transistor control signals a, b, and c for controlling the number of turned-on low-voltage transistors. When adjusting the channel current, the number of low-voltage transistors turned on is determined according to the magnitude of the current, and the gate voltage of the low-voltage transistor can be kept fluctuating within a small range during the current adjustment process, thereby reducing the resistance of the channel. Jamming performance has been somewhat improved.

The specific structure of the decoder circuit according to the embodiment of the present application and how to generate N current mirror control signals based on the digital ISET signal will be described below with reference to FIGS. 4 to 6 .

In order to control N current mirror units, the decoder circuit may include N decoder subunits for generating N current mirror control signals to respectively control the turn-on or turn-off of corresponding output-side transistors among the N output-side transistors .

Take the 11-bit ISET<10:0> signal as an example below. If you want to convert the 11-bit ISET signal into a corresponding number of current mirror control signals, one solution can be to use 11-bit binary codes to control 2 ¹¹ transistors. Only 11 corresponding control signals are needed to turn on or off, but this scheme is greatly affected by the matching accuracy of the current mirror, especially when a carry occurs in a high bit, the current mirror unit that is turned on will change a lot. For example, when the control code word changes from 1023 (the hexadecimal number corresponds to 0x3ff) to 1024 (the hexadecimal number corresponds to 0x400), the current mirror unit that was turned on before will be turned off, and the current mirror unit that was turned off before will turn on Generally, due to the influence of the matching accuracy of the current mirror, the total current may change greatly, thus affecting the linearity of current regulation. Therefore, this solution has high requirements on the matching accuracy of the current mirror.

Another solution is to convert the control signal into a thermometer code. At this time, when adjacent code words change, only the conduction state of one current mirror changes, which can improve the linearity of current regulation. However, in the case of generating 2 ¹¹ current mirror control signals based on the 11-bit ISET signal, the number of required control signals is excessive.

According to an embodiment of the present application, a matrix array control scheme is proposed. Specifically, the decoder circuit may include N decoder subunits, and these decoder subunits may be arranged as a matrix array of M rows×K columns, wherein each array unit in the matrix array may include one or Multiple decoder subunits. Here, M times K may be equal to or smaller than N. When M times K is equal to N, each array unit in the matrix array includes one decoder subunit, and when M times K is less than N, each array unit in the matrix array may include multiple decoder subunits .

FIG. 4 shows a schematic diagram of a circuit of each array unit in the decoder circuit shown in FIG. 3 according to an embodiment of the present application. The input control signals of the array unit are A, B, and C respectively, and the output signal is D, wherein the input control signals A, B, and C are thermometer code signals converted based on the ISET signal, and the output signal D is generated by the array unit The current mirror control signal. Therefore, the decoder circuit further includes a code conversion unit (not shown in the figure), which is used to convert the ISET signal into input control signals A, B, and C of each array unit. As shown in Figure 4, each array unit is controlled by A, B, and C signals, and its control logic is: C||(A&B), that is, when the C signal exists, all the current mirror units corresponding to the corresponding row of array units are turned on When the C signal is not present, the A&B array controls the corresponding current mirror unit to be turned on or off.

According to an embodiment of the present application, when M multiplied by K is equal to N, each array unit in the matrix array includes a decoder subunit, and the code conversion unit can convert the ISET signal into the first row including the M-bit thermometer code A control signal C, a second row control signal A including an M-bit thermometer code, and a column control signal B including a K-bit thermometer code. Each bit in the first row control signal C and the second row control signal A is used to control a corresponding row of decoder subunits among the N decoder subunits, and each bit in the column control signal B is used to control A corresponding column of decoder subunits among the N decoder subunits, and the priority of the first row control signal is higher than that of the second row control signal.

More specifically, the code conversion unit may be configured to generate the first row control signal C and the second row control signal A based on the highest m bits of the ISET signal, and generate the column control signal based on the remaining (n-m) bits of the ISET signal. For example, the value represented by the M-bit thermometer code of the control signal C in the first row is equal to the value represented by the highest m-bit binary code of the ISET signal, and the value represented by the M-bit thermometer code of the control signal A in the second row is equal to the value represented by the ISET signal Add 1 to the value represented by the binary code of the highest m bits, and the value represented by the K-bit thermometer code of the column control signal is equal to the value represented by the binary code of the remaining (n-m) bits of the ISET signal.

FIG. 5 shows a schematic diagram of a current mirror control unit array according to an embodiment of the present application. In this embodiment, assuming that the ISET signal is a 9-bit binary code signal ISET<8:0>, the current mirror control unit array can be designed as a 16×32 matrix array. The current mirror control unit here actually corresponds to the decoder subunit in the decoder circuit. That is to say, the decoder circuit can be arranged to include decoder subunits in 16 rows and 32 columns (ie, a total of 512 decoder subunits), and each matrix array unit includes a decoder subunit. As shown in Figure 5, A1 to A32 may correspond to the first row of decoder subunits, P1 to P32 may correspond to the 16th row of decoder subunits, A1 to P1 may correspond to the first column of decoder subunits, A32 to P32 may correspond to the 32nd column decoder subunit.

In this embodiment, the highest 4 bits ISET<8:5> of the ISET signal are converted to the first row signal C<15:0> using thermometer code, and the lowest 5 bits ISET<4:0> are converted to use The column signal B<31:0> of the thermometer code, and ISET<8:5>+1 is converted into the second row signal A<15:0> of the thermometer code, that is, A controls one more row than C. When the control signal ISET<8:0> comes, the signal C of the first line will control all the units of the previous ISET<8:5> line to be turned on, and the line signal A of the line ISET<8:5>+1 is high, At this time, the row will control the conduction of ISET<4:0> units according to the column signal B<31:0>, and realize the total number of conduction units: ISET<8:5>*32+ISET<4:0>=ISET< 8:0>, which is the same as the number of control codewords. In the above equation, ISET<8:5> represents the number of current mirror units that are turned on based on the upper 4-bit control signal, and ISET<4:0> represents the current mirror that is turned on based on the lower 5-bit control signal The number of units, ISET<8:0> indicates the number of current mirror units that are turned on based on the 9-bit control signal.

According to this embodiment, since the control signals A, B, and C of the rows and columns all use thermometer codes, so taking the code word +1 as an example, no matter whether there is a carry in the code word, only a new conductive current mirror unit will be added each time , while the original conducting current mirror unit will not change. This not only improves the linearity of current regulation, but also reduces the number of control signals. For example, according to the arrangement of the current mirror control unit array shown in Figure 5, in order to control the on or off of 512 current mirror units based on the 9-bit ISET signal, only 16+16+32=64 control signals are required , instead of 512 control signals.

In addition, for ISET signals with more digits, the array of current mirror control units can be arranged in a manner similar to that shown in FIG. 5 . For example, when the ISET signal is an 11-bit binary code word ISET<10:0>, 2048 current mirror units can be controlled to be turned on or off based on the ISET signal. Using an array arrangement similar to that shown in FIG. 5 , the current mirror control units can be arranged as a matrix array with 32 rows and 64 columns. With this array arrangement, if the control signals A, B, and C of the rows and columns all use thermometer codes, 32+32+64=128 control signals are required, which greatly reduces the control signals compared with 2048 control signals quantity.

However, in order to further reduce the number of control signals, it may be considered to convert some of the highest bits of the ISET signal into row and column control signals, and convert the remaining few low bits to control the decoder subunits in the array unit.

With this array arrangement, when the ISET signal is an n-bit binary code, in order to control N=2 ⁿ current mirror units, the N decoder subunits in the decoder circuit can be arranged as M rows×K A matrix array of columns, wherein each array unit in the matrix array includes a plurality of decoder subunits. For example, M multiplied by K may be equal to 2 to the pth power (p is smaller than n), and each array unit in the matrix array includes 2 to the (np) power of decoder subunits.

In this case, similar to the code word conversion method described before, the code conversion unit in the decoder circuit can convert the highest p bits of the ISET signal into the first line control signal including the M-bit thermometer code, including the M-bit thermometer code. The second row control signal of the code and the column control signal including the K-bit thermometer code, and convert the remaining (n-p) bits of the ISET signal into an array unit control signal including the 2(n-p)th position thermometer code. Each bit in the first row control signal and the second row control signal is used to control the decoder subunit corresponding to the corresponding row of array units in the matrix array, and each bit in the column control signal is used to control the decoder subunits in the matrix array respectively. Corresponding to the decoder subunit corresponding to a column of array units, the priority of the first row control signal is higher than that of the second row control signal, and each bit of the array unit control signal is used to control each array unit in the matrix array. Corresponding decoder subunit.

Specifically, the ISET signal formed by the highest p bits of the ISET signal may be referred to as a high-order ISET signal, and the code conversion unit may be configured to generate the first row control signal and the second row control signal based on the highest m bits of the high-order ISET signal, And a column control signal is generated based on the remaining (p-m) bits of the upper ISET signal. The value represented by the M-bit thermometer code of the control signal in the first row is equal to the value represented by the highest m-bit binary code of the high-order ISET signal, and the value represented by the M-bit thermometer code of the control signal in the second row is equal to the highest m of the high-order ISET signal The value represented by the binary code of the bit is added by 1; the value represented by the K-bit thermometer code of the column control signal is equal to the value represented by the binary code of the remaining (p-m) bits of the high-order ISET signal.

Fig. 6 shows a schematic diagram of a current mirror control unit array according to another embodiment of the present application. As shown in Figure 6, for the 11-bit ISET signal ISET<10:0>, on the basis of converting the highest 9-bit signal ISET<11:2> of the signal into row and column control, the lower 2-bit signal ISET<1: 0> is converted into a thermometer code signal that controls a finer current mirror unit, and the current size of each current mirror unit controlled by it is 1/4 of the original current mirror unit, and these currents are controlled according to the low 2-bit signal of the ISET signal turn on or off of the mirror unit. Using the array arrangement of the current mirror control units shown in Figure 6, in order to realize the control of 2048 current mirror units, a total of 16+16+32+4=68 control signals are needed, compared to the method similar to that shown in Figure 5 In terms of the current mirror control unit array arrangement, the number of control signals can be further reduced.

In addition, according to the embodiment of the present application, a channel current control method for a mini LED backlight source is also provided. The method is applied to the channel current control device as described above, and includes: providing a corresponding reference voltage signal, a pulse width modulation signal and a digital current setting signal to each mini LED channel in the mini LED backlight through the control unit; The transistor controls the dimming of each mini LED channel based on the pulse width modulation signal, and uses the constant current control unit and the low voltage transistor to realize the current regulation and constant current of the mini LED channel based on the reference voltage signal, pulse width modulation signal and digital current setting signal control.

The channel current control device and method based on the embodiments of the present application can fully meet the demand for local dimming of mini LED backlight sources.

"One embodiment", "another embodiment" and "embodiment" are mentioned above, but it should be understood that the features mentioned in each embodiment are not necessarily only applicable to this embodiment, but may be used in other embodiments. Features in one embodiment can be applied to, or included in, another embodiment.

Ordinal numerals such as "first", "second"... are mentioned above. However, it should be understood that these expressions are only for the convenience of description and reference, and there is no sequential relationship between the defined objects.

Additionally, various operations or steps have been described as multiple discrete operations in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as to imply that these operations or steps are necessarily order dependent. In particular, these operations or steps need not be performed in the order presented.

The present application may be implemented in other specific forms without departing from its spirit and essential characteristics. For example, features described in certain embodiments may be modified without departing from the basic spirit of the application. Accordingly, the present embodiments are to be considered in all respects as illustrative rather than restrictive, the scope of the application being defined by the appended claims rather than the above description, and within the meaning and equivalents of the claims All changes in scope are thereby embraced within the scope of this application.

Claims (20)

1. A channel current control device for mini LED backlight, comprising: a control unit for providing a corresponding reference voltage signal, a pulse width modulation signal and a digital current setting signal to each mini LED channel in the mini LED backlight; and For each mini LED channel, the channel current control device includes: a constant current control unit, a high-voltage transistor and a low-voltage transistor, Wherein, the high-voltage transistor is connected in series between a plurality of LEDs in the mini LED channel and the low-voltage transistor, and the gate of the high-voltage transistor is used to receive the pulse width modulation signal, The input terminal of the constant current control unit is used to receive the reference voltage signal, the pulse width modulation signal and the digital current setting signal, and the output terminal of the constant current control unit is connected to the low voltage transistor to Realize current regulation and constant current control on the mini LED channel. 2. The channel current control device according to claim 1, wherein the constant current control unit comprises a current mirror circuit and a decoder circuit, The current mirror circuit includes an input-side transistor and N output-side transistors connected in parallel, The decoder circuit is configured to generate N current mirror control signals based on the digital current setting signal, which are respectively used to control the turn-on or turn-off of corresponding output-side transistors among the N output-side transistors, Wherein, the digital current setting signal includes an n-bit binary code, and the N is equal to 2 to the nth power. 3. The channel current control device according to claim 2, wherein the reference voltage signal is connected to the gate of the input side transistor through a first operational amplifier for setting the maximum brightness current of the mini LED channel . 4. The channel current control device according to claim 2, wherein the gate of the low-voltage transistor is connected to the drain of the input-side transistor through a second operational amplifier, and the source of the low-voltage transistor is connected to the The drains of the N output side transistors. 5. The channel current control device according to any one of claims 1 to 4, wherein the low voltage transistor comprises a plurality of low voltage transistors connected in parallel, and the constant current control unit further comprises: A logic control circuit, configured to generate a plurality of low-voltage transistor control signals based on the pulse width modulation signal and a predetermined number of high bits of the digital current setting signal, respectively used to control corresponding low-voltage transistors among the plurality of low-voltage transistors Transistors are turned on or off. 6. The channel current control device according to claim 2, wherein the decoder circuit comprises N decoder subunits for generating the N current mirror control signals; and The N decoder subunits are arranged as a matrix array of M rows×K columns, wherein each array unit in the matrix array includes one or more decoder subunits. 7. The channel current control device according to claim 6, wherein M multiplied by K is equal to N, and each array unit in the matrix array includes a decoder subunit. 8. The channel current control device according to claim 7, wherein the decoder circuit further comprises a code conversion unit for converting the digital current setting signal into a first row control signal comprising an M-bit thermometer code, A second row control signal including an M-bit thermometer code and a column control signal including a K-bit thermometer code; Each bit of the first row control signal and the second row control signal is used to control a corresponding row of decoder subunits among the N decoder subunits; Each bit in the column control signal is used to control a corresponding column of decoder subunits among the N decoder subunits; and The priority of the first row control signal is higher than that of the second row control signal. 9. The channel current control device according to claim 8, wherein the code conversion unit is configured to generate the first row control signal and the second row control signal based on the highest m bits of the digital current setting signal signal, and generate the column control signal based on the remaining (n-m) bits of the digital current setting signal. 10. The channel current control device according to claim 9, wherein the value represented by the M-bit thermometer code of the first row of control signals is equal to the value represented by the highest m-bit binary code of the digital current setting signal; The value represented by the M-bit thermometer code of the second row control signal is equal to the value represented by the highest m-bit binary code of the digital current setting signal plus 1; The value represented by the K-bit thermometer code of the column control signal is equal to the value represented by the binary code of the remaining (n-m) bits of the digital current setting signal. 11. The channel current control device according to claim 6, wherein, M multiplied by K is equal to the p power of 2 and p is less than n, and each array unit in the matrix array comprises 2 (n-p) power decoder subunit. 12. The channel current control device according to claim 11, wherein the decoder circuit further comprises a code conversion unit for converting the highest p bits of the digital current setting signal into the first p bits comprising an M-bit thermometer code. a row control signal, a second row control signal comprising an M-bit thermometer code, and a column control signal comprising a K-bit thermometer code, and converting the remaining (n-p) bits of the digital current setting signal into a (n-p) order comprising 2 The array unit control signal of the thermometer code; Each bit of the first row control signal and the second row control signal is used to control a corresponding row of array units in the matrix array; Each bit in the column control signal is used to control a corresponding column of array units in the matrix array; the first row control signal has a higher priority than the second row control signal; and Each bit of the array unit control signal is respectively used to control a corresponding decoder subunit in each array unit in the matrix array. 13. The channel current control device according to claim 12, wherein the digital current setting signal formed by the highest p bits of the digital current setting signal is called a high-order digital current setting signal, The code conversion unit is configured to generate the first row control signal and the second row control signal based on the highest m bits of the high-order digital current setting signal, and based on the remaining (p-m) of the high-order digital current setting signal ) bit generates the column control signal. 14. The channel current control device according to claim 13, wherein the value represented by the M-bit thermometer code of the first line control signal is equal to the value represented by the highest m-bit binary code of the high-order digital current setting signal ; The value represented by the M-bit thermometer code of the second line control signal is equal to the value represented by the highest m-bit binary code of the high-order digital current setting signal plus 1; The value represented by the K-bit thermometer code of the column control signal is equal to the value represented by the binary code of the remaining (p-m) bits of the high-order digital current setting signal. 15. The channel current control device according to any one of claims 8 to 14, wherein each array unit is configured to implement the following control logic to generate a corresponding current mirror control signal: C||(A&B), where C represents the first row control signal, A represents the second row control signal, and B represents the column control signal. 16. A channel current control method for a mini LED backlight, applied to the channel current control device according to any one of claims 1 to 15, the method comprising: providing a corresponding reference voltage signal, a pulse width modulation signal and a digital current setting signal to each mini LED channel in the mini LED backlight through the control unit; Using the high-voltage transistor to perform dimming control on each mini LED channel based on the pulse width modulation signal, Using the constant current control unit and the low voltage transistor to realize current regulation and constant current control of the mini LED channel based on the reference voltage signal, the pulse width modulation signal and the digital current setting signal. 17. The channel current control method according to claim 16, wherein the constant current control unit comprises a current mirror circuit and a decoder circuit, and the current mirror circuit comprises an input side transistor and N output side transistors connected in parallel , the method also includes: Using the decoder circuit to generate N current mirror control signals based on the digital current setting signal, which are respectively used to control the turn-on or turn-off of corresponding output-side transistors among the N output-side transistors, Wherein, the digital current setting signal includes an n-bit binary code, and the N is equal to 2 to the nth power. 18. The channel current control method according to claim 17, wherein the reference voltage signal is connected to the gate of the input-side transistor through a first operational amplifier, and the method further comprises: setting Set the maximum brightness current of the corresponding mini LED channel. 19. The channel current control method according to claim 16, wherein the low-voltage transistor comprises a plurality of low-voltage transistors connected in parallel, and the method further comprises: a predetermined value based on the pulse width modulation signal and the digital current setting signal The number of high bits is used to generate a plurality of low-voltage transistor control signals, which are respectively used to control the turn-on or turn-off of corresponding low-voltage transistors in the plurality of low-voltage transistors. 20. A display device, comprising a mini LED backlight and the channel current control device for the mini LED backlight according to any one of claims 1 to 15.