Channel current control apparatus and method for mini LED backlight

Abstract

The application provides a channel current control device and method for a mini LED backlight. The channel current control device comprises: a control unit configured to provide 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 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 the mini LED channel and the low-voltage transistor, the gate of the high-voltage transistor receives the pulse width modulation signal, the input 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 of the constant current control unit is connected with the low-voltage transistor to realize current regulation and constant current control of the mini LED channel.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of display devices, and more particularly to a channel current control device and method for a mini LED backlight. BACKGROUND

[0002] Among the backlight applied to display devices, the mini LED backlight is a new type of backlight. Compared with the display device using the traditional backlight, the display device using the mini LED backlight has better performance in dynamic contrast and brightness, and has the advantages of thinness, high quality, low power consumption and energy saving, which greatly improves the performance of the display device. The mini LED backlight can realize regional dimming, so that the overall picture displayed on the screen of the display device can be dynamically dimmed by fine partitioning, thereby realizing high dynamic contrast display.

[0003] Figure 1 is a schematic diagram of a constant current control circuit of a traditional backlight. As shown in Figure 1 , Vout is the output voltage of the front-stage DC / DC or AC / DC, the control unit generates a reference voltage Vref signal and a pulse width modulation PWM signal, the Vref signal generates a constant current of the channel through the operational amplifier OP and the high-voltage transistor HM and the resistor R, and the PWM signal is a dimming signal. In PWM dimming, the traditional backlight adopts a unified dimming mode, that is, the PWM1-PWMx signals of each channel are the same signal, and when adjusting, all the LED lamps of the channels have the same brightness. However, for the display device using the mini LED backlight, considering the demand for regional dimming, the current of each channel is different when 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 become urgent problems to be solved. SUMMARY

[0004] In view of the above problems, the present application provides a channel current control device and method for a mini LED backlight.

[0005] According to an aspect of the present application, a channel current control device for a mini LED backlight is provided, comprising: a control unit configured to provide 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 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 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 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 of the constant current control unit is connected with the low voltage transistor to realize current regulation and constant current control of the mini LED channel.

[0006] According to another aspect of the present application, a channel current control method for a mini LED backlight is provided, applied to the channel current control device as described above, the method comprising: providing, by a control unit, 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; using a high voltage transistor to perform dimming control on each mini LED channel based on the pulse width modulation signal, and using a constant current control unit and a 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.

[0007] According to still another aspect of the present application, a display device is provided, comprising a mini LED backlight and a channel current control device for the mini LED backlight as described above. BRIEF DESCRIPTION OF DRAWINGS

[0008] The present application can be better understood from the following description of specific embodiments thereof, taken in conjunction with the accompanying drawings in which:

[0009] Figure 1 A schematic diagram of a constant current control circuit of a conventional backlight is shown;

[0010] Figure 2 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 is shown;

[0011] Figure 3 A schematic diagram of a current control circuit of each channel in a channel current control device for a mini LED backlight according to an embodiment of the present application is shown;

[0012] Figure 4 A schematic diagram of a channel current control device for a mini LED backlight according to an embodiment of the present application is shown;Figure 3 schematic diagram of the circuit of each array unit in the decoder circuit shown in FIG. 1;

[0013] Figure 5 a schematic diagram of a current mirror control unit array according to another embodiment of the present application is shown.

[0014] Figure 6 a schematic diagram of a current mirror control unit array according to another embodiment of the present application is shown. DETAILED DESCRIPTION

[0015] The features and exemplary embodiments of the 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 present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without some or all of these specific details. The description of the embodiments is merely illustrative of the present application and is not intended to limit the present application, as is apparent to one of ordinary skill in the art. The present application is not limited to any particular configuration set forth below, but rather, the present application covers any and all modifications, equivalents, and alternatives falling within the spirit and scope of the present application. In the drawings and the following description, well-known structures and techniques have not been shown or described in detail in order to avoid unnecessarily obscuring the present application.

[0016] The present application proposes a channel current control device for a mini LED backlight, which sets the maximum brightness current of each channel through a reference voltage signal, realizes the dimming of each channel through the control of a high-voltage transistor by a PWM signal, and adjusts the channel current of each channel through a digital current setting (ISET) signal. In addition, the entire display screen can be divided into N regions (i.e., N channels), and the communication between the N regions and the control unit can adopt a serial time-division multiplexing manner. Therefore, the channel current control device according to the present application can fully meet the demand of the regional dimming of the mini LED backlight.

[0017] Figure 2 a schematic diagram of the circuit of the channel current control device for a mini LED backlight according to an embodiment of the present application is shown. As shown in FIG. 1, the mini LED backlight includes a plurality of mini LED channels, and the channel current control device includes a control unit for providing a corresponding control signal, such as a reference voltage Vref signal, a pulse width modulation PWM signal, and a digital ISET signal, to each mini LED channel. Figure 2

[0018] ​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 the 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 a PWM signal to perform dimming control on the mini LED channel based on the PWM signal; the input end of the constant current control unit is used to receive a Vref signal, a PWM signal and an ISET signal, and the output end thereof is connected with the low-voltage transistor to realize current regulation and constant current control on the mini LED channel together with the low-voltage transistor.

[0019] Compared with the constant current control circuit of the conventional backlight source shown in Figure 1 In the channel current control device according to the embodiment of the present application, Figure 1 the high-voltage transistor connected with each channel in the constant current control circuit of the conventional backlight source shown in is replaced by a series connection of a high-voltage transistor and a low-voltage transistor. The high-voltage transistor is responsible for PWM dimming of the channel and high-voltage isolation, 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 in use, and a smaller high-voltage transistor can be used under the condition that the current on the channel is the same as in the conventional architecture, thereby saving the chip area of the channel.

[0020] In addition, in the constant current control circuit of the conventional backlight source shown in Figure 1 the constant current control of each channel is realized by an operational amplifier OP and a high-voltage transistor HM and a resistor R. Unlike this, 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 conventional backlight source, the current of the channel is controlled by the digital ISET signal received by the channel, and the number of turned-on transistors in the current mirror circuit is controlled by a simple decoder array, so that the channel current is controlled according to the number of turned-on current mirror units. This can save the digital-to-analog conversion unit for digital-to-analog conversion of the digital ISET signal, and at the same time precise channel current control can be realized. The constant current control principle according to the embodiment of the present application will be explained below. Figure 3

[0021] Figure 3 A schematic diagram of the current control circuit of each channel in the channel current control device for a mini LED backlight source according to the embodiment of the present application is shown. 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 The decoder circuit is configured to generate N current mirror control signals based on the digital ISET signal, respectively for controlling the turn-on or turn-off of a corresponding one of the N output side transistors, thereby controlling the number of turn-on current mirror units.

[0022] The digital ISET signal can include n-bit binary code, thereby the 2 n N can be equal to 2 raised to the power of n. As shown in Figure 3 ISET signal, for example, is ISET<10:0>, accordingly, the 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 by the decoder circuit will be described in detail below with reference to Figure 4 to Figure 6 .

[0023] 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 for setting the maximum brightness current of the mini LED channel, the gate of the low-voltage transistor is connected to the drain of the input side transistor M0 through the second operational amplifier OP2, and the source of the low-voltage transistor is connected to the drain of the N parallel output side transistors.

[0024] It should be noted that according to some embodiments of the present application, the low-voltage transistor can include a plurality of low-voltage transistors in parallel, and the constant current control unit can further include a logic control circuit configured to generate a plurality of low-voltage transistor control signals based on the PWM signal and a predetermined number of high bits of the digital ISET signal, respectively for controlling the turn-on or turn-off of a corresponding one of the plurality of low-voltage transistors. For example, Figure 3 three low-voltage transistors and corresponding three low-voltage transistor control signals a, b, c are shown. In fact, each low-voltage transistor can also be in parallel with a predetermined number of low-voltage transistors. For example, Figure 3 m = 1 as shown in indicates that the first low-voltage transistor can include one low-voltage transistor, m = 3 indicates that the second low-voltage transistor can include three low-voltage transistors in parallel, and m = 5 indicates that the third low-voltage transistor can include three low-voltage transistors in parallel. That is, Figure 3 each channel as shown in

[0025] As shown in Figure 3As shown, the logic control circuit can receive the highest three bits of the digital ISET signal to generate low-voltage transistor control signals a, b, c for controlling the number of low-voltage transistors turned on. When regulating the channel current, the number of low-voltage transistors turned on is determined according to the magnitude order of the current, which can keep the gate voltage of the low-voltage transistor within a small range during the current regulation, thereby improving the anti-interference performance of the channel to a certain extent.

[0026] The specific structure of the decoder circuit according to the embodiments 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 Figure 4 to Figure 6

[0027] To control the N current mirror units, the decoder circuit can include N decoder sub-units for generating N current mirror control signals to control the turn-on or turn-off of the corresponding output-side transistor in the N output-side transistors, respectively.

[0028] Taking an 11-bit ISET<10:0> signal as an example, to convert the 11-bit ISET signal into a corresponding number of current mirror control signals, one solution can be to use an 11-bit binary code to control 2 11 transistors to turn on or off, which only requires 11 corresponding control signals. However, this solution is greatly affected by the current mirror matching accuracy, especially when a carry occurs at a high bit, the number of current mirror units turned on will change greatly. For example, when the control code word changes from 1023 (0x3ff in hexadecimal) to 1024 (0x400 in hexadecimal), the current mirror units previously turned on will be turned off, and the current mirror units previously turned off will be turned on. Due to the influence of the current mirror matching accuracy, the total current may change greatly, thereby affecting the linearity of current regulation. Therefore, this solution has a high requirement for the current mirror matching accuracy.

[0029] Another solution is to convert the control signal into a thermometer code, in which case only 1 current mirror will change its turn-on state when adjacent code words change, which can improve the linearity of current regulation. However, for the case of generating 2 11 current mirror control signals based on an 11-bit ISET signal, the number of control signals required is too large.

[0030] ​According to embodiments of this application, a matrix array control scheme is proposed. Specifically, the decoder circuit may include N decoder sub-units, which can be arranged in an M-row × K-column matrix array, wherein each array unit in the matrix array may include one or more decoder sub-units. Here, M multiplied by K may be equal to or less than N. When M multiplied by K equals N, each array unit in the matrix array includes one decoder sub-unit, while when M multiplied by K is less than N, each array unit in the matrix array may include multiple decoder sub-units.

[0031] Figure 4 Examples of embodiments according to this application are shown as follows Figure 3 The diagram shows a schematic of the circuitry for each array unit in the decoder circuit. The input control signals for this array unit are A, B, and C, and the output signal is D. The input control signals A, B, and C are thermometer code signals converted from the ISET signal, and the output signal D is the current mirror control signal generated by this array unit. Therefore, the decoder circuit also includes a code conversion unit (not shown in the diagram) for converting the ISET signal into the input control signals A, B, and C for each array unit. Figure 4 As shown, each array unit is controlled by signals A, B, and C. The control logic is: C||(A&B). That is, when signal C is present, all current mirror units corresponding to the corresponding row of array units are turned on. When signal C is absent, the A&B array controls the turn-on or turn-off of the corresponding current mirror units.

[0032] According to one embodiment of this application, when M multiplied by K equals N, each array unit in the matrix array includes a decoder subunit. The code conversion unit can convert the ISET signal into a first row control signal C including M-bit thermometer code, a second row control signal A including M-bit thermometer code, and a column control signal B including 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. The first row control signal has a higher priority than the second row control signal.

[0033] More specifically, the code conversion unit can 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 first row control signal C is equal to the value represented by the binary code of the highest m bits of the ISET signal, the value represented by the M-bit thermometer code of the second row control signal A is equal to the value represented by the binary code of the highest m bits of the ISET signal plus 1, 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.

[0034] Figure 5 A schematic diagram of an array of current mirror control units according to an embodiment of the application is shown. In this embodiment, assuming the ISET signal is a 9-bit binary code signal ISET<8:0>, the array of current mirror control units can be designed as a 16x32 matrix array. The current mirror control units here actually correspond to the decoder sub-units in the decoder circuit. That is, the decoder circuit can be arranged to include 16 rows of 32 columns of decoder sub-units (i.e. a total of 512 decoder sub-units), each matrix array unit including one decoder sub-unit. As shown, A1 to A32 can correspond to the 1st row of decoder sub-units, P1 to P32 can correspond to the 16th row of decoder sub-units, A1 to P1 can correspond to the 1st column of decoder sub-units, and A32 to P32 can correspond to the 32nd column of decoder sub-units. Figure 5

[0035] In this embodiment, the highest 4 bits ISET<8:5> of the ISET signal are converted to the first row signal C<15:0> in thermometer code, the lowest 5 bits ISET<4:0> are converted to the column signal B<31:0> in thermometer code, and ISET<8:5>+1 are converted to the second row signal A<15:0> in thermometer code, i.e. A controls one more row than C. When the control signal ISET<8:0> comes, the first row signal C will turn on all the units of the previous ISET<8:5> rows, and the ISET<8:5>+1th row signal A is high, at this time this row will control ISET<4:0> units to turn on according to the column signal B<31:0>, realizing the total number of units turned on: 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 controlled to turn on based on the high 4-bit control signal, ISET<4:0> represents the number of current mirror units controlled to turn on based on the low 5-bit control signal, and ISET<8:0> represents the number of current mirror units controlled to turn on based on the 9-bit control signal.

[0036] ​According to this embodiment, since the control signals A, B, and C for the rows and columns all use thermometer codes, taking code word +1 as an example, regardless of whether there is a carry-over in the code word, only a new conducting current mirror unit is added each time, while the existing conducting current mirror units remain unchanged. This improves the linearity of current regulation and reduces the number of control signals. For example, according to... Figure 5 The arrangement of the current mirror control unit array shown requires only 16 + 16 + 32 = 64 control signals instead of 512 to control the on or off of 512 current mirror units based on the 9-bit ISET signal.

[0037] Furthermore, for ISET signals with more bits, it is possible to use a method similar to... Figure 5 The current mirror control unit array is arranged as shown. For example, when the ISET signal is an 11-bit binary codeword ISET<10:0>, the on / off state of 2048 current mirror units can be controlled based on this ISET signal. A similar approach is used... Figure 5 The array arrangement shown allows the current mirror control unit to be arranged as a 32-row, 64-column matrix array. Using this array arrangement, if the control signals A, B, and C of each row and column all use thermometer codes, then 32 + 32 + 64 = 128 control signals are required, which significantly reduces the number of control signals compared to 2048.

[0038] However, in order to further reduce the number of control signals, it is possible to convert some of the most significant bits of the ISET signal into row and column control signals, and convert the remaining few low-signal bits into decoder subunits within the control array unit.

[0039] Using this array arrangement, when the ISET signal is an n-bit binary code, in order to control N=2 n A current mirror unit, and N decoder subunits in the decoder circuit can be arranged as an M-row × K-column matrix array, where each array unit in the matrix array includes multiple decoder subunits. For example, M multiplied by K can equal 2 to the power of p (p is less than n), and each array unit in the matrix array includes 2 to the power of (np) decoder subunits.

[0040] In this scenario, similar to the codeword conversion method described previously, the code conversion unit in the decoder circuit can convert the highest p bits of the ISET signal into a first row control signal including M-bit thermometer code, a second row control signal including M-bit thermometer code, and a column control signal including K-bit thermometer code. It also converts the remaining (np) bits of the ISET signal into array cell control signals including 2^(np)-power thermometer code. Each bit in the first and second row control signals controls the decoder subunit corresponding to a specific row of array cells in the matrix array, and each bit in the column control signals controls the decoder subunit corresponding to a specific column of array cells in the matrix array. The first row control signal has a higher priority than the second row control signal, and each bit in the array cell control signal controls the corresponding decoder subunit in each array cell of the matrix array.

[0041] Specifically, the ISET signal composed of the highest p bits can be called the high-order ISET signal. The code conversion unit can 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 to generate the column control signal based on the remaining (pm) bits of the high-order ISET signal. The value represented by the M-bit thermometer code of the first row control signal is equal to the value represented by the binary code of the highest m bits of the high-order ISET signal; the value represented by the M-bit thermometer code of the second row control signal is equal to the value represented by the binary code of the highest m bits of the high-order ISET signal plus 1; 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 (pm) bits of the high-order ISET signal.

[0042] Figure 6 A schematic diagram of a current mirror control unit array according to another embodiment of this application is shown. Figure 6 As shown, for the 11-bit ISET signal ISET<10:0>, after converting the highest 9 bits of the signal ISET<11:2> into row and column control, the lower 2 bits of the signal ISET<1:0> are converted into thermometer code signals to control the current mirror units more precisely. The current magnitude of each current mirror unit controlled is 1 / 4 of the original current mirror unit. The conduction or deactivation of these current mirror units is controlled according to the lower 2 bits of the ISET signal. Figure 6 The current mirror control unit array arrangement shown requires a total of 16 + 16 + 32 + 4 = 68 control signals to control 2048 current mirror units. This is significantly more complex than using a similar array arrangement. Figure 5 The arrangement of the current mirror control unit array shown can further reduce the number of control signals.

[0043] In addition, according to the embodiment of the present application, a channel current control method for a mini LED backlight is also provided. The method is applied to the channel current control device as described above, and comprises: providing, by the control unit, 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 using a high-voltage transistor to perform dimming control on each mini LED channel based on the pulse width modulation signal, and using a constant current control unit and a low-voltage transistor to realize current adjustment and constant current control on the mini LED channel based on the reference voltage signal, the pulse width modulation signal and the digital current setting signal.

[0044] The channel current control device and method according to the embodiment of the present application can fully meet the needs of area dimming of the mini LED backlight.

[0045] It is mentioned above that “one embodiment”, “another embodiment”, “an embodiment” are mentioned; however, it should be understood that the features mentioned in each embodiment do not necessarily only apply to this embodiment, but can be applied to other embodiments. The features in one embodiment can be applied to another embodiment, or can be included in another embodiment.

[0046] It is mentioned above that “first”, “second” and the like ordinal numbers are mentioned. However, it should be understood that these expressions are only for the convenience of narration and reference, and there is no order relationship between the objects defined.

[0047] In addition, various operations or steps are described as a plurality of discrete operations; however, the order of description should not be interpreted as implying that these operations or steps must be dependent on the order. In particular, these operations or steps do not need to be performed in the order presented.

[0048] The present application can be implemented in other specific forms without departing from the spirit and essential characteristics thereof. For example, the features described in the specific embodiments can be modified without departing from the basic spirit of the present application. Therefore, the current embodiments are considered to be exemplary rather than limiting, the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and equivalents of the claims are included in the scope of the present application.

Claims

1. A channel current control device for a mini LED backlight, comprising: a control unit configured to provide 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 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 the mini LED channel and the low voltage transistor, and a gate of the high voltage transistor is configured to receive the pulse width modulation signal, an input of the constant current control unit is configured to receive the reference voltage signal, the pulse width modulation signal and the digital current setting signal, and an output of the constant current control unit is connected with the low voltage transistor to achieve current regulation and constant current control of the mini LED channel, wherein the constant current control unit comprises a current mirror circuit and a decoder circuit, the current mirror circuit comprises 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 for controlling a corresponding one of the N output side transistors to be turned on or turned off, wherein the digital current setting signal comprises an n-bit binary code, and the N equals to 2 raised to the power of n. the reference voltage signal is connected to a gate of the input side transistor through a first operational amplifier for setting a maximum brightness current of the mini LED channel.

2. The access current control device of claim 1, wherein, a gate of the low voltage transistor is connected to a drain of the input side transistor through a second operational amplifier, and a source of the low voltage transistor is connected to drains of the N output side transistors.

3. The access current control device of claim 1, wherein, the low voltage transistor comprises a plurality of low voltage transistors connected in parallel, and the constant current control unit further comprises:

4. The access current control device according to any one of claims 1 to 3, wherein, a logic control circuit configured to generate a plurality of low voltage transistor control signals based on a predetermined number of high bits of the pulse width modulation signal and the digital current setting signal for controlling a corresponding one of the plurality of low voltage transistors to be turned on or turned off. the decoder circuit comprises N decoder sub-units for generating the N current mirror control signals; 5. The access current control device of claim 1, wherein, and the N decoder sub-units are arranged as a matrix array of M rows by K columns, wherein each array unit in the matrix array comprises one or more decoder sub-units. M multiplied by K equals to N, and each array unit in the matrix array comprises one decoder sub-unit.

6. The access current control device of claim 5, wherein, the decoder circuit further comprises a code conversion unit configured to convert the digital current setting signal into a first row control signal comprising M-bit thermometer code, a second row control signal comprising M-bit thermometer code and a column control signal comprising K-bit thermometer code; 7. The access current control device of claim 6, wherein, each bit in the first row control signal and the second row control signal is configured to control a corresponding one of M rows of decoder sub-units in the N decoder sub-units, respectively; and each bit in the column control signal is configured to control a corresponding one of K columns of decoder sub-units in the N decoder sub-units, respectively. Each bit of the column control signals is used to control a corresponding column of decoder sub-units in the N decoder sub-units, respectively; and The first row control signal has a higher priority than the second row control signal.

8. The access current control device of claim 7, 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, and generate the column control signals based on the remaining (n-m) bits of the digital current setting signal.

9. The access current control device of claim 8, wherein, The value represented by the M-bit thermometer code of the first row control signal is equal to the value represented by the binary code of the highest m bits 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 binary code of the highest m bits of the digital current setting signal plus 1; The value represented by the K-bit thermometer code of the column control signals is equal to the value represented by the binary code of the remaining (n-m) bits of the digital current setting signal.

10. The access current control device of claim 5, wherein, M multiplied by K is equal to 2 raised to the power of p and p is less than n, and each array unit in the matrix array includes 2 raised to the power of (n-p) decoder sub-units.

11. The access current control device of claim 10, wherein, The decoder circuit further includes a code conversion unit configured to convert the highest p bits of the digital current setting signal into a first row control signal including an M-bit thermometer code, a second row control signal including an M-bit thermometer code, and column control signals including a K-bit thermometer code, and convert the remaining (n-p) bits of the digital current setting signal into an array unit control signal including a 2 raised to the power of (n-p) 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 array units in the matrix array, respectively. Each bit of the column control signals is used to control a corresponding column of array units in the matrix array, respectively. 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 used to control a corresponding decoder sub-unit in each array unit in the matrix array, respectively.

12. The access current control device of claim 11, wherein, The highest p bits of the digital current setting signal constitute a high-bit 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-bit digital current setting signal, and generate the column control signals based on the remaining (p-m) bits of the high-bit digital current setting signal.

13. The access current control device of claim 12, wherein, The value represented by the M-bit thermometer code of the first row control signal is equal to the value represented by the binary code of the highest m bits of the high-bit 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 binary code of the highest m bits of the high-bit digital current setting signal plus 1; The value represented by the K-bit thermometer code of the column control signals is equal to the value represented by the binary code of the remaining (p-m) bits of the high-bit digital current setting signal.

14. The access current control device of claim 7 or 8 or 9 or 11 or 12 or 13, 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.

15. A channel current control method for a mini LED backlight, applied to the channel current control device of any one of claims 1-14, the method comprising: providing, by the control unit, 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; controlling, by the high-voltage transistor, each mini LED channel based on the pulse width modulation signal, implementing, by the constant current control unit and the low-voltage transistor, 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.

16. The method of controlling the channel current according to claim 15, wherein, The constant current control unit includes a current mirror circuit and a decoder circuit, the current mirror circuit including an input-side transistor and N output-side transistors connected in parallel, the method further comprising: generating, by the decoder circuit, N current mirror control signals based on the digital current setting signal, for controlling the conduction or non-conduction of a corresponding output-side transistor in the N output-side transistors, wherein the digital current setting signal includes an n-bit binary code, and the N is equal to 2 raised to the power of n.

17. The method of controlling the channel current according to claim 16, 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 the maximum brightness current of the corresponding mini LED channel based on the reference voltage signal.

18. The method of controlling a channel current according to claim 15, wherein, The low-voltage transistor includes a plurality of low-voltage transistors connected in parallel, and the method further comprises generating a plurality of low-voltage transistor control signals based on a predetermined number of high bits of the pulse width modulation signal and the digital current setting signal, for controlling the conduction or non-conduction of a corresponding low-voltage transistor in the plurality of low-voltage transistors.

19. A display device comprising a mini LED backlight and a channel current control device for the mini LED backlight as claimed in any one of claims 1-14.

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