Driving circuit and method of display module, display module

Abstract

This application discloses a driving circuit and method for a display module, and the display module itself. The display module includes at least two sets of LED strings, each set connected to a voltage source. The driving circuit includes an LED string driver chip, a control module, a switching module, and a shifting module. The control module generates control signals and shift pulse signals. The first terminals of at least two switching units of the switching module are connected one-to-one with at least two channels of the LED string driver chip, and their second terminals are connected one-to-one with at least two sets of LED strings. The shifting module receives shift pulse signals and control signals, shifts the control signals at least once according to the shift pulse signals, and outputs the shifted signals to the control terminals of the corresponding switching units to control at least two switching units to turn on the channels of their corresponding LED string driver chips at different times. The LED string driver chip dims the LED strings in the turned-on channels. This method solves the overheating problem of the display module.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to driving circuits and methods for display modules, and display modules. Background Technology

[0002] Currently, more and more display products are using Mini-LED (small light-emitting diode) as the light source. Mini-LED adopts a direct-lit, small-pitch LED design, and achieves regional dimming in a smaller area through a large number of densely packed LEDs. Compared with traditional light source designs, it can achieve better brightness uniformity and higher color contrast within a smaller light mixing distance, enabling ultra-thin designs of terminal products and saving energy.

[0003] Mini-LED backlit LEDs typically use PWM (Pulse Width Modulation) dimming. However, the disadvantage of PWM dimming is that the PWM signal supplied to all LED driver chips is the same, and the current in each current channel of the same driver chip is the same. This can cause excessive instantaneous current drawdown of the driver chip, resulting in excessive EMI (Electromagnetic Interference) energy. This poses a challenge to both the LED driver chip and EMI standards. Furthermore, since the current passes through for the same amount of time, the LED strings heat up simultaneously, causing a sudden release of heat and severe overheating. Summary of the Invention

[0004] This application provides a driving circuit and method for a display module, and a display module that can solve the overheating problem of the display module.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: providing a driving circuit for a display module, the display module including at least two sets of light strings, each set of light strings being connected to a voltage source; the driving circuit including: a light string driver chip; a control module for generating control signals and shift pulse signals; a switching module including at least two switching units, the first terminals of the at least two switching units being connected one-to-one with at least two channels of the light string driver chip, and the second terminals of the at least two switching units being connected one-to-one with at least two sets of light strings; a shifting module, the shifting module being connected one-to-one with the control terminals of the at least two switching units, and the shifting module being connected to the control module for receiving shift pulse signals and control signals, shifting the control signals at least once according to the shift pulse signals, and outputting them to the control terminals of the corresponding switching units to control the at least two switching units to turn on the channels of their corresponding light string driver chips at different times; the light string driver chip is used to dim the light strings of the channel after the channel is turned on.

[0006] The shift module includes at least two shift registers connected in sequence; the output terminals of the at least two shift registers are connected one-to-one with the control terminals of at least two switching units, and each shift register is used to receive shift pulse signals, shift the input control signals, and output them to the control terminal of its corresponding switching unit.

[0007] Among them, at least two shift registers are at least two D flip-flops; the output terminals of at least two D flip-flops are connected one-to-one with the control terminals of at least two switching units; the data input terminal of the first D flip-flop in the at least two D flip-flops is used to receive control signals, the clock input terminal of each D flip-flop is used to receive shift pulse signals, and the non-inverting output terminal of each D flip-flop is connected to the data input terminal of the next adjacent D flip-flop and the control terminal of the corresponding switching unit.

[0008] Specifically, when the light emission times of the LED strings corresponding to each channel of the LED string driver chip do not overlap, the shift pulse signal needs to ensure that the light emission time interval between the LED strings meets the following condition: m=1 / (F (n)-a; where m represents the interval, F represents the refresh rate, n represents the number of channels connected to the LED string driver chip and the LED string, and a represents the light emission time of the LED string corresponding to each channel.

[0009] When the light emission times of the LED strings corresponding to each channel of the LED string driver chip overlap, the shift pulse signal needs to ensure that the overlapping light emission times of each LED string meet the following conditions: h = (1 / F - 2a) / (n - 2); where m represents the interval, F represents the refresh rate, n represents the number of channels connected to the LED string driver chip and the LED string, a represents the light emission time of the LED string corresponding to each channel, and h represents the light emission overlap time.

[0010] The illumination time of each light string is positively correlated with the pulse width of the shift pulse signal.

[0011] The control module is also used to acquire the position information of the target light string, determine the target switch unit corresponding to the target light string based on the position information, and adjust the pulse width of the shift pulse segment in the shift pulse signal corresponding to the target switch unit based on the target switch unit. The target light string is a light string whose luminous brightness is greater than or less than that of the other light strings.

[0012] The control module is also used to obtain the position information of the target light string, obtain the target channel on the light string driver chip corresponding to the target light string based on the position information, and determine the target switch unit corresponding to the target light string through the target channel.

[0013] To solve the above-mentioned technical problems, another technical solution adopted in this application is to provide a display module, which includes the driving circuit provided by the above-mentioned technical solution.

[0014] To solve the above-mentioned technical problems, another technical solution adopted in this application is to provide a display device, which includes the display module provided by the above-mentioned technical solution.

[0015] To solve the above-mentioned technical problems, another technical solution adopted in this application is: providing a driving method for a display module, the display module including at least two sets of light strings, each set of light strings being connected to a voltage source; applied to a driving circuit, the driving circuit including: a light string driver chip, a control module, a switching module, and a shifting module, the method including: the control module sending a shift pulse signal and a control signal to the shifting module, so that the shifting module shifts the control signal at least once according to the shift pulse signal, and outputs it to the control terminal of the corresponding switching unit in the switching module; controlling different switching units in the switching module to turn on the channels of their corresponding light string driver chips at different times; after the channel is turned on, the light string driver chip dims the light strings of the channel.

[0016] The display module driving circuit and method provided in this application, and the display module itself, include a corresponding switching unit between the channel of the LED string driver chip and each group of LED strings. A shift module receives shift pulse signals and control signals sent by a control module. The shift module shifts the control signal at least once according to the shift pulse signal and outputs it to the control terminal of the corresponding switching unit to control at least two switching units to turn on the channel of their corresponding LED string driver chip at different times. The LED string driver chip is used to dim the LED strings in the channel after the channel is turned on, allowing the LED strings to receive current at staggered peaks, thus ensuring that the LED string driver chip operates within a certain time period. The current does not reach its peak simultaneously as in related technologies, and the EMI energy in this frequency band is not as concentrated, thus reducing noise. This solves the problem of excessive instantaneous current drawdown and severe overheating of the LED string driver chip caused by the same PWM signal supplied to all LED string driver chips in the display module and the same current in each current channel of the same LED string driver chip. It also solves the problem of excessive EMI energy exceeding the standard in a certain frequency band, and the problem of instantaneous heat release and severe overheating caused by the same current flow time and emission time between LED strings in related technologies. Furthermore, this application can also flexibly adjust the emission time of each LED string corresponding to each channel of each LED string driver chip by controlling the shift pulse signal, achieving precise distributed phase control and further improving the dimming accuracy of the area. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 A schematic diagram of the product architecture for the related Mini-LED light source design; Figure 2 This is a schematic diagram of the structure of an embodiment of the Mini-LED light source provided in this application; Figure 3 This is a schematic diagram of the structure of an embodiment of the driving circuit of the display module provided in this application; Figure 4 This is a waveform diagram corresponding to the shift module; Figure 5 This is a waveform diagram corresponding to the LED string driver chip; Figure 6 This is a schematic diagram of another embodiment of the driving circuit of the display module provided in this application; Figure 7 This is a schematic diagram of another embodiment of the driving circuit of the display module provided in this application; Figure 8 This is a waveform diagram showing that the light emission times of the light string do not overlap; Figure 9 This is a waveform diagram illustrating the adjustment of the light intensity of the corresponding LED string in the channel; Figure 10 This is a schematic diagram of the display brightness provided in this application; Figure 11 This is a schematic diagram of the structure of an embodiment of the display module provided in this application; Figure 12 This is a schematic diagram of the structure of an embodiment of the display device provided in this application; Figure 13 This is a flowchart illustrating an embodiment of the driving method for the display module provided in this application.

[0018] Annotation instructions: LED string: 1; LED string: 2; LED string: 3; LED string driver chip: 10; Control module: 20; Switch module: 30; Shift module: 40; First shift register: 41; Second shift register: 42; Third shift register: 43; Switch unit: T1; Switch unit: T2; Switch unit: T3; First D flip-flop: 401; Second D flip-flop: 402; Third D flip-flop: 403; Display module: 200; Backlight module: 101; Driver circuit: 102; Display device: 300. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are only for explaining this application and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, not all structures. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] Currently, more and more display products are using Mini-LED as the backlight. Mini-LED adopts a direct-lit, small-pitch LED design, and achieves regional dimming in a smaller area through a large number of densely packed LEDs. Compared with traditional backlight designs, it can achieve better brightness uniformity and higher color contrast within a smaller light mixing distance, enabling ultra-thin designs of terminal products and saving energy. The related Mini-LED backlight control technology adopts a traditional one-to-one control method, that is, each control LED zone corresponds to one constant current drive chip control channel. When the number of zones reaches more than a thousand, the number of constant current control chips will increase sharply, which will consume a large number of chips. Mini-LED technology can be understood as a comprehensive upgrade to LCD (Liquid Crystal Display). The backlight layer of Mini-LED can accommodate more LEDs per unit area, significantly increasing the number of backlight sources. This allows for regional brightness adjustment, enabling the switching off of LEDs in specific areas to achieve complete black. This not only reduces power consumption but also, due to the increased number of LEDs per unit area, achieves ultra-high contrast and fine dynamic distribution, making bright areas brighter and dark areas darker, resulting in a more detailed display. Mini-LED backlighting can be combined with Local Dimming technology to control the switching and brightness adjustment of corresponding backlight areas in real time based on the brightness and darkness of different parts of the TV signal, making blacks deeper, whites whiter, and colors more natural and vibrant, providing an immersive and lifelike visual experience.

[0022] Mini-LED backlit LEDs typically use PWM dimming. However, PWM dimming has a drawback: the PWM signal is the same for all driver chips, and the current in each current channel of the same driver chip is the same. This can cause excessive instantaneous current draw of the driver chip, resulting in high EMI energy, which poses a challenge to both IC and EMI standards. Furthermore, the simultaneous heating of the LEDs due to the same current flow time leads to rapid heat release and severe overheating. This design also has significant limitations due to the identical current and dimming across all channels of the same driver chip. Additionally, if the PWM signal frequency is between 200Hz and 20kHz, the inductors and capacitors will emit audible noise.

[0023] like Figure 1 For the product architecture related to Mini-LED backlight design, the motherboard is a comprehensive module responsible for transmitting signals and power. This module includes a control module, a logic module, and a power module. The control module is used to control the switching of the LED strings in the Mini-LED backlight module and the activation of the TFT display. The logic module receives signals from the motherboard and generates the necessary logic signals for the Mini-LED and the display. The power module receives the input voltage from the motherboard and generates the required voltage and current based on the brightness requirements of the LED strings and the display's specifications. The Mini-LED backlight is composed of multiple modules, such as... Figure 2 Each module corresponds to a LED string driver chip, and multiple modules share a set of VLED voltages. Each constant current driver chip has multiple control channels used to control the current of each LED string. Each LED string consists of multiple LEDs connected in series. The voltage of each LED in a string is determined by VLED. The value of VLED divided by the number of strings gives the voltage of each LED. Since the current flowing through a string is the same, the brightness of each LED in a string is the same. And since the current value set for each channel of the LED driver chip is the same, all LEDs controlled by one LED driver have the same brightness. Thus, it can be seen that although Mini-LED backlighting can dim locally, the dimming area precision is limited.

[0024] Based on this, the display module driving circuit and method, and the display module provided in this application, set corresponding switching units between the channels of the LED string driver chip and each group of LED strings, and utilize a shift module to receive shift pulse signals and control signals sent by the control module. The shift module shifts the control signal at least once according to the shift pulse signal and outputs it to the control terminal of the corresponding switching unit to control at least two switching units to turn on the channels of their corresponding LED string driver chips at different times. The LED string driver chip is used to dim the LED strings in the channel after the channel is turned on, so that the current supplied to the LED strings can be staggered, so that the current of the LED string driver chip in a certain period of time is... Unlike related technologies, this technology avoids simultaneous peak values, and the EMI energy in this frequency band is less concentrated, thus reducing noise. It solves the problems of excessive instantaneous current drawdown and severe overheating of the LED string driver chip caused by the same PWM signal supplied to all LED string driver chips in Mini-LED backlighting and the same current in each current channel of the same LED string driver chip. It also solves the problem of excessive EMI energy exceeding standards in a single frequency band, and addresses the issue of simultaneous heat release and severe overheating caused by the same current flow time and emission time between LED strings in related technologies. Furthermore, this application can flexibly adjust the emission time of each LED string corresponding to each channel of each LED string driver chip by controlling the shift pulse signal, achieving precise distributed phase control and further improving the dimming accuracy of the area. See any of the following embodiments for details.

[0025] See Figure 3 , Figure 3 This is a schematic diagram of an embodiment of the driving circuit for a display module provided in this application. The display module includes at least two sets of LED strings, each set of LED strings being connected to a voltage source VIN. Figure 3 As shown, the display module includes string light 1, string light 2, and string light 3. It can be understood that... Figure 3 The number of LED strings shown is for illustrative purposes only; the actual number depends on the display module configuration. For example, at least three sets of LED strings, at least five sets of LED strings, at least ten sets of LED strings, at least twenty sets of LED strings, or at least fifty sets of LED strings. Each set of LED strings can be formed by several LEDs connected in series. In some embodiments, the display module can be a backlight module. In some embodiments, the display module can include a backlight module and a display device. In some embodiments, the display device can further include a display panel.

[0026] The driving circuit includes: a light string driver chip 10, a control module 20, a switch module 30, and a shift module 40.

[0027] The LED string driver chip 10 is an electronic integrated circuit that controls the operation of LED devices (LED strings). Because LEDs have negative temperature characteristics (resistance decreases as temperature increases), a stable current is required to prevent thermal runaway. This chip achieves brightness adjustment and stable operation by converting the input power supply into a constant current.

[0028] The control module 20 is used to generate control signals and shift pulse signals. The control module 20 can be composed of a corresponding processor, such as a microcontroller, a central processing unit, or a timing controller. Details will not be elaborated here.

[0029] The switch module 30 includes at least two switch units. The first terminals of each of the at least two switch units are connected one-to-one to at least two channels of the LED string driver chip 10, and the second terminals of each of the at least two switch units are connected one-to-one to at least two sets of LED strings. For example... Figure 3 As shown, the switch module 30 includes switch unit T1, switch unit T2, and switch unit T3. The first terminal of switch unit T1 is connected to channel out1 of the LED string driver chip 10, the first terminal of switch unit T2 is connected to channel out2 of the LED string driver chip 10, and the first terminal of switch unit T3 is connected to channel out3 of the LED string driver chip 10. The second terminal of switch unit T1 is connected to LED string 1, the second terminal of switch unit T2 is connected to LED string 2, and the second terminal of switch unit T3 is connected to LED string 3. Switch units T1, T2, and T3 can be electronic components with switching capabilities, such as transistors.

[0030] The shift module 40 is connected to the control terminals of at least two switching units one-to-one, and is also connected to the control module 20. It receives shift pulse signals and control signals, shifts the control signals at least once according to the shift pulse signals, and outputs the shifted signals to the control terminals of the corresponding switching units to control the at least two switching units to turn on the channels of their corresponding LED string driver chips 10 at different times. Figure 3 As shown, the shift module 40 is connected to the control terminals of the switch units T1, T2, and T3 respectively.

[0031] The LED string driver chip 10 is used to dim the LED strings in the channel after the channel is turned on. For example... Figure 3 As shown, after channel 1 is turned on, the corresponding light string 1 is dimmed. After channel 2 is turned on, the corresponding light string 2 is dimmed. After channel 3 is turned on, the corresponding light string 3 is dimmed.

[0032] In some embodiments, combined with Figure 4 and Figure 5 Explanation: After control module 20 provides a PWM signal to shift module 40, and control module 20 also provides a shift pulse signal to shift module 40, such as a one-cycle square wave signal, shift module 40 reads the state of the PWM signal when the first rising edge of the shift pulse signal CPV arrives. At this time, the PWM signal state is H (high level), and shift module 40 outputs a level signal of state H to the control terminal of switching unit T1. See details... Figure 4 The waveform corresponding to Q1, Figure 4 The waveform corresponding to Q1 represents the waveform of the level signal received by the control terminal of the switching unit T1. When the second pulse signal in the shift pulse signal CPV arrives, the shift module 40 reads the state as H, and then the shift module 40 outputs the level signal of state H to the control terminal of the switching unit T2. See details... Figure 4 The waveform corresponding to Q2, Figure 4 The waveform corresponding to Q2 represents the waveform of the level signal received by the control terminal of the switching unit T2. When the third pulse signal in the shift pulse signal CPV arrives, the shift module 40 reads the state as H, and then the shift module 40 outputs the level signal of state H to the control terminal of the switching unit T3. See details... Figure 4 The waveform corresponding to Q3, Figure 4 The waveform corresponding to Q3 represents the waveform of the level signal received by the control terminal of the switching unit T3. Similarly, when the PWM signal is in the L (low level) state, the rising edge of the first shift pulse signal CPV after the L state is used to read the state of the PWM signal. Since it is L, the shift module 40 outputs a level signal in the L state to the control terminal of the switching unit T1. Based on this, when the rising edge of the next shift pulse signal CPV arrives, the shift module 40 outputs a level signal in the L state to the control terminal of the switching unit T2, and so on. At the end, a clear signal is used to pull all the outputs of the shift module 40 to the control terminals of the switching units T1, T2, and T3 to zero. This allows the PWM signal to be output in staggered shifts for each channel of the LED string driver chip 10. Figure 5 As shown, within one cycle of PWM dimming, multiple channels of the LED string driver chip 10 can be distributed for phase dimming. Figure 5 In the diagram, out1 represents the waveform corresponding to channel out1, out2 represents the waveform corresponding to channel out2, and out3 represents the waveform corresponding to channel out3. Because the channels are open for the same duration but have different phases, their brightness is the same. However, this allows the LED strings of the corresponding channels to stagger their current supply within a cycle. Therefore, the current of the corresponding LED string driver chip 10 will not reach its peak simultaneously in a certain period of time, unlike in related technologies. Furthermore, the EMI energy in this frequency band is not as concentrated, and the noise can also be reduced.

[0033] In this embodiment, corresponding switching units are set between the channels of the LED string driver chip 10 and each group of LED strings. A shift module 40 receives the shift pulse signal CPV and control signal sent by the control module 20. The shift module 40 shifts the control signal at least once according to the shift pulse signal CPV and outputs it to the control terminal of the corresponding switching unit to control at least two switching units to turn on their corresponding LED string driver chip 10 channels at different times. The LED string driver chip 10 is used to dim the LED strings in the channel after the channel is turned on, allowing the LED strings to stagger their current supply, so that the current of the LED string driver chip 10 at a certain time period will not be as high as expected. This technology achieves peak performance simultaneously, and EMI energy is less concentrated in that frequency band, thus reducing noise. It solves the problems of excessive instantaneous current drawdown and severe overheating of the LED string driver chip 10 caused by the same PWM signal supplied to all LED string driver chips 10 in Mini-LED backlighting and the same current in each current channel of the same LED string driver chip 10. It also solves the problem of excessive EMI energy exceeding standards in a single frequency band, and addresses the issue of simultaneous heat release and severe overheating caused by the same current flow time and emission time between LED strings in related technologies. Furthermore, this application can flexibly adjust the emission time of each LED string corresponding to each channel of each LED string driver chip 10 by controlling the shift pulse signal CPV, achieving precise distributed phase control and further improving the dimming accuracy of the area.

[0034] See Figure 6 , Figure 6 This is a schematic diagram of another embodiment of the driving circuit for the display module provided in this application. The display module includes at least two sets of LED strings, each set of LED strings being connected to a voltage source VIN. For example... Figure 6 As shown, the display module includes LED string 1, LED string 2 and LED string 3.

[0035] The driving circuit includes: a light string driver chip 10, a control module 20, a switch module 30, and a shift module 40.

[0036] The control module 20 is used to generate control signals and shift pulse signals CPV.

[0037] The switch module 30 includes at least two switch units. The first ends of the at least two switch units are connected one-to-one with at least two channels of the LED string driver chip 10, and the second ends of the at least two switch units are connected one-to-one with at least two sets of LED strings. For example... Figure 6As shown, the switch module 30 includes switch unit T1, switch unit T2, and switch unit T3. The first terminal of switch unit T1 is connected to channel out1 of the LED string driver chip 10, the first terminal of switch unit T2 is connected to channel out2 of the LED string driver chip 10, and the first terminal of switch unit T3 is connected to channel out3 of the LED string driver chip 10. The second terminal of switch unit T1 is connected to LED string 1, the second terminal of switch unit T2 is connected to LED string 2, and the second terminal of switch unit T3 is connected to LED string 3.

[0038] The shift module 40 includes: at least two shift registers connected in sequence; the output terminals of the at least two shift registers are connected one-to-one with the control terminals of at least two switching units, and each shift register is used to receive a shift pulse signal CPV, shift the input control signal, and output it to the control terminal of its corresponding switching unit. Figure 4 As shown, the shift module 40 includes a first shift register 41, a second shift register 42, and a third shift register 43. The output of the first shift register 41 is connected to the control terminal of the switching unit T1. The output of the second shift register 42 is connected to the control terminal of the switching unit T2. The output of the third shift register 43 is connected to the control terminal of the switching unit T3. The number of shift registers corresponds to the number of LED strings, or the number of shift registers corresponds to the number of switching units.

[0039] In some embodiments, combined with Figure 4 and Figure 5 Explanation: like Figure 4 As shown, after the control module 20 provides a PWM signal to the shift module 40, and the control module 20 also provides a shift pulse signal CPV to the shift module 40, such as a square wave signal with one cycle, the first shift register 41 reads the state of the PWM signal when the first rising edge of the shift pulse signal CPV arrives. At this time, the state of the PWM signal is H (high level), so the first shift register 41 outputs the level signal of state H to the control terminal of the switching unit T1. See details. Figure 4 The waveform corresponding to Q1. When the second pulse signal in the shift pulse signal CPV arrives, the second shift register 42 reads the state as H, and then the second shift register 42 outputs the level signal of state H to the control terminal of the switching unit T2. See details. Figure 4 The waveform corresponding to Q2. When the third pulse signal in the shift pulse signal CPV arrives, the third shift register 43 reads the state as H, and then the third shift register 43 outputs the level signal of state H to the control terminal of the switching unit T3. See details. Figure 4The waveform corresponding to Q3. Similarly, when the PWM signal is in the L (low level) state, the rising edge of the first shift pulse signal CPV after the L state is used to read the state of the PWM signal. Since it is L at this time, the first shift register 41 outputs an L-state level signal to the control terminal of the switching unit T1. Based on this, when the rising edge of the next shift pulse signal CPV arrives, the second shift register 42 also outputs an L-state level signal to the control terminal of the switching unit T2, and so on. At the end, a clear signal is used to pull all the outputs of the shift registers to the control terminals of switching units T1, T2, and T3 to zero. This allows the PWM signal to be output in staggered shifts for each channel of the LED string driver chip 10, such as... Figure 5 As shown, within one cycle of PWM dimming, multiple channels of the LED string driver chip 10 can be distributed for phase dimming. Figure 5 In the diagram, out1 represents the waveform corresponding to channel out1, out2 represents the waveform corresponding to channel out2, and out3 represents the waveform corresponding to channel out3. Because the channels are open for the same duration but have different phases, their brightness is the same. However, this allows the LED strings of the corresponding channels to stagger their current supply within a cycle. Therefore, the current of the corresponding LED string driver chip 10 will not reach its peak simultaneously in a certain period of time, unlike in related technologies. Furthermore, the EMI energy in this frequency band is not as concentrated, and the noise can also be reduced.

[0040] In this embodiment, corresponding switching units are set between the channels of the LED string driver chip 10 and each group of LED strings. The shift module 40 receives the shift pulse signal CPV and control signal sent by the control module 20. The first shift register 41, the second shift register 42, and the third shift register 43 shift the control signal at least once according to the shift pulse signal CPV and output it to the control terminal of the corresponding switching unit to control at least two switching units to turn on their corresponding LED string driver chip 10 channels at different times. The LED string driver chip 10 is used to dim the LED strings in the channel after the channel is turned on, allowing the LED strings to receive current at different times, thus enabling the LED string driver chip 10 to dim the LED strings after the channel is turned on. The current in a given time period will not reach its peak simultaneously as in related technologies, and the EMI energy in that frequency band is not as concentrated, thus reducing noise. This solves the problem of excessive instantaneous current drawdown and severe overheating of the LED string driver chip 10 caused by the same PWM signal supplied to all LED string driver chips 10 for Mini-LED backlighting and the same current in each current channel of the same LED string driver chip 10. It also solves the problem of excessive EMI energy exceeding the standard in a certain frequency band, and the problem of instantaneous heat release and severe overheating caused by the same current flow time and light emission time between LED strings in related technologies. Furthermore, this application can also flexibly adjust the light emission time of each LED string corresponding to each channel of each LED string driver chip 10 by controlling the shift pulse signal CPV, achieving precise distributed phase control and further improving the dimming accuracy of the area.

[0041] See Figure 7 , Figure 7 This is a schematic diagram of another embodiment of the driving circuit for the display module provided in this application. The display module includes at least two sets of LED strings, each set of LED strings being connected to a voltage source VIN. For example... Figure 7 As shown, the display module includes LED string 1, LED string 2 and LED string 3.

[0042] The driving circuit includes: a light string driver chip 10, a control module 20, a switch module 30, and a shift module 40.

[0043] The control module 20 is used to generate control signals and shift pulse signals CPV.

[0044] The switch module 30 includes at least two switch units. The first ends of the at least two switch units are connected one-to-one with at least two channels of the LED string driver chip 10, and the second ends of the at least two switch units are connected one-to-one with at least two sets of LED strings. For example... Figure 7As shown, the switch module 30 includes switch unit T1, switch unit T2, and switch unit T3. The first terminal of switch unit T1 is connected to channel out1 of the LED string driver chip 10, the first terminal of switch unit T2 is connected to channel out2 of the LED string driver chip 10, and the first terminal of switch unit T3 is connected to channel out3 of the LED string driver chip 10. The second terminal of switch unit T1 is connected to LED string 1, the second terminal of switch unit T2 is connected to LED string 2, and the second terminal of switch unit T3 is connected to LED string 3.

[0045] The shift module 40 includes: at least two D flip-flops connected in sequence; the outputs of the at least two D flip-flops are connected one-to-one with the control terminals of at least two switching units; wherein, the data input terminal of the first D flip-flop is used to receive a control signal, the clock input terminal of each D flip-flop is used to receive a shift pulse signal CPV, and the non-inverting output terminal of each D flip-flop is connected to the data input terminal of the next adjacent D flip-flop and the control terminal of the corresponding switching unit. That is, the D flip-flops are equivalent to the shift register described above.

[0046] like Figure 7 As shown, the shift module 40 includes a first D flip-flop 401, a second D flip-flop 402, and a third D flip-flop 403. The output of the first D flip-flop 401 is connected to the control terminal of the switching unit T1. The output of the second D flip-flop 402 is connected to the control terminal of the switching unit T2. The output of the third D flip-flop 403 is connected to the control terminal of the switching unit T3. The number of D flip-flops corresponds to the number of LED strings, or the number of D flip-flops corresponds to the number of switching units.

[0047] In some embodiments, combined with Figure 4 and Figure 5 Explanation: like Figure 4 As shown, after the control module 20 provides a PWM signal to the shift module 40, it also provides a shift pulse signal CPV to the shift module 40. For example, the shift pulse signal CPV is a square wave signal with one cycle. The first D flip-flop 401 reads the state of the PWM signal when the first rising edge of the shift pulse signal CPV arrives. At this time, the PWM signal state is H (high level). Then, the first D flip-flop 401 outputs a level signal of state H to the control terminal of the switching unit T1. See details... Figure 4 The waveform corresponding to Q1. When the second pulse signal in the shift pulse signal CPV arrives, the second D flip-flop 402 reads the state as H, and the shift module outputs the level signal of state H to the control terminal of the switching unit T2. See details. Figure 4The waveform corresponding to Q2. When the third pulse signal in the shift pulse signal CPV arrives, the third D flip-flop 403 reads the state as H, then the first D flip-flop 401 outputs the level signal of state H to the control terminal of the switching unit T3. See details. Figure 4 The waveform corresponding to Q3. Similarly, when the PWM signal is in the L (low level) state, the rising edge of the first shift pulse signal CPV after the L state is used to read the state of the PWM signal. Since it is L at this time, the first D flip-flop 401 outputs an L-state level signal to the control terminal of the switching unit T1. Based on this, when the rising edge of the next shift pulse of the shift pulse signal CPV arrives, the second D flip-flop 402 also outputs an L-state level signal to the control terminal of the switching unit T2, and so on. At the end, a clear signal is used to pull all the outputs of the D flip-flops to the control terminals of switching units T1, T2, and T3 to zero. This allows the PWM signal to be output in staggered shifts for each channel of the LED string driver chip 10, such as... Figure 5 As shown, within one cycle of PWM dimming, multiple channels of the LED string driver chip 10 can be distributed for phase dimming. Figure 5 In the diagram, out1 represents the waveform corresponding to channel out1, out2 represents the waveform corresponding to channel out2, and out3 represents the waveform corresponding to channel out3. Because the channels are open for the same duration but have different phases, their brightness is the same. However, this allows the LED strings of the corresponding channels to stagger their current supply within a cycle. Therefore, the current of the corresponding LED string driver chip 10 will not reach its peak simultaneously in a certain period of time, unlike in related technologies. Furthermore, the EMI energy in this frequency band is not as concentrated, and the noise can also be reduced.

[0048] In this embodiment, corresponding switching units are set between the channels of the LED string driver chip 10 and each group of LED strings. The shift module 40 receives the shift pulse signal CPV and control signal sent by the control module 20. The first D flip-flop 401, the second D flip-flop 402, and the third D flip-flop 403 shift the control signal at least once according to the shift pulse signal CPV and output it to the control terminal of the corresponding switching unit. This controls at least two switching units to turn on their corresponding LED string driver chip 10 channels at different times. The LED string driver chip 10 is used to dim the LED strings in the channel after the channel is turned on, allowing the LED strings to receive current at different times, thus enabling the LED string driver chip 10 to... The current in a given time period will not reach its peak simultaneously as in related technologies, and the EMI energy in that frequency band is not as concentrated, thus reducing noise. This solves the problem of excessive instantaneous current drawdown and severe overheating of the LED string driver chip 10 caused by the same PWM signal supplied to all LED string driver chips 10 for Mini-LED backlighting and the same current in each current channel of the same LED string driver chip 10. It also solves the problem of excessive EMI energy exceeding the standard in a certain frequency band, and the problem of instantaneous heat release and severe overheating caused by the same current flow time and light emission time between LED strings in related technologies. Furthermore, this application can also flexibly adjust the light emission time of each LED string corresponding to each channel of each LED string driver chip 10 by controlling the shift pulse signal CPV, achieving precise distributed phase control and further improving the dimming accuracy of the area.

[0049] In some embodiments, where there are multiple sets of LED strings in the display module, it is necessary to allocate the relative positions of the light-emitting channels and the light-emitting times of the LED strings on the respective channels in a corresponding manner. The following methods can be used to determine this.

[0050] The highest frequency at which the human eye can perceive the flicker of a light source is called the "critical flicker frequency." Above this frequency, the light appears as a continuous, stable sensation to the human eye. For most adults under normal conditions, this critical value is approximately between 50Hz and 60Hz. Therefore, the frequency of a single channel must be greater than or equal to 60Hz. Assuming the backlight frequency F is 60Hz, this means that the current of all channels needs to be supplied within 1 / 60Hz, or 16.667µs. Assuming the number of channels n is 30, the required emission time a for the desired brightness is 0.6µs. There are two possible scenarios.

[0051] The first scenario involves a short illumination time, i.e., 1 / (refresh rate). (Number of channels) ≥ emission time. That is, 1 / (F If n) ≥ a, then as Figure 8As shown, the emission time of each channel does not need to overlap, that is, the interval m between each channel is 1 / (refresh rate). (Number of channels) - Emission time = 1 / (F) n)-a.

[0052] That is, when the light emission times of the light strings corresponding to each channel of the light string driver chip 10 do not overlap, the shift pulse signal CPV needs to ensure that the light emission time interval between the light strings meets the following condition: m=1 / (F n)-a; where m represents the interval, F represents the refresh rate, n represents the number of channels connected to the LED string driver chip 10 and the LED string, and a represents the light emission time of the LED string corresponding to each channel.

[0053] The second type, if the emission time is relatively long, i.e. 1 / (F n) < a. For example, ... Figure 4 The emission times shown overlap. Assuming the overlap time is h, we have the formula 2a + (n-2)h = 1 / F. The overlap time h can be expressed as: h = (1 / F - 2a) / (n-2). And taking the example above where F is 60H, h = (1 / 60 - 2a) / (n-2). 0.0006) / (30-2) = 0.0005524us. Using this formula, the relative position time in various situations can be obtained.

[0054] That is, when the light emission times of the light strings corresponding to each channel of the light string driver chip 10 overlap, the shift pulse signal CPV needs to ensure that the light emission overlap time of each light string meets the following condition: h = (1 / F - 2a) / (n - 2); where m represents the interval, F represents the refresh rate, n represents the number of channels connected to the LED string driver chip 10 and the LED string, a represents the light emission time of the LED string corresponding to each channel, and h represents the light emission overlap time.

[0055] In some embodiments, for a given Mini-LED backlight (display module), the current of all channels corresponding to a single LED string driver chip 10 is the same, and the current of each LED string driver chip 10 can be controlled independently. This presents a limitation: the area of ​​the LED string corresponding to this LED string driver chip 10 can only emit light of uniform brightness, significantly restricting the dimming area. Therefore, the driving circuit of this application can control the dimming width of each channel, such as... Figure 9As shown, the shift register corresponding to Q1 reads the state of the PWM signal when the rising edge of the shift pulse signal CPV arrives. Therefore, by controlling the pulse width of the shift pulse signal CPV, the time of the rising edge in each cycle can be changed, thereby altering the width of Q1 / Q2 / Q3, which in turn changes the on-time of channels out1, out2, and out3. When the PWM signal is L, the pulse width of the shift pulse signal CPV is changed, and Q1 becomes L. At the next rising edge of the shift pulse signal CPV, the corresponding pulse width of the PWM signal decreases, and the state of L is read at the next rising edge. At this time, the pulse time t1 of Q1 is greater than the pulse time t2 of Q2. The brightness of the LED string in channel out1 will then be greater than the brightness of the LED string in channel out2, thus changing the illumination duration of each channel. Although the magnitude of the current in each channel cannot be changed, the brightness of the LED string corresponding to each channel can be changed by controlling the pulse width of the shift pulse signal CPV. For each channel of each LED string driver chip 10, the luminous intensity of the LED string corresponding to that channel can be adjusted by the waveform of the shift pulse signal CPV.

[0056] That is, the light emission time of each string of lights is positively correlated with the pulse width of the shift pulse signal CPV.

[0057] In some embodiments, the control module 20 is further configured to acquire the position information of the target light string, determine the target switching unit corresponding to the target light string based on the position information, and adjust the pulse width of the shift pulse segment in the shift pulse signal CPV corresponding to the target switching unit based on the target switching unit; wherein, the target light string is a light string whose luminous intensity is greater than or less than that of other light strings. The control module is also configured to acquire the position information of the target light string, acquire the target channel on the light string driver chip corresponding to the target light string based on the position information, and determine the target switching unit corresponding to the target light string through the target channel.

[0058] In some embodiments, the timing of adjusting the pulse width of each channel can be adjusted according to the brightness required by the data, thereby improving the contrast based on the working principle of Mini-LED. Because all channels corresponding to a single LED string driver chip 10 have the same current, areas with the same display current in a block have the same brightness. Figure 10As shown in the left figure, a jagged edge appears at the junction. Using the technical solution of this application, the target light string that needs adjustment is first identified. Then, the position information of the target light string is determined based on the target light string. Furthermore, based on the preset relationship between position and channel, the target channel on the light string driver chip corresponding to the target light string is obtained based on the position information. The control module 20 can then determine the target switching unit corresponding to the target light string through the target channel based on this information; adjust the pulse width of the shift pulse segment in the shift pulse signal CPV corresponding to the target switching unit according to the target switching unit. Then, after the shift pulse signal CPV is input to the shift module 40, the target light string emits light accordingly, thus adjusting the edge area from... Figure 10 The left side transitions smoothly as follows: Figure 10 As shown on the right, the adjustment range has changed from a block controlled by the LED string driver chip 10 to a string controlled by a channel, allowing for more precise adjustment. That is, the target LED string here is... Figure 10 The string of lights corresponding to the gray area on the right.

[0059] like Figure 10 In this configuration, each block can correspond to one LED driver chip and four LED strings. Each LED string corresponds to one channel. For example... Figure 10 As shown in the left figure, all channels corresponding to a single LED string driver chip 10 have the same current, so areas with the same display current have the same brightness, but jagged edges appear at the junctions. In this application, considering that each LED string and channel is connected and disconnected via a switching unit, individual control is possible. Based on this, it can be determined whether the edges of the graphic corresponding to the block to be lit will exhibit jagged or uneven shapes. If so, the block corresponding to the graphic edge is identified. Furthermore, the numbers of the target LED strings that need adjustment within these blocks (these numbers represent the position information of the LED strings) are obtained. Based on these numbers, the corresponding switching unit can be determined, and the pulse width of the shift pulse segment in the shift pulse signal CPV corresponding to the target switching unit can be adjusted to control the connection duration of that switching unit, thereby controlling the brightness of its corresponding LED string.

[0060] See Figure 11 , Figure 11 This is a schematic diagram of an embodiment of the display module provided in this application. The display module 200 includes a backlight module 101 and a driving circuit 102.

[0061] In some embodiments, the display module 200 can be a mini direct display.

[0062] In some embodiments, the display module 200 may include a backlight module 101, a driving circuit 102, and a display panel.

[0063] In some embodiments, the display module 200 includes a backlight module, a display device, and a display panel.

[0064] See Figure 12 , Figure 12 This is a schematic diagram of an embodiment of the display device provided in this application. The display device 300 includes a display module 200. The display module 200 is as described in any of the above embodiments.

[0065] See Figure 13 , Figure 13 This is a flowchart illustrating an embodiment of the driving method for a backlight module provided in this application. The method, applicable to the driving circuit of any of the above embodiments, includes: Step 131: The control module 20 sends a shift pulse signal CPV and a control signal to the shift module 40, so that the shift module 40 shifts the control signal at least once according to the shift pulse signal CPV and outputs it to the control terminal of the corresponding switching unit.

[0066] Step 132: Control at least two switching units to turn on the channels of their corresponding LED string driver chip 10 at different times.

[0067] Step 133: After the channel is turned on, the LED string driver chip 10 dims the LED strings in the channel.

[0068] The specific technical solutions for steps 131 to 133 can be found in other embodiments of this application, and will not be repeated here.

[0069] In summary, the backlight module driving circuit and method, display module, and display device provided in this application include a corresponding switching unit between the channel of the LED string driver chip 10 and each LED string, and a shift module 40 receiving the shift pulse signal CPV and control signal sent by the control module 20. The shift module 40 shifts the control signal at least once according to the shift pulse signal CPV and outputs it to the control terminal of the corresponding switching unit to control at least two switching units to turn on the channel of their corresponding LED string driver chip 10 at different times. The LED string driver chip 10 is used to dim the LED strings in the channel after the channel is turned on, allowing the LED strings to receive current in staggered shifts, thus enabling the LED string driver chip 10 to dim the LED strings in the channel. The current at any given time will not reach its peak simultaneously as in related technologies, and the EMI energy in that frequency band is not as concentrated, thus reducing noise. This solves the problem of excessive instantaneous current drawdown and severe overheating of the LED string driver chip 10 caused by the same PWM signal supplied to all LED string driver chips 10 for Mini-LED backlighting and the same current in each current channel of the same LED string driver chip 10. It also solves the problem of excessive EMI energy exceeding the standard in a certain frequency band, and the problem of instantaneous heat release and severe overheating caused by the same current flow time and light emission time between LED strings in related technologies. Furthermore, this application can also flexibly adjust the light emission time of each LED string corresponding to each channel of each LED string driver chip 10 by controlling the shift pulse signal CPV, achieving precise distributed phase control and further improving the dimming accuracy of the area.

[0070] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of circuits or units is merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0071] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0072] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0073] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A driving circuit for a display module, characterized in that, The display module includes at least two sets of LED strings, each set of LED strings being connected to a voltage source; the driving circuit includes: LED string driver chip; The control module is used to generate control signals and shift pulse signals; A switch module, comprising at least two switch units, wherein the first end of the at least two switch units is connected to at least two channels of the LED string driver chip in a one-to-one correspondence, and the second end of the at least two switch units is connected to at least two sets of LED strings in a one-to-one correspondence. A shift module is provided, which is connected to the control terminals of the at least two switching units one by one, and is also connected to the control module. The shift module is used to receive the shift pulse signal and the control signal, shift the control signal at least once according to the shift pulse signal, and output it to the control terminal of the corresponding switching unit to control the at least two switching units to turn on the channels of their corresponding LED string driver chips at different times. The LED string driver chip is used to dim the LED strings in the channel after the channel is turned on.

2. The driving circuit according to claim 1, characterized in that, The shift module includes at least two shift registers connected in sequence; the output terminals of the at least two shift registers are connected one-to-one with the control terminals of the at least two switching units, and each shift register is used to receive the shift pulse signal, shift the input control signal, and output it to the control terminal of its corresponding switching unit.

3. The driving circuit according to claim 2, characterized in that, The at least two shift registers are at least two D flip-flops; the outputs of the at least two D flip-flops are connected one-to-one with the control terminals of the at least two switching units. Wherein, the data input terminal of the first D flip-flop of the at least two D flip-flops is used to receive the control signal, the clock input terminal of each D flip-flop is used to receive the shift pulse signal, and the non-inverting output terminal of each D flip-flop is connected to the data input terminal of the next adjacent D flip-flop and the control terminal of the corresponding switching unit.

4. The driving circuit according to any one of claims 1-3, characterized in that, When the light emission times of the light strings corresponding to each channel of the light string driver chip do not overlap, the shift pulse signal needs to ensure that the light emission time interval between the light strings meets the following condition: m=1 / (F n)-a; where m represents the interval, F represents the refresh rate, n represents the number of channels connected to the LED string driver chip and the LED string, and a represents the light emission time of the LED string corresponding to each channel.

5. The driving circuit according to any one of claims 1-3, characterized in that, When the light emission times of the light strings corresponding to each channel of the light string driver chip overlap, the shift pulse signal needs to ensure that the light emission overlap time of each light string meets the following condition: h = (1 / F - 2a) / (n - 2); where m represents the interval, F represents the refresh rate, n represents the number of channels connected to the LED string driver chip and the LED string, a represents the light emission time of the LED string corresponding to each channel, and h represents the light emission overlap time.

6. The driving circuit according to any one of claims 1-3, characterized in that, The illumination time of each light string is positively correlated with the pulse width of the shift pulse signal.

7. The driving circuit according to claim 6, characterized in that, The control module is also used to acquire the position information of the target light string, determine the target switch unit corresponding to the target light string based on the position information, and adjust the pulse width of the shift pulse segment in the shift pulse signal corresponding to the target switch unit based on the target switch unit; wherein, the target light string is a light string whose luminous brightness is greater than or less than that of other light strings.

8. The driving circuit according to claim 7, characterized in that, The control module is also used to acquire the position information of the target light string, acquire the target channel on the light string driver chip corresponding to the target light string based on the position information, and determine the target switch unit corresponding to the target light string through the target channel.

9. A display module, characterized in that, The display module includes the driving circuit as described in any one of claims 1-7.

10. A driving method for a display module, the display module comprising at least two sets of LED strings, each set of LED strings being connected to a voltage source; characterized in that, The method is applied to a driving circuit, which includes: a string light driver chip, a control module, a switching module, and a shifting module. The control module sends a shift pulse signal and a control signal to the shift module, so that the shift module shifts the control signal at least once according to the shift pulse signal and outputs it to the control terminal of the corresponding switch unit in the switch module; The switch module controls different switch units to turn on the corresponding channels of the LED string driver chip at different times; After the channel is turned on, the LED string driver chip dims the LED string in the channel.

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