Backlight driving circuit, chip, backlight module and electronic device

Abstract

This application provides a backlight driving circuit, a chip, a backlight module, and an electronic device, relating to the field of display technology, which can reduce the losses of the backlight driving circuit. The backlight driving circuit is applied to a backlight module, wherein at least one backlight string is arranged on the lamp board of the backlight module; a first terminal of a current source is coupled to the cathode of the backlight string, and the anode of the backlight string is coupled to a power supply; a second terminal of the current source is coupled to ground; a control circuit is configured to detect the electrical signal of the first terminal or the control terminal of the current source; and output a control signal to the driving circuit according to the electrical signal; the driving circuit is configured to adjust the current flowing through the first and second terminals of the current source, and the voltage of the first terminal of the current source, according to the control signal.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a backlight driving circuit, chip, backlight module and electronic device. Background Technology

[0002] Currently, the LCD display industry uses backlight modules to provide backlighting for LCD panels. The mainstream backlight solutions include global dimming and local dimming (or local dimming / control) technology. With the evolution of backlight technology, mini light-emitting diodes (MLEDs) are widely used in backlight panels as the light-emitting units of LED strings. Especially in local dimming technology, the switching and brightness adjustment of corresponding backlight areas can be controlled in real time according to the brightness and darkness of different parts of the screen, making blacks deeper, whites whiter, and colors more natural and vibrant, providing a more immersive and realistic visual experience. Mini LED backlight solutions typically use multiple channels (CH, usually each channel corresponds to a backlight string (including multiple LEDs connected in series), and the backlight driver circuit drives many LEDs by providing current to each channel to drive the corresponding backlight string to emit light), resulting in higher power levels. Larger screen sizes mean higher brightness and more backlight channels to meet standards such as High Dynamic Range 600 (HDR600), HDR1000, and HDR Vivid. Ultimately, backlight power levels also increase, typically reaching several hundred watts in a television. Considering power conversion efficiency, power loss is not negligible.

[0003] However, the relationship between the forward voltage (VF) and current of an LED is that the higher the voltage, the larger the current. For the same forward current, the VF of an LED will vary due to differences in manufacturing process and materials. Thus, due to variations in LED manufacturing processes, the VF of an LED will ultimately differ, resulting in different voltages for each channel (typically the channel voltage V). CHx The anode voltage Vout of the backlight string and the voltage drop V of the string are given. LS The difference between the sum of the voltage values ​​(VF) of the LEDs connected in series in the string and the difference between the sum of the voltage values ​​(VF) of the LEDs in each channel is also different. Because the VF of each LED in a channel is different, the voltage values ​​will differ even when the same current I flows through them. LED Below, the total forward conduction voltage (i.e., V) of the backlight string connected to each channel. LS The differences in voltage (V) across different channels result in different voltage levels (V) across each channel. CHx They are also different. Thus, when the voltage V of a certain channel... CHxHigher voltage levels will increase the losses in the backlight driver circuit. Furthermore, because mini LED backlights use multiple channels, to save board layout area, the current sources (usually metal-oxide-semiconductor field-effect transistors, MOSFETs) that supply current to the backlight strings on each channel are typically integrated into a single chip along with the current source's driver circuitry. Therefore, this loss is released as heat on the chip, leading to chip overheating and, in severe cases, chip damage. Summary of the Invention

[0004] Embodiments of this application provide a backlight driving circuit, a chip, a backlight module, and an electronic device, which can reduce the loss of the backlight driving circuit.

[0005] In a first aspect, a backlight driving circuit is provided. This backlight driving circuit is applied to a backlight module, the backlight module having at least one backlight string on its lamp board, the backlight string including at least one series-connected light-emitting unit; the backlight driving circuit includes: a control circuit, at least one driving circuit, and at least one current source. A first terminal of the current source is coupled to the cathode of the backlight string, and the anode of the backlight string is coupled to a power supply; a second terminal of the current source is coupled to ground; the driving circuit is coupled to a control terminal of the current source; the control circuit is coupled to the driving circuit, and is also coupled to the first terminal or the control terminal of the current source; the control circuit is configured to detect an electrical signal at the first terminal or the control terminal of the current source; the control circuit is further configured to output a control signal to the driving circuit based on the electrical signal; the driving circuit is configured to adjust the current flowing through the first and second terminals of the current source, and the voltage at the first terminal of the current source, based on the control signal. In this way, the current flowing through the first and second terminals of the current source, as well as the voltage at the first terminal, can be dynamically adjusted by detecting the electrical signal at the first terminal or the control terminal of the current source, thus avoiding excessive losses when the current source supplies current to its corresponding backlight string.

[0006] In one possible implementation, the driving circuit includes an operational amplifier and a first switch; the current source includes a driving transistor and a first resistor; a first terminal of the driving transistor is coupled to a first terminal of the current source, a second terminal of the driving transistor is coupled to a second terminal of the current source through the first resistor, and a control terminal of the driving transistor is coupled to a control terminal of the current source; the positive input terminal of the operational amplifier is coupled to the control circuit, and the negative input terminal of the operational amplifier is coupled to the second terminal of the driving transistor; the output terminal of the operational amplifier is coupled to a first terminal of the first switch, and the second terminal of the first switch is coupled to the control terminal of the driving transistor; the control signal includes a voltage signal and a switch control signal; the positive input terminal of the operational amplifier is configured to receive the voltage signal, and the control terminal of the first switch is configured to receive the switch control signal; wherein, when the switch control signal turns on the first switch, the voltage signal is used to control the current flowing through the first and second terminals of the driving transistor, and the switch control signal is used to control the voltage at the first terminal of the driving transistor.

[0007] In one possible implementation, if the control circuit determines that the voltage corresponding to the electrical signal is greater than a first threshold, the control circuit controls the drive circuit to increase the current flowing through the first and second terminals of the current source and decrease the voltage at the first terminal of the current source via a control signal. Thus, when the control circuit determines that the voltage corresponding to the first terminal or control terminal of a current source is greater than the threshold based on the electrical signal, it indicates that the voltage at the first terminal of the current source is too high, meaning that the current source is generating excessive losses when supplying current to its corresponding backlight string. If the voltage at the first terminal of the current source is directly reduced by decreasing the current, it may not guarantee that the backlight string connected to the current source will emit light normally. Therefore, in this application, the control circuit determines that the electrical signal is greater than the first threshold, and controls the drive circuit to increase the current flowing through the first and second terminals of the current source and decrease the voltage at the first terminal of the current source via a control signal. This ensures that the backlight string emits light normally, and by reducing the voltage at the first terminal of the current source, the losses generated by the current source are also reduced, thereby reducing the overall losses of the backlight drive circuit.

[0008] In one possible implementation, the control circuit determines that the voltage corresponding to the electrical signal is less than a second threshold. The control circuit then controls the drive circuit via a control signal to reduce the current flowing through the first and second terminals of the current source and increase the voltage at the first terminal of the current source. Thus, this application also provides an application scenario where there is a need to increase the voltage at the first terminal of the current source while reducing the current flowing through the first and second terminals. It should be noted that when the control circuit adjusts (decreases or increases) the voltage at the first terminal of the current source, it can do so in steps of varying sizes. Different step sizes can be set depending on the application scenario; for example, a smaller step size can be set for low-power mobile phones, while a larger step size can be set for high-power large-screen devices, in order to ensure adjustment accuracy while shortening the voltage adjustment time.

[0009] In one possible implementation, the system further includes: a bandgap reference source connected between the driving circuit and the control circuit; the bandgap reference source is configured to adjust the voltage signal according to a predetermined ratio. Thus, when controlling the current of the backlight string, since the bandgap reference source can adjust the voltage signal according to a predetermined ratio, a smaller current accuracy can be achieved, thereby enabling more precise backlight brightness adjustment.

[0010] In one possible implementation, the first switch includes: a first transistor and a second transistor; a first terminal of the first transistor is coupled to ground, a second terminal of the first transistor is coupled to a control terminal of the second transistor, and the control terminal of the first transistor is coupled to a control circuit; a first terminal of the second transistor is coupled to the output terminal of an operational amplifier, a second terminal of the second transistor is coupled to the control terminal of a driving transistor, and the control terminal of the second transistor is also coupled to the output terminal of the operational amplifier through a second resistor; the first transistor is configured to periodically turn on its first and second terminals under the control of a switch control signal; the second transistor is configured to turn on its first and second terminals when the first and second terminals of the first transistor are turned on, so as to transmit the signal from the output terminal of the operational amplifier to the control terminal of the driving transistor. This scheme provides a specific implementation of the first switch; of course, it is understood that the first switch can also take other forms.

[0011] In one possible implementation, the first transistor includes an N-type transistor, and the second transistor includes a P-type transistor. The first terminal of the first transistor is the source of the N-type transistor; the second terminal of the first transistor is the drain of the N-type transistor, and the control terminal of the first transistor is the gate of the N-type transistor. The first terminal of the second transistor is the source of the P-type transistor; the second terminal of the second transistor is the drain of the P-type transistor, and the control terminal of the second transistor is the gate of the P-type transistor. Thus, when the N-type transistor is turned on, current flows from the drain (d) to the source (s), and when the P-type transistor is turned on, current flows from the source (s) to the drain (d). Furthermore, the source (s) of the N-type transistor is connected to ground (GND) at a fixed voltage, which facilitates circuit design. When the N-type transistor is turned on, the second resistor provides a fixed voltage difference between the source (s) and gate (g) of the P-type transistor. As long as the voltage at the source (s) is greater than that at the gate (g), and the conduction threshold condition is met, Q13 can be turned on.

[0012] In one possible implementation, the system further includes: at least one comparator and a reference voltage generation circuit; the positive input of the comparator is coupled to a first terminal of the current source or a control terminal of the current source, and the negative input of the comparator is coupled to the reference voltage generation circuit; the output of the comparator is coupled to a control circuit; the reference voltage generation circuit is configured to generate a first reference voltage; the comparator is configured to compare the voltage at the first terminal of the current source with the first reference voltage, or to compare the voltage at the control terminal of the current source with the first reference voltage, and output a comparison result at the output of the comparator; the control circuit is configured to determine the electrical signal at the first terminal of the current source or the control terminal of the current source based on the comparison result. Thus, the control circuit can detect the signal at the first terminal or the control terminal of the current source in the digital domain.

[0013] In one possible implementation, the system further includes: a selector comprising multiple input terminals, an output terminal, and at least one control terminal; a first terminal or control terminal of the current source coupled to an input terminal of the selector; an output terminal of the selector coupled to a control circuit; and at least one control terminal of the selector coupled to the control circuit; the control circuit is configured to output a gating control signal to the selector via at least one control terminal of the selector; and the selector is configured to connect any input terminal of the selector to its output terminal according to the gating control signal. In some scenarios, each sub-lamp board of the backlight module needs to provide 16, 32, 48, or even more channels of backlight LED string. When the control circuit cannot provide the corresponding number of ports to detect the electrical signal of the first terminal or control terminal of the current source as described above, due to limitations in the number of ports provided by the control circuit, this possible implementation can be used. This allows for time-division detection of the electrical signal of the first terminal of each current source, reducing the complexity of the control circuit.

[0014] Secondly, a chip is provided for use in a backlight module, wherein at least one backlight string is disposed on the lamp board of the backlight module, the backlight string including at least one light-emitting unit connected in series; the chip includes: at least one driving circuit and at least one current source; a first terminal of the current source is coupled to the cathode of the backlight string, and the anode of the backlight string is coupled to a power supply; a second terminal of the current source is coupled to ground; the driving circuit is coupled to a control terminal of the current source; the driving circuit is also coupled to a control circuit; the first terminal of the current source or the control terminal of the current source is also coupled to the control circuit; the control circuit is configured to detect an electrical signal at the first terminal of the current source or the control terminal of the current source; the control circuit is also configured to output a control signal to the driving circuit according to the electrical signal; the driving circuit is configured to adjust the current flowing through the first terminal and the second terminal of the current source, and the voltage at the first terminal of the current source, according to the control signal.

[0015] In one possible implementation, the driving circuit includes an operational amplifier and a first switch; the current source includes a driving transistor and a first resistor; a first terminal of the driving transistor is coupled to a first terminal of the current source, a second terminal of the driving transistor is coupled to a second terminal of the current source through the first resistor, and a control terminal of the driving transistor is coupled to a control terminal of the current source; the positive input terminal of the operational amplifier is coupled to the control circuit, and the negative input terminal of the operational amplifier is coupled to the second terminal of the driving transistor; the output terminal of the operational amplifier is coupled to a first terminal of the first switch, and the second terminal of the first switch is coupled to the control terminal of the driving transistor; the control signal includes a voltage signal and a switch control signal; the positive input terminal of the operational amplifier is configured to receive the voltage signal, and the control terminal of the first switch is configured to receive the switch control signal; wherein, when the switch control signal turns on the first switch, the voltage signal is used to control the current flowing through the first and second terminals of the driving transistor, and the switch control signal is used to control the voltage at the first terminal of the driving transistor.

[0016] In one possible implementation, if the control circuit determines that the voltage corresponding to the electrical signal is greater than a first threshold, the control circuit controls the drive circuit to increase the current flowing through the first and second terminals of the current source and decrease the voltage at the first terminal of the current source by controlling the control signal.

[0017] In one possible implementation, if the control circuit determines that the voltage corresponding to the electrical signal is greater than a second threshold, the control circuit controls the drive circuit to reduce the current flowing through the first and second terminals of the current source and increase the voltage at the first terminal of the current source by controlling the control signal.

[0018] In one possible implementation, it further includes: a bandgap reference source connected between the positive input of the operational amplifier and the control circuit; the bandgap reference source being configured to adjust the voltage signal according to a predetermined ratio.

[0019] In one possible implementation, the first switch includes: a first transistor and a second transistor; a first terminal of the first transistor is coupled to ground, a second terminal of the first transistor is coupled to a control terminal of the second transistor, and the control terminal of the first transistor is coupled to a control circuit; a first terminal of the second transistor is coupled to the output terminal of an operational amplifier, a second terminal of the second transistor is coupled to the control terminal of a driving transistor, and the control terminal of the second transistor is also coupled to the output terminal of the operational amplifier through a second resistor; the first transistor is configured to periodically turn on its first and second terminals under the control of a switch control signal; the second transistor is configured to turn on its first and second terminals when the first and second terminals of the first transistor are turned on, so as to transmit the signal from the output terminal of the operational amplifier to the control terminal of the driving transistor.

[0020] In one possible implementation, the first transistor includes an N-type transistor, and the second transistor includes a P-type transistor; the first terminal of the first transistor is the source of the N-type transistor; the second terminal of the first transistor is the drain of the N-type transistor, and the control terminal of the first transistor is the gate of the N-type transistor; the first terminal of the second transistor is the source of the P-type transistor; the second terminal of the second transistor is the drain of the P-type transistor, and the control terminal of the second transistor is the gate of the P-type transistor.

[0021] In one possible implementation, the system further includes: at least one comparator and a reference voltage generation circuit; the positive input of the comparator is coupled to a first terminal of the current source or a control terminal of the current source, and the inverting input of the comparator is coupled to the reference voltage generation circuit; the output of the comparator is coupled to a control circuit; the reference voltage generation circuit is configured to generate a first reference voltage; the comparator is configured to compare the voltage at the first terminal of the current source with the first reference voltage, or to compare the voltage at the control terminal of the current source with the first reference voltage, and to output a comparison result at the output of the comparator; the control circuit is configured to determine an electrical signal at the first terminal of the current source or the control terminal of the current source based on the comparison result.

[0022] In one possible implementation, the system further includes: a selector, wherein the selector includes a plurality of input terminals, an output terminal, and at least one control terminal; a first terminal of the current source or a control terminal of the current source is coupled to an input terminal of the selector; an output terminal of the selector is coupled to a control circuit; and at least one control terminal of the selector is coupled to the control circuit; the control circuit is configured to output a gating control signal to the selector through at least one control terminal of the selector; and the selector is configured to connect any input terminal of the selector to the output terminal of the selector according to the gating control signal.

[0023] In one possible implementation, the control circuitry is contained within the chip.

[0024] Thirdly, a backlight module is provided, which includes a backplate, a flat plate, a lamp board, and a diffuser plate; wherein the flat plate is located between the backplate and the lamp board, and the lamp board is located between the flat plate and the diffuser plate; at least one backlight string is provided on the lamp board, and the backplate is provided with the aforementioned backlight driving circuit or the aforementioned chip.

[0025] Fourthly, an electronic device is provided, including the aforementioned backlight module and a liquid crystal panel disposed on the backlight module.

[0026] The technical effects achieved by the second, third, and fourth aspects can be referred to the description in the first aspect or any possible implementation method, and will not be repeated here. Attached Figure Description

[0027] Figure 1 A schematic diagram of the overall structure of an electronic device provided for an embodiment of this application;

[0028] Figure 2 An exploded view of a screen assembly provided for an embodiment of this application;

[0029] Figure 3 A schematic diagram of the structure of a sub-lamp panel provided for an embodiment of this application;

[0030] Figure 4 A schematic diagram of the structure of a sub-lamp panel is provided for another embodiment of this application;

[0031] Figure 5 A schematic diagram of the structure of a connector provided for an embodiment of this application;

[0032] Figure 6 A schematic diagram of the connection structure between a control module and a connector provided for an embodiment of this application;

[0033] Figure 7 A schematic diagram of a backlight driving circuit provided for an embodiment of this application;

[0034] Figure 8 A schematic diagram of a backlight driving circuit provided for an embodiment of this application;

[0035] Figure 9 A partial structural schematic diagram of a backlight driving circuit provided for an embodiment of this application;

[0036] Figure 10 A schematic diagram of the current and voltage curves of an LED provided for an embodiment of this application;

[0037] Figure 11 A schematic diagram of a backlight driving circuit provided for another embodiment of this application;

[0038] Figure 12 A schematic diagram of a backlight driving circuit provided in another embodiment of this application;

[0039] Figure 13 A partial structural schematic diagram of a backlight driving circuit provided for another embodiment of this application;

[0040] Figure 14 A partial structural schematic diagram of a backlight driving circuit provided for another embodiment of this application;

[0041] Figure 15 A schematic diagram of a backlight driving circuit provided in another embodiment of this application;

[0042] Figure 16 A schematic diagram of a backlight driving circuit provided for another embodiment of this application;

[0043] Figure 17 A partial structural schematic diagram of a backlight driving circuit provided for another embodiment of this application;

[0044] Figure 18 A schematic diagram of a backlight driving circuit provided in another embodiment of this application;

[0045] Figure 19 A schematic diagram of a backlight driving circuit provided in another embodiment of this application;

[0046] Figure 20 A schematic diagram of a backlight driving circuit provided for another embodiment of this application;

[0047] Figure 21 A schematic diagram of a backlight driving circuit provided in another embodiment of this application;

[0048] Figure 22 A schematic diagram of a backlight driving circuit provided in another embodiment of this application;

[0049] Figure 23 A schematic diagram of a chip provided for an embodiment of this application;

[0050] Figure 24 This is a schematic diagram of a chip provided for another embodiment of this application. Detailed Implementation

[0051] The technical solutions in some embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application are within the scope of protection of this application.

[0052] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific example," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this application. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0053] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this application, unless otherwise stated, "multiple" means two or more. Furthermore, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0054] In the description of this application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0055] The transistors provided in the embodiments of this application can be metal-oxide-semiconductor field-effect transistors (MOSFETs). In the embodiments of this application, transistors are classified into two types: N-type transistors and P-type transistors. A transistor includes a source, a drain, and a gate. By controlling the level of the input gate, the transistor can be controlled to be turned on (open) or off (closed, cut off, or open-circuited). When the transistor is on, the source and drain conduct, generating an on-state current. Furthermore, the magnitude of the on-state current generated between the source and drain varies depending on the gate level. When the transistor is off, the source and drain do not conduct, and no current is generated. In the embodiments of this application, the gate of the transistor is also referred to as the control terminal, the source as the first terminal, and the drain as the second terminal; or, the gate is referred to as the control terminal, the drain as the first terminal, and the source as the second terminal. Furthermore, an N-type transistor turns on when the control terminal is high, with both terminals conducting and generating an on-state current between them; when the control terminal is low, the N-type transistor turns off, with neither terminal conducting and no current generated. A P-type transistor turns on when the control terminal is low, with both terminals conducting and generating an on-state current; when the control terminal is high, the P-type transistor turns off, with neither terminal conducting and no current generated. The transistors used in the switches in the following schemes can all be referenced to this description.

[0056] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0057] Figure 1 This is a schematic diagram of the structure of an electronic device 100 provided in an embodiment of this application. The electronic device 100 can be a screen-based electronic device such as an advertising screen (billboard), monitor, television (TV, such as a smart screen), laptop computer, tablet computer, or in-vehicle device. Optionally, in some scenarios, the electronic device 100 can be a mobile phone, e-reader, or wearable device. Figure 1 The illustrated embodiment uses a television as an example of an electronic device 100.

[0058] Electronic device 100 may include housing 110 and screen assembly 200.

[0059] The housing 110 may include a frame and a back cover. The frame may surround the periphery of the back cover. The housing 110 may, for example, include the mid-frame of the electronic device 100. In one example, the mid-frame of the electronic device 100 may be housed within the inner periphery of the frame. In another example, the mid-frame of the electronic device 100 may serve as the frame of the housing 110. The screen assembly 200 may be a component that provides display functionality for the electronic device 100. Users can view the screen assembly 200 to enjoy media resources such as images and videos. The screen assembly 200 may be mounted on the housing 110. The periphery of the screen assembly 200 may abut against the inner edge of the frame. The frame may secure the screen assembly 200 to the housing 110. The screen assembly 200 and the back cover may be mounted on opposite sides of the frame, such that the housing 110 provides mechanical protection for the components inside the electronic device, especially the components on the screen assembly 200. The screen assembly 200 may, for example, be secured to the mid-frame of the electronic device 100.

[0060] The electronic device 100 may also include a control module. Specific implementations of the control module may include, for example, a processor, controller, connector, driver board, integrated circuit, chip, power supply, etc. In embodiments of this application, the control module may specifically include a backlight driving circuit, which may be in chip form or integrated into a driver board, etc. Furthermore, in embodiments of this application, it may specifically include a power supply, and one or more of the control circuit, driving circuit, and current source in the backlight driving circuit. The screen assembly 200 may, for example, be configured with a control module, which may be housed within the housing 110. In one example, the control module may include at least one communication interface, a bus, at least one processor, and at least one memory. At least one communication interface, at least one processor, and at least one memory can communicate with each other via the bus. At least one communication interface can be used to receive and send signals. For example, the light-emitting unit of the screen assembly 200 can be connected to one of the communication interfaces, allowing the control module to trigger the light-emitting unit to emit light. At least one memory is used to store application code. The application code may, for example, include code that controls the light-emitting unit to emit light or not emit light. At least one processor can be used to execute the aforementioned application code to control the light-emitting unit. In this application, "at least one" includes, for example, one or more of the two cases.

[0061] The following is combined Figure 2 This paper describes the screen component 200 provided in the embodiments of this application. Figure 2 This is an exploded view of screen component 200. Within it... Figure 2 The screen assembly 200 shown includes a backlight module 210 and a liquid crystal panel 220 disposed on the light-emitting side of the backlight module 210. The backlight module 210 may include stacked components such as a backplate 211, a flat plate 212, a lamp plate 213, a diffuser plate 214, and an optical film 215. Of course, the above... Figure 2 The above is merely an example of a general structure for a backlight module 210. In some examples, the backlight module 210 may include more or fewer components than those described above.

[0062] The backplate 211 can have functions such as supporting the electronic device 100 and providing mechanical protection for the electronic components inside the electronic device 100. The material of the backplate 211 can be a material that meets mechanical strength requirements and can provide support. For example, the backplate 211 can be a metallic material such as stainless steel, aluminum alloy, zinc alloy, or titanium alloy. Alternatively, the backplate 211 can be a non-metallic material such as resin. The backplate 211 can include a first backplate end face and a second backplate end face, with the first backplate end face closer to the lamp panel 213 and the second backplate end face farther from the lamp panel 213. For the user, the first backplate end face can correspond to the front of the electronic device 100, and the second backplate end face can correspond to the back of the electronic device 100. The front of the electronic device 100 can be the side of the electronic device 100 that is frequently observed when the user uses the electronic device 100. The back of the electronic device 100 can be positioned opposite to the front of the electronic device 100, and the back of the electronic device 100 can be the side of the electronic device 100 that is not frequently observed when the user uses the electronic device 100. For example, electronic device 100 can be a television, and the side of the television with the screen assembly can be the front of the television; the side of the television with the back cover can be the back of the television. The first back panel end face corresponds to the front of electronic device 100, meaning that the first back panel end face can be observed when viewing the back panel 211 from the direction the user is viewing the front of electronic device 100. The second back panel end face corresponds to the back of electronic device 100, meaning that the second back panel end face can be observed when viewing the back panel 211 from the direction the user is viewing the back of electronic device 100. For ease of description, the first back panel end face can be referred to as the front of back panel 211, and the second back panel end face can be referred to as the back of back panel 211. In one possible example, the first back panel end face can be fixed to the back cover of housing 110. For example, the first back panel end face can be fixed to the back cover of housing 110 by mechanical fasteners such as screws, double-sided tape, or foam. In other possible examples, the back panel 211 can serve as the back cover of housing 110.

[0063] A flat plate 212 can be located between the light panel 213 and the back plate 211. The flat plate 212 provides support for the light panel 213 to maintain or ensure its flatness. The flat plate 212 can be a conductive material with a certain rigidity. For example, the flat plate 212 can be an aluminum plate. The flat plate 212 can be fixed to the back plate 211, for example, using mechanical connectors such as double-sided tape or foam. In one possible scenario, during the transportation of the electronic device 100, it may be bumped or dropped. In this case, the electronic device 100 can withstand a certain degree of external force. The back plate 211 can deform accordingly to resist this external force. If the light panel 213 is directly fixed to the back plate 211, the light panel 213 may deform relatively significantly along with the back plate 211. Avoiding the above situation would increase the difficulty of transporting the electronic device 100. If the back plate 211 deforms relatively significantly, it is detrimental to the display effect of the light panel 213. For example, due to the different mixing distances in different areas of the lamp panel 213, the electronic device 100 may experience display problems such as uneven brightness and ghosting. By placing the flat plate 212 between the back plate 211 and the lamp panel 213, the flat plate 212 can act as a transition between the lamp panel 213 and the back plate 211 in terms of deformation. The deformation of the flat plate 212 can be less than that of the back plate 211, thus reducing the deformation of the lamp panel 213. In other words, when the back plate 211 undergoes relatively significant deformation, the deformation of the lamp panel 213 can be kept as small or as inconspicuous as possible.

[0064] Optical film 215 can change the frequency of light from lamp panel 213. Optical film 215 may include quantum dots. For example, lamp panel 213 may emit high-energy blue light; the blue light can excite the quantum dots encapsulated in optical film 215, so that the quantum dots can convert the blue light emitted by lamp panel 213 into white light (quantum dots can be a nanoscale semiconductor; by applying a certain electric field or light pressure to quantum dots, quantum dots can emit light of a specific frequency). Quantum dots may be formed, for example, in a chemical coating or phosphor. In one possible example, light emitted from optical film 215 may enter liquid crystal panel 220. Liquid crystal panel 220 may include a liquid crystal layer and a light filter layer. The liquid crystal in the liquid crystal layer can control the liquid crystal cells to turn on or off, thereby controlling the intensity of white light passing through the liquid crystal cells. By turning on the liquid crystal cells, the white light passing through the liquid crystal cells can illuminate the light filter layer. The light filter layer may include a red light filter, a green light filter, and a blue light filter. The red light filter can be used to convert white light into red light. A green light filter can be used to convert white light into green light. A blue light filter can be used to convert white light into blue light. Thus, electronic device 100 can be controlled to emit light of multiple colors to display colored patterns.

[0065] In other examples, the diffuser 214 may include quantum dots, thus allowing the diffuser 214 to alter the frequency of light from the lamp panel 213. In some embodiments, the diffuser 214 may be integrally formed with the optical film 215. The light emitted from the lamp panel 213 may undergo only light mixing without further optical processing and directly enter the diffuser 214. That is, in some possible scenarios, quantum dots may not be configured on the light-emitting units of the lamp panel 213. This helps reduce the structural complexity of the lamp panel 213 and allows the light-emitting units to be arranged relatively closely on the lamp panel 213. For example, the size of the phosphor is typically larger than the size of the light-emitting units of the lamp panel 213; encapsulating the phosphor on the lamp panel 213 is not conducive to the close arrangement of the light-emitting units.

[0066] In some examples, the lamp panel 213 may also include multiple arrayed sub-lamp panels 2130. The following description uses one sub-lamp panel 2130 as an example. The sub-lamp panel 2130 may include a first lamp panel end face 2131 and a second lamp panel end face 2132. Figure 3 This is a schematic structural diagram of the first lamp plate end face 2131 of a sub-lamp plate 2130 provided in an embodiment of this application. Light emitted from the sub-lamp plate 2130 can be emitted from the first lamp plate end face 2131 of the sub-lamp plate 2130. The first lamp plate end face 2131 of the sub-lamp plate 2130 can be the surface of the sub-lamp plate 2130 that is close to the diffuser plate 214 and away from the back plate 211. The following is in conjunction with... Figure 3 This section describes the structure of the first lamp board end face 2131 of the sub-lamp board 2130. The sub-lamp board 2130 may include multiple light-emitting units 2133. For example, the sub-lamp board 2130 may include multiple light-emitting units 2133 arranged in an array. The light-emitting unit 2133 may be, for example, a chip with light-emitting function. The light-emitting unit 2133 may also be a light-emitting diode (LED), wherein several light-emitting units located in the same column or row can be connected to form a backlight string. Figure 4 This is a schematic structural diagram of the second lamp plate end face 2132 of a sub-lamp plate 2130 provided in an embodiment of this application. The second lamp plate end face 2132 of the sub-lamp plate 2130 can be disposed close to the back plate 211 and away from the diffuser plate 214. The following is in conjunction with... Figure 4 The structure of the second lamp board end face 2132 of the sub-lamp board 2130 is described. The second lamp board end face 2132 of the sub-lamp board 2130 may be provided with double-sided adhesive, which can fix the sub-lamp board 2130 to the flat plate 212. In one possible example, the double-sided adhesive can be thermally conductive adhesive 2134. Since the sub-lamp board 2130 may generate relatively high heat during operation, the thermally conductive adhesive 2134 helps to transfer the heat of the sub-lamp board 2130 to the flat plate 212, thereby improving the heat dissipation of the electronic device 100.

[0067] The second lamp board end face 2132 of the sub-lamp board 2130 may also be provided with a conductive spring 2135. One end of the conductive spring 2135 can be electrically connected to the sub-lamp board 2130. The other end of the conductive spring 2135 can abut against the flat plate 212. When the sub-lamp board 2130 is working, the light-emitting unit 2133 of the sub-lamp board 2130 can accumulate charge. The conductive spring 2135 can ground the sub-lamp board 2130, which is beneficial to improving the electromagnetic compatibility (EMC) of the electronic device 100.

[0068] The sub-lamp board 2130 may further include one or more backlight driving circuits 2136 and one or more connectors 2137. Through the connectors 2137, signals related to the sub-lamp board 2130 can be input to the backlight driving circuit 2136 to control the backlight driving circuit 2136 to provide current to the light-emitting unit 2133, thereby controlling the brightness state of the light-emitting unit 2133. This allows the backlight driving circuit 2136 to control the brightness state of the light-emitting unit 2133 according to the control signals. Specifically, when the light-emitting unit 2133 is in a bright state, it can be driven by the backlight driving circuit 2136. Optionally, when the light-emitting unit 2133 is in a bright state, its brightness is adjustable. When the light-emitting unit 2133 is in a dim state, it can be turned off by the backlight driving circuit 2136 (i.e., the light-emitting unit 2133 may not be driven).

[0069] like Figure 5 As shown in the partially enlarged view of connector 2137, in one example, connector 2137 may include multiple connector ports P (also called pins). For example, connector 2137 may include 30 to 100 connector ports P. Correspondingly, backlight driving circuit 2136 may include multiple signal input ports corresponding to the multiple connector ports. The multiple connector ports and multiple signal input ports can be electrically connected in a one-to-one, one-to-many, or many-to-one manner. Connector ports P can be used to transmit signals related to sub-lamp board 2130. Of course, when backlight driving circuit 2136 is provided in the control module described above, current of light-emitting unit 2133 can also be directly transmitted to sub-lamp board 2130 through connector ports P. Backlight driving circuit 2136 can be used to drive a backlight string formed by connecting one or more light-emitting units 2133 of sub-lamp board 2130 in series, and to control the light emission of each light-emitting unit 2133 of sub-lamp board 2130. For example, the backlight driving circuit 2136 can turn off one or more light-emitting units 2133 connected in series in a backlight string, and control the brightness of one or more light-emitting units 2133 connected in series in a backlight string, etc. Of course, Figure 6This is just one example. In some solutions, it is not limited to placing all of the backlight driving circuit 2136 on the sub-lamp board 2130, or placing some of the structures or modules of the backlight driving circuit 2136 on the sub-lamp board 2130, or placing all of the backlight driving circuit 2136 on the control module 217.

[0070] In one example, control module 217 may include Figure 7 The power supply 31 and backlight driving circuit 32 are shown. The power supply 31 can be a switching circuit, such as... Figure 7 As shown, the input port Vin of power supply 31 can be coupled to a battery or an external adapter to provide input voltage to the switching circuit; the output port Vout of power supply 31 can be coupled to the anode of each lamp string to provide output voltage to each lamp string. Specifically, the switching circuit is used to step down or step up the input voltage of power supply 31 and output the output voltage to the output port Vout. For example, the switching circuit specifically includes an inductor L1, a diode D1, a switching transistor M1, and a resistor R. CS In this circuit, inductor L1 and diode D1 are connected in series between the input port Vin and the output port Vout. The anode of diode D1 is electrically connected to inductor L1, and the cathode of diode D1 is electrically connected to the output port Vout. The drain (d) of switching transistor M1 is electrically connected to the anode of diode D1, and the source (s) of switching transistor M1 is connected to resistor R. CS Connect to ground (GND). Thus, by inputting a switching signal to the gate (g) of the switching transistor M1, the conduction state of the switching transistor M1 is periodically controlled, thereby achieving voltage conversion. For example... Figure 7 As shown, the backlight driving circuit 32 can specifically include multiple (n) current output channels CH (channels CH1, CH2, ..., CHn), where each current output channel, under the control of its respective control signal (e.g., a pulse width modulation (PWM) signal), can provide current to each backlight string Ls (Ls1, Ls2, Ls3, ..., Lsn) to achieve the light emission control of the light-emitting units in the backlight string. Typically, this backlight driving circuit 32 can be implemented in chip form, such as... Figure 7 As shown, the PWM signal and each channel CH can be transmitted through the chip's output / input pins.

[0071] like Figure 8 As shown, a specific implementation of the circuitry for each channel in a backlight driving circuit 32 is provided. This backlight driving circuit 32 may include circuitry commensurate with the number of backlight LED strings (i.e., the number of channels). Figure 8The provided circuit structure includes a current source 321, an operational amplifier U1, a driver transistor Q1, a resistor R1, and a resistor R. FBx The first terminal of current source 321 is coupled to the power supply terminal VDD (which can be coupled to the voltage output terminal Vout of power supply 31); the second terminal of current source 321 is coupled to ground GND through resistor R1, and the second terminal of current source 321 is coupled to the positive input terminal (+) of operational amplifier U1. The control terminal of current source 321 is used to receive PWM signals; the gate g of driving transistor Q1 is coupled to the output terminal of operational amplifier U1, and the source s of driving transistor Q1 is coupled to resistor R1. FEx Coupled to ground (GND), the source (s) of driving transistor Q1 is coupled to the inverting input (-) of operational amplifier U1, and the drain (d) of driving transistor Q1 is coupled to the cathode of a string of lamps, providing a channel voltage V to the cathode of the string of lamps. CHx Thus, due to the relationship between resistor R1 and resistor R FBx Satisfying relation R1 / R FBx =K Iset When the current Iset output by the current source 321 is adjusted by controlling it with a PWM signal, the operational amplifier can output V based on the voltage difference between the positive input terminal (+) and the negative input terminal (-). OS Amplification is performed to adjust the conduction state of the drive transistor Q1 using the output signal, thereby adjusting V. CHx The size and the current I flowing through the light string LED , where Iset / I LED =1 / K Iset Of course, to ensure a stable voltage is supplied between the anode and cathode of each backlight string, Figure 7 The image also shows a capacitor C connected in parallel with the backlight string Ls1. LED1 ,certainly, Figure 7 Although the capacitors connected in series and parallel for other backlight LEDs are not shown in the diagram, it should be understood that other backlight LED strings also have corresponding capacitors connected in parallel. Similarly, to ensure the stability of the channel output voltage of the backlight drive circuit, a capacitor C is connected between each channel and ground GND. CH ( Figure 7 The image only shows the capacitor C corresponding to channel CH1. CH1 That is, the capacitor C connected to the cathode of the backlight string. CH1 ).

[0072] However, the relationship between the voltage (VF) and current of an LED is that the higher the voltage, the greater the current it conducts (e.g., ...). Figure 9 (As shown). Furthermore, under the same on-current, different LEDs have different voltage currents (VF) due to differences in manufacturing process and materials. Thus, due to the differences in LED manufacturing processes, the VF of the LED ultimately varies, resulting in different voltages for each channel (typically the channel voltage V).CHx The anode voltage Vout of the LED string and the voltage drop V of the backlight LED string are given. LS The difference (in terms of voltage) is also different. Because the VF voltage of each LED in the channel is different, when the same current I flows through it, the voltage difference will be different. LED Below, the total forward voltage (i.e., V) of the backlight string connected to each channel. LS The differences in voltage (V) across different channels result in different voltage levels (V) across each channel. CHx They are also different. Thus, when the voltage V of a certain channel... CHx At higher values, the power loss of the backlight driving circuit will increase, where the channel power loss P = V. CHx *I CHx (where I is in the series circuit) CHx =I LED Furthermore, because mini LED backlights use multiple channels, to save board layout area, the current sources (usually metal-oxide-semiconductor field-effect transistors, MOSFETs) that supply current to the backlight strings on each channel in the backlight driver circuit are typically integrated into a single chip along with the current source's driving circuitry. Therefore, this loss is released as heat on the chip, leading to chip overheating and, in severe cases, chip damage.

[0073] To solve the above problems, refer to Figure 10 As shown, an embodiment of this application provides a light-emitting device driving circuit. Applied to the aforementioned backlight module, the lamp board of the backlight module is provided with at least one backlight string Ls (wherein... Figure 10 The backlight strings shown are Ls1, Ls2, Ls3, ..., Lsn. The backlight string Ls includes at least one light-emitting unit connected in series. For example, the light-emitting unit can be... Figure 10 The LED in the backlight driving circuit includes: a control circuit 43, and at least one driving circuit 42 (wherein) Figure 10 The diagram shows drive circuits 42-1, 42-2, 42-3, ..., 42-n) and at least one current source 44 (wherein... Figure 10 The diagram shows current sources 44-1, 44-2, 44-3, ..., 44-n.

[0074] The first terminal of the current source 44 is coupled to the cathode of the backlight string Ls, and the anode of the backlight string Ls is coupled to the power supply 41 (e.g., coupled to...). Figure 10 The output terminal of the power supply is Vout); the second terminal of the current source 44 is coupled to ground GND; the drive circuit 42 is coupled to the control terminal of the current source 41; the control circuit 43 is coupled to the drive circuit 42, and the control circuit 43 is also coupled to the first terminal of the current source 44 or the control terminal of the current source 44.

[0075] Control circuit 43 is configured to detect the first terminal of current source 44 (e.g., Figure 10 (as shown) or the control terminal of current source 44 (such as...) Figure 11 The control circuit 43 is further configured to output a control signal to the drive circuit 42 based on the electrical signal; the drive circuit 42 is configured to adjust the current flowing through the first and second terminals of the current source 44 and the voltage at the first terminal of the current source 44 based on the control signal. Since the control circuit can adjust the current flowing through the first and second terminals of the current source and the voltage at the first terminal of the current source based on the electrical signal from the first terminal of the current source or the control terminal of the current source, the current flowing through the first and second terminals of the current source and the voltage at the first terminal of the current source can be dynamically adjusted by detecting the electrical signal from the first terminal of the current source or the control terminal of the current source, thus avoiding excessive losses when the current source provides current to its corresponding backlight string.

[0076] It should be noted that, since the current source 44 is controlled by the electrical signal at its control terminal, it can be understood that the electrical signal at the first terminal of the current source 44 and the electrical signal at the control terminal of the current source 44 have a fixed proportional relationship. The specific proportion is mainly limited by the parameter selection of the internal components of the current source. Furthermore, the control circuit 43 can be a logic function circuit such as a CPU, MCU, or FPGA, which has multiple input / output (I / O) interfaces. These interfaces can input or output digital or analog signals and perform some functional processing based on the input signals. For example, in implementing the embodiments of this application, the aforementioned electrical signals can be judged, and a control signal can be generated based on the judgment result. The aforementioned threshold can be a preset default value within the control circuit, or the threshold can also be the minimum voltage value corresponding to each electrical signal detected by the control circuit.

[0077] Specifically, if the control circuit 43 determines that the voltage corresponding to the electrical signal is greater than the first threshold, the control circuit controls the drive circuit 42 to increase the current flowing through the first and second terminals of the current source 44 and decrease the voltage at the first terminal of the current source 44 through the control signal. Thus, when the control circuit determines that the voltage corresponding to the first terminal or control terminal of a current source is greater than the threshold based on the electrical signal, it indicates that the voltage at the first terminal of the current source is too high, meaning that the current source is generating excessive losses when supplying current to its corresponding backlight string. If the voltage at the first terminal of the current source 44 is directly reduced by decreasing the current, it may not be possible to ensure that the backlight string connected to the current source emits light normally. Therefore, in this application, if the control circuit determines that the electrical signal is greater than the first threshold, the control circuit controls the drive circuit to increase the current flowing through the first and second terminals of the current source and decrease the voltage at the first terminal of the current source through the control signal. This ensures that the backlight string emits light normally, and by reducing the voltage at the first terminal of the current source, the losses generated by the current source are also reduced, thereby reducing the overall losses of the backlight drive circuit. In some examples, depending on the actual scenario, the voltage at the first terminal of the current source 44 can be increased, while the current flowing through the first and second terminals of the current source 44 can be decreased. For example, when the control circuit 44 determines that the voltage corresponding to the electrical signal is less than a second threshold, the control circuit controls the drive circuit to decrease the current flowing through the first and second terminals of the current source and increase the voltage at the first terminal of the current source through a control signal. For example, when the control circuit 44 adjusts (decreases or increases) the voltage at the first terminal of the current source, it can do so in steps. Different step sizes can be set depending on the application scenario. For example, a smaller step size can be set for low-power mobile phones, and a larger step size can be set for high-power large-screen devices, in order to ensure the accuracy of the adjustment while shortening the voltage adjustment time.

[0078] Furthermore, it is understandable that when the voltage at the first terminal of the current source is adjusted in smaller steps, the voltage at the first terminal of the current source will gradually approach the first threshold. Thus, when the control circuit 44 determines that the voltage at the first terminal of the current source is less than or equal to the first threshold for the first time after a voltage adjustment, the adjustment stops. Similarly, when the voltage at the first terminal of the current source is adjusted in larger steps, it is understandable that the voltage at the first terminal of the current source will gradually approach the second threshold. Thus, when the control circuit 44 determines that the voltage at the first terminal of the current source is greater than or equal to the second threshold for the first time after a voltage adjustment, the adjustment stops. Of course, when the step size is set relatively large, if the voltage at the first terminal of the current source is less than the first threshold for the first time after an adjustment when the voltage at the first terminal of the current source is adjusted in smaller steps, a smaller step size can be used to adjust the voltage at the first terminal of the current source, thereby making the voltage at the first terminal of the current source approach the first threshold even more closely. Of course, when the voltage at the first terminal of the current source is increased by step size, if the voltage at the first terminal of the current source is greater than the second threshold for the first time after a certain adjustment, the voltage at the first terminal of the current source can be decreased by a smaller step size, so that the voltage at the first terminal of the current source is closer to the second threshold. The first threshold and the second threshold can be the same value or different values.

[0079] Combination Figure 12 As shown, the embodiments of this application provide specific structures and connection methods for the driving circuit 42 and the current source 44. Specifically, driving circuit 42-1 includes operational amplifier U11 and switch K11; driving circuit 42-2 includes operational amplifier U21 and switch K21; driving circuit 42-3 includes operational amplifier U31 and switch K31; and driving circuit 42-n includes operational amplifier Un1 and switch Kn1. Current source 44-1 includes driving transistor Q11 and resistor R11; current source 44-2 includes driving transistor Q21 and resistor R21; current source 44-3 includes driving transistor Q31 and resistor R31; and current source 44-n includes driving transistor Qn1 and resistor Rn1. The following is combined with… Figure 12 The specific structure and connection method of the drive circuit 42-1 and the current source 44-1 are described. The internal structure and connection method of other drive circuits and current sources can be referred to the drive circuit 42-1 and the current source 44-1 and will not be described again.

[0080] The first terminal of driving transistor Q11 is coupled to the first terminal of current source 44-1, and the second terminal of driving transistor Q11 is coupled to the second terminal of current source 44-1 (i.e., ground GND) through resistor R11. The control terminal of driving transistor Q11 is coupled to the control terminal of current source 44-1. The positive input terminal (+) of operational amplifier U11 is coupled to control circuit 43, and the negative input terminal (-) of operational amplifier U11 is coupled to the second terminal of driving transistor Q11. The output terminal of operational amplifier U11 is coupled to the first terminal of switch K11, and the second terminal of switch K11 is coupled to the control terminal of driving transistor Q11.

[0081] The control signals include voltage signals Vset (Vset11, Vset21, Vset31...Vsetn1) and switch control signals PWM (PWM11, PWM21, PWM31...PWMn1); the positive input terminal (+) of operational amplifier U11 is configured to receive voltage signal Vset11, and the control terminal of switch K11 is configured to receive switch control signal PWM11; wherein, when switch control signal PWM11 turns on the switch, voltage signal Vset11 is used to control the current flowing through the first and second terminals of driving transistor Q11 (i.e., the current flowing through circuit I of lamp string Ls1). Ls1 The switching control signal PWM11 is used to control the voltage at the first terminal of the drive transistor Q11 (i.e., the channel voltage V of the lamp string Ls1). CH1 In order to simplify circuit design and reduce costs, [the following was combined]. Figure 13 As shown, the driving transistors Q11, Q21, Q31, ..., Qn1 are all N-type transistors. In this case, the first terminal of driving transistor Q11 is the drain (d), the second terminal is the source (s), and the control terminal is the gate (g). When driving transistor Q11 uses an N-type transistor, the source (s) is directly connected to ground (GND) through resistor R11 (a fixed value). It only needs to have a higher voltage at the gate than the source to conduct; for example, a fixed voltage of Vin or Vout will suffice. When conducting, the current flows from the drain to the source; the circuit design is relatively simple. When using other methods, such as when driving transistors Q11, Q21, Q31, ..., Qn1 are all P-type transistors, the drain (d) of driving transistor Q11 needs to be connected to ground through R11. When conducting, the current flows from the source to the drain, but the voltage at the source is not fixed (depending on the voltage division of the backlight string). Therefore, the gate voltage controlling the conduction of driving transistor Q11 cannot be determined, requiring a separate isolated power supply control or bootstrap voltage boost circuit.

[0082] Specifically, in combination Figure 13The specific functions of the drive circuit 42-1 and the current source 44-1 are explained as follows: Since the inverting input terminal (-) of the operational amplifier U11 is directly connected to the source (s) terminal of transistor Q11, when the switch K11 connects the output terminal of U11 to the gate (g) terminal of Q11, a closed-loop feedback is formed. Therefore, the voltage signal Vset11 input to the positive input terminal (+) of U11 is equal to the voltage at the source (s) terminal of Q11. From this, the following formula can be constructed:

[0083] Vout = V Ls1 +V CH1 Equation 1; where V LS1 For the voltage divider of the backlight string Ls1, V CH1 The voltage at the drain (d) terminal of Q11;

[0084] V Ls1 =VF1+VF2+VF3+……VFm, Equation 2; m is the number of LEDs on the backlight string LS1, and VF is the forward voltage drop of the LED;

[0085] I Ls1 =Vset11 / R11, Equation 3; I Ls1 This represents the current of the backlight string Ls1;

[0086] Vset11=V CH1 ×D PWM11 Formula 4; D PWM11 This refers to the duty cycle of the switching control signal PWM11;

[0087] I = I0 exp(qVF / nkT-1), Equation 5; q, n, k and T are constants, and I0 is the reverse saturation current of the LED;

[0088] Based on equations one through five above, when V CH1 When it is higher, Vset11 can be increased by adjusting it. Then, according to Equation 3, this will lead to I Ls1 Increase. At the same time, according to Equation 5, when I... Ls1 Increasing the value of V leads to an increase in VF. Therefore, V can be obtained from equation two. Ls1 It will become larger. Combining with Equation 1, since Vout is fixed, V needs to be reduced. CH1 According to Equation 4, since Vset11 increases and V CH1 To balance equation four, D needs to be increased by decreasing it. PWM11 This allows for either increasing or maintaining the current I of the backlight string. Ls1 While ensuring its normal light emission, V was reduced. CH1 This also reduces the overall loss of the backlight driving circuit. Of course, in some examples, when V... CH1 When it is relatively small, if there is a need to increase VCH1 You can also adjust and decrease Vset11, and reduce D. PWM11 .

[0089] Of course, the above explanation mainly focuses on the control circuit 43 detecting V. CH1 Taking this as an example, the relationship between the gate (g) voltage and the drain (d) voltage of Q11 is usually fixed. Therefore, since the gate voltage of Q11 reflects the drain voltage, the gate voltage can also be used as the aforementioned electrical signal. That is, when the gate voltage is greater than the threshold (which can be understood as the threshold values ​​set for the gate and drain are not the same), it precisely reflects V. CH1 Relatively high.

[0090] Furthermore, in combination Figure 14 As shown, switch K11 includes transistors Q12 and Q13; the first terminal of transistor Q12 is coupled to ground GND, the second terminal of transistor Q12 is coupled to the control terminal of transistor Q13, and the control terminal of transistor Q12 is coupled to control circuit 43; the first terminal of transistor Q13 is coupled to the output terminal of operational amplifier U11, the second terminal of transistor Q13 is coupled to the control terminal of driving transistor Q11, and the control terminal of transistor Q13 is also coupled to the output terminal of operational amplifier U11 through resistor R12; transistor Q12 is configured to periodically turn on the first and second terminals of transistor Q12 under the control of switch control signal Vset11; transistor Q13 is configured to turn on the first and second terminals of transistor Q13 when the first and second terminals of transistor Q12 are turned on, so as to transmit the signal from the output terminal of operational amplifier U11 to the control terminal of driving transistor Q11.

[0091] For example, transistor Q12 can be an N-type transistor, and Q13 can be a P-type transistor. When transistor Q12 is an N-type transistor, the source (s) terminal is the first terminal, the drain (d) terminal is the second terminal, and the gate (g) terminal is the control terminal. When transistor Q13 is a P-type transistor, the source (s) terminal is the first terminal, the drain (d) terminal is the second terminal, and the gate (g) terminal is the control terminal. In this way, when Q12 is turned on, the current flows from the drain (d) terminal to the source (s) terminal, and when Q13 is turned on, the current flows from the source (s) terminal to the drain (d) terminal. Furthermore, the source terminal of Q12 is connected to ground (GND) with a fixed voltage, which facilitates circuit design. When Q12 is turned on, resistor R12 provides a fixed voltage difference between the source (s) terminal and the gate (g) terminal of Q13. As long as the voltage at the source terminal is greater than that at the gate terminal and the conduction threshold condition is met, Q13 can be turned on.

[0092] Combination Figure 15 As shown, the backlight driving circuit also includes: bandgap reference sources 45 (45-1, 45-2, 45-3, ..., 45-n). Figure 15As shown, bandgap reference source 45-1 is connected between drive circuit 42-1 and control circuit 43; bandgap reference source 45-2 is connected between drive circuit 42-2 and control circuit 43; bandgap reference source 45-3 is connected between drive circuit 42-3 and control circuit 43; and bandgap reference source 45-n is connected between drive circuit 42-n and control circuit 43. The bandgap reference sources 45 (45-1, 45-2, 45-3, ..., 45-n) are configured to adjust the voltage signal Vset (Vset11, Vset21, Vset31, ..., Vsetn1) according to a predetermined ratio. Figure 15 The control circuit 43 shown is used to detect the electrical signal at the first terminal of the current source 44; as Figure 16 As shown, the bandgap reference source 45 can also be applied to a scheme where the control circuit 43 detects the electrical signal at the control terminal of the current source 44.

[0093] like Figure 17 As shown, a specific structural schematic diagram of a bandgap reference source 45 is provided, including: transistors Q14, Q15, Q16, operational amplifier U13, resistors R13 and R14; wherein, the first terminal of Q15 is connected to the power supply terminal VCC, the first terminal of Q16 is connected to the power supply terminal VCC; the control terminal of Q15 is connected to the control terminal of Q16, the second terminal of Q15 is connected to the control terminal of Q15 and the first terminal of Q14, and the second terminal of Q14 is connected to ground GND through resistor R13; the positive input terminal (+) of the operational amplifier is connected to the control circuit 43 for receiving the voltage signal Vset11; the negative input terminal (-) of the operational amplifier U13 is connected to ground GND; the second terminal of Q16 is connected to the driving circuit 42-1 through resistor R14 (specifically connected to the positive input terminal (+) of the operational amplifier U11 of the driving circuit 42-1). In this way, the bandgap reference source 45 can adjust the ratio of Vset11 to the voltage output to the drive circuit 42-1 according to the ratio of resistors R13 and R14. Thus, when the control step of the control circuit 43 on Vset11 is large (e.g., 50mV), the voltage signal output to the positive input terminal (+) of the operational amplifier U11 can be adjusted to a smaller step (e.g., 10mV) by adjusting the ratio of resistors R13 and R14. Therefore, according to Equation 3 above, when controlling the current of the backlight string Ls1, a smaller current accuracy can be achieved, thereby enabling more precise backlight brightness adjustment. Furthermore, to reduce the complexity and cost of the circuit design, Q15 and Q16 can be P-type transistors, and Q14 can be an N-type transistor. When transistor Q14 is an N-type transistor, the source (s) terminal is the second terminal, the drain (d) terminal is the first terminal, and the gate (g) terminal is the control terminal. When transistors Q15 and Q16 are P-type transistors, the source (s) terminal is the first terminal, the drain (d) terminal is the second terminal, and the gate (g) terminal is the control terminal.

[0094] Of course, in some scenarios, each sub-lamp board of the backlight module needs to provide 16, 32, 48, or even more channels of backlight LED string. Limited by the number of ports provided by the control circuit 43, when the control circuit 43 cannot provide the corresponding number of channels to realize the detection of the electrical signal at the first terminal or control terminal of the aforementioned current source 44, such as... Figure 18 As shown, the backlight driving circuit provided in the embodiments of this application further includes: a selector 46, wherein the selector 46 includes a plurality of input terminals, an output terminal, and at least one control terminal; the first terminal of each current source 44 (44-1, 44-2, 44-3, ..., 44-n) or the control terminal of the current source is coupled to the input terminal of the selector 46; the output terminal of the selector 46 is coupled to the control circuit 43; at least one control terminal of the selector 46 is coupled to the control circuit 43; the control circuit 43 is configured to output a gating control signal to the selector 46 through at least one control terminal of the selector 46; the selector 46 is configured to connect any input terminal of the selector 46 to the output terminal of the selector 46 according to the gating control signal.

[0095] For example, when the sub-light panel contains a backlight string with four channels (Ls1, Ls2, Ls3, and Ls4), the selector 46 can include four input terminals and two control terminals. Thus, the control circuit 43 can input a two-bit binary code to the two control terminals to control the selection of the selector 46. For instance, if the control circuit 43 inputs binary code 00 to the selector 46 through the two control terminals, the selector 46 will connect the first input terminal to the output terminal, thereby connecting the first terminal of the current source 44-1 connected to the backlight string Ls1 to the control circuit 43, realizing the detection of the electrical signal at the first terminal of the current source 44-1; if the control circuit 43 inputs binary code 01 to the selector 46 through the two control terminals, the selector 46 will connect the second input terminal to the output terminal, thereby connecting the first terminal of the current source 44-2 connected to the backlight string Ls2 to the control circuit 43, realizing the detection of the electrical signal at the first terminal of the current source 44-2. The control circuit 43 inputs binary code 10 to the selector 46 through two control terminals. The selector 46 then connects its third input terminal to its output terminal, thus connecting the first terminal of the current source 44-3 connected to the backlight string Ls3 to the control circuit 43, enabling the detection of the electrical signal at the first terminal of the current source 44-3. Similarly, the control circuit 43 inputs binary code 11 to the selector 46 through two control terminals. The selector 46 then connects its fourth input terminal to its output terminal, thus connecting the first terminal of the current source 44-4 connected to the backlight string Ls4 to the control circuit 43, enabling the detection of the electrical signal at the first terminal of the current source 44-4. This time-division multiplexing of the electrical signals at the first terminal of each current source 44 reduces the complexity of the control circuit 43. Of course, Figure 18The control circuit 43 shown is used to detect the electrical signal at the first terminal of the current source 44; as Figure 19 As shown, the selector 46 can also be applied to a scheme where the control circuit 43 detects the electrical signal at the control terminal of the current source 44.

[0096] In the above scheme, the control circuit 43 mainly detects the signal at the first end or control end of the current source 44 in the analog domain, that is, it directly detects the analog signal at the first end or control end of the current source 44.

[0097] In some implementations, the control circuit 43 can also detect the signal at the first or control terminal of the current source 44 in the digital domain. (See reference...) Figure 20As shown, the backlight driving circuit also includes at least one comparator (U12, U22, U32, ..., Un2) and a reference voltage generation circuit 47. Taking the connection relationship of comparator U12 as an example, the positive input terminal of U12 is coupled to the first terminal of current source 44-1 or the control terminal of current source 44-1, and the inverting input terminal of comparator U12 is coupled to the reference voltage generation circuit 47; the output terminal of comparator U12 is coupled to the control circuit 43; the reference voltage generation circuit 47 is configured to generate a first reference voltage Vref; the comparator U12 is configured to compare the voltage of the first terminal of current source 44-1 with the first reference voltage Vref, or compare the voltage of the control terminal of current source 44-1 with the first reference voltage Vref, and output the comparison result at the output terminal of comparator U12. For example, if the voltage at the first terminal of current source 44-1 is greater than the first reference voltage Vref, or the voltage at the control terminal of current source 44-1 is greater than the first reference voltage Vref, then the comparison result 1 is output; otherwise, the comparison result 0 is output. The control circuit 43 is configured to determine the electrical signal at the first terminal or the control terminal of current source 44-1 based on the comparison result. The connection relationships and functions of the other comparators U22, U32, ..., Un2 with their corresponding current sources 44-2, 44-3, ..., 44-n are similar to those of U12 described above, and will not be repeated here. Thus, when the first reference voltage Vref gradually increases in steps, the comparator Ux1 connected to the current source 44-x, which is initially lower than the first reference voltage Vref, will output 0, while the comparators connected to other current sources 44 will output 1. At this time, the control circuit 43 can control the reference voltage generation circuit 47 to maintain the first reference voltage Vref, and adjust the voltage of the first terminal or control terminal of the other current sources 44 by adjusting the Vset and PDM of the drive circuits connected to the other current sources 44, until all comparators output 0. Then, the voltage of the first terminal (or control terminal) of each current source 44 is adjusted to a lower, near-or the same level. Of course, the above adjustment of the voltage of the first terminal (or control terminal) of other current sources 44 is based on the voltage of the first terminal (or control terminal) of a certain current source 44. Alternatively, to ensure that the voltage of the first terminal (or control terminal) of all current sources 44 stabilizes at a specified voltage, the first reference voltage Vref can also be configured to that specified voltage. Figure 20 The control circuit 43 shown is used to detect the electrical signal at the first terminal of the current source 44; as Figure 21 As shown, the control circuit 43 can detect the signal at the first terminal or control terminal of the current source 44 in the digital domain. It can also be applied to a scheme where the control circuit 43 detects the electrical signal at the control terminal of the current source 44.

[0098] In addition, combined Figure 22As shown, a first chip CS1 is provided, applied to a backlight module. The backlight module's lamp board has at least one backlight string, each backlight string including at least one series-connected light-emitting unit. The first chip CS1 includes: at least one driving circuit 42 and at least one current source 44, as described above. Figure 10 as well as Figure 11 The connection method is as follows: the first terminal of the current source 44 is used to couple the cathode of the backlight string Ls, and the anode of the backlight string Ls is coupled to the power supply 41; the second terminal of the current source 44 is used to couple to ground GND; the driving circuit 42 is coupled to the control terminal of the current source 44; the driving circuit 42 is also coupled to the control circuit 43; the first terminal or the control terminal of the current source 44 is also used to couple to the control circuit 43; the functions of the driving circuit 42, the control circuit 43, and the current source 44 can be referred to the above example and will not be repeated here. Specifically, refer to... Figure 22 The provided package structure of the first chip CS1 also includes input pins (Pin-Pinx) and output pins (pout1-poutn). Among them... Figure 22 The example shown also includes a second chip CS2, which includes the control circuit 43 described above. The function and connection method of the control circuit 43 are as described above. Figure 10 as well as Figure 11 The description will not be repeated here. For details, please refer to [link / reference]. Figure 22 The provided package structure of the second chip CS2 also includes input pins (Pin-Pinn) and output pins (pout1-poutm), where m = 2n. The input pins (Pin-Pinn) of the first chip CS1 and the output pins (pout1-poutm) of the second chip CS2 are connected one-to-one, providing a connection between the control circuit 43 and each of the driving circuits 42. The output pins (pout1-poutn) of the first chip CS1 are respectively connected to the cathodes of a backlight string Ls (Ls1-Lsn), and the input pins (Pin-Pinn) of the second chip CS2 are respectively connected to the cathodes Ls (Ls1-Lsn) of a backlight string. This achieves a scheme for detecting the electrical signals at the first end of each current source.

[0099] exist Figure 23 In the provided solution, relative to Figure 22 As shown, to implement the detection scheme for the electrical signals at the control terminals of each current source, the first chip CS1 also includes external pins (pg1-pgn), where each external pin (pg1-pgn) is connected to the control terminal (i.e., the gate of the driving transistor) of a current source. Figure 23In the provided scheme, the input pins (Pin-Pinn) of the second chip CS2 are connected one by one to the external pins (pg1-pgn) of the first chip CS1, thereby realizing the detection scheme of electrical signals of the control terminals of each current source. Furthermore, when the backlight driving circuit also includes one or more of the aforementioned gap reference source 45, selector 46, comparators (U12, U22, ..., Un2), and reference voltage generation circuit 47, these components can be selectively integrated into either the first chip CS1 or the second chip CS2. For example, the gap reference source 45 can be integrated into the first chip CS1, and the selector 46, comparators (U12, U22, ..., Un2), and reference voltage generation circuit 47 can be integrated into the second chip CS2.

[0100] exist Figure 24 In the provided solution, the second chip CS2 can also be integrated into the first chip CS1. In this case, the first chip CS1 includes at least one driving circuit 42, a control circuit 43, and at least one current source 44 from the aforementioned backlight driving circuit. The functions of the driving circuit 42, control circuit 43, and current source 44 are as described in the previous example and will not be repeated here. Specifically, refer to... Figure 24 The provided package structure of the first chip CS1 includes pins (Pi / o1-Pi / on), where each pin (Pi / o1-Pi / on) is connected to the cathode of a lamp string to provide a connection between the backlight driving circuit and each backlight lamp string. Furthermore, when the backlight driving circuit also includes one or more of the aforementioned gap reference source 45, selector 46, comparators (U12, U22, ..., Un2), and reference voltage generation circuit 47, these components can also be selectively integrated into the first chip CS1.

[0101] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce a good effect.

[0102] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A backlight driving circuit, applied to a backlight module, wherein at least one backlight LED string is disposed on the lamp board of the backlight module, the backlight LED string comprising at least one light-emitting unit connected in series; characterized in that, The backlight driving circuit includes: a control circuit, at least one driving circuit, and at least one current source; The first end of the current source is used to couple to the cathode of the backlight string, and the anode of the backlight string is used to couple to the power supply; the second end of the current source is used to couple to ground; the driving circuit is coupled to the control end of the current source; the control circuit is coupled to the driving circuit, and the control circuit is also coupled to the control end of the current source; The control circuit is configured to detect the electrical signal at the control terminal of the current source; The control circuit is further configured to output a control signal to the drive circuit based on the electrical signal; The driving circuit is configured to adjust the current flowing through the first and second terminals of the current source, and the voltage at the first terminal of the current source, according to the control signal. The driving circuit includes an operational amplifier and a first switch; the current source includes a driving transistor and a first resistor. The first terminal of the driving transistor is coupled to the first terminal of the current source, the second terminal of the driving transistor is coupled to the second terminal of the current source through the first resistor, and the control terminal of the driving transistor is coupled to the control terminal of the current source. The positive input terminal of the operational amplifier is coupled to the control circuit, and the inverting input terminal of the operational amplifier is coupled to the second terminal of the driving transistor. The output terminal of the operational amplifier is coupled to the first terminal of the first switch, and the second terminal of the first switch is coupled to the control terminal of the driving transistor. The control signals include voltage signals and switch control signals; The positive input terminal of the operational amplifier is configured to receive the voltage signal, and the control terminal of the first switch is configured to receive the switch control signal; Wherein, when the switch control signal turns on the first switch, the voltage signal is used to control the current flowing through the first and second terminals of the driving transistor, and the switch control signal is used to control the voltage at the first terminal of the driving transistor; It also includes: a bandgap reference source, wherein the bandgap reference source is connected between the driving circuit and the control circuit; The bandgap reference source is configured to adjust the voltage signal according to a predetermined ratio.

2. The backlight driving circuit according to claim 1, characterized in that, If the control circuit determines that the voltage corresponding to the electrical signal is greater than a first threshold, the control circuit controls the drive circuit to increase the current flowing through the first and second terminals of the current source and decrease the voltage at the first terminal of the current source through the control signal.

3. The backlight driving circuit according to claim 1, characterized in that, If the control circuit determines that the voltage corresponding to the electrical signal is less than the second threshold, the control circuit controls the drive circuit to reduce the current flowing through the first and second terminals of the current source and increase the voltage at the first terminal of the current source through the control signal.

4. The backlight driving circuit according to claim 1, characterized in that, The first switch includes: a first transistor and a second transistor; The first terminal of the first transistor is coupled to ground, the second terminal of the first transistor is coupled to the control terminal of the second transistor, and the control terminal of the first transistor is coupled to the control circuit; The first terminal of the second transistor is coupled to the output terminal of the operational amplifier, the second terminal of the second transistor is coupled to the control terminal of the driving transistor, and the control terminal of the second transistor is also coupled to the output terminal of the operational amplifier through a second resistor; The first transistor is configured to periodically turn on its first terminal and its second terminal under the control of the switch control signal; The second transistor is configured to conduct the first terminal of the second transistor and the second terminal of the second transistor when the first terminal of the first transistor and the second terminal of the first transistor are conducting, so as to transmit the signal at the output terminal of the operational amplifier to the control terminal of the driving transistor.

5. The backlight driving circuit according to claim 4, characterized in that, The first transistor includes an N-type transistor, and the second transistor includes a P-type transistor; the first terminal of the first transistor is the source of the N-type transistor; the second terminal of the first transistor is the drain of the N-type transistor, and the control terminal of the first transistor is the gate of the N-type transistor; the first terminal of the second transistor is the source of the P-type transistor; the second terminal of the second transistor is the drain of the P-type transistor, and the control terminal of the second transistor is the gate of the P-type transistor.

6. The backlight driving circuit according to any one of claims 1-5, characterized in that, Also includes: At least one comparator and a reference voltage generation circuit; The positive input terminal of the comparator is coupled to the first terminal of the current source or the control terminal of the current source; the inverting input terminal of the comparator is coupled to the reference voltage generation circuit; and the output terminal of the comparator is coupled to the control circuit. The reference voltage generation circuit is configured to generate a first reference voltage; The comparator is configured to compare the voltage at the first terminal of the current source with the first reference voltage, or to compare the voltage at the control terminal of the current source with the first reference voltage, and to output a comparison result at the output terminal of the comparator. The control circuit is configured to determine the electrical signal of the first terminal of the current source or the control terminal of the current source based on the comparison result.

7. The backlight driving circuit according to any one of claims 1-5, characterized in that, It also includes: a selector, wherein the selector includes a plurality of input terminals, an output terminal and at least one control terminal, a first terminal of the current source or the control terminal of the current source is coupled to the input terminal of the selector, the output terminal of the selector is coupled to the control circuit, and at least one control terminal of the selector is coupled to the control circuit; The control circuit is configured to output a gating control signal to the selector through at least one control terminal of the selector; The selector is configured to connect either input terminal of the selector to the output terminal of the selector according to the gating control signal.

8. A chip used in a backlight module, wherein at least one backlight string is disposed on the lamp board of the backlight module, the backlight string comprising at least one light-emitting unit connected in series; characterized in that, The chip includes: at least one driving circuit and at least one current source; The first end of the current source is used to couple to the cathode of the backlight string, and the anode of the backlight string is coupled to the power supply; the second end of the current source is used to couple to ground; the driving circuit is coupled to the control end of the current source; the driving circuit is also used to couple to the control circuit; the control end of the current source is also used to couple to the control circuit. The control circuit is configured to detect the electrical signal at the control terminal of the current source; The control circuit is further configured to output a control signal to the drive circuit based on the electrical signal; The driving circuit is configured to adjust the current flowing through the first and second terminals of the current source, and the voltage at the first terminal of the current source, according to the control signal. The driving circuit includes an operational amplifier and a first switch; the current source includes a driving transistor and a first resistor. The first terminal of the driving transistor is coupled to the first terminal of the current source, the second terminal of the driving transistor is coupled to the second terminal of the current source through the first resistor, and the control terminal of the driving transistor is coupled to the control terminal of the current source. The positive input terminal of the operational amplifier is coupled to the control circuit, and the inverting input terminal of the operational amplifier is coupled to the second terminal of the driving transistor. The output terminal of the operational amplifier is coupled to the first terminal of the first switch, and the second terminal of the first switch is coupled to the control terminal of the driving transistor. The control signals include voltage signals and switch control signals; The positive input terminal of the operational amplifier is configured to receive the voltage signal, and the control terminal of the first switch is configured to receive the switch control signal; Wherein, when the switch control signal turns on the first switch, the voltage signal is used to control the current flowing through the first and second terminals of the driving transistor, and the switch control signal is used to control the voltage at the first terminal of the driving transistor; It also includes: a bandgap reference source, which is connected between the positive input terminal of the operational amplifier and the control circuit; The bandgap reference source is configured to adjust the voltage signal according to a predetermined ratio.

9. The chip according to claim 8, characterized in that, If the control circuit determines that the voltage corresponding to the electrical signal is greater than a first threshold, the control circuit controls the drive circuit to increase the current flowing through the first and second terminals of the current source and decrease the voltage at the first terminal of the current source through the control signal.

10. The chip according to claim 8, characterized in that, If the control circuit determines that the voltage corresponding to the electrical signal is less than the second threshold, the control circuit controls the drive circuit to reduce the current flowing through the first and second terminals of the current source and increase the voltage at the first terminal of the current source through the control signal.

11. The chip according to claim 8, characterized in that, The first switch includes: a first transistor and a second transistor; The first terminal of the first transistor is coupled to ground, the second terminal of the first transistor is coupled to the control terminal of the second transistor, and the control terminal of the first transistor is coupled to the control circuit; The first terminal of the second transistor is coupled to the output terminal of the operational amplifier, the second terminal of the second transistor is coupled to the control terminal of the driving transistor, and the control terminal of the second transistor is also coupled to the output terminal of the operational amplifier through a second resistor; The first transistor is configured to periodically turn on its first terminal and its second terminal under the control of the switch control signal; The second transistor is configured to conduct the first terminal of the second transistor and the second terminal of the second transistor when the first terminal of the first transistor and the second terminal of the first transistor are conducting, so as to transmit the signal at the output terminal of the operational amplifier to the control terminal of the driving transistor.

12. The chip according to claim 11, characterized in that, The first transistor includes an N-type transistor, and the second transistor includes a P-type transistor; the first terminal of the first transistor is the source of the N-type transistor; the second terminal of the first transistor is the drain of the N-type transistor, and the control terminal of the first transistor is the gate of the N-type transistor; the first terminal of the second transistor is the source of the P-type transistor; the second terminal of the second transistor is the drain of the P-type transistor, and the control terminal of the second transistor is the gate of the P-type transistor.

13. The chip according to any one of claims 8-12, characterized in that, Also includes: At least one comparator and a reference voltage generation circuit; The positive input terminal of the comparator is coupled to the first terminal of the current source or the control terminal of the current source; the inverting input terminal of the comparator is coupled to the reference voltage generation circuit; and the output terminal of the comparator is coupled to the control circuit. The reference voltage generation circuit is configured to generate a first reference voltage; The comparator is configured to compare the voltage at the first terminal of the current source with the first reference voltage, or to compare the voltage at the control terminal of the current source with the first reference voltage, and to output a comparison result at the output terminal of the comparator. The control circuit is configured to determine the electrical signal of the first terminal of the current source or the control terminal of the current source based on the comparison result.

14. The chip according to any one of claims 8-12, characterized in that, It also includes: a selector, wherein the selector includes a plurality of input terminals, an output terminal and at least one control terminal, a first terminal of the current source or the control terminal of the current source is coupled to the input terminal of the selector, the output terminal of the selector is coupled to the control circuit, and at least one control terminal of the selector is coupled to the control circuit; The control circuit is configured to output a gating control signal to the selector through at least one control terminal of the selector; The selector is configured to connect either input terminal of the selector to the output terminal of the selector according to the gating control signal.

15. The chip according to any one of claims 8-12, characterized in that, The control circuit is contained within the chip.

16. A backlight module, characterized in that, The backlight module includes a backplate, a flat plate, a lamp board, and a diffuser plate; wherein the flat plate is located between the backplate and the lamp board, and the lamp board is located between the flat plate and the diffuser plate; at least one backlight string is provided on the lamp board, and the backplate is provided with a backlight driving circuit as described in any one of claims 1-7, or a chip as described in any one of claims 8-15.

17. An electronic device, characterized in that, It includes the backlight module as described in claim 16, and the liquid crystal panel disposed on the backlight module.

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