Voltage reduction system, circuit board and display screen

Abstract

The utility model provides a voltage reduction system, a circuit board and a display screen. The step-down system comprises a first capacitor, a step-down circuit and a voltage division circuit; a first polar plate of the first capacitor is connected with a first end of the backlight module, and a second polar plate of the first capacitor is connected with a second end of the backlight module and a grounding end; the first end of the step-down circuit is used for outputting first load voltage, and the second end of the step-down circuit is used for outputting second load voltage; and one end of the voltage division circuit is connected with the second end of the voltage reduction circuit and used for accessing second load voltage, and the other end of the voltage division circuit is connected with the third end of the backlight module. The voltage reduction system can perform voltage division processing on the negative voltage flowing to the backlight module so as to reduce the negative voltage borne by the light-emitting diode in the backlight module, so that the problem that the light-emitting diode is damaged by the negative voltage and fails is avoided, the service life of the light-emitting diode is prolonged, the light emitting reliability of the backlight module is further ensured, and the service life of the backlight module is prolonged. And the display effect of the display screen is further ensured.

Description

Technical Field

[0001] The present application relates to the technical field of backlight display, and more specifically, to a voltage reduction system, a circuit board and a display screen. Background Art

[0002] At present, display screens usually use light emitting diodes (LEDs) as backlight modules to provide light sources. However, LEDs usually require a specific driving voltage to ensure efficient and stable light emission. For this reason, display screens in related technologies are usually provided with a step-down circuit to reduce the high voltage of the display screen to a load voltage so that the LEDs can emit light stably.

[0003] However, at the moment of power-on, the negative pressure on the backlight module may be too large, causing the light-emitting diodes in the backlight module to be damaged and fail, thereby affecting the display effect of the display screen. Utility Model Content

[0004] To solve the above problems, the present application provides a step-down system, a circuit board and a display panel, which aim to solve the problem that the backlight module is subjected to excessive negative pressure at the moment of power-on, causing the backlight module to be damaged and fail.

[0005] In a first aspect, the present application provides a step-down system, which is applied to a backlight module, wherein the backlight module includes a plurality of light-emitting diodes connected in series, and the step-down system includes a first capacitor, a step-down circuit, and a voltage divider circuit; a first plate of the first capacitor is connected to a first end of the backlight module, and a second plate of the first capacitor is connected to a second end of the backlight module and a ground end; a first end of the step-down circuit is connected to a first end of the backlight module for outputting a first load voltage; one end of the voltage divider circuit is connected to a second end of the step-down circuit for receiving a second load voltage output by the step-down circuit, and the other end of the voltage divider circuit is connected to a third end of the backlight module.

[0006] Based on the step-down system provided by the present application, when the step-down circuit is short-circuited at the moment of power-on, the second load voltage outputted from the second end of the step-down circuit is in a high voltage state relative to the ground and flows to the light-emitting diode close to the output end of the step-down circuit. At this time, a voltage divider circuit is provided in the second end of the step-down circuit and the third end of the backlight module. The voltage divider circuit can divide the negative pressure flowing to the backlight module to reduce the negative pressure borne by the light-emitting diode in the backlight module, thereby avoiding the problem that the negative pressure borne by the reverse-cutoff light-emitting diode exceeds the withstand voltage specification value that it can withstand, causing the light-emitting diode to be damaged and fail, thereby improving the service life of the light-emitting diode, thereby ensuring the light output reliability of the backlight module, and further ensuring the display effect of the display screen.

[0007] As an optional embodiment, the backlight module also includes a second capacitor, the first plate of the second capacitor is connected to one of the light-emitting diodes, and the second plate of the second capacitor is connected to the second plate of the first capacitor and the ground terminal; wherein the step-down circuit, the voltage divider circuit, the light-emitting diode and the second capacitor form a closed loop.

[0008] As an optional implementation, the voltage divider circuit includes a diode, a cathode of the diode is connected to the second end of the step-down circuit, and an anode of the diode is connected to the third end of the backlight module.

[0009] In the above technical solution, the diode divides the voltage to reduce the negative pressure on the light-emitting diode, thereby preventing the negative pressure on the reverse-cutoff light-emitting diode from exceeding the withstand voltage specification value that it can withstand, causing the light-emitting diode to be damaged and fail, thereby increasing the service life of the light-emitting diode. In addition, the diode is small in size, low in cost, and simple to prepare.

[0010] As an optional embodiment, the step-down circuit includes a fourth capacitor, a first resistor and a second resistor; the first plate of the fourth capacitor is connected to the first load voltage, and the second plate of the fourth capacitor is connected to one end of the voltage divider circuit; one end of the first resistor is connected to the first plate of the fourth capacitor; one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is connected to the second plate of the fourth capacitor and one end of the voltage divider circuit.

[0011] As an optional implementation, the voltage reduction system further includes a voltage stabilizing circuit, one end of the voltage stabilizing circuit is connected to the second end of the voltage reduction circuit and one end of the voltage divider circuit, and the other end of the voltage stabilizing circuit is connected to the third end of the backlight module.

[0012] As an optional implementation, the voltage stabilizing circuit includes a third resistor, one end of the third resistor is connected to the second end of the step-down circuit and one end of the voltage divider circuit, and the other end of the third resistor is connected to the third end of the backlight module.

[0013] As an optional implementation, the voltage stabilizing circuit includes a magnetic bead unit, one end of the magnetic bead unit is connected to the second end of the step-down circuit and one end of the voltage divider circuit, and the other end of the magnetic bead unit is connected to the third end of the backlight module.

[0014] In a second aspect, an embodiment of the present application provides a circuit board, comprising the step-down system described in any optional manner of the first aspect.

[0015] In a third aspect, an embodiment of the present application provides a display screen, comprising a backlight module and the circuit board described in the second aspect, wherein the backlight module comprises a plurality of light-emitting diodes connected in series, and the circuit board is electrically connected to the backlight module. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of a module structure of a display screen provided by a related technical embodiment;

[0018] Figure 2 It is a schematic diagram of a circuit structure of a display screen provided by a related technical embodiment;

[0019] Figure 3 It is a schematic diagram of the circuit structure of a display screen provided in an embodiment of the present application;

[0020] Figure 4 is a schematic diagram of the circuit structure of another display screen provided in an embodiment of the present application;

[0021] Figure 5 This is a schematic diagram of the circuit structure of another display screen provided in an embodiment of the present application;

[0022] Figure 6 is a schematic diagram of a circuit structure of another display screen provided in an embodiment of the present application;

[0023] Figure 7 is a schematic diagram of a circuit structure of another display screen provided in an embodiment of the present application;

[0024] Figure 8 is a schematic diagram of a circuit structure of another display screen provided in an embodiment of the present application;

[0025] Fig. 9 is a schematic diagram of a circuit structure of another display screen provided in an embodiment of the present application;

[0026] Fig.10 is a schematic diagram of a circuit structure of another display screen provided in an embodiment of the present application;

[0027] Fig.11 is a schematic diagram of a circuit structure of another display screen provided in an embodiment of the present application;

[0028] Fig.12 This is a schematic diagram of the circuit structure of another display screen provided in an embodiment of the present application.

[0029] Reference numerals:

[0030] 1', display screen; 11', backlight module; 12', step-down circuit; 1, display screen; 11, backlight module; 12, circuit board; 13, step-down system; 131, step-down circuit; 132, voltage divider circuit; 133, voltage stabilizing circuit; 1331, magnetic bead unit;

[0031] LED, light-emitting diode; VBL, first load voltage; LED-, second load voltage; LED1, first light-emitting diode; LED2, second light-emitting diode; LED3, third light-emitting diode; LED4, fourth light-emitting diode; LED5, fifth light-emitting diode; LED6, sixth light-emitting diode; EB, load capacitance; CB, input capacitance; CK, equivalent capacitance; DB, diode; GND, ground terminal; C1, first capacitance; C2, second capacitance; C3, third capacitance; R1, first resistor; R2, second resistor; R3, third resistor. DETAILED DESCRIPTION

[0032] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, and circuits are omitted to prevent unnecessary details from obstructing the description of the present application.

[0033] At present, display screens are usually composed of a power module, a control circuit and a backlight module. The power module is used to provide stable power to the components in the display screen (such as the control circuit, the backlight module, etc.) so that the control circuit and the backlight module can work normally. The control circuit includes a sending card, a receiving card and corresponding software, which is responsible for receiving the video source signal and processing and distributing it so that the display screen can display the corresponding pattern or video.

[0034] Among them, the backlight module is usually composed of a plurality of light-emitting diodes, and the control circuit controls the on and off of different light-emitting diodes so that the display screen can display the corresponding pattern or video. However, the light-emitting diode usually requires a specific driving voltage to ensure efficient and stable light emission, and the power supply voltage (for example, 5 volts or 12 volts) provided by the power module is usually higher than the load voltage of the light-emitting diode. For this reason, a step-down circuit is usually provided in the display screen in the related art, and the step-down circuit is connected to the supply voltage, and the supply voltage is reduced to a preset voltage (i.e., the load voltage of the light-emitting diode) and output to the backlight module. However, at the moment of power-on, the step-down circuit may be short-circuited, resulting in the voltage of the first end of the step-down circuit (one end for outputting the positive load voltage) and the voltage of the second end (one end for outputting the negative load voltage) being at the same potential, thereby causing the negative pressure borne by the backlight module to be too large, resulting in the light-emitting diode in the backlight module being damaged and failing, affecting the display effect of the display screen.

[0035] For example, the display screen 1' in the related art may include a backlight module 11' and a buck circuit 12', wherein a first end of the buck circuit 12' outputs a first load voltage VBL and is connected to one end of the backlight module 11' to provide the first load voltage VBL for the backlight module 11' during operation, and a second end of the buck circuit 12' outputs a second load voltage LED- and the other end of the backlight module 11' is connected. Figure 2 As shown, the step-down circuit 12' includes a load capacitor EB and an input capacitor CB, and the backlight module 11' includes a plurality of light-emitting diodes LED. At the moment of power-on, the flow direction of the first load voltage VBL is as follows: Figure 2 As shown by the dotted arrow, the first load voltage VBL will charge the input capacitor CB. At the same time, the load capacitor EB has no energy at the moment of power-on, that is, the load capacitor EB is in a short-circuit state at the moment of power-on, causing the first load voltage VBL and the second load voltage LED- to rise synchronously and have the same potential. The first load voltage VBL will be directly added to the second load voltage LED-, causing the second load voltage LED- to be in a high-voltage state relative to the ground. At the same time, multiple light-emitting diodes LED are attached to the back plate (for example, a metal conductor) of the display screen to form an equivalent capacitor CK. At this time, the first load voltage VBL will pass through the light-emitting diode LED near the output end of the step-down circuit 12', the equivalent capacitor CK, and then to the ground end GND to form a reverse cutoff loop. The light-emitting diode LED is reversely cut off, that is, the light-emitting diode LED close to the output end of the step-down circuit 12' will be subjected to negative voltage. The negative voltage at the moment of power-on is the high-voltage first load voltage VBL. When the first load voltage VBL exceeds the withstand voltage specification value borne by the light-emitting diode LED and is repeatedly impacted by the light-emitting diode LED for a long time, the light-emitting diode LED will be damaged and fail, resulting in light failure of the backlight module 11', which in turn affects the display effect of the display screen.

[0036] To this end, the present application provides a step-down system, a circuit board and a display screen. The step-down system is capable of dividing the negative pressure flowing to the backlight module to reduce the negative pressure borne by the light-emitting diodes in the backlight module, thereby avoiding the problem of the light-emitting diodes being damaged and failing due to the negative pressure, improving the service life of the light-emitting diodes, and further ensuring the light output reliability of the backlight module, so as to further ensure the display effect of the display screen.

[0037] The voltage reduction system, circuit board and display screen provided in the present application are exemplarily introduced below in conjunction with the accompanying drawings.

[0038] like Figure 3 As shown, the embodiment of the present application provides a display screen 1, including a backlight module 11 and a circuit board 12, the circuit board 12 is electrically connected to the backlight module 11, and the circuit board 12 is used to provide a driving voltage for the backlight module 11, so that the backlight module 11 can ensure efficient and stable light emission, so that the display screen 1 can display normally. Figure 3 As shown, the backlight module 11 generally includes a plurality of light emitting diodes LED connected in series, and the circuit board 12 is electrically connected to the plurality of light emitting diodes LED connected in series to provide a driving voltage for the light emitting diodes LED so that the light emitting diodes LED can ensure efficient and stable light emission.

[0039] Since the supply voltage of the circuit board 12 is usually higher than the load voltage of the light emitting diode LED in the backlight module 11, in order to ensure the light emitting stability of the light emitting diode LED, in one example, Figure 4 As shown, the circuit board 12 provided in the present application is usually also provided with a step-down system 13, which is connected to the backlight module 11. The step-down system 13 is connected to the power supply voltage and converts the power supply voltage into a load voltage. The first end of the step-down system 13 outputs a first load voltage VBL to the anode of the light-emitting diode LED, and the second end of the step-down system 13 outputs a second load voltage LED-, so that the light-emitting diode LED can emit light stably.

[0040] However, at the moment of power-on, the step-down system may be short-circuited, causing the step-down circuit to apply a negative pressure to the backlight module 11, causing the light-emitting diodes LED in the backlight module 11 to be damaged and fail, affecting the display effect of the display screen 1. In order to avoid the above problem, in an example, Figure 5As shown, the step-down system 13 provided in the present application may include a first capacitor C1, a step-down circuit 131 and a voltage divider circuit 132, the first plate of the first capacitor C1 is connected to the first end of the backlight module 11, the second plate of the first capacitor C1 is connected to the second end of the backlight module 11 and the ground terminal GND, the first end of the step-down circuit 131 is used to output the first load voltage VBL, the second end of the step-down circuit 131 is used to output the second load voltage LED-, one end of the voltage divider circuit 132 is connected to the second end of the step-down circuit 131 for connecting the second load voltage LED-, and the other end of the voltage divider circuit 132 is connected to the third end of the backlight module 11.

[0041] Here, it is worth noting that the first end of the backlight module 11 refers to the positive electrode of the first light emitting diode LED, which is used to connect to the first load voltage VBL, and the third end of the backlight module 11 refers to the negative electrode of the last light emitting diode LED, which is used to connect to the second load voltage LED-. Figure 5 As shown, the backlight module 11 may include a first light emitting diode LED1, a second light emitting diode LED2, a third light emitting diode LED3, a fourth light emitting diode LED4, a fifth light emitting diode LED5 and a sixth light emitting diode LED6 which are connected in series in sequence, wherein the anode of the first light emitting diode LED1 is the first end of the backlight module 11, and the cathode of the sixth light emitting diode LED6 is the second end of the backlight module 11.

[0042] In this example, the first load voltage VBL charges the first capacitor C1 at the moment of power-on. When the step-down circuit 131 is short-circuited at the moment of power-on, the second load voltage LED- outputted from the second end of the step-down circuit 131 is in a high voltage state relative to the ground, and is equivalent to the first load voltage VBL and flows to the light-emitting diode LED close to the output end of the step-down circuit 131. At this time, a voltage divider circuit 132 is arranged between the second end of the step-down circuit 131 and the third end of the backlight module 11. The voltage divider circuit 132 can divide the negative pressure flowing to the backlight module 11 to reduce the negative pressure borne by the light-emitting diode LED in the backlight module 11, thereby avoiding the problem that the negative pressure borne by the reverse-cutoff light-emitting diode LED exceeds the withstand voltage specification value that it can withstand, resulting in the light-emitting diode LED being damaged and failing, thereby improving the service life of the light-emitting diode LED, thereby ensuring the light output reliability of the backlight module 11, and further ensuring the display effect of the display screen 1.

[0043] Among them, a plurality of light-emitting diodes LED are usually attached to the back plate of the whole display screen 1. When the display screen 1 adopts a metal conductor, an equivalent capacitor will be formed when the plurality of light-emitting diodes LED are attached to the back plate of the whole display screen 1. At the moment of power-on, the step-down circuit 131, the voltage divider circuit 132, the equivalent capacitor and the first capacitor C1 will form a closed loop. Specifically, at the moment of power-on, the second load voltage LED- output by the second end of the step-down circuit 131 is equivalent to the first load voltage VBL, and the first load voltage VBL will pass through the light-emitting diodes LED (such as the sixth light-emitting diode LED6 and the fifth light-emitting diode LED5) close to the output end of the step-down circuit 131, the equivalent capacitor and then to the ground terminal GND to form a closed loop. Here, it is worth explaining that the equivalent capacitor is formed when the plurality of light-emitting diodes LED are attached to the back plate of the whole display screen 1, and there is no physical component of the equivalent capacitor in the actual circuit.

[0044] When the display screen 1 is made of non-metallic conductor (such as plastic), there is no equivalent capacitor in the circuit. In order to form a closed loop between the step-down circuit 131, the voltage divider circuit 132 and the first capacitor C1, in one example, Figure 6 As shown, the backlight module 11 also includes a second capacitor C2, the first plate of the second capacitor C2 is connected to the fifth light-emitting diode LED5, and the second plate of the second capacitor C2 is connected to the second plate of the first capacitor C1 and the ground terminal GND. In this example, at the moment of power-on, the step-down circuit 131, the voltage divider circuit 132, the second capacitor C2 and the first capacitor C1 will form a closed loop. Specifically, at the moment of power-on, the second load voltage LED- output by the second end of the step-down circuit 131 is equal to the first load voltage VBL, and the first load voltage VBL will pass through the light-emitting diode LED (such as the sixth light-emitting diode LED6 and the fifth light-emitting diode LED5) close to the output end of the step-down circuit 131, the second capacitor C2 and then to the ground terminal GND to form a closed loop.

[0045] Optional, see Figure 6 and Figure 7 The voltage divider circuit 132 includes a diode DB, the cathode of the diode DB is connected to the second end of the step-down circuit 131, and the anode of the diode DB is connected to the third end of the backlight module 11 (ie, Figure 6When the second load voltage LED- output by the second end of the step-down circuit 131 is in a high voltage state relative to the ground and flows to the sixth light-emitting diode LED6, the diode DB will divide the voltage to reduce the negative pressure borne by the sixth light-emitting diode LED6, thereby avoiding the problem that the negative pressure borne by the reverse-cutoff sixth light-emitting diode LED6 exceeds the withstand voltage specification value it can withstand, causing the sixth light-emitting diode LED6 to be damaged and fail, thereby improving the service life of the light-emitting diode LED. In addition, the diode DB is small in size, low in cost, and simple to prepare.

[0046] When the voltage divider circuit 132 includes a diode DB, as shown in FIG. Figure 7 As shown, the voltage divider circuit 132 further forms a third capacitor C3, the first plate of the third capacitor C3 is connected to the positive electrode of the diode DB and the third end of the backlight module 11, the second plate of the third capacitor C3 is connected to the negative electrode of the diode DB and the second end of the step-down circuit 131, it can be understood that the third capacitor C3 is the junction capacitance of the diode DB, similarly, the backlight module 11 includes N light-emitting diodes LED, each light-emitting diode LED is correspondingly provided with a junction capacitance, that is, the third capacitor C3 and Figure 7 The junction capacitance Cn, junction capacitance Cn-1, etc. shown in are all equivalent capacitances formed, and there are no physical components of equivalent capacitance in the actual circuit. At the moment of power-on, the first load voltage VBL and the second load voltage LED- are synchronously raised and have the same potential, so the negative voltage flowing to the backlight module 11 is equivalent to the first load voltage VBL. In this example, at the moment of power-on, when the first load voltage VBL flows to the backlight module 11, most of the voltage of the first load voltage VBL will be applied to the third capacitor C3 to reduce the negative pressure borne by the light-emitting diode LED in the backlight module 11, thereby avoiding the problem that the negative pressure borne by the reverse-cutoff light-emitting diode LED exceeds the withstand voltage specification value that it can withstand, causing the light-emitting diode LED to be damaged and fail, thereby improving the service life of the light-emitting diode LED, thereby ensuring the light output reliability of the backlight module 11, and further ensuring the display effect of the display screen 1.

[0047] Optionally, the voltage divider circuit 132 may also be other circuits or devices that can achieve the above functions, and this application does not make any specific limitation on this.

[0048] In one example, if Figure 8 As shown, the step-down circuit 131 may include a fourth capacitor C4, a first resistor R1 and a second resistor R2. The first plate of the fourth capacitor C4 is connected to the first load voltage VBL, and the second plate of the fourth capacitor C4 is connected to one end of the voltage divider circuit 132 (i.e., Figure 8The first load voltage VBL and the second load voltage LED-are connected to each other at the same potential, and the first load voltage VBL is directly added to the second load voltage LED-, causing the second load voltage LED- to be in a high voltage state relative to the ground.

[0049] When the negative voltage outputted by the step-down circuit 131 to the backlight module 11 is a low voltage, the voltage divider circuit 132 may not be required to divide the negative voltage. For this purpose, in one example, Fig. 9 As shown, the voltage reduction system 13 provided in the present application further includes a voltage stabilizing circuit 133, one end of the voltage stabilizing circuit 133 is connected to the second end of the voltage reduction circuit 131 (ie, Fig. 9 The second electrode plate of the fourth capacitor C4 and the other end of the second resistor R2) and one end of the voltage divider circuit 132 (ie, Figure 8 The other end of the voltage stabilizing circuit 133 is connected to the third end of the backlight module 11. When the negative voltage output by the step-down circuit 131 to the backlight module 11 is a low voltage, the voltage divider circuit 132 can be short-circuited by the voltage stabilizing circuit 133, so that the voltage output by the step-down circuit 131 will flow to the sixth light-emitting diode LED6 in the backlight module 11 through the voltage stabilizing circuit 133, so as to ensure the reliability of voltage transmission and save a certain cost.

[0050] Optional, such as Fig.10 As shown, the voltage stabilizing circuit 133 may include a third resistor R3, one end of the third resistor R3 is connected to the second end of the step-down circuit 131 and one end of the voltage divider circuit 132, and the other end of the third resistor R3 is connected to the other end of the voltage divider circuit 132 and the third end of the backlight module 11.

[0051] Optional, such as Fig.11 As shown, the voltage stabilizing circuit 133 may include a magnetic bead unit 1331, one end of the magnetic bead unit 1331 is connected to the second end of the step-down circuit 131 and one end of the voltage divider circuit 132, and the other end of the magnetic bead unit 1331 is connected to the other end of the voltage divider circuit 132 and the third end of the backlight module 11.

[0052] Optional, such as Fig.12As shown, the voltage stabilizing circuit 133 may also include a third resistor R3 and a magnetic bead unit 1331 at the same time, one end of the third resistor R3 is also connected to one end of the magnetic bead unit 1331, and the other end of the third resistor R3 is also connected to the other end of the magnetic bead unit 1331. The specific setting components of the voltage stabilizing circuit 133 can be set according to actual needs, and this application does not make any specific restrictions on this.

[0053] Here, it can be understood that when the negative voltage output by the step-down circuit 131 to the backlight module 11 is a low voltage, there is no need to set up the voltage divider circuit 132 in the step-down system 13, but a voltage stabilizing circuit 133 is directly added between the second end of the step-down circuit 131 and one end of the voltage divider circuit 132 and the third end of the backlight module 11, so that the voltage output by the step-down circuit 131 will flow to the sixth light-emitting diode LED6 in the backlight module 11 through the voltage stabilizing circuit 133, so as to ensure the reliability of voltage transmission and further save certain costs.

[0054] Optionally, the buck circuit 131 may adopt a DC-DC conversion circuit, such as a BUCK buck circuit. The energy loss during the conversion process of the BUCK buck circuit is small and the conversion efficiency is high. At the same time, the BUCK buck circuit can flexibly adjust the load voltage by changing the duty cycle of the switch to adapt to the different load requirements of the backlight module 11. The buck circuit 131 may also adopt other circuits or devices that can achieve the above functions. This application does not make any specific restrictions on this.

[0055] Optionally, other control systems or circuits may be provided on the circuit board 12, and this application does not impose any specific limitation on this.

[0056] In summary, when there is a short circuit problem in the buck circuit 131, causing the buck circuit 131 to output a high-voltage first load voltage VBL to the light-emitting diode LED near the output end of the buck circuit 131, the voltage divider circuit 132 in the buck system 13 provided in the present application can divide the negative pressure flowing to the backlight module 11 to reduce the negative pressure borne by the light-emitting diode LED in the backlight module 11, thereby avoiding the problem that the negative pressure borne by the reverse-cutoff light-emitting diode LED exceeds the withstand voltage specification value it can withstand, causing the light-emitting diode LED to be damaged and fail, thereby improving the service life of the light-emitting diode LED, and further ensuring the light output reliability of the backlight module 11, so as to further ensure the display effect of the display screen 1.

[0057] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0058] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0059] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0060] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0061] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A step-down system, applied to a backlight module, wherein the backlight module comprises a plurality of light-emitting diodes connected in series, characterized in that: The pressure reduction system comprises: A first capacitor, wherein a first electrode plate of the first capacitor is connected to a first end of the backlight module, and a second electrode plate of the first capacitor is connected to a second end of the backlight module and a ground end; a step-down circuit, a first end of which is connected to a first end of the backlight module and is used to output a first load voltage; and A voltage divider circuit, one end of which is connected to the second end of the step-down circuit for receiving a second load voltage output by the step-down circuit, and the other end of which is connected to the third end of the backlight module.

2. The pressure reduction system according to claim 1, characterized in that: The backlight module further includes a second capacitor, a first electrode plate of the second capacitor is connected to one of the light emitting diodes, and a second electrode plate of the second capacitor is connected to the second electrode plate of the first capacitor and the ground terminal; The step-down circuit, the voltage divider circuit, the light-emitting diode and the second capacitor form a closed loop.

3. The pressure reduction system according to claim 1, characterized in that: The voltage divider circuit comprises: A diode, wherein a cathode of the diode is connected to the second end of the step-down circuit, and an anode of the diode is connected to the third end of the backlight module.

4. The pressure reduction system according to claim 1, characterized in that: The step-down circuit comprises: a fourth capacitor, wherein a first plate of the fourth capacitor is connected to the first load voltage, and a second plate of the fourth capacitor is connected to one end of the voltage divider circuit; a first resistor, one end of which is connected to the first electrode plate of the fourth capacitor; and A second resistor, one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is connected to the second plate of the fourth capacitor and one end of the voltage divider circuit.

5. The pressure reduction system according to any one of claims 1 to 4, characterized in that: The depressurization system further comprises: A voltage stabilizing circuit, one end of which is connected to the second end of the step-down circuit and one end of the voltage divider circuit, and the other end of which is connected to the third end of the backlight module.

6. The pressure reduction system according to claim 5, characterized in that: The voltage stabilizing circuit comprises: A third resistor, one end of the third resistor is connected to the second end of the step-down circuit and one end of the voltage divider circuit, and the other end of the third resistor is connected to the third end of the backlight module.

7. The pressure reduction system according to claim 5, characterized in that: The voltage stabilizing circuit comprises: A magnetic bead unit, one end of which is connected to the second end of the step-down circuit and one end of the voltage divider circuit, and the other end of which is connected to the third end of the backlight module.

8. A circuit board, characterized in that: Comprising the pressure reduction system as described in any one of claims 1-7.

9. A display screen, characterized in that: include: A backlight module, wherein the backlight module comprises a plurality of light emitting diodes connected in series; as well as, The circuit board as claimed in claim 8, wherein the circuit board is electrically connected to the backlight module.

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