Backlight driving circuit, backlight module, LCD display screen and electronic equipment

Abstract

The utility model provides a backlight driving circuit, a backlight module, an LCD display screen and electronic equipment, and relates to the technical field of display. The backlight driving circuit comprises a driving chip, an over-current protection circuit, a voltage boosting and stabilizing circuit and a fly-wheel diode. The first end of the overcurrent protection circuit is electrically connected with the output end of the power supply, and the second end of the overcurrent protection circuit is electrically connected with the first end of the boost voltage stabilizing circuit. Wherein the over-current protection circuit detects a second current flowing through the over-current protection circuit in real time and is automatically disconnected when the second current is greater than a first preset current so as to disconnect the power supply from the boost voltage stabilizing circuit, and the first preset current is the current flowing through the over-current protection circuit when the backlight driving circuit works normally. According to the backlight driving circuit, the voltage boosting and stabilizing circuit in the backlight driving circuit can be prevented from being damaged by large current in the backlight driving circuit, and the use reliability and safety of the backlight driving circuit are effectively improved.

Description

Technical Field

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

[0002] With the continuous development of liquid crystal display technology, LCD backlight modules have been widely used in various electronic products, industrial control equipment, and automotive terminals due to their advantages such as good display effect, low power consumption, and compact structure. To ensure the normal display of the LCD backlight module, its internal backlight lamps usually need to be provided with a stable constant current power supply through a backlight driver circuit.

[0003] In related technologies, to reduce the overall size of the device, the backlight driver circuit and backlight are typically designed in a compact manner. The backlight driver circuit is integrated on the substrate and connected to the backlight via a board-to-board connector (BTB connector) and a flexible printed circuit (FPC). In practical applications, since the connection between the backlight driver circuit and the backlight is usually done manually on the production line, improper operation or the presence of metal dust or foreign objects inside the connector may cause a short circuit due to grounding of the backlight's positive terminal. This short circuit will generate a large instantaneous current within the backlight driver circuit, which may cause some components in the backlight driver circuit to overheat and burn out, leading to backlight driver circuit failure, affecting the normal operation of the electronic device, and even posing electrical safety hazards.

[0004] Therefore, the existing backlight driving circuit has the risk of instantaneous high current caused by short circuit faults, which can easily lead to the burnout of the backlight driving circuit, and this is an urgent problem that needs to be solved. Utility Model Content

[0005] This application provides a backlight driving circuit, a backlight module, an LCD display screen, and an electronic device, which can provide overcurrent protection for the backlight driving circuit when a short circuit fault occurs in the backlight, preventing the components in the backlight driving circuit from overheating and burning out, thereby ensuring the stability and safety of the electronic device.

[0006] In a first aspect, this application provides a backlight driving circuit, which includes a driving chip, an overcurrent protection circuit, a boost regulator circuit, and a freewheeling diode.

[0007] The first terminal of the overcurrent protection circuit is electrically connected to the output terminal of the power supply, and the second terminal of the overcurrent protection circuit is electrically connected to the first terminal of the boost regulator circuit; the power supply is used to output the first voltage.

[0008] The second terminal of the boost regulator circuit is electrically connected to the first terminal of the driver chip. The third terminal of the boost regulator circuit is electrically connected to the second terminal of the driver chip and the first terminal of the freewheeling diode. The fourth terminal of the boost regulator circuit is electrically connected to the second terminal of the freewheeling diode. The connection point between the fourth terminal of the boost regulator circuit and the second terminal of the freewheeling diode is a first common terminal, which is electrically connected to the first terminal of the connector.

[0009] The third terminal of the driver chip is electrically connected to the first terminal of the controller, and the fourth terminal of the driver chip is electrically connected to the second terminal of the connector. The third and fourth terminals of the connector are electrically connected to the backlight via a flexible printed circuit board.

[0010] The boost regulator circuit is used to boost the first voltage and stably output the second voltage; the driver chip is used to receive the control signal output by the controller and provide a first current to the backlight according to the control signal and the second voltage; the overcurrent protection circuit is used to disconnect the power supply from the boost regulator circuit when the second current flowing through the overcurrent protection circuit is greater than a first preset current, wherein the first preset current is the current flowing through the overcurrent protection circuit when the backlight driver circuit is working normally.

[0011] This application provides a backlight driving circuit, which includes a driver chip, an overcurrent protection circuit, a boost regulator circuit, and a freewheeling diode. The first terminal of the overcurrent protection circuit is electrically connected to the output terminal of the power supply. The second terminal of the overcurrent protection circuit is electrically connected to the first terminal of the boost regulator circuit. The second terminal of the boost regulator circuit is electrically connected to the first terminal of the driver chip. The third terminal of the boost regulator circuit is electrically connected to both the second terminal of the driver chip and the first terminal of the freewheeling diode. The fourth terminal of the boost regulator circuit is electrically connected to the second terminal of the freewheeling diode. The connection point between the fourth terminal of the boost regulator circuit and the second terminal of the freewheeling diode is a first common terminal, which is electrically connected to the first terminal of a connector. The third terminal of the driver chip is electrically connected to the first terminal of the controller, and the fourth terminal of the driver chip is electrically connected to the second terminal of the connector. The third and fourth terminals of the connector are electrically connected to the backlight via a flexible printed circuit board. The overcurrent protection circuit detects the second current flowing through it in real time and automatically disconnects when the second current exceeds the first preset current, thereby disconnecting the power supply from the boost regulator circuit. The first preset current is the current flowing through the overcurrent protection circuit when the backlight driver circuit is operating normally. This application can prevent the boost regulator circuit in the backlight driver circuit from being damaged by the large current in the backlight driver circuit, effectively improving the reliability and safety of the backlight driver circuit.

[0012] In one possible design, the overcurrent protection circuit includes a PTC thermistor;

[0013] The first end of the PTC thermistor is electrically connected to the output end of the power supply, and the second end of the PTC thermistor is electrically connected to the first end of the boost regulator circuit.

[0014] In one possible design, the overcurrent protection circuit includes a current-limiting load switch;

[0015] The first terminal of the current-limiting load switch is electrically connected to the output terminal of the power supply, and the second terminal of the current-limiting load switch is electrically connected to the first terminal of the boost voltage regulator circuit.

[0016] In one possible design, the boost regulator circuit includes a boost module, a first regulator module, and a second regulator module;

[0017] The first terminal of the first voltage regulator module is electrically connected to the second terminal of the overcurrent protection circuit, and the second terminal of the first voltage regulator module is electrically connected to the ground terminal; the connection terminal between the first terminal of the first voltage regulator module and the second terminal of the overcurrent protection circuit is the second common terminal.

[0018] The first terminal of the boost module is electrically connected to the second common terminal and the first terminal of the driver chip, respectively, and the second terminal of the boost module is electrically connected to the second terminal of the driver chip and the first terminal of the freewheeling diode, respectively.

[0019] The first terminal of the second voltage regulator module is electrically connected to the second terminal of the freewheeling diode, and the second terminal of the second voltage regulator module is electrically connected to the ground terminal.

[0020] In one possible design, the boost module includes a boost inductor;

[0021] The first terminal of the boost inductor is electrically connected to the second common terminal and the first terminal of the driver chip, respectively, and the second terminal of the boost inductor is electrically connected to the second terminal of the driver chip and the first terminal of the freewheeling diode, respectively.

[0022] In one possible design, the first voltage regulator module includes a first capacitor, a first terminal of which is electrically connected to a second terminal of the overcurrent protection circuit, and a second terminal of which is electrically connected to the ground terminal.

[0023] The second voltage regulator module includes a second capacitor, the first end of which is electrically connected to the second end of the freewheeling diode, and the second end of which is electrically connected to the ground terminal.

[0024] In one possible design, the backlight driving circuit further includes a current limiting circuit;

[0025] The first terminal of the current limiting circuit is electrically connected to the fourth terminal of the driver chip, and the second terminal of the current limiting circuit is electrically connected to the ground terminal.

[0026] The current limiting circuit is used to limit the first current so that the first current is less than the second preset current.

[0027] In a second aspect, this application provides a backlight module, including a substrate, a flexible printed circuit board and a backlight lamp, as well as a backlight driving circuit disposed on the substrate as described in the first aspect and any possible design of the first aspect.

[0028] The output of the backlight driving circuit is electrically connected to the backlight lamp via a connector and the flexible printed circuit board.

[0029] Thirdly, this application provides an LCD display screen, including a liquid crystal panel and a backlight module as described in the second aspect above.

[0030] Fourthly, this application provides an electronic device including an LCD display screen as described in the third aspect above.

[0031] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0032] Figure 1 This is a circuit block diagram of a backlight driving circuit provided in an embodiment of this application.

[0033] Figure 2 A circuit block diagram of another backlight driving circuit provided in an embodiment of this application.

[0034] Figure 3 This is a circuit schematic diagram of a backlight driving circuit provided in an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 10. Backlight driving circuit;

[0037] 11. Driver chip; 12. Overcurrent protection circuit; 13. Boost regulator circuit; 14. Freewheeling diode;

[0038] 131. Boost module; 132. First voltage regulator module; 133. Second voltage regulator module;

[0039] 20. Power supply;

[0040] 30. Controller;

[0041] 40. Connector;

[0042] 50. Flexible printed circuit boards;

[0043] 60. Backlight. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the 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, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims and drawings of this application are intended to cover non-exclusive inclusion.

[0046] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0047] Furthermore, the terms "first," "second," etc., in the specification and claims of this application or in the aforementioned drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.

[0048] In the description of this application, unless otherwise stated, "multiple" means two or more (including two), and similarly, "multiple groups" means two or more (including two groups).

[0049] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, "connection" or "joining" in mechanical structures can refer to a physical connection, such as a fixed connection, for example, a connection fixed by a partition, such as a connection fixed by screws, bolts, or other partitions; a physical connection can also be a detachable connection, such as a snap-fit ​​or interlocking connection; a physical connection can also be an integral connection, such as a connection formed by welding, bonding, or integral molding. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0050] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0051] Figure 1 This is a circuit block diagram of a backlight driving circuit provided in an embodiment of this application. Figure 1 As shown, the backlight driving circuit 10 includes a driving chip 11, an overcurrent protection circuit 12, a boost regulator circuit 13, and a freewheeling diode 14.

[0052] The first terminal of the overcurrent protection circuit 12 is electrically connected to the output terminal of the power supply 20, and the second terminal of the overcurrent protection circuit 12 is electrically connected to the first terminal of the boost voltage regulator circuit 13; the power supply 20 is used to output the first voltage.

[0053] The overcurrent protection circuit 12 is used to disconnect the power supply 20 from the boost voltage regulator circuit 13 when the second current flowing through the overcurrent protection circuit 12 is greater than the first preset current.

[0054] It should be noted that the first preset current is the current flowing through the current protection circuit 12 when the backlight driving circuit 10 is working normally.

[0055] The overcurrent protection circuit 12 is used to detect the second current flowing through the overcurrent protection circuit 12 in real time.

[0056] When the second current is less than or equal to the first preset current, the overcurrent protection circuit 12 remains in a normal conducting state, and the backlight driving circuit 10 operates normally.

[0057] When the second current exceeds the first preset current, the overcurrent protection circuit 12 automatically disconnects, thereby disconnecting the power supply 20 from the boost regulator circuit 13, to prevent the excessive second current from causing the boost regulator circuit 13 to overheat and burn out.

[0058] Figure 3 This is a circuit schematic diagram of a backlight driving circuit provided in an embodiment of this application. Figure 3 As shown, in one possible embodiment, the overcurrent protection circuit 12 includes a PTC thermistor R1.

[0059] The first terminal of the PTC thermistor R1 is electrically connected to the output terminal of the power supply 20, and the second terminal of the PTC thermistor R1 is electrically connected to the first terminal of the boost regulator circuit 13.

[0060] Specifically, for a positive temperature coefficient (PTC) thermistor, when the second current flowing through the PTC thermistor R1 is less than or equal to the first preset current, the resistance of the PTC thermistor R1 is at its normal value, allowing normal current flow. When the second current flowing through the PTC thermistor R1 exceeds the first preset current, the temperature of the PTC thermistor R1 will rise rapidly. As the temperature of the PTC thermistor R1 rises, its resistance increases sharply, and the PTC thermistor R1 cuts off the second current, thereby disconnecting the boost regulator circuit 13 from the power supply 20, protecting the boost regulator circuit 13 from damage due to the excessive second current.

[0061] It should be noted that after the PTC thermistor R1 cuts off the second current, if the second current is less than the first preset current, the temperature of the PTC thermistor R1 will gradually return to normal, the resistance of the PTC thermistor R1 will also return to normal, and the backlight driving circuit 10 will work normally.

[0062] In practical applications, the PTC thermistor R1 can be a PTC thermistor with model number LP-HSML050.

[0063] The holding current I of the PTC thermistor R1 H The holding current I of the PTC thermistor R1 is 0.50 amperes (A). H This is the maximum current value at which the PTC thermistor R1 will not trip due to overcurrent at an ambient temperature of 25℃.

[0064] The tripping current I of the PTC thermistor R1 T The trip current I of the PTC thermistor R1 is 1.00 amperes (A). T This is the minimum current required for the PTC thermistor R1 to activate its overcurrent protection function at an ambient temperature of 25°C. When the second current flowing through the PTC thermistor R1 reaches 1.00A, the PTC thermistor R1 will immediately limit the current flow and disconnect the boost regulator circuit 13 from the power supply 20 to prevent damage to the boost regulator circuit 13 due to overcurrent. The first preset current can be 1.00A.

[0065] The maximum withstand voltage Vmax of the PTC thermistor R1 is 6 volts (V). The maximum withstand voltage Vmax of the PTC thermistor R1 is the maximum voltage that the PTC thermistor R1 can withstand without damage at its rated current. That is, when the first voltage is below 6V, the PTC thermistor R1 can operate normally and withstand the rated current.

[0066] The maximum fault current I_max of the PTC thermistor R1 is 3.00 amperes (A). The maximum fault current I_max of the PTC thermistor R1 is the maximum fault current that the PTC thermistor R1 can withstand, that is, the maximum current value that the PTC thermistor R1 can withstand without being damaged in the event of an excessive current fault.

[0067] The trip time (Ttrip) of the PTC thermistor R1 is 0.10 seconds (s). The trip time (Ttrip) of the PTC thermistor R1 is the time required for the PTC thermistor R1 to automatically disconnect the circuit when it detects an overcurrent.

[0068] Typical power dissipation Pd of PTC thermistor R1 typ The typical power dissipation of the PTC thermistor R1 is 0.50 watts (W). typ This represents the power consumed by the PTC thermistor R1 under normal operating conditions, indicating the typical power consumption of the PTC thermistor R1 at rated current when the ambient temperature is 25℃.

[0069] The minimum resistance R of the PTC thermistor R1 min The minimum resistance R of the PTC thermistor R1 is 0.05 ohms (Ω). min This is the lowest resistance value of the PTC thermistor R1 at an ambient temperature of 25℃.

[0070] The maximum resistance R1 of the PTC thermistor is R max The resistance is 0.80 ohms (Ω). The maximum resistance R of the PTC thermistor R1 is... max This is the maximum resistance of the PTC thermistor R1 before it trips.

[0071] In this embodiment, a PTC thermistor is used as an overcurrent protection circuit. Utilizing the positive temperature coefficient characteristic of the PTC thermistor, the connection between the power supply and the boost regulator circuit can be automatically disconnected when the second current exceeds the first preset current. This prevents the boost regulator circuit in the backlight driver circuit from being damaged due to overcurrent. The overcurrent protection circuit has a simple circuit structure and effectively improves the reliability of the backlight driver circuit.

[0072] In yet another possible embodiment, the overcurrent protection circuit 12 includes a current-limiting load switch.

[0073] The first terminal of the current-limiting load switch is electrically connected to the output terminal of the power supply 20, and the second terminal of the current-limiting load switch is electrically connected to the first terminal of the boost regulator circuit 13.

[0074] The current-limiting load switch has a built-in overcurrent detection circuit, which can detect the second current flowing through it in real time.

[0075] In practical applications, the ETA6027 current-limiting load switch can be selected. In this case, the first terminal of the current-limiting load switch is the IN pin, and the second terminal is the OUT pin.

[0076] In addition, the nFAULT pin of the current-limiting load switch is a fault indication pin. The nFAULT pin of the current-limiting load switch can also be electrically connected to the second terminal of the controller 30 to indicate to the controller 30 whether the current-limiting load switch is in a fault state.

[0077] When the second current flowing through the current-limiting load switch exceeds the first preset current, the current-limiting load switch turns off, and its nFAULT pin outputs a low-level signal to the controller 30 to indicate that the current-limiting load switch has entered overcurrent protection mode. When the second current flowing through the current-limiting load switch is less than or equal to the first preset current, the current-limiting load switch remains in normal conduction mode, and its nFAULT pin outputs a high-level signal to the controller 30 to indicate that the current-limiting load switch is in normal conduction mode.

[0078] By electrically connecting the nFAULT pin of the current-limiting load switch to the controller 30, the controller 30 can promptly detect whether an overcurrent has occurred in the backlight drive circuit 10.

[0079] The EN pin of the current-limiting load switch is the enable pin. The EN pin of the current-limiting load switch can also be electrically connected to the third terminal of the controller 30 so that the controller 30 can selectively control the current-limiting load switch to be turned on or off.

[0080] The second terminal of the boost regulator circuit 13 is electrically connected to the first terminal of the driver chip 11. The third terminal of the boost regulator circuit 13 is electrically connected to the second terminal of the driver chip 11 and the first terminal of the freewheeling diode 14. The fourth terminal of the boost regulator circuit 13 is electrically connected to the second terminal of the freewheeling diode 14. The connection between the fourth terminal of the boost regulator circuit 13 and the second terminal of the freewheeling diode 14 is the first common terminal, which is electrically connected to the first terminal of the connector 40.

[0081] The boost regulator circuit 13 is used to boost the first voltage and stabilize the output of the second voltage.

[0082] It should be noted that the boost regulator circuit 13 is used to boost and regulate the first voltage provided by the power supply 20 to stabilize the output of the second voltage and provide the second voltage to the driver chip 11.

[0083] Figure 2 A circuit block diagram of another backlight driving circuit provided in an embodiment of this application. (See diagram below.) Figure 2 As shown, in one possible embodiment, the boost regulator circuit 13 includes a boost module 131, a first regulator module 132, and a second regulator module 133.

[0084] The first terminal of the first voltage regulator module 132 is electrically connected to the second terminal of the overcurrent protection circuit 12, and the second terminal of the first voltage regulator module 132 is electrically connected to the ground terminal. The connection point between the first terminal of the first voltage regulator module 132 and the second terminal of the overcurrent protection circuit 12 is the second common terminal.

[0085] The first voltage regulator module 132 includes a first capacitor C1.

[0086] It should be noted that one end of the first capacitor C1 is the first end of the first voltage regulator module 132, and the first end of the first voltage regulator module 132 is the first end of the boost voltage regulator circuit 13, that is, one end of the first capacitor C1 is the first end of the boost voltage regulator circuit 13.

[0087] Specifically, one end of the first capacitor C1 is electrically connected to the second end of the overcurrent protection circuit 12, and the other end of the first capacitor C1 is grounded.

[0088] In this embodiment, since the voltage output (first voltage) of the overcurrent protection circuit 12 may contain certain fluctuations or pulses, the first capacitor C1, by storing and releasing electrical energy, can provide a stable voltage input to the boost module 131, ensuring that the boost module 131 can operate stably and avoiding negative impacts from voltage fluctuations on the boost module 131. Simultaneously, the first capacitor C1 also acts as a filter, effectively removing high-frequency noise and pulsations that may appear in the first voltage, reducing voltage noise, and ensuring that the boost module 131 can obtain a stable and clean voltage input, thereby improving the overall stability and operational reliability of the backlight driving circuit 10.

[0089] The first terminal of the boost module 131 is electrically connected to the second common terminal and the first terminal of the driver chip 11, respectively, and the second terminal of the boost module 131 is electrically connected to the second terminal of the driver chip 11 and the first terminal of the freewheeling diode 14, respectively.

[0090] The boost module 131 includes a boost inductor L1.

[0091] It should be noted that one end of the boost inductor L1 is the first end of the boost module 131, and the first end of the boost module 131 is the second end of the boost regulator circuit 13, that is, one end of the boost inductor L1 is the second end of the boost regulator circuit 13. The other end of the boost inductor L1 is the second end of the boost module 131, and the second end of the boost module 131 is the third end of the boost regulator circuit 13, that is, the other end of the boost inductor L1 is the third end of the boost regulator circuit 13.

[0092] Driver chip 11 is a driver chip with model number AW9962EDNR. The first terminal of driver chip 11 is the VIN pin of driver chip 11. The second terminal of driver chip 11 is the SW pin of driver chip 11.

[0093] like Figure 3 As shown, freewheeling diode 14 is freewheeling diode D1. The first terminal of freewheeling diode 14 is the positive terminal of freewheeling diode 14.

[0094] Specifically, one end of the boost inductor L1 is electrically connected to the second common terminal and the VIN pin of the driver chip 11, and the other end of the boost inductor L1 is electrically connected to the SW pin of the driver chip 11 and the positive terminal of the freewheeling diode 14.

[0095] In this embodiment, the boost inductor L1 is used to raise the first voltage, which has been regulated and filtered by the first capacitor C1, to a second voltage through electromagnetic induction. The second voltage is the voltage required to drive the backlight 60 to work.

[0096] The first terminal of the second voltage regulator module 133 is electrically connected to the second terminal of the freewheeling diode 14, and the second terminal of the second voltage regulator module 133 is electrically connected to the ground terminal.

[0097] The second voltage regulator module 133 includes a second capacitor C2. The second terminal of the freewheeling diode 14 is the negative terminal of the freewheeling diode 14.

[0098] It should be noted that one end of the second capacitor C2 is the first end of the second voltage regulator module 133, and the first end of the second voltage regulator module 133 is the fourth end of the boost voltage regulator circuit 13, that is, one end of the second capacitor C2 is the fourth end of the boost voltage regulator circuit 13.

[0099] Specifically, one end of the second capacitor C2 is electrically connected to the negative terminal of the freewheeling diode 14, and the other end of the second capacitor C2 is grounded.

[0100] In this embodiment, since the voltage output by the boost module 131 (the second voltage) may contain certain fluctuations or pulses, the second capacitor C2 can stabilize the second voltage by storing and releasing electrical energy, thus preventing the fluctuations of the second voltage from negatively affecting the normal operation of the backlight 60. Simultaneously, the second capacitor C2 also acts as a filter, effectively removing high-frequency noise and pulsations that may appear in the second voltage, reducing voltage noise, and ensuring that the backlight 60 receives a stable and clean voltage input, thereby improving the overall stability and reliability of the backlight drive circuit 10.

[0101] The third terminal of the driver chip 11 is electrically connected to the first terminal of the controller 30, and the fourth terminal of the driver chip 11 is electrically connected to the second terminal of the connector 40. The third and fourth terminals of the connector 40 are electrically connected to the backlight 60 through the flexible printed circuit board 50.

[0102] It should be noted that the third terminal of the driver chip 11 is the CTRL pin of the driver chip 11, and the fourth terminal of the driver chip 11 is the FB pin of the driver chip 11.

[0103] Connector 40 is a circuit board to circuit board connector.

[0104] The driver chip 11 is used to receive the control signal output by the controller 30 and provide a first current to the backlight 60 according to the control signal and the second voltage.

[0105] It should be noted that the control signal output by the controller 30 is a PWM signal. The driver chip 11 can adjust the magnitude of the first current output by the driver chip 11 based on the duty cycle of the PWM signal, thereby adjusting the brightness of the backlight 60.

[0106] In this configuration, the signal output from the first common terminal is the LED+ signal, and the signal output from the fourth terminal of the driver chip 11 is the LED- signal. That is, the first terminal of connector 40 is connected to the LED+ signal, and the second terminal of connector 40 is connected to the LED- signal. In this case, the third terminal of connector 40 outputs the LED+ signal to the flexible printed circuit board 50 and connects to the positive terminal of the backlight 60 through the flexible printed circuit board 50; the fourth terminal of connector 40 outputs the LED- signal to the flexible printed circuit board 50 and connects to the negative terminal of the backlight 60 through the flexible printed circuit board 50.

[0107] It should be noted that the specific structure of the backlight driving circuit 10 connected to the backlight 60 through the connector 40 and the flexible printed circuit board 50 is the same as the structure of the backlight driving circuit connected to the backlight through the connector and the flexible printed circuit board in the prior art, and will not be described again in this embodiment.

[0108] In this embodiment, when the production line operator attaches the FPC in the backlight module to the substrate via the BTB connector, if the attachment is not properly secured due to operator error, or if there is metal dust or foreign matter inside the BTB connector, the LED+ signal inside the BTB connector will be directly short-circuited. At this time, the second current flowing through the overcurrent protection circuit 12 will rapidly increase to exceed the first preset current. The overcurrent protection circuit 12 will then quickly disconnect, and the first voltage will no longer pass through the boost module 131, effectively preventing damage to the boost module 131 from the instantaneous high current, thereby preventing the backlight driving circuit 10 from burning out. When the second current flowing through the overcurrent protection circuit 12 returns to less than or equal to the first preset current, the overcurrent protection circuit 12 automatically resumes its conducting state, and the backlight driving circuit 10 can operate normally.

[0109] It should be noted that using the backlight driving circuit provided in this application can effectively solve the problem of overheating and burning of certain components in the backlight driving circuit due to improper operation during the assembly process, thus saving production line maintenance costs. After the assembly is completed, if the LCD screen does not display anything, production line operators only need to reconnect the FPC and base station or clean the BTB connector to restore normal LCD display.

[0110] This application provides a backlight driving circuit, which includes a driver chip, an overcurrent protection circuit, a boost regulator circuit, and a freewheeling diode. The first terminal of the overcurrent protection circuit is electrically connected to the output terminal of the power supply. The second terminal of the overcurrent protection circuit is electrically connected to the first terminal of the boost regulator circuit. The second terminal of the boost regulator circuit is electrically connected to the first terminal of the driver chip. The third terminal of the boost regulator circuit is electrically connected to both the second terminal of the driver chip and the first terminal of the freewheeling diode. The fourth terminal of the boost regulator circuit is electrically connected to the second terminal of the freewheeling diode. The connection point between the fourth terminal of the boost regulator circuit and the second terminal of the freewheeling diode is a first common terminal, which is electrically connected to the first terminal of a connector. The third terminal of the driver chip is electrically connected to the first terminal of the controller, and the fourth terminal of the driver chip is electrically connected to the second terminal of the connector. The third and fourth terminals of the connector are electrically connected to the backlight via a flexible printed circuit board. The overcurrent protection circuit detects the second current flowing through it in real time and automatically disconnects when the second current exceeds the first preset current, thereby disconnecting the power supply from the boost regulator circuit. The first preset current is the current flowing through the overcurrent protection circuit when the backlight driver circuit is operating normally. This application can prevent the boost regulator circuit in the backlight driver circuit from being damaged by the large current in the backlight driver circuit, effectively improving the reliability and safety of the backlight driver circuit.

[0111] like Figure 2 As shown, in one possible embodiment, the backlight driving circuit 10 further includes a current limiting circuit 15.

[0112] The first terminal of the current limiting circuit 15 is electrically connected to the fourth terminal of the driver chip 11, and the second terminal of the current limiting circuit 15 is electrically connected to the ground terminal.

[0113] like Figure 3 As shown, it should be noted that the current limiting circuit 15 includes a current limiting resistor R2. One end of the current limiting resistor R2 is the first end of the current limiting circuit 15, and the other end of the current limiting resistor R2 is the second end of the current limiting circuit 15.

[0114] Specifically, one end of the current-limiting resistor R2 is electrically connected to the fourth terminal of the driver chip 11, and the other end of the current-limiting resistor R2 is grounded.

[0115] The current limiting circuit 15 is used to limit the first current so that the first current is less than the second preset current.

[0116] It should be noted that the second preset current is the maximum current that the backlight drive circuit 10 is allowed to provide to the backlight lamp 60, as preset by the user.

[0117] In this embodiment, the first current is limited by a current limiting circuit so that the first current is less than the second preset current. The second preset current is the maximum current that the backlight driving circuit is allowed to provide to the backlight in a user-preset manner, which can protect the backlight from overcurrent damage.

[0118] In the above embodiments, such as Figure 1 , Figure 2 and Figure 3 As shown in the diagram, the arrows indicate the direction of current flow. Figure 2 In the process, the first common terminal inputs the LED+ signal to the connector 40 through a wire, and the fourth terminal of the driver chip 11 inputs the LED- signal to the connector 40 through another wire. Therefore, the connector 40 also needs to output the LED+ signal and the LED- signal to the flexible printed circuit board 50 through two wires. Finally, the flexible printed circuit board 50 provides the LED+ signal and the LED- signal to the backlight 60 through two wires, thereby realizing the driving of the backlight 60.

[0119] This application also provides a backlight module, including: a substrate, a flexible printed circuit board and a backlight lamp, and a backlight driving circuit as provided in the foregoing embodiments disposed on the substrate; the output terminal of the backlight driving circuit is electrically connected to the backlight lamp through a connector and the flexible printed circuit board.

[0120] This application also provides an LCD display screen, including: a liquid crystal panel, and the backlight module provided in the foregoing embodiments.

[0121] This application also provides an electronic device, including: the LCD display screen provided in the foregoing embodiments.

[0122] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A backlight driving circuit, wherein the backlight driving circuit is integrated on a substrate, characterized in that, The backlight driving circuit includes a driving chip, an overcurrent protection circuit, a boost regulator circuit, and a freewheeling diode. The first terminal of the overcurrent protection circuit is electrically connected to the output terminal of the power supply, and the second terminal of the overcurrent protection circuit is electrically connected to the first terminal of the boost regulator circuit; the power supply is used to output the first voltage. The second terminal of the boost regulator circuit is electrically connected to the first terminal of the driver chip. The third terminal of the boost regulator circuit is electrically connected to the second terminal of the driver chip and the first terminal of the freewheeling diode. The fourth terminal of the boost regulator circuit is electrically connected to the second terminal of the freewheeling diode. The connection point between the fourth terminal of the boost regulator circuit and the second terminal of the freewheeling diode is a first common terminal, which is electrically connected to the first terminal of the connector. The third terminal of the driver chip is electrically connected to the first terminal of the controller, and the fourth terminal of the driver chip is electrically connected to the second terminal of the connector. The third and fourth terminals of the connector are electrically connected to the backlight via a flexible printed circuit board. The boost regulator circuit is used to boost the first voltage and stably output the second voltage; the driver chip is used to receive the control signal output by the controller and provide a first current to the backlight according to the control signal and the second voltage; the overcurrent protection circuit is used to disconnect the power supply from the boost regulator circuit when the second current flowing through the overcurrent protection circuit is greater than a first preset current, wherein the first preset current is the current flowing through the overcurrent protection circuit when the backlight driver circuit is working normally.

2. The circuit according to claim 1, characterized in that, The overcurrent protection circuit includes a PTC thermistor; The first end of the PTC thermistor is electrically connected to the output end of the power supply, and the second end of the PTC thermistor is electrically connected to the first end of the boost regulator circuit.

3. The circuit according to claim 1, characterized in that, The overcurrent protection circuit includes a current-limiting load switch; The first terminal of the current-limiting load switch is electrically connected to the output terminal of the power supply, and the second terminal of the current-limiting load switch is electrically connected to the first terminal of the boost voltage regulator circuit.

4. The circuit according to claim 1, characterized in that, The boost regulator circuit includes a boost module, a first regulator module, and a second regulator module. The first terminal of the first voltage regulator module is electrically connected to the second terminal of the overcurrent protection circuit, and the second terminal of the first voltage regulator module is electrically connected to the ground terminal; the connection terminal between the first terminal of the first voltage regulator module and the second terminal of the overcurrent protection circuit is the second common terminal. The first terminal of the boost module is electrically connected to the second common terminal and the first terminal of the driver chip, respectively, and the second terminal of the boost module is electrically connected to the second terminal of the driver chip and the first terminal of the freewheeling diode, respectively. The first terminal of the second voltage regulator module is electrically connected to the second terminal of the freewheeling diode, and the second terminal of the second voltage regulator module is electrically connected to the ground terminal.

5. The circuit according to claim 4, characterized in that, The boost module includes a boost inductor; The first terminal of the boost inductor is electrically connected to the second common terminal and the first terminal of the driver chip, respectively, and the second terminal of the boost inductor is electrically connected to the second terminal of the driver chip and the first terminal of the freewheeling diode, respectively.

6. The circuit according to claim 4, characterized in that, The first voltage regulator module includes a first capacitor, a first terminal of which is electrically connected to the second terminal of the overcurrent protection circuit, and a second terminal of which is electrically connected to the ground terminal. The second voltage regulator module includes a second capacitor, the first end of which is electrically connected to the second end of the freewheeling diode, and the second end of which is electrically connected to the ground terminal.

7. The circuit according to claim 1, characterized in that, The backlight driving circuit also includes a current limiting circuit; The first terminal of the current limiting circuit is electrically connected to the fourth terminal of the driver chip, and the second terminal of the current limiting circuit is electrically connected to the ground terminal. The current limiting circuit is used to limit the first current so that the first current is less than the second preset current.

8. A backlight module, characterized in that, It includes a substrate, a flexible printed circuit board and a backlight, and a backlight driving circuit as described in any one of claims 1 to 7 disposed on the substrate; The output of the backlight driving circuit is electrically connected to the backlight lamp via a connector and the flexible printed circuit board.

9. An LCD display screen, characterized in that, It includes a liquid crystal panel and the backlight module as described in claim 8.

10. An electronic device, characterized in that, Including the LCD display screen as described in claim 9.

Images