15. Backlight control circuit for 6-inch notebook display

Abstract

This application relates to a backlight control circuit for a 15.6-inch laptop display. The backlight control circuit includes a power module, a main control module, and a load module. The main control module includes resistors R3 and R4, a chip U2, and a capacitor C5. The first terminal of resistor R3 is electrically connected to the power module, and the second terminal of resistor R3 is electrically connected to chip U2. The first terminal of resistor R4 is also electrically connected to the power module, and the second terminal of resistor R4 is electrically connected to chip U2. The first terminal of capacitor C5 is electrically connected to chip U2, and the second terminal of capacitor C5 is grounded. The load module is electrically connected to chip U2. The solution provided in this application enhances the anti-interference capability of the backlight control circuit, improves EMI noise reduction, and maintains the normal operation of the backlight LED assembly.

Description

Technical Field

[0001] This utility model relates to the field of display technology, and in particular to a backlight control circuit for a 15.6-inch laptop display. Background Technology

[0002] The backlight control circuit of a laptop display converts the voltage input from a storage battery or adapter to provide the necessary stable operating voltage to the backlight LED assembly.

[0003] In related technologies, the current backlight control circuits have reduced anti-interference capabilities and poor EMI noise reduction effects, resulting in potential flickering issues in the backlight LED light groups. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a backlight control circuit for a 15.6-inch laptop display, which can enhance the anti-interference capability of the backlight control circuit, improve the EMI noise reduction effect, and maintain the normal operation of the backlight LED light group.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] The first aspect of this application provides a backlight control circuit for a 15.6-inch laptop display, comprising: a power module; a main control module, including resistors R3 and R4, a chip U2, and a capacitor C5, wherein the first end of resistor R3 is electrically connected to the power module, the second end of resistor R3 is electrically connected to the chip U2, the first end of resistor R4 is electrically connected to the power module, the second end of resistor R4 is electrically connected to the chip U2, the first end of capacitor C5 is electrically connected to the chip U2, and the second end of capacitor C5 is grounded; and a load module electrically connected to the chip U2.

[0007] The main control module also includes a communication signal input terminal, which is electrically connected to the chip U2. The second end of the resistor R3 is electrically connected to the communication signal input terminal, and the second end of the resistor R4 is electrically connected to the communication signal input terminal.

[0008] The power module includes capacitor C1, capacitor C2, resistor R25 and chip U1. The first end of capacitor C1 is electrically connected to the first end of capacitor C2. The second end of capacitor C1 is grounded. The second end of capacitor C2 is grounded. The first end of resistor R25 is electrically connected to the first end of capacitor C2. The second end of resistor R25 is electrically connected to chip U1.

[0009] The power module also includes an inductor L1, the first end of which is electrically connected to the chip U1.

[0010] The power module also includes resistors R1 and R2. The first end of resistor R1 is electrically connected to the first end of inductor L1, the second end of resistor R1 is electrically connected to the first end of resistor R2, and the second end of resistor R2 is grounded.

[0011] The power module also includes capacitor C3 and capacitor C4. The first end of capacitor C3 is electrically connected to the second end of inductor L1, and the second end of capacitor C3 is grounded. The first end of capacitor C4 is electrically connected to the first end of capacitor C3, and the second end of capacitor C4 is grounded.

[0012] The load module includes an inductor L2, and the first end of the inductor L2 is electrically connected to the second end of the inductor L1.

[0013] The load module also includes a diode D1, the first end of which is electrically connected to the second end of the inductor L2.

[0014] The load module also includes capacitors C6, C7 and C8. The second terminal of diode D1 is electrically connected to the first terminal of capacitor C6, the first terminal of capacitor C7 and the first terminal of capacitor C8, respectively. The second terminals of capacitors C6, C7 and C8 are all grounded.

[0015] The load module also includes an LED light group, the first end of which is electrically connected to the second end of the diode D1, and the second end of which is electrically connected to the chip U2.

[0016] Compared with the prior art, the present invention has at least the following advantages:

[0017] Resistors R3 and R4 are pull-up resistors, providing a stable high-level state for communication signal transmission and preventing noise interference caused by the signal lines being in a floating state. The inclusion of capacitor C5 enhances the overall EMI noise reduction effect of the circuit and strengthens the anti-interference capability of the backlight control circuit. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below.

[0019] Figure 1 This is a functional block diagram of the backlight control circuit of a 15.6-inch laptop display in one embodiment of the present invention.

[0020] Figure 2 This is a circuit diagram of the main control module in one embodiment of the present invention;

[0021] Figure 3This is a circuit diagram of the power supply module in one embodiment of the present invention;

[0022] Figure 4 This is a circuit diagram of the load module in one embodiment of the present invention. Detailed Implementation

[0023] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0024] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0025] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] The backlight control circuit of a laptop display converts the voltage input from a storage battery or adapter to provide the necessary stable operating voltage to the backlight LED assembly. Current backlight control circuits have reduced interference immunity and poor EMI noise reduction, leading to a potential flickering issue with the backlight LED assembly.

[0027] To address the aforementioned issues, this application provides a backlight control circuit for a 15.6-inch laptop display, which enhances the anti-interference capability of the backlight control circuit, improves EMI noise reduction, and maintains the normal operation of the backlight LED assembly.

[0028] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings.

[0029] See Figure 1 and Figure 2 A backlight control circuit for a 15.6-inch laptop display includes: a power module 100, a main control module 200, and a load module 300; the main control module 200 includes resistors R3 and R4, a chip U2, and a capacitor C5; the first end of resistor R3 is electrically connected to the power module 100, and the second end of resistor R3 is electrically connected to the chip U2; the first end of resistor R4 is electrically connected to the power module 100, and the second end of resistor R4 is electrically connected to the chip U2; the first end of capacitor C5 is electrically connected to the chip U2, and the second end of capacitor C5 is grounded; the load module 300 is electrically connected to the chip U2.

[0030] It should be noted that the power supply module 100 provides drive voltage to the main control module 200 and the load module 300, while the main control module 200 controls the constant current and constant voltage output of the load module 300. Furthermore, chip U2 can be an NT50590, and resistors R3 and R4 are pull-up resistors to provide a stable high-level state for communication signal transmission, preventing noise interference caused by floating signal lines. The inclusion of capacitor C5 enhances the overall EMI noise reduction effect of the circuit and strengthens the anti-interference capability of the backlight control circuit.

[0031] See Figure 2 In one embodiment, the main control module 200 further includes a communication signal input terminal, which is electrically connected to the chip U2. The second end of the resistor R3 is electrically connected to the communication signal input terminal, and the second end of the resistor R4 is electrically connected to the communication signal input terminal.

[0032] It should be noted that the communication signal input terminal is an I2C communication signal.

[0033] See Figure 3 In one embodiment, the power module 100 includes capacitor C1, capacitor C2, resistor R25 and chip U1. The first end of capacitor C1 is electrically connected to the first end of capacitor C2, the second end of capacitor C1 is grounded, the second end of capacitor C2 is grounded, the first end of resistor R25 is electrically connected to the first end of capacitor C2, and the second end of resistor R25 is electrically connected to chip U1.

[0034] It should be noted that capacitors C1 and C2 are filter capacitors, resistor R25 is a current-limiting resistor, and chip U1 is a step-down chip. The model of chip U1 can be FP6381AS5CTR.

[0035] See Figure 3 In one embodiment, the power module 100 further includes an inductor L1, the first end of which is electrically connected to the chip U1.

[0036] It should be noted that inductor L1 is used to suppress sudden current changes, reduce the current surge when the built-in MOSFET of chip U1 switches, and reduce the stress impact of the output on subsequent circuit components.

[0037] See Figure 3 In one embodiment, the power module 100 further includes resistors R1 and R2. The first end of resistor R1 is electrically connected to the first end of inductor L1, the second end of resistor R1 is electrically connected to the first end of resistor R2, and the second end of resistor R2 is grounded.

[0038] It should be noted that resistors R1 and R2 are voltage divider resistors.

[0039] See Figure 3 In one embodiment, the power module 100 further includes capacitor C3 and capacitor C4. The first end of capacitor C3 is electrically connected to the second end of inductor L1, and the second end of capacitor C3 is grounded. The first end of capacitor C4 is electrically connected to the first end of capacitor C3, and the second end of capacitor C4 is grounded.

[0040] It should be noted that capacitors C3 and C4 are used to suppress the ripple of the output voltage. They smooth the current fluctuations through the charging and discharging process, preventing large fluctuations in the load voltage. They work in conjunction with inductor L1 to output a stable VIN voltage.

[0041] See Figure 4 In one embodiment, the load module 300 includes an inductor L2, the first end of which is electrically connected to the second end of an inductor L1.

[0042] It should be noted that inductor L2 is used to suppress sudden current changes. When the input current changes abruptly, inductor L2 generates a self-induced electromotive force that opposes the current change, thus providing a constant current for the subsequent load circuit.

[0043] See Figure 4 In one embodiment, the load module 300 further includes a diode D1, the first end of which is electrically connected to the second end of the inductor L2.

[0044] It should be noted that diode D1 serves to prevent reverse current flow.

[0045] See Figure 4 In one embodiment, the load module 300 further includes capacitors C6, C7 and C8. The second terminal of diode D1 is electrically connected to the first terminal of capacitor C6, the first terminal of capacitor C7 and the first terminal of capacitor C8, respectively. The second terminals of capacitors C6, C7 and C8 are all grounded.

[0046] It should be noted that capacitors C6, C7, and C8 serve a decoupling function.

[0047] See Figure 4 In one embodiment, the load module 300 further includes an LED lamp group, the first end of which is electrically connected to the second end of the diode D1, and the second end of which is electrically connected to the chip U2.

[0048] It should be noted that the LED light group includes, but is not limited to, 6 groups of light strips. Specifically, D2 to D7 form one group, D8 to D13 form one group, D14 to D19 form one group, D20 to D25 form one group, D26 to D31 form one group, and D32 to D37 form one group.

[0049] The circuit principle of this application is explained below:

[0050] First, the VCC voltage passes through capacitors C1 and C2 to ground to filter out noise signals. Then, the startup voltage is input to pin 1 of chip U1, which is connected to the input terminal of the built-in power regulator. At the same time, the VCC voltage is connected to the current-limiting resistor R25 and input to the enable terminal pin 2, which plays a role in delaying the voltage phase transmission. This ensures that the enable terminal of chip U1 is in a low-level state when it is powered on, preventing the built-in circuit of chip U1 from starting up erroneously. The buck module will only start the built-in circuit to drive the operation after the input voltage of pin 1 stabilizes. Chip U1 outputs voltage via a 3-pin switch after passing through its internal DC-DC buck logic drive circuit. The output voltage is connected to one end of inductor L1 to suppress current surges, mitigating the current surge during switching of the built-in MOSFET and reducing stress on subsequent circuit components. The other end of inductor L1 is connected to resistors R1 and R2 in series for voltage division. This voltage is fed back to pin 4 of chip U1, which is connected to the inverting input of the built-in voltage comparator. The voltage is compared with the reference voltage VREF, and the output signal controls the DC-DC buck logic drive circuit, thus limiting the output fluctuation range. Inductor L1 is also connected to capacitors C3 and C4 to suppress output voltage ripple. The charging and discharging process smooths current fluctuations, preventing large voltage fluctuations at the load end. This coordinated operation with inductor L1 ensures a stable VIN voltage output.

[0051] Power module 100 transmits VIN voltage to pin 22 of chip U2, providing a startup voltage for the built-in LED driver and putting chip U2 into a ready-to-work state. Pin 23, the enable pin, connects to external control signals. When the backlight control circuit is activated, the laptop's central control motherboard sends a high-level signal to pin 23 of chip U2, activating the internal logic circuitry. Furthermore, pins 2 and 3 of chip U2 connect to external I2C communication signals, linking to the serial port protocol of the central control motherboard. External pull-up resistors R3 and R4 provide a stable high-level state for communication signal transmission, preventing noise interference caused by floating signal lines. An external capacitor C5 on pin 4 of chip U2 filters the signal to ground, eliminating output noise interference from the built-in linear regulator, enhancing the overall EMI noise reduction effect, and strengthening the anti-interference capability of the backlight control circuit. The 24-pin connector of chip U2 connects to the PWM dimming control signal transmitted from the central control motherboard. By adjusting the duty cycle of the pulse signal, the average output voltage or current is changed, thereby achieving precise control of analog quantities such as brightness and speed.

[0052] Furthermore, the VIN voltage is connected to inductor L2 to suppress sudden current changes. When the input current changes abruptly, inductor L2 generates a self-induced electromotive force that impedes the current change, thus providing constant current for the subsequent load circuit. The other end of inductor L2 is connected to pins 19 and 20 of chip U2, providing voltage control to the drain of the built-in MOSFET to change the logic drive of the main control module. Simultaneously, it monitors the current of the LED group, providing overcurrent protection to prevent overload and damage to the LED backlight. Inductor L2 is also connected to the positive terminal of diode D1, preventing reverse current flow to the power input terminal based on the diode's unidirectional conductivity. Then, the VIN voltage, output from the negative terminal of diode D1, is connected to capacitors C6, C7, and C8 for decoupling, providing a more stable power supply to the LED group. This also reduces noise coupled from components to the power supply terminal and minimizes the indirect noise from other components. The 15-pin connector of chip U2 is connected to the VIN voltage after decoupling from capacitors C6, C7, and C8. This voltage is fed back to the internal components of chip U2 to monitor the actual voltage of the LED group, providing overvoltage protection, resolving the potential issues of constant voltage drive in the control module, and maintaining balanced voltage and overcurrent distribution among the multiple channels of the backlight LEDs.

[0053] The VIN voltage, after passing through the decoupling capacitor, is connected to the common anode of the LED group. The negative terminal is connected to pins 7, 8, 9, 11, 13, and 14 of chip U2. The constant current absorption method is used to control the negative terminal of the LED group, which solves the voltage difference between the LED groups and maintains the balanced voltage division of the backlight multi-channel. Combined with the built-in loop voltage compensation of chip U2 and the duty cycle voltage of the PWM dimming control signal, the voltage or current of the LED group is changed, thereby achieving the operational stability of the drive circuit and forming a closed loop.

[0054] The solution of this application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have different focuses; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. Those skilled in the art should also understand that the actions and modules involved in the specification are not necessarily essential to this application. Furthermore, it is understood that the steps in the method of this application embodiment can be adjusted, combined, and deleted according to actual needs, and the modules in the device of this application embodiment can be combined, divided, and deleted according to actual needs.

[0055] 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 control circuit for a 15.6-inch laptop display, characterized in that, include: Power module; The main control module includes resistor R3, resistor R4, chip U2, and capacitor C5. The first end of resistor R3 is electrically connected to the power module, and the second end of resistor R3 is electrically connected to chip U2. The first end of resistor R4 is electrically connected to the power module, and the second end of resistor R4 is electrically connected to chip U2. The first end of capacitor C5 is electrically connected to chip U2, and the second end of capacitor C5 is grounded. The load module is electrically connected to the chip U2.

2. The backlight control circuit for a 15.6-inch laptop display according to claim 1, characterized in that, The main control module also includes a communication signal input terminal, which is electrically connected to the chip U2. The second end of the resistor R3 is electrically connected to the communication signal input terminal, and the second end of the resistor R4 is electrically connected to the communication signal input terminal.

3. The backlight control circuit for a 15.6-inch laptop display according to claim 2, characterized in that, The power module includes capacitor C1, capacitor C2, resistor R25 and chip U1. The first end of capacitor C1 is electrically connected to the first end of capacitor C2. The second end of capacitor C1 is grounded. The second end of capacitor C2 is grounded. The first end of resistor R25 is electrically connected to the first end of capacitor C2. The second end of resistor R25 is electrically connected to chip U1.

4. The backlight control circuit for a 15.6-inch laptop display according to claim 3, characterized in that, The power module also includes an inductor L1, the first end of which is electrically connected to the chip U1.

5. The backlight control circuit for a 15.6-inch laptop display according to claim 4, characterized in that, The power module also includes resistors R1 and R2. The first end of resistor R1 is electrically connected to the first end of inductor L1, the second end of resistor R1 is electrically connected to the first end of resistor R2, and the second end of resistor R2 is grounded.

6. The backlight control circuit for a 15.6-inch laptop display according to claim 4, characterized in that, The power module also includes capacitor C3 and capacitor C4. The first end of capacitor C3 is electrically connected to the second end of inductor L1, and the second end of capacitor C3 is grounded. The first end of capacitor C4 is electrically connected to the first end of capacitor C3, and the second end of capacitor C4 is grounded.

7. The backlight control circuit for a 15.6-inch laptop display according to claim 4, characterized in that, The load module includes an inductor L2, and the first end of the inductor L2 is electrically connected to the second end of the inductor L1.

8. The backlight control circuit for a 15.6-inch laptop display according to claim 7, characterized in that, The load module also includes a diode D1, the first end of which is electrically connected to the second end of the inductor L2.

9. The backlight control circuit for a 15.6-inch laptop display according to claim 8, characterized in that, The load module also includes capacitors C6, C7 and C8. The second terminal of diode D1 is electrically connected to the first terminal of capacitor C6, the first terminal of capacitor C7 and the first terminal of capacitor C8, respectively. The second terminals of capacitors C6, C7 and C8 are all grounded.

10. The backlight control circuit for a 15.6-inch laptop display according to claim 9, characterized in that, The load module also includes an LED light group, the first end of which is electrically connected to the second end of the diode D1, and the second end of which is electrically connected to the chip U2.

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