A topological notebook backlight module circuit structure
Patent Information
- Application Number
- CN202522142587.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-10
- Publication Date
- 2026-10-09
- Estimated Expiration
- 2035-10-10
AI Technical Summary
[0006]本申请目的在于克服现有笔记本电脑背光模组电路中，传统限流电阻+PWM调光方案功耗高、效率低、亮度一致性差的缺陷，相比现有技术提供一种拓扑式笔记本背光模组线路结构，包括多颗以菊花链拓扑方式连接的恒流驱动芯片，每颗所述恒流驱动芯片均由单点归零码控制，并具有电源引脚、地引脚、输入引脚、输出引脚和N个恒流输出引脚（N≥2）；
本申请通过多颗以菊花链拓扑方式连接的恒流驱动芯片设计，消除限流电阻损耗，5V供电下能量利用率达90.6%（保守值），较传统方案节能约36%，适配笔记本续航需求，恒流源电路抵消LED正向压降差异，各通道亮度偏差＜2%，且支持独立调光与低功耗模式下的灵活关断，在保证亮度与一致性的同时显著提高了能量利用率，适合于笔记本电脑背光等对功耗敏感的场合。
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Figure CN224841230U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of notebook backlighting, and in particular to a topological notebook backlight module circuit structure. Background Technology
[0002] The backlight module is a crucial component of a laptop's display system, and its performance directly impacts display quality and device battery life. Please refer to... Figure 1 Existing laptop backlight module circuits typically employ a simple constant voltage drive scheme, using PWM (pulse width modulation) signals to control the on / off state of MOSFET transistors to dim the series LED array. Each LED is connected in series with a current-limiting resistor, and the entire LED array is powered by a 5V constant power supply.
[0003] When the PWM signal is high, the MOSFET is turned on, and each LED branch illuminates; when the PWM signal is low, the MOSFET is turned off, and each LED is off. The backlight brightness is adjusted by regulating the duty cycle of the PWM signal. Although this scheme has a simple circuit structure and low cost, its power consumption distribution and efficiency characteristics are far from ideal.
[0004] In the aforementioned traditional backlight driving circuit, the total power consumption consists of two parts: LED light emission consumption and current-limiting resistor loss. Taking a 5V constant power supply, a white LED forward voltage drop of 2.9V, and an operating current of 12mA as an example: LED power consumption P_LED = V_F × I = 2.9V × 0.012A = 0.0348W; resistor voltage V_R = V_SUPPLY V_F=5.0V 2.9V = 2.1V; Resistor power consumption P_R = V_R × I = 2.1V × 0.012A = 0.0252W; Total power consumption P_TOTAL_TRAD = P_LED + P_R = 60.0mW; Energy efficiency (luminous emission / total power consumption) η_TRAD ≈ 58%.
[0005] It is evident that only about 60% of the power in each LED branch is used for LED illumination, while approximately 40% of the energy is wasted in the current-limiting resistor. If the backlight array contains multiple parallel LED branches, the total power loss of the current-limiting resistor will accumulate linearly with the number of LEDs. For example, when a backlight module with 10 LEDs is operating at full brightness, the current-limiting resistor consumes approximately 0.4W of power, while the LEDs themselves consume approximately 0.6W. This loss not only reduces the power utilization efficiency of the backlight driver circuit (typically only 50%–60% overall efficiency), which is detrimental to energy consumption control in battery-powered devices such as laptops, but also causes the current-limiting resistor to heat up, increasing the circuit's heat dissipation burden and affecting the backlight module's operational stability and component lifespan. Therefore, a technical solution that can improve backlight driving efficiency and reliability is urgently needed. Utility Model Content
[0006] The purpose of this application is to overcome the shortcomings of the traditional current-limiting resistor + PWM dimming scheme in existing laptop backlight module circuits, which has high power consumption, low efficiency and poor brightness consistency. Compared with the prior art, it provides a topology-based laptop backlight module circuit structure, which includes multiple constant current driving chips connected in a daisy-chain topology. Each of the constant current driving chips is controlled by a single-point return-to-zero code and has a power supply pin, a ground pin, an input pin, an output pin and N constant current output pins (N≥2). Each constant current output pin is connected to the cathode of the corresponding LED, and the anode of the LED is connected to a 5V DC power supply; the constant current driver chip does not integrate a boost function; the circuit does not contain a current-limiting resistor; each constant current output channel supports independent control of its current magnitude to achieve LED brightness adjustment.
[0007] Furthermore, the single-point return-to-zero code control adopts a single-line digital control method, and this single-line digital control method supports serial data transmission, which can realize efficient data interaction between the main controller and multiple constant current drive chips.
[0008] Furthermore, the constant current driver chip supports cascading output. Multiple constant current driver chips are connected in sequence through input pins and output pins to form a daisy chain connection structure. The main controller only needs to use a small number of control signal lines to control all constant current driver chips.
[0009] Furthermore, the current value of each constant current output channel can be set by programming or adjusted by quantization to meet the precise control requirements of LED brightness in different scenarios.
[0010] Furthermore, the main controller sends control data containing the brightness values of each LED channel to the first constant current driver chip in the daisy-chain topology via a serial interface. After processing the data, the first constant current driver chip transmits the data to the next constant current driver chip through its output pin, and so on to the last constant current driver chip. The last constant current driver chip then sends the data back to the main controller, forming a communication chain that is connected end to end.
[0011] Furthermore, all constant current driver chips use a unified clock signal for data shifting and refresh control to ensure that the brightness updates of all LED channels are synchronized, avoiding brightness differences or delays.
[0012] Furthermore, the constant current driver chip is provided with a feedback terminal, which is used to monitor the voltage on each constant current output channel, so that the output voltage of the 5V DC power supply is just higher than the voltage threshold required by the LED, and the voltage drop inside the constant current driver chip is kept at a low level to reduce power loss.
[0013] Compared to existing technologies, the advantages of this application are: This application utilizes a design of multiple constant current driver chips connected in a daisy-chain topology to eliminate current-limiting resistor losses. Under 5V power supply, the energy utilization rate reaches 90.6% (conservative value), saving approximately 36% energy compared to traditional solutions. It is suitable for the battery life requirements of laptops. The constant current source circuit compensates for the difference in LED forward voltage drop, with brightness deviation of each channel <2%. It also supports independent dimming and flexible shutdown in low-power mode. While ensuring brightness and consistency, it significantly improves energy utilization, making it suitable for power-sensitive applications such as laptop backlights. Attached Figure Description
[0014] Figure 1 Circuit diagram of an existing resistor-limited current-limiting laptop backlight solution; Figure 2 This is the circuit diagram for this application. Detailed Implementation
[0015] The embodiments will be described clearly and completely with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.
[0016] Example: This utility model provides a topological circuit structure for a notebook backlight module. Please refer to [link / reference]. Figure 2 It includes multiple constant current drive chips, a main controller, and multiple LEDs connected in a daisy-chain topology.
[0017] Each constant current driver chip is controlled by a single-point return-to-zero code and has a power supply pin, a ground pin, an input pin, an output pin, and N constant current output pins (N≥2). The chip does not integrate a boost function, and the entire circuit does not contain a current-limiting resistor.
[0018] Each constant current output pin is connected to the cathode of the corresponding LED, and the anode of the LED is connected to a 5V DC power supply. The constant current source circuit inside the constant current driver chip can ensure that no matter how the forward voltage of the LED changes, each constant current output channel outputs a constant set current, ensuring consistent LED brightness.
[0019] The single-point return-to-zero code control adopts a single-wire digital control method and supports serial data transmission. The main controller sends control data containing the brightness values of each LED channel to the first constant current driver chip in the daisy-chain topology through a serial interface. After processing the data, the first constant current driver chip transmits the data to the next constant current driver chip through its output pin, and so on to the last constant current driver chip. The last constant current driver chip sends the data back to the main controller, forming a communication chain that connects the beginning and the end, realizing efficient data interaction between the main controller and all constant current driver chips.
[0020] Because the constant current driver chip supports cascading output, multiple chips can form a daisy chain structure by connecting the input pins and output pins in sequence. The main controller only needs a few control signal lines to control a large number of constant current driver chips. When it is necessary to add or reduce the backlight area, the number of constant current driver chips can be increased or decreased accordingly, which has strong scalability.
[0021] The current value of each constant current output channel can be set via programming or adjusted via quantization. The control data sent by the main controller includes the required brightness level for each LED channel. After receiving the data, the constant current driver chip adjusts the current magnitude or duty cycle of the corresponding channel through internal counting or modulation circuits to achieve PWM dimming or analog current dimming, precisely controlling the brightness of each LED area. Simultaneously, when some backlight areas do not need to be fully illuminated, the current of the corresponding channel can be reduced or even completely turned off, reducing unnecessary energy consumption.
[0022] In addition, the constant current driver chip is equipped with a feedback terminal, which monitors the voltage on each constant current output channel to ensure that the output voltage of the 5V DC power supply is just higher than the voltage threshold required by the LED. This keeps the voltage drop inside the constant current driver chip at a low level, preventing excess voltage from being dissipated as heat on the chip and maximizing driving efficiency.
[0023] Under the conditions of 5V power supply, 2.9V forward voltage drop of white LED, and 12mA operating current, even considering the conservative voltage drop of 0.3V inside the constant current driver chip, the total power consumption of a single LED branch is about 38.4mW, with an energy utilization rate of about 90.6%, which is about 36% more energy-efficient than the traditional solution and an efficiency improvement of about 32.6 percentage points. If we take the ideal upper limit (the voltage drop inside the chip can be ignored), the total power consumption of a single LED branch is about 34.8mW, with an efficiency close to 100%, which significantly improves the energy utilization rate of the backlight module.
[0024] Please refer to the following for details. Figure 2 In this embodiment, the topology notebook computer backlight module circuit includes a main controller (such as the main controller driver of the LCD panel or an independent MCU), two constant current driver chips (U1, U2, each chip has four constant current output pins, i.e., N=4) and eight LEDs (LED1-LED8).
[0025] The power supply pins of constant current drive chips U1 and U2 are both connected to a 5V DC power supply, and their ground pins are both grounded. The input pin of U1 is connected to the serial interface output of the main controller, the output pin of U1 is connected to the input pin of U2, and the output pin of U2 is connected to the serial interface input of the main controller, forming a daisy-chain communication chain. The four constant current output pins of U1 are connected to the cathodes of LED1-LED4, and the four constant current output pins of U2 are connected to the cathodes of LED5-LED8. The anodes of LED1-LED8 are all connected to a 5V DC power supply.
[0026] In this embodiment, the single-point zero-code control adopts a single-wire digital control method. The main controller sends control data to U1 at a preset frequency (e.g., 100kHz). The control data includes the brightness levels (e.g., 0-255) of LEDs 1-8. After receiving the control data, U1 first parses the brightness levels of LEDs 1-4 and adjusts the current of each channel to a value matching the brightness level (e.g., 12mA current corresponding to brightness level 255) through its internal constant current source circuit. Subsequently, U1 transmits the brightness level data of LEDs 5-8 to the input pin of U2 through its output pin. After receiving the data, U2 parses the brightness levels of LEDs 5-8 and adjusts the current of the corresponding channels. Finally, U2 sends a data reception confirmation signal back to the main controller. This data is transmitted in series until the last chip sends the data back to the main controller, forming a communication chain with the beginning and end connected. In this daisy-chain connection method, the system only needs a small number of control signal lines to control a large number of constant current drive chips sequentially. When increasing or decreasing the backlight area, only the number of chips needs to be increased or decreased accordingly, which has high scalability.
[0027] All constant current drive chips use a unified clock signal (provided by the main controller, with the frequency consistent with the data transmission frequency) for data shifting and refresh control. After receiving the data, the chip adjusts the current magnitude or duty cycle of the corresponding channel through internal counting or modulation circuits to achieve PWM dimming or analog current dimming, thereby precisely controlling the brightness of each lamp area and ensuring that the brightness updates of LED1-LED8 are synchronized, avoiding brightness delays or differences.
[0028] Furthermore, to optimize power consumption, the constant current driver chip in this embodiment monitors the voltage on each channel via feedback, ensuring that the supply voltage is just above the voltage threshold required by the LED string. This automatic voltage adjustment keeps the voltage drop of the constant current output tube at a low level, thus preventing excess voltage from being dissipated as heat on the chip and maximizing driving efficiency. In summary, through the daisy-chain solution of the constant current driver chip in this invention, the backlight system achieves independent dimming in multiple areas while reducing power consumption, significantly improving the energy utilization and image quality of the display device.
[0029] When the laptop is in low-power mode (such as when the battery level is below 20%), the main controller can send control data to reduce the current of LEDs in non-core display areas (such as LED4 and LED5 in the edge area of the screen) to 5mA, keep the current of LEDs in core display areas (such as LED2, LED3, LED6, and LED7 in the center area of the screen) at 8mA, and turn off the current of LED1 and LED8 to reduce unnecessary energy consumption.
[0030] The feedback terminal of the constant current driver chip monitors the voltage of each constant current output channel in real time. When the LED forward voltage increases by 0.2V due to temperature changes, the feedback terminal transmits the voltage change signal to the internal control circuit of the chip. The control circuit fine-tunes the internal voltage drop of the chip so that the 5V DC power supply output voltage can still meet the LED's operating requirements, while avoiding excess voltage dissipation as heat. Actual testing shows that, under the conditions of 5V power supply, a white LED forward voltage drop of 2.9V, and an operating current of 12mA, the total power consumption of a single LED branch is 38.2mW, with an energy utilization rate of 90.8%. Compared to the traditional solution, this represents a 36.3% energy saving and a 32.8 percentage point efficiency improvement. Furthermore, the brightness deviation of LEDs 1-8 is less than 2%, significantly better than the traditional solution.
[0031] If we take the ideal upper limit (the gap between the heads can be ignored), the total power consumption of a single branch is about 34.8mW, and the efficiency is close to 100%. Therefore, in application scenarios that do not integrate boost converters and are mainly powered by 5V DC, this utility model significantly improves energy utilization while ensuring brightness and consistency by eliminating the structural losses of the current limiting resistor, making it suitable for power-sensitive applications such as laptop backlights.
[0032] The above description is merely the best implementation method adopted in light of current practical needs, but the scope of protection of this application is not limited thereto.
Claims
1. A topological notebook backlight module circuit structure, comprising multiple constant current driver chips, a main controller, and multiple LEDs connected in a daisy-chain topology, characterized in that: Each of the constant current driver chips is controlled by a single-point return-to-zero code and has a power supply pin, a ground pin, an input pin, an output pin, and N constant current output pins (N≥2). Each constant current output pin is connected to the cathode of the corresponding LED, and the anode of the LED is connected to a 5V DC power supply; the constant current driver chip does not integrate a boost function; the circuit does not contain a current-limiting resistor; each constant current output channel supports independent control of its current magnitude to achieve LED brightness adjustment.
2. The circuit structure of a topological notebook backlight module according to claim 1, characterized in that, The single-point zero-code control adopts a single-line digital control method, which supports serial data transmission and enables efficient data interaction between the main controller and multiple constant current drive chips.
3. The circuit structure of a topological notebook backlight module according to claim 1, characterized in that, The constant current driver chip supports cascading output. Multiple constant current driver chips are connected in a daisy chain structure by sequentially connecting their input pins and output pins. The main controller only needs to use a small number of control signal lines to control all constant current driver chips.
4. The circuit structure of a topological notebook backlight module according to claim 1, characterized in that, The current value of each constant current output channel can be set by programming or adjusted by quantization to meet the precise control requirements of LED brightness in different scenarios.
5. The circuit structure of a topological notebook backlight module according to claim 1, characterized in that, The main controller sends control data containing the brightness values of each LED channel to the first constant current driver chip in the daisy-chain topology via a serial interface. After processing the data, the first constant current driver chip transmits the data to the next constant current driver chip through its output pin, and so on to the last constant current driver chip. The last constant current driver chip then sends the data back to the main controller, forming a communication chain that is connected end to end.
6. The circuit structure of a topological notebook backlight module according to claim 1, characterized in that, All constant current driver chips use a unified clock signal for data shifting and refresh control, ensuring that the brightness updates of all LED channels are synchronized, avoiding brightness differences or delays.
7. The circuit structure of a topological notebook backlight module according to claim 1, characterized in that, The constant current driver chip is equipped with a feedback terminal, which is used to monitor the voltage on each constant current output channel, so that the output voltage of the 5V DC power supply is just higher than the voltage threshold required by the LED, and the voltage drop inside the constant current driver chip is kept at a low level to reduce power loss.