Self-adaptive backlight driving and energy-saving circuit for vehicle-mounted display

Abstract

The invention discloses a self-adaptive backlight driving and energy-saving circuit for a vehicle-mounted display, and relates to the technical field of vehicle-mounted electronic equipment. The system comprises a power supply input module, an LED backlight module, an LED driving chip, a microcontroller unit, an environment sensing module and a system state sensing module, the power input module provides working voltage, the environment sensing module detects environment illumination intensity and outputs electric signals, the system state sensing module detects the running state of a vehicle-mounted system and outputs state signals, the microcontroller unit receives the signals and generates PWM dimming signals, and the LED driving chip controls current of the LED backlight module according to the signals so as to adjust brightness. According to the scheme, backlight brightness self-adaptive control is realized, the problems of high power consumption and non-intelligent adjustment of a traditional scheme are solved, and energy conservation and user experience are considered.

Description

An adaptive backlight driving and energy-saving circuit for automotive displays Technical Field

[0001] This invention relates to the field of automotive electronic equipment technology, and more specifically to an adaptive backlight driving and energy-saving circuit for automotive displays. Background Technology

[0002] With the increasing demands for automotive intelligence and human-machine interaction, the application scenarios for in-vehicle displays are becoming more and more widespread. Their backlight systems need to ensure visibility under different ambient lighting conditions. Traditional in-vehicle display backlight drive circuits mostly use fixed brightness output or manual adjustment, which cannot adaptively adjust according to ambient light intensity and the operating status of the in-vehicle system. In low ambient light, excessively high backlight brightness not only wastes energy but also causes glare, affecting user comfort; in high ambient light, a fixed low brightness results in blurry display content, impacting the user experience. Furthermore, traditional solutions do not consider the impact of system temperature and other operating conditions on the backlight; prolonged high brightness operation can easily lead to severe overheating of components, shortening the device's lifespan.

[0003] Based on the above problems, there is an urgent need for a backlight driving solution that can adaptively adjust based on the environment and system status, in order to solve the problems of high power consumption, unintelligent adjustment, and poor user experience of traditional solutions. Summary of the Invention

[0004] The purpose of this invention is to provide an adaptive backlight driving circuit for an in-vehicle display, comprising a power input module, an LED backlight module, an LED driver chip, and a microcontroller unit, and further comprising an environmental sensing module and a system status sensing module; the power input module outputs a working voltage to the LED driver chip and the microcontroller unit; the environmental sensing module detects the ambient light intensity around the display and outputs an electrical signal; the system status sensing module detects the operating status of the in-vehicle system and outputs a status signal; the microcontroller unit receives the electrical signal from the environmental sensing module and the status signal from the system status sensing module, generates a PWM dimming signal and sends it to the LED driver chip; the LED driver chip controls the current flowing through the LED backlight module according to the PWM dimming signal to achieve backlight brightness adjustment.

[0005] Preferably, the LED driver chip is model MPQ3364GR-AEC1-Z. This LED driver chip features constant current drive function and a PWM dimming interface. It has a DIM pin, which receives the PWM dimming signal sent by the microcontroller unit. The LED driver chip sets the constant current output current reference through the ISET resistor. The current calculation formula is as follows:

[0006] ;

[0007] Where R is the nominal resistance value of the ISET resistor, and R is taken as 10KΩ, corresponding to .

[0008] More preferably, the microcontroller unit is model S32K144. The microcontroller unit is equipped with GPIO pins and ADC input pins. The GPIO pins are connected to the DIM pins of the LED driver chip, and the ADC input pins are connected to the output of the environmental sensing module. The microcontroller unit is also connected to the IGN detection signal interface, the CAN bus transceiver, and the temperature sensor. The microcontroller unit stores a preset brightness curve, executes a backlight control algorithm to generate a PWM dimming signal, and is also connected to the HMI interface to receive brightness adjustment commands input from the HMI interface and store them as brightness reference values.

[0009] In a further preferred embodiment, the environmental sensing module includes an ambient light sensor, which detects the ambient light intensity in real time and converts the light intensity into an electrical signal corresponding to 0 lux to 100,000 lux. The electrical signal is transmitted to the ADC input pin of the microcontroller unit through the output terminal of the environmental sensing module, and the microcontroller unit obtains the specific value of the ambient light intensity through ADC sampling.

[0010] In a further preferred embodiment, the status signals of the system status sensing module include IGN signals, CAN bus communication status, display mode, and temperature data. The IGN signal corresponds to the on / off state of the vehicle ignition switch. The CAN bus communication status includes CAN bus activity status and brightness adjustment commands. The display modes are divided into Normal mode, WaitDisplay mode, and Sleep mode. The temperature data is collected by a temperature detection element mounted on the surface of the LED driver chip, and the temperature detection element outputs a temperature signal in the range of -40℃ to 125℃.

[0011] Further preferably, when the microcontroller unit generates the PWM dimming signal, it follows the following control logic: when the ambient light intensity is greater than 50,000 lux, the target brightness is 80% to 100% of the maximum brightness; when it is between 10,000 lux and 50,000 lux, the target brightness is 40% to 80% of the maximum brightness; when it is between 1,000 lux and 10,000 lux, the target brightness is 20% to 40% of the maximum brightness; when it is less than 1,000 lux, the target brightness is 5% to 20% of the maximum brightness; in Normal mode, the brightness is adjusted according to the above logic combined with the brightness reference value; in WaitDisplay mode, the target brightness is 5% to 10% of the maximum brightness or the TFT is turned off while the microcontroller unit remains awake; in Sleep mode, the backlight is turned off; when the temperature is greater than 85°C, the target brightness is 50% to 70% of the current brightness; the brightness reference value adjustment range is 5% to 100% of the maximum brightness; the CAN bus brightness adjustment command directly specifies the target brightness percentage.

[0012] Further preferably, the duty cycle of the PWM dimming signal is linearly correlated with the target brightness, the duty cycle adjustment range is 0% to 100%, the duty cycle accuracy is 0.1%, the microcontroller unit generates the PWM dimming signal through the internal timer module, the timer module counting frequency is 1MHz to 10MHz, the PWM dimming signal is transmitted to the DIM pin of the LED driver chip through the GPIO pin, the LED driver chip adjusts the conduction time of the internal switching transistor according to the duty cycle, and the average current flowing through the LED backlight module ranges from 6.225mA to 124.5mA.

[0013] More preferably, the power input module receives a +12V vehicle power supply. The boost output stage of the LED driver chip includes an inductor L3 and a Schottky diode D7. The inductor L3 has parameters of 10uH / 4.5A, and the Schottky diode D7 is model B360BQ-13-F. Decoupling filter capacitors C107, C109, C110, C111, C112, C113, and C114 are provided at the input and output terminals, where C109 is 10uF / 50V, C110 is 10uF / 50V, C111 is 12pF / 50V, and C112 is 10uF / 50V. C113 is 47uF / 50V, and C114 is 100uF / 50V; the OVP pin of the LED driver chip sets the overvoltage protection threshold through a voltage divider between resistors R174 and R177. The parameters of resistor R174 are 150KΩ / 1%, and the parameters of resistor R177 are 10KΩ / 1%, with an overvoltage protection threshold of 32V; the LCD signal lines are equipped with ESD protection components ESD7, ESD8, ESD9, ESD10, ESD11, and ESD12, all of which are model NC / DT1140-04LPQ-7 and packaged in DFN-10-2.5X1-0.5.

[0014] Further preferred, the operation flow of the microcontroller unit is as follows: First, initialization is performed, and a preset brightness curve is loaded; second, ambient light detection and system status detection are performed simultaneously, with ambient light detection only performed when configuring the ambient light sensor; third, the target brightness level is calculated by integrating the ambient light intensity signal, status signal, brightness reference value, and CAN bus brightness adjustment command; fourth, a PWM dimming signal with a corresponding duty cycle is generated; fifth, the LED backlight module current is adjusted through the LED driver chip; brightness control logic is executed throughout the process to maintain the backlight brightness in line with the current requirements.

[0015] In a further preferred embodiment, the brightness adjustment command of the HMI interface is transmitted to the microcontroller unit via wired communication. The microcontroller unit stores the brightness reference value in its internal flash memory, with storage addresses from 0x00080000 to 0x00080004. The brightness reference value is updated at a frequency not exceeding 1Hz. The brightness adjustment command received by the microcontroller unit via the CAN bus transceiver adopts the CAN2.0B protocol with a baud rate of 500Kbps.

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

[0017] The inventive aspect of this invention lies in the addition of an environmental sensing module and a system status sensing module. A microcontroller unit collaboratively processes these two types of signals to generate a PWM dimming signal, which, in conjunction with the LED driver chip, precisely controls the backlight current. This solution effectively solves the core problem of traditional backlight drivers' inability to adaptively adjust, achieving dynamic matching of backlight brightness with the environment and system status. This reduces unnecessary power consumption, avoids glare or insufficient visibility, and simultaneously reduces device heat generation, extending equipment lifespan. Attached Figure Description

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0019] Figure 1 is a block diagram of the adaptive backlight driving and energy-saving circuit connection for vehicle display of the present invention;

[0020] Figure 2 is a schematic diagram of the LED backlight driving circuit of the MPQ3364 chip of the present invention;

[0021] Figure 3 is a schematic diagram of the ESD electrostatic protection circuit for the LCD signal line of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The concepts involved in this application will first be described with reference to the accompanying drawings. It should be noted that the following descriptions of various concepts are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] Traditional technical solutions have the following technical problems: the backlight driver of the vehicle display relies on a fixed brightness or manual adjustment, and cannot dynamically adjust according to ambient light and system status, resulting in wasted power consumption and poor user experience.

[0025] Based on this, please refer to Figures 1-3. This embodiment provides an adaptive backlight driving circuit for an in-vehicle display, including a power input module, an LED backlight module, an LED driver chip, and a microcontroller unit. It also includes an environmental sensing module and a system status sensing module. The power input module outputs a working voltage to the LED driver chip and the microcontroller unit. The environmental sensing module detects the ambient light intensity around the display and outputs an electrical signal. The system status sensing module detects the operating status of the in-vehicle system and outputs a status signal. The microcontroller unit receives the electrical signal from the environmental sensing module and the status signal from the system status sensing module, generates a PWM dimming signal, and sends it to the LED driver chip. The LED driver chip controls the current flowing through the LED backlight module according to the PWM dimming signal to achieve backlight brightness adjustment.

[0026] This technical solution constructs a complete adaptive backlight driving closed-loop system, with each module working together to achieve end-to-end control from perception to execution. The power input module, as the core of energy supply, specifically receives and regulates the standard vehicle power supply, outputting a stable voltage that meets the operating requirements of each device. This provides the necessary power for the LED driver chip and a stable operating voltage for the microcontroller unit, ensuring the core control unit is unaffected by power supply fluctuations. The environmental perception module incorporates a dedicated ambient light detection element, capable of capturing subtle changes in ambient light intensity in real time. It converts physical light signals into analog electrical signals recognizable by the microcontroller unit. This conversion process features high linearity and fast response, accurately reflecting differences in lighting conditions under different scenarios. The system status perception module comprehensively monitors key operating parameters of the vehicle system, including ignition switch on / off status, CAN bus communication status, device operating modes, and core component temperatures. All status information is converted into standardized signal outputs, providing system-level decision-making basis for brightness adjustment. As the control core of the entire system, the microcontroller unit simultaneously receives the illumination signals from the environmental sensing module and the status signals from the system status sensing module via a dedicated interface. The built-in backlight control algorithm performs real-time analysis and fusion calculations on these two types of signals, determines the target brightness suitable for the current scene based on preset logic, and then generates a PWM dimming signal with a corresponding duty cycle through an internal timer module. This signal is directly transmitted to the LED driver chip via a dedicated pin. After receiving the PWM dimming signal, the LED driver chip precisely adjusts the current flowing through the LED backlight module through its internal constant current control circuit. The current change is linearly related to the PWM duty cycle, thereby achieving smooth adjustment of the backlight brightness and forming a complete collaborative workflow of "environmental and status sensing - signal processing - dimming signal generation - brightness execution".

[0027] The technical effects achieved by the above embodiments include: realizing dynamic adaptation of backlight brightness, balancing visibility and energy saving requirements, improving user comfort, and reducing system heat generation.

[0028] Traditional technical solutions have the following technical problems: LED driver chips lack clear constant current reference settings and precise dimming interface designs, resulting in insufficient backlight current control accuracy.

[0029] Based on this, the LED driver chip model is MPQ3364GR-AEC1-Z. This LED driver chip features constant current drive function and a PWM dimming interface. It has a DIM pin, which receives the PWM dimming signal sent by the microcontroller unit. The LED driver chip sets the constant current output current reference through the ISET resistor. The current calculation formula is as follows: Where R is the nominal resistance value of the ISET resistor, and R is 10KΩ, corresponding to .

[0030] This technical solution clearly defines the specific model selection of the LED driver chip, the core interface configuration, and the constant current reference setting method, ensuring the accuracy and stability of backlight current control. The selected MPQ3364GR-AEC1-Z chip is a high-efficiency boost LED driver specifically designed for automotive backlight driving. Its built-in constant current drive circuit effectively suppresses current fluctuations, ensuring stable brightness of the LED backlight module. The chip's DIM pin is a dedicated PWM dimming interface, featuring high input impedance and low signal loss. It directly connects to the GPIO pins of the microcontroller unit, ensuring distortion-free transmission of the PWM dimming signal and providing a hardware foundation for precise dimming. The constant current output current reference is precisely set through an external ISET resistor, and the core calculation formula... It is derived based on the internal circuit design principles of the chip, and the dimension of R in the formula is kiloohms. The dimension of is milliampere, and the two are inversely proportional. By selecting an ISET resistor with a nominal resistance of 10KΩ and substituting it into the formula, we can calculate... This current value has been optimized to meet the rated operating requirements of automotive LED backlight modules, while also balancing brightness performance and energy consumption control. The chip internally monitors the current flowing through the LED backlight module in real time through a feedback adjustment mechanism, and adjusts it against the set value. The values ​​are compared and corrected to ensure that the deviation between the actual working current and the set value is controlled within a very small range, thus achieving a constant current drive effect.

[0031] The technical effects achieved by the above embodiments include: realizing precise and stable control of LED backlight current, ensuring the linearity of brightness adjustment, and improving the reliability and consistency of backlight driving.

[0032] Traditional technical solutions have the following technical problems: the microcontroller unit lacks targeted pin configuration and functional design, and cannot efficiently receive multi-source signals and generate accurate dimming signals.

[0033] Based on this, the microcontroller unit is model S32K144. The microcontroller unit is equipped with GPIO pins and ADC input pins. The GPIO pins are connected to the DIM pins of the LED driver chip, and the ADC input pins are connected to the output of the environmental sensing module. The microcontroller unit is also connected to the IGN detection signal interface, the CAN bus transceiver, and the temperature sensor. The microcontroller unit stores a preset brightness curve, executes the backlight control algorithm to generate a PWM dimming signal, and is also connected to the HMI interface to receive brightness adjustment commands input from the HMI interface and store them as brightness reference values.

[0034] This technical solution comprehensively optimizes the hardware configuration and software functions of the microcontroller unit, ensuring efficient processing of multi-source signals and precise generation of control signals. The selected S32K144 microcontroller unit possesses the high reliability and powerful computing capabilities required for automotive applications. Its GPIO pins are specifically configured to output PWM dimming signals. This pin supports high-speed signal output and can generate PWM waveforms with stable frequency and precise duty cycles, directly interfacing with the DIM pins of the LED driver chip to reduce interference and delay in the signal transmission path. The ADC input pin has a sampling accuracy of 12 bits or more and is specifically used to receive analog electrical signals output from the environmental sensing module. The internal analog-to-digital converter converts the analog signals into digital signals, featuring high sampling rate and low quantization error, accurately reproducing ambient light intensity information. The microcontroller unit connects to the IGN detection signal interface via a dedicated communication interface to acquire the on / off status of the vehicle's ignition switch in real time, providing the basic trigger signal for turning the backlight system on and off. It connects to the vehicle's CAN network via a CAN bus transceiver, receiving brightness adjustment commands from the network and providing feedback on the backlight system's operating status. A temperature sensor interface collects real-time temperature data from core components, providing data support for thermal management strategies. The microcontroller unit internally stores a preset brightness curve, optimized based on extensive vehicle scenario test data, covering reference brightness values ​​under different lighting and system conditions, providing a reference for initial dimming. The built-in backlight control algorithm has multi-source data fusion processing capabilities, performing comprehensive calculations on ambient light data, system status data, and user-manually set values ​​to dynamically adjust the duty cycle of the PWM dimming signal. Simultaneously, the microcontroller unit establishes communication with the HMI interface via a dedicated interface, receiving brightness adjustment commands input by the user in real time and storing the corresponding brightness value as a brightness reference value. Subsequent dimming is based on this reference value for dynamic adjustment, enabling flexible switching between automatic adjustment and manual intervention.

[0035] The technical effects achieved by the above embodiments include: realizing efficient integration and processing of multi-source signals, ensuring the accuracy of dimming signal generation, and supporting seamless switching between automatic and manual adjustment modes.

[0036] Traditional technical solutions have the following technical problems: the lack of quantitative standards and reliable signal transmission paths for ambient light detection leads to inaccurate ambient brightness data.

[0037] Based on this, the environmental sensing module includes an ambient light sensor, which detects the ambient light intensity in real time and converts the light intensity into an electrical signal corresponding to 0 lux to 100,000 lux. The electrical signal is transmitted to the ADC input pin of the microcontroller unit through the output terminal of the environmental sensing module. The microcontroller unit obtains the specific value of the ambient light intensity through ADC sampling.

[0038] This technical solution establishes a standardized ambient light detection and signal transmission mechanism to ensure the accuracy and reliability of ambient light data. The ambient light sensor built into the environmental perception module employs a high-sensitivity photoelectric conversion element, possessing a wide-range detection capability, covering a light range from 0 lux to 100,000 lux. This range fully encompasses all possible lighting conditions in vehicle scenarios, from low-light environments at night and inside tunnels to strong daylight and midday sun, ensuring accurate detection in various scenarios. When the sensor is working, it converts light signals of different intensities into corresponding analog electrical signals. The conversion process follows a strict linear relationship; the light intensity is directly proportional to the electrical signal amplitude, with no nonlinear distortion, accurately reflecting the actual changes in light intensity. The output of the environmental perception module uses a shielded transmission line, directly connecting to the ADC input pin of the microcontroller unit. The short transmission path and absence of additional intermediate conversion stages effectively reduce the impact of electromagnetic interference on the signal, ensuring complete electrical signal transmission. The microcontroller unit initiates the ADC sampling function to digitize the received analog electrical signal. The sampling frequency is set according to actual needs to ensure that the dynamic changes in light intensity can be captured. The sampled digital signal is processed by an internal filtering algorithm to remove outliers caused by accidental interference, and finally obtains a specific value that can accurately represent the current ambient light intensity, providing accurate data support for the microcontroller unit's dimming decision.

[0039] The technical effects achieved by the above embodiments include: realizing accurate quantitative detection and reliable transmission of ambient light intensity, providing an accurate environmental data basis for adaptive dimming.

[0040] Traditional technical solutions have the following technical problems: the system status detection dimensions are incomplete, and there is a lack of comprehensive collection of key operating parameters, which affects the adaptability of brightness adjustment.

[0041] Based on this, the status signals of the system status sensing module include IGN signal, CAN bus communication status, display mode and temperature data. The IGN signal corresponds to the on / off state of the car ignition switch. The CAN bus communication status includes CAN bus activity status and brightness adjustment command. The display modes are divided into Normal mode, WaitDisplay mode and Sleep mode. The temperature data is collected by a temperature detection element installed on the surface of the LED driver chip. The temperature detection element outputs a temperature signal in the range of -40℃ to 125℃.

[0042] This technical solution constructs a multi-dimensional, comprehensive system status detection system, providing a complete and accurate decision-making basis for brightness adjustment. The IGN signal directly reflects the on / off state of the vehicle's ignition switch. When the ignition switch is on, the IGN signal triggers the system to start the backlight drive; when the ignition switch is off, the IGN signal triggers the system to enter a low-power or sleep state, providing basic control signals for the start and stop of the backlight system. CAN bus communication status detection includes two core aspects: first, monitoring the activity status of the CAN bus to determine whether the vehicle network is communicating normally, ensuring the effective transmission of brightness adjustment commands; second, receiving brightness adjustment commands sent by other vehicle units in the CAN bus to achieve unified brightness control at the vehicle level. Display mode detection clearly distinguishes three core working modes: Normal mode corresponds to the normal display state during normal vehicle operation, WaitDisplay mode corresponds to the vehicle's standby state but needs to display necessary information, and Sleep mode corresponds to the sleep state when the vehicle is parked for a long time. Different modes correspond to different brightness requirements, providing a mode basis for differentiated dimming strategies. Temperature data detection is achieved through a temperature sensing element specifically mounted on the surface of the LED driver chip. This element is tightly attached to the chip surface, enabling rapid response to changes in chip temperature. The detection range covers the extreme automotive ambient temperature range of -40℃ to 125℃. The acquired temperature signal directly reflects the actual operating temperature of the LED driver chip, preventing performance degradation or damage caused by chip overheating and providing accurate data support for brightness adjustment related to thermal management. All status signals are output in a standardized format, ensuring efficient parsing and processing by the microcontroller unit.

[0043] The technical effects achieved by the above embodiments include: comprehensively capturing key system operation parameters, providing multi-dimensional decision-making basis for brightness adjustment, and ensuring that the adjustment strategy is accurately adapted to the actual scenario.

[0044] Traditional technical solutions have the following technical problems: the microcontroller unit lacks clear brightness adjustment logic, resulting in a lack of unified standards for determining the target brightness.

[0045] Based on this, when the microcontroller unit generates a PWM dimming signal, it follows the following control logic: when the ambient light intensity is greater than 50,000 lux, the target brightness is 80% to 100% of the maximum brightness; when it is between 10,000 lux and 50,000 lux, the target brightness is 40% to 80% of the maximum brightness; when it is between 1,000 lux and 10,000 lux, the target brightness is 20% to 40% of the maximum brightness; when it is less than 1,000 lux, the target brightness is 5% to 20% of the maximum brightness; in Normal mode, the brightness is adjusted according to the above logic combined with the brightness reference value; in WaitDisplay mode, the target brightness is 5% to 10% of the maximum brightness or the TFT is turned off while the microcontroller unit remains awake; in Sleep mode, the backlight is turned off; when the temperature is greater than 85℃, the target brightness is 50% to 70% of the current brightness; the brightness reference value adjustment range is 5% to 100% of the maximum brightness; the CAN bus brightness adjustment command directly specifies the target brightness percentage.

[0046] This technical solution establishes a standardized brightness adjustment logic that adapts to multiple scenarios and coordinates multiple factors, ensuring the scientific validity and consistency of target brightness determination. Based on ambient light intensity as the core adjustment criterion, four distinct light intensity ranges are defined, each corresponding to a fixed brightness range. This division is optimized based on actual lighting test data from in-vehicle scenarios, ensuring optimal visibility of the display under different lighting conditions. High brightness is provided in strong light environments to ensure clear display, while brightness is reduced in low light environments to avoid glare. Differentiated adjustment strategies are developed for three operating modes: in Normal mode, light intensity is the core factor, while user-defined brightness benchmarks are incorporated for dynamic adjustment, balancing environmental adaptability and personalized needs; in WaitDisplay mode, low brightness design or shutdown of the display panel while keeping the control unit awake is employed, minimizing power consumption while ensuring necessary information display; in Sleep mode, the backlight is completely shut off for ultimate energy saving. A temperature protection adjustment mechanism is introduced: when the temperature exceeds 85℃, the current brightness is automatically reduced to a set ratio, reducing power consumption and device heat generation, preventing damage to core components due to high temperatures, and ensuring long-term stable system operation. It supports two manual intervention methods. The brightness reference value set by the user through the HMI interface covers the full brightness range from 5% to 100%, which can meet the visual preferences of different users. The brightness adjustment command transmitted by the CAN bus can directly specify the target brightness percentage, realize unified control at the vehicle system level, and the adjustment logic sorts according to priority when multiple factors are superimposed, ensuring that the decision is orderly and reasonable.

[0047] The technical effects achieved by the above embodiments include: establishing a clear and unified brightness adjustment standard, achieving accurate adaptation to multiple scenarios, and balancing visibility, energy efficiency and device safety.

[0048] Traditional technical solutions have the following technical problems: the generation and transmission of PWM dimming signals lack clear parameter settings, resulting in insufficient brightness adjustment accuracy and response speed.

[0049] Based on this, the duty cycle of the PWM dimming signal corresponds linearly to the target brightness, with a duty cycle adjustment range of 0% to 100% and a duty cycle accuracy of 0.1%. The microcontroller unit generates the PWM dimming signal through an internal timer module with a counting frequency of 1MHz to 10MHz. The PWM dimming signal is transmitted to the DIM pin of the LED driver chip through the GPIO pin. The LED driver chip adjusts the conduction time of the internal switching transistor according to the duty cycle. The average current flowing through the LED backlight module ranges from 6.225mA to 124.5mA.

[0050] This technical solution establishes clear parameter standards for the generation, transmission, and execution of PWM dimming signals, ensuring high precision and rapid response in brightness adjustment. The duty cycle of the PWM dimming signal establishes a strict linear correspondence with the target brightness. The full range of duty cycle adjustment from 0% to 100% covers the complete range of backlight changes from off to maximum brightness. A 0.1% duty cycle accuracy ensures fine-grained brightness adjustment, enabling smooth brightness changes that are imperceptible to the naked eye, avoiding visual discomfort caused by sudden brightness fluctuations. The microcontroller unit generates the PWM dimming signal through an internal high-performance timer module. The timer module's counting frequency can be set within the range of 1MHz to 10MHz according to actual needs. High-frequency counting ensures the frequency stability of the PWM signal, avoiding brightness flicker caused by frequency fluctuations. The generated PWM dimming signal is directly transmitted to the DIM pin of the LED driver chip through the GPIO pin of the microcontroller unit. The transmission path has no intermediate buffering, and signal delay is controlled to an extremely low level, ensuring rapid response in brightness adjustment and meeting the real-time dimming requirements in dynamic scenarios. After receiving the PWM dimming signal, the LED driver chip precisely adjusts the conduction time of the internal switching transistor according to the signal duty cycle. The larger the duty cycle, the longer the conduction time of the switching transistor, and the larger the average current flowing through the LED backlight module. Conversely, the smaller the current, the smaller the average current. The adjustment range of the average current is 6.225mA to 124.5mA. This range matches the rated operating current of the LED backlight module, ensuring maximum brightness requirements while avoiding brightness instability caused by insufficient current, thus achieving linear and precise brightness adjustment.

[0051] The technical effects achieved by the above embodiments include: improving PWM dimming accuracy and response speed, realizing delicate and smooth adjustment of backlight brightness, and optimizing the visual experience.

[0052] Traditional technical solutions have the following technical problems: the power supply circuit, protection circuit and ESD protection design are not perfect, resulting in insufficient system stability and reliability.

[0053] Based on this, the power input module receives a +12V vehicle power supply. The boost output stage of the LED driver chip includes an inductor L3 and a Schottky diode D7. The inductor L3 has parameters of 10uH / 4.5A, and the Schottky diode D7 is model B360BQ-13-F. Decoupling filter capacitors C107, C109, C110, C111, C112, C113, and C114 are provided at the input and output terminals. Among them, C109 is 10uF / 50V, C110 is 10uF / 50V, C111 is 12pF / 50V, C112 is 10uF / 50V, and C114 is 10uF / 50V. 113 is 47uF / 50V, and C114 is 100uF / 50V; the OVP pin of the LED driver chip sets the overvoltage protection threshold through a voltage divider between resistors R174 and R177. The parameters of resistor R174 are 150KΩ / 1%, and the parameters of resistor R177 are 10KΩ / 1%, with an overvoltage protection threshold of 32V; the LCD signal lines are equipped with ESD protection components ESD7, ESD8, ESD9, ESD10, ESD11, and ESD12, all of which are model NC / DT1140-04LPQ-7 and packaged in DFN-10-2.5X1-0.5.

[0054] This technical solution optimizes circuit design from multiple aspects, including power supply, filtering and noise reduction, overvoltage protection, and electrostatic discharge protection, comprehensively improving system stability and reliability. The power input module is specifically adapted to the automotive +12V standard power supply, compatible with the voltage fluctuation range of automotive power supplies, providing a stable input for subsequent circuits. The boost output stage of the LED driver chip uses a combination of high-performance inductor L3 and Schottky diode D7. Inductor L3 has an inductance of 10uH and a rated current of 4.5A, featuring low loss and high saturation current characteristics, enabling efficient voltage boost conversion. Schottky diode D7, model B360BQ-13-F, features low forward voltage drop and fast switching speed, effectively reducing energy loss during the boost process and ensuring sufficient driving voltage for the LED backlight module. The input and output terminals are equipped with a combination of decoupling filter capacitors of various specifications. C109, C110, and C112 are all 10uF / 50V, mainly used to filter out low-frequency power supply noise; C111 is 12pF / 50V, specifically for suppressing high-frequency interference; C113 is 47uF / 50V and C114 is 100uF / 50V, used to stabilize the output voltage. All capacitors work together to ensure the purity of the power supply signal and prevent noise from affecting the driver circuit. The OVP pin of the LED driver chip forms a voltage divider circuit with resistors R174 and R177. The nominal resistance of resistor R174 is 150KΩ with an accuracy of 1%, and the nominal resistance of resistor R177 is 10KΩ with an accuracy of 1%. Through precise voltage division, the overvoltage protection threshold is set to 32V. When the output voltage exceeds this threshold, the chip automatically activates the protection mechanism to prevent damage to the LED backlight module and driver chip due to overvoltage. The LCD signal lines are equipped with dedicated ESD protection components. All protection components are model NC / DT1140-04LPQ-7, packaged in DFN-10-2.5X1-0.5, and feature low clamping voltage and high anti-static capability. They can effectively absorb electrostatic pulses and protect the LCD signal lines and core components from electrostatic interference damage.

[0055] The technical effects achieved by the above embodiments include: improving the stability and anti-interference capability of the circuit system, effectively protecting core components, and extending the service life of the system.

[0056] Traditional technical solutions have the following technical problems: the operation process of the microcontroller unit is not clear, resulting in insufficient logical coherence and real-time performance of brightness adjustment.

[0057] Based on this, the operation flow of the microcontroller unit is as follows: First, initialization is performed, and a preset brightness curve is loaded; second, ambient light detection and system status detection are performed simultaneously, with ambient light detection only performed when configuring the ambient light sensor; third, the target brightness level is calculated by integrating the ambient light intensity signal, status signal, brightness reference value, and CAN bus brightness adjustment command; fourth, a PWM dimming signal with a corresponding duty cycle is generated; fifth, the LED backlight module current is adjusted through the LED driver chip; brightness control logic is executed throughout the process to maintain the backlight brightness in line with the current requirements.

[0058] This technical solution establishes standardized and streamlined microcontroller unit operation steps to ensure the logical consistency and real-time performance of brightness adjustment. The first initialization step is automatically executed after system power-on. The microcontroller unit initializes and configures its peripherals, LED driver chip, and related interfaces, while simultaneously loading a preset brightness curve. This curve provides a reference for the initial brightness, ensuring the system quickly enters a stable operating state after startup and avoiding abnormal initial brightness. The second step initiates a parallel detection mechanism, simultaneously executing ambient light detection and system status detection. These two detection operations are performed concurrently without any order, significantly improving data acquisition efficiency. The ambient light detection function is flexibly enabled based on system configuration, executing only when an ambient light sensor is present, avoiding invalid calculations in the absence of a sensor and saving system resources. The third step is a data fusion and computation phase. The microcontroller unit combines the collected ambient light intensity signal and system status signal with the stored brightness reference value and received CAN bus brightness adjustment commands. Through a built-in backlight control algorithm, it performs multi-dimensional comprehensive calculations. The algorithm assigns weights to various data types according to preset priorities, accurately calculating the optimal target brightness level for the current scene, ensuring the scientific and rational nature of the decision. In the fourth step, the PWM dimming signal generation stage, the microcontroller unit generates a PWM signal with a corresponding duty cycle based on the calculated target brightness level through its internal timer module. The duty cycle is strictly matched with the target brightness, and the signal generation response time is short to ensure real-time performance. In the fifth step, the adjustment stage, the PWM dimming signal is transmitted to the LED driver chip. The driver chip responds quickly and adjusts the current flowing through the LED backlight module to achieve precise brightness switching. Throughout the entire operation, the microcontroller unit adheres to the brightness control logic, continuously monitoring changes in various input signals. If any signal fluctuation occurs, it immediately re-executes subsequent steps to ensure that the backlight brightness always matches the current requirement.

[0059] The technical effects achieved by the above embodiments include: standardizing the operation process of the microcontroller unit, improving the real-time performance and consistency of brightness adjustment, and ensuring reasonable and efficient adjustment decisions.

[0060] Traditional technical solutions have the following technical problems: the transmission and storage of HMI interface commands lack clear specifications, and the CAN bus command reception protocol is unclear, which affects the reliability of manual adjustment.

[0061] Based on this, the brightness adjustment command of the HMI interface is transmitted to the microcontroller unit via wired communication. The microcontroller unit stores the brightness reference value in the internal flash memory, with storage addresses from 0x00080000 to 0x00080004. The brightness reference value is updated at a frequency of no more than 1Hz. The brightness adjustment command received by the microcontroller unit through the CAN bus transceiver adopts the CAN2.0B protocol with a baud rate of 500Kbps.

[0062] This technical solution clarifies the transmission and storage standards for manual adjustment commands and the CAN bus communication protocol, ensuring the reliability and compatibility of manual adjustments. The brightness adjustment commands from the HMI interface are transmitted via wired communication, using a transmission line with strong anti-interference capabilities to effectively resist electromagnetic interference in the vehicle environment. This ensures the command signal is transmitted to the microcontroller unit intact and without distortion, preventing command failure or erroneous execution due to signal interference. Upon receiving the command, the microcontroller unit stores the corresponding brightness reference value in its internal dedicated flash memory area. The storage address is fixed between 0x00080000 and 0x00080004. This address range is a stable storage area for the microcontroller unit, ensuring high data reliability and minimizing data loss. The brightness reference value update frequency is strictly controlled within 1Hz to avoid frequent write operations that could damage the flash memory, while ensuring that the user-adjusted brightness value takes effect promptly. When the microcontroller unit receives the brightness adjustment command from the vehicle system via the CAN bus transceiver, it adopts the industry-standard CAN2.0B protocol. This protocol features high transmission rate, strong anti-interference capability, and good compatibility, making it suitable for multi-node communication scenarios in vehicles. The communication baud rate is set to 500Kbps, which balances transmission efficiency and stability, enabling fast transmission of brightness adjustment commands while avoiding transmission errors caused by excessively high rates. This ensures that the microcontroller unit can accurately receive and execute the brightness adjustment commands at the vehicle level.

[0063] The technical effects achieved by the above embodiments include: improving the reliability of manual adjustment command transmission and storage, ensuring CAN bus communication compatibility and efficiency, and optimizing the manual adjustment experience.

[0064] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any way. Any person skilled in the art can make some modifications or alterations to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as the technology or embodiments that are substantially the same as the present invention.

[0065] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. An adaptive backlight driving circuit for an automotive display, comprising a power input module, an LED backlight module, an LED driver chip, and a microcontroller unit, characterized in that, It also includes an environmental sensing module and a system status sensing module; the power input module outputs operating voltage to the LED driver chip and the microcontroller unit; the environmental sensing module detects the ambient light intensity around the display and outputs an electrical signal; the system status sensing module detects the operating status of the vehicle system and outputs a status signal; the microcontroller unit receives the electrical signal from the environmental sensing module and the status signal from the system status sensing module, generates a PWM dimming signal and sends it to the LED driver chip; the LED driver chip controls the current flowing through the LED backlight module according to the PWM dimming signal to achieve backlight brightness adjustment.

2. The adaptive backlight driving circuit for an in-vehicle display according to claim 1, characterized in that, The LED driver chip model is MPQ3364GR-AEC1-Z. This LED driver chip features constant current drive function and a PWM dimming interface. It has a DIM pin, which receives the PWM dimming signal from the microcontroller unit. The LED driver chip sets the constant current output current reference through the ISET resistor. The current calculation formula is as follows: Where R is the nominal resistance value of the ISET resistor, and R is taken as 10KΩ, corresponding to... 。 3. The adaptive backlight driving circuit for an in-vehicle display according to claim 1, characterized in that, The microcontroller unit is model S32K144. The microcontroller unit is equipped with GPIO pins and ADC input pins. The GPIO pins are connected to the DIM pins of the LED driver chip, and the ADC input pins are connected to the output of the environmental sensing module. The microcontroller unit is also connected to the IGN detection signal interface, the CAN bus transceiver, and the temperature sensor. The microcontroller unit stores the preset brightness curve, executes the backlight control algorithm to generate the PWM dimming signal, and is also connected to the HMI interface to receive the brightness adjustment commands input from the HMI interface and store them as the brightness reference value.

4. The adaptive backlight driving circuit for an in-vehicle display according to claim 1, characterized in that, The environmental sensing module includes an ambient light sensor, which detects the ambient light intensity in real time and converts the intensity into an electrical signal corresponding to 0 lux to 100,000 lux. The electrical signal is transmitted to the ADC input pin of the microcontroller unit through the output of the environmental sensing module. The microcontroller unit obtains the specific value of the ambient light intensity through ADC sampling.

5. The adaptive backlight driving circuit for an automotive display according to claim 1, characterized in that, The status signals of the system status sensing module include IGN signal, CAN bus communication status, display mode and temperature data. The IGN signal corresponds to the on / off status of the car ignition switch. The CAN bus communication status includes CAN bus activity status and brightness adjustment command. The display modes are divided into Normal mode, WaitDisplay mode and Sleep mode. The temperature data is collected by a temperature detection element installed on the surface of the LED driver chip. The temperature detection element outputs a temperature signal in the range of -40℃ to 125℃.

6. The adaptive backlight driving circuit for an automotive display according to claim 1, characterized in that, When the microcontroller unit generates a PWM dimming signal, it follows the control logic as follows: When the ambient light intensity is greater than 50,000 lux, the target brightness is 80% to 100% of the maximum brightness; when it is between 10,000 lux and 50,000 lux, the target brightness is 40% to 80% of the maximum brightness; when it is between 1,000 lux and 10,000 lux, the target brightness is 20% to 40% of the maximum brightness; when it is less than 1,000 lux, the target brightness is 5% to 20% of the maximum brightness; in Normal mode, the brightness is adjusted according to the above logic combined with the brightness reference value; in WaitDisplay mode, the target brightness is 5% to 10% of the maximum brightness or the TFT is turned off while the microcontroller unit remains awake; in Sleep mode, the backlight is turned off; when the temperature is greater than 85℃, the target brightness is 50% to 70% of the current brightness; the brightness reference value adjustment range is 5% to 100% of the maximum brightness; the CAN bus brightness adjustment command directly specifies the target brightness percentage.

7. The adaptive backlight driving circuit for an automotive display according to claim 1, characterized in that, The duty cycle of the PWM dimming signal is linearly related to the target brightness. The duty cycle adjustment range is 0% to 100%, and the duty cycle accuracy is 0.1%. The microcontroller unit generates the PWM dimming signal through the internal timer module. The timer module counts from 1MHz to 10MHz. The PWM dimming signal is transmitted to the DIM pin of the LED driver chip through the GPIO pin. The LED driver chip adjusts the conduction time of the internal switching transistor according to the duty cycle. The average current flowing through the LED backlight module ranges from 6.225mA to 124.5mA.

8. The adaptive backlight driving circuit for an automotive display according to claim 1, characterized in that, The power input module receives a +12V vehicle power supply. The boost output stage of the LED driver chip includes inductor L3 and Schottky diode D7. Inductor L3 has parameters of 10uH / 4.5A, and Schottky diode D7 is model B360BQ-13-F. Decoupling filter capacitors C107, C109, C110, C111, C112, C113, and C114 are provided at the input and output terminals. Among them, C109 is 10uF / 50V, C110 is 10uF / 50V, C111 is 12pF / 50V, C112 is 10uF / 50V, and C114 is 12pF / 50V. 3 is 47uF / 50V, C114 is 100uF / 50V; the OVP pin of the LED driver chip sets the overvoltage protection threshold through a voltage divider between resistors R174 and R177. The parameters of resistor R174 are 150KΩ / 1%, and the parameters of resistor R177 are 10KΩ / 1%, with an overvoltage protection threshold of 32V; the LCD signal lines are equipped with ESD protection components ESD7, ESD8, ESD9, ESD10, ESD11, and ESD12, all of which are model NC / DT1140-04LPQ-7 and packaged in DFN-10-2.5X1-0.

5.

9. The adaptive backlight driving circuit for an automotive display according to claim 1, characterized in that, The operation flow of the microcontroller unit is as follows: First, initialization is performed, and a preset brightness curve is loaded; second, ambient light detection and system status detection are performed simultaneously, with ambient light detection only performed when configuring the ambient light sensor; third, the target brightness level is calculated by integrating the ambient light intensity signal, status signal, brightness reference value, and CAN bus brightness adjustment command; fourth, a PWM dimming signal with a corresponding duty cycle is generated; fifth, the LED backlight module current is adjusted through the LED driver chip; brightness control logic is executed throughout the process to maintain the backlight brightness in line with the current requirements.

10. The adaptive backlight driving circuit for an automotive display according to claim 3, characterized in that, The brightness adjustment command from the HMI interface is transmitted to the microcontroller unit via wired communication. The microcontroller unit stores the brightness reference value in its internal flash memory, with storage addresses from 0x00080000 to 0x00080004. The brightness reference value is updated at a frequency not exceeding 1Hz. The brightness adjustment command received by the microcontroller unit via the CAN bus transceiver adopts the CAN2.0B protocol with a baud rate of 500Kbps.

Images