Brightness control method and system for vehicle-mounted head-up display and display

Abstract

The invention relates to a brightness control method and system for a vehicle-mounted head-up display and the display. A dynamic adaptation model based on ambient light intensity is constructed by combining human eye visual adaptation characteristics and HUD field angle characteristics, visual adaptation behaviors of human eyes under different illumination conditions can be simulated, and the brightness of the HUD is automatically adjusted according to different light intensity changes, so that information display better conforms to the visual comfort of the human eyes. According to the invention, the maximum HUD display brightness acceptable by human eyes under different illumination conditions can be calculated, the brightness adjustment values under different illumination conditions are dynamically calculated by using the De Boer coefficient, and the brightness of the HUD display is adjusted in real time according to the external light environment, so that the brightness adaptive dynamic closed-loop adjustment is realized, the HUD is effectively prevented from being too bright under low ambient light, and the HUD display quality is improved. The visual blinding phenomenon caused by instantaneous strong light reflection or bright element emerging in a dark scene is avoided, the function safety level of the vehicle-mounted HUD system is remarkably improved, and the ISO 26262ASIL-B level safety requirement is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of in-vehicle head-up displays, and particularly relates to a brightness control method, system, and display for an in-vehicle head-up display. Background Art

[0002] With the development of the automotive industry, in-vehicle head-up displays (HUDs) have become important devices for enhancing driving safety and convenience. The HUD system projects key information (such as vehicle speed, navigation instructions, warning messages, etc.) onto the driver's forward field of view, allowing the driver to obtain immediate driving information without having to look down at the dashboard, thereby reducing the driver's line-of-sight deviation and lowering the risk of traffic accidents caused by distracted driving.

[0003] However, existing in-vehicle HUD systems still face many technical challenges in actual use, especially in terms of brightness and color control in complex lighting environments. Specifically, during vehicle operation, the intensity of external light changes significantly, such as strong sunlight during the day, low-light environments at dusk, and dim lighting in tunnels. These changes have a significant impact on the display effect of the HUD system. If the brightness adjustment range of the HUD is insufficient or unable to adapt to ambient light changes in real time, the following problems may occur:

[0004] When the vehicle is in a strong light environment (such as direct sunlight during the day), the HUD display may appear too dim for the driver to clearly see the information; while in a dim environment (such as at night or in a tunnel), the display may be too bright, and the glaring light source may cause visual discomfort to the driver and even lead to temporary blindness.

[0005] In addition, if the display color of the HUD system is not reasonably designed, it may lead to difficulties in reading information. Especially in different ambient lights, insufficient color contrast will affect the driver's immediate recognition of information, further increasing the driving risk. The brightness and color adjustment of existing HUD systems mostly rely on manual adjustment or preset modes, lacking sufficient intelligent adaptive functions and unable to dynamically adjust display parameters according to actual lighting conditions. Especially when the ambient light changes rapidly (such as when entering or exiting a tunnel), the brightness and display effect of the HUD may not respond in time, thus affecting the driver's judgment and reaction time. Summary of the Invention

[0006] In view of the deficiencies of the above-mentioned existing technologies, the present application provides a brightness control method, system and display for an in-vehicle head-up display. By combining the human eye visual adaptation characteristics with the HUD field of view characteristics, a dynamic adaptation model based on ambient light intensity is constructed, which can simulate the visual adaptation behavior of the human eye under different lighting conditions, and automatically adjust the brightness of the HUD according to different light intensity changes, making the information display more in line with the visual comfort of the human eye.

[0007] In a first aspect, a brightness control method for an in-vehicle head-up display, the method comprising:

[0008] S1: Collect environmental parameters;

[0009] S2: Perform filtering and fusion processing on the environmental parameters to generate a global ambient light intensity parameter;

[0010] S3: Calculate the effective field of view within the driver's eye box according to the design parameters of the HUD optical system;

[0011] S4: Calculate the HUD display brightness corresponding to different De Boer coefficients under the current ambient light intensity according to the global ambient light intensity parameter and the effective field of view, wherein the HUD display brightness is the maximum HUD brightness acceptable to the human eye under the current external ambient light;

[0012] S5: Perform brightness control on the in-vehicle head-up display according to the HUD display brightness.

[0013] The method proposed in the present application obtains the current ambient light intensity and adjusts the HUD display brightness according to this light intensity, so as to maintain the best display effect under various lighting conditions. Especially in strong light or low light environments, it can effectively avoid visual discomfort and information loss caused by over-bright or over-dark displays. This method can calculate the maximum HUD display brightness acceptable to the human eye under different lighting conditions. This brightness control method not only considers the influence of external lighting, but also combines the design parameters of the vehicle system, dynamically calculates the best display brightness by reverse deduction, and dynamically calculates the brightness adjustment value under different lighting conditions using the De Boer coefficient, and can adjust the brightness of the HUD display in real time according to the external light environment.

[0014] Preferably, the environmental parameters include the vehicle front ambient light intensity information from the front windshield sensor and the vehicle upper ambient light intensity information from the cockpit top sensor.

[0015] Preferably, step S2 is specifically: perform low-pass filtering processing on the environmental parameters, and use a weighted average algorithm to fuse the vehicle front ambient light intensity information and the vehicle upper ambient light intensity information to generate a global ambient light intensity parameter;

[0016] Among them, according to the spatial relationship between the installation positions of the sensors and the driver's line of sight, a weight coefficient of 0.6 to 0.8 is assigned to the front windshield sensor, and a weight coefficient of 0.2 to 0.4 is assigned to the sensor on the top of the cockpit.

[0017] Preferably, step S3 is specifically as follows: Based on the De Boer formula for the sensitivity of the human eye to glare, different DeBoer coefficients are selected for dynamic inversion to obtain the effective field of view angle.

[0018] Preferably, step S4 is specifically as follows: According to the ambient light brightness of the environment where the driver is located, how many degrees below the forward field of view the light source is, and the maximum brightness of the virtual image that can be detected under the maximum white image brightness of the HUD display, the relationship between the ambient light and the Deboer coefficient of this product design is obtained. Referring to the Deboer coefficient recommendation, for example, selecting 2, the maximum HUD brightness acceptable to the human eye under different ambient light backgrounds can be inversely deduced, and thus the maximum brightness acceptable to the human eye that does not cause blindness can be obtained.

[0019] Preferably, step S5 is specifically as follows:

[0020] S51: Real-time obtain the image data to be displayed on the HUD, parse the image data to be displayed on the HUD, and extract the average grayscale of the whole image;

[0021] S52: Calculate the overall average grayscale of the image, and the formula is:

[0022] C grey = 0.2989C red + 0.5870C green + 0.114C blue ;

[0023] S53: Linearly couple the HUD backlight current with the average grayscale of the image, and apply the ISO 26262 safety brightness upper limit Lsafe constraint to obtain the maximum acceptable HUD virtual image brightness Lsafe for the human eye;

[0024] S54: Convert the HUD virtual image brightness Lsafe into a high-frequency PWM signal to drive the HUD light source; or control the backlight brightness through the brightness driving chip via SPI or I2C.

[0025] When the ambient light is lower than a certain threshold, the system automatically switches to the night mode to reduce the HUD brightness.

[0026] When the ambient light sensor has an abnormal mutation or is lost, the ambient light is treated as 0, and the HUD backlight is set to the lowest brightness.

[0027] In a second aspect, a brightness control system for a vehicle-mounted head-up display, the system includes:

[0028] The first data processing unit receives environmental data collected by vehicle-mounted sensors, filters and fuses the collected environmental parameters, and generates global ambient light intensity parameters;

[0029] The second data processing unit is used to calculate the effective field of view within the driver's eye box according to the design parameters of the HUD optical system;

[0030] The third data processing unit is used to calculate the HUD display brightness corresponding to different De Boer coefficients under the current ambient light intensity according to the global ambient light intensity parameters and the effective field of view;

[0031] The regulation unit controls the brightness of the vehicle-mounted head-up display according to the HUD display brightness.

[0032] In a third aspect, a display uses the brightness control method for a vehicle-mounted head-up display described in the first aspect to regulate the brightness.

[0033] Compared with the prior art, the beneficial effects of this application are as follows:

[0034] This application collects ambient light intensity parameters in real time through a photosensitive sensor, establishes a human eye adaptation model in combination with the HUD field of view characteristics, and dynamically infers the maximum acceptable brightness threshold under different environments based on the De Boer coefficient. An innovative dual compensation mechanism is constructed to non-linearly couple and calculate the RGB gray-scale characteristics of the image and the background light brightness, and the brightness control is realized through the PWM dimming module.

[0035] This solution breaks through the limitation of the traditional fixed brightness threshold, establishes a three-dimensional mapping relationship of ambient light - display content - human eye perception, provides a theoretical basis, and realizes the dynamic closed-loop regulation of brightness adaptation. It effectively prevents the phenomenon of visual blindness caused by the over-brightness of the HUD under low ambient light, the reflection of instantaneous strong light, or the sudden appearance of bright elements in a dark scene, significantly improves the functional safety level of the vehicle-mounted HUD system, and meets the safety requirements of ISO 26262 ASIL-B level. Description of the Drawings

[0036] Figure 1 is a flowchart of the brightness control method for a vehicle-mounted head-up display shown in an embodiment of this application.

[0037] Figure 2 is the safe display brightness under different DeBor coefficients shown in an embodiment of this application. Detailed Embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in combination with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0039] Embodiment 1: A brightness control method for an in-vehicle head-up display, the method comprising:

[0040] S1: Collect environmental parameters;

[0041] Preferably, the environmental parameters include vehicle front ambient light intensity information from a front windshield sensor and vehicle upper ambient light intensity information from a cockpit top sensor. Install a sunlight and rain sensor on the vehicle's front windshield and a high-precision photosensitive sensor on the top of the cockpit to collect ambient light intensity (unit: lux) and color temperature parameters in real time. These sensors can not only sense changes in sunlight but also identify light differences under different weather conditions such as cloudy and rainy days. In addition, they can detect the illumination of street lights at night or the headlights of oncoming vehicles, ensuring accurate capture of light information in various complex environments. When there are significant differences or direct loss in the detection values of the ambient light sensors, to ensure no glare, the HUD directly reduces the backlight to the lowest safe brightness or turns off the display and reports a fault message.

[0042] S2: Perform filtering and fusion processing on the environmental parameters to generate a global ambient light intensity parameter;

[0043] Perform noise reduction processing on multi-sensor data through a filtering algorithm to eliminate instantaneous interferences (such as lightning, mirror reflections, street lights, entering and exiting tunnels, etc.). The forward light sensor is installed at the front of the vehicle to detect the vehicle front ambient light intensity (such as tunnel entrances, oncoming vehicle headlights). The top light sensor is installed on the roof of the vehicle to detect the vehicle upper ambient light intensity (such as tunnel ceiling lights, street lights). Perform low-pass filtering (such as moving window averaging or Kalman filtering) on the original light intensity data (L_front, L_top) to eliminate instantaneous noise.

[0044] Preferably, step S2 is specifically: perform low-pass filtering processing on the environmental parameters, and use a weighted average algorithm to fuse the vehicle front ambient light intensity information and the vehicle upper ambient light intensity information to generate a global ambient light intensity parameter;

[0045] Among them, according to the spatial relationship between the installation positions of each sensor and the driver's line of sight, a weight coefficient of 0.6 to 0.8 is assigned to the front windshield sensor, and a weight coefficient of 0.2 to 0.4 is assigned to the cockpit top sensor.

[0046] Allocate weights w1 (forward) and w2 (topward) according to sensor characteristics or application requirements

[0047] Calculate E using the weighted average formula:

[0048] E = w1·F + w2·T;

[0049] By flexibly allocating weights, multi-sensor data can be effectively fused to improve the robustness of ambient light estimation.

[0050] S3: Calculate the effective field of view within the driver's eye box according to the design parameters of the HUD optical system;

[0051] According to the design parameters of the HUD optical system (such as projection distance, virtual image size, divergence angle), calculate the effective field of view (FOV) within the driver's eye box. The typical values are 5° - 15° horizontally and 2° - 5° vertically.

[0052] S4: Calculate the HUD display brightness corresponding to different De Boer coefficients under the current ambient light intensity based on the global ambient light intensity parameter and the effective field of view. The HUD display brightness is the maximum HUD brightness acceptable to the human eye under the current external ambient light. When the ambient light is below a certain threshold, the system automatically switches to the night mode to reduce the HUD brightness and minimize the impact on the driver's night vision.

[0053] De Boer coefficient Reference evaluation 1 Unbearable cannot be accepted 3 Disturbing 5 Just admissible 7 Acceptable 9 Noticeable ;

[0054] Preferably, as Figure 2 shown, it is recommended to select 1 or 2 for the actual performance De Boer coefficient.

[0055] De Boer formula based on the human eye's sensitivity to glare:

[0056]

[0057] W = De Boer blinding level, (1 - 9 levels, the smaller the value, the higher the glare tolerance); Preferably, the De Boer blinding level is selected below 3.

[0058] L = HUD display brightness (cd / m 2 ).

[0059] θ = angle between the viewing angle and the blinding source (LDA, °). The HUD generally has the following downward viewing angles, not directly in front of the driver's line of sight, and requires a few degrees downward, usually 2 - 4 degrees.

[0060] E = Ambient light received by the driver's eyes (lux), i.e., the magnitude of the ambient light in the environment where the driver is located. Generally, indoor lighting is about 300 lux, about 10 - 50 lux under streetlights at night, and basically above 1000 lux during the day.

[0061] Among them, W is the De Boer score (from 1 to 9 levels, the smaller the value, the higher the glare tolerance).

[0062] Preferably, in order to further illustrate the relationship between the product design ambient light and the Deboer coefficient based on the ambient light brightness where the driver is located, the position of the light source, and the maximum brightness of the virtual image that can be detected under the maximum white image brightness of the HUD display, and to reverse - infer the maximum HUD brightness that the human eye can accept under different ambient light backgrounds, multiple different ambient light brightness scenarios can also be considered. For example: Indoor dim light environment: The ambient light brightness is about 10 lux. Cloudy outdoor environment: The ambient light brightness is about 1000 lux. Sunny outdoor environment: The ambient light brightness is about 10000 lux. Fix the light source at different angles in the forward field of view, such as 0°, 10°, 20°, etc. Under different ambient light brightness and light source angles, gradually increase the brightness of the HUD display white image until the observer can just detect the maximum brightness of the HUD virtual image, and use a photometer to measure and record this value. Then establish the relationship between the Deboer coefficient and the ambient light:

[0063] The relationship between the Deboer coefficient, the ambient light brightness, and the maximum detectable brightness of the HUD virtual image can be expressed as:

[0064]

[0065] Calculate the Deboer coefficient in different environments. According to the collected data, calculate the Deboer coefficient K for each experimental environment. For example, in the indoor dim light environment (10 lux), the Deboer coefficient is 2.

[0066] Based on the above, reverse - infer the maximum HUD brightness that the human eye can accept: With the Deboer coefficient being 2, calculate the maximum HUD brightness under different ambient lights. According to the definition of the Deboer coefficient, the maximum HUD brightness that the human eye can accept under different ambient light backgrounds can be reverse - inferred.

[0067] Comprehensively, it can be obtained that:

[0068] For the indoor dim light environment of 10 lux, the maximum HUD brightness that the human eye can accept is 20 cd / m².

[0069] For the cloudy outdoor environment of 1000 lux, the maximum HUD brightness that the human eye can accept is 2000 cd / m².

[0070] For an outdoor sunny environment of 10000 lux, the maximum HUD brightness acceptable to the human eye is 20000 cd / m2.

[0071] Verify the calculated maximum HUD brightness in the actual driving environment to observe whether the driver will feel dazzled or blinded. If problems are found, adjust the Deboer coefficient or re-collect data to optimize the calculation results.

[0072] Through the above steps, the relationship between the ambient light of the product design and the Deboer coefficient can be obtained, and the maximum HUD brightness acceptable to the human eye under different ambient light backgrounds can be deduced inversely, so as to ensure that the HUD display will not cause the driver to be blinded.

[0073] S5: Perform brightness control of the in-vehicle head-up display according to the HUD display brightness.

[0074] The method proposed in this application obtains the current ambient light intensity and adjusts the HUD display brightness according to this light intensity, so as to maintain the best display effect under various lighting conditions. Especially in strong light or low light environments, it can effectively avoid visual discomfort and information loss caused by over-bright or over-dark displays. This method can calculate the maximum HUD display brightness acceptable to the human eye under different lighting conditions. This brightness control method not only considers the influence of external lighting, but also combines the design parameters of the in-vehicle system, inversely deduces the optimal display brightness dynamically, and dynamically calculates the brightness adjustment value under different lighting conditions by using the De Boer coefficient, and can adjust the brightness of the HUD display in real time according to the external light environment.

[0075] Preferably, step S3 is specifically: based on the De Boer formula for the human eye's sensitivity to glare, select different DeBoer coefficients for dynamic inversion to obtain the effective field of view angle.

[0076] Preferably, step S5 is specifically:

[0077] S51: Obtain the HUD image data to be displayed in real time, parse the HUD image data to be displayed, and extract the average grayscale of the whole image;

[0078] Image data is usually stored in the form of a pixel matrix, which may be an RGB (red, green, blue) or grayscale (single-channel) image. When parsing the image, convert this data into a format suitable for calculation, convert the RGB image into a grayscale image, or directly process the grayscale image. The parsed data can be a two-dimensional matrix, where each value represents the grayscale value of the corresponding pixel in the image.

[0079] After parsing the image data, the average grayscale value of the image can be calculated. The average grayscale value represents the brightness level of the entire image and reflects the overall light and dark situation of the image. This calculation is obtained by averaging the grayscale values of all pixels in the image.

[0080] S52: Calculate the overall average grayscale of the image:

[0081] The video processing chip obtains the HUD image data to be displayed in real time, extracts the grayscale values of the RGB three channels of each frame of the image, calculates the overall average grayscale of the image, referring to the following formula, and calibrates the parameters according to the actual RGB-to-brightness ratio of the HUD:

[0082] C grey = 0.2989C red + 0.5870C green + 0.114C blue ;

[0083] S53: According to the ISO26262 ASIL-B level functional safety requirements, set the HUD brightness upper limit Lsafe under different ambient lights, confirm the maximum backlight brightness at which the HUD does not cause blindness according to the current image grayscale, and ensure that the HUD display brightness is always less than the safety brightness Lsafe during vehicle driving. Specifically: linearly couple the HUD backlight current with the average grayscale of the image, and apply the ISO26262 safety brightness upper limit Lsafe constraint to obtain the maximum acceptable HUD virtual image brightness Lsafe for the human eye;

[0084] Assume that there is a certain linear relationship between the brightness (image brightness) of the HUD and the backlight current. Specifically, the backlight current I backlight and the average grayscale value G of the entire image avg The relationship between them can be expressed as:

[0085] G avg = a·I backlinght + b;

[0086] Through this linear relationship, the average grayscale of the image can be controlled by adjusting the backlight current, thereby affecting the brightness of the HUD.

[0087] ISO 26262 is an automotive functional safety standard that stipulates various safety requirements in vehicle systems. To ensure the display safety of the HUD, it is necessary to impose an upper limit on the virtual image brightness according to the requirements of ISO26262. This safety brightness upper limit Lsafe is the maximum brightness value that the human eye can accept. Exceeding this brightness may cause discomfort or visual fatigue, and even affect driving safety.

[0088] According to the safety standard requirements of ISO 26262, we need to ensure that the maximum brightness Lmax does not exceed the safety brightness upper limit Lsafe, that is:

[0089] L image ≤ L safe ;

[0090] Combined with the above linear coupling relationship, the following can be obtained:

[0091] k·G avg <L safe ;

[0092] Based on this, according to the relationship between G avg and the backlight current I backlight (obtained from the previous linear coupling), the maximum value of the backlight current can be calculated, thereby restricting it not to exceed the corresponding safe brightness upper limit:

[0093] Calculate the maximum backlight current:

[0094]

[0095] Then substitute it into the linear relationship:

[0096]

[0097] Obtain the maximum backlight current I backlightmax , that is:

[0098]

[0099] The backlight current I backlight should not exceed the above maximum value I backlightmax , thereby ensuring that the brightness does not exceed the safe brightness Lsafe.

[0100] Finally, by adjusting the backlight current and the image gray level, it can be ensured that the virtual image brightness of the HUD meets the safety requirements of ISO 26262, avoiding discomfort to the driver's vision.

[0101] S54: Convert the HUD virtual image brightness Lsafe into a high-frequency PWM signal to drive the HUD light source; or control the backlight brightness through the brightness driving chip via SPI or I2C.

[0102] Preferably, convert the target brightness Ltarget into a PWM duty cycle:

[0103]

[0104] where D is the PWM duty cycle (between 0 and 1), and Lmax_pwm is the maximum brightness of the HUD light source. Drive the LED light source with high-frequency PWM (≥1kHz) to avoid visual fatigue caused by low-frequency flicker.

[0105] To avoid visual fatigue caused by low-frequency flicker, the frequency of the PWM signal should be at least 1kHz or higher. Preferably, the frequency of the PWM signal should be set between 1kHz and 10kHz, so that the human eye can hardly perceive the flicker effect.

[0106] Among them, the high-frequency PWM signal is used to drive the LED light source. The LED driving circuit receives a periodic PWM signal and controls the average brightness of the LED by adjusting the duty cycle. The larger the duty cycle, the stronger the average light brightness emitted by the LED. By controlling the PWM duty cycle, the brightness of the LED light source can accurately follow the target brightness Ltarget.

[0107] If an SPI or I2C interface is used to control the brightness driving chip, the brightness control can be completed by sending a digital signal to the driving chip. In this case, the LED driving chip generates a corresponding PWM signal according to the received brightness value. This method is applicable to more complex HUD systems, where there may be multiple LEDs or other control requirements.

[0108] To automatically switch to the night mode and reduce the HUD brightness when the ambient light is below a certain threshold, and to process the ambient light as 0 and set the HUD backlight to the lowest brightness after an abnormal mutation or loss of the ambient light sensor, the following can also be done:

[0109] When the ambient light is below a certain threshold, the system automatically switches to the night mode, and the HUD display brightness can be reduced by adjusting the PWM duty cycle (such as reducing the duty cycle of the PWM signal).

[0110] Whether a mutation has occurred is judged by the change rate of the sensor value or the difference from the previously read value. For example, if the change in the light value of the sensor is greater than the set threshold (such as 500 lx / s) within a short period of time, it is determined as a mutation.

[0111] If the sensor signal is lost or abnormal, it can usually be judged by setting a timeout mechanism. For example, if the sampled data is empty or the data change is abnormal for several consecutive times, it is determined that the sensor is lost.

[0112] When the ambient light sensor has an abnormal mutation or is lost, the ambient light is processed as 0, and the HUD backlight is set to the lowest brightness.

[0113] Embodiment 2, a brightness control system for an in-vehicle head-up display, the system includes:

[0114] A first data processing unit, which receives the environmental data collected by the vehicle-mounted sensors, filters and fuses the collected environmental parameters, and generates a global ambient light intensity parameter; preferably, the vehicle-mounted sensors can be any one or more of an ambient light sensor, an accelerometer, and a temperature sensor.

[0115] A second data processing unit for calculating an effective field of view angle within the driver's eye box according to the design parameters of the HUD optical system; this field of view angle can be used to determine which parts of the HUD content will be displayed, as well as the size of the display area and the accuracy of brightness adjustment.

[0116] A third data processing unit for calculating the HUD display brightness corresponding to different De Boer coefficients under the current ambient light intensity according to the global ambient light intensity parameter and the effective field of view angle; among them, the De Boer coefficient reflects the relationship between the ambient light intensity and the display brightness. According to the De Boer coefficient, the brightness of the HUD display is adjusted under different lighting conditions to ensure that the driver can clearly see the head-up display content in different environments.

[0117] A regulation unit for controlling the brightness of the in-vehicle head-up display according to the HUD display brightness.

[0118] Embodiment 3, a display, wherein the display uses the brightness control method for an in-vehicle head-up display as described in the first aspect for brightness regulation.

[0119] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application thereto. Those of ordinary skill in the art can make various changes and modifications therein without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as claimed in the appended claims.

[0120] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0121] Although the description of the present application is made in conjunction with the above specific embodiments, it is obvious that those skilled in the art can make many substitutions, modifications and changes based on the above content. Therefore, all such substitutions, modifications and changes are included within the spirit and scope of the appended claims.

Claims

1. A brightness control method for a vehicle head-up display, characterized in that, Including: S1: Collect environmental parameters; S2: Filter and fuse the environmental parameters to generate a global ambient light intensity parameter; S3: Calculate the effective field of view angle within the driver's eye box according to the design parameters of the HUD optical system; S4: Calculate the HUD display brightness corresponding to different De Boer coefficients under the current ambient light intensity according to the global ambient light intensity parameter and the effective field of view angle, where the HUD display brightness is the maximum HUD brightness acceptable to the human eye under the current external ambient light; S5: Control the brightness of the in-vehicle head-up display according to the HUD display brightness.

2. The brightness control method for a vehicle head-up display according to claim 1, wherein The environmental parameters include the vehicle front ambient light intensity information from the front windshield sensor and the vehicle upper ambient light intensity information from the cockpit top sensor.

3. A brightness control method for a vehicle head-up display according to claim 2, characterized in that, The step S2 is specifically: Perform low-pass filtering on the environmental parameters, and use a weighted average algorithm to fuse the vehicle front ambient light intensity information and the vehicle upper ambient light intensity information to generate a global ambient light intensity parameter; Among them, according to the spatial relationship between the installation positions of the sensors and the driver's line of sight, a weight coefficient of 0.6 to 0.8 is assigned to the front windshield sensor, and a weight coefficient of 0.2 to 0.4 is assigned to the cockpit top sensor.

4. A brightness control method for an in-vehicle head-up display according to claim 3, characterized in that, The step S3 is specifically: Based on the De Boer formula for the human eye's sensitivity to glare, select different De Boer coefficients for dynamic inversion to obtain the effective field of view angle.

5. A brightness control method for an in-vehicle head-up display according to claim 4, characterized in that, The step S5 is specifically: S51: Real-time obtain the HUD image data to be displayed, parse the HUD image data to be displayed, and extract the full-image average gray level of the image; S52: Calculate the overall average gray level of the image, and the formula is: C grey = 0.2989C red + 0.5870C green + 0.114C blue ; S53: Linearly couple the HUD backlight current and the image average gray level, and apply the ISO 26262 safety brightness upper limit Lsafe constraint to obtain the maximum acceptable HUD virtual image brightness Lsafe for the human eye; S54: Convert the HUD virtual image brightness Lsafe into a high-frequency PWM signal to drive the HUD light source; or control the backlight brightness through a brightness driving chip via SPI or I2C.

6. The brightness control method for a vehicle head-up display according to claim 5, characterized in that, Also including: When the ambient light is lower than a certain threshold, the system automatically switches to the night mode to reduce the HUD brightness.

7. A brightness control method for an in-vehicle head-up display according to claim 6, characterized in that, Also including: When the ambient light sensor has an abnormal mutation or is lost, the ambient light is treated as 0, and the HUD backlight is set to the lowest brightness.

8. A control system for the brightness control method of a vehicle head-up display according to any one of claims 1-7, characterized in that, The system includes: The first data processing unit receives the environmental data collected by the vehicle-mounted sensors, and filters and fuses the collected environmental parameters to generate a global ambient light intensity parameter; The second data processing unit is used to calculate the effective field of view angle within the driver's eye box according to the design parameters of the HUD optical system; The third data processing unit is used to calculate the HUD display brightness corresponding to different De Boer coefficients under the current ambient light intensity according to the global ambient light intensity parameter and the effective field of view angle; The regulation unit controls the brightness of the in-vehicle head-up display according to the HUD display brightness.

9. A display, characterized in that, The display uses the brightness control method for the in-vehicle head-up display as described in any one of claims 1-7 for brightness regulation.

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