Brightness adjusting method and head-up display

Abstract

The invention provides a brightness adjusting method and a head-up display. The brightness adjusting method comprises the following steps: S110, acquiring effective ambient light illuminance at the current moment; s120, target virtual image brightness at the current moment is determined according to the effective environment illuminance and a first relation, and the first relation is the corresponding relation between the effective environment illuminance and the target virtual image brightness; s130, according to the target virtual image brightness, the actual virtual image brightness at the previous moment and a sensitivity coefficient, the actual virtual image brightness at the current moment is determined, and the sensitivity coefficient is related to the perception ability of human eyes; and S140, controlling the head-up display to carry out brightness adjustment according to the actual virtual image brightness at the current moment. According to the brightness adjusting method, the virtual image brightness of the head-up display can be quickly and smoothly adjusted according to the effective ambient illuminance and the sensitivity coefficient, and comfortable visual experience is provided for a user.

Description

Technical Field

[0001] The present invention generally relates to the field of brightness adjustment of a head-up display, and in particular to a brightness adjustment method and a head-up display. Background Art

[0002] Head-up display (HUD), also known as head-up display, was originally designed for military fighter jets to help pilots view key information at any time during flight. In recent years, automotive head-up display technology has gradually matured, and can project important driving information such as speed and navigation directly onto the windshield in front of the driver. This design allows drivers to obtain the required information without lowering their heads, effectively reducing cognitive load and significantly improving driving safety.

[0003] During the driving process, the change of sunlight angle, entering and exiting shadows or tunnels / basements will also cause the driver's perceived ambient brightness to change continuously. If the brightness of the virtual image of the head-up display is too low, the driver may have difficulty seeing the information; if the brightness is too high, it may cause glare. Therefore, in order to ensure that the head-up display can provide a comfortable visual experience in different environments, the virtual image brightness of the head-up display needs to be automatically adjusted according to the ambient brightness.

[0004] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the prior art in the field. Summary of the invention

[0005] In view of one or more defects in the prior art, the present invention provides a brightness adjustment method for a head-up display, comprising: S110: Obtaining the effective ambient light illumination at the current moment; S120: determining the target virtual image brightness at the current moment according to the effective ambient light illumination and a first relationship, wherein the first relationship is a corresponding relationship between the effective ambient light illumination and the target virtual image brightness; S130: determining the actual virtual image brightness at the current moment according to the target virtual image brightness, the actual virtual image brightness at the previous moment, and a sensitivity coefficient, wherein the sensitivity coefficient is related to the perception ability of the human eye; S140: Controlling the head-up display to adjust brightness according to the actual virtual image brightness at the current moment.

[0006] According to one aspect of the present invention, step S110 includes: acquiring the ambient light illumination based on the light illumination sensor, and using the ambient light illumination as the effective ambient light illumination at the current moment.

[0007] According to one aspect of the present invention, step S110 includes: Based on the light sensor, the ambient light intensity is obtained at preset time intervals, and a historical data queue of the ambient light intensity is established; Extract multiple ambient light illuminations from the ambient light illumination history data queue, perform filtering processing on the multiple ambient light illuminations, and use the filtering processing result as the effective ambient light illumination at the current moment.

[0008] According to one aspect of the present invention, the filtering process is mean filtering or median filtering.

[0009] According to one aspect of the present invention, the first relationship is a mapping table of the effective ambient light illumination and the target virtual image brightness; or, the first relationship is a correlation function of the effective ambient light illumination and the target virtual image brightness, and the correlation function is: ; Among them, I is the effective ambient light illumination, B is the target virtual image brightness, and a and b are optimization parameters.

[0010] According to one aspect of the present invention, step S130 includes: Comparing the actual virtual image brightness at the previous moment with the target virtual image brightness; If the target virtual image brightness is less than the actual virtual image brightness at the previous moment, compare the reduction rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a first threshold, If the reduction rate is less than or equal to the first threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the reduction rate is greater than a first threshold, determining the actual virtual image brightness at the current moment based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, the actual virtual image brightness at the current moment being less than the actual virtual image brightness at the previous moment; If the target virtual image brightness is not less than the actual virtual image brightness at the previous moment, compare the growth rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a second threshold, If the growth rate is less than or equal to the second threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the growth rate is greater than a second threshold, the actual virtual image brightness at the current moment is determined based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, and the actual virtual image brightness at the current moment is greater than the actual virtual image brightness at the previous moment.

[0011] According to one aspect of the present invention, the first threshold is , where p is the first control parameter, is the sensitivity coefficient.

[0012] According to one aspect of the present invention, the first control parameter p=1.

[0013] According to one aspect of the present invention, when the reduction rate is greater than the first threshold, the actual virtual image brightness at the current moment is determined according to the following formula: , ,in, is the actual virtual image brightness at the previous moment, is the brightness of the target virtual image.

[0014] According to one aspect of the present invention, the second threshold is , where q is the second control parameter and σ is the sensitivity coefficient.

[0015] According to one aspect of the present invention, the second control parameter q∈[1,5].

[0016] According to one aspect of the present invention, when the growth rate is greater than the second threshold, the actual virtual image brightness at the current moment is determined according to the following formula: , ,in, is the actual virtual image brightness at the previous moment, is the brightness of the target virtual image.

[0017] According to one aspect of the present invention, the sensitivity coefficient is characterized by the minimum change rate or minimum change amount of the virtual image brightness change of the head-up display that can be perceived by human eyes at the current brightness.

[0018] According to one aspect of the present invention, step S140 includes: outputting a brightness control signal based on the actual virtual image brightness at the current moment and a second relationship, thereby controlling the head-up display to adjust the brightness, wherein the second relationship is the corresponding relationship between the actual virtual image brightness at the current moment and the brightness control signal, and the brightness control signal is a pulse width modulation signal.

[0019] According to one aspect of the present invention, the brightness adjustment method further includes: cyclically executing steps S110-S140 at preset time intervals.

[0020] The present invention also provides a head-up display, comprising: Backlight module; a light level sensor configured to measure ambient light levels; and A control module, coupled to the backlight module and the light sensor, respectively, the control module being configured to: determine the effective ambient light illumination at the current moment based on the ambient light illumination measured by the light sensor, determine the target virtual image brightness at the current moment according to the effective ambient light illumination and the first relationship, further determine the actual virtual image brightness at the current moment according to the target virtual image brightness, the actual virtual image brightness at the previous moment and the sensitivity coefficient, and control the backlight module according to the actual virtual image brightness at the current moment; Among them, the first relationship is the corresponding relationship between the effective ambient light illumination and the target virtual image brightness, and the sensitivity coefficient is related to the perception ability of the human eye.

[0021] According to one aspect of the present invention, the control module is configured to obtain the ambient light illumination based on the light illumination sensor, and use the ambient light illumination as the effective ambient light illumination at the current moment.

[0022] According to one aspect of the present invention, the control module is configured as follows: Based on the light sensor, the ambient light intensity is obtained at preset time intervals, and a historical data queue of the ambient light intensity is established; Extract multiple ambient light illuminations from the ambient light illumination history data queue, perform filtering processing on the multiple ambient light illuminations, and use the filtering processing result as the ambient light illumination at the current moment.

[0023] Comparing the actual virtual image brightness at the previous moment with the target virtual image brightness; If the target virtual image brightness is less than the actual virtual image brightness at the previous moment, compare the reduction rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a first threshold, If the reduction rate is less than or equal to the first threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the reduction rate is greater than a first threshold, determining the actual virtual image brightness at the current moment based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, the actual virtual image brightness at the current moment being less than the actual virtual image brightness at the previous moment; If the target virtual image brightness is not less than the actual virtual image brightness at the previous moment, compare the growth rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a second threshold, If the growth rate is less than or equal to the second threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the growth rate is greater than a second threshold, the actual virtual image brightness at the current moment is determined based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, and the actual virtual image brightness at the current moment is greater than the actual virtual image brightness at the previous moment.

[0024] According to one aspect of the present invention, the control module is configured to output a brightness control signal according to the actual virtual image brightness at the current moment and a second relationship, wherein the second relationship is a corresponding relationship between the actual virtual image brightness at the current moment and the brightness control signal.

[0025] Compared with the prior art, the embodiments of the present invention provide a brightness adjustment method and a head-up display, which can quickly and smoothly adjust the virtual image brightness of the head-up display according to the effective ambient light illumination and the sensitivity coefficient, thereby providing a comfortable visual experience for the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 A flow chart showing a method for adjusting brightness of a head-up display according to an embodiment of the present invention is shown; Figure 2 A schematic diagram of an application scenario of a head-up display according to an embodiment of the present invention is shown; Figure 3 A flowchart of step S130 according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of a head-up display according to an embodiment of the present invention is shown.

[0027] In the figure: 100, brightness adjustment method; 200, head-up display; 210, backlight module; 220, light intensity sensor; 230, backlight module. DETAILED DESCRIPTION

[0028] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0033] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0034] Figure 1 FIG. 1 is a flow chart showing a method 100 for adjusting brightness of a head-up display according to an embodiment of the present invention. Figure 1 As shown, the brightness adjustment method 100 includes the following steps, and each step is described in detail below.

[0035] In step S110: the effective ambient light illumination at the current moment is obtained.

[0036] Figure 2 FIG. 4 shows a schematic diagram of an application scenario of a head-up display according to an embodiment of the present invention. Figure 2 As shown, in the vehicle scene, a head-up display is provided on the dashboard to project a virtual image to the target area in front of the driver, such as vehicle speed, navigation information, etc. A light intensity sensor is also provided in the vehicle to sense the effective ambient light intensity outside the vehicle, such as sensing the effective ambient light intensity of the target area. The light intensity sensor can be provided independently of the head-up display or integrated in the head-up display.

[0037] In some embodiments, the ambient light illumination of the target area can be collected by the light illumination sensor at the current moment, and the ambient light illumination is used as the effective ambient light illumination at the current moment. The target area can be, for example, the virtual image background area of ​​the head-up display.

[0038] In some other embodiments, the ambient light illumination of the target area can be collected at preset time intervals by the light illumination sensor. For example, the ambient light illumination of the target area is collected in turn every t1 time. An ambient light illumination history data queue can be established to record and store ambient light illumination data. The ambient light illumination history data queue has a preset queue length, and the queue length represents the time length of the ambient light illumination retained in the ambient light illumination history data queue. For example, when the queue length is 10 seconds, the ambient light illumination is retained in the ambient light illumination history data queue for 10 seconds. Whenever the light illumination sensor obtains the ambient light illumination once, the latest ambient light illumination can be inserted into the ambient light illumination history data queue, and the oldest ambient light illumination in the ambient light illumination history data queue is deleted. Optionally, in the ambient light illumination history data queue, the ambient light illumination is sorted according to the order of entering the queue. Whenever the light illumination sensor obtains the ambient light illumination once, the latest ambient light illumination is inserted into the tail of the ambient light illumination history data queue, and the head data of the ambient light illumination history data queue is deleted.

[0039] Multiple ambient light illuminations can be extracted from the ambient light illumination history data queue, and these ambient light illuminations are filtered, and the result of the filtering process is used as the effective ambient light illumination at the current moment, so as to reduce the influence of random fluctuations and abnormal values, accurately reflect the illumination conditions of the current environment, and provide a solid data basis for subsequent analysis and decision-making. In this embodiment, the filtering process adopts mean filtering, for example: the latest M ambient light illumination data can be selected from the ambient light illumination history data queue, their average value can be calculated, and this average value can be used as the effective ambient light illumination at the current moment. In other embodiments, filtering methods such as median filtering can also be selected for filtering according to actual application requirements and the characteristics of ambient light illumination data. Median filtering is to sort the extracted multiple (M) ambient light illuminations by size, and take the middle value as the effective ambient light illumination at the current moment. This method has a good inhibitory effect on extreme values ​​and noise.

[0040] The target virtual image brightness refers to the brightness level that the virtual image projected by the head-up display should reach in a static environment (i.e., when the ambient light illumination remains basically unchanged) in order to achieve the best visual effect and user experience and reduce the visual burden of the driver. Different ambient light illuminations have corresponding target virtual image brightnesses. The target virtual image brightness corresponding to the ambient light illumination can be determined experimentally, for example: Under the lighting conditions of the environment, the tester observes the virtual image projected by the head-up display and gradually adjusts the virtual image brightness of the head-up display. When the tester believes that the virtual image is clearly visible and does not cause visual fatigue or discomfort, the virtual image brightness of the head-up display is the ambient light illuminance. The corresponding target virtual image brightness. Those skilled in the art will appreciate that, in order to improve accuracy, multiple testers may perform tests separately, and perform statistical and analytical processing (eg, calculating the average or median) on the test results to obtain a more accurate target virtual image brightness.

[0041] The first relationship is the corresponding relationship between the effective ambient light illumination and the target virtual image brightness. In a specific embodiment, the first relationship can be a mapping table, which corresponds the effective ambient light illumination to the target virtual image brightness. Once the effective ambient light illumination at a certain moment is determined, the target virtual image brightness at the same moment can be determined by querying this mapping table (first relationship). In some embodiments, the first relationship can also be a correlation function, which links the effective ambient light illumination to the target virtual image brightness. After determining the effective ambient light illumination at a certain moment, the target virtual image brightness at the same moment can be calculated by substituting the effective ambient light illumination at that moment into the correlation function. The correlation function can be determined, for example, in the following manner: first, the target virtual image brightness corresponding to different ambient light illuminations is determined by experimental measurement (which can be completed by one tester or by multiple testers). Then, the standard curve of ambient light illumination and target virtual image brightness is fitted using an optimization method (such as the least squares method), thereby obtaining a correlation function (mathematical model) between the effective ambient light illumination and the target virtual image brightness. Optionally, the correlation function between the effective ambient light illumination and the target virtual image brightness can be: , where I is the effective ambient light illumination, B is the target virtual image brightness, a and b are optimization parameters, which can be obtained through multiple experimental measurements.

[0042] Step S130: Determine the actual virtual image brightness at the current moment based on the target virtual image brightness, the actual virtual image brightness at the previous moment, and the sensitivity coefficient. .

[0043] The actual virtual image brightness at the previous moment refers to the brightness of the virtual image projected by the head-up display at the previous moment. The actual virtual image brightness at the current moment refers to the brightness of the virtual image that the head-up display will project at the current moment. The head-up display adjusts the brightness of the virtual image it projects, for example, at a fixed time interval △t. The current moment is taken as the zero moment, and the previous moment is, for example, the -△t moment. The time interval △t is, for example, 0.1 seconds, 0.2 seconds, 0.5 seconds, 1 second, 2 seconds, 5 seconds, 10 seconds or a longer time interval. Other values ​​are also within the scope of the present disclosure. Correspondingly, the illuminance sensor can collect the ambient light illuminance of the target area at a time interval of △t'. △t' and △t may be the same or different, and the present invention is not limited thereto.

[0044] The sensitivity coefficient is related to the perception ability of the human eye. In a specific implementation, the sensitivity coefficient can be characterized by the minimum change rate or minimum change amount of the virtual image brightness change of the head-up display that the human eye can perceive at the current brightness. The following description takes the minimum change rate as an example. ,in, is the virtual image brightness of the head-up display, is the minimum brightness change that can be perceived by the human eye at the virtual image brightness B. The sensitivity coefficient can be determined experimentally. It is described in detail below. The head-up display usually has a preset virtual image brightness range ( , ), through the following steps of determining the sensitivity coefficient, the preset interval can be divided into (n+1) brightness, which are ( = , …, ), and the minimum brightness change perceptible to the human eye at each virtual image brightness can be determined respectively. The experimental steps for determining the sensitivity coefficient may include, for example:

[0045] First, adjust the virtual image brightness of the head-up display to the lowest virtual image brightness. .

[0046] Secondly, the virtual image brightness of the head-up display is changed from Adjust to , and observe with the naked eye whether the virtual image brightness changes. If the virtual image brightness does not change, adjust the virtual image brightness back to , and increase , and then again change the virtual image brightness from Adjust to , and observe with the naked eye whether the virtual image brightness changes. If the virtual image brightness changes, Recorded as .in, The initial value of is preferably the virtual image brightness The minimum increase in brightness of the virtual image that can be adjusted nearby usually corresponds to the minimum brightness change that the head-up display can support on the hardware. In this way, the virtual image brightness can be determined more accurately. The minimum brightness change that can be perceived by the human eye nearby is based on the as well as , the sensitivity coefficient characterized by the minimum rate of change can be determined.

[0047] Then, determine the virtual image brightness The minimum brightness change that can be perceived by the human eye nearby. Specifically, when the head-up display ends at the previous step, the virtual image brightness is , change the virtual image brightness from Adjust to , and observe with the naked eye whether the virtual image brightness changes. If the virtual image brightness does not change, adjust the virtual image brightness back to , and increase , and then again change the virtual image brightness from Adjust to This process is repeated until the virtual image brightness changes. Recorded as .in, The initial value of is preferably the virtual image brightness The minimum increase in brightness of the virtual image that can be adjusted nearby usually corresponds to the minimum brightness change that the head-up display can support on the hardware. In this way, the virtual image brightness can be determined more accurately. The minimum brightness change that can be perceived by the human eye nearby is based on the as well as , the sensitivity coefficient characterized by the minimum rate of change can be determined.

[0048] After that, the above methods can be used to determine the , , , …, , "as well as" , , , …, ",in, , It is the maximum virtual image brightness that the head-up display can achieve.

[0049] Finally, the virtual image brightness " , , …, "And the corresponding minimum brightness change" , , …, "Linear regression analysis was performed, in which the virtual image brightness" , , …, "As the variable on the horizontal axis, the minimum brightness change" , , …, " is used as the variable on the ordinate axis. Through this linear regression analysis, a fitting straight line can be obtained. The slope of the fitting straight line is the sensitivity coefficient. The sensitivity coefficient is applicable to all virtual image brightnesses of the head-up display and can be used as a universal parameter to describe the relationship between virtual image brightness and minimum brightness change. In addition, the virtual image brightness " , , …, "And the corresponding minimum brightness change" , , …, ", respectively determine the sensitivity coefficients corresponding to different virtual image brightness, for example: virtual image brightness The corresponding sensitivity coefficient , virtual image brightness The corresponding sensitivity coefficient , virtual image brightness The corresponding sensitivity coefficient Those skilled in the art will appreciate that, in order to improve accuracy, multiple testers may perform tests separately, and perform statistical and analytical processing (eg, calculating the average or median) on the test results to obtain a more accurate sensitivity coefficient.

[0050] Figure 3 FIG. 4 shows a flow chart of step S130 according to an embodiment of the present invention. Figure 3 As shown, step S130 at least includes steps S131-S136, which are described in detail below.

[0051] In step S131, the actual virtual image brightness at the previous moment can be compared The brightness of the target virtual image at the current moment , to determine the change trend (increase, decrease) of the virtual image brightness. Among them, if the target virtual image brightness at the current moment Smaller than the actual virtual image brightness at the previous moment , then go to step S132; if the current target virtual image brightness Not less than (greater than or equal to) the actual virtual image brightness at the previous moment , then go to step S134.

[0052] Step S132: Compare the brightness of the target virtual image at the current moment Compared with the actual virtual image brightness at the previous moment The reduction rate R d (R d = ) with the first threshold. The purpose of this comparison is to determine whether it is necessary to change the brightness of the virtual image. dis greater than the first threshold, then proceed to step S133; if the reduction rate R d If it is less than or equal to the first threshold, the process goes to step S136.

[0053] In step S133: based on the sensitivity coefficient and the actual virtual image brightness at the previous moment Determine the actual virtual image brightness at the current moment , where the actual virtual image brightness at the current moment is Smaller than the actual virtual image brightness at the previous moment . Alternatively, the formula " "Determine the actual virtual image brightness at the current moment , where: is the sensitivity coefficient, and p is the first control parameter. Optionally, the first threshold is the product of the sensitivity coefficient and the first control parameter ( ). The first control parameter is the control parameter when the virtual image brightness decreases. By adjusting the size of the first control parameter, the amplitude (ratio) of the single reduction in the virtual image brightness can be controlled, thereby managing the rate of reduction in the virtual image brightness. Given that it usually takes a long time for the human eye to adapt from a bright environment to a dark environment (i.e., the dark adaptation process), the first control parameter is usually set to 1 (p=1) so that the human eye can hardly feel the brightness change of the virtual image, providing the user with a more comfortable visual experience. Of course, the first control parameter is not limited to being set to 1, but can also be flexibly adjusted to other values ​​(such as 1, 1.5, 2, etc.) according to specific needs and environmental conditions. The larger the value of the first control parameter, the greater the reduction in the virtual image brightness, and the more obvious the human eye's perception of the virtual image brightness change. The value of the first control parameter can be set to be adjustable. By adjusting the value of the first control parameter, it can be ensured that the reduction in the virtual image brightness is both rapid and in line with the user's visual preferences, providing the user with a comfortable visual experience.

[0054] Step S134: Compare the current target virtual image brightness Compared with the actual virtual image brightness at the previous moment The rate of increase R i (R i = The purpose of this comparison is to determine whether it is necessary to change the brightness of the virtual image. i is greater than the second threshold, then proceed to step S135; if the rising rate R i If it is less than or equal to the second threshold, the process goes to step S136.

[0055] In step S135: based on the sensitivity coefficient and the actual virtual image brightness at the previous moment Determine the actual virtual image brightness at the current moment , where the actual virtual image brightness at the current moment is Greater than the actual virtual image brightness at the previous moment . Alternatively, the formula " "Determine the actual virtual image brightness at the current moment , where: is the sensitivity coefficient, and q is the second control parameter. Optionally, the second threshold is the product of the sensitivity coefficient and the second control parameter ( ). The second control parameter is the control parameter for the virtual image brightness growth. By adjusting the size of the second control parameter, the amplitude (ratio) of the single increase in the virtual image brightness can be controlled, thereby managing the rate of virtual image brightness growth. Given that the time required for the human eye to transition from a dark environment to a bright environment (i.e., the light adaptation process) is relatively short, the second control parameter can be set to any value in [1,5]. When the second control parameter is 1, the human eye can hardly feel the brightness change of the virtual image. Such a setting helps to provide a smooth and imperceptible brightness transition and reduce visual discomfort. The larger the value of the second control parameter, the greater the increase in the virtual image brightness, and the more obvious the human eye's perception of the virtual image brightness change. The value of the second control parameter can be set to be adjustable. By adjusting the value of the second control parameter, it can be ensured that the virtual image brightness grows both rapidly and in line with the user's visual preferences, providing the user with a comfortable visual experience.

[0056] In step S136: the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment to avoid frequent changes in virtual image brightness due to slight fluctuations in ambient light illumination. Frequent changes in virtual image brightness may cause people to mistakenly believe that the device has malfunctioned and may easily cause visual fatigue.

[0057] In step S140: according to the actual virtual image brightness at the current moment, the head-up display is controlled to adjust the brightness.

[0058] In a specific embodiment, a brightness control signal can be output according to the actual virtual image brightness at the current moment and the second relationship to control the head-up display to adjust the brightness. The second relationship mentioned here refers to the corresponding relationship between the actual virtual image brightness at the current moment and the brightness control signal. Optionally, the brightness control signal can be a pulse width modulation signal, and the second relationship can be a mapping table. Specifically, the mapping table corresponds the actual virtual image brightness to the duty cycle of the pulse width modulation signal. Once the actual virtual image brightness at the current moment is determined, the duty cycle of the pulse width modulation signal can be determined by querying this mapping table (second relationship). By adjusting the duty cycle of the pulse width modulation signal input to the head-up display, the luminous power of the backlight module of the head-up display can be controlled, thereby causing the virtual image brightness of the head-up display to change.

[0059] According to one embodiment of the present invention, steps S110-S140 may be cyclically executed at preset time intervals (for example, steps S110-S140 are executed once every Δt time interval) to achieve dynamic adjustment of the virtual image brightness, thereby ensuring that the virtual image brightness of the head-up display can adapt to changes in ambient light and provide users with a better visual experience.

[0060] Compared with the prior art, the embodiment of the present invention provides a brightness adjustment method 100, which realizes the control of the amplitude of a single change (increase or decrease) of the virtual image brightness by introducing a sensitivity coefficient and flexibly adjusting the control parameters (first control parameter, second control parameter), so that the brightness change is both rapid and in line with the user's visual preference, reducing visual discomfort and fatigue. By cyclically executing the brightness adjustment steps, continuous dynamic adjustment of the virtual image brightness is achieved, ensuring that a good visual experience can be provided under different lighting conditions.

[0061] Figure 4 FIG. 2 shows a schematic diagram of a head-up display 200 according to an embodiment of the present invention. Figure 4 As shown, the head-up display 200 includes a backlight module 210, an illumination sensor 220 and a control module 230, wherein the backlight module 210 and the illumination sensor 220 are respectively coupled to the control module 230. The illumination sensor 220 is configured to measure the ambient light illumination. The control module 230 is configured to determine the effective ambient light illumination at the current moment based on the ambient light illumination measured by the illumination sensor 220. The control module 230 is also configured to determine the target virtual image brightness at the current moment according to the effective ambient light illumination and the first relationship, and then determine the actual virtual image brightness at the current moment according to the target virtual image brightness, the actual virtual image brightness at the previous moment and the sensitivity coefficient. The control module 230 is also configured to control the backlight module 210 according to the actual virtual image brightness at the current moment.

[0062] According to an embodiment of the present invention, the control module 230 may be configured to collect the ambient light illumination of the target area through the light illumination sensor at the current moment, and use the ambient light illumination as the effective ambient light illumination at the current moment. The target area may be, for example, the virtual image background area of ​​the head-up display.

[0063] According to another embodiment of the present invention, the control module 230 may be configured to obtain the ambient light illumination at preset time intervals through the light illumination sensor 220. The control module 230 is also configured to be provided with an ambient light illumination history data queue, and whenever the light illumination sensor 220 obtains the ambient light illumination once, the latest ambient light illumination is inserted into the ambient light illumination history data queue, and the oldest ambient light illumination in the ambient light illumination history data queue is deleted. The control module 230 is also configured to extract multiple ambient light illuminations from the ambient light illumination history data queue, filter these ambient light illuminations, and use the result of the filtering process as the effective ambient light illumination at the current moment.

[0064] According to an embodiment of the present invention, the control module 230 can also be configured to compare the actual virtual image brightness at the last moment with the target virtual image brightness. When the target virtual image brightness is less than the actual virtual image brightness at the last moment, the decrease rate of the target virtual image brightness compared to the actual virtual image brightness at the last moment is compared with the first threshold value, wherein if the decrease rate is less than or equal to the first threshold value, the actual virtual image brightness at the last moment is used as the actual virtual image brightness at the current moment, and if the decrease rate is greater than the first threshold value, the actual virtual image brightness at the current moment is determined based on the sensitivity coefficient and the actual virtual image brightness at the last moment, and the actual virtual image brightness at the current moment is less than the actual virtual image brightness at the last moment. When the target virtual image brightness is not less than the actual virtual image brightness at the last moment, the growth rate of the target virtual image brightness compared to the actual virtual image brightness at the last moment is compared with the second threshold value, and if the growth rate is less than or equal to the second threshold value, the actual virtual image brightness at the last moment is used as the actual virtual image brightness at the current moment, and if the growth rate is greater than the second threshold value, the actual virtual image brightness at the current moment is determined based on the sensitivity coefficient and the actual virtual image brightness at the last moment, and the actual virtual image brightness at the current moment is greater than the actual virtual image brightness at the last moment.

[0065] According to an embodiment of the present invention, the control module 230 may also be configured to output a brightness control signal according to the actual virtual image brightness at the current moment and the second relationship, and control the head-up display 200 to adjust the brightness.

[0066] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for adjusting brightness of a head-up display, comprising: S110: Obtaining the effective ambient light illumination at the current moment; S120: determining the target virtual image brightness at the current moment according to the effective ambient light illumination and a first relationship, wherein the first relationship is a corresponding relationship between the effective ambient light illumination and the target virtual image brightness; S130: determining the actual virtual image brightness at the current moment according to the target virtual image brightness, the actual virtual image brightness at the previous moment, and a sensitivity coefficient, wherein the sensitivity coefficient is related to the perception ability of the human eye, and the sensitivity coefficient is characterized by a minimum change rate or a minimum change amount of the virtual image brightness change of the head-up display that can be perceived by the human eye at the current brightness; S140: Controlling the head-up display to adjust brightness according to the actual virtual image brightness at the current moment.

2. The brightness adjustment method according to claim 1, wherein: Step S110 includes: obtaining the ambient light illumination based on the light illumination sensor, and taking the ambient light illumination as the effective ambient light illumination at the current moment.

3. The brightness adjustment method according to claim 1, wherein: Step S110 includes: Based on the light sensor, the ambient light intensity is obtained at preset time intervals, and a historical data queue of the ambient light intensity is established; Extract multiple ambient light illuminations from the ambient light illumination history data queue, perform filtering processing on the multiple ambient light illuminations, and use the filtering processing result as the effective ambient light illumination at the current moment.

4. The brightness adjustment method according to claim 3, wherein: The filtering process is mean filtering or median filtering.

5. The brightness adjustment method according to claim 1, wherein: The first relationship is a mapping table of the effective ambient light illumination and the target virtual image brightness; or, the first relationship is a correlation function of the effective ambient light illumination and the target virtual image brightness, and the correlation function is: ； Among them, I is the effective ambient light illumination, B is the target virtual image brightness, and a and b are optimization parameters.

6. The brightness adjustment method according to claim 1, wherein: Step S130 includes: Comparing the actual virtual image brightness at the previous moment with the target virtual image brightness; If the target virtual image brightness is less than the actual virtual image brightness at the previous moment, compare the reduction rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a first threshold, If the reduction rate is less than or equal to the first threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the reduction rate is greater than a first threshold, determining the actual virtual image brightness at the current moment based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, the actual virtual image brightness at the current moment being less than the actual virtual image brightness at the previous moment; If the target virtual image brightness is not less than the actual virtual image brightness at the previous moment, compare the growth rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a second threshold, If the growth rate is less than or equal to the second threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the growth rate is greater than a second threshold, the actual virtual image brightness at the current moment is determined based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, and the actual virtual image brightness at the current moment is greater than the actual virtual image brightness at the previous moment.

7. The brightness adjustment method according to claim 6, wherein: The first threshold is , where p is the first control parameter, is the sensitivity coefficient, which is characterized by a minimum change rate of the brightness change of the virtual image of the head-up display that can be perceived by human eyes at the current brightness.

8. The brightness adjustment method according to claim 7, wherein: The first control parameter p=1.

9. The brightness adjustment method according to claim 7, wherein: When the reduction rate is greater than the first threshold, the actual virtual image brightness at the current moment is determined according to the following formula: , ,in, is the actual virtual image brightness at the previous moment, is the brightness of the target virtual image.

10. The brightness adjustment method according to claim 6, wherein: The second threshold is , where q is the second control parameter and σ is the sensitivity coefficient.

11. The brightness adjustment method according to claim 10, wherein: The second control parameter q∈[1,5].

12. The brightness adjustment method according to claim 9, wherein: When the growth rate is greater than the second threshold, the actual virtual image brightness at the current moment is determined according to the following formula: , ,in, is the actual virtual image brightness at the previous moment, is the brightness of the target virtual image.

13. The brightness adjustment method according to claim 1, wherein: Step S140 includes: outputting a brightness control signal according to the actual virtual image brightness at the current moment and a second relationship, thereby controlling the head-up display to adjust the brightness, wherein the second relationship is the corresponding relationship between the actual virtual image brightness at the current moment and the brightness control signal, and the brightness control signal is a pulse width modulation signal.

14. The brightness adjustment method according to claim 1, wherein: Also includes: Steps S110 - S140 are cyclically executed at preset time intervals.

15. A head-up display comprising: Backlight module; a light sensor configured to measure ambient light levels; and A control module, coupled to the backlight module and the light sensor, respectively, the control module being configured to: determine the effective ambient light illumination at the current moment based on the ambient light illumination measured by the light sensor, determine the target virtual image brightness at the current moment according to the effective ambient light illumination and the first relationship, further determine the actual virtual image brightness at the current moment according to the target virtual image brightness, the actual virtual image brightness at the previous moment and the sensitivity coefficient, and control the backlight module according to the actual virtual image brightness at the current moment; Among them, the first relationship is the corresponding relationship between the effective ambient light illumination and the target virtual image brightness, the sensitivity coefficient is related to the perception ability of the human eye, and the sensitivity coefficient is characterized by the minimum change rate or minimum change amount of the virtual image brightness change of the head-up display that can be perceived by the human eye at the current brightness.

16. The head-up display according to claim 15, wherein: The control module is configured to obtain the ambient light illumination based on the light illumination sensor, and use the ambient light illumination as the effective ambient light illumination at the current moment.

17. The head-up display according to claim 15, wherein: The control module is configured as follows: Based on the light sensor, the ambient light intensity is obtained at preset time intervals, and a historical data queue of the ambient light intensity is established; Extract multiple ambient light illuminations from the ambient light illumination history data queue, perform filtering processing on the multiple ambient light illuminations, and use the filtering processing result as the ambient light illumination at the current moment.

18. The head-up display according to claim 15, wherein: The control module is configured as follows: Comparing the actual virtual image brightness at the previous moment with the target virtual image brightness; If the target virtual image brightness is less than the actual virtual image brightness at the previous moment, compare the reduction rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a first threshold, If the reduction rate is less than or equal to the first threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the reduction rate is greater than a first threshold, determining the actual virtual image brightness at the current moment based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, the actual virtual image brightness at the current moment being less than the actual virtual image brightness at the previous moment; If the target virtual image brightness is not less than the actual virtual image brightness at the previous moment, compare the growth rate of the target virtual image brightness compared to the actual virtual image brightness at the previous moment with a second threshold, If the growth rate is less than or equal to the second threshold, the actual virtual image brightness at the previous moment is used as the actual virtual image brightness at the current moment. If the growth rate is greater than a second threshold, the actual virtual image brightness at the current moment is determined based on the sensitivity coefficient and the actual virtual image brightness at the previous moment, and the actual virtual image brightness at the current moment is greater than the actual virtual image brightness at the previous moment.

19. The head-up display according to claim 15, wherein: The control module is configured to output a brightness control signal according to the actual virtual image brightness at the current moment and a second relationship, wherein the second relationship is a corresponding relationship between the actual virtual image brightness at the current moment and the brightness control signal.

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