Dodging sheet, backlight module, vehicle and design method

Abstract

The invention relates to a dodging sheet which is suitable for being used in a backlight module of a head-up display, scattering particles are dispersed in the dodging sheet, and the concentration of the scattering particles in the center area of the dodging sheet is smaller than that of the scattering particles in the edge area of the dodging sheet. The invention further provides a backlight module, a vehicle and a design method. The dodging sheet and the backlight module provided by the invention are suitable for a global dimming head-up display, and the visibility of a background frame of a display area of the head-up display can be reduced while the display effect of the head-up display is ensured. According to the dodging sheet and the backlight module provided by the invention, the energy consumption and the temperature rise of the head-up display can be reduced, and the possibility that the temperature of the backlight module of the head-up display is too high under the scene of backward sunlight can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of head-up displays, and in particular to a light-homogenizing sheet, a backlight module, a vehicle, and a design method. Background Art

[0002] A heads-up display (HUD) is an optical display device that projects critical information directly in front of the user's field of view. Its core function is to allow users to simultaneously access device data and external environmental information without lowering their heads, significantly improving operational efficiency and safety. Technically, a HUD uses optical reflection to project crucial data, such as speed, navigation instructions, and device status parameters, in the form of clear images or text onto a transparent display or windshield in front of the user. This design cleverly solves the problem of traditional display devices requiring users to frequently shift their gaze.

[0003] Some vehicles are equipped with a head-up display, which reflects the light emitted from the LCD to the driver's sight through two sets of mirrors, allowing the driver to view information such as vehicle speed and gear position at a certain position above the vehicle's hood. This avoids the driver's eyes from moving back and forth between the outside of the vehicle and the dashboard, greatly reducing the time the eyes are away from the road, which helps to improve driving safety.

[0004] The backlight control mode of the existing head-up display adopts global dimming control, and the backlight brightness of the head-up display is uniformly adjusted. The existing head-up display has the following technical problems: When a head-up display is in operation, the backlight is usually bright. When displaying a dark image, the dark state effect is usually achieved by reducing the transmittance of the liquid crystal layer. However, due to light leakage in the liquid crystal layer, the head-up display suffers from low image contrast, high energy consumption, and high temperature rise of the liquid crystal layer. At night, if the HUD backlight is set too dim, the user will have difficulty seeing the information displayed on the HUD. If the HUD backlight is set too bright, the user will see a bluish background, forming a noticeable background frame in the HUD display area, which will degrade the HUD experience. In some vehicle usage scenarios, sunlight will flow back into the backlight module of the head-up display, causing the temperature of the head-up display backlight module to be too high. Summary of the Invention

[0005] The object of the present invention is to provide a light diffuser, a backlight module, a vehicle and a design method to alleviate or eliminate at least one of the above-mentioned technical problems.

[0006] The light homogenizer described in the present invention is suitable for use in a backlight module of a head-up display. Scattering particles are dispersed in the light homogenizer, and the concentration of the scattering particles in the central area of ​​the light homogenizer is less than the concentration of the scattering particles in the edge area of ​​the light homogenizer.

[0007] Optionally, the concentration of the scattering particles gradually decreases along the direction from the edge area to the central area.

[0008] Optionally, the light homogenizing sheet includes a substrate, and the scattering particles are doped in the substrate.

[0009] Optionally, the light homogenizing sheet includes a substrate, and the scattering particles are coated on the substrate.

[0010] Optionally, the substrate is a PET substrate.

[0011] Optionally, the scattering particles are silica particles.

[0012] Optionally, the light-distributing sheet is a square sheet.

[0013] The present invention also provides a backlight module suitable for use in a head-up display. The backlight module includes a light board and any one of the above-mentioned light homogenizers, wherein the light homogenizer is located on the light-emitting side of the light board.

[0014] Optionally, the light board includes a PCB circuit board and a plurality of LED lamp beads, and the plurality of LED lamp beads are evenly arranged on the PCB circuit board.

[0015] Optionally, the backlight module is a global dimming backlight module.

[0016] The present invention also provides a vehicle, comprising any one of the backlight modules described above.

[0017] The present invention further proposes a design method for designing any of the above-mentioned light diffusers, comprising the following steps: A head-up display (HUD) equipped with a local dimming backlight module is installed on a vehicle. The HUD backlight module is adjusted to find a target dimming solution that meets preset requirements. A backlight brightness distribution requirement for the HUD is determined based on the target dimming solution. The preset requirements include: the brightness of a central area of ​​the HUD backlight module is greater than the brightness of an edge area of ​​the HUD backlight module; the image display effect of the HUD meets the preset display effect requirements during daytime operation; and the background frame visibility of the HUD meets the preset visibility requirements during nighttime operation. The design scheme of the light homogenizer is determined by taking the concentration distribution of scattering particles in the light homogenizer as the design variable and the global dimming backlight module equipped with the light homogenizer to meet the backlight brightness distribution requirement as the design goal.

[0018] The present invention improves the light homogenizer by providing scattering particles in the light homogenizer, enabling the light homogenizer to perform a light homogenization function. The concentration of scattering particles in the center area of ​​the light homogenizer is lower than that in the edge areas of the light homogenizer. When the brightness of the light source is consistent across the entire backlight area, the brightness of the light output from the center area of ​​the light homogenizer is brighter than that from the edge areas. In daytime environments, due to the brighter light outside the vehicle, changes in the brightness of the head-up display area are usually not noticeable. In nighttime environments, the center area of ​​the head-up display area has a higher brightness, which can ensure the display effect of the head-up display. In nighttime environments, the edge areas of the head-up display area are darker, which can reduce the visibility of the background frame of the head-up display area, even to the point where the human eye cannot see the background frame of the head-up display area. By dimming the light homogenizer, the brightness of different backlight areas can be blurred or brightened. In some scenarios, it is not necessary to reduce the transmittance of the liquid crystal layer to achieve a dark state effect, which helps to reduce the temperature rise of the liquid crystal layer, reduce the energy consumption of the head-up display, and ensure the image display effect of the head-up display. The above-mentioned light diffuser is distributed with scattering particles, which can block part of the backflowing sunlight, reduce the impact of the backlight module on the backlight module, and help reduce the possibility of the backlight module of the head-up display being overheated in the scenario of backflowing sunlight.

[0019] The diffuser and backlight module proposed in this invention are suitable for use in heads-up displays (HUDs) with global dimming. While maintaining the HUD's display quality, they can also reduce the visibility of the background frame within the HUD's display area. This invention helps reduce HUD energy consumption and temperature rise, and helps mitigate the possibility of backlight module overheating in HUDs exposed to sunlight backflow. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the light-dispersing sheet described in some embodiments; Figure 2 is an exploded view of the backlight module described in some embodiments; Figure 3 is a flow chart of the design method described in some embodiments; Figure 4 A brightness distribution curve of a light-diffusing sheet determined by the design method described in some embodiments; Figure 5 A schematic diagram of the brightness distribution of the light-diffuser determined by the design method described in some embodiments; Figure 6Schematic diagram of the four states of the head-up display area.

[0021] In the figure, 1 is the light board, 2 is the lens board, 3 is the base, 4 is the Fresnel lens, 5 is the one-way diffusion film, 6 is the H-adaptive lens, 7 is the uniform light sheet, 8 is the V-adaptive lens, 9 is the upper cover, 10 is the background frame, 20 is the image, 701 is the substrate, 702 is the scattering particles, 703 is the center area, and 704 is the edge area. DETAILED DESCRIPTION

[0022] The following describes the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art will readily appreciate the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the various details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are intended only to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0023] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. The illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0024] like Figure 1 A light homogenizer 7 is shown, which is suitable for use in a backlight module of a head-up display. Scattering particles 702 are dispersed in the light homogenizer 7, and the concentration of the scattering particles 702 in the central area 703 of the light homogenizer 7 is less than the concentration of the scattering particles 702 in the edge area 704 of the light homogenizer 7.

[0025] By adopting the above-mentioned technical solution, scattering particles 702 are set in the light homogenizing sheet 7, so that the light homogenizing sheet 7 can play the role of light homogenization. The concentration of the scattering particles 702 in the central area 703 of the light homogenizing sheet 7 is less than the concentration of the scattering particles 702 in the edge area 704 of the light homogenizing sheet 7. When the brightness of the light source in the entire backlight area is consistent, the brightness of the light output by the central area 703 of the light homogenizing sheet 7 is brighter than the brightness of the light output by the edge area 704. In a daytime environment, due to the bright light outside the car, the change in the brightness of the head-up display area is usually not visible. In a night environment, the central area 703 of the head-up display area has a higher brightness, which can ensure the display effect of the head-up display. In a night environment, the edge area of ​​the head-up display area is darker, which can reduce the visibility of the background frame of the head-up display area, and even achieve the effect that the human eye cannot see the background frame of the head-up display area.

[0026] By dimming the light through the light homogenizer 7, the brightness of different areas of the backlight can be blurred or brightened. In some scenarios, there is no need to reduce the transmittance of the liquid crystal layer to achieve a dark state effect, which helps to reduce the temperature rise of the liquid crystal layer, reduce the energy consumption of the head-up display, and ensure the image display effect of the head-up display.

[0027] The light diffuser 7 is provided with scattering particles 702 , which can block some of the backflowing sunlight, reduce the impact of the backlight module on the backlight module, and help reduce the possibility of the backlight module of the head-up display being overheated in the scenario of backflowing sunlight.

[0028] In some embodiments, the concentration of scattering particles 702 gradually decreases from edge region 704 to center region 703. This gradient in the concentration of scattering particles 702 can reduce the perception by the human eye of higher brightness in the center of the head-up display area and lower brightness in the edge regions, thereby reducing the visual impact on the user. With this gradient brightness distribution scheme, during daytime, the overall backlight brightness is high. For the entire display area of ​​the head-up display and the displayed image, the difference in display quality between the edge regions and the center region 703 is minimal, making the visual impact less noticeable to the user. At night, the overall backlight brightness is lower, but the displayed image is primarily concentrated in the center region 703, ensuring a good image display. The lower brightness in the edge regions blends in with the exterior background, reducing the visibility of the background frame.

[0029] In some embodiments, the light homogenizer 7 includes a substrate 701, and scattering particles 702 are doped into the substrate 701. Doping the scattering particles 702 into the light homogenizer 7 has the advantages of stable performance, low cost, and easy thickness control.

[0030] In practice, a gradient doping process can be used to gradually reduce the concentration of scattering particles 702 from the edge region 704 to the center region 703. This gradient doping process is a highly effective solution widely adopted in the industry. By precisely controlling the spatial distribution of the scattering particles 702, the gradient doping process can enhance the light scattering capability of the edge region 704 of the light homogenizer 7 and reduce the light scattering capability of the center region 703 of the light homogenizer 7.

[0031] More specifically, the gradient doping process includes the following steps: first, preparing the raw materials for the substrate 701 and the raw materials for the scattering particles 702, and placing the raw materials for the substrate 701 and the scattering particles 702 in different feeding devices. During the molding process of the substrate 701, the amount of scattering particles 702 added is adjusted through a feeding control system. When processing begins at the edge region 704 of the light diffuser 7, the feeding rate of the scattering particles 702 is increased so that more scattering particles 702 are evenly mixed into the raw material of the substrate. As the processing progresses toward the center region 703, the feeding rate of the scattering particles 702 is gradually reduced so that the amount of scattering particles 702 mixed into the substrate 701 continues to decrease, thereby forming a distribution with a gradient decrease in the concentration of the scattering particles 702 from the edge region 704 to the center region 703.

[0032] In some embodiments, the light homogenizer 7 includes a substrate 701, and scattering particles 702 are coated on the substrate 701. The scattering particles 702 are disposed on the light homogenizer 7 by doping, which is easy to implement.

[0033] In practice, a gradient coating process can be employed to achieve a gradual decrease in the concentration of scattering particles 702 from the edge region 704 to the center region 703. This process is an efficient and flexible solution, particularly suitable for thin substrates or where localized optical performance adjustments are required. By precisely controlling the flow rate and coating path of the coating liquid, the gradient coating process creates a continuously varying particle concentration gradient on the substrate surface, thereby precisely regulating the light scattering ability of different regions of the light homogenizer 7.

[0034] More specifically, the gradient coating process includes the following steps: First, a substrate 701 is secured on a mobile platform. A coating liquid containing scattering particles 702 is prepared. The coating liquid is typically a mixture of scattering particles 702, a solvent, and a binder. The coating liquid is then injected into a coating head with an adjustable flow rate. After the coating equipment is activated, the coating head begins coating at the edge of the substrate 701. A flow control system increases the flow rate of the coating liquid, ensuring that a higher concentration of scattering particles 702 uniformly covers the substrate surface in the edge region 704. As the coating head moves along a predetermined path toward the center region 703, the system gradually decreases the flow rate of the coating liquid, while simultaneously adjusting the speed of the mobile platform to ensure that the coating density of the scattering particles 702 decreases linearly with distance from the edge region 704. After coating, the scattering particles 702 are firmly attached to the substrate 701 through a drying or curing process, ultimately forming a light-distributing sheet 7 in which the concentration of scattering particles 702 gradually decreases from the edge region 704 to the center region 703.

[0035] In a specific implementation, the substrate 701 may be an optical polymer, such as a PMMA substrate, a PET substrate, or a PC substrate. The scattering particles 702 may be inorganic particles, such as silicon dioxide particles, titanium dioxide particles, or zinc oxide particles.

[0036] As a preferred example, the substrate 701 is a PET substrate, and the scattering particles 702 are silicon dioxide particles doped in the PET substrate. This light-distributing sheet 7 can meet the requirements of a head-up display and has the characteristics of low cost.

[0037] As a preferred example, the light diffuser 7 is a square sheet-shaped piece, which is suitable for use in the backlight module of a head-up display. In a specific implementation, a square sheet-shaped substrate 701 can be used to manufacture the square sheet-shaped light diffuser 7. Obviously, mounting points can be set on the outer periphery of the square sheet-shaped light diffuser 7, such as mounting ears extending outward from the light diffuser 7. Typically, mounting holes are provided in the mounting ears, and fasteners that cooperate with the mounting holes are used to securely install the light diffuser 7 in the backlight module.

[0038] As a preferred example, the light homogenizer 7 is suitable for use in a backlight module of a head-up display, the backlight module is a global dimming backlight module, scattering particles 702 are dispersed in the light homogenizer 7, the concentration of the scattering particles 702 in the central area 703 of the light homogenizer 7 is less than the concentration of the scattering particles 702 in the edge area 704 of the light homogenizer 7, the light homogenizer 7 includes a substrate 701, the scattering particles 702 are doped in the substrate 701 or coated on the substrate 701, the substrate 701 is a PET substrate, and the scattering particles 702 are silica particles.

[0039] As a preferred example, the light diffuser 7 is divided into 12 x 12 zones, with five brightness steps from the outer circle to the inner circle, with the outermost circle having 46 zones and the innermost circle having 16 zones. This partitioning scheme is primarily designed to address the difficulty of the manufacturing process: the more zones, the more difficult the process is to control. From the edge area 704 of the light diffuser 7 to the center area 703 of the light diffuser 7, the proportion of the brightness value to the maximum brightness is 96%, 97.5%, 98.8%, 99.7%, and 100%, respectively, with the brightness value in the center area 703 being the highest. This brightness distribution scheme has a relatively gentle gradient, which meets the observation requirements of the human eye. That is, there is no obvious brightness change during the day, and the background frame is not obvious at night. During the day, the overall brightness is high. For the entire display area and image, the display effect of the edge area is not much different from that of the center area, and the visual impact to the user is not obvious. At night, the overall brightness of the display area is lower, but the image is mainly concentrated in the center of the display area. The brightness of the edge area is low, and the background frame is not obvious, which weakens the human eye's perception.

[0040] The present invention also proposes a backlight module suitable for use in a head-up display. The backlight module includes a light board 1 and a light homogenizer 7 as described above. The light homogenizer 7 is located on the light-emitting side of the light board 1 .

[0041] The main improvement of the above-mentioned backlight module lies in the light homogenizer 7. The concentration of the scattering particles 702 in the central area 703 of the light homogenizer 7 is less than the concentration of the scattering particles 702 in the edge area 704 of the light homogenizer 7. When the brightness of the light source in the entire area of ​​the backlight module is consistent, the brightness of the light output by the central area 703 of the light homogenizer 7 is brighter than the brightness of the light output by the edge area 704. In a daytime environment, since the light outside the car is brighter, the change in the brightness of the head-up display area is usually not visible. In a night environment, the central area 703 of the head-up display area has a higher brightness, which can ensure the display effect of the head-up display. In a night environment, the edge area of ​​the head-up display area is darker, which can reduce the visibility of the background frame of the head-up display area, and even achieve the effect that the human eye cannot see the background frame of the head-up display area.

[0042] By dimming the backlight module's homogenizer 7, the brightness of different backlight areas can be blurred or brightened. In some scenarios, there is no need to reduce the transmittance of the liquid crystal layer to achieve a dark state effect, which helps to reduce the temperature rise of the liquid crystal layer, reduce the energy consumption of the head-up display, and ensure the image display effect of the head-up display.

[0043] The backlight module's light homogenizer 7 is distributed with scattering particles 702. The light homogenizer 7 can block some of the backflowing sunlight, reduce the impact of the backlight module on the backlight module, and help reduce the possibility of the head-up display's backlight module temperature being too high in the scenario of backflowing sunlight.

[0044] In some embodiments, the light board 1 includes a PCB and multiple LEDs, which are evenly arranged on the PCB. This even arrangement of the LEDs allows for uniform backlight output, making the brightness of the light output from the center region 703 of the light diffuser 7 brighter than that from the edge regions.

[0045] As a preferred example, the above-mentioned backlight module is a global dimming backlight module. As the core light source engine of the head-up display, the global dimming backlight module achieves ambient light adaptation through global synchronous brightness adjustment. The light diffuser 7 proposed in this application is particularly suitable for the global dimming backlight module. The global dimming backlight module using the light diffuser 7 proposed in this application can meet the display requirements and background frame visibility requirements of the head-up display and has the characteristics of low cost.

[0046] During specific implementation, other structures and components of the backlight module may be implemented with reference to the global dimming backlight module in the prior art.

[0047] Global dimming is the most widely used backlight brightness control technology. It simultaneously and uniformly adjusts the brightness of all light-emitting areas across the entire backlight unit. Regardless of the screen content (full black, full white, or complex images), the brightness of the light emitted by the entire backlight unit remains completely consistent. A typical global dimming backlight unit typically consists of a light source, a light guide plate, an optical film assembly, and a reflector.

[0048] Global dimming backlight modules can use PWM dimming. This method adjusts the average brightness perceived by the human eye by switching the LED current on and off at a very high frequency, controlling the proportion of time the LED is on within a cycle. A high duty cycle results in high brightness, while a low duty cycle results in low brightness. This method maintains the LED at its optimal operating point.

[0049] Global dimming backlight modules can also use DC dimming or analog dimming to directly adjust the current flowing through the LEDs. Higher currents result in higher brightness, while lower currents result in lower brightness. DC dimming and analog dimming are relatively simple to implement.

[0050] As a specific example, Figure 2 As shown, the backlight module also includes a lens plate 2, a base 3, a Fresnel lens 4, a one-way diffusion film 5, an H-matching lens 6, a V-matching lens 8, and a top cover 9. These components are arranged in order from bottom to top, namely, the light plate 1, the lens plate 2, the Fresnel lens 4, the one-way diffusion film 5, the H-matching lens 6, the light diffuser 7, and the V-matching lens 8. They are fixed together by the base 3 and the top cover 9 to form the backlight module. This ensures that the relative positions of the components remain stable during operation to prevent vibration or displacement from affecting the light output effect.

[0051] The lens plate 2 includes multiple lens sections, each corresponding to a plurality of LED lamp beads. The lens plate 2 is typically made of PC material and primarily functions to collect light emitted by the LED lamp beads. The lens section is a convex spherical shell. Since the light emitted by the LED lamp beads is dispersed 180 degrees, the light is constricted by the lens section and focused toward the top of the lens section.

[0052] The base 3 is usually made of PC material. The main function of the base 3 is to provide a mounting point for the light board 1, lens board 2, Fresnel lens 4, one-way diffusion film 5, H-adaptive lens 6, light homogenizer 7 and V-adaptive lens 8.

[0053] The Fresnel lens 4 is usually made of PET material, and its main function is to collect light for the second time.

[0054] The one-way diffusion film 5 is usually made of PET material. The main function of the one-way diffusion film 5 is to increase the diffusion angle of light and enlarge the light spot.

[0055] The H-adaptive lens 6 is usually made of PET material. The main function of the H-adaptive lens 6 is to deflect the light in the horizontal direction into the eye box.

[0056] The main function of the light homogenizing sheet 7 is to perform light homogenization.

[0057] The V-adaptive lens 8 is usually made of PET material. The main function of the V-adaptive lens 8 is to deflect vertical light into the eye box.

[0058] The upper cover 9 is usually made of PC material. The main function of the upper cover 9 is to fix the light board 1, lens board 2, Fresnel lens 4, one-way diffusion film 5, H-adaptive lens 6, light homogenizer 7 and V-adaptive lens 8 on the base 3.

[0059] As a preferred example, the backlight module is a global dimming backlight module, which includes a light homogenizer 7, a lens plate 2, a base 3, a Fresnel lens 4, a one-way diffusion film 5, an H-adaptive lens 6, a V-adaptive lens 8 and an upper cover 9. The light board 1, the lens plate 2, the Fresnel lens 4, the one-way diffusion film 5, the H-adaptive lens 6, the light homogenizer 7, and the V-adaptive lens 8 are arranged in sequence from bottom to top and are fixed together through the base 3 and the upper cover 9. Scattering particles 702 are dispersed in the light homogenizer 7. The concentration of the scattering particles 702 in the central area 703 of the light homogenizer 7 is less than the concentration of the scattering particles 702 in the edge area 704 of the light homogenizer 7. The light homogenizer 7 includes a substrate 701. The scattering particles 702 are doped in the substrate 701 or coated on the substrate 701. The substrate 701 is a PET substrate, and the scattering particles 702 are silica particles.

[0060] The present invention also provides a vehicle, comprising any one of the backlight modules described above, wherein the backlight module is arranged in a head-up display of the vehicle.

[0061] As a specific example, the head-up display of the vehicle includes a backlight module, which is a global dimming backlight module. The backlight module includes a light homogenizer 7, a lens plate 2, a base 3, a Fresnel lens 4, a one-way diffusion film 5, an H-adaptive lens 6, a V-adaptive lens 8 and an upper cover 9. The light board 1, the lens plate 2, the Fresnel lens 4, the one-way diffusion film 5, the H-adaptive lens 6, the light homogenizer 7, and the V-adaptive lens 8 are arranged in sequence from bottom to top and are fixed together through the base 3 and the upper cover 9. Scattering particles 702 are dispersed in the light homogenizer 7. The concentration of the scattering particles 702 in the central area 703 of the light homogenizer 7 is less than the concentration of the scattering particles 702 in the edge area 704 of the light homogenizer 7. The light homogenizer 7 includes a substrate 701. The scattering particles 702 are doped in the substrate 701 or coated on the substrate 701. The substrate 701 is a PET substrate, and the scattering particles 702 are silica particles.

[0062] The vehicle may be, but is not limited to, a pure electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), a new energy vehicle (NEV), a fuel vehicle, etc.

[0063] like Figure 3 As shown, the present invention also proposes a design method, which is used to design any of the above-mentioned light diffusers 7, and the design method includes the following steps: S100: Installing a head-up display (HUD) equipped with a local dimming backlight module on a vehicle, adjusting the local dimming backlight module to find a target dimming solution that meets preset requirements, and determining a backlight brightness distribution requirement for the HUD based on the target dimming solution; the preset requirements include: the brightness of a central area 703 of the local dimming backlight module is greater than the brightness of an edge area of ​​the local dimming backlight module; under daytime operating conditions, the image display effect of the HUD meets the preset display effect requirements; and under nighttime operating conditions, the background frame visibility of the HUD meets the preset visibility requirements; S200 : Determine a design solution for the light homogenizer 7 by taking the concentration distribution of the scattering particles 702 in the light homogenizer 7 as a design variable and the global dimming backlight module equipped with the light homogenizer 7 meeting the backlight brightness distribution requirement as a design goal.

[0064] By adopting the above technical solution, the regional dimming backlight module is first used for testing to determine the target dimming solution and backlight brightness distribution requirements, providing a more accurate target for designing the light homogenizer 7, and being able to design a light homogenizer 7 that meets the requirements more quickly.

[0065] As a specific example, the preset display effect requirements include a brightness threshold, a contrast threshold and a clarity threshold. When the brightness of the head-up display image display is not lower than the brightness threshold, the contrast of the head-up display image display is not lower than the contrast threshold, and the clarity of the head-up display image display is not lower than the clarity threshold, it means that the image display effect of the head-up display meets the preset display effect requirements.

[0066] As a specific example, the preset visibility requirement includes a visibility threshold. When the visibility of the background frame of the head-up display is lower than the visibility threshold, it indicates that the visibility of the background frame of the head-up display meets the preset visibility requirement.

[0067] As a specific example, the design method includes the following steps: Step 1: Install a head-up display (HUD) equipped with a local dimming backlight module (DDM) on the vehicle. Simulate the HUD's brightness distribution under daytime and nighttime conditions, using various backgrounds and images. Using zoned lighting control, adjust the brightness of the entire backlight from the edge toward the center, finding an appropriate stepped brightness level that allows for normal image display during the day and eliminates or is unnoticeable to the human eye at night. Based on the brightness-related parameters output by the DDM, calculate the actual brightness value produced by the DDM, and collect and record the actual brightness value distribution of the stepped brightness level.

[0068] Step 2: Design a DOE experimental plan, and make light homogenizers 7 with different silicon dioxide particle concentration distributions according to the experimental plan. Find a light homogenizer 7 with the same level as the actual brightness value distribution, and record the silicon dioxide particle concentration distribution plan.

[0069] Step 3: Install the light homogenizer 7 manufactured according to the silica particle concentration distribution scheme on the vehicle, and perform regression experiments to verify the effect of the light homogenizer 7.

[0070] Step 4: Repeat steps 1, 2, and 3 to determine the average of the silica particle concentration distribution plans as the production plan.

[0071] As a specific example, the brightness distribution of the entire light homogenizer 7 is as follows: Figure 5 As shown, the overall distribution is dark in the edge area and bright in the middle area. Considering that the partitions of the regional dimming backlight module are generally more than 80 zones, the partitions designed for the light homogenizer 7 in this example are 12*12, and there are 5 brightness steps from the outer circle to the inner circle, with the outermost circle having 46 partitions and the innermost circle having 16 partitions. The partition scheme here is mainly considered to consider the difficulty of the manufacturing process. The more partitions, the more difficult it is to control the process. The brightness distribution curve of the determined light homogenizer 7 is shown in the figure below. Figure 4 As shown, from the edge area of ​​the light-homogenizing sheet 7 to the middle area of ​​the light-homogenizing sheet 7, the proportion of the brightness value to the maximum brightness is 96%, 97.5%, 98.8%, 99.7% and 100% respectively, and the brightness value of the middle area is the highest brightness. The gradient of this brightness distribution scheme is relatively gentle, which meets the observation requirements of the human eye, that is, no obvious brightness changes can be seen during the day, and the background frame is not obvious at night. During the day, the overall brightness is high. For the entire display area and image, the display effect of the edge area and the display effect of the middle area are not much different, and the visual impact on the user is not obvious. At night, the overall brightness of the display area is low, but the image is mainly concentrated in the middle position of the display area. The brightness of the edge area is low and the background frame is not obvious, which weakens the perception of the human eye.

[0072] In specific implementation, the light-homogenizing sheet 7 can be composed of a PET substrate and silica particles doped inside the PET substrate. By fitting the overall brightness, the final doping distribution scheme of the silica particles is determined. The doping distribution of the silica particles is consistent with the brightness distribution. The edge area is more doped and the middle area is less doped. The light-homogenizing sheet 7 produced in this way finally shows the effect of bright middle and dark surroundings.

[0073] like Figure 6 As shown, the display area of ​​the head-up display has the following four states: the first state is as follows: Figure 6 As shown in FIG. A in FIG. , the display area has an image 20 and a severely visible background frame 10; the second state is as follows Figure 6 As shown in FIG. B in FIG, the display area has an image 20 and a medium visible background frame 10; the third state is as shown in FIG. Figure 6 As shown in FIG. C in FIG, the display area has an image 20 and a slightly visible background frame 10; the fourth state is as shown in FIG. Figure 6 As shown in Figure D, the display area has an image 20 and no visible background frame 10. In the prior art, the background frame 10 in the head-up display area can be controlled at the levels of the first and second states, making the background frame 10 clearly visible to the human eye. By using the light diffuser 7 proposed in this application, the background frame 10 in the head-up display area can be controlled at the levels of the third and fourth states, with minimal or no impact on the driver.

[0074] It should be noted that, in the present invention, the image refers to a dynamic or static visual element displayed in the display area of ​​the head-up display to provide information to the driver, such as vehicle speed value, real-time road condition signs and turn arrows.

[0075] The above embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the scope of protection of the present invention. In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. mean that the specific features, structures, materials or characteristics of the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0076] In the description of the present invention, it should be understood that the terms "upper", "lower" and the like indicate directions based on the attached drawings. Figure 2The orientations represented by the coordinate system in are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, an element defined by the sentence "comprises a..." does not exclude the presence of other identical elements in the process, method, article or terminal device comprising the element.

Claims

1. A light-distributing sheet, characterized in that: The light homogenizer is suitable for use in a backlight module of a head-up display. Scattering particles (702) are dispersed in the light homogenizer (7), and the concentration of the scattering particles (702) in the central area (703) of the light homogenizer is less than the concentration of the scattering particles (702) in the edge area (704) of the light homogenizer.

2. The light homogenizing sheet according to claim 1, characterized in that: The concentration of the scattering particles (702) gradually decreases along the direction from the edge region (704) to the central region (703).

3. The light homogenizing sheet according to claim 1, characterized in that: The light homogenizing sheet comprises a substrate (701), and the scattering particles (702) are doped in the substrate (701).

4. The light homogenizing sheet according to claim 1, characterized in that: The light homogenizing sheet comprises a substrate (701), and the scattering particles (702) are coated on the substrate (701).

5. The light homogenizing sheet according to claim 3 or 4, characterized in that: The substrate (701) is a PET substrate.

6. The light homogenizing sheet according to claim 3 or 4, characterized in that: The scattering particles (702) are silicon dioxide particles.

7. The light homogenizing sheet according to claim 1, characterized in that: The light-distributing sheet is a square sheet.

8. A backlight module, characterized in that: The backlight module is suitable for use in a head-up display, and comprises a light board (1) and a light homogenizer according to any one of claims 1 to 7, wherein the light homogenizer is located on the light-emitting side of the light board (1).

9. The backlight module according to claim 8, wherein: The lamp board (1) comprises a PCB circuit board and a plurality of LED lamp beads, wherein the plurality of LED lamp beads are evenly arranged on the PCB circuit board.

10. The backlight module according to claim 8, wherein: The backlight module is a global dimming backlight module.

11. A vehicle, characterized in that: The backlight module comprises the backlight module according to any one of claims 8 to 10.

12. A design method, characterized in that: The design method is used to design a light diffuser according to any one of claims 1 to 7, and the design method comprises the following steps: A head-up display (HUD) equipped with a local dimming backlight module is installed on a vehicle. The HUD backlight module is adjusted to find a target dimming solution that meets preset requirements. A backlight brightness distribution requirement for the HUD is determined based on the target dimming solution. The preset requirements include: the brightness of a central area of ​​the HUD backlight module is greater than the brightness of an edge area of ​​the HUD backlight module; the image display effect of the HUD meets the preset display effect requirements during daytime operation; and the background frame visibility of the HUD meets the preset visibility requirements during nighttime operation. The design scheme of the light homogenizer is determined by taking the concentration distribution of scattering particles in the light homogenizer as the design variable and the global dimming backlight module equipped with the light homogenizer to meet the backlight brightness distribution requirement as the design goal.

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