Diffusion screen, display device, and vehicle

Abstract

A diffusion screen (300), which can be applied to a projection display device, such as a head-up display system. The diffusion screen (300) can reduce reflection of incident light on the surface of the diffusion screen (300) and increase transmission, such that when stray light is incident on the surface of the diffusion screen (300), the stray light reflected into an imaging light path can be reduced, thereby achieving the objective of improving the imaging quality of the display system. The diffusion screen (300) comprises a first surface (301); a first film stack (302) is provided on the first surface (301); and the first film stack (302) is used for reducing the reflectivity of the incident light on the first film stack (302), and comprises multiple layers of first thin films (#1, #2, ..., #N) having different refractive indexes.

Description

Diffusing screen, display device and vehicle

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on October 30, 2023, application number 202311428387.6, and application name “A Diffuser Screen, Display Device and Vehicle”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the fields of display technology and intelligent automobile driving technology, and more particularly, to a diffusion screen, a display device, and a vehicle. Background Art

[0003] Cars have become an indispensable means of transportation in our daily lives. As the number of cars increases, the frequency of traffic accidents is also increasing. To improve driving safety, head-up displays (HUDs), particularly augmented reality head-up displays (AR-HUDs), have become a hot research topic.

[0004] In the HUD system, in order to avoid glare caused by backflow of sunlight and prevent most stray light from entering the human eye, the direction of the vertical line of the diffuser is usually set to be at an angle of about 15° with the direction of the main imaging light. However, the direction of the main imaging light emitted by the picture generation unit (PGU) is usually ≤15°, resulting in energy loss of the imaging light emitted from the diffuser. Currently, the common solution is to add a field lens (such as a cylindrical lens, etc.) to the system and use the field lens to adjust the angle of the light, as shown in Figure 2. However, due to the large size of the field lens and the risk of stray light on the surface, it not only leads to a decrease in the clarity of the displayed image, but also increases the size and glare risk of the HUD system, and further increases the design complexity of the HUD system. Therefore, how to reduce the glare risk of the HUD system without changing the optical path design of the HUD system is a problem that needs to be solved.

[0005] Summary of the Invention

[0006] The present application provides a diffusion screen, a display device, and a vehicle. The diffusion screen provided in the present application can achieve directional matching between projection light and image light, and when used in a display device, can reduce the size of the display device and improve the imaging quality of the display device.

[0007] In a first aspect, embodiments of the present application provide a diffuser screen comprising: a first surface, on which a first film system is disposed, the first film system comprising multiple layers of first thin films with different refractive indices, the first film system being configured to reduce the reflectivity of incident light on the first film system.

[0008] Based on the above solution, the diffuser screen provided by this application can reduce the reflectivity of incident light striking the first film system, allowing more of the incident light to be transmitted through the first film system. It can be understood that when the incident light is image light, the first film system ensures that more of the incident light transmits through the diffuser screen, thereby reducing reflection losses of the image light on the diffuser screen. Furthermore, when the incident light is stray light, the lower reflectivity prevents stray light from reflecting into the imaging optical path and causing deterioration in image quality. Therefore, when the diffuser screen of this application is used in a display system, it can ensure the system's image quality and thus enhance the user experience.

[0009] In combination with the first aspect, in certain implementations of the first aspect, the refractive index of the multilayer first thin film gradually decreases in a direction away from the first surface.

[0010] In combination with the first aspect, in some implementations of the first aspect, the diffusion screen further includes a second surface, the second surface is opposite to the first surface, and the first film system is disposed on the second surface.

[0011] By arranging the same first film system on the first surface and the second surface of the diffusion screen, the anti-reflection performance of the diffusion screen can be further improved. At the same time, arranging the same first film system can also simplify the process flow and reduce costs.

[0012] In combination with the first aspect, in certain implementations of the first aspect, the refractive index of the multilayer first thin film gradually decreases in a direction away from the second surface.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the diffuser screen further includes a second surface, the second surface being opposite to the first surface, a second film system being disposed on the second surface of the diffuser screen, the second film system including a plurality of second thin films having different refractive indices, the second film system being configured to reduce reflectivity of incident light on the second film system.

[0014] The first film system and the second film system are different in at least one of the following:

[0015] The number of layers of the first film system and the second film system, the refractive index of at least one first film in the multilayer first film and the refractive index of at least one second film in the multilayer second film, the thickness of at least one first film in the multilayer first film and the thickness of at least one second film in the multilayer second film.

[0016] By arranging different film systems on the first surface and the second surface of the diffusion screen, the use scenarios of the diffusion screen can be increased, making the design of the diffusion screen more flexible.

[0017] In combination with the first aspect, in certain implementations of the first aspect, the refractive index of the multilayer second film gradually decreases in a direction away from the second surface.

[0018] In combination with the first aspect, in certain implementations of the first aspect, at least one of the first film system and the second film system is an anti-reflection (AR) film.

[0019] In combination with the first aspect, in certain implementations of the first aspect, at least one of the first film system and the second film system includes a microstructure, and the microstructure is used to reduce the reflectivity of the incident light on the film system including the microstructure.

[0020] By further reducing the reflectivity of the first film surface and the second film surface through the microstructure, the imaging quality of the system can be further improved.

[0021] In combination with the first aspect, in certain implementations of the first aspect, the refractive index of the first film system is determined based on the refractive index of the diffuser screen and the target reflectivity of the incident light in the first film system.

[0022] In a second aspect, embodiments of the present application provide a display device. The display device includes a projection module, a first reflective element, a second reflective element, and a diffuser screen as described in the first aspect and any possible implementation of the first aspect. The projection module is configured to project image light onto the second surface of the diffuser screen; the diffuser screen is configured to transmit the image light from the projection module from the first surface to the first reflective element and generate a relay image on the first surface based on the image light from the projection module; the first reflective element is configured to reflect the image light from the diffuser screen to the second reflective element; and the second reflective element is configured to reflect the image light from the first reflective element toward the human eye.

[0023] In combination with the second aspect, in certain implementations of the second aspect, an angle between a normal line of the second surface and the image light incident on the second surface is greater than or equal to 15°.

[0024] Based on the above solution, the possibility of sunlight entering the imaging light path after reflection can be further reduced, thereby reducing the glare of the display system and achieving the purpose of improving user experience.

[0025] In a third aspect, embodiments of the present application provide a vehicle. The vehicle includes the display device and a windshield according to the second aspect and any possible implementation thereof. The second reflective element is configured to reflect image light from the first reflective element toward the windshield, and the windshield is configured to reflect image light from the display device toward a person's eye.

[0026] In a fourth aspect, an embodiment of the present application provides a vehicle-mounted system, which includes the display device according to the second aspect and any possible implementation of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic diagram of an application scenario of a HUD device provided in an embodiment of the present application.

[0028] FIG2 is a schematic diagram of using a cylindrical lens to match the projection light and imaging light directions of a HUD system.

[0029] FIG3 is a schematic structural diagram of a first diffusion screen 300 provided in an embodiment of the present application.

[0030] FIG4 is a schematic structural diagram of a second diffusion screen 400 provided in an embodiment of the present application.

[0031] FIG5 is a schematic structural diagram of a third diffusion screen 500 provided in an embodiment of the present application.

[0032] FIG6 is a schematic structural diagram of a fourth diffusion screen 600 provided in an embodiment of the present application.

[0033] FIG7 is a schematic diagram of a display device 700 provided in an embodiment of the present application.

[0034] FIG8 shows a possible structure of a projection module 701 provided in an embodiment of the present application.

[0035] FIG9 shows a possible structure of a projection module 701 in which the modulation unit 712 is a DMD, provided in an embodiment of the present application.

[0036] FIG10 is a schematic diagram of an optical path 1000 of a display device 700 provided in an embodiment of the present application when applied to a vehicle.

[0037] FIG11 is a circuit diagram of a display device provided in an embodiment of the present application.

[0038] FIG12 is a schematic diagram of a possible functional framework of a vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0040] In order to facilitate understanding of the embodiments of the present application, the following explanations are provided.

[0041] First, the terms "first," "second," and various numbers in the following descriptions or drawings of the embodiments of the present application are merely for convenience of description and are not necessarily used to describe a specific order or sequence, and are not intended to limit the scope of the embodiments of the present application. For example, they may be used to distinguish between different surfaces or different film systems.

[0042] Second, the terms "including" and "having" and any variations thereof in the embodiments of the present application shown below are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or apparatuses.

[0043] Third, in the embodiments of this application, words such as "exemplarily" or "for example" are used to indicate examples, illustrations, or descriptions. An embodiment or design described as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. The use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete manner to facilitate understanding.

[0044] Fourth, in the embodiment of the present application, image light refers to light carrying an image (or image information) and is used to generate an image.

[0045] Fifth, in the drawings of this application, the thickness, size, and shape of various optical components are slightly exaggerated for ease of illustration. Specifically, the shapes of the optical components shown in the drawings are provided by way of example. For example, the shapes of the curved mirrors in this application are not limited to the spherical or aspherical shapes shown in the drawings. Furthermore, the drawings are for illustrative purposes only and are not drawn strictly to scale.

[0046] Sixth, unless otherwise defined, all terms (including technical and scientific terms) used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0047] Seventh, in the description of the embodiments of the present application, the orientation or position relationship indicated by the term "upper" is defined relative to the orientation or position of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. It can change accordingly according to the change in the orientation of the components in the drawings, and therefore cannot be understood as a limitation on the present application.

[0048] Eighth, this application relates to light-trapping structures. Light-trapping structures are an anti-reflection technology that creates a series of tiny grooves or columnar structures on the surface of a material. When light enters a medium with light-trapping structures, the light propagation path is extended, thereby increasing light absorption. This causes the light to reflect and refract multiple times when reflected from the material surface, thereby reducing the intensity of the reflected light.

[0049] Ninth, the present application relates to an anti-reflection coating (AR), also known as an anti-reflection coating or an anti-reflection coating. It is formed by coating one or more layers of thin films on a substrate. These thin films are usually composed of alternating materials with high and low refractive indices. Among them, the film layer with a high refractive index will cause the phase of the light wave to be delayed, and the film layer with a low refractive index will cause the phase of the light wave to be advanced. When light is incident on the surface of the substrate from the external medium, a part of the light wave will be reflected on the surface of the substrate, and the other part will pass through the substrate and be reflected again, thereby interfering with the reflected light on the surface. Therefore, by controlling the thickness and refractive index of each layer, the interference effect at the surface of the substrate is minimized, thereby achieving the purpose of anti-reflection and anti-transmission.

[0050] FIG1 is a schematic diagram of an application scenario of the HUD device provided in an embodiment of the present application. As shown in FIG1 , the HUD device is provided on a car. The HUD device is used to project the vehicle's status information, indication information of external objects, and navigation information into the driver's field of view through the vehicle's windshield (also referred to as a windshield). Status information includes but is not limited to information such as driving speed, mileage, fuel level, water temperature, and headlight status. Information indicating external objects includes but is not limited to safe vehicle distance, surrounding obstacles, and reversing images. Navigation information includes but is not limited to direction arrows, distance, and driving time.

[0051] Among them, the virtual images corresponding to the navigation information and the indication information of external objects can be superimposed on the real environment outside the vehicle, so that the driver can obtain the visual effects of augmented reality, such as augmented reality (AR) navigation, adaptive cruise, lane departure warning, etc. Since the virtual image corresponding to the navigation information can be combined with the real scene, the HUD device is usually coordinated with the advanced driving assistant system (ADAS) system of the car. In order not to interfere with the road conditions, the virtual image corresponding to the instrument information is usually about 2 to 3 meters away from the human eye. In order to better integrate the virtual image corresponding to the navigation information with the real road surface, the virtual image corresponding to the navigation information is generally about 7 to 15 meters away from the human eye. Among them, the position where the virtual image of the navigation information is located is called the far focal plane, and the plane where the virtual image of the instrument information is located is called the near focal plane.

[0052] Currently, research on HUD devices focuses on preventing sunlight backflow and reducing their size. The main cause of sunlight backflow is that sunlight entering the imaging system generates white spots on the surface of the diffuser screen. After reflecting off the diffuser screen, the white spots re-enter the imaging light path and reach the human eye, causing screen glare. Therefore, to prevent glare caused by sunlight backflow and improve user experience, HUD devices typically set the normal direction of the diffuser screen to be misaligned with the main direction of the imaging light. For example, in common HUD devices using Liquid Crystal On Silicon (LCoS) as the display chip and HUD devices using Digital Light Processing (DLP) as the display chip, the normal direction of the diffuser screen is typically at an angle of 15° to 30° with the main direction of the imaging light. However, the main direction of the image light projected by the display chip onto the diffuser screen is usually less than or equal to 15°. This results in the main direction of the image light incident on the diffuser screen not matching the design, resulting in energy loss and affecting image quality. In order to ensure the display effect of the HUD device, the angle arrangement between the PGU and the diffuser screen, as well as the angle arrangement between the diffuser screen and the reflective element (used to reflect the image light into the human eye) need to strictly comply with the design, resulting in limited spatial layout of the HUD device and difficulty in reducing its volume. In order to make up for this design defect of the HUD device, some solutions introduce field lenses, such as cylindrical lenses, into the HUD device to correct the angle of the image light incident on the diffuser screen. The optical path diagram of this solution is shown in Figure 2. However, in this solution, since the cylindrical lens is thicker and larger in size, more space is required in the HUD device to accommodate the cylindrical lens, resulting in a larger HUD device. At the same time, the thicker cylindrical lens will also affect the clarity of the imaging. In addition, the cylindrical lens will also increase the reflective surface of the system, resulting in stray light in the HUD device and increasing the probability of glare.

[0053] To avoid the many drawbacks associated with the use of field lenses, this application proposes a diffuser screen with an anti-reflection and anti-reflection coating applied to at least one surface. This reduces glare caused by sunlight backflowing into the display device, thereby improving the HUD's visual quality. Compared to solutions that incorporate field lenses in the HUD's optical path, this solution does not increase the display device's size and avoids the degradation of display quality caused by field lenses.

[0054] Figure 3 is a schematic diagram of the structure of a first diffuser screen 300 provided in an embodiment of the present application. As shown in Figure 3 , diffuser screen 300 includes a first surface 301, on which a first film system 302 is disposed. First film system 302 comprises N first thin film layers with different refractive indices, namely, first film #1, first film #2, ..., first film #N in Figure 3 , where N is an integer greater than or equal to 2. First film system 302 is used to reduce the reflectivity of incident light on first film system 302.

[0055] Optionally, the refractive index of the multilayer first thin films of the first film system 302 gradually decreases in a direction away from the first surface 301 .

[0056] For example, when N is 5, the first film system 302 includes a first film #1, a first film #2, a first film #3, a first film #4, and a first film #5. In this case, the first film #1, the first film #2, the first film #3, the first film #4, and the first film #5 are arranged in the order from the first surface 301 to the direction away from the first surface 301. That is, the first film #1 is arranged on the first surface 301, the first film #2 is arranged on the first film #1, the first film #3 is arranged on the first film #2, the first film #4 is arranged on the first film #3, and the first film #5 is arranged on the first film #4, with the first film #5 in contact with air. If the refractive index of the first film #1 is n1, the refractive index of the first film #2 is n2, the refractive index of the first film #3 is n3, the refractive index of the first film #4 is n4, and the refractive index of the first film #5 is n5, then n1>n2>n3>n4>n5.

[0057] It is understood that in a HUD system, when sunlight enters the first surface 301 of the diffuser 300 from the air, reflection and refraction occur. This reflected light may re-enter the imaging optical path, causing glare in the HUD system, affecting imaging quality and posing a safety hazard to the driver. Therefore, after the first film system 302 is provided on the first surface 301 of the diffuser 300, the refractive index of the first film system 302 no longer changes suddenly when incident from the air onto the first surface 301. Instead, the refractive index gradually increases from the air to the first surface 301. Therefore, the transmittance of sunlight can be increased while the reflectivity can be reduced. Furthermore, because the refractive indices of the multilayer thin films differ, light can be designed to interfere between the films, thereby offsetting reflections and further improving transmittance.

[0058] Optionally, the first film system 302 is an anti-reflection film.

[0059] It should be noted that, regardless of whether the first film system 302 is a multilayer film with a gradient refractive index or an AR film with a staggered refractive index distribution, the refractive index of each layer is determined based on the refractive index of the diffuser screen 300 material and the target reflectivity of the first film system for incident light. In other words, once the diffuser screen material and the target reflectivity of the system settings are determined, the number of layers, refractive index, and thickness of the first film system 302 can be designed based on these parameters. This ensures that, after the first film system 302 is applied to the first surface of the diffuser screen 300, the reflectivity of the reflected light is less than or equal to the target reflectivity.

[0060] Optionally, the base material of the diffusion screen 300 is polymethyl methacrylate (PMMA), polycarbonate (PC), optical glass, etc., which is not limited in this application.

[0061] In the embodiment of the present application, the first film system 302 can be formed by physical vapor deposition (PVD) or chemical vapor deposition (CVD), such as atomic layer deposition (ALD), sputtering, or wet coating, etc., which are not limited in this application. For processes such as PVD, CVD, ALD, sputtering, and wet coating, reference can be made to the existing related technical process descriptions, which will not be repeated here. It is understood that the processes listed above for forming the first film system 302 are currently common coating processes, and other coating processes developed in the future should also be applicable to the solutions of this application.

[0062] To further eliminate reflections from the first film system 302 and improve transmission performance, a microstructure can be provided on the first surface 301, as shown in Figure 4 , which schematically illustrates the structure of a second diffuser screen 400 provided in an embodiment of the present application. As shown in Figure 4 , microstructures 401, also referred to as microstructure arrays, are provided on the first surface 301 of the diffuser screen 400. These microstructures are used to reduce the reflectivity of incident light on the first surface 301.

[0063] Optionally, the microstructure is a light-trapping structure. When a conical light-trapping structure is provided on the first surface 301 of the diffuser screen 400, incident light will be scattered at the interface of the nano-light-trapping structure, thereby reducing the probability of reflection. Specifically, when light strikes the surface of the light-trapping structure, some light will be reflected back, while another part will enter the interior of the light-trapping structure, undergoing multiple reflections and refractions before leaving the material surface. Due to the phase difference between the reflected light and the light entering the light-trapping structure, these two parts of light will interfere at the first surface 301, further reducing the intensity of the reflected light.

[0064] When a light-trapping structure is used, in the embodiment of the present application, the first film system 302 can be a bionic anti-reflection optical film based on the light-trapping properties of butterfly scales, or a bionic anti-reflection optical film based on the light-trapping properties of a moth-eye structure. The light-trapping structure can be prepared using methods such as selective etching or etching, which are not limited in this application.

[0065] FIG5 is a schematic structural diagram of a third type of diffuser screen 500 provided in an embodiment of the present application. As shown in FIG5 , the diffuser screen 500 includes a first surface 301 and a second surface 501. A first film system 302 is provided on the first surface 301. The first film system 302 includes N layers of first thin films with different refractive indices, namely, first film #1, first film #2, ..., first film #N in FIG5 , where N is an integer greater than or equal to 2. The second film system 502 includes M layers of second thin films with different refractive indices, namely, second film #1, second film #2, ..., second film #M in FIG5 , where M is an integer greater than or equal to 2. The first film system 302 is used to reduce the reflectivity of incident light on the first film system 302. The second film system 502 is used to reduce the reflectivity of incident light on the second film system 502.

[0066] Optionally, the refractive index of the multilayer first thin films of the first film system 302 gradually decreases in a direction away from the first surface 301 . The refractive index of the multilayer second thin films of the second film system 502 gradually decreases in a direction away from the second surface 501 .

[0067] For example, when N is 5 and M is 3, the first film system 302 includes a first film #1, a first film #2, a first film #3, a first film #4, and a first film #5. In this case, the first film #1, the first film #2, the first film #3, the first film #4, and the first film #5 are sequentially arranged in a direction away from the first surface 301. That is, the first film #1 is arranged on the first surface 301, the first film #2 is arranged on the first film #1, the first film #2 is arranged on the first film #3, the first film #3 is arranged on the first film #4, and the first film #4 is arranged on the first film #5, with the first film #5 in contact with air. The second film system 502 includes a second film #1, a second film #2, and a second film #3. In this case, the second film #1, the second film #2, and the second film #3 are sequentially arranged in a direction away from the second surface 501. That is, the second film #1 is arranged on the second surface 501, the second film #2 is arranged on the second film #1, the second film #2 is arranged on the second film #3, and the first film #3 is in contact with air. If the refractive index of the first film #1 is n11, the refractive index of the first film #2 is n12, the refractive index of the first film #3 is n13, the refractive index of the first film #4 is n14, and the refractive index of the first film #5 is n15, then n11>n12>n13>n14>n15. If the refractive index of the second film #1 is n21, the refractive index of the first film #2 is n22, and the refractive index of the first film #3 is n23, then n21>n22>n23.

[0068] Optionally, at least one of the first film system 302 and the second film system 502 is an anti-reflection film.

[0069] It should be noted that, in the diffuser screen 500 shown in FIG. 5 , the first film system 302 may be the same as the second film system 502 , or the first film system 302 may be different from the second film system 502 .

[0070] For example, when the first film system 302 and the second film system 502 are identical, the films disposed on the first surface 301 and the second surface 501 of the diffuser screen 500 are identical. When the second film system 502 and the first film system 302 are identical, the description of the second film system 502 can be found in the descriptions of FIG. 3 and FIG. 4 above and will not be repeated here.

[0071] For example, when the first film system 302 and the second film system 502 are different, the first film system 302 and the second film system 502 may be different in at least one of the following:

[0072] The number of film layers in the first film system 302 is different from the number of film layers in the second film system 502; the refractive index of at least one first film in the multilayer first film is different from the refractive index of at least one second film in the multilayer second film; the thickness of at least one first film in the multilayer first film is different from the thickness of at least one second film in the multilayer second film.

[0073] When the number of film layers in the first film system 302 is different from the number of film layers in the second film system 502, the number of layers in the first film system 302 may be greater than the number of layers in the second film system 502. For example, in FIG5 , N is greater than M. Alternatively, the number of layers in the first film system 302 may be less than the number of layers in the second film system 502. That is, in FIG5 , N is less than M.

[0074] When the refractive index of at least one of the multiple layers of first thin films in the first film system 302 differs from the refractive index of at least one of the multiple layers of second thin films in the second film system 502, it may be that the refractive index of one or more of the multiple layers of first thin films in the first film system 302 differs from the refractive index of one or more of the multiple layers of second thin films in the second film system 502. For example, if N equals M, the refractive index of at least one of the first thin films in the first film system 302 may differ from the refractive index of at least one of the second thin films at a corresponding position in the second film system 502. For example, the refractive indexes of first film #1 and second film #1 may differ, or the refractive indexes of first film #1 and second film #1 may differ while the refractive indexes of first film #3 and second film #3 also differ. Similarly, other different situations are not enumerated here.

[0075] When the thickness of at least one first film in the multilayer first films of the first film system 302 differs from the thickness of at least one second film in the multilayer second films of the second film system 502, it may be that the thickness of one or more first films in the multilayer first films of the first film system 302 differs from the thickness of one or more first films in the multilayer second films of the second film system 502. For example, if N equals M, the thickness of at least one first film in the first film system 302 may differ from the thickness of at least one second film in a corresponding position in the second film system 502. For example, the thickness of first film #1 and second film #1 may differ, or the thickness of first film #1 and second film #1 may differ while the thickness of first film #2 and second film #2 also differ. Similarly, other different situations are not enumerated here.

[0076] It is understood that when the diffuser 500 is used in a HUD system, compared to a single-sided film system, a double-sided film system can further reduce the reflected light from sunlight backflow while enhancing the transmission of image light through the diffuser 500. In other words, the diffuser 500 can not only reduce the reflectivity of stray light, but also reduce the loss of image light.

[0077] It can also be understood that the first film system 302 and the second film system 502 can both be film systems with a gradient refractive ratio, or both can be anti-reflection films, or one can be a film system with a gradient refractive ratio and the other can be an anti-reflection film, which is not limited in this application.

[0078] It is understandable that the second film system 502 can be formed using processes such as PVD, CVD, ALD, sputtering, and wet coating, which is not limited in this application.

[0079] Furthermore, to further eliminate reflection from the first film system 502 and improve transmission performance, a microstructure (e.g., a light-trapping structure) can be provided on the second surface 501 using methods such as selective etching or corrosion. As shown in FIG6 , microstructures 601 are provided on the second surface 501 of the diffuser screen 600, thereby further reducing the intensity of reflected light and enhancing the intensity of transmitted light. It is understood that when microstructures are provided on the second surface 501, the first surface 301 may or may not be provided with microstructures, depending on the reflectivity requirements for the reflected light. This is not a limitation of the present application.

[0080] Next, some possible structures of the display device provided in this application are described in conjunction with the diffusion screen shown in FIG. 3 to FIG. 6 .

[0081] FIG7 is a schematic diagram of a display device 700 provided in an embodiment of the present application. As shown in FIG7 , the display device 700 includes a projection module 701, a diffuser screen 702, a first reflective element 703, and a second reflective element 704. The projection module 701 is configured to project image light onto the second surface (such as surface 2 in FIG7 ) of the diffuser screen 702. The diffuser screen 702 is configured to transmit the image light from the projection module from its first surface (such as surface 1 in FIG7 ) to the first reflective element, and to generate a relay image on the first surface based on the image light from the projection module. The first reflective element 703 is configured to reflect the image light emitted by the diffuser screen 702 to the second reflective element 704. The second reflective element 704 is configured to reflect the image light reflected by the first reflective element 703 toward the human eye. The diffuser screen 702 may be any of the diffusers shown in FIG3 to FIG6 , or a new diffuser designed based on any of the diffusers shown in FIG3 to FIG6 .

[0082] It can be understood that since the display device 700 provided in the present application adopts the diffusion screen provided in the present application for reducing the reflectivity of incident light (including any one of the above-mentioned diffusion screen 300, diffusion screen 400, diffusion screen 500 and diffusion screen 600), when sunlight enters the interior of the display device 700 from the outside, it is reflected by the second reflection element 704 and the first reflection element 703 in sequence and reaches the diffusion screen 702. Since the surface of the diffusion screen 702 is provided with at least one of the first film system or the second film system, the reflected light of the sunlight at the diffusion screen 702 can be reduced, thereby avoiding the reflected light from re-entering the imaging light path and mixing with the image light, thereby avoiding the glare phenomenon caused by the reflected light.

[0083] Optionally, the display device 700 may further include a dust cover 705. The dust cover 705 has the functions of isolating the external high temperature, preventing the internal temperature of the display device 700 from being too high, or preventing external dust from entering the device.

[0084] In order to further reduce the glare caused by the reflected light, in some embodiments, the perpendicular bisector of the diffusion screen 702 and the main ray of the image light may form a certain angle, for example, an angle greater than 15°.

[0085] In the embodiment of the present application, the projection module 701 can adopt an LCoS display, an organic light-emitting diode (OLED) display, a liquid crystal display (LCD), a digital light processing (DLP) display or a micro-electro-mechanical system (MEMS) display, etc., which is not limited in this application.

[0086] It should be noted that, in the display device 700 shown in FIG7 , the first reflective element 703 may be a concave mirror, a convex mirror, or a plane mirror with a free-form surface, which is not limited in this application.

[0087] It is understandable that the number of reflective elements included in the display device 700 is not limited to that shown in FIG. 7 and can be adjusted accordingly according to needs.

[0088] As an example, Figure 8 illustrates a possible structure of a projection module 701 provided in an embodiment of the present application. Projection module 701 includes a light source 711, a modulation unit 712, and a projection device 713. Depending on the display technology employed by projection module 701, modulation unit 712 can be an LCoS modulator, a DMD, or a transmissive spatial light modulator (LCD). For example, when modulation unit 712 is an LCoS modulator, light source 711 can be a red, green, or blue light emitting diode (LED) light source, which together with the LCoS modulator forms an LCoS display. When modulation unit 712 is a DMD, it can be a MEMS-controlled DMD modulator, combined with a laser or LED light source to form a DLP display. Alternatively, when modulation unit 712 is an LCD modulator, light source 711 can be a linear light source composed of red, green, and blue cold cathode fluorescent tubes, which together with the LCD modulator form an LCD display. Projection device 713 can be a projection lens.

[0089] Optionally, to improve projection quality and / or reduce the volume of the projection module 701, in some embodiments, the projection module 701 further includes a refraction module 714, or the projection module 701 further includes a polarization conversion module 714. When the projection module 701 includes the refraction module 714, the refraction module 714 can be one or more lenses (for focusing the energy of the light beam to ensure the energy of the light beam or for diffusing the light spot to increase the projection field of view), and / or one or more prisms (for folding the light path to reduce the volume of the projection module), etc., and this application does not limit this. When the projection module 701 includes the polarization conversion module 714, the polarization conversion module 714 is used to change the polarization state of the image light.

[0090] As an example, FIG9 provides a possible structure of a projection module 701 in which the modulation unit 712 is a DMD in an embodiment of the present application. As shown in FIG9 , the light source 711 includes a first monochromatic light array 911, a second monochromatic light array 912, a third monochromatic light array 913, dichroic filters 921 and 922, and a lens group 933. The three monochromatic light arrays can respectively correspond to monochromatic light of the three primary colors, including red light, blue light, and green light. In order to improve the utilization rate of light energy, in some embodiments, a collimating lens is further arranged after the monochromatic light array, such as the collimating lens 9111, the collimating lens 9112, and the collimating lens 9113 in FIG9 . The refractive module 714 includes a lens group and a prism. Specifically, when the projection module 701 is used in the display device 700 shown in Figure 7, the first monochromatic light array 911, the second monochromatic light array 912, and the third monochromatic light array 913 respectively emit corresponding monochromatic lights. The three monochromatic lights pass through the dichroic filters 921 and 922 and are incident on the lens group of the refractive module. After being emitted from the lens group, they are incident on the DMD 712 through the prism. The DMD 712 modulates the input light beam based on the data information of the input image and outputs image light. The image light is incident on the projection device 713 after transmitting through the prism, and then emits the image light toward the diffusion screen through the projection device 713.

[0091] When the display device 700 is applied to a vehicle, FIG10 is a schematic diagram of an optical path 1000 of the display device 700 provided in an embodiment of the present application applied to a vehicle. Specifically, the projection module 701 generates image light and projects the image light to the diffusion screen 702. While the diffusion screen 702 generates a relay image, it transmits the image light from the projection module to the first reflective element 703. Then, the first reflective element 703 reflects the image light from the diffusion screen 702 to the second reflective element 704. After being reflected by the second reflective element 704, the image light transmits the light shield 705 and is reflected through the windshield 1001 to the human eye for imaging. The image generated by the image light can be an augmented reality display image, which is used to display information such as indication information and navigation information of external objects. Alternatively, the image generated by the image light can be a status display image, which is used to display status information of a vehicle. Taking a car as an example, the status information of a vehicle is not limited to information such as driving speed, mileage, fuel level, water temperature, and headlight status.

[0092] It is understandable that the means of transportation to which the present application scheme can be applied include but are not limited to cars, airplanes, trains or ships.

[0093] In addition, an embodiment of the present application further provides a vehicle, which includes any of the aforementioned display devices, including but not limited to cars, airplanes, trains, or ships.

[0094] Figure 11 is a circuit diagram of a display device provided in an embodiment of the present application. As shown in Figure 11, the circuit in the display device mainly includes a host CPU 1201, an external memory interface 1202, an internal memory 1203, an audio module 1204, a video module 1205, a power module 1206, a wireless communication module 1207, an I / O interface 1208, a video interface 1209, a display circuit 1210 and a modulator 1212. Among them, the main processor 1201 and its peripheral components, such as the external memory interface 1202, the internal memory 1203, the audio module 1204, the video module 1205, the power module 1206, the wireless communication module 1207, the I / O interface 1208, the video interface 1209, and the display circuit 1210 can be connected via a bus. The main processor 1201 can be called a front-end processor.

[0095] In addition, the circuit diagrams shown in the embodiments of the present application do not constitute specific limitations on the display device. In other embodiments of the present application, the display device may include more or fewer components than shown, or may combine or separate certain components, or arrange the components differently. The components shown in the diagrams may be implemented in hardware, software, or a combination of software and hardware.

[0096] The main processor 1201 includes one or more processing units. For example, the main processor 1201 may include an application processor (AP), a modem processor, a graphics processor (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural network processor (NPU). Different processing units may be independent devices or integrated into one or more processors.

[0097] The main processor 1201 may also be provided with a memory for storing instructions and data. In some embodiments, the memory in the main processor 1201 is a cache memory. This memory can store instructions or data that the main processor 1201 has just used or is reusing. If the main processor 1201 needs to use the instruction or data again, it can directly call it from the memory. This avoids repeated accesses, reduces the waiting time of the main processor 1201, and thus improves system efficiency.

[0098] In some embodiments, the display device may further include multiple input / output (I / O) interfaces 1208 connected to the main processor 1201. The interfaces 1208 may include an I2C (Inter-Integrated Circuit) interface, an I2S (Inter-Integrated Circuit Sound) interface, a PCM (Pulse Code Modulation) interface, a UART (Universal Asynchronous Receiver / Transmitter) interface, a MIPI (Mobile Industry Processor Interface) interface, a GPIO (General-Purpose Input / Output) interface, a SIM (Subscriber Identity Module) interface, and / or a USB (Universal Serial Bus) interface. The I / O interfaces 1208 may be connected to devices such as a mouse, touchpad, keyboard, camera, speaker, microphone, etc., as well as physical buttons on the display device (e.g., volume button, brightness adjustment button, power button, etc.).

[0099] The external memory interface 1202 can be used to connect an external memory card, such as a Micro SD card, to expand the storage capacity of the display device. The external memory card communicates with the main processor 1201 through the external memory interface 1202 to implement data storage function.

[0100] The internal memory 1203 can be used to store computer executable program codes, which include instructions. The internal memory 1203 may include a program storage area and a data storage area. The program storage area may store an operating system, an application required for at least one function (such as a call function, a time setting function, etc.), etc. The data storage area may store data created during the use of the display device (such as a phone book, world time, etc.), etc. In addition, the internal memory 1203 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, a universal flash memory (UFS), etc. The main processor 1201 executes various functional applications and data processing of the display device by running instructions stored in the internal memory 1203 and / or instructions stored in a memory provided in the main processor 1201.

[0101] The display device can implement audio functions such as music playback and calls through the audio module 1204 and the application processor.

[0102] The audio module 1204 is used to convert digital audio information into analog audio signal output, and is also used to convert analog audio input into digital audio signals. The audio module 1204 can also be used to encode and decode audio signals, such as for playing or recording. In some embodiments, the audio module 1204 can be provided in the main processor 1201, or some functional modules of the audio module 1204 can be provided in the main processor 1201.

[0103] The video interface 1209 can receive external audio and video signals, which can specifically be a High Definition Multimedia Interface (HDMI), a Digital Visual Interface (DVI), a Video Graphics Array (VGA), a Display Port (DP), etc. The video interface 1209 can also output video to the outside. When the display device is used as a head-up display, the video interface 1209 can receive speed signals and power signals input from peripheral devices, and can also receive external AR video signals. When the display device is used as a projector, the video interface 1209 can receive video signals input from an external computer or terminal device.

[0104] The video module 1205 can decode the video input from the video interface 1209, for example, by performing H.264 decoding. The video module can also encode the video captured by the display device, for example, by performing H.264 encoding on the video captured by an external camera. Furthermore, the main processor 1201 can also decode the video input from the video interface 1209 and output the decoded image signal to the display circuit 1210.

[0105] The display circuit 1210 and modulator 1212 are used to display corresponding images. In this embodiment, the video interface 1209 receives an external video source signal, which the video module 1205 decodes and / or digitizes before outputting one or more image signals to the display circuit 1210. The display circuit 1210 drives the modulator 1212 based on the input image signal to image the incident polarized light and output image light. Furthermore, the main processor 1201 may also output one or more image signals to the display circuit 1210.

[0106] In this embodiment, the display circuit 1210 and the modulator 1212 are electronic components in the modulation unit 712 shown in FIG. 8 , and the display circuit 1210 can be referred to as a driving circuit.

[0107] The power module 1206 is used to provide power to the main processor 1201 and the light source 1200 based on input power (e.g., direct current). The power module 1206 may include a rechargeable battery, which can provide power to the main processor 1201 and the light source 1200. Light emitted by the light source 1200 can be transmitted to the modulator 1212 for imaging, thereby forming an image light signal.

[0108] The wireless communication module 1207 enables the display device to communicate wirelessly with the outside world. It can provide wireless local area networks (WLAN) (such as Wireless Fidelity (Wi-Fi) networks), Bluetooth (BT), Global Navigation Satellite System (GNSS), Frequency Modulation (FM), Near Field Communication (NFC), infrared technology (IR) and other wireless communication solutions. The wireless communication module 1207 can be one or more devices that integrate at least one communication processing module. The wireless communication module 1207 receives electromagnetic waves via an antenna, frequency modulates and filters the electromagnetic wave signals, and sends the processed signals to the main processor 1201. The wireless communication module 1207 can also receive signals to be sent from the main processor 1201, frequency modulate them, amplify them, and convert them into electromagnetic waves for radiation through the antenna.

[0109] In addition, in addition to being input through the video interface 1209, the video data decoded by the video module 1205 can also be received wirelessly through the wireless communication module 1207 or read from an external memory. For example, the display device can receive video data from a terminal device or an in-vehicle entertainment system through the wireless local area network in the vehicle, and the display device can also read audio and video data stored in an external memory.

[0110] The above-mentioned display device can be installed on a vehicle. Please refer to Figure 12, which is a schematic diagram of a possible functional framework of a vehicle provided in an embodiment of the present application.

[0111] As shown in FIG12 , the functional framework of a vehicle may include various subsystems, such as a sensor system 12, a control system 14, one or more peripheral devices 16 (one of which is shown as an example), a power supply 18, a computer system 20, and a head-up display system 22. Optionally, the vehicle may also include other functional systems, such as an engine system that provides power for the vehicle, etc., which are not limited in this application.

[0112] The sensor system 12 may include a plurality of detection devices that sense the information being measured and convert the sensed information into electrical signals or other required information outputs according to certain rules. As shown in the figure, these detection devices may include a global positioning system (GPS), a vehicle speed sensor, an inertial measurement unit (IMU), a radar unit, a laser rangefinder, a camera, a wheel speed sensor, a steering sensor, a gear position sensor, or other components for automatic detection, etc., and this application does not limit them.

[0113] The control system 14 may include several components, such as a steering unit, a braking unit, a lighting system, an autonomous driving system, a map navigation system, a network timing system, and an obstacle avoidance system, as shown. Optionally, the control system 14 may also include components such as a throttle controller and an engine controller for controlling vehicle speed, although this application does not limit this.

[0114] The peripheral devices 16 may include several components, such as the communication system shown in the figure, a touch screen, a user interface, a microphone, and a speaker. The communication system is used to enable network communication between the vehicle and other devices. In practical applications, the communication system may utilize wireless communication technology or wired communication technology to enable network communication between the vehicle and other devices. Wired communication technology may involve communication between the vehicle and other devices via network cables or optical fibers.

[0115] Power supply 18 represents a system that provides electrical power or energy to the vehicle, and may include, but is not limited to, rechargeable lithium batteries or lead-acid batteries. In practical applications, one or more battery components in the power supply are used to provide electrical energy or energy for starting the vehicle. The type and material of the power supply are not limited in this application.

[0116] Several functions of the vehicle are controlled and implemented by a computer system 20. The computer system 20 may include one or more processors 2001 (a single processor is shown as an example) and a memory 2002 (also referred to as a storage device). In practical applications, the memory 2002 may be internal to the computer system 20 or external to the computer system 20, for example, as a cache in the vehicle, although this application does not limit this.

[0117] in,

[0118] The processor 2001 may include one or more general-purpose processors, such as a graphics processing unit (GPU). The processor 2001 may be used to run relevant programs or instructions corresponding to the programs stored in the memory 2002 to implement corresponding functions of the vehicle.

[0119] The memory 2002 may include a volatile memory, such as RAM; the memory may also include a non-volatile memory, such as ROM, flash memory, HDD or solid-state drive SSD; the memory 2002 may also include a combination of the above types of memory. The memory 2002 can be used to store a set of program codes or instructions corresponding to the program codes, so that the processor 2001 can call the program codes or instructions stored in the memory 2002 to implement the corresponding functions of the vehicle. In the present application, the memory 2002 can store a set of program codes for vehicle control, and the processor 2001 can call the program codes to control the safe driving of the vehicle. How to achieve safe driving of the vehicle is described in detail below in this application.

[0120] Optionally, in addition to storing program code or instructions, memory 2002 may also store information such as road maps, driving routes, and sensor data. Computer system 20 may integrate with other components in the vehicle functional framework diagram, such as sensors and GPS in the sensor system, to implement relevant vehicle functions. For example, computer system 20 may control the vehicle's direction or speed based on data input from sensor system 12, although this application does not limit this.

[0121] The head-up display system 22 may include several components, such as the windshield shown, a controller, and a head-up display. The controller 222 is configured to generate images (e.g., images containing vehicle status such as speed, battery / fuel level, and augmented reality (AR) content) in response to user instructions and transmit these images to the head-up display for display. The head-up display may include an image generation unit and a reflector assembly. The windshield is configured to cooperate with the head-up display to implement the optical path of the head-up display system, thereby presenting the target image in front of the driver. The functions of some components of the head-up display system may also be implemented by other subsystems of the vehicle. For example, the controller may also be a component of the control system.

[0122] FIG12 of this application illustrates four subsystems: sensor system 12, control system 14, computer system 20, and head-up display system 22. These subsystems are merely illustrative and not limiting. In practice, a vehicle may combine several components according to different functions to create subsystems with corresponding functions. In practice, a vehicle may include more or fewer systems or components, and this application does not limit this.

[0123] The above-mentioned transportation vehicles can be cars, trucks, motorcycles, buses, ships, airplanes, helicopters, lawn mowers, recreational vehicles, amusement park vehicles, construction equipment, trams, golf carts, trains, and carts, etc., and the embodiments of the present application do not make special limitations.

[0124] Unless otherwise defined, technical or scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0125] The above description is only one embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the present application shall be included in the scope of protection of the present application.

Claims

1. A diffusion screen, characterized in that: include: First surface, A first film system is disposed on the first surface, wherein the first film system includes a plurality of first thin films with different refractive indices, and the first film system is used to reduce the reflectivity of incident light on the first film system.

2. The diffuser screen according to claim 1, characterized in that: The refractive index of the multi-layer first thin film gradually decreases in a direction away from the first surface.

3. The diffuser screen according to claim 1 or 2, characterized in that: The diffusion screen further includes a second surface, the second surface is opposite to the first surface, and the first film system is disposed on the second surface.

4. The diffuser screen according to claim 3, characterized in that: The refractive index of the multi-layer first thin film gradually decreases in a direction away from the second surface.

5. The diffuser screen according to claim 1 or 2, characterized in that: The diffusion screen further includes a second surface, the second surface is opposite to the first surface, a second film system is arranged on the second surface of the diffusion screen, the second film system includes a plurality of second thin films with different refractive indices, and the second film system is used to reduce the reflectivity of incident light on the second film system. The first film system and the second film system are different in at least one of the following: The number of layers of the first film system and the second film system, the refractive index of at least one first film in the multilayer first film and the refractive index of at least one second film in the multilayer second film, the thickness of at least one first film in the multilayer first film and the thickness of at least one second film in the multilayer second film.

6. The diffuser screen according to claim 5, characterized in that: The refractive index of the multi-layer second thin film gradually decreases in a direction away from the second surface.

7. The diffuser screen according to claim 5, characterized in that: At least one of the first film system and the second film system is an anti-reflection (AR) film.

8. The diffuser screen according to any one of claims 5 to 7, characterized in that: At least one of the first film system and the second film system includes a microstructure, and the microstructure is used to reduce the reflectivity of the incident light on the film system including the microstructure.

9. The diffuser screen according to any one of claims 1 to 8, characterized in that: The refractive index of the first film system is determined based on the refractive index of the diffusion screen and the target reflectivity of the incident light in the first film system.

10. A display device, characterized in that: The device comprises a projection module, a first reflective element, a second reflective element and a diffusion screen as claimed in any one of claims 1 to 9, wherein: The projection module is used to project image light onto a second surface of the diffusion screen, the second surface being opposite to the first surface; the diffusion screen is used to transmit the image light from the projection module from the first surface to the first reflection element, and to generate a relay image on the first surface based on the image light from the projection module; The first reflecting element is used to reflect the image light from the diffusion screen to the second reflecting element; The second reflecting element is used to reflect the image light from the first reflecting element toward human eyes.

11. The display device according to claim 10, characterized in that: An angle between a normal line of the second surface and the image light incident on the second surface is greater than or equal to 15°.

12. A means of transport, characterized in that: The device comprises the display device and the windshield according to claim 10 or 11, The windshield is used to reflect the image light from the display device to human eyes.

13. A vehicle-mounted system, characterized in that: Includes the display device according to claim 10 or 11.

Images