Display device and vehicle display system

Abstract

This invention discloses a display device and a carrier display system including the same. The display device includes a display module, a first optical element, and a reflector. The display module includes a first display area and a second display area, respectively for emitting first image light and second image light. The first optical element includes a beam splitter, which is disposed on the side of the first optical element facing the display module and reflects at least a portion of the first image light and transmits at least a portion of the second image light. The reflector reflects the first image light reflected by the beam splitter to the first optical element, and at least a portion of the first image light reflected by the reflector is transmitted through the first optical element. At least a portion of the first image light and at least a portion of the second image light transmitted through the first optical element generate a first image and a second image respectively in a virtual eye area.

Description

Technical Field

[0001] This invention relates to a display device and a vehicle display system including the same. Specifically, this invention relates to a display device that utilizes optical reflection and transmission to simultaneously project and display images with different image distances, and a vehicle display system including the same. Prior Technology

[0002] With the development of automotive display technology, head-up displays (HUDs) have become increasingly widely used in various vehicle models. By projecting virtual images in front of the driver's field of vision, drivers can receive visual information without taking their eyes off the road, effectively improving driving safety and user experience. HUD systems with longer imaging distances, in particular, can present virtual images further away from the driver, facilitating natural eye movements and real-time information recognition. However, to achieve a longer virtual image distance (VID) and maintain clear and stable image quality, the optical imaging path often needs to be extended, leading to an increase in the overall size of the display system and limiting the application of HUDs in the confined space of a vehicle.

[0003] Furthermore, due to the reversibility of the optical path, when a head-up display is designed with a high magnification, sunlight may enter in reverse along the imaging path and focus on the surface of the Picture Generation Unit (PGU), creating solar loading and reducing display quality and system lifespan. Therefore, minimizing system size and providing protection against solar loading are significant challenges in the automotive display field. Summary of the Invention

[0004] One object of the present invention is to provide a display device comprising optical elements having partial transmission and partial reflection properties, for providing diverse optical path combinations within a limited space to simultaneously project and display images with different image distances.

[0005] Another object of the present invention is to provide a vehicle display system, which is disposed within a vehicle and includes optical elements having partial transmission and partial reflection properties, so as to simultaneously project and display images with different image distances on a windshield.

[0006] The display device includes a display module, a first optical element, and a reflector. The display module includes a first display area and a second display area, respectively used to emit a first image light and a second image light. The first optical element is disposed in the optical path of the first image light and the second image light and includes a beam splitter, wherein the beam splitter is disposed on the side of the first optical element facing the display module and configured to reflect at least a portion of the first image light and transmit at least a portion of the second image light. The reflector is disposed in the optical path of the first image light after reflection by the beam splitter and configured to reflect the first image light reflected by the beam splitter to the first optical element, and at least a portion of the first image light reflected by the reflector is transmitted through the first optical element. At least a portion of the first image light and at least a portion of the second image light transmitted through the first optical element generate a first image and a second image respectively in a virtual eye area.

[0007] On the other hand, the vehicle display system is installed inside the vehicle and includes the aforementioned display device. The vehicle includes a windshield, and the windshield reflects first image light and second image light to generate first image and second image respectively. Simple Explanation of the Diagram

[0008] Figure 1 is a cross-sectional schematic diagram of a display device according to an embodiment.

[0009] Figure 2 is a schematic diagram of the transmission and reflection paths of the display device in the embodiment of Figure 1.

[0010] Figure 3 is a schematic diagram of optical imaging of a display device according to another embodiment.

[0011] Figure 4 is a schematic diagram of the optical imaging of a display device according to another embodiment.

[0012] Figure 5 is a schematic diagram of optical imaging of a display device according to another embodiment.

[0013] Figure 6 is a schematic diagram of the sunlight load path of a display device according to another embodiment.

[0014] Figure 7A is a cross-sectional schematic diagram of a display device according to another embodiment.

[0015] Figure 7B is a schematic diagram of the solar glare path of the display device in the embodiment of Figure 7A.

[0016] Figure 8A is a cross-sectional schematic diagram of a display device according to another embodiment.

[0017] Figure 8B is a schematic diagram of the solar glare path of the display device in the embodiment of Figure 8A.

[0018] Figure 9 is a perspective view of a vehicle display system according to an embodiment. Implementation

[0019] Various embodiments will be described below, and those skilled in the art should readily understand the spirit and principles of the invention by referring to the description and accompanying drawings. However, while specific embodiments will be described in detail herein, these embodiments are merely illustrative and are not intended to be limiting or exhaustive in any respect. Therefore, various changes and modifications to the invention will be readily apparent and easily achievable by those skilled in the art without departing from the spirit and principles of the invention.

[0020] In the accompanying drawings, the thicknesses of layers, films, panels, regions, etc., are enlarged for clarity. The relative dimensions of the elements in the drawings are merely illustrative and not intended to limit the invention. The embodiments described herein should not be construed as being limited to the specific shapes of the areas shown in the drawings; for example, areas shown or described as flat may generally have rough and / or non-linear characteristics. Furthermore, the optical paths shown in the drawings are merely schematic and not intended to illustrate the precise angles and directions of the optical paths.

[0021] It should be understood that when a component such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another component, it may be directly on or connected to the other component, or intermediate components may also be present. Conversely, when a component is referred to as being "directly on" or "directly connected to" another component, no intermediate components are present. As used herein, "connection" may refer to physical and / or electrical connections. Furthermore, "electrical connection" or "electrical coupling" indicates that intermediate components may be present.

[0022] Throughout this specification, the same component symbols denote the same components. It should be understood that although the terms "first," "second," "third," etc., may be used herein to describe various components, parts, regions, layers, and / or portions, these components, regions, and / or portions should not be limited by these terms. These terms are used only to distinguish one component, part, region, layer, or portion from another. Therefore, "first element," "first component," "first region," "first layer," or "first part" discussed below may be referred to as a second element, part, region, layer, or portion without departing from the teachings herein.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not restrictive. As used herein, unless the content clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one." "Or" means "and / or." As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It should also be understood that, when used in this specification, the terms "comprising" and / or "including" specify the presence or addition of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or combinations thereof.

[0024] Figure 1 shows a cross-sectional schematic diagram and a simplified optical path diagram of a display device according to one embodiment of the present invention. The display device includes a display module 100, a first optical element 200, and a reflector 300. The display module 100 includes a first display area 110 and a second display area 120, which are used to emit a first image light L1 and a second image light L2, respectively. The display module 100 may include, but is not limited to, a backlight module, a projection module, a laser module, etc. The first display area 110 and the second display area 120 may be different blocks on the same display surface or may have different display surface orientations. They may be arranged adjacent to each other, for example, adjacent to each other on the cross-section shown in Figure 1, or arranged along different directions in different embodiments. The first optical element 200 is disposed on the optical path of the first image light L1 and the second image light L2 and includes a beam splitter 210, wherein the beam splitter 210 is disposed on the side of the first optical element 200 facing the display module 100. The beam splitter 210 has the properties of partial reflection and partial transmission, and is configured to reflect at least part of the first image light L1 and transmit at least part of the second image light L2. A reflector 300 is disposed on the optical path of the first image ray L1 after reflection by the beam splitter 210 and is configured to reflect the first image ray L1 reflected by the beam splitter 210 to the first optical element 200. At least a portion of the first image ray L1 reflected by the reflector 300 is transmitted through the first optical element 200. At least a portion of the first image ray L1 and at least a portion of the second image ray L2 transmitted through the first optical element 200 generate a first image P1 and a second image P2 respectively in the virtual eye region 500.

[0025] In some embodiments, the display device may further include a projection surface 400, which is disposed on the optical path after the first image light L1 and the second image light L2 have transmitted through the first optical element 200. The projection surface 400 is configured to at least partially reflect the first image light L1 and the second image light L2 to the virtual eye area 500, thereby generating a first image P1 and a second image P2, respectively. When the display device is installed in a vehicle, such as an automobile, and used as a head-up display, the projection surface 400 may be the windshield of the vehicle, and the virtual eye area 500 may correspond to the driver's eye position, but is not limited thereto.

[0026] Next, referring to the transmission and reflection path diagram of the display device shown in FIG2, the imaging optical paths of the first image ray L1 and the second image ray L2 will be explained respectively. The first image ray L1 shines from the first display area 110 toward the first optical element 200, and then undergoes partial transmission and partial reflection on the beam splitter 210 of the first optical element 200. Part of the first image ray L1t passes through the beam splitter 210 and travels in a direction away from the display module 100, and its image is not magnified by the reflector 300; at the same time, another part of the first image ray L1 is reflected by the beam splitter 210 to the reflective surface 310 of the reflector 300, and then reflected by the reflector 300 back to the beam splitter 210, and then undergoes partial transmission and partial reflection again on the beam splitter 210 (the reflected light does not reach the virtual eye area 500, so it is not shown). Finally, the part of the first image ray L1r that passes through the beam splitter 210 forms the first image P1 in the virtual eye area 500 (for example, reflected on the projection surface 400 as shown in FIG1 and entering the virtual eye area 500). On the other hand, the second image light L2 shines from the second display area 120 toward the first optical element 200, and then undergoes partial transmission and partial reflection on the beam splitter 210 of the first optical element 200 (the reflected light does not reach the virtual eye area 500, so it is not shown). Part of the second image light L2t passes through the beam splitter 210 and finally reaches the virtual eye area 500 (for example, it is reflected on the projection surface 400 as shown in FIG. 1 and enters the virtual eye area 500) to form the second image P2.

[0027] Furthermore, the display module 100 may further include a light guide structure 130 to adjust the emission angle range of the first image light L1 and the second image light L2. For example, the light guide structure 130 may be disposed on the boundary between the first display area 110 and the second display area 120 to limit the emission direction of the second image light L2 to be relatively far away from the first display area 110, so that the light path of the second image light L2 after being reflected by the beam splitter 210 will not reach the reflector 300. In addition, the light guide structure 130 may also be disposed in other positions to block unused light paths and avoid the formation of stray light, which would affect the image quality. By designing the light paths of the first image light L1 and the second image light L2 to be different, the first image P1 and the second image P2 can have different imaging positions and magnifications.

[0028] In some embodiments, the beam-splitting film 210 may be, for example, a thin plate with a beam-splitting effect or a coating on the first optical element 200, or it may be the first optical element 200 itself. The beam-splitting effect of the beam-splitting film 210 can be described by the beam-splitting ratio, which is defined as the energy ratio of the transmitted light to the reflected light, and the beam-splitting film 210 has the same beam-splitting ratio for light rays with different polarization directions. In other words, the polarization state of the reflected or transmitted light passing through the beam-splitting film 210 is the same as the polarization state of the incident light; when the incident light contains both S-polarized light and P-polarized light, both are allocated as reflected light and transmitted light according to the designed beam-splitting ratio.

[0029] As shown in Figure 2, after the first image ray L1 or the second image ray L2 is split by the beam splitter 210, the energy of both the transmitted and reflected light is reduced compared to the incident light (expressed as a finer linewidth). The differences in linewidth (if any) of the optical paths in the accompanying drawings are only used to illustrate the relative intensity of the light and do not represent the actual transmission / reflection ratio. The beam splitting ratio of the beam splitter 210 can be designed to be close to 1, so that the first image ray L1r used to form the first image P1 has higher energy. When the beam splitting ratio is equal to 1, the energy of the first image ray L1r, after one partial reflection (energy halved) and one partial transmission (energy halved again), can be 25% of the energy of the first image ray L1 emitted from the first display area 110; simultaneously, the energy of the second image ray L2t used to form the second image P2 (after one partial transmission) can be 50% of the energy of the second image ray L2 emitted from the second display area 120. In other embodiments, the spectrophotometer 210 may have different spectrophotometric ratios, such as, but not limited to, greater than or equal to 0.9 and less than or equal to 1.1.

[0030] The aforementioned calculation of light energy only considers the partial transmission and partial reflection properties of the beam splitter 210, without further considering the optical properties of non-planar mirrors. In different embodiments, the beam splitter 210 and / or the reflector 300 may be curved surfaces, which have the effect of converging or diverging light rays, further affecting the energy density (i.e., intensity) of the reflected light per unit area, so the brightness of the final image may vary.

[0031] Figure 2 illustrates only some representative optical paths. In different embodiments, the emission angle ranges of the first image ray L1 and the second image ray L2, the position and shape of the beam splitter 210, and the position and shape of the reflector 300 can be adjusted to form the desired optical path configuration. For example, the first optical element 200 may include, but is not limited to, planar or curved shapes. In the embodiment shown in Figure 3, the first optical element 200 may be designed as a curved surface, and the beam splitter 210 therein is also a curved surface with the same curvature and protrudes towards the display module 100 (in other words, it is recessed towards the direction away from the projection surface 400). The first optical element 200 may also have functions such as dust prevention and blocking solar glare (which will be explained later). By integrating different functions into one element, the number of elements in the display device can be reduced, and the size of the display device can be decreased. Furthermore, the reflecting surface 310 of the reflector 300 can be curved and concave in the direction away from the first optical element 200. That is, the reflector 300 can be a concave mirror, used to magnify the imaging size of the first image P1 and to converge light to enhance the brightness of the first image P1. The object distance of the first image ray L1 relative to the reflector 300 can be considered as the distance from the first display area 110 to the first optical element 200 plus the distance from the reflector 300 to the first optical element 200. Through two reflections, the size of the display device can be reduced without compressing the required object distance.

[0032] In one embodiment, as shown in FIG3, the projection surface 400 may include a first region 410 and a second region 420, wherein the second region 420 may be disposed on the side of the first region 410 near the first optical element 200. The first region 410 and the second region 420 respectively reflect the first image light L1 and the second image light L2 to form the first image P1 and the second image P2, and the reflectivity of the second region 420 is greater than that of the first region 410. The projection surface 400 may include a light-transmitting material, such as glass, and has the properties of partial transmission and partial reflection. The second region 420 may include an opaque coating disposed on the side of the second region 420 facing the display module 100 for reflecting the second image light L2. With this configuration, external light can be transmitted through the projection surface 400 and enter the virtual eye area 500, with its direction being the same as the direction in which the first image light L1 is reflected by the projection surface 400 to the virtual eye area 500, so that the external scene coincides with the first image P1, thereby achieving the effect of augmented reality (AR). Furthermore, for the first image ray L1t (see Figure 2) that is directly transmitted through the beam splitter 210 from the first display area 110, if it is incident on the first area 410 with a low reflectivity in the projection surface 400, the intensity of the reflected first image ray L1t may be insufficient to form a clear image (compared to the first image P1 focused by the reflector 300); if the first image ray L1t is incident on the second area 420, whether it will form an image in the virtual eye area 500 depends on its incident angle. In this embodiment, the first display area 110 is positioned above the second display area 120 in the cross-section shown in Figure 3. Therefore, the incident angle of the first image ray L1t (see Figure 2) that directly transmits through the beam splitter 210 and is incident on the second area 420 is different from the incident angle of the second image ray L2 (also see L2t shown in Figure 2), so that the imaging position of the first image ray L1t will not fall into the virtual eye area 500. In another embodiment (which will be described later), the first display area 110 may be located in different positions, such that the imaging position of the first image ray L1t that directly transmits through the beam splitter 210 and is incident on the second area 420 may fall into the virtual eye area 500.

[0033] Figures 4 and 5 illustrate embodiments of display devices with different projection surface angles of 400°. The spatial arrangement of the components in the display device is explained below with respect to the first image ray L1. For simplicity, the second image ray L2 is not shown in Figures 4 and 5. The virtual eye region 500 receives the first image ray L1 reflected from the projection surface 400 within a viewing angle range α. The viewing angle range α lies between a first direction D1 and a second direction D2, with the second direction D2 offset relative to the first direction D1 towards the first optical element 200. For example, the first direction D1 can be horizontal, and the second direction D2 can be offset downwards relative to the first direction D1. The angle between them (i.e., the viewing angle range α) can be, for example, greater than or equal to 0° and less than or equal to 20°. Based on the reversibility of light, imaginary rays can be emitted from the virtual eye region 500 along the first direction D1 and the second direction D2 respectively to perform reverse optical path tracing, thereby obtaining the optical path of the first image ray L1 in the display device and adjusting the spatial arrangement of the components accordingly. For example, the relative positions of the virtual eye area 500 and the projection surface 400 can be designed first. Since the imaginary light emitted from the virtual eye area 500 is reflected by the projection surface 400 and then passes through the first optical element 200 and enters the reflector 300, the spatial configuration of the first optical element 200 and the reflector 300 can be designed accordingly. Continuing to trace the light path of the imaginary light after being reflected by the reflector 300, it is reflected by the first optical element 200 to the first display area 110, and the spatial configuration of the first optical element 200 and the first display area 110 can be designed accordingly.

[0034] In the embodiment shown in Figure 4, at least a portion of the projection surface 400 may have an inclination angle β relative to the first direction D1. For example, when the projection surface 400 is curved (see Figure 3), the tangent plane at the position of the first image ray L1 incident on the projection surface 400 may have an inclination angle β relative to the first direction D1. The angle between the imaginary ray emitted along the first direction D1 and the projection surface 400 is equal to β; the angle between the imaginary ray emitted along the second direction D2 and the projection surface 400 is θ1, and the difference between these two angles (i.e., β – θ1) is equal to the angle between the first direction D1 and the second direction D2 (i.e., α), so θ1 = β – α. The angle between the reflected light of the imaginary ray emitted along the second direction D2 and the projection surface 400 is θ2. Since the angle of incidence equals the angle of reflection, the angle between the incident light and the reflecting surface is also equal to the angle between the reflected light and the reflecting surface, so θ2 = θ1. Another auxiliary line parallel to the first direction D1 is drawn, passing through the intersection of the second direction D2 and the projection surface 400. The angle θ3 between this auxiliary line and the projection surface 400 is equal to the angle between the first direction D1 and the projection surface 400 (i.e., the tilt angle β). The imaginary light emitted from the virtual eye zone 500 is reflected by the projection surface 400 and deflected towards the first optical element 200 and the reflector 300. This deflection angle is defined as the angle between the direction of the reflected light and the first direction D1 (e.g., the horizontal direction), which can be used to design the position of the reflector 300. For the imaginary light emitted along the first direction D1, its deflection angle is the sum of the angle between the reflected light and the projection surface 400 (equal to the angle between the incident light and the projection surface 400, hence equal to β) and the angle between the projection surface 400 and the first direction D1 (i.e., β), which is 2β. For the light path emitted along the second direction D2, its deflection angle is θ2 + θ3 = (β – α) + β = 2β – α. When the deflection angle is less than 90°, it means that the reflected light gradually moves away from the virtual eye area 500 along the first direction D1 as it travels towards the reflector 300, that is, the reflected light is deflected towards the front of the user. Correspondingly, the reflector 300 can be disposed on the opposite front side of the display device, that is, on the side of the display module 100 near the projection surface 400, as shown in Figure 4. In one embodiment, the reflector 300 can be disposed on the opposite front side of the display device based on the deflection angle (i.e., 2β – α) corresponding to the second direction D2 being less than or equal to 90°. Furthermore, in one embodiment, the viewing angle α of the virtual eye zone 500 can be 20° and the tilt angle β can be less than or equal to 55°. For example, a vehicle such as a small car can have a windshield with a relatively small angle to the horizontal direction and serve as a projection surface 400, which can correspond to the configuration of the reflector 300 located on the opposite front side of the display device.Furthermore, the reflective surface 310 of the reflector 300 can be deflected toward the virtual eye area 500, and the first optical element 200 can be deflected in the opposite direction relative to the reflective surface 310, so that the light path from the reflector 300 is reflected by the first optical element 200 to the first display area 110 located on the opposite rear side of the display device.

[0035] On the other hand, the embodiment shown in Figure 5 has a different spatial configuration than the embodiment shown in Figure 4. In the embodiment shown in Figure 5, the tilt angle β of the projection surface 400 is larger, and the horizontal position of the reflector 300 is closer to the virtual eye area 500. In terms of application, when the display device is installed in different types of vehicles and the windshield of the vehicle serves as the projection surface 400, vehicles such as trucks, buses, and motorboats can have windshields with a relatively large angle to the horizontal direction and serve as the projection surface 400, resulting in a larger tilt angle β of the projection surface 400. Referring to the angular relationship described above, when the deflection angle of the reflected light reflected by the projection surface 400 is greater than 90°, it means that the reflected light gradually approaches the virtual eye area 500 in the first direction D1 as it travels toward the reflector 300, that is, the reflected light is deflected toward the rear of the user. Correspondingly, the reflector 300 can be set on the opposite rear side of the display device, that is, on the side of the display module 100 away from the projection surface 400. In one embodiment, the reflector 300 can be positioned on the rear side of the display device based on a deflection angle (i.e., 2β – α) corresponding to the second direction D2 being greater than or equal to 90°. In another embodiment, the reflector 300 can be positioned on the rear side of the display device based on a deflection angle (i.e., 2β) corresponding to the first direction D1 being greater than or equal to 90°, i.e., a tilt angle β being greater than or equal to 45°. Furthermore, the reflective surface 310 of the reflector 300 can be deflected away from the virtual eye area 500, and the first optical element 200 can be deflected in the opposite direction relative to the reflective surface 310, so that the light path from the reflector 300 can be reflected by the first optical element 200 to the first display area 110 located on the front side of the display device.

[0036] In the foregoing embodiments, the range of deflection angles and their spatial arrangement with the reflector 300 are only one of the reference factors for the design of the display device, but are not limited thereto. The shape and position of other optical elements can also affect the design of the optical path.

[0037] Based on the relative position of the display module 100 and the projection surface 400, the imaging path of the second image ray L2 can be adjusted. Referring to Figure 3, the first area 410 and the second area 420 of the projection surface 400 reflect the first image ray L1 and the second image ray L2 to the virtual eye area 500, respectively. The tilt angles of the first area 410 and the second area 420 can be different; for example, the projection surface 400 can have curvature or can be spliced ​​together from planes with different tilt angles. Therefore, the tilt angle of the second area 420 can be adjusted according to the position of the second display area 120 so that the second image ray L2 emitted from the second display area 120 is reflected by the second area 420 and reaches the virtual eye area 500. Specifically, considering the line connecting the second display area 120 and the second area 420, and the line connecting the second area 420 and the virtual eye area 500, based on the fact that the angle of incidence equals the angle of reflection, the normal direction of the second area 420 can be designed to bisect the angle between the two lines so that the optical path of the second display ray L2 conforms to the two lines. In terms of application, if it is inconvenient to adjust the overall angle and curvature of the projection surface 400, for example, using a windshield with a specific configuration of the vehicle as the first area 410, an additional reflector can be set at a position adjacent to the windshield to serve as the second area 420. For example, the light-shielding element 700 shown in Figure 7A can also serve as the second area 420. On the other hand, the position of the second display area 120 can also be adjusted according to the tilt angle of the second area 420, and the second display area 120 and the first display area 110 are not limited to being adjacent or separated.

[0038] As shown in Figure 6, in one embodiment, the first optical element 200 further includes a polarizing film 220 disposed on the side of the first optical element 200 away from the display module 100. The polarizing film 220 may be designed to have different transmittance for light with different polarization directions, for example, transmitting S-polarized light (whose electric field direction is perpendicular to the plane formed by the incident light and the reflected light) and reflecting P-polarized light (whose electric field direction is parallel to the plane formed by the incident light and the reflected light). In one embodiment, the first image ray L1 and the second image ray L2 (see Figure 1) have the same first polarization direction (e.g., S-polarization), and the polarizing film 220 is configured to transmit light with the first polarization direction (e.g., S-polarization) and reflect light with a polarization direction perpendicular to the first polarization direction (e.g., P-polarization), so that the first image ray L1 and the second image ray L2 emitted by the display module 100 can penetrate the polarizing film 220, and their optical paths are substantially the same as when the polarizing film 220 is not disposed (e.g., the optical path shown in Figure 1). Furthermore, the polarizing film 220 has a transmittance of greater than or equal to 90% for light with a first polarization direction to maintain high imaging brightness. For external light EL (e.g., sunlight) from outside the projection surface 400 (i.e., the side away from the virtual eye area 500), if it is unpolarized light, it can be split into half S-polarized light and half P-polarized light. The polarizing film 220 can reduce the amount of external light EL incident on the display module by about half. In addition, the display device may further include a filter 600, which is disposed on the side of the display module 100 facing the first optical element 200. The filter 600 has a transmittance of greater than that of infrared light in the visible light wavelength range. For example, it can transmit visible light with wavelengths less than 750 nanometers and reflect infrared light with wavelengths greater than 750 nanometers, so that the first image light L1 and the second image light L2, which belong to the visible light wavelength range, can pass through the filter 600, while most of the infrared light in the external light EL (e.g., sunlight) is blocked by the filter 600.

[0039] Based on the reversibility of light, external light rays EL incident backward along the effective imaging light path of the first image ray L1 onto the projection surface 400 will sequentially pass through the first optical element 200, be reflected by the reflector 300, and then be reflected again by the first optical element 200 to reach the display module 100. Since the concave mirror of the reflector 300 has the function of converging light, the energy of the external light rays EL will be more concentrated after passing through the reflector 300. Therefore, the external light rays EL incident backward along the light path of the first image ray L1 can cause significant thermal damage to the display module 100. In this embodiment, after the external light rays EL (e.g., sunlight) penetrate the projection surface 400, they travel backward along the effective imaging light path of the first image ray L1. The process is as follows (omitting the light rays that leave the effective imaging light path due to reflection): partially transmitted through the polarizing film 220; partially transmitted through the beam splitter 210; reflected by the reflector 300, then partially reflected again through the beam splitter 210; partially transmitted through the filter 600, and finally reaching the display module 100. The beam splitter 210 provides partial transmission and partial reflection during the process. When the beam splitter 210 has a splitting ratio of 1, both the transmittance and reflectance are 50%, which reduces the energy of external light EL to 25% (i.e., 50% x 50%). Furthermore, based on the light transmittance of the polarizer 220 and the filter 600, the further attenuation of the external light EL energy can be calculated. This configuration reduces the energy of external light EL illuminating the display device, preventing heat damage to the display module 100 and thus affecting display function and device lifespan.

[0040] On the other hand, external light can also affect the user's view of the first image P1 and the second image P2. For example, sunlight reflected by the first optical element 200 and entering the virtual eye zone 500 can cause solar glare. As shown in Figures 7A and 7B, the display device may further include a light-shielding element 700 to block solar glare that may enter the virtual eye zone 500. When external light EL (e.g., sunlight) penetrates the projection surface 400 and enters the first optical element 200, some of the external light EL may be reflected by the first optical element 200 (e.g., partial reflection occurs on the beam splitter 210) and enter the virtual eye zone 500, or be reflected sequentially by the first optical element 200 and the projection surface 400 and enter the virtual eye zone 500. Based on the reversibility of light, an imaginary light ray M can be emitted from the virtual eye zone 500 toward the first optical element 200 or the projection surface 400 for reverse optical path tracing to determine the placement position of the light-shielding element 700. In the embodiment shown in Figure 7A, the tilt angle β of the projection surface 400 is relatively small (see Figure 4), and the first optical element 200 is designed as a curved surface that is recessed in a direction away from the projection surface 400. The end of the first optical element 200 near the virtual eye area 500 is bent away from the display module 100 so that imaginary light rays M from different positions of the virtual eye area 500 pointing towards the first optical element 200 are reflected and converged at the end of the projection surface 400 near the first optical element 200; at the same time, the imaginary light rays M emitted from the virtual eye area 500 toward the projection surface 400 are reflected sequentially by the projection surface 400 and the first optical element 200, and then incident on the end of the projection surface 400 near the first optical element 200. By means of reverse optical path tracing, an opaque light-blocking element 700 can be provided at the end of the projection surface 400 near the first optical element 200 without obstructing the view of the first image P1 (see Figure 1). As shown in Figure 7B, external light rays EL can penetrate the projection surface at various angles. Part of the external light rays EL is blocked by the light-shielding element 700, and another part of the external light rays EL is reflected by the first optical element 200 and then reflected by the projection surface 400 into the glare area G. The glare area G does not overlap with the virtual eye area 500. In one embodiment, the opaque second area 420 (see Figure 3) can also serve as the light-shielding element 700 to block the external light rays EL.

[0041] In the embodiments shown in Figures 8A and 8B, the tilt angle β of the projection surface 400 is relatively large (see Figure 5), and the light-shielding element 700 can be set at different positions to match the tilt angle of the projection surface 400. The reflective surface of the first optical element 200 is curved and faces the virtual eye area 500. When external light (e.g., sunlight) penetrates the projection surface 400 and enters the first optical element 200, some of the external light may be reflected by the first optical element 200 (e.g., partial reflection occurs on the beam splitter 210) and enter the virtual eye area 500. Another part of the external light EL can be reflected sequentially by the first optical element 200 and the projection surface 400 but will not enter the virtual eye area 500. As shown in Figure 8A, through reverse optical path tracing analysis, imaginary light rays M pointing from the virtual eye area 500 to different positions of the first optical element 200 are all reflected and converged at the end of the projection surface 400 away from the first optical element 200. An opaque light-shielding element 700 can be placed at this location without obstructing the view of the first image P1 (see Figure 1). As shown in Figure 8B, external light rays EL can penetrate the projection surface at various angles. Some external light rays EL are blocked by the light-shielding element 700, while another portion is reflected by the first optical element 200 and then reflected by the projection surface 400 into the glare area G. The glare area G does not overlap with the virtual eye area 500. With the aforementioned arrangement, the amount of external light rays EL reflected into the virtual eye area 500 can be reduced, thus preventing the user's vision from being affected by solar glare.

[0042] As shown in the embodiment of FIG9, the vehicle display system of the present invention can be installed in a vehicle such as an automobile and includes the aforementioned display device. The vehicle includes a windshield, which can serve as a projection surface 400 to reflect a first image ray L1 and a second image ray L2 to generate a first image P1 and a second image P2, respectively. As mentioned above, by designing the optical paths of the first image ray L1 and the second image ray L2 differently, the first image P1 and the second image P2 can have different imaging distances and magnifications. FIG9 shows the corresponding positions of the first image P1 and the second image P2 on the projection surface 400. The difference in imaging distance is not shown; please refer to FIG1 for comparison of their imaging distances. For example, the display device can be a head-up display (HUD) in a vehicle such as a car. The first image P1, with a longer imaging distance (distance between the image and the virtual eye zone 500) and a higher magnification, can be used to display information about changes in road conditions and is combined with the driver's main field of vision. For example, it can be a windshield-type head-up display (W-HUD) with an imaging distance of 2 to 3 meters or an augmented reality head-up display (AR-HUD) with an imaging distance of 10 meters or more. Its magnification can be 2 to 20 times, but is not limited to this. The second image P2, with a shorter imaging distance and a lower magnification, can be used to display information such as the car's instrument panel and is located at the lower part of the windshield (i.e., the second zone 420) to avoid obstructing the driver's view. Its magnification is related to the curvature of the projection surface 400, for example, but not limited to 1 to 2 times.

[0043] In one embodiment, as shown in FIG9, the first display area 110 and the second display area 120 are arranged adjacent to each other. The first display area 110 is located in front of the driver's seat, that is, between the driver's seat and the windshield, which serves as the projection surface 400, and the second display area 120 extends to the front of the passenger seat. A portion of the first image light L1r emitted from the first display area 110 is reflected by the first optical element 200 and the reflector 300 and then transmitted through the first optical element 200 to enter the first area 410 of the projection surface 400, forming the first image P1. On the other hand, at least a portion of the second image light L2d emitted from the second display area 120 is directly projected onto the projection surface 400 without passing through the first optical element 200, and together with another portion of the second image light L2t (transmitted through the first optical element 200), it constitutes the second image P2. Since the range of the second image P2 extends to the front of the passenger seat, its imaging position is not limited to the virtual eye area 500 corresponding to the driver's eyes, but can be expanded to correspond to the passenger's eyes in the passenger seat. Therefore, it can be used to display images other than driving-related information, such as in conjunction with the in-vehicle entertainment system.

[0044] The present invention has been described by the above embodiments; however, the above embodiments are for illustrative purposes only and not intended to be limiting. Depending on the design, some elements of one embodiment may be applied to other embodiments, but this is not a limitation. The scope of protection of the present invention shall be determined by the claims. Without departing from the spirit of the present invention, those skilled in the art can make various modifications and refinements without exceeding the scope defined by the appended claims.

[0045] 100: Display Module 110: First display area 120: Second display area 130: Light guide structure 200: First optical element 210: Spectrophotometer 220:Polarizing film 300: Reflector 310: Reflecting surface 400: Projection plane 410: District 1 420: Second District 500: Virtual Eye Zone 600: Filter 700: Light-shielding element D1: First Direction D2: Second Direction EL: External light G: Glare Zone L1, L1r, L1t: First image ray L2, L2d, L2t: Second image rays M: Imaginary light P1: First Image P2: Second Image P1': Secondary First Image α: Field of view β: Tilt angle θ1, θ2, θ3: included angles

Claims

1. A display device, comprising: A display module includes a first display area and a second display area, respectively used to emit a first image light and a second image light; a first optical element is disposed on the optical path of the first image light and the second image light and includes a beam splitter, wherein the beam splitter is disposed on the side of the first optical element facing the display module and configured to reflect at least a portion of the first image light and transmit at least a portion of the second image light; a reflector is disposed on the optical path of the first image light after being reflected by the beam splitter, the light reflected by the reflector has the same polarization direction as the original incident light, the reflector is configured to reflect the first image light reflected by the beam splitter to the first optical element, and at least a portion of the first image light reflected by the reflector is transmitted through the first optical element, wherein at least a portion of the first image light and at least a portion of the second image light transmitted through the first optical element generate a first image and a second image respectively in a virtual eye area.

2. The display device of claim 1, wherein the beam splitter has a beam splitting ratio defined as the energy ratio of transmitted light to reflected light, and the beam splitter has the same beam splitting ratio for light rays with different polarization directions.

3. The display device as requested in item 2, wherein the spectral ratio is greater than or equal to 0.9 and less than or equal to 1.

1.

4. The display device of claim 1, wherein the beam-splitting film is curved and protrudes toward the display module.

5. The display device of claim 1, wherein the first optical element further includes a polarizing film disposed on one side of the first optical element away from the display module, and the polarizing film has different transmittance for light with different polarization directions.

6. The display device of claim 5, wherein the first image light and the second image light have the same first polarization direction, and the polarizing film is configured to transmit light having the first polarization direction and reflect light having a polarization direction perpendicular to the first polarization direction.

7. The display device of claim 6, wherein the polarizing film has a transmittance of 90% or more for light having the first polarization direction.

8. The display device of claim 1, wherein the mirror has a reflective surface that is curved and recessed toward a direction away from the first optical element.

9. The display device of claim 1 further includes a filter disposed on one side of the display module facing the first optical element, and the filter has a transmittance in the visible light wavelength range greater than its transmittance in the infrared light wavelength range.

10. The display device of claim 1 further includes a projection surface disposed on the optical path after the first image ray and the second image ray have been transmitted through the first optical element, and the projection surface is configured to at least partially reflect the first image ray and the second image ray to generate the first image and the second image respectively.

11. The display device of claim 10, wherein the reflector is disposed on the side of the display module near the projection surface, the virtual eye area receives the first image light reflected from the projection surface in a viewing angle range (α), the viewing angle range (α) being between a first direction and a second direction, the second direction being offset toward the first optical element relative to the first direction, at least a portion of the projection surface having a tilt angle (β) relative to the first direction, and the viewing angle range (α) and the tilt angle (β) satisfying the following formula: the difference between twice the tilt angle (β) and the viewing angle range (α) is less than or equal to 90°.

12. The display device of claim 11, wherein the tilt angle (β) is less than or equal to 55°.

13. The display device of claim 10, wherein the reflector is disposed on the side of the display module away from the projection surface, the virtual eye area receives the first image light reflected from the projection surface in a viewing angle range (α), the viewing angle range (α) being between a first direction and a second direction, the second direction being offset toward the first optical element relative to the first direction, at least a portion of the projection surface having a tilt angle (β) relative to the first direction, and the viewing angle range (α) and the tilt angle (β) satisfying the following formula: the difference between twice the tilt angle (β) and the viewing angle range (α) is greater than or equal to 90°.

14. The display device of claim 13, wherein the tilt angle (β) is greater than or equal to 45°.

15. The display device of claim 10, wherein at least a portion of the second image light emitted from the second display area is projected directly onto the projection surface without passing through the beam splitter.

16. The display device of claim 10, wherein the projection surface includes a first area and a second area, the first area and the second area respectively reflecting the first image light and the second image light to form the first image and the second image, and the reflectivity of the second area is greater than that of the first area.

17. The display device of claim 16, wherein the projection surface comprises a light-transmitting material and the second region comprises an opaque coating disposed on the side of the second region facing the display module.

18. A vehicle display system disposed within a vehicle and including the display device described in any one of claims 1 to 17, the vehicle including a windshield, the windshield reflecting the first image light and the second image light to respectively generate the first image and the second image.

Images