Vehicle-mounted projection display device, vehicle-mounted projection display system, and vehicle

Abstract

The present application relates to a vehicle-mounted projection display device, a vehicle-mounted projection display system, and a vehicle. The vehicle-mounted projection display device comprises: a curved optical waveguide, mounted on a vehicle body; a projector, the projector being configured to project an image source light beam to the curved optical waveguide; an coupling-in holographic optical element, arranged at an coupling-in position of the curved optical waveguide; and a coupling-out holographic optical element, arranged at an optical coupling-out side of the curved optical waveguide. The coupling-in holographic optical element is configured to guide the propagation of the image source light beam coupled into the curved optical waveguide to a plurality of coupling-out positions at the optical coupling-out side, such that the size of a coupling-out light beam at each coupling-out position guided by the coupling-out holographic optical element at the coupling-out positions is within a preset size range, and the range of an eyebox imaged on the optical coupling-out side is within a preset eyebox range.

Description

Vehicle-mounted projection display device, vehicle-mounted projection display system and vehicle

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 2024113218291, filed on September 20, 2024, and entitled "Vehicle-mounted projection display device, vehicle-mounted projection display system and vehicle", the contents of which are hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the field of vehicle-mounted head-up display technology, and in particular to a vehicle-mounted projection display device, a vehicle-mounted projection display system and a vehicle. BACKGROUND

[0004] Based on the development of head-up display (HUD) technology, HUD has begun to be applied in some vehicles, so that the driver can obtain important information such as vehicle speed and navigation without lowering his head to look at the instrument panel, which brings convenience to the driver. At the same time, the clarity of the HUD display image and the miniaturization of the system structure are also important factors affecting the application of the HUD system. SUMMARY

[0005] Therefore, it is necessary to provide a vehicle-mounted projection display device, a vehicle-mounted projection display system and a vehicle capable of small volume and aberration-free projection image display to solve the above technical problems.

[0006] In a first aspect, a vehicle-mounted projection display device is provided, comprising:

[0007] a curved optical waveguide mounted on a vehicle body;

[0008] a projector configured to project an image source light beam to the curved optical waveguide;

[0009] a coupling-in holographic optical element arranged at a coupling-in position of the curved optical waveguide;

[0010] a coupling-out holographic optical element arranged at a light coupling-out side of the curved optical waveguide;

[0011] The coupling-in holographic optical element is configured to guide the image source light beam coupled into the curved optical waveguide to propagate to a plurality of coupling-out positions at the light coupling-out side, so that the size of the coupling-out light beam at each coupling-out position is within a preset size range and the eyebox range formed at the light coupling-out side is within a preset eyebox range after being guided by the coupling-out holographic optical element at the coupling-out position.

[0012] The vehicle-mounted projection display device provided by the embodiments of the present application utilizes the curved surface light waveguide and the in-coupling holographic optical element to realize pupil expansion, so that a smaller projector can be used and the overall space occupied by the vehicle-mounted projection display device is reduced. In addition, in view of the aberration problem caused by the curvature of the curved surface light waveguide, the in-coupling holographic optical element and the out-coupling holographic optical element have the guiding ability for light, so that the eyebox range formed on the light out-coupling side is within the preset eyebox range, and the size of the light beams coupled out at the plurality of out-coupling positions is within the preset size range, so as to ensure that the user can clearly see the image projected by the projector within the preset eyebox range, and the aberration problem is improved. Based on the cooperation of the holographic optical element and the curved surface light waveguide, the holographic optical element has a small volume and is integrated on the curved surface light waveguide, so that the volume of the vehicle-mounted projection display device can be reduced. On the other hand, the in-coupling holographic optical element and the out-coupling holographic optical element cooperate to segmentally guide the image source light beams coupled in and out of the curved surface light waveguide, so as to ensure that the projected image is clearly displayed within the preset eyebox range. That is, the vehicle-mounted projection display device provided by the embodiments of the present application can be miniaturized on the basis of clearly displaying the image projected by the projector within the preset eyebox range.

[0013] In a second aspect, a vehicle-mounted projection display system is provided, comprising:

[0014] a data acquisition terminal configured to acquire user interaction information and / or data information collected by a vehicle-mounted sensor; and

[0015] The vehicle-mounted projection display device, the projector in the vehicle-mounted projection display device is connected with the data acquisition terminal.

[0016] The vehicle-mounted projection display system utilizes the information acquisition capability of the data acquisition terminal and the holographic waveguide display capability of the vehicle-mounted projection display device, and can realize the projection display of the user interaction information and the data information, and the display content has no aberration. The vehicle-mounted projection display system has a small volume.

[0017] In a third aspect, a vehicle is provided, comprising the vehicle-mounted projection display device or the vehicle-mounted projection display system.

[0018] The vehicle carrying the vehicle-mounted projection display device or the vehicle-mounted projection display system can at least realize the aberration-free projection display of the image displayed by the projector under the design of a miniaturized product.

[0019] The details of one or more embodiments of the present application are presented in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the specification, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings needed to be used in the embodiments or the related art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0021] FIG. 1 is a structural schematic diagram of a vehicle-mounted projection display device and a vehicle-mounted projection display system according to some embodiments;

[0022] FIG. 2 is a schematic diagram of the propagation of an image source light beam after being incident on a curved optical waveguide without undergoing in-coupling and out-coupling correction according to some embodiments;

[0023] FIG. 3 is a structural schematic diagram of a vehicle-mounted projection display device and a schematic diagram of total reflection of an image source light beam according to some embodiments;

[0024] FIG. 4 is a structural schematic diagram of a vehicle-mounted projection display device according to some embodiments;

[0025] FIG. 5 is a schematic diagram of the relationship between the total reflection step size in the total reflection process of an image source light beam and the exit pupil size of the out-coupling holographic optical element at the out-coupling position according to some embodiments;

[0026] FIG. 6 is a schematic diagram of the relationship between multiple exit pupil positions within an eyebox range according to some embodiments;

[0027] FIG. 7 is a structural schematic diagram of a vehicle-mounted projection display device according to some embodiments;

[0028] FIG. 8 is a schematic diagram of the light beam distribution of a vehicle-mounted projection display device according to some embodiments;

[0029] FIG. 9 is a schematic diagram of the light beam distribution of a vehicle-mounted projection display device according to some embodiments;

[0030] FIG. 10 is a schematic diagram of an exposure implementation scheme of an in-coupling holographic optical element according to some embodiments;

[0031] FIG. 11 is a schematic diagram of the light beam divergence of an out-coupling holographic optical element before correction according to some embodiments;

[0032] FIG. 12 is a schematic diagram of an exposure scheme of an out-coupling holographic optical element according to some embodiments;

[0033] FIG. 13 is a structural schematic diagram of a vehicle-mounted projection display device according to some embodiments;

[0034] FIG. 14 is a structural schematic diagram of a vehicle-mounted curved glass according to some embodiments;

[0035] FIG. 15 is a structural schematic diagram of a vehicle-mounted projection display device, a vehicle-mounted projection display system according to some embodiments;

[0036] FIG. 16 is a structural schematic diagram of a vehicle according to some embodiments. DETAILED DESCRIPTION

[0037] For the purpose of promoting an understanding of the present application, the present application will now be described in greater detail with reference to the relevant drawings. Embodiments of the present application are shown in the drawings. However, the present application can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. It will be fully appreciated that the present application is applicable to other embodiments and can be practiced in a variety of ways.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0039] It should be understood that the terms “first”, “second”, etc. used in the present application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0040] It should be noted that when an element is considered to be “connected” to another element, it can be directly connected to the other element or connected to the other element through a central element. In addition, “connected” in the following embodiments should be understood as “electrically connected”, “communicatively connected” and the like if there is transmission of electrical signals or data between the connected objects.

[0041] As used herein, the singular forms “a”, “an” and “the” can also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise / comprising” or “have / having” specify the presence of stated features, integers, steps, operations, components, parts or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, components, parts or combinations thereof. At the same time, the term “and / or” used in the specification includes any and all combinations of the related listed items.

[0042] Based on the development of HUD technology, HUD has begun to be applied in some vehicles. In some related technologies, a planar substrate is installed on the center console, and the image source light beam projected by the projector is subjected to planar light waveguide processing, and then coupled out to the windshield to reflect the formed image by the windshield. However, the HUD system in the related technology has a large volume and generates geometric aberration.

[0043] In some embodiments of the present application, a vehicle-mounted projection display device 100 is provided, as shown in FIG. 1, comprising a projector 10, a curved light waveguide 20, a coupling-in holographic optical element 30, and a coupling-out holographic optical element 40.

[0044] The vehicle-mounted projection display device 100 can be applied to a vehicle, wherein the curved light waveguide 20 is mounted on the body 200 of the vehicle. The curved light waveguide 20 refers to a light waveguide component with curvature mounted on the vehicle.

[0045] The projector 10 is configured to project an image source light beam to the curved light waveguide 20. The projector 10 refers to a device capable of generating an image source light beam according to the image to be projected, which carries the information of the image, and the image source light beam can display the image on an imaging surface for a user to view. The projector 10 is configured to provide the field of view and pupil of the vehicle-mounted projection display device. The specific model of the projector 10 provided in the embodiments of the present application is not limited herein, and can be selected according to the requirements of the exit pupil size, cost, and the like.

[0046] The coupling-in holographic optical element 30 is arranged at the coupling-in position of the curved light waveguide 20, and the coupling-out holographic optical element 40 is arranged at the light coupling-out side of the curved light waveguide 20.

[0047] As shown in FIG. 2, the coupling-in holographic optical element 30 is configured to guide the image source light beam LS coupled into the curved light waveguide 20 to propagate to a plurality of coupling-out positions OC at the light coupling-out side, so as to be guided by the coupling-out holographic optical element 40 at the coupling-out position OC, and the size of the light beam coupled out at each coupling-out position OC is within a preset size range, and the eye box range imaged at the light coupling-out side is within a preset eye box range.

[0048] The "eye box" refers to the range of the area within which a user can clearly see the display content within the eye movement range. The preset size range is a range value determined based on the pupil size of the human eye. The preset eye box range is an eye box range determined based on the eye movement range of a person viewing the image projected by the projector in the vehicle. When the size of the light beam coupled out at each coupling-out position OC is within the preset size range, and the eye box range imaged at the light coupling-out side is within the preset eye box range, the image projected by the projector can be clearly observed by the human eye within the eye box range, and the problem of aberration is improved.

[0049] In some embodiments, the implementation of the in-coupling holographic optical element 30 guiding the propagation of the image source light beams coupled into the curved light waveguide 20 to a plurality of out-coupling positions OC on the light out-coupling side can be based on guiding the image source light beams to undergo total reflection in the curved light waveguide 20. As shown in FIG. 2, for the in-coupling position OR of the curved light waveguide 20, it can be understood that the image source light beams LS projected by the projector 10 are projected onto a region on the curved light waveguide 20. The in-coupling position depends on the angle of the light beams projected by the projector 10 and the relative position of the projector 10 and the curved light waveguide 20. The in-coupling holographic optical element 30 refers to an element capable of changing the propagation path of the image source light beams. The in-coupling holographic optical element 30 should be matched with the exit pupil size of the projector 10 to guide the propagation direction of all the light beams projected by the projector 10.

[0050] As shown in FIG. 2, without the in-coupling holographic optical element 30, the image source light beams LS projected by the projector are incident from the concave surface of the curved light waveguide 20. At this time, the curved surface of the curved light waveguide 20 is equivalent to a lens, and the focal length F = r / (n-1), where r is the radius of curvature at the point of incidence of the light beam, and n is the refractive index of the light waveguide. Therefore, the refractive interface of the in-coupling position OR has a certain diverging effect, which can cause aberration of the image source light beams. Therefore, in the embodiments of the present application, the in-coupling holographic optical element 30 is introduced, and based on the beam correction effect of the in-coupling holographic optical element 30, the image source light beams can propagate in a corrected light wave manner after being coupled into the curved light waveguide 20, which can keep consistent with the pupil size of the image source light beams LS projected by the projector 10, thereby reducing the aberration. In addition, the in-coupling holographic optical element 30 corrects the propagation path of the image source light beams, so that the incidence angle of the image source light beams is greater than the critical angle of total reflection when the image source light beams propagate to the convex surface of the curved light waveguide 20, and then the image source light beams undergo total reflection in the curved light waveguide 20 to achieve the purpose of pupil expansion. Using the pupil expansion technology, the eyebox size and the field of view can be separated, so that a smaller projector can be used in the same display field of view range, thereby reducing the overall occupied space of the vehicle-mounted projection display device.

[0051] In some embodiments, the propagation direction of the corrected image source light beam LS is adjusted for the in-coupling holographic optical element 30, so as to ensure that the image source light beam LS is totally reflected in the curved light waveguide 20. For example, the critical angle C of the total reflection of the image source light beam LS in the curved light waveguide 20 after being incident from the air to the curved light waveguide 20 satisfies the following relationship: C = arcsin(n / n1), n is the refractive index of the curved light waveguide 20, n1 is the refractive index of the air, and an angle greater than or equal to the critical angle can be taken. In an example, the refractive index of the curved light waveguide 20 can be 1.488, and the critical angle of total reflection is 43° according to the refraction law formula. Considering that the light has a certain divergence in the curved light waveguide, an incident angle of 50° can be taken. At this time, the in-coupling holographic optical element 30 corrects the incident image source light beam LS to a propagation direction with an incident angle of 50° to the convex surface of the curved light waveguide 20. When the refractive index of the curved light waveguide 20 is other values, the parameters of the in-coupling holographic optical element 30 can also be determined based on the above principle and the critical angle formula. The recording mode of the in-coupling holographic optical element 30 ensures that the light beam coupled into the curved light waveguide 20 matches the beam spot of the image source light beam LS projected by the projector 10, and the image remains unchanged.

[0052] As shown in FIG. 2, when the image source light beam is totally reflected and transmitted in the curved light waveguide 20, the image source light beam is equivalent to a process of being reflected by a curved mirror once when passing through each curved surface (including the inner surface and the outer surface). If the image source light beam LS is perpendicular to the curved surface, the focal length F = r / 2. Considering that the light is totally internally reflected at an angle θ in the curved light waveguide 20, the curved focal length at this time is F = r*cos(θ) / 2. Since the image source light beam is incident to the curved surface of the curved light waveguide 20 at an acute angle in the total reflection process, the focal length of the reflection will be shorter. With the increase of the number of total reflections, the aberration caused by the curved surface characteristics of the curved light waveguide 20 increases, and the pupil size (the out-pupil size corresponding to the out-coupling position OC) becomes smaller. Therefore, only the in-coupling holographic optical element 30 is arranged, and the image projected by the projector 10 cannot remain constant in size within the eyebox range. The vehicle-mounted projection display device provided in some embodiments of the present application further comprises an out-coupling holographic optical element 40 arranged on the light out-coupling side of the curved light waveguide 20. The out-coupling holographic optical element 40 is configured to correct the aberration of the light beams coupled out through the plurality of out-coupling positions OC. After being guided by the out-coupling holographic optical element, the size of the light beam coupled out at each out-coupling position is within a preset size range, and the eyebox range imaged on the light out-coupling side is within a preset eyebox range, so that the image source light beam is coupled out without aberration at the plurality of out-coupling positions OC.

[0053] The correction of the light path by the out-coupling holographic optical element 40 corrects the aberration caused by the curvature of the curved light waveguide 20 at the multiple out-coupling positions OC as shown in FIG. 3, so that the corrected image source light beam propagates in the desired light wave mode, and the beam spot size of the out-coupled light beam is consistent with the beam spot size of the image source light beam LS projected by the projector 10. Based on this, the image projected by the projector 10 remains constant in size within the eyebox range, so that the image can be clearly and aberration-free observed by the human eye within the eyebox range. The out-coupling position OC depends on various factors that affect the propagation of the light beam, such as the curvature and thickness of the curved light waveguide 20, the refractive index of the curved light waveguide 20, the angle at which the image source light beam undergoes total internal reflection within the curved light waveguide 20, etc. For a certain type of curved light waveguide 20, whose curvature, thickness, refractive index, etc. are determined, the parameters of the in-coupling holographic optical element 30 and the incident angle of the image source light beam LS projected by the projector 10 determine the total reflection angle, which in turn determines the out-coupling position OC.

[0054] The vehicle-mounted projection display device provided by the embodiments of the present application uses a curved light waveguide and an in-coupling holographic optical element to achieve pupil expansion, so that a small-sized projector can be used, thereby reducing the overall space occupied by the vehicle-mounted projection display device. Moreover, considering the aberration problem caused by the curvature of the curved light waveguide, the guiding ability of the in-coupling holographic optical element and the out-coupling holographic optical element for light waves makes the eyebox range formed on the light out-coupling side be within a preset eyebox range, and the size of the light beam coupled out at the multiple out-coupling positions be within a preset size range, so as to ensure that the user can clearly see the image projected by the projector within the preset eyebox range, and the aberration problem is improved. Based on the cooperation of the holographic optical element and the curved light waveguide, the volume of the holographic optical element is very small and integrated on the curved light waveguide, so the volume of the vehicle-mounted projection display device can be reduced. On the other hand, the cooperation of the in-coupling holographic optical element and the out-coupling holographic optical element guides the image source light beam coupled in and out of the curved light waveguide in segments, so as to ensure that the projected image is clearly displayed within the preset eyebox range. That is, the vehicle-mounted projection display device provided by the embodiments of the present application can be miniaturized on the basis of clearly displaying the image projected by the projector within the preset eyebox range.

[0055] In some embodiments, the out-coupling holographic optical element can be one, which can be integrally arranged on the curved light waveguide. However, the out-coupling holographic optical element in this case mainly emphasizes its correction effect on the light beam at the out-coupling position, and the characteristics at the non-out-coupling position are not limited herein. For example, the out-coupling holographic optical element can have a grating arrangement at the non-out-coupling position, or can be designed as a smooth surface.

[0056] In some embodiments, the preset size range is 2mm-8mm. That is, the preset size range can be any value interval between 2mm and 8mm, for example, 2mm-3mm, 3mm-4mm, 4mm-5mm, 6mm-7mm, 7mm-8mm, etc.

[0057] Under the guidance of the in-coupling holographic optical element and the out-coupling holographic optical element, the size of the light beam coupled out at each out-coupling position is 2mm-8mm, which matches the pupil size of the human eye, and can ensure that the user can observe a clear image within the eye movement range.

[0058] In some embodiments, the preset eyebox range in the first direction is 50mm-200mm, and the preset eyebox range in the second direction is 40mm-150mm. That is, the value of the preset eyebox range in the first direction can be any value interval between 50mm and 200mm, for example, 50mm-51mm, 100mm-110mm, 150mm-180mm, 180mm-200mm, etc. The value of the preset eyebox range in the second direction can be any value interval between 40mm and 150mm, for example, 40mm-50mm, 80mm-100mm, 140mm-150mm, etc.

[0059] In some embodiments, the first direction is the horizontal direction, and the second direction is the vertical direction. For example, the eyebox range in the first direction corresponds to the left-right eye movement range of the driver, and the eyebox range in the second direction corresponds to the up-down eye movement range of the driver.

[0060] Under the guidance of the in-coupling holographic optical element and the out-coupling holographic optical element, the eyebox range in the first direction on the light out-coupling side is 50mm-200mm, and the eyebox range in the second direction is 40mm-150mm, which can match the eye movement range of the user in the vehicle-mounted scene, and take into account the driving safety and large visual available area.

[0061] In some embodiments, the preset size range is 2mm-8mm, and the preset eyebox range in the first direction is 50mm-200mm, and the preset eyebox range in the second direction is 40mm-150mm.

[0062] Under the guidance of the in-coupling holographic optical element and the out-coupling holographic optical element, the size of the light beam coupled out at each out-coupling position is 2mm-8mm, which matches the pupil size of the human eye, and can ensure that the user can observe a clear image within the eye movement range. The eyebox range imaged in the first direction on the light out-coupling side is 50mm-200mm, and the eyebox range imaged in the second direction is 40mm-150mm, which can match the eye movement range of the user in the vehicle scene, and can balance the driving safety and the large visual available area. Based on the two, the user can always observe a clear image within the eye movement range in the vehicle scene.

[0063] In some embodiments, the preset eyebox range in the first direction is 80mm-135mm, and the preset eyebox range in the second direction is 50mm-95mm.

[0064] The size of the eyebox range and the pupil dilation are related, and together determine the visual experience and comfort of the user when using the vehicle-mounted projection display device. In theory, the better the pupil dilation, the wider the eye movement range (eye movement range) in which the user can maintain a high-quality visual experience. The vehicle-mounted projection display device provided by some embodiments of the present application can provide a larger visual available area by using a curved light waveguide to achieve pupil dilation without significantly increasing the physical volume of the device. However, the increase in the number of pupil dilation will reduce the brightness of the displayed image. In order to obtain higher image quality, the brightness requirement of the projector is increased, which increases the cost. Therefore, in some embodiments of the present application, the parameters of the in-coupling holographic optical element and the out-coupling holographic optical element are configured so that the eyebox range imaged in the first direction on the light out-coupling side is 80mm-135mm, and the eyebox range imaged in the second direction is 50mm-95mm. With this parameter setting, a projector with a luminous flux of 200lm-1000lm can be selected, which not only meets the eye movement range requirement of the driver under the driving safety condition, but also avoids increasing the cost of the projector and other hardware. That is, with this parameter setting, the clear display of the image within the preset eyebox range and the cost of the vehicle-mounted projection display device can be balanced.

[0065] In some embodiments, as shown in FIG. 3, the out-coupling holographic optical element 40 is a plurality of out-coupling holographic optical elements 40, and the plurality of out-coupling holographic optical elements 40 are respectively arranged at a plurality of out-coupling positions OC.

[0066] The coupling-out holographic optical element 40 can be disposed at the coupling-out positions OC of the curved surface light waveguide 20 based on the light beam propagation path of the image source light beam LS that is totally reflected in the curved surface light waveguide 20, to correct the curvature-induced aberration of the curved surface light waveguide 20, so that the pupil size of the image source light beam coupled out through each coupling-out position OC matches the beam spot of the image source light beam LS projected by the projector 10, thereby realizing that the image formed at each coupling-out position OC in the eyebox range matches the image projected by the projector 10 without distortion, ensuring the imaging quality. In some embodiments, the pupil size of the image source light beam coupled out through each coupling-out position OC is consistent with the size of the beam spot of the image source light beam LS projected by the projector 10, at which time the image formed at each coupling-out position OC is consistent in size with the image projected by the projector 10 and is clearly visible.

[0067] The vehicle-mounted projection display device provided by some embodiments of the present application can avoid laying a large area of coupling-out holographic optical elements by respectively disposing a plurality of coupling-out holographic optical elements at a plurality of coupling-out positions, which is conducive to reducing costs. In addition, the separate arrangement of the coupling-out holographic optical elements can facilitate the differentiated configuration of the parameters of the coupling-out holographic optical elements to accurately perform beam segmentation correction.

[0068] In some embodiments, as shown in FIG. 4, the vehicle-mounted projection display device further includes a pupil expansion holographic optical element 50.

[0069] The pupil expansion holographic optical element 50 is disposed on the curved surface light waveguide 20 and is configured to guide the image source light beam LS in the curved surface light waveguide 20 to propagate to a plurality of coupling-out positions OC in at least one direction.

[0070] Pupil expansion refers to expanding the range of the eyebox by duplicating the number of pupils. The pupil expansion holographic optical element 50 is an optical element made using holographic technology, which can introduce specific phase changes in the optical path to manipulate the light beam, thereby adjusting the size of the total light beam or changing the shape of the total light beam. By disposing the pupil expansion holographic optical element 50 on the image source light beam propagation path of the curved surface light waveguide 20, pupil expansion in at least one dimension can be realized, and the range of the eyebox can be increased.

[0071] For example, pupil expansion can include one-dimensional pupil expansion or two-dimensional pupil expansion. One-dimensional pupil expansion can be achieved by designing a hologram that contains information for dispersing the incident image source light beam LS in a certain direction when recorded. When the reproduction light is incident on such a hologram, it will reconstruct the dispersed light wavefront according to the phase information recorded by the hologram, thereby forming a wider total light beam in a specific direction.

[0072] Two-dimensional pupil expansion can increase the size of the light beam in two perpendicular directions at the same time. By precisely controlling the recording process of the hologram, so that the incident image source light beam LS is effectively dispersed in two directions, the replication of the pupil in two directions is realized, thereby forming a larger total light spot and increasing the eyebox range in two directions.

[0073] The vehicle-mounted projection display device provided by some embodiments of the present application adopts the in-coupling holographic optical element 30, the out-coupling holographic optical element 40, and the pupil-expanding holographic optical element 50, which are all holographic optical elements. The holographic optical element is thin and light, can cover a large area, is suitable for large-area laying in the scene of the windshield and the like, can realize a large eyebox range, and can be mass-produced using a roll-to-roll technology, which is beneficial to improving the production efficiency.

[0074] The in-coupling holographic optical element 30 and the out-coupling holographic optical element 40 not only couple the image source light beam into the curved optical waveguide 20, but also correct the image source light beam LS, so as to ensure that the beam spot of the internal propagation light beam after each total internal reflection does not become smaller or is close to constant. The thickness of the curved optical waveguide 20 and the size of the out-coupling holographic optical element 40 (i.e., the size of the exit pupil) depend on each other. A thicker curved optical waveguide 20 and a larger beam propagation angle correspond to a larger effective size of the out-coupling holographic optical element 40 (the effective size refers to the size of the part used for correcting the propagation direction of the light beam).

[0075] In some embodiments, as shown in FIGS. 5-6, the interval distance between the light beams coupled out by the adjacent two out-coupling positions OC is less than or equal to the size of the light beam coupled out by a single out-coupling position OC, and is greater than or equal to half of the size of the light beam coupled out by a single out-coupling position OC.

[0076] In some embodiments, the size of the out-coupled light beam refers to the diameter of the out-coupled light beam.

[0077] When the interval distance between the light beams coupled out by the adjacent two out-coupling positions is less than or equal to the size of the light beam coupled out by a single out-coupling position, the continuity of the exit pupil light beam can be ensured, and in this case, the image received by the human eye is still complete, but the energy of the overlapping part is superimposed. In view of this, the interval distance between the light beams coupled out by the adjacent two out-coupling positions is configured to be greater than or equal to half of the size of the light beam coupled out by a single out-coupling position, so as to avoid large-area pupil overlap, so that the energy of the entire exit pupil surface is relatively uniform, and the integrity of the exit pupil imaging and the display brightness uniformity are taken into account.

[0078] In some embodiments, the in-coupling holographic optical element 30 can guide the image source light beam to totally reflect in the curved light waveguide 20, and the interval distance between the light beams coupled out by two adjacent out-coupling positions is the total reflection step length L of the image source light beam in the curved light waveguide 20, and the size of the light beam coupled out by a single out-coupling position is the exit pupil size X of the out-coupling holographic optical element 40 at the out-coupling position. The two should satisfy the following relationship:

[0079] The total reflection step length L of the image source light beam in the curved light waveguide 20 is less than or equal to the exit pupil size X of the out-coupling holographic optical element 40 at the out-coupling position, and greater than or equal to half of the exit pupil size X of the out-coupling holographic optical element 40 at the out-coupling position.

[0080] The total reflection step length L of the image source light beam when totally reflecting in the curved light waveguide 20 is related to the light waveguide thickness T and the total reflection angle θ1, and tan(θ1) = L / 2T. As shown in FIG. 5, if the total reflection step length L is less than or equal to the single exit pupil size X, pupil overlap occurs, and at this time, the image received by the human eye is still complete, and thus X≥2T*tan(θ1). The total reflection angle θ1 is affected by the parameters of the in-coupling holographic optical element 30, and in the case of a certain thickness of the curved light waveguide 20, the size of the in-coupling holographic optical element 30 relative to the exit pupil size X and the total reflection step length L needs to be set.

[0081] As shown in FIG. 5, when the total reflection step length L is less than the exit pupil size X of the out-coupling holographic optical element 40 at the out-coupling position, the continuity of the image can be ensured, but the energy of the overlapping part is superimposed, and the energy distribution of the entire exit pupil surface is uneven. The vehicle-mounted projection display device provided in some embodiments of the present application can avoid large-area pupil overlap by restricting the size of the total reflection step length and configuring the total reflection step length to be greater than or equal to half of the exit pupil size of the out-coupling holographic optical element at the out-coupling position (X≤2L), so that the energy of the entire exit pupil surface is relatively uniform, and the integrity of the exit pupil surface imaging and the display brightness uniformity are taken into account.

[0082] In some embodiments, as shown in FIG. 7, the diffraction efficiency of the out-coupling holographic optical element 40 at the plurality of out-coupling positions OC gradually increases along the propagation direction F of the image source light beam LS in the curved light waveguide.

[0083] As shown in FIG. 7, the propagation direction of the image source light beam LS refers to the direction in which the image source light beam LS propagates on the plane where the curved light waveguide 20 is located. The image source light beam LS can propagate in at least one direction on the curved light waveguide 20 to couple out light beams at a plurality of out-coupling positions OC in the at least one direction, thereby expanding the eyebox range.

[0084] At the coupling-out position OC where the coupling-out holographic optical element 40 is located, the light beam undergoes multiple diffractions and reflections inside the curved optical waveguide 20. Assuming that the number of diffraction and reflection is n (n is greater than 1), if the diffraction efficiency of the coupling-out holographic optical element 40 is the same, the ratio of the exit light intensity after each diffraction to the incident light intensity of the same time is the same, but as the diffraction exit light consumes light intensity, the incident light intensity of each diffraction gradually decreases as n increases, thus causing the exit light intensity to decrease, the difference is large, and the uniformity is poor. Finally, the image received by the human eye is lengthened in the F direction, but the brightness is uneven, which causes visual fatigue. Therefore, the vehicle-mounted projection display device provided by some embodiments of the present application differentiates the diffraction efficiency of the coupling-out holographic optical element 40 along the propagation direction F of the image source light beam LS by segmenting, that is, the smaller the distance of the coupling-out holographic optical element 40 from the last coupling-out holographic optical element 40, the greater the diffraction efficiency. The diffraction efficiency of the coupling-out holographic optical element 40 at the last coupling-out position can be designed according to the required upper limit of brightness, and the diffraction efficiency of the coupling-out holographic optical element 40 at the last coupling-out position determines the upper limit of brightness of the entire exit pupil surface.

[0085] The vehicle-mounted projection display device provided by some embodiments of the present application takes into account the imaging integrity and the brightness uniformity of the exit pupil surface on the basis of restricting the total reflection step length L and the exit pupil size X. In addition, considering that in the case where the diffraction efficiency at each coupling-out position OC is the same, the incident light intensity of each diffraction gradually decreases along the propagation direction F of the image source light beam LS due to the consumption of light intensity by the diffraction exit light, thus causing the light intensity of each coupling-out to decrease, that is, the light intensity of the image source light beam LS propagating to the next coupling-out position OC is smaller than that of the image source light beam LS at the previous coupling-out position OC. By incrementally designing the diffraction efficiency of the coupling-out holographic optical element 40 at the multiple coupling-out positions OC, the coupling-out position OC reached first by the image source light beam LS can be prevented from consuming too much light intensity, and finally the display brightness of the exit pupil image can reach a certain uniformity, so that when the pupil of the human eye moves in a small range, the human eye will not feel obvious differences in image brightness.

[0086] In some embodiments, as shown in FIG. 7, the diffraction efficiency of the coupling-out holographic optical element 40 at the n th coupling-out position OC along the propagation direction F of the image source light beam LS satisfies the following relationship: η n = η1 / (1-(n-1)η1)

[0087] wherein η1 is the diffraction efficiency of the coupling-out holographic optical element at the first coupling-out position, η n is the diffraction efficiency of the coupling-out holographic optical element at the n th coupling-out position, and n is greater than or equal to 1.

[0088] Assuming that I n and ηn respectively, the light intensity after the n-th reflection of the image source light beam and the diffraction efficiency at the reflection position, and the relationship between the light intensity and the diffraction efficiency of the adjacent two light beams can be obtained as follows: n-1 / η n-1 -I n-1 )η n =I n

[0089] that is, I n = η n (1-η n-1 )*I n-1 / η n-1

[0090] The coefficient factor is η n (1-η n-1 ) / η n-1 When the coefficient factor is a constant 1, the uniformity of the light beam energy at any position can be ensured. By deducing the equation of the coefficient factor being 1 between the n-th position and the (n-1)-th position, the (n-1)-th position and the (n-2)-th position, the (n-2)-th position and the (n-3)-th position, and the (n-3)-th position and the (n-4)-th position, and so on, it can be determined that the diffraction efficiency of the (n-1)-th position and the first position satisfies the following relationship: η n = η1 / (1-(n-1)η1)

[0091] After the diffraction efficiency of the first position is determined, the diffraction efficiency of the coupling-out holographic optical element at other coupling-out positions can be designed according to the above expression. Based on this design, the coefficient factor of the light intensity of any coupling-out position and the light intensity of the first coupling-out position can be kept at 1, that is, the light intensity is consistent, thereby ensuring the uniformity of the light beam energy and making the brightness of the image seen by the user have high consistency.

[0092] For most holographic recording materials, within a certain exposure, the diffraction efficiency of the holographic optical element increases linearly with the increase of the exposure, and the curve tends to be flat when the exposure reaches a certain value. Therefore, the coupling-out holographic optical element provided in some embodiments of the present application can change its diffraction efficiency by changing its corresponding exposure. For example, the intensity of the interference light source can be changed, or the exposure time of the interference light source can be changed.

[0093] In some embodiments, the diffraction efficiency of the multiple coupling-out holographic optical elements in the F direction is realized by increasing the exposure time. For the coupling-out holographic optical element, two reference lights can be used for exposure. For example, two baffles can be placed in the two exposure light paths of the reference light 1 and the reference light 2, and the exposure time of the coupling-out holographic optical element at each coupling-out position can be changed by moving the baffles, so as to finally change the exposure of the holographic film.

[0094] The vehicle-mounted projection display device provided by some embodiments of the present application can improve the accuracy of the coupling-out position and angle control of the light beams, correct the accumulated aberration in the curved light waveguide, and provide a uniform and undistorted image in the entire field of view, by setting the coupling-in holographic optical element and the coupling-out holographic optical element and based on the segmented design of the coupling-out holographic optical element, each segment having different diffraction efficiency and functions.

[0095] In some embodiments, under the guidance of the coupling-out holographic optical element, the propagation direction of the light beams coupled out at each coupling-out position is parallel to the user observation direction.

[0096] As shown in FIG. 8, since the curved light waveguide has a certain curvature, when the coupling-out holographic optical element only corrects the aberration of the image source light beams, the coupled-out light beams propagate along the normal direction of the curved surface at the position, the eye movement range is greatly reduced, and as shown in FIG. 8, if the projector projects a smiling face image, the imaging on the exit pupil surface is also negatively affected, and the angle at which the user can view a clear image is limited. That is, under the influence of the curvature of the curved light waveguide, when the image source light beams are coupled out on the side away from the ambient light, they propagate towards the curvature radius of the curved light waveguide, greatly reducing the eye movement range. The vehicle-mounted projection display device provided by some embodiments of the present application corrects the coupling-out direction of the light beams at the coupling-out position through the coupling-out holographic optical element, so that the coupled-out light beams S are parallel to the user observation direction K (as shown in FIG. 9), thereby ensuring a large eye movement range.

[0097] In some embodiments, as shown in FIG. 10, the coupling-in holographic optical element is a holographic optical element made based on spherical wave (reference light 2) exposure, and the distance between the wave source of the spherical wave and the surface (convex surface) of the curved light waveguide 20 on the side away from the projector is equal to the off-axis focal length of the image source light beams at the coupling-in holographic optical element position.

[0098] The coupling-in holographic optical element is made by transmission exposure, and for example, when the propagation angle of the image source light beams in the curved light waveguide 20 is 50°, the corresponding off-axis focal length is 0.32r (r is the curvature radius of the curved light waveguide 20) in some embodiments. The exposure process is shown in FIG. 10, the reference light 1 is parallel light, and the reference light 2 is spherical wave. The perpendicular distance between the spherical wave and the convex surface of the curved light waveguide 20 is 0.32r, which can accurately correct the aberration caused by the curved waveguide. It should be noted that the example is intended to explain the process of correcting the aberration based on exposure of the coupling-in holographic optical element provided by the embodiments of the present application. When the propagation angle of the image source light beams in the curved light waveguide 20 is another angle, the corresponding off-axis focal length changes, and at this time, the perpendicular distance between the spherical wave and the upper surface of the curved light waveguide 20 also changes.

[0099] The vehicle-mounted projection display device provided by some embodiments of the present application has a coupling-in holographic optical element that provides off-axis aberration compensation at the coupling-in position, so that the image source light beams incident on the curved optical waveguide propagate in the curved optical waveguide in the expected direction, and the recording method of the coupling-in holographic optical element ensures that the spot of the internally propagating light beam after each total internal reflection is nearly constant, which is conducive to maintaining the image.

[0100] In some embodiments, the reference light 2 shown in FIG. 10 can also be a free-form wave with a certain focal length. Based on the coupling-in holographic optical element exposed by the free-form wave, the off-axis aberration caused by the curvature of the curved optical waveguide 20 can be compensated, so that the image source light beams projected by the projector propagate in the curved optical waveguide 20 in the expected light wave mode.

[0101] It should be noted that in the process of aberration correction of the coupling-out holographic optical element of the vehicle-mounted projection display device provided by some embodiments of the present application, in addition to considering the problem of pupil size reduction caused by total reflection, the dispersion of the exit pupil image caused by the change of refractive index and curvature at the coupling-out position is also considered (as shown by the light beam S in FIG. 11).

[0102] Based on the above, it can be known that the image divergence is caused by the refraction phenomenon at the coupling-out position, but different coupling-out positions will also produce off-axis aberration due to the off-axis light path. The degree of divergence and focusing of the parallel light when coupling out of the curved optical waveguide is F=r / (n-1), and when there is off-axis aberration, the off-axis focal length is F=r*cos(θ) / (n-1), as shown in FIG. 12. If the angle between the normal direction of the coupling-out holographic optical element and the normal direction of the center of the curved optical waveguide is θ, the object light direction when the coupling-out holographic optical element is exposed should be at an angle of -θ with the normal direction of the coupling-out holographic optical element (as shown in FIG. 12), that is, the object light is parallel to the line of sight, so as to avoid aberration.

[0103] In some embodiments, when the vehicle-mounted projection display device does not have the pupil expansion function, the user can only see the image within the eye movement range which is the same size as the exit pupil of the projector. Assuming that the exit pupil size of the projector is Then the user can only see the image within the eye movement range of At this time, the size of the coupling-in holographic optical element needs to be consistent with the size of the exit pupil of the projector, so as to realize efficient light flux and ensure that any position in the eyebox can view the projected image.

[0104] The efficient light flux also requires that the wavelength used by the projector matches the exposure wavelength of the coupling-in holographic optical element. In order to reduce chromatic aberration and increase diffraction efficiency, a multi-layer waveguide stack can be used to achieve full-color display. The coupling-in holographic optical element and the coupling-out holographic optical element of each layer are optimized for a specific color, thereby improving the color uniformity at the exit pupil position.

[0105] In some embodiments, the exit pupil size of the projector ranges from 2 mm to 8 mm, the size of the coupling-in holographic optical element ranges from 2 mm to 8 mm, and the size of the coupling-out position of the coupling-out holographic optical element ranges from 2 mm to 8 mm.

[0106] In order to balance imaging integrity and brightness uniformity, the size relationship between the full reflection step L and the exit pupil size X of the coupling-out position can satisfy the formula L≤X, X≤2L. The relationship between the full reflection step L and the curved light waveguide thickness T, full reflection angle θ is tan(θ)=L / 2T. Therefore, through calculation, in some embodiments, when the exit pupil size of the coupling-out position is 2 mm to 8 mm, the imaging integrity and brightness uniformity can be balanced for product applications with a curved light waveguide thickness of less than 3 mm.

[0107] In order to ensure the correction effect of the coupling-out holographic optical element, its size needs to match the exit pupil size of the coupling-out position. Therefore, the effective size of the coupling-out holographic optical element at the coupling-out position can be set to 2 mm to 8 mm. That is, the effective size of the coupling-out holographic optical element at the coupling-out position can be any value between 2 mm and 8 mm, such as 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, etc.

[0108] In addition, when the exit pupil size of the projector is 2 mm to 8 mm, which matches the average pupil size of the human eye, the projected image source light beam is projected onto the coupling-in holographic optical element with a size matching the image source light beam. After correction by the coupling-in holographic optical element, the parallel light is coupled into the curved light waveguide. The size of the parallel light is consistent with the beam spot size of the image source light beam projected by the projector. The light beam is totally reflected in the curved light waveguide. During the total reflection process, at the coupling-out position, based on the setting of the coupling-out holographic optical element, a light beam with a size of 2 mm to 8 mm is received, achieving complete reception of the light beam. The aberration of the light beam propagating to the coupling-out position is corrected, so that the size of the coupling-out light beam matches the exit pupil size of the projector. Based on the above size design, a clear image can be seen within the eye movement range of the human eye within a large eye box range.

[0109] The vehicle-mounted projection display device provided by some embodiments of the present application can match the size of the exit pupil of the projector by setting the size of the in-coupling holographic optical element and the size of the out-coupling position of the out-coupling holographic optical element to 2mm-8mm, so as to ensure that the effective correction area of the in-coupling holographic optical element and the out-coupling holographic optical element can completely cover the image source light beam emitted by the projector, thereby avoiding the decline of the imaging quality.

[0110] In some embodiments, the thickness of the curved optical waveguide is less than 3mm.

[0111] The thickness of the curved optical waveguide and the size of the exit pupil of the out-coupling holographic optical element at the out-coupling position are dependent on each other. In the design of a thicker curved optical waveguide, a larger size of the out-coupling holographic optical element needs to be set at the out-coupling position. For the vehicle-mounted projection display device, when the thickness of the curved optical waveguide is less than 3mm, the size of the out-coupling holographic optical element at the out-coupling position can be ensured without being too large, thereby reducing the cost.

[0112] In some embodiments, as shown in FIG. 13, the curved optical waveguide 20 is the front windshield of the vehicle.

[0113] The front windshield can be installed on the vehicle body 200. The image source light beam LS projected by the projector 10 is projected onto the front windshield near the side close to the vehicle cabin, coupled into the front windshield through the in-coupling holographic optical element, totally reflected in the front windshield, and coupled out as a light beam consistent with the image source light beam LS projected by the projector 10 through the out-coupling holographic optical element at the out-coupling position, so as to present the image projected by the projector 10 for the user to view. Based on the above embodiments, the image can be clearly displayed for the driver to view within a large eyebox range. Due to the increase of the eyebox range, more effective content can be displayed on the front windshield, such as the surrounding vehicle situation, the current vehicle speed, the distance to the navigation destination, the current speed limit information, etc. The content diversity of the displayed image is improved. It can be applied to the HUD, and more applicable to the AR-HUD (Augmented Reality Head-Up Display) and MR-HUD (Mixed Reality Head-Up Display) which have large image size. The field of view angle can be determined by the refractive index of the projector and the curved optical waveguide. Assuming that the refractive index of the front windshield is 1.5, the horizontal field of view angle can be greater than 14°, which fully meets the requirement of the field of view angle of the AR-HUD being greater than 10°.

[0114] The display of the image projected by the projector based on the front windshield of the vehicle is beneficial to providing the relevant image for the driver to assist the driving process during driving, and the driver does not need to lower his head to check the central control screen or mobile phone and other devices, thereby improving the driving safety.

[0115] In addition, since the front windshield has a certain reflection efficiency, the highest is not more than 25%, resulting in 75% energy loss, when the optical waveguide is integrated in the front windshield, the light utilization rate can be greatly improved, and the light efficiency can reduce and balance the rainbow problem caused by the grating.

[0116] In some embodiments, the curved light waveguide is provided on the front windshield.

[0117] The effect of assisting the driving process can be achieved by providing relevant images in front of the driver's seat by setting a curved light waveguide with the same curvature on the front windshield, thereby improving driving safety.

[0118] In some embodiments, the curved light waveguide 20 can be attached to the side of the front windshield close to the cabin, and the image source light beam LS projected by the projector 10 is projected onto the side of the curved light waveguide close to the cabin, coupled into the curved light waveguide through the in-coupling holographic optical element, totally reflected in the curved light waveguide, and coupled out through the out-coupling holographic optical element as a light beam consistent with the image source light beam LS projected by the projector 10, so as to present the image projected by the projector 10 for the user to view. Based on the above embodiments, the image can be clearly displayed in a large eyebox range for the driver to view. Due to the increase of the eyebox range, more effective content can be displayed on the curved light waveguide, such as the surrounding vehicle situation, the current vehicle speed, the distance to the navigation destination, the current speed limit information, etc. The content diversity of the displayed image is improved. It can be applied to HUD, and more suitable for AR-HUD (Augmented Reality Head-Up Display, augmented reality head-up display), MR-HUD (Mixed Reality Head-Up Display, mixed reality head-up display) and other image size large scenarios. The field of view angle can be determined by the refractive index of the projector and the curved light waveguide. Assuming that the refractive index of the curved light waveguide is 1.5, the horizontal field of view angle can be greater than 14°, which fully meets the requirement of the field of view angle of AR-HUD being greater than 10°.

[0119] In some embodiments, the in-coupling holographic optical element is disposed on the front windshield directly in front of the driver, and the eyebox vertical dimension is set to 150mm and the eyebox horizontal dimension is set to 100mm, taking into account the driving habits of different drivers, which can meet the requirement of the eyebox size of 130mm*50mm in the common AR-HUD scene, and there is even more eyebox range to display more image content. As introduced in the above embodiments, the thickness of the front windshield, the exit pupil size of the out-coupling holographic optical element, and the total internal reflection angle of the light in the front windshield are related. When the front windshield is 3mm and the total internal reflection angle is 50°, the effective exit pupil size of the out-coupling holographic optical element at the out-coupling position can be set to 8mm. At this time, the number of pupils can be calculated to be 312, and the more the number of pupils, the lower the exit pupil brightness is realized. The brightness of the projector can be increased to ensure the exit pupil brightness. The vehicle-mounted projection display device provided in some embodiments of the present application has an efficiency that is 80% higher and a volume that is 60% smaller than the light waveguide disposed in the center console in the traditional technology, that is, both the efficiency and the volume are significantly improved.

[0120] In some embodiments, the refractive indices of the curved light waveguide, the in-coupling holographic optical element, and the out-coupling holographic optical element are the same.

[0121] When the refractive indices of the curved light waveguide, the in-coupling holographic optical element, and the out-coupling holographic optical element are the same, or the angle change caused by the difference in refractive indices between the three is very small, when the image source light beam is perpendicular to the curved surface of the curved light waveguide, only the astigmatism or focusing caused by the surface curvature of the curved light waveguide needs to be considered. When the image source light beam propagates in the curved light waveguide, the curved surface can be similar to a cylindrical mirror, and the focal length is F=r / 2. Since the in-coupling angle is an acute angle and is off-axis reflection, the aberration correction of the in-coupling holographic optical element mainly considers the off-axis focal length aberration F=r*cos(θ) / 2, θ is the included angle between the image source light beam and the curved surface radius.

[0122] The refractive indices of the curved light waveguide, the in-coupling holographic optical element, and the out-coupling holographic optical element are the same, which can avoid the change in the angle of the light beam caused by the difference in the refractive indices of the three. At this time, when the light is perpendicular to the curved surface of the curved light waveguide, only the astigmatism or focusing caused by the surface curvature of the curved light waveguide needs to be considered, the off-axis focal length caused by the curvature can be quickly determined, and then the parameters of the in-coupling holographic optical element and the out-coupling holographic optical element can be designed based on the off-axis focal length, which is conducive to reducing the design cost.

[0123] In some embodiments, the curved light waveguide is glass with a sandwich layer.

[0124] In some embodiments, as shown in FIG. 14, the curved optical waveguide 20 comprises a first glass plate 21, a second glass plate 22, and a medium layer 23 sandwiched between the first glass plate 21 and the second glass plate 22.

[0125] In some embodiments, the medium layer 23 is a polyvinyl butyral (PVB) layer, which helps to keep the fragments together when the glass breaks, preventing splashing. In some embodiments, the refractive index of the PVB layer is the same as that of the first glass plate and the second glass plate, which can ensure the consistency of the refractive index of the curved glass on the vehicle.

[0126] In some embodiments, the thickness of the first glass plate 21 and the second glass plate 22 can be 2.0 mm, and the thickness of the PVB layer can be 0.76 mm, so that the total thickness of the curved optical waveguide reaches 4.76 mm. In some embodiments, the radius of curvature of the curved optical waveguide is greater than 2000 mm and less than 10000 mm.

[0127] In some embodiments, as shown in FIG. 1 and FIG. 15, a vehicle-mounted projection display system is provided, comprising a data acquisition terminal 300 and the vehicle-mounted projection display device 100 described above.

[0128] The data acquisition terminal 300 is configured to obtain user interaction information and / or data information collected by vehicle-mounted sensors. The projector in the vehicle-mounted projection display device 100 is connected with the data acquisition terminal 300.

[0129] The type of the data acquisition terminal 300 includes but is not limited to mobile terminals such as wearable devices, mobile phones, computers, etc., and user interaction information can be obtained based on these devices. The data acquisition terminal 300 can also include a vehicle-mounted controller, which is in communication connection with vehicle-mounted sensors to obtain data information collected by the vehicle-mounted sensors. The vehicle-mounted sensors include but are not limited to lidar, speed sensor, camera, etc. The vehicle-mounted controller supports processing of data information of the vehicle-mounted sensors to generate processed information. For example, based on data collected by the lidar, the vehicle-mounted controller can determine the distribution of vehicles around the vehicle body and generate a vehicle distribution map for projection display. For another example, the vehicle-mounted controller can determine the current speed of the vehicle according to data collected by the speed sensor and generate a speed prompt image for projection display. For another example, the vehicle-mounted controller can generate a picture of vehicle distribution on each lane based on data collected by the lidar and data collected by the camera, for projection display. The types of the data acquisition terminal 300 are not exhaustive. It should be understood that in the vehicle use scenario, information of interest to the user can be obtained through the data acquisition terminal 300.

[0130] The vehicle-mounted projection display device 100 is connected with the data acquisition terminal 300, the projector 10 can acquire data information such as a vehicle distribution map and a vehicle speed prompt image, and generate an image source light beam of a corresponding image, and project the image source light beam to the curved light waveguide, and based on the correction of the curved waveguide and the holographic optical element, the image display without aberration in a large eye box range is realized. That is, the vehicle-mounted projection display system provided by some embodiments of the present application can realize the projection display of user interaction information and data information by using the information acquisition capability of the data acquisition terminal 300 and the holographic waveguide display capability of the vehicle-mounted projection display device 100, and the display content is free of aberration. Since the holographic optical element (30 and 40) and the pupil expansion technology based on the curved light waveguide are adopted, the miniaturized design of the vehicle-mounted projection display system is facilitated on the premise of realizing clear image display in a large eye box range.

[0131] In some embodiments, as shown in FIG. 15, the vehicle-mounted projection display device 100 is connected with the data acquisition terminal 300 in a wired manner or in a wireless communication manner.

[0132] For the data acquisition terminal not integrated on the vehicle body, a wireless communication manner can be used to establish a connection with the projector. For example, when the data acquisition terminal is a mobile phone, the mobile phone can be connected with the projector in a Bluetooth or other wireless communication manner, so as to improve the user convenience.

[0133] For the data acquisition terminal integrated on the vehicle body, a wired connection manner can be used. For example, when the data acquisition terminal is a camera, the camera can be connected with the projector in a wired manner by wiring in the vehicle frame, so as to increase the connection reliability and stability.

[0134] In some embodiments, as shown in FIG. 16, a vehicle 1 is provided, and the vehicle includes the above-mentioned vehicle-mounted projection display device (not shown) or the above-mentioned vehicle-mounted projection display system (not shown).

[0135] The vehicle carrying the above-mentioned vehicle-mounted projection display device or the above-mentioned vehicle-mounted projection display system can at least realize the aberration-free projection display of the projector display image under the miniaturized product design.

[0136] In some embodiments, the projector is placed on the center console of the vehicle or the vehicle pillar close to the driver's seat. By placing the projector on the center console of the vehicle or hiding the projector in the vehicle pillar close to the driver's seat, the influence of the projector on the driver's field of view can be reduced.

[0137] In the description of the present specification, the description of the terms "some embodiments", "other embodiments", "ideal embodiments" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above-mentioned terms does not necessarily mean the same embodiment or example.

[0138] Any combination of the technical features in the above embodiments can be made. For the sake of brevity, the foregoing description has not described all possible combinations of the technical features in the above embodiments, however, as long as the combination of the technical features does not contradict, it should be considered within the scope of the present disclosure.

[0139] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A vehicle-mounted projection display device, comprising: a curved light waveguide mounted on a vehicle body; a projector configured to project an image source light beam into the curved light waveguide; an in-coupling holographic optical element disposed at an in-coupling position of the curved light waveguide; an out-coupling holographic optical element disposed at a light out-coupling side of the curved light waveguide; wherein the in-coupling holographic optical element is configured to guide the image source light beam coupled into the curved light waveguide to propagate to a plurality of out-coupling positions at the light out-coupling side, so that after being guided by the out-coupling holographic optical element at the out-coupling positions, a size of the light beam coupled out at each out-coupling position is within a preset size range, and an eyebox range imaged at the light out-coupling side is within a preset eyebox range.

2. The vehicle-mounted projection display device according to claim 1, wherein The preset size range is 2mm-8mm; and / or, The preset eyebox range in a first direction is 50mm-200mm, and the preset eyebox range in a second direction is 40mm-150mm.

3. The vehicle-mounted projection display apparatus according to claim 1 or 2, wherein The out-coupling holographic optical element is a plurality of out-coupling holographic optical elements, and each of the plurality of out-coupling holographic optical elements is disposed at a corresponding out-coupling position.

4. The vehicular projection display apparatus according to any one of claims 1-3, wherein, The vehicle-mounted projection display device further comprises: a pupil expansion holographic optical element disposed on the curved light waveguide, the pupil expansion holographic optical element being configured to guide the image source light beam in the curved light waveguide to propagate to a plurality of out-coupling positions in at least one direction.

5. The vehicular projection display apparatus according to any one of claims 1-4, wherein, After being guided by the in-coupling holographic optical element and the out-coupling holographic optical element, a spacing distance between light beams coupled out by two adjacent out-coupling positions is less than or equal to a size of a light beam coupled out by a single out-coupling position, and greater than or equal to half of the size of the light beam coupled out by the single out-coupling position.

6. The vehicle-mounted projection display device according to claim 3, wherein Along a propagation direction of the image source light beam in the curved light waveguide, diffraction efficiencies of the out-coupling holographic optical elements increase in sequence.

7. The vehicular projection display device according to claim 6, wherein The diffraction efficiency of the out-coupling holographic optical element along the n-th out-coupling location of the curved optical waveguide in the propagation direction of the image source light beam satisfies the following relationship: η n = η1 / (1-(n-1)η1) wherein η1is the diffraction efficiency of the out-coupling holographic optical element at the first out-coupling position, said η n is the diffraction efficiency of the out-coupling holographic optical element at the n-th out-coupling position, n being equal to or greater than 1.

8. The vehicular projection display apparatus according to any one of claims 1-7, wherein, After being guided by the out-coupling holographic optical element, a propagation direction of the light beam coupled out at each out-coupling position is parallel to a user observation direction.

9. The vehicular projection display apparatus according to any one of claims 1-8, wherein, The in-coupling holographic optical element is a holographic optical element made based on spherical wave exposure, and a distance between a wave source of the spherical wave and a surface of the curved light waveguide away from the projector is equal to an off-axis focal length of the image source light beam at the in-coupling holographic optical element position.

10. The vehicular projection display apparatus according to any one of claims 1-9, wherein, A size of the in-coupling holographic optical element, a size of the out-coupling position of the out-coupling holographic optical element, and an exit pupil size of the projector are consistent.

11. The vehicle-mounted projection display device according to claim 10, wherein The exit pupil size of the projector ranges from 2mm to 8mm, the size of the in-coupling holographic optical element ranges from 2mm to 8mm, and the size of the out-coupling position of the out-coupling holographic optical element ranges from 2mm to 8mm.

12. The vehicle-mounted projection display device according to claim 1, wherein, A thickness of the curved light waveguide is less than 3mm.

13. The vehicle-mounted projection display device according to claim 1, wherein, The curved light waveguide is a front windshield of a vehicle.

14. The vehicular projection display device according to claim 1, wherein, The curved light waveguide is disposed on a front windshield of a vehicle.

15. The vehicular projection display device according to claim 1, wherein The curved light waveguide, the in-coupling holographic optical element, and the out-coupling holographic optical element have the same refractive index.

16. A vehicle-mounted projection display system, comprising: a data acquisition terminal configured to acquire user interaction information, and / or data information collected by a vehicle-mounted sensor; The vehicle-mounted projection display device according to any one of claims 1-15, wherein a projector in the vehicle-mounted projection display device is connected with the data collection terminal.

17. A vehicle, wherein, The vehicle comprises the vehicle-mounted projection display device according to any one of claims 1-15.

18. A vehicle, wherein, The vehicle comprises the vehicle-mounted projection display system according to claim 17.

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