Projection apparatus, display device, means of transportation, and projection method

Abstract

A projection apparatus, a display device, a means of transportation, and a projection method are provided. The projection apparatus (100) includes an optical element. A picture generating unit (110) in the optical element emits a polarized beam onto a reflective polarizer (120). The polarized beam passes through the reflective polarizer (120), which selectively transmits light of different polarization states. After passing through the reflective polarizer (120), the polarized beam passes through a first polarization converter (140) to change its polarization state, is reflected by a curved mirror (130), passes through the first polarization converter (140), and changes its polarization state again. The polarized beam passes through the reflective polarizer (120) twice, resulting in different polarization states. The optical elements in the projection device (100) may selectively process polarized beams, and space may be reused by optical paths, resulting in a compact internal structure of the projection device (100) and effectively controlling the volume of the projection device (100).

Description

[Technical Field]

[0001] The present application relates to projection imaging technology, which is applied in the field of augmented reality technology for intelligent vehicles, and in particular to a projection apparatus, a display device, a means of transportation, and a projection method. [Background technology]

[0002] As the intelligent vehicle market develops, intelligent optical displays such as augmented reality head-up displays (AR-HUDs) are increasingly becoming a core component. AR-HUDs combine holographic augmented reality (AR) technology with head-up display (HUD) functions. The acquired image information is superimposed onto the real 3D environment ahead through computing processing, thereby integrating information such as distance, speed, and navigation into the real image the driver receives. The computing data is combined with the display scenario, resulting in richer and more intuitive digital information, which improves the driving experience and safety. AR-HUD technology is gradually being adopted in large, medium, and small passenger cars, commercial vehicles, construction vehicles, and other vehicles, and is widely used to comprehensively improve the performance and user experience of intelligent cockpits.

[0003] Currently, freeform solutions are being adopted in the mass production of in-vehicle AR-HUDs. Specifically, after the picture generation unit (PGU) generates a real-focus image, that real-focus image is then magnified by two or three freeform surfaces to form a virtual image that is more than 100 times larger. In AR-HUD technology, the field of view (FOV) and virtual image distance (VID) are important parameters that affect the imaging effect of AR-HUD display technology. A larger FOV and longer VID indicate a higher degree of integration between digital information and display scenarios, and a better driver experience.

[0004] As FOV and VID requirements increase, the volume of AR-HUD devices increases. For example, an AU-HUD device with a 15x5 square degree FOV and a 7.5-meter VID can have a volume of approximately 15 liters. An AU-HUD device with a 20x8 square degree FOV and a 20-meter VID increases its volume to approximately 25 liters. Because vehicle interior space is limited and most AR-HUD devices are currently located in the center console in front of the steering wheel, an increase in the volume of the AR-HUD device inevitably leads to an increase in the volume of the center console, thereby impacting the in-vehicle use of solutions with a wide field of view and long virtual image distance. Therefore, miniaturizing AR-HUD devices represents a breakthrough that resolves the tradeoff between improving the user experience through technology and in-vehicle requirements. Summary of the Invention

[0005] The present application discloses a projection apparatus, a vehicle, a display device, and a projection method. The present application provides a polarization component for changing the polarization state of a light beam, so that when the field of view and virtual image distance of the projection apparatus are increased, the volume of the projection apparatus can be correspondingly reduced. [Means for solving the problem]

[0006] According to a first aspect, an embodiment of the present application discloses a projection device including a picture generation unit, a reflective polarizer, a first curved mirror, and a first polarization converter, wherein the picture generation unit is configured to emit a polarized beam, the first polarization converter is located between the reflective polarizer and the first curved mirror and configured to transmit the polarized beam to change its polarization state, the first curved mirror is configured to reflect the polarized beam, and the polarized beam, after being emitted by the picture generation unit, propagates through the reflective polarizer to the first polarization converter, transmits through the first polarization converter to propagate to the first curved mirror, propagates through the first curved mirror to the first polarization converter, and transmits through the first polarization converter to propagate to the reflective polarizer. The picture generation unit is configured to emit the polarized beam. The polarized light beam is selectively transmitted and reflected by the reflective polarizer while passing back and forth between the reflective polarizer and the curved mirror based on the different responses of the reflective polarizer, the first polarization converter, and the curved mirror to the polarization state of the polarized light beam. Because the reflective polarizer is not required to avoid the light beam passing back and forth, the volume of the projection device is correspondingly reduced. As the FOV and VID of the projection device increase, the volume of the projection device can be effectively controlled so that it only increases slightly, remains unchanged, or decreases.

[0007]

[0013] Referring to the first aspect, in a possible implementation of the first aspect, the reflective polarizer is configured to transmit a polarized beam having a first polarization state and reflect a polarized beam having a second polarization state, the polarization states including linear polarization and circular polarization, the polarized beam having the first state including linear polarization and circular polarization, and the polarized beam having the second state including linear polarization and circular polarization. Based on the selective transmittance of the reflective polarizer for the polarized beams of different states, the reflective polarizer does not need to avoid the light beam passing back and forth, and the volume of the projection device is accordingly reduced.

[0008] Referring to the first aspect, in a possible implementation of the first aspect, the first curved mirror includes a first curved reflector, and the picture generating unit is located on a side of the reflective polarizer closer to the first curved reflector, the picture generating unit emits a polarized beam, the polarization state of the polarized beam is linearly polarized in a second state, the polarized beam is reflected by the reflective polarizer and propagates to a first polarization converter, the polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to circularly polarized in a second state, and passes through the first polarization converter to propagate to the first curved reflector, the polarized beam is reflected by the first curved reflector to convert the polarization state of the polarized beam to circularly polarized in a first state and propagates to the first polarization converter, the polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to linearly polarized in a first state, and passes through the first polarization converter to propagate to the reflective polarizer, and passes through the reflective polarizer. Corresponding parameters of the reflective polarizer, the curved mirror, and the first polarization converter are set so that the light beam can be first reflected by the reflective polarizer, and the reflected light beam changes its polarization state through the curved mirror and the first polarization converter before passing through the reflective polarizer. In this way, the reflective polarizer and the picture generating unit can be arranged vertically within the center console to reduce the lateral size of the projection device.

[0009] Referring to the first aspect, in a possible implementation of the first aspect, the first polarization converter includes a quarter-wave plate.

[0010] Referring to the first aspect, in a possible implementation of the first aspect, the first curved mirror includes a first curved reflector, and the picture generating unit is located on a side of the reflective polarizer closer to the first curved reflector, and the picture generating unit emits a polarized beam, and the polarization state of the polarized beam is linearly polarized in a second state, and the polarized beam passes through a first polarization converter to convert the polarization state of the polarized beam into circularly polarized in a second state, and is reflected by the reflective polarizer to convert the polarization state of the polarized beam into circularly polarized in a first state. The polarized beam is propagated to a first polarization converter, where it passes through the first polarization converter to convert the polarization state of the polarized beam to linearly polarized light of a first state, then propagated to a first curved reflector, where it is reflected by the first curved reflector, the polarized beam reflected by the first curved reflector is propagated to a first polarization converter, where it passes through the first polarization converter to convert the polarization state of the polarized beam to circularly polarized light of a first state, then propagated to a reflective polarizer, where it is transmitted through the reflective polarizer. Corresponding parameters of the reflective polarizer, the curved mirror, and the first polarization converter are set so that the reflective polarizer can reflect circularly polarized light of a second state and transmit circularly polarized light of the first state, and the projection device can be selected to transmit more states of polarized light.

[0011] Referring to the first aspect, in a possible implementation of the first aspect, the first curved mirror includes a free-form semi-transparent mirror, the picture generating unit is located on a side of the free-form semi-transparent mirror away from the reflective polarizer, the picture generating unit emits a polarized beam, and the polarization state of the polarized beam is a second state of linear polarization, the polarized beam is transmitted through the free-form semi-transparent mirror, the polarized beam transmitted through the free-form semi-transparent mirror is transmitted through a first polarization converter to convert the polarization state of the polarized beam into a second state of circular polarization, and is reflected by the reflective polarizer to generate a polarized beam. The polarized beam is transmitted through the first polarization converter to convert the polarization state of the polarized beam to a first state of circular polarization, and propagates to a first polarization converter. The polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to a first state of linear polarization, and propagates to a free-form semi-transparent mirror. The polarized beam is reflected by the free-form semi-transparent mirror. The polarized beam reflected by the free-form semi-transparent mirror propagates to a first polarization converter. The polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to a first state of circular polarization, and propagates through the first polarization converter to propagate to a reflective polarizer. The curved mirror includes a free-form semi-transparent mirror, and the curved mirror has selective transparency for the light beam of the polarization state. The curved mirror can be positioned so as not to avoid the incident light beam, thereby further reducing the volume of the projection device.

[0012] Referring to the first aspect, in a possible implementation of the first aspect, the first curved mirror includes a first curved reflector, and the picture generating unit is located on a side of the reflective polarizer away from the first curved reflector, and the picture generating unit emits a polarized beam, and the polarization state of the polarized beam is a second state of linear polarization, and the polarized beam transmits through the reflective polarizer, and the polarized beam transmitted through the reflective polarizer is propagated to a first polarization converter, and the polarized beam transmits through the first polarization converter to convert the polarized beam into a linear polarization. The light beam is then reflected by the first curved reflector to convert the polarization state of the polarized beam to a first state of circular polarization and transmitted through the first polarization converter to propagate to the first curved reflector. The polarized beam is then reflected by the first curved reflector to convert the polarization state of the polarized beam to a first state of circular polarization and transmitted through the first polarization converter. The polarized beam is then transmitted through the first polarization converter to convert the polarization state of the polarized beam to a first state of linear polarization and transmitted through the first polarization converter to propagate to the reflective polarizer. The polarized beam is then reflected back to the outside of the projection device via the reflective polarizer. The light beam first passes through the reflective polarizer, where the polarization state of the transmitted light beam is changed via the curved mirror and the first polarization converter. The light beam is then reflected back to the outside of the projection device via the reflective polarizer. The reflective polarizer is not required to avoid retroreflected light beams, effectively reducing the volume of the projection device.

[0013]

[0013] Referring to the first aspect, in a possible implementation of the first aspect, the projection device further includes a second polarization converter, the second polarization converter being located on a side of the reflective polarizer away from the first curved reflector, and the second polarization converter being configured to convert the polarized light beam emitted by the reflective polarizer from circularly polarized light to linearly polarized light. In this way, the projection device emits linearly polarized light, and the polarization type of the linearly polarized light matches the polarization type of the incident light beam emitted by the picture generating unit in the projection device.

[0014] Referring to the first aspect, in a possible implementation of the first aspect, the second polarization converter includes a quarter wave plate or a half wave plate.

[0015] Referring to the first aspect, in a possible implementation of the first aspect, the first polarization converter includes a quarter wave plate or a half wave plate.

[0016] Referring to the first aspect, in a possible implementation of the first aspect, the reflective polarizer includes a polarizing element, and the polarizing element includes at least one of a liquid crystal polarizer or a reflective polarizing film. Different states of circularly polarized light can be selectively transmitted by the liquid crystal polarizer through voltage control of a liquid crystal material and rotation of the liquid crystal.

[0017] Referring to the first aspect, in a possible implementation of the first aspect, the reflective polarizer further includes a substrate layer, and the polarizing element is attached to the substrate layer to hold the reflective polarizer within the projection device and avoid image shaking due to vibration of the reflective polarizer.

[0018] Referring to the first aspect, in a possible implementation of the first aspect, the projection device further includes a lens element, the lens element being located at the light beam output end of the projection device and configured to adjust the optical path of the output light beam. The lens element performs optical adjustment of the light beam emitted by the projection device to improve the optical quality of the entire architecture of the projection device and reduce the difficulty of designing and processing the free-form surface of the curved mirror. In addition, in existing manufacturing processes for projection devices, each module is manufactured in a standardized manner, and the processing parameters of the lens element may be designed to meet different optical requirements, such as different vehicle models, to meet multiple performance requirements of the projection device. This reduces the difficulty and cost of the overall development of the projection device.

[0019] The optical design of a projection device is determined or optimized based on performance indicators, material selection, test acceptance, tolerance control, processing and assembly, cost, etc. These factors must be considered throughout the process, from the beginning of product design to the end of product production, and throughout the device commissioning process in product application. In the entire process, especially for head-up display devices, the design parameters of the freeform mirror have a significant impact on the overall image quality of the product, and the parameter design and production of the freeform mirror place high demands on the process. According to an embodiment of the present application, for the same indicator achieved by the freeform mirror, adding lens elements means increasing the optimization dimension of the optical design. The imaging of the projection device can be optimized by adjusting the parameter design of the lens elements, reducing the requirements for the indicators of the freeform surface. In addition, changing the lens elements can meet the specific performance indicator requirements of the projection device, thereby eliminating the need to change the freeform surface, reducing the difficulty and complexity of optical system optimization.

[0020]

[0013] Referring to the first aspect, in a possible implementation of the first aspect, the projection device further includes a diffuser, the diffuser being located on the light-emitting side of the picture generation unit and configured to realize a projected image plane of the picture generation unit. The diffuser can receive a real image of the picture generation unit and perform light homogenization and optical stretch angle control on the image to provide a display surface for polarization and folding components within the projection device.

[0021]

[0013] Referring to the first aspect, in a possible implementation of the first aspect, the projection device further includes an anti-glare film configured to process polarized light beams to mitigate or prevent glare. The anti-glare film can change the center of symmetry of light reflection. When external sunlight enters the projection device through the windshield, the light reflected by the anti-glare film is outside the driver's visual range, for example, above the driver's eyes, and does not enter the driver's eyes, thereby avoiding dazzle.

[0022] According to a second aspect, an embodiment of the present application provides a display device including an imaging screen and a projection apparatus according to any one of the aforementioned implementations, wherein the imaging screen is configured to receive and image an outgoing light beam emitted by the projection apparatus.

[0023] Referring to the second aspect, in a possible implementation of the second aspect, the display device includes holographic glasses and / or a helmet.

[0024] According to a third aspect, an embodiment of the present application discloses a vehicle including a windshield and a projection or display device according to any one of the implementations described above, wherein the vehicle includes a projection medium configured to receive and image an outgoing light beam emitted by the projection device.

[0025] According to a fourth aspect, an embodiment of the present application discloses a projection method applied to a projection device, the projection device including a picture generation unit, a reflective polarizer, a first curved mirror, and a first polarization converter. The method includes:

[0026] The picture generating unit emits a polarized beam, which propagates through a reflective polarizer to a first polarization converter, transmits through the first polarization converter to propagate to a first curved mirror, propagates through the first curved mirror to the first polarization converter, transmits through the first polarization converter to propagate to a reflective polarizer, and is projected outside the projection device via the reflective polarizer.

[0027] It should be noted that some possible implementations of the second, third and fourth aspects of the present application have the same concept as some implementations of the first aspect. For the beneficial effects brought about by the implementations, please refer to the beneficial effects of the first aspect. Therefore, the details will not be described again.

[0028] The accompanying drawings used in the embodiments of the present application will now be described. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. [Figure 2] FIG. 10 is a diagram of the virtual image distance. [Figure 3] 1 is a diagram of an application scenario of a projection device in the field of vehicles according to an embodiment of the present application; [Figure 4] FIG. 2 is a diagram of an application scenario of the projection device in the field of vehicles from another perspective according to an embodiment of the present application; [Figure 5] 1 is a diagram of imaging in a vehicle field where a projection device projects an image onto the driver's eyes according to an embodiment of the present application; [Figure 6] 1 is a diagram of a light path of a projection device applied in the field of vehicles according to an embodiment of the present application; [Figure 7] 1 is a diagram of a light beam transmission of a projection device applied to a head-up display field according to an embodiment of the present application; [Figure 8] 1 is a diagram illustrating the change in polarization state of a light beam of a projection device according to an embodiment of the present application; [Figure 9] FIG. 10 is another light beam transmission diagram of a projection device applied to a head-up display field according to an embodiment of the present application. [Figure 10] 10 is another diagram of a change in the polarization state of a light beam of a projection device according to an embodiment of the present application; [Figure 11] FIG. 10 is another light beam transmission diagram of a projection device applied to a head-up display field according to an embodiment of the present application. [Figure 12] 10 is another diagram of a change in the polarization state of a light beam of a projection device according to an embodiment of the present application; [Figure 13] FIG. 10 is another light beam transmission diagram of a projection device applied to a head-up display field according to an embodiment of the present application. [Figure 14] 10 is another diagram of a change in the polarization state of a light beam of a projection device according to an embodiment of the present application; [Figure 15]1 is a diagram of an arrangement of lens elements in a projection apparatus according to an embodiment of the present application; [Figure 16] 1 is a diagram of a diffuser arrangement in a projection apparatus according to an embodiment of the present application; [Figure 17] 1 is a diagram of an arrangement of an anti-glare film in a projection device according to an embodiment of the present application. [Figure 18] FIG. 2 is a diagram of a processor arrangement in a projection device according to an embodiment of the present application. [Figure 19] 1 is a diagram of two curved mirrors in a projection device according to an embodiment of the present application; and [Figure 20] 1 is a diagram of the structure of a computing device according to one embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following describes embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. It should be noted that in the embodiments of the present application, terms such as "example" or "for example" are used to represent giving an example, an example, or an explanation. Any embodiment or design solution described as "example" or "for example" in the embodiments of the present application should not be described as being preferred or having more advantages than another embodiment or design method. Rather, the use of words such as "example" or "for example" is intended to present a relative concept in a concrete manner.

[0031] The term "comprises" used in the embodiments of this application should not be construed as being limited to the contents listed below, and does not exclude other elements. Thus, it should be construed as specifying the presence of a mentioned feature, whole, or component, but not excluding the presence or addition of one or more other features, wholes, or components and groups thereof.

[0032] In the embodiments of the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following items" or similar expressions means any combination of these items, including any combination of one item or more items. For example, at least one of a, b, or c can refer to a, b, c, (a and b), (a and c), (b and c), or (a, b, and c), where a, b, and c may be singular or plural. The term "and / or" describes an association between related objects and indicates that three relationships may exist. For example, A and / or B can refer to the following three cases: when only A is present, when both A and B are present, and when only B is present, and A and B may be singular or plural. The character " / " generally indicates an "or" relationship between related objects.

[0033] Additionally, unless otherwise stated, ordinal numbers such as "first" and "second" in the embodiments of the present application are intended to distinguish between multiple entities and are not intended to limit the order, chronology, priority, or importance of the multiple entities. For example, a first beam splitting device and a second beam splitting device are intended to distinguish between different beam splitting devices and do not indicate different structures, detection principles, importance, etc., of the two devices.

[0034] References herein to "one embodiment" or "one embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in one embodiment" throughout this specification do not necessarily refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure.

[0035] For ease of understanding, the following will first explain some terms in the embodiments of this application.

[0036] The field of view (FOV), also known as the angle of view, is the maximum three-dimensional angle from the edge of the displayed image to the image acquisition center. For example, in an optical measurement device, the center of the lens of the optical measurement device is the image acquisition center, and the object image measured by the optical measurement device can pass through the lens. In addition, the angle formed by the two edges of the maximum range presented through the lens is called the field of view. In addition, in a projection device, the angle between the two side edges of the image projected by the projection device to the imaging mechanism, which are usually the two most distant edge points, and the center point of the lens of the projection device is usually the field of view. In a head-up display field of view, the image acquisition center is the human pupil. In a projection field of view, the FOV generally includes a vertical field of view, a horizontal field of view, and a diagonal field of view. As shown in Figure 1, point O in Figure 1 is the image acquisition center, the rectangle bounded by ABCD is the projected image, the angle between the OA connecting line and the OB connecting line is the horizontal field of view, the angle between the OB connecting line and the OC connecting line is the vertical field of view, and the angle between the OA connecting line and the OC connecting line can be the diagonal field of view. Unless otherwise specified, the default field of view generally includes the horizontal field of view and the vertical field of view.

[0037] Virtual Image Distance (VID) refers to the distance from the projected virtual image to the image acquisition center. In a head-up display field, the image acquisition center is the human pupil. As shown in Figure 2, in a head-up display system, the virtual image distance is the linear distance from the human pupil to the virtual image.

[0038] FIG. 3 is a diagram illustrating an application scenario of the projection device 100 in a vehicle field according to an embodiment of the present application. FIG. 4 is a diagram illustrating an application scenario of the projection device 100 in a vehicle field from another perspective according to an embodiment of the present application. FIG. 5 is an imaging diagram of the projection device 100 in a vehicle field according to an embodiment of the present application, in which the projection device 100 projects an image to the driver's eyes. The imaging diagram illustrates virtual image information that the driver can see when the projection device 100 of FIGS. 3 and 4 projects an image to the driver's eyes. When the driver looks outside the vehicle through the windshield 200, they can see a virtual image with a specific depth of field (i.e., the distance at which a clear image is presented in the range before and after the focus of the image). Information about the area ahead of the vehicle is acquired through an information acquisition module such as a camera and an infrared sensor. The information about the road ahead includes the distance to the vehicle ahead, the speed of the vehicle ahead, road information, etc., and corresponding digital information is projected by imaging so as to be closely combined with the environmental information of the vehicle ahead. The digital information includes vehicle speed, navigation information (road display), vehicle gear, cruise control, distance to the vehicle ahead, the speed of the vehicle ahead, rotational speed information, charge status information, range information, audiovisual entertainment system information, etc. In this way, the driver can obtain the information necessary for driving the vehicle 1 without looking away from the vehicle. This avoids driving risks that may arise from the driver not being able to consider road conditions while driving the vehicle 1, for example, by looking down to view information on the dashboard or central control screen. To implement the above-mentioned projection, the vehicle must have a head-up display (HUD) system. The extended head-up display system may include a projection device 100 and an optical element. The projection device 100 may project an image, and the optical element may include the vehicle's windshield 200, a reflective film attached to the windshield 200, or a screen separately disposed in the vehicle's cockpit. The optical element can reflect and / or refract the image projected by the projection device 100 and then project the image into the driver's eyes, so that the driver can see a virtual information image in front of the windshield 200.

[0039] The head-up display field of view may be 15 x 5 square degrees. The 15 degrees may be the horizontal field of view, which may be the angle between the OA and OB connecting lines, as shown in Figure 1. The 5 degrees may be the vertical field of view, which may be the angle between the OB and OC connecting lines. Generally, the size of a human retina is limited. The FOV of each human eye is usually 90 to 120 degrees (which may be horizontal or vertical), and the 3D state of an object can be perceived through the human eye based on the disparity between the two eyes. By increasing the FOV, the projection device can improve the fit between the virtual image and the real image, increase the coverage area of ​​the virtual image, and correspondingly improve the driver's visual experience.

[0040] In a head-up display field, the VID may be 7.5 meters. As shown in Figure 2, the VID can be the distance between the front of the vehicle and the driver's eyes. Increasing the corresponding VID of the projection device can increase the depth of the virtual image relative to the driver's field of view, resulting in a better fit between the virtual image and the distant real image and a more realistic three-dimensional effect of the virtual image. In addition, increasing the VID reduces the driver's need to frequently change the focal length when viewing the displayed image information or virtual image information, thereby improving the driver's eye comfort and correspondingly improving driving safety.

[0041] FIG. 6 is a diagram of the optical path of a projection device 100 applied to a vehicle. The picture generation unit 110 emits a light beam toward the reflector 190. The cross-sectional area of ​​the light beam emitted by the picture generation unit 110 gradually increases, and the light beam is reflected by the reflector 190 and expanded to the first curved mirror 130. The first curved mirror 130 reflects the light beam toward the windshield 200, through which it is reflected to the driver's eyes. The first curved mirror 130 selects parameters based on the internal structure, installation position, and shape of the display area of ​​the windshield of the projection device 100 to correct and compensate for optical distortions caused by different curvatures and optical path lengths in different projection areas of the windshield.

[0042] When the FOV of the projection device 100 is increased, the optical path transmission distance within the projection device 100 must be increased to increase the magnification factor. This increases the size of the light beam reflected by the reflector 190 and the first curved mirror 130, and the size of the reflector 190 and the first curved mirror 130 must also be increased accordingly. When the VID of the projection device 100 is increased while maintaining image quality, the optical path transmission distance within the projection device 100 must also be increased. Regardless of whether the FOV or VID is increased, the volume of the projection device 100 increases. For example, a projection device 100 with an FOV of 15×5 square degrees and a VID of 7.5 meters often has a volume of around 15 liters. A projection device 100 with an FOV of 20×8 square degrees and a VID of 20 meters may have a volume of 25 liters, nearly doubling the volume.

[0043] In the field of vehicles, a projection device 100 for realizing an extended head-up display function is mostly placed in the center console of the vehicle. As shown in FIGS. 3 and 4, the projection device 100 may be placed in the center console, located in front of the steering wheel (corresponding to the front of the vehicle in the direction of travel). The center console has many components, and the overall size of the center console is limited. Therefore, a projection device 100 with a large volume is not suitable for placement in the center console. Due to the volume limitation, the FOV and VID within the current head-up display field cannot reach a wide range, which affects the imaging quality.

[0044] It should be noted that in the embodiments of the present application, an example in which the vehicle is an automobile is used for explanation purposes, and this should not be considered a limitation on the embodiments of the present application. The vehicle may be a conventional fuel vehicle or a new energy vehicle, for example, a pure electric vehicle or a hybrid vehicle. The vehicle may be any one of different types of vehicles, such as a car, a truck, a passenger bus, and a sport utility vehicle (SUV), or may be a land transportation device for transporting people or goods, such as a tricycle, a motorcycle, or a train. Alternatively, the projection device in the embodiments of the present application may also be used in another type of transportation means, such as an airplane or a ship.

[0045] To solve the problem of the increased volume of the projection device 100 and the difficulty of installing the projection device 100 in a vehicle due to the increased FOV and VID, an embodiment of the present application provides a projection device. As shown in FIGS. 7 and 8, the projection device 100 includes a picture generation unit 110, a reflective polarizer 120, a first curved mirror 130, and a first polarization converter 140. The first curved mirror 130 may be a spherical mirror, an aspherical mirror, or a freeform mirror. The first curved mirror 130 has a reflective function and can reflect all polarized light beams or a portion of the polarized light beams. In this implementation, for example, the first curved mirror 130 is a freeform mirror.

[0046] The picture generation unit 110 emits a light beam to the reflective polarizer 120, where the light beam is a polarized beam, which includes multiple states of, for example, linear and circular polarization.

[0047] Linear polarization means that the light vector vibrates only in a certain direction, and the vibration of the light vector is on a plane in the direction of light propagation. For example, linear polarization in a first state and linear polarization in a second state have different polarization forms. The vibration directions of the linear polarization in the first state and the linear polarization in the second state are different. For example, the linear polarization in the first state may be P linear polarization, and the linear polarization in the second state may be S linear polarization, with the vibration direction of the P linear polarization being perpendicular to the vibration direction of the S linear polarization. It should be understood that this implementation form is intended merely to distinguish between different forms of linear polarization, and that the terms "first" and "second" do not limit the form of linear polarization. The linear polarization in the first state may alternatively be S linear polarization, and the linear polarization in the second state may alternatively be P linear polarization.

[0048] Circularly polarized light is light whose electric vector traces a circular path in the light beam transmission direction. For example, circularly polarized light has different polarization forms between a first state and a second state. The rotation directions of the first state and the second state circularly polarized light are different. For example, the first state circularly polarized light may be right-handed circularly polarized light, and the second state circularly polarized light may be left-handed circularly polarized light. Circularly polarized light whose electric vector rotates clockwise in the light direction is called right-handed circularly polarized light, and circularly polarized light whose electric vector rotates counterclockwise is called left-handed circularly polarized light. It should be understood that this implementation is intended merely to distinguish between different forms of circularly polarized light, and that the terms "first" and "second" do not limit the form of circular polarization. The first state circularly polarized light may alternatively be left-handed circularly polarized light, and the second state circularly polarized light may alternatively be right-handed circularly polarized light.

[0049] The light beam emitted by the picture generating unit 110 passes back and forth between the reflective polarizer 120 and the first curved mirror 130, and the first polarization converter 140 is located between the reflective polarizer 120 and the first curved mirror 130. The light beam that passes back and forth between the reflective polarizer 120 and the first curved mirror 130 may then pass through the first polarization converter 140. The first polarization converter 140 may convert the polarization state of the transmitted light beam, for example, convert linearly polarized light to circularly polarized light, or convert circularly polarized light to linearly polarized light.

[0050] The picture generation unit 110 is a real picture generation unit, and mainly includes a microdisplay (LCoS, DLP, LBS, Micro LED, etc.), an illumination light source and system (the illumination light source may be an LED or a laser, or a combination thereof), an imaging lens unit, etc.

[0051] The reflective polarizer 120 is a polarization device with selective transmittance based on the polarization state. The reflective polarizer 120 may transmit light polarized in a first state and reflect light polarized in a second state. For example, the polarization direction of the reflective polarizer 120 corresponds to the vibration direction of P linearly polarized light. When the light beam emitted by the picture generating unit 110 is S linearly polarized light, the S linearly polarized light is reflected by the reflective polarizer 120 and converted to circularly polarized light by the first polarization converter 140. The first curved mirror 130 may reflect the circularly polarized light and change the rotation direction of the circularly polarized light. The light beam may be converted to P linearly polarized light when passing through the first polarization converter 140 again. In this case, the P linearly polarized light may be transmitted through the reflective polarizer 120 or transmitted to the outside of the projection device 100 via the reflective polarizer 120.

[0052] Alternatively, the polarization direction of the reflective polarizer 120 coincides with the vibration direction of the S-linearly polarized light. When the light beam emitted by the picture generating unit 110 is S-linearly polarized light, the S-linearly polarized light passes through the reflective polarizer 120 and is converted to circularly polarized light by the first polarization converter 140. The first curved mirror 130 may reflect the circularly polarized light and change the rotation direction of the circularly polarized light. The light beam may be converted to P-linearly polarized light when passing through the first polarization converter 140 again. In this case, the P-linearly polarized light is reflected by the reflective polarizer 120 and transmitted to the outside of the projection device 100. In this embodiment, increasing the FOV and VID based on the selective transmission of the polarization state of the reflective polarizer 120 and controlling the increase in the overall volume of the projection device 100 are described as only two methods. There is no limitation in implementing this application using only the above two methods. Other implementations are described below.

[0053] The reflective polarizer 120 described in the embodiments of the present application includes a polarizing element. The polarizing element may be a reflective polarizing film. The reflective polarizing film has selective transmission based on the polarization state, and the first polarization converter 140 changes the polarization state of the light emitted by the picture generating unit 110. When the light beam incident on the first curved mirror 130 is circularly polarized, the first curved mirror 130 may change the polarization form of the circularly polarized light. Using the combination of the first polarization converter 140 and the first curved mirror 130, the polarization state and form between the reflective polarizer 120 and the first curved mirror 130 are converted. When a light beam with a different polarization state is transmitted through the reflective polarizer 120, the first polarization state can be transmitted through the reflective polarizer 120, and the second polarization state can be reflected by the reflective polarizer 120. When the optical path of the projection device 100 is designed, the reflective polarizer 120 does not need to avoid the round-trip transmitted light beam, and the round-trip transmitted light beam is the light beam between the reflective polarizer 120 and the first curved mirror 130.

[0054] As the FOV and VID of the projection device 100 increase, the areas of the reflective polarizer 120 and the first curved mirror 130 increase accordingly, and the light beam transmission distance also increases accordingly (the spacing between the picture generating unit 110, the reflective polarizer 120, and the first curved mirror 130 increases). The reflective polarizer 120 does not need to avoid the light beam traveling back and forth to balance the increase in volume of the projection device 100 due to the increase in the areas of the reflective polarizer 120 and the first curved mirror 130 and the increase in volume of the projection device 100 due to the increase in the light beam transmission distance. In this way, the projection device 100 may have a slight increase in volume, remain unchanged, or decrease in volume.

[0055] In one possible implementation, see Figures 7 and 8. Figure 7 is a diagram of the light beam transmission of the projection device 100 applied to a head-up display field in this implementation. Figure 8 is a diagram of the change in the light beam polarization state of the projection device 100 in this implementation.

[0056] The picture generation unit 110 is located below the reflective polarizer 120. Below refers to the direction corresponding to when the vehicle is in normal driving mode. The projection device 100 is integrated into the center console, which is located below the windshield 200. Below in FIG. 7 is the Y direction, which corresponds to the downward direction when the vehicle is driving. The right side in FIG. 7 is the X direction, which corresponds to the rear side when the vehicle is driving. As shown in FIG. 7, the picture generation unit 110 is located in the Y direction of the reflective polarizer 120 and shifted in the X direction. The picture generation unit 110 emits an incident light beam 111 toward the reflective polarizer 120. The incident light beam 111 is a light beam emitted by the picture generation unit 110 and first encounters the reflective polarizer 120. The incident light beam 111 is linearly polarized light in a second state.

[0057] In this implementation, the second state of linear polarization is S-linear polarization, as shown in FIG. 8 , for example. In FIG. 8 , a double-headed arrow slanting from the upper right to the lower left indicates S-linear polarization, and an incident light beam 111 of S-linear polarization is reflected by the reflective polarizer 120 to form a first retroreflected light beam 112. The first retroreflected light beam 112 is S-linearly polarized and is converted to a second state of circular polarization after passing through the first polarization converter 140. In this implementation, for example, the second state of circular polarization is left-handed circular polarization. In FIG. 8 , a counterclockwise arc-shaped arrow indicates left-handed circular polarization, and the first retroreflected light beam 112 of left-handed circular polarization is reflected by the first curved reflector 131 to form a second retroreflected light beam 113.

[0058] As shown in Figure 7, a portion of the light beam processed by the optical element passes through the reflective polarizer 120 again, and a portion of the light beam does not pass through the reflective polarizer 120. Alternatively, as shown in Figure 8, all of the processed light beam may pass through the reflective polarizer 120 again. The amount of the processed light beam that passes through the reflective polarizer is not limited by the present application.

[0059] In this implementation, the first curved mirror 130 includes a first curved reflector 131. In this embodiment, a freeform reflector is used as an example to correct aberrations caused by the irregular curve of the windshield. The surfaces of optical elements used in conventional optical designs are standard spherical surfaces. Typically, multiple spherical mirrors are required to work together to correct aberrations. Therefore, the optical structure of the optical element is complex and occupies a large space. As the optical industry develops, the design and manufacturing technology of complex aspherical surfaces has improved significantly. Aspherical surfaces are typically non-rotating aspherical surfaces, such as quadratic surfaces, higher-order surfaces, and off-axis aspherical surfaces, such as paraboloids, ellipsoids, involute surfaces, and hyperboloids with a rotation axis. In different usage scenarios, one aspherical surface typically replaces two or more spherical surfaces to correct aberrations, simplifying the optical structure and achieving a smaller and lighter optical path.

[0060] Compared to aspherical surfaces, free-form surfaces have a more complex optical structure. Each point on the surface has a different radius of curvature, allowing for a much greater degree of freedom. Free-form surfaces can replace multiple aspherical surfaces to correct aberrations, while also maximizing optical quality and simplifying optical structures. Optical free-form surfaces have complex structures and a high degree of freedom, and there is no clear definition of their meaning. Generally, any optical surface that does not have global rotational symmetry, does not have a unified optical axis, and has multiple radii of curvature across its entire surface is considered an optical free-form surface.

[0061] The second retroreflected light beam 113 reflected by the first curved reflector 131 is converted to right-handed circularly polarized light. In Fig. 8, the clockwise arc arrow indicates right-handed circularly polarized light, which is converted to P linearly polarized light after passing through the first polarization converter 140. In Fig. 8, the double-headed arrow slanting from the upper left to the lower right indicates P linearly polarized light. The P linearly polarized second retroreflected light beam 113 may pass through the reflective polarizer 120 and be reflected by the windshield 200 to be imaged into the driver's eye.

[0062] 7 and 6 , in this implementation, the picture generating unit 110 is arranged to emit a polarized light beam, and the light beam is selectively transmitted and reflected by the reflective polarizer 120 while passing back and forth between the reflective polarizer 120 and the first curved reflector 131 based on the different responses of the reflective polarizer 120, the first polarization converter 140, and the first curved reflector 131 to the polarization state of the light beam. Because the reflective polarizer 120 is not required to avoid the light beam passing back and forth, the volume of the projection device 100 is correspondingly reduced. As the FOV and VID of the projection device 100 increase, the volume of the projection device 100 is effectively controlled so that the volume increases slightly, remains unchanged, or decreases.

[0063] It will be appreciated that the second state of linear polarization in this implementation may alternatively be P linear polarization, and the P linearly polarized incident light beam 111 is reflected by the reflective polarizer 120 to form the first retroreflected light beam 112. The first retroreflected light beam 112 is P linearly polarized and is converted to the second state of circular polarization after passing through the first polarization converter 140. The second state of circular polarization may be right-handed circular polarization, and the first retroreflected light beam 112 in the right-handed circular polarization state is reflected by the first curved reflector 131 to form the second retroreflected light beam 113.

[0064] The second retroreflected light beam 113 reflected by the first curved reflector 131 is converted into left-handed circularly polarized light, which is converted into S-linearly polarized light after passing through the first polarization converter 140, and the S-linearly polarized second retroreflected light beam 113 passes through the reflective polarizer 120 and may be imaged into the driver's eyes after being reflected by the windshield 200.

[0065] In this implementation, the reflective polarizer 120 may be a reflective polarizing film with polarizing properties, or two materials with different refractive indices may be used to form a multilayer film, such as a dual brightness enhancement film (DBEF). Specifically, the multilayer film may be a reflective polarizing brightness enhancement film, or may include multiple layers, such as a diffuser layer, multiple layers of reflective polarizing films, and a diffuser layer, stacked in sequence. Specifically, the reflective polarizing film may be separately attached to a substrate layer, which may be a polycarbonate (PC) or glass substrate. The size of the first polarization converter 140 and corresponding parameters, such as the spacing between the reflective polarizing film and the first polarization converter 140, may be designed based on the optical system architecture of the projection device 100 to ensure that all light beams pass through different apertures. This allows the overall size of the first polarization converter 140 to be effectively utilized. In addition, the spacing between the reflective polarizer 120 and the first curved reflector 131 is also designed based on the optical system architecture of the projection device 100.

[0066] The first polarization converter 140 may be a quarter wave plate (QWP) or a half wave plate (HWP). The wave plate is a parallel planar sheet made of a crystal. It may be a wafer cut in a direction parallel to the optical axis of a birefringent crystal such as calcite, or it may be made of a material such as a mica disk, cellophane, or polyvinyl alcohol that has the propagation direction of the incident light. Specifically, the wave plate may be attached to the reflective surface of the first curved reflector 131, or may be separately attached to a polycarbonate (PC) or glass substrate.

[0067] In one possible implementation, as shown in Figures 9 and 10, Figure 9 is a diagram of another light beam transmission of the projection device 100 applied to a head-up display field in this implementation, and Figure 10 is a diagram of another change in the polarization state of the light beam of the projection device 100 in this implementation.

[0068] The picture generation unit 110 is located below the reflective polarizer 120. Below refers to the direction corresponding to when the vehicle is in normal driving mode. The projection device 100 is integrated into the center console, which is located below the windshield. Below in FIG. 9 is the Y direction, which corresponds to the downward direction when the vehicle is driving. The right side in FIG. 9 is the X direction, which corresponds to the rear side when the vehicle is driving. As shown in FIG. 9, the picture generation unit 110 is located in the Y direction of the reflective polarizer 120 and shifted in the X direction. The picture generation unit 110 emits an incident light beam 111 toward the reflective polarizer 120. The incident light beam 111 is a light beam emitted by the picture generation unit 110 and first encounters the reflective polarizer 120.

[0069] In this implementation, for example, the second state polarization is left-handed circular polarization, as shown in FIG. 10 . The picture generating unit 110 emits an incident light beam 111 with an S-linear polarization state. In FIG. 10 , a double-headed arrow slanting from the upper right to the lower left indicates S-linear polarization. The S-linearly polarized incident light beam 111 first passes through the first polarization converter 140 and is converted to left-handed circular polarization. In FIG. 10 , a counterclockwise arc arrow indicates left-handed circular polarization. The left-handed circular polarization is the second state polarization in this implementation, and the left-handed circular polarization is converted to right-handed circular polarization after reflection by the reflective polarizer 120. In FIG. 10 , a clockwise arc arrow indicates right-handed circular polarization that forms the first retroreflected light beam 112. The first retroreflected light beam 112 is right-handed circular polarization and is converted to the first state linear polarization after passing through the first polarization converter 140. In this implementation, for example, the first state of circular polarization is P linear polarization. In Figure 10, the double-headed arrow sloping from the upper left to the lower right indicates P linear polarization, and the first retroreflected light beam 112 in the P linear polarization state is reflected by the first curved reflector 131 to form the second retroreflected light beam 113.

[0070] In this implementation, the first curved mirror 130 includes a first curved reflector 131. In this embodiment, a freeform reflector is used as an example to correct for aberrations caused by the irregular curve of the windshield.

[0071] The second retroreflected light beam 113 reflected by the first curved reflector 131 is in a P linear polarization state, and the second retroreflected light beam 113 in the P linear polarization state is converted to a first state polarization after passing through the first polarization converter 140. Right-handed circularly polarized light is the first state polarization described in this implementation. The right-handed circularly polarized light may be transmitted through the reflective polarizer 120 or may be imaged into the driver's eye after being reflected by the windshield 200.

[0072] For example, it will be understood that the second state polarization in this implementation may alternatively be right-handed circular polarization. The picture generating unit 110 emits the incident light beam 111 in a P linear polarization state, and the P linear polarization is converted to a second state polarization after passing through the first polarization converter 140; for example, the second state polarization may be right-handed circular polarization, and the right-handed circular polarization is reflected by the reflective polarizer 120 to form the first retroreflected light beam 112. The first retroreflected light beam 112 is left-handed circularly polarized and is converted to the first state linear polarization after passing through the first polarization converter 140. The first state linear polarization may be P linear polarization, and the first retroreflected light beam 112 in the P linear polarization state is reflected by the first curved reflector 131 to form the second retroreflected light beam 113.

[0073] The second retroreflected light beam 113 reflected by the first curved reflector 131 is in a P linear polarization state, and the P linear polarization is converted to right-handed circular polarization after passing through the first polarization converter 140, and the second retroreflected light beam 113 in the right-handed circular polarization state may pass through the reflective polarizer 120 and be imaged into the driver's eye after being reflected by the windshield 200.

[0074] In this implementation, the reflective polarizer 120 includes a polarizing element, which may be a liquid crystal polarizer with polarization properties. The liquid crystal polarizer controls the voltage to achieve liquid crystal polarization, which may reflect left-handed circularly polarized light and transmit right-handed circularly polarized light, or reflect right-handed circularly polarized light and transmit left-handed circularly polarized light. The liquid crystal polarizer may be attached to a substrate layer, which may be a polycarbonate (PC) or glass substrate. Corresponding parameters, such as the size of the first polarization converter 140 and the spacing between the liquid crystal polarizer and the first polarization converter 140, may be designed based on the optical system architecture of the projection device 100 to ensure that all light beams pass through different apertures. This effectively utilizes the overall size of the first polarization converter 140. In addition, the spacing between the reflective polarizer 120 and the first curved reflector 131 is also designed based on the optical system architecture of the projection device 100.

[0075] The first polarization converter 140 may be a quarter wave plate (QWP) or a half wave plate (HWP). The wave plate is a parallel planar sheet made of a crystal. It may be a wafer cut in a direction parallel to the optical axis of a birefringent crystal such as calcite, or it may be made of a material such as a mica disk, cellophane, or polyvinyl alcohol that has the propagation direction of the incident light. Specifically, the wave plate may be attached to the reflective surface of the first curved reflector 131, or may be separately attached to a polycarbonate (PC) or glass substrate.

[0076] It will be appreciated that the wave plate of the first polarization converter 140 may be a unitary structure, such as the integrated wave plate shown in Figure 9 for transmitting the incident light beam 111, the first retroreflected light beam 112, and the second retroreflected light beam 113. Alternatively, the wave plate of the first polarization converter 140 may be two parts, one disposed between the reflective polarizer 120 and the picture generating unit 110 to transmit the incident light beam 111, and the other disposed between the reflective polarizer 120 and the first curved reflector 131 to transmit the first retroreflected light beam 112 and the second retroreflected light beam 113.

[0077] 9 may further include a second polarization converter 150. The second polarization converter 150 is disposed on a side of the reflective polarizer 120 that is away from the first curved reflector 131. In addition, the circularly polarized light transmitted through the reflective polarizer 120 is transmitted through the second polarization converter 150, which converts the circularly polarized light into linearly polarized light, which may be reflected by the windshield 200 and then imaged into the driver's eyes.

[0078] In one possible implementation, as shown in Figures 11 and 12, Figure 11 is a diagram of another light beam transmission of the projection device 100 applied to a head-up display field in this implementation, and Figure 12 is a diagram of another change in the polarization state of the light beam of the projection device 100 in this implementation.

[0079] Compared to the previous implementation, in this implementation, the incident light beam 111 may first pass through the reflective polarizer 120, and the incident light beam 111 that passes through the reflective polarizer 120 passes back and forth between the reflective polarizer 120 and the first curved mirror 130, and is reflected from the projection device 100 via the reflective polarizer 120.

[0080] Specifically, as shown in FIGS. 11 and 12, the picture generation unit 110 may be located to the right of the reflective polarizer 120. The right side corresponds to the rear side of the vehicle's traveling direction when the vehicle is in normal driving mode. The entire projection device 100 is located within the center console, which is located below the windshield. The downward direction in FIG. 11 corresponds to the Y direction, which corresponds to the downward direction when the vehicle is traveling. The right side in FIG. 11 corresponds to the X direction, which corresponds to the rear side of the vehicle's traveling direction when the vehicle is traveling. As shown in FIG. 11, the picture generation unit 110 is located in the X direction of the reflective polarizer 120 and is shifted in the Y direction. The picture generation unit 110 emits an incident light beam 111 toward the reflective polarizer 120. The incident light beam 111 is a light beam emitted by the picture generation unit 110 and first comes into contact with the reflective polarizer 120.

[0081] In this implementation, the first state of linear polarization is S-linear polarization, as shown in FIG. 12, for example. In FIG. 12, a double-headed arrow slanting from the upper right to the lower left indicates S-linear polarization, and the picture generating unit 110 emits S-linear polarization. An incident light beam 111 in the S-polarization state passes through a reflective polarizer 120 to form a transmitted light beam 114. The transmitted light beam 114 is S-linear polarization and is converted to a first state of circular polarization after passing through a first polarization converter 140. In this implementation, for example, the first state of circular polarization is left-handed circular polarization. In FIG. 12, a counterclockwise arc-shaped arrow indicates left-handed circular polarization, and the transmitted light beam 114 in the left-handed circular polarization state is reflected by a first curved reflector 131 to form a first retroreflected light beam 112.

[0082] In this implementation, the first curved mirror 130 includes a first curved reflector 131. In this embodiment, a freeform reflector is used as an example to correct for aberrations caused by the irregular curve of the windshield.

[0083] The first retroreflected light beam 112 reflected by the first curved reflector 131 is converted to right-handed circularly polarized light. In FIG. 12 , the clockwise arc arrow indicates right-handed circularly polarized light, which is converted to P linearly polarized light after passing through the first polarization converter 140. In FIG. 12 , the double-headed arrow slanting from the upper left to the lower right indicates P linearly polarized light. The first retroreflected light beam 112 in the P linear polarization state is reflected by the reflective polarizer 120. The second state of linear polarization in this implementation may be P linearly polarized light, forming the second retroreflected light beam 113. In this implementation, the reflective polarizer 120 is positioned obliquely, specifically, from the lower left to the upper right, to prevent the second retroreflected light beam 113 from being reflected again by the first curved reflector 131. In this manner, the second retroreflected light beam 113 can avoid the reflective polarizer 120 and the first polarization converter 140. The second retro-reflected light beam 113 of P linear polarization is emitted outside the projection device 100 and is imaged to the driver's eye after being reflected by the windshield 200 .

[0084] It will be understood that the second state linear polarization in this implementation may alternatively be S linear polarization, and the first state linear polarization may alternatively be P linear polarization, with the incident light beam 111 being in a P linear polarization state. The incident light beam 111 is transmitted through the reflective polarizer 120 to form a transmitted light beam 114. The transmitted light beam 114 is P linearly polarized and is converted to a first state circular polarization after passing through the first polarization converter 140. The first state circular polarization may be right-handed circular polarization, and the transmitted light beam 114 in the right-handed circular polarization state is reflected by the first curved reflector 131 to form the first retroreflected light beam 112.

[0085] The first retroreflected light beam 112 reflected by the first curved reflector 131 is converted into left-handed circularly polarized light, which is converted into S-linearly polarized light after passing through the first polarization converter 140, and the S-linearly polarized first retroreflected light beam 112 is reflected by the reflective polarizer 120 to form a second retroreflected light beam 113 with S-linear polarization state. The second retroreflected light beam 113 is emitted outside the projection device 100 and is reflected by the windshield 200 to be imaged into the driver's eyes.

[0086] In this implementation, the reflective polarizer 120 may be a reflective polarizing film with polarizing properties, or two materials with different refractive indices may be used to form a multilayer film, such as a dual brightness enhancement film (DBEF). Specifically, the multilayer film may be a reflective polarizing brightness enhancement film, or may include multiple layers, such as a diffuser layer, multiple layers of reflective polarizing films, and a diffuser layer, stacked in sequence. Specifically, the reflective polarizing film may be separately attached to a substrate layer, which may be a polycarbonate (PC) or glass substrate. The size of the first polarization converter 140 and corresponding parameters, such as the spacing between the reflective polarizing film and the first polarization converter 140, may be designed based on the optical system architecture of the projection device 100 to ensure that all light beams pass through different apertures. This allows the overall size of the first polarization converter 140 to be effectively utilized. In addition, the spacing between the reflective polarizer 120 and the first curved reflector 131 is also designed based on the optical system architecture of the projection device 100.

[0087] The first polarization converter 140 may be a quarter wave plate (QWP) or a half wave plate (HWP). The wave plate is a parallel planar sheet made of a crystal. It may be a wafer cut in a direction parallel to the optical axis of a birefringent crystal such as calcite, or it may be made of a material such as a mica disk, cellophane, or polyvinyl alcohol that has the propagation direction of the incident light. Specifically, the wave plate may be attached to the reflective surface of the first curved reflector 131, or may be separately attached to a polycarbonate (PC) or glass substrate.

[0088] In one possible implementation, as shown in Figures 13 and 14, Figure 13 is a diagram of another light beam transmission of the projection device 100 applied to a head-up display field in this implementation, and Figure 14 is a diagram of another change in the polarization state of the light beam of the projection device 100 in this implementation.

[0089] Compared with the previous implementation, in this implementation, the incident light beam 111 may first be transmitted through the first curved mirror 130 and then reflected by the reflective polarizer 120. The light beam reflected by the reflective polarizer 120 may be transmitted back and forth between the reflective polarizer 120 and the first curved mirror 130 and emitted outside the projection device 100 via the reflective polarizer 120.

[0090] Specifically, as shown in FIGS. 13 and 14 , the picture generation unit 110 may be located below the reflective polarizer 120, a first curved mirror 130 may be located between the reflective polarizer 120 and the picture generation unit 110, and a first polarization converter 140 may be located between the reflective polarizer 120 and the first curved mirror 130. Referring to the corresponding direction when the vehicle is in a normal driving state, the projection device 100 is integrated into the center console, and the center console is located below the windshield. The downward direction in FIG. 13 is the Y direction, which corresponds to the downward direction when the vehicle is driving. The right side in FIG. 13 is the X direction, which corresponds to the rear side when the vehicle is driving. As shown in FIG. 13 , the picture generation unit 110 is located in the Y direction of the reflective polarizer 120, and the picture generation unit 110 emits an incident light beam 111 toward the reflective polarizer 120. The incident light beam 111 is the light beam emitted by the picture generating unit 110 and that first encounters the reflective polarizer 120 .

[0091] In this implementation, as shown in FIGS. 13 and 14 , the incident light beam 111 emitted by the picture generating unit 110 is S-linearly polarized light. In FIG. 14 , a double-headed arrow slanting from the upper right to the lower left indicates S-linearly polarized light. The S-linearly polarized light may be transmitted through the first curved mirror 130, and the transmitted incident light beam 111 remains S-linearly polarized and then passes through the first polarization converter 140. The first polarization converter 140 converts the incident light beam 111 to left-handed circularly polarized light, and in FIG. 14 , a counterclockwise arc-shaped arrow indicates left-handed circularly polarized light. In this implementation, the second state of circular polarization may be left-handed circularly polarized light, and the incident light beam 111 enters the reflective polarizer 120 and is reflected by the reflective polarizer 120 to form the first retroreflected light beam 112.

[0092] In this implementation, the first curved mirror 130 includes a first curved semi-transparent mirror 132. In this implementation, a freeform semi-transparent mirror is used as an example. The curved mirror has polarization-based selective transmission, and can transmit linearly polarized light in a second state and reflect linearly polarized light in a first state. In addition, the first curved semi-transparent mirror 132 has a freeform shape at the reflecting surface, which corrects aberrations caused by the irregular curve of the windshield after reflecting the light beam.

[0093] In this implementation, the first state of circular polarization may be right-handed circular polarization, and the second state of circular polarization may be left-handed circular polarization, and the first retroreflected light beam 112 reflected by the reflective polarizer 120 is converted to right-handed circular polarization. In FIG. 14 , the clockwise arc arrow indicates right-handed circular polarization, which is converted to P linear polarization after passing through the first polarization converter 140. In FIG. 14 , the double-headed arrow sloping from the upper left to the lower right indicates P linear polarization. The first retroreflected light beam 112 in the P linear polarization state is reflected by the first curved semitransparent mirror 132, and the reflected light beam becomes the second retroreflected light beam 113. The second retroreflected light beam 113 passes through the first polarization converter 140 and is converted to right-handed circular polarization. In this implementation, the first state of circular polarization may be right-handed circular polarization. The second retro-reflected light beam 113 may be transmitted through the reflective polarizer 120 and emitted outside the projection device 100, and may be imaged to the driver's eye after being reflected by the windshield 200.

[0094] It will be understood that the second state of circular polarization in this implementation may alternatively be left-handed circular polarization, the first state of circular polarization may alternatively be right-handed circular polarization, and the incident light beam 111 emitted by the picture generating unit 110 may be a P linear polarization state. The incident light beam 111 may pass through the first curved semi-transparent mirror 132 and pass through the first polarization converter 140 in a P linear polarization state and be converted to right-handed circular polarization. In this implementation, the reflective polarizer 120 may transmit left-handed circular polarization and reflect right-handed circular polarization. The incident light beam 111 in the right-handed circular polarization state is reflected by the reflective polarizer 120 to form the first retroreflected light beam 112.

[0095] The first retroreflected light beam 112 reflected by the reflective polarizer 120 is in a left-handed circularly polarized state, and the left-handed circularly polarized first retroreflected light beam 112 is converted to S-linearly polarized light after passing through the first polarization converter 140. The S-linearly polarized light is reflected by the first curved semi-transparent mirror 132 into a second retroreflected light beam 113, which is converted to left-handed circularly polarized light by the first polarization converter 140. The left-handed circularly polarized light passes through the reflective polarizer 120, is emitted out of the projection device 100, and may be reflected by the windshield 200 to be imaged into the driver's eyes.

[0096] In this implementation, the reflective polarizer 120 may be a reflective polarizing film with polarizing properties, or two materials with different refractive indices may be used to form a multilayer film, such as a dual brightness enhancement film (DBEF). Specifically, the multilayer film may be a reflective polarizing brightness enhancement film, or may include multiple layers, such as a diffuser layer, multiple layers of reflective polarizing films, and a diffuser layer, stacked in sequence. Specifically, the reflective polarizing film may be separately attached to a substrate layer, which may be a polycarbonate (PC) or glass substrate. The size of the first polarization converter 140 and corresponding parameters, such as the spacing between the reflective polarizing film and the first polarization converter 140, may be designed based on the optical system architecture of the projection device 100 to ensure that all light beams pass through different apertures. This allows the overall size of the first polarization converter 140 to be effectively utilized. In addition, the spacing between the reflective polarizer 120 and the first curved reflector 131 is also designed based on the optical system architecture of the projection device 100.

[0097] The first polarization converter 140 may be a quarter wave plate (QWP) or a half wave plate (HWP). The wave plate is a parallel planar sheet made of a crystal. It may be a wafer cut in a direction parallel to the optical axis of a birefringent crystal such as calcite, or it may be made of a material such as a mica disk, cellophane, or polyvinyl alcohol that has the propagation direction of the incident light. Specifically, the wave plate may be attached to the reflective surface of the first curved reflector 131, or may be separately attached to a polycarbonate (PC) or glass substrate.

[0098] 15, the projection device 100 of this implementation further includes a lens element 160. The lens element 160 is located at the light beam emission end of the projection device 100. The light beam emitted from the projection device 100 passes through the lens element 160 and is emitted outside the projection device.

[0099] Specifically, lens element 160 may be disposed on the back-end light beam of retroreflected light reflected or transmitted by reflective polarizer 120. After optical coefficient adjustments are made to the light beam through reflective polarizer 120, first curved mirror 130, and first polarization converter 140 (which may further include second polarization converter 150), the light beam is emitted through lens element 160 onto windshield 200.

[0100] For example, as shown in FIG. 15, a lens element 160 may be disposed between the reflective polarizer 120 and the windshield 200, and all of the light beams reflected by the first curved mirror 130 may be transmitted through the lens element 160.

[0101] The lens element 160 performs optical adjustments on the light beam emitted by the projection apparatus 100, improving the optical quality of the entire architecture of the projection apparatus 100 and reducing the difficulty of designing and processing the free-form surface of the first curved mirror 130. In addition, in the existing manufacturing process of the projection apparatus 100, each module is manufactured in a standardized manner, and the processing parameters of the lens element may be designed to meet different optical requirements, such as different vehicle models, to satisfy multiple performance requirements of the projection apparatus 100, thereby reducing the difficulty and cost of the overall development of the projection apparatus 100.

[0102] Specifically, the lens element 160 may be made of materials such as resin, glass, micro-nanostructures, etc. In terms of shape, depending on the optical requirements of the projection device 100, the profile of the lens element 160 may be a phenia lens, an aspheric lens, a diffraction grating lens, etc.

[0103] It will be understood that the lens element 160 in this implementation can be applied to the projection apparatus in any of the previously described implementations.

[0104] The optical design of the projection device 100 is determined or optimized based on performance indicators, material selection, testability, tolerance control, processing and assembly, cost, and so on. These factors must be considered throughout the entire process, from the beginning of product design to the end of product production, as well as the device commissioning process in product application. In the entire process, especially for head-up display devices, the design parameters of the freeform mirror have a significant impact on the overall image quality of the product, making the parameter design and production of the freeform mirror highly demanding. According to this embodiment of the present application, for the same indicator achieved by the freeform surface, adding the lens element 160 means increasing the optimization dimension of the optical design. The imaging of the projection device can be optimized by adjusting the parameter design of the lens element 160, reducing the requirements for the indicators of the freeform surface. In addition, changing the lens element 160 can meet the specific performance indicator requirements of the projection device, eliminating the need to change the freeform surface, thereby reducing the difficulty and complexity of optical system optimization.

[0105] 16, the projection device 100 further includes a diffuser 170, which is located on the light-emitting side of the picture generation unit 110. The light beam emitted by the picture generation unit 110 to the reflective polarizer 120 passes through the diffuser 170.

[0106] The diffuser 170 can realize the projection image plane of the picture generation unit 110 and the image formation target plane of the projection device 100. The surface of the diffuser 170 has a micro-nano structure, and the substrate material is glass, resin, or glass substrate resin. The diffuser 170 may be an element independent of a microlens array (MLA) or a diffractive optical element (DOE), or may be a device that can easily combine with a Fresnel element, and may be processed by nanoimprint lithography, etching, or injection molding.

[0107] The diffuser 170 is a physical screen that can receive the real image of the picture generation unit 110, perform light homogenization and optical stretch angle control on the image, and provide a display surface for the polarization and folding components within the projection device 100.

[0108] In one possible implementation, as shown in FIG. 17 , the projection device 100 further includes an anti-glare film 180. The reflective polarizer 120, the first curved mirror 130, and the first polarization converter 140 form a light path module. The anti-glare film 180 is located on the light-emitting side of the light path module. Specifically, as shown in FIG. 17 , the anti-glare film 180 may be located above the reflective polarizer 120 and between the reflective polarizer 120 and the lens element 160. The light beam emitted by the light path module is emitted outside the projection device 100 after passing through the anti-glare film 180.

[0109] The anti-glare film 180 can change the center of symmetry of light reflection. When external sunlight enters the projection device 100 through the windshield 200, the light reflected by the anti-glare film 180 is outside the range visible to the driver, for example, above the driver's eyes, and does not enter the driver's eyes, thereby preventing the driver from becoming dizzy.

[0110] In one possible implementation, FIG. 18 is a diagram of a structural configuration of a projection device 100.

[0111] Projection device 100 includes devices such as picture generation unit 110, reflective polarizer 120, first curved mirror 130, and first polarization converter 140, or further includes elements such as second polarization converter 150, lens element 160, diffuser 170, and anti-glare film 180. In this implementation, projection device 100 further includes processor 190. Processor 190 can generate a virtual image, and projection device 100 can emit a light beam for the virtual image.

[0112] Specifically, the acquisition device acquires environmental information. For example, a radar system acquires information such as the driving environment of the vehicle ahead and the road ahead, including information such as lane information, distance to the vehicle ahead, and the speed of the vehicle ahead. The environmental information is sent to the processor 190, which processes the environmental information. In addition, the processor 190 acquires digital information related to the moving vehicle, such as vehicle speed, navigation, vehicle gear, cruise control, rotation speed, charge status, endurance range, audiovisual entertainment system, etc. The digital information is combined with the acquired environmental information, and the corresponding environmental information is combined with the corresponding digital information. For example, as shown in FIG. 5, the distance to the vehicle ahead is displayed behind the vehicle ahead, and a virtual image of navigation information is displayed on the road surface (e.g., a left-turn prompt arrow is displayed, and the virtual arrow corresponds to the displayed lane). After combining the environmental information with the digital information, the processor 190 generates a light beam corresponding to the virtual image. After being imaged through the picture generation unit 110, the reflective polarizer 120, the first curved mirror 130, the first polarization converter 140, etc., the light beam is reflected by the windshield 200 and imaged into the driver's eyes.

[0113] In one possible implementation, multiple curved mirrors may be disposed in the projection device 100. As shown in Figure 19, the projection device 100 may further include a second curved mirror 133 in addition to the first curved mirror 130, or may further include other curved mirrors. The reflective polarizer and polarization converter described in the embodiments of the present application may be disposed between the picture generation unit 110 and the first curved mirror 130.

[0114] The present application further provides a specific implementation of a display device, which includes an imaging screen and a projection device according to any one of the above-mentioned implementations, wherein a light beam emitted by the projection device is refracted and / or reflected by the imaging screen for imaging.

[0115] The display device may be a projection device such as a projector. The display may be a display screen, and the light beam emitted by the projection device 100 is projected directly onto the display for imaging.

[0116] Alternatively, the display device may be a head-mounted display device, such as holographic glasses and / or a helmet, that projects a virtual image in front of a person to form a virtual augmented reality image. For example, the display device may be used in augmented reality glasses and an augmented reality helmet, or in virtual reality (VR) glasses and a virtual reality helmet. The operating principle of the display device is similar to that of a head-up display in a vehicle, with the difference being the design of the optical distance and optical parameters.

[0117] An embodiment of the present application further provides a specific implementation form of a transportation means. The transportation means in this embodiment of the present application may include road transportation means, water transportation means, air transportation means, industrial devices, agricultural devices, entertainment devices, etc. For example, the transportation means may be a vehicle. The vehicle is a vehicle in a broad sense and may be a transportation means (such as a commercial vehicle, a passenger car, a motorcycle, an aircraft, or a train), an industrial vehicle (such as a forklift, a trailer, or a tractor), a construction vehicle (such as a hydraulic excavator, a bulldozer, or a crane), an agricultural machine (such as a lawn mower or a harvester), an entertainment device, or a toy vehicle. The type of vehicle is not specifically limited in the embodiment of the present application. As another example, the transportation means may be a transportation means such as an airplane or a ship.

[0118] In addition to typical components such as an engine or motor, road wheels, a steering wheel, and a transmission, the vehicle may further include any of the aforementioned embodiments of the projection device 100 or may include a display device in the aforementioned implementations. Additionally, the vehicle may further include a projection medium. The projection medium may be a windshield 200, configured to receive light emitted by the projection device 100 and perform imaging. In this implementation, the projection device 100 projects an image. After being refracted and / or reflected by the projection medium, such as the windshield 200, the image eventually reaches the driver's eye, allowing the driver to see a virtual image with a specific depth of field outside the vehicle while looking out through the windshield.

[0119] An embodiment of the present application further provides a projection method applied to the projection apparatus in any one of the above-mentioned implementations. The projection apparatus includes a picture generation unit 110, a reflective polarizer 120, a first curved mirror 130, and a first polarization converter 140. Specific steps of the projection method in this embodiment of the present application are described in detail below.

[0120] Step S100: The picture generating unit emits a polarized light beam. Specifically, the picture generating unit may emit the polarized light beam through a polarizing mechanism such as a polarizing film.

[0121] Step S200: The polarized beam is propagated to a first polarization converter through a reflective polarizer, passes through the first polarization converter to propagate to a first curved mirror, propagates to the first polarization converter through the first curved mirror, passes through the first polarization converter to propagate to a reflective polarizer, and is projected outside the projection device through the reflective polarizer.

[0122] The polarized light emitted by the picture-generating unit is directed toward the reflective polarizer 120, whose polarization direction is different from that of the polarized light emitted by the picture-generating unit, and the reflective polarizer 120 reflects the light beam. The light beam then travels back and forth between the reflective polarizer 120 and the first curved mirror 130. The first curved mirror 130 can reflect the polarized light and change the form of circular polarization, and can change the polarization form in combination with the first polarization converter 140. In this way, the light beam that has traveled back and forth can be transmitted again when it passes through the reflective polarizer 120, and is finally reflected by the windshield to form an image in the driver's eyes.

[0123] Alternatively, the polarized light emitted by the picture-generating unit is directed toward the reflective polarizer 120, whose polarization direction is the same as that of the polarized light emitted by the picture-generating unit, and the light beam is transmitted through the reflective polarizer 120. The transmitted light beam is transmitted back and forth between the reflective polarizer 120 and the first curved mirror 130. The first curved mirror 130 can reflect the polarized light and change the form of circular polarization, and can change the polarization form in combination with the first polarization converter 140. In this way, the transmitted light beam can be reflected when it is transmitted back through the reflective polarizer 120, and finally reflected by the windshield to be imaged in the driver's eyes.

[0124] An embodiment of the present application further provides a computing device. Figure 20 is a diagram of the structure of a computing device 300 according to an embodiment of the present application. The computing device 300 includes a processor 310, a memory 320, a communication interface 330, and a bus 340.

[0125] It should be understood that the communication interface 330 in the computing device 300 shown in FIG. 20 may be used to communicate with another device.

[0126] The processor 310 may be connected to a memory 320. The memory 320 may be configured to store program codes and data. Thus, the memory 320 may be a storage unit within the processor 310, an external storage unit separate from the processor 310, or a component including a storage unit within the processor 310 and an external storage unit separate from the processor 310.

[0127] Optionally, the computing device 300 may further include a bus 340. The memory 320 and the communication interface 330 may be connected to the processor 310 via the bus 340. The bus 340 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus 340 may be categorized into an address bus, a data bus, a control bus, etc. For ease of representation, only one line is used in FIG. 20, but this does not imply that there is only one bus or one type of bus.

[0128] It should be understood that in this embodiment of the present application, the processor 310 may be a Central Processing Unit (CPU). The processor may alternatively be a general-purpose processor, a Digital Signal Processor (DSP), an Application-Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or another programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc. Alternatively, the processor 310 may be configured to use one or more integrated circuits and execute associated programs to implement the technical solutions provided in this embodiment of the present application.

[0129] The memory 320 may include read-only memory and random access memory and may provide instructions and data to the processor 310. A portion of the processor 310 may further include non-volatile random access memory. For example, the processor 310 may further store device type information.

[0130] When computing device 300 operates, processor 310 executes computer-executable instructions in memory 320 to perform the operational steps of the methods described above.

[0131] It should be understood that the computing device 300 according to this embodiment of the present application may correspond to a corresponding execution entity of the method according to the embodiment of the present application, and the above-mentioned and other operations and / or functions of the modules in the computing device 300 are intended to separately implement corresponding procedures of the method according to the embodiment. For the sake of brevity, the details will not be described again here.

[0132] Those skilled in the art may recognize that, in combination with the examples described in the embodiments disclosed herein, the units and algorithm steps may be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether a function is implemented by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may implement the described functions using various methods for each specific application, but such implementation should not be considered to go beyond the scope of this application.

[0133] For the purpose of easy description, it can be clearly understood by those skilled in the art that the detailed working processes of the aforementioned systems, devices and units should be referred to the corresponding processes of the aforementioned method embodiments, and the details will not be repeated here.

[0134] In some embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the described device embodiments are merely examples. For example, the division into units is merely a logical division of function. In actual implementation, other division schemes may be used. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the shown or described mutual couplings or direct couplings or communication connections may be implemented via some interfaces. Indirect couplings or communication connections between devices or units may be implemented in electronic, mechanical, or other forms.

[0135] The units described as separate parts may or may not be physically separate, and the parts shown as units may or may not be physical units, may be located in one place, or may be distributed over multiple network units. Some or all of the units may be selected based on actual requirements to achieve the objectives of the solutions of the embodiments.

[0136] In addition, the functional units in the embodiments of the present application may be integrated into one processing unit, or each of the units may exist physically alone, or two or more units may be integrated into one unit.

[0137] When a function is implemented in the form of a software functional unit and sold or used as an independent product, the function may be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of the present application, or portions contributing to the prior art, or portions of the technical solutions may be implemented in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for instructing a computing device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. The aforementioned storage medium includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0138] An embodiment of the present application further provides a computer-readable storage medium, which stores a computer program, and when the program is executed by a processor, the program is used to perform a diversity problem generation method, which includes at least one of the solutions described in the previous embodiments.

[0139] The computer storage medium in the embodiments of the present application may be any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any combination thereof. More specific examples (non-exhaustive list) of computer-readable storage media include an electrical connection with one or more wires, a portable computer disk, a hard disk, RAM, ROM, erasable programmable read-only memory, optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this specification, a computer-readable storage medium may be any tangible medium that contains or stores a program, and the program may be used by or in combination with an instruction execution system, device, or component.

[0140] It should be noted that the above are merely exemplary embodiments and applied technical principles of the present application. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that those skilled in the art can make various obvious changes, adjustments, and substitutions without departing from the protection scope of the present invention. Therefore, although the present application has been described in detail using the above embodiments, the present invention is not only limited to the above embodiments, but can also include many other equivalent embodiments without departing from the concept of the present invention, all of which fall within the protection scope of the present invention. [Explanation of symbols]

[0141] 100 Projection device 110 Picture Generation Unit 111 Incident light beam 112 first retroreflected light beam 113 Second retroreflected light beam 114 Transmitted Light Beam 120 reflective polarizer 130 First curved mirror 131 First curved reflector 132 First curved semi-transparent mirror 133 Second curved mirror 140 First polarization converter 150 Second Polarization Converter 160 lens elements 170 Diffuser 180 Anti-glare film 190 Reflector, Processor 200 Windshield 300 computing devices 310 processor 320 memory 330 Communication Interface 340 Bus

Claims

1. 1. A projection device comprising: a picture generation unit, a reflective polarizer, a first curved mirror, and a first polarization converter, wherein the picture generation unit is configured to emit a polarized beam; the first polarization converter is located between the reflective polarizer and the first curved mirror and is configured to transmit the polarized light beam and change the polarization state of the polarized light beam; the first curved mirror is configured to reflect the polarized beam; a projection device, wherein the polarized beam, after being emitted by the picture generating unit, propagates through the reflective polarizer to the first polarization converter, transmits through the first polarization converter to propagate to the first curved mirror, propagates through the first curved mirror to the first polarization converter, and transmits through the first polarization converter to propagate to the reflective polarizer.

2. the reflective polarizer is configured to transmit a polarized beam having a first polarization state and to reflect a polarized beam having a second polarization state; 2. The projection device of claim 1, wherein the polarization states include linear polarization and circular polarization, the polarized beam in the first state includes first state linear polarization and first state circular polarization, and the polarized beam in the second state includes second state linear polarization and second state circular polarization.

3. the first curved mirror comprises a first curved reflector, the picture generating unit is located on a side of the reflective polarizer closer to the first curved reflector, the picture generating unit emits a polarized beam, and the polarization state of the polarized beam is the second state of linear polarization; 3. The projection device of claim 1, wherein the polarized beam is reflected by the reflective polarizer and propagates to the first polarization converter, the polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to the second state of circular polarization, and passes through the first polarization converter to propagate to the first curved reflector, the polarized beam is reflected by the first curved reflector to convert the polarization state of the polarized beam to the first state of circular polarization and propagates to the first polarization converter, the polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to the first state of linear polarization, and passes through the first polarization converter to propagate to the reflective polarizer, and passes through the reflective polarizer.

4. 4. The projection device of claim 1, wherein the first polarization converter comprises a quarter wave plate.

5. the first curved mirror comprises a first curved reflector, the picture generating unit is located on a side of the reflective polarizer closer to the first curved reflector, the picture generating unit emits a polarized beam, and the polarization state of the polarized beam is the second state of linear polarization; 3. The projection device of claim 1, wherein the polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to the second state of circular polarization, is reflected by the reflective polarizer to convert the polarization state of the polarized beam to the first state of circular polarization, is propagated to the first polarization converter, the polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to the first state of linear polarization, is propagated to the first curved reflector, the polarized beam is reflected by the first curved reflector, the polarized beam reflected by the first curved reflector is propagated to the first polarization converter, the polarized beam passes through the first polarization converter to convert the polarization state of the polarized beam to the first state of circular polarization, is propagated through the first polarization converter to propagate to the reflective polarizer, and is propagated through the reflective polarizer.

6. the first curved mirror comprises a freeform semi-transparent mirror, the picture generating unit is located on a side of the freeform semi-transparent mirror away from the reflective polarizer, the picture generating unit emits a polarized beam, and the polarization state of the polarized beam is the second state of linear polarization; 3. The projection device of claim 1, wherein the polarized beam is transmitted through the free-form semi-transparent mirror, the polarized beam transmitted through the free-form semi-transparent mirror is transmitted through the first polarization converter to convert the polarization state of the polarized beam to the second state of circular polarization, is reflected by the reflective polarizer to convert the polarization state of the polarized beam to the first state of circular polarization, and is propagated to the first polarization converter, the polarized beam is transmitted through the first polarization converter to convert the polarization state of the polarized beam to the first state of linear polarization, and is propagated to the free-form semi-transparent mirror, the polarized beam is reflected by the free-form semi-transparent mirror, the polarized beam reflected by the free-form semi-transparent mirror is propagated to the first polarization converter, the polarized beam is transmitted through the first polarization converter to convert the polarization state of the polarized beam to the first state of circular polarization, and is transmitted through the first polarization converter to propagate to the reflective polarizer, and is then transmitted through the reflective polarizer.

7. the first curved mirror comprises a first curved reflector, the picture generating unit is located on a side of the reflective polarizer away from the first curved reflector, the picture generating unit emits a polarized beam, the polarization state of the polarized beam is the second state of linear polarization; 3. The projection device of claim 1, wherein the polarized beam is transmitted through the reflective polarizer, the polarized beam transmitted through the reflective polarizer is propagated to the first polarization converter, the polarized beam is transmitted through the first polarization converter to convert the polarization state of the polarized beam to the second state of circular polarization, the polarized beam is transmitted through the first polarization converter to propagate to the first curved reflector, the polarized beam is reflected by the first curved reflector to convert the polarization state of the polarized beam to the first state of circular polarization, the polarized beam is propagated to the first polarization converter, the polarized beam is transmitted through the first polarization converter to convert the polarization state of the polarized beam to the first state of linear polarization, the polarized beam is transmitted through the first polarization converter to propagate to the reflective polarizer, and the polarized beam is reflected via the reflective polarizer to an exterior of the projection device.

8. 7. The projection device of claim 5, further comprising a second polarization converter located on a side of the reflective polarizer away from the first curved reflector, the second polarization converter configured to convert the polarized beam emitted by the reflective polarizer from the circular polarization to the linear polarization.

9. 9. The projection apparatus of claim 8, wherein the second polarization converter comprises a quarter wave plate or a half wave plate.

10. 8. The projection device of claim 5, 6 or 7, wherein the first polarization converter comprises a quarter wave plate or a half wave plate.

11. 8. The projection device of claim 1, 2, 3, 5, 6 or 7, wherein the reflective polarizer comprises a polarizing element, the polarizing element comprising at least one of a liquid crystal polarizer or a reflective polarizing film.

12. 12. The projection apparatus of claim 11, wherein the reflective polarizer further comprises a substrate layer, the polarizing element being attached to the substrate layer.

13. 8. The projection device of claim 1, 2, 3, 5, 6 or 7, wherein the projection device further comprises a lens element located at a light beam exit end of the projection device, the lens element configured to adjust an optical path of an exit light beam emitted by the projection device.

14. 8. The projection device of claim 1, 2, 3, 5, 6 or 7, wherein the projection device further comprises a diffuser, the diffuser being located on a light-emitting side of the picture generation unit, the diffuser being configured to implement a projection image plane of the picture generation unit.

15. 8. The projection device of claim 1, 2, 3, 5, 6 or 7, wherein the projection device further comprises an anti-glare film, the anti-glare film configured to treat the polarized beam to reduce or prevent glare.

16. 10. A display device comprising an imaging screen and the projection device of claim 1, wherein the imaging screen is configured to receive an output light beam emitted by the projection device and to form an image based on the output light beam.

17. The display device of claim 16 , wherein the display device comprises holographic glasses and / or a helmet.

18. 18. A vehicle comprising a projection device according to claim 1 or a display device according to claim 16 or 17, the vehicle comprising a projection medium configured to receive an output light beam emitted by the projection device and to perform imaging based on the output light beam.

19. 1. A projection method applied to a projection device, the projection device comprising a picture generation unit, a reflective polarizer, a first curved mirror, and a first polarization converter, the method comprising: emitting a polarized beam by the first picture generating unit; propagating the polarized beam through the reflective polarizer to the first polarization converter, transmitting the polarized beam through the first polarization converter for propagation to the first curved mirror, propagating the polarized beam through the first curved mirror to the first polarization converter, transmitting the polarized beam through the first polarization converter for propagation to the reflective polarizer, and projecting the polarized beam through the reflective polarizer external to the projection device; A projection method, including:

Images