Double-optical-path structure with continuous depth of field on far image surface and head-up display device

Abstract

The utility model provides a double optical path structure with continuous depth of field on a far image surface and a head-up display device, the double optical path structure comprises a projection device Z1, and light emitted by the projection device Z1 is reflected by a windshield glass WS to form short-distance projection and long-distance projection at a virtual image end. By controlling the included angle between the light L1 and the light L2, the included angle is larger than 30 degrees when a single light source is used and is larger than 25 degrees when double light sources are used, more natural and smooth visual transition can be effectively achieved, visual faults or abrupt feeling in a traditional projection mode is reduced, and the visual comfort degree is improved. And the configuration of a single light source or double light sources is adopted, so that the technology has higher flexibility. According to the head-up display device, the far and near projection virtual image perfectly fused with the real environment in vision can be presented, and on the basis of adding far projection and ground fusion, the dizziness caused by obvious projection distance difference when the view field is switched back and forth in far and near projection is reduced, so that the driving experience of a driver is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of head-up displays, and particularly relates to a dual optical path structure with a continuous depth of field for a far image and a head-up display device. BACKGROUND

[0002] In the prior art, such as the patent application CN218630367U, the light emitted by the image light source control part is divided into two paths by the plane mirror, one is into the first segment of the near projection light barrel, then enters the second segment of the near projection light barrel through the plane mirror, and finally emits light at the near projection diffusion board thereof; the other is into the first segment of the far projection light barrel, then enters the second segment of the near projection light barrel through the plane mirror, and finally emits light at the far projection diffusion board thereof.

[0003] Then, the generated near projection light source and the far projection light source are reflected by the first-order curved mirror, the second-order curved mirror and the windshield glass respectively, and two separated far projection and near projection are generated, so as to be received by the human eye.

[0004] The disadvantage of this technology is that the angle between the far projection image and the road surface is close to vertical, which results in a weak fusion effect between the actual far projection part image and the ground, and the navigation elements cannot well play the driving assistance effect. At the same time, the projection distance difference between the far projection and the near projection is large, and the human eye is prone to fatigue due to the distance jump in the mutual switching process of the two images, and the applicability is narrow, and it is only suitable for PGU image light sources of DLP / LCOS projection type.

[0005] In addition to the technical defects in the above patent application file, the traditional technical method is to change the optical path by optical design in the image source control part, so that the emitted light is a plurality of light beams with different distances and positions, thereby realizing multiple projections with different distances. This way of changing the optical path by optical design in the image source control part is relatively complex to implement and is not easy to adjust. Practical new type content

[0006] In view of the defects of the prior art, the present application provides a dual optical path structure with a continuous depth of field for a far image and a head-up display device, which realizes the mode of "one vertical and one inclined" image surface combination by the dual optical path structure with an angle between the far image surface and the road surface less than 60°, thereby increasing the fusion of the far projection and the ground, reducing the dizziness caused by the obvious projection distance difference when the field of view is switched back and forth between the far projection and the near projection, and improving the driving experience of the driver.

[0007] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0008] In a first aspect, the application provides a dual optical path structure with a continuous depth of field, which includes a projection device Z1. The light emitted by the projection device Z1 is reflected by the windshield WS and forms a close-range projection and a long-range projection at the virtual image end. The projection device Z1 can be a single light source or a dual light source. When the projection device Z1 is a single light source, the emitted light includes light rays L1 and L2. The angle between the light rays L1 and L2 is greater than 30°. When the projection device Z1 is a dual light source, the angle between the first light source and the second light source is greater than 25°.

[0009] The head-up display device projects light at different distances to form a close-range and long-range projection at the virtual image end, ensuring that objects in the field of view remain clear at different distances, thereby achieving a continuous depth of field effect. This is of great significance for application scenarios that require clear visual presentation in complex or multi-level environments, such as virtual reality, augmented reality, advanced driver assistance systems, etc.

[0010] By controlling the angle between the light rays L1 and L2, such as greater than 30° for a single light source and greater than 25° for a dual light source, a more natural and smooth visual transition can be effectively achieved, reducing the visual discontinuity or abruptness in traditional projection methods and improving visual comfort. The use of a single light source or dual light source configuration makes the technology more flexible. The single light source configuration simplifies the design and is suitable for cost-sensitive scenarios, while the dual light source configuration provides higher light intensity and precise light path control, making it suitable for scenarios with higher display requirements. Under different projection effects, the projection distance of different focal lengths can be more accurately controlled, improving the adaptability and practicality of the system. Optimizing the light source configuration of the projection device Z1, especially in dual light source mode, can effectively reduce light interference between different light sources, improve the accuracy of light projection, and optimize image quality, making it particularly suitable for applications that require fine display in complex environments.

[0011] Preferably, in the dual optical path structure described in the application, when the projection device Z1 is a single light source, it further includes a plane mirror M71. The plane mirror M71 is placed at any position of the light source light emitting surface. A portion of the light emitted by the single light source is reflected by the plane mirror M71 to form light ray L2, and the other portion is light ray L1. The light rays L1 and L2 combine to form an image light source combination module.

[0012] The application uses the plane mirror M71 to provide a technical solution that can achieve clear images at different focal lengths through the combination of a single light source and a plane mirror M71. This design is relatively simple, and through the optimization of the mirror, the utilization efficiency of the light source can be effectively improved to achieve a continuous depth of field effect.

[0013] Preferably, in the double optical path structure described in the present application, when the projection device Z1 is a single light source, it further comprises a wedge-shaped prism F1 placed at any position of the light source light emitting surface, wherein a part of the light emitted by the single light source is reflected to the second mirror surface through the first mirror surface of the wedge-shaped prism F1, directly transmits through the third mirror surface to refract out, forming the light L2; another part of the light is the light L1; the light L1 and the light L2 combine to form an image light source combination module.

[0014] The present application can realize accurate distribution and guidance of light based on a single light source through the addition of the wedge-shaped prism F1, effectively improving the definition of the image, the utilization rate of the light source, and the overall efficiency of the system. In addition, the design of the wedge-shaped prism F1 can also realize a compact structure, flexible adjustment and simplified optical design, thereby having better adaptability in multiple application scenarios.

[0015] Preferably, in the double optical path structure described in the present application, when the projection device Z1 is a single light source, it further comprises a prism F2 placed at any position of the light source light emitting surface, wherein a part of the light emitted by the single light source is refracted after passing through the first mirror surface of the prism F2, and then transmits through the second mirror surface to refract out, forming the light L2; another part of the light is the light L1; the light L1 and the light L2 combine to form an image light source combination module.

[0016] The present application can realize efficient light distribution and focal length control based on a single light source through the use of the prism F2, while optimizing the continuous depth of field effect and image quality. This structure has the advantages of simplified design, improved optical efficiency, reduced distortion, and reduced cost, and is suitable for various application scenarios that require efficient optical design and high-quality projection.

[0017] Preferably, in the double optical path structure described in the present application, when the projection device Z1 is a single light source, it further comprises a wedge-shaped prism F3 placed at any position of the light source light emitting surface, wherein a part of the light emitted by the single light source is refracted to the second mirror surface through the first mirror surface of the wedge-shaped prism F3, and then refracted to the third mirror surface through the second mirror surface, and then refracted out through the second mirror surface to form the light L2; another part of the light is the light L1; the light L1 and the light L2 combine to form an image light source combination module.

[0018] The present application is based on the double optical path structure design of the wedge-shaped prism F3, which provides a continuous depth of field effect and realizes efficient use of the light source through a single light source and accurate refractive path distribution, reduces the complexity of the system, avoids optical distortion, and has the advantages of high light efficiency, low cost, and high reliability, and is suitable for projection applications with high requirements for image quality and system compactness.

[0019] Preferably, the double light path structure described in the application further comprises a first curved mirror M1 and a second curved mirror M2; wherein,

[0020] The light rays L1 and L2 of the image light source combination module are reflected by the first curved mirror M1 and the second curved mirror M2, and after being reflected by the windshield WS, near distance projection and far distance projection are formed at the virtual image end.

[0021] The double light path structure realizes the continuous depth of field effect through the reflection of the first and second curved mirrors and the additional reflection function of the windshield, and realizes the "one vertical and one inclined" image plane combination mode through the double light path architecture with an angle between the far image plane and the road surface less than 60°, thereby reducing the dizziness caused by the obvious projection distance difference when switching the field of view between the near and far projections, and improving the driving experience of the driver.

[0022] Preferably, the near distance projection and the far distance projection do not have overlapping areas in spatial angle.

[0023] Preferably, the near distance projection is at a spatial distance of 4.5m from the human eye.

[0024] Preferably, the far distance projection is at a spatial distance of 4.6-7.8m from the human eye.

[0025] The double light path structure with continuous depth of field of the far image plane realizes clear and accurate projection effect by accurately setting the spatial distance of the near distance and far distance projection and ensuring that the projection areas of the two do not overlap. Not only the image quality is optimized, but also the user's viewing experience is improved. It is especially suitable for occasions that require precise control of projection distance and focal length, such as virtual reality (VR), augmented reality (AR), vehicle display, etc.

[0026] In a second aspect, the application further provides a head-up display device comprising the double light path structure of the first aspect, the head-up display device further comprising a first curved mirror M1, a second curved mirror M2 and a windshield WS, at least two image planes emitted in the double light path structure enter the first curved mirror M1 and the second curved mirror M2 in turn, and then enter the human eye after being reflected by the windshield WS, and finally form at least two different positions and levels of virtual images in front of the windshield WS.

[0027] The head-up display described in the present application combines a double light path structure with a mirror system, not only forming multiple virtual image levels in front of the windshield to improve the depth and clarity of information display, but also greatly enhancing driving safety, optimizing space utilization, adapting to various environmental lighting conditions, and improving system stability and durability. These technical advantages make the device particularly suitable for information display applications in modern cars, improving driving experience and safety.

[0028] Compared with the prior art, the present application has the beneficial effects that:

[0029] 1. Continuous depth of field and clear virtual image display: multiple virtual images of different distances are formed simultaneously in the same visual area.

[0030] 2. Double light source configuration and light path separation: the appropriate angle between the light sources can effectively separate the light paths, further reducing power consumption of the light sources and increasing the stability and uniformity of the light.

[0031] 3. Optimal configuration of optical elements: different optical elements are added to accurately adjust the path of light through refraction, reflection, etc.

[0032] 4. Use of curved mirrors to improve reflection efficiency: the use of a first curved mirror M1 and a second curved mirror M2 can improve the reflection efficiency of light.

[0033] 5. Non-overlapping area projection: near and far projections do not overlap in spatial angle.

[0034] 6. Enhanced driving safety: the driver does not need to look down at the vehicle dashboard or other display devices, which can effectively reduce the risk of distraction during driving.

[0035] 7. Multi-level virtual image display and user experience: multi-level display can enhance the presentation of information, allowing users to clearly obtain necessary driving data in different situations.

[0036] 8. Adapt to various lighting environments: the windshield as a display medium can work stably under various lighting conditions and is not easily affected by external strong light, sunlight or interior lighting. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a schematic diagram of the internal structure of the head-up display of the present application.

[0038] Figure 2 is a schematic diagram of a double light path structure with continuous depth of field for a far image.

[0039] Figure 3Figure 1 is a schematic diagram of a dual optical path structure with continuous depth of field of a far image according to an embodiment of the present application.

[0040] Figure 4 Figure 1 is a schematic diagram of a dual optical path structure with continuous depth of field of a far image according to an embodiment of the present application.

[0041] Figure 5 Figure 1 is a schematic diagram of a dual optical path structure with continuous depth of field of a far image according to an embodiment of the present application.

[0042] Figure 6 Figure 1 is a schematic diagram of a dual optical path structure with continuous depth of field of a far image according to an embodiment of the present application.

[0043] Figure 7 Figure 1 is a schematic diagram of a dual optical path structure with continuous depth of field of a far image according to an embodiment of the present application.

[0044] Figure 8 Figure 1 is a schematic diagram of a dual optical path structure with continuous depth of field of a far image according to an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative work fall within the scope of protection of the present application.

[0046] Embodiment one, referring to Figure 1 and Figure 2 , the present application proposes a dual optical path structure with continuous depth of field of a far image, the dual optical path structure comprising a projection device Z1, the light emitted by the projection device Z1 forms a close-range projection and a long-range projection at a virtual image end after reflection by a windshield glass WS; wherein the projection device Z1 is a single light source or a dual light source; when the projection device Z1 is a single light source, the emitted light comprises light L1 and light L2; the included angle between the light L1 and the light L2 is greater than 30°; when the projection device Z1 is a dual light source, the included angle between the first light source and the second light source is greater than 25°.

[0047] The head-up display device provided by the utility model forms near distance and far distance projection at the virtual image end through the projection of light rays at different distances, ensures that the objects in the field of view can be kept clear at different distances, and thus realizes the continuous depth of field effect. This has important significance for application scenarios (such as virtual reality, augmented reality, advanced driver assistance systems, etc.) that need to present clear vision in complex or multi-level environments. For example, it can be applied to vehicle-mounted HUDs, projects instrument information, navigation instructions and the like on the front windshield of a vehicle, and the driver does not need to lower his head to check the instrument panel. Or aviation HUD: the pilot obtains flight data through the projection of the front window, and the flight safety is improved.

[0048] The present application can effectively realize more natural and smooth visual transition by controlling the included angle of light rays L1 and L2 (more than 30° when a single light source is used, and more than 25° when double light sources are used), reduce the visual discontinuity or jarring feeling in the traditional projection mode, and improve the visual comfort. The use of single light source or double light source configuration makes the technology more flexible. The single light source configuration simplifies the design and is suitable for cost-sensitive scenarios; and the double light source configuration can provide higher light intensity and precise light path control, and is suitable for scenarios with higher requirements for display effect. Under the projection effect of different distances, the projection distance of different focal lengths can be more accurately controlled, and the adaptability and practicality of the system are improved. Optimizing the light source configuration of the projection device Z1 (especially in the double light source mode) can effectively reduce the light interference between different light sources, improve the accuracy of light projection, optimize the image quality, and is especially suitable for applications that require fine display in complex environments.

[0049] Referring to Figure 3 As shown in the double light path structure described in the present application, when the projection device Z1 is a single light source, it further comprises a plane mirror M71; the plane mirror M71 is placed at any position of the light source light emitting surface, wherein a part of the light emitted by the single light source is reflected by the plane mirror M71 to form light L2; another part of the light is light L1; the light L1 and the light L2 combine to form an image light source combination module.

[0050] The present application provides a technical solution that can realize clear images at different focal lengths by using the plane mirror M71 and the combination of the single light source and the plane mirror M71. It has a relatively simple design, and can effectively improve the utilization efficiency of the light source through the optimization of the mirror, and achieve the visual effect of continuous depth of field.

[0051] Referring to Figure 4As shown, in the double optical path structure described in the present application, when the projection device Z1 is a single light source, further comprising: a wedge-shaped prism F1 placed at any position of the light source light emitting surface, wherein a part of the light emitted by the single light source is reflected to the second mirror surface through the first mirror surface of the wedge-shaped prism F1, directly transmits through the third mirror surface to refract out, forming the light L2; another part of the light is the light L1; the light L1 and the light L2 combine to form an image light source combination module.

[0052] By adding the wedge-shaped prism F1, the projection device Z1 can realize accurate distribution and guidance of light on the basis of a single light source, effectively improving the definition of the image, the utilization rate of the light source and the overall efficiency of the system. In addition, the design of the wedge-shaped prism F1 can also realize a compact structure, flexible adjustment and simplified optical design, thereby having better adaptability in multiple application scenarios.

[0053] Referring to Figure 5 As shown, in the double optical path structure described in the present application, when the projection device Z1 is a single light source, further comprising: a prism F2 placed at any position of the light source light emitting surface, wherein a part of the light emitted by the single light source is refracted after passing through the first mirror surface of the prism F2, and then transmits through the second mirror surface to refract out, forming the light L2; another part of the light is the light L1; the light L1 and the light L2 combine to form an image light source combination module.

[0054] By using the prism F2, this design can realize efficient light distribution and focal length control on the basis of a single light source, while optimizing the continuous depth of field effect and image quality. This structure has the advantages of simplified design, improved optical efficiency, reduced distortion, reduced cost, etc., and is suitable for various application occasions that require efficient optical design and high-quality projection.

[0055] Referring to Figure 6 As shown, in the double optical path structure described in the present application, when the projection device Z1 is a single light source, further comprising: a wedge-shaped prism F3 placed at any position of the light source light emitting surface, wherein a part of the light emitted by the single light source is refracted to the second mirror surface through the first mirror surface of the wedge-shaped prism F3, and then refracted to the third mirror surface through the second mirror surface, and then refracted out through the second mirror surface to form the light L2; another part of the light is the light L1; the light L1 and the light L2 combine to form an image light source combination module.

[0056] The present application is based on the double light path structure design of the wedge prism F3, through a single light source and accurate refraction path distribution, not only provides continuous depth of field effect, but also realizes efficient use of light source, reduces the complexity of the system, avoids optical distortion, and has the advantages of high light efficiency, low cost and high reliability, etc., and is suitable for projection applications with high requirements for image quality and system compactness.

[0057] Referring to Figures 2 to 6 As shown in the figure, the double light path structure further includes the above-mentioned projection device Z1, and further includes a first curved mirror M1 and a second curved mirror M2; wherein,

[0058] The light rays L1 and L2 of the image light source combination module are reflected by the first curved mirror M1 and the second curved mirror M2, and after being reflected by the windshield glass WS, near-distance projection and far-distance projection are formed at the virtual image end.

[0059] This double light path structure provides multiple advantages through the reflection of the first and second curved mirrors and the additional reflection function of the windshield glass, including continuous depth of field, optimized image quality, improved optical efficiency, flexible focal length control, and the ability to adapt to complex environments. Its compact design, improved stability and system reliability are particularly suitable for projection applications with high requirements for image quality, volume and environmental adaptability, such as vehicle-mounted, aviation and mobile devices, etc.

[0060] Referring to Figure 7 As shown in the figure, the near-distance projection and the far-distance projection do not have overlapping areas in the spatial angle.

[0061] In the present application, the near-distance projection is at a spatial distance of 4.5m from the human eye. It is usually used to display more detailed and high-resolution images, such as screen display of personal devices, interactive content, etc.

[0062] The far-distance projection is at a spatial distance of 4.6~7.8m from the human eye. It is usually used to display large-scale and low-resolution images, such as environmental projection, background picture, etc.

[0063] The double light path structure with continuous depth of field of the far image end brings clear and accurate projection effect by accurately setting the spatial distance of near-distance and far-distance projection and ensuring that the projection areas of the two do not overlap. This technology not only optimizes the image quality, but also improves the user's viewing experience, and has wide application potential.

[0064] This structure is particularly suitable for applications that require precise control of projection distance and focal length, such as virtual reality (VR), augmented reality (AR), vehicle-mounted display, etc. These applications usually require precise control of the display range and clarity of images.

[0065] Embodiment two, referring toFigure 7 and Figure 8 As shown in FIG. 1, a head-up display device includes a double light path structure, a first curved mirror M1, a second curved mirror M2, and a windshield WS. At least two image planes emitted in the double light path structure enter the first curved mirror M1 and the second curved mirror M2 in sequence, are reflected by the windshield WS, and finally form at least two virtual images at different positions and levels in front of the windshield WS.

[0066] The head-up display device combines the double light path structure with the mirror system, which not only forms multiple virtual image levels in front of the windshield, enhancing the depth and clarity of information display, but also significantly enhances driving safety, optimizes space utilization, adapts to various environmental lighting conditions, and improves system stability and durability. These technical advantages make the device particularly suitable for information display applications in modern cars, improving driving experience and safety.

[0067] Through the cooperation of the first and second curved mirrors, the clarity and stability of the image are ensured, and optical distortion in traditional display devices is reduced, avoiding the overlap of different projection areas, improving the recognition and accuracy of the image, and improving the comfort of the display, reducing visual fatigue. The device can display multiple key information at the same time, improve the efficiency of driving or observation, ensure image stability and clarity, and maintain optimal display effects even in complex lighting environments. Users can enjoy clear image display without adjusting the focal length. In vehicle head-up display, augmented reality (AR) display, and other scenarios requiring multi-level image display, the device has significant technical competitiveness.

[0068] The present application provides an advanced head-up display device with a continuous depth of field. Through the cooperative work of the image light source combination module and the optical elements, the projection angle, graphic modeling, and software algorithm are optimized, realizing a virtual image that can be clearly displayed at different focal lengths. This greatly improves the display effect of the HUD and the driving experience, enhancing safety and comfort. This technology has wide application prospects, especially in autonomous driving and advanced driver assistance systems (ADAS).

[0069] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above-described example embodiments are merely exemplary and are not intended to limit the scope of the present application. Those of ordinary skill in the art can make various changes and modifications without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as claimed in the appended claims.

[0070] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the description contained herein. That is, although the present application is described in terms of particular embodiments and illustrative figures, persons skilled in the art will recognize that many modifications and changes can be made thereto without departing from the scope of the present application. Thus, the scope of the present application is not to be limited to the descriptions or drawings contained herein but is to be understood as including any equivalents thereof.

[0071] While the application has been described in connection with specific embodiments thereof, it will be understood that many modifications, changes, and variations will be specific to the description contained herein. Accordingly, it is intended to embrace all such modifications, changes, and variations that fall within the spirit and broad scope of the appended claims.

Claims

1. A dual optical path structure with continuous depth of field for a far- field imager, characterized in that, The double light path structure comprises a projection device Z1, light rays emitted by the projection device Z1 form a close-range projection and a long-range projection at the virtual image end after being reflected by the windshield WS; wherein the projection device Z1 is a single light source or a double light source; when the projection device Z1 is a single light source, the light rays emitted by the projection device Z1 comprise light rays L1 and light rays L2; the included angle between the light rays L1 and the light rays L2 is greater than 30°; when the projection device Z1 is a double light source, the included angle between the first light source and the second light source is greater than 25°.

2. The dual optical path structure with continuous depth of field of the far focus according to claim 1, wherein, When the projection device Z1 is a single light source, the double light path structure further comprises a plane mirror M71; the plane mirror M71 is placed at any position of the light emitting surface of the light source, wherein a part of the light rays emitted by the single light source is reflected by the plane mirror M71 to form the light rays L2; the other part of the light rays is the light rays L1; the light rays L1 and the light rays L2 combine to form an image light source combination module.

3. The dual optical path structure with continuous depth of field of claim 1, wherein, When the projection device Z1 is a single light source, the double light path structure further comprises a wedge-shaped prism F1, the wedge-shaped prism F1 is placed at any position of the light emitting surface of the light source, wherein a part of the light rays emitted by the single light source is reflected by the first mirror surface of the wedge-shaped prism F1 to the second mirror surface, directly transmits through the third mirror surface to be refracted out to form the light rays L2; the other part of the light rays is the light rays L1; the light rays L1 and the light rays L2 combine to form an image light source combination module.

4. The dual light path structure with continuous depth of field of claim 1, wherein, When the projection device Z1 is a single light source, the double light path structure further comprises a prism F2, the prism F2 is placed at any position of the light emitting surface of the light source, wherein a part of the light rays emitted by the single light source is refracted by the first mirror surface of the prism F2 after being refracted by the second mirror surface to be refracted out to form the light rays L2; the other part of the light rays is the light rays L1; the light rays L1 and the light rays L2 combine to form an image light source combination module.

5. The dual light path structure with continuous depth of field of claim 1, wherein, When the projection device Z1 is a single light source, the double light path structure further comprises a wedge-shaped prism F3, the wedge-shaped prism F3 is placed at any position of the light emitting surface of the light source, wherein a part of the light rays emitted by the single light source is refracted by the first mirror surface of the wedge-shaped prism F3 to the second mirror surface, is refracted by the second mirror surface to the third mirror surface, and is then refracted out by the second mirror surface to form the light rays L2; the other part of the light rays is the light rays L1; the light rays L1 and the light rays L2 combine to form an image light source combination module.

6. The dual optical path structure with continuous depth of field of any one of claims 2-5, wherein, The projection device Z1 further comprises a first-order curved mirror M1 and a second-order curved mirror M2; wherein, The light rays L1 and the light rays L2 of the image light source combination module are reflected by the first-order curved mirror M1 and the second-order curved mirror M2, and form a close-range projection and a long-range projection at the virtual image end after being reflected by the windshield WS.

7. The double light path structure with continuous depth of field of a far image according to claim 1, wherein The close-range projection and the long-range projection do not have an overlapping area in the spatial angle.

8. The double light path structure with continuous depth of field of a far image according to claim 6, wherein The close-range projection is at a spatial distance of 4.5 m from the human eye.

9. The double light path structure with continuous depth of field of a far image according to claim 6, wherein The long-distance projection is at a spatial distance of 4.6-7.8 m from the human eye.

10. A head-up display device, characterized by comprising: The double optical path structure according to any one of claims 1-5, further comprising a first curved mirror M1, a second curved mirror M2 and a windshield WS, wherein the at least two image planes emitted in the double optical path structure enter the first curved mirror M1 and the second curved mirror M2 in sequence, are reflected by the windshield WS and then enter the human eye, and finally form at least two virtual images at different positions and levels in front of the windshield WS.

Images