Virtual image projection device
By using the optical path structure of the PGU module, the first reflector, the body holographic lens and the second reflector in the vehicle projection device, a virtual image with a large format and a small brightness disturbance is generated, which solves the shortcomings of the existing vehicle projection device in terms of volume, privacy, frame and brightness, and achieves an efficient projection effect suitable for rear passengers.
Patent Information
- Application Number
- CN202422156576.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-03
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-09-03
AI Technical Summary
The existing on-board projection devices have shortcomings in volume, privacy, frame and brightness due to external light interference, which is particularly difficult to meet the information display and entertainment needs of rear passengers.
The optical path structure including a PGU module, a first reflector, a body holographic lens and a second reflector is adopted. Through the synergistic effect of these optical elements, a virtual image with a large format and a small brightness disturbance is generated, which can only be seen by the human eye located in the eye box, thereby ensuring privacy.
A virtual image projection device with small size, good privacy, large amplitude and low brightness interference from external light is realized. It is suitable for rear passengers and improves the overall performance of the on-board projection device.
Smart Images
Figure CN222994763U_ABST
Abstract
Description
Technical Field
[0001] This solution belongs to the technical field of projection devices, and specifically relates to a virtual image projection device. Background Art
[0002] In-vehicle projection devices, as an important part of modern vehicle interiors, not only provide rich entertainment and information display functions for drivers and passengers, but also play a key role in enhancing driving safety and riding experience. Currently, in-vehicle projection devices on the market are mainly divided into two categories: real image type and virtual image type.
[0003] Real image type projection devices mainly include two solutions: micro-projectors and LCD displays. Micro-projectors are a projection technology that was applied to the in-vehicle environment earlier. Their working principle is similar to that of traditional projectors, which project images onto a screen through a light source, lens, and display chip. However, the volume of micro-projectors is relatively large, imaging requires a certain distance, and the image must rely on a screen to be received to achieve display. Therefore, a relatively large installation space is required, which limits their layout in the vehicle. In addition, the viewing angle of micro-projectors is relatively wide, the privacy is not strong, and the image brightness is easily interfered by ambient light. Especially in strong sunlight or complex in-vehicle lighting conditions, the image quality will drop significantly.
[0004] LCD displays are a relatively mainstream solution in the current in-vehicle display field. Compared with micro-projectors, LCD displays are small in volume and are easily integrated into various parts of the vehicle, such as the center console, instrument panel, etc. However, while the volume is reduced, the screen size is also reduced, generally not exceeding 10 inches. This makes passengers prone to dizziness when viewing, especially during long-term viewing or driving. The visual fatigue problem caused by the small screen is more prominent. In addition, LCD displays also have the problems of wide viewing angle and weak privacy. The brightness is not high, and the image brightness is easily interfered by ambient light, resulting in a poor viewing experience in strong light environments.
[0005] The representative of virtual image type projection devices is the Head-Up Display (HUD). The HUD projects images onto the front windshield through the principle of optical reflection to form virtual images, enabling the driver to view vehicle information or navigation instructions without having to look down. The HUD has extremely strong privacy. Clear images can only be seen within a specific viewing area, which allows the driver to focus on driving without being interfered by other display devices in the vehicle (for example, a HUD specifically set for the co-pilot). At the same time, the HUD has a relatively large frame and can provide more abundant information display. However, the disadvantages of the HUD are also obvious. Since the image enters the human eye through the reflection of the front windshield, its viewing position is relatively fixed and is only suitable for the use of the driver or co-pilot. For rear passengers, the HUD cannot provide effective information display and entertainment functions.
[0006] Therefore, it is necessary to design a projection device that is small in size, has good privacy, has a large picture size, is less affected by external light interference in terms of brightness, and is suitable for rear passengers to use. Summary of the Utility Model
[0007] This solution aims to overcome at least one defect in the prior art and provides a virtual image projection device that is small in size, has good privacy, has a large picture size, is less affected by external light interference in terms of brightness, and is suitable for rear passengers to use.
[0008] To solve the above technical problems, the following technical solutions are adopted:
[0009] A virtual image projection device includes a PGU module, a first reflector, a volume holographic lens, and a second reflector sequentially arranged on the optical path. Among them, the PGU module is used to emit image light beams, the first reflector is used to reflect the image light beams from the PGU module, the volume holographic lens is used to diffract and reflect the image light beams from the first reflector, the second reflector is used to reflect and magnify the image light beams from the volume holographic lens, and the image light beams from the second reflector pass through the volume holographic lens and enter the human eye located in the eye box, forming an enlarged virtual image on the side of the second reflector facing away from the volume holographic lens.
[0010] Through the synergistic effect of the first reflector, the volume holographic lens, and the second reflector, this solution enables the image light beams emitted by the PGU module to present an enlarged virtual image with a large picture size and less affected by external light interference on the side of the second reflector facing away from the volume holographic lens, and this virtual image can only be seen by the human eye located in the eye box, thus ensuring the privacy of viewing. This virtual image does not need to be presented through the front windshield and is suitable for rear passengers to use. Importantly, through the diffraction and reflection of the volume holographic lens, the limitation that the incident angle must be equal to the exit angle in geometric optical reflection is broken, enabling the second reflector to be arranged directly opposite the volume holographic lens without having to be offset by a certain position, which is beneficial to reducing the overall volume of the virtual image projection device.
[0011] For the volume holographic lens and the second reflector, it can be designed such that among the image light beams incident on the volume holographic lens, only the image light beams diffracted and reflected by the volume holographic lens can be incident on the second reflector, avoiding the image light beams reflected by the surface of the volume holographic lens from being incident on the second reflector and entering the human eye, causing double images. The PGU module and the first reflector are preferably arranged above or below the volume holographic lens and the second reflector, which can make the image light beams reflected by the surface of the volume holographic lens propagate upward or downward and will not be received by the eyes of other passengers, further improving the privacy of viewing.
[0012] The transverse length of the eye box is preferably more than 130 millimeters, the longitudinal length is preferably more than 50 millimeters, and the diagonal length of the virtual image is preferably more than 18 inches to ensure the viewing experience.
[0013] The distance d1 between the eye box and the volume holographic lens is preferably 400 to 900 millimeters, and the distance d2 between the virtual image and the eye box is preferably more than 2 meters, so as to be applied as an in-vehicle projection device for rear passengers.
[0014] The angle α between the chief ray of the image beam emitted from the PGU module to the first mirror and the first mirror is 50 to 80 degrees, the angle β between the chief ray of the image beam emitted from the first mirror to the volume holographic lens and the volume holographic lens is 30 to 60 degrees, the length l1 of the chief ray of the image beam emitted from the PGU module to the first mirror is 40 to 120 millimeters, the length l2 of the chief ray of the image beam emitted from the first mirror to the volume holographic lens is 100 to 160 millimeters, and the length l3 of the chief ray of the image beam emitted from the volume holographic lens to the second mirror is 80 to 150 millimeters, so as to minimize the overall volume of the device.
[0015] The surface shape of the second mirror is preferably a free-form surface, which can not only change the propagation direction of the image beam, but also undertake the function of image magnification, so as to obtain a large-format virtual image.
[0016] The surface shape of the first mirror can be a plane, a cylindrical surface, a spherical surface, an aspherical surface or a free-form surface. If the surface shape of the first mirror is a plane, the original size and shape of the image can be kept unchanged, and only the propagation direction of the image beam is changed; if the surface shape of the first mirror is a cylindrical surface, a spherical surface, an aspherical surface or a free-form surface, it can not only change the propagation direction of the image beam, but also undertake the function of image magnification.
[0017] The PGU module can be a DLP optical engine module, an LCOS optical engine module, an LBS optical engine module, an LCD optical engine module or an OLED display module.
[0018] The beneficial effects of this solution compared with the prior art are as follows: Through the synergistic effect of the first mirror, the volume holographic lens and the second mirror, the image beam emitted by the PGU module can present a large-format virtual image with little interference from external light on the side of the second mirror facing away from the volume holographic lens, and this virtual image can only be seen by the human eyes located in the eye box, thus ensuring the privacy of viewing. The virtual image does not need to be presented through the front windshield and is suitable for rear passengers. The key is that through the diffraction reflection of the volume holographic lens, the limitation that the incident angle must be equal to the exit angle in geometric optical reflection is broken, so that the second mirror can be set facing the volume holographic lens without staggering a certain position, which is beneficial to reducing the overall volume of the virtual image projection device. Description of the Drawings
[0019] The accompanying drawings are only for illustrative purposes and should not be construed as limiting the solution; for better illustration of the solution, some components in the drawings are omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.
[0020] Figure 1 It is a schematic diagram of the imaging optical path of a virtual image projection device with a flat virtual image plane.
[0021] Figure 2 It is a schematic diagram of the imaging optical path of a virtual image projection device with an inclined virtual image plane.
[0022] Figure 3 It is a schematic diagram of the imaging optical path of a virtual image projection device with a curved virtual image plane.
[0023] Figure 4 It is a schematic diagram of the structure and optical path of a virtual image projection device.
[0024] Figure 5 It is a schematic diagram of the reflection optical path of a volume holographic lens.
[0025] Figure 6 It is a schematic diagram of the structure and main optical path of a virtual image projection device.
[0026] Explanation of reference numerals: PGU module 100, first reflector 200, volume holographic lens 300, second reflector 400, eye box B, virtual image I. Detailed implementation manners
[0027] To enable those skilled in the art to better understand the solution, the following further details the solution with specific embodiments.
[0028] Figures 1 to 6 It schematically shows a possible virtual image projection device, which includes a PGU module 100, a first reflector 200, a volume holographic lens 300, and a second reflector 400. The PGU module 100, the first reflector 200, the volume holographic lens 300, and the second reflector 400 are sequentially arranged on the optical path.
[0029] The PGU (Picture Generation Unit) module, as an image generation unit, is a core component in various projection display systems such as in-vehicle head-up displays (HUD) and augmented reality head-up displays (AR-HUD). It is responsible for generating high-quality image information and emitting image beams, which are then projected into the line of sight of the driver or passengers through an optical system composed of a first reflector 200, a volume holographic lens 300, and a second reflector 400, providing an intuitive and rich information display and interaction experience. Specifically, the PGU module 100 can be a DLP (Digital Light Processing) optical engine module, an LCOS (Liquid Crystal on Silicon) optical engine module, an LBS (Laser Beam Scanning) optical engine module, an LCD (Liquid Crystal Display) module, an OLED (Organic Light-Emitting Diode) display module, etc.
[0030] The first reflector 200 changes the propagation direction of the image beam from the PGU module 100 through reflection, enabling the image beam to be incident on the volume holographic lens 300. Specifically, the surface shape of the first reflector 200 can be a plane, a cylinder, a sphere, an aspherical surface, or a freeform surface. If the surface shape of the first reflector 200 is a plane, it can maintain the original size and shape of the image and only change the propagation direction of the image beam; if the surface shape of the first reflector 200 is a cylinder, a sphere, an aspherical surface, or a freeform surface, it can not only change the propagation direction of the image beam but also perform the function of image magnification.
[0031] The volume holographic lens 300 changes the propagation direction of the image beam from the first reflector 200 by diffraction and reflection, so that the image beam can be incident on the second reflector 400. Specifically, the volume holographic lens 300 is a special optical element manufactured using volume holographic technology, which is made by recording three-dimensional interference patterns of two or more coherent light beams. These interference patterns are recorded in a material with volume holographic photosensitive properties. When light with an incident angle within a specific range is irradiated on these recorded holographic patterns, diffraction will occur, thereby changing the propagation direction of the light, while light with an incident angle that does not meet the aforementioned specific range will not be diffracted. The aforementioned specific range is related to the incident angle of the coherent light beam during the manufacturing process of the volume holographic lens 300. The volume holographic lens 300 can be designed and manufactured based on the incident angle range of the image beam on the volume holographic lens 300, so that the image beam from the first reflector 200 can be diffracted and reflected by the volume holographic lens 300. Different from a reflective mirror or a semi-transparent and semi-reflective mirror, the volume holographic lens 300 breaks the limitation that the incident angle must be equal to the exit angle in geometric optical reflection through diffraction reflection, so that the second reflective mirror 400 can be set directly opposite the volume holographic lens 300 without having to stagger a certain position, which is beneficial to reducing the overall volume of the virtual image projection device.
[0032] The volume holographic lens 300 usually has a certain thickness, and only the interference pattern recorded inside it can diffract and reflect the image beam, while its surface still follows the geometric optical reflection principle. The image beam reflected by the surface of the volume holographic lens 300 will interfere with the image beam diffracted and reflected by the volume holographic lens 300, causing double images. To this end, by designing the relative size of the volume holographic lens 300 and the second reflector 400, the incident angle of the image beam, etc., it can be made that among the image beams incident on the volume holographic lens 300, only the image beams diffracted and reflected by the volume holographic lens 300 can be incident on the second reflector 400, while the image beams reflected by the surface of the volume holographic lens 300 cannot be incident on the second reflector 400, and thus cannot enter the human eye, thereby reducing or even avoiding double images, such as Figure 5 .
[0033] The second reflector 400 changes the propagation direction and image size of the image beam from the volume holographic lens 300 through reflection and magnification, enabling the image beam to pass through the volume holographic lens 300 and enter the human eye located in the eyebox, forming an enlarged virtual image on the side of the second reflector 400 facing away from the volume holographic lens 300. Specifically, the surface shape of the second reflector 400 is a free-form surface, which can not only change the propagation direction of the image beam but also undertake the function of image magnification to obtain a large-format virtual image. The eyebox is the area where the human eye can view. The image beam reflected by the second reflector 400 will converge in the eyebox, and the reverse extension lines of these image beams will converge into an enlarged virtual image on the side of the second reflector 400 facing away from the volume holographic lens 300. The human eye can only view this virtual image within the eyebox range, which is beneficial to ensuring privacy. Presenting the image information carried by the image beam through the virtual image is beneficial to avoiding the interference of external light on the brightness.
[0034] The PGU module 100 and the first reflector 200 can be arranged above the volume holographic lens 300 and the second reflector 400, or can be arranged below the volume holographic lens 300 and the second reflector 400. Thus, the image beam reflected by the surface of the volume holographic lens 300 will propagate upward or downward and will not be received by the eyes of other passengers, which is beneficial to further improving the privacy of viewing.
[0035] To ensure the viewing experience, when designing, the horizontal length of the eyebox can be designed to be 130 mm or more (including 130 mm), the vertical length can be designed to be 50 mm or more (including 50 mm), and the diagonal length of the virtual image can also be designed to be 18 inches or more (including 18 inches). When applied as an in-vehicle projection device for rear passengers, the distance d1 between the eyebox and the volume holographic lens 300 can be designed to be 400 - 900 mm, and the distance d2 between the virtual image and the eyebox can also be designed to be 2 m or more (including 2 m). The plane where the virtual image is located can be designed as a flat surface (such as Figure 1 ), an inclined surface (such as Figure 2 ), or a curved surface (such as Figure 3 ) and other surface shapes to obtain a better viewing experience.
[0036] To minimize the overall volume of the device, the relative positions of the PGU module 100, the first reflector 200, the volume holographic lens 300, and the second reflector 400 can be restricted. Such as Figure 6As shown, the angle α between the chief ray of the image beam emitted from the PGU module 100 to the first mirror 200 can be designed to be 50 to 80 degrees, the angle β between the chief ray of the image beam emitted from the first mirror 200 to the volume holographic lens 300 can be designed to be 30 to 60 degrees, the length l1 of the chief ray of the image beam emitted from the PGU module 100 to the first mirror 200 can be designed to be 40 to 120 millimeters, the length l2 of the chief ray of the image beam emitted from the first mirror 200 to the volume holographic lens 300 can be designed to be 100 to 160 millimeters, and the length l3 of the chief ray of the image beam emitted from the volume holographic lens 300 to the second mirror 400 can be designed to be 80 to 150 millimeters.
[0037] Obviously, the above-mentioned embodiments of this solution are merely examples for clearly illustrating this solution, rather than limitations on the implementation manners of this solution. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this solution shall be included in the protection scope of the claims of this solution.
Claims
1. A virtual image projection device, characterized in that: The virtual image projection device includes a PGU module, a first reflector, a volume holographic lens and a second reflector which are sequentially arranged on an optical path. The PGU module is used to emit an image light beam. The first reflector is used to reflect the image light beam from the PGU module. The volume holographic lens is used to diffract and reflect the image light beam from the first reflector. The second reflector is used to reflect and amplify the image light beam from the volume holographic lens. The image light beam from the second reflector passes through the volume holographic lens and enters the human eye located in the eye box, forming an amplified virtual image on the side of the second reflector facing away from the volume holographic lens.
2. The virtual image projection device according to claim 1, characterized in that: Among the image light beams incident on the volume holographic lens, only the image light beams diffracted and reflected by the volume holographic lens can be incident on the second reflecting mirror.
3. The virtual image projection device according to claim 1, characterized in that: The PGU module and the first reflector are arranged above or below the volume holographic lens and the second reflector.
4. The virtual image projection device according to any one of claims 1 to 3, characterized in that: The eye box has a lateral length of more than 130 mm and a longitudinal length of more than 50 mm.
5. The virtual image projection device according to any one of claims 1 to 3, characterized in that: The virtual image has a diagonal length of more than 18 inches.
6. The virtual image projection device according to any one of claims 1 to 3, characterized in that: The distance d1 between the eye box and the volume holographic lens is 400-900 mm.
7. The virtual image projection device according to any one of claims 1 to 3, characterized in that: The distance d2 between the virtual image and the eye box exceeds 2 meters.
8. The virtual image projection device according to any one of claims 1 to 3, characterized in that: The angle α between the main ray of the image light beam emitted from the PGU module to the first reflector and the first reflector is 50 to 80 degrees, the angle β between the main ray of the image light beam emitted from the first reflector to the volume holographic lens and the volume holographic lens is 30 to 60 degrees, the length l1 of the main ray of the image light beam emitted from the PGU module to the first reflector is 40 to 120 mm, the length l2 of the main ray of the image light beam emitted from the first reflector to the volume holographic lens is 100 to 160 mm, and the length l3 of the main ray of the image light beam emitted from the volume holographic lens to the second reflector is 80 to 150 mm.
9. The virtual image projection device according to any one of claims 1 to 3, characterized in that: The surface shape of the second reflector is a free-form surface.
10. The virtual image projection device according to any one of claims 1 to 3, characterized in that: The surface shape of the first reflector is a plane, a cylinder, a spherical surface, an aspherical surface or a free-form surface; and / or The PGU module is a DLP optical machine module, an LCOS optical machine module, an LBS optical machine module, an LCD optical machine module or an OLED display module.