Immersed compact long-distance vehicle-mounted head-up display system

Abstract

The utility model discloses an immersed compact long-distance vehicle-mounted head-up display system, which comprises a micro image display, a polygonal curved prism and an automobile front windshield. The polygonal curved surface prism comprises a prism incident surface, a first reflecting surface, a second reflecting surface and an emergent surface, the incident surface, the first reflecting surface and the emergent surface are planes, and the surface type of the second reflecting surface is a six-order XY polynomial free-form surface. Light emitted by the micro-image display enters the incident surface of the polygonal curved prism, sequentially passes through the first reflecting surface and the second reflecting surface and then exits from the emergent surface of the prism to form divergent beams which are emitted to human eyes, and a virtual image is formed on the outer side of a front windshield of an automobile. And human eyes can observe a virtual image formed by reverse extension of the divergent beam at a position 9.5-10.5 m in front of the front windshield of the automobile. The optical system provided by the utility model realizes large-view-field, large-eye-movement-range and long-distance projection imaging, reduces the size to 6.4 L or below on the premise of satisfying better imaging quality, is compact and simple in structure and easy to install and adjust, and has wide application prospects.

Description

Technical Field

[0001] This utility model relates to a vehicle head-up display system for long-distance imaging, belonging to the field of optical technology. Background Technology

[0002] While driving, drivers need to constantly observe the dashboard and road surface to obtain various information such as ever-changing road conditions, speed, and vehicle position. The time a driver takes their eyes off the road to check the dashboard is considered a blind spot, increasing the risk of accidents at high speeds. A head-up display (HUD) system projects driving information through the windshield to a virtual image a certain distance directly in front of the driver's field of vision. The driver can view information such as speed, fuel level, and turn signals without looking down. This is safer for the driver and eliminates the need to constantly adjust their eyes between looking at the road ahead and the nearby instruments, reducing eye strain and significantly improving the driving experience.

[0003] Currently, in-vehicle head-up displays (HUDs) are mainly divided into direct reflection HUDs (C-HUDs), windshield-mounted HUDs (W-HUDs), and augmented reality HUDs (AR-HUDs). C-HUDs use a resin panel placed on the car's dashboard as a connector to display a virtual image. While they are inexpensive and highly adaptable, their imaging area is small, and falling could pose a safety hazard to the driver, leading to their gradual marginalization in the market. W-HUDs use the windshield as the imaging area, offering a larger and farther imaging range than C-HUDs, providing a better viewing experience and driving safety. However, traditional W-HUDs typically have an imaging distance of around 3 meters, causing navigation guidance and turn signals to fail to blend with the real-world scene, potentially interfering with driver judgment in some situations. To achieve a seamless integration with the road surface, the imaging distance for interactive information needs to reach 7 meters or even 10 meters or more.

[0004] Prior to this invention, the literature "Optimization Design of Optical Module for Dual Freeform Surface Head-Up Display System" (Laser & Optoelectronics Progress, 2023, 60(09):360-366) reported a long-distance vehicle head-up display system based on a freeform surface off-axis dual-reflector structure. This system uses the aperture stop offset range (Eyebox) to simulate the driver's field of view movement range and utilizes multiple structures for optimization simulation, ensuring that each field-of-view spot falls within the Airy disk, and that the modulation transfer function of the image approaches the diffraction limit. However, the two reflective surfaces used in this system are both freeform surfaces, leading to significant processing and assembly difficulties. Furthermore, the large Airy disk of this system limits its diffraction limit, resulting in low system resolution. Additionally, the system's large size restricts its applicability, making it unsuitable for use in vehicles with limited available space in the dashboard. Therefore, this system suffers from problems such as high processing and assembly difficulty, low resolution, and large size, limiting its practical application in the field of vehicle projection. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a compact, small-sized vehicle head-up display system with a large field of view and a wide eye-tracking range for long-distance imaging.

[0006] The technical solution to achieve the purpose of this invention is to provide an immersive, compact, long-distance vehicle projection system, which includes a micro-image display, a polygonal curved prism, and a car windshield. The polygonal curved prism includes an incident surface, a first reflecting surface, a second reflecting surface, and an exiting surface. Light emitted from the micro-image display is incident on the incident surface of the polygonal curved prism, passes through the first and second reflecting surfaces in sequence, and exits through the exiting surface. After being reflected by the car windshield, the light enters the human eye. The human eye observes a virtual image formed by the backward extension of the diverging light beam at a distance of 9.5 to 10.5 meters in front of the vehicle through the car windshield.

[0007] The polygonal curved prism has a plane prism incident surface, a first reflecting surface, and a prism exit surface, while the second reflecting surface and the surface shape of the car's windshield are freeform surfaces; the surface shape of the freeform surface is an XY polynomial, and its expression z is:

[0008] ;

[0009] in, c For curvature, k The conic coefficient, A 1~ A 27 These are the coefficients of each polynomial;

[0010] The conicity of the freeform surface of the second reflecting surface (4) satisfies the condition: -0.5≤ kIf ≤0.5, the coefficients of its polynomial satisfy the condition: -0.3≤ A 1≤-0.6、1≤ A 2 ≤4、1≤ A 3≤4、-2≤ A 4≤0、-0.3≤ A 5≤0.3、-0.5≤ A 6≤0.5、0≤ A 7≤2、-0.1≤ A 8≤0.1、-1≤ A 9≤1、-0.1≤ A 10 ≤0.1, -0.1≤ A 11 ≤0.1, -0.2≤ A 12 ≤0.2、-0.1≤ A 13 ≤0.1, -0.2≤ A 14 ≤0.2、-0.1≤ A 15 ≤0.1, -0.1≤ A 20 ≤0.1, -0.05≤ A 21 ≤0.05, -6×10 -3 ≤ A 27 ≤6×10 -3 ;

[0011] The conicity of the freeform surface of the automobile windshield (6) satisfies the condition: -1≤ k ≤1, and the coefficients of its polynomial satisfy the condition: 10≤ A 1≤13、2≤ A 2 ≤5、-2≤ A 3≤2、-1≤ A 4≤1、-1≤ A 5≤1、-0.05≤ A 6≤0.05、-0.5≤ A 7≤0.5、-0.1≤ A 8≤0.1、-0.1≤ A 9≤0.1、-0.1≤ A 10 ≤0.1, -7×10 -3 ≤ A 11 ≤7×10 -3 -0.03≤ A12 ≤0.03, -0.05≤ A 13 ≤0.05, -0.05≤ A 14 ≤0.05, the rest are 0.

[0012] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0013] 1. This utility model integrates a single planar reflective surface and a single freeform reflective surface onto a polygonal curved prism. By optimizing the surface shape and rotation angle of the freeform surface, the system aberrations introduced by the irregular surface shape of the car windshield are balanced, achieving a large field of view and long-distance imaging with a field of view of 10°×5° and a virtual image imaging distance of 10m. It realizes the fusion effect of interactive information of the vehicle head-up display system with the real scene, and expands the eye movement range to 130mm×50mm, meeting the driver's needs for a large observation range and comfortable viewing experience.

[0014] 2. By rationally arranging the reflective surface and introducing a polygonal curved prism made of a material with a high refractive index and a low dispersion coefficient, this utility model increases the refractive index of the light propagation medium, effectively shortens the optical path required for imaging, reduces the volume, and achieves a compact structure.

[0015] 3. The polygonal prism used in this utility model system contains only one free-form reflective surface, while the rest of the surfaces are flat. Compared with the traditional design of 2 to 3 free-form surfaces, this reduces the processing complexity and assembly difficulty of the system.

[0016] 4. This invention significantly improves the system's resolving power by optimizing the material of the polygonal curved prism, the shape of the second reflecting surface, the rotation angle, and the distance between the first and second reflecting surfaces. The detector pixel size used in this system is 75μm, and according to the Nyquist sampling theorem, the system's cutoff frequency is approximately 6.7 lp / mm. Compared to the traditional design where the transfer function across the entire field of view is only 0.4 at 6-7 lp / mm, this system achieves a transfer function of 0.75 at the center of the eye movement range at 6.9 lp / mm, and the transfer function across the entire field of view is greater than 0.55 at 6.9 lp / mm, resulting in good imaging quality and high system resolving power. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the immersion compact long-distance vehicle head-up display system provided in this embodiment of the utility model.

[0018] Figure 2 This is a dot diagram of the vehicle head-up display optical system provided in this embodiment of the utility model.

[0019] Figure 3 This is a field curvature curve diagram of the vehicle head-up display optical system provided in this embodiment of the utility model.

[0020] Figure 4 This is a distortion curve diagram of the vehicle head-up display optical system provided in this embodiment of the utility model.

[0021] Figure 5 This is a graph of the MTF (Mean Transfer Function) of the vehicle head-up display optical system provided in this embodiment of the present invention.

[0022] Among them: 1. Micro-image display; 2. Incident surface of polygonal prism; 3. First reflecting surface of polygonal prism; 4. Second reflecting surface of polygonal prism; 5. Exit surface of polygonal prism; 6. Automobile windshield; 7. Human eye position; 8. Polygonal prism. Detailed Implementation

[0023] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments. Example

[0024] This embodiment provides an immersive, compact, long-range vehicle head-up display system. The system consists of a micro-image display, a polygonal curved prism, and a car windshield. Its field of view is 10° × 5°, eye movement range is 130mm × 50mm, pupil diameter is 6mm, the distance between the human eye and the car windshield is 0.8m, the virtual image display distance is 10m, and its volume is 6.39L. It features a large field of view and eye movement range, long imaging distance, the ability to integrate interactive information with the real scene, a simple and compact structure, and ease of manufacturing and assembly. The performance parameters of the vehicle head-up display system provided in this embodiment are shown in Table 1.

[0025] Table 1:

[0026]

[0027] See appendix Figure 1 This is a schematic diagram of the vehicle head-up display system described in this embodiment. The system includes a micro-image display 1, a polygonal curved prism 8, and a car windshield 6. The polygonal curved prism is provided with a prism incident surface 2, a first reflecting surface 3, a second reflecting surface 4, and a prism exit surface 5. Light emitted from the micro-image display 1 is incident on the incident surface 2 of the polygonal curved prism, and then passes through the first reflecting surface 3 and the second reflecting surface 4 in sequence before exiting from the prism exit surface 5, forming a diverging beam that is directed toward the human eye 7 and forms a virtual image on the outside of the car windshield 6. The human eye can observe the virtual image formed by the backward extension of the diverging beam through the car windshield at a distance of 10m in front.

[0028] In this embodiment, a first three-dimensional rectangular coordinate system (x1, y1, z1) is defined with the center of the human eye 7 as the origin. A horizontal straight line passing through the center of the human eye 7 is the z1 axis, with the right (i.e., pointing towards the windshield) as the positive direction. A second three-dimensional rectangular coordinate system (x2, y2, z2) is defined with the center of the windshield 6 as the origin. The origin of the second three-dimensional rectangular coordinate system (x2, y2, z2) is set at the position (0, -15.4399, 799.8616) of the first three-dimensional rectangular coordinate system (x1, y1, z1), with units in mm. The positive direction of the z2 axis is rotated counterclockwise by 51° to 53° relative to the positive direction of the z1 axis of the first three-dimensional rectangular coordinate system (x1, y1, z1). A third three-dimensional rectangular coordinate system (x3, y3, z3) is defined with the center of the second reflector 4 as the origin. The origin of the third three-dimensional rectangular coordinate system (x3, y3, z3) is set at the position (0, 3.7413, 238.5546) of the second three-dimensional rectangular coordinate system (x2, y2, z2), with the unit being mm. The positive direction of the z2 axis is rotated counterclockwise by 84° to 85° relative to the positive direction of the z2 axis of the second three-dimensional rectangular coordinate system (x2, y2, z2). A fourth three-dimensional rectangular coordinate system (x4, y4, z4) is defined with the center of the first reflecting mirror 3 as the origin. The origin of the fourth three-dimensional rectangular coordinate system (x4, y4, z4) is set at the position (0, -21.4073, 141.2186) of the third three-dimensional rectangular coordinate system (x3, y3, z3), with the unit being mm. The positive direction of the z4 axis is rotated counterclockwise by 0° to 1° relative to the positive direction of the z3 axis of the third three-dimensional rectangular coordinate system (x3, y3, z3). A fifth three-dimensional rectangular coordinate system (x5, y5, z5) is defined with the center of the microdisplay 1 as the origin. The origin of the fifth three-dimensional rectangular coordinate system (x5, y5, z5) is set at the position (0, -10.4561, 89.1351) of the fourth three-dimensional rectangular coordinate system (x4, y4, z4), with the unit being mm. The positive direction of the z5 axis is rotated counterclockwise by 30° to 31° relative to the positive direction of the z4 axis of the fourth three-dimensional rectangular coordinate system (x4, y4, z4).

[0029] Along the direction of light propagation, the distance from the center point of the microdisplay 1 to the center point of the incident surface 2 of the polygonal prism is 3-5 mm, the distance from the center point of the first reflecting surface 3 to the center point of the second reflecting surface 4 is 87-89 mm, the distance from the center point of the first reflecting surface 3 to the center point of the second reflecting surface 4 is 142-144 mm, and the distance from the center point of the second reflecting surface 4 to the center point of the exit surface 5 of the polygonal prism is 90-92 mm.

[0030] In this embodiment, the second reflecting surface 4 of the polygonal prism is a freeform surface with a surface shape of a 6th-order XY polynomial. In the aforementioned third three-dimensional rectangular coordinate system, its surface shape expression z is:

[0031] ;

[0032] in, c For curvature, k The conic coefficient, A 1~ A 27 These are the coefficients of each polynomial; where -0.5 ≤ k If ≤0.5, the coefficients of its polynomial satisfy the condition: -0.3≤ A 1≤-0.6、1≤ A 2 ≤4、1≤ A 3≤4、-2≤ A 4≤0、-0.3≤ A 5≤0.3、-0.5≤ A 6≤0.5、0≤ A 7≤2、-0.1≤ A 8≤0.1、-1≤ A 9≤1、-0.1≤ A 10 ≤0.1, -0.1≤ A 11 ≤0.1, -0.2≤ A 12 ≤0.2、-0.1≤ A 13 ≤0.1, -0.2≤ A 14 ≤0.2、-0.1≤ A 15 ≤0.1, -0.1≤ A 20 ≤0.1, -0.05≤ A 21 ≤0.05, -6×10 -3 ≤ A 27 ≤6×10 -3 .

[0033] In this embodiment, the car windshield 6 is a freeform surface with a surface shape of a fourth-order XY polynomial. In the aforementioned second three-dimensional rectangular coordinate system, its surface shape expression z is:

[0034] ;

[0035] in, c For curvature, k The conic coefficient, A 1~ A 14 These are the coefficients of each polynomial; where -1 ≤ k ≤1, and the coefficients of its polynomial satisfy the condition: 10≤ A1≤13、2≤ A 2 ≤5、-2≤ A 3≤2、-1≤ A 4≤1、-1≤ A 5≤1、-0.05≤ A 6≤0.05、-0.5≤ A 7≤0.5、-0.1≤ A 8≤0.1、-0.1≤ A 9≤0.1、-0.1≤ A 10 ≤0.1, -7×10 -3 ≤ A 11 ≤7×10 -3 -0.03≤ A 12 ≤0.03, -0.05≤ A 13 ≤0.05, -0.05≤ A 14 ≤0.05.

[0036] The specific parameters of each optical element in this embodiment are shown in Table 2.

[0037] Table 2:

[0038]

[0039] Among them, the refractive index of the polygonal prism material is n=1.458, and the Abbe number is v=67.821; the tilt angle of the car windshield 6 relative to the plane where the human eye 7 is located is 52°; the tilt angle of the second reflecting surface 4 of the polygonal prism relative to the plane where the car windshield 6 is located is 84.5°; the tilt angle of the first reflecting surface 3 of the polygonal prism relative to the plane where the second reflecting surface 4 of the polygonal prism is located is 0.5°; and the tilt angle of the microdisplay 1 relative to the plane where the first reflecting surface 3 of the polygonal prism is located is 30.974°.

[0040] See appendix Figure 2 This is a dot plot of the vehicle head-up display optical system provided in this embodiment. Figures (a) and (b) are full-field dot plots of the center and edge image quality worst positions of the eye movement range, respectively. The circles in the figures represent Airy disks. Figure 2 The results show that the root mean square radius of the light spot at the center of the eye movement range and at the edge where the image quality is worst is less than 13.31 μm, which is much smaller than the radius of the Airy disk. In addition, the light spot energy is concentrated and the imaging quality is good.

[0041] See appendix Figure 3This is a field curvature curve diagram of the vehicle head-up display optical system provided in this utility model embodiment. Figures (a) and (b) are the field curvature curve diagrams at the center and edge of the eye movement range, respectively, where the horizontal axis represents the field curvature value and the vertical axis is the normalized field of view. The dashed and solid curves in the figures represent the field curvature in the sagittal and meridional planes, respectively. Figure 3 The results show that the system effectively corrected the field curvature, ensuring that the difference between the two curves, i.e., the astigmatism value, is within the aberration tolerance range.

[0042] See appendix Figure 4 This is a distortion curve diagram of the vehicle head-up display optical system provided in this embodiment of the present invention. Figures (a) and (b) show the distortion curves at the center and edge of the eye movement range, respectively, where the image quality is worst. In the figures, the horizontal axis represents the distortion value as a percentage of the corresponding image height, and the vertical axis is the normalized field of view. Figure 4 The results show that the maximum distortion at the center of the eye movement range is 0.9972%, and the maximum distortion at the edge of the eye movement range is 1.5247%. The system has corrected the distortion well, and no obvious deformation will appear when viewed by the human eye.

[0043] See appendix Figure 5 This is a graph showing the MTF (Mean Transfer Function) curves of the vehicle head-up display optical system provided in this embodiment of the invention; wherein, graphs (a) and (b) correspond to the MTF curves of all fields of view on the image plane corresponding to the center position and the position with the worst image quality at the edge of the eye movement range, respectively. Figure 5 The results show that the optical transfer function of the image plane corresponding to the center of the eye movement range is greater than 0.75 in the entire field of view at 6.9 lp / mm; the optical transfer function of the image plane corresponding to the position with the worst image quality at the edge is greater than 0.55 in the entire field of view at 6.9 lp / mm, which is close to the diffraction limit. The curves are smooth and compact, indicating that the system has clear and uniform imaging and good imaging quality in the entire field of view.

[0044] This invention provides an immersion-type compact vehicle head-up display system with a pupil diameter of 6mm, a virtual image display distance of 10m, a field of view of 10°×5°, and an eye movement range of 130mm×50mm. At a sampling frequency of 6.9lp / mm, the optical transfer function (OPF) of the entire field of view corresponding to the center position of the eye movement range is greater than 0.75, and the OPF of the entire field of view corresponding to the position with the worst image quality at the edge is greater than 0.55, approaching the diffraction limit. This results in good imaging quality, a large field of view, a compact structure, and ease of fabrication and assembly, meeting the application requirements of vehicle head-up displays.

Claims

1. An immersive, compact, long-range vehicle head-up display system, characterized in that: It includes a micro-image display (1), a polygonal prism (8), and a car windshield (6); the polygonal prism (8) includes a prism incident surface (2), a first reflecting surface (3), a second reflecting surface (4), and a prism exit surface (5); the light emitted from the micro-image display is incident on the polygonal prism incident surface, passes through the first reflecting surface and the second reflecting surface in sequence, and exits through the prism exit surface. After being reflected by the car windshield, it enters the human eye (7). The human eye observes the virtual image formed by the backward extension of the diverging light beam at a distance of 9.5 to 10.5 m in front of the car windshield; The prism incident surface (2), the first reflecting surface (3), and the prism exit surface (5) of the polygonal curved prism (8) are planes, while the surface shapes of the second reflecting surface (4) and the windshield (6) of the car are free-form surfaces; the surface shape of the free-form surface is an XY polynomial, and its expression z is: ； in, c For curvature, k The conic coefficient, A 1~ A 27 These are the coefficients of each polynomial; The conicity of the freeform surface of the second reflecting surface (4) satisfies the condition: -0.5≤ k If ≤0.5, the coefficients of its polynomial satisfy the condition: -0.3≤ A 1≤-0.6、1≤ A 2 ≤4、1≤ A 3≤4、-2≤ A 4≤0、-0.3≤ A 5≤0.3、-0.5≤ A 6≤0.5、0≤ A 7≤2、-0.1≤ A 8≤0.1、-1≤ A 9≤1、-0.1≤ A 10 ≤0.1, -0.1≤ A 11 ≤0.1, -0.2≤ A 12 ≤0.2、-0.1≤ A 13 ≤0.1, -0.2≤ A 14 ≤0.2、-0.1≤ A 15 ≤0.1, -0.1≤ A 20 ≤0.1, -0.05≤ A 21 ≤0.05, -6×10 -3 ≤ A 27 ≤6×10 -3 ; The conicity of the freeform surface of the automobile windshield (6) satisfies the condition: -1≤ k ≤1, and the coefficients of its polynomial satisfy the condition: 10≤ A 1≤13、2≤ A 2 ≤5、-2≤ A 3≤2、-1≤ A 4≤1、-1≤ A 5≤1、-0.05≤ A 6≤0.05、-0.5≤ A 7≤0.5、-0.1≤ A 8≤0.1、-0.1≤ A 9≤0.1、-0.1≤ A 10 ≤0.1, -7×10 -3 ≤ A 11 ≤7×10 -3 -0.03≤ A 12 ≤0.03, -0.05≤ A 13 ≤0.05, -0.05≤ A 14 ≤0.05, the rest are 0.

2. The immersive compact long-range vehicle head-up display system according to claim 1, characterized in that: The refractive index n of the polygonal curved prism (8) is in the range of 1.4≤n≤1.5, and the Abbe number v is in the range of 66.8≤v≤68.8.

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