Head-up display system based on two-dimensional geometric array waveguide

Abstract

The present invention relates to a head-up display system based on a two-dimensional geometric array waveguide. This system comprises an image generation unit and at least two one-dimensional array waveguides. The one-dimensional array waveguides are composed of multiple sub-prisms, each with an angle-selective reflective film on its inclined surface. The system also includes a Fresnel lens component and a diffractive optical element. The Fresnel lens component is used to compensate for aberrations introduced by the vehicle windshield, while the diffractive optical element is used to expand the optical etendue. The technical solution of the present invention can achieve a larger display range without significantly increasing the size of the vehicle head-up display system.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile head-up display, and in particular to a head-up display system based on a two-dimensional geometric array waveguide. Background Art

[0002] Driven by the modern automotive industry and intelligent driving technologies, head-up displays (HUDs) are becoming an increasingly important means of visualizing vehicle information. By projecting critical information such as speed, navigation instructions, and warning alerts directly into the driver's field of view, they reduce the need to glance down at the instrument panel, improving both safety and comfort. Compared to traditional instrument clusters or central control screens, HUDs offer a more immersive driving environment and increase reaction time in emergencies. This holds significant potential for application in high-end vehicles and in the future of autonomous driving.

[0003] The earliest Combiner Head-Up Display (called "synthetic mirror head-up display" in the existing technology) usually requires an additional independent imaging plate in front of the windshield, which not only increases the system volume but also makes the vehicle structure more complex. The subsequently developed Windshield Head-Up Display (called "windshield head-up display"), although it uses the windshield as a reflective mirror, still has difficulty in achieving a significantly expanded display range within a limited space. Moreover, when the windshield curvature is more complex, aberration correction is also more difficult. The augmented reality head-up display technology that has emerged in recent years superimposes real-time traffic instructions and auxiliary information on the traditional head-up display, but there is still a trade-off between field of view coverage, system compactness and imaging quality. How to achieve a larger display range without significantly increasing the overall system volume, so that the driver can obtain a wider range of information projection within the relatively limited cockpit space, has become a technical problem that technicians in this field urgently need to solve. Summary of the Invention

[0004] The main purpose of the present invention is to solve the technical problem that existing automobile head-up display systems are difficult to achieve a larger display range without significantly increasing the system volume.

[0005] A first aspect of the present invention provides a head-up display system based on a two-dimensional geometric array waveguide, wherein the head-up display system based on a two-dimensional geometric array waveguide includes an image generation unit and an array waveguide;

[0006] The arrayed waveguide comprises:

[0007] A plurality of sub-prisms arranged along a first direction, each of the sub-prisms having a first inclined surface, a second inclined surface, an upper surface, and a lower surface;

[0008] The plurality of upper surfaces are sequentially connected to form an upper end surface of the arrayed waveguide, and the plurality of lower surfaces are sequentially connected to form a lower end surface of the arrayed waveguide;

[0009] A first preset angle is formed between the first inclined surface and the lower end surface;

[0010] A plurality of the first inclined surfaces and a plurality of the second inclined surfaces are alternately arranged along the first direction and are parallel to each other;

[0011] The first inclined surface of the first sub-prism and the second inclined surface of the last sub-prism are both provided with total reflection films, and the first inclined surfaces of the sub-prisms except the first sub-prism are all provided with angle selective transmission reflection films;

[0012] The light coupling-in area of ​​the arrayed waveguide is arranged on the lower surface of the first sub-prism, and the light coupling-out area is arranged on the upper end surface; wherein,

[0013] The light generated by the image generating unit enters the arrayed waveguide through the light coupling-in region, and is reflected back and forth between the upper end face and the lower end face by the total reflection film of the first sub-prism at a total reflection critical angle not less than that of the upper end face and the lower end face;

[0014] The angle selectively transparent reflective film is configured to transmit part of the incident light and reflect the remaining incident light, and a part of the light reflected by the angle selectively transparent reflective film among all the angle selectively transparent reflective films is emitted toward the upper end surface and transmitted through at a total reflection critical angle smaller than the upper end surface, and another part of the light reflected by the angle selectively transparent reflective film is emitted toward the lower end surface, and after being reflected at the lower end surface, is emitted toward the upper end surface and transmitted through at a total reflection critical angle smaller than the upper end surface.

[0015] Optionally, in the first direction, the reflectivity of the angle selective transmission reflective film is The following relationship is satisfied:

[0016] ;

[0017] in, is the serial number of the angle selective transmission reflective film, and its value range is 1 to M, where M is the total number of first inclined surfaces provided with the angle selective transmission reflective film in the arrayed waveguide.

[0018] Optionally, the first preset angle is ;

[0019] The light generated by the image generation unit has a predetermined viewing angle, and the half angle of the predetermined viewing angle is ;

[0020] and The following relations are satisfied:

[0021] ;

[0022] ;

[0023] ;

[0024] ;

[0025] in, is the refractive index of the array waveguide.

[0026] Optionally, the number of the arrayed waveguides is at least two, and all the arrayed waveguides include a first arrayed waveguide arranged along the first direction, and a second arrayed waveguide arranged along a second direction perpendicular to the first direction, wherein:

[0027] The light coupling-in region of the first arrayed waveguide is connected to the image generating unit, and the light coupling-out region of the first arrayed waveguide is connected to the light coupling-in region of the second arrayed waveguide, so that light propagates and expands the pupil through the first arrayed waveguide and the second arrayed waveguide in sequence.

[0028] Optionally, a car windshield is arranged on the light emitting path of the second array waveguide, and a Fresnel lens component is provided between the car windshield and the second array waveguide, and the Fresnel lens component is configured to compensate for the aberration introduced by the car windshield in different directions.

[0029] Optionally, the Fresnel lens component includes a first cylindrical Fresnel lens and a second cylindrical Fresnel lens, and the first cylindrical Fresnel lens and the second cylindrical Fresnel lens are stacked;

[0030] The first cylindrical Fresnel lens includes a first substrate and a first Fresnel structure provided on the first substrate;

[0031] The second cylindrical Fresnel lens includes a second substrate and a second Fresnel structure provided on the second substrate;

[0032] The first Fresnel structure extends along a third direction, and the second Fresnel structure extends along a fourth direction perpendicular to the third direction.

[0033] Optionally, the radial cross-sections of the first Fresnel structure and the second Fresnel structure have the same sag expression as the even-order aspheric surface, and the sag expression is:

[0034] ;

[0035] in, is the base curvature coefficient, is the curvature, is the distance from the point on the aspheric surface to the optical axis, is the cone coefficient, is the aspheric coefficient; is the y coordinate of the point on the surface, The value range is 1 to 16.

[0036] Optionally, the head-up display system based on a two-dimensional geometric array waveguide also includes a diffraction optical element, which is arranged at the exit pupil of the image generation unit or the entrance pupil of the array waveguide. The diffraction optical element is used to expand the optical expansion, and the pixel size of the diffraction optical element is smaller than the pixel size of the spatial light modulator in the image generation unit.

[0037] Optionally, two adjacent sub-prisms in the arrayed waveguide are fixed by bonding.

[0038] The head-up display system based on a two-dimensional geometric array waveguide described in this invention gradually expands the display range within a limited space by multiple reflections and partial transmissions of light within the waveguide, thereby achieving a wider projection range without significantly increasing the system's volume. The key lies in the rational design of the inclined surfaces of the sub-prisms, the application of total reflection films on the first and last sub-prisms to maintain efficient light propagation, and the placement of angle-selective reflective films on the intermediate sub-prisms to couple out some light in batches. Because the sub-prisms are alternately arranged within the same waveguide structure, light is guided through total reflection or transmission each time it encounters an inclined surface, thereby extending the optical path and gradually expanding it in both the horizontal and vertical directions, ultimately forming a large display range.

[0039] Unlike traditional technologies that rely on bulky mirrors or the installation of multiple layers of lenses to expand the field of view, this invention achieves efficient light coupling and expansion within the waveguide. Multiple reflections avoid significant scattering losses, while moderate transmission allows some light to be emitted at the optimal time. This significantly improves the visual range and imaging uniformity while maintaining the overall system compactness. This arrangement effectively overcomes the technical bottleneck of existing head-up display systems, which have limited the ability to achieve a larger display range. It lays a solid foundation for providing a head-up display with a wide field of view and stable imaging quality within the limited cockpit space. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0041] Figure 1 Schematic diagram of the structure of an embodiment of a head-up display system based on a two-dimensional geometric array waveguide according to the present invention;

[0042] Figure 2 Schematic diagram of the structure of another embodiment of the head-up display system based on a two-dimensional geometric array waveguide of the present invention;

[0043] Figure 3 is a schematic diagram of light propagating on the first array waveguide;

[0044] Figure 4 Schematic diagram of the principle based on the first arrayed waveguide;

[0045] Figure 5 Schematic diagram of the structure of Fresnel lens components;

[0046] Figure 6 This is a display diagram of the car windshield aberration corrected and not corrected.

[0047] Description of Figure Numbers:

[0048] 1. Image generation unit; 2. First arrayed waveguide; 21. Sub-prism; 211. First inclined surface; 212. Second inclined surface; 213. Upper surface; 214. Lower surface; 22. Upper end surface; 23. Lower end surface; 3. Second arrayed waveguide; 4. Fresnel lens component; 41. First cylindrical Fresnel lens; 42. Second cylindrical Fresnel lens; 5. Automobile windshield.

[0049] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0051] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0052] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, and must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0053] The present invention proposes a head-up display system based on a two-dimensional geometric array waveguide.

[0054] In the embodiment of the present invention, Figures 1 to 6 As shown, the head-up display system based on the two-dimensional geometric array waveguide type includes an image generation unit 1 and an array waveguide;

[0055] The arrayed waveguide comprises:

[0056] A plurality of sub-prisms 21 arranged along a first direction, each of the sub-prisms 21 having a first inclined surface 211, a second inclined surface 212, an upper surface 213 and a lower surface 214;

[0057] The plurality of upper surfaces 213 are sequentially connected to form the upper end surface 22 of the arrayed waveguide, and the plurality of lower surfaces 214 are sequentially connected to form the lower end surface 23 of the arrayed waveguide;

[0058] A first preset angle is formed between the first inclined surface 211 and the lower end surface 23;

[0059] The plurality of first inclined surfaces 211 and the plurality of second inclined surfaces 212 are alternately arranged along the first direction and are parallel to each other;

[0060] The first inclined surface 211 of the first sub-prism 21 and the second inclined surface 212 of the last sub-prism 21 are both provided with total reflection films, and the first inclined surfaces 211 of the sub-prisms 21 other than the first sub-prism 21 are all provided with angle selective transmission reflection films;

[0061] The light coupling-in area of ​​the arrayed waveguide is arranged on the lower surface 214 of the first sub-prism 21, and the light coupling-out area is arranged on the upper end surface 22; wherein,

[0062] The light generated by the image generating unit 1 enters the arrayed waveguide through the light coupling-in region, and is reflected back and forth between the upper end surface 22 and the lower end surface 23 by the total reflection film of the first sub-prism 21 at a total reflection critical angle not less than that of the upper end surface 22 and the lower end surface 23;

[0063] The angle selectively transparent reflective film is configured to transmit part of the incident light and reflect the remaining incident light, and a part of the light reflected by the angle selectively transparent reflective film among all the angle selectively transparent reflective film is emitted toward the upper end surface 22 and transmitted through at a total reflection critical angle smaller than the upper end surface 22, and another part of the light reflected by the angle selectively transparent reflective film is emitted toward the lower end surface 23, and after being reflected at the lower end surface 23, is emitted toward the upper end surface 22 and transmitted through at a total reflection critical angle smaller than the upper end surface 22.

[0064] Specifically, the image generation unit 1 can be a thin-film transistor-liquid crystal display (TFT-LCD), a thin-film transistor-liquid crystal display (DLP), a thin-film transistor-liquid crystal display (LCOS), a micro-light emitting diode display (Micro-LED), a micro holographic light engine, etc., without any specific limitation herein.

[0065] The arrayed waveguide consists of multiple sub-prisms 21, which can be made of polymethyl methacrylate (PMMA) or optical glass. The surfaces of the sub-prisms 21 are precision-machined to a nanometer-level roughness to ensure efficient light transmission. The size of the sub-prisms 21 can be adjusted to meet application requirements.

[0066] Totally reflective films can be produced through vacuum evaporation or magnetron sputtering. Common materials include aluminum, silver, or gold. Dielectric multilayers can also be used to improve reflectivity and durability. The film thickness can range from tens to hundreds of nanometers. The preparation of angle-selective reflective films requires precise control of their transmittance and reflectivity. This can be achieved by adjusting the film thickness or using a combination of different materials, such as partially transparent silver films or dielectric multilayers.

[0067] The sub-prisms 21 are connected with each other using optical grade ultraviolet (UV) curing adhesive, whose refractive index matches the material of the sub-prisms 21. After bonding, heat treatment or UV curing is performed to enhance the structural strength.

[0068] It should be noted that when light travels from a denser medium (with a higher refractive index) to a less dense medium (with a lower refractive index), if the angle of incidence is greater than a certain angle, the light will not be able to pass through the interface between the two media and will be completely reflected back to the denser medium. This angle is called the critical angle of total reflection.

[0069] It's easy to understand that the head-up display system based on a two-dimensional geometric array waveguide described in the present invention gradually expands the display range within a limited space by multiple reflections and partial transmissions of light within the waveguide, thereby achieving a wider projection range without significantly increasing the system's volume. The key lies in the rational design of the inclined surfaces of the sub-prisms 21, the placement of total reflection films on the first and last sub-prisms 21 to maintain efficient light propagation, and the placement of angle-selective reflective films on the intermediate sub-prisms 21 to couple out some light in batches. Because the sub-prisms 21 are alternately arranged within the same waveguide structure, light is guided to undergo total reflection or transmission each time it encounters an inclined surface, thereby extending the optical path and gradually expanding it in the horizontal and vertical directions, ultimately forming a large display range.

[0070] Unlike traditional technologies that rely on bulky mirrors or the installation of multiple layers of lenses to expand the display range, this invention achieves efficient light coupling and expansion within the waveguide. Multiple reflections avoid significant scattering losses, while moderate transmission allows some light to be emitted at the optimal time. This significantly improves the visual range and imaging uniformity while maintaining the overall system compactness. This arrangement effectively overcomes the technical bottleneck of existing head-up display systems, which have limited the ability to achieve a larger display range. It lays a solid foundation for providing a head-up display with a wide field of view and stable imaging quality within the limited cockpit space.

[0071] like Figure 3As shown, the arrayed waveguide is composed of multiple sub-prisms 21 assembled in sequence. In the figure, S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, and S14 are all surfaces of the sub-prisms 21. Specifically, the odd-numbered surfaces S1, S3, S5, S7, S9, S11, and S13 are first inclined surfaces 211, while the even-numbered surfaces S2, S4, S6, S8, S10, S12, and S14 are second inclined surfaces 212. The first inclined surface 211 (i.e., S1) of the first sub-prism 21 of the arrayed waveguide and the second inclined surface 212 (i.e., S14) of the last sub-prism 21 are provided with a total reflection coating. Subsequently, the first inclined surfaces 211 (i.e., S3, S5, S7, S9, S11, and S13) of the sub-prisms 21 other than the first sub-prism 21 are provided with an angle-selective transmission reflective coating.

[0072] In order to ensure the uniformity of the output light distribution and the consistency of the imaging brightness, multiple angle selective transmission reflective films need to be designed with different reflectivities and transmittances, so that the light can be reflected or transmitted according to the preset ratio when passing through each prism. Specifically, in the first direction, the reflectivity of the angle selective transmission reflective films coated on the S3, S5, S7, S9, S11, and S13 surfaces calculated according to the light intensity is The following relationship is satisfied:

[0073] ;

[0074] in, is the serial number of the angle selective transmission reflective film, and its value range is 1 to M, where M is the total number of first inclined surfaces provided with the angle selective transmission reflective film in the arrayed waveguide.

[0075] In this geometric array structure, after light is coupled into the arrayed waveguide, it is first retained within the waveguide by the total reflection coating of the first sub-prism 21. It then encounters successively different angle-selective reflective coatings with varying reflectivity. Each interaction results in partial transmission and reflection based on the coating design, gradually decoupling the light from the waveguide. By designing these different angle-selective reflective coatings with varying reflectivity, the attenuation of light across the sub-prisms 21 is more effectively distributed, preventing excessive attenuation in the initial stage while ensuring sufficient brightness at the final stage.

[0076] like Figure 4The figure shows a schematic diagram of the principle based on the array waveguide, the basic principle of which is that the central field of view light, the edge field of view light and the light sandwiched between the two light rays satisfy the law of total reflection, and can be totally reflected and propagated with the wall of the sub-prism 21 in the array waveguide. Because angle selective transmittance reflective films with different reflectivities are coated between the sub-prisms 21, such as angle selective transmittance reflective films are coated between the S2 surface of the sub-prism 21 and the S3 surface of the sub-prism 21. When light rays of various angles are incident on the surface where the angle selective transmittance reflective film is located, light rays of different incident angles are either transmitted or reflected, and finally the transmission of light rays with a fixed light intensity and the reflection of light rays with a fixed light intensity are realized. The angle selective transmittance reflective films with different reflectivities of the array are used to realize the reflection of multiple incident light rays, thereby realizing the pupil expansion of the coupled light rays. In order to reduce stray light and enable the incident light rays to be totally reflected in the array waveguide, specifically, the first preset angle is ;

[0077] The light generated by the image generation unit 1 has a predetermined viewing angle, and the half angle of the predetermined viewing angle is ;

[0078] and The following relations are satisfied:

[0079] ;

[0080] ;

[0081] ;

[0082] ;

[0083] in, is the refractive index of the array waveguide.

[0084] The present invention can be based on the refractive index n of the waveguide material and the required viewing angle. To reasonably set the first preset angle , thereby achieving the optimal design solution that balances full reflection efficiency and wide display coverage. For head-up display systems, within the limited installation space, it is necessary to ensure that light is reflected multiple times to improve light energy utilization while ensuring that the imaging range is wide enough to meet the driver's visual needs.

[0085] Optionally, the number of the arrayed waveguides is at least two, and all the arrayed waveguides include a first arrayed waveguide 2 arranged along the first direction, and a second arrayed waveguide 3 arranged along a second direction perpendicular to the first direction, wherein:

[0086] The light coupling-in region of the first arrayed waveguide 2 is connected to the image generating unit 1, and the light coupling-out region of the first arrayed waveguide 2 is connected to the light coupling-in region of the second arrayed waveguide 3, so that light propagates and expands the pupil through the first arrayed waveguide 2 and the second arrayed waveguide 3 in sequence.

[0087] Specifically, the number of arrayed waveguides can be two, three, four, etc., and the sizes of the sub-prisms 21 of each arrayed waveguide can be set to be different, which is not limited here.

[0088] This application takes two arrayed waveguides as an example. During assembly, the assembly can be performed in the following order: first, the corresponding end faces of the sub-prisms 21 of the first arrayed waveguide 2 and the second arrayed waveguide 3 are coated with angle-selective transmittance reflective films with corresponding reflectivities; second, the coated sub-prisms 21 are glued together to form the first arrayed waveguide 2 and the second arrayed waveguide 3; third, the outcoupling region of the first arrayed waveguide 2 is matched with the incoupling region of the second arrayed waveguide 3 and glued together, finally forming a two-dimensional geometric arrayed waveguide.

[0089] Compared to arranging the sub-prism 21 or waveguide structure in a single direction only, by adding an additional arrayed waveguide in the second direction, the light can be coupled and expanded in two orthogonal axes respectively, so that the waveguide system that can only achieve one-dimensional linear expansion can be transformed into a system that can perform two-dimensional expansion. Specifically, if the first arrayed waveguide 2 is responsible for reflecting and transmitting the light multiple times in the horizontal direction, then the second arrayed waveguide 3 connected vertically to it can continue to repeat the same process in the vertical direction or another orthogonal direction, thereby completing the coupling, compensation and emission of light over a larger range. In this way, the head-up display system can not only provide wide image coverage in the horizontal direction, but also further increase the visible area in the vertical direction to meet the diversified display requirements of different car models and driving needs. Especially in limited installation space, the combination of these two levels of arrayed waveguides can achieve higher light energy utilization and a wider display range than a single-stage waveguide, significantly enhancing the adaptability and clarity of the head-up display in real road scenes.

[0090] Optionally, a car windshield 5 is arranged on the light emitting path of the second arrayed waveguide 3, and a Fresnel lens component 4 is provided between the car windshield 5 and the second arrayed waveguide 3, and the Fresnel lens component 4 is configured to compensate for the aberration introduced by the car windshield 5 in different directions.

[0091] After emitting from the second arrayed waveguide 3, light must pass through the car's windshield 5 before being projected into the driver's field of view. If the windshield is non-planar or has irregular curvature, this can cause distortion or aberration of the light as it passes through the interface. The additional Fresnel lens component 4 corrects or corrects any aberrations in the light before it enters the windshield, ensuring that the image ultimately projected to the driver remains clear and distortion-free.

[0092] It is not difficult to understand that the introduction of the Fresnel lens component 4 can effectively compensate for the complex aberrations caused by the curvature of the windshield without changing the existing structure of the windshield, thereby ensuring that the large field of view is not seriously damaged by the surface distortion when projected into the driver's field of view.

[0093] Specifically, the Fresnel lens component 4 includes a first cylindrical Fresnel lens 41 and a second cylindrical Fresnel lens 42 , and the first cylindrical Fresnel lens 41 and the second cylindrical Fresnel lens 42 are stacked;

[0094] The first cylindrical Fresnel lens 41 includes a first substrate and a first Fresnel structure provided on the first substrate;

[0095] The second cylindrical Fresnel lens 42 includes a second substrate and a second Fresnel structure provided on the second substrate;

[0096] The first Fresnel structure extends along a third direction, and the second Fresnel structure extends along a fourth direction perpendicular to the third direction.

[0097] Specifically, see Figure 5 A "Fresnel structure" involves breaking down the continuous curved surface of a traditional convex or concave lens into multiple steps, either ring-shaped or strip-shaped. This approach, through multiple approximations, achieves an optical focusing or diverging effect similar to that of a complete curved surface. This effectively reduces the thickness and weight of the lens while allowing for the refraction and correction of light in different directions as needed. For example, the first cylindrical Fresnel lens 41 and the second cylindrical Fresnel lens 42 can be cut or engraved in different directions, creating concave or serrated Fresnel structures with varying refractive powers in the horizontal and vertical directions. This reduces the assembly difficulty and optical cost of the two-dimensional waveguide when combined with the windshield.

[0098] In this solution, when the first cylindrical Fresnel lens 41 and the second cylindrical Fresnel lens 42 are stacked or closely attached, the Fresnel structures extending in the third and fourth directions, respectively, can correct aberrations in different dimensions. Because windshields are not strictly uniaxially symmetrical, double curvature or aspheric components in both the transverse and longitudinal directions often need to be considered: the first cylindrical Fresnel lens 41 primarily corrects some aberrations in the third direction; the second cylindrical Fresnel lens 42 corrects distortion in the fourth direction, perpendicular to the third. By machining corresponding stepped or annular tooth structures on each cylindrical Fresnel lens, the light beam propagation paths in two orthogonal directions can be optimized while maintaining a low overall lens thickness. This reduces manufacturing complexity.

[0099] Specifically, the radial cross-sections of the first Fresnel structure and the second Fresnel structure have the same sag expression as the even-order aspheric surface, and the sag expression is:

[0100] ;

[0101] in, is the base curvature coefficient, is the curvature, is the distance from the point on the aspheric surface to the optical axis, is the cone coefficient, is the aspheric coefficient; is the y coordinate of the point on the surface, The value range is 1 to 16.

[0102] This sag expression specifies a method for describing aspheric free-form surfaces that can be shared and implemented by the first and second Fresnel structures. This allows the present invention to achieve sufficient flexibility and precision in windshield and waveguide lamination and image distortion correction. In other words, while ensuring that the overall thickness of the lens or reflective surface is not excessive, this high-order aspheric polynomial correction effectively reduces aberrations caused by complex curvature, enabling heads-up displays to achieve a balance between a large display range and high image quality.

[0103] Optionally, the head-up display system based on a two-dimensional geometric array waveguide also includes a diffractive optical element, which is arranged at the exit pupil of the image generation unit 1 or the entrance pupil of the array waveguide. The diffractive optical element is used to expand the optical extension, and the pixel size of the diffractive optical element is smaller than the pixel size of the spatial light modulator in the image generation unit 1.

[0104] Specifically, the principle of a diffractive optical element is to etch or emboss a multi-level diffraction structure (such as fine annular diffraction patterns or a two-dimensional grating) on ​​its surface, causing the incident light beam to undergo diffraction distribution or phase modulation as it passes through the element, thereby achieving a large diffusion angle or focusing capability within a relatively small physical size. Because its pixel size is much smaller than the spatial light modulator pixels commonly used in PGUs and can be optimized using neural network algorithms or other design methods, it can significantly increase the optical entendre at the exit pupil without significantly increasing the system volume.

[0105] Optionally, two adjacent sub-prisms 21 in the arrayed waveguide are fixed by bonding.

[0106] Specifically, the docking surfaces of adjacent sub-prisms 21 often need to fit tightly together to ensure seamless transmission and reflection of light between the two prisms. Adopting optical glue, UV glue or other transparent polymer materials for bonding can not only ensure sufficient mechanical strength and stability, but also effectively control the refractive index transition at the connection point, so that the interface between the sub-prisms 21 does not produce additional scattering or deflection. Through this bonding and fixing method, a continuous and stable light channel can be formed inside the array waveguide, so that multiple total reflections and angle-selective transmission and reflection processes can be carried out smoothly at the connection point of adjacent sub-prisms 21, thereby maintaining the predetermined imaging quality and optical uniformity, and laying a solid foundation for designs such as windshield compensation or Fresnel lens correction.

[0107] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A head-up display system based on a two-dimensional geometric array waveguide, characterized in that: It includes an image generating unit (1) and an array waveguide; The arrayed waveguide comprises: A plurality of sub-prisms (21) arranged along a first direction, each sub-prism (21) having a first inclined surface (211), a second inclined surface (212), an upper surface (213), and a lower surface (214); The plurality of upper surfaces (213) are sequentially connected to form the upper end surface (22) of the arrayed waveguide, and the plurality of lower surfaces (214) are sequentially connected to form the lower end surface (23) of the arrayed waveguide; A first preset angle is formed between the first inclined surface (211) and the lower end surface (23); A plurality of the first inclined surfaces (211) and a plurality of the second inclined surfaces (212) are alternately arranged along the first direction and are parallel to each other; The first inclined surface (211) of the first sub-prism (21) and the second inclined surface (212) of the last sub-prism (21) are both provided with total reflection films, and the first inclined surfaces (211) of the other sub-prisms (21) except the first sub-prism (21) are all provided with angle selective transmission reflection films; The light coupling-in area of ​​the arrayed waveguide is arranged on the lower surface (214) of the first sub-prism (21), and the light coupling-out area is arranged on the upper end surface (22); The angle selectively transparent reflective film is configured to transmit a portion of incident light and reflect the remaining incident light, wherein a portion of the light reflected by the angle selectively transparent reflective film is emitted toward the upper end surface (22) at a total reflection critical angle smaller than the upper end surface (22) and is transmitted out, and another portion of the light reflected by the angle selectively transparent reflective film is emitted toward the lower end surface (23), and after being reflected by the lower end surface (23), is emitted toward the upper end surface (22) at a total reflection critical angle smaller than the upper end surface (22) and is transmitted out; In the first direction, the reflectivity of the angle selective transmission reflective film is The following relationship is satisfied: ； in, is the serial number of the angle selective transmission reflective film, with a value ranging from 1 to M, where M is the total number of first inclined surfaces (211) provided with the angle selective transmission reflective film in the arrayed waveguide; The number of the arrayed waveguides is at least two, and all of the arrayed waveguides include a first arrayed waveguide (2) arranged along the first direction, and a second arrayed waveguide (3) arranged along a second direction perpendicular to the first direction, wherein: The light coupling-in region of the first arrayed waveguide (2) is connected to the image generating unit (1), and the light coupling-out region of the first arrayed waveguide (2) is connected to the light coupling-in region of the second arrayed waveguide (3). The light coupling-out region of the first arrayed waveguide (2) has a plurality of light coupling-out positions, and the light coupling-in region of the second arrayed waveguide (3) has a plurality of light coupling-in positions. The plurality of light coupling-out positions are the same in number as the plurality of light coupling-in positions, and one of the plurality of light coupling-out positions corresponds to one of the light coupling-in positions, so that light propagates and expands the pupil through the first arrayed waveguide (2) and the second arrayed waveguide (3) in sequence.

2. The head-up display system based on a two-dimensional geometric array waveguide according to claim 1, characterized in that: The light generated by the image generation unit (1) enters the array waveguide through the light coupling-in region, and is reflected back and forth between the upper end surface (22) and the lower end surface (23) at a total reflection critical angle not less than that of the upper end surface (22) and the lower end surface (23) under the reflection of the total reflection film of the first sub-prism (21).

3. The head-up display system based on a two-dimensional geometric array waveguide according to claim 1, characterized in that: The first preset angle is ; The light generated by the image generation unit (1) has a predetermined viewing angle, and the half angle of the predetermined viewing angle is ; and The following relations are satisfied: ； ； ； ； in, is the refractive index of the array waveguide.

4. The head-up display system based on a two-dimensional geometric array waveguide according to claim 1, characterized in that: An automobile windshield (5) is arranged on a light emission path of the second arrayed waveguide (3); a Fresnel lens component (4) is provided between the automobile windshield (5) and the second arrayed waveguide (3); and the Fresnel lens component (4) is configured to compensate for aberrations introduced by the automobile windshield (5) in different directions.

5. The head-up display system based on a two-dimensional geometric array waveguide according to claim 4, characterized in that: The Fresnel lens component (4) comprises a first cylindrical Fresnel lens (41) and a second cylindrical Fresnel lens (42), wherein the first cylindrical Fresnel lens (41) and the second cylindrical Fresnel lens (42) are stacked. The first cylindrical Fresnel lens (41) comprises a first substrate and a first Fresnel structure arranged on the first substrate; The second cylindrical Fresnel lens (42) comprises a second substrate and a second Fresnel structure arranged on the second substrate; The first Fresnel structure extends along a third direction, and the second Fresnel structure extends along a fourth direction perpendicular to the third direction; the third direction is parallel to the first direction, and the fourth direction is parallel to the second direction.

6. The head-up display system based on a two-dimensional geometric array waveguide according to claim 1, characterized in that: The head-up display system based on a two-dimensional geometric array waveguide further includes a diffractive optical element, which is arranged at the exit pupil of the image generation unit (1) or the entrance pupil of the array waveguide. The diffractive optical element is used to expand the optical etendue, and the pixel size of the diffractive optical element is smaller than the pixel size of the spatial light modulator in the image generation unit (1).

7. The head-up display system based on a two-dimensional geometric array waveguide according to claim 1, characterized in that: Two adjacent sub-prisms (21) in the array waveguide are fixed by bonding.

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