HUD system based on array optical waveguide

Abstract

The invention discloses an HUD system based on an array optical waveguide, and relates to the technical field of optical display, and the system comprises an image generation unit which is used for generating virtual image light with a field angle of alpha * beta, outputting the virtual image light into an optical waveguide in a parallel light mode, and enabling the aperture of an output light beam to be not smaller than the coupling-in aperture of a pupil-expanding optical waveguide assembly; the pupil-expanding optical waveguide assembly is used for receiving the image light and performing pupil expansion, the pupil-expanding optical waveguide assembly is of an array optical waveguide structure and comprises a plurality of parallel reflection slopes, the first reflection slope is a coupling-in slope, the subsequent reflection slope is a pupil-expanding slope, and the free-form surface compensating mirror is used for compensating the pupil of the pupil-expanding optical waveguide assembly. The invention provides a parameterized AR-HUD system which creatively couples the array pupil-expanding optical waveguide which can be designed in a quantized manner and the predistortion correction of the free-form surface compensating mirror, and provides a computable design rule of the pupil-expanding size, the number of inclined planes and the reflectivity gradient.

Description

Technical Field

[0001] This invention relates to the field of optical display technology, specifically to a HUD system based on an arrayed optical waveguide. Background Technology

[0002] Head-up displays (HUDs) and their advanced form, augmented reality head-up displays (AR-HUDs), are the core human-machine interface of smart cockpits. Traditional HUDs use freeform surface mirrors, but as key indicators such as field of view (FOV) and vehicle visibility (VID) increase, the overall structure grows dramatically, posing significant challenges to system integration into vehicles. In contrast, AR-HUDs, which utilize optical waveguide technology, can effectively reduce the size of the HUD.

[0003] Currently, common optical waveguide technologies are divided into two types: arrayed waveguides and diffractive waveguides. Arrayed waveguides are based on the laws of light refraction and reflection, specifically consisting of a series of arrayed reflective surfaces coated with angle-selective reflective films, enabling pupil expansion, reflection, and homogenization of light beams. Diffractive waveguides, on the other hand, are based on the wave principle of light, fabricating nanostructures on a substrate to cause diffraction when light beams pass through these micro / nano structures, thus achieving beam control. In contrast, arrayed waveguides, belonging to geometric optics, are not sensitive to wavelength and can achieve better color reproduction. Diffractive waveguides, belonging to wave optics, are extremely sensitive to wavelength due to their nanoscale working structure. When used as a display technology, they are prone to color inhomogeneity, which is difficult to resolve. Furthermore, diffractive waveguides are difficult and inefficient to manufacture for large areas, while arrayed waveguides are mainly produced through optical cold processing, with relatively mature and stable manufacturing technologies. Therefore, arrayed waveguides are more in line with the development trend of AR-HUDs. Common AR waveguide HUD solutions use Fresnel lenses to correct windshield aberrations or diffractive waveguides, which cannot correct aberrations with high quality and have risks such as color cast and low efficiency.

[0004] Patent CN 223123320 U discloses a head-up display (HUD) device and vehicle for augmented reality. Its core components include an optical engine, a lens assembly, an optical waveguide assembly, and a correction mirror assembly. It can achieve a wider range of augmented reality displays, improving the user experience. Furthermore, the optical waveguide assembly occupies less space, enabling miniaturization of the HUD device for easier installation and placement within a vehicle. The core component, the optical waveguide assembly, is located between the lens assembly and the correction mirror assembly. It couples in a first image light beam, which is then diffracted to form a second image light beam, which is then coupled out to the correction mirror assembly. While this solution nominally achieves an optical waveguide HUD, because its core component is a diffractive optical waveguide, the device suffers from unresolved color distortion issues in its display effect. It also exhibits low luminous efficiency and high manufacturing difficulty, resulting in numerous drawbacks in practical product applications.

[0005] Patent CN 119224925 A provides an integrated solution for optical waveguides, display devices, and vehicles. The specific solution involves an optical waveguide comprising a transparent body, a first grating, and a second grating. The first grating is positioned in the center of the second grating. This solution primarily addresses the low light utilization rate of diffractive waveguides and can reduce the device's size, improving the user experience. However, the core technology of this solution is the grating. If this solution were applied to automobiles, issues such as color uniformity and brightness would arise, and the manufacturing process would be very difficult and costly, hindering practical product applications. Summary of the Invention

[0006] The purpose of this invention is to provide a HUD system based on an arrayed optical waveguide to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a HUD system based on an arrayed optical waveguide, including an image generation unit for generating a virtual image light with a field of view of α*β, and outputting it into the optical waveguide in a parallel light manner, and the aperture of its output beam is not less than the coupling entrance aperture of the pupil-expanding optical waveguide component. A pupil-expanding optical waveguide assembly is used to receive the image light and expand the pupil. The pupil-expanding optical waveguide assembly is an arrayed optical waveguide structure containing multiple parallel reflecting slopes, wherein the first reflecting slope is a coupling slope and the subsequent reflecting slopes are pupil-expanding slopes. Freeform surface compensation lens is used to receive parallel light emitted after pupil dilation and perform pre-distortion correction, so that the emitted light becomes a specific angular distribution of light that meets the windshield aberration compensation requirements; The dustproof film, also known as an optical control film, is used to block dust and suppress stray light, allowing light rays behind the compensating lens to propagate safely forward. The windshield is used to reflect the light to the driver's eye level to form a virtual image.

[0008] According to the above technical solution, the final pupil expansion dimensions X and Y of the pupil-expanding optical waveguide assembly satisfy the following relationship: ,in For lateral pupil dilation, This refers to the vertical pupil size. , For the system's Eyebox size, Interpupillary distance, , For the system's field of view, , These are the field loss coefficients in the X and Y directions, respectively.

[0009] According to the above technical solution, the pupil-expanding optical waveguide assembly includes a transverse pupil-expanding optical waveguide and a longitudinal pupil-expanding optical waveguide, and the transverse pupil-expanding optical waveguide has a certain number of pupil-expanding inclined surfaces. Angle between the inclined plane and the waveguide plane Waveguide thickness satisfy The number of pupil-expanding inclined planes in the longitudinal pupil-expanding optical waveguide Angle between the inclined plane and the waveguide plane Waveguide thickness satisfy .

[0010] According to the above technical solution, the pupil-expanding inclined surface is divided into multiple groups, each group containing 2 to 3 pupil-expanding inclined surfaces. The pupil-expanding inclined surfaces in the same group have the same reflectivity, and the reflectivity between adjacent groups increases, with an increase of 5% to 30%. The coupling inclined surface is set as a total reflective surface.

[0011] According to the above technical solution, the freeform surface compensation mirror is composed of one or more pieces, presents a negative optical power as a whole, and is set as an optical device with one side being a plane and the other side being a freeform surface, so as to realize the pre-correction of aberrations introduced by the windshield glass. The freeform surface is parameterized by one of the Zernike polynomial, the XY extended polynomial, and the Chebyshev polynomial.

[0012] A HUD design method based on arrayed optical waveguides includes the following steps: S1. Obtain the target system parameters a, b, L, α, β, and determine the field-of-view loss coefficient. , ; S2. Calculate the final pupil expansion dimensions X and Y of the pupil expansion waveguide assembly (201) based on the parameters; S3, Setting for Lateral Pupil Expanding Waveguide , The number of pupil-dilating inclined planes is determined according to the following formula. Setting up the longitudinal pupil-expanding waveguide , The number of pupil-dilating inclined planes is determined according to the following formula. ; S4. Set the first reflecting slope as the coupling slope and set it as the total reflection surface, and set the subsequent reflecting slopes as pupil dilation slopes; S5. Parametrically model the freeform surface compensation mirror to pre-correct the aberrations introduced by the windshield, thereby forming a clear virtual image at the driver's eye position.

[0013] According to the above technical solution, in step S1, the field loss coefficient is determined. , The specific method is as follows: S1-1, The effective field of view after considering the pre-distortion of the compensating mirror, windshield refraction / reflection, and waveguide incidence angle limitations are as follows: , ,but , ,and The image generation unit, pupil expansion waveguide, freeform surface compensation mirror, and windshield glass are integrated into an optical model; S1-2. Sample the set of principal rays within the target's field of view: For each sampled principal ray, determine whether it meets the following criteria: it can enter the waveguide, complete pupil expansion and coupling, and still fall into the preset eyebox after passing through the compensation mirror and windshield. This is expressed using an indicator function. ; S1-3, In the horizontal direction, take the... The maximum left and right boundary angles that are valid , ,but The same applies to the vertical direction. , ,but Finally obtained , .

[0014] According to the above technical solution, the image generation unit includes a lens part and a deflection prism; wherein the lens part includes an image source and a lens group, used to generate light rays that meet the system's field of view requirements and carry image information, and the deflection prism is used to deflect or reverse the light rays so that they are coupled into the pupil-expanding waveguide component.

[0015] According to the above technical solution, the dustproof film is composed of PC or glass components.

[0016] According to the above technical solution, the number of pupil-expanding inclined surfaces of the transverse pupil-expanding waveguide and the longitudinal pupil-expanding waveguide is preferably 9 to 15.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention uses freeform surface components to independently correct windshield aberrations, effectively corrects optical aberrations introduced by the windshield glass, ensures clear and distortion-free virtual images, improves image quality while increasing component reuse rate, and uses arrayed waveguide technology to eliminate color shift and other problems, improves efficiency, and enhances the overall performance of HUD; eliminates driver visual fatigue, and achieves system miniaturization while ensuring a large FOV and far VID. This paper presents a quantitative optical waveguide design method. The provided mathematical formulas transform the design process from experience-dependent to computationally calculable, ensuring that system performance, such as the Eyebox size, is predictable and achievable. The gradient reflectivity design effectively compensates for light energy attenuation, achieving a uniform display effect without bright or dark stripes, guaranteeing optical efficiency and display uniformity, and realizing AR displays with a large field of view, high brightness, and uniform brightness. The clearly defined parameter ranges, such as the number of bevels and reflectivity gradients, provide direct basis for production and process control. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the core components of the present invention; Figure 3 This is a schematic diagram of the light rays in this invention; Figure 4 This is an explanatory diagram of the arrayed optical waveguide of the present invention; Figure 5 This is a schematic diagram of the transverse pupil-expanding optical waveguide of the present invention; Figure 6 This is a schematic diagram of the longitudinal pupil-expanding optical waveguide of the present invention; Figure 7 This is a structural diagram of the compensation mirror of the present invention; Figure 8 This is a system model diagram of the present invention; Figure 9 This is an image simulation effect diagram of the present invention; Figure 10 This is a simulation effect diagram of the white field condition of the present invention; Figure 11 This is a system model diagram of the present invention that eliminates the freeform surface compensation mirror; Figure 12 This is a simulation image of the effect of eliminating the freeform surface compensation mirror in this invention; Figure 13 This is a simulation result diagram of the present invention eliminating the freeform surface compensation mirror. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 The present invention provides a technical solution: a HUD system based on an arrayed optical waveguide, including an image generation unit 101, which generates a virtual image light with a field of view of α*β and outputs it into the optical waveguide in a parallel light manner, and the aperture of its output beam is not less than the coupling entrance aperture of the pupil-expanding optical waveguide component. The pupil-expanding optical waveguide component 201 is used to receive image light and expand the pupil. The pupil-expanding optical waveguide component 201 is an array optical waveguide structure containing multiple parallel reflective slopes, wherein the first reflective slope is a coupling slope and the subsequent reflective slopes are pupil-expanding slopes. The freeform surface compensation mirror 301 is used to receive the parallel light emitted after pupil dilation and perform pre-distortion correction, so that the emitted light becomes a specific angle distribution light that meets the windshield aberration compensation requirements. Dustproof film 401 is an optical control film used to block dust and suppress stray light, allowing light rays after passing through compensation lens 301 to propagate safely forward; Windshield 501 is used to reflect light to the driver's eye level to form a virtual image; The image generation unit outputs parallel image light that satisfies the field of view angle and is coupled into the array waveguide. The light is reflected and coupled out multiple times on multiple parallel reflective inclined surfaces according to a predetermined propagation path to complete the exit pupil expansion. The exit light after pupil expansion is then pre-distorted by a freeform surface compensation mirror, so that it still forms a clear virtual image at the driver's eye position after being reflected by the windshield. By combining a quantifiable pupil expansion waveguide with a pre-distortion compensation mirror, the large FOV / far VID requirement is decoupled from the path of volume expansion caused by relying solely on a freeform surface reflector, thus taking into account both miniaturized packaging and controllable image quality.

[0021] The final pupil-expanding dimensions X and Y of the pupil-expanding waveguide assembly 201 satisfy the following relationship: ,in For lateral pupil dilation, This refers to the vertical pupil size. , For the system's Eyebox size, Interpupillary distance, , For the system's field of view, , These are the field loss coefficients in the X and Y directions, respectively.

[0022] By incorporating the target eyebox size, eye distance, target field of view, and system effective field of view loss coefficient into the pupil expansion size calculation, the final pupil expansion size of the waveguide can be directly derived from the indicators, thereby forming a deterministic mapping between indicators and structural dimensions. This reduces the reliance on repeated trial and error in optical path iteration, improves the predictability and verifiability of eyebox achievement, and reduces the risk of design rework.

[0023] The pupil-expanding optical waveguide assembly 201 includes a transverse pupil-expanding optical waveguide 2011 and a longitudinal pupil-expanding optical waveguide 2012, and the transverse pupil-expanding optical waveguide has a certain number of pupil-expanding bevels. Angle between the inclined plane and the waveguide plane Waveguide thickness satisfy The number of pupil-expanding inclined planes in the longitudinal pupil-expanding optical waveguide Angle between the inclined plane and the waveguide plane Waveguide thickness satisfy ; Based on the relationship between waveguide thickness, slope angle and equivalent displacement caused by single reflection, geometric constraints are established on pupil size and number of slopes, so that the number of slopes is determined by back calculation of the target pupil size, and is selected in conjunction with θ and h that can be achieved by the process.

[0024] The pupil-expanding inclined surfaces are divided into multiple groups, each containing 2 to 3 pupil-expanding inclined surfaces. The pupil-expanding inclined surfaces within the same group have the same reflectivity, and the reflectivity between adjacent groups increases by 5% to 30%. The coupling inclined surfaces are set as total reflective surfaces. The size of the pupil and the number of inclined surfaces required are transformed from empirical settings to calculable selection, avoiding the decrease in efficiency or the increase in processing difficulty caused by too many inclined surfaces, and improving the engineering feasibility of the structural design.

[0025] The freeform surface compensation mirror 301 consists of one or more pieces, presents negative optical power as a whole, and is set as an optical device with one side being a plane and the other side being a freeform surface, so as to achieve pre-correction of aberrations introduced by the windshield glass 501. The freeform surface is parametrically described by one of the Zernike polynomial, the XY extended polynomial, and the Chebyshev polynomial. Since successive beam splitting and coupling out along the propagation direction leads to power attenuation within the waveguide, a gradient distribution with equal reflectivity within the same group and increasing reflectivity between groups is used to achieve higher reflectivity on the rear slope to compensate for energy consumption in the front, thus achieving a more uniform energy distribution in the exit pupil direction. The coupling slope is designed for total internal reflection to ensure coupling efficiency and initial energy. This approach suppresses bright and dark fringes and brightness gradients without significantly increasing the complexity of the film system, improving display uniformity and optical efficiency, and providing a clear and feasible range for coating / process control.

[0026] A HUD design method based on arrayed optical waveguides includes the following steps: S1. Obtain the target system parameters a, b, L, α, β, and determine the field-of-view loss coefficient. , ; S2. Calculate the final pupil expansion dimensions X and Y of the pupil expansion waveguide assembly (201) based on the parameters; S3, Setting for Lateral Pupil Expanding Waveguide 2011 , The number of pupil-dilating inclined planes is determined according to the following formula. Designed for the longitudinal pupil-expanding waveguide 2012 , The number of pupil-dilating inclined planes is determined according to the following formula. ; S4. Set the first reflecting slope as the coupling slope and set it as the total reflection surface, and set the subsequent reflecting slopes as pupil dilation slopes; S5. Parametrically model the freeform surface compensation mirror 301 to pre-distort the aberrations introduced into the windshield glass 501, thereby forming a clear virtual image at the driver's eye position. In S1, determine the field loss coefficient. , The specific method is as follows: S1-1, The effective field of view after considering the pre-distortion of the compensating mirror, windshield refraction / reflection, and waveguide incidence angle limitations are as follows: , ,but , ,and The image generation unit, pupil expansion waveguide, freeform surface compensation mirror, and windshield glass are integrated into an optical model; S1-2. Sample the set of principal rays within the target's field of view: For each sampled principal ray, determine whether it meets the following criteria: it can enter the waveguide, complete pupil expansion and coupling, and still fall into the preset eyebox after passing through the compensation mirror and windshield. This is expressed using an indicator function. ; S1-3, In the horizontal direction, take the... The maximum left and right boundary angles that are valid , ,but The same applies to the vertical direction. , ,but Finally obtained , ; Within the target field of view, the principal ray is sampled, and the reachability of rays that can enter the waveguide, complete pupil expansion coupling, and fall into the eyebox after passing through the compensating lens and windshield is uniformly determined using an indicator function. The effective field of view is obtained by calculating the maximum left / right / up / down boundary angles that meet the determination conditions, thereby quantifying the field of view loss coefficient and feeding it back into the pupil expansion size calculation. This explicitly quantifies the effective field of view contraction caused by the windshield + compensating lens + waveguide emission angle limitation, avoiding design deviations in eyebox or pupil expansion size caused by only calculating based on nominal FOV, and improving the accuracy and auditability of indicator back-calculation and structural selection.

[0027] The image generation unit 101 includes a lens part 1011 and a deflection prism 1012; wherein the lens part 1011 includes an image source and a lens group, used to generate light rays that meet the system field of view requirements and carry image information, and the deflection prism 1012 is used to deflect or change the direction of the light rays so that they are coupled into the pupil-expanding waveguide component 201. The dustproof film 401 is made of PC or glass components.

[0028] The number of pupil-expanding inclined surfaces in the transverse pupil-expanding waveguide 2011 and the longitudinal pupil-expanding waveguide 2012 is preferably 9 to 15.

[0029] To prevent the formation of micro-textures / electrostatic adsorption stripes along the 45° direction on the surface of the dustproof film, which would cause diagonal brightness bias within the Eyebox (i.e., NE+SW being brighter and NW+SE being darker, or vice versa), and to self-correct reflectivity for abnormal diagonal brightness, four corner points within the Eyebox are selected as sampling points: Northeast, Northwest, Southeast, and Southwest. Photodetectors are placed at these four locations to sample the brightness, and the brightness is obtained for each point. , , , Construct diagonal skew index directly using the four corner points ,in , This indicates that NE and SW are diagonally brighter. This indicates that NW and SE are diagonally brighter. A diagonal compensation bias is applied to the grouped reflectance. Assume the pupil-expanding slope is divided into G groups, each with 2–3 lenses, with the inter-group increase remaining constant. Group reflectance Introduce a preset gain coefficient Calculate the compensated reflectance ,right Perform monotonic projection and correction to satisfy the following hard constraints: same reflectance within the same group, increasing reflectance between groups, with an increase rate of 5%–30%, and maintaining total internal reflection at the coupled slope. Repeat sampling and correction until the conditions are met. ,in This is a preset threshold constant. This means linearly mapping the group number to... This allows for fine-tuning of the reflectivity in the front and rear sections in opposite directions, thereby offsetting the energy bias caused by diagonal skew. When diagonal brightness skew occurs in the Eyebox due to non-uniformity of the film layer, misalignment during assembly, or surface microstructure, a diagonal skew index is constructed using the brightness of the four corner points. Without changing the constraints of group increment and step range, a small-amplitude correction is applied to the reflectivity of each group, which varies linearly with the group number. This causes the waveguide's outgoing energy distribution along the propagation direction to produce a compensation trend opposite to the skew.

[0030] Example: 101 is the PGU (Image Generation Unit), used to generate image light that meets the system's FOV requirements; 201 is the optical waveguide, used to expand the pupil of the image light emitted from 101, ensuring the light distribution meets the system's eyebox requirements; 301 is a compensation lens, used to compensate for the phase difference introduced by the windshield 501, i.e., to calibrate the light emitted from 201 so that the light remains parallel after reflection by the windshield 501; 401 is a dustproof film, matched to the overall automotive structure, used to block dust or eliminate stray light, and allows light passing through 301 to propagate safely forward; 501 is the windshield, used to reflect the light emitted through 401 to the driver's eye position.

[0031] Figure 2 This is a schematic diagram of the core components of the present invention. Image unit 101 includes 1011 and 1012. 1011 is the lens section, comprising an image source and a lens assembly, primarily used to generate light carrying image information that meets the system's required field of view (FOV). 1012 is a deflecting prism, used to deflect or reverse the light emitted from 1011, allowing the light to better couple into the optical waveguide. 201 is the optical waveguide section, comprising two components, 2011 and 2012, representing the horizontal and vertical directions respectively. These components are mainly used to expand the pupil horizontally and vertically of the light emitted from 101, ensuring the light distribution meets the system's eyebox requirements. 301 is a compensation lens, whose main function is to pre-correct the aberrations of the windshield 501. The light emitted from 2012 originally produces a clear, distortion-free image, but after passing through 501, due to the horizontal and vertical curvature of 501, the image becomes distorted and blurry. Therefore, 301 is needed for aberration correction. 401 is a dustproof film, characterized by its optical control properties. It is usually composed of PC or glass components and can block dust or eliminate stray light.

[0032] Figure 3 This is a schematic diagram of the light rays in this invention. The light rays emitted from PGU101, after passing through the optical waveguide 201 and expanding the pupil, will enter the compensation lens 301. Since 301 has aberration pre-correction functionality, and considering the allowance for later distortion correction, the field of view (FOV) will suffer a certain amount of loss. The field of view loss coefficients in the X and Y directions are... . Figure 4 This is an illustration of an arrayed optical waveguide, which is a transparent body composed of two parallel polished surfaces. Multiple reflective inclined surfaces are arranged inside it, the first of which is a coupling inclined surface, and the subsequent inclined surfaces are pupil-expanding inclined surfaces. The inclined surfaces are parallel to each other, and the projected size of the pupil-expanding inclined surface is the pupil size. The thickness of the optical waveguide is h, and the angle between the inclined surface and the lower surface is θ. Figure 5 The transverse pupil-expanding waveguide in this invention has an included angle of inclination of . Thickness is It has n pupil-expanding reflective slopes. Figure 6 The longitudinal pupil-expanding waveguide in this invention has an included angle of inclination of . Thickness is It has n pupil-expanding reflective slopes.

[0033] Figure 7 The compensating mirror in this invention is typically composed of one or more mirrors and exhibits negative optical power overall. To balance the processing performance and display effect of the actual product, the compensating mirror is usually configured as an optical device with one side being a plane and the other side being a freeform surface. The freeform surface can typically be a Zernike polynomial, an XY extended polynomial, or a Chebyshev polynomial, etc.

[0034] Based on the conditions defined in this patent, the following embodiments are provided: Table 1 shows the input parameter requirements: Table 1 According to the method provided in this patent, the optical waveguide parameters are set as shown in Table 2: Table 2 Specifically, for ease of actual production and processing, the angle between the inclined plane and the waveguide plane of both the transverse and longitudinal pupil-expanding waveguides is set to 25°, and the number of inclined planes is set to 11, with the same reflectivity setting for identical inclined planes. The plane closest to the light inlet is designated as S1, and the subsequent planes are designated as S2 to S11. Table 3 shows the reflectivity settings for each inclined plane: Table 3 Modeling and simulation are performed based on the above conditions, where Figure 8 This is a system model diagram. Figure 9 This is a simulation image. Figure 10 This is a simulation result under white field conditions. The simulation results show that the actual effect is excellent, clear and without distortion, meeting the requirements of normal use.

[0035] To further illustrate the superior effectiveness of the technical method provided in this patent, comparative examples are provided below. In this patent, 301 is the core component, which has the function of correcting windshield aberrations. If this component is removed, the system's display will exhibit image distortion or deformation. Based on the above embodiments, Figure 11 To cancel the system model diagram of 301, Figure 12 The simulation results show the image under this structure. The simulation results indicate that the image has significant distortion and cannot meet the requirements of normal use.

[0036] Meanwhile, the reflectivity setting standard of the pupil-expanding waveguide slope also greatly affects the actual effect of the system. Based on this embodiment, the reflectivity of the reflecting slope is set according to the conditions in Table 4, and the simulation results are as follows. Figure 13 As shown, there is obvious unevenness in the white field condition, which cannot meet the actual use requirements.

[0037] Table 4

[0038] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0039] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A HUD system based on an arrayed optical waveguide, characterized in that: Along the optical path propagation direction, it includes: an image generation unit (101), which generates a virtual image light with a field of view of α*β and outputs it into the optical waveguide in a parallel light manner, and its output beam aperture is not less than the coupling entrance aperture of the pupil-expanding optical waveguide component; The pupil-expanding optical waveguide component (201) is used to receive the image light and expand the pupil. The pupil-expanding optical waveguide component (201) is an array optical waveguide structure containing multiple parallel reflective slopes, wherein the first reflective slope is a coupling slope and the subsequent reflective slopes are pupil-expanding slopes. The freeform surface compensation mirror (301) is used to receive the parallel light emitted after pupil dilation and perform pre-distortion correction, so that the emitted light becomes a specific angle distribution light that meets the windshield aberration compensation requirements. The dustproof film (401) is an optical control film used to block dust and suppress stray light, so that the light after passing through the compensation lens (301) can safely propagate forward; The windshield (501) is used to reflect the light to the driver's eye position to form a virtual image.

2. The HUD system based on arrayed optical waveguides according to claim 1, characterized in that: The final pupil-expanding dimensions X and Y of the pupil-expanding optical waveguide assembly (201) satisfy the following relationship: ,in For lateral pupil dilation, This refers to the vertical pupil size. , For the system's Eyebox size, Interpupillary distance, , For the system's field of view, , These are the field loss coefficients in the X and Y directions, respectively.

3. A HUD system based on an arrayed optical waveguide according to claim 2, characterized in that: The pupil-expanding waveguide assembly (201) includes a transverse pupil-expanding waveguide (2011) and a longitudinal pupil-expanding waveguide (2012), and the transverse pupil-expanding waveguide has a certain number of pupil-expanding bevels. Angle between the inclined plane and the waveguide plane Waveguide thickness satisfy The number of pupil-expanding inclined planes in the longitudinal pupil-expanding optical waveguide Angle between the inclined plane and the waveguide plane Waveguide thickness satisfy .

4. A HUD system based on an arrayed optical waveguide according to claim 1, characterized in that: The pupil-expanding inclined surfaces are divided into multiple groups, each group containing 2 to 3 pupil-expanding inclined surfaces. The pupil-expanding inclined surfaces in the same group have the same reflectivity. The reflectivity between adjacent groups increases, and the increase is 5% to 30%. The coupling inclined surface is set as a total reflective surface.

5. A HUD system based on an arrayed optical waveguide according to claim 1, characterized in that: The freeform surface compensation mirror (301) consists of one or more pieces, presents a negative optical power as a whole, and is set as an optical device with one side being a plane and the other side being a freeform surface, so as to realize the pre-correction of aberrations introduced by the windshield glass (501). The freeform surface is parameterized by one of the Zernike polynomial, the XY extended polynomial, and the Chebyshev polynomial.

6. A HUD design method based on an arrayed optical waveguide according to any one of claims 1-5, characterized in that: Includes the following steps: S1. Obtain the target system parameters a, b, L, α, β, and determine the field-of-view loss coefficient. , ; S2. Calculate the final pupil expansion dimensions X and Y of the pupil expansion waveguide assembly (201) based on the parameters: S3, Setting for Lateral Pupil Waveguide (2011) , The number of pupil-dilating inclined planes is determined according to the following formula. For longitudinal pupil-expanding waveguides (2012) , The number of pupil-dilating inclined planes is determined according to the following formula. ; S4. Set the first reflecting slope as the coupling slope and set it as the total reflection surface, and set the subsequent reflecting slopes as pupil dilation slopes; S5. Parametric modeling of the freeform surface compensation mirror (301) is performed so that it can pre-distort the aberrations introduced into the windshield glass (501) to form a clear virtual image at the driver's eye position.

7. A HUD design method based on an arrayed optical waveguide according to claim 6, characterized in that: In S1, the field loss coefficient is determined. , The specific method is as follows: S1-1, The effective field of view after considering the pre-distortion of the compensating mirror, windshield refraction / reflection, and waveguide incidence angle limitations are as follows: , ,but , ,and The image generation unit, pupil expansion waveguide, freeform surface compensation mirror, and windshield glass are integrated into an optical model; S1-2. Sample the set of principal rays within the target's field of view: For each sampled principal ray, determine whether it meets the following criteria: it can enter the waveguide, complete pupil expansion and coupling, and still fall into the preset eyebox after passing through the compensation mirror and windshield. This is expressed using an indicator function. ; S1-3, In the horizontal direction, take the... The maximum left and right boundary angles that are valid , ,but The same applies to the vertical direction. , ,but Finally obtained , .

8. A HUD system based on an arrayed optical waveguide according to claim 1, characterized in that: The image generation unit (101) includes a lens part (1011) and a deflection prism (1012); wherein the lens part (1011) includes an image source and a lens group, used to generate light rays that meet the system field of view requirements and carry image information, and the deflection prism (1012) is used to deflect or change the direction of the light rays so that they are coupled into the pupil-expanding waveguide component (201).

9. A HUD system based on an arrayed optical waveguide according to claim 1, characterized in that: The dustproof film (401) is made of PC or glass components.

10. A HUD system based on an arrayed optical waveguide according to claim 3, characterized in that: The number of pupil-expanding inclined surfaces in the transverse pupil-expanding waveguide (2011) and the longitudinal pupil-expanding waveguide (2012) is preferably 9 to 15.

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