HUD optical system and vehicle

Abstract

The invention belongs to the technical field of head-up displays, and provides an HUD optical system, which comprises an image source, a first reflector, a second reflector, a semi-transparent and semi-reflective mirror and front windshield glass, an image source, a first reflecting mirror, a second reflecting mirror and a semi-transparent and semi-reflecting mirror are arranged in a surrounding space to form a closed light path folding area, a 4-shaped folding light path is formed through three times of reflection, the object distance of the light path is increased through the folding light path to achieve ultra-long-distance projection, the problem of glass ghosting can be solved without wedge-shaped film glass, and the projection efficiency is improved. And the volume of the system is compressed to the greatest extent based on the closed light path folding area, so that the field angle and the virtual image distance are enlarged, the compact volume of the system is ensured, and the adaptability and the installation convenience of the head-up display in a vehicle are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of head-up display technology, and specifically relates to a HUD optical system. Background Technology

[0002] In practical automotive applications, the inner and outer surfaces of a conventional vehicle windshield are parallel to each other. When the HUD image is reflected from these surfaces, the difference in reflection point height causes misalignment, resulting in ghosting, blurry images, and discomfort for the driver. The magnitude of the ghosting is strongly correlated with D (glass thickness), VID (virtual image distance), and a (angle of incidence of light on the glass), exceeding the resolution requirements of the human eye. Therefore, glass treatment is necessary, typically by adding a wedge-shaped PVB film inside the glass to resolve the ghosting problem. However, wedge-shaped glass is usually very expensive.

[0003] Meanwhile, with the increasing electrification and intelligence of automobiles, the FOV (Field of View) and VID (Virtual Image Distance) of HUDs will become increasingly larger to provide a better driving experience. The size of a HUD is strongly correlated with the FOV, VID, and PGU (Image Generation Unit) dimensions. To increase the FOV and VID while maintaining the HUD's size, the PGU size must inevitably be sacrificed. Specifically, for conventional AR / W-HUDs, the VID is typically between 2.5m and 7.5m. If the VID is too large, the HUD system will be extremely bulky, failing to meet vehicle installation requirements.

[0004] Furthermore, conventional TFT (Thin Film Transistor) technology suffers from sunlight backflow, which can easily lead to localized overheating of the PGU (Power Generation Unit). One common solution is to increase the PGU size to expand the sunlight converging area, thereby reducing energy density and temperature rise. However, increasing the size directly leads to an increase in the volume of the optical system, creating a conflict between compact design and thermal management. Therefore, the industry often uses LCOS or DLP solutions to replace TFTs, utilizing their optical properties to reduce heat density. However, these two solutions are significantly more expensive than TFTs, typically 2 to 4 times more expensive. In addition, due to the presence of the diffuser in the alternative structure, a noticeable white background effect is generated when sunlight backflows, severely reducing image contrast. Especially in scenes with alternating light and dark conditions, such as tunnels or streetlights, this can easily cause background flicker, interfering with the driver's visual experience and bringing new optical and perceptual challenges. Summary of the Invention

[0005] The purpose of this invention is to disclose a HUD optical system that solves the technical problems in current HUD technology, where the pursuit of compactness restricts the optical path design, or the pursuit of heat resistance against backflow of sunlight forces the adoption of high-cost LCOS / DLP solutions, making it difficult to balance cost, size and display effect.

[0006] To achieve the above objectives, this invention discloses a HUD optical system, including an image source, a first reflector, a second reflector, a semi-transparent mirror, and a windshield; the first reflector is disposed in the light emission direction of the image source; the semi-transparent mirror is disposed on one side of the image source, with one side of its reflective surface facing the first and second reflectors, and the other side of its light-transmitting surface facing the windshield; the second reflector is disposed on the other side of the image source, with its reflective surface facing the first reflector; the image source, the first reflector, the second reflector, and the semi-transparent mirror are arranged in a surrounding spatial arrangement to form a closed optical path folding area; The light emitted from the image source is reflected by the first reflector after passing through the optical path folding area, performing the first optical path folding; the reflected light passes through the optical path folding area and is incident on the semi-transparent mirror; the semi-transparent mirror reflects the light so that it passes through the optical path folding area and is incident on the second reflector, performing the second optical path folding; the second reflector reflects the light so that it passes through the optical path folding area and is incident forward on the semi-transparent mirror, performing the third optical path folding; finally, the light passes forward through the semi-transparent mirror and is projected onto the windshield.

[0007] This basic solution is based on an image source, a first reflector, a second reflector, and a semi-transparent mirror arranged in a surrounding spatial pattern to form a closed optical path folding area. Through three reflections, a "4"-shaped folded optical path is formed. The folded optical path increases the object distance to achieve ultra-long-distance projection. The problem of glass ghosting can be solved without the need for wedge-shaped film glass. Furthermore, the closed optical path folding area maximizes the compression of the system volume. While expanding the field of view and the distance to the virtual image, it ensures a compact system size and significantly improves the adaptability and installation convenience of the head-up display in vehicles.

[0008] As an optional implementation, the first reflector includes a plane reflector, which is disposed in the light emission direction of the image source and is close to the dashboard or the driver.

[0009] The first reflecting mirror in this scheme is a plane reflecting mirror, which has a mature manufacturing process, low cost, and does not introduce additional aberrations, which is beneficial for system assembly and optical path accuracy control.

[0010] As an optional implementation, the first reflector includes a first curved reflector, which is disposed in the light emission direction of the image source and is close to the dashboard or the driver's side; the first curved reflector includes one of a spherical mirror, an aspherical mirror, and a freeform mirror.

[0011] The first reflecting mirror in this scheme is a spherical, aspherical, or freeform mirror. Aspherical and freeform mirrors can effectively correct system aberrations, expand the field of view, optimize distortion and image quality, and significantly improve optical performance.

[0012] As an optional implementation, the second reflector includes a second curved reflector, which is disposed on the side of the image source away from the windshield, with its reflective surface facing the first reflector and pointing towards the windshield; The second curved surface mirror is a freeform surface mirror, and its surface shape expression is as follows:

[0013] In the formula, z represents the sag of the freeform surface;

[0014] In the formula, r represents the radial distance of the freeform surface on the second curved mirror, c represents the vertex curvature of the freeform surface, and k represents the conic coefficient. The coefficients are represented by x and y, which represent the values ​​in the x and y directions of the three-dimensional data relative to the elevation z, respectively.

[0015] This solution places the second curved reflector on the side of the image source away from the windshield, with its reflective surface facing the first reflector and pointing towards the windshield. By placing the second reflector on one side of the entire optical path folding area, without clamping it to one side of the optical path, structural interference is avoided. This facilitates the stable installation of the second reflector and also makes it easy to integrate a height adjustment mechanism behind it, thereby enabling convenient calibration of the virtual image position (i.e., image height adjustment).

[0016] As an optional implementation, the side of the semi-transparent mirror closest to the windshield is a light-transmitting surface, and the side furthest from the windshield is a reflective surface. The reflective surface is stacked with a semi-transparent film layer, and the light-transmitting surface is stacked with an AR anti-reflective layer.

[0017] This design uses a semi-transparent, semi-reflective mirror as the core folding element. Based on its reflection and transmission capabilities, light is folded three times to form a closed optical path. Since both the PGU (Power Array Unit) and the first reflecting mirror are integrated within the optical path folding area formed by the second curved mirror and the semi-transparent, semi-reflective mirror, the optical path is completely folded, resulting in a compact structure and achieving ultra-long-distance projection. This facilitates product miniaturization and practical applications. A semi-transparent, semi-reflective coating is deposited on the reflective surface of the semi-transparent, semi-reflective mirror to precisely control the beam splitting ratio; an AR (Anti-Reflective) coating is deposited on its transmissive surface to significantly reduce residual surface reflection, thereby improving transmission efficiency, suppressing ghosting, and enhancing system contrast and image purity.

[0018] As an optional implementation, a quarter-wave plate is also included, which is disposed on the front end of the second reflector near the semi-transparent mirror to adjust the polarization state of the light path.

[0019] This scheme places a quarter-wave plate at the front end of the second reflecting mirror (closer to the semi-transparent mirror side), which can precisely control the polarization state of the round-trip beam, effectively improve the selectivity of the semi-transparent mirror for S-rays and P-rays, enhance the extinction ratio, and significantly suppress polarized stray light generated by multiple reflections inside the system, thereby optimizing the imaging contrast.

[0020] As an optional implementation, the side of the semi-transparent mirror closest to the windshield is a light-transmitting surface, and the side furthest from the windshield is a reflective surface. The reflective surface is stacked with a 3M reflective polarizing film, and the light-transmitting surface is stacked with an AR anti-reflective layer.

[0021] This solution, based on a quarter-wave plate, stacks a 3M reflective polarizing film on the reflective surface of a semi-transparent mirror. This film works in conjunction with the quarter-wave plate to achieve efficient polarization conversion and recovery, significantly improving light energy utilization. An AR anti-reflective layer is stacked on its transparent surface to further reduce transmission loss and stray light, together achieving high brightness and high contrast imaging effects.

[0022] As an optional implementation, the image source includes a TFT-PGU, which includes a TFT microdisplay chip and a light source.

[0023] This solution uses TFT as the PGU, which significantly reduces the system's production cost. At the same time, based on the closed optical path folding area, it ensures image contrast while solving the high temperature problem caused by sunlight backflow, effectively avoiding white background and flickering white background when passing through tunnels, further improving the user experience.

[0024] As an optional implementation, the semi-transparent and semi-reflective mirror is a plane mirror.

[0025] The core optical components used in this solution (first reflecting mirror, second reflecting mirror, semi-transparent and semi-reflective mirror, etc.) are all mature, low-cost standard optical components that are easy to procure and integrate, have good process compatibility, save costs, simplify the structure, and have high reliability.

[0026] The present invention also provides a vehicle including a HUD optical system as described above. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is an optical path structure diagram of a conventional HUD optical path provided in an embodiment of the present invention; Figure 2 This is a system structure diagram of a HUD optical system provided in Embodiment 1 of the present invention; Figure 3 This is a partial structural enlarged view of a HUD optical system provided in Embodiment 1 of the present invention; Figure 4 This is a system structure diagram of a HUD optical system provided in Embodiment 2 of the present invention; Figure 5 This is a system structure diagram of a HUD optical system provided in Embodiment 3 of the present invention; Figure 6 This is a system structure diagram of a HUD optical system provided in Embodiment 4 of the present invention; Icons: Image source 1, first reflector 2, second reflector 3, semi-transparent and semi-reflective mirror 4, windshield 5, quarter-wave plate 6, human eye 7; semi-transparent and semi-reflective film layer 41, AR anti-reflective layer 42, 3M reflective polarizing film 43. Detailed Implementation

[0029] 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.

[0030] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0031] Furthermore, some of the aforementioned terms, besides indicating direction or positional relationships, may also have other meanings. For example, the term "above" may, in certain circumstances, indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0032] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0033] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0034] Traditional HUD optical path (parameter) Figure 1 This is an off-axis three-mirror structure. To solve the glass ghosting problem, VID > 15m is required. According to the Gaussian imaging formula 1 / u + / v = 1 / f, where u is the object distance in the optical path... Figure 1 As shown, u ≈ distance A + distance B + distance C, and v is the image distance in the optical path. Figure 1 As shown, v≈VID+distanceD. Since the focal length f of the glass is basically fixed after the glass shape is locked, it can be seen that as VID increases, u will inevitably increase, which means the volume will increase.

[0035] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0036] Example 1 Please see Figure 2 , Figure 3 As shown, this application provides a HUD optical system, including an image source 1, a first reflector 2, a second reflector 3, a semi-transparent mirror 4, and a windshield 5; the first reflector 2 is disposed in the light emission direction of the image source 1; the semi-transparent mirror 4 is disposed on one side of the image source 1, with one side of its reflective surface facing the first reflector 2 and the second reflector 3, and the other side of its light-transmitting surface facing the windshield 5; the second reflector 3 is disposed on the other side of the image source 1, with its reflective surface facing the first reflector 2; the image source 1, the first reflector 2, the second reflector 3, and the semi-transparent mirror 4 are arranged in a surrounding spatial arrangement to form a closed optical path folding area; The light emitted from image source 1 is reflected by the first reflector 2 after passing through the optical path folding area, performing the first optical path folding; the reflected light passes through the optical path folding area and enters the semi-transparent mirror 4; the semi-transparent mirror 4 reflects the light so that it passes through the optical path folding area and enters the second reflector 3, performing the second optical path folding; the second reflector 3 reflects the light so that it passes through the optical path folding area and enters the semi-transparent mirror 4 in a forward direction, performing the third optical path folding; finally, the light passes forward through the semi-transparent mirror 4 and is projected onto the windshield 5. The projection direction of the light is shown in the appendix. Figure 2 The arrow in the image points to...

[0037] As an optional implementation, the first reflector 2 is positioned in the light emission direction of the image source 1 and is close to the side of the dashboard.

[0038] The first reflecting mirror 2 includes a plane reflecting mirror or a first curved surface reflecting mirror; The first curved mirror includes one of a spherical mirror, an aspherical mirror, and a freeform mirror.

[0039] In this embodiment, the first reflecting mirror 2 is a plane reflecting mirror, which has a mature manufacturing process, low cost, and does not introduce additional aberrations, which is beneficial for system assembly and optical path accuracy control.

[0040] In this embodiment, the first reflecting mirror 2 is a spherical, aspherical, or freeform mirror. Aspherical and freeform mirrors can effectively correct system aberrations (adjust the system focal length and reduce the system volume to a certain extent), expand the field of view, optimize distortion and image quality, and significantly improve optical performance.

[0041] As an optional implementation, the second reflector 3 includes a second curved reflector, which is disposed on the side of the image source 1 away from the windshield 5, with its reflective surface facing the first reflector 2 and pointing towards the windshield 5; The second curved surface mirror is a freeform surface mirror, and its surface shape expression is as follows:

[0042] In the formula, z represents the sag (height) of the freeform surface; Represents the fundamental terms of quadratic surfaces (such as the core of a sphere, parabola, or hyperboloid). Represents a high-order polynomial;

[0043] In the formula, r represents the radial distance of the freeform surface on the second curved mirror, c represents the vertex curvature of the freeform surface, and k represents the conic coefficient. The coefficients are represented by x and y, which represent the values ​​in the x and y directions of the three-dimensional data relative to the elevation z, respectively.

[0044] In this embodiment, the second curved reflector is placed on the side of the image source 1 away from the windshield 5, with its reflective surface facing the first reflector 2 and pointing towards the windshield 5. By placing the second reflector 3 on one side of the entire optical path folding area, without being clamped to one side of the optical path, structural interference is avoided, which is conducive to the stable installation of the second reflector 3 and also facilitates the integration of a height adjustment mechanism behind it, thereby realizing convenient calibration of the virtual image position (i.e., image height adjustment).

[0045] As an optional implementation, the side of the semi-transparent mirror 4 closest to the windshield 5 is a light-transmitting surface, and the side furthest from the windshield 5 is a reflective surface. The reflective surface is stacked with a semi-transparent and semi-reflective film layer 41, and the light-transmitting surface is stacked with an AR anti-reflective layer 42, thereby controlling the reflection and transmission within the range of 50% ± 5%.

[0046] In this embodiment, a semi-transparent mirror 4 is used as the core folding element. Based on its reflection and transmission functions, light is folded three times to form a closed optical path. Since the PGU and the first reflector 2 are both built into the optical path folding area formed by the second curved mirror and the semi-transparent mirror 4, the optical path is completely folded, resulting in a compact structure and achieving ultra-long-distance projection, which is beneficial for product miniaturization and practical application. A semi-transparent mirror 41 is coated on the reflective surface of the semi-transparent mirror 4 to precisely control the beam splitting ratio; an AR anti-reflective coating is coated on its transparent surface to significantly reduce residual surface reflection light, thereby improving transmission efficiency, suppressing ghosting, and enhancing system contrast and image purity.

[0047] As an optional implementation, the image source 1 includes a TFT-PGU, which includes a TFT microdisplay chip and a light source.

[0048] This embodiment uses a TFT as the PGU, which significantly reduces the system's production cost. At the same time, based on the closed optical path folding area, it ensures image contrast while solving the high temperature problem caused by sunlight backflow, effectively avoiding white background and flickering white background when passing through tunnels, further improving the user experience.

[0049] As an optional implementation, the semi-transparent and semi-reflective mirror 4 is a plane mirror.

[0050] The core optical components used in this embodiment (first reflector 2, second reflector 3, semi-transparent and semi-reflective mirror 4, etc.) are all mature, low-cost standard optical components that are easy to procure and integrate, have good process compatibility, save costs, simplify the structure, and have high reliability.

[0051] The working principle of this invention is as follows: The light emitted from the image source 1 passes through the optical path folding area and enters the first reflector 2, where it is reflected by the first reflector 2, thus performing the first optical path folding. The reflected light passes through the optical path folding area and is incident on the semi-transparent and semi-reflective mirror 4, where it is reflected by the semi-transparent and semi-reflective mirror 4, thus performing a second optical path folding. The semi-transparent and semi-reflective mirror 4 reflects light to pass through the optical path folding area and enter the second reflective mirror 3, where it is reflected by the second reflective mirror 3, thus performing a third optical path folding. The second reflector 3 reflects light so that it passes through the optical path folding area and is incident in the forward direction onto the semi-transparent and semi-reflective mirror 4; Finally, the light passes through the semi-transparent mirror 4 and is projected onto the windshield 5, where it is reflected to the driver's eye 7 (i.e., the driver's eye area).

[0052] The optical path is folded multiple times in the internal optical path folding area, thereby increasing the object distance of the system, u = distance a + distance b + distance c + distance d + distance f, which increases the VID of the optical path system to 20 meters. However, since the optical path is folded internally, the volume of the system does not increase.

[0053] The main application scenario of this invention is AR-HUD, which is mainly used by the driver as an auxiliary safe driving scenario.

[0054] Example 2 Please see Figure 4 As shown, this embodiment of the invention provides a HUD optical system. The difference between this embodiment and Embodiment 1 is that this invention further includes a quarter-wave plate 6, which is disposed on the front end of the second reflector 3 near the semi-transparent mirror 4 to adjust the polarization state of the light path.

[0055] Specifically, the light emitted from image source 1 is polarized in polarization state 2. The linearly polarized light incident on the second reflecting mirror 3 (e.g., a freeform mirror) is first adjusted to circularly polarized light after passing through the quarter-wave plate 6, and then enters the second reflecting mirror 3. After being reflected by the second reflecting mirror 3, it passes through the quarter-wave plate again and is adjusted to linearly polarized light, at which point the polarization state is polarization state 1, where: Polarization state 1: The polarization state of image source 1 (TFT) in a normal HUD is defined as polarization state 1. At this time, the polarization direction of the light emitted from image source 1 is parallel to the long side, that is, the vibration direction is in the horizontal direction.

[0056] Polarization state 2: The polarization state that is perpendicular to the vibration direction of polarization state 1 is defined as polarization state 2, that is, the vibration direction is in the vertical direction.

[0057] In this embodiment, the quarter-wave plate 6 is placed at the front end of the reflector of the second reflector 3 (close to the side of the semi-transparent mirror 4), which can precisely control the polarization state of the round-trip beam, effectively improve the selectivity of the semi-transparent mirror 4 for s-rays and p-rays, enhance the extinction ratio, and significantly suppress the polarized stray light generated by multiple reflections inside the system, thereby optimizing the imaging contrast.

[0058] As an optional implementation, the semi-transparent mirror 4 has a light-transmitting surface on the side closer to the windshield 5 and a reflective surface on the side farther away from the windshield 5. The reflective surface is stacked with a 3M reflective polarizing film 43 (i.e., 3M DBEF-QV2), and the light-transmitting surface is stacked with an AR anti-reflective layer 42.

[0059] In this embodiment, based on the configuration of a quarter-wave plate 6, a 3M reflective polarizing film 43 is stacked on the reflective surface of the semi-transparent mirror 4. Together with the quarter-wave plate 6, it achieves efficient polarization conversion and recovery, greatly improving the light energy utilization rate. An AR anti-reflection layer 42 is stacked on its light-transmitting surface to further reduce transmission loss and stray light, thus achieving a high-brightness and high-contrast imaging effect.

[0060] Example 3 Please see Figure 5 As shown, this embodiment of the invention provides a HUD optical system. The difference between this embodiment and embodiment 1 is that the first reflector 2 is disposed in the light emission direction of the image source 1 and is closer to the driver's side.

[0061] Example 4 Please see Figure 6 As shown, this embodiment of the invention provides a HUD optical system. The difference between this embodiment and embodiment 2 is that the first reflector 2 is disposed in the light emission direction of the image source 1 and is closer to the driver's side.

[0062] Example 5 This invention also provides a vehicle including a HUD optical system as described in Embodiment 1, Embodiment 2, Embodiment 3, or Embodiment 4 above.

[0063] The embodiments of the present invention are based on an image source 1, a first reflector 2, a second reflector 3, and a semi-transparent and semi-reflective mirror 4 arranged in a surrounding spatial pattern to form a closed optical path folding area. A “4”-shaped folded optical path is formed through three reflections. The folded optical path increases the object distance to achieve ultra-long-distance projection. The problem of glass ghosting can be solved without the need for wedge-shaped film glass. Furthermore, the closed optical path folding area maximizes the compression of the system volume. While expanding the field of view and the distance to the virtual image, the system volume is kept compact, which significantly improves the adaptability and installation convenience of the head-up display in vehicles.

[0064] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A HUD optical system, characterized in that: The system includes an image source, a first reflector, a second reflector, a semi-transparent mirror, and a windshield. The first reflector is positioned in the direction of light emission from the image source. The semi-transparent mirror is positioned on one side of the image source, with its reflective surface facing the first and second reflectors and its light-transmitting surface facing the windshield. The second reflector is positioned on the other side of the image source, with its reflective surface facing the first reflector. The image source, the first reflector, the second reflector, and the semi-transparent mirror are arranged in a surrounding spatial arrangement to form a closed optical path folding area. The light emitted from the image source is reflected by the first reflector after passing through the optical path folding area, performing the first optical path folding; the reflected light passes through the optical path folding area and is incident on the semi-transparent mirror; the semi-transparent mirror reflects the light so that it passes through the optical path folding area and is incident on the second reflector, performing the second optical path folding; the second reflector reflects the light so that it passes through the optical path folding area and is incident forward on the semi-transparent mirror, performing the third optical path folding; finally, the light passes forward through the semi-transparent mirror and is projected onto the windshield.

2. The HUD optical system as described in claim 1, characterized in that: The first reflector includes a plane reflector, which is positioned in the direction of light emission from the image source and is close to the dashboard or the driver.

3. The HUD optical system as described in claim 1, characterized in that: The first reflector includes a first curved reflector, which is disposed in the light emission direction of the image source and is close to the dashboard or the driver's side; the first curved reflector includes one of a spherical mirror, an aspherical mirror, and a freeform mirror.

4. The HUD optical system as described in claim 1, characterized in that: The second reflector includes a second curved reflector, which is disposed on the side of the image source away from the windshield, with its reflective surface facing the first reflector and pointing towards the windshield; The second curved surface mirror is a freeform surface mirror, and its surface shape expression is as follows: In the formula, z represents the sag of the freeform surface; In the formula, r represents the radial distance of the freeform surface on the second curved mirror, c represents the vertex curvature of the freeform surface, and k represents the conic coefficient. The coefficients are represented by x and y, which represent the values ​​in the x and y directions of the three-dimensional data relative to the elevation z, respectively.

5. The HUD optical system as described in claim 1, characterized in that: The semi-transparent and semi-reflective mirror has a light-transmitting surface on the side closest to the windshield and a reflective surface on the side furthest from the windshield. The reflective surface is stacked with a semi-transparent and semi-reflective film layer, and the light-transmitting surface is stacked with an AR anti-reflective layer.

6. The HUD optical system as described in claim 1, characterized in that: It also includes a quarter-wave plate, which is disposed on the front end of the second reflector near the semi-transparent mirror to adjust the polarization state of the light path.

7. A HUD optical system as described in claim 6, characterized in that: The semi-transparent mirror has a light-transmitting surface on the side closest to the windshield and a reflective surface on the side furthest from the windshield. The reflective surface is stacked with a 3M reflective polarizing film, and the light-transmitting surface is stacked with an AR anti-reflective layer.

8. The HUD optical system as described in claim 1, characterized in that: The image source includes a TFT-PGU, which includes a TFT microdisplay chip and a light source.

9. A HUD optical system as described in claim 1, characterized in that: The semi-transparent, semi-reflective mirror is a plane mirror.

10. A vehicle, characterized in that: Includes a HUD optical system as described in any one of claims 1 to 9.

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