A head-up display and a car

Abstract

This invention relates to the technical field of vehicle-mounted equipment, and discloses a head-up display and a car, comprising: a self-emissive display module, including a printed circuit board, a plurality of LED chips arranged in an array on the front side of the printed circuit board, a black insulating layer filling between the LED chips, and a transparent encapsulation layer covering the LED chips, wherein the LED chips are bare chips without encapsulation shells and are fixed and electrically connected to the pads of the printed circuit board by eutectic bonding or solder paste reflow process; a driving circuit, including a plurality of driving ICs disposed on the back side of the printed circuit board by flip-chip bonding process, a connector for connecting the driving ICs, and a flexible circuit board connecting the connector and an external main control driving board; and an optical system disposed in the light emission direction of the self-emissive display module for collimating, reflecting and amplifying the light emitted by the self-emissive display module to project an image in the form of a virtual image to a predetermined position.

Description

Technical Field

[0001] This invention relates to the technical field of vehicle-mounted equipment, and more particularly to a head-up display and a car. Background Technology

[0002] Head-up displays (HUDs) are important in-vehicle devices that enhance driving safety and experience. Traditionally, they generally use LCD (liquid crystal display) combined with a backlight module as the image source, projecting images onto the windshield through an optical system. However, LCD technology has inherent limitations such as low luminous efficiency, high power consumption, high heat generation, limited contrast, and slow response speed. In particular, it is prone to problems such as washed-out images and poor visibility in strong light environments.

[0003] To improve the brightness and optical efficiency of HUDs, the industry has also explored microdisplay technologies such as DLP (Digital Micromirror Device) and LCOS (Liquid Crystal on Silicon). Among these, LCOS, a reflective microdisplay technology based on liquid crystal on silicon, offers significantly higher light energy utilization compared to transmissive LCDs, reaching over 40%, and can achieve higher brightness output with lower power consumption. However, these solutions still rely on complex optomechanical structures, resulting in high cost and large size, and limitations in resolution improvement and light source lifespan.

[0004] In recent years, self-emissive display technologies (such as OLED and Mini / Micro LED technologies) have provided a new direction for the development of HUDs. These technologies possess the characteristic of self-emissive pixels, eliminating the need for a backlight module and avoiding light energy loss during transmission. They also offer advantages such as high brightness, high contrast, wide color gamut, fast response, low power consumption, and long lifespan. However, applying self-emissive display technology to HUDs still faces many challenges. Because HUD display modules are small and require high resolution (such as 1080p or 4K), pixel pitches must reach sub-millimeter or even tens of micrometer levels, necessitating the high-density integration of millions of LED chips. Ensuring high-speed driving and long-term reliability of the LED chip array within the harsh automotive environment and limited space has become a pressing technical challenge. Summary of the Invention

[0005] The main objective of this invention is to provide a head-up display and an automobile, which aims to solve the aforementioned technical problems.

[0006] To achieve the above objectives, the present invention provides a head-up display, comprising:

[0007] The self-emissive display module includes a printed circuit board, a plurality of LED chips arranged in an array on the front side of the printed circuit board, a black insulating layer filling between the LED chips, and a transparent encapsulation layer covering the LED chips. The LED chips are bare chips without encapsulation shells and are fixed and electrically connected to the pads of the printed circuit board by eutectic bonding or solder paste reflow process.

[0008] The driving circuit includes a plurality of driving ICs disposed on the back of the printed circuit board by flip-chip bonding, a connector for connecting each of the driving ICs, and a flexible circuit board connecting the connector to an external main control driving board. The printed circuit board is provided with blind holes or through holes. The driving ICs are electrically connected to the LED chips through the blind holes or through holes, and each of the driving ICs is located directly behind the area of ​​the LED chip it drives.

[0009] An optical system is provided in the light-emitting direction of the self-emissive display module to collimate, reflect, and amplify the light emitted by the self-emissive display module so as to project the image as a virtual image onto a predetermined position.

[0010] Optionally, in one embodiment, the printed circuit board uses FR4 substrate with a glass transition temperature of not less than 180°C, and the surface of the printed circuit board is covered with white solder resist ink.

[0011] Optionally, in one embodiment, the light-emitting surface of the self-emissive display module is attached with an anti-reflection and anti-reflection cover plate, and the surface of the anti-reflection and anti-reflection cover plate is provided with an anti-reflection coating and an anti-fingerprint coating.

[0012] Optionally, in one embodiment, a metal heat sink or via array is provided on the inner layer of the printed circuit board at the corresponding positions of the LED chip and the driver IC, and the driver circuit is mounted with a metal heat sink.

[0013] Optionally, in one embodiment, the optical system comprises, in sequence along the optical path direction:

[0014] A collimating and homogenizing element is disposed close to the light-emitting surface of the self-emissive display module to converge and homogenize the emitted light from the self-emissive display module.

[0015] A plane mirror is used to fold the optical path and pre-correct the image. The surface of the plane mirror is coated with an anti-reflective dielectric film, and the reflectivity to the visible light band is not less than 95%.

[0016] A concave mirror is used to magnify the light reflected by the plane mirror and project it to a predetermined position to form a virtual image at a distance.

[0017] The collimating and homogenizing element, the planar reflector and the concave reflector are arranged in a zigzag pattern, and the predetermined position is the windshield of the vehicle or an independent transparent reflective glass.

[0018] Optionally, in one embodiment, the collimating and homogenizing element is a microstructured lens array or a Fresnel lens.

[0019] Optionally, in one embodiment, the plane mirror is mounted on a bracket with a hinge mechanism and connected to an electric adjustment mechanism to adjust the tilt angle of the plane mirror.

[0020] Optionally, in one embodiment, the concave mirror is a freeform mirror or a Fresnel mirror.

[0021] Optionally, in one embodiment, a wedge-shaped PVB film or coating is disposed in the windshield interlayer, and a narrow-band reflective film is coated on the surface of the transparent reflective glass.

[0022] The reflectivity of the windshield or the transparent reflective glass to the light emission band of the self-emissive display module is not less than 50%, and the transmittance to the remaining visible light bands is not less than 70%.

[0023] The present invention also provides an automobile, including: an instrument panel and the above-mentioned head-up display, wherein the head-up display is disposed on the instrument panel.

[0024] The technical solution provided by this invention integrates unpackaged bare chips directly onto a printed circuit board using eutectic bonding or solder paste reflow processes. Combined with the filling and covering of a black insulating layer and a transparent encapsulation layer, this significantly reduces the physical thickness and optical crosstalk of the self-emissive display module while achieving high-density LED chip array integration, thus improving brightness and contrast. The driving circuit is integrated behind the self-emissive display module using flip-chip bonding, with electrical connections achieved through blind or through-holes. This significantly shortens the signal transmission path, reduces impedance and power consumption, and improves driving response speed and anti-interference capabilities, making it particularly suitable for high-resolution, high-refresh-rate display requirements in automotive environments. The overall structure is compact, avoiding the size and cost issues of traditional optical-mechanical solutions. Furthermore, the collimation and amplification design of the optical system ensures the clarity and stability of the virtual image projection. Ultimately, this achieves a highly reliable, low-power, high-brightness, and high-contrast automotive display effect within a limited space, significantly improving visibility and driving safety in strong light environments. Attached Figure Description

[0025] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0026] Figure 1 This is a partial cross-sectional view of a self-emissive display module according to an embodiment of the head-up display of the present invention;

[0027] Figure 2 This is a schematic diagram of the driving circuit of an embodiment of the head-up display of the present invention;

[0028] Figure 3 This is a schematic diagram of the optical system of an embodiment of the head-up display of the present invention.

[0029] Among them, 10 is the self-emissive display module; 11 is the printed circuit board; 12 is the LED chip; 13 is the black insulating layer; and 14 is the transparent encapsulation layer.

[0030] 20. Driver circuit; 21. Driver IC; 22. Connector; 23. Flexible circuit board;

[0031] 30. Optical system; 31. Collimating and homogenizing element; 32. Plane mirror; 33. Concave mirror. Detailed Implementation

[0032] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and similar expressions used in this specification are for illustrative purposes only. In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of indicated technical features. Thus, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.

[0033] Furthermore, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections via an intermediate medium, or internal communication between two components. All technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0034] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] like Figures 1 to 3 As shown, an embodiment of the present invention provides a head-up display, including: a self-emissive display module 10, a driving circuit 20, and an optical system 30.

[0036] like Figure 1 As shown, the self-emissive display module 10 includes a printed circuit board 11, a plurality of LED chips 12 arranged in an array on the front side of the printed circuit board 11, a black insulating layer 13 filling between the LED chips 12, and a transparent encapsulation layer 14 covering the LED chips 12.

[0037] In this embodiment, the printed circuit board 11 uses FR4 substrate with a glass transition temperature of not less than 180°C, which possesses excellent mechanical strength, electrical properties, and heat resistance. The resin system of the printed circuit board 11 is modified to a UV-resistant and non-oxidatively discolored formula, preventing the substrate from yellowing under prolonged high irradiation and affecting reflectivity. The surface of the printed circuit board 11 is covered with a high-reflectivity white solder resist ink to improve the utilization rate of the emitted light from the LED chip 12.

[0038] In this embodiment, RGB tri-color LED chips 12 with a size of 50–100 micrometers are selected as pixel units. Currently, the 0306 specification (3×6 mil) can be used, and smaller chips such as 2×4 mil or 1×2 mil can be used in the future. Each complete pixel consists of three sub-millimeter-level LED chips 12 for red, green, and blue. The pixel pitch P is set to 0.2mm or smaller, and ultra-small pitch specifications such as 0.1mm and 0.05mm can be selected according to actual needs to achieve high-definition display effects. For example, when the pixel pitch is 0.1mm, the size of the LED chip 12 array is about 19.2cm×10.8cm to achieve a resolution of 1920×1080; if a 0.05mm pitch is used, 1080p can be achieved with a width of only 9.6cm, thus allowing a smaller self-emissive display module 10 to achieve ultra-high-definition display. With such a small pixel size, the traditional SMD (surface mount device) process is no longer applicable. Therefore, this embodiment adopts the COB (chip-on-board) process, which directly mounts the bare chip without a package onto the printed circuit board 11. This process eliminates the need for a bracket package and has the advantages of high optical efficiency and lower cost.

[0039] The LED chip 12 is electrically connected and fixed to the pads of the printed circuit board 11 through eutectic bonding or solder paste reflow process. The anode and cathode of each LED chip 12 are connected to the corresponding driving circuits, and are connected to the driver IC 21 through multi-layer traces inside the printed circuit board 11. To ensure the mounting accuracy of the tiny LED chips 12, high-precision placement equipment and a vision alignment system are used to ensure the correct soldering rate of millions of LED chips 12.

[0040] After the LED chips 12 are mounted, their surfaces undergo protective encapsulation: First, black insulating resin is used to fill the gaps between the LED chips 12, forming a smooth black insulating layer 13 to absorb stray light, prevent cross-linking between adjacent pixels, and provide a high-contrast display background while protecting the exposed LED chips 12. Then, a layer of transparent protective adhesive (such as epoxy or silicone) tens of micrometers thick is spin-coated onto the entire LED chip 12 array surface to form a transparent encapsulation layer 14, which serves to prevent moisture and dust. This transparent encapsulation layer 14 can also improve light extraction efficiency to some extent through the difference in refractive index between itself and air. Finally, an anti-reflective and anti-reflective cover plate (such as ultra-thin quartz glass or heat-resistant resin sheet) is attached to the light-emitting surface of the encapsulated self-emissive display module 10. Besides protecting the LED array from dust and mechanical damage, this further improves optical efficiency. The surface of this anti-reflective and anti-reflective cover plate can also be treated with an anti-reflective coating and an anti-fingerprint coating, reducing ambient light reflection and facilitating cleaning and maintenance.

[0041] like Figure 2The diagram shows the layout of the driving circuit 20 on the back of the self-emissive display module 10. The driving circuit 20 includes a plurality of driving ICs 21 disposed on the back of the printed circuit board 11, a connector 22 for connecting the driving ICs 21, and a flexible circuit board 23 for connecting the external main control driving board and the connector 22.

[0042] All driver ICs 21 are mounted on the back of the printed circuit board 11 using a flip-chip soldering process. The printed circuit board 11 has blind vias or through-holes, through which the driver ICs 21 are electrically connected to the LED chips 12 on the front side. To reduce wiring density, each driver IC 21 is positioned directly behind the area of ​​the LED chips 12 it drives, with copper wires connected using the shortest path to reduce signal delay and crosstalk. Decoupling capacitors, thermal sensors, and other components are also located on the back of the printed circuit board 11 for voltage regulation, filtering, and temperature monitoring to improve the stability and safety of the self-emissive display module 10. Due to the large number of pixels in the self-emissive display module 10 (approximately 2.07 million pixels for a 1080p screen, with a total of approximately 6.22 million RGB sub-pixels), multiple driver ICs 21 are used for zoned collaborative driving. Based on the resolution of the self-emissive display module 10, several areas are divided on the back of the printed circuit board 11, each area corresponding to a specific number of rows and columns of pixels, controlled by one or more driver ICs 21. The driver IC21 is preferably an automotive-grade LED display driver device, supporting 48 or more channels of output. A single driver IC21 can independently control thousands of LED chips 12. The driver IC21 supports PWM grayscale control and current adjustment functions, and can achieve at least 8 to 10-bit grayscale (256 to 1024 levels) brightness control. It can also drive the entire self-emissive display module 10 at a refresh rate of several hundred hertz, ensuring that there is no flicker that is perceptible to the naked eye.

[0043] A connector 22 is located on one edge of the back side of the printed circuit board 11, used to connect the power and data signals of all driver ICs 21. The connector 22 is connected to the external main control driver board through the flexible circuit board 23. The external main control driver board has an onboard video decoding and processing unit, which is responsible for converting the image content input from the vehicle information system into point control signals of the LED chip 12 array, and can adjust parameters such as brightness and color temperature in real time (such as automatically reducing brightness at night to prevent glare). The flexible circuit board 23 adopts a high-density differential line design to carry high-speed video data, synchronization signals, and power supply. To meet the bandwidth requirements of 1080p@60Hz or even higher refresh rate video, the flexible circuit board 23 is designed for multi-channel parallel output. Taking 1080p@60Hz 24-bit color depth video as an example, the required data rate is about 3.7 Gbps, which can be compressed or time-division multiplexed and transmitted to each driver IC 21 through multiple differential lines.

[0044] The driver IC 21 is centrally located on the back of the printed circuit board 11, generating heat during operation. Simultaneously, the high-density LED chips 12 on the front also dissipate heat when emitting light. Therefore, this invention integrates several heat dissipation optimization measures: a thick copper process is used to increase the thickness of the inner copper foil layer of the printed circuit board 11, utilizing copper's high thermal conductivity to enhance lateral heat diffusion; metal heat sinks or via arrays are placed in the inner layer of the printed circuit board 11 at the corresponding positions of the LED chips 12 and driver IC 21 to improve heat conduction along the thickness direction, rapidly transferring heat to the back surface; furthermore, a custom metal heat sink (such as aluminum alloy or copper alloy) is tightly mounted on the driver circuit 20, closely covering the main heat-generating areas, further homogenizing heat and enhancing convective heat dissipation. This metal heat sink can also be integrated with the head-up display housing, achieving structural reuse. Thanks to the high efficiency and low power consumption of the self-emissive display module 10, this head-up display can maintain thermal balance through passive cooling during normal operation, eliminating the need for forced fan cooling, thus ensuring quiet and stable system operation.

[0045] See Figure 3 The optical system 30 includes collimating and homogenizing elements 31, a plane mirror 32, and a concave mirror 33 arranged in a zigzag pattern, in order to balance imaging quality, efficiency, and structural compactness.

[0046] The original light emitted by the self-emissive display module 10 is the self-emissive light of each LED chip 12, and has a certain divergence angle. To improve subsequent projection efficiency and imaging quality, a collimating and homogenizing element 31 is disposed close to the light-emitting surface of the self-emissive display module 10. In this embodiment, the collimating and homogenizing element 31 can be a microstructure lens array (such as a combined microlens sheet) or a Fresnel lens, or a collimation system composed of multiple lenses. Its function is to converge the beam in the vertical direction, reduce the divergence angle, and allow more light to travel along the projection light path without being diffused and lost on the optical engine cavity wall; at the same time, it disperses and homogenizes the brightness distribution in the horizontal direction, avoiding grid spots or unevenness that may occur in direct imaging. By pre-processing the collimating and homogenizing element 31, the light entering the next optical element can be made more parallel and evenly distributed, thereby improving the illumination uniformity of the eye box area. This step is particularly important for traditional HUD backlights. Common methods include setting up homogenizing rods, diffusers, etc. However, since the LED chip 12 itself is densely arranged and has high brightness, the requirement for homogenization is relatively reduced. Thinner micro-optical components can be used to achieve a similar effect.

[0047] The collimated light rays are directed towards the plane mirror 32, which is a highly reflective coated glass or metal-coated mirror. It is installed at an appropriate position in front of the self-emissive display module 10, forming a certain angle with the self-emissive display module 10 and the next optical element (concave mirror 33). Its main functions are twofold: First, it folds the light path, changing the direction of light propagation and reflecting the image from the self-emissive display module 10 upwards or backwards to guide it to the next optical element. This folding design reduces the overall length of the head-up display, allowing it to better adapt to the limited vertical and horizontal space of the vehicle's dashboard. Second, it pre-corrects the image: since the virtual image needs to be projected onto the windshield and then reflected to the human eye, involving non-coaxial optics and aberrations introduced by the tilted glass, the position and angle of the plane mirror 32 can be optimized to partially correct for viewing angle shift and astigmatism. In this embodiment, the planar reflector 32 is preferably designed to be adjustable: the planar reflector 32 is fixed to a bracket with a hinge mechanism and connected to an electric adjustment mechanism (a miniature electric push rod or a stepper motor adjustment mechanism) to finely adjust the tilt angle of the planar reflector 32. This allows for dynamic adjustment of the position and clarity of the projected image during HUD installation and calibration or during vehicle use, compensating for differences in the tilt and curvature of the windshield to adapt to the windshield curvature and driver seating position of different vehicle models, ensuring that the HUD image seen by different vehicle models and drivers is clear and aligned. Furthermore, the surface of the planar reflector 32 is coated with an anti-reflective dielectric film layer, achieving a reflectivity of over 95% in the visible light band, while maximizing the transmission or absorption of external infrared heat radiation to reduce stray light and ghosting when sunlight enters.

[0048] After being reflected by the plane mirror 32, the light carries complete image information and is projected onto the concave mirror 33. The concave mirror 33 is one of the key components of the optical system 30, used to magnify the image and project it to a predetermined position to form a virtual image at a distance. In this embodiment, the concave mirror 33 is preferably a Fresnel mirror or a freeform mirror. The Fresnel mirror approximates the curved surface shape through a concentric ring structure, is thin and lightweight, and is suitable for the compact space of an vehicle; the freeform mirror, through its aspherical shape design, can simultaneously correct multiple aberrations. The concave mirror 33 is equivalent to a projection lens, further converging the collimated image from the plane mirror 32 and imaging it at a distance. Specifically, the concave mirror 33 reflects and focuses the parallel (or slightly divergent) light rays from the plane mirror 32 in the direction of the driver's field of vision. The precisely calculated curved surface causes the light rays to converge about several meters in front of the driver's eyes, forming a virtual image focal plane. For example, the virtual image distance can be designed to be 2.5m, so that the driver can clearly see the information displayed on the HUD without zooming. The concave reflector 33 also serves to magnify the image: because the self-emissive display module 10 is relatively small, optical magnification is required to present a sufficiently large field of view at a distance of 2-3 meters. This invention adjusts the radius of curvature of the concave reflector 33 to make the image size projected onto the windshield several times larger than the actual size of the self-emissive display module 10 (typical magnification 310x, adjustable as needed). It should be noted that because the self-emissive display module 10 itself has extremely high pixel density, the magnified virtual image still maintains high resolution and clarity, without noticeable pixelation.

[0049] The image magnified by the concave reflector 33 is finally projected onto the windshield of the car and reflected into the driver's eyes. The windshield acts as a semi-reflective mirror, reflecting the HUD image while allowing visibility of the surrounding scenery. To balance reflection and transparency, a wedge-shaped PVB film or coating is placed in the windshield's interlayer to overlap the virtual image reflected from the inner surface with the image reflected from the outer surface, thus eliminating double images. This invention is applicable to windshield-type (W-HUD) and combined (C-HUD) head-up displays. For W-HUDs that directly utilize the windshield, the windshield is pre-wedge-shaped during vehicle manufacturing to produce a single reflection image of the incident light from the head-up display. For C-HUDs, a dedicated transparent reflective glass (mounted on the dashboard) can be used. The surface of the transparent reflective glass is coated with a narrow-band reflective film that reflects only the light in the HUD projection band while allowing high transmission of other bands of light. In this way, the driver can see the HUD image without affecting their view of the road. It is important to emphasize that, because the self-emissive display module 10 of this invention outputs extremely high brightness, the transmittance of the transparent reflective glass can be selected to be relatively high (for example, reflecting only about 50% of the HUD light, with the rest passing through), ensuring that external scenery is minimally obstructed; even so, the high-brightness HUD image remains sufficiently clear. This is a significant improvement compared to traditional HUDs. Traditional LCD HUDs, due to limited brightness, typically have to design a high-reflectivity, low-transmittance windshield wedge film (e.g., only allowing 20% ​​of external light to pass through, reflecting 80% of the backlight), sacrificing some transparency in bright light environments. This invention can achieve a transmittance of over 70% while maintaining the required brightness for the image, improving safety and user experience.

[0050] To achieve the ideal imaging effect of minimal distortion and a large eyebox, this invention incorporates a freeform surface design into the optical system 30. A freeform surface refers to a general aspherical surface with different curvatures along two principal cross-sections on its optical surface. By carefully designing the shape of the freeform surface, various optical aberrations such as distortion, astigmatism, and chromatic aberration in the projection light path can be corrected simultaneously, ensuring that the virtual image projected by the HUD is clearly focused and undistorted, whether at the center or edge of the field of view. Furthermore, the freeform surface design expands the eyebox range. The eyebox of a HUD refers to the area within which the driver's eyes can move while still seeing the complete HUD image. This invention, through a freeform surface pupil matching design, aligns the exit pupil of the self-emissive display module 10 with the driver's entrance pupil and appropriately increases the exit pupil size, providing a larger eye movement tolerance. Even with small head movements, the driver can still see the full HUD image without losing sight of it or experiencing image loss due to slight angle deviations. This is particularly important for AR-HUDs, as the AR display content is superimposed on the real-world road scene, requiring the widest possible viewing angle. The optical system 30 of this invention is optimized to achieve a viewing angle range of at least ±15° horizontally and ±5° vertically, with an eye box size of 120mm × 50mm, sufficient to cover the positional variations of drivers of different heights. Simultaneously, utilizing a freeform surface design, a certain degree of distortion inversion correction is pre-introduced into the planar reflector 32 or concave reflector 33, ensuring that the image projected onto the curved windshield by the HUD, after hyperbolic reflection, is no longer distorted or tilted, but accurately aligned with the actual road scene. This optical pre-correction, combined with a digital distortion correction algorithm, further improves the integration of the AR-HUD virtual image with reality.

[0051] This invention incorporates measures to enhance system luminous efficiency throughout its optical design, maximizing the utilization of every ray of light. First, all optical components are made of high-quality materials and coated; lenses are made of optical-grade PMMA or glass with double-sided anti-reflection coatings; mirrors are made of high-reflectivity aluminum or dielectric films (reflectivity >95%); the windshield wedge film design ensures transparency while maintaining the required 50% or higher reflectivity for the HUD light. Second, key surfaces in the optical path (such as the collimating and homogenizing element 31 and the concave mirror 33) employ an optical "aperture matching" design to prevent stray light from outside the self-emissive display module 10 from entering the imaging path. For example, a field stop is placed at an appropriate position on the self-emissive display module 10, allowing only the portion of the light cone required for imaging to pass through, while blocking and absorbing the remaining stray light. Third, the inner wall of the HUD is coated with black to prevent glare from multiple reflections of any remaining light. Due to the absence of polarizer losses, the transmission / reflection efficiency of the optical system 30 itself is also improved. Statistics show that the overall optical transmission efficiency of traditional HUDs from backlight to eye is less than 10%, while the design of this invention increases the overall optical transmission efficiency to more than 50%.

[0052] This invention eliminates liquid crystal imaging losses, allowing the self-emissive display module 10 to utilize almost 100% of the luminous flux. Combined with the improved optical system 30, the overall luminous efficiency is more than an order of magnitude higher than traditional solutions. By eliminating components such as the backlight module, polarizer, and aperture in traditional HUDs, the imaging module structure of this invention is much simpler. The LED chip 12 and driving circuit 20 are highly integrated on a single printed circuit board 11, resulting in a small size and thin profile, which facilitates the overall layout of the HUD. The optical path is also simplified due to the high brightness margin; additional brightness enhancement films and polarization recovery devices are optional, thus reducing the number of optical components and adjustment complexity. The overall HUD system size is reduced, making it easier to install in limited dashboard space and adaptable to a wider range of vehicle models.

[0053] It should be noted that the above-described optical system is a preferred embodiment of the present invention, but is not limited to the only form. Those skilled in the art can adjust the layout according to specific HUD specifications. For example, in a compact HUD, the plane mirror can be omitted, and a freeform mirror can be used directly as both a collimator and an imaging mirror; or in an AR-HUD, a waveguide extender or a volume holographic grating can be added as a combiner to achieve a larger field of view. These modified designs, as long as they fall within the scope of the present invention, are also covered by this patent.

Claims

1. A head-up display, characterized by, The application relates to a self-luminous display module. The self-luminous display module (10) comprises a printed circuit board (11), a plurality of LED chips (12) arranged in an array on the front surface of the printed circuit board (11), a black insulating layer (13) filled between the LED chips (12), and a transparent encapsulating layer (14) covering the LED chips (12), wherein the LED chips (12) are bare chips without encapsulating shells and are fixed and electrically connected to the pads of the printed circuit board (11) through a eutectic bonding or a tin paste reflow process; The driving circuit (20) comprises a plurality of driving ICs (21) arranged on the back surface of the printed circuit board (11) through a flip chip process, a connector (22) for connecting the driving ICs (21), and a flexible circuit board (23) connecting the connector (22) and an external main control driving board, wherein the printed circuit board (11) is provided with blind holes or through holes, the driving ICs (21) are electrically connected to the LED chips (12) through the blind holes or the through holes, and each driving IC (21) is arranged at the back of the region of the LED chips (12) driven by the driving IC (21). The optical system (30) is arranged on the light emitting direction of the self-luminous display module (10) and is used for collimating, reflecting and amplifying the light emitted by the self-luminous display module (10) to project an image in the form of a virtual image to a predetermined position. The optical system (30) comprises, in sequence along the light path direction: A collimating and uniform light element (31) is arranged close to the light emitting surface of the self-luminous display module (10) and is used for converging and uniformizing the light emitted by the self-luminous display module (10); A plane mirror (32) is used for folding the light path and pre-correcting the image, wherein the surface of the plane mirror (32) is coated with a reflection-increasing medium film layer, and the reflectivity of the visible light band is not less than 95%; A concave mirror (33) is used for amplifying and projecting the light reflected by the plane mirror (32) to a predetermined position to form a long-distance virtual image. The collimating and uniform light element (31), the plane mirror (32) and the concave mirror (33) are arranged in a "Z" shape, and the predetermined position is the front windshield glass of a vehicle or an independent transparent reflective glass.

2. The head-up display of claim 1, wherein, The printed circuit board (11) adopts an FR4 board material with a glass transition temperature not less than 180 DEG C, and the surface of the printed circuit board (11) is covered with white solder resist ink.

3. The head-up display of claim 1, wherein, The light emitting surface of the self-luminous display module (10) is attached with an anti-reflection and anti-fingerprint cover plate, and the surface of the cover plate is provided with an anti-reflection coating film and an anti-fingerprint coating layer.

4. The head-up display of claim 1, wherein, Metal heat dissipation blocks or via arrays are arranged in the inner layer of the printed circuit board (11) at the positions corresponding to the LED chips (12) and the driving ICs (21), and the driving circuit (20) is attached with a metal heat dissipation plate.

5. The head-up display of claim 1, wherein, The collimating and uniform light element (31) is a microstructure lens array or a Fresnel lens.

6. The head-up display of claim 1, wherein, The plane mirror (32) is installed on a support with a hinge mechanism and is connected with an electric adjusting mechanism to adjust the inclination angle of the plane mirror (32).

7. The head-up display of claim 1, wherein, The concave mirror (33) is a free-form surface mirror or a Fresnel mirror.

8. The head-up display of claim 1, wherein, The wedge-shaped PVB film or coated film is arranged in the front windshield interlayer, the transparent reflective glass surface is coated with a narrow-band reflective film, and the reflectivity of the front windshield or the transparent reflective glass to the light-emitting wave band of the self-luminous display module (10) is not less than 50%, and the transmittance to the remaining visible light wave band is not less than 70%.

9. An automobile characterized by comprising: The head-up display according to any one of claims 1 to 8 is arranged on the instrument panel.

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