WO2022143294A1 - 一种hud系统及车辆 - Google Patents

一种hud系统及车辆 Download PDF

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Publication number
WO2022143294A1
WO2022143294A1 PCT/CN2021/139994 CN2021139994W WO2022143294A1 WO 2022143294 A1 WO2022143294 A1 WO 2022143294A1 CN 2021139994 W CN2021139994 W CN 2021139994W WO 2022143294 A1 WO2022143294 A1 WO 2022143294A1
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Prior art keywords
image
vertical
horizontal
plane
light
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PCT/CN2021/139994
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English (en)
French (fr)
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李仕茂
王金蕾
邹冰
闫云飞
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华为技术有限公司
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Publication of WO2022143294A1 publication Critical patent/WO2022143294A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
    • B60K35/60—Instruments characterised by their location or relative disposition in or on vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R1/00—Optical viewing arrangements; Real-time viewing arrangements for drivers or passengers using optical image capturing systems, e.g. cameras or video systems specially adapted for use in or on vehicles
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0179—Display position adjusting means not related to the information to be displayed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
    • B60K2360/20—Optical features of instruments
    • B60K2360/33—Illumination features
    • B60K2360/334—Projection means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
    • B60K2360/77—Instrument locations other than the dashboard
    • B60K2360/785—Instrument locations other than the dashboard on or in relation to the windshield or windows
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0179—Display position adjusting means not related to the information to be displayed
    • G02B2027/0183—Adaptation to parameters characterising the motion of the vehicle

Definitions

  • the present application relates to the technical field of HUD systems, and in particular, to a HUD system and a vehicle.
  • Head-up display is a device that projects instrument information (such as speed) and navigation information to the front of the driver's field of vision.
  • the control display can improve the braking reaction time in emergency situations and improve driving safety.
  • the imaging principle of the HUD system can be seen in Figure 1a: the instrument information and navigation information are generated by the picture generation unit (PGU) in the HUD system, and then a virtual image is formed in front of the car through the curved mirror and the windshield.
  • PGU displays are pixelated, and the number of pixels included in landscape and portrait is not the same, such as 16:9. The higher the number of pixels that the PGU includes, the higher the resolution of the displayed image.
  • the virtual image is generally larger than the actual display area of the PGU. Therefore, it is usually necessary to enlarge the image generated by the PGU.
  • the image generated by the PGU can be enlarged in the horizontal and vertical proportions (that is, the horizontal enlargement ratio is equal to the vertical enlargement ratio), as shown in Figure 1b, if the display chip formed by all the pixels of the PGU (ie the actual display area) After the vertical proportional magnification, since the size and position of the virtual image are pre-designed, the human eye may only see part of the virtual image (called the effective display area), and the virtual image outside the effective display area cannot be seen. Therefore, the effective display area of the PGU will be smaller than that of the display chip, thereby causing a waste of physical display resources of the PGU.
  • method 2 is proposed, the horizontal magnification is greater than the vertical magnification, as shown in Figure 1c, so that the effective display area of the PGU is the display chip, but because the horizontal magnification is different from the vertical magnification, it will cause the image to have a large magnification.
  • the direction is stretched, that is, the virtual image is distorted, so the distortion of the virtual image needs to be corrected.
  • the present application provides a HUD system and a vehicle, which are used to solve the problem in the prior art that a display chip that can fully utilize the PGU cannot be realized without correcting virtual image distortion.
  • the present application provides a HUD system
  • the HUD system may include M PGUs and an optical imaging unit
  • the PGUs include rectangular pixels
  • M is a positive integer.
  • the PGU is used to generate an image and transmit the light of the image to the optical imaging unit.
  • the optical imaging unit is used to enlarge the image horizontally and vertically, respectively, and transmit the light of the enlarged image to the windshield; the reverse extension line of the light of the enlarged image reflected by the windshield A void is formed at the first preset position.
  • the horizontal magnification is different from the vertical magnification, and the horizontal pixel density of the virtual image is the same as the vertical pixel density.
  • the horizontal magnification ratio to be different from the vertical magnification ratio, it is helpful to make full use of the display chip of the PGU.
  • the image generated by the PGU with rectangular pixels will introduce optical distortion.
  • the difference between the horizontal magnification and the vertical magnification can produce reverse optical distortion, so that the horizontal pixel density of the virtual image can be the same as the vertical pixel density. Therefore, the formed virtual image will not Distortion is generated, so that correction of the virtual image is also not required.
  • the ratio of the horizontal width to the vertical width of the rectangular pixel is equal to the ratio of the vertical enlargement ratio to the horizontal enlargement ratio.
  • the lateral magnification is determined according to the lateral width of the PGU, the virtual image distance of the HUD system, and the lateral field of view of the HUD system; the vertical magnification is determined according to the PGU is determined by the longitudinal width of the HUD system, the virtual image distance of the HUD system and the longitudinal field of view of the HUD system.
  • the lateral magnification ratio 2 ⁇ the virtual image distance of the HUD system ⁇ tan (lateral field of view/2)/the lateral width of the PGU;
  • the vertical magnification ratio 2 ⁇ the virtual image distance of the HUD system ⁇ tan (longitudinal Field of view/2)/Longitudinal width of the PGU.
  • the optical imaging unit is used for enlarging the image horizontally and vertically, respectively changing the propagation path of the light of the image on the horizontal plane and the vertical plane, and enlarging and changing the path.
  • the rear light is propagated to the windshield; wherein, the reversed extension line of the enlarged and changed light after being reflected by the windshield is focused on the vertical image plane on the vertical plane, and focuses on the horizontal image plane on the horizontal plane.
  • the vertical image plane and the horizontal image plane are in different positions, and the distance between the vertical image plane and the center of the eye box is determined according to the preset angular resolution, and the eye box is the driver's double image plane. target area. Further, optionally, the distance between the horizontal image plane and the center of the eye box is the virtual image distance of the HUD.
  • the vertical image plane and the horizontal image plane can be separated by the optical imaging unit, and the virtual image distance of the HUD can be flexibly adjusted by adjusting the position of the horizontal image plane. Also, since the ghost of the virtual image perceived by the human eye is on the vertical image plane, the adjustment of the virtual image distance and the elimination of the ghost are decoupled.
  • the optical imaging unit can be used to pull the vertical image plane away to a position where the ghost of the virtual image can be eliminated, that is, the first preset position. It can also be understood that when the vertical virtual image plane is at the first preset position, usually the driver's binocular cannot distinguish the main image and the secondary image, thereby eliminating the ghost of the virtual image.
  • the optical imaging unit may include a first curved mirror, and the lateral focal length of the first curved mirror is different from the longitudinal focal length.
  • the optical imaging unit may include a second curved mirror reflection and a cylindrical mirror, the cylindrical mirror is located on a horizontal plane or a vertical plane, the horizontal image plane is located on the horizontal plane, and the vertical image plane is located on the vertical plane.
  • the optical imaging unit may include a third curved reflection mirror and a fourth curved reflection mirror, and at least one of the third curved reflection and the fourth curved reflection mirror has a different lateral focal length and longitudinal focal length.
  • the optical imaging assembly further includes a zoom lens.
  • the zoom lens can be used to change the position and/or the horizontal magnification of the horizontal image plane by adjusting the horizontal focal length; or, the zoom lens can be used to change the position of the vertical image plane and/or the vertical magnification by adjusting the vertical focal length Rate.
  • the zoom lens can be used to change the position and/or the horizontal magnification of the horizontal image plane by adjusting the horizontal focal length, and the zoom lens can be used to change the position and/or vertical direction of the vertical image plane by adjusting the vertical focal length magnification.
  • the imaging position control, lateral magnification and/or longitudinal magnification control of the entire HUD system can be achieved through the zoom lens.
  • the M PGUs include a first PGU and a second PGU
  • the optical imaging unit includes a flat mirror, a second curved mirror, and a cylindrical mirror
  • the flat mirror is used for Reflect the light from the image of the first PGU to the second curved mirror
  • the cylindrical mirror changes the propagation path of the light from the image of the second PGU, and changes the propagation path of the light.
  • the second curved mirror is used for laterally enlarging and longitudinally enlarging the image formed by the light from the cylindrical mirror, and propagating the light of the enlarged image to the Windshield, the reverse extension line of the light reflected by the windshield is focused on the vertical image plane on the vertical plane, and focused on the horizontal image plane on the horizontal plane; and the light from the plane mirror is formed into a
  • the image is enlarged horizontally and vertically, and the light of the enlarged image is propagated to the windshield, and a reverse extension line of the light reflected by the windshield forms a virtual image at a second preset position.
  • the HUD includes multiple PGUs
  • multiple virtual images with different depths can be formed, that is, one PGU corresponds to a virtual image at one location.
  • the second preset position is determined according to a preset angular resolution, the center position of the eye box, the incident angle of incident light, the thickness of the windshield, and the refractive index of the windshield. of.
  • the second preset position may be a position where virtual image ghosting can be eliminated. It can also be understood that when the virtual image is at the second preset position, the driver's binoculars are usually unable to distinguish the main image and the auxiliary image, thereby eliminating the ghost of the virtual image.
  • the present application provides a vehicle, which may include any one of the first aspect or the first aspect of the HUD system and a windshield; the windshield is used to reflect light from the HUD system to the eye box , the eye box is the area where the driver's eyes are located.
  • the windshield includes a wedge-type windshield or a plane-type windshield.
  • the ghost can be eliminated by selecting an appropriate wedge angle ⁇ , and the horizontal image plane and the vertical image plane can be separated, which can realize the adjustment of the virtual image distance of the HUD and the decoupling of eliminating ghosts, so that it can be flexibly Adjust the virtual image distance of the HUD.
  • Fig. 1a is a schematic diagram of the imaging principle of a HUD system in the prior art
  • Figure 1b is a schematic diagram of an image of a display chip formed by all the pixels of a PGU in the prior art after being enlarged in equal proportions in the horizontal and vertical directions;
  • Fig. 1c is a schematic diagram of a display chip formed by all the pixels of a PGU in the prior art after the magnification of the horizontal magnification ratio is greater than that of the vertical magnification ratio;
  • 2a is a schematic diagram of the relationship between the physical size and resolution of a pixel under the same photosensitive area provided by the application;
  • Fig. 2b is another schematic diagram of the relationship between pixel physical size and resolution under the same photosensitive area provided by the application;
  • 2c is a schematic diagram of a field of view and a virtual image distance provided by the application
  • 2d is a schematic structural diagram of a plano-convex cylindrical mirror provided by the application.
  • 2e is a schematic structural diagram of a plano-concave cylindrical mirror provided by the application.
  • 3a is a schematic diagram of a possible application scenario provided by the present application.
  • Figure 3b is a schematic structural diagram of a W-HUD system provided by the application.
  • 3c is a schematic structural diagram of an AR-HUD system provided by the application.
  • FIG. 4 is a schematic structural diagram of a HUD system provided by the application.
  • 5a is a schematic structural diagram of a PGU provided by the application including 10 ⁇ 4 rectangular pixels;
  • 5b is a schematic diagram of a virtual image provided by the application in which the horizontal pixel density and the vertical pixel density of a virtual image are equal;
  • 5c is a schematic diagram of the imaging optical path of a HUD system provided by the application.
  • FIG. 6a is a schematic structural diagram of an LCoS provided by the application.
  • 6b is a schematic structural diagram of a PGU provided by the application.
  • 6c is a schematic structural diagram of a backlight system provided by the application.
  • FIG. 6d is a schematic diagram of a light propagation path with extension matching provided by the application.
  • FIG. 7a is a schematic diagram of a schematic diagram for generating ghosting provided by the application.
  • Fig. 7b is a kind of effect diagram schematic diagram of generating ghosting provided by the application.
  • 7c is a schematic diagram of the relationship between an image angle and a virtual image distance provided by the application.
  • FIG. 8 is a schematic diagram of a vertical plane and a horizontal plane provided by the application.
  • Figure 9a is a schematic diagram of focusing of an imaged light at different x positions of the retina of both eyes provided by the application;
  • Fig. 9b is a schematic diagram of another kind of imaging light focusing provided by the application at the same y position of the retina of both eyes;
  • 10a is a schematic diagram of the architecture of a HUD system provided by the application.
  • FIG. 10b is a schematic diagram of the architecture of another HUD system provided by the application.
  • Figure 10c is a schematic diagram of the architecture of another HUD system provided by the application.
  • Figure 11a is a schematic diagram of a simplified vertical optical path provided by the application.
  • Fig. 11b is a schematic diagram of the optical path of a simplified horizontal plane provided by the application.
  • 12a is a schematic structural diagram of a liquid lens provided by the application.
  • FIG. 13 is a schematic diagram of another HUD system architecture provided by this application.
  • FIG. 14 is a simplified schematic diagram of a partial structure of a vehicle provided by the application.
  • FIG. 15 is a schematic structural diagram of a wedge-shaped windshield provided by the application.
  • a pixel refers to the smallest unit that constitutes an imaging area.
  • the horizontal width and vertical width of a pixel refer to the physical size of the pixel (see Figures 2a and 2b below).
  • Pixel density represents the number of pixels included per inch. The higher the PPI value, the higher the density of the image can be displayed.
  • the resolution and the physical size of the pixel are trade-offs.
  • the relationship between pixel physical size and resolution under the same photosensitive area The horizontal and vertical widths of the pixels in Fig. 2a are both a, and the resolution is 4 ⁇ 4; the horizontal and vertical widths of the pixels in Fig. 2b are both a/2, and the resolution is 8 ⁇ 8. It can be determined from Figure 2a and Figure 2b that the smaller the pixel size, the higher the resolution; the larger the pixel size, the lower the resolution.
  • VID Virtual image distance
  • the virtual image distance refers to the distance between the center of the eye box and the center of the virtual image, as shown in Figure 2c below.
  • the virtual image distance may be represented by V.
  • the field of view includes a horizontal field of view (H_FOV) and a vertical field of view (V_FOV).
  • the horizontal field of view refers to the maximum visible range of the HUD system in the horizontal direction
  • the vertical field of view refers to the maximum visible range of the HUD system in the vertical direction, as shown in Figure 2c.
  • the horizontal field of view angle may also be referred to as a horizontal field of view angle
  • the vertical field of view angle may also be referred to as a vertical field of view angle.
  • the lateral viewing angle may be determined by the following formula 1
  • the longitudinal viewing angle may be determined by the following formula 2.
  • Cylindrical mirrors have curvature in one dimension, enabling one-dimensional shaping. It can also be understood as diffusing or converging light in one dimension and reflecting light in another dimension. For example, plano-convex cylindrical mirror (see Figure 2d), plano-concave cylindrical mirror (see Figure 2e).
  • Angular resolution refers to the resolving power of an imaging system, that is, the ability to differentiate the smallest distance between adjacent objects. It is generally expressed by the size of the angle between the two smallest distinguishable objects by the imaging system.
  • the angular resolution of the human eye refers to the resolving power of the human eye.
  • the light-emitting object Since the light-emitting object is not on the optical axis of the optical system, the light emitted by it has an oblique angle with the optical axis. After the ray is refracted by the lens, the convergence point of its sub-vertical ray and the horizontal ray is not at the same point. That is, the light cannot be focused on a point, and the image is not clear, so astigmatism occurs.
  • This application scenario takes the HUD system applied to the car as an example.
  • the HUD system is used to form an enlarged virtual image of instrument information and navigation information, and project it into the driver's field of vision through the windshield of the car, so as to present a virtual image to the driver at a distance (for example, 2 to 20m) away from the road.
  • a distance for example, 2 to 20m
  • the driver's eyes usually need to be in the eyebox. It will be appreciated that if the human eye is aligned with the center of the eye box, a complete and sharp virtual image can be obtained.
  • the general size of the eye box is 130mm ⁇ 50mm, that is, the eye box has a moving range of about ⁇ 50mm in the longitudinal direction and a moving range of about ⁇ 130mm in the lateral direction.
  • the HUD system provided in this application can also be applied to other scenarios, such as an aircraft (such as a fighter jet), etc.
  • the driver on the fighter jet can track and target objects based on the HUD system, thereby helping Improve combat success and flexibility.
  • the HUD system may be a windshield (W)-HUD system or an augmented reality (AR)-HUD system.
  • FIG. 3b exemplarily shows a schematic structural diagram of the W-HUD system for the present application.
  • the W-HUD system includes a PGU and curved mirrors. The image generated by the PGU is projected to the windshield and then reflected by the windshield to the driver's binocular imaging. The reverse extension of the image formed by the driver's binocular forms a virtual image in front of the car. Since the W-HUD system is integrated with the body, the safety is high, and it can also be called a front-mounted HUD system.
  • the virtual image distance of the W-HUD system is between 2 and 3m.
  • FIG. 3c is a schematic structural diagram of an AR-HUD system exemplarily shown in the present application.
  • the AR-HUD system can superimpose virtual information such as navigation on the real road surface, so that it can display richer content; and the virtual image distance of the AR-HUD system is generally greater than 5m, which can better realize the combination of virtual and real.
  • the virtual image displayed by the AR-HUD system needs to be combined with the real scene, which requires the car to have precise positioning and detection functions.
  • the AR-HUD system needs to cooperate with the advanced driving assistant system (ADAS) system of the car.
  • ADAS advanced driving assistant system
  • the number of pixels included in the horizontal direction of the PGU is different from the number of pixels included in the vertical direction.
  • the ratio of the number of pixels in the horizontal direction to the number of pixels in the vertical direction is 16:9.
  • the horizontal field of view and the vertical field of view are also different in the field of view of the HUD system, for example, the ratio of the horizontal field of view to the vertical field of view is 3:1.
  • the ratio of the horizontal field of view to the vertical field of view of the HUD-based system is different from the ratio of the horizontal pixels to the vertical pixels of the PGU.
  • the virtual image formed by the HUD system in the prior art either cannot make full use of the display chip of the PGU, resulting in a waste of physical resources of the PGU; or it will cause image distortion, resulting in the low efficiency of the HUD system to display images due to the distortion correction.
  • the drive circuit is complicated and so on.
  • the present application proposes a HUD system.
  • the HUD system can not only realize the full use of the display chip of the PGU, but also will not cause distortion of the virtual image in the process of amplifying the image generated by the PGU.
  • the HUD system may include M image generating units PGU401 and optical imaging units 402 .
  • the PGU401 includes rectangular pixels, and the M is a positive integer; the PGU401 is used to generate an image and propagate the image to the optical imaging unit 402; the optical imaging unit 402 is used to enlarge the image horizontally and vertically, respectively Amplify, and transmit the light of the enlarged image to the windshield; the light of the enlarged image is reflected by the windshield to form a virtual image at the first preset position by the reverse extension line.
  • the horizontal pixel density of the virtual image is the same as the vertical pixel density, and the horizontal magnification is different from the vertical magnification.
  • the light of the image can also be understood as the light that carries the image information.
  • the horizontal enlargement ratio is greater than the vertical enlargement ratio, and the enlarged image is equivalent to stretching the original image horizontally.
  • the horizontal magnification ratio is smaller than the vertical magnification ratio, and the enlarged image is equivalent to stretching the image to the vertical direction.
  • the horizontal magnification ratio to be different from the vertical magnification ratio, it is helpful to make full use of the display chip of the PGU.
  • the image generated by the PGU with rectangular pixels will introduce optical distortion.
  • the reverse optical distortion can be generated by the difference between the horizontal magnification and the vertical magnification, so that the horizontal pixel density of the virtual image can be the same as the vertical pixel density. Therefore, the formation of virtual images will not Distortion is generated, so that correction of the virtual image is also not required.
  • the PGU may include k ⁇ n rectangular pixels.
  • FIG. 5a a schematic diagram of a PGU provided by the present application including 10 ⁇ 4 rectangular pixels.
  • the resolution of the images produced by this PGU is non-uniform.
  • the horizontal width of the display chip of the PGU is h
  • the vertical width is l. It can also be understood that if the display chip of the PGU is fully utilized, the horizontal width of the effective display area is h, and the vertical width is l.
  • the horizontal width of the virtual image to be displayed is H and the vertical width is L
  • the horizontal magnification ratio M1 H/h
  • the vertical magnification ratio M2 L/l. It should be understood that the horizontal width and vertical width of the virtual image are pre-designed.
  • the PGU includes the same number of pixels as the virtual image.
  • the horizontal direction of the PGU includes k rectangular pixels, and the vertical direction includes n rectangular pixels, and the virtual image also includes k pixels in the horizontal direction and n pixels in the vertical direction.
  • the ratio r of the horizontal width to the vertical width of each rectangular pixel included in the PGU can be determined. For details, please refer to the following formula 1.
  • the ratio r of the horizontal width to the vertical width of the rectangular pixels included in the PGU is equal to the ratio of the vertical magnification to the horizontal magnification.
  • the imaging optical path of the HUD system can be simplified as the optical path shown in Fig. 5c.
  • the ratio r of the horizontal width to the vertical width of each rectangular pixel can be determined as the following formula 2.
  • the ratio r of the horizontal width to the vertical width of the rectangular pixels included in the PGU is related to the vertical viewing angle, the lateral viewing angle, the lateral width of the PGU and the vertical width of the PGU of the HUD system.
  • ⁇ 1 13 degrees
  • ⁇ 2 5 degrees
  • the horizontal width and vertical width of each rectangular pixel can be determined.
  • the display chips of the PGU can be fully utilized by the difference of the horizontal magnification ratio and the vertical magnification ratio.
  • the pixels included in the PGU can be designed to be rectangular pixels, and the vertical width of the pixel is larger than the horizontal width. ratio of rates.
  • the horizontal and vertical widths of the rectangular pixels included in the PGU can be selected; or the horizontal and vertical magnification ratios can be determined based on the horizontal and vertical widths of the rectangular pixels included in the PGU.
  • the PGU may be a liquid crystal display (LCD), a digital micromirror display (DMD), a liquid crystal on silicon (LCoS) or a laser light scanning ( laser beam scanning, LBS).
  • LCD liquid crystal display
  • DMD digital micromirror display
  • LCDoS liquid crystal on silicon
  • LBS laser beam scanning
  • the LCD technology can control the liquid crystal state through voltage, thereby changing the polarization state of the backlight, and cooperate with the polarizer to realize the intensity modulation of light.
  • the intensity of the light can be modulated pixelated, and finally an image is formed.
  • the PGU in a W-HUD system is an LCD.
  • the pixelated modulated light intensity can be understood as the size of the light intensity of the corresponding area that can be controlled by a pixel.
  • LCoS is also a liquid crystal technology.
  • the difference from LCD is that it is reflective, and the incident light is reflected on the silicon wafer after passing through the liquid crystal.
  • the direction of the long axis of the liquid crystal molecules can be changed by changing the applied voltage signal or current signal to change the LCoS refractive index, thereby changing the phase of the light passing through the LCoS. It is equivalent to using the retardation of the phase to rotate the polarization state of the light, and cooperate with the polarizing beam splitter (PBS) to realize the modulation of the light intensity.
  • PBS polarizing beam splitter
  • the image size displayed by LCoS and DMD chips is generally less than 1 inch, and the generated image is directly enlarged.
  • the horizontal and vertical magnification ratios are relatively large, and the optical path is difficult to achieve.
  • LBS The imaging principle of LBS is relatively simple. It is that the laser is incident on the MEMS mirror, and the deflection of the MEMS can be controlled to scan the laser in space to form an image on the diffusion screen.
  • the light spot formed by the light emitted by the light source is not uniform, and the shape of the light spot does not match the display chip. Therefore, there are backlight systems for non-self-illuminating PGUs. That is, the light emitted by the light source is incident on the display chip after being uniformly lighted by the backlight system, and an image is generated after spatial modulation.
  • the backlight system may include a collimating lens, a fly-eye lens 1 , a fly-eye lens 2 and a relay lens.
  • both the fly-eye lens 1 and the fly-eye lens 2 include three sub-eyes as an example. It should be noted that the more sub-eyes included in the fly-eye lens, the better the uniform light effect.
  • the number of sub-eyes included in the fly-eye lens 1 and the fly-eye lens 2 are the same and correspond one-to-one.
  • FIG. 6c is only an exemplary structure of a backlight system, and the actual backlight system may also include color combination or color separation optical elements, and there will be other components in different PGUs, such as LCoS general It also includes a polarization conversion unit, etc., which is not limited in this application.
  • the fly-eye lens can also be replaced with a light rod. If it is a fly-eye lens, the ratio of the horizontal width to the vertical width of each sub-eye is equal to the ratio of the horizontal width to the vertical width of the PGU display chip; if it is a light bar, the ratio of the horizontal width to the vertical width of the cross section of the light bar is equal to the ratio of the display chip The ratio of horizontal width to vertical width.
  • etendue is a very important concept, and the conservation of etendue should be considered when designing optical systems to reduce losses.
  • the etendue is the product of the area and the aperture angle. As shown in Figure 6d, the light is incident from the incident aperture D in and exits from the exit aperture D out . Since the exit aperture D out is small, if the etendue is conserved in this process, the outgoing The angle will become larger.
  • PGU in order to improve the utilization rate of light, it is necessary to consider the etendue matching of each optical element. Along the direction of light propagation, the etendue of the rear optical element cannot be smaller than that of the front optical element, otherwise it will bring loss.
  • the ratio of the horizontal width to the vertical width of the PGU cannot be too large.
  • the ratio of the horizontal width to the vertical width of the sub-eye is equal to the ratio of the horizontal width to the vertical width of the PGU. If the ratio of the horizontal width to the vertical width of the sub-eye is too large, it is difficult to match the extension of the light source. .
  • the ratio of the lateral width to the vertical width of the light-emitting area of the LED light source is generally less than 2:1, and the divergence angle is large and the collimation spot is large.
  • the ratio of the horizontal width to the vertical width of the PGU is usually designed to be close to 1, such as 16:9; it is not directly designed to be the same as the ratio of the horizontal field of view to the vertical field of view (3:1) of the virtual image.
  • the PGU can also be a structure other than the above-mentioned exemplary structure, for example, it can also be an organic light emitting diode (organic light emitting diode, OLED), or a micro light emitting diode (micro light emitting diode, micro-LED) etc.
  • OLED organic light emitting diode
  • micro-LED micro light emitting diode
  • the light-emitting display screen is not limited in this application.
  • the windshield In order to prevent the windshield from being broken as a whole after being hit, the windshield usually includes two layers of glass and a layer of polyvinyl butyral (PVB) material sandwiched between the two layers of glass.
  • the refractive index of the PVB material is the same as that of the glass.
  • the windshield can be simplified as a flat glass with a certain thickness (usually 4-5mm). Since the windshield has a certain thickness, the formed virtual image will have a ghost image.
  • FIG. 7a a schematic diagram of a principle diagram for ghost generation provided by the present application. Light will be reflected on the front and rear surfaces of the windshield.
  • the reflection of the object on the front and outer surfaces of the windshield forms the main image
  • the reflection on the rear inner surface of the windshield forms a secondary image
  • Partial overlap of the two images is called ghosting.
  • the distance between the main image and the auxiliary image is related to the thickness of the windshield.
  • the interval between the main image and the auxiliary image is fixed.
  • both the main image and the secondary image are virtual images.
  • the angle formed by the main image and the auxiliary image with the driver's eyes is called the image angle ⁇ . If the incident angle of the light entering the front outer surface of the windshield is ⁇ , the main image reaches the driver's eyes.
  • the optical distance i.e. virtual image distance
  • the thickness of the windshield is t
  • the refractive index of the windshield is n
  • the image angle ⁇ can be determined according to the principle of mirror imaging.
  • ⁇ represents the incident angle of the light of the secondary image on the front outer surface
  • ⁇ 1 represents the refraction angle of the light of the secondary image on the front outer surface
  • the angular resolution of the human eye is 1 arc minute, about 0.017°.
  • the included image angle ⁇ is greater than the angular resolution of the human eye, the human eye will see a double image, as shown in Figure 7b, the effect of the double image seen by the human eye.
  • the image angle ⁇ is not greater than the angular resolution of the human eye, the human eye cannot see the ghost.
  • the incident angle ⁇ depends on the angle between the windshield and the ground, the angle formed by the connection line between the center position of the eye box and the virtual image and the ground, which is usually a fixed value; the thickness of the windshield t and the refractive index n of the windshield are also relatively fixed; therefore, in order to eliminate the ghost of the virtual image, when designing the HUD system, the virtual image distance (a+b) can be adjusted to eliminate the ghost of the virtual image.
  • FIG. 7c a schematic diagram of the relationship between the included image angle ⁇ and the virtual image distance (a+b) is provided for this application. It can be seen from Figure 7c that the larger the virtual image distance (a+b) is, the smaller the image angle ⁇ is. When the virtual image distance (a+b) is not less than 12 meters, the image angle ⁇ is not greater than the angular resolution of ordinary human eyes 0.017 °. It can also be understood that when the virtual image distance is large enough, the human eye cannot distinguish the main image and the secondary image, that is, the ghost of the virtual image can be eliminated. It should be understood that this method of eliminating ghosting can be applied to a HUD system with a virtual image distance of not less than 12 meters, such as an AR-HUD system.
  • the yoz plane perpendicular to the binocular is the vertical plane (or called the meridional plane). It can also be understood that the vertical plane is the plane perpendicular to the binocular connection line and passing through the binocular center.
  • the rays located in the vertical plane are called vertical rays (or meridian rays), and the position where the vertical rays are focused is called the vertical image plane (or meridian image plane).
  • the xoz plane parallel to the binocular is the horizontal plane (or called the sagittal plane), and the sagittal plane is perpendicular to the meridional plane.
  • the rays located in the horizontal plane are called horizontal rays (or sagittal rays), and the position where the horizontal rays are focused is called the horizontal image plane (or sagittal image plane).
  • the angle of the windshield relative to the driver is close to 90 degrees, that is, when the incident light is vertically incident, the incident angle ⁇ is very small. It can be seen from Figure 7a that the image angle ⁇ is close to zero. Therefore, the heavy Shadows are only considered in the vertical plane. That is, the primary and secondary images observed by the driver are staggered in the y direction. It can also be understood that the included image angle ⁇ can be reduced by increasing the distance between the vertical image plane and the eye box. It should be understood that the driver's eyes are usually in the center of the eye box.
  • the depth information of the object perceived by the driver is mainly realized by binocular disparity.
  • the eye is equivalent to an imaging system.
  • the light of the object enters the retina of the human eyeball to form an image, and the image information is received by the neurons on the retina and transmitted to the brain to form an image experience.
  • the same object will form images at different positions of the binocular retina. According to the size of the difference between the two positions of the binocular retina, the brain can "calculate" the distance of the object.
  • the driver's binocular is horizontally distributed left and right, then the imaged light will be focused at different x positions of the binocular retina, as shown in Figure 9a, on the vertical plane, the binocular is in the same position, so the light is in the The binocular retinas are focused at the same y position, as shown in Figure 9b. That is, the horizontal rays of the horizontal plane (xoz plane) focus on different positions of the binocular retina, while the vertical rays of the vertical plane (yoz plane) focus on the same position of the binocular retina.
  • the position of the virtual image is judged by the brain as the position of the horizontal image plane, and the position of the vertical image plane has no effect on the distance that people perceive the virtual image; moreover, as can be seen from Figure 7a, the ghost is generated on the vertical image plane.
  • the optical imaging unit is introduced in detail.
  • the optical imaging unit is used to enlarge the image horizontally and vertically, and change the propagation path of the light of the image on the horizontal plane and the vertical plane, respectively, and enlarge and change the image.
  • the optical imaging unit can enlarge the image horizontally and vertically, and can also separate the vertical image plane from the horizontal image plane (that is, the horizontal image plane and the vertical image plane are not at the same position, see FIG.
  • Astigmatic image An image with astigmatism is one where the rays of the image are present in both the vertical and horizontal planes.
  • the position of the vertical image plane may be determined according to the center position of the eye box. Further, optionally, the position of the vertical image plane may be determined according to the center position of the eye box and the preset angular resolution. Exemplarily, the position of the vertical image plane can be determined in combination with the above formulas 4 to 6.
  • the preset angular resolution may be obtained by counting the angular resolutions of a large number of human eyes.
  • the preset angular resolution may be equal to 0.017°.
  • the distance between the horizontal image plane and the center of the eye box is equal to the virtual image distance of the HUD system, and the virtual image distance can be greater than the distance between the vertical image plane and the center of the eye box, or the virtual image distance can also be smaller than the vertical image distance.
  • the distance between the face and the center of the eyebox that is to say, the virtual image distance of the HUD system can be decoupled from the vertical image plane, so that the virtual image distance of the HUD system can be flexibly adjusted.
  • the optical imaging assembly may include a first curved mirror, and in order to realize the formation of a virtual image with astigmatism, the lateral focal length and the longitudinal focal length of the first free-form curved mirror are different.
  • changing the lateral focal length can be used to adjust the propagation path of the horizontal light on the horizontal plane
  • changing the vertical focal length can be used to adjust the propagation path of the vertical light on the vertical plane.
  • the optical imaging unit may include a second curved mirror and a cylindrical mirror.
  • the cylindrical mirror is located on a horizontal plane, or can also be located on a vertical plane.
  • the cylindrical mirror on the horizontal plane means that the surface with curvature is in the horizontal direction, that is, the cylindrical mirror participates in imaging on the horizontal plane.
  • the cylindrical mirror on the horizontal plane only has a divergent or converging effect on the horizontal light, and only has a specular reflection effect on the vertical light. That is to say, the cylindrical mirror on the horizontal plane can make only the horizontal light on the horizontal plane participate in the imaging.
  • the cylindrical mirror on the vertical plane means that the surface with curvature is in the vertical direction, that is, the cylindrical mirror participates in the imaging on the vertical plane.
  • the cylindrical mirror on the vertical plane only has a divergent or converging effect on the vertical light, and only has a specular reflection on the horizontal light. That is to say, the cylindrical mirror on the vertical plane can make only the vertical light on the vertical plane participate in the imaging. It should be understood that only surfaces with curvature can have a divergent or convergent effect on light.
  • the lateral focal length and the longitudinal focal length of the second curved mirror may or may not be equal, which is not limited in this application.
  • the optical imaging unit may include a third curved mirror and a fourth curved mirror, wherein a difference between the third curved mirror and at least one curved mirror in the fourth curved mirror Horizontal focal length is different from vertical focal length.
  • the HUD system may include a PGU and an optical imaging unit.
  • the optical imaging unit may include a cylindrical mirror and a second curved mirror on a horizontal plane.
  • the cylindrical mirror on the horizontal plane can propagate (eg converge or diverge) the horizontal light on the horizontal plane to the second curved mirror, and reflect the vertical light on the vertical plane to the second curved mirror.
  • the second curved mirror transmits both the light from the horizontal plane and the light from the vertical plane to the windshield, so that the vertical image plane and the horizontal image plane can be separated, and the vertical image plane can be pulled away to a position where ghost images can be eliminated.
  • the optical path of Fig. 10a can be abstracted as the optical paths of Figs. 11a and 11b, that is, the off-axis reflection system is equivalently simplified to a coaxial transmission system, so as to further explain the imaging optical path of Fig. 10a.
  • take the second curved mirror as a spherical mirror as an example take the horizontal focal length of the second curved mirror as the same as the vertical focal length (both f) as an example, and take the cylindrical mirror as a plano-concave cylindrical mirror as an example .
  • u2 represents the optical distance between the PGU and the second curved mirror, that is, the object distance of the second curved mirror
  • v2 represents the optical distance between the vertical image plane and the second curved mirror, that is, the second curved mirror
  • the image distance on the vertical plane f is the focal length of the second curved mirror
  • g is the optical distance from the center of the eye box to the second curved mirror
  • ⁇ 2 is the longitudinal field of view
  • L is the longitudinal width of the virtual image
  • l is the PGU vertical width. It should be understood that optical distance refers to the distance that light travels.
  • the plane-concave cylindrical mirror can be simplified as a concave mirror due to the parameters and imaging of the cylindrical mirror on the horizontal plane, so the optical path of the horizontal plane of Fig. 10a can be abstracted as the optical path of Fig. 11b. According to the imaging formula and geometric relationship, the following formulas 10 to 14 can be obtained.
  • u1 represents the object distance of the concave mirror
  • u0 is the image distance of the concave mirror
  • v1 represents the optical distance between the horizontal image plane and the second curved mirror, that is, the image distance of the second curved mirror on the vertical plane
  • f represents the focal length of the second curved mirror
  • g represents the optical distance from the center of the eye box to the second curved mirror
  • ⁇ 1 represents the lateral field angle
  • H represents the lateral width of the virtual image
  • h represents the lateral width of the PGU.
  • the lateral field angle ⁇ 1 13°
  • the vertical field angle ⁇ 2 5°
  • the HUD system may include a PGU and an optical imaging unit.
  • the optical imaging unit may include a cylindrical mirror and a second curved mirror on a vertical plane.
  • the cylindrical mirror on the vertical plane can condense or diverge the vertical light on the vertical plane to the second curved mirror, and reflect the horizontal light on the horizontal plane to the second curved mirror.
  • the second curved mirror transmits both the light from the horizontal plane and the light from the vertical plane to the windshield. It can also be understood that the cylindrical mirror on the vertical plane and the second curved mirror jointly realize the separation of the vertical image plane and the horizontal image plane, and the vertical image plane is pulled away to a position where ghost images can be eliminated.
  • the equivalent optical path of FIG. 11a may be the equivalent optical path of the horizontal plane of FIG. 10b
  • the equivalent optical path of FIG. 11b is is the equivalent optical path of the vertical plane of Fig. 10b.
  • the HUD system may include a PGU and an optical imaging unit.
  • the optical imaging unit may include a third curved mirror and a fourth curved mirror. The third curved mirror and the fourth curved mirror jointly realize that the vertical image plane is pulled away to a position where ghost images can be eliminated.
  • the optical imaging assembly may further include a zoom lens; the zoom lens is an optical element that can control the focal length electrically, and can realize the imaging position control, lateral magnification and vertical magnification control of the entire HUD system .
  • the zoom lens can be used to change the position and/or the lateral magnification of the horizontal image plane by adjusting the lateral focal length.
  • the zoom lens can be used to change the position and/or the vertical magnification of the vertical image plane by adjusting the vertical focal length.
  • a zoom lens may be used to change the position and/or lateral magnification of the horizontal image plane by adjusting the lateral focal length, and to change the position and/or vertical magnification of the vertical image plane by adjusting the longitudinal focal length.
  • FIG. 12a a schematic structural diagram of a liquid lens provided by the present application.
  • the liquid lens can change the shape of the film material by changing the applied voltage signal or current signal, and at the same time, the liquid is injected into or out of the liquid lens, thereby changing the focal length of the liquid lens, so that the lateral magnification, longitudinal magnification, horizontal image plane can be realized. and control of the vertical image plane.
  • FIG. 12b it is a schematic structural diagram of another liquid lens provided by the present application.
  • the liquid lens can use the principle of electro-wetting to change the surface shape of the interface between the two immiscible liquids by changing the applied voltage signal or current signal, thereby changing the focal length of the liquid lens, thereby realizing lateral magnification. ratio, vertical magnification, horizontal image plane, and vertical image plane control.
  • the virtual image can be zoomed in or out. It should be noted that if the horizontal focal length of the zoom lens is the same as the vertical focal length, the horizontal image plane and the vertical image plane can be simultaneously zoomed in or out; if the horizontal and vertical focal lengths of the zoom lens are different, the horizontal image plane and the vertical The distance at which the image plane changes is also different.
  • the information such as the instrument of the car can be projected to a position closer to the car, and the navigation information can be projected to a position farther away from the car. That is to say, the HUD system can project multiple virtual images of different depths in front of the car, which is equivalent to having multiple screens at different distances in front of the car.
  • the HUD system may include first and second PGUs, a flat mirror, a cylindrical mirror, and a second curved mirror.
  • the HUD system may be called a dual-depth virtual image display HUD system.
  • the first PGU is used to generate image 1;
  • the plane mirror is used to reflect the light carrying the information of image 1 to the second curved mirror;
  • Enlarging and longitudinally enlarging, and propagating the light of the enlarged image to the windshield, and the reverse extension line of the light reflected by the windshield forms a virtual image 1 at the second preset position (ie, position B), wherein the lateral magnification ratio is the same as the longitudinal one.
  • the magnification is different.
  • the image 1 generated by the first PGU can be projected to the position B in front of the car through the flat mirror and the second curved mirror, that is, the virtual image 1 is formed at the position B.
  • the second PGU is used to generate the image 2;
  • the cylindrical mirror is used to change the propagation path of the light carrying the image information 2, and reflect the changed light to the second curved mirror;
  • the second curved mirror is also used to
  • the light carrying the information of the image 2 is enlarged horizontally and vertically, and the light of the enlarged image is propagated to the windshield, and the reverse extension line of the light reflected by the windshield is focused on the vertical plane on the vertical plane.
  • the image plane is focused on the horizontal image plane (ie, the position A) on the horizontal plane, and a virtual image 2 is formed at the position A. That is to say, the image 2 generated by the second PGU is projected to the position A in front of the car through the cylindrical mirror and the second curved mirror, that is, the virtual image 2 is formed at the position A.
  • the second preset position is determined according to a preset angular resolution and a center position of an eye box, where the eye box is an area where the driver's binocular is located.
  • the second preset position may be a position where ordinary human eyes cannot see ghost images. It can also be understood that when the virtual image is located at the second preset position, the human eye cannot see that the virtual image has a ghost image. Therefore, it is not necessary to eliminate the ghost image from the virtual image at the second preset position.
  • the second preset position may be a position where the virtual image ghost can be eliminated. It can also be understood that when the virtual image is at the second preset position, the driver's binoculars are usually unable to distinguish the main image and the auxiliary image, thereby eliminating the ghost of the virtual image. Specifically, it can be determined by referring to the aforementioned formula 4 to formula 6.
  • the present application can also provide a vehicle, which can include the above-mentioned HUD system and a windshield.
  • the windshield is used to reflect the light from the HUD system to an eye box, which is an area where the driver's binocular is located.
  • the vehicle may also include other devices, such as a steering wheel, a processor, a memory, a wireless communication device, and sensors.
  • a simplified schematic diagram of a partial structure of a vehicle provided by the present application.
  • the vehicle may include a HUD system and a windshield.
  • the HUD system can be located under the steering wheel.
  • FIG. 14 is only an example.
  • the vehicle to which this application applies may have more or fewer components than the vehicle shown in FIG. 14 , may combine two or more components, or may have a different configuration of components.
  • processor in the embodiments of the present application may be a central processing unit (central processing unit, CPU), and may also be other general-purpose processors, digital signal processors (digital signal processors, DSP), application-specific integrated circuits (application specific integrated circuit, ASIC), field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof.
  • CPU central processing unit
  • DSP digital signal processors
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • a general-purpose processor may be a microprocessor or any conventional processor.
  • the windshield includes a wedge-shaped windshield (see 15) or a flat windshield. It should be noted that the windshield in the foregoing embodiment is a plane windshield.
  • the decoupling of eliminating ghost and virtual image distance can be achieved. That is, the position of the horizontal image plane can be changed, so that the size of the virtual image distance can be changed.
  • the windshield is generally a wedge-shaped windshield, and the virtual image distance is generally 2.5m.
  • the horizontal image plane can be pulled away, that is, the virtual image distance can be increased, for example, the virtual image distance can be increased to a distance of 5m or more (eg, 15m).
  • the ghost can be eliminated by selecting the appropriate wedge angle ⁇ . Combining the above-mentioned Figure 15, the following geometric relationship can be obtained.
  • ⁇ represents the incident angle of the light entering the front outer surface of the windshield ;
  • ⁇ 2 represents the refraction angle of the ray of the secondary image at the front outer surface.
  • At least one (a) of a, b or c can mean: a, b, c, "a and b", “a and c", “b and c", or "a and b and c” ", where a, b, c can be single or multiple.
  • the character “/” generally indicates that the contextual object is an "or” relationship.
  • the character “/” indicates that the related objects before and after are a “division” relationship.
  • the word “exemplary” is used to mean serving as an example, illustration, or illustration. Any embodiment or design described in this application as "exemplary” should not be construed as preferred or advantageous over other embodiments or designs. Alternatively, it can be understood that the use of the word example is intended to present concepts in a specific manner, and not to limit the application.

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Abstract

一种抬头显示HUD系统及车辆，HUD包括M个包括矩形像素的图像产生单元PGU（401）和光学成像单元（402），PGU（401）用于产生图像，并将图像的光线传播至光学成像单元（402）；光学成像单元（402）用于对图像进行放大，并将放大后的图像的光线传播至风挡；经风挡反射后的光线的反向延长线在第一预设位置形成虚像，横向放大率与纵向放大率不同，虚像的横向像素密度与纵向像素密度相同。采用矩形像素的PGU（401）产生的图像有畸变，横向放大率与纵向放大率不同可产生反向的畸变、且有助于充分利用PGU（401）的显示芯片，从而实现虚像的横向像素密度与纵向像素密度相同。

Description

一种HUD系统及车辆
本申请要求于2020年12月31日提交中国国家知识产权局、申请号为202011634553.4、申请名称为“一种HUD系统及车辆”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及HUD系统技术领域，尤其涉及一种HUD系统及车辆。
背景技术
随着汽车技术的不断发展，对汽车使用的便捷性和安全性的提出了越来越高的要求。例如，抬头显示(head up display，HUD)(或称为平视显示系统)已被广泛应用于汽车。抬头显示是把仪表信息(如速度)、导航信息等投射至驾驶员视野前方的一种装置，驾驶员可以在视野前方看到仪表信息和导航信息，不需要低头观察方向盘下方的仪表盘或者中控显示屏，从而可提高紧急情况下的制动反应时间，提升驾驶的安全性。
HUD系统的成像原理可参见图1a：仪表信息和导航信息等通过HUD系统中的图像生成单元(picture generation unit，PGU)产生图像，然后通过曲面反射镜和风挡在汽车前方形成虚像。通常，PGU显示都是像素化的，而且横向和纵向包括的像素数量是不相同，例如16:9。PGU包括的像素数量越多，显示的图像的分辨率越高。但是受限于空间布局或者驾驶员的视线，虚像一般大于PGU的实际显示区域，因此，通常需要放大PGU产生的图像。现有技术中通常有如下两种放大方式。方式1，可将PGU产生的图像按横向和纵向等比例放大(即横向放大率等于纵向放大率)，如图1b，若将PGU的全部像素形成的显示芯片(即实际显示区域)按横向和纵向等比例放大后，由于虚像的大小及位置是预先设计的，人眼可能只能看到其中的部分虚像(称为有效显示区域)，有效显示区域之外的虚像均不能被看到。因此，会造成PGU的有效显示区域小于显示芯片，从而造成PGU物理显示资源的浪费。因此提出了方式2，横向放大率大于纵向放大率，如图1c所示，这样PGU的有效显示区域即为显示芯片，但是由于横向放大率与纵向放大率不同，会造成图像往放大率大的方向拉伸，即虚像产生了畸变，从而需要对虚像的畸变进行校正。
综上所述，HUD系统如何既可以充分利用PGU的显示芯片，又不需要校正虚像的畸变，是当前亟需解决的技术问题。
发明内容
本申请提供一种HUD系统及车辆，用于解决现有技术中无法既可以实现充分利用PGU的显示芯片，又不需要校正虚像畸变的问题。
第一方面，本申请提供一种HUD系统，该HUD系统可包括M个PGU和光学成像单元，所述PGU包括矩形像素，所述M为正整数。所述PGU用于产生图像，并将所述图像的光线传播至所述光学成像单元。所述光学成像单元用于对所述图像分别进行横向放大和纵向放大，并将放大后的图像的光线传播至风挡；所述放大后的图像的光线经所述风挡反射后的反向延长线在第一预设位置形成虚。横向放大率与纵向放大率不同，所述虚像的横 向像素密度与纵向像素密度相同。
基于该方案，通过将横向放大率与纵向放大率设置的不同，从而有助于充分利用PGU的显示芯片。采用矩形像素的PGU产生的图像会引入光学畸变，横向放大率与纵向放大率不同可产生反向的光学畸变，从而可以实现虚像的横向像素密度与纵向像素密度相同，因此，形成的虚像不会产生畸变，从而也不需要对虚像进行校正。
在一种可能的实现方式中，所述矩形像素的横向宽度和纵向宽度的比值等于所述纵向放大率与所述横向放大率的比值。
进一步，可选地，所述横向放大率是根据所述PGU的横向宽度、所述HUD系统的虚像距和所述HUD系统的横向视场角确定的；所述纵向放大率是根据所述PGU的纵向宽度、所述HUD系统的虚像距和所述HUD系统的纵向视场角确定的。
示例性地，所述横向放大率＝2×HUD系统的虚像距×tan(横向视场角/2)/PGU的横向宽度；所述纵向放大率＝2×HUD系统的虚像距×tan(纵向视场角/2)/PGU的纵向宽度。
在一种可能的实现方式中，所述光学成像单元用于对所述图像分别进行横向放大和纵向放大，在水平面和垂直面分别改变所述图像的光线的传播路径，并将放大且改变路径后的光线传播至所述风挡；其中，所述放大且改变路径后的光线经所述风挡反射后的反向延长线在所述垂直面聚焦于垂直像面，在所述水平面聚焦于水平像面；所述垂直像面与所述水平像面处于不同的位置，所述垂直像面与眼盒的中心之间距离是根据预设角分辨率确定的，所述眼盒为驾驶员的双目所处区域。进一步，可选地，水平像面与眼盒中心之间的距离为所述HUD的虚像距。
通过该光学成像单元可以将垂直像面和水平像面分离，通过调整水平像面的位置可以灵活调节HUD的虚像距。又由于人眼感受到的虚像的重影是在垂直像面，因此，实现了调节虚像距与消除重影解耦。
在一种可能的实现方式中，该光学成像单元可用于将垂直像面拉远至可以消除虚像重影的位置，即第一预设位置。也可以理解为，当垂直虚像面处于第一预设位置时，通常驾驶员的双目是无法分辨出主像和副像，从而实现了消除虚像的重影。
在一种可能的实现方式中，所述光学成像单元可以包括第一曲面反射镜，所述第一曲面反射镜的横向焦距与纵向焦距不同。
或者，光学成像单元可以包括第二曲面镜反射和柱面镜，所述柱面镜位于水平面或垂直面，所述水平像面位于所述水平面，所述垂直像面位于所述垂直面。
或者，光学成像单元可以包括第三曲面反射和第四曲面反射镜，所述第三曲面反射和所述第四曲面反射镜中至少一个曲面反射镜的横向焦距与纵向焦距不同。
在一种可能的实现方式中，所述光学成像组件还包括变焦透镜。所述变焦透镜可用于通过调节横向焦距，改变所述水平像面的位置和/或横向放大率；或者，变焦透镜可用于通过调节纵向焦距，改变所述垂直像面的位置和/或纵向放大率。或者，所述变焦透镜可用于通过调节横向焦距，改变所述水平像面的位置和/或横向放大率，且变焦透镜可用于通过调节纵向焦距，改变所述垂直像面的位置和/或纵向放大率。
通过变焦透镜可以实现整个HUD系统的成像位置控制、横向放大率和/或纵向放大率的控制。
在一种可能的实现方式中，所述M个PGU包括第一PGU和第二PGU，所述光学成像单元包括平面反射镜、第二曲面反射镜和柱面镜；所述平面反射镜用于将来自所述第一 PGU的图像的光线反射至所述第二曲面反射镜；所述柱面镜于改变来自所述第二PGU的图像的光线的传播路径，并将传播路径改变后的光线反射至所述第二曲面反射镜；所述第二曲面反射镜用于将来自所述柱面镜的光线形成的图像进行横向放大和纵向放大，并将放大后的图像的光线传播至所述风挡，经所述风挡反射后的光线的反向延长线在垂直面上聚焦于所述垂直像面，在水平面上聚焦于所述水平像面；并将来自所述平面反射镜的光线形成的图像进行横向放大和纵向放大，并将放大后的图像的光线传播至所述风挡，经所述风挡反射后的光线的反向延长线在第二预设位置形成虚像。
当HUD包括多个PGU时，可以形成多个不同深度的虚像，即一个PGU对应一个位置的虚像。
在一种可能的实现方式中，所述第二预设位置是根据预设角分辨率确定、眼盒的中心位置、入射光的入射角、所述风挡的厚度以及所述风挡的折射率确定的。
在一种可能的实现方式中，第二预设位置可为可以消除虚像重影的位置。也可以理解为，当虚像处于第二预设位置时，通常驾驶员的双目是无法分辨出主像和副像，从而实现了消除虚像的重影。
第二方面，本申请提供一种车辆，该车辆可包括上述第一方面或第一方面中的任意一种HUD系统以及风挡；所述风挡用于将来自所述HUD系统的光线反射至眼盒，所述眼盒为驾驶员的双目所处的区域。
在一种可能的实现方式，所述风挡包括楔型风挡或平面型风挡。
当风挡为楔形风挡时，可以通过选取的合适的楔角δ来消除重影，且可以将水平像面和垂直像面分离，可实现调节HUD的虚像距与消除重影解耦，从而可以灵活调整HUD的虚像距。
上述第二方面可以达到的技术效果可以参照上述第一方面中有益效果的描述，此处不再重复赘述。
附图说明
图1a为现有技术中的一种HUD系统的成像原理示意图；
图1b为现有技术中的有一种PGU的全部像素形成的显示芯片按横向和纵向等比例放大后的图像示意图；
图1c为现有技术中的有一种PGU的全部像素形成的显示芯片按横向放大率大于纵向放大率放大后的图像示意图；
图2a为本申请提供的一种在相同感光面积下像素物理尺寸与分辨率的关系示意图；
图2b为本申请提供的另一种在相同感光面积下像素物理尺寸与分辨率的关系示意图；
图2c为本申请提供的一种视场角及虚像距的示意图；
图2d为本申请提供的一种平凸柱面镜的结构示意图；
图2e为本申请提供的一种平凹柱面镜的结构示意图；
图3a为本申请提供的一种可能的应用场景示意图；
图3b为本申请提供的一种W-HUD系统的结构示意图；
图3c为本申请提供的一种AR-HUD系统的结构示意图；
图4为本申请提供的一种HUD系统的结构示意图；
图5a为本申请提供的一种PGU包括10×4个矩形像素的结构示意图；
图5b为本申请提供的一种虚像的横向像素密度与纵向像素密度相等的虚像示意图；
图5c为本申请提供的一种HUD系统的成像光路示意图；
图6a为本申请提供的一种LCoS的结构示意图；
图6b为本申请提供的一种PGU的结构示意图；
图6c为本申请提供的一种背光系统的结构示意图；
图6d为本申请提供的一种扩展量匹配的光线传播路径示意图；
图7a为本申请提供的一种产生重影的原理图示意图；
图7b为本申请提供的一种产生重影的效果图示意图；
图7c为本申请提供的一种像夹角与虚像距的关系示意图；
图8为本申请提供的一种垂直面和水平面的示意图；
图9a为本申请提供的一种成像的光线在双眼视网膜不同x位置聚焦的示意图；
图9b为本申请提供的另一种成像的光线在双眼视网膜同一个y位置聚焦的示意图；
图10a为本申请提供的一种HUD系统的架构示意图；
图10b为本申请提供的另一种HUD系统的架构示意图；
图10c为本申请提供的又一种HUD系统的架构示意图；
图11a为本申请提供的一种简化的垂直面的光路示意图；
图11b为本申请提供的一种简化的水平面的光路示意图；
图12a为本申请提供的一种液体透镜的结构示意图；
图12b为本申请提供的另一种液体透镜的结构示意图；
图13为本申请提供的又一种HUD系统架构示意图；
图14为本申请提供的一种车辆部分结构的简化示意图；
图15为本申请提供的一种楔形风挡的结构示意图。
具体实施方式
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
以下，对本申请中的部分用语进行解释说明。需要说明的是，这些解释是为了便于本领域技术人员理解，并不是对本申请所要求的保护范围构成限定。
1)像素
像素指构成成像区域的最小单元。其中，像素的横向宽度和纵向宽度是指像素的物理尺寸(可参见下述图2a和图2b)。
2)像素密度(pixels per inch，PPI)
像素密度表示每英寸包括的像素数量。PPI数值越高，表示能够以越高的密度显示图像。
3)分辨率
分辨率指可用于成像的最大像素的数量。通常以横向像素的数量和纵向像素的数量的乘积来衡量，即分辨率＝横向像素的数量×纵向像素的数量。
需要说明的是，在相同感光面积下，分辨率与像素的物理尺寸是此消彼长的。参考图2a和图2b，在相同感光面积下像素物理尺寸与分辨率的关系。图2a中像素的横向宽度和纵向宽度均为a，分辨率为4×4；图2b的像素的横向宽度和纵向宽度均为a/2，分辨率为 8×8。由图2a和图2b可以确定，即像素尺寸越小，分辨率越高；像素尺寸越大，分辨率越低。
4)虚像距(virtual image distance，VID)
虚像距是指眼盒中心与虚像的中心之间的距离，可参见下述图2c。在本申请中，虚像距可用V表示。
5)视场角(field of view，FOV)
视场角包括横向视场角(H_FOV)和纵向视场角(V_FOV)。横向视场角是指HUD系统在横向的最大可见范围，纵向视场角是HUD系统在纵向的最大可见范围，可参见图2c。其中，横向视场角也可称为水平视场角，纵向视场角也可称为垂直视场角。
示例性地，横向视场角可通过如下公式1确定，纵向视场角可通过如下公式2确定。
Figure PCTCN2021139994-appb-000001
Figure PCTCN2021139994-appb-000002
6)柱面镜
柱面镜在一个维度上有曲率，可以实现一维整形。也可以理解为，在一个维度上对光线进行发散或会聚，在另一个维度上对光线进行反射。例如平凸柱面镜(参阅图2d)、平凹柱面镜(参阅图2e)。
7)角分辨率
角分辨率是指成像系统的分辨能力，即可以有差别地区分开相邻物体最小间距的能力。一般用成像系统对两个最小可辨物体之间所张角度的大小表示。人眼的角分辨率是指人眼的分辨能力。
8)像散
由于发光物不在光学系统的光轴上，它所发出的光线与光轴有一倾斜角。该光线经透镜折射后，其子垂直光线与水平光线的会聚点不在一个点上。即光线不能聚焦于一点，成像不清晰，故产生像散。
基于上述内容，如图3a所示，为本申请提供的一种可能的应用场景。该应用场景以HUD系统应用于汽车为例。HUD系统用于将仪表信息和导航信息等形成放大虚像，通过汽车风挡投射在驾驶员的视野范围内，从而向驾驶员呈现道路远方一定距离(例如2到20m)外的虚像。为了看到清晰的虚像，驾驶员的眼睛通常需处于眼盒(eyebox)。应理解，如果人眼与眼盒的中心对齐，则可获得完整且清晰的虚像。当眼睛向左右或上下移动时，在每个方向上的某个点处，图像将变差，直到无法接受，即超出眼盒范围。在超出眼盒的区域可能会呈现图像扭曲、显色错误，甚至不显示等问题。由于不同驾驶员的身高，一般眼盒尺寸大小是130mm×50mm，即眼盒在纵向上有约±50mm的移动范围，在横向上有约±130mm的移动范围。
应理解，如上场景只是举例，本申请提供的HUD系统还可以应用在其它场景，例如可应用于飞行器(如战斗机)等，战斗机上驾驶员可以基于HUD系统进行物体追踪和瞄准，从而有助于提高作战成功率和灵活性。
本申请中，HUD系统可以是挡风玻璃(Windshield，W)-HUD系统或者增强现实 (Augmented Reality，AR)-HUD系统。请参阅图3b，为本申请示例性地示出了W-HUD系统的结构示意图。W-HUD系统包括PGU和曲面反射镜。PGU产生的图像投射至挡风玻璃后经挡风玻璃反射至驾驶员双目成像，在驾驶员的双目形成的图像的反向延长线在汽车的前方形成虚像。由于W-HUD系统与车身集成，安全性较高，也可称为前装HUD系统。W-HUD系统的虚像距在2～3m之间。
请参阅图3c，为本申请示例性地的示出了一种AR-HUD系统的结构示意图。该AR-HUD系统可以将导航等虚拟信息叠加在现实路面，从而可以显示较丰富的内容；而且AR-HUD系统的虚像距一般大于5m，可以更好的实现虚实结合。应理解，AR-HUD系统显示的虚像需要与实景结合，其要求汽车具有精确的定位与探测功能，通常AR-HUD系统需要与汽车的高级驾驶辅助系统(advanced driving assistant system，ADAS)系统配合。
在上述可能的应用场景中，通常，PGU的横向包括的像素数量和纵向包括的像素数量是不相同的，例如横向的像素数量与纵向的像素数量的比为16:9。HUD系统的视场角中的横向视场角与纵向视场角也是不相同的，例如横向视场角与纵向视场角的比为3:1。
基于HUD系统的横向视场角与纵向视场角的比值不同于PGU横向像素与纵向像素的比值。如背景技术所介绍，现有技术中HUD系统形成的虚像要么无法充分利用PGU的显示芯片，造成PGU物理资源的浪费；要么会造成图像畸变，造成因矫正畸变引起HUD系统显示图像的效率低且驱动电路复杂等问题。
鉴于上述问题，本申请提出一种HUD系统。该HUD系统既可以实现充分利用PGU的显示芯片，且在放大PGU产生的图像过程不会造成虚像出现畸变。
下面结合附图4至附图13，对本申请提出的HUD系统进行具体阐述。
基于上述内容，如图4所示，为本申请提供的一种HUD系统的结构示意图。该HUD系统可包括M个图像产生单元PGU401和光学成像单元402。PGU401包括矩形像素，所述M为正整数；PGU401用于产生图像，并将所述图像传播至所述光学成像单元402；所述光学成像单元402用于对所述图像分别进行横向放大和纵向放大，并将放大后的图像的光线传播至风挡；所述放大后的图像的光线经风挡反射后的反向延长线在第一预设位置形成虚像。其中，虚像的横向像素密度与纵向像素密度相同，横向放大率与纵向放大率不同。其中，图像的光线也可以理解为携带图像信息的光线。
在一种可能的实现方式中，当PGU的横向宽度小于纵向宽度时，横向放大率大于纵向放大率，放大后的图像相当于将原图像往横向拉伸。当PGU的横向大于纵向宽度时，横向放大率小于纵向放大率，放大后的图像相当于将图像往纵向拉伸。
基于上述HUD系统，通过将横向放大率与纵向放大率设置的不同，从而有助于充分利用PGU的显示芯片。采用矩形像素的PGU产生的图像会引入光学畸变，通过横向放大率与纵向放大率不同可产生反向的光学畸变，从而可以实现虚像的横向像素密度与纵向像素密度相同，因此，形成虚像不会产生畸变，从而也不需要对虚像进行校正。
下面对图4所示的各个功能单元和结构分别进行介绍说明，以给出示例性的具体实现方案。为方便说明，下文中的PGU和光学成像单元均未加标识。
一、PGU
在一种可能的实现方式中，PGU可包括k×n个矩形像素。如图5a所示，为本申请提供的一种PGU包括10×4个矩形像素的示意图。该PGU产生的图像的分辨率是非均匀的。 该示例中，PGU的显示芯片的横向宽度为h，纵向宽度为l。也可以理解为，若充分利用PGU的显示芯片，则有效显示区域的横向宽度为h，纵向宽度为l。
若需要显示的虚像的横向宽度为H，纵向宽度为L，为了保证充分利用PGU的显示芯片，则横向放大率M1＝H/h，纵向放大率M2＝L/l。应理解，虚像的横向宽度与纵向宽度是预先设计的。
由于放大图像不改变像素的个数，因此，PGU包括的像素数量与虚像的像素数量相同。PGU的横向包括k个矩形像素，纵向包括n个矩形像素，则虚像的横向也包括k个像素，纵向也包括n个像素。
为了保证虚像的分辨率是均匀的，即虚像的横向像素密度与纵向像素密度相等(请参阅图5b)。虚像的横向像素密度为k/H，则纵向像素密度也为k/H，因此，虚像的纵向包括的像素的数量n＝L/H×k。
基于上述内容，可以确定PGU包括的每个矩形像素的横向宽度与纵向宽度的比值r。具体可参见下述公式1。
r＝(h/k)/(l/n)＝(h/l)×(L/H)＝(h/H)×(L/l)＝M2/M1  公式1
由上述公式1可知，PGU包括的矩形像素的横向宽度与纵向宽度的比值r等于纵向放大率与横向放大率的比值。
进一步，可选地，HUD系统的成像光路可简化为图5c所示的光路。结合图5c和上述图2c，可以确定虚像的横向宽度H＝2×V×tan(θ 1/2)，虚像的纵向宽度L＝2×V×tan(θ 2/2)；相应地，可确定出图像的横向放大率M1＝2×V×tan(θ 1/2)/h，图像的纵向放大率M2＝2×V×tan(θ 2/2)/l；其中，θ 1表示横向视场角，θ 2表示纵向视场角，V表示虚像距。应理解，横向视场角θ1、纵向视场角θ2、以及虚像距V是预先设计的。
结合上述公式1，可确定出每个矩形像素的横向宽度与纵向宽度的比值r如下述公式2。
r＝M2/M1＝[2×V×tan(θ 2/2)/l]/[2×V×tan(θ 1/2)/h]＝[tan(θ 2/2)/tan(θ 1/2)]×(h/l)  公式2
进一步，可选地，当θ较小时，tanθ≈θ，上述公式2可简化为下述公式3。
r＝(θ2/θ1)×(h/l)  公式3
由上述公式3可知，PGU包括的矩形像素的横向宽度与纵向宽度的比值r与HUD系统的纵向视场角、横向视场角、PGU的横向宽度以及PGU的纵向宽度有关。
示例性地，θ 1＝13度，θ 2＝5度，PGU的横向宽度与纵向宽度的比值h/l＝16/9，结合上述公式3，可确定每个矩形像素的横向宽度与纵向宽度的比值r＝(θ 2/θ 1)×(h/l)＝(5/13)×(16/9)＝0.68。
通过上述内容可以进一步确定出，通过横向放大率与纵向放大率不同可实现PGU的显示芯片能够被全部有效利用。为了保证虚像的横向像素密度与纵向像素密度相同，可通过设计PGU包括的像素为矩形像素、且像素的纵向宽度大于横向宽度，具体的横向宽度与纵向宽度的比值r等于纵向放大率与横向放大率的比值。
也可以理解为，基于上述内容，可选择PGU包括的矩形像素的横向宽度和纵向宽度；或者也可以基于PGU包括的矩形像素的横向宽度和纵向宽度，确定横向放大率和纵向放大率。
在一种可能的实现方式中，PGU可以为液晶显示(liquid crystal display，LCD)、数字微镜显示(digital micromirror display，DMD)、硅基液晶(liquid crystal on silicon，LCoS)或激光光线扫描(laser beam scanning，LBS)。下面分别进行详细介绍。
LCD技术可通过电压控制液晶状态，从而改变背光的偏振态，配合偏振器实现光的强度调制，使用集成电路技术就可以像素化的调制光的强度，最终形成图像。通常，W-HUD系统中的PGU为LCD。其中，像素化的调制光强度可以理解为像素可以控制对应区域的光强度的大小。
LCoS也是液晶技术，与LCD差异的地方在于它是反射式的，入射光经过液晶后打到硅片上反射，参阅图6a，为本申请提供的一种LCoS的结构示意图。可以通过改变外加电压信号或电流信号来改变液晶分子长轴的方向，以改变LCoS折射率，从而可改变光经过LCoS的相位。相当于利用相位的延迟来旋转光的偏振态，并配合偏振分光棱镜(polarizing beam splitter，PBS)实现光强度的调制。像素化的集成电路(即控制电路)可在基于金属氧化物半导体元件(complementary metal-oxide semiconductor，CMOS)工艺的硅基底上制备，可以实现相比于LCD更小的显示芯片。DMD与LCoS类似，基于CMOS工艺的显示芯片，不同之处在于DMD是像素化的微镜，如数字微镜，每个微镜的状态有0和1，通过控制数字微镜的状态来实现光强度的调制。通常，AR-HUD系统因为视场角更大，需要更高亮度的PGU，AR-HUD系统中的PGU可采用DMD或LCoS。DMD和LCoS具有效率高，散热好，亮度容易提升的优势。
需要说明的是，LCoS和DMD芯片显示的图像尺寸一般都小于1英寸，直接对产生图像进行放大，横向放大率和纵向放大率均比较大，光路实现比较困难，通常需要通过镜头在一个扩散屏上先形成一个较大的实像，之后再对这个实像进行放大形成虚像，请参阅图6b。
LBS的成像原理相对较简单，它是激光入射到MEMS反射镜上，控制MEMS的偏转可以在空间中扫描激光，从而在扩散屏上形成图像。
通常，要产生亮度均匀的图像，匀光是一个较为关键的过程。通常光源发射的光线形成的光斑是不均匀的，而且光斑形状与显示芯片不匹配。因此，对于非自发光的PGU都有背光系统。即光源发射的光线经过背光系统的匀光之后入射到显示芯片上，经过空间调制之后产生图像。
如图6c所示，为本申请提供的一种背光系统结构的示意图。该背光系统可包括准直透镜、复眼透镜1、复眼透镜2和中继透镜。该示例中复眼透镜1和复眼透镜2均以包括3个子眼为例的。需要说明的是，复眼透镜包括的子眼越多，匀光效果越好。复眼透镜1和复眼透镜2包括的子眼数量相同且一一对应。光源发出的光线经过准直透镜准直，然后经过复眼透镜1和复眼透镜2在无穷远处匀光，再通过中继透镜把均匀的光斑在显示芯片上成像。应理解，图6c仅是示例性的示出了一种背光系统的结构，实际的背光系统还可包括合色或者分色的光学元件，而且于不同的PGU还会有其他组件，比如LCoS一般还会包括偏振转换单元等，本申请对此不做限定。
需要说明的是，复眼透镜也可以用光棒替换。如果是复眼透镜，每个子眼的横向宽度和纵向宽度的比值等于PGU显示芯片的横向宽度和纵向宽度的比值；如果是光棒，光棒的横截面的横向宽度和纵向宽度的比值等于显示芯片的横向宽度和纵向宽度比值。
对于非成像光学系统，光学扩展量是非常重要的概念，在设计光学系统的时候要考虑扩展量守恒以减少损耗。光学扩展量是面积与孔径角的乘积，如图6d所示，光从入射孔径D in入射，从出射孔径D out出射，由于出射孔径D out较小，如果这个过程扩展量守恒， 所以出射的角度将变大。设计PGU的时候，为了提高光的利用率，需要考虑各个光学元件的扩展量匹配，沿光线传播的方向，后面的光学元件其扩展量不能小于前面的光学元件，否则将带来损耗。因此，选取PGU时，PGU的横向宽度和纵向宽度的比值不能太大。结合上述图6c，子眼的横向宽度和纵向宽度的比值等于PGU的横向宽度和纵向宽度的比值，如果子眼的横向宽度和纵向宽度的比值太大，很难做到与光源的扩展量匹配。例如，LED光源的发光面积的横向宽度和纵向宽度比一般都小于2:1，而且发散角大，准直光斑大，子眼的横向宽度和纵向宽度比大于2:1将很难匹配。结合上述6c所示，如果子眼的某一边太小，大角度入射的光线将会入射到非对应的子眼上，这些光线(即二级匀光束)将不能被后面的光学元件利用。因此，设计PGU时，PGU的横向宽度和纵向宽度比值等于1是较容易做到扩展量匹配的，从而光的利用率较高。因此，通常设计PGU的横向宽度与纵向宽度的比值接近1，例如16:9；而不直接设计为与虚像的横向视场角和纵向视场角比(3:1)相同。
需要说明的是，PGU也可以是除上述示例性示出的结构，例如还可以是有机发光二极管(organic light emitting diode，OLED)，或者微型发光二极管(micro light emitting diode，micro-LED)等自发光的显示屏，本申请对此不做限定。
为了防止风挡被撞击之后整块破碎，通常风挡包括两层玻璃及夹在两层玻璃中间的一层聚乙烯醇缩丁醛(polyvinyl butyral，PVB)材料，PVB材料的折射率与玻璃的折射率较接近，为了方案的说明，可将风挡简化为有一定厚度(一般为4～5mm)的平面玻璃。由于风挡具有一定厚度、因此会使得形成的虚像产生重影。如图7a所示，为本申请提供的一种产生重影的原理图示意图。光在风挡的前后表面都会发生反射，根据镜面成像原理，物体在风挡的前外表面的反射形成主像，在风挡的后内表面反射形成副像，所以驾驶员会看到两个像，这两个像有部分重叠，即为重影。应理解，主像与副像之间的距离与风挡的厚度有关，对于厚度固定的风挡，主像与副像之间的间隔是固定的。另外，主像和副像均虚像。
结合上述图7a，主像和副像分别与驾驶员的眼睛组成的夹角称为像夹角γ，若射入风挡的前外表面的光线的入射角为α，主像至驾驶员的眼睛的光学距离(即虚像距)为(a+b)、风挡的厚度为t，风挡的折射率为n，根据镜面成像原理可以确定像夹角γ。结合图7a，可得到如下几何关系：
γ＝α-β
Figure PCTCN2021139994-appb-000003
Figure PCTCN2021139994-appb-000004
AB+CD+2t·tan(β 1)＝(a+b)·sin·(α)
其中，β表示副像的光线在前外表面的入射角，β 1表示副像的光线在前外表面的光线的折射角。
化简上述几何关系可得到下述公式4至公式6。
γ＝α-β   公式4
2t·tan(β 1)＝(a+b)·[sin(α)-cos(α)·tan(β)]   公式5
sin(β)＝n·sin(β 1)   公式6
示例性地，设α＝60°，a+b＝2500mm，t＝4.8mm，n＝1.5，则根据上述公式4至公式6可以确定出像夹角γ＝0.078°。通常人眼的角分辨率为1角分，约0.017°。当像夹角γ大于人眼的角分辨率时，人眼会看到重影，可参见图7b人眼看到的有重影的效果图。当像夹角γ不大于人眼的角分辨率时，人眼就看不到重影。
由图7b可以看出，重影会影响图像显示的信息的清晰度和驾驶体验，因此，在HUD系统设计时需要考虑消除虚像的重影。进一步，可选地，基于上述公式4至公式6，入射角α取决于风挡与地面的角度、眼盒的中心位置与虚像的连线与地面所形成的角度，通常是固定值；风挡的厚度t和风挡的折射率n也是相对固定；因此，为了消除虚像的重影，设计HUD系统时，可以调整虚像距(a+b)以实现消除虚像的重影。
如图7c所示，为本申请提供的一种像夹角γ与虚像距(a+b)的关系示意图。由图7c可知，虚像距(a+b)越大，像夹角γ越小，当虚像距(a+b)不小于12米时，像夹角γ不大于普通人眼的角分辨率0.017°。也可以理解为，当虚像距足够大时，人眼分不出主像和副像，即可以消除虚像的重影。应理解，该消除重影的方式可应用虚像距不小于12米的HUD系统，例如AR-HUD系统。
在介绍消除重影的实现方式之前，首先定义两个平面，即垂直面和水平面。参见图8，与双目垂直的yoz平面为垂直面(或称为子午面)。也可以理解为，垂直面是与双目连线垂直且过双目中心的平面。位于垂直面内的光线称为垂直光线(或称为子午光线)，垂直光线聚焦的位置称为垂直像面(或称为子午像面)。与双目平行的xoz平面为水平面(或称为弧矢面)，弧矢面与子午面垂直。位于水平面内的光线称为水平光线(或称为弧矢光线)，水平光线聚焦的位置称为水平像面(或称为弧矢像面)。
结合上述图7a，在水平面内，风挡相对驾驶员的角度接近90度，即入射光线是垂直入射时，入射角α非常小，从图7a可以看出像夹角γ接近于零，因此，重影只考虑在垂直面内。也就是说，驾驶员观察到的主像和副像是在y方向错开的。也可以理解为，通过增大垂直像面与眼盒之间的距离即可减小像夹角γ。应理解，驾驶员的双目通常处于眼盒中心。
进一步，可选地，驾驶员感受物体的深度信息主要是靠双目视差实现的。眼睛相当于一个成像系统，物体的光线进入人眼球的视网膜上形成图像，图像信息被视网膜上的神经元接收并传入大脑，形成图像感受。同一个物体会在双目视网膜的不同位置形成图像，根据双目视网膜的这两个位置的差异的大小，大脑就可以“计算”出物体的距离。结合上述图8，驾驶员的双目是水平左右分布的，那么成像的光线将在双目视网膜不同x位置聚焦，如图9a所示，在垂直面上，双目处于同一位置，所以光线在双目视网膜同一个y位置聚焦，如图9b所示。也就是说，水平面(xoz平面)的水平光线聚焦于双目的视网膜不同位置，而垂直面(yoz平面)的垂直光线聚焦于双目的视网膜的相同位置。大脑判断虚像的位置是水平像面的位置，垂直像面的位置对人感受虚像的距离没有影响；而且，由图7a可以看出，重影是产生于垂直像面。
基于此，可通过将垂直像面与水平像面分开，即可将消除重影与虚像距进行解耦，将垂直像面拉远来从而实现消除虚像的重影。进一步，可通过上述光学成像单元来实现。如下，对光学成像单元进行详细介绍。
二、光学成像单元
在一种可能的实现方式中，所述光学成像单元用于对所述图像分别进行横向放大和纵向放大，并在水平面和垂直面分别改变所述图像的光线的传播路径，并将放大且改变路径后的光线传播至所述风挡；所述放大且改变路径后的光线经所述风挡反射后的反向延长线在所述垂直面聚焦于垂直像面，在所述水平面聚焦于水平像面。也就是说，该光学成像单元既可以将图像进行横向放大和纵向放大，还可以将垂直像面与水平像面分离(即水平像面与垂直像面不在同一位置，参阅图8，形成具有像散的图像。具有像散的图像是指在垂直面和水平面上均有该图像的光线。
结合上述图7c，当虚像距不小于12米时，像夹角不大于预设角分辨率。此时，大多数人是看不到虚像的重影。也就是说，当垂直像面与眼盒中心之间的距离不小于12m时，可以实现大多数人可以观察不到虚像的重影。
在一种可能的实现方式中，垂直像面的位置可根据眼盒的中心位置确定。进一步，可选地，垂直像面的位置可根据眼盒的中心位置和预设角分辨率确定的。示例性地，可结合上述公式4至公式6确定垂直像面的位置。
进一步，可选地，预设角分辨率可以是统计大量人眼的角分辨率得到的。例如，预设角分辨率可等于0.017°。
需要说明的是，水平像面与眼盒的中心之间的距离等于所述HUD系统的虚像距，虚像距可以大于垂直像面与眼盒中心之间的距离，或者虚像距也可以小于垂直像面与眼盒中心之间的距离。也就是说，HUD系统的虚像距与垂直像面可以是解耦的，从而可灵活调整HUD系统的虚像距。
在一种可能的实现方式中，该光学成像组件可包括一个第一曲面反射镜，为了实现形成具有像散的虚像，该第一自由曲面反射镜的横向焦距和纵向焦距不同。其中，改变横向焦距可用于调整水平面上的水平光线的传播路径，改变纵向焦距可用于调整垂直面上的垂直光线的传播路径。
在另一种可能的实现方式中，光学成像单元可包括一个第二曲面反射镜和柱面镜。其中，所述柱面镜位于水平面，或者也可以位于垂直面。水平面上的柱面镜是指有曲率的面在水平方向，即柱面镜在水平面上参与成像。水平面上的柱面镜只对水平光线有发散或会聚作用，对垂直光线只起镜面反射作用。也就是说，水平面上的柱面镜可使得只有水平面上的水平光线参与成像。垂直面上的柱面镜是指有曲率的面在垂直方向，即柱面镜在垂直面上参与成像。垂直面上的柱面镜只对垂直光线具有发散或会聚作用，对水平光线只起镜面反射。也就是说，垂直面上的柱面镜可使得只有垂直面上的垂直光线上参与成像。应理解，有曲率的面才可对光线有发散或会聚作用。其中，第二曲面反射镜的横向焦距与纵向焦距可以相等，也可以不相等，本申请对此不做限定。
在又一种可能的实现方式中，光学成像单元可包括第三曲面反射镜和第四曲面反射镜，其中，所述第三曲面反射和所述第四曲面反射镜中至少一个曲面反射镜的横向焦距与纵向焦距不同。
下面，基于光学成像单元可能的结构，示例性地示出了三种可以实现消除虚像重影的HUD系统的架构示意图。下文的介绍中以M＝1为例进行说明。
如图10a所示，为本申请提供的一种HUD系统的架构示意图。该HUD系统可包括 PGU和光学成像单元。PGU可参见前述相关描述，此处不再重复赘述。光学成像单元可包括在水平面上的柱面镜和第二曲面反射镜。水平面上的柱面镜可以将水平面上的水平光线传播(例如汇聚或发散)至第二曲面反射镜，将垂直面上的垂直光线反射至第二曲面反射镜。第二曲面反射镜将来自水平面的光线和垂直面的光线均传播至风挡，从而可实现将垂直像面和水平像面分离，并将垂直像面拉远至可以消除虚像重影的位置。
为了便于理解，可将图10a的光路抽象为图11a和图11b的光路，即将离轴的反射系统等效简化为共轴的透射系统，以便于进一步解释图10a的成像光路。为了便于方案的说明，以第二曲面反射镜为球面镜为例，以第二曲面反射镜的水平焦距与垂直焦距相同(均为f)为例，以柱面镜为平凹柱面镜为例。
针对图10a的垂直面，由于水平面上的柱面镜只在水平面参与成像，故可将图10a的垂直面的光路抽象为图11a的光路。根据成像公式和几何关系，可得到下述公式7至公式9。
Figure PCTCN2021139994-appb-000005
Figure PCTCN2021139994-appb-000006
Figure PCTCN2021139994-appb-000007
其中，u2表示PGU与第二曲面反射镜之间的光学距离，即第二曲面反射镜的物距，v2表示垂直像面与第二曲面反射镜之间的光学距离，即第二曲面反射镜在垂直面的像距，f表示第二曲面反射镜的焦距，g表示眼盒的中心至第二曲面反射镜的光学距离，θ2表示纵向视场角，L表示虚像的纵向宽度，l表示PGU的纵向宽度。应理解，光学距离是指光传播的路程。
针对图10a的水平面，由于水平面上的柱面镜在水平面参数与成像，可将平凹柱面镜简化为凹面镜，故可将图10a水平面的光路抽象为图11b的光路。根据成像公式和几何关系，可得到下述公式10至公式14。
Figure PCTCN2021139994-appb-000008
Figure PCTCN2021139994-appb-000009
Figure PCTCN2021139994-appb-000010
Figure PCTCN2021139994-appb-000011
Figure PCTCN2021139994-appb-000012
其中，u1表示凹面镜的物距，u0是凹面镜的像距，v1表示水平像面与第二曲面反射镜的之间的光学距离，即第二曲面反射镜在垂直面的像距，f表示第二曲面反射镜的焦距，g表示眼盒的中心至第二曲面反射镜的光学距离，θ1表示横向视场角，H表示虚像的横向宽度，h表示PGU的横向宽度。
基于上述图11a和图11b，示例性地，以虚像距V＝3m、横向视场角θ 1＝13°、纵向视场角θ 2＝5°、垂直像面与眼盒中心之间的距离为12m为例，设u2＝480mm、v2＝12m-g＝11m、 v1＝3m-g＝2m、d＝260mm。
根据上述公式4至公式14，可以计算得到PGU横向宽度h＝214mm，纵向宽度l＝46mm，PGU的横向宽度与纵向宽度的比值＝h/l＝214/46＝4.7，横向视场角与纵向视场角的比值＝13:5。也就是说，这个虚像距离为3m的无重影HUD系统，虚像是被纵向拉伸的，为了保证虚像的横向像素密度与纵向像素密度相等，PGU使用矩形像素。结合上述公式2，可以确定r＝[tan(θ 2/2)/tan(θ 1/2)]×(h/l)＝[tan(5/2)/tan(13/2)]×4.7＝1.8。应理解，当垂直像面与水平像面分开后，确定横向放大率与纵向放大率时涉及到的虚像距均是指水平像面与眼盒中心之间的距离。
如图10b所示，为本申请提供的又一种HUD系统示意图。该HUD系统可包括PGU和光学成像单元。PGU可参见前述相关描述，此处不再重复赘述。光学成像单元可包括在垂直面上的柱面镜和第二曲面反射镜。垂直面上的柱面镜可以将垂直面上的垂直光线汇聚或发散至第二曲面反射镜，将水平面上的水平光线反射至第二曲面反射镜。第二曲面反射镜将来自水平面的光线和垂直面的光线均传播至风挡。也可以理解为，垂直面上的柱面镜和第二曲面反射镜共同实现将垂直像面和水平像面分离，并将垂直像面拉远至可以消除虚像重影的位置。
图10b中的光学成像单元的等效光路可参见上述图11a和图图11b的相关描述，即图11a的等效光路可为该图10b的水平面的等效光路，图11b的等效光路即为该图10b的垂直面的等效光路。
如图10c所示，为本申请提供的又一种HUD系统示意图。该HUD系统可包括PGU和光学成像单元。PGU可参见前述相关描述，此处不再重复赘述。光学成像单元可包括第三曲面反射镜和第四曲面反射镜。第三曲面反射镜和第四曲面反射镜共同实现将垂直像面拉远至可以消除重影的位置。
通过上述图10a至图10c任一个HUD系统，既可以实现消除重影，还可以使得虚像的横向像素密度和纵向像素密度相同。
在一种可能的实现方式中，所述光学成像组件还可包括变焦透镜；变焦透镜是可以电动控制焦距的光学元件，可以实现整个HUD系统的成像位置控制、横向放大率和纵向放大率的控制。
进一步，可选地，所述变焦透镜可用于通过调节横向焦距，以改变所述水平像面的位置和/或横向放大率。或者，所述变焦透镜可用于通过调节纵向焦距，改变所述垂直像面的位置和/或纵向放大率。或者，变焦透镜可用于通过调节横向焦距改变所述水平像面的位置和/或横向放大率，且通过调节纵向焦距改变所述垂直像面的位置和/或纵向放大率。
如图12a所示，为本申请提供的一种液体透镜的结构示意图。该液体透镜可以通过改变施加的电压信号或电流信号来改变薄膜材料的形状，同时液体注入或者流出液体透镜，从而改变液体透镜的焦距，从而可实现对横向放大率、纵向放大率、水平像面以及垂直像面的控制。
如图12b所示，为本申请提供的另一种液体透镜的结构示意图。该液体透镜可以利用电浸润的原理，通过改变施加电压信号或电流信号来改变互不相融的两种液体之间的交界面的面型，从而改变液体透镜的焦距，从而可实现对横向放大率、纵向放大率、水平像面以及垂直像面的控制。
通过该变变焦透镜的焦距，可以实现将虚像拉远或拉近。需要说明的是，若变焦透镜的横向焦距与纵向焦距相同，则可以将水平像面和垂直像面同步拉远或拉近；若变焦透镜的横向焦距与纵向焦距不同，则水平像面与垂直像面改变的距离也不同。
在一种可能的应用场景中，可以将汽车的仪表等信息投射至离汽车较近的位置，将导航信息投射至离汽车较远的位置。也就是说，HUD系统可以在汽车的前方投射多个不同深度的虚像，相当于在汽车的前方有多个不同距离的屏幕。
下面，示例性地示出了一种可以实现形成的多个不同位置的虚像，且虚像无重影的HUD系统的架构示意图。该示例性中以M＝2为例进行说明。需要说明的是，M也可以大于2，本申请对此不做限定。
如图13所示，为本申请提供的又一种HUD系统架构示意图。该HUD系统可包括第一PGU和第二PGU、平面镜、柱面镜和第二曲面反射镜。该HUD系统可称为双深度虚像显示的HUD系统。其中，第一PGU用于产生图像1；平面镜用于将携带图像1的信息的光线反射至第二曲面反射镜；第二曲面反射镜用于将携带图像1的信息的光线形成的图像进行横向放大和纵向放大，并将放大后的图像的光线传播至风挡，经风挡反射后的光线的反向延长线在第二预设位置(即位置B)形成虚像1，其中，横向放大率与纵向放大率不同。也就是说，第一PGU产生的图像1可经平面镜和第二曲面反射镜投射至汽车前方的位置B，即在位置B形成虚像1。第二PGU用于产生图像2；柱面镜用于改变携带图像信息2的光线的传播路径，并将传播路径改变后的光线反射至第二曲面反射镜；第二曲面反射镜还用于将携带图像2的信息的光线进行横向放大和纵向放大，并将放大后的图像的光线传播至所述风挡，经所述风挡反射后的光线的反向延长线在垂直面上聚焦于所述垂直像面，在水平面上聚焦于所述水平像面(即位置A)，在位置A形成虚像2。也就是说，第二PGU产生的图像2经柱面镜和第二曲面反射镜投射至汽车前方的位置A，即在位置A形成虚像2。
在一种可能的实现方式中，所述第二预设位置是根据预设角分辨率确定和眼盒的中心位置确定的，所述眼盒为驾驶员的双目所处区域。该第二预设位置可以是普通人眼看不到重影的位置。也可以理解为，虚像位于该第二预设位置时，人眼是看不到虚像有重影的，因此，不需要对第二预设位置的虚像消除重影。
进一步，可选地，第二预设位置可为可以消除虚像重影的位置。也可以理解为，当虚像处于第二预设位置时，通常驾驶员的双目是无法分辨出主像和副像，从而实现了消除虚像的重影。具体可参见前述公式4至公式6确定。
需要说明的是，第一PGU和第二PGU可参见上述PGU的相关介绍，此处不再重复赘述。另外，在位置A形成的虚像2的过程可参见前述消除虚像的重影的实现方式，在虚位置B形成的虚像1不需要消除重影。
基于上述描述的HUD系统的结构和功能原理，本申请还可以提供一种车辆，该车辆可以包括上述HUD系统和风挡。所述风挡用于将来自所述HUD系统的光线反射至眼盒，所述眼盒为驾驶员的双目所处的区域。
当然该车辆还可以包括其他器件，例如方向盘、处理器、存储器、无线通信装置和传感器等。如图14所示，为本申请提供的一种车辆部分结构的简化示意图。该车辆可包括 HUD系统和风挡。HUD系统可位于方向盘下方。
应理解，图14所示的硬件结构仅是一个示例。本申请所适用的车辆可以具有比图14中所示车辆更多的或者更少的部件，可以组合两个或更多的部件，或者可以具有不同的部件配置。
可以理解的是，本申请的实施例中的处理器可以是中央处理单元(central processing unit，CPU)，还可以是其它通用处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现场可编程门阵列(field programmable gate array，FPGA)或者其它可编程逻辑器件、晶体管逻辑器件，硬件部件或者其任意组合。通用处理器可以是微处理器，也可以是任何常规的处理器。
在一种可能的实现方式中，风挡包括楔型风挡(请参阅15)或者平面风挡。需要说明的是，前述实施例中的风挡即为平面型风挡。
需要说明的是，通过将楔形风挡的垂直像面与水平像面分离，可以实现消除重影与虚像距的解耦。即可以实现改变水平像面的位置，从而可以改变虚像距的大小。例如，可应用于已经装配了W-HUD系统的车辆，其风挡一般是楔形风挡，虚像距一般是2.5m。通过将垂直像面与水平像面分离，可以实现将水平像面拉远，即可以增大虚像距，例如可以将虚像距增大到5m及5m以上(如15m)的距离。
对于楔形风挡可以通过选取合适的楔角δ来消除重影。结合上述图15，可得到如下几何关系。
γ 1＝α-β
β 2＝β 1+2δ
Figure PCTCN2021139994-appb-000013
AB+t·tan(β 1)+t·tan(β 2)＝a·sin(α)
其中，α表示射入风挡的前外表面的光线的入射角为α，β表示副像的光线在前外表面的入射角，β 1表示副像的光线在前外表面的光线的折射角，β 2表示副像的光线在前外表面的光线的折射角。
由上述公式可以看出，选取合适的楔角δ可以使得主像与副像在同一条直线上，此时人眼看到的主像和副像是重合的，即消除了重影。
在本申请的各个实施例中，如果没有特殊说明以及逻辑冲突，不同的实施例之间的术语和/或描述具有一致性、且可以相互引用，不同的实施例中的技术特征根据其内在的逻辑关系可以组合形成新的实施例。
本申请中，“均匀”不是指绝对的均匀，可以允许有一定工程上的误差。“垂直”不是指绝对的垂直，可以允许有一定工程上的误差。“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况，其中A，B可以是单数或者复数。“以下至少一项(个)”或其类似表达，是指这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a，b或c中的至少一项(个)，可以表示：a，b，c，“a和b”，“a和c”，“b和c”，或“a和b和c”，其中a，b，c可以是单个，也可以是多个。在本申请的文字描述中，字符“/”，一般表示前后关联对象是一种“或”的关 系。在本申请的公式中，字符“/”，表示前后关联对象是一种“相除”的关系。另外，在本申请中，“示例的”一词用于表示作例子、例证或说明。本申请中被描述为“示例”的任何实施例或设计方案不应被解释为比其它实施例或设计方案更优选或更具优势。或者可理解为，使用示例的一词旨在以具体方式呈现概念，并不对本申请构成限定。
可以理解的是，在本申请中涉及的各种数字编号仅为描述方便进行的区分，并不用来限制本申请的实施例的范围。上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定。术语“第一”、“第二”等类似表述，是用于分区别类似的对象，而不必用于描述特定的顺序或先后次序。此外，术语“包括”和“具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元。方法、系统、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。
尽管结合具体特征及其实施例对本申请进行了描述，显而易见的，在不脱离本申请的精神和范围的情况下，可对其进行各种修改和组合。相应地，本说明书和附图仅仅是所附权利要求所界定的方案进行示例性说明，且视为已覆盖本申请范围内的任意和所有修改、变化、组合或等同物。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本发明的精神和范围。这样，倘若本申请实施例的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (11)

  1. 一种抬头显示HUD系统，其特征在于，包括M个图像产生单元PGU和光学成像单元，所述PGU包括矩形像素，所述M为正整数；
    所述PGU，用于产生图像，并将所述图像的光线传播至所述光学成像单元；
    所述光学成像单元，用于对所述图像分别进行横向放大和纵向放大，并将放大后的图像的光线传播至风挡；所述放大后的图像的光线经所述风挡反射后的反向延长线在第一预设位置形成虚像，其中，横向放大率与纵向放大率不同，所述虚像的横向像素密度与纵向像素密度相同。
  2. 如权利要求1所述的HUD系统，其特征在于，所述矩形像素的横向宽度和纵向宽度的比值等于所述纵向放大率与所述横向放大率的比值。
  3. 如权利要求2所述的HUD系统，其特征在于，所述横向放大率是根据所述PGU的横向宽度、所述HUD系统的虚像距和所述HUD系统的横向视场角确定的；所述纵向放大率是根据所述PGU的纵向宽度、所述HUD系统的虚像距和所述HUD系统的纵向视场角确定的。
  4. 如权利要求3所述的HUD系统，其特征在于，
    所述横向放大率＝2×HUD系统的虚像距×tan(横向视场角/2)/PGU的横向宽度；
    所述纵向放大率＝2×HUD系统的虚像距×tan(纵向视场角/2)/PGU的纵向宽度。
  5. 如权利要求1所述的HUD系统，其特征在于，所述光学成像单元，用于：
    对所述图像分别进行横向放大和纵向放大，在水平面和垂直面分别改变所述图像的光线的传播路径，并将放大且改变路径后的光线传播至所述风挡；
    其中，所述放大且改变路径后的光线经所述风挡反射后的反向延长线在所述垂直面聚焦于垂直像面，在所述水平面聚焦于水平像面；所述垂直像面与所述水平像面处于不同的位置，所述垂直像面与眼盒的中心之间距离是根据预设角分辨率确定的，所述眼盒为驾驶员的双目所处区域。
  6. 如权利要求5所述的HUD系统，其特征在于，所述光学成像单元包括以下任一项：
    第一曲面反射镜，所述第一曲面反射镜的横向焦距与纵向焦距不同；
    第二曲面镜反射和柱面镜，所述柱面镜位于水平面或垂直面，所述水平像面位于所述水平面，所述垂直像面位于所述垂直面；
    第三曲面反射和第四曲面反射镜，所述第三曲面反射和所述第四曲面反射镜中至少一个曲面反射镜的横向焦距与纵向焦距不同。
  7. 如权利要求5或6所述的HUD系统，其特征在于，所述光学成像组件还包括变焦透镜；
    所述变焦透镜，用于通过调节横向焦距，改变所述水平像面的位置和/或横向放大率；和/或，用于通过调节纵向焦距，改变所述垂直像面的位置和/或纵向放大率。
  8. 如权利要求5至7任一项所述的HUD系统，其特征在于，所述M个PGU包括第一PGU和第二PGU，所述光学成像单元包括平面反射镜、第二曲面反射镜和柱面镜；
    所述平面反射镜，用于将来自所述第一PGU的图像的光线反射至所述第二曲面反射镜；
    所述柱面镜，用于改变来自所述第二PGU的图像的光线的传播路径，并将传播路径 改变后的光线反射至所述第二曲面反射镜；
    所述第二曲面反射镜，用于将来自所述柱面镜的光线形成的图像进行横向放大和纵向放大，并将放大后的图像的光线传播至所述风挡，经所述风挡反射后的光线的反向延长线在垂直面上聚焦于所述垂直像面，在水平面上聚焦于所述水平像面；并将来自所述平面反射镜的光线形成的图像进行横向放大和纵向放大，并将放大后的图像的光线传播至所述风挡，经所述风挡反射后的光线的反向延长线在第二预设位置形成虚像。
  9. 如权利要求8所述的HUD系统，其特征在于，所述第二预设位置是根据预设角分辨率确定、眼盒的中心位置、入射光的入射角、所述风挡的厚度以及所述风挡的折射率确定的。
  10. 一种车辆，其特征在于，包括如权利要求1～9任一项所述的抬头显示HUD系统、以及风挡；所述风挡用于将来自所述HUD系统的光线反射至眼盒，所述眼盒为驾驶员的双目所处的区域。
  11. 如权利要求10所述的车辆，其特征在于，所述风挡包括楔型风挡或平面型风挡。
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