WO2023143008A1 - 投影镜头、投影设备及车辆 - Google Patents

投影镜头、投影设备及车辆 Download PDF

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Publication number
WO2023143008A1
WO2023143008A1 PCT/CN2023/071336 CN2023071336W WO2023143008A1 WO 2023143008 A1 WO2023143008 A1 WO 2023143008A1 CN 2023071336 W CN2023071336 W CN 2023071336W WO 2023143008 A1 WO2023143008 A1 WO 2023143008A1
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Prior art keywords
lens
projection
image source
lens group
group
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PCT/CN2023/071336
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English (en)
French (fr)
Inventor
贺保丁
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华为技术有限公司
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Publication of WO2023143008A1 publication Critical patent/WO2023143008A1/zh

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/005—Projectors using an electronic spatial light modulator but not peculiar thereto
    • G03B21/006—Projectors using an electronic spatial light modulator but not peculiar thereto using LCD's
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
    • G02B13/0055—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element
    • G02B13/006—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element at least one element being a compound optical element, e.g. cemented elements
    • 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
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • 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
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G02B7/028—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/142—Adjusting of projection optics
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2073—Polarisers in the lamp house

Definitions

  • the present application relates to the field of projection technology, in particular to a projection lens, projection equipment and a vehicle.
  • intelligent projection headlights have a long projection distance, a large range, and high requirements for brightness.
  • the system output brightness of intelligent projection headlights is related to the energy of the light source on the one hand, and related to the light transmission efficiency on the other hand. Due to the limitation of light source energy, how to effectively improve the light transmission efficiency has become an urgent problem to be solved.
  • the application provides a projection lens, projection equipment and a vehicle, which have high light transmission efficiency and high projection brightness.
  • the present application provides a projection lens that can be applied to a projection device.
  • the projection device includes a liquid crystal on silicon chip as an image source, and the projection lens is located on the projection side of the liquid crystal on silicon chip.
  • the projection lens includes a first lens group, a polarization beam splitting prism and a second lens group arranged in sequence along the projection side to the image source side, and the second lens group has positive refractive power.
  • the projection light projected by the liquid crystal on silicon chip passes through the second lens group, enters the polarization beam splitter prism, and then projects out through the first lens group to form an image on the projection side of the projection lens.
  • the second lens group has positive refractive power, the second lens group can converge the light, thereby reducing the incident angle of the projection light entering the polarization beam splitter prism, so as to improve the transmission efficiency of the projection light at the polarization beam splitter prism, so that the projection lens and the projection device High light transmission efficiency and high projection brightness.
  • the focal length f2 of the second lens group and the focal length EFL of the projection lens satisfy: 1.8 ⁇ f2/EFL ⁇ 1.
  • the second lens group can change The angle at which the projection light enters the polarization beamsplitter prism makes the angle between the projection light and the optical axis of the system smaller, and the incident angle of the projection light entering the polarization beamsplitter prism is smaller, thereby effectively improving the transmission efficiency of the projection light at the polarization beamsplitter prism and improving the polarization beam splitter.
  • the utilization rate of the projection light by the prism improves the light transmission efficiency of the projection lens and the projection device, so that the brightness of the image finally projected by the projection device is high.
  • the first lens group can have positive optical power.
  • the focal length f1 of the first lens group and the focal length EFL of the projection lens satisfy: f1/EFL ⁇ 2.
  • the first lens group can cooperate with the second lens group, and through the reasonable collocation of the materials and shapes of the lenses in the first lens group and the second lens group, both the viewing angle of the projection lens and the projected image can be taken into account. clarity.
  • the ratio range of the focal length f1 of the first lens group to the effective focal length EFL of the projection lens the projection light projected by the polarization beam splitter is changed, which helps the projection lens to achieve the effect of high-definition projection, making the projection The projection image quality of the device is better.
  • the projection lens is provided with a split first lens group and a second lens group, and the focal power of the entire projection lens can be flexibly adjusted by setting the focal power of the first lens group and/or the second lens group, and can The optical power of the second lens group takes into account the light transmission efficiency of the projection lens, so as to improve the performance of the projection device.
  • the first lens group includes three to six lenses
  • the second lens group includes two to three lenses
  • both the first lens and the last lens near the projection side of the first lens group have positive power; the first lens near the projection side of the second lens group has positive power, and the last lens has negative power. Focus.
  • the first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged from the projection side to the image source side, and the first lens and the fifth lens have positive refractive power , one of the second lens, the third lens and the fourth lens has a positive refractive power, and the other two lenses have a negative refractive power;
  • the second lens group includes a sixth lens and a sixth lens arranged from the projection side to the image source side Seven lenses, the sixth lens has positive power, and the seventh lens has negative power.
  • the first lens group may include five lenses, which are respectively the first lens, the second lens, the third lens, the fourth lens, and the fifth lens arranged from the projection side to the image source side, and each lens coaxial setting.
  • the first lens, the fourth lens and the fifth lens have positive refractive power, and the second lens and the third lens have negative refractive power.
  • the projection lens further includes an aperture, and the aperture may be located between the second lens and the third lens.
  • the first lens group may include at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the fifth lens has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the third lens and the fourth lens can be combined into a cemented lens group to eliminate chromatic aberration, reduce the volume of the projection lens, and reduce the tolerance sensitivity of the projection lens.
  • the second lens group may include two lenses, which are respectively the sixth lens and the seventh lens arranged from the projection side to the image source side, and the lenses are arranged coaxially.
  • the sixth lens has positive optical power and the seventh lens has negative optical power.
  • the second lens group includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the seventh lens has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the first lens group may include five lenses, which are respectively the first lens, the second lens, the third lens, the fourth lens, and the fifth lens arranged from the projection side to the image source side, and each lens coaxial setting.
  • the first lens, the fourth lens and the fifth lens have positive refractive power, and the second lens and the third lens have negative refractive power.
  • the projection lens further includes an aperture, and the aperture may be located between the second lens and the third lens.
  • the first lens group may include at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the fifth lens has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the third lens and the fourth lens can be combined into a cemented lens group to eliminate chromatic aberration, reduce the size of the projection lens, and reduce tolerance sensitivity.
  • the second lens group may include three lenses, which are respectively the sixth lens, the seventh lens and the eighth lens arranged from the projection side to the image source side, and the lenses are arranged coaxially.
  • the sixth lens and the seventh lens have positive refractive power
  • the eighth lens has negative refractive power.
  • the second lens group includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the sixth lens has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the seventh lens and the eighth lens can be combined into a cemented lens group to eliminate chromatic aberration, reduce the volume of the projection lens, and reduce tolerance sensitivity.
  • the first lens group may include six lenses, which are respectively a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged from the projection side to the image source side, And each lens is coaxially arranged.
  • the first lens, the fourth lens, the fifth lens, and the sixth lens have positive refractive power
  • the second lens and the third lens have negative refractive power.
  • the projection lens further includes an aperture, and the aperture may be located between the second lens and the third lens.
  • the first lens group may include at least one lens having a negative temperature coefficient of refractive index (dn/dt ⁇ 0).
  • the fifth lens and the sixth lens have a negative temperature coefficient of refractive index (dn/dt ⁇ 0 ).
  • the third lens and the fourth lens can be combined into a cemented lens group to eliminate chromatic aberration, reduce the size of the projection lens, and reduce tolerance sensitivity.
  • the second lens group may include two lenses, which are respectively the seventh lens and the eighth lens arranged from the projection side to the image source side, and the lenses are arranged coaxially.
  • the seventh lens has positive optical power and the eighth lens has negative optical power.
  • the second lens group includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the seventh lens has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the third lens and the fourth lens of the first lens group are combined into a cemented lens group.
  • the third lens and the fourth lens are combined into a cemented lens group, which can eliminate chromatic aberration, reduce the volume of the projection lens, and reduce the tolerance sensitivity of the projection lens.
  • the first lens group can move along the optical axis direction of the projection lens.
  • the projection lens can focus at different projection distances, and the resolution remains clear.
  • the projection device can use the projection lens to realize the requirement of clear projection of the projection headlight at a distance of 4m to 50m.
  • the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy: 4.5 ⁇ TTL/EFL ⁇ 2.5.
  • the total length of the projection lens is short and the volume is small, making the structure of the projection lens more compact.
  • the optical back focus BFL of the projection lens and the focal length EFL of the projection lens satisfy: BFL/EFL ⁇ 0.5.
  • the first lens group includes at least one lens with a negative temperature coefficient of refractive index (dn/dt ⁇ 0), and the second lens group includes at least one lens with a negative temperature coefficient of refractive index (dn/dt ⁇ 0).
  • the first lens group is provided with a lens with a negative temperature coefficient of refraction index (dn/dt ⁇ 0), and the second lens group is also provided with a lens with a negative temperature coefficient of refraction index (dn/dt ⁇ 0). , which is beneficial to realize the adiabatic design of the projection lens.
  • the projection lens can be reasonably matched to the temperature coefficient of refractive index of each lens in the first lens group and the second lens group, and cooperate with the settings of the optical power of the first lens group and the second lens group and
  • the structural design of the lens can realize the adiabatic design of mutual compensation between optics and structure in the application environment of different temperatures of the projection lens, so that after the projection lens is focused at room temperature, there is no need to focus again, thus ensuring that the projection lens can project clearly at different temperatures Imaging makes the performance of the projection lens stable and adaptable to the environment.
  • the projection lens further includes an aperture, and the aperture is located in the first lens group, or between the first lens group and the polarization beam splitter.
  • the polarization beam splitter prism includes adjacent first image source sides and second image source sides, and the second lens group is located on the first image source side of the polarization beam splitter prism; the projection lens also includes a third lens group, the third lens group The lens group is located on the second image source side of the polarization beam splitter prism.
  • the present application also provides a projection device.
  • the projection device includes a light source, a polarizer, an image source, and a projection lens.
  • the light source is located on the light incident side of the polarization beam splitter prism of the projection lens.
  • the polarizer and the image source are arranged on the projection lens. On the image source side of the second lens group, the polarizer is closer to the projection lens than the image source.
  • the image source may include a liquid crystal on silicon chip.
  • the emitted light of the light source enters the polarizing beam splitting prism from the incident side of the polarizing beam splitting prism, and the polarizing beam splitting prism converts the emitted light into polarized light, wherein one path of polarized light exits the polarizing beam splitting prism, and passes through the second lens group and the polarizer in turn,
  • the silicon-based liquid crystal chip can adjust the polarization state of the light according to the projection pattern, and project the projection light.
  • the image is projected onto the projection surface. Since the photography lens has high light transmission efficiency, the projection device including the projection lens can also achieve high light transmission efficiency, and finally the brightness of the projected image is high.
  • the optical axis of the second lens group may be arranged parallel to the optical axis of the first lens group. In some other implementation manners, the optical axis of the second lens group may also be arranged perpendicular to the optical axis of the first lens group.
  • the projection side and the image source side of the polarization beam splitter prism are opposite sides.
  • the optical axis of the second lens group can also be perpendicular to the optical axis of the first lens group, the positions of the polarizer and the liquid crystal on silicon chip change with the second lens group.
  • the projection side and the image source side of the polarization beam splitter prism are two adjacent sides.
  • the projection device When the optical axis of the second lens group is arranged parallel to the optical axis of the first lens group, the first lens group, the polarization beam splitter, the second lens group, the polarizer and the silicon-based liquid crystal chip are all coaxially arranged, and the projection device is approximately long.
  • the strip shape, the height dimension is small, which can realize the convenient installation of the projection equipment in the long strip space.
  • the arrangement of the first lens group, the polarization beam splitter, the second lens group, the polarizer and the silicon-based liquid crystal chip was approximately square or L-shaped, which can Realize the installation of projection equipment in approximately square space or L-shaped space. Therefore, the projection lens and the projection device can be set through different arrangements of the first lens group and the second lens group to meet the installation requirements of different installation spaces and increase the scope of application.
  • the present application also provides a projection device.
  • the projection device includes a light source, a first polarizer, a second polarizer, a first image source, a second image source, and a projection lens.
  • the first polarizer and the first image source are arranged on the first image source side of the second lens group of the projection lens, and the first polarizer is closer to the projection lens than the first image source; the second polarizer and the second
  • the image source is arranged on the second image source side of the third lens group of the projection lens, and the second polarizer is closer to the projection lens than the second image source.
  • the first image source may include a first liquid crystal on silicon chip
  • the second image source may include a second liquid crystal on silicon chip.
  • the light emitted by the light source is divided into two polarized lights by the polarizing beam splitter prism, one of which is emitted from the first image source side of the polarizing beam splitting prism, and the other polarized light is emitted from the second image source of the polarizing beam splitting prism side shot.
  • the second lens group, the first polarizer and the first liquid crystal on silicon chip can use one polarized light to project, while the third lens group, the second polarizer and the second silicon-based liquid crystal chip can use another polarized light to project, This makes the projection lens have a higher utilization rate of the light emitted by the light source. Compared with the solution of using one channel of polarized light projection, the light utilization rate can reach 2 times or nearly 2 times.
  • the present application further provides a vehicle, the vehicle includes a headlight, and the headlight includes the projection device described in any one of the foregoing.
  • the headlights can be used as intelligent projection headlights of the vehicle.
  • the headlights of the vehicle adopt the aforementioned projection equipment, and its transparent picture has high brightness and small size.
  • FIG. 1 is a schematic structural diagram of a projection device provided by an embodiment of the present application.
  • Fig. 2 is a partial structural diagram of the projection device shown in Fig. 1 in some embodiments;
  • Fig. 3 is the modulation transfer function curve of the projection lens shown in Fig. 2 at normal temperature
  • Fig. 4 is a modulation transfer function curve of the projection lens shown in Fig. 2 at a temperature of -40°C;
  • Fig. 5 is a modulation transfer function curve of the projection lens shown in Fig. 2 at a temperature of 150°C;
  • Fig. 6 is a graph of vertical axis chromatic aberration in some embodiments of the projection lens shown in Fig. 2;
  • Fig. 7 is a partial structural schematic diagram of the projection device shown in Fig. 1 in other embodiments;
  • Fig. 8 is a modulation transfer function curve of the projection lens shown in Fig. 7 at normal temperature
  • Fig. 9 is a modulation transfer function curve of the projection lens shown in Fig. 7 at a temperature of -40°C;
  • Fig. 10 is a modulation transfer function curve of the projection lens shown in Fig. 7 at a temperature of 150°C;
  • Fig. 11 is a graph of vertical axis chromatic aberration in some embodiments of the projection lens shown in Fig. 7;
  • Fig. 12 is a partial structural diagram of the projection device shown in Fig. 1 in some other embodiments;
  • Fig. 13 is a modulation transfer function curve of the projection lens shown in Fig. 12 at room temperature;
  • Fig. 14 is a modulation transfer function curve of the projection lens shown in Fig. 12 at a temperature of -40°C;
  • Fig. 15 is a modulation transfer function curve of the projection lens shown in Fig. 12 at a temperature of 150°C;
  • Fig. 16 is a graph of vertical axis chromatic aberration in some embodiments of the projection lens shown in Fig. 12;
  • FIG. 17 is a schematic structural diagram of another projection device provided by an embodiment of the present application.
  • Focal power which characterizes the ability of an optical system to deflect light.
  • a lens or lens group with positive refractive power which has a positive focal length and has the effect of converging light rays.
  • a lens or lens group with negative optical power has a negative focal length and has the effect of diverging light rays.
  • Focal length also known as focal length, is a measure of the concentration or divergence of light in an optical system. The vertical distance from the principal surface on the image side to the focal plane.
  • the effective focal length (EFL) of the lens refers to the distance from the main surface of the lens image to the focal point.
  • the side where the image source is located is the image source side, and the surface of the lens close to the image source side can be called the image source side;
  • the side where the projected image is located is the projection side , the surface of the lens near the projection side can be called the projection side.
  • Aperture (F-number, denoted as F#) is a relative value obtained from the focal length of the lens / the diameter of the lens through the lens. The smaller the aperture number (F#), the greater the amount of light entering in the same unit time many.
  • the total track length (TTL) of the lens refers to the total length from the vertex of the surface closest to the projection side of the lens to the surface of the image source. TTL is the main factor forming the height of the projection device.
  • Optical back focus (BackFocal Length, BFL), the distance from the vertex of the surface of the last lens closest to the image source side to the focal plane.
  • Modulation Transfer Function also known as spatial contrast transfer function (spatial contrast transfer function), spatial frequency contrast sensitivity function (spatial frequency contrast sensitivity function), is a function of spatial frequency, reflecting the optical system to transfer various
  • the ability of frequency sinusoidal modulation degree is an evaluation quantity of system imaging quality.
  • the optical axis is a ray that passes perpendicularly through the center of an ideal lens.
  • the ideal convex mirror should be a point where all the light converges behind the lens. This point where all the light converges is the focus.
  • Field of view (FOV) in optical instruments, with the lens of the optical instrument as the vertex, and the angle formed by the two edges of the maximum range where the object image of the measured object can pass through the lens is called the field of view horn.
  • the size of the field of view determines the field of view of the optical instrument. The larger the field of view, the larger the field of view and the smaller the optical magnification.
  • Half image height (Image Height, IH) indicates the radius of the imaging circle.
  • the Abbe number (Abbe) that is, the dispersion coefficient, is the difference ratio of the refractive index of an optical material at different wavelengths, and represents the degree of dispersion of the material.
  • chromatic aberration of magnification also known as chromatic aberration of magnification or lateral chromatic aberration
  • the wavelength causes the magnification of the optical system to change, and the size of the image changes accordingly.
  • Diffraction limit means that an ideal object point is imaged by an optical system. Due to the limitation of diffraction, it is impossible to obtain an ideal image point, but a Fraunhofer diffraction image. Since the aperture of the general optical system is circular, the Fraunhofer diffraction image is the so-called Airy disk. In this way, the image of each object point is a diffuse spot, and it is difficult to distinguish two diffuse spots when they are close together, which limits the resolution of the system. The larger the spot, the lower the resolution.
  • the meridian plane the plane formed by the chief ray (main beam) of the object point outside the optical axis and the optical axis, is called the meridian plane.
  • Sagittal surface sagittal surface
  • the chief ray main beam passing through the object point outside the optical axis
  • the plane perpendicular to the meridian plane is called sagittal surface.
  • LCOS Liquid Crystal on Silicon
  • Polarization beam splitter can split the incident unpolarized light into two beams of linearly polarized light perpendicular to each other.
  • Polarizer has the ability to selectively absorb light vibrations in different directions, so that the diaphragm has a special direction.
  • the light vibration component perpendicular to this direction is completely absorbed. Absorption, only let the light vibration component parallel to this direction pass, and this specific direction is called the polarization direction of the polarizer.
  • the thickness, size and shape of lenses have been slightly exaggerated for convenience of illustration.
  • the shapes of spherical or aspheric surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspheric surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings.
  • the drawings are examples only and are not strictly drawn to scale.
  • Embodiments of the present application provide a projection lens, a projection device including the projection lens, and a vehicle including the projection device.
  • the headlights of the vehicle include the projection device, and the headlights can be used as intelligent projection headlights of the vehicle.
  • the projection lens includes a first lens group, a polarization beam splitting prism and a second lens group arranged in sequence along the projection side to the image source side, and the second lens group has positive refractive power.
  • the polarization splitter prism is arranged between the first lens group and the second lens group, and the second lens group has positive refractive power, so that the projection lens has higher light transmission efficiency and higher brightness of the projected picture.
  • the projection equipment can also be applied to the head-up display (Head Up Display, HUD), indoor projector or outdoor projector and other equipment.
  • FIG. 1 is a schematic structural diagram of a projection device 100 provided in an embodiment of the present application.
  • the projection device 100 may include a projection lens 10 , a light source 40 , a polarizer 20 and an image source.
  • the image source is an image display component for outputting a projected image.
  • the image source of the projection device 100 may be a liquid crystal on silicon chip 30 .
  • the image source of the projection device 100 may also be other chips for outputting projected images, which is not strictly limited in the present application.
  • the liquid crystal on silicon chip 30 is taken as an example for illustration.
  • the projection device 100 has a projection side and an image source side. The projection side is the side close to the image projected by the projection device 100 , and the image source side is the side close to the liquid crystal on silicon chip 30 .
  • the projection lens 10 may include a first lens group 1 , a polarization beam splitter prism 3 and a second lens group 2 , and the first lens group 1 , the polarization beam splitter prism 3 and the second lens group 2 are arranged in sequence from the projection side to the image source side.
  • the light source 40 is located on the light-incident side of the polarizing beam-splitting prism 3 of the projection lens 10 , and the light-incident side of the polarizing beam-splitting prism 3 is used to receive incident light.
  • the polarizer 20 and the liquid crystal on silicon chip 30 are arranged on the image source side of the second lens group 2 of the projection lens 10, and the polarizer 20 is closer to the projection lens 10 than the image source.
  • the light source 40 may be a light-emitting diode (light-emitting diode, LED) light source or a laser light source, and the light source 40 may also be other types of light sources, which are not strictly limited in this application.
  • the emitted light from the light source 40 enters the polarized beamsplitter prism 3 from the incident side of the polarized beamsplitter prism 3, and the polarized beamsplitter prism 3 converts the emitted light into polarized light.
  • the liquid crystal on silicon chip 30 is irradiated, the liquid crystal on silicon chip 30 can adjust the polarization state of the light according to the projection pattern, and project the projection light, which passes through the polarizer 20, the second The lens group 2, the polarization beam splitter prism 3 and the first lens group 1 finally project the image onto the projection surface.
  • the second lens group 2 has positive refractive power. Since the second lens group 2 has positive refractive power, the second lens group 2 can converge the light, thereby reducing the incident angle of the projected light entering the polarization beam splitter prism 3 .
  • the incident angle at which the projection light enters the polarization beamsplitter prism 3 is small, so that the polarization beamsplitter prism 3 has less reflection of the projection light and high transmittance, thereby improving the transmission efficiency of the projection light at the polarization beamsplitter prism 3, so that the projection lens 10 and projection
  • the light transmission efficiency of the device 100 is high, and the projection brightness is high.
  • the high light transmission efficiency of the projection lens 10 and the projection device 100 can not only meet the needs of long-distance, large-scale, high-brightness projection in the use environment of vehicle smart projection headlights. Requirements, and avoid the problem that the size of the projection device 100 is larger due to the use of high-energy light sources, and realize the small volume and low cost of the intelligent projection headlight.
  • the industry usually adopts a solution to improve the projection brightness by improving the efficiency of the projection light source.
  • the improvement of the projection light source efficiency will inevitably lead to projection
  • the increase in the volume of the light source and the high cost have resulted in the problems of large volume and high cost in the projection equipment and the intelligent projection headlights using the projection equipment.
  • the projection brightness can be effectively improved without additionally increasing the efficiency of the projection light source or the increase in the efficiency of the projection light source is very small, and can even be reduced to a certain extent.
  • the efficiency of the projection light source is conducive to the small size and low-cost design of the projection device 100 and the intelligent projection headlight. It has high applicability and wide application range in the vehicle field where space and cost requirements are becoming more and more stringent.
  • the focal length f2 of the second lens group 2 and the focal length EFL of the projection lens 10 satisfy: 1.8 ⁇ f2/EFL ⁇ 1.
  • the value of f2/EFL may be 1.20, 1.31, 1.36, 1.40, 1.50, 1.62, 1.71, etc.
  • the second The lens group 2 can change the angle at which the projected light enters the polarizing beamsplitter prism 3, so that the angle between the projected light and the optical axis of the system is small, and the incident angle at which the projected light enters the polarizing beamsplitter prism 3 is small, thereby effectively improving the projection light in the polarizing beamsplitting prism 3.
  • the transmission efficiency is improved, the utilization rate of the projection light by the polarization beam splitter 3 is improved, the light transmission efficiency of the projection lens 10 and the projection device 100 is improved, and the brightness of the image finally projected by the projection device 100 is high.
  • the first lens group 1 may have positive refractive power.
  • the focal length f1 of the first lens group 1 and the focal length EFL of the projection lens 10 satisfy: f1/EFL ⁇ 2.
  • the value of f1/EFL may be 2.25, 2.32, 2.46, 2.53, 2.60, 2.65, 3.21, etc.
  • the first lens group 1 can cooperate with the second lens group 2, and through the rational collocation of the materials and shapes of the lenses in the first lens group 1 and the second lens group 2, the viewing angle of the projection lens 10 can also be considered. Field angle and sharpness of the projected image.
  • the projection lens 10 is provided with separate first lens group 1 and second lens group 2, and the power of the entire projection lens 10 can be flexibly adjusted by setting the optical power of the first lens group 1 and/or the second lens group 2.
  • optical power, and the optical power of the second lens group 2 can take into account the transmission efficiency of projection light, so as to improve the performance of the projection device 100 .
  • the first lens group 1 includes three to six lenses
  • the second lens group 2 includes two to three lenses.
  • both the first lens and the last lens near the projection side of the first lens group 1 have positive refractive power; the first lens near the projection side of the second lens group 2 has positive refractive power, and the last lens has positive refractive power. Negative optical power.
  • the first lens group 1 includes a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15 arranged from the projection side to the image source side, the first lens 11,
  • the 5th lens 15 has positive refractive power
  • a piece of lens in the second lens 12 has positive refractive power
  • other two lenses have negative refractive power
  • the sixth lens 21 and the seventh lens 22 are arranged side by side to the image source side, the sixth lens 21 has a positive refractive power, and the seventh lens 22 has a negative refractive power.
  • the third lens 13 and the fourth lens 14 of the first lens group 1 are combined into a cemented lens group.
  • the third lens 13 and the fourth lens 14 are combined into a cemented lens group, which can eliminate chromatic aberration, reduce the volume of the projection lens 10 , and reduce the tolerance sensitivity of the projection lens 10 .
  • the f-number (F#) of the projection lens 10 can reach 1.3.
  • the value of F-number (F#) may be 1.3, 1.38, etc.
  • the f-number (F#) of the projection lens 10 can reach 1.3, which can have a smaller f-number (F#) compared to the prior art, and achieve a large
  • the aperture increases the amount of light passing through the projection lens 10 , thereby improving the brightness of the image finally projected by the projection device 100 .
  • the first lens group 1 can move along the optical axis of the projection lens 10 .
  • the movement of the first lens group 1 can be realized automatically by setting a driving component such as a motor, or can be manually moved by a user, which is not strictly limited in this application.
  • the projection lens 10 can focus at different projection distances, and the resolution keep it clear.
  • the projection device 100 can use the projection lens 10 to realize the clear projection requirement of the projection headlight at a distance of 4m to 50m.
  • the total optical length TTL of the projection lens 10 and the focal length EFL of the projection lens 10 satisfy: 4.5 ⁇ TTL/EFL ⁇ 2.5.
  • the value of TTL/EFL may be 2.86, 3.32, 3.53, 3.75, 4.10, 4.15, 4.22, etc.
  • the total length of the projection lens 10 is short and the volume is small, so that the structure of the projection lens 10 is more compact.
  • the optical back focus BFL of the projection lens 10 and the focal length EFL of the projection lens 10 satisfy: BFL/EFL ⁇ 0.5.
  • the value of BFL/EFL can be 0.20, 0.26, 0.30, 0.32, 0.39, 0.41, 0.46, etc.
  • the first lens group 1 includes at least one lens with a negative temperature coefficient of refractive index (dn/dt ⁇ 0), and the second lens group 2 includes at least one lens with a negative temperature coefficient of refractive index (dn/dt ⁇ 0). lens.
  • the first lens group 1 is provided with a lens with a negative temperature coefficient of refraction index (dn/dt ⁇ 0), and the second lens group 2 is also provided with a lens with a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the lens is beneficial to realize the adiabatic design of the projection lens 10 .
  • the projection lens 10 can reasonably match the refractive index temperature coefficients of the lenses in the first lens group 1 and the second lens group 2, and cooperate with the light of the first lens group 1 and the second lens group 2.
  • the setting of the focal power and the structural design of the lens can realize the adiabatic design in which the optics and the structure compensate each other in the application environment of different temperatures of the projection lens 10, so that the projection lens 10 does not need to focus again after focusing at room temperature, thereby ensuring projection
  • the lens 10 can clearly project images at different temperatures, so that the projection lens 10 has stable performance and strong adaptability to the environment.
  • the optical axis of the second lens group 2 can be arranged parallel to the optical axis of the first lens group 1 .
  • the projection side and the image source side of the polarization beam splitter prism 3 are opposite sides.
  • the optical axis of the second lens group 2 may also be perpendicular to the optical axis of the first lens group 1 , and the positions of the polarizer 20 and the liquid crystal on silicon chip 30 vary with the second lens group 2 .
  • the projection side and the image source side of the polarization beam splitter prism 3 are two adjacent sides.
  • the optical axis of the second lens group 2 when the optical axis of the second lens group 2 is arranged parallel to the optical axis of the first lens group 1, the first lens group 1, the polarization beam splitter prism 3, the second lens group 2, the polarizer 20 and the silicon substrate
  • the liquid crystal chips 30 are all coaxially arranged, and the projection device 100 is roughly strip-shaped, with a small dimension in the height direction, which can realize the convenient installation of the projection device 100 in the strip-shaped space.
  • the projection lens 10 and the projection device 100 can be set through different arrangements of the first lens group 1 and the second lens group 2 to meet the installation requirements of different installation spaces and increase the scope of application.
  • the projection lens 10 further includes an aperture 50 , and the aperture 50 is located in the first lens group 1 , or located between the first lens group 1 and the polarization beam splitter prism 3 .
  • FIG. 2 is a partial structural diagram of the projection device 100 shown in FIG. 1 in some embodiments.
  • the projection device 100 may include a projection lens 10 , a polarizer 20 and a liquid crystal on silicon chip 30 .
  • the projection lens 10 may include a first lens group 1 , a polarization beam splitter prism 3 and a second lens group 2 , and the first lens group 1 , the polarization beam splitter prism 3 and the second lens group 2 are arranged in sequence from the projection side to the image source side.
  • the polarizer 20 and the liquid crystal on silicon chip 30 are sequentially arranged on the image source side of the second lens group 2 of the projection lens 10 .
  • the first lens group 1 may include five lenses, which are respectively the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, and the fifth lens arranged from the projection side to the image source side. lens 15, and each lens is coaxially arranged. It should be noted that, in this embodiment, when the optical axes of the multi-lenses are slightly misaligned due to assembly or lens manufacturing process, it is also considered that the multi-lenses are arranged coaxially.
  • the first lens 11 , the fourth lens 14 and the fifth lens 15 have positive refractive power, and the second lens 12 and the third lens 13 have negative refractive power.
  • the projection lens 10 also includes a stop 50 which may be located between the second lens 12 and the third lens 13 .
  • the first lens group 1 includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the fifth lens 15 has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the third lens 13 and the fourth lens 14 can be combined into a cemented lens group to eliminate chromatic aberration, reduce the volume of the projection lens 10 , and reduce the tolerance sensitivity of the projection lens 10 .
  • the second lens group 2 may include two lenses, namely the sixth lens 21 and the seventh lens 22 arranged from the projection side to the image source side, and the lenses are arranged coaxially.
  • the sixth lens 21 has positive refractive power
  • the seventh lens 22 has negative refractive power
  • the image source side of the seventh lens 22 is concave
  • the projection side is convex.
  • the seventh lens 22 may be a meniscus lens.
  • the second lens group 2 includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the seventh lens 22 has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • Table 1 is the basic parameters of the projection lens 10 shown in FIG. The radius of curvature (R), thickness (Thickness), refractive index (Nd), Abbe number (Vd) and focal length (f).
  • the projection lens 10 when the projection lens 10 is in an ideal state, when the projection light enters the polarization beam splitter 3 through the second lens group 2, the angle between the projection light and the system optical axis can be reduced to less than 10°, and the polarization beam splitter prism 3, the transmission efficiency of light reaches about 85%, thereby improving the light transmission efficiency of the projection device 100 .
  • FIG. 3 to FIG. 6 are diagrams showing the optical properties of the projection lens 10 shown in FIG. 2 .
  • FIG. 3 is a modulation transfer function curve of the projection lens 10 shown in FIG. 2 at normal temperature.
  • the abscissa in Figure 3 is the spatial frequency, and the unit is line pairs/mm (lp/mm); the ordinate is the optical transfer function (Optical Transfer Function, OTF) modulus.
  • OTF Optical Transfer Function
  • 3 shows the modulation transfer function curves of the projection lens 10 at different positions in the meridional direction (0.0000 mm to 4.8360 mm) and in the sagittal direction (0.0000 mm to 4.8360 mm) at room temperature.
  • the pixel size of the liquid crystal on silicon chip 30 used in this embodiment is 4.3 ⁇ m, and the corresponding Nyquist frequency is 116 lp/mm.
  • the OTF coefficient corresponding to the full field of view of the projection lens 10 at room temperature is above 0.3, and the imaging quality is high.
  • FIG. 4 is a modulation transfer function curve of the projection lens 10 shown in FIG. 2 at a temperature of -40°C.
  • FIG. 5 is a modulation transfer function curve of the projection lens 10 shown in FIG. 2 at a temperature of 150° C.
  • the abscissa in Figure 4 and Figure 5 is the spatial frequency, and the unit is line pairs/mm (lp/mm); the ordinate is the optical transfer function (Optical Transfer Function, OTF) modulus.
  • OTF optical Transfer Function
  • FIG. 6 is a vertical axis chromatic aberration graph in some embodiments of the projection lens 10 shown in FIG. Diffraction-limited range in microns ( ⁇ m).
  • FIG. 6 shows the vertical axis chromatic aberration after the light with wavelengths of 460nm, 555nm, 617nm and Airy disk passes through the projection lens 10 shown in FIG. 2 .
  • the vertical axis chromatic aberration of the projection lens 10 is at most 3.7 ⁇ m, which is smaller than the size of one pixel of the liquid crystal on silicon chip 30, that is, within 4.3 ⁇ m. Therefore, the projection lens in this embodiment
  • the chromatic aberration control of 10 is very good, which meets the needs of clear projection.
  • FIG. 7 is a partial structural diagram of another embodiment of the projection device 100 shown in FIG. 1 .
  • the projection device 100 may include a projection lens 10 , a polarizer 20 and a liquid crystal on silicon chip 30 .
  • the projection lens 10 may include a first lens group 1 , a polarization beam splitter prism 3 and a second lens group 2 , and the first lens group 1 , the polarization beam splitter prism 3 and the second lens group 2 are arranged in sequence from the projection side to the image source side.
  • the polarizer 20 and the liquid crystal on silicon chip 30 are sequentially arranged on the image source side of the second lens group 2 of the projection lens 10 .
  • the first lens group 1 may include five lenses, which are respectively the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, and the fifth lens arranged from the projection side to the image source side. lens 15, and each lens is coaxially arranged.
  • the first lens 11 , the fourth lens 14 and the fifth lens 15 have positive refractive power
  • the second lens 12 and the third lens 13 have negative refractive power.
  • the projection lens 10 also includes a stop 50 which may be located between the second lens 12 and the third lens 13 .
  • the first lens group 1 includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the fifth lens 15 has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the third lens 13 and the fourth lens 14 can be combined into a cemented lens group to eliminate chromatic aberration, reduce the volume of the projection lens 10, and reduce tolerance sensitivity.
  • the second lens group 2 may include three lenses, which are respectively the sixth lens 21, the seventh lens 22, and the eighth lens 23 arranged from the projection side to the image source side, and the lenses are arranged coaxially.
  • the sixth lens 21 and the seventh lens 22 have positive refractive power
  • the eighth lens 23 has negative refractive power
  • the image source side of the eighth lens 23 is concave
  • the projection side is convex.
  • the eighth lens 23 may specifically be a meniscus lens.
  • the second lens group 2 includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the sixth lens 21 has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the seventh lens 22 and the eighth lens 23 can be combined into a cemented lens group to eliminate chromatic aberration, reduce the volume of the projection lens 10, and reduce tolerance sensitivity.
  • Table 3 is the basic parameters of the projection lens 10 shown in FIG.
  • FIG. 8 to FIG. 11 are representation diagrams of the optical performance of the projection lens 10 shown in FIG. 7 .
  • FIG. 8 is a modulation transfer function curve of the projection lens 10 shown in FIG. 7 at normal temperature.
  • the abscissa of Figure 8 is the spatial frequency, and the unit is line pairs/mm (line pairs/mm, lp/mm); the ordinate is the optical transfer function (Optical Transfer Function, OTF) modulus; wherein, the projection is shown in Figure 8 Modulation transfer function curves of the lens 10 at different positions (0.0000 mm to 4.8360 mm) in the meridional direction and different positions (0.0000 mm to 4.8360 mm) in the sagittal direction at room temperature.
  • OTF Optical Transfer Function
  • the pixel size of the liquid crystal on silicon chip 30 used in this embodiment is 4.3 ⁇ m, the corresponding Nyquist frequency is 116 lp/mm, the OTF coefficient corresponding to the full field of view is above 0.3, and the imaging quality is high.
  • FIG. 9 is a modulation transfer function curve of the projection lens 10 shown in FIG. 7 at a temperature of -40°C.
  • FIG. 10 is a modulation transfer function curve of the projection lens 10 shown in FIG. 7 at a temperature of 150° C.
  • the abscissa of Fig. 9 and Fig. 10 is the spatial frequency, and the unit is line pair/mm (line pairs/mm, lp/mm);
  • the ordinate is the optical transfer function (Optical Transfer Function, OTF) modulus; Wherein, Fig.
  • Figure 10 shows the modulation transfer functions of the projection lens 10 at different positions in the meridional direction (0.0000mm to 4.8360mm) and sagittal directions (0.0000mm to 4.8360mm) at temperatures of -40°C and 150°C respectively. curve.
  • FIG. 11 is a vertical axis chromatic aberration curve diagram in some embodiments of the projection lens 10 shown in FIG. 7, and the ordinate of FIG. 11 is the actual image height field value, and the unit is millimeter (mm); Diffraction-limited range in microns ( ⁇ m).
  • FIG. 11 shows the vertical axis chromatic aberration after the light with wavelengths of 460nm, 555nm, 617nm and Airy disk passes through the projection lens 10 shown in FIG. 7 . It can be seen from FIG. 11 that in this embodiment, the vertical axis chromatic aberration of the projection lens 10 is at most 2.7 ⁇ m, which is smaller than the size of one pixel of the liquid crystal on silicon chip 30, that is, within 4.3 ⁇ m. Therefore, the projection lens in this embodiment The chromatic aberration control of 10 is very good, which meets the needs of clear projection.
  • FIG. 12 is a partial structural diagram of the projection device 100 shown in FIG. 1 in some other embodiments.
  • the projection device 100 may include a projection lens 10 , a polarizer 20 and a liquid crystal on silicon chip 30 .
  • the projection lens 10 may include a first lens group 1 , a polarization beam splitter prism 3 and a second lens group 2 , and the first lens group 1 , the polarization beam splitter prism 3 and the second lens group 2 are arranged in sequence from the projection side to the image source side.
  • the polarizer 20 and the liquid crystal on silicon chip 30 are sequentially arranged on the image source side of the second lens group 2 of the projection lens 10 .
  • the first lens group 1 may include six lenses, which are respectively the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, and the fifth lens arranged from the projection side to the image source side.
  • the lens 15 and the sixth lens 16 are arranged coaxially.
  • the first lens 11 , the fourth lens 14 , the fifth lens 15 and the sixth lens 16 have positive refractive power
  • the second lens 12 and the third lens 13 have negative refractive power.
  • the projection lens 10 further includes an aperture 50 , and the aperture 50 may be located between the second lens 12 and the third lens 13 .
  • the first lens group 1 includes at least one lens with a negative temperature coefficient of refractive index (dn/dt ⁇ 0).
  • the fifth lens 15 and the sixth lens 16 have a negative temperature coefficient of refractive index (dn/dt ⁇ 0). ⁇ 0).
  • the third lens 13 and the fourth lens 14 can be combined into a cemented lens group to eliminate chromatic aberration, reduce the volume of the projection lens 10, and reduce tolerance sensitivity.
  • the second lens group 2 may include two lenses, namely the seventh lens 22 and the eighth lens 23 arranged from the projection side to the image source side, and the lenses are arranged coaxially.
  • the seventh lens 22 has positive refractive power
  • the eighth lens 23 has negative refractive power
  • the image source side of the eighth lens 23 is concave
  • the projection side is convex.
  • the eighth lens 23 may specifically be a meniscus lens.
  • the second lens group 2 includes at least one lens having a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • the seventh lens 22 has a negative temperature coefficient of refraction index (dn/dt ⁇ 0).
  • Table 5 is the basic parameters of the projection lens 10 shown in FIG. The radius of curvature (R), thickness (Thickness), refractive index (Nd), Abbe number (Vd) and focal length (f).
  • FIG. 13 to FIG. 16 are graphs showing the optical properties of the projection lens 10 shown in FIG. 12 .
  • FIG. 13 is a modulation transfer function curve of the projection lens 10 shown in FIG. 12 at normal temperature.
  • the abscissa in Figure 13 is the spatial frequency, and the unit is line pairs/mm (lp/mm); the ordinate is the optical transfer function (Optical Transfer Function, OTF) modulus.
  • 13 shows the modulation transfer function curves of the projection lens 10 at different positions in the meridional direction (0.0000 mm to 4.8360 mm) and in the sagittal direction (0.0000 mm to 4.8360 mm) at room temperature.
  • the pixel size of the liquid crystal on silicon chip 30 used in this embodiment is 4.3 ⁇ m, the corresponding Nyquist frequency is 116 lp/mm, the OTF coefficient corresponding to the full field of view is above 0.4, and the imaging quality is high.
  • FIG. 14 is a modulation transfer function curve of the projection lens 10 shown in FIG. 12 at a temperature of -40°C.
  • FIG. 15 is a modulation transfer function curve of the projection lens 10 shown in FIG. 12 at a temperature of 150° C.
  • the abscissa of Fig. 14 and Fig. 15 is the spatial frequency, and the unit is line pairs/mm (line pairs/mm, lp/mm);
  • the ordinate is the optical transfer function (Optical Transfer Function, OTF) modulus; Wherein, Fig.
  • Figure 15 shows the modulation transfer functions of the projection lens 10 at different positions in the meridian direction (0.0000mm to 4.8360mm) and sagittal directions (0.0000mm to 4.8360mm) at temperatures of -40°C and 150°C respectively. curve.
  • FIG. 16 is a vertical axis chromatic aberration graph in some embodiments of the projection lens 10 shown in FIG. 12 , and the ordinate of FIG. 16 is the actual image height field value, and the unit is millimeter (mm); the abscissa is Diffraction-limited range in microns ( ⁇ m).
  • FIG. 16 shows the vertical axis chromatic aberration of light with wavelengths of 460nm, 555nm, 617nm and Airy disk passing through the projection lens 10 of this embodiment. It can be seen from FIG. 16 that in this embodiment, the vertical axis chromatic aberration is at most 4 ⁇ m, which is smaller than the size of one pixel of the liquid crystal on silicon chip 30, that is, within 4.3 ⁇ m. Therefore, the chromatic aberration control of the projection lens 10 of this embodiment is very good , to meet the needs of clear projection.
  • the optical power of the first lens group 1 and the second lens group 2 can be matched by setting the positions of the first lens group 1, the polarization beam splitter prism 3 and the second lens group 2 of the projection lens 10 and the setting of the focal length, and through reasonable matching of the focal length, temperature coefficient of refraction index, thickness, refraction index and Abbe number of each lens in the first lens group 1 and the second lens group 2, in addition combining the projection lens 10 in the aperture , focal length, and total optical length, etc., realize the projection lens 10 with high light transmission efficiency, high projection brightness, high definition, large aperture, small size, and the application of the projection lens 10 at -40°C to 105°C
  • the adiabatic design of mutual compensation between optics and structure makes it unnecessary to focus again after the projection lens 10 is focused at room temperature, so that the projection lens 10 can maintain clear projection images at different temperatures, making the projection image quality of the projection device 100 high. Stable performance and strong adaptability to the environment.
  • FIG. 17 is a block diagram of another projection device 100 provided in this embodiment.
  • the projection device 100 may include a projection lens 10 , a light source 40 , a first polarizer 20 , a first image source, a second polarizer 60 and a second image source.
  • the first image source of the projection device 100 may be the first liquid crystal on silicon chip 30
  • the second image source of the projection device 100 may be the second liquid crystal on silicon chip 70
  • the first liquid crystal on silicon chip 30 and the second The liquid crystal on silicon chip 70 is used to output projected images.
  • the projection device 100 has a projection side, which is a side close to the image projected by the projection device 100 .
  • the polarization beam splitter prism 3 includes adjacent first image source side and second image source side, the first image source side is the side close to the first liquid crystal on silicon chip 30, the second image source side is close to the second silicon chip One side of the base liquid crystal chip 70.
  • the projection lens 10 may include a first lens group 1 , a polarization beam splitter prism 3 , a second lens group 2 and a third lens group 4 .
  • the second lens group 2 is positioned at the first image source side of the polarization beam splitter prism 3, the first lens group 1, the polarization beam splitter prism 3 and the second lens group 2 are arranged in sequence along the projection side to the first image source side, and the second lens group 2
  • the optical axis of the first lens group 1 is arranged parallel to the optical axis, the first polarizer 20 and the first liquid crystal on silicon chip 30 are arranged on the first image source side of the second lens group 2, and the first polarizer 20 is smaller than the first A liquid crystal on silicon chip 30 is close to the projection lens 10 .
  • the third lens group 4 is positioned at the second image source side of the polarization beam splitter prism 3, the optical axis of the third lens group 4 is vertically arranged with the optical axis of the first lens group 1, the second polarizer 60 and the second liquid crystal on silicon chip 70 Arranged on the second image source side of the third lens group 4 , the second polarizer 60 is closer to the projection lens 10 than the second liquid crystal on silicon chip 70 .
  • the light source 40 is located on the light incident side of the polarization beam splitter prism 3 of the projection lens 10 , and the light incident side of the polarization beam splitter prism 3 is used to receive incident light.
  • the light source 40 may be a light-emitting diode (light-emitting diode, LED) light source or a laser light source, and the light source 40 may also be other types of light sources, which are not strictly limited in this application.
  • the emitted light from the light source 40 enters the polarized beamsplitter prism 3 from the incident side of the polarized beamsplitter prism 3, and the polarized beamsplitter prism 3 divides the emitted light into two paths of polarized light, wherein one path of polarized light is self-polarized beamsplitter prism 3
  • the first image source is emitted from the side, passes through the second lens group 2 and the first polarizer 20 in turn, and then irradiates the first liquid crystal on silicon chip 30, and the first liquid crystal on silicon chip 30 can adjust the polarization state of light according to the projection pattern, projecting
  • the projection light passes through the first polarizer 20 , the second lens group 2 , the polarizing beam splitter prism 3 and the first lens group 1 in sequence, and finally projects an image onto the projection surface.
  • Another road of polarized light is emitted from the second image source side of the polarizing beam splitter prism 3, passes through the third lens group 4 and the second polarizer 60 successively, and is irradiated to the second liquid crystal on silicon chip 70, and the second liquid crystal on silicon chip 70 can be according to Projecting patterns, adjusting the polarization state of light, projecting projection light, the projection light passes through the second polarizer 60, the third lens group 4, the polarization beam splitter prism 3 and the first lens group 1 in sequence, and finally projects the image onto the projection surface.
  • the light emitted by the light source 40 is divided into two polarized lights by the polarization beam splitter prism 3, and the second lens group 2, the first polarizer 20 and the first liquid crystal on silicon chip 30 can use one polarized light for projection, And the third lens group 4, the second polarizer 60 and the second liquid crystal on silicon chip 70 can use another way of polarized light to project, so that the projection lens 10 has a higher utilization rate of the light emitted by the light source 40, compared with using one way of polarized light. With the solution of polarized light projection, the light utilization rate can reach 2 times or nearly 2 times.
  • the arrangement of the third lens group 4, the second polarizer 60 and the second liquid crystal on silicon chip 70 in this embodiment not only improves the light utilization and light transmission efficiency of the projection device 100, but also improves the projection brightness of the projection device 100 and the quality of the final projection image.
  • the relevant design of the first lens group 1 and the second lens group 2 can refer to the previous embodiments, and will not be repeated here.
  • the image output by the first LCOS chip 30 may be the same as the image output by the second LCOS chip 70, and the final image output by the projection device 100 is the first LCOS chip 30 and the second LCOS chip 70.
  • the liquid crystal chip 70 outputs a superimposed image of the image, and the projection brightness is higher, thereby enhancing the effect of the final output image of the projection device 100 .
  • the setting of each lens in the third lens group 4 can be the same as that of the second lens group 2
  • the distance between the third lens group 4 and the polarization beam splitter 3 can be the same as that between the second lens group 2 and the polarization beam splitter 3. distances are equal.
  • the first liquid crystal on silicon chip 30 can output a part of the image
  • the second liquid crystal on silicon chip 70 can output another part of the image
  • the image output by the first liquid crystal on silicon chip 30 and the second liquid crystal on silicon chip 70 The output images together form a complete image finally output by the projection device 100, so as to improve the projection quality.
  • the setting of each lens in the third lens group 4 can be different from the second lens group 2, and the distance between the third lens group 4 and the polarization beam splitter prism 3 can be the same as the distance between the second lens group 2 and the polarization beam splitter prism 3. The distances are not equal.

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  • Optics & Photonics (AREA)
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Abstract

一种投影镜头（10）、投影设备（100）及车辆。投影镜头（10）包括沿投影侧至像源侧依次排列的第一透镜组（1）、偏振分光棱镜（3）及第二透镜组（2），第二透镜组（2）具有正光焦度，使得投影镜头（10）具有较高的光传输效率，投影亮度高。

Description

投影镜头、投影设备及车辆
本申请要求于2022年01月27日提交中国专利局、申请号为202210103429.8、申请名称为“投影镜头、投影设备及车辆”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
本申请涉及投影技术领域，尤其涉及一种投影镜头、投影设备及车辆。
背景技术
近年来，随着汽车智能大灯照明、投影技术的发展，对光的控制需求越来越精细，像素级智能大灯正在得到快速的发展。对比室内投影机，智能投影大灯的投影距离远，范围大，对亮度要求高。而智能投影大灯的系统输出亮度一方面与光源能量相关，另一方面与光传输效率相关。由于光源能量的限制，如何有效提升光传输效率成为亟待解决的问题。
发明内容
本申请提供了一种投影镜头、投影设备及车辆，具有较高的光传输效率，投影亮度高。
第一方面，本申请提供了一种投影镜头，可以应用于投影设备中。投影设备包括可作为像源的硅基液晶芯片，投影镜头位于硅基液晶芯片的投影侧。投影镜头包括沿投影侧至像源侧依次排列的第一透镜组、偏振分光棱镜及第二透镜组，第二透镜组具有正光焦度。
在本申请中，硅基液晶芯片投射出的投影光线经第二透镜组，进入偏振分光棱镜，而后通过第一透镜组投射出，于投影镜头的投影侧成像。
由于第二透镜组具有正光焦度，第二透镜组能够汇聚光线，从而减小投影光线进入偏振分光棱镜的入射角度，以提升投影光线在偏振分光棱镜处传输效率，使得投影镜头和投影设备的光传输效率较高，投影亮度高。
一些实现方式中，第二透镜组的焦距f2与投影镜头的焦距EFL满足：1.8≥f2/EFL≥1。
在本实现方式中，通过对第二透镜组的焦距f2与投影镜头的有效焦距EFL的比值范围的合理设计，使得投影光线通过第二透镜组射入偏振分光棱镜时，第二透镜组能够改变投影光线进入偏振分光棱镜的角度，使得投影光线与系统光轴夹角较小，投影光线进入偏振分光棱镜的入射角度较小，从而有效提升投影光线在偏振分光棱镜处传输效率，提高了偏振分光棱镜对投影光线的利用率，提升了投影镜头和投影设备的光传输效率，使得投影设备最终投射出的影像的亮度高。
一些实现方式中，第一透镜组可以具有正光焦度。其中，第一透镜组的焦距f1与投影镜头的焦距EFL满足：f1/EFL≥2。
在本实现方式中，第一透镜组能够配合第二透镜组，并通过第一透镜组、第二透镜组的组内各镜片材料和形状的合理搭配，兼顾投影镜头的视场角和投影图像的清晰度。通过对第一透镜组的焦距f1与投影镜头的有效焦距EFL的比值范围的合理设计，以改变由偏振分光棱镜投射出的投影光线，有助于投影镜头实现高清晰度投影的效果，使得投影设备的投影成像质量更佳。
此外，投影镜头设置了分体的第一透镜组和第二透镜组，可以通过设置第一透镜组和/或第二透镜组的光焦度，灵活调节整个投影镜头的光焦度，并且能够通过第二透镜组的光焦 度兼顾投影镜头的光传输效率，以提高投影设备的性能。
一些实现方式中，第一透镜组包括三至六片透镜，第二透镜组包括二至三片透镜。
在本实现方式中，通过对第一透镜组和第二透镜组的透镜数量的合理设置，在满足第一透镜组和第二透镜组的焦距需求的同时，还可以兼顾投影设备小体积和低成本。
一些实现方式中，第一透镜组靠近投影侧的第一片透镜和最后一片透镜均具有正光焦度；第二透镜组靠近投影侧的第一片透镜具有正光焦度，最后一片透镜具有负光焦度。
一些实现方式中，第一透镜组包括从投影侧至像源侧排列的第一透镜、第二透镜、第三透镜、第四透镜、第五透镜，第一透镜、第五透镜具有正光焦度，第二透镜、第三透镜及第四透镜中的一片透镜具有正光焦度，另外两片透镜具有负光焦度；第二透镜组包括从投影侧至像源侧排列的第六透镜和第七透镜，第六透镜具有正光焦度，第七透镜具有负光焦度。
在本实现方式中，通过对第一透镜组和第二透镜组的各透镜数量和光焦度的合理设置，不仅使得投影镜头的光传输效率高、投影质量佳，而且投影镜头的体积小、制造成本较低，有利于投影镜头在智能投影大灯中的应用。
一些实现方式中，第一透镜组可以包括五片透镜，分别为从投影侧至像源侧排列的第一透镜、第二透镜、第三透镜、第四透镜、第五透镜，且各片透镜同轴设置。第一透镜、第四透镜及第五透镜具有正光焦度，第二透镜和第三透镜具有负光焦度。
其中，投影镜头还包括光阑，光阑可以位于第二透镜和第三透镜之间。
其中，第一透镜组可以包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第五透镜的折射率温度系数为负(dn/dt<0)。此外，第三透镜和第四透镜可以组合成胶合透镜组，以消除色差，缩小投影镜头的体积，降低投影镜头的公差敏感度。
其中，第二透镜组可以包括两片透镜，分别为从投影侧至像源侧排列的第六透镜和第七透镜，且各片透镜同轴设置。第六透镜具有正光焦度，第七透镜具有负光焦度。第二透镜组包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第七透镜的折射率温度系数为负(dn/dt<0)。
一些实现方式中，第一透镜组可以包括五片透镜，分别为从投影侧至像源侧排列的第一透镜、第二透镜、第三透镜、第四透镜、第五透镜，且各片透镜同轴设置。第一透镜、第四透镜及第五透镜具有正光焦度，第二透镜和第三透镜具有负光焦度。
其中，投影镜头还包括光阑，光阑可以位于第二透镜和第三透镜之间。
其中，第一透镜组可以包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第五透镜的折射率温度系数为负(dn/dt<0)。此外，第三透镜和第四透镜可以组合成胶合透镜组，以消除色差，缩小投影镜头的体积，降低公差敏感度。
其中，第二透镜组可以包括三片透镜，分别为从投影侧至像源侧排列的第六透镜、第七透镜及第八透镜，且各片透镜同轴设置。在本实现方式中，第六透镜和第七透镜具有正光焦度，第八透镜具有负光焦度。第二透镜组包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第六透镜的折射率温度系数为负(dn/dt<0)。此外，第七透镜和第八透镜可以组合成胶合透镜组，以消除色差，缩小投影镜头的体积，降低公差敏感度。
一些实现方式中，第一透镜组可以包括六片透镜，分别为从投影侧至像源侧排列的第一透镜、第二透镜、第三透镜、第四透镜、第五透镜和第六透镜，且各片透镜同轴设置。在本实现方式中，第一透镜、第四透镜、第五透镜及第六透镜具有正光焦度，第二透镜和第三透镜具有负光焦度。
其中，投影镜头还包括光阑，光阑可以位于第二透镜和第三透镜之间。
其中，第一透镜组可以包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第五透镜和第六透镜的折射率温度系数为负(dn/dt<0)。此外，第三透镜和第四透镜可以组合成胶合透镜组，以消除色差，缩小投影镜头的体积，降低公差敏感度。
其中，第二透镜组可以包括两片透镜，分别为从投影侧至像源侧排列的第七透镜和第八透镜，且各片透镜同轴设置。在本实现方式中，第七透镜具有正光焦度，第八透镜具有负光焦度。第二透镜组包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第七透镜的折射率温度系数为负(dn/dt<0)。
一些实现方式中，第一透镜组的第三透镜和第四透镜组合成胶合透镜组。
在本实现方式中，第三透镜和第四透镜组合成胶合透镜组，可以消除色差，缩小投影镜头的体积，降低投影镜头的公差敏感度。
一些实现方式中，第一透镜组能够沿投影镜头的光轴方向移动。
在本实现方式中，通过第一透镜组的移动，以调整第一透镜组与偏振分光棱镜之间的空气间隔的大小，即可实现投影镜头在不同投影距离下对焦，且解像力保持清晰。在一些实现方式中，投影设备可以通过投影镜头实现投影大灯在4m到50m使用距离清晰投影的需求。
一些实现方式中，投影镜头的光学总长TTL与投影镜头的焦距EFL满足：4.5≥TTL/EFL≥2.5。
在本实现方式中，通过对投影镜头的光学总长TTL与投影镜头的焦距EFL比值范围的合理设置，实现投影镜头总长短，体积小的目的，使得投影镜头的结构更紧凑。
一些实现方式中，投影镜头的光学后焦BFL与投影镜头的焦距EFL满足：BFL/EFL≤0.5。
在本实现方式中，通过对投影镜头的光学后焦BFL与投影镜头的焦距EFL比值范围的合理设置，实现投影镜头短后焦，体积小的目的。
一些实现方式中，第一透镜组包括至少一片折射率温度系数为负(dn/dt<0)的透镜，第二透镜组包括至少一片折射率温度系数为负(dn/dt<0)的透镜。
在本实现方式中，第一透镜组设有折射率温度系数为负(dn/dt<0)的透镜，第二透镜组也设有折射率温度系数为负(dn/dt<0)的透镜，有利于实现投影镜头的消热差设计。
在一些实现方式中，投影镜头可以通过对第一透镜组和第二透镜组中各透镜的折射率温度系数的合理搭配，并配合第一透镜组、第二透镜组的光焦度的设置和透镜的结构设计，可实现投影镜头不同温度的应用环境中，光学与结构相互补偿的消热差设计，使得投影镜头在常温对焦后，无需再次对焦，从而可以保证投影镜头在不同温度下清晰投影成像，使得投影镜头性能稳定，对环境适应性强。
一些实现方式中，投影镜头还包括光阑，光阑位于第一透镜组，或者位于第一透镜组与偏振分光棱镜之间。
一些实现方式中，偏振分光棱镜包括相邻的第一像源侧和第二像源侧，第二透镜组位于偏振分光棱镜的第一像源侧；投影镜头还包括第三透镜组，第三透镜组位于偏振分光棱镜的第二像源侧。
第二方面，本申请还提供一种投影设备，投影设备包括光源、偏光片、像源和投影镜头，光源位于投影镜头的偏振分光棱镜的入光侧，偏光片和像源排布于投影镜头的第二透镜组的像源侧，偏光片较像源靠近投影镜头。
一些实现方式中，像源包括可以硅基液晶芯片。其中，光源的发射光线从偏振分光棱镜的入光侧进入偏振分光棱镜，偏振分光棱镜将发射光线转换成偏振光，其中一路偏振光射出偏振分光棱镜后，依次通过第二透镜组和偏光片，照射到硅基液晶芯片，硅基液晶芯片可以 根据投影图案，调整光的偏振态，投射出投影光线，投影光线依次通过偏光片、第二透镜组、偏振分光棱镜以及第一透镜组，最终将图像投影到投影面上。由于摄影镜头具有较高的光线传输效率，因此包含投影镜头的投影设备也能实现较高光传输效率，最终投射出的影像的亮度较高。
一些实现方式中，第二透镜组的光轴可以与第一透镜组的光轴平行设置。在另一些实现方式中，第二透镜组的光轴也可以与第一透镜组的光轴垂直设置。
在本实现方式中，第二透镜组的光轴与第一透镜组的光轴平行设置时，偏振分光棱镜的投影侧和像源侧为相背的两侧。当第二透镜组的光轴也可以垂直于第一透镜组的光轴，偏光片及硅基液晶芯片的位置随第二透镜组变化。此时，偏振分光棱镜的投影侧和像源侧为相邻的两侧。第二透镜组的光轴与第一透镜组的光轴平行设置时，第一透镜组、偏振分光棱镜、第二透镜组、偏光片及硅基液晶芯片均同轴排列，投影设备大致为长条形，高度方向尺寸较小，可实现投影设备在长条形空间中的便捷安装。第二透镜组的光轴与第一透镜组的光轴垂直设置时，第一透镜组、偏振分光棱镜、第二透镜组、偏光片及硅基液晶芯片的排布近似方形或L形，可实现投影设备在近似方形空间或L形空间中的安装。故而，投影镜头和投影设备可以通过第一透镜组与第二透镜组的不同排布设置，以满足不同安装空间的安装要求，增加了适用范围。
第三方面，本申请还提供一种投影设备，投影设备包括光源、第一偏光片、第二偏光片、第一像源、第二像源及投影镜头，光源位于投影镜头的偏振分光棱镜的入光侧，第一偏光片和第一像源排布于投影镜头的第二透镜组的第一像源侧，第一偏光片较第一像源靠近投影镜头；第二偏光片和第二像源排布于投影镜头的第三透镜组的第二像源侧，第二偏光片较第二像源靠近投影镜头。其中，第一像源可以包括第一硅基液晶芯片，第二像源可以包括第二硅基液晶芯片。
在本实现方式中，光源的发射光线被偏振分光棱镜分为两路偏振光，其中一路偏振光自偏振分光棱镜的第一像源侧射出，另一路偏振光自偏振分光棱镜的第二像源侧射出。第二透镜组、第一偏光片及第一硅基液晶芯片能够利用一路偏振光进行投影，而第三透镜组、第二偏光片和第二硅基液晶芯片能够利用另一路偏振光进行投影，使得投影镜头对光源的发射光线的利用率较高，相较于利用一路偏振光投影的方案，光线利用率可以达到2倍或将近2倍。
第四方面，本申请还提供一种车辆，车辆包括前大灯，前大灯包括前述任一项描述的投影设备。其中，前大灯可作为车辆的智能投影大灯。车辆的前大灯采用前述投影设备，其透明画面亮度高且体积小。
附图说明
图1是本申请实施例提供的一种投影设备的结构示意图；
图2是图1所示投影设备在一些实施例中的部分结构示意图；
图3是图2所示投影镜头在常温下的调制传递函数曲线；
图4是图2所示投影镜头在-40℃温度下的调制传递函数曲线；
图5是图2所示投影镜头在150℃温度下的调制传递函数曲线；
图6是图2所示投影镜头在一些实施例中的垂轴色差曲线图；
图7是图1所示投影设备在另一些实施例中的部分结构示意图；
图8是图7所示投影镜头在常温下的调制传递函数曲线；
图9是图7所示投影镜头在-40℃温度下的调制传递函数曲线；
图10是图7所示投影镜头在150℃温度下的调制传递函数曲线；
图11是图7所示投影镜头在一些实施例中的垂轴色差曲线图；
图12是图1所示投影设备在再一些实施例中的部分结构示意图；
图13是图12所示投影镜头在常温下的调制传递函数曲线；
图14是图12所示投影镜头在-40℃温度下的调制传递函数曲线；
图15是图12所示投影镜头在150℃温度下的调制传递函数曲线；
图16是图12所示投影镜头在一些实施例中的垂轴色差曲线图；
图17是本申请实施例提供的另一种投影设备的结构示意图。
具体实施方式
下面将结合附图，对本申请实施例中的技术方案进行描述。
为方便理解，下面先对本申请所涉及的技术术语进行解释和描述。
光焦度(focal power)，表征光学系统偏折光线的能力。
具有正光焦度的透镜或透镜组，透镜或透镜组具有正的焦距，具有会聚光线的效果。
具有负光焦度的透镜或透镜组，透镜或透镜组具有负的焦距，具有发散光线的效果。
焦距(focal length)，也称为焦长，是光学系统中衡量光的聚集或发散的度量方式，指无限远的景物通过透镜或透镜组在焦平面结成清晰影像时，透镜或透镜组的像方主面至焦平面的垂直距离。
镜头有效焦距(effective focal length，EFL)，是指镜头像方主面到焦点的距离。
以透镜或透镜组为界，像源所在的一侧为像源侧，透镜靠近像源侧的表面可以称为像源侧面；以透镜或透镜组为界，投影图像所在的一侧为投影侧，透镜靠近投影侧的表面可以称为投影侧面。
光圈(Aperture)，光圈数(F-number，记作F#)，是镜头的焦距/镜头通光直径得出的相对值，光圈数(F#)愈小，在同一单位时间内的进光量便愈多。
镜头总长(total track length，TTL)，指镜头最靠近投影侧的表面顶点至像源表面的总长度，TTL是形成投影设备的高度的主要因素。
光学后焦(BackFocal Length，BFL)，镜头最后一片透镜最靠近像源侧的表面顶点至焦平面的距离。
调制传递函数(Modulation Transfer Function，MTF)，又称空间对比传递函数(spatial contrast transfer function)、空间频率对比敏感度函数(spatial frequencycontrast sensitivity function)，是以空间频率的函数，反映光学系统传递各种频率正弦物调制度的能力，是系统成像质量的一种评价量。
光轴，是一条垂直穿过理想透镜中心的光线。与光轴平行的光线射入凸透镜时，理想的凸镜应是所有的光线会聚在透镜后的一点，这个会聚所有光线的一点，即为焦点。
视场角(field of view，FOV)，在光学仪器中，以光学仪器的镜头为顶点，以被测目标的物像可通过镜头的最大范围的两条边缘构成的夹角，称为视场角。视场角的大小决定了光学仪器的视野范围，视场角越大，视野就越大，光学倍率就越小。
半像高(Image Height，IH)，表示成像圆的半径。
阿贝数(Abbe)，即色散系数，是光学材料在不同波长下的折射率的差值比，代表材料色散程度大小。
垂轴色差，也称为倍率色差或横向色差，光学系统对不同色光的放大率的差异称为倍率色差。波长引起光学系统的放大率的变化，像的大小随之变化。
衍射极限(diffraction limit)，是指一个理想物点经光学系统成像，由于衍射的限制， 不可能得到理想像点，而是得到一个夫朗和费衍射像。由于一般光学系统的口径都是圆形，夫朗和费衍射像就是所谓的艾里斑。这样每个物点的像就是一个弥散斑，两个弥散斑靠近后就不好区分，这样就限制了系统的分辨率，这个斑越大，分辨率越低。
子午面(meridian plane)，光轴外物点的主光线(主光束)与光轴所构成的平面，称为子午面。
弧矢面(sagittal surface)，过光轴外物点的主光线(主光束)，并与子午面垂直的平面，称为弧矢面。
硅基液晶(Liquid Crystal on Silicon，LCOS)芯片，一种基于反射模式的矩阵液晶显示装置。
偏振分光棱镜(polarization beam splitter，PBS)，能把入射的非偏振光分成两束相互垂直的线偏光。
偏光片(Polarizer)，对不同方向的光振动有选择吸收的性能，从而使膜片有一个特殊的方向，当一束自然光射到膜片上的时候，与此方向垂直的光振动分量完全被吸收，只让平行于该方向的光振动分量通过，该特定的方向叫做偏光片的偏振动方向。
下面将结合附图对本申请实施例中的技术方案进行描述。其中，在本申请实施例的描述中，除非另有说明，“/”表示或的意思，例如，A/B可以表示A或B；文本中的“和/或”仅仅是一种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这三种情况，另外，在本申请实施例的描述中，“多个”是指两个或多于两个。术语“第一”、“第二”等用词仅用于描述目的，而不能理解为暗示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。
在附图中，为了便于说明，已稍微夸大了透镜的厚度、尺寸和形状。具体来讲，附图中所示的球面或非球面的形状通过示例的方式示出。即，球面或非球面的形状不限于附图中示出的球面或非球面的形状。附图仅为示例而并非严格按比例绘制。
本申请实施例提供一种投影镜头、包括该投影镜头的投影设备、以及包括该投影设备的车辆，车辆的前大灯包括投影设备，前大灯可作为车辆的智能投影大灯。投影镜头包括沿投影侧至像源侧依次排列的第一透镜组、偏振分光棱镜及第二透镜组，第二透镜组具有正光焦度。本申请将偏振分光棱镜设置在第一透镜组和第二透镜组中间，第二透镜组具有正光焦度，使得投影镜头具有较高的光传输效率，投影画面亮度较高。其中，投影设备除应用于车辆的智能投影大灯，还可以应用于车载抬头显示器(Head Up Display，HUD)、室内投影仪或室外投影机等设备。
请参阅图1，图1是本申请实施例提供的一种投影设备100的结构示意图。
一些实施例中，投影设备100可以包括投影镜头10、光源40、偏光片20以及像源。其中，像源为图像显示元件，用于输出投影图像。示例性的，投影设备100的像源可以为硅基液晶芯片30。在其他一些实施例中，投影设备100的像源也可以为其他用于输出投影图像的芯片，本申请对此不做严格限制，以下实施例中均以硅基液晶芯片30为例进行说明。投影设备100具有投影侧和像源侧，投影侧为靠近投影设备100投射出的影像的一侧，像源侧为靠近硅基液晶芯片30的一侧。投影镜头10可以包括第一透镜组1、偏振分光棱镜3以及第二透镜组2，第一透镜组1、偏振分光棱镜3以及第二透镜组2沿投影侧至像源侧依次排列。光源40位于投影镜头10的偏振分光棱镜3的入光侧，偏振分光棱镜3的入光侧用于接收入射光线。偏光片20和硅基液晶芯片30排布于投影镜头10的第二透镜组2的像源侧，偏光片 20较像源靠近投影镜头10。光源40可以为发光二极管(light-emitting diode，LED)光源或激光光源，光源40也可以为其他种类的光源，本申请对此不做严格限定。
在本实施例中，光源40的发射光线从偏振分光棱镜3的入光侧进入偏振分光棱镜3，偏振分光棱镜3将发射光线转换成偏振光，其中一路偏振光射出偏振分光棱镜3后，依次通过第二透镜组2和偏光片20，照射到硅基液晶芯片30，硅基液晶芯片30可以根据投影图案，调整光的偏振态，投射出投影光线，投影光线依次通过偏光片20、第二透镜组2、偏振分光棱镜3以及第一透镜组1，最终将图像投影到投影面上。
一些实施例中，第二透镜组2具有正光焦度。由于第二透镜组2具有正光焦度，第二透镜组2能够汇聚光线，从而减小投影光线进入偏振分光棱镜3的入射角度。投影光线进入偏振分光棱镜3的入射角度较小，使得偏振分光棱镜3对投影光线的反射少，透过率高，从而可以提升投影光线在偏振分光棱镜3处传输效率，使得投影镜头10和投影设备100的光传输效率较高，投影亮度高。当投影设备100应用于车辆智能大灯时，投影镜头10和投影设备100较高的光传输效率，不仅可以满足车辆智能投影大灯在使用环境中，对于远距离、大范围、高亮度投影的要求，而且避免了由于使用高能量光源导致投影设备100的尺寸较大的问题，实现了智能投影大灯的小体积和低成本。
可以理解的是，业内目前为满足车辆智能投影大灯的远距离、高亮度投影需求，通常都采用通过提高投影光源的效率，以提升投影亮度的方案，然而，投影光源效率的提升必然导致投影光源体积的增加、且成本高，造成投影设备及应用投影设备的智能投影大灯、存在体积大、成本高的问题。而本申请方案中，通过提高投影镜头10和投影设备100的光传输效率，能够有效提升投影亮度，无需额外增加投影光源的效率或增加投影光源效率的幅度很小，甚至可以在一定程度上降低投影光源的效率，有利于投影设备100及智能投影大灯实现小体积、低成本的设计，在空间要求、成本要求越来越严格的车辆领域中，适用性高、适用范围广。
一些实施例中，第二透镜组2的焦距f2与投影镜头10的焦距EFL满足：1.8≥f2/EFL≥1。例如，f2/EFL的值可以是1.20、1.31、1.36、1.40、1.50、1.62、1.71等。
在本实施例中，通过对第二透镜组2的焦距f2与投影镜头10的有效焦距EFL的比值范围的合理设计，使得投影光线通过第二透镜组2射入偏振分光棱镜3时，第二透镜组2能够改变投影光线进入偏振分光棱镜3的角度，使得投影光线与系统光轴夹角较小，投影光线进入偏振分光棱镜3的入射角度较小，从而有效提升投影光线在偏振分光棱镜3处传输效率，提高了偏振分光棱镜3对投影光线的利用率，提升了投影镜头10和投影设备100的光传输效率，使得投影设备100最终投射出的影像的亮度高。
一些实施例中，第一透镜组1可以具有正光焦度。其中，第一透镜组1的焦距f1与投影镜头10的焦距EFL满足：f1/EFL≥2。例如，f1/EFL的值可以是2.25、2.32、2.46、2.53、2.60、2.65、3.21等。
在本实施例中，第一透镜组1能够配合第二透镜组2，并通过第一透镜组1、第二透镜组2的组内各镜片材料和形状的合理搭配，兼顾投影镜头10的视场角和投影图像的清晰度。通过对第一透镜组1的焦距f1与投影镜头10的有效焦距EFL的比值范围的合理设计，以改变由偏振分光棱镜3射出的投影光线，有助于投影镜头10实现高清晰度投影的效果，使得投影设备100的投影成像质量更佳。
此外，投影镜头10设置了分体的第一透镜组1和第二透镜组2，可以通过设置第一透镜组1和/或第二透镜组2的光焦度，灵活调节整个投影镜头10的光焦度，并且能够通过第二透镜组2的光焦度兼顾投影光线的传输效率，以提高投影设备100的性能。
一些实施例中，第一透镜组1包括三至六片透镜，第二透镜组2包括二至三片透镜。
在本实施例中，通过对第一透镜组1和第二透镜组2的透镜数量的合理设置，在满足第一透镜组1和第二透镜组2的焦距需求的同时，还可以兼顾投影设备100的小体积和低成本。
一些实施例中，第一透镜组1靠近投影侧的第一片透镜和最后一片透镜均具有正光焦度；第二透镜组2靠近投影侧的第一片透镜具有正光焦度，最后一片透镜具有负光焦度。
一些实施例中，第一透镜组1包括从投影侧至像源侧排列的第一透镜11、第二透镜12、第三透镜13、第四透镜14、第五透镜15，第一透镜11、第五透镜15具有正光焦度，第二透镜12、第三透镜13及第四透镜14中的一片透镜具有正光焦度，另外两片透镜具有负光焦度；第二透镜组2包括从投影侧至像源侧排列的第六透镜21和第七透镜22，第六透镜21具有正光焦度，第七透镜22具有负光焦度。
在本实施例中，通过对第一透镜组1和第二透镜组2的各透镜数量和光焦度的合理设置，不仅使得投影镜头10的光传输效率高、投影质量佳，而且投影镜头10的体积小、制造成本较低，有利于投影镜头10在智能投影大灯中的应用。
一些实施例中，第一透镜组1的第三透镜13和第四透镜14组合成胶合透镜组。
在本实施例中，第三透镜13和第四透镜14组合成胶合透镜组，可以消除色差，缩小投影镜头10的体积，降低投影镜头10的公差敏感度。
一些实施例中，投影镜头10的光圈数(F#)能够达到1.3。例如，光圈数(F#)的值可以是1.3、1.38等。
在本实施例中，投影镜头10的光圈数(F#)能够达到1.3，相对于现有技术能够具有较小的光圈数(F#)，在具有较高的光线传输效率的情况下，同时实现大光圈，增大投影镜头10的通光量，从而提高投影设备100最终投射出的影像的亮度。
一些实施例中，第一透镜组1能够沿投影镜头10的光轴方向移动。其中，第一透镜组1的移动可以通过设置马达等驱动组件实现自动移动，也可以由用户进行手动移动，本申请对此不做严格限制。
在本实施例中，通过第一透镜组1的移动，以调整第一透镜组1与偏振分光棱镜3之间的空气间隔的大小，即可实现投影镜头10在不同投影距离下对焦，且解像力保持清晰。在一些实施例中，投影设备100可以通过投影镜头10实现投影大灯在4m到50m使用距离清晰投影的需求。
一些实施例中，投影镜头10的光学总长TTL与投影镜头10的焦距EFL满足：4.5≥TTL/EFL≥2.5。例如，TTL/EFL的值可以是2.86、3.32、3.53、3.75、4.10、4.15、4.22等。
在本实施例中，通过对投影镜头10的光学总长TTL与投影镜头10的焦距EFL比值范围的合理设置，实现投影镜头10总长短，体积小的目的，使得投影镜头10的结构更紧凑。
一些实施例中，投影镜头10的光学后焦BFL与投影镜头10的焦距EFL满足：BFL/EFL≤0.5。例如，BFL/EFL的值可以是0.20、0.26、0.30、0.32、0.39、0.41、0.46等。
在本实施例中，通过对投影镜头10的光学后焦BFL与投影镜头10的焦距EFL比值范围的合理设置，实现投影镜头10短后焦，体积小的目的。
一些实施例中，第一透镜组1包括至少一片折射率温度系数为负(dn/dt<0)的透镜，第二透镜组2包括至少一片折射率温度系数为负(dn/dt<0)的透镜。
在本实施例中，第一透镜组1设有折射率温度系数为负(dn/dt<0)的透镜，第二透镜组2也设有折射率温度系数为负(dn/dt<0)的透镜，有利于实现投影镜头10的消热差设计。
在一些实施例中，投影镜头10可以通过对第一透镜组1和第二透镜组2中各透镜的折射 率温度系数的合理搭配，并配合第一透镜组1、第二透镜组2的光焦度的设置和透镜的结构设计，可实现投影镜头10不同温度的应用环境中，光学与结构相互补偿的消热差设计，使得投影镜头10在常温对焦后，无需再次对焦，从而可以保证投影镜头10在不同温度下清晰投影成像，使得投影镜头10性能稳定，对环境适应性强。
一些实施例中，第二透镜组2的光轴可以与第一透镜组1的光轴平行设置。此时，偏振分光棱镜3的投影侧和像源侧为相背的两侧。在其他一些实施例中，第二透镜组2的光轴也可以垂直于第一透镜组1的光轴，偏光片20及硅基液晶芯片30的位置随第二透镜组2变化。此时，偏振分光棱镜3的投影侧和像源侧为相邻的两侧。
在本实施例中，第二透镜组2的光轴与第一透镜组1的光轴平行设置时，第一透镜组1、偏振分光棱镜3、第二透镜组2、偏光片20及硅基液晶芯片30均同轴排列，投影设备100大致为长条形，高度方向尺寸较小，可实现投影设备100在长条形空间中的便捷安装。第二透镜组2的光轴与第一透镜组1的光轴垂直设置时，第一透镜组1、偏振分光棱镜3、第二透镜组2、偏光片20及硅基液晶芯片30的排布近似方形或L形，可实现投影设备100在近似方形空间或L形空间中的安装。故而，投影镜头10和投影设备100可以通过第一透镜组1与第二透镜组2的不同排布设置，以满足不同安装空间的安装要求，增加了适用范围。
其中，投影镜头10还包括光阑50，光阑50位于第一透镜组1，或者位于第一透镜组1与偏振分光棱镜3之间。
为方便理解本实施例提供的投影镜头10的效果，以下通过结合图2至图16更加详细地描述本实施例的一些具体的而非限制性的例子。
请参阅图2，图2是图1所示投影设备100在一些实施例中的部分结构示意图。
一些实施例中，投影设备100可以包括投影镜头10、偏光片20以及硅基液晶芯片30。投影镜头10可以包括第一透镜组1、偏振分光棱镜3以及第二透镜组2，第一透镜组1、偏振分光棱镜3以及第二透镜组2沿投影侧至像源侧依次排列。偏光片20和硅基液晶芯片30依次排布于投影镜头10的第二透镜组2的像源侧。
在本实施例中，第一透镜组1可以包括五片透镜，分别为从投影侧至像源侧排列的第一透镜11、第二透镜12、第三透镜13、第四透镜14、第五透镜15，且各片透镜同轴设置。需要说明的是，在本实施例中，当多片透镜由于装配原因或者透镜制作工艺等原因，其光轴存在少许错开时，也认为多片透镜是同轴设置。
其中，第一透镜11、第四透镜14以及第五透镜15具有正光焦度，第二透镜12和第三透镜13具有负光焦度。投影镜头10还包括光阑50，光阑50可以位于第二透镜12和第三透镜13之间。其中，第一透镜组1包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第五透镜15的折射率温度系数为负(dn/dt<0)。此外，第三透镜13和第四透镜14可以组合成胶合透镜组，以消除色差，缩小投影镜头10的体积，降低投影镜头10的公差敏感度。
在本实施例中，第二透镜组2可以包括两片透镜，分别为从投影侧至像源侧排列的第六透镜21和第七透镜22，且各片透镜同轴设置。其中，第六透镜21具有正光焦度，第七透镜22具有负光焦度，第七透镜22的像源侧面为凹面，投影侧面为凸面。第七透镜22具体可以是弯月透镜。第二透镜组2包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第七透镜22的折射率温度系数为负(dn/dt<0)。
以下结合数据和光学性能的表征图，呈现图2所示投影设备100在一些实施例中的具体化方案。
请结合参阅表1和表2，表1是图2所示投影镜头10在一些实施例中的基本参数，表2是图2所示投影设备100的各透镜、偏振分光棱镜3和偏光片20的曲率半径(R)、厚度(Thickness)、折射率(Nd)、阿贝数(Vd)和焦距(f)。
表1
光圈数F# 1.38
镜头有效焦距EFL 32mm
视场角FOV 17.7°
半像高IH 4.83mm
镜头总长TTL 120mm
第一透镜组焦距f1 80.88mm
第二透镜组焦距f2 41.98mm
光学后焦BFL 9.75mm
f1/EFL 2.53
f2/EFL 1.31
TTL/EFL 3.75
BFL/EFL 0.30
表2
Figure PCTCN2023071336-appb-000001
其中，表格中各个符号的含义如下：
S1：第一透镜11的投影侧面；
S2：第一透镜11的像源侧面；
S3：第二透镜12的投影侧面；
S4：第二透镜12的像源侧面；
S5：第三透镜13的投影侧面；
S6：第三透镜13与第四透镜14胶合处的透镜面；
S7：第四透镜14的像源侧面；
S8：第五透镜15的投影侧面；
S9：第五透镜15的像源侧面；
S10：偏振分光棱镜3的投影侧面；
S11：偏振分光棱镜3的像源侧面；
S12：第六透镜21的投影侧面；
S13：第六透镜21的像源侧面；
S14：第七透镜22的投影侧面；
S15：第七透镜22的像源侧面；
S16：偏光片20的投影侧面；
S17：偏光片20的像源侧面。
值得注意的是，下面以具体数值为例说明表2中用于表示曲率半径R的值的含义，对于5.67E+01，该公式中E+01代表10的一次方，因此5.67E+01的值为56.7；对于7.00E-01，该公式中E-01代表10的负一次方，因此7.00E-01的值为0.700；对于2.00E+00，该公式中E+00代表10的0次方，因此2.00E+00的值为2.00。
在本实施例中，投影镜头10在理想状态下，当投影光线经第二透镜组2射入偏振分光棱镜3时，投影光线与系统光轴夹角可减小至10°以下，偏振分光棱镜3对光的传输效率达到约85％，从而提高了投影设备100的光传输效率。
请一并参阅图3至图6，图3至图6是图2所示投影镜头10的光学性能的表征图。
示例性的，图3是图2所示投影镜头10在常温下的调制传递函数曲线。图3的横坐标为空间频率，单位为线对/毫米(line pairs/mm，lp/mm)；纵坐标为光学传递函数(Optical Transfer Function，OTF)模值。其中，图3中示意出投影镜头10在常温下，于子午方向的不同位置(0.0000mm至4.8360mm)、弧矢方向的不同位置(0.0000mm至4.8360mm)的调制传递函数曲线。本实施例采用的硅基液晶芯片30的像素大小为4.3μm，对应的奈奎斯特频率为116lp/mm。如图3中所示，投影镜头10在常温下的全视场对应的OTF系数在0.3以上，成像质量高。
示例性的，图4是图2所示投影镜头10在-40℃温度下的调制传递函数曲线。图5是图2所示投影镜头10在150℃温度下的调制传递函数曲线。图4和图5的横坐标为空间频率，单位为线对/毫米(line pairs/mm，lp/mm)；纵坐标为光学传递函数(Optical Transfer Function，OTF)模值。其中，图4和图5中分别示意出投影镜头10在-40℃和150℃温度下，于子午方向的不同位置(0.0000mm至4.8360mm)、弧矢方向的不同位置(0.0000mm至4.8360mm)的调制传递函数曲线。从图4和图5的调制传递函数曲线可以看出，从-40℃到105℃，在116lp/mm空间频率下，其全视场对应的OTF系数均在0.3以上，可以看出本实施例的投影镜头10从-40℃到105℃实现了消热差效果，在低温以及高温下的成像变形差异较小，使得投影镜 头10在较宽的温度范围内均能够满足成像清晰的要求。
示例性的，图6是图2所示投影镜头10在一些实施例中的垂轴色差曲线图，图6的纵坐标为实际像高视场值大小，单位为毫米(mm)；横坐标为衍射极限范围，单位为微米(μm)。图6显示出了波长分别为460nm、555nm、617nm、艾里斑的光经过图2所示投影镜头10后的垂轴色差。从图6中可以看出，本实施例中，投影镜头10的垂轴色差最大为3.7μm，小于硅基液晶芯片30一个像素的大小，即在4.3μm以内，因此本实施例中的投影镜头10的色差控制非常好，满足清晰投影需求。
请参阅图7，图7是图1所示投影设备100在另一些实施例中的部分结构示意图。
一些实施例中，投影设备100可以包括投影镜头10、偏光片20以及硅基液晶芯片30。投影镜头10可以包括第一透镜组1、偏振分光棱镜3以及第二透镜组2，第一透镜组1、偏振分光棱镜3以及第二透镜组2沿投影侧至像源侧依次排列。偏光片20和硅基液晶芯片30依次排布于投影镜头10的第二透镜组2的像源侧。
在本实施例中，第一透镜组1可以包括五片透镜，分别为从投影侧至像源侧排列的第一透镜11、第二透镜12、第三透镜13、第四透镜14、第五透镜15，且各片透镜同轴设置。其中，第一透镜11、第四透镜14以及第五透镜15具有正光焦度，第二透镜12和第三透镜13具有负光焦度。投影镜头10还包括光阑50，光阑50可以位于第二透镜12和第三透镜13之间。其中，第一透镜组1包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第五透镜15的折射率温度系数为负(dn/dt<0)。此外，第三透镜13和第四透镜14可以组合成胶合透镜组，以消除色差，缩小投影镜头10的体积，降低公差敏感度。
在本实施例中，第二透镜组2可以包括三片透镜，分别为从投影侧至像源侧排列的第六透镜21、第七透镜22以及第八透镜23，且各片透镜同轴设置。其中，第六透镜21和第七透镜22具有正光焦度，第八透镜23具有负光焦度，第八透镜23的像源侧面为凹面，投影侧面为凸面。第八透镜23具体可以是弯月透镜。第二透镜组2包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第六透镜21的折射率温度系数为负(dn/dt<0)。此外，第七透镜22和第八透镜23可以组合成胶合透镜组，以消除色差，缩小投影镜头10的体积，降低公差敏感度。
以下结合数据和光学性能的表征图，呈现图7所示投影设备100在一些实施例中的具体化方案。
请结合参阅表3和表4，表3是图7所示投影镜头10在一些实施例中的基本参数，表4是图7所示投影设备100的各透镜、偏振分光棱镜3和偏光片20的曲率半径(R)、厚度(Thickness)、折射率(Nd)、阿贝数(Vd)和焦距(f)。
表3
光圈数F# 1.3
镜头有效焦距EFL 32mm
视场角FOV 17.6°
半像高IH 4.83mm
镜头总长TTL 113mm
第一透镜组焦距f1 78.75mm
第二透镜组焦距f2 44.66mm
光学后焦BFL 9.55mm
f1/EFL 2.46
f2/EFL 1.40
TTL/EFL 3.53
BFL/EFL 0.30
表4
Figure PCTCN2023071336-appb-000002
其中，表格中各个符号的含义如下：
S1：第一透镜11的投影侧面；
S2：第一透镜11的像源侧面；
S3：第二透镜12的投影侧面；
S4：第二透镜12的像源侧面；
S5：第三透镜13的投影侧面；
S6：第三透镜13与第四透镜14胶合处的透镜面；
S7：第四透镜14的像源侧面；
S8：第五透镜15的投影侧面；
S9：第五透镜15的像源侧面；
S10：偏振分光棱镜3的投影侧面；
S11：偏振分光棱镜3的像源侧面；
S12：第六透镜21的投影侧面；
S13：第六透镜21的像源侧面；
S14：第七透镜22的投影侧面；
S15：第七透镜22与第八透镜23胶合处的透镜面；
S16：第八透镜23的像源侧面；
S17：偏光片20的投影侧面；
S18：偏光片20的像源侧面。
值得注意的是，下面以具体数值为例说明表4中用于表示曲率半径R的值的含义，对于4.62E+01，该公式中E+01代表10的一次方，因此4.62E+01的值为46.2；对于1.33E+02，该公式中E+02代表10的二次方，因此1.33E+02的值为133；对于7.98E-01，该公式中E-01代表10的负一次方，因此7.98E-01的值为0.798；对于1.00E+00，该公式中E+00代表10的0次方，因此1.00E+00的值为1.00。
请一并参阅图8至图11，图8至图11为图7所示投影镜头10的光学性能的表征图。
示例性的，图8是图7所示投影镜头10在常温下的调制传递函数曲线。图8的横坐标为空间频率，单位为线对/毫米(line pairs/mm，lp/mm)；纵坐标为光学传递函数(Optical Transfer Function，OTF)模值；其中，图8中示意出投影镜头10在常温下，于子午方向的不同位置(0.0000mm至4.8360mm)、弧矢方向的不同位置(0.0000mm至4.8360mm)的调制传递函数曲线。本实施例采用的硅基液晶芯片30的像素大小为4.3μm，对应的奈奎斯特频率为116lp/mm，全视场对应的OTF系数在0.3以上，成像质量高。
示例性的，图9是图7所示投影镜头10在-40℃温度下的调制传递函数曲线。图10是图7所示投影镜头10在150℃温度下的调制传递函数曲线。图9和图10的横坐标为空间频率，单位为线对/毫米(line pairs/mm，lp/mm)；纵坐标为光学传递函数(Optical Transfer Function，OTF)模值；其中，图9和图10中分别示意出投影镜头10在-40℃和150℃温度下，于子午方向的不同位置(0.0000mm至4.8360mm)、弧矢方向的不同位置(0.0000mm至4.8360mm)的调制传递函数曲线。从图9和图10的调制传递函数曲线可以看出，从-40℃到105℃，在116lp/mm空间频率下，其全视场对应的OTF系数均在0.3以上，可以看出本实施例的投影镜头10从-40℃到105℃实现了消热差效果，在低温以及高温下的成像变形差异较小，使得投影镜头10在较宽的温度范围内均能够满足成像清晰的要求。
示例性的，图11是图7所示投影镜头10在一些实施例中的垂轴色差曲线图，图11的纵坐标为实际像高视场值大小，单位为毫米(mm)；横坐标为衍射极限范围，单位为微米(μm)。图11显示出了波长分别为460nm、555nm、617nm、艾里斑的光经过图7所示投影镜头10后的垂轴色差。从图11中可以看出，本实施例中，投影镜头10的垂轴色差最大为2.7μm，小于硅基液晶芯片30一个像素的大小，即在4.3μm以内，因此本实施例中的投影镜头10的色差控制非常好，满足清晰投影需求。
请参阅图12，图12是图1所示投影设备100在再一些实施例中的部分结构示意图。
一些实施例中，投影设备100可以包括投影镜头10、偏光片20以及硅基液晶芯片30。投影镜头10可以包括第一透镜组1、偏振分光棱镜3以及第二透镜组2，第一透镜组1、偏振分光棱镜3以及第二透镜组2沿投影侧至像源侧依次排列。偏光片20和硅基液晶芯片30依次排布于投影镜头10的第二透镜组2的像源侧。
在本实施例中，第一透镜组1可以包括六片透镜，分别为从投影侧至像源侧排列的第一 透镜11、第二透镜12、第三透镜13、第四透镜14、第五透镜15以及第六透镜16，且各片透镜同轴设置。其中，第一透镜11、第四透镜14、第五透镜15以及第六透镜16具有正光焦度，第二透镜12和第三透镜13具有负光焦度。其中，投影镜头10还包括光阑50，光阑50可以位于第二透镜12和第三透镜13之间。其中，第一透镜组1包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第五透镜15和第六透镜16的折射率温度系数为负(dn/dt<0)。此外，第三透镜13和第四透镜14可以组合成胶合透镜组，以消除色差，缩小投影镜头10的体积，降低公差敏感度。
在本实施例中，第二透镜组2可以包括两片透镜，分别为从投影侧至像源侧排列的第七透镜22和第八透镜23，且各片透镜同轴设置。其中，第七透镜22具有正光焦度，第八透镜23具有负光焦度，第八透镜23的像源侧面为凹面，投影侧面为凸面。第八透镜23具体可以是弯月透镜。第二透镜组2包括至少一片折射率温度系数为负(dn/dt<0)的透镜，示例性的，第七透镜22的折射率温度系数为负(dn/dt<0)。
以下结合数据和光学性能的表征图，呈现图12所示投影设备100在一些实施例中的具体化方案。
请结合参阅表5和表6，表5是图12所示投影镜头10在一些实施例中的基本参数，表6是图12所示投影设备100的各透镜、偏振分光棱镜3和偏光片20的曲率半径(R)、厚度(Thickness)、折射率(Nd)、阿贝数(Vd)和焦距(f)。
表5
光圈数F# 1.3
镜头有效焦距EFL 32mm
视场角FOV 17.6°
半像高IH 4.83mm
镜头总长TTL 119mm
第一透镜组焦距f1 65.36mm
第二透镜组焦距f2 51.22mm
光学后焦BFL 10.1mm
f1/EFL 2.53
f2/EFL 1.31
TTL/EFL 3.75
BFL/EFL 0.30
表6
Figure PCTCN2023071336-appb-000003
Figure PCTCN2023071336-appb-000004
其中，表格中各个符号的含义如下：
S1：第一透镜11的投影侧面；
S2：第一透镜11的像源侧面；
S3：第二透镜12的投影侧面；
S4：第二透镜12的像源侧面；
S5：第三透镜13的投影侧面；
S6：第三透镜13与第四透镜14胶合处的透镜面；
S7：第四透镜14的像源侧面；
S8：第五透镜15的投影侧面；
S9：第五透镜15的像源侧面；
S10：第六透镜16的投影侧面；
S11：第六透镜16的像源侧面；
S12：偏振分光棱镜3的投影侧面；
S13：偏振分光棱镜3的像源侧面；
S14：第七透镜22的投影侧面；
S15：第七透镜22的像源侧面；
S16：第八透镜23的投影侧面；
S17：第八透镜23的像源侧面；
S18：偏光片20的投影侧面；
S19：偏光片20的像源侧面。
值得注意的是，下面以具体数值为例说明表6中用于表示曲率半径R的值的含义，对于4.30E+01，该公式中E+01代表10的一次方，因此4.30E+01的值为43.0；对于1.72E+02，该公式中E+02代表10的二次方，因此1.72E+02的值为172；对于1.39E-01，该公式中E-01代表10的负一次方，因此1.39E-01的值为0.139；对于2.00E+00，该公式中E+00代表10 的0次方，因此2.00E+00的值为2.00。
请一并参阅图13至图16，图13至图16为图12所示投影镜头10的光学性能的表征图。
示例性的，图13是图12所示投影镜头10在常温下的调制传递函数曲线。图13的横坐标为空间频率，单位为线对/毫米(line pairs/mm，lp/mm)；纵坐标为光学传递函数(Optical Transfer Function，OTF)模值。其中，图13中示意出投影镜头10在常温下，于子午方向的不同位置(0.0000mm至4.8360mm)、弧矢方向的不同位置(0.0000mm至4.8360mm)的调制传递函数曲线。本实施例采用的硅基液晶芯片30的像素大小为4.3μm，对应的奈奎斯特频率为116lp/mm下，全视场对应的OTF系数在0.4以上，成像质量高。
示例性的，图14是图12所示投影镜头10在-40℃温度下的调制传递函数曲线。图15是图12所示投影镜头10在150℃温度下的调制传递函数曲线。图14和图15的横坐标为空间频率，单位为线对/毫米(line pairs/mm，lp/mm)；纵坐标为光学传递函数(Optical Transfer Function，OTF)模值；其中，图14和图15中分别示意出投影镜头10在-40℃和150℃温度下，于子午方向的不同位置(0.0000mm至4.8360mm)、弧矢方向的不同位置(0.0000mm至4.8360mm)的调制传递函数曲线。从图14和图15的调制传递函数曲线可以看出，从-40℃到105℃，在116lp/mm空间频率下，其全视场对应的OTF系数均在0.3以上，可以看出本实施例的投影镜头10从-40℃到105℃实现了消热差效果，在低温以及高温下的成像变形差异较小，使得投影镜头10在较宽的温度范围内均能够满足成像清晰的要求。
示例性的，图16是图12所示投影镜头10在一些实施例中的垂轴色差曲线图，图16的纵坐标为实际像高视场值大小，单位为毫米(mm)；横坐标为衍射极限范围，单位为微米(μm)。图16显示出了波长分别为460nm、555nm、617nm、艾里斑的光经过本实施例的投影镜头10后的垂轴色差。从图16中可以看出，本实施例中，垂轴色差最大为4μm，小于硅基液晶芯片30一个像素的大小，即在4.3μm以内，因此本实施例的投影镜头10的色差控制非常好，满足清晰投影需求。
在本申请实施例中，可以通过对投影镜头10的第一透镜组1、偏振分光棱镜3及第二透镜组2的位置设置，配合第一透镜组1和第二透镜组2的光焦度和焦距的设置，并且可以通过对第一透镜组1和第二透镜组2中各透镜的焦距、折射率温度系数、厚度、折射率以及阿贝数的合理搭配，另外结合投影镜头10在光圈、焦距、以及光学总长等方面的共同配合，实现投影镜头10的光传输效率高，投影亮度高，清晰度度高，大光圈，小体积，并且投影镜头10在-40℃至105℃的应用环境中，光学与结构相互补偿的消热差设计，使得投影镜头10在常温对焦后，无需再次对焦，从而可以保持投影镜头10在不同温度下清晰投影成像，使得投影设备100投影成像质量高，性能稳定，对环境适应性强。
请参阅图17，图17是本实施例提供的另一种投影设备100的模块示意图。
一些实施例中，投影设备100可以包括投影镜头10、光源40、第一偏光片20、第一像源、第二偏光片60以及第二像源。示例性的，投影设备100的第一像源可以为第一硅基液晶芯片30，投影设备100的第二像源可以为第二硅基液晶芯片70，第一硅基液晶芯片30和第二硅基液晶芯片70用于输出投影图像。投影设备100具有投影侧，投影侧为靠近投影设备100投射出的影像的一侧。
其中，偏振分光棱镜3包括相邻的第一像源侧和第二像源侧，第一像源侧为靠近第一硅基液晶芯片30的一侧，第二像源侧为靠近第二硅基液晶芯片70的一侧。
在本实施例中，投影镜头10可以包括第一透镜组1、偏振分光棱镜3、第二透镜组2以及第三透镜组4。第二透镜组2位于偏振分光棱镜3的第一像源侧，第一透镜组1、偏振分光 棱镜3以及第二透镜组2沿投影侧至第一像源侧依次排列，第二透镜组2的光轴与第一透镜组1的光轴平行设置，第一偏光片20和第一硅基液晶芯片30排布于第二透镜组2的第一像源侧，第一偏光片20较第一硅基液晶芯片30靠近投影镜头10。第三透镜组4位于偏振分光棱镜3的第二像源侧，第三透镜组4的光轴与第一透镜组1的光轴垂直设置，第二偏光片60和第二硅基液晶芯片70排布于第三透镜组4的第二像源侧，第二偏光片60较第二硅基液晶芯片70靠近投影镜头10。其中，光源40位于投影镜头10的偏振分光棱镜3的入光侧，偏振分光棱镜3的入光侧用于接收入射光线。光源40可以为发光二极管(light-emitting diode，LED)光源或激光光源，光源40也可以为其他种类的光源，本申请对此不做严格限定。
在本实施例中，光源40的发射光线从偏振分光棱镜3的入光侧进入偏振分光棱镜3，偏振分光棱镜3将发射光线分为两路偏振光，其中一路偏振光自偏振分光棱镜3的第一像源侧射出，依次通过第二透镜组2和第一偏光片20，照射到第一硅基液晶芯片30，第一硅基液晶芯片30可以根据投影图案，调整光的偏振态，投射出投影光线，投影光线依次通过第一偏光片20、第二透镜组2、偏振分光棱镜3以及第一透镜组1，最终将图像投影到投影面上。另一路偏振光自偏振分光棱镜3的第二像源侧射出，依次通过第三透镜组4和第二偏光片60，照射到第二硅基液晶芯片70，第二硅基液晶芯片70可以根据投影图案，调整光的偏振态，投射出投影光线，投影光线依次通过第二偏光片60、第三透镜组4、偏振分光棱镜3以及第一透镜组1，最终将图像投影到投影面上。
在本实施例中，光源40的发射光线被偏振分光棱镜3分为两路偏振光，第二透镜组2、第一偏光片20以及第一硅基液晶芯片30能够利用一路偏振光进行投影，而第三透镜组4、第二偏光片60以及第二硅基液晶芯片70能够利用另一路偏振光进行投影，使得投影镜头10对光源40的发射光线的利用率较高，相较于利用一路偏振光投影的方案，光线利用率可以达到2倍或将近2倍。本实施例中第三透镜组4、第二偏光片60以及第二硅基液晶芯片70的设置，不仅提高了投影设备100对光线的利用率和光传输效率，而且提高了投影设备100的投影亮度和最终投影成像的质量。
示例性的，第一透镜组1、第二透镜组2的相关设计可以参考前文实施例，此处不再赘述。
在一些实施例中，第一硅基液晶芯片30输出的图像可以与第二硅基液晶芯片70输出的图像相同，投影设备100最终输出的图像为第一硅基液晶芯片30和第二硅基液晶芯片70输出图像的叠加图像，投影亮度更高，从而增强投影设备100最终输出图像的效果。其中，第三透镜组4中各透镜的设置可以与第二透镜组2相同，并且第三透镜组4至偏振分光棱镜3之间的距离可以与第二透镜组2至偏振分光棱镜3之间的距离相等。
在另一些实施例中，第一硅基液晶芯片30可以输出一部分图像，第二硅基液晶芯片70可以输出另一部分图像，第一硅基液晶芯片30输出的图像与第二硅基液晶芯片70输出的图像共同组成投影设备100最终输出的完整图像，以提高投影质量。其中，第三透镜组4中各透镜的设置可以与第二透镜组2不同，第三透镜组4至偏振分光棱镜3之间的距离可以与第二透镜组2至偏振分光棱镜3之间的距离不相等。本申请中不对第一硅基液晶芯片30和第二硅基液晶芯片70输出的图像做严格的限制。
以上实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (19)

  1. 一种投影镜头，其特征在于，包括沿投影侧至像源侧依次排列的第一透镜组、偏振分光棱镜及第二透镜组，所述第二透镜组具有正光焦度。
  2. 根据权利要求1所述的投影镜头，其特征在于，所述第二透镜组的焦距f2与所述投影镜头的焦距EFL满足：1.8≥f2/EFL≥1。
  3. 根据权利要求2所述的投影镜头，其特征在于，所述第一透镜组的焦距f1与所述投影镜头的焦距EFL满足：f1/EFL≥2。
  4. 根据权利要求1至3中任一项所述的投影镜头，其特征在于，所述第一透镜组包括三至六片透镜，所述第二透镜组包括二至三片透镜。
  5. 根据权利要求4所述的投影镜头，其特征在于，所述第一透镜组包括从投影侧至像源侧排列的第一透镜、第二透镜、第三透镜、第四透镜、第五透镜，所述第一透镜、所述第五透镜具有正光焦度，所述第二透镜、所述第三透镜及所述第四透镜中的一片透镜具有正光焦度，另外两片透镜具有负光焦度；
    所述第二透镜组包括从投影侧至像源侧排列的第六透镜和第七透镜，所述第六透镜具有正光焦度，所述第七透镜具有负光焦度。
  6. 根据权利要求5所述的投影镜头，其特征在于，所述第四透镜具有正光焦度，所述第二透镜和所述第三透镜具有负光焦度。
  7. 根据权利要求4所述的投影镜头，其特征在于，所述第一透镜组包括从投影侧至像源侧排列的第一透镜、第二透镜、第三透镜、第四透镜、第五透镜，所述第一透镜、所述第四透镜及所述第五透镜具有正光焦度，所述第二透镜和所述第三透镜具有负光焦度；
    所述第二透镜组包括从投影侧至像源侧排列的第六透镜、第七透镜及第八透镜，所述第六透镜和所述第七透镜具有正光焦度，所述第八透镜具有负光焦度。
  8. 根据权利要求4所述的投影镜头，其特征在于，所述第一透镜组包括从投影侧至像源侧排列的第一透镜、第二透镜、第三透镜、第四透镜、第五透镜、第六透镜，所述第一透镜、所述第四透镜、所述第五透镜及所述第六透镜具有正光焦度，所述第二透镜和所述第三透镜具有负光焦度；
    所述第二透镜组包括从投影侧至像源侧排列的第七透镜和第八透镜，所述第七透镜具有正光焦度，所述第八透镜具有负光焦度。
  9. 根据权利要求5至8中任一项所述的投影镜头，其特征在于，所述第三透镜和所述第四透镜组合成胶合透镜组。
  10. 根据权利要求1至9中任一项所述的投影镜头，其特征在于，所述第一透镜组能够沿所述投影镜头的光轴方向移动。
  11. 根据权利要求1至10中任一项所述的投影镜头，其特征在于，所述投影镜头的光学总长TTL与所述投影镜头的焦距EFL满足：4.5≥TTL/EFL≥2.5。
  12. 根据权利要求1至11中任一项所述的投影镜头，其特征在于，所述投影镜头的光学后焦BFL与所述投影镜头的焦距EFL满足：BFL/EFL≤0.5。
  13. 根据权利要求1至12中任一项所述的投影镜头，其特征在于，所述第一透镜组包括至少一片折射率温度系数为负(dn/dt<0)的透镜，所述第二透镜组包括至少一片折射率温度系数为负(dn/dt<0)的透镜。
  14. 根据权利要求1至13中任一项所述的投影镜头，其特征在于，所述投影镜头还包括 光阑，所述光阑位于所述第一透镜组，或者位于所述第一透镜组与所述偏振分光棱镜之间。
  15. 根据权利要求1至14中任一项所述的投影镜头，其特征在于，所述偏振分光棱镜包括相邻的第一像源侧和第二像源侧，所述第二透镜组位于所述偏振分光棱镜的第一像源侧；
    所述投影镜头还包括第三透镜组，所述第三透镜组位于所述偏振分光棱镜的第二像源侧。
  16. 一种投影设备，其特征在于，包括光源、偏光片、像源及权利要求1至14中任一项所述的投影镜头，所述光源位于所述投影镜头的偏振分光棱镜的入光侧，所述偏光片和所述像源排布于所述投影镜头的第二透镜组的像源侧，所述偏光片较所述像源靠近所述投影镜头。
  17. 根据权利要求16所述的投影设备，其特征在于，所述像源包括硅基液晶芯片。
  18. 一种投影设备，其特征在于，包括光源、第一偏光片、第二偏光片、第一像源、第二像源及权利要求15所述的投影镜头，所述光源位于所述投影镜头的偏振分光棱镜的入光侧，所述第一偏光片和所述第一像源排布于所述投影镜头的所述第二透镜组的第一像源侧，所述第一偏光片较所述第一像源靠近所述投影镜头；
    所述第二偏光片和所述第二像源排布于所述投影镜头的所述第三透镜组的第二像源侧，所述第二偏光片较所述第二像源靠近所述投影镜头。
  19. 一种车辆，其特征在于，包括前大灯，所述前大灯包括权利要求16至18中任一项所述的投影设备。
PCT/CN2023/071336 2022-01-27 2023-01-09 投影镜头、投影设备及车辆 WO2023143008A1 (zh)

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CN1866076A (zh) * 2005-05-16 2006-11-22 中强光电股份有限公司 光学投影装置
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