WO2023273441A1 - Système optique de projection - Google Patents

Système optique de projection Download PDF

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Publication number
WO2023273441A1
WO2023273441A1 PCT/CN2022/083349 CN2022083349W WO2023273441A1 WO 2023273441 A1 WO2023273441 A1 WO 2023273441A1 CN 2022083349 W CN2022083349 W CN 2022083349W WO 2023273441 A1 WO2023273441 A1 WO 2023273441A1
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WO
WIPO (PCT)
Prior art keywords
lens
lens group
optical system
projection optical
group
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PCT/CN2022/083349
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English (en)
Chinese (zh)
Inventor
陈怡学
伍俊东
杨峰
葛睿
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成都极米科技股份有限公司
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Publication of WO2023273441A1 publication Critical patent/WO2023273441A1/fr

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    • 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
    • G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
    • 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

Definitions

  • the invention relates to the technical field of optical lenses, in particular to a projection optical system.
  • the zoom lens can obtain images of different sizes through continuous zoom without changing the working distance, and the zoom lens will be more and more used.
  • the optical system used for projection In order to meet the needs of the current situation, for the optical system used for projection, it tends to design a lens with a larger diameter to effectively obtain more light, which can make the projection screen obtain higher brightness.
  • the Fno design value of the projection lens is F1.7, and there are the following difficulties in designing a larger-diameter lens: the correction of system off-axis aberration and distortion correction, and the design of a high-performance MTF zoom lens usually has a large structure and is relatively difficult to use. The number of lenses is large, so the structure of the lens becomes complicated and the cost is higher.
  • the object of the present invention is to provide a projection optical system, which can effectively improve system aberration and suppress system distortion, and can meet the requirements of simple structure, small size, low cost and large aperture.
  • the present invention provides the following technical solutions:
  • a projection optical system comprising a first lens group, a second lens group, a third lens group, a fourth lens group and a fifth lens group arranged sequentially from the enlargement side to the reduction side, the first lens group is used to adjust focus, the second lens group, the third lens group and the fourth lens group are used for zooming, and the diaphragm is located between the third lens group and the fourth lens group;
  • the first lens group includes a first lens, the first lens is closest to the magnification side in the first lens group, at least one surface of which is aspherical, and the fourth lens group includes a fifth lens, the The fifth lens is closest to the magnification side in the fourth lens group, and at least one surface thereof is aspherical.
  • the fourth lens group includes a first cemented lens
  • the first cemented lens at least includes a lens with a first refractive index and a lens with a second refractive index, and the first refractive index is greater than the second refractive index.
  • the third lens group is used to converge light.
  • the second lens group includes a third lens with positive diopter
  • the third lens group includes a fourth lens with positive diopter.
  • the fourth lens group includes a fifth lens with positive diopter, a sixth lens that is a biconcave lens, a seventh lens that is a biconvex lens, and an eighth lens that is a concave-convex lens, the sixth lens, the The seventh lens is cemented with the eighth lens.
  • the fifth lens group includes a second cemented lens, an eleventh lens and a twelfth lens, the eleventh lens is a plano-convex lens or a convex lens, and the twelfth lens is a plano-convex lens or a convex lens, or
  • the fifth lens group includes a second cemented lens and at least one lens whose surface is aspherical.
  • the diaphragm can move along with the fourth lens group along the optical axis and the relative position of the diaphragm to the fourth lens group is fixed.
  • the second lens group moves to the reduction side
  • the third lens group and the fourth lens group move to the magnification side
  • FNOw ⁇ 1.45, FNOt ⁇ 1.62, FNOt and FNOw represent the relative aperture numbers of the projection optical system at the telephoto end and the wide-angle end, respectively.
  • EFLt/EFLw 1.25, TAw ⁇ 1.19°, TAt ⁇ 1.77°
  • EFLt and EFLw represent the effective focal lengths of the projection optical system at the telephoto end and wide-angle end respectively
  • TAt and Taw respectively Indicates the telecentric angle of the projection optical system at the telephoto end and wide-angle end.
  • the first lens group is used for focusing
  • the second lens group, the third lens group and the fourth lens group are used for zooming
  • the diaphragm is located in the third lens group. and the fourth lens group.
  • At least one surface of the first lens of the first lens group is aspherical. It is beneficial to improve the field of view of the optical system and better correct off-axis aberrations and distortions.
  • At least one surface of the fifth lens included in the fourth lens group is aspherical.
  • An aspheric lens is arranged behind the diaphragm, which can well correct the aberration of the optical system and improve the MTF performance.
  • the projection optical system can meet the requirements of large aperture, simple structure, miniaturization and low cost by optimizing the number of lenses in each lens group, the surface shape of each lens and the optical parameters of the lens, and can effectively improve the performance of the system. Aberrations and distortions in the suppression system occur.
  • FIG. 1 is a schematic diagram of a projection optical system at the wide-angle end provided by an embodiment of the present invention
  • FIG. 2 is a schematic diagram of a projection optical system at a telephoto end provided by an embodiment of the present invention.
  • This embodiment provides a projection optical system, including a first lens group, a second lens group, a third lens group, a fourth lens group and a fifth lens group arranged in sequence from the magnification side to the reduction side, the first lens The group is used for focusing, the second lens group, the third lens group and the fourth lens group are used for zooming, and the diaphragm is located between the third lens group and the fourth lens group;
  • the first lens group includes a first lens, the first lens is closest to the magnification side in the first lens group, at least one surface of which is aspherical, and the fourth lens group includes a fifth lens, the The fifth lens is closest to the magnification side in the fourth lens group, and at least one surface thereof is aspherical.
  • the enlarged side refers to the side where the screen is located
  • the reduced side refers to the side where the image source is located.
  • the image source emits light, passes through each lens group in turn, and projects onto the screen, projecting an image on the screen.
  • the second lens group, the third lens group and the fourth lens group are used for zooming
  • the first lens group is used for focusing, so that a clear image is projected on the screen.
  • the first lens included in the first lens group is closest to the magnification side in the first lens group, at least one surface of which is aspherical, which is beneficial to improve the field of view of the optical system, and can be better corrected by rationally optimizing the aspheric coefficient Off-axis aberration and distortion, as well as the requirements that can effectively guarantee the long working distance of the projection optical system.
  • the fifth lens closest to the magnification side in the fourth lens group that is, the fifth lens is adjacent to the diaphragm, at least one surface of which is an aspheric surface, and an aspheric lens is arranged behind the diaphragm, which can well correct the aberration of the optical system. MTF performance. Therefore, the projection optical system can effectively correct aberrations and suppress distortions, obtain good imaging quality, reduce the number of lenses used, and make the system structure simple and miniaturized.
  • the projection optical system of this embodiment can meet the requirements of large aperture, simple structure, miniaturization and low cost by optimizing the number of lenses in each lens group, the surface shape of each lens, and the optical parameters of the lens, and can effectively Improve system aberration and suppress system distortion.
  • the fourth lens group includes a first cemented lens
  • the first cemented lens at least includes a lens with a first refractive index and a lens with a second refractive index, and the first refractive index is greater than the second refractive index.
  • the lens can be made of low-dispersion negative expansion coefficient material, which can compensate the temperature drift of the entire optical system while ensuring a small chromatic aberration of the entire optical system.
  • the third lens group is used to converge the light
  • the diaphragm is located between the third lens group and the fourth lens group, and the third lens group can converge the incoming light to the diaphragm, so that the optical system can have the same clear aperture Reduce the size of the aperture and reduce the volume of the system structure. Therefore, the projection optical system can obtain an image picture with higher brightness, and the system structure can be miniaturized.
  • the third lens group can have a positive diopter and can converge light rays.
  • the third lens group may include any one or a combination of convex lenses or plano-convex lenses.
  • the structure of the third lens group can be designed according to the application requirements. It is preferable that the third lens group use a small number of lenses when a better imaging effect can be achieved, which is helpful for system miniaturization.
  • the projection optical system of this embodiment realizes zooming by moving the second lens group, the third lens group and the fourth lens group along the optical axis respectively, wherein the diaphragm can move along the optical axis with the fourth lens group , and the relative position of the diaphragm and the fourth lens group is fixed.
  • the projection optical system can keep the position of the imaging plane unchanged during the zooming process, and the position of the imaging plane can be maintained without moving the first lens group along the optical axis, that is, there is no need to adjust the first lens group
  • the projected image screen can be kept clear all the time.
  • the position of the fifth lens group does not change during the zooming process of the projection optical system.
  • the second lens group moves to the reduction side, and the third lens group and the fourth lens group move to the magnification side.
  • the projection optical system at the wide-angle end means that each lens group of the projection optical system is at the position where the field of view of the projection optical system is maximized.
  • the projection optical system is at the telephoto end. maximum location.
  • the aperture of the aperture in the projection optical system of this embodiment can be changed, and the size of the aperture of the aperture can be adjusted according to application scenarios, so as to realize a dynamic aperture effect to adapt to more application scenarios.
  • the aperture can be adjusted to the maximum.
  • the aperture can be appropriately reduced.
  • the diopters of the first lens group and the fifth lens group are negative and positive in sequence, and the total diopter of the second lens group, the third lens group and the fourth lens group is positive.
  • FIG. 1 is a schematic diagram of a projection optical system provided by this embodiment at a wide-angle end
  • FIG. 2 is a schematic diagram of a projection optical system provided by this embodiment at a telephoto end.
  • the projection optical system includes a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4 and a fifth lens group G5.
  • the first lens group G1 includes a first lens L1 and a second lens L2 that is a biconcave lens.
  • the first lens L1 is an aspheric lens, and its surfaces facing the enlargement side and the reduction side may both be even-order aspheric surfaces.
  • the curvature radii of both surfaces of the second lens L2 are the same.
  • the diopters of the first lens L1 and the second lens L2 are negative and negative in sequence.
  • the first lens L1 can be made of resin material.
  • the second lens group G2 includes a third lens L3 which is a biconvex lens.
  • the diopter of the third lens L3 is positive.
  • the curvature radii of the two surfaces of the third lens L3 can be designed to be the same.
  • the diopter of the third lens group G3 is positive, and setting it at the front end of the diaphragm ST can effectively gather light and reduce the opening diameter of the diaphragm.
  • the third lens group G3 may include a fourth lens L4, and the fourth lens L4 is a plano-convex lens, which can cause negative distortion and correct the distortion of the front lens group.
  • the fourth lens group G4 includes a fifth lens L5 with positive diopter, a sixth lens L6 that is a biconcave lens, a seventh lens L7 that is a biconvex lens, and an eighth lens L8 that is a concave-convex lens, the sixth lens L6, the seventh lens L7 and the eighth lens L8 are glued together, and the composite focal length is negative, and the diopters of each lens are negative, positive and negative in sequence.
  • the fifth lens L5 is an aspherical lens, and the surfaces facing the enlargement side and the reduction side may both be even-order aspheric surfaces.
  • the sixth lens L6 is made of a material with a high refractive index
  • the seventh lens L7 or the eighth lens L8 is made of a material with a low refractive index
  • the eighth lens L8 can be made of a material with a low dispersion coefficient and a negative expansion coefficient, which can compensate thermal defocus of the optical system.
  • the curvature radii of both surfaces of the sixth lens L6 are the same.
  • the fifth lens L5 can be a glass lens.
  • the fifth lens group G5 includes a second cemented lens, an eleventh lens L11 and a twelfth lens L12, the eleventh lens L11 is a plano-convex lens or a convex lens, and the twelfth lens L12 is a plano-convex lens or a convex lens. Both the eleventh lens L11 and the twelfth lens L12 in the optical system shown in FIG. 1 are plano-convex lenses with positive diopters.
  • the fifth lens group G5 may include a second cemented lens and at least one surface of an aspherical lens, and the use of an aspheric lens can reduce the number of lenses used.
  • the second cemented lens includes a ninth lens L9 that is a biconcave lens and a tenth lens L10 that is a biconvex lens, and the diopters are negative and positive in sequence.
  • the tenth lens L10 is made of a material with a low dispersion coefficient and a negative expansion coefficient, which can compensate thermal defocus of the optical system.
  • the curvature radii of the two surfaces of the second lens L2 , the third lens L3 and the sixth lens L6 are respectively the same, which can reduce the cost and simplify the production and assembly process.
  • One of the surfaces of the fourth lens L4, the tenth lens L10 and the eleventh lens L11 is designed to be flat, which can effectively reduce the mold cost required for lens production.
  • the projection optical system of this embodiment satisfies the following conditional formula: FNOw ⁇ 1.45, FNOt ⁇ 1.62, FNOt, FNOw represent the relative aperture numbers of the projection optical system at the telephoto end and wide-angle end, respectively.
  • the projection optical system of this embodiment also satisfies the following conditional formula: EFLt/EFLw ⁇ 1.25, TAw ⁇ 1.19°, TAt ⁇ 1.77°, wherein EFLt and EFLw respectively represent the effective focal lengths of the projection optical system at the telephoto end and the wide-angle end , TAt, Taw represent the telecentric angles of the projection optical system at the telephoto end and the wide-angle end, respectively.
  • TTLw/EFLw ⁇ 10.51 where TTLw represents the total lens length of the projection optical system at the wide-angle end, and EFLw represents the effective focal length of the projection optical system at the wide-angle end.
  • the total lens length is defined as the distance from the vertex of the lens surface closest to the magnification side of the optical system to the image plane of the image source on the reduction side.
  • BFL/EFLw>2.37 wherein BFL represents the back focal length of the projection optical system, and EFLw represents the effective focal length of the projection optical system at the wide-angle end.
  • the Fno of the projection optical system is 1.45 ⁇ 3.34, the telecentric angle TA of the system is 1.19 ⁇ 1.77°, and the 0.47-inch digital micromirror device (Digital Micromirror Device, DMD) chip can project a 228.6cm (90-inch ) screen, forming a screen with a diagonal of 72 inches at the telephoto end.
  • DMD Digital Micromirror Device
  • the projection optical system can achieve a distortion of less than 0.3%, a focal length of 12.56-15.704 mm continuous zoom, and can ensure a good resolution capability at a spatial frequency of 93 lp/mm.
  • optical design software is used to repeatedly optimize the optical design of the curvature radius, material, thickness, air gap and aspheric lens of each lens, which can achieve small aberration, high resolution, simple structure, ingenious design, and It has high manufacturing mass productivity and is convenient for mass production.
  • the projection system can place the digital micromirror element chip 100 in an offset manner, that is, the central axis of the digital micromirror element chip 100 deviates from the optical axis of the lens, so as to ensure that the projected image screen is biased upwards during the projection operation, and the output beam is realized. Higher than the position of the projection lens, the projection screen will not be blocked by the lens.
  • the prism 101 is used to guide the light emitted by the digital micromirror element chip 100 to enter the lens.
  • the projection optical system may further include a drive motor connected to the diaphragm, used to drive the diaphragm blades to adjust the aperture size of the diaphragm, so as to adapt to work in different scenarios.
  • a drive motor connected to the diaphragm, used to drive the diaphragm blades to adjust the aperture size of the diaphragm, so as to adapt to work in different scenarios.
  • the projection optical system can also be provided with a shaking vibrating mirror 102, so that the lens can simultaneously obtain the inherent resolution of the digital micromirror element chip 100 when the vibrating mirror is stationary and the high resolution when the vibrating mirror is working and shaking.
  • the following table 1 shows the detailed optical data of the projection optical system of a specific example.
  • z represents the distance vector from the apex of the aspheric surface when the aspheric surface is at the position of height r along the optical axis
  • c represents the radius of curvature of the apex of the aspheric surface
  • k represents the conic coefficient
  • ⁇ 1 to 8 represent two to sixteen The aspheric coefficients corresponding to the order.
  • Table 2 below shows the aspheric coefficients of the surfaces S1 and S2 of the first lens L1 and the surfaces S10 and S11 of the fifth lens L5.
  • Table 3 shows the distance corresponding to the projection optical system at the wide-angle end and the telephoto end:

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)

Abstract

L'invention concerne un système optique de projection qui comprend un premier groupe de lentilles (G1) étant utilisé pour la focalisation ; un second groupe de lentilles (G2), un troisième groupe de lentilles (G3), et un quatrième groupe de lentilles (G4) étant utilisés pour effectuer un zoom ; un diaphragme (ST) étant situé entre le troisième groupe de lentilles (G3) et le quatrième groupe de lentilles (G4) ; au moins une surface d'une première lentille (L1) comprise dans le premier groupe de lentilles (G1) est asphérique, ce qui aide à améliorer le champ de vision du système optique et mieux corriger les aberrations et les distorsions hors axe ; et au moins une surface d'une cinquième lentille (L5) comprise dans le quatrième groupe de lentilles (G4) est asphérique, et une lentille asphérique est disposée derrière le diaphragme (ST), ce qui peut bien corriger des aberrations de système optique pour améliorer les performances MTF. Grâce à l'optimisation de la conception du nombre de lentilles de chaque groupe de lentilles, la forme de surface de chaque lentille, et des paramètres optiques des lentilles, le présent système optique de projection peut satisfaire aux exigences d'une grande ouverture, d'une structure simple et miniaturisée et de faibles coûts, et peut améliorer efficacement les aberrations du système et supprimer l'apparition de distorsions du système.
PCT/CN2022/083349 2021-06-29 2022-03-28 Système optique de projection WO2023273441A1 (fr)

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CN113253414B (zh) * 2021-06-29 2021-09-28 成都极米科技股份有限公司 一种投影光学系统
CN113341550B (zh) * 2021-07-29 2021-11-09 成都极米科技股份有限公司 一种应用于投影的变焦镜头
CN116594147B (zh) * 2023-03-20 2024-03-29 宜宾市极米光电有限公司 投影镜头及投影设备

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