Zoom projection lens, projection system and projection device

Abstract

This application discloses a zoom projection lens, a projection system, and a projection device. The zoom projection lens includes a first lens group with negative optical power, a second lens group with positive optical power, an aperture stop, a third lens group with positive optical power, and a fourth lens group with positive optical power. The first lens group includes a first lens, a second lens, and a third lens with negative, negative, and positive diopters, respectively. The second lens group includes a fourth lens with positive diopter. The third lens group includes a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens with negative, positive, negative, positive, and positive diopters, respectively. The fourth lens group includes a tenth lens with positive diopter. The first lens group is used for focusing, and the second and third lens groups are movable along the optical axis. The second lens group is a zoom group, the third lens group is a zoom compensation group, and the fourth lens group is a fixed group. This application can improve the performance of the zoom projection lens.

Description

Technical Field

[0001] This application relates to the field of projection imaging, and more particularly to a zoom projection lens, a projection system, and a projection device. Background Technology

[0002] As projection modules are increasingly widely used in various fields, fixed-focus lenses, limited by their single and fixed field of view, cannot change the size of the projected image without altering the projection distance. This presents some inconveniences and limits their application scenarios. Zoom lenses, on the other hand, can achieve different projected image sizes through continuous zoom without changing the working distance. Current zoom lenses are developing towards larger fields of view and relative apertures, higher magnification, smaller size, and clearer images, making them a hot topic in zoom optical system design.

[0003] Current demands for smaller projection devices necessitate more compact designs and smaller dimensions for zoom projection lenses. This presents certain challenges to the performance of zoom projection lenses, and the performance of existing lenses needs improvement. Summary of the Invention

[0004] This application provides a zoom projection lens, a projection system, and a projection device, which can improve the performance of the zoom projection lens.

[0005] An embodiment of the first aspect of this application provides a zoom projection lens, which includes, along the optical axis from the magnification side to the reduction side, a first lens group with negative optical power, a second lens group with positive optical power, an aperture stop, a third lens group with positive optical power, and a fourth lens group with positive optical power. The first lens group includes, along the optical axis from the magnification side to the reduction side, a first lens, a second lens, and a third lens with refractive powers of negative, negative, and positive, respectively. The second lens group includes a fourth lens with positive refractive power. The third lens group includes, along the optical axis from the magnification side to the reduction side, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens with refractive powers of negative, positive, negative, positive, and positive, respectively. The fourth lens group includes a tenth lens with positive refractive power. The first lens group is used for focusing, and the second and third lens groups are both movable along the optical axis. The second lens group is a zoom group, the third lens group is a zoom compensation group, and the fourth lens group is a fixed group.

[0006] According to an embodiment of the first aspect of this application, the back focal length of the zoom projection lens is BFL, the total optical length of the zoom projection lens at the wide-angle end is TTLw, the effective focal length of the zoom projection lens at the wide-angle end is EFLw, and the effective focal length of the zoom projection lens at the telephoto end is EFLt. The zoom projection lens satisfies at least one of the following conditions: 0.15≤BFL / TTLw≤1.0; 5.3≤TTLw / EFLw≤11.5; 5.3≤TTLw / EFLt≤8.8; 1.5≤BFL / EFLw≤3.

[0007] According to any of the foregoing embodiments of the first aspect of this application, the zoom ratio of the zoom projection lens is 1.0≤EFLt / EFLw≤3.

[0008] According to any of the foregoing embodiments of the first aspect of this application, the aperture number of the zoom projection lens is Fno, and the zoom projection lens satisfies: 2mm≤EFLw / Fno≤8mm; and / or, 4mm≤EFLt / Fno≤12mm.

[0009] According to any of the foregoing embodiments of the first aspect of this application, the unidirectional movement distance of the second lens group is d2, the unidirectional movement distance of the third lens group is d3, and the zoom projection lens satisfies: 0.05≤d2 / TTLw≤0.2; and / or, 0.02≤d3 / TTLw≤0.1.

[0010] According to any of the foregoing embodiments of the first aspect of this application, the diameter of the image plane circle of the zoom projection lens is D, and the zoom projection lens satisfies the following conditions: 4≤TTLw / D≤9; and / or, 0.5≤EFLw / D≤1.5.

[0011] According to any of the foregoing embodiments of the first aspect of this application, the maximum telecentric angle of each focal length of the zoom projection lens is TAmax, where TAmax ≤ 1.5°.

[0012] According to any of the foregoing embodiments of the first aspect of this application, the focal length of the first lens group is fg1, the focal length of the second lens group is fg2, the focal length of the third lens group is fg3, and the focal length of the fourth lens group is fg4. The zoom projection lens satisfies at least one of the following conditions: -4.3 < fg1 / EFLw < -1.7; 2.2 < fg2 / EFLw < 5.2; 5.1 < fg3 / EFLw < 8.2; 1.6 < fg4 / EFLw < 6.2; -60mm ≤ fg1 ≤ -10mm; 16mm ≤ fg2 ≤ 70mm; 30mm ≤ fg3 ≤ 100mm; 20mm ≤ fg2 ≤ 80mm.

[0013] According to any of the foregoing embodiments of the first aspect of this application, the combined focal length of the third lens group and the fourth lens group is f34, and the distance between the aperture stop and the farthest lens in the fourth lens group near the reduced side surface along the optical axis is T2, wherein 0.4≤f34 / T2≤1.3.

[0014] According to any of the foregoing embodiments of the first aspect of this application, the sixth lens, the seventh lens, and the eighth lens constitute a cemented triplet lens group. The refractive index of the sixth lens is nd1, and the Abbe number is Vd1. The refractive index of the seventh lens is nd2, and the Abbe number is Vd2. The refractive index of the eighth lens is nd3, and the Abbe number is Vd3. Wherein, nd1 < nd2, nd3 < nd2, and Vd1 > Vd2, Vd3 > Vd2.

[0015] According to any of the foregoing embodiments of the first aspect of this application, the eighth lens satisfies at least one of the following conditions: 1.43≤nd3≤1.55; 70≤Vd3≤95; the refractive index temperature coefficient dn / dt of the eighth lens is <0.

[0016] According to any of the foregoing embodiments of the first aspect of this application, the first lens satisfies at least one of the following conditions: 1.45≤nd≤1.65; 60≤Vd≤82; the first lens is an aspherical lens; wherein, nd is the refractive index of the lens, and Vd is the Abbe number of the lens.

[0017] According to any of the foregoing embodiments of the first aspect of this application, the second lens is a biconcave lens; and / or, the third lens is a biconvex lens; and / or, the surface of the fourth lens near the magnification side is convex, and the surface of the fourth lens near the reduction side is concave; and / or, the surface of the fifth lens near the magnification side is convex, and the surface of the fifth lens near the reduction side is concave; and / or, the sixth lens is a biconvex lens; and / or, the seventh lens is a biconcave lens; and / or, the eighth lens is a biconvex lens; and / or, the ninth lens is a biconvex lens; and / or, the surface of the tenth lens near the magnification side is convex, and the surface of the tenth lens near the reduction side is planar.

[0018] According to any of the foregoing embodiments of the first aspect of this application, the aperture number of the zoom projection lens is Fno, the outer diameter of the largest lens in the zoom projection lens is Lmax, and the zoom projection lens satisfies at least one of the following conditions: 8mm≤Lmax / Fno≤22mm; 1.5≤Fno≤3; and all lenses of the zoom projection lens are glass lenses.

[0019] According to any of the foregoing embodiments of the first aspect of this application, the zoom projection lens satisfies at least one of the following conditions: the first lens group includes at least one aspherical lens; the second lens group includes at least one lens with a refractive index greater than 1.7; the third lens group includes at least one lens with a refractive index greater than 1.7; the third lens group includes at least one lens with an Abbe number greater than 75; the third lens group includes at least one lens with a refractive index temperature coefficient dn / dt to focal length fn ratio (dn / dt) / fn < 0; the third lens group includes at least one set of cemented lenses, the cemented lenses include one lens with an Abbe number greater than 70, and the refractive index temperature coefficient Dn / Dt of at least one lens in the cemented lenses is ≤ -6; the fourth lens group includes at least one lens with a refractive index greater than 1.9.

[0020] According to any of the foregoing embodiments of the first aspect of this application, during the zooming process from the wide-angle end to the telephoto end, both the second lens group and the third lens group move towards the magnification side; and / or, the aperture stop moves synchronously with the third lens group.

[0021] According to any of the foregoing embodiments of the first aspect of this application, the zoom projection lens further includes a beam splitting structure and a light valve. The light valve is disposed on the side of the fourth lens group near the reduction side, and the beam splitting structure is disposed between the light valve and the aperture stop. The lens group and the aperture stop located on the side of the beam splitting structure near the magnification side form an output light module, and the lens group located on the side of the beam splitting structure near the reduction side forms an input light module. The zoom projection lens includes two sets of output light modules with different output light directions. The beam splitting structure is used to transmit light from the input light module to at least one of the two sets of output light modules.

[0022] According to any of the foregoing embodiments of the first aspect of this application, the beam splitting structure includes a reflective element, and the light emission orientation of the two light emission modules is different from that of the light emission orientation of the input light module; or, the beam splitting structure includes a semi-transparent and semi-reflective element, and one of the two light emission modules has the same light emission orientation as the input light module.

[0023] According to any of the foregoing embodiments of the first aspect of this application, the beam splitting structure is rotatably configured and has a first rotation position and a second rotation position; in the first rotation position, the beam splitting structure is used to transmit light from the input light module to an output light module; in the second rotation position, the beam splitting structure is used to transmit light from the input light module to another output light module.

[0024] According to any of the foregoing embodiments of the first aspect of this application, the beam-splitting structure is movably disposed along a first direction, the first direction intersecting the optical axis direction of the incident light module.

[0025] According to any of the foregoing embodiments of the first aspect of this application, the beam splitting structure is disposed between the fourth lens group and the third lens group, the light output module includes the first lens group, the second lens group, the aperture stop and the third lens group, and the light input module includes the fourth lens group.

[0026] According to any of the foregoing embodiments of the first aspect of this application, the minimum air gap between the third lens group and the fourth lens group is Tmin, wherein Tmin ≥ 18 mm.

[0027] According to any of the foregoing embodiments of the first aspect of this application, at least n lenses with optical power are included between the beam splitting structure and the optical valve, wherein 1≤n≤6.

[0028] The second aspect of this application also provides a projection system, which includes a zoom projection lens according to any embodiment of the first aspect described above.

[0029] A third aspect of this application also provides a projection device, which includes a zoom projection lens of any embodiment of the first aspect or a projection system of the second aspect.

[0030] In a zoom projection lens provided in this application, the zoom projection lens includes a first lens group, a second lens group, an aperture stop, a third lens group, and a fourth lens group. The aperture stop can be used to converge the light rays from the front and back, which helps to shorten the overall length of the zoom projection lens. The first lens group, the second lens group, the aperture stop, the third lens group, and the fourth lens group are arranged sequentially from the magnifying side to the reducing side along the optical axis. During projection, light rays from the light source pass sequentially through the fourth lens group, the third lens group, the aperture stop, the second lens group, and the first lens group from the image plane side, and are finally projected onto the projection screen. The zoom projection lens includes at least ten lenses, that is, the zoom projection lens can be a ten-lens structure. The lens size and structure are compact, and the overall length and lens diameter are relatively limited, making the structure of the zoom projection lens precise, so as to achieve the purpose of low cost, compactness, and small size, thereby reducing space occupation. By reasonably setting the positive and negative refractive powers of each lens in the first lens group, the second lens group, the third lens group, and the fourth lens group, it is beneficial to ensure a smooth transition of light rays and to ensure the stability of imaging, thereby improving the performance of the zoom projection lens. Attached Figure Description

[0031] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, wherein the same or similar reference numerals denote the same or similar features.

[0032] Figure 1 This is one of the structural schematic diagrams of a zoom projection lens provided in the first aspect embodiment of this application;

[0033] Figure 2 This is a schematic diagram of the structure of a zoom projection lens that zooms from the wide end to the telephoto end according to the first aspect embodiment of this application;

[0034] Figure 3This is a second schematic diagram of the structure of a zoom projection lens provided in the first aspect of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] G1, First lens group; G2, Second lens group; S, Aperture stop; G3, Third lens group; G4, Fourth lens group; P, Prism; CG, Protective glass; DMD, Digital microlens device; SCR, Projection screen; A, Light output module; B, Beam splitting structure; C, Light input module;

[0037] L1, First lens; L2, Second lens; L3, Third lens; L4, Fourth lens; L5, Fifth lens; L6, Sixth lens; L7, Seventh lens; L8, Eighth lens; L9, Ninth lens; L10, Tenth lens. Detailed Implementation

[0038] The features and exemplary embodiments of various aspects of this application will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a comprehensive understanding of this application. However, it will be apparent to those skilled in the art that this application can be implemented without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of this application by illustrating examples. In the accompanying drawings and the following description, at least some well-known structures and techniques are not shown to avoid unnecessarily obscuring the application; and, for clarity, the dimensions of some structures may be exaggerated. Furthermore, the features, structures, or characteristics described below can be combined in any suitable manner in one or more embodiments.

[0039] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0040] The directional terms appearing in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] Zoom lenses are generally more difficult to design than prime lenses. In zoom lens design, if the optical power distribution of each lens group is not reasonable, the aberrations of its optical system are difficult to correct effectively, thus making it difficult to obtain good image quality. In order to make more efficient use of illumination, zoom lenses must also meet the requirements of telecentric imaging at both the wide end (also known as the wide-angle end) and the telephoto end (also known as the telephoto end) of the zoom projection lens, while also maintaining the same aperture number. Therefore, zoom lenses usually have a larger lens structure and use more lens elements, making the lens structure more complex and the cost higher.

[0042] Because lenses used in vehicles have extremely high requirements for thermal performance and space size, projection lenses with high resolution, good thermal stability, low chromatic aberration, simple and compact structure, low cost, constant aperture, and telecentric zoom have become a technical challenge in this field.

[0043] This application is proposed to solve the aforementioned technical problems. To better understand this application, the following is combined with... Figures 1 to 3 The zoom projection lens, projection system, and projection device of the present application embodiments will be described in detail.

[0044] The projection device includes a projector. The zoom projection lens in this application embodiment can be a zoom projection lens of a projector. Optionally, the zoom projection lens can be a zoom projection lens of a laser projector. Laser projectors have the characteristics of high image contrast, clear imaging, vibrant colors, and higher brightness. Optionally, the zoom projection lens in this application embodiment can also be applied to LED (Light Emitting Diode) projectors, LCD (Liquid Crystal Display) projectors, etc. The zoom projection lens in this application embodiment includes, but is not limited to, a zoom projection lens as a projector. If other devices use the zoom projection lens provided in this application, they should also fall within the protection scope of this application.

[0045] The zoom projection lens of this application embodiment can be used as a zoom projection lens for a projector. Optionally, the zoom projection lens may further include a prism P, a protective glass CG, and a digital micromirror device (DMD) chip. A first lens group G1, a second lens group G2, an aperture S, a third lens group G3, a fourth lens group G4, the prism P, the protective glass CG, and the digital micromirror device DMD are arranged along the optical axis from the magnification side to the reduction side. During projection, light enters the lens group from the image plane side of the DMD via the protective glass CG and the prism P, and finally exits the lens group to project onto the projection screen SCR (Screen), achieving the projection imaging effect. For example, the zoom projection lens can be applied to an in-vehicle projection system or an in-vehicle projection device.

[0046] Please refer to the following: Figure 1 and Figure 2 , Figure 1 This illustration shows one of the structural schematic diagrams of a zoom projection lens provided in the first aspect embodiment of this application. Figure 2 This illustration shows a structural schematic diagram of a zoom projection lens provided in the first aspect embodiment of this application, zooming from the wide end to the telephoto end.

[0047] like Figure 1 and Figure 2 As shown, an embodiment of the first aspect of this application provides a zoom projection lens, which includes, along the optical axis from the magnification side to the reduction side, a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, an aperture stop S, a third lens group G3 with positive optical power, and a fourth lens group G4 with positive optical power; the first lens group G1 includes, along the optical axis from the magnification side to the reduction side, a first lens L1, a second lens L2, and a third lens L3 with negative, negative, and positive diopters, respectively; the second lens group G2 includes a first lens L1 with negative diopter, a second lens L2, and a third lens L3 with positive diopter, respectively; the second lens group G2 includes a third lens L1 with positive diopter, a second lens L2 with negative diopter, and a third lens L3 with positive diopter. The fourth lens L4; the third lens group G3 includes, along the optical axis from the magnification side to the reduction side, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 with refractive powers of negative, positive, negative, positive, and positive, respectively; the fourth lens group G4 includes a tenth lens L10 with positive refractive power; wherein, the first lens group G1 is used for focusing, the second lens group G2 and the third lens group G3 are both movable along the optical axis, the second lens group G2 is a zoom group, the third lens group G3 is a zoom compensation group, and the fourth lens group G4 is a fixed group.

[0048] In this embodiment of the application, when the zoom projection lens is applied to a projection system or projection device, the magnifying side can refer to the side closer to the projection screen SCR, and the shrinking side can refer to the side closer to the DMD.

[0049] Optionally, the aperture stop S is a variable aperture stop S, which can continuously adjust the size of the opening aperture. By adjusting the size of the aperture stop S, the brightness of the zoom projection lens can be changed to achieve different applications. For example, when high brightness is required, the aperture stop S can be adjusted to the maximum, and when in a darker environment, the aperture stop S can be reduced.

[0050] Optionally, during the zoom process from the wide-angle end to the telephoto end, both the second lens group G2 and the third lens group G3 move towards the magnification side. During the zoom process, the position of the first lens group G1 can remain unchanged, the position of the fourth lens group G4 is fixed, and the position of the imaging plane remains unchanged. In other words, when the user adjusts the zoom, the imaging plane remains fixed and the projected image size is adjusted, so the projected image remains clear without adjusting the focusing front group.

[0051] The zoom projection lens of this application comprises four lens groups with a negative-positive-positive optical power structure. The first lens group G1 is a focusing group, which has a focusing function. The second lens group G2 and the third lens group G3 move along the optical axis between the magnification and reduction sides to enable the zoom projection lens to zoom. Among them, the second lens group G2 is a zoom group, which has a zoom function and is responsible for changing the focal length of the projection lens, thereby adjusting the size of the projected image. When different sizes of images need to be projected, the zoom lens group can respond quickly and achieve continuous changes in focal length by changing the relative positions between the lens groups. The third lens group G3 is a zoom compensation group, which compensates for the system zoom. The zoom compensation group plays a role in fine adjustment and correction in the projection lens. When the zoom lens group changes the focal length, it causes image plane movement and image distortion. The zoom compensation group, through its special shape and position design, can compensate for this image plane movement and image distortion caused by zoom, ensuring that the projected image remains clear and distortion-free at different focal lengths. Furthermore, the zoom compensation lens group optimizes aberration correction, improving image contrast and color reproduction. The fourth lens group, G4, is a rear fixed group to maintain a fixed back focal length.

[0052] The second lens group G2 can consist of only the fourth lens L4. Fewer lenses reduce the lens size and improve structural compactness. The fourth lens L4, with positive diopter, is located on the light-emitting side of the aperture S, effectively converging light and reducing the aperture S diameter, thus decreasing the lens size.

[0053] The fourth lens group G4 can consist of only the tenth lens L10. Fewer lenses reduce the lens size and improve structural compactness. The tenth lens L10, with its positive diopter, facilitates a small telecentric angle. Since the fourth lens group G4 is a fixed-position lens, the back focal length of the zoom projection lens remains constant throughout the zoom process.

[0054] In the zoom projection lens of this application embodiment, the zoom projection lens includes a first lens group G1, a second lens group G2, an aperture stop S, a third lens group G3, and a fourth lens group G4. The aperture stop S can be used to converge the light rays from the front and back, which is beneficial to shorten the overall length of the zoom projection lens. The first lens group G1, the second lens group G2, the aperture stop S, the third lens group G3, and the fourth lens group G4 are arranged sequentially from the magnification side to the reduction side along the optical axis. During projection, light rays from the light source pass sequentially from the image plane side through the fourth lens group G4, the third lens group G3, the aperture stop S, the second lens group G2, and the first lens group G1, and are finally projected onto the projection screen SCR. The zoom projection lens includes at least ten lenses, meaning it can be a ten-lens structure. The lens has a compact size and structure, with significant limitations on its overall length and lens diameter. This allows for a precise structure, achieving low cost, compactness, and small size to reduce space occupation. By rationally setting the positive and negative refractive powers of each lens in the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4, it is beneficial to ensure a smooth transition of light and the stability of imaging, thereby improving the performance of the zoom projection lens.

[0055] In some optional embodiments, in the first lens group G1, the first lens L1 can be an aspherical lens, and the second lens L2 can be a negative diopter biconcave lens, where both the magnifying and reducing surfaces of the lens are concave. The third lens L3 can be a positive diopter biconvex lens, where both the magnifying and reducing surfaces of the lens are convex. Specifically, by rationally optimizing the aspherical coefficient, the negative diopter aspherical lens can effectively correct off-axis aberrations and distortions; the second lens L2 can share the negative focal length of the aspherical lens, reducing the burden on the first negative lens, resulting in a more reasonable focal length distribution, better system performance, and better manufacturability; the third lens L3 balances the overall focal length of the first lens group G1, making the eccentricity tilt tolerance sensitivity of the first lens group G1 better and more suitable for mass production.

[0056] In this embodiment of the application, the surface shape expression of the aspherical lens is:

[0057]

[0058] In the above formula, z represents the distance from a point on the aspherical surface to the vertex of the aspherical surface along the optical axis; c represents the curvature corresponding to the radius; r represents the radial height of the lens; k represents the conic constant; and α1 to α10 represent the aspherical constants corresponding to orders two to twenty, respectively.

[0059] Specifically, when the k coefficient is less than -1, the surface shape curve of the lens is a hyperbola; when the k coefficient is equal to -1, the surface shape curve of the lens is a parabola; when the k coefficient is between -1 and 0, the surface shape curve of the lens is an ellipse; when the k coefficient is equal to 0, the surface shape curve of the lens is a circle; and when the k coefficient is greater than 0, the surface shape curve of the lens is an oval.

[0060] This application embodiment also provides a parameter comparison table 1 for the first lens L1 being an aspherical lens, wherein S1 represents the side surface of the first lens L1 near the magnification side, and S2 represents the side surface of the first lens L1 near the reduction side.

[0061] Table 1

[0062] k <![CDATA[α2]]> <![CDATA[α3]]> <![CDATA[α4]]> <![CDATA[α5]]> <![CDATA[α6]]> <![CDATA[α7]]> <![CDATA[α8]]> <![CDATA[α9]]> <![CDATA[α 10 ]]> S1 -2.3 7.1E-04 -1.3E-05 1.9E-07 -2.1E-09 1.7E-11 -9.1E-14 3.2E-16 -6.6E-19 5.9E-22 S2 0.0 7.1E-04 -7.7E-06 -5.0E-09 3.0E-09 -7.2E-11 9.1E-13 -6.7E-15 2.7E-17 -4.7E-20

[0063] The first lens L1 is an aspherical lens with negative diopter. According to the above expression and Table 1, the surface S1 of the first lens L1 is M-shaped, which can gather large-angle light rays. By reasonably optimizing the radius of curvature and the aspherical coefficient, the distortion aberration and off-axis aberration of the lens can be effectively corrected.

[0064] Optionally, the second lens group G2 is a zoom group, and the surface of the fourth lens L4 near the magnification side is convex, while the surface near the reduction side is concave. That is, the fourth lens L4 can be a positive diopter convex-concave lens. The second lens group G2 is the zoom group of the zoom projection lens, and moving it back and forth along the optical axis can zoom the system.

[0065] Optionally, the aperture stop S is located after the second lens group G2 and can participate in the zoom movement along with the third lens group G3. The third lens group G3 includes five lenses. Optionally, a set of cemented triplet lenses can be designed in the third lens group G3, using achromatic material combinations to correct the chromatic aberration of the system. Lenses containing special thermal properties can also be designed in the third lens group G3 to balance and correct the thermal drift of the system and suppress thermal defocusing at different temperatures. Moving the third lens group G3 back and forth along the optical axis can compensate for the zoom of the system. Optionally, the surface of the fifth lens L5 near the magnification side is convex, and the surface of the fifth lens L5 near the reduction side is concave. The sixth lens L6 is a biconvex lens, the seventh lens L7 is a biconcave lens, the eighth lens L8 is a biconvex lens, and the ninth lens L9 is a biconvex lens. Among them, the sixth lens L6, the seventh lens L7, and the eighth lens L8 can form a cemented triplet lens group, and the combined refractive power of the cemented triplet lens group is positive.

[0066] By cementing three lenses—the sixth lens L6, the seventh lens L7, and the eighth lens L8—it is beneficial to correct chromatic aberration and reduce the air gap between the lenses, thus compressing the overall optical length of the system. Generally, the higher the refractive index of the medium, the more severe the dispersion and the lower the Abbe number; conversely, the lower the refractive index of the medium, the less severe the dispersion and the higher the Abbe number. Therefore, the Abbe number of a lens with a higher refractive index is lower than that of a lens with a lower refractive index. Cementing the sixth, seventh, and eighth lenses together forms a triplet lens group. This triplet lens group satisfies the achromatic principle by using a combination of high and low refractive indices, effectively correcting chromatic aberration in the system. The triplet design for the sixth, seventh, and eighth lenses (L8) also effectively utilizes the cancellation of positive and negative spherical aberration at the cemented surface, ensuring that the overall spherical aberration of the optical system is corrected.

[0067] Optionally, in the triplet lens group, the refractive index of the sixth lens L6 is nd1, and the Abbe number is Vd1; the refractive index of the seventh lens L7 is nd2, and the Abbe number is Vd2; and the refractive index of the eighth lens L8 is nd3, and the Abbe number is Vd3; wherein nd1 < nd2, nd3 < nd2; and Vd1 > Vd2, Vd3 > Vd2. The refractive indices of the sixth lens L6 and the eighth lens L8 are lower than those of the seventh lens L7, and the Abbe numbers of the sixth lens L6 and the eighth lens L8 are higher than those of the seventh lens L7. Furthermore, the sixth lens L6 and the eighth lens L8 can be made of different low-dispersion materials, specifically materials with an Abbe number greater than 65. By optimizing the combination of refractive index and Abbe number and the lens shape for the application wavelength, chromatic aberration and spherical aberration can be well corrected.

[0068] Optionally, the eighth lens L8 satisfies at least one of the following conditions: 1.43≤nd3≤1.55; 70≤Vd3≤95; the refractive index temperature coefficient dn / dt of the eighth lens L8 is <0. Optionally, the eighth lens L8 is a glass lens.

[0069] The triplet lens group employs a positive-negative-positive cemented structure. The eighth lens L8 in the triplet lens group is made of glass with an nd3 of 1.43–1.55 and an Abbe number Vd3 of 70–95, and the dn / dt ratio is negative, which also allows for thermal compensation of the entire optical system. Optionally, the sixth, seventh, and eighth triplet lens groups are positioned near the rear of the aperture stop S, which provides good chromatic aberration correction.

[0070] Optionally, the fourth lens group G4 is a rear fixed group, the surface of the tenth lens L10 near the magnification side is convex, and the surface of the tenth lens L10 near the reduction side is flat.

[0071] In these embodiments, the MTF (Modulation Transfer Function) performance can be improved by setting the parameters of each lens, resulting in good image quality and reduced system distortion. By rationally setting the surface texture of each lens, the optical lens can achieve smaller aberrations, better light utilization, and higher resolution.

[0072] The distances between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the aperture S, and the distances between the third lens group G3 and the fourth lens group G4 are variable. That is, the distances between these distances change with the focal length of the zoom projection lens. Optionally, the distance between the aperture S and the third lens group G3 can be fixed, meaning the aperture S can move with the third lens group G3 during zooming, simplifying the lens design.

[0073] For example, the distance between the third lens L3 and the fourth lens L4 is variable, with a distance of x1; the distance between the fourth lens L4 and the fifth lens L5 is variable, with a distance of x2; and the distance between the ninth lens L9 and the tenth lens L10 is variable, with a distance of x3. These distances refer to the straight-line distance between the centers of two adjacent lenses on the optical axis. Referring to Table 2, which shows different lens spacings at the wide-angle and telephoto ends of a zoom projection lens in one embodiment.

[0074] Table 2:

[0075] x1 x2 x3 Wide 12.0 16.5 20.2 tele 1.2 20.0 27.9

[0076] When the radius of curvature of the magnifying side of a lens is positive, the magnifying side is convex; otherwise, it is concave. When the radius of curvature of the reducing side of a lens is negative, the reducing side is convex; otherwise, it is concave. When the radius of curvature of the magnifying side of a lens is ±∞, the magnifying side is flat. When the radius of curvature of the reducing side of a lens is ±∞, the reducing side is flat.

[0077] In some embodiments, the first lens L1 can be an aspherical negative lens, with the radius of curvature of the surface of the first lens L1 near the magnification side being -115mm to -10mm, and the radius of curvature of the surface of the first lens L1 near the reduction side being 20mm to 100mm. The second lens L2 can be a biconcave negative lens, with the radius of curvature of the surface of the second lens L2 near the magnification side being -50mm to -25mm, and the radius of curvature of the surface of the second lens L2 near the reduction side being 5mm to 40mm. The third lens L3 can be a biconvex positive lens, with the radius of curvature of the surface of the third lens L3 near the magnification side being 20mm to 60mm, and the radius of curvature of the surface of the third lens L3 near the reduction side being -90mm to -40mm. The fourth lens L4 can be a convex-concave positive lens, with the convex surface facing the magnification side, the radius of curvature of the surface of the fourth lens L4 near the magnification side being 20mm to 60mm, and the radius of curvature of the surface of the fourth lens L4 near the reduction side being >100mm. The fifth lens L5 can be a convex-concave positive lens, with the convex surface facing the magnifying side. The radius of curvature of the surface of the fifth lens L5 near the magnifying side is >100mm, and the radius of curvature of the surface of the fifth lens L5 near the reducing side is 10mm to 50mm. The sixth lens L6 can be a biconvex positive lens. The radius of curvature of the surface of the sixth lens L6 near the magnifying side is 20mm to 50mm, and the radius of curvature of the surface of the sixth lens L6 near the reducing side is -30mm to -6mm. The seventh lens L7 can be a biconcave negative lens. The radius of curvature of the surface of the seventh lens L7 near the magnifying side is -30mm to -6mm, and the radius of curvature of the surface of the seventh lens L7 near the reducing side is 30mm to 70mm. The eighth lens L8 can be a biconvex positive lens. The radius of curvature of the surface of the eighth lens L8 near the magnifying side is 30mm to 70mm, and the radius of curvature of the surface of the eighth lens L8 near the reducing side is -50mm to -10mm. The ninth lens L9 can be a biconvex positive lens. The radius of curvature of the surface of the ninth lens L9 near the magnification side is 75mm to 150mm, and the radius of curvature of the surface of the ninth lens L9 near the reduction side is -30mm to -10mm. The tenth lens L10 can be a plano-convex positive lens with the convex surface facing the magnification side. The radius of curvature of the surface of the tenth lens L10 near the magnification side is 20mm to 55mm, and the surface of the tenth lens L10 near the reduction side is flat.

[0078] In these embodiments, by reasonably setting the radius of curvature of each lens surface, the image projected from the zoom projection lens can have a better display effect.

[0079] In this embodiment, the second lens group G2 and the third lens group G3 are zoom groups. Compared with the related technologies that set three or more moving zoom groups, the lens architecture of this application is simple and conducive to the miniaturization of zoom projection lenses.

[0080] Optionally, to maximize light efficiency at different focal lengths, zoom projection lenses can maintain the same aperture number Fno during zooming from the wide-angle end to the telephoto end. This reduces the likelihood of lower light intake efficiency at the telephoto end compared to the wide-angle end, or even significantly lower, thus achieving more efficient application lighting. The specific formula is Fno = EFL / EPD, where EFL refers to the effective focal length of the lens, and the entrance pupil diameter (EPD) represents the maximum diameter of light allowed to enter the lens when viewed from object space. In zoom projection lenses, the effective focal length at the wide-angle end is defined as EFLw, and the effective focal length at the telephoto end is defined as EFLt. During zooming, the zoom projection lens maintains the same aperture number for both wide and low focal lengths, i.e., Fnow = FnoT. From this, we can derive: EFLw / EFLt = EPDw / EPDt.

[0081] Optionally, 1.5 ≤ Fno ≤ 3; for example, the value of Fno can be 1.5, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, etc. Of course, the aperture number Fno of the zoom projection lens can also be any combination of the above values. For example, the zoom projection lens provided in this embodiment can maintain a constant aperture number Fno of 2.4.

[0082] In some optional embodiments, the back focal length of the zoom projection lens is BFL, the total optical length of the zoom projection lens at the wide-angle end is TTLw, the effective focal length of the zoom projection lens at the wide-angle end is EFLw, the effective focal length of the zoom projection lens at the telephoto end is EFLt, and the zoom projection lens satisfies at least one of the following conditions: 0.15≤BFL / TTLw≤1.0; 5.3≤TTLw / EFLw≤11.5; 5.3≤TTLw / EFLt≤8.8; 1.5≤BFL / EFLw≤3.

[0083] In this embodiment, the focal length of the zoom projection lens can also be referred to as the effective focal length. The back focal length of the zoom projection lens can also be referred to as the back focal length; the back focal length of the zoom projection lens refers to the distance on the optical axis between the reduced-size side of the lens closest to the DMD and the DMD chip. Optionally, the total optical length TTLw of the zoom projection lens refers to the axial distance along the optical axis between the magnifying side of the first lens L1 and the DMD at the wide-angle end. Optionally, in a ten-lens zoom projection lens architecture, the back focal length of the zoom projection lens is equal to the distance on the optical axis between the reduced-size side of the tenth lens L10 and the DMD.

[0084] Optionally, the zoom projection lens satisfies the following conditions: 0.15 ≤ BFL / TTLw ≤ 1.0; 5.3 ≤ TTLw / EFLw ≤ ​​11.5; 5.3 ≤ TTLw / EFLw ≤ ​​8.8; 1.5 ≤ BFL / EFLw ≤ ​​3. For example, the BFL / TTLw ratio can be 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0. The BFL / TTL ratio can also be any combination of the above values. The ratios of other parameters are similar and will not be elaborated here. Through the above design, both the size and optical imaging quality of the zoom projection lens can be considered. This design allows the zoom projection lens to have a long back focus while also satisfying the characteristic of a short lens length, enabling the miniaturization of projection devices using this zoom projection lens, thereby improving the performance of the zoom projection lens.

[0085] In some optional embodiments, the zoom ratio of the zoom projection lens is 1.0 ≤ EFLt / EFLw ≤ ​​3. The EFLt / EFLw ratio can be 1.0, 1.001, 1.213, 1.228, 1.244, 1.245, 2.0, or 3, etc. The EFLt / EFLw ratio can also be any combination of the above values. This embodiment of the zoom projection lens has a large zoom range, providing versatility and convenience in terms of image size, projection distance, and installation flexibility.

[0086] In some optional embodiments, the zoom projection lens satisfies: 2mm ≤ EFLw / Fno ≤ 8mm. Optionally, 4mm ≤ EFLt / Fno ≤ 12mm. For example, the ratio of EFLw / Fno can be 8mm, 6mm, 5mm, 4mm, or 2mm, etc. The ratio of EFLt / Fno can be 12mm, 10mm, 8mm, 6mm, or 4mm, etc. The above ratios can also be any combination or range of the above values.

[0087] Optionally, the unidirectional movement distance of the second lens group G2 is d2, and the unidirectional movement distance of the third lens group G3 is d3. The zoom projection lens satisfies: 0.05 ≤ d2 / TTLw ≤ 0.2. Optionally, 0.02 ≤ d3 / TTLw ≤ 0.1. With a limited total lens length, a longer back focal length increases design complexity. Simultaneously, with a limited total length, a longer movable distance d2 for the second lens group G2 (as a zoom group) generally results in a larger zoom ratio.

[0088] In these embodiments, by properly designing d2 and d3, the desired zoom range from wide-angle to telephoto can be achieved. The movement of the lens group is also used to adjust the lens's focusing distance. Ensuring that d2 and d3 are within a given range helps achieve accurate and stable focusing performance. Limiting the movement distance of the lens group also helps maintain the structural stability of the lens. The movement distance of the lens group also directly affects the lens's manufacturing cost. By optimizing the design of d2 and d3, costs can be reduced while maintaining performance.

[0089] In some optional embodiments, the image plane diameter of the zoom projection lens is D, and the zoom projection lens satisfies the following condition: 4≤TTLw / D≤9. Optionally, 0.5≤EFLw / D≤1.5.

[0090] A zoom projection lens with a wide-angle end optical total length (TTLw) to image plane diameter (D) within the range of [4, 9] helps reduce aberrations and improve image sharpness and detail. It also improves lens compactness; a smaller TTLw / D ratio (close to 4) means a more compact lens, which is especially important for space-constrained applications such as portable projectors, micro projectors, and vehicle-mounted projectors. A compact lens design not only facilitates portability and installation but also reduces manufacturing and transportation costs. Furthermore, within this TTLw / D range, the lens can adapt to different sized SCR projection screens and projection distances, providing greater flexibility and a wider range of applications.

[0091] An EFLw / D ratio ≥ 0.5 means the effective focal length (EFLw) at the wide-angle end is at least half the image plane diameter (D). This ratio ensures the lens has a sufficient field of view at the wide-angle end while maintaining a relatively small image plane size, which helps reduce the overall size and weight of the lens. An EFLw / D ratio ≤ 1.5 limits the effective focal length (EFLw) at the wide-angle end to no more than 1.5 times the image plane diameter (D). This ratio helps control the lens's magnification, ensuring that excessive distortion or blurring does not occur when imaging at the wide-angle end. Through the above design, not only can the lens have the required field of view and image quality, but the size and weight of the lens can also be optimized, facilitating system integration and application.

[0092] For example, the TTLw / D ratio can be 4, 5, 6, 7, 8, or 9, etc. The TTLw / D ratio can also be any combination of the above values. The EFLw / D ratio can be 0.5, 0.6, 0.8, 1.0, 1.2, or 1.5, etc., and the EFLw / D ratio can also be any combination of the above values.

[0093] In some optional embodiments, the maximum telecentric angle of the zoom projection lens at each focal length is TAmax, where TAmax ≤ 1.5°. The maximum telecentric angle of the zoom projection lens is designed not to exceed 1.5°. This limitation ensures that light, after passing through the lens, is projected onto the target surface at a relatively consistent angle, thereby helping to maintain the sharpness and uniformity of the projected image and ensuring that the projection system meets specific image quality and performance requirements.

[0094] In some optional embodiments, the focal length of the first lens group G1 is fg1, the focal length of the second lens group G2 is fg2, the focal length of the third lens group G3 is fg3, and the focal length of the fourth lens group G4 is fg4, and the zoom projection lens satisfies at least one of the following conditions:

[0095] -4.3 < fg1 / EFLw < -1.7; for example, the ratio of fg1 / EFLw can be -4.2, -3.5, -3.2, -2.5, -2.0, -1.8, etc. The ratio of fg1 / EFLw can also be any combination of the above values. The first lens group G1 is a negative lens group that diverges light, which can be used to expand the field of view of the lens, especially at the wide-angle end. A larger absolute value of fg1 / EFLw means that the first lens group G1 contributes more to the overall optical performance and can be responsible for most of the divergence.

[0096] 2.2 < fg2 / EFLw < 5.2; for example, the ratio of fg2 / EFLw can be 5.1, 4.5, 3.5, 3.0, 2.5, etc. The ratio of fg2 / EFLw can also be any combination of the above values. The second lens group G2 is a positive lens group that converges light rays, which can be used to reduce light intensity and improve image quality, especially at the telephoto end. A larger fg2 / EFLw ratio means that the second lens group G2 can handle a larger zoom ratio during zooming.

[0097] 5.1 < fg3 / EFLw < 8.2; for example, the ratio of fg3 / EFLw can be 8.1, 7.5, 6.5, 5.8, 5.2, etc. The ratio of fg3 / EFLw can also be any combination of the above values. The third lens group G3 is a positive lens group with a relatively large focal length. The third lens group G3 can play a zoom compensation role during zooming. A larger focal length range helps to achieve a greater zoom magnification.

[0098] 1.6 < fg4 / EFLw < 6.2. For example, the ratio of fg4 / EFLw can be 6.1, 5.5, 4.5, 3.0, 1.8, etc. The ratio of fg4 / EFLw can also be any combination of the above values. The fourth lens group G4 is a positive lens group.

[0099] Optionally, the zoom projection lens satisfies the following conditions: -4.3 < fg1 / EFLw < -1.7; 2.2 < fg2 / EFLw < 5.2; 5.1 < fg3 / EFLw < 8.2; 1.6 < fg4 / EFLw < 6.2.

[0100] Optional: -60mm≤fg1≤-10mm; 16mm≤fg2≤70mm; 30mm≤fg3≤100mm; 20mm≤fg2≤80mm.

[0101] By rationally designing the focal lengths and proportions of various lens groups, the desired zoom range from wide-angle to telephoto can be achieved. The combination and proportions of different lens groups have a significant impact on image quality. In particular, the proper configuration of positive and negative lens groups can correct various aberrations and improve image quality.

[0102] In some optional embodiments, the combined focal length of the third lens group G3 and the fourth lens group G4 is f34, and the distance from the aperture stop S to the surface of the farthest lens in the fourth lens group G4 near the reduced side along the optical axis is T2, where 0.4≤f34 / T2≤1.3.

[0103] In the design of zoom projection lenses, controlling the f34 / T2 ratio within the above range is beneficial to improving the lens's optical performance and zoom capability, while reducing the lens's size and weight.

[0104] In some optional embodiments, the first lens L1 satisfies at least one of the following conditions: 1.45 ≤ nd ≤ 1.65; 60 ≤ Vd ≤ 82; and the first lens L1 is an aspherical lens; where nd is the refractive index of the lens and Vd is the Abbe number of the lens. Optionally, the first lens L1 satisfies 1.45 ≤ nd ≤ 1.65; 60 ≤ Vd ≤ 82; and the first lens L1 is an aspherical lens. Designing the first lens L1 with appropriate curvature, spacing, and aspherical parameters can effectively correct spherical aberration and field curvature of the system to improve the optical MTF performance of the lens.

[0105] In some optional embodiments, the outer diameter of the largest lens in the zoom projection lens is Lmax, where 8mm ≤ Lmax / Fno ≤ 22mm. For example, the ratio of Lmax / Fno can be 22mm, 20mm, 18mm, 16mm, 14mm, 12mm, 10mm, or 8mm, etc. The ratio of Lmax / Fno can also be any combination of the above values.

[0106] The Fno parameter represents the light-gathering capability of a lens. A smaller Fno value indicates stronger light-gathering capability and higher brightness. The outer diameter of a lens can be understood as the length of the outer diameter of a circular object, that is, the longest straight-line distance from one edge of the lens to the other. It can also be understood as the diameter of the lens. Within a certain range of Fno, the maximum outer diameter of the lens is correspondingly limited, thus enabling the design of small-sized zoom projection lenses to reduce space occupation.

[0107] Optionally, the largest lens in the zoom projection lens can be the first lens L1.

[0108] Optionally, the zoom projection lens uses glass lenses. Glass lenses have good thermal stability, which can further ensure optical performance under high and low temperature environments, and can also reduce the overall lens cost and manufacturing difficulty.

[0109] In some alternative embodiments, the first lens group G1 includes at least one aspherical lens; the aspherical lens can correct system aberrations and improve MTF performance. By designing appropriate curvature and spacing as well as aspherical parameters, the spherical aberration and field curvature of the system can be effectively corrected to improve the optical MTF performance of the lens.

[0110] Optionally, the second lens group G2 includes at least one lens with a refractive index greater than 1.7. When only the fourth lens L4 is used, the refractive index of the fourth lens L4 is greater than 1.7. This can effectively correct lens distortion and astigmatism, and at the same time, it can also correct the lens's sine aberration to a certain extent, thereby further improving image quality.

[0111] Optionally, the third lens group G3 may include at least one lens with a refractive index greater than 1.7. This can effectively correct lens distortion and astigmatism, and also correct the lens's sine aberration to a certain extent, thereby further improving image quality. For example, the third lens group G3 may include one, two, or three lenses with a refractive index greater than 1.7.

[0112] Optionally, at least one lens in the third lens group G3 has an Abbe number greater than 75. Lenses with an Abbe number greater than 75 have low dispersion characteristics, enabling them to provide better color correction.

[0113] Optionally, the third lens group G3 includes at least one lens with a refractive index temperature coefficient dn / dt to focal length fn ratio (dn / dt) / fn < 0; a lens with positive refractive power and a negative refractive index temperature coefficient Dn / Dt can compensate for thermal defocusing of the entire zoom projection lens. A lens with negative refractive power and a positive refractive index temperature coefficient Dn / Dt can also compensate for thermal defocusing of the entire zoom projection lens, ensuring that the zoom projection lens does not significantly affect image quality within a certain temperature range.

[0114] For example, the ratio of the refractive index temperature coefficient to the focal length of the eighth lens L8 can be negative.

[0115] Optionally, the third lens group G3 includes at least one set of cemented lenses, each comprising a lens with an Abbe number greater than 70, and at least one of the cemented lenses having a refractive index temperature coefficient Dn / Dt ≤ -6. Lenses with an Abbe number greater than 70 exhibit low dispersion, providing better color correction. The requirement that at least one of the cemented lenses has a refractive index temperature coefficient Dn / Dt ≤ -6 ensures the lens's performance stability at different temperatures, particularly in environments with significant temperature variations; this design helps maintain the imaging quality of the optical system.

[0116] Optionally, the fourth lens group G4 includes at least one lens with a refractive index greater than 1.9. For example, the tenth lens L10 has a refractive index greater than 1.9, which has significant advantages in reducing aperture and improving telecentric angle.

[0117] The zoom projection lens provided in this application has a precise structure, achieving the design requirements of low cost and compact size. The lens is small in size, with significant limitations on its overall length and lens aperture to reduce space occupation. The compact structural design enables miniaturization of the zoom projection lens. It satisfies the requirements of high resolution quality while maintaining a compact structure and controllable cost. When applied to automotive applications, it provides greater design freedom to avoid interference issues caused by interior trim components. This application is based on optical imaging principles, using optical design software to repeatedly optimize the curvature radius, material, thickness, air gap, and two cemented lenses of the zoom projection lens. This achieves the goals of low aberration, high resolution, long back focal length, small overall length, simple structure, high manufacturability, and ease of mass production.

[0118] Combined with reference Figures 1 to 3 , Figure 3 This is shown as a second schematic diagram of the structure of a zoom projection lens provided in the first aspect embodiment of this application.

[0119] like Figure 3 As shown, in some optional embodiments, the zoom projection lens further includes a beam splitting structure B and a light valve. The light valve is located on the side of the fourth lens group G4 near the reduction side, and the beam splitting structure B is located between the light valve and the aperture stop S. The lens group located on the side of the beam splitting structure B near the magnification side and the aperture stop S form the light output module A, and the lens group located on the side of the beam splitting structure B near the reduction side forms the light input module C. The zoom projection lens includes two light output modules A with different light output directions. The beam splitting structure B is used to transmit the light from the light input module C to at least one of the two light output modules A.

[0120] In these embodiments, the two light-emitting modules A can share the same light-incident module C, simplifying the structure of the zoom projection lens capable of multi-directional projection. Light path switching is achieved through the beam-splitting structure B, eliminating the need to rotate the projection device and enabling multi-directional projection to meet various application requirements. Furthermore, both light-emitting modules A can have their focal length adjusted to achieve different image sizes.

[0121] The beam-splitting structure B can be a plane or a curved surface (such as a spherical surface, an aspherical surface, a free-form surface, etc.), and its beam-splitting device can be a reflective element or a reflective-transmitting element.

[0122] Optionally, the beam splitting structure B includes a reflective element, and the light-emitting directions of the two light-emitting modules A are different from those of the light-emitting module C, so as to change the light path from the light-emitting module C through reflection.

[0123] Optionally, the beam-splitting structure B includes a semi-transparent, semi-reflective element, and one of the two light-emitting modules A has the same light-emitting direction as the incident light module C. The semi-transparent, semi-reflective element facilitates simultaneous imaging of two projection screens with SCRs at different orientations. One of the two light-emitting modules A uses the reflective properties of the beam-splitting structure B to alter the light path from the incident light module C before emitting light for imaging, while the other can directly receive unreflected light through the transparent properties of the beam-splitting structure B for emitting light for imaging. This improves the applicability of zoom projection lenses.

[0124] The beam splitter also has a switchable mechanism. Optionally, the beam splitter structure B can be switched by rotation or by insertion / removal. The optical path can be switched by rotating the position of the beam splitter structure B or by inserting / removing the beam splitter structure B.

[0125] Optionally, the beam-splitting structure B is rotatable and has a first rotation position and a second rotation position. In the first rotation position, the beam-splitting structure B is used to transmit the light from the input light module C to one output light module A. In the second rotation position, the beam-splitting structure B is used to transmit the light from the input light module C to another output light module A. The rotation axis of the beam-splitting structure B can be set perpendicular to the optical axis. After the optical axis path is changed by the beam-splitting structure B, the optical axis has at least two different sub-optical axes. The rotation axis of the beam-splitting structure B can be set perpendicular to both sub-optical axes, that is, the rotation axis of the beam-splitting structure B is perpendicular to the plane containing the two sub-optical axes.

[0126] Optionally, the beam-splitting structure B is movable along a first direction, which intersects the optical axis of the incident light module C. Moving the beam-splitting structure B along the first direction allows it to enter the optical axis to change the optical path, or it can be moved out to avoid any impact, thereby achieving optical path switching.

[0127] In these embodiments, the above-described method of switching optical paths is beneficial for simplifying the beam splitting structure B and makes it easier to install within the zoom projection lens.

[0128] In some optional embodiments, the beam-splitting structure B is disposed between the fourth lens group G4 and the third lens group G3. The light-emitting module A includes the first lens group G1, the second lens group G2, the aperture stop S, and the third lens group G3, and the light-input module C includes the fourth lens group G4. The two light-emitting modules A can share the fourth lens group G4 to simplify the structure of the zoom projection lens capable of multi-directional projection.

[0129] In other embodiments, the beam-splitting structure B may be disposed between the first lens group G1 and the second lens group G2, or between the second lens group G2 and the aperture stop S, or between the aperture stop S and the third lens group G3. Optionally, the beam-splitting structure B and the optical valve include at least n lenses with optical power, where 1 ≤ n ≤ 6. The optical valve may be a DMD, Lcos, or LCD, etc.

[0130] In some optional embodiments, the minimum air gap between the third lens group G3 and the fourth lens group G4 is Tmin, where Tmin ≥ 18 mm. A minimum air gap greater than 18 mm between the third lens group G3 and the fourth lens group G4 facilitates the placement of the beam-splitting structure B in the space between them.

[0131] Furthermore, because zooming is required, the third lens group G3 will move along the optical axis. After the zooming movement, the air gap Tmax between the third lens group G3 and the fourth lens group G4 is ≥25mm. With the total length of the lens limited, the larger this gap requirement is, the greater the design difficulty. By setting a light-splitting structure B with a small footprint, the design difficulty of a zoom projection lens capable of multi-directional projection can be simplified.

[0132] A second aspect of this application also provides a projection system including a zoom projection lens according to any embodiment of the first aspect. Since the projection system of this application includes a zoom projection lens according to any embodiment of the first aspect, it also possesses the aforementioned advantages of the zoom projection lens of this application.

[0133] A third aspect of this application also provides a projection device, which includes a zoom projection lens of any embodiment of the first aspect or a projection system of the second aspect. Since the projection device of this application includes a zoom projection lens of any embodiment of the first aspect or a projection system of the second aspect, it also possesses the aforementioned advantages of the zoom projection lens of this application.

[0134] The technical solution of this application will be further described below with reference to the embodiments.

[0135] Example 1

[0136] Please refer to the following: Figure 1 and Figure 2 The zoom projection lens of Embodiment 1 includes, from the magnification side to the reduction side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture S, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, a prism P, a protective glass CG, and a digital microlens device DMD.

[0137] The lens consists of the following lenses: Lens 1 (L1) is an aspherical negative lens; Lens 2 (L2) is a biconcave negative lens; Lens 3 (L3) is a biconvex positive lens; Lens 4 (L4) is a convex-concave positive lens with its convex surface facing the magnification side; Lens 5 (L5) is a convex-concave positive lens with its convex surface facing the magnification side; Lens 6 (L6) is a biconvex positive lens; Lens 7 (L7) is a biconcave negative lens; Lens 8 (L8) is a biconvex positive lens; Lens 9 (L9) is a biconvex positive lens; and Lens 10 (L10) is a plano-convex positive lens with its convex surface facing the magnification side. The overall optical power of the lens is positive.

[0138] The relevant parameters of each component are shown in Table 3.

[0139] Table 3

[0140]

[0141] Surfaces 1 to 26 are arranged sequentially from the magnifying side to the reducing side. x1 represents the distance between the third lens L3 and the fourth lens L4; x2 represents the distance between the fourth lens L4 and the fifth lens L5; and x3 represents the distance between the ninth lens L9 and the tenth lens L10. Referring to Table 2, Table 2 shows the values ​​of x1, x2, and x3 of the zoom projection lens at the wide-angle and telephoto ends in this embodiment.

[0142] Example 1 provides a zoom projection lens with a constant aperture of f / 2.4, a back focal length (BFL) of 26.5 mm, a BFL / TTLw of 0.2233, an EFLt of 15.7 mm, an EFLw of 12.61 mm, a TTLw / EFLw of 9.41, a TTLw / EFLt of 7.76, a BFL / EFLw of 2.10, a zoom ratio of EFLt / EFLw of 1.245, and a maximum telecentric angle (TAmax) of 1.3°. This lens has a precise structure, achieving a low-cost, compact imaging lens. This application is based on optical imaging principles and uses optical design software to repeatedly optimize the curvature radius, material, thickness, air gap, and cemented lens elements of the zoom projection lens, achieving low aberrations, high resolution, a long back focal length, small overall length, simple structure, high manufacturability, and ease of mass production.

[0143] Example 2

[0144] Please refer to the following: Figures 1 to 3 The parameters of each lens in the zoom projection lens of Embodiment 2 can be referred to those of Embodiment 1, and will not be repeated here. The difference is that Embodiment 2 adds a beam-splitting structure B and another set of light-emitting modules A, thereby realizing multi-directional projection of the zoom projection lens.

[0145] This application may be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithm described in a particular embodiment may be modified without departing from the basic spirit of this application. Therefore, the present embodiments are to be regarded as exemplary rather than limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and scope of the claims and their equivalents are thus included within the scope of this application.

Claims

1. A zoom projection lens, characterized in that, Along the optical axis from the magnifying side to the reducing side, it includes, in sequence, a first lens group with negative optical power, a second lens group with positive optical power, an aperture stop, a third lens group with positive optical power, and a fourth lens group with positive optical power. The first lens group includes, in sequence along the optical axis from the magnifying side to the reducing side, a first lens, a second lens, and a third lens with refractive powers of negative, negative, and positive, respectively. The second lens group includes a fourth lens with positive refractive power; The third lens group includes, along the optical axis from the magnification side to the reduction side, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, with refractive powers of negative, positive, negative, positive, and positive, respectively. The fourth lens group includes a tenth lens with positive diopter; The first lens group is used for focusing, the second lens group and the third lens group are both movable along the optical axis, the second lens group is a zoom group, the third lens group is a zoom compensation group, and the fourth lens group is a fixed group.

2. The zoom projection lens according to claim 1, characterized in that, The zoom projection lens has a back focal length of BFL, an optical total length of TTLw at the wide-angle end, an effective focal length of EFLw at the wide-angle end, and an effective focal length of EFLt at the telephoto end. The zoom projection lens satisfies at least one of the following conditions: 0.15≤BFL / TTLw≤1.0; 5.3≤TTLw / EFLw≤11.5; 5.3≤TTLw / EFLt≤8.8; 1.5≤BFL / EFLw≤3.

3. The zoom projection lens according to claim 2, characterized in that, The zoom ratio of the zoom projection lens is 1.0≤EFLt / EFLw≤3.

4. The zoom projection lens according to claim 1, characterized in that, The effective focal length of the zoom projection lens at the wide-angle end is EFLw, the effective focal length of the zoom projection lens at the telephoto end is EFLt, and the aperture number of the zoom projection lens is Fno. The zoom projection lens satisfies the following: 2mm≤EFLw / Fno≤8mm; and / or, 4mm≤EFLt / Fno≤12mm.

5. The zoom projection lens according to claim 1, characterized in that, The total optical length of the zoom projection lens at the wide-angle end is TTLw, the unidirectional movement distance of the second lens group is d2, the unidirectional movement distance of the third lens group is d3, and the zoom projection lens satisfies: 0.05≤d2 / TTLw≤0.2; and / or, 0.02≤d3 / TTLw≤0.

1.

6. The zoom projection lens according to claim 1, characterized in that, The total optical length of the zoom projection lens at the wide-angle end is TTLw, the effective focal length of the zoom projection lens at the wide-angle end is EFLw, the diameter of the image plane circle of the zoom projection lens is D, and the zoom projection lens satisfies the following conditions: 4≤TTLw / D≤9; and / or, 0.5≤EFLw / D≤1.

5.

7. The zoom projection lens according to claim 1, characterized in that, The maximum telecentric angle of each focal length of the zoom projection lens is TAmax, and TAmax ≤ 1.5°.

8. The zoom projection lens according to claim 1, characterized in that, The effective focal length of the zoom projection lens at the wide-angle end is EFLw, the focal length of the first lens group is fg1, the focal length of the second lens group is fg2, the focal length of the third lens group is fg3, and the focal length of the fourth lens group is fg4. The zoom projection lens satisfies at least one of the following conditions: -4.3 < fg1 / EFLw < -1.7; 2.2 < fg2 / EFLw < 5.2; 5.1 < fg3 / EFLw < 8.2; 1.6 < fg4 / EFLw < 6.2; -60mm≤fg1≤-10mm; 16mm≤fg2≤70mm; 30mm≤fg3≤100mm; 20mm≤fg2≤80mm.

9. The zoom projection lens according to claim 1, characterized in that, The combined focal length of the third and fourth lens groups is f34. Along the optical axis, the distance from the aperture stop to the surface of the farthest lens in the fourth lens group closest to the reduction side is T2. 0.4≤f34 / T2≤1.

3.

10. The zoom projection lens according to claim 1, characterized in that, The sixth lens, the seventh lens, and the eighth lens form a cemented triplet lens group. The refractive index of the sixth lens is nd1 and the Abbe number is Vd1. The refractive index of the seventh lens is nd2 and the Abbe number is Vd2. The refractive index of the eighth lens is nd3 and the Abbe number is Vd3. Where nd1 < nd2, nd3 < nd2; And Vd1 > Vd2, Vd3 > Vd2.

11. The zoom projection lens according to claim 10, characterized in that, The eighth lens satisfies at least one of the following conditions: 1.43≤nd3≤1.55; 70≤Vd3≤95; The refractive index temperature coefficient dn / dt of the eighth lens is <0.

12. The zoom projection lens according to claim 1, characterized in that, The first lens satisfies at least one of the following conditions: 1.45≤nd≤1.65; 60≤Vd≤82; The first lens is an aspherical lens; Where nd is the refractive index of the lens, and Vd is the Abbe number of the lens.

13. The zoom projection lens according to any one of claims 1 to 12, characterized in that, The second lens is a biconcave lens; And / or, the third lens is a biconvex lens; And / or, the surface of the fourth lens near the magnification side is convex, and the surface of the fourth lens near the reduction side is concave; And / or, the surface of the fifth lens near the magnification side is convex, and the surface of the fifth lens near the reduction side is concave; And / or, the sixth lens is a biconvex lens; And / or, the seventh lens is a biconcave lens; And / or, the eighth lens is a biconvex lens; And / or, the ninth lens is a biconvex lens; And / or, the surface of the tenth lens near the magnification side is convex, and the surface of the tenth lens near the reduction side is planar.

14. The zoom projection lens according to any one of claims 1 to 12, characterized in that, The zoom projection lens has an aperture number of Fno, the outer diameter of the largest lens in the zoom projection lens is Lmax, and the zoom projection lens satisfies at least one of the following conditions: 8mm≤Lmax / Fno≤22mm; 1.5≤Fno≤3; All lenses in the zoom projection lens are glass lenses.

15. The zoom projection lens according to any one of claims 1 to 12, characterized in that, The zoom projection lens satisfies at least one of the following conditions: The first lens group includes at least one aspherical lens; The second lens group includes at least one lens with a refractive index greater than 1.7; The third lens group includes at least one lens with a refractive index greater than 1.7; At least one lens in the third lens group has an Abbe number greater than 75; The third lens group includes at least one lens in which the ratio of the refractive index temperature coefficient dn / dt to the focal length fn (dn / dt) / fn < 0; The third lens group includes at least one set of cemented lenses, each cemented lens including a lens with an Abbe number greater than 70, and at least one of the cemented lenses has a refractive index temperature coefficient Dn / Dt ≤ -6. The fourth lens group includes at least one lens with a refractive index greater than 1.

9.

16. The zoom projection lens according to any one of claims 1 to 12, characterized in that, During the zoom process from the wide-angle end to the telephoto end, both the second lens group and the third lens group move towards the magnification side; and / or, The aperture moves synchronously with the third lens group.

17. The zoom projection lens according to any one of claims 1 to 12, characterized in that, The zoom projection lens also includes a beam splitting structure and a light valve. The light valve is located on the side of the fourth lens group near the reduction side, and the beam splitting structure is located between the light valve and the aperture stop. The lens group and aperture located on the side of the beam splitting structure closer to the magnification side form the light output module, and the lens group located on the side of the beam splitting structure closer to the reduction side forms the light input module. The zoom projection lens includes two sets of the light output modules with different light output directions. The beam splitting structure is used to transmit light from the light input module to at least one of the two sets of the light output modules.

18. The zoom projection lens according to claim 17, characterized in that, The beam-splitting structure includes a reflective element, and the light-emitting directions of the two sets of light-emitting modules are different from the light-emitting directions of the light-incident modules. Alternatively, the beam splitting structure includes a semi-transparent and semi-reflective element, and one of the two sets of light-emitting modules has the same light-emitting direction as the light-incident module; Alternatively, the beam-splitting structure can be rotatably configured, having a first rotation position and a second rotation position; at the first rotation position, the beam-splitting structure is used to transmit the light from the input light module to one of the output light modules; In the second rotation position, the beam splitting structure is used to transmit the light from the input light module to another output light module; Alternatively, the beam-splitting structure may be movably configured along a first direction, which intersects with the optical axis direction of the incident light module.

19. The zoom projection lens according to claim 17, characterized in that, The beam splitting structure is disposed between the fourth lens group and the third lens group. The light output module includes the first lens group, the second lens group, the aperture stop, and the third lens group. The light input module includes the fourth lens group.

20. The zoom projection lens according to claim 19, characterized in that, The minimum air gap between the third lens group and the fourth lens group is Tmin, where Tmin ≥ 18 mm.

21. The zoom projection lens according to claim 17, characterized in that, The beam splitting structure and the optical valve include at least n lenses with optical power, where 1≤n≤6.

22. A projection system, characterized in that, Includes the zoom projection lens according to any one of claims 1 to 21.

23. A projection device, characterized in that, Includes the zoom projection lens according to any one of claims 1 to 21 or the projection system according to claim 22.

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