Projection lens, projection system and projection device

Abstract

The application discloses a projection lens, a projection system and a projection device. The projection lens comprises a first lens group, a diaphragm and a second lens group. The first lens group comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens. The first lens has a negative refractive power, the second lens has a positive refractive power, the third lens has a negative refractive power, the fourth lens has a negative refractive power, the fifth lens has a negative refractive power, and the sixth lens has a positive refractive power. The second lens group comprises a seventh lens, an eighth lens, a ninth lens and a tenth lens. The seventh lens has a positive refractive power, the eighth lens has a negative refractive power, the ninth lens has a positive refractive power, and the tenth lens has a positive refractive power. The projection lens satisfies at least one of the following conditions: 0.2 <= BFL / EFL <= 3; and BFL / TTL >= 0.1. The projection lens provided by the application can realize small size and improve the performance of the projection lens.

Description

Technical Field

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

[0002] As projectors are increasingly used across various fields, the projection lens determines the image quality, and its design is constantly being improved and optimized. Currently, there are greater demands for smaller projector sizes, requiring more compact and smaller projection lens structures. This presents certain challenges to the performance of projection lenses, and the performance of existing lenses needs improvement. Summary of the Invention

[0003] This application provides a projection lens, a projection system, and a projection device, which can improve the performance of the projection lens.

[0004] An embodiment of the first aspect of this application provides a projection lens, which includes, sequentially from the magnification side to the reduction side along the optical axis, a first lens group with negative optical power, an aperture stop, and a second lens group with positive optical power; the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially from the magnification side to the reduction side along the optical axis, wherein the first lens has negative refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has negative refractive power, the fifth lens has negative refractive power, and the sixth lens has positive refractive power; the second lens group includes a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged sequentially from the magnification side to the reduction side along the optical axis, wherein the seventh lens has positive refractive power, the eighth lens has negative refractive power, the ninth lens has positive refractive power, and the tenth lens has positive refractive power; the focal length of the projection lens is EFL, the back focal length of the projection lens is BFL, the total optical length of the projection lens is TTL, and the projection lens satisfies at least one of the following conditions: 0.2≤BFL / EFL≤3; BFL / TTL≥0.1.

[0005] According to an embodiment of the first aspect of this application, the surface of the first lens near the magnification side is convex, and the surface of the first lens near the reduction side is concave; and / or, the surface of the second lens near the magnification side is convex; and / or, the surface of the third lens near the magnification side is convex, and the surface of the third lens near the reduction side is concave; 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 fifth lens is a biconcave lens; and / or, the sixth lens is a biconvex lens; and / or, the surface of the seventh lens near the magnification side is concave, and the surface of the seventh lens near the reduction side is convex; and / or, the eighth lens is a biconcave lens; and / or, the ninth lens is a biconvex lens; and / or, the tenth lens is a biconvex lens.

[0006] According to any of the foregoing embodiments of the first aspect of this application, the second lens group further includes an eleventh lens, which is disposed on the side of the tenth lens away from the aperture stop; wherein the eleventh lens has positive diopter, and / or, the surface of the eleventh lens near the magnification side is convex.

[0007] According to any of the foregoing embodiments of the first aspect of this application, the projection lens satisfies at least one of the following conditions: all lenses of the projection lens are all-glass spherical lenses; the first lens is an aspherical lens; and one of the tenth and eleventh lenses is a glass aspherical lens.

[0008] According to any of the foregoing embodiments of the first aspect of this application, the fifth lens and the sixth lens constitute a cemented doublet lens group with positive refractive power; and / or, the seventh lens, the eighth lens and the ninth lens constitute a cemented triplet lens group with negative refractive power.

[0009] According to any of the foregoing embodiments of the first aspect of this application, in the triplet lens group, at least one lens has an Abbe number greater than 50, or at least one lens has a refractive index greater than 1.7.

[0010] According to any of the foregoing embodiments of the first aspect of this application, the focal length of the first lens group is EFL. ZOOM1 The focal length of the second lens group is EFL. ZOOM2 And it satisfies the following relationship: -100.0 < EFL ZOOM1 / EFL < -20.0; 0.3 < EFL ZOOM2 / EFL < 4.

[0011] According to any of the foregoing embodiments of the first aspect of this application, the image circle radius of the projection lens is H, the aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens satisfies at least one of the following relationships: 5≤TTL / H≤30; 1≤EFL / H≤3; 8mm≤L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm.

[0012] According to any of the foregoing embodiments of the first aspect of this application, the aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens satisfies at least one of the following relationships: 10mm ≤ EFL ≤ 20mm; TTL ≤ 120mm; BFL ≥ 16mm; Fno ≤ 4; L MAX ≤50mm; projection lens distortion less than 0.5%.

[0013] According to any of the foregoing embodiments of the first aspect of this application, the first lens group includes at least two lenses with a refractive index greater than 1.7; and / or, the second lens group includes at least one lens with a refractive index greater than 1.7; and / or, the second lens group includes X lenses with a negative ratio of refractive index temperature coefficient to focal length, and satisfies the following relationship: 1≤X≤4.

[0014] The second aspect of this application also provides a projection system, which includes a projection lens according to any of the embodiments of the first aspect described above.

[0015] A third aspect of this application also provides a projection device, which includes a projection lens of any embodiment of the first aspect or a projection system of the second aspect.

[0016] In a projection lens provided in this application, the projection lens includes a first lens group, an aperture stop, and a second lens group. By rationally setting the positive and negative refractive powers of each lens in the first and second lens groups, the projection lens structure is made precise, achieving the goals of low cost, compactness, and small size. The first lens group G1 is responsible for light collection and correction of distortion and other off-axis aberrations. The second lens group G2 is responsible for controlling the image-side telecentric angle and correcting chromatic aberration and other off-axis aberrations. The first lens group G1 undertakes the distortion correction capability, which is beneficial to improving the field of view of the system. It can effectively correct off-axis aberrations such as distortion, coma, field curvature, and astigmatism, ensuring a relatively smooth incident angle between the light and the lens surface, providing a large field of view without generating large higher-order aberrations. By rationally planning the refractive powers of each lens, it is beneficial to ensure a smooth light transition and the stability of the image.

[0017] By limiting the ratio of the back focal length (BFL) to the focal length (EFL) of the projection lens to within the range of [0.2, 3], a longer back focal length can be achieved, providing favorable conditions for brightness, structure, and heat dissipation, thereby improving the performance of the projection lens. By limiting the ratio of the back focal length (BFL) to the total optical length (TTL) to be greater than or equal to 0.1, the projection lens can achieve a longer back focal length while maintaining a short lens length, enabling miniaturization of the projection device using this lens and further improving its performance. In summary, the embodiments of this application can improve the performance of projection lenses. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a schematic diagram of the structure of a projection lens provided in the first aspect embodiment of this application;

[0020] Figure 2 This is a schematic diagram of another projection lens provided in the first aspect embodiment of this application;

[0021] Figure 3 This is a schematic diagram of the structure of another projection lens provided in the first aspect embodiment of this application;

[0022] Figure 4 This is the MTF performance diagram of the projection lens provided in Embodiment 1 of this application;

[0023] Figure 5 This is a distortion diagram of the projection lens provided in Embodiment 1 of this application;

[0024] Figure 6 This is a dot diagram of the projection lens provided in Embodiment 1 of this application;

[0025] Figure 7 This is the MTF performance diagram of the projection lens provided in Embodiment 2 of this application;

[0026] Figure 8 This is a distortion diagram of the projection lens provided in Embodiment 2 of this application;

[0027] Figure 9 This is a dot diagram of the projection lens provided in Embodiment 2 of this application;

[0028] Figure 10 This is the MTF performance diagram of the projection lens provided in Embodiment 3 of this application;

[0029] Figure 11 This is a distortion diagram of the projection lens provided in Embodiment 3 of this application;

[0030] Figure 12 This is a dot diagram of the projection lens provided in Embodiment 3 of this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] G1, First lens group; S, Aperture stop; G2, Second lens group; P, Prism; CG, Protective glass; DMD, Digital microlens device; SCR, Projection screen;

[0033] 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; L11, Eleventh lens. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] 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.

[0037] As projectors are increasingly used across various fields, the projection lens determines the image quality, and its design is constantly being improved and optimized. Currently, there are greater demands for smaller projector sizes, requiring more compact and smaller projection lenses. This presents certain challenges to lens performance, necessitating both small size and consistent performance, as well as cost reduction.

[0038] 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 projection lens, projection system, and projection device of the present application are described in detail.

[0039] The projection lens in this application embodiment can be a projection lens of a projector. Optionally, the projection lens can be a projection lens of a laser projector. Laser projectors have the characteristics of high image contrast, clear imaging, vivid colors, and higher brightness. Optionally, the projection lens in this application embodiment can also be applied to LED (Light Emitting Diode) projectors, LCD (Liquid Crystal Display) projectors, etc. The projection lens in this application embodiment is not limited to a projection lens of a projector; if other devices use the projection lens provided in this application, they should also fall within the protection scope of this application.

[0040] The projection lens of this application embodiment can be applied to a fixed-focus projection lens of a projector. The fixed-focus projection lens also includes a prism P, a protective glass CG, and a digital micromirror device (DMD) chip. The first lens group G1, the aperture S, the second lens group G2, 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 projection lens from the image plane side of the DMD, passes through the protective glass CG and the prism P, and finally exits the projection lens to the projection screen SCR (Screen), thus obtaining the projection imaging effect. For example, the projection lens can be applied to an in-vehicle projection system or an in-vehicle projection device.

[0041] Please refer to the following: Figure 1 , Figure 1 This is a schematic diagram of the structure of a projection lens provided in the first aspect of this application.

[0042] like Figure 1As shown, an embodiment of the first aspect of this application provides a 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, an aperture stop S, and a second lens group G2 with positive optical power; the first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 arranged sequentially along the optical axis from the magnification side to the reduction side, wherein the first lens L1 has negative refractive power, the second lens L2 has positive refractive power, the third lens L3 has negative refractive power, the fourth lens L4 has negative refractive power, and the fifth lens L5 has... The first lens has negative refractive power, and the sixth lens L6 has positive refractive power. The second lens group G2 includes a seventh lens L7, an eighth lens L8, a ninth lens L9, and a tenth lens L10 arranged sequentially along the optical axis from the magnification side to the reduction side. The seventh lens L7 has positive refractive power, the eighth lens L8 has negative refractive power, the ninth lens L9 has positive refractive power, and the tenth lens L10 has positive refractive power. The focal length of the projection lens is EFL, the back focal length of the projection lens is BFL, and the total optical length of the projection lens is TTL. The projection lens satisfies at least one of the following conditions: 0.2≤BFL / EFL≤3; BFL / TTL≥0.1.

[0043] In this embodiment, the magnifying side refers to the side of the projection lens that is closer to the SCR projection screen when the projection lens is applied to the projection system or projection device, and the shrinking side refers to the side of the projection lens that is closer to the DMD.

[0044] In this embodiment, the back focal length of the projection lens can also be called the back focal length; the focal length of the projection lens can also be called the effective focal length. Optionally, the total optical length of the projection lens is TTL, which is the axial distance along the optical axis between the magnifying side of the first lens L1 and the DMD. The back focal length of the projection lens refers to the distance along the optical axis between the reducing side of the lens closest to the DMD and the DMD chip.

[0045] Optionally, in a ten-lens projection lens architecture, the back focal length of the projection lens is equal to the distance on the optical axis between the reduced side of the tenth lens L10 and the DMD.

[0046] Optionally, the second lens group G2 also includes an eleventh lens L11, which is located on the side of the tenth lens L10 opposite to the aperture stop S, and has positive diopter. In the eleven-lens projection lens architecture, the back focal length of the projection lens is equal to the distance on the optical axis between the reduced side of the eleventh lens L11 and the DMD.

[0047] Optionally, the projection lens satisfies the following relationship: 0.2≤BFL / EFL≤3; BFL / TTL≥0.1.

[0048] For example, the BFL / EFL ratio can be 3, 2.8, 2.5, 2.2, 2, 1.8, 1.6, 1.3, 1, 0.8, 0.5, or 0.2, etc. The BFL / EFL ratio can also be any combination of the above values. The BFL / TTL ratio can be 0.1, 0.12, 0.15, 0.2, 0.25, 0.3, 0.32, 0.35, 0.4, or 0.5, etc. The BFL / TTL ratio can also be any combination of the above values.

[0049] Optionally, the aperture stop S is a variable aperture stop, which can continuously adjust the size of the opening. By adjusting the size of the aperture stop S, the brightness of the 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] In this embodiment, the first lens group G1, the aperture S, and the second lens group G2 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 second lens group G2, the aperture S, and the first lens group G1 from the image plane side, and are finally projected onto the projection screen SCR. The projection lens includes at least ten lenses. By reasonably setting the positive and negative refractive powers of each lens in the first lens group G1 and the second lens group G2, the structure of the projection lens is made precise, thereby achieving the goals of low cost, compactness, and small size.

[0051] In the projection lens of this application embodiment, the projection lens includes a first lens group G1, an aperture S and a second lens group G2. The aperture S can be used to gather the light from the front and back, which is beneficial to shorten the total length of the projection lens.

[0052] The first lens group G1 collects light and corrects distortion and other off-axis aberrations. The second lens group G2 controls the image-side telecentric angle and corrects chromatic aberration and other off-axis aberrations. The first lens group G1 provides distortion correction, which helps to increase the system's field of view. It effectively corrects off-axis aberrations such as distortion, coma, field curvature, and astigmatism, ensuring a relatively smooth angle of incidence between the light and the lens surface, providing a large field of view without producing large higher-order aberrations. By rationally planning the refractive power of each lens, a smooth light transition is ensured, contributing to the stability of the image.

[0053] By limiting the ratio of the back focal length (BFL) to the focal length (EFL) of the projection lens to within the range of [0.2, 3], a longer back focal length can be achieved, providing favorable conditions for brightness, structure, and heat dissipation, thereby improving the performance of the projection lens. By limiting the ratio of the back focal length (BFL) to the total optical length (TTL) to be greater than or equal to 0.1, the projection lens can achieve a longer back focal length while maintaining a short lens length, enabling miniaturization of the projection device using this lens and further improving its performance. In summary, the embodiments of this application can improve the performance of projection lenses.

[0054] In the projection lens of this application embodiment, the MTF (Modulation Transfer Function) performance can be improved by setting the parameters of each lens, so that the lens has good imaging quality and at the same time reduces system distortion.

[0055] 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.

[0056] In some embodiments, the surface of the first lens L1 near the magnification side is convex, and the surface of the first lens L1 near the reduction side is concave. That is, the radius of curvature of the magnification side of the first lens L1 is positive, and the radius of curvature of the reduction side of the first lens L1 is positive.

[0057] Optionally, the surface of the second lens L2 near the magnifying side is convex. The surface of the second lens L2 near the reducing side can be concave or flat.

[0058] Optionally, the surface of the third lens L3 near the magnification side is convex, and the surface of the third lens L3 near the reduction side is concave.

[0059] Optionally, the surface of the fourth lens L4 near the magnification side is convex, and the surface of the fourth lens L4 near the reduction side is concave.

[0060] Optionally, the fifth lens L5 is a biconcave lens. A biconcave lens is one in which both the magnifying and reducing surfaces are concave.

[0061] Optionally, the sixth lens L6 is a biconvex lens. A biconvex lens is one in which both the magnifying and reducing surfaces are convex.

[0062] Optionally, the surface of the seventh lens L7 near the magnifying side is concave, and the surface of the seventh lens L7 near the reducing side is convex.

[0063] Optionally, the eighth lens L8 is a biconcave lens. Optionally, the ninth lens L9 is a biconvex lens. Optionally, the tenth lens L10 is a biconvex lens.

[0064] In these embodiments, by rationally setting the concave and convex shapes of each lens surface, the optical lens can have smaller aberrations, better light utilization, and higher resolution.

[0065] In some embodiments, the second lens group G2 further includes an eleventh lens L11, which is disposed on the side of the tenth lens L10 opposite to the aperture stop S; wherein, the eleventh lens L11 has positive refractive power. By reasonably setting the curvature and thickness of the eleventh lens L11, off-axis aberrations and system distortions can be effectively corrected, thereby improving MTF performance. Optionally, the surface of the eleventh lens L11 near the magnification side is convex, and the surface of the eleventh lens L11 near the reduction side can be either convex or flat.

[0066] Optionally, the eleventh lens L11 can be a biconvex positive lens, with both the magnifying and reducing sides of the eleventh lens L11 being convex.

[0067] In some embodiments, the first lens L1 can be a meniscus negative lens, the radius of curvature of the surface of the first lens L1 near the magnification side is 30mm to 60mm, and the radius of curvature of the surface of the first lens L1 near the reduction side is 10mm to 35mm.

[0068] The second lens L2 can be a meniscus positive lens or a plano-convex positive lens. The radius of curvature of the surface of the second lens L2 near the magnification side is 15mm to 40mm, and the radius of curvature of the surface of the second lens L2 near the reduction side is 60mm to ∞.

[0069] The third lens L3 can be a meniscus negative lens. The radius of curvature of the surface of the third lens L3 near the magnification side is 10mm to 40mm, and the radius of curvature of the surface of the third lens L3 near the reduction side is 8mm to 80mm.

[0070] The fourth lens L4 can be a meniscus negative lens. The radius of curvature of the surface of the fourth lens L4 near the magnification side is 10mm to 50mm, and the radius of curvature of the surface of the fourth lens L4 near the reduction side is 5mm to 20mm.

[0071] Specifically, the fifth lens L5 and the sixth lens L6 can be two separate lenses or a cemented doublet. The fifth lens L5 can be a biconcave negative lens, with a radius of curvature of -15mm to -100mm on the surface near the magnifying side and 5mm to 50mm on the surface near the reducing side. The sixth lens L6 can be a biconvex positive lens, with a radius of curvature of 5mm to 60mm on the surface near the magnifying side and -20mm to -80mm on the surface near the reducing side.

[0072] Lens L7 (seventh lens), L8 (eighth lens), and L9 (ninth lens) can form a cemented three-lens group. Lens L7 can be a meniscus positive lens, with a radius of curvature of -15mm to -100mm on the surface near the magnifying side and -7mm to -50mm on the surface near the reducing side. Lens L8 can be a biconcave negative lens, with a radius of curvature of -7mm to -50mm on the surface near the magnifying side and 25mm to 100mm on the surface near the reducing side. Lens L9 can be a biconvex positive lens, with a radius of curvature of 25mm to 100mm on the surface near the magnifying side and -10mm to -40mm on the surface near the reducing side.

[0073] The tenth lens L10 can be a biconvex positive lens. The radius of curvature of the surface of the tenth lens L10 near the magnification side is 40mm to 280mm, and the radius of curvature of the surface of the tenth lens L10 near the reduction side is -20mm to -100mm.

[0074] The eleventh lens L11 can be a biconvex positive lens or a plano-convex positive lens. The radius of curvature of the surface of the eleventh lens L11 near the magnification side is 15mm to 300mm, and the radius of curvature of the surface of the eleventh lens L11 near the reduction side is -∞ to -20mm.

[0075] In these embodiments, by reasonably setting the radius of curvature of each lens surface, the image projected from the projection lens can have a better display effect.

[0076] In some embodiments, the projection lens uses all-glass spherical lenses. An all-glass spherical lens is a lens whose front and back surfaces are both spherical, or one surface is spherical and the other is flat, and the entire lens is made of glass. Since the radius of curvature is the same in all directions, the refractive power is also equal.

[0077] In these embodiments, the projection lens uses all-glass spherical lenses, without plastic aspherical lenses or glass molded aspherical lenses, which greatly reduces the overall lens cost and manufacturing difficulty.

[0078] It should be noted that, in the embodiments of this application, some of the all-glass spherical lenses can be replaced with other types of lenses. Optionally, the first lens L1 can be replaced with an aspherical lens.

[0079] Optionally, one of the tenth lens L10 and the eleventh lens L11 can be replaced with a glass aspherical lens. This embodiment can also reduce the cost and manufacturing difficulty of the projection lens.

[0080] In this embodiment of the application, the surface shape expression of the aspherical lens is:

[0081]

[0082] In the above formula, z represents the distance from a point on the aspherical surface to the vertex of the aspherical surface in the direction of 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 α8 represent the aspherical coefficients corresponding to the second to sixteenth orders, respectively.

[0083] 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.

[0084] In some embodiments, the projection lens uses all-glass spherical lenses. An all-glass spherical lens is a lens whose front and back surfaces are both spherical, or one surface is spherical and the other is flat, and the entire lens is made of glass. Since the radius of curvature is the same in all directions, the refractive power is also equal.

[0085] This application also provides a parameter comparison table for the first lens L1 being an aspherical lens or the tenth lens L10 being an aspherical lens, for reference. Wherein, S1 represents the surface of the first lens L1 near the magnifying side, S2 represents the surface of the first lens L1 near the reducing side; S20 represents the surface of the tenth lens L10 near the magnifying side, and S21 represents the surface of the tenth lens L10 near the reducing side.

[0086]

Parameter Comparison Table

[0087] S1 S2 S20 S21 k -0.04 0 0 0 α2 -8.12E-07 5.12E-07 5.27E-06 4.28E-06 α3 -1.45E-09 -8.55E-10 -1.59E-08 1.96E-08 α4 1.33E-11 -1.23E-11 -2.74E-10 -7.13E-11 α5 3.75E-14 5.27E-13 -3.00E-12 -2.04E-12 α6 3.33E-16 5.33E-15 1.21E-13 -3.06E-14 α7 1.01E-17 -2.65E-17 3.79E-17 2.87E-15 α8 -6.97E-20 -1.13E-19 -1.70E-17 -3.32E-17

[0088] A cemented doublet lens group is a lens group formed by cementing two lenses together, while a cemented triplet lens group is a lens group formed by cementing three lenses together, with the cemented surfaces of adjacent lenses touching each other.

[0089] In some embodiments, the fifth lens L5 and the sixth lens L6 form a cemented doublet with positive refractive power. By cementing the two lenses, the fifth lens L5 and the sixth lens L6, it is beneficial to correct chromatic aberration and reduce the air gap between the lenses, thereby compressing the overall optical length of the system.

[0090] In some embodiments, the seventh lens L7, the eighth lens L8, and the ninth lens L9 form a cemented lens group with negative refractive power. By cementing the seven lenses L7, L8, and L9 together to form a cemented lens, it is beneficial to correct chromatic aberration and reduce the air gap between the lenses, thereby compressing the overall optical length of the system.

[0091] In this embodiment, only one set of cemented doublet lenses and one set of cemented triplet lenses can be provided, thereby reducing the cost of the projection lens. Optionally, the fifth lens L5 and the sixth lens L6 can also be provided alternately, with only one set of cemented triplet lenses consisting of the seventh lens L7, the eighth lens L8, and the ninth lens L9.

[0092] In some embodiments, in the triplet lens group, at least one lens has an Abbe number greater than 50, or at least one lens has a refractive index greater than 1.7.

[0093] Generally speaking, the higher the refractive index of a medium, the more severe the dispersion and the lower the Abbe number; conversely, the lower the refractive index of a medium, the less severe the dispersion and the higher the Abbe number. Therefore, a lens with a higher refractive index has a lower Abbe number than a lens with a lower refractive index.

[0094] In these embodiments, by limiting the Abbe number of at least one lens in the triplet lens group to be greater than 50, or the refractive index of at least one lens to be greater than 1.7, the chromatic aberration of the system can be effectively corrected, the distortion and astigmatism of the projection lens can be improved, and the image quality can be enhanced.

[0095] For example, in a triplet lens group, the refractive indices of the seventh lens L7 and the ninth lens L9 can both be less than the refractive index of the eighth lens L8. The refractive index of the eighth lens L8 is greater than 1.7; for example, the refractive index of the eighth lens L8 can be 1.72, 1.75, 1.78, 1.8, etc.

[0096] In these embodiments, the combination of refractive power and refractive index of multiple lenses in the cemented lens group can effectively correct system chromatic aberration, and the cancellation of positive and negative spherical aberrations on the cemented surface can achieve the overall spherical aberration correction effect of the projection lens, thereby ensuring both image quality and simple structure of the projection lens.

[0097] Optionally, the fifth lens L5 and the sixth lens L6 are paired in a low-refractive-index and high-refractive-index configuration, while the seventh lens L7, the eighth lens L8, and the ninth lens L9 are paired in a low-refractive-index, high-refractive-index, and low-refractive-index configuration. A lens with a high refractive index is defined as a lens with a refractive index not less than 1.70, and a lens with a low refractive index is defined as a lens with a refractive index not greater than 1.60.

[0098] In some embodiments, the focal length of the first lens group G1 is EFL. ZOOM1 The focal length of the second lens group G2 is EFL. ZOOM2 And it satisfies the following relationship: -100.0 < EFL ZOOM1 / EFL < -20.0; 0.3 < EFL ZOOM2 / EFL < 4.

[0099] For example, EFL ZOOM1 The / EFL ratio can be -95, -85, -70, -55, -40, -30, or -25, etc. EFL ZOOM1 The / EFL ratio can also be any combination of the above values.

[0100] For example, EFL ZOOM2 The ratio of / EFL can be 3.8, 3.5, 3.2, 2.5, 2.0, 1.6, 1.2, 0.8, 0.6, or 0.4, etc. EFL ZOOM2 The / EFL ratio can also be any combination of the above values.

[0101] In these embodiments, the first lens group G1 has good light collection, distortion correction, and other off-axis aberration effects. The second lens group G2 has good image-side telecentric angle control, chromatic aberration correction, and other off-axis aberration effects.

[0102] In some embodiments, the image radius of the projection lens is H, the aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens satisfies at least one of the following relationships: 5≤TTL / H≤30; 1≤EFL / H≤3; 8mm≤L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm.

[0103] The Fno parameter represents the light-gathering capability of a lens. Fno = focal length (EFL) of the projection lens / aperture diameter. With a constant focal length, a larger aperture diameter results in a smaller Fno value, 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 itself. Within a certain range of Fno, the maximum outer diameter of the lens is correspondingly limited, thus enabling the design of small projection lenses to reduce space occupation. The image radius can also be understood as the image plane height.

[0104] Optionally, the projection lens satisfies the following relationships: 5≤TTL / H≤30; 1≤EFL / H≤3; 8mm≤L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm. While possessing strong light transmission capability, it also meets the characteristic of short lens length, which allows for the miniaturization of projection devices using this projection lens.

[0105] For example, the TTL / H ratio can be 30, 24, 20, 16, 12, 10, 8, or 5, etc. The TTL / H ratio can also be any combination of the above values.

[0106] For example, the EFL / H ratio can be 3, 2.8, 2.4, 2, 1.6, 1.4, 1.2, or 1, etc. The EFL / H ratio can also be any combination of the above values.

[0107] For example, L MAX The / Fno ratio can be 30mm, 24mm, 20mm, 16mm, 12mm, 10mm, or 8mm, etc. L MAX The ratio / Fno can also be any combination of the above values. Optionally, the largest lens in the projection lens can be the first lens L1.

[0108] For example, the EFL / Fno ratio can be 16mm, 12mm, 10mm, 8mm, 6mm, 4mm, or 2mm, etc. The EFL / Fno ratio can also be any combination of the above values.

[0109] In some embodiments, the projection lens satisfies at least one of the following relationships: 10mm ≤ EFL ≤ 20mm; TTL ≤ 120mm; BFL ≥ 16mm; Fno ≤ 4; L MAX ≤50mm; projection lens distortion less than 0.5%.

[0110] Optionally, the projection lens satisfies the following relationships: 10mm ≤ EFL ≤ 20mm; TTL ≤ 120mm; BFL ≥ 16mm; Fno ≤ 4; L MAX ≤50mm; the distortion of the projection lens is less than 0.5%. The projection lens of the present application embodiment has the advantages of large aperture and high performance, which is conducive to achieving the goals of large aperture, high resolution, high imaging quality, high brightness, low chromatic aberration and long back focus of the projection lens.

[0111] In some embodiments, the projection lens satisfies the following relationship: Fno ≤ 4. The Fno parameter represents the lens's light-gathering capability. The larger the aperture diameter, the smaller the Fno value, the stronger the lens's light-gathering capability, and the higher the brightness. In this embodiment, the projection lens can increase the relative aperture of the stop S to achieve a large aperture, increase light transmission, and improve brightness.

[0112] For example, the aperture number Fno of the projection lens can be 1.8, 2.2, 2.4, 2.6, 2.8, 3.2, 3.6, or 4.0, etc. Of course, the aperture number Fno of the projection lens can also be any combination of the above values.

[0113] In some embodiments, the projection lens satisfies the following relationship: 10mm≤EFL≤20mm.

[0114] For example, the focal length (EFL) of the projection lens can be 10mm, 12mm, 13mm, 15mm, 16mm, 18mm, 19mm, or 20mm, etc. The focal length (EFL) of the projection lens can also be any combination of the above values.

[0115] In some embodiments, the projection lens satisfies the following relationship: TTL≤120mm.

[0116] For example, the total optical length (TTL) of the projection lens can be 120mm, 118mm, 116mm, 115mm, 113mm, 112.5mm, 112mm, 110mm, or 100mm, etc. Of course, the total optical length (TTL) of the projection lens can also be any combination of the above values.

[0117] In some embodiments, the projection lens satisfies the following relationship: BFL ≥ 16mm.

[0118] If the projection lens has a ten-lens structure, BFL can be the distance from the tenth lens L10 to the DMD. The space between the tenth lens L10 and the DMD can be used to place the prism P, protective glass CG, etc.

[0119] If the projection lens has an eleven-lens structure, BFL can be the distance from the eleventh lens L11 to the DMD. The space between the eleventh lens L11 and the DMD can be used to place the prism P, protective glass CG, etc.

[0120] For example, the back focal length (BFL) of the projection lens can be 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 35mm, or 40mm, etc. Of course, the back focal length (BFL) of the projection lens can also be any combination of the above values.

[0121] In some embodiments, L MAX ≤50mm. That is, the diameter of each lens is no greater than 50mm. This is beneficial for miniaturizing the projection lens. For example, the diameter of each lens can be 50mm, 48mm, 45mm, 40mm, 38mm, 36mm, 35mm, 34.6mm, 34.4mm, 34.2mm, or 34.0mm, etc. Of course, the diameter of each lens can also be any combination of the above values.

[0122] In some embodiments, the distortion of the projection lens is less than 0.5%. This allows the projection lens to maintain the shape of the image well during imaging, reducing the shape difference between the projected image and the actual object, and enabling the projection lens to provide a more accurate and clearer projected image.

[0123] In some embodiments, the first lens group G1 includes at least two lenses with a refractive index greater than 1.7. This can effectively correct lens distortion and astigmatism, and also correct the sine difference of the lens to a certain extent, thereby further improving image quality. For example, the first lens group G1 may include 2, 3, 4, or 5 lenses with a refractive index greater than 1.7.

[0124] In some embodiments, the second lens group G2 includes at least one lens with a refractive index greater than 1.7. This can effectively correct lens distortion and astigmatism, and also correct the sine difference of the lens to a certain extent, thereby further improving image quality. For example, the second lens group G2 may include one, two, three, or four lenses with a refractive index greater than 1.8.

[0125] In some embodiments, the second lens group G2 includes the refractive index temperature coefficient Dn / Dt of the X-plate and the focal length F. G A lens with a negative ratio, i.e., (Dn / Dt) / F G <0, Dn / Dt is the temperature coefficient of refractive index of the lens, F GLet X be the focal length of the lens. And it satisfies the following relationship: 1 ≤ X ≤ 4. A lens with positive refractive power and a negative temperature coefficient of refractive index Dn / Dt can compensate for thermal defocusing of the entire projection lens. A lens with negative refractive power and a positive temperature coefficient of refractive index Dn / Dt can also compensate for thermal defocusing of the entire projection lens.

[0126] Optionally, X can be 1, 2, 3, or 4. For example, the ratio of the refractive index temperature coefficient to the focal length of the seventh lens L7 can be negative; the ratio of the refractive index temperature coefficient to the focal length of the ninth lens L9 can also be negative.

[0127] In these embodiments, the projection lens that meets the above conditions can effectively compensate for thermal defocusing, so that the projection lens does not have a significant impact on image quality within a certain temperature range.

[0128] In some embodiments, the fourth lens L4 is a biconcave negative lens, and the fifth lens L5 is a biconvex positive lens. The magnifying side and the reducing side of the fourth lens L4 are both concave. The magnifying side and the reducing side of the fifth lens L5 are both convex.

[0129] In some embodiments, the sixth lens L6 is a biconvex positive lens, the seventh lens L7 is a biconcave negative lens, and the eighth lens L8 is a biconvex positive lens. The magnifying side and the reducing side of the sixth lens L6 are both convex. The magnifying side and the reducing side of the seventh lens L7 are both concave. The magnifying side and the reducing side of the eighth lens L8 are both convex.

[0130] In these embodiments, by reasonably setting the concave and convex shapes of each lens surface, the optical lens can have smaller aberrations, better light utilization, and higher resolution.

[0131] The projection lens provided in this application has a precise structure, achieving a low-cost, compact design. The lens is small in size, with significant limitations on its overall length and lens aperture to minimize space occupation. The compact structural design enables miniaturization of the projection lens. It satisfies the requirements of high resolution 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 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.

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

[0133] A third aspect of this application also provides a projection device, which includes a 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 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 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 , Figures 4 to 6 , Figures 4 to 6 The MTF performance diagram, distortion diagram, and dot plot of the projection lens provided in Example 1 are shown respectively. MTF is one of the best tools for quantifying the overall imaging performance of a system in terms of resolution and contrast. MTF is defined as the ratio of the contrast of the output image to the contrast of the input image, and the value is between 0 and 1. The closer the MTF value is to 1, the higher the image quality, indicating that the system has a higher resolution and can transmit smaller details. Generally speaking, an MTF performance of 0.3 is sufficient for normal imaging. From Figure 4 As can be seen, the lens has an MTF of 0.6 or higher, which indicates good image quality and the ability to effectively transmit image contrast, resulting in clearer and sharper images.

[0137] Generally, lens distortion should be less than 1%. Figure 5 The horizontal axis in the graph represents the distortion value of the projection lens, from... Figure 5 As can be seen, the distortion of this lens is small and can be controlled within 0.5%.

[0138] In geometric optics imaging, many light rays emanating from a single point, after passing through an optical system and forming an image, no longer converge to a single point on the image plane due to aberrations. Instead, they form a speckle of confusion distributed within a certain range; this is called a dot plot. The dot plot visually demonstrates the imaging quality of a projection lens under different fields of view. By observing the distribution of light rays emitted from an object point on the image plane after passing through the lens, one can determine the lens's aberrations. If the speckle of confusion in the dot plot is small and concentrated, it indicates good image quality. The RMS (Root Mean Square) value is a commonly used indicator to measure the size of the speckle in the dot plot. The smaller the RMS value, the more concentrated the speckle, and the better the image quality of the lens. Figure 6 As can be seen, the RMS values ​​of each diffusion spot are between 1.3 and 2.5, indicating that the projection lens has good image quality.

[0139] The projection lens of Embodiment 1, from the magnifying side to the reducing side, includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, an aperture S, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a prism P, and a protective glass CG.

[0140] The lens consists of the following lenses: Lens 1 (L1) is a meniscus negative lens with its convex surface facing the magnifying side; Lens 2 (L2) is a meniscus positive lens with its convex surface facing the magnifying side; Lens 3 (L3) is a meniscus negative lens with its convex surface facing the magnifying side; Lens 4 (L4) is a meniscus negative lens with its convex surface facing the magnifying side; Lens 5 (L5) is a biconcave negative lens; Lens 6 (L6) is a biconvex positive lens; Lenses 7 (L7), 8 (L8), and 9 (L9) form a cemented triplet lens group. Lens 7 (L7) is a meniscus positive lens with its convex surface facing the reducing side; Lens 8 (L8) is a biconcave negative lens; Lens 9 (L9) is a biconvex positive lens; Lens 10 (L10) is a biconvex positive lens; and Lens 11 (L11) is a biconvex positive lens. The overall optical power of the lens is positive.

[0141] The relevant parameters of each component are shown in Table 1.

[0142] Table 1

[0143]

[0144] Among them, surfaces 1 to 25 are arranged sequentially from the enlarged side to the reduced side.

[0145] Example 1 provides a long back focal length (BFL) projection lens with a BFL / EFL ratio of 1.5 and a BFL / TTL ratio of 0.25. 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 two cemented lenses of the projection lens, achieving low aberrations, high resolution, long back focal length, small overall length, simple structure, high manufacturability, and ease of mass production.

[0146] Example 2

[0147] Please refer to the following: Figure 2 , Figures 7 to 9 , Figures 7 to 9 The MTF performance diagram, distortion diagram, and dot plot of the projection lens provided in Example 2 are shown respectively. From Figure 7 As can be seen, the lens's MTF is generally above 0.6, indicating good image quality and the ability to effectively transmit image contrast, resulting in clearer and sharper images. From Figure 8 As can be seen, the lens has low distortion, which can be controlled within 0.5%. From Figure 9 As can be seen, the RMS values ​​of each diffusion spot are between 1.1 and 2.0, indicating that the projection lens has good image quality.

[0148] The projection lens of Embodiment 2, from the magnifying side to the reducing side, includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, an aperture S, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a prism P, and a protective glass CG.

[0149] The difference between Example 2 and Example 1 is that in Example 2, the fifth lens L5 and the sixth lens L6 form a cemented doublet lens group. Also, the specific parameters of the projection lens are different.

[0150] The relevant parameters of each component are shown in Table 2.

[0151] Table 2

[0152]

[0153]

[0154] Among them, surfaces 1 to 24 are arranged sequentially from the enlarged side to the reduced side.

[0155] Example 2 provides a long back focal length (BFL) projection lens with a BFL / EFL ratio of 1.4 and a BFL / TTL ratio of 0.24. This lens has a precise structure, achieving a low-cost, compact imaging lens. 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 projection lens, achieving low aberrations, high resolution, long back focal length, small overall length, simple structure, high manufacturability, and ease of mass production.

[0156] Example 3

[0157] Please refer to the following: Figure 3 , Figures 10 to 12 , Figures 10 to 12 The MTF performance diagram, distortion diagram, and dot plot of the projection lens provided in Example 3 are shown respectively. From Figure 10 As can be seen, the lens's MTF is generally above 0.6, indicating good image quality and the ability to effectively transmit image contrast, resulting in clearer and sharper images. From Figure 11 As can be seen, the lens has low distortion, which can be controlled within 0.5%. From Figure 12 As can be seen, the RMS values ​​of each diffusion spot are between 1.1 and 1.7, indicating that the projection lens has good imaging quality.

[0158] The projection lens of Embodiment 3, from the magnification side to the reduction side, includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, an aperture S, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, a prism P, and a protective glass CG.

[0159] The difference between Example 3 and Example 1 is that Example 3 uses a ten-lens structure and does not have an eleventh lens L11. The specific parameters of the projection lens are also different.

[0160] The relevant parameters of each component are shown in Table 3.

[0161] Table 3

[0162]

[0163]

[0164] Among them, surfaces 1 to 23 are arranged sequentially from the enlarged side to the reduced side.

[0165] Example 3 provides a long back focal length (BFL) projection lens with a BFL / EFL ratio of 1 and a BFL / TTL ratio of 0.24. 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 two cemented lenses of the projection lens, achieving low aberrations, high resolution, long back focal length, small overall length, simple structure, high manufacturability, and ease of mass production.

[0166] 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 projection lens, characterized in that, Along the optical axis from the magnifying side to the reducing side, it includes a first lens group with negative optical power, an aperture, and a second lens group with positive optical power in sequence. The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along the optical axis from the magnification side to the reduction side. The first lens has negative refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has negative refractive power, the fifth lens has negative refractive power, and the sixth lens has positive refractive power. The second lens group includes a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged sequentially along the optical axis from the magnification side to the reduction side. The seventh lens has positive refractive power, the eighth lens has negative refractive power, the ninth lens has positive refractive power, and the tenth lens has positive refractive power. The projection lens has a focal length of EFL, a back focal length of BFL, and a total optical length of TTL. The projection lens satisfies at least one of the following conditions: 0.2≤BFL / EFL≤3; BFL / TTL≥0.

1.

2. The projection lens according to claim 1, characterized in that, The surface of the first lens near the magnifying side is convex, and the surface of the first lens near the reducing side is concave. And / or, the surface of the second lens near the magnifying side is convex; And / or, the surface of the third lens near the magnification side is convex, and the surface of the third lens near the reduction side is concave; 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 fifth lens is a biconcave lens; And / or, the sixth lens is a biconvex lens; And / or, the surface of the seventh lens near the magnification side is concave, and the surface of the seventh lens near the reduction side is convex; And / or, the eighth lens is a biconcave lens; And / or, the ninth lens is a biconvex lens; And / or, the tenth lens is a biconvex lens.

3. The projection lens according to claim 1, characterized in that, The second lens group further includes an eleventh lens, which is disposed on the side of the tenth lens away from the aperture stop; wherein the eleventh lens has positive diopter, and / or the surface of the eleventh lens near the magnification side is convex.

4. The projection lens according to claim 3, characterized in that, The projection lens satisfies at least one of the following conditions: The lenses of the projection lenses are all all-glass spherical lenses; The first lens is an aspherical lens; One of the tenth lens and the eleventh lens is a glass aspherical lens.

5. The projection lens according to claim 1, characterized in that, The fifth lens and the sixth lens form a cemented doublet with positive refractive power; and / or, The seventh lens, the eighth lens, and the ninth lens together form a triplex lens group with negative refractive power.

6. The projection lens according to claim 5, characterized in that, In the triplet lens group, at least one lens has an Abbe number greater than 50, or at least one lens has a refractive index greater than 1.

7.

7. The projection lens according to claim 1, characterized in that, The focal length of the first lens group is EFL. ZOOM1 The focal length of the second lens group is EFL. ZOOM2 And satisfy the following relation: -100.0<EFL ZOOM1 / EFL<-20.0; 0.3 < EFL ZOOM2 / EFL<4。 8. The projection lens according to any one of claims 1 to 7, characterized in that, The image circle radius of the projection lens is H, the aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens satisfies at least one of the following relationships: 5≤TTL / H≤30; 1≤EFL / H≤3; 8mm≤L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm.

9. The projection lens according to any one of claims 1 to 7, characterized in that, The aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens satisfies at least one of the following relationships: 10mm≤EFL≤20mm; TTL≤120mm; BFL ≥ 16mm; Fno≤4; L MAX ≤50mm; The distortion of the projection lens is less than 0.5%.

10. The projection lens according to any one of claims 1 to 7, characterized in that, The first lens group includes at least two lenses with a refractive index greater than 1.7; and / or, The second lens group includes at least one lens with a refractive index greater than 1.7; and / or, The second lens group includes lenses with a negative ratio of refractive index temperature coefficient to focal length, and satisfies the following relationship: 1≤X≤4.

11. A projection system, characterized in that, Includes the projection lens according to any one of claims 1 to 10.

12. A projection device, characterized in that, Includes the projection lens of any one of claims 1 to 10 or the projection system of claim 11.

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