Projection lens, projection system and projection device

Abstract

The embodiment of the invention provides a projection lens, a projection system and a projection device. The projection lens includes a plurality of lenses including a first lens group having negative refractive power and a second lens group having positive refractive power. The first lens group comprises a front lens group and at least one bonding lens group, and the front lens group comprises a first front lens with negative diopter and a second front lens with negative diopter; the second lens group comprises at least one balsaming lens group and a rear lens group, and the rear lens group comprises a first rear lens with 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 in the plurality of lenses, the number of the lenses with positive refractive power and the Abbe number greater than 80 is H; at least one of the following relational expressions is satisfied: TTL / EFL < = 20; bFL / EFL > = 5; 4 > = H > = 1. According to the embodiment of the invention, the small size is realized while the long back focus is realized, and meanwhile, relatively good distortion and MTF performance are realized.

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] LCOS panels typically utilize the polarization properties of light to operate, thus requiring a polarization selection device in the back focus path of the projection lens design. To ensure high contrast in the final projection effect, a polarizing beam splitter (PBS) is often used. This device needs to be placed at a 45° angle to the optical axis, thus requiring a larger air path. Furthermore, with projection technology trending towards greater brightness, incorporating the light combining device in the lens's back focus path could also solve the heat dissipation issues encountered by the chip panel. This would undoubtedly result in a longer back focus path, which presents greater challenges for light correction and system chromatic aberration control. Summary of the Invention

[0003] This application provides a projection lens, a projection system, and a projection device. The projection lens achieves a long back focus while also being small in size, and has good distortion and MTF performance.

[0004] An embodiment of the first aspect of this application provides a projection lens, which includes multiple lenses. The multiple lenses, from the magnification side to the reduction side, sequentially include a first lens group with negative refractive power and a second lens group with positive refractive power. The first lens group, from the magnification side to the reduction side, sequentially includes a front lens group and at least one cemented lens group. The front lens group, from the magnification side to the reduction side, sequentially includes a first front lens with negative refractive power and a second front lens with negative refractive power. The second lens group, from the magnification side to the reduction side, sequentially includes at least one cemented lens group and a rear lens group. The lens group includes a first rear lens with positive refractive power; there is a refractive index difference between adjacent lenses in each cemented lens group, and the multiple cemented lens groups include cemented doublet lens groups and cemented triplet lens groups; 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 among the multiple lenses, the number of lenses with positive refractive power and Abbe number greater than 80 is H, and at least one of the following relationships is satisfied: TTL / EFL≤20; BFL / EFL≥5; 4≥H≥1.

[0005] According to an embodiment of the first aspect of this application, the first lens is an aspherical lens, or / and the first lens is a resin lens.

[0006] According to any of the foregoing embodiments of the first aspect of this application, there are M triplet lens groups and N doublet lens groups, and the following relationships are satisfied: 3≥M≥1; 4≥N≥2; N+M≥3.

[0007] According to any of the foregoing embodiments of the first aspect of this application, the second lens group includes at least two lenses with a refractive index greater than 1.8.

[0008] According to any of the foregoing embodiments of the first aspect of this application, the second lens group includes an X-plate having positive refractive power and a temperature coefficient of refractive index of Dn / Dt, and satisfies the following relationship: Dn / Dt<0, 4≥X≥1.

[0009] According to any of the foregoing embodiments of the first aspect of this application, a plurality of cemented lens groups sequentially include a first cemented triplet lens group, a cemented doublet lens group, a second cemented triplet lens group, and a third cemented triplet lens group from the magnification side to the reduction side. The first lens group includes the first cemented triplet lens group, and the second lens group includes the cemented doublet lens group, the second cemented triplet lens group, and the third cemented triplet lens group.

[0010] According to any of the foregoing embodiments of the first aspect of this application, in a plurality of cemented lens groups, the refractive powers of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as negative, positive, negative, negative, positive, negative, positive, negative, positive, negative, and positive, and the refractive indices of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as low refractive index, high refractive index, high refractive index, low refractive index, high refractive index, high refractive index, low refractive index, high refractive index, low refractive index, high refractive index, and low refractive index; or / and, 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: -4.0≤EFL ZOOM1 / EFL≤-1.5; 2.5≤EFL ZOOM2 / EFL≤9.0.

[0011] According to any of the foregoing embodiments of the first aspect of this application, a plurality of cemented lens groups sequentially include a first cemented doublet lens group, a second cemented doublet lens group, a first cemented triplet lens group, and a second cemented triplet lens group from the magnifying side to the reducing side. The first lens group includes the first cemented doublet lens group and the second cemented doublet lens group, the second lens group includes the first cemented triplet lens group and the second cemented triplet lens group, and the rear lens group further includes a second rear lens disposed between the second cemented triplet lens group and the first rear lens, the second rear lens having positive refractive power.

[0012] According to any of the foregoing embodiments of the first aspect of this application, in a plurality of cemented lens groups, the refractive powers of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as negative, positive, positive, negative, negative, positive, negative, positive, negative, and positive, and the refractive indices of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as low refractive index, high refractive index, high refractive index, high refractive index, high refractive index, low refractive index, high refractive index, low refractive index, high refractive index, and low refractive index; or / and, the focal length of the first lens group is EFL. ZOOM1The focal length of the second lens group is EFL. ZOOM2 And it satisfies the following relationship: -8.0≤EFL ZOOM1 / EFL≤-4.0; 2.0≤EFL ZOOM2 / EFL≤5.0.

[0013] According to any of the foregoing embodiments of the first aspect of this application, a plurality of cemented lens groups sequentially include a first triplet lens group, a first doublet lens group, a second doublet lens group, and a third doublet lens group from the magnifying side to the reducing side. The first lens group includes the first triplet lens group and the first doublet lens group, the second lens group includes the second doublet lens group and the third doublet lens group, and the rear lens group further includes a second rear lens disposed between the third doublet lens group and the first rear lens, the second rear lens having positive refractive power.

[0014] According to any of the foregoing embodiments of the first aspect of this application, in a plurality of cemented lens groups, the refractive powers of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as positive, negative, positive, negative, positive, positive, negative, positive, and negative; the refractive indices of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as low refractive index, low refractive index, high refractive index, high refractive index, low refractive index, low refractive index, high refractive index, low refractive index, and high refractive index; and / or, 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: -8.0≤EFL ZOOM1 / EFL≤-4.0; 2.0≤EFL ZOOM2 / EFL≤5.0.

[0015] According to any of the foregoing embodiments of the first aspect of this application, the projection lens satisfies at least one of the following relationships: 9.5mm≤EFL≤10.5mm; TTL≤180mm; BFL≥58mm; the aperture number of the projection lens is FNO, FNO≤2.5; the distortion of the projection lens is less than 0.5%; the field of view of the projection lens is ≥64°; the telecentric angle of the projection lens is TA, and TA≤1.0; the ratio of the projection distance to the screen width of the projection lens is TR, and 1.0≤TR≤1.2; the diameter of each lens is not greater than 36mm.

[0016] 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.

[0017] 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.

[0018] In the projection lens of this application, the front lens group is configured to include a first front lens with negative refractive power and a second front lens with negative refractive power. This allows the second front lens to share some of the optical power of the first front lens, thereby reducing the sensitivity of the first front lens. The number of lenses with positive refractive power and an Abbe number greater than 80 among the multiple lenses is 1-4, which can meet the thermal defocusing requirements of the projection lens, thus ensuring a high-performance MTF value at high temperatures. A cemented lens group is set in the first lens group and the second lens group G2. The refractive index difference between adjacent lenses in the cemented lens group allows it to provide good chromatic aberration correction and effectively correct chromatic aberration caused by increased spectral bandwidth while converging light. Furthermore, the compact structural design of the projection lens enables miniaturization. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a schematic diagram of the structure of a projection lens provided in the first aspect embodiment of this application;

[0021] Figure 2 This is a schematic diagram of another projection lens provided in the first aspect embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the structure of another projection lens provided in the first aspect of this application. Detailed Implementation

[0023] 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.

[0024] 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.

[0025] 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.

[0026] LCOS panels typically utilize the polarization properties of light to operate, thus requiring a polarization selection device in the back focus path of the projection lens design. To ensure high contrast in the final projection effect, a polarizing beam splitter (PBS) is often used. This device needs to be placed at a 45° angle to the optical axis, thus requiring a larger air path. Furthermore, with projection technology trending towards greater brightness, incorporating the light combining device in the lens's back focus path could also solve the heat dissipation issues encountered by the chip panel. This would undoubtedly result in a longer back focus path, which presents greater challenges for light correction and system chromatic aberration control.

[0027] 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 according to embodiments of this application will be described in detail.

[0028] The projection lens of this application is particularly suitable as a projection lens for Liquid Crystal on Silicon (LCOS) projectors. However, the projection lens of this application is not limited to use as a projection lens for Liquid Crystal on Silicon (LCOS) projectors. If other devices use the projection lens provided in this application, they should also fall within the protection scope of this application. For example, the projection lens of this application can also be applied to LED projectors, Liquid Crystal Display (LCD) projectors, laser projectors, etc.

[0029] The projection lens in this embodiment is applied to the fixed-focus projection lens of a projector.

[0030] 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.

[0031] like Figure 1 As shown, an embodiment of this application provides a projection lens, which includes multiple lenses. From the magnification side to the reduction side, the multiple lenses sequentially include a first lens group G1 with negative refractive power and a second lens group G2 with positive refractive power. The first lens group G1, from the magnification side to the reduction side, sequentially includes a front lens group 10 and at least one cemented lens group 20. The front lens group 10, from the magnification side to the reduction side, sequentially includes a first front lens 11 with negative refractive power and a second front lens 12 with negative refractive power. The second lens group G2, from the magnification side to the reduction side, sequentially includes at least one cemented lens group 20 and... The rear lens group 30 includes a first rear lens 31 with positive refractive power. There is a refractive index difference between adjacent lenses in each cemented lens group 20. The multiple cemented lens groups 20 include a cemented doublet lens group 21 and a cemented triplet lens group 23. 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. Among the multiple lenses, the number of lenses with positive refractive power and an Abbe number greater than 80 is H, and at least one of the following relationships is satisfied: TTL / EFL≤20; BFL / EFL≥5; 4≥H≥1.

[0032] Optionally, the projection lens satisfies the following relationships: TTL / EFL≤20; BFL / EFL≥5, 4≥H≥1.

[0033] For example, the TTL / EFL ratio can be 20, 19, 18, 17, 16, 15, 14, 13, 12, or 11, etc. Of course, the TTL / EFL ratio can also be any combination of the above values.

[0034] For example, the BFL / EFL ratio can be 5, 6, 7, 8, 9, or 10, etc. Of course, the TTL / EFL ratio can also be any combination of the above values.

[0035] For example, the number of lenses with positive refractive power and an Abbe number greater than 80 can be 1, 2, 3, or 4. Of course, the number of lenses with positive refractive power and an Abbe number greater than 80 can also be any combination of the above values.

[0036] Optionally, an aperture S is provided between the first lens group G1 and the second lens group G2.

[0037] Optionally, aperture S is a variable aperture stop, which can continuously adjust the size of the opening. By adjusting the size of aperture S, the brightness of the projection lens can be changed to achieve different applications. For example, when high brightness is required, aperture S can be adjusted to the maximum, and when in a darker environment, aperture S can be reduced.

[0038] In these alternative embodiments, the aperture S size can be adjusted according to the application scenario to achieve a dynamic aperture S effect to adapt to more application scenarios and improve the applicability of the projection lens.

[0039] In some embodiments, such as Figure 1 or Figure 3 As shown, the projection lens also includes a galvanometer 40, a prism 50, a beam splitter PBS, and a liquid crystal on silicon (LCOS) chip 60. The first lens group G1, the second lens group G2, the galvanometer 40, the prism 50, the beam splitter PBS, and the liquid crystal on silicon (LCOS) chip 60 are arranged sequentially along the optical axis from the magnification side to the reduction side. During projection, the light emitted from the liquid crystal on silicon chip 60 is sequentially projected onto the SCR projection screen via the beam splitter PBS, the prism 50, the galvanometer 40, the second lens group G2, and the first lens group G1, achieving the projection imaging effect.

[0040] In some embodiments, such as Figure 2 As shown, the projection lens also includes a galvanometer 40, a prism 50, and a liquid crystal on silicon (LCOS) chip 60. The first lens group G1, the second lens group G2, the galvanometer 40, the prism 50, and the liquid crystal on silicon (LCOS) chip 60 are arranged sequentially along the optical axis from the magnification side to the reduction side. During projection, the light emitted from the liquid crystal on silicon chip 60 is sequentially projected onto the SCR projection screen via the prism 50, the galvanometer 40, the second lens group G2, and the first lens group G1, achieving the projection imaging effect.

[0041] In some embodiments, the galvanometer 40 is jitterable. The jitterable galvanometer 40 allows the projection lens to simultaneously obtain the inherent resolution of the silicon-based liquid crystal chip 60 when the galvanometer 40 is stationary and the 4K high resolution when the galvanometer 40 is jittering.

[0042] Optionally, the galvanometer 40 vibrates under the drive of the driving element.

[0043] In some embodiments, when the projection distance, i.e. the distance to the object surface projection side, changes to obtain different image sizes, focusing can be achieved by adjusting the interval between the galvanometer 40 and the second lens group G2.

[0044] In this embodiment, the magnifying side refers to the side of the projection lens that is closer to the projection screen SCR when the projection lens is applied to the projection system, and the shrinking side refers to the side of the projection lens that is closer to the liquid crystal on silicon (LCOS) chip 60; 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 front lens 11 and the liquid crystal on silicon (LCOS) chip 60.

[0045] In this embodiment, the double-cemented lens group 21 refers to a lens group formed by cementing two lenses together, and the triple-cemented lens group 23 refers to a lens group formed by cementing three lenses together, with the cementing surfaces of adjacent lenses touching each other.

[0046] In this embodiment, the back focal length of the projection lens refers to the focal length of the lens that is closest to the silicon-based liquid crystal chip 60 on the optical axis. That is, the focal length of the first back lens 31.

[0047] In this embodiment, the back focal length of the projection lens is equal to the distance on the optical axis between the reduced side of the first rear lens 31 and the silicon-based liquid crystal chip 60.

[0048] In this embodiment of the application, 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.

[0049] In the projection lens of this embodiment, the front lens group 10 is configured to include a first front lens 11 with negative refractive power and a second front lens 12 with negative refractive power. This allows the second front lens 12 to share some of the optical power of the first front lens 11, thereby reducing the sensitivity of the first front lens 11. The number of lenses with positive refractive power and an Abbe number greater than 80 among the multiple lenses is 1-4, which can meet the thermal defocusing requirements of the projection lens, thus ensuring a high-performance MTF value at high temperatures. A cemented lens group 20 is provided in the first lens group G1 and the second lens group G2. The adjacent lenses in the cemented lens group 20 have a refractive index difference, allowing the cemented lens group 20 to provide good chromatic aberration correction and effectively correct chromatic aberration caused by increased spectral bandwidth while converging light. Furthermore, the compact structural design of the projection lens enables miniaturization.

[0050] In some embodiments, the first front lens 11 is an aspherical lens. An aspherical lens is a lens whose radius of curvature varies with its central axis. By adjusting the surface constant and aspherical coefficient, aspherical lenses can largely eliminate spherical aberration.

[0051] In these embodiments, the first front lens 11 is an aspherical lens, which is beneficial for improving the field of view of the system and effectively correcting off-axis aberrations and system distortion. That is, in the embodiments of this application, the first front lens 11 is used to correct distortion, astigmatism, and sinusoidal aberration.

[0052] Optionally, the first front lens 11 is a resin lens. That is, the first front lens 11 is made of resin material, which reduces the processing difficulty of the first front lens 11, increases the tolerance rate of errors generated in the process, reduces costs, and the resin lens can provide strong distortion correction capability. The resin material can be selected from materials known in the art.

[0053] In some embodiments, the first front lens 11 satisfies the aspherical polynomial formula:

[0054]

[0055] In the formula, z represents the distance from a point on the aspherical surface to the vertex of the aspherical surface along the optical axis;

[0056] c represents the curvature corresponding to the radius;

[0057] r represents the radial height of the first front lens 11;

[0058] k represents the conic constant;

[0059] α1 to α8 represent the aspheric coefficients corresponding to orders two to sixteen, respectively;

[0060] When the coefficient k is less than -1, the surface profile curve of the first front lens 11 is a hyperbola;

[0061] When the coefficient k equals -1, the surface profile curve of the first front lens 11 is a parabola;

[0062] When the coefficient k is between -1 and 0, the surface curve of the first front lens 11 is an ellipse;

[0063] When the k coefficient is equal to 0, the surface curve of the first front lens 11 is circular;

[0064] When the coefficient k is greater than 0, the surface curve of the first front lens 11 is an oval.

[0065] In some embodiments, there are M cemented lens groups 23 and N cemented lens groups 21, satisfying the following relationships: 3≥M≥1; 4≥N≥2; N+M≥3. This arrangement of multiple cemented lens groups 20 is more conducive to providing good chromatic aberration correction effect and effectively correcting chromatic aberration caused by the increase in spectral bandwidth.

[0066] For example, there may be two, three, or four cemented doublet lens groups 21. Of course, the number of cemented doublet lens groups 21 can also be any combination of the above values.

[0067] For example, one, two, or three cemented lens groups 23 can be provided. Of course, the number of cemented lens groups 23 can also be any combination of the above values.

[0068] For example, the sum of the number of cemented triplet lens group 23 and cemented doublet lens group 21 can be 3, 4, or 5, etc. Of course, the sum of the number of cemented triplet lens group 23 and cemented doublet lens group 21 can also be any combination of the above values.

[0069] In some embodiments, the second lens group G2 includes at least two lenses with a refractive index greater than 1.8.

[0070] For example, the second lens group G2 may contain 2, 3, 4, 5, or 6 lenses with a refractive index greater than 1.8. Of course, the number of lenses with a refractive index greater than 1.8 in the second lens group G2 can also be any combination of the above values.

[0071] In some embodiments, the second lens group G2 includes X lenses with positive refractive power and a refractive index temperature coefficient of Dn / Dt, satisfying the following relationship: Dn / Dt < 0, 4 ≥ X ≥ 1. Lenses with positive refractive power and a refractive index temperature coefficient of Dn / Dt can also compensate for thermal defocusing of the entire projection lens.

[0072] For example, a lens with positive refractive power and a refractive index temperature coefficient of Dn / Dt can be one, two, three, or four lenses. Of course, the number of lenses with positive refractive power and a refractive index temperature coefficient of Dn / Dt can also be any combination of the above values.

[0073] In some embodiments, the lens having positive refractive power and a refractive index temperature coefficient of Dn / Dt also has a low refractive index. When such a lens is combined with a lens having negative refractive power and a high refractive index to form a cemented lens group 20, an achromatic design can be performed to ensure that the projection lens has a small chromatic aberration.

[0074] Generally, 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, the Abbe number of a lens with a higher refractive index is less than that of a lens with a lower refractive index. In other words, the second lens group G2 contains X lenses made of low-dispersion material.

[0075] In some embodiments, the projection lens satisfies the following relationship: 9.5mm ≤ EFL ≤ 10.5mm.

[0076] For example, the focal length (EFL) of the projection lens can be 9.5mm, 9.6mm, 9.7mm, 9.8mm, 9.9mm, 10.0mm, 10.1mm, 10.2mm, 10.3mm, 10.4mm, or 10.5mm, etc. Of course, the focal length (EFL) of the projection lens can also be any combination of the above values.

[0077] In some embodiments, the projection lens satisfies the following relationship: TTL≤180mm.

[0078] For example, the total optical length (TTL) of the projection lens can be 180mm, 179mm, 178mm, 177mm, 176mm, 175mm, 174mm, 173mm, 172mm, 171mm, or 170mm, etc. Of course, the total optical length (TTL) of the projection lens can also be any combination of the above values.

[0079] In some embodiments, the projection lens satisfies the following relationship: BFL ≥ 58mm.

[0080] For example, the back focal length (BFL) of the projection lens can be 58mm, 59mm, 60mm, 61mm, 62mm, 63mm, 64mm, 65mm, 66mm, 67mm, 68mm, 69mm, or 70mm, etc. Of course, the back focal length (BFL) of the projection lens can also be any combination of the above values.

[0081] In some embodiments, the aperture number of the projection lens is FNO, where FNO ≤ 2.5. FNO is a parameter representing the lens's light-gathering capability. FNO = focal length (EFL) of the projection lens / aperture diameter (S). With the focal length remaining constant, a larger aperture diameter (S) results in a smaller FNO value, stronger light-gathering capability, and higher brightness. The projection optical system of this embodiment can increase the relative aperture (S) to achieve a large aperture (S), increasing light transmission and improving brightness.

[0082] For example, the aperture number FNO of the projection lens can be 2.5, 2.48, 2.46, 2.44, 2.42, 2.4, 2.38, 2.36, 2.34, 2.32, or 2.3, etc. Of course, the aperture number FNO of the projection lens can also be any combination of the above values.

[0083] In some embodiments, the projection lens satisfies the following relationship: the distortion of the projection lens is less than 0.5%.

[0084] In some embodiments, the projection lens satisfies the following relationship: the field of view of the projection lens is ≥64°.

[0085] In some embodiments, the projection lens satisfies the following relationship: the ratio of the projection distance of the projection lens to the screen width is TR, and 1.0≤TR≤1.2.

[0086] For example, the projection distance to screen width ratio TR of the projection lens can be 1.0, 1.05, 1.1, 1.15, or 1.2, etc. Of course, the projection distance to screen width ratio TR of the projection lens can also be any combination of the above values.

[0087] In some embodiments, the projection lens satisfies the following relationship: the telecentric angle TA of the projection lens satisfies the following condition: TA≤1.14°.

[0088] For example, the telecentric angle TA of the projection lens can be 1.14, 1.13, 1.12, 1.11, 1.10, 1.09, 1.08, 1.07, 1.06, 1.05, 1.04, 1.03, 1.02, 1.01, or 1.0, etc. Of course, the telecentric angle TA of the projection lens can also be any combination of the above values.

[0089] In some embodiments, the projection lenses satisfy the following relationship: the diameter of each lens is no greater than 36mm. This is beneficial for the miniaturization of the projection lenses.

[0090] For example, the diameter of each lens can be 36mm, 35.8mm, 35.6mm, 35.4mm, 35.2mm, 35mm, 34.8mm, 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.

[0091] In these embodiments, the projection distance of the projection lens is the distance between the magnified side of the first front lens 11 and the projection screen SCR; the telecentric angle of the projection lens is the angle between the principal rays of each field of view and the optical axis direction.

[0092] like Figure 1 As shown, in some embodiments, multiple cemented lens groups 20 sequentially include a first cemented triplet lens group 23A, a cemented doublet lens group 21, a second cemented triplet lens group 23B, and a third cemented triplet lens group 23C from the magnifying side to the reducing side. A first lens group G1 includes the first cemented triplet lens group 23A, and a second lens group G2 includes the cemented doublet lens group 21, the second cemented triplet lens group 23B, and the third cemented triplet lens group 23C. That is, there are three cemented triplet lens groups 23, namely the first cemented triplet lens group 23A, the second cemented triplet lens group 23B, and the third cemented triplet lens group 23C; and one cemented doublet lens group.

[0093] In some embodiments, in the plurality of cemented lens groups 20, the refractive powers of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as negative, positive, negative, negative, positive, negative, positive, negative, positive, negative and positive, and the refractive indices of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as low refractive index, high refractive index, high refractive index, high refractive index, high refractive index, high refractive index, low refractive index, high refractive index, low refractive index, high refractive index and low refractive index.

[0094] In these embodiments, a lens with a high refractive index refers to a lens with a refractive index of not less than 1.70, and a lens with a low refractive index refers to a lens with a refractive index of not more than 1.60.

[0095] In these embodiments, the combination of the refractive power and refractive index of multiple lenses in the multiple cemented lens groups 20 can effectively correct the system chromatic aberration, and the cancellation of positive and negative spherical aberrations of 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.

[0096] In these embodiments, the plurality of cemented lens groups 20 include a first lens L1 having negative refractive power and low refractive index, a second lens L2 having positive refractive power and high refractive index, a third lens L3 having negative refractive power and high refractive index, a fourth lens L4 having negative refractive power and high refractive index, a fifth lens L5 having positive refractive power and high refractive index, a sixth lens L6 having negative refractive power and high refractive index, a seventh lens L7 having positive refractive power and low refractive index, an eighth lens L8 having negative refractive power and high refractive index, a ninth lens L9 having positive refractive power and low refractive index, a tenth lens L10 having negative refractive power and high refractive index, and an eleventh lens L11 having positive refractive power and low refractive index.

[0097] Among them, the first lens L1, the second lens L2 and the third lens L3 form the first cemented triplet lens group 23A; the fourth lens L4 and the fifth lens L5 form the cemented doublet lens group 21; the sixth lens L6, the seventh lens L7 and the eighth lens L8 form the second cemented triplet lens group 23B; and the ninth lens L9, the tenth lens L10 and the eleventh lens L11 form the third cemented triplet lens group 23C.

[0098] Optionally, at least one of the seventh lens L7, the ninth lens L9, and the eleventh lens L11 has an Abbe number greater than 80.

[0099] Optionally, the refractive index temperature coefficients Dn / Dt of the seventh lens L7 and the ninth lens L9 are less than 0. Both lenses, the seventh lens L7 and the ninth lens L9, which have positive refractive power, are made of materials with low refractive index and negative Dn / Dt. This can effectively compensate for the heat of the entire optical system, so as to ensure that the projection lens does not have a significant impact on the image quality within a certain temperature range.

[0100] 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 satisfy the following relation:

[0101] -4.0≤EFL ZOOM1 / EFL≤-1.5;

[0102] 2.5≤EFL ZOOM2 / EFL≤9.0.

[0103] For example, EFL ZOOM1 The / EFL ratio can be -4.0, -3.8, -3.6, -3.4, -3.2, -3.0, -2.8, -2.6, -2.4, -2.2, -2.0, -1.8, -1.6, or -1.5, etc. Of course, EFL... ZOOM1 The / EFL ratio can also be any combination of the above values.

[0104] For example, EFL ZOOM2 The / EFL ratio can be 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, or 9.0, etc. Of course, EFL... ZOOM2 The / EFL ratio can also be any combination of the above values.

[0105] 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.

[0106] In some embodiments, the magnifying side of the first front lens 11 is concave or convex, and the reducing side of the first front lens 11 is convex; the magnifying side of the second front lens 12 is convex, and the reducing side of the second front lens 12 is concave; both the magnifying and reducing sides of the first lens L1 are concave; both the magnifying and reducing sides of the second lens L2 are convex; the magnifying side of the third lens L3 is concave, and the reducing side of the third lens L3 is convex; the magnifying side of the fourth lens L4 is concave, convex, or flat, and the reducing side of the fourth lens L4 is concave; the fifth lens... Both the magnifying and reducing sides of lens L5 are convex; the magnifying side of the sixth lens L6 is convex, and the reducing side of the sixth lens L6 is concave; both the magnifying and reducing sides of the seventh lens L7 are convex; the magnifying side of the eighth lens L8 is concave, and the reducing side of the eighth lens L8 is convex; both the magnifying and reducing sides of the ninth lens L9 are convex; both the magnifying and reducing sides of the tenth lens L10 are concave; both the magnifying and reducing sides of the eleventh lens L11 are convex; and both the magnifying and reducing sides of the first rear lens 31 are convex.

[0107] In some embodiments, -30mm≤EFL ZOOM1 ≤-20mm, 30mm≤EFL ZOOM2≤70mm; the radius of curvature of the magnifying side of the first front lens 11 is -30mm to 300mm, and the radius of curvature of the reducing side of the first front lens 11 is -180mm to -20mm; the radius of curvature of the magnifying side of the second front lens 12 is 100mm to 180mm, and the radius of curvature of the reducing side of the second front lens 12 is 15mm to 40mm; the radius of curvature of the magnifying side of the first lens L1 is -70mm to -30mm, and the radius of curvature of the reducing side of the first lens L1 is 15mm to 40mm; the magnifying side of the second lens L2... The radius of curvature of the side surface of the first lens L2 is 15mm to 40mm; the radius of curvature of the reducing side surface of the second lens L2 is -40mm to -15mm; the radius of curvature of the magnifying side surface of the third lens L3 is -40mm to -15mm, and the radius of curvature of the reducing side surface of the third lens L3 is -80mm to -25mm; the radius of curvature of the magnifying side surface of the fourth lens L4 is 200mm to ∞ or -∞ to -200mm, and the radius of curvature of the reducing side surface of the fourth lens L4 is 15mm to 40mm; the radius of curvature of the magnifying side surface of the fifth lens L5 is 15mm to 40mm. The radius of curvature of the reducing side of the fifth lens L5 is -100mm to -40mm; the radius of curvature of the magnifying side of the sixth lens L6 is 100mm to 300mm, and the radius of curvature of the reducing side of the sixth lens L6 is 15mm to 40mm; the radius of curvature of the magnifying side of the seventh lens L7 is 15mm to 40mm, and the radius of curvature of the reducing side of the seventh lens L7 is -15mm to -60mm; the radius of curvature of the magnifying side of the eighth lens L8 is -15mm to -60mm, and the radius of curvature of the reducing side of the eighth lens L8 is... The radius of curvature of the magnifying side of the ninth lens L9 is -80mm to -25mm; the radius of curvature of the magnifying side of the ninth lens L9 is -40mm to -15mm; the radius of curvature of the magnifying side of the tenth lens L10 is -40mm to -15mm; the radius of curvature of the reducing side of the tenth lens L10 is 100mm to 300mm; the radius of curvature of the magnifying side of the eleventh lens L11 is 100mm to 300mm; the radius of curvature of the reducing side of the eleventh lens L11 is -50mm to -15mm.

[0108] like Figure 2As shown, in some embodiments, multiple cemented lens groups 20 sequentially include a first cemented doublet lens group 21A, a second cemented doublet lens group 21B, a first cemented triplet lens group 23A, and a second cemented triplet lens group 23B from the magnifying side to the reducing side. A first lens group G1 includes the first cemented doublet lens group 21A and the second cemented doublet lens group 21B, and a second lens group G2 includes the first cemented triplet lens group 23A and the second cemented triplet lens group 23B. The rear lens group 30 further includes a second rear lens 33 disposed between the second cemented triplet lens group 23B and the first rear lens 31, and the second rear lens 33 has positive refractive power. That is, there are two cemented triplet lens groups 23, namely the first cemented triplet lens group 23A and the second cemented triplet lens group 23B; and two cemented doublet lens groups 21, namely the first cemented doublet lens group 21A and the second cemented doublet lens group 21B.

[0109] In some embodiments, in the plurality of cemented lens groups 20, the refractive powers of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as negative, positive, positive, negative, negative, positive, negative, positive, negative and positive, and the refractive indices of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as low refractive index, high refractive index, high refractive index, high refractive index, high refractive index, low refractive index, high refractive index, low refractive index, high refractive index and low refractive index.

[0110] In these embodiments, a lens with a high refractive index refers to a lens with a refractive index greater than 1.80, and a lens with a low refractive index refers to a lens with a refractive index less than 1.80.

[0111] In these embodiments, the combination of the refractive power and refractive index of multiple lenses in the multiple cemented lens groups 20 can effectively correct the system chromatic aberration, and the cancellation of positive and negative spherical aberrations of 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.

[0112] In these embodiments, the plurality of cemented lens groups 20 include a first lens L1 having negative refractive power and low refractive index, a second lens L2 having positive refractive power and high refractive index, a third lens L3 having positive refractive power and high refractive index, a fourth lens L4 having negative refractive power and high refractive index, a fifth lens L5 having negative refractive power and high refractive index, a sixth lens L6 having positive refractive power and low refractive index, a seventh lens L7 having negative refractive power and high refractive index, an eighth lens L8 having positive refractive power and low refractive index, a ninth lens L9 having negative refractive power and high refractive index, and a tenth lens L10 having positive refractive power and low refractive index.

[0113] The first lens L1 and the second lens L2 form a first cemented doublet lens group 21A; the third lens L3 and the fourth lens L4 form a second cemented doublet lens group 21B; the fifth lens L5, the sixth lens L6 and the seventh lens L7 form a first cemented triplet lens group 23A; and the eighth lens L8, the ninth lens L9 and the tenth lens L10 form a second cemented triplet lens group 23B.

[0114] Optionally, at least one of the sixth lens L6, the eighth lens L8, and the tenth lens L10 has an Abbe number greater than 80.

[0115] Optionally, the refractive index temperature coefficients Dn / Dt of the sixth lens L6, the eighth lens L8, and the tenth lens L10 are less than 0. These three lenses with positive refractive power are all made of materials with low refractive index and negative Dn / Dt. This effectively compensates for the heat of the entire optical system, ensuring that the projection lens does not significantly affect image quality within a certain temperature range.

[0116] 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 satisfy the following relation:

[0117] -8.0≤EFL ZOOM1 / EFL≤-4.0;

[0118] 2.0≤EFL ZOOM2 / EFL≤5.0.

[0119] For example, EFL ZOOM1 The / EFL ratio can be -4.0, -4.5, -5.0, -5.5, -6.0, -6.5, -7.0, -7.5, or -8.0, etc. Of course, EFL... ZOOM1 The / EFL ratio can also be any combination of the above values.

[0120] For example, EFL ZOOM2 The / EFL ratio can be 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0, etc. Of course, EFL... ZOOM2 The / EFL ratio can also be any combination of the above values.

[0121] In some embodiments, the magnifying side of the first front lens 11 is concave, and the reducing side of the first front lens 11 is convex; both the magnifying and reducing sides of the second front lens 12 are concave; both the magnifying and reducing sides of the first lens L1 are concave; both the magnifying and reducing sides of the second lens L2 are convex; both the magnifying and reducing sides of the third lens L3 are convex; both the magnifying and reducing sides of the fourth lens L4 are concave; both the magnifying and reducing sides of the fifth lens L5 are concave; both the magnifying and reducing sides of the sixth lens L6 are convex; both the magnifying and reducing sides of the seventh lens L7 are concave, and both the reducing side of the seventh lens L7 are convex; both the magnifying and reducing sides of the eighth lens L8 are convex; both the magnifying and reducing sides of the ninth lens L9 are concave; both the magnifying and reducing sides of the tenth lens L10 are convex; both the magnifying and reducing sides of the second rear lens 33 are concave, and both the reducing side of the second rear lens 33 are convex; both the magnifying and reducing sides of the first rear lens 31 are convex.

[0122] like Figure 3 As shown, in some embodiments, multiple cemented lens groups 20 sequentially include a cemented triplet lens group 23, a first cemented doublet lens group 21A, a second cemented doublet lens group 21B, and a third cemented doublet lens group 21C from the magnifying side to the reducing side. A first lens group G1 includes the cemented triplet lens group 23 and the first cemented doublet lens group 21A, a second lens group G2 includes the second cemented doublet lens group 21B and the third cemented doublet lens group 21C, and a rear lens group 30 further includes a second rear lens 33 disposed between the third cemented doublet lens group 21C and the first rear lens 31. The second rear lens 33 has positive refractive power. That is, there is one cemented triplet lens group 23; and three cemented doublet lens groups 21, namely the first cemented doublet lens group 21A, the second cemented doublet lens group 21B, and the third cemented doublet lens group 21C.

[0123] In some embodiments, in the plurality of cemented lens groups 20, the refractive powers of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as negative, positive, negative, negative, positive, positive, negative, positive and negative; the refractive indices of the plurality of lenses are arranged sequentially from the magnifying side to the reducing side as low refractive index, low refractive index, high refractive index, high refractive index, low refractive index, low refractive index, high refractive index, low refractive index and high refractive index.

[0124] In these embodiments, a lens with a high refractive index refers to a lens with a refractive index greater than 1.80, and a lens with a low refractive index refers to a lens with a refractive index not greater than 1.80.

[0125] In these embodiments, the combination of the refractive power and refractive index of multiple lenses in the multiple cemented lens groups 20 can effectively correct the system chromatic aberration, and the cancellation of positive and negative spherical aberrations of 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.

[0126] In these embodiments, the plurality of cemented lens groups 20 include a first lens L1 having negative refractive power and low refractive index, a second lens L2 having positive refractive power and low refractive index, a third lens L3 having negative refractive power and high refractive index, a fourth lens L4 having negative refractive power and high refractive index, a fifth lens L5 having positive refractive power and low refractive index, a sixth lens L6 having positive refractive power and low refractive index, a seventh lens L7 having negative refractive power and high refractive index, an eighth lens L8 having positive refractive power and low refractive index, and a ninth lens L9 having negative refractive power and high refractive index.

[0127] Among them, the first lens L1, the second lens L2 and the third lens L3 form a cemented triplet lens group 23; the fourth lens L4 and the fifth lens L5 form a first cemented doublet lens group 21A; the sixth lens L6 and the seventh lens L7 form a second cemented doublet lens group 21B; and the eighth lens L8 and the ninth lens L9 form a third cemented doublet lens group 21C.

[0128] Optionally, at least one of the first lens L2, the fifth lens L5, the sixth lens L6, and the eighth lens L8 has an Abbe number greater than 80.

[0129] Optionally, the refractive index temperature coefficients Dn / Dt of the fifth lens L5, the sixth lens L6, and the eighth lens L8 are less than 0. These three lenses with positive refractive power are all made of materials with low refractive index and negative Dn / Dt. This effectively compensates for the heat of the entire optical system, ensuring that the projection lens does not significantly affect image quality within a certain temperature range.

[0130] In some embodiments, 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:

[0131] -8.0≤EFL ZOOM1 / EFL≤-4.0;

[0132] 2.0≤EFL ZOOM2 / EFL≤5.0.

[0133] For example, EFL ZOOM1The / EFL ratio can be -4.0, -4.5, -5.0, -5.5, -6.0, -6.5, -7.0, -7.5, or -8.0, etc. Of course, EFL... ZOOM1 The / EFL ratio can also be any combination of the above values.

[0134] For example, EFL ZOOM2 The / EFL ratio can be 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0, etc. Of course, EFL... ZOOM2 The / EFL ratio can also be any combination of the above values.

[0135] In some embodiments, the magnifying side of the first front lens 11 is concave, and the reducing side of the first front lens 11 is convex; both the magnifying and reducing sides of the second front lens 12 are concave; both the magnifying and reducing sides of the first lens L1 are convex; both the magnifying and reducing sides of the second lens L2 are concave; both the magnifying and reducing sides of the third lens L3 are convex; both the magnifying and reducing sides of the fourth lens L4 are concave; both the magnifying and reducing sides of the fifth lens L5 are convex; both the magnifying and reducing sides of the sixth lens L6 are convex; both the magnifying and reducing sides of the seventh lens L7 are concave; both the magnifying and reducing sides of the eighth lens L8 are convex; both the magnifying and reducing sides of the ninth lens L9 are concave, and both the reducing side of the ninth lens L9 are convex; both the magnifying and reducing sides of the second rear lens 33 are convex; and both the magnifying and reducing sides of the first rear lens 31 are convex.

[0136] 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.

[0137] 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.

[0138] The technical solution of this application will be further described below with reference to the embodiments.

[0139] Example 1

[0140] The projection lens of Embodiment 1, from the magnifying side to the reducing side, includes, in sequence, a first front lens 11, a second front lens 12, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a first rear lens 31, a galvanometer 40, a prism 50, a beam splitter PBS, and a liquid crystal on silicon (LCOS) chip 60.

[0141] The relevant parameters of each component are shown in Table 1 and Table 2.

[0142] Table 1

[0143]

[0144]

[0145] Among them, surfaces 1 to 27 are arranged sequentially from the enlarged side to the reduced side.

[0146] Table 2

[0147] surface k <![CDATA[α1]]> <![CDATA[α2]]> <![CDATA[α3]]> <![CDATA[α4]]> <![CDATA[α5]]> <![CDATA[α6]]> <![CDATA[α7]]> 1 0 3.1E-04 -2.1E-06 1.2E-08 -4.4E-11 1.1E-13 -1.5E-16 9.2E-20 2 0 2.8E-04 -8.2E-07 -7.0E-09 1.2E-10 -7.6E-13 2.2E-15 -2.4E-18

[0148] Among them, surface 1 is the magnified side of the first front lens 11, surface 2 is the reduced side of the first front lens 11, and the data of α8 is 0.

[0149] Example 1 provides a projection lens with an aperture of F2.5, distortion less than 0.5%, and a back focal length to effective focal length ratio (BFL / EFL) ≥ 5. This lens has a precise structure, achieving a low-cost, compact imaging lens. The above projection lens forms an 80-inch diagonal image at a projection distance of 2125mm. This application is based on the principle of optical imaging. Using optical design software, the curvature radius, material, thickness, and air gap of each lens in the projection lens are repeatedly optimized. This optimization also includes the design of a resin aspherical lens, a cemented doublet lens, and three cemented triplet lenses. The result is a lens with low aberrations, high resolution, simple structure, ingenious design, high manufacturability, and ease of mass production.

[0150] Example 2

[0151] The projection lens of Embodiment 2, from the magnifying side to the reducing side, includes, in sequence, a first front lens 11, a second front lens 12, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, 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 second rear lens 33, a first rear lens 31, a galvanometer 40, a prism 50, and a liquid crystal on silicon (LCOS) chip 60.

[0152] The relevant parameters of each component are shown in Tables 3 and 4.

[0153] Table 3

[0154]

[0155] Among them, surfaces 1 to 28 are arranged sequentially from the enlarged side to the reduced side.

[0156] Table 4

[0157]

[0158]

[0159] Among them, surface 1 is the magnified side of the first front lens 11, surface 2 is the reduced side of the first front lens 11, and the data of α8 is 0.

[0160] Example 2 provides a projection lens with an aperture of F2.5, distortion less than 0.5%, and a back focal length to effective focal length ratio (BFL / EFL) ≥ 5. This lens has a precise structure, achieving a low-cost, compact imaging lens. The above projection lens forms an 80-inch diagonal image at a projection distance of 2125mm. This application is based on the principle of optical imaging. Using optical design software, the curvature radius, material, thickness, and on-axis spacing of each lens in the projection lens are repeatedly optimized. This optimization also includes the design of one resin aspherical lens, two cemented triplicate lenses, and two cemented doublet lenses, achieving low aberrations, high resolution, simple structure, ingenious design, high manufacturability, and ease of mass production.

[0161] Example 3

[0162] The projection lens of Embodiment 3, from the magnifying side to the reducing side, includes, in sequence, a first front lens 11, a second front lens 12, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a second rear lens 33, a first rear lens 31, a galvanometer 40, a prism 50, a beam splitter PBS, and a liquid crystal on silicon (LCOS) chip 60.

[0163] The relevant parameters of each component are shown in Tables 5 and 6.

[0164] Table 5

[0165]

[0166]

[0167] Among them, surfaces 1 to 27 are arranged sequentially from the enlarged side to the reduced side.

[0168] Table 6

[0169] surface k <![CDATA[α1]]> <![CDATA[α2]]> <![CDATA[α3]]> <![CDATA[α4]]> <![CDATA[α5]]> <![CDATA[α6]]> <![CDATA[α7]]> 1 -1 2.98E-04 -1.67E-06 6.87E-09 -1.92E-11 3.45E-14 -3.62E-17 1.69E-20 2 0 2.50E-04 -6.20E-07 -3.42E-09 3.99E-11 -1.62E-13 3.05E-16 -2.23E-19

[0170] Among them, surface 1 is the magnified side of the first front lens 11, surface 2 is the reduced side of the first front lens 11, and the data of α8 is 0.

[0171] Example 3 provides a projection lens with an aperture of F2.5, distortion less than 0.5%, and a back focal length to effective focal length ratio (BFL / EFL) ≥ 5. This lens has a precise structure, achieving a low-cost, compact imaging lens. The above projection lens forms an 80-inch diagonal image at a projection distance of 2125mm. This application is based on the principle of optical imaging. Using optical design software, the curvature radius, material, thickness, and on-axis spacing of each lens in the projection lens are repeatedly optimized. This optimization also includes the design of a resin aspherical lens, a cemented triplet lens, and three cemented doublet lenses, achieving low aberrations, high resolution, simple structure, ingenious design, high manufacturability, and ease of mass production.

[0172] 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, The multiple lenses include, in order from the magnification side to the reduction side, a first lens group having a negative refractive power and a second lens group having a positive refractive power. The first lens group includes, in order from the magnification side to the reduction side, a front lens group and at least one cemented lens group, and the front lens group includes, in order from the magnification side to the reduction side, a first front lens having a negative refractive power and a second front lens having a negative refractive power. The second lens group includes, in order from the magnification side to the reduction side, at least one cemented lens group and a rear lens group, and the rear lens group includes a first rear lens having a positive refractive power. Adjacent two lenses in each of the cemented lens groups have a refractive index difference, and the multiple cemented lens groups include a double cemented lens group and a triple cemented lens group. The projection lens has an effective focal length EFL, a back focal length BFL, and a total track length TTL, and in the multiple lenses, the number of lenses having a positive refractive power and an Abbe number greater than 80 is H, and at least one of the following relationships is satisfied: TTL / EFL≤20; BFL / EFL≥5; 4≥H≥1。 2. The projection lens according to claim 1, characterized in that The first lens is an aspherical lens, or / and the first lens is a resin lens.

3. The projection lens of claim 1, wherein The triple cemented lens group is provided with M, and the double cemented lens group is provided with N, and the following relationship is satisfied: 3≥M≥1； 4≥N≥2； N+M≥3.

4. The projection lens of claim 1, wherein The second lens group is provided with at least two lenses having a refractive index greater than 1.

8.

5. The projection lens of claim 1, wherein The second lens group includes X lenses having a positive refractive power and a refractive index temperature coefficient Dn / Dt, and the following relationship is satisfied: Dn / Dt<0, 4≥X≥1.

6. The projection lens according to claim 1 or 5, characterized in that The multiple cemented lens groups include, in order from the magnification side to the reduction side, a first triple cemented lens group, a double cemented lens group, a second triple cemented lens group, and a third triple cemented lens group, the first lens group includes the first triple cemented lens group, and the second lens group includes the double cemented lens group, the second triple cemented lens group, and the third triple cemented lens group.

7. The projection lens of claim 6, wherein, In the multiple cemented lens groups, the refractive powers of the multiple lenses are arranged in order from the magnification side to the reduction side as negative, positive, negative, negative, positive, negative, positive, negative, positive, negative, and positive, and the refractive indices of the multiple lenses are arranged in order from the magnification side to the reduction side as low refractive index, high refractive index, high refractive index, low refractive index, high refractive index, high refractive index, low refractive index, high refractive index, low refractive index, high refractive index, and low refractive index; or / and, a focal length of the first lens group is EFL ZOOM1 a focal length of the second lens group is EFL ZOOM2 and the following relation is satisfied: - 4.0 < EFL ZOOM1 EFL < -1.5; 2.5 < EFL ZOOM2 / EFL < 9.

0.

8. The projection lens according to claim 1 or 5, characterized in that, The multiple cemented lens groups include, in order from the magnification side to the reduction side, a first double cemented lens group, a second double cemented lens group, a first triple cemented lens group, and a second triple cemented lens group, the first lens group includes the first double cemented lens group and the second double cemented lens group, the second lens group includes the first triple cemented lens group and the second triple cemented lens group, and the rear lens group further includes a second rear lens provided between the second triple cemented lens group and the first rear lens, and the second rear lens has a positive refractive power.

9. The projection lens of claim 8, wherein, In the plurality of cemented lens groups, powers of the plurality of lenses are arranged in order from the magnifying side to the reducing side as negative, positive, positive, negative, negative, positive, negative, positive, negative, and positive, and refractive indexes of the plurality of lenses are arranged in order from the magnifying side to the reducing side as low refractive index, high refractive index, high refractive index, high refractive index, high refractive index, low refractive index, high refractive index, low refractive index, high refractive index, and low refractive index; or / and, a focal length of the first lens group is EFL ZOOM1 a focal length of the second lens group is EFL ZOOM2 and the following relation is satisfied: -8.0 < EFL ZOOM1 / EFL < -4.0; 2.0 < EFL ZOOM2 / EFL < 5.

0.

10. The projection lens according to claim 1 or 5, characterized in that, The plurality of cemented lens groups comprises in order from the magnifying side to the reducing side a first triple cemented lens group, a first double cemented lens group, a second double cemented lens group, and a third double cemented lens group, the first lens group comprises the first triple cemented lens group and the first double cemented lens group, the second lens group comprises the second double cemented lens group and the third double cemented lens group, and the rear lens group further comprises a second rear lens arranged between the third double cemented lens group and the first rear lens, the second rear lens having positive refractive power.

11. The projection lens of claim 10, wherein, In the plurality of cemented lens groups, powers of the plurality of lenses are arranged in order from the magnifying side to the reducing side as positive, negative, positive, negative, positive, positive, negative, positive, and negative; and refractive indexes of the plurality of lenses are arranged in order from the magnifying side to the reducing side as low refractive index, low refractive index, high refractive index, high refractive index, low refractive index, low refractive index, high refractive index, low refractive index, and high refractive index; or / and, a focal length of the first lens group is EFL ZOOM1 a focal length of the second lens group is EFL ZOOM2 and the following relation is satisfied: -8.0 < EFL ZOOM1 / EFL < -4.0; 2.0 < EFL ZOOM2 / EFL < 5.

0.

12. The projection lens of claim 1, wherein, The projection lens satisfies at least one of the following relationships: 9.5mm≤EFL≤10.5mm; TTL≤180mm; BFL≥58mm; The projection lens has an F-number FNO, and FNO≤2.5; The projection lens has a distortion less than 0.5%; The projection lens has a field of view angle ≧64°; The projection lens has a telecentric angle TA, and TA≤1.0; The projection lens has a projection distance to picture width ratio TR, and 1.0≤TR≤1.2; Each of the lenses has a diameter not greater than 36mm.

13. A projection system, characterized by The projection lens of any one of claims 1-12.

14. A projection apparatus, characterized by comprising: The projection system of claim 13.

Images