Projection lens

Abstract

The invention belongs to the technical field of projection, and discloses a projection lens, which comprises a lens assembly I with negative focal power, a lens assembly II with positive or negative focal power and a lens assembly III with positive focal power, which are arranged from an amplification side to a reduction side, the second lens assembly is a zoom group and comprises a first zoom lens group, a second zoom lens group and a third zoom lens group which are arranged from the magnification side to the reduction side and independently move along the optical axis, and the element, closest to the reduction side, in the third zoom lens group is a diaphragm. The projection lens is optimally designed, so that a larger back focal length space can be provided, clear full-frame imaging and uniform frame illumination are ensured, and the projection lens has the advantages of long back focal length, high brightness, low chromatic aberration, low distortion and high imaging quality.

Description

Technical Field

[0001] This invention belongs to the field of projection technology, and in particular relates to a projection lens. Background Technology

[0002] Projection displays are now widely used in near-eye displays (AR-Glass), home projection, and commercial projection. Existing projection technologies include DLP, LCOS, LCD, and LBS. LCOS display is a reflective display technology that organically combines LCD and CMOS integrated circuits. As a new type of display device, LCOS has many advantages such as large screen size, high brightness, high resolution, and energy saving. Compared to DLP projection technology, LCOS selects light through its own polarization characteristics, and its contrast ratio can now reach several thousand or even tens of thousands.

[0003] However, when the LCOS light-combining system is applied to a lens, the lens's back focal length increases, which increases the design difficulty of the lens and makes it difficult to guarantee clear full-frame imaging and uniform image illumination. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention discloses a projection lens that provides a larger back focal length space to ensure clear full-frame imaging and uniform screen illumination, and has the advantages of long back focal length, high brightness, low chromatic aberration, low distortion, and high image quality.

[0005] The specific technical solution of the present invention is as follows:

[0006] A projection lens includes a lens assembly 1 with negative optical power, a lens assembly 2 with positive or negative optical power, and a lens assembly 3 with positive optical power, arranged from the magnification side to the reduction side.

[0007] The second lens assembly is a zoom group, which includes zoom lens group one, zoom lens group two, and zoom lens group three, each independently movable along the optical axis from the magnification side to the reduction side. The element closest to the reduction side in zoom lens group three is the aperture stop.

[0008] The projection lens satisfies at least one of the following conditions:

[0009] Magnification ratio ≥ 1.5;

[0010] The number of lenses with a positive focal length and an Abbe number greater than 80 is ≤ 4.

[0011] 1≤N1≤4, and / or 1≤N2≤5, where N1 is the number of cemented triplet lenses and N2 is the number of cemented doublet lenses;

[0012] BFL / TTL≥0.2, where BFL is the back focal length of the projection lens and TTL is the total length of the projection lens.

[0013] The lens architecture proposed in this application can significantly improve the overall performance of the lens under the condition of long back focal length (i.e., the distance of light from the rear principal plane of the lens to the imaging plane is long or the distance from the last lens element to the chip is long), so as to meet the growing demand for high-quality imaging. In other words, this application effectively solves the problems of insufficient brightness, significant chromatic aberration, and large distortion commonly found in traditional long back focal length lenses, thereby bringing users a clearer, more accurate, and more natural visual experience.

[0014] Preferably, the projection lens satisfies the following conditions:

[0015] TTL5 / TTL>0.4, where TTL5 is the length from the lens closest to the magnification side in the third lens assembly to the projection lens chip.

[0016] By properly configuring the ratio between the back focal length of lens assembly three and the total length of the projection lens, the brightness of the projection lens can be significantly improved, color difference and distortion can be effectively reduced, thereby obtaining a better high-quality image.

[0017] Preferably, the projection ratio of the projection lens is continuously variable from 1.2 to 2.1;

[0018] When the projection ratio is 1.2, TTL / EFL ≤ 25; when the projection ratio is 1.9, TTL / EFL ≥ 14.

[0019] When the projection ratio is 1.3, TTL / EFL ≤ 20; when the projection ratio is 2.1, TTL / EFL ≥ 11.

[0020] Here, EFL is the effective focal length of the projection lens.

[0021] By rationally configuring the ratio between the total length of the projection lens and the effective focal length of the projection lens, it is possible to achieve a continuously variable throw ratio while miniaturizing and lightening the lens and maintaining high image quality.

[0022] Preferably, the focal length relationship between each lens assembly and the projection lens in lens assembly one, lens assembly two, and lens assembly three is as follows:

[0023] -4.5 < EFL1 / EFL < -1;

[0024] 3.6 < EFL2 / EFL < 45;

[0025] 3.1 < EFL3 / EFL < 8.5;

[0026] -25 < EFL4 / EFL < -4;

[0027] 2 < EFL5 / EFL < 4;

[0028] Wherein, EFL1 is the effective focal length of lens assembly 1, EFL2 is the effective focal length of zoom lens group 1, EFL3 is the effective focal length of zoom lens group 2, EFL4 is the effective focal length of zoom lens group 3, EFL5 is the effective focal length of lens assembly 3, and EFL is the effective focal length of the projection lens.

[0029] In this application, by optimizing the ratio of the effective focal lengths between each lens assembly and the projection lens, an appropriate focal length relationship is established between the two, which helps to meet the requirements of a simple and compact structure and low cost based on a large aperture and a long back focal length. At the same time, it has the advantages of high brightness, low distortion, and improved projection image quality.

[0030] Preferably, the focal length relationships between each lens assembly and the projection lens in lens assembly 1, lens assembly 2, and lens assembly 3 are as follows:

[0031] -4 < EFL1 / EFL < -2; 7 < EFL2 / EFL < 14; 4.5 < EFL3 / EFL < 8.5; -25 < EFL4 / EFL < -13; 2 < EFL5 / EFL < 4; or

[0032] -4.5 < EFL1 / EFL < -2.5; 15 < EFL2 / EFL < 45; 4.5 < EFL3 / EFL < 8.5; -10 < EFL4 / EFL < -4; 2 < EFL5 / EFL < 4; or

[0033] -2.1 < EFL1 / EFL < -1.0; 3.6 < EFL2 / EFL < 8.1; 3.1 < EFL3 / EFL < 6.3; -16 < EFL4 / EFL < -8; 2 < EFL5 / EFL < 4.

[0034] When the projection lens has different architecture designs, optimizing the ratio of the effective focal lengths between each lens assembly and the projection lens to appropriate conditions can well meet the specific effects.

[0035] Preferably, the projection lens adopts a lens architecture one, wherein the lens assembly one includes a lens with negative refractive power one, a lens with negative refractive power two, a lens with positive refractive power three, and a lens with negative refractive power four, arranged from the magnification side to the reduction side; the zoom lens group one includes a lens with positive refractive power five; the zoom lens group two includes a lens with negative refractive power six, a lens with positive refractive power seven, and a lens with positive refractive power eight, arranged from the magnification side to the reduction side; the zoom lens group three includes a lens with negative refractive power nine, a lens with positive refractive power ten, arranged from the magnification side to the reduction side; and the lens assembly three includes a lens with positive refractive power eleven, a lens with negative refractive power twelve, a lens with positive refractive power thirteen, a lens with negative refractive power fourteen, a lens with positive refractive power fifteen, a lens with negative refractive power sixteen, a lens with positive refractive power seventeen, and a lens with positive refractive power eighteen, arranged from the magnification side to the reduction side.

[0036] Alternatively, the projection lens adopts lens architecture two, wherein lens assembly one includes a lens with negative diopter 1, a lens with negative diopter 2, a lens with positive diopter 3, a lens with positive diopter 4, and a lens with negative diopter 5 arranged from the magnification side to the reduction side; zoom lens group one includes a lens with positive diopter 6; zoom lens group two includes a lens with negative diopter 7, a lens with positive diopter 8, and a lens with positive diopter 9 arranged from the magnification side to the reduction side; zoom lens group three includes a lens with negative diopter 10 and a lens with positive diopter 11 arranged from the magnification side to the reduction side; and lens assembly three includes a lens with negative diopter 12, a lens with positive diopter 13, a lens with negative diopter 14, a lens with positive diopter 15, a lens with negative diopter 16, a lens with positive diopter 17, and a lens with positive diopter 18 arranged from the magnification side to the reduction side.

[0037] Alternatively, the projection lens adopts lens architecture three, wherein lens assembly one includes a lens with negative refractive power one, a lens with negative refractive power two, a lens with positive refractive power three, a lens with positive refractive power four, and a lens with negative refractive power five, arranged from the magnification side to the reduction side; zoom lens group one includes a lens with positive refractive power six; zoom lens group two includes a lens with negative refractive power seven, a lens with positive refractive power eight, a lens with positive refractive power nine, and a lens with positive refractive power nine, arranged from the magnification side to the reduction side. The zoom lens group three includes a lens 11 with negative diopter and a lens 12 with positive diopter, arranged from the magnification side to the reduction side; the lens assembly three includes a lens 13 with negative diopter, a lens 14 with negative diopter, a lens 15 with positive diopter, a lens 16 with negative diopter, a lens 17 with positive diopter, a lens 18 with negative diopter, a lens 19 with positive diopter, and a lens 20 with positive diopter, arranged from the magnification side to the reduction side.

[0038] In this application, lens assembly one is used for focusing, lens assembly two is used for zooming, and lens assembly three is a fixed lens assembly. With the above-mentioned lens composition, it has excellent imaging capabilities, which can significantly improve the clarity and quality of the image, while achieving a high degree of structural compactness. In addition, it realizes a high-performance continuous zoom function, which allows seamless adjustment of the screen size within the same projection distance to meet diverse display needs.

[0039] Preferably, in lens architecture one, lens two, lens three, and lens four are connected to form a cemented triplet lens, wherein the refractive index of lens two is less than that of lens three, the Abbe number of lens two is greater than that of lens three, the refractive index of lens three is less than that of lens four, and the Abbe number of lens three is greater than that of lens four; lens nine and lens ten are connected to form a cemented doublet lens, wherein the refractive index of lens nine is less than that of lens ten, and the Abbe number of lens nine is greater than that of lens ten; lens twelve, lens thirteen, and lens fourteen are connected to form a cemented triplet lens, wherein the refractive index of lens twelve is greater than that of lens thirteen, the Abbe number of lens twelve is less than that of lens thirteen, the refractive index of lens thirteen is less than that of lens fourteen, and the Abbe number of lens thirteen is greater than that of lens fourteen; and lens sixteen and lens seventeen are connected to form a cemented doublet lens, wherein the refractive index of lens sixteen is greater than that of lens seventeen, and the Abbe number of lens sixteen is less than that of lens seventeen.

[0040] In lens architecture two, lens elements two and three are connected to form a cemented doublet lens, where the refractive index of lens element two is less than that of lens element three, and the Abbe number of lens element two is greater than that of lens element three; lens elements four and five are connected to form a cemented doublet lens, where the refractive index of lens element four is less than that of lens element five, and the Abbe number of lens element four is greater than that of lens element five; lens elements seven and eight are connected to form a cemented doublet lens, where the refractive index of lens element seven is greater than that of lens element eight, and the Abbe number of lens element seven is less than that of lens element eight; lens elements ten and eleven are connected to form a cemented doublet lens, where the refractive index of lens element ten is less than that of lens element three, and the refractive index of lens element ten is less than that of lens element three, and the refractive index of lens element four is greater than that of lens element three, and the refractive index of lens element four is greater than that of lens element three, and the refractive index of lens element four is greater than that of lens element three, and the Abbe number ... Abbe number of lens element four is greater than that of lens element three, and the Abbe number of lens element four is greater than that of lens element three, and the Abbe number of lens element four is greater than that of lens element three, and the Abbe number of lens element four is greater than that of The refractive index of lens 10 is less than that of lens 11, and the Abbe number of lens 10 is greater than that of lens 11; lenses 12, 13, and 14 are connected to form a cemented triode lens, where the refractive index of lens 12 is greater than that of lens 13, the Abbe number of lens 12 is less than that of lens 13, the refractive index of lens 13 is less than that of lens 14, and the Abbe number of lens 13 is greater than that of lens 14; lenses 15 and 16 are connected to form a cemented bilayer lens, where the refractive index of lens 15 is less than that of lens 16, and the Abbe number of lens 15 is greater than that of lens 16.

[0041] In lens architecture three, lens two and lens three are connected to form a cemented doublet lens, where the refractive index of lens two is less than that of lens three, and the Abbe number of lens two is greater than that of lens three; lens four and lens five are connected to form a cemented doublet lens, where the refractive index of lens four is less than that of lens five, and the Abbe number of lens four is greater than that of lens five; lens eleven and lens twelve are connected to form a cemented doublet lens, where the refractive index of lens eleven is less than that of lens twelve, and the Abbe number of lens eleven is greater than that of lens twelve; lens fourteen, lens fifteen, and lens sixteen are connected to form a cemented triplicate lens, where the refractive index of lens fourteen is greater than that of lens fifteen, and the Abbe number of lens fourteen is less than that of lens fifteen; the refractive index of lens sixteen is greater than that of lens fifteen, and the Abbe number of lens sixteen is less than that of lens fifteen; lens eighteen and lens nineteen are connected to form a cemented doublet lens, where the refractive index of lens eighteen is greater than that of lens nineteen, and the Abbe number of lens eighteen is less than that of lens nineteen.

[0042] Preferably, the lens assembly three includes a lens eleven with positive diopter, a lens twelfth with negative diopter, a lens thirteenth with positive diopter, a lens fourteenth with negative diopter, a lens fifteenth with positive diopter, a lens sixteenth with negative diopter, a lens seventeenth with positive diopter, a lens eighteenth with negative diopter, and a lens nineteenth with positive diopter, arranged from the magnification side to the reduction side.

[0043] By optimizing the lens composition of lens assembly three, imaging capabilities can be significantly improved, image clarity and quality can be greatly enhanced, and a high degree of structural compactness can be achieved. In addition, a high-performance continuous zoom function is realized, allowing seamless adjustment of the screen size within the same projection distance to meet diverse display needs.

[0044] Preferably, the lenses sixteen, seventeen, and eighteen are connected to form a cemented triplet lens. The refractive index of the lens sixteen is greater than that of the lens seventeen, the Abbe number of the lens sixteen is less than that of the lens seventeen, the refractive index of the lens eighteen is greater than that of the lens seventeen, and the Abbe number of the lens eighteen is less than that of the lens seventeen.

[0045] By optimizing the design of the cemented lens composed of the lenses in lens assembly three, chromatic aberration is eliminated and the system spherical aberration of the projection lens is corrected.

[0046] Preferably, the lens closest to the magnifying side is a meniscus lens and is an aspherical lens.

[0047] Meniscus lenses can effectively reduce aberrations and improve focusing ability, thereby effectively optimizing imaging; aspherical lenses can be used to correct distortion and astigmatism, and effectively correct field curvature.

[0048] Preferably, in lens architecture two, lens nine is an aspherical lens.

[0049] Aspherical lenses can be used to correct distortion and astigmatism, effectively correcting field curvature.

[0050] Preferably, the diameter of all lenses is less than 30mm, or the diameter of all lenses is less than 32mm.

[0051] The smaller lens diameter makes the entire projection lens more compact, making it easier to carry and move; smaller diameter lenses may be more economical in terms of material use and processing, thereby reducing the overall manufacturing cost of the lens; based on the optimized design of this application, it helps to maintain the brightness and clarity of the projected image and reduce light loss.

[0052] Preferably, the ratio between the back focal length of the projection lens and the effective focal length of the projection lens is BFL / EFL≥5.

[0053] Optimizing the ratio between the back focal length and the effective focal length of a projection lens can improve the flexibility of lens design, enhance optical performance, and increase the compactness of the lens design.

[0054] Preferably, the lens assembly three includes 1 to 4 lenses with positive diopter and is made of a material with negative dn / dt.

[0055] Here, dn / dt represents the derivative of the refractive index (n) with respect to temperature (t).

[0056] Lenses with positive diopter can converge light, while materials with negative dn / dt can avoid image blurring and distortion caused by temperature changes, thus maintaining color stability and accuracy. This helps to keep the lens focal length relatively stable when the temperature changes, thereby ensuring high-quality projection effects in different working environments.

[0057] Preferably, the lens assembly three includes no fewer than four lenses with a refractive index greater than 1.8;

[0058] The lens assembly three includes at least one lens with a refractive index greater than 1.8 and a positive diopter.

[0059] The higher the refractive index, the thinner the edge thickness of the lens. This can significantly reduce the lens thickness, making the lens lighter and more portable, while also providing high light transmittance and reducing energy loss, thereby improving projection efficiency and reducing production costs. By optimizing the lens composition of the lens assembly, aberrations can also be effectively reduced, sharpness can be improved, and image quality can be guaranteed.

[0060] Preferably, it also includes a silicon-based liquid crystal disposed near the reduced side of the lens assembly three, the silicon-based liquid crystal being offset relative to the optical axis.

[0061] When the projector is working, the emitted image is offset so that the emitted beam is higher than the position of the projection lens, thus preventing the projected image from being blocked by the projection lens.

[0062] Compared with existing technologies, this invention can achieve continuous zoom and a long back focal length of the projection lens, effectively improving brightness, reducing chromatic aberration, and reducing distortion to meet the design requirements of high imaging quality. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the projection lens in Embodiment 1 of the present invention;

[0064] Figure 2 This is a schematic diagram of the projection lens in Embodiment 3 of the present invention;

[0065] Figure 3 This is a schematic diagram of the projection lens in Embodiment 4 of the present invention.

[0066] In the diagram: G1 - Lens assembly 1; G2 - Lens assembly 2; G21 - Zoom lens group 1; G22 - Zoom lens group 2; G23 - Zoom lens group 3; G3 - Lens assembly 3; L1 - Lens 1; L2 - Lens 2; L3 - Lens 3; L4 - Lens 4; L5 - Lens 5; L6 - Lens 6; L7 - Lens 7; L8 - Lens 8; L9 - Lens 9; L10 - Lens 10; L11 - Lens 11; L12 - Lens 12; L13 - Lens 13; L14 - Lens 14; L15 - Lens 15; L16 - Lens 16; L17 - Lens 17; L18 - Lens 18; L19 - Lens 19; L20 - Lens 20; 1 - Galvanometer; 2 - Prism; 3 - Polarizing beam splitter; 4 - Liquid crystal on silicon. Detailed Implementation

[0067] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0068] This application discloses a projection lens that can achieve continuous zoom and a long back focal length, effectively improving brightness, reducing chromatic aberration, and reducing distortion to meet the design requirements of high imaging quality. The projection lens includes a lens assembly G1 with negative optical power, a lens assembly G2 with positive or negative optical power, and a lens assembly G3 with positive optical power, arranged from the magnification side to the reduction side. The lens assembly G2 is a zoom group, which includes zoom lens group G21, zoom lens group G22, and zoom lens group G23, each independently movable along the optical axis, arranged from the magnification side to the reduction side. The element closest to the reduction side in zoom lens group G23 is the aperture stop. The projection lens satisfies at least one of the following conditions: zoom ratio ≥ 1.5; number of lenses with positive focal length and Abbe number > 80 ≤ 3; 1 ≤ N1 ≤ 4, and / or 1 ≤ N2 ≤ 5, where N1 is the number of cemented triplet lenses and N2 is the number of cemented doublet lenses; BFL / TTL ≥ 0.2, where BFL is the back focal length of the projection lens and TTL is the total length of the projection lens. Furthermore, in this application, the projection lens satisfies the following condition: TTL5 / TTL>0.4, where TTL5 is the length from the lens closest to the magnification side in the lens assembly three to the projection lens chip.

[0069] In this application, the projection ratio of the projection lens is continuously variable from 1.2 to 2.1. The focal length relationships between each lens assembly (G1), lens assembly (G2), and lens assembly (G3) and the projection lens are as follows: -4.5 < EFL1 / EFL < -1; 3.6 < EFL2 / EFL < 45; 3.1 < EFL3 / EFL < 8.5; -25 < EFL4 / EFL < -4; 2 < EFL5 / EFL < 4; where EFL1 is the effective focal length of lens assembly (G1), EFL2 is the effective focal length of zoom lens group (G21), EFL3 is the effective focal length of zoom lens group (G22), EFL4 is the effective focal length of zoom lens group (G23), EFL5 is the effective focal length of lens assembly (G3), and EFL is the effective focal length of the projection lens.

[0070] Example 1

[0071] Based on the above, in Embodiment 1, the lens assembly G1 includes a negative diopter lens L1, a negative diopter lens L2, a positive diopter lens L3, and a negative diopter lens L4, arranged from the magnification side to the reduction side; the zoom lens group G21 includes a positive diopter lens L5; the zoom lens group G22 includes a negative diopter lens L6, a positive diopter lens L7, and a positive diopter lens L8, arranged from the magnification side to the reduction side; and the zoom lens group G23 includes a negative diopter lens L6, a positive diopter lens L7, and a positive diopter lens L8, arranged from the magnification side to the reduction side. Lens assembly 3G3 includes a lens assembly consisting of a lens assembly with negative diopter (L9) and a lens assembly with positive diopter (L10); the lens assembly comprises a lens assembly with positive diopter (L11), a lens assembly with negative diopter (L12), a lens assembly with positive diopter (L13), a lens assembly with negative diopter (L14), a lens assembly with positive diopter (L15), a lens assembly with negative diopter (L16), a lens assembly with positive diopter (L17), and a lens assembly with positive diopter (L18), arranged from the magnification side to the reduction side; lens assembly 1L1 is a meniscus lens convex towards the magnification side; lens assembly 1L1 is an aspherical lens. Zoom lens group 1G21 is a front focusing group, enabling clear image formation under different object distances; zoom lens group 2G22 is a zoom group, enabling different image sizes to be adjusted under the same object distance; zoom lens group 3G23 is a fixed group, further compensating for aberrations in the entire system.

[0072] In this embodiment, the three lens assemblies have a negative-positive-positive diopter configuration. Lens assembly one (G1) is for focusing, lens assembly two (G2) is for zooming, and lens assembly three (G3) is a fixed lens to ensure a long working distance for the projection lens. Specifically, lens one (L1) is a meniscus lens convex towards the magnification side and is an aspherical lens, used to correct distortion and astigmatism, effectively correcting field curvature. Lens one (L1) is made of resin, which has advantages such as being lightweight, impact-resistant, having high light transmittance, simple processing, and low cost. By optimizing the aspherical coefficient of lens one (L1), off-axis aberrations and distortions can be effectively corrected. Lens 2 L2 is a biconcave lens, lens 3 L3 is a biconvex lens, lens 4 L4 is a biconcave lens, lens 5 L5 is a plano-convex lens, lens 6 L6 is a biconcave lens, lens 7 L7 is a concave-convex lens, lens 8 L8 is a biconvex lens, lens 9 L9 is a biconcave lens, lens 10 L10 is a biconvex lens, lens 11 L11 is a concave-plano lens, lens 12 L12 is a plano-concave lens, lens 13 L13 is a biconvex lens, lens 14 L14 is a concave-convex lens, lens 15 L15 is a biconvex lens, lens 16 L16 is a convex-concave lens, lens 17 L17 is a biconvex lens, and lens 18 L18 is a biconvex lens.

[0073] In this embodiment, the lens comprises at least four cemented lenses. In this embodiment, there are two cemented triplet lenses and two cemented doublet lenses. Specifically, lens 2L2, lens 3L3, and lens 4L4 are connected to form a cemented triplet lens, with a combination of low-refractive index, high-refractive index, and high-refractive index. The refractive index of lens 2L2 is less than that of lens 3L3, the Abbe number of lens 2L2 is greater than that of lens 3L3, the refractive index of lens 3L3 is less than that of lens 4L4, and the Abbe number of lens 3L3 is greater than that of lens 4L4. Lens 9L9 and lens 10L10 are connected to form a cemented doublet lens, with a combination of high-refractive index and high-refractive index. The refractive index of lens 9L9 is less than that of lens 10L10, and the Abbe number of lens 9L9 is greater than that of lens 10L10. Lens 12L12 and lens 10L ... Lens L13 and lens 14 L14 are connected to form a cemented triplet lens, with a combination of high-refractive-index and low-refractive-index combinations. The refractive index of lens 12 L12 is greater than that of lens 13 L13, and the Abbe number of lens 12 L12 is less than that of lens 13 L13. Similarly, the Abbe number of lens 13 L13 is greater than that of lens 14 L14. Lens L16 and lens 17 L17 are connected to form a cemented doublet lens, also with a combination of high-refractive-index and low-refractive-index combinations. The refractive index of lens L16 is greater than that of lens L17 L17, and the Abbe number of lens L16 is less than that of lens L17 L17. It should be noted that in this embodiment, a refractive index of 1.7 is used as a threshold; a refractive index greater than or equal to the threshold is considered high-refractive-index, and a refractive index less than the threshold is considered low-refractive-index.

[0074] In this embodiment, in lens assembly three G3, the Abbe number of the lens with positive diopter is greater than 80.

[0075] In this embodiment, the projection ratio of the projection lens is continuously variable between 1.2 and 1.9. When the projection ratio is 1.2, TTL / EFL ≤ 25; when the projection ratio is 1.9, TTL / EFL ≥ 14. Furthermore, the following relationship is also satisfied: -4 <EFL1 / EFL<-2;7<EFL2 / EFL<14;4.5<EFL3 / EFL<8.5;-25<EFL4 / EFL<-13;2<EFL5 / EFL<4。

[0076] Furthermore, this embodiment satisfies the following conditions: the ratio between the back focal length of the projection lens and the effective focal length of the projection lens is BFL / EFL≥5; the lens assembly three G3 includes 1 to 4 lenses with positive diopter and is made of a material with negative dn / dt, where dn / dt represents the derivative of refractive index (n) with respect to temperature (t); the lens assembly three G3 includes no less than four lenses with a refractive index greater than 1.8; the lens assembly three G3 includes no less than one lens with a positive diopter and a refractive index greater than 1.8.

[0077] In this embodiment, a silicon-based liquid crystal 4 is also included, disposed near the reduction side of the lens assembly 3G3, and the silicon-based liquid crystal 4 is offset relative to the optical axis. During projection, light enters the projection lens from the reduction end side, i.e., the LCOS image plane side, via the polarizing beam splitter 3, the prism 2, and the galvanometer 1, and finally exits the projection lens onto the projection surface to obtain the projection imaging effect.

[0078] Furthermore, during zooming from the Wide end (wide-angle end) to the Tele end (telephoto end), lens assembly 1 G1 and lens assembly 2 G2 remain stationary. Within lens assembly 2 G2, zoom lens group 1 G21 and zoom lens group 3 G23 move towards the reduction side, while zoom lens group 2 G22 moves towards the magnification side. Since lens assembly 3 G3 is a fixed lens group, the back focal length of the projection lens remains constant throughout the zoom process, offering advantages such as good imaging stability, simplified system design, and improved image quality. In addition, when the lens operates at different screen distances, focusing can be achieved by adjusting lens assembly 1 G1. That is, when the projection distance changes to obtain different image sizes, focusing can be adjusted by changing the distance between lens assembly 1 G1 and galvanometer 1.

[0079] Specifically, the design parameters of the projection lens are shown in Table 1.

[0080] Table 1

[0081]

[0082]

[0083] For any given lens, when the radius of curvature on the magnifying side is positive, the magnifying side is convex; when the radius of curvature on the reducing side is negative, the reducing side is convex. In this embodiment, lens L1 is an aspherical lens, and the remaining lenses are spherical lenses. The aspherical polynomial formula is:

[0084]

[0085] In the formula, parameter z represents the distance sag of the aspherical surface from the fixed point of the aspherical surface at a height r along the optical axis, parameter c is the curvature corresponding to the radius, r is the radial height of the lens, k is the conic conic coefficient, and α1 to αn are the aspherical coefficients corresponding to orders 2 to 2n, respectively.

[0086] When the coefficient k is less than -1, the surface profile of the lens is a hyperbola;

[0087] When the coefficient k equals -1, the surface profile of the lens is a parabola;

[0088] When the k coefficient is between -1 and 0, the surface curve of the lens is an ellipse;

[0089] When the k coefficient is equal to 0, the surface curve of the lens is circular;

[0090] When the coefficient k is greater than 0, the surface shape curve of the lens is an oval.

[0091] As shown in Table 2 below.

[0092] Table 2

[0093] k α2 α3 α4 α5 α6 α7 α8 α9 S1 0 3.87E-05 -2.09E-07 1.13E-09 -4.35E-12 1.14E-14 -1.96E-17 2.10E-20 -1.27E-23 S2 0 4.32E-05 -1.88E-07 2.84E-10 7.58E-12 -7.41E-14 3.32E-16 -8.17E-19 1.06E-21

[0094] In the table, S1 is the magnifying side surface of lens L1, and S2 is the reducing side surface of lens L1.

[0095] The projection lens in this embodiment also meets the zoom ratio and BFL / TTL requirements. Specifically, the zoom ratio is 1.5, 1.6, 1.7..., and the BFL / TTL is 0.2, 0.3... Therefore, based on the principle that a larger aperture diameter and a larger light passage allow for more light to be received while keeping the lens focal length constant, resulting in higher brightness, this embodiment provides a zoom projection lens with an aperture of F2.5, distortion less than 0.5%, and a BFL / EFL ratio ≥ 5. This lens has a precise, low-cost, and compact structure. The above-mentioned projection lens forms a continuous diagonal image variation of 57-90 inches at a position of 2390mm. This embodiment is based on the principle of optical imaging. The curvature radius, material, thickness, air gap and other aspects of each lens of the projection lens are optimized. With one plastic aspherical lens and seventeen glass spherical lenses, including four cemented lenses, the optical optimization design is carried out repeatedly to achieve small aberrations, high resolution, simple structure, ingenious design, high manufacturability and easy mass production.

[0096] Example 2

[0097] The difference between this embodiment and Embodiment 1 described above is that the lens assembly 3G3 includes, from the magnification side to the reduction side, a lens 11L11 with positive refractive power, a lens 12L12 with negative refractive power, a lens 13L13 with positive refractive power, a lens 14L14 with negative refractive power, a lens 15L15 with positive refractive power, a lens 16L16 with negative refractive power, a lens 17L17 with positive refractive power, a lens 18L18 with negative refractive power, and a lens 19L19 with positive refractive power. Lenses 16L16, 17L17, and 18L18 are connected to form a cemented triplet lens. The refractive index of lens 16L16 is greater than that of lens 17L17, and the Abbe number of lens 16L16 is less than that of lens 17L17. Similarly, the refractive index of lens 18L18 is greater than that of lens 17L17, and the Abbe number of lens 18L18 is less than that of lens 17L17. It should be noted that when lens 16L16, lens 17L17, and lens 18L18 are connected to form a cemented triplet lens, the cemented triplet lens as a whole has a biconvex structure. It is understood that in this embodiment, the number of cemented triplet lenses is three, and the number of cemented doublet lenses is one.

[0098] This embodiment features a nineteen-lens structure. Compared to Embodiment 1, the last cemented doublet lens is replaced with a cemented triplet lens, achieving the same technical effect as Embodiment 1.

[0099] Example 3

[0100] The difference between this embodiment and Embodiment 1 is that the lens assembly G1 includes a lens with negative diopter L1, a lens with negative diopter L2, a lens with positive diopter L3, a lens with positive diopter L4, and a lens with negative diopter L5, arranged from the magnification side to the reduction side; the zoom lens group G21 includes a lens with positive diopter L6; and the zoom lens group G22 includes a lens with negative diopter L7, a lens with positive diopter L8, and a lens with positive diopter L5, arranged from the magnification side to the reduction side. Lens 9 L9; The zoom lens group 3 G23 includes a lens 10 L10 with negative refractive power and a lens 11 L11 with positive refractive power, arranged from the magnification side to the reduction side; The lens assembly 3 G3 includes a lens 12 L12 with negative refractive power, a lens 13 L13 with positive refractive power, a lens 14 L14 with negative refractive power, a lens 15 L15 with positive refractive power, a lens 16 L16 with negative refractive power, a lens 17 L17 with positive refractive power, and a lens 18 L18 with positive refractive power, arranged from the magnification side to the reduction side.

[0101] In this embodiment, the three lens components have a negative-negative-positive diopter structure. Specifically, lens L1 is a meniscus lens convex towards the magnification side and is an aspherical lens, used to correct distortion and astigmatism, and effectively correct field curvature. Lens L1 is made of resin, which has advantages such as being lightweight, impact-resistant, having high light transmittance, simple processing technology, and low cost. By optimizing the aspherical coefficient of lens L1, off-axis aberrations and distortions can be effectively corrected. Lens 2 (L2) is a biconcave lens, lens 3 (L3) is a convex-concave lens, lens 4 (L4) is a plano-convex lens, lens 5 (L5) is a concave-convex lens, lens 6 (L6) is a concave-convex lens, lens 7 (L7) is a biconcave lens, lens 8 (L8) is a biconvex lens, lens 9 (L9) is a biconvex lens, lens 10 (L10) is a biconcave lens, lens 11 (L11) is a biconvex lens, lens 12 (L12) is a biconcave lens, lens 13 (L13) is a biconvex lens, lens 14 (L14) is a concave-convex lens, lens 15 (L15) is a biconvex lens, lens 16 (L16) is a concave-convex lens, lens 17 (L17) is a plano-convex lens, and lens 18 (L18) is a biconvex lens. Lens 9 (L9) is also an aspherical lens, used to correct distortion and astigmatism, effectively correcting field curvature. In this embodiment, there is one cemented triplet lens and five cemented doublet lenses. Furthermore, lens 2 (L2) and lens 3 (L3) are connected as a cemented doublet with a combination of low and high refractive indices. The refractive index of lens 2 (L2) is less than that of lens 3 (L3), and the Abbe number of lens 2 (L2) is greater than that of lens 3 (L3). Similarly, lens 4 (L4) and lens 5 (L5) are connected as a cemented doublet with a combination of high and high refractive indices. The refractive index of lens 4 (L4) is less than that of lens 5 (L5), and the Abbe number of lens 4 (L4) is greater than that of lens 5 (L5). Lens 7 (L7) and lens 8 (L8) are connected as a cemented doublet with a combination of high and low refractive indices. The refractive index of lens 7 (L7) is greater than that of lens 8 (L8), and the Abbe number of lens 7 (L7) is less than that of lens 8 (L8). Finally, lens 10 (L10) and lens 11 (L11) are connected as a cemented doublet with a combination of high and high refractive indices. The refractive index of lens 11L11 is less than that of lens 10L10, and the Abbe number of lens 11L11 is greater than that of lens 11L11. Lenses 12L12, 13L13, and 14L14 are connected to form a cemented triplicate lens, with a combination of high-refractive-index, low-refractive-index, and high-refractive-index lenses. The refractive index of lens 12L12 is greater than that of lens 13L13, and the Abbe number of lens 12L12 is less than that of lens 13L13. The refractive index of lens 13L13 is less than that of lens 14L14, and the Abbe number of lens 13L13 is greater than that of lens 14L14. Lenses 15L15 and 16L16 are connected to form a cemented bilayer lens, with a combination of low-refractive-index, high-refractive-index lenses. The refractive index of lens 15L15 is less than that of lens 16L16, and the Abbe number of lens 15L15 is greater than that of lens 16L16.In this embodiment, a refractive index of 1.6 or 1.7 is used as a threshold to determine whether each lens is high-refractive or low-refractive.

[0102] In this embodiment, the projection ratio of the projection lens is continuously variable between 1.3 and 2.1. When the projection ratio is 1.3, TTL / EFL ≤ 20; when the projection ratio is 2.1, TTL / EFL ≥ 11. Furthermore, the following relationship is also satisfied: -4.5 <EFL1 / EFL<-2.5;15<EFL2 / EFL<45;4.5<EFL3 / EFL<8.5;-10<EFL4 / EFL<-4;2<EFL5 / EFL<4。

[0103] Specifically, the design parameters of the projection lens are shown in Table 3.

[0104] Table 3

[0105]

[0106]

[0107] In this embodiment, lens nine L9 is also an aspherical lens. Therefore, when designing lens one L1 using only the aspherical polynomial formula in embodiment 1, it is also necessary to design lens nine L9 using the same formula.

[0108] The designs of lens 1 (L1) and lens 9 (L9) are shown in Table 4 below.

[0109] Table 4

[0110] k α2 α3 α4 α5 α6 α7 α8 α9 S1 0 6.31E-05 -2.84E-07 -2.01E-10 2.02E-11 -1.81E-13 8.42E-16 -2.24E-18 3.25E-21 S2 0 6.48E-05 -2.17E-07 -8.78E-10 -2.42E-12 5.72E-13 -8.08E-15 5.15E-17 -1.62E-19 S14 0 -1.41E-05 -7.39E-08 1.85E-09 -9.58E-11 2.49E-12 -3.75E-14 3.25E-16 -1.50E-18 S15 0 -9.30E-06 -8.87E-09 -1.53E-09 1.60E-11 2.62E-13 -1.01E-14 1.20E-16 -6.60E-19

[0111] In the table, S1 is the magnifying side surface of lens L1, S2 is the reducing side surface of lens L1, S14 is the magnifying side surface of lens L9, and S15 is the reducing side surface of lens L9.

[0112] The projection lens in this embodiment also meets the zoom ratio and BFL / TTL requirements. Specifically, the zoom ratio is 1.5, 1.6, 1.7..., and the BFL / TTL is 0.2, 0.3... . Therefore, this embodiment provides a zoom projection lens with an aperture of F2.5 and distortion of less than 0.5%. This lens has a precise, low-cost, and compact structure. The aforementioned projection lens forms a continuous diagonal image variation of 51-83 inches at a position of 2390mm. This embodiment is based on the principle of optical imaging, optimizing the curvature radius, material, thickness, and air gap of each lens element. It utilizes one plastic aspherical lens, one glass molded aspherical lens, and sixteen glass spherical lenses, including six cemented lenses, through repeated optical optimization design to achieve low aberrations, high resolution, simple structure, and ingenious design. It is highly manufacturable and easy to mass-produce.

[0113] Example 4

[0114] The difference between this embodiment and Embodiment 1 is that the lens assembly G1 includes a negative diopter lens L1, a negative diopter lens L2, a positive diopter lens L3, a positive diopter lens L4, and a negative diopter lens L5, arranged from the magnification side to the reduction side; the zoom lens group G21 includes a positive diopter lens L6; and the zoom lens group G22 includes a negative diopter lens L7, a positive diopter lens L8, a positive diopter lens L9, and a positive diopter lens L5, arranged from the magnification side to the reduction side. The zoom lens group 3G23 includes a lens 11L11 with negative diopter and a lens 12L12 with positive diopter, arranged from the magnification side to the reduction side; the lens assembly 3G3 includes a lens 13L13 with negative diopter, a lens 14L14 with negative diopter, a lens 15L15 with positive diopter, a lens 16L16 with negative diopter, a lens 17L17 with positive diopter, a lens 18L18 with negative diopter, a lens 19L19 with positive diopter, and a lens 20L20 with positive diopter, arranged from the magnification side to the reduction side.

[0115] In this embodiment, the three lens components have a negative-positive-positive diopter configuration. Specifically, lens L1 is a meniscus lens convex towards the magnification side and is an aspherical lens, used to correct distortion and astigmatism, and effectively correct field curvature. Lens L1 is made of resin, which has advantages such as being lightweight, impact-resistant, having high light transmittance, simple processing technology, and low cost. By optimizing the aspherical coefficient of lens L1, off-axis aberrations and distortions can be effectively corrected. Lens 2L2 is a biconcave lens, lens 3L3 is a biconvex lens, lens 4L4 is a biconvex lens, lens 5L5 is a biconcave lens, lens 6L6 is a biconvex lens, lens 7L7 is a biconcave lens, lens 8L8 is a biconvex lens, lens 9L9 is a concave-convex lens, lens 10L10 is a biconvex lens, lens 11L11 is a biconcave lens, lens 12L12 is a biconvex lens, lens 13L13 is a biconcave lens, lens 14L14 is a convex-concave lens, lens 15L15 is a biconvex lens, lens 16L16 is a concave-convex lens, lens 17L17 is a biconvex lens, lens 18L18 is a convex-concave lens, lens 19L19 is a biconvex lens, and lens 20L20 is a biconvex lens. In this embodiment, there is one cemented triplet lens and four cemented doublet lenses. Furthermore, lens 2 (L2) and lens 3 (L3) are connected as a cemented doublet with a combination of low and high refractive indices. The refractive index of lens 2 (L2) is less than that of lens 3 (L3), and the Abbe number of lens 2 (L2) is greater than that of lens 3 (L3). Similarly, lens 4 (L4) and lens 5 (L5) are connected as a cemented doublet with a combination of high and high refractive indices. The refractive index of lens 4 (L4) is less than that of lens 5 (L5), and the Abbe number of lens 4 (L4) is greater than that of lens 5 (L5). Finally, lens 11 (L11) and lens 12 (L12) are connected as a cemented doublet with a combination of high and high refractive indices. The refractive index of lens 11 (L11) is less than that of lens 12 (L12), and the Abbe number of lens 11 (L11) is greater than that of lens 12 (L12). The Abbe number is determined by the following parameters: Lens 14L14, Lens 15L15, and Lens 16L16 are connected as a cemented triplet lens, with a high-refractive-index and low-refractive-index combination. The refractive index of Lens 14L14 is greater than that of Lens 15L15, and the Abbe number of Lens 14L14 is less than that of Lens 15L15. Similarly, the refractive index of Lens 16L16 is greater than that of Lens 15L15, and the Abbe number of Lens 16L16 is less than that of Lens 15L15. Lens 18L18 and Lens 19L19 are connected as a cemented doublet lens, with a high-refractive-index and low-refractive-index combination. The refractive index of Lens 18L18 is greater than that of Lens 19L19, and the Abbe number of Lens 18L18 is less than that of Lens 19L19. In this embodiment, a refractive index of 1.6 or 1.7 is used as a threshold to determine whether each lens is a high-refractive-index or low-refractive-index lens.

[0116] In this embodiment, the projection ratio of the projection lens is continuously variable between 1.3 and 2.1. When the projection ratio is 1.3, TTL / EFL ≤ 20; when the projection ratio is 2.1, TTL / EFL ≥ 11. Furthermore, the following relationship is also satisfied: -2.1 <EFL1 / EFL<-1.0;3.6<EFL2 / EFL<8.1;3.1<EFL3 / EFL<6.3;-16<EFL4 / EFL<-8;2<EFL5 / EFL<4。

[0117] Specifically, the design parameters of the projection lens are shown in Table 5.

[0118] Table 5

[0119]

[0120]

[0121] Among them, lens one is an aspherical lens, as shown in Table 6 below.

[0122] Table 6

[0123] k α2 α3 α4 α5 α6 α7 α8 α9 S1 0 4.78E-05 -2.62E-07 1.52E-09 -6.18E-12 1.76E-14 -3.80E-17 6.62E-20 -8.10E-23 S2 0 4.57E-05 3.17E-07 -1.73E-08 3.35E-10 -3.57E-12 2.31E-14 -8.99E-17 1.95E-19

[0124] In the table, S1 is the magnifying side surface of lens L1, and S2 is the reducing side surface of lens L1.

[0125] The projection lens in this embodiment also meets the zoom ratio and BFL / TTL requirements. Specifically, the zoom ratio is 1.5, 1.6, 1.7..., and the BFL / TTL is 0.2, 0.3... . Therefore, this embodiment provides a zoom projection lens with an aperture of F2.5, distortion less than 0.5%, and a BFL / EFL ratio ≥ 5. This lens has a precise, low-cost, and compact structure. The aforementioned projection lens forms a continuous diagonal image variation of 72-90 inches at a position of 2390mm. Based on the principle of optical imaging, this embodiment optimizes the curvature radius, material, thickness, and air gap of each lens element. It uses one plastic aspherical lens and nineteen glass spherical lenses, including five cemented lenses, through repeated optical optimization design to achieve low aberrations, high resolution, simple structure, ingenious design, high manufacturability, and ease of mass production.

[0126] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A projection lens characterized in that, The lens assembly one with negative optical power, the lens assembly two with positive or negative optical power, and the lens assembly three with positive optical power are arranged from the magnification side to the demagnification side; The lens assembly two is a zoom group, which comprises zoom lens group one, zoom lens group two, and zoom lens group three, each of which is independently movable along the optical axis and arranged from the magnification side to the demagnification side, and the element closest to the demagnification side in the zoom lens group three is a diaphragm; The projection lens satisfies at least one of the following conditions: The zoom ratio is greater than or equal to 1.5; The number of lenses with positive focal length and Abbe number greater than 80 is less than or equal to 4; 1≤N1≤4 and / or 1≤N2≤5, N1 is the number of three-cemented lenses, and N2 is the number of two-cemented lenses; BFL / TTL is greater than or equal to 0.2, BFL is the back focal length of the projection lens, and TTL is the total length of the projection lens.

2. The projection lens of claim 1, wherein, The projection lens satisfies the following condition: TTL5 / TTL is greater than or equal to 0.4, and TTL5 is the length from the lens closest to the magnification side in the lens assembly three to the chip of the projection lens.

3. The projection lens of claim 1, wherein, The projection ratio of the projection lens is continuously variable between 1.2 and 2.1; When the projection ratio is 1.2, TTL / EFL is less than or equal to 25; when the projection ratio is 1.9, TTL / EFL is greater than or equal to 14; When the projection ratio is 1.3, TTL / EFL is less than or equal to 20; when the projection ratio is 2.1, TTL / EFL is greater than or equal to 11; EFL is the effective focal length of the projection lens.

4. The projection lens of claim 1, wherein, The focal length relationship between each lens assembly and the projection lens in the lens assembly one, the lens assembly two, and the lens assembly three is as follows: -4.5<EFL1 / EFL<-1; 3.6<EFL2 / EFL<45; 3.1<EFL3 / EFL<8.5; -25<EFL4 / EFL<-4; 2<EFL5 / EFL<4; EFL1 is the effective focal length of the lens assembly one, EFL2 is the effective focal length of the zoom lens group one, EFL3 is the effective focal length of the zoom lens group two, EFL4 is the effective focal length of the zoom lens group three, EFL5 is the effective focal length of the lens assembly three, and EFL is the effective focal length of the projection lens.

5. A projection lens as claimed in claim 4, characterized in that The focal length relationship between each lens assembly and the projection lens in the lens assembly one, the lens assembly two, and the lens assembly three is as follows: -4<EFL1 / EFL<-2; 7<EFL2 / EFL<14; 4.5<EFL3 / EFL<8.5; -25<EFL4 / EFL<-13; 2<EFL5 / EFL<4; Or -4.5<EFL1 / EFL<-2.5; 15<EFL2 / EFL<45; 4.5<EFL3 / EFL<8.5; -10<EFL4 / EFL<-4; 2<EFL5 / EFL<4; or -2.1<EFL1 / EFL<-1.0; 3.6<EFL2 / EFL<8.1; 3.1<EFL3 / EFL<6.3; -16<EFL4 / EFL<-8; 2<EFL5 / EFL<4.

6. A projection lens according to any one of claims 1 to 4, wherein The projection lens adopts lens architecture one, the lens assembly one includes from the magnification side to the reduction side setting the diopter is negative lens one, the diopter is negative lens two, the diopter is positive lens three, the diopter is negative lens four;The zoom lens group one includes the diopter is positive lens five;The zoom lens group two includes from the magnification side to the reduction side setting the diopter is negative lens six, the diopter is positive lens seven, the diopter is positive lens eight;The zoom lens group three includes from the magnification side to the reduction side setting the diopter is negative lens nine, the diopter is positive lens ten;The lens assembly three includes from the magnification side to the reduction side setting the diopter is positive lens eleven, the diopter is negative lens twelve, the diopter is positive lens thirteen, the diopter is negative lens fourteen, the diopter is positive lens fifteen, the diopter is negative lens sixteen, the diopter is positive lens seventeen, the diopter is positive lens eighteen; Or, the projection lens adopts lens architecture two, the lens assembly one includes from the magnification side to the reduction side setting the diopter is negative lens one, the diopter is negative lens two, the diopter is positive lens three, the diopter is positive lens four, the diopter is negative lens five;The zoom lens group one includes the diopter is positive lens six;The zoom lens group two includes from the magnification side to the reduction side setting the diopter is negative lens seven, the diopter is positive lens eight, the diopter is positive lens nine, the zoom lens group three includes from the magnification side to the reduction side setting the diopter is negative lens ten, the diopter is positive lens eleven;The lens assembly three includes from the magnification side to the reduction side setting the diopter is negative lens twelve, the diopter is positive lens thirteen, the diopter is negative lens fourteen, the diopter is positive lens fifteen, the diopter is negative lens sixteen, the diopter is positive lens seventeen, the diopter is positive lens eighteen; Or, the projection lens adopts lens architecture three, the lens assembly one includes from the magnification side to the reduction side setting the diopter is negative lens one, the diopter is negative lens two, the diopter is positive lens three, the diopter is positive lens four, the diopter is negative lens five;The zoom lens group one includes the diopter is positive lens six;The zoom lens group two includes from the magnification side to the reduction side setting the diopter is negative lens seven, the diopter is positive lens eight, the diopter is positive lens nine, the diopter is positive lens ten, the zoom lens group three includes from the magnification side to the reduction side setting the diopter is negative lens eleven, the diopter is positive lens twelve;The lens assembly three includes from the magnification side to the reduction side setting the diopter is negative lens thirteen, the diopter is negative lens fourteen, the diopter is positive lens fifteen, the diopter is negative lens sixteen, the diopter is positive lens seventeen, the diopter is negative lens eighteen, the diopter is positive lens nineteen, the diopter is positive lens twenty.

7. The projection lens of claim 6, wherein, In the lens architecture one, the lens two, the lens three and the lens four are connected as a three-cemented lens, the refractive index of the lens two is less than the refractive index of the lens three, the Abbe number of the lens two is greater than the Abbe number of the lens three, the refractive index of the lens three is less than the refractive index of the lens four, and the Abbe number of the lens three is greater than the Abbe number of the lens four; the lens nine and the lens ten are connected as a double-cemented lens, the refractive index of the lens nine is less than the refractive index of the lens ten, and the Abbe number of the lens nine is greater than the Abbe number of the lens ten; the lens twelve, the lens thirteen and the lens fourteen are connected as a three-cemented lens, the refractive index of the lens twelve is greater than the refractive index of the lens thirteen, the Abbe number of the lens twelve is less than the Abbe number of the lens thirteen, the refractive index of the lens thirteen is less than the refractive index of the lens fourteen, and the Abbe number of the lens thirteen is greater than the Abbe number of the lens fourteen; the lens sixteen and the lens seventeen are connected as a double-cemented lens, the refractive index of the lens sixteen is greater than the refractive index of the lens seventeen, and the Abbe number of the lens sixteen is less than the Abbe number of the lens seventeen; In the lens architecture two, the lens two and the lens three are connected as a double-cemented lens, the refractive index of the lens two is less than the refractive index of the lens three, and the Abbe number of the lens two is greater than the Abbe number of the lens three; the lens four and the lens five are connected as a double-cemented lens, the refractive index of the lens four is less than the refractive index of the lens five, and the Abbe number of the lens four is greater than the Abbe number of the lens five; the lens seven and the lens eight are connected as a double-cemented lens, the refractive index of the lens seven is greater than the refractive index of the lens eight, and the Abbe number of the lens seven is less than the Abbe number of the lens eight; the lens ten and the lens eleven are connected as a double-cemented lens, the refractive index of the lens ten is less than the refractive index of the lens eleven, and the Abbe number of the lens ten is greater than the Abbe number of the lens eleven; the lens twelve, the lens thirteen and the lens fourteen are connected as a three-cemented lens, the refractive index of the lens twelve is greater than the refractive index of the lens thirteen, the Abbe number of the lens twelve is less than the Abbe number of the lens thirteen, the refractive index of the lens thirteen is less than the refractive index of the lens fourteen, and the Abbe number of the lens thirteen is greater than the Abbe number of the lens fourteen; the lens fifteen and the lens sixteen are connected as a double-cemented lens, the refractive index of the lens fifteen is less than the refractive index of the lens sixteen, and the Abbe number of the lens fifteen is greater than the Abbe number of the lens sixteen; In the lens architecture three, the lens two and the lens three are connected as a double cemented lens, the lens two has a smaller refractive index and a larger Abbe number than the lens three; the lens four and the lens five are connected as a double cemented lens, the lens four has a smaller refractive index and a larger Abbe number than the lens five; the lens eleven and the lens twelve are connected as a double cemented lens, the lens eleven has a smaller refractive index and a larger Abbe number than the lens twelve; the lens fourteen, the lens fifteen and the lens sixteen are connected as a triple cemented lens, the lens fourteen has a larger refractive index and a smaller Abbe number than the lens fifteen, the lens sixteen has a larger refractive index and a smaller Abbe number than the lens fifteen; the lens eighteen and the lens nineteen are connected as a double cemented lens, the lens eighteen has a larger refractive index and a smaller Abbe number than the lens nineteen.

8. The projection lens of claim 6 wherein, In the lens architecture one, the lens assembly three includes, from the magnifying side to the reducing side, a lens eleven with positive refractive power, a lens twelve with negative refractive power, a lens thirteen with positive refractive power, a lens fourteen with negative refractive power, a lens fifteen with positive refractive power, a lens sixteen with negative refractive power, a lens seventeen with positive refractive power, a lens eighteen with negative refractive power, and a lens nineteen with positive refractive power.

9. A projection lens as claimed in claim 8, characterized in that The lens sixteen, the lens seventeen and the lens eighteen are connected as a triple cemented lens, the lens sixteen has a larger refractive index and a smaller Abbe number than the lens seventeen, the lens eighteen has a larger refractive index and a smaller Abbe number than the lens seventeen.

10. The projection lens of claim 1, wherein, The lens closest to the magnifying side is a meniscus lens and a non-spherical lens.

11. The projection lens of claim 6, wherein, In the lens architecture two, the lens nine is a non-spherical lens.

12. The projection lens of claim 1, wherein, The diameter of all the lenses is less than 30 mm, or the diameter of all the lenses is less than 32 mm.

13. The projection lens of claim 1, wherein, The ratio between the back focal length of the projection lens and the effective focal length of the projection lens is BFL / EFL≥5.

14. The projection lens of claim 1, wherein, The lens assembly three includes 1-4 lenses with positive refractive power and is made of a material with negative dn / dt. Wherein, dn / dt represents the derivative of refractive index (n) to temperature (t).

15. The projection lens of claim 1, wherein, The lens assembly three includes no less than four lenses with a refractive index greater than 1.

8. The lens assembly three includes no less than one lens with positive refractive power and a refractive index greater than 1.8.

Images