Multi-throw compatible projection lens and 3D printing device

Abstract

The application discloses a multi-standoff compatible projection lens and a 3D printing device, which comprises a front lens group, a diaphragm and a rear lens group arranged in sequence from an object plane to an image plane, wherein the front lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence from the object plane to the image plane, the rear lens group comprises a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens arranged in sequence from the object plane to the image plane, the first lens, the second lens, the fifth lens and the seventh lens have negative focal lengths, and the third lens, the fourth lens, the sixth lens, the eighth lens, the ninth lens and the tenth lens have positive focal lengths; the first lens can move along an optical axis relative to the second lens, and the effective focal lengths of the front lens group and the rear lens group are reasonably distributed. The application has the advantages of being compatible with ultraviolet bands, good environmental stability, compact structure and high resolution.

Description

Technical Field

[0001] This invention belongs to the field of optical lens technology, specifically relating to a projection lens compatible with multiple object distances and a 3D printing device. Background Technology

[0002] In recent years, ultraviolet (UV) light curing 3D printing technology has been widely used in precision manufacturing, medical devices, and other fields due to its advantages such as high precision and rapid prototyping. This technology achieves three-dimensional structure formation by curing photosensitive resin layer by layer with ultraviolet light (such as the 385nm-405nm wavelength range). The performance of the projection lens, as its core optical component, directly determines the printing resolution and the quality of the finished product. However, existing projection lenses used in such devices still face the following technical bottlenecks:

[0003] 1) Insufficient adaptation to the ultraviolet band: Traditional projection lenses are mostly designed for visible light, while ultraviolet light has a shorter wavelength, which can easily cause problems such as material dispersion and decreased transmittance. Ordinary optical glass has low transmittance (usually <70%) in the 385nm-405nm band and significant ultraviolet color difference, resulting in an increased spot size, which is difficult to meet the requirements of micron-level curing precision;

[0004] 2) Poor environmental stability: 3D printing equipment often needs to work in a wide temperature environment (such as -40℃ to 85℃), while conventional lenses are prone to thermal defocusing due to mismatch in material thermal expansion coefficients or insufficient mechanical structure compensation, resulting in inconsistent cured layer thickness;

[0005] 3) Low compatibility with multi-object distance projection: To adapt to different printing sizes, the projection object distance needs to be flexibly adjusted within the range of 229mm-350mm. Existing lenses usually have a fixed optimized single object distance (such as 287mm). When the object distance changes, insufficient aberration compensation leads to a sharp drop in edge resolution, affecting the uniformity of large-size printing;

[0006] 4) The contradiction between structural compactness and image quality: High-resolution lenses often require complex optical designs (such as aspherical or multi-group linkage structures), resulting in an excessively long optical length (>130mm), making it difficult to adapt to miniaturized 3D printing equipment. At the same time, the low proportion of spherical lenses will increase manufacturing costs.

[0007] To address the aforementioned issues, existing technologies typically improve upon these problems by adding aspherical lenses or active focusing mechanisms to mitigate aberrations and environmental drift. However, aspherical lenses are expensive to manufacture, and dynamic focusing mechanisms introduce mechanical complexity, reducing system reliability. Therefore, there is an urgent need for a low-cost projection lens that combines high image quality in the ultraviolet band, wide temperature stability, multi-object distance compatibility, and a compact structure to promote the industrial application of high-precision 3D printing technology. Summary of the Invention

[0008] The purpose of this invention is to address the above-mentioned problems by proposing a projection lens and 3D printing equipment that are compatible with multiple object distances. This invention provides a projection lens that is adaptable to the ultraviolet band, has good environmental stability, is compatible with multiple object distances, and has a compact structure and high resolution.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] This invention proposes a multi-object distance compatible projection lens, comprising a front lens group, an aperture stop, and a rear lens group arranged sequentially from the object plane to the image plane. The front lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially from the object plane to the image plane. The rear lens group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged sequentially from the object plane to the image plane. The first lens, second lens, fifth lens, and seventh lens have negative optical power, while the third lens, fourth lens, sixth lens, eighth lens, ninth lens, and tenth lens have positive optical power. The first lens can move relative to the second lens along the optical axis and satisfies the following conditions:

[0011] -120 <f A <-80, 10 <f B <30;

[0012] Among them, f A f is the effective focal length of the front lens group. B This represents the effective focal length of the rear lens group, in mm.

[0013] Preferably, the first lens, the second lens, the fourth lens, the fifth lens, and the tenth lens are all convex-concave lenses, the third lens and the ninth lens are both biconvex lenses, the sixth lens and the eighth lens are both concave-convex lenses, and the seventh lens is a biconcave lens.

[0014] Preferably, the projection lens that is compatible with multiple object distances also meets the following conditions:

[0015] -89 <f1<-72.8,-45.5<f2<-37.2,25.7<f3<31.4,73.9<f4<90.4,

[0016] -27.4 <f5<-22.4,23.4<f6<28.5,-18<f7<-14.7,40.2<f8<49.1,

[0017] 30 <f9<36.6,87<f 10 <82;

[0018] Among them, f1, f2, f3, f4, f5, f6, f7, f8, f9, f 10The focal lengths of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth lenses, in mm, are listed in order.

[0019] Preferably, the projection lens that is compatible with multiple object distances also meets the following conditions:

[0020] 31.9 <R 11 <39, 91.5 <R 21 <111.89, 36.6 <R 31 <44.8, 16.4 <R 41 <20.1,

[0021] 20.7 <R 51 <25.3, -94.0 <R 61 <-70, -16.9 <R 71 <-13.9, -108 <R 81 <-88.6,

[0022] 71.2 <R 91 <87.1, 36.6 <R 101 <44.7; 19.8 <R 12 <24.15, 20.6 <R 22 <25.2,

[0023] -44.8 <R 32 <-36.6, 19.4 <R 42 <23.7, 7.8 <R 52 <9.5, -14.5 <R 62 <-11.8,

[0024] 39.2 <R 72 <50, -25.9 <R 82 <-21.2, -27.6 <R 92 <-22.7, 93.7 <R 102 <120;

[0025] Among them, R 11 R 21 R 31 R 41 R 51 R 61 R 71 R 81 R 91 R 101 The radii of curvature of the object-side surfaces of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth lenses, in mm; R12 R 22 R 32 R 42 R 52 R 62 R 72 R 82 R 92 R 102 The radii of curvature of the image-side surfaces of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth lenses, in mm, are shown in order; "-" indicates a negative direction.

[0026] Preferably, the projection lens that is compatible with multiple object distances also meets the following conditions:

[0027] 15 <f<19,1.95≤f / D≤2.1,1.3<TR<1 .7;

[0028] Where f is the effective focal length of the multi-object distance compatible projection lens, in mm; D is the entrance pupil diameter, in mm; and TR is the projection ratio of the multi-object distance compatible projection lens.

[0029] Preferably, the projection lens that is compatible with multiple object distances also meets the following conditions:

[0030] 90 <TTL<130,40<TA<60,10<TB<27;

[0031] Where TTL is the total optical length of the projection lens that is compatible with multiple object distances, TA is the optical length of the front lens group, and TB is the optical length of the rear lens group, all in mm.

[0032] Preferably, the projection lens that is compatible with multiple object distances also meets the following conditions:

[0033] 1.5≤ SD 1 / SD 10≤1.9,0.045≤A1 / TTL<0.09,

[0034] 0.08≤A2 / TTL<0.12, 0.1≤A5 / TTL<0.2;

[0035] in, SD 1 represents the edge ray height on the object side of the first lens. SD 10 represents the edge ray height of the image side of the tenth lens, TTL represents the total optical length of the multi-object distance compatible projection lens, A1 represents the center air gap between the first and second lenses, A2 represents the center air gap between the second and third lenses, and A5 represents the center air gap between the fifth and sixth lenses. All units are in mm.

[0036] Preferably, the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens and tenth lens are all spherical glass lenses, and each lens has a transmittance of ≥90% in the 385nm~405nm wavelength range. At least two lenses in the front lens group have a refractive index greater than 1.7, and at least two lenses in the rear lens group have an Abbe number greater than 70.

[0037] Preferably, the projection lens that is compatible with multiple object distances also meets the following conditions:

[0038] CRA<1°, 28<BFL<37, TV DIST <0.15%;

[0039] Where CRA is the maximum ray angle of the multi-object distance compatible projection lens on the imaging plane, BFL is the on-axis distance from the image side of the tenth lens to the imaging plane, in mm, TV DIST This refers to TV distortion on the imaging plane.

[0040] A 3D printing apparatus comprising any of the above-described multi-object distance compatible projection lenses.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] This projection lens employs ten lenses, preferably an all-glass spherical lens structure. The fewer lenses and simpler structure enable positive and negative optical power separation, effectively correcting image plane curvature and improving image quality. This results in high resolution (MTF not less than 70%) and a resolution not less than 93 lp / mm, demonstrating high resolving power. Furthermore, the lens exhibits low distortion, with an absolute TV distortion of less than 0.15%, achieving image quality far exceeding existing technologies. The lens also utilizes minute adjustments in lens spacing to ensure clear projection over a wide range of distances from 229mm to 350mm, allowing for matching with a 0.75" image source chip (1080p resolution), thereby enhancing 3D printing quality. This results in a projection lens with low distortion and high resolution, achieving clear and distortion-free 3D printing under 350nm-450nm wavelength light, adapting to a wide temperature range of -40℃ to 85℃, and exhibiting good stability and compatibility. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the multi-object distance compatible projection lens in Embodiment 1 of the present invention;

[0044] Figure 2 This is the MTF plot of Scheme 1 in Embodiment 1 of the present invention when the projection distance is 229mm;

[0045] Figure 3This is the MTF plot of Scheme 1 in Embodiment 1 of the present invention when the projection distance is 287mm;

[0046] Figure 4 This is the MTF diagram of Scheme 1 in Embodiment 1 of the present invention when the projection distance is 350mm;

[0047] Figure 5 This is a TV distortion diagram of Scheme 1 in Embodiment 1 of the present invention;

[0048] Figure 6 This is a schematic diagram of the multi-object distance compatible projection lens in Scheme 2 of Embodiment 1 of the present invention;

[0049] Figure 7 This is the MTF diagram of Scheme 2 in Embodiment 1 of the present invention when the projection distance is 229mm;

[0050] Figure 8 This is the MTF diagram of Scheme 2 in Embodiment 1 of the present invention when the projection distance is 287mm;

[0051] Figure 9 This is the MTF diagram of Scheme 2 in Embodiment 1 of the present invention when the projection distance is 350mm;

[0052] Figure 10 This is a TV distortion diagram of scheme 2 in embodiment 1 of the present invention.

[0053] Explanation of reference numerals in the attached diagram: L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; L9, ninth lens; L10, tenth lens; L11, equivalent galvanometer; L12, equivalent prism; STO, aperture stop; CG, protective glass; DMD, image source chip. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application.

[0056] Example 1:

[0057] like Figures 1-10 As shown, a projection lens compatible with multiple object distances includes a front lens group, an aperture stop (STO), and a rear lens group arranged sequentially from the object plane to the image plane. The front lens group includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged sequentially from the object plane to the image plane. The rear lens group includes a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, and a tenth lens L10 arranged sequentially from the object plane to the image plane. The first lens L1, the second lens L2, the fifth lens L5, and the seventh lens L7 have negative optical power, while the third lens L3, the fourth lens L4, the sixth lens L6, the eighth lens L8, the ninth lens L9, and the tenth lens L10 have positive optical power. The first lens L1 can move relative to the second lens L2 along the optical axis and satisfies the following condition:

[0058] -120 <f A <-80, 10 <f B <30;

[0059] Among them, f A f is the effective focal length of the front lens group. B This represents the effective focal length of the rear lens group, in mm.

[0060] Specifically, the effective focal length of the front lens group can be -103.5 mm or -105 mm, and the effective focal length of the rear lens group can be 20.6 mm or 21 mm. Meeting the above conditions is beneficial for optimizing projection lens distortion and improving resolution; exceeding these ranges fails to meet the requirements for high resolution and low distortion. This projection lens uses ten lenses, resulting in a simple structure and achieving separation of positive and negative optical focal lengths. This effectively corrects the image plane curvature of the projection lens, improving image quality and providing high resolution. It exhibits low distortion and is suitable for a wide projection distance range of 229 mm to 350 mm, achieving clear and distortion-free 3D printing effects under 350 nm-450 nm wavelength light. It also demonstrates good stability and compatibility.

[0061] In one embodiment, the first lens L1, the second lens L2, the fourth lens L4, the fifth lens L5 and the tenth lens L10 are all convex-concave lenses, the third lens L3 and the ninth lens L9 are both biconvex lenses, the sixth lens L6 and the eighth lens L8 are both concave-convex lenses, and the seventh lens L7 is a biconcave lens.

[0062] In one embodiment, the multi-object distance compatible projection lens also satisfies the following condition:

[0063] -89 <f1<-72.8,-45.5<f2<-37.2,25.7<f3<31.4,73.9<f4<90.4,

[0064] -27.4 <f5<-22.4,23.4<f6<28.5,-18<f7<-14.7,40.2<f8<49.1,

[0065] 30 <f9<36.6,87<f 10 <82;

[0066] Among them, f1, f2, f3, f4, f5, f6, f7, f8, f9, f 10 The focal lengths of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, and the tenth lens L10 are, in mm.

[0067] In one embodiment, the multi-object distance compatible projection lens also satisfies the following condition:

[0068] 31.9 <R 11 <39, 91.5 <R 21 <111.89, 36.6 <R 31 <44.8, 16.4 <R 41 <20.1,

[0069] 20.7 <R 51 <25.3, -94.0 <R 61 <-70, -16.9 <R 71 <-13.9, -108 <R 81 <-88.6,

[0070] 71.2 <R 91 <87.1, 36.6 <R 101 <44.7; 19.8 <R 12 <24.15, 20.6 <R 22 <25.2,

[0071] -44.8 <R 32 <-36.6, 19.4 <R 42 <23.7, 7.8 <R 52 <9.5, -14.5 <R 62 <-11.8,

[0072] 39.2 <R 72 <50, -25.9 <R 82 <-21.2, -27.6 <R 92 <-22.7, 93.7 <R 102 <120;

[0073] Among them, R 11 R21 R 31 R 41 R 51 R 61 R 71 R 81 R 91 R 101 The radii of curvature of the object-side surfaces of lenses L1, L2, L3, L4, L5, L6, L7, L8, L9, and L10, respectively, in mm; R 12 R 22 R 32 R 42 R 52 R 62 R 72 R 82 R 92 R 102 The curvature radii of the image-side surfaces of the first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, and tenth lens L10 are in mm; "-" indicates the negative direction.

[0074] In one embodiment, the multi-object distance compatible projection lens also satisfies the following condition:

[0075] 15 <f<19,1.95≤f / D≤2.1,1.3<TR<1 .7;

[0076] Where f is the effective focal length of the multi-object distance compatible projection lens, in mm; D is the entrance pupil diameter, in mm; and TR is the projection ratio of the multi-object distance compatible projection lens.

[0077] Specifically, f / D can be 2.0 or 2.05. Meeting the above conditions, the projection lens has a large aperture, suitable for both low-cost, low-light projection devices and high-light projection devices, giving it broad applicability and meeting the needs of most projection scenarios on the market. Additionally, f can be 16.97 or 17 (mm). Meeting the above conditions allows for projection of the required image size at short distances; exceeding the upper limit results in a smaller lens angle and a smaller image size; falling below the lower limit requires an increased lens angle and a more complex lens design, failing to meet the miniaturization and low-cost requirements. TR can be 1.495 or 1.49. Meeting the above conditions facilitates the overall miniaturization of the projection device, projecting a larger image size at shorter distances. Exceeding the upper limit results in a small image size, affecting usability; falling below the lower limit results in a very short projection distance, increasing design complexity and requiring more lenses to compensate for distortion, hindering cost reduction.

[0078] In one embodiment, the multi-object distance compatible projection lens also satisfies the following condition:

[0079] 90 <TTL<130,40<TA<60,10<TB<27;

[0080] Where TTL is the total optical length of the projection lens that is compatible with multiple object distances, TA is the optical length of the front lens group, and TB is the optical length of the rear lens group, all in mm.

[0081] Specifically, TTL can be 106.2 or 107 mm. Meeting the above conditions ensures the projection lens has a small, compact size, meeting miniaturization requirements; exceeding the upper limit fails to meet miniaturization needs; falling below the lower limit compresses the lens space, hindering sharpness improvement and increasing material costs, potentially leading to excessive expenses. The optical length of the front lens group can be 51.7 or 52 mm, and the optical length of the rear lens group can be 23.5 or 24 mm. Meeting the above conditions effectively improves the relative illumination of the projection lens; exceeding these ranges reduces illumination, compromising the consistency of brightness between the center and edges of the projected image.

[0082] In one embodiment, the multi-object distance compatible projection lens also satisfies the following condition:

[0083] 1.5≤ SD 1 / SD 10≤1.9,0.045≤A1 / TTL<0.09,

[0084] 0.08≤A2 / TTL<0.12, 0.1≤A5 / TTL<0.2;

[0085] in, SD1 represents the edge ray height of the object-side surface of the first lens L1. SD 10 represents the edge ray height of the image side of the tenth lens L10, TTL represents the total optical length of the multi-object distance compatible projection lens, A1 represents the center air gap between the first lens L1 and the second lens L2, A2 represents the center air gap between the second lens L2 and the third lens L3, and A5 represents the center air gap between the fifth lens L5 and the sixth lens L6. All units are in mm.

[0086] Specifically, SD 1 / SD 8 can be 1.72 or 1.75. Meeting the above conditions, the aperture of the first lens L1 and the tenth lens L10 of the projection lens are very close, allowing the head and tail diameters to be essentially the same. This facilitates miniaturization of the projection device, reduces the exposed projection area, improves integration, reduces discomfort from exposure, and enhances the aesthetics of the projection device in space. Exceeding the upper limit results in an excessively large head size, reducing the aesthetics of the application; below the lower limit, the head size is too small, increasing design difficulty and requiring more lenses to compensate for optical distortion caused by the small head, which is detrimental to cost reduction. A1 can be 7.6 or 7.8 in mm, meeting the above conditions. This interval is variable, and by adjusting this interval (e.g., assembling the lens inside the lens barrel, which can be a split design, fine-tuning is achieved through threaded rotation between the lens barrels, eliminating the need for a complex focusing structure), it compensates for field curvature changes at different projection distances, ensuring clear projection from 229mm to 350mm. A2 can be 10.15 or 10.3 mm. A5 can be 15.2 or 15.4 mm. Satisfying the above conditions helps ensure that the lens thickness inside the projection lens is not too thick, thus improving the overall transmittance of the projection lens. If the above range is exceeded, the lens thickness inside the projection lens increases, the light absorption rate increases, which is not conducive to improving the overall transmittance of the projection lens.

[0087] In one embodiment, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, and the tenth lens L10 are all spherical glass lenses, and each lens has a transmittance of ≥90% in the 385nm~405nm wavelength range. At least two lenses in the front lens group have a refractive index greater than 1.7, and at least two lenses in the rear lens group have an Abbe number greater than 70.

[0088] Specifically, at least two lenses in the front lens group are made of high-refractive-index ultraviolet glass with a refractive index nd > 1.7; at least two lenses in the rear lens group are made of low-dispersion fluorophosphate glass with an Abbe number νd > 70. The spherical glass lens material must have a transmittance ≥ 90% in the 385nm~405nm wavelength range. A transmittance of 90% or 91% can improve light energy utilization. Insufficient light energy utilization leads to energy waste, a weakened signal-to-noise ratio, and a weaker signal received by the image source chip.

[0089] In one embodiment, the multi-object distance compatible projection lens also satisfies the following condition:

[0090] CRA<1°,28<BFL<37,TV DIST <0.15%;

[0091] Where CRA is the maximum ray angle of the multi-object distance compatible projection lens on the imaging plane, BFL is the on-axis distance from the image side of the tenth lens L10 to the imaging plane, in mm, and TV. DIST This refers to TV distortion on the imaging plane.

[0092] Specifically, CRA can be 0.5, 0.45, etc., in degrees. Meeting these conditions ensures the telecentricity of the projection lens is within a small range, guaranteeing alignment between the lens and the light output direction, improving light output efficiency from the center to the edge of the image, and avoiding uneven brightness. Exceeding this range results in excessive telecentricity, easily leading to low light output efficiency and affecting image brightness and uniformity. BFL can be 30, 31, etc., in mm. BFL also includes the thickness of the equivalent galvanometer and equivalent prism of the projection lens. Meeting these conditions allows the projection lens to be matched with a larger back focal length, sufficient prism space and light output / heat dissipation space, and can accommodate more projection optical engines. Exceeding the upper limit results in an excessively large back focal length, increasing the design difficulty and cost of the projection lens; below the lower limit, the back focal length is too small, which is detrimental to the lighting path arrangement and optical engine heat dissipation, affecting the user experience. Additionally, TV... DIST The distortion can be 0.05% or 0.13%. Keeping TV distortion within a small range ensures that the distortion of the projected image is almost imperceptible to the human eye in both the horizontal and vertical directions, thus improving comfort. Exceeding this range results in excessive distortion, causing significant viewing discomfort and affecting the 3D printing effect. The imaging surface is located on the image source chip.

[0093] For ease of understanding, specific schemes will be explained in detail below. The reference wavelength for the effective focal length, Abbe number, and refractive index in each scheme is 385nm.

[0094] Option 1:

[0095] like Figure 1As shown, in this embodiment, the projection lens includes a front lens group, an aperture stop (STO), a rear lens group, an equivalent galvanometer (L11), an equivalent prism (L12), a protective glass (CG), and an image source chip (DMD) arranged sequentially along the light incident direction (i.e., from the object plane to the image plane). The front lens group, along the object plane to the image plane, sequentially includes a first lens (L1) with convex-concave negative optical power, a second lens (L2) with convex-concave negative optical power, a third lens (L3) with biconvex positive optical power, a fourth lens (L4) with convex-concave positive optical power, and a fifth lens (L5) with convex-concave negative optical power. The rear lens group, along the object plane to the image plane, sequentially includes a sixth lens (L6) with concave-convex positive optical power, a seventh lens (L7) with biconvex negative optical power, an eighth lens (L8) with concave-convex positive optical power, a ninth lens (L9) with biconvex positive optical power, and a tenth lens (L10) with convex-concave positive optical power.

[0096] The effective focal length of this projection lens is f=16.97mm, the aperture number is Fno=2.0, the maximum image plane is 12.4mm, and the on-axis distance from the object side of the first lens L1 to the image source chip DMD is TTL=106.2mm; it can be seen that this projection lens can achieve high resolution, miniaturization, and a large image plane.

[0097] Specifically, the optical parameters of the projection lens are shown in Table 1:

[0098] Table 1

[0099]

[0100] like Figure 1 As shown, surface number S0 represents the object surface, and surface numbers S1, S3, S5, S7, S9, S12, S14, S16, S18, S20, S22, S24 to S26 represent the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the equivalent galvanometer L11, the equivalent prism L12, and the object surface of the protective glass CG, respectively. Surface numbers S2, S4, S6, S8, and S10 represent the object surface of the protective glass CG. S13, S15, S17, S19, S21, S13, S25 to S27 represent the image-side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the equivalent galvanometer L11, the equivalent prism L12, and the protective glass CG, respectively. STO represents the aperture stop, i.e., surface number S11. Surface number S28 represents the imaging surface of the image source chip (DMD, Digital Micromirror Device).

[0101] Based on the above data, Figure 2 , Figure 3 , Figure 4The graphs show the relationship between MTF and frequency for different fields of view at projection distances of 229mm, 287mm, and 350mm. The center and edges of the field of view have clear imaging at different frequencies, and the MTF of all fields of view is greater than 0.7 at the limiting frequency of 93p / mm. Figure 5 This indicates that the TV distortion of the projection lens is less than 0.15% within the range of the corresponding image source chip DMD size. In summary, the projection lens has good distortion control and excellent image quality.

[0102] Option 2:

[0103] like Figure 6 As shown, in this embodiment, the projection lens includes a front lens group, an aperture stop (STO), a rear lens group, an equivalent galvanometer (L11), an equivalent prism (L12), a protective glass (CG), and an image source chip (DMD) arranged sequentially along the light incident direction (i.e., from the object plane to the image plane). The front lens group, along the object plane to the image plane, sequentially includes a first lens (L1) with convex-concave negative optical power, a second lens (L2) with convex-concave negative optical power, a third lens (L3) with biconvex positive optical power, a fourth lens (L4) with convex-concave positive optical power, and a fifth lens (L5) with convex-concave negative optical power. The rear lens group, along the object plane to the image plane, sequentially includes a sixth lens (L6) with concave-convex positive optical power, a seventh lens (L7) with biconvex negative optical power, an eighth lens (L8) with concave-convex positive optical power, a ninth lens (L9) with biconvex positive optical power, and a tenth lens (L10) with convex-concave positive optical power.

[0104] The effective focal length of this projection lens is f=16.65mm, the aperture number Fno=2.0, the maximum image plane is 12.4mm, and the on-axis distance from the object side of the first lens L1 to the image source chip DMD is TTL=106.2mm; it can be seen that this projection lens can achieve high resolution, miniaturization, and a large image plane.

[0105] Specifically, the optical parameters of the projection lens are shown in Table 2:

[0106] Table 2

[0107]

[0108] like Figure 1As shown, surface number S0 represents the object surface, and surface numbers S1, S3, S5, S7, S9, S12, S14, S16, S18, S20, S22, S24 to S26 represent the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the equivalent galvanometer L11, the equivalent prism L12, and the object surface of the protective glass CG, respectively. Surface numbers S2, S4, S6, S8, and S10 represent the object surface of the protective glass CG. S13, S15, S17, S19, S21, S13, S25 to S27 represent the image-side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the equivalent galvanometer L11, the equivalent prism L12, and the protective glass CG, respectively. STO represents the aperture stop, i.e., surface number S11. Surface number S28 represents the imaging surface of the image source chip (DMD, Digital Micromirror Device).

[0109] Based on the above data, Figure 7 , Figure 8 , Figure 9 The graphs show the relationship between MTF and frequency for different fields of view at projection distances of 229mm, 287mm, and 350mm. The center and edges of the field of view have clear imaging at different frequencies, and the MTF of all fields of view is greater than 0.7 at the limiting frequency of 93p / mm. Figure 10 This indicates that the TV distortion of the projection lens is less than 0.15% within the range of the corresponding image source chip DMD size. In summary, the projection lens has good distortion control and excellent image quality.

[0110] Example 2:

[0111] A 3D printing device includes any of the aforementioned multi-object distance compatible projection lenses. Specifically, this 3D printing device, based on the projection lens in Embodiment 1, can achieve high resolution and low distortion, and can clearly adapt to a wide projection distance range of 229mm to 350mm, thereby matching a 0.75" image source chip, i.e., a chip with a resolution of 1080p, thus improving the quality of 3D printing. It achieves clear and non-distortion 3D printing effects under 350nm-450nm wavelength light, adapts to a wide temperature environment from -40℃ to 85℃, and exhibits good stability and compatibility.

[0112] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The embodiments described above are merely specific and detailed examples of the embodiments described in this application, and should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A projection lens compatible with multiple object distances, characterized in that: The multi-object distance compatible projection lens consists of a front lens group, an aperture stop (STO), and a rear lens group arranged sequentially from the object plane to the image plane. The front lens group consists of a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), and a fifth lens (L5) arranged sequentially from the object plane to the image plane. The rear lens group consists of a sixth lens (L6), a seventh lens (L7), an eighth lens (L8), a ninth lens (L9), and a tenth lens (L10) arranged sequentially from the object plane to the image plane. The first lens (L1), second lens (L2), fifth lens (L5), and seventh lens (L7) have negative optical power, while the third lens (L3), fourth lens (L4), sixth lens (L6), eighth lens (L8), ninth lens (L9), and tenth lens (L10) have positive optical power. The first lens (L1) can move relative to the second lens (L2) along the optical axis and satisfies the following conditions: -120<f A <-80,10<f B <30; Among them, f A f is the effective focal length of the front lens group. B The effective focal length of the rear lens group is in mm; The first lens (L1), the second lens (L2), the fourth lens (L4), the fifth lens (L5) and the tenth lens (L10) are all convex and concave lenses, the third lens (L3) and the ninth lens (L9) are both biconvex lenses, the sixth lens (L6) and the eighth lens (L8) are both concave and convex lenses, and the seventh lens (L7) is a biconcave lens. The multi-object distance compatible projection lens also meets the following conditions: -89 <f1< -72.8,-45.5<f2<-37.2,25.7<f3<31.4,73.9<f4<90.4, -27.4 <f5<-22.4,23.4<f6<28.5,-18<f7<-14.7,40.2<f8<49.1, 30<f9<36.6,87<f 10 <82; Among them, f1, f2, f3, f4, f5, f6, f7, f8, f9, f 10 The focal lengths of the first lens (L1), second lens (L2), third lens (L3), fourth lens (L4), fifth lens (L5), sixth lens (L6), seventh lens (L7), eighth lens (L8), ninth lens (L9), and tenth lens (L10) are, in mm.

2. The multi-object distance compatible projection lens as described in claim 1, characterized in that: The multi-object distance compatible projection lens also meets the following conditions: 31.9<R 11 <39,91.5<R 21 <111.89,36.6<R 31 <44.8,16.4<R 41 <20.1, 20.7<R 51 <25.3,-94.0<R 61 <-70,-16.9<R 71 <-13.9,-108<R 81 <-88.6, 71.2<R 91 <87.1,36.6<R 101 <44.7;19.8<R 12 <24.15,20.6<R 22 <25.2, -44.8<R 32 <-36.6,19.4<R 42 <23.7,7.8<R 52 <9.5,-14.5<R 62 <-11.8, 39.2<R 72 <50,-25.9<R 82 <-21.2,-27.6<R 92 <-22.7,93.7<R 102 <120; Among them, R 11 R 21 R 31 R 41 R 51 R 61 R 71 R 81 R 91 R 101 The following are the radii of curvature of the object-side surfaces of the first lens (L1), second lens (L2), third lens (L3), fourth lens (L4), fifth lens (L5), sixth lens (L6), seventh lens (L7), eighth lens (L8), ninth lens (L9), and tenth lens (L10), in mm; R 12 R 22 R 32 R 42 R 52 R 62 R 72 R 82 R 92 R 102 The curvature radii of the image-side surfaces of the first lens (L1), second lens (L2), third lens (L3), fourth lens (L4), fifth lens (L5), sixth lens (L6), seventh lens (L7), eighth lens (L8), ninth lens (L9), and tenth lens (L10) are in mm, respectively; "-" indicates the negative direction.

3. The multi-object distance compatible projection lens as described in claim 1, characterized in that: The multi-object distance compatible projection lens also meets the following conditions: 15 <f<19,1.95≤f / D≤2.1,1.3<TR<1 .7; Where f is the effective focal length of the multi-object distance compatible projection lens, in mm; D is the entrance pupil diameter, in mm; and TR is the projection ratio of the multi-object distance compatible projection lens.

4. The multi-object distance compatible projection lens as described in claim 1, characterized in that: The multi-object distance compatible projection lens also meets the following conditions: 90 <TTL<130,40<TA<60,10<TB< 27; Wherein, TTL is the total optical length of the multi-object distance compatible projection lens, TA is the optical length of the front lens group, and TB is the optical length of the rear lens group, all in mm.

5. The multi-object distance compatible projection lens as described in claim 1, characterized in that: The multi-object distance compatible projection lens also meets the following conditions: 1.5≤ SD 1 / SD 10≤1.9,0.045≤A1 / TTL<0.09, 0.08≤A2 / TTL<0.12, 0.1≤A5 / TTL<0.2; in, SD 1 represents the edge ray height of the object-side surface of the first lens (L1). SD 10 is the edge ray height of the image side of the tenth lens (L10), TTL is the total optical length of the multi-object distance compatible projection lens, A1 is the center air gap between the first lens (L1) and the second lens (L2), A2 is the center air gap between the second lens (L2) and the third lens (L3), and A5 is the center air gap between the fifth lens (L5) and the sixth lens (L6). All units are mm.

6. The multi-object distance compatible projection lens as described in claim 1, characterized in that: The first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), the fifth lens (L5), the sixth lens (L6), the seventh lens (L7), the eighth lens (L8), the ninth lens (L9), and the tenth lens (L10) are all spherical glass lenses, and each of the lenses has a transmittance of ≥90% in the 385nm~405nm wavelength range. At least two lenses in the front lens group have a refractive index greater than 1.7, and at least two lenses in the rear lens group have an Abbe number greater than 70.

7. The projection lens compatible with multiple object distances as described in claim 1, characterized in that: The multi-object distance compatible projection lens also meets the following conditions: CRA<1°,28<BFL<37,TV DIST <0.15%; Where CRA is the maximum ray angle of the multi-object distance compatible projection lens on the imaging plane, BFL is the on-axis distance from the image side of the tenth lens (L10) to the imaging plane, in mm, and TV. DIST This refers to TV distortion on the imaging plane.

8. A 3D printing device, characterized in that: The 3D printing equipment includes a multi-distance compatible projection lens as described in any one of claims 1 to 7.

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