An ultra-high-definition resolution projection lens

Abstract

The application discloses a kind of super-high-definition resolution projection lenses, projection lens successively includes the first lens of positive refractive power from object side to image side, the second lens of negative refractive power, the third lens of negative refractive power, the fourth lens of positive refractive power, the fifth lens of positive refractive power, the sixth lens of positive refractive power, the seventh lens of negative refractive power, the eighth lens of positive refractive power and the ninth lens of positive refractive power, diaphragm is arranged on the surface of fifth lens near object side, third lens and fourth lens form first double cemented lens group, sixth lens and seventh lens form second double cemented lens group.The application provides the projection lens that can realize super-high-definition resolution, can reduce imaging chromatic aberration, can be widely applied in projection lens technical field.

Description

Technical Field

[0001] This invention relates to the field of projection lens technology, and more particularly to an ultra-high-definition resolution projection lens. Background Technology

[0002] Common projection technologies on the market, such as Liquid Crystal Display (LCD) projection technology and Digital Light Processing (DLP) projection technology, mainly use chips smaller than one inch, with small pixel sizes. Their prices are easily affected by external factors and are relatively high in cost, especially for projection chips with a resolution of 4K, where the pixel size usually reaches 3.8μm, making production technically difficult and expensive. Therefore, in recent years, projection technology using single-panel large-panel LCDs has begun to be developed. The LCD panels used are usually larger than 4 inches, with pixel sizes typically above 30μm. The manufacturing difficulty of LCD panels has been greatly reduced, and the cost is also lower.

[0003] However, due to poor lens imaging and the fact that the production technology of projection LCD panels is still in its early stages, single LCD projectors are currently mainly used in the low-end projector market, with resolutions generally ranging from 720p to 1080p. There are no projection lenses that can achieve ultra-high-definition resolution, and when ordinary lenses are applied to single LCD projectors, the color difference in the image is relatively large. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide an ultra-high-definition resolution projection lens that can reduce chromatic aberration in imaging.

[0005] On one hand, the present invention provides an ultra-high-definition resolution projection lens, which, from the object side to the image side, sequentially includes a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power. An aperture stop is provided on the surface of the fifth lens near the object side.

[0006] The third lens and the fourth lens form a first cemented doublet lens group, and the sixth lens and the seventh lens form a second cemented doublet lens group.

[0007] Optionally, the second lens, the fifth lens, and the eighth lens are all aspherical lenses, the object surface of the eighth lens has a greater curvature than the first curvature, and the image surface of the eighth lens has a greater curvature than the second curvature.

[0008] Optionally, the first lens, the third lens, the fourth lens, the sixth lens, and the seventh lens are all spherical lenses.

[0009] Optionally, the ninth lens is a Fresnel lens.

[0010] Optionally, the distance between the first lens and the eighth lens is less than or equal to 75 mm.

[0011] Optionally, the focal length of the first lens and the focal length of the second lens satisfy the following relationship:

[0012] -3.0 <f1 / f2<-1.5

[0013] Where f1 is the focal length of the first lens and f2 is the focal length of the second lens.

[0014] Optionally, the focal lengths of the first cemented doublet lens group and the second cemented doublet lens group satisfy the following relationship:

[0015] -3.0 <f3 / f4<-1.5

[0016] Where f3 is the focal length of the first cemented doublet lens group and f4 is the focal length of the second cemented doublet lens group.

[0017] Optionally, the focal length of the second lens and the focal length of the fifth lens satisfy the following relationship:

[0018] -1.5 <f2 / f5<-0.5

[0019] Where f2 is the focal length of the second lens and f5 is the focal length of the fifth lens.

[0020] Optionally, the focal length of the eighth lens satisfies the following relationship:

[0021] -0.01 < 1 / f6 < 0.01

[0022] Here, f6 is the focal length of the eighth lens.

[0023] Optionally, the combined focal length of the first lens to the eighth lens and the distance of the eighth lens to the image plane satisfy the following relationship:

[0024] 0.8 <f7 / L<1.3

[0025] Where f7 is the combined focal length of the first lens to the eighth lens, and L is the distance from the eighth lens to the image plane.

[0026] The present invention provides the following advantages: The projection lens involved in this invention comprises, from the object side to the image side, a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power. An aperture stop is provided on the surface of the fifth lens near the object side. The third and fourth lenses form a first cemented doublet lens group, and the sixth and seventh lenses form a second cemented doublet lens group. The first lens has a positive optical power... The first lens has a focal length that focuses the light beam and corrects field curvature. The second lens has a negative focal length, effectively reducing the exit angle of the light rays emanating from the edges. The third and fourth lenses are cemented doublets, which correct chromatic aberration. The fifth lens, located behind the aperture stop, effectively reduces spherical aberration caused by the relatively large lens aperture. The sixth and seventh lenses are also cemented doublets, which correct chromatic aberration. By placing the aperture stop on the fifth lens and using a set of cemented doublets before and after the aperture stop, chromatic aberration can be effectively reduced, providing a projection lens capable of achieving ultra-high-definition resolution. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an ultra-high-definition resolution projection lens provided by the present invention;

[0028] Figure 2 This is a schematic diagram of the light source of an ultra-high-definition resolution projection lens provided by the present invention;

[0029] Figure 3 This is the MTF diagram of an ultra-high-definition resolution projection lens provided by the present invention;

[0030] Figure 4 This invention provides a field curvature diagram and distortion diagram of an ultra-high-definition resolution projection lens;

[0031] Figure 5 This is a schematic diagram of the light source of another ultra-high-definition resolution projection lens provided by the present invention;

[0032] Figure 6 This is an MTF diagram of another ultra-high-definition resolution projection lens provided by the present invention;

[0033] Figure 7 This invention provides a field curvature diagram and distortion diagram of another ultra-high-definition resolution projection lens. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0035] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0036] In the following description, when referring to the accompanying drawings, the same numbers in different drawings denote the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0037] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of an ultra-high-definition resolution projection lens. The present invention provides an ultra-high-definition resolution projection lens, which, from the object side to the image side, sequentially includes a first lens L1 with positive optical power, a second lens L2 with negative optical power, a third lens L3 with negative optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with positive optical power, a sixth lens L6 with positive optical power, a seventh lens L7 with negative optical power, an eighth lens L8 with positive optical power, and a ninth lens L9 with positive optical power. An aperture stop is disposed on the surface of the fifth lens L5 near the object side.

[0038] The third lens L3 and the fourth lens L4 form a first cemented doublet lens group, and the sixth lens L6 and the seventh lens L7 form a second cemented doublet lens group.

[0039] Specifically, the ultra-high definition resolution can be 4K or higher, and the aperture stop can be set on the front surface of the fifth lens, or the aperture stop can be close to the front surface of the fifth lens, which can simplify the mechanical structure of the lens.

[0040] The first lens L1 has positive optical power and acts as a light-gathering lens, while also correcting field curvature. The second lens L2 is a plastic aspherical lens with negative optical power, which effectively reduces the exit angle of light rays emanating from the edges. The third lens L3 and the fourth lens L4 are cemented doublets, which correct chromatic aberration. The fifth lens L5 is located behind the aperture stop and can effectively reduce spherical aberration caused by the relatively large aperture of the lens. The sixth lens L6 and the seventh lens L7 are cemented doublets, which also correct chromatic aberration.

[0041] In some embodiments, the second lens L2, the fifth lens L5, and the eighth lens L8 are all aspherical lenses, the object surface of the eighth lens L8 has a greater curvature than the first curvature, and the image surface of the eighth lens L8 has a greater curvature than the second curvature.

[0042] Specifically, the aspherical lens can be, but is not limited to, a plastic aspherical lens. With the object side in front and the image side behind, the curvature of the object side surface of the eighth lens L8 can be the curvature of the front surface of the eighth lens L8, and the curvature of the image side surface of the eighth lens L8 can be the curvature of the rear surface of the eighth lens L8. The first curvature and the second curvature can be the same or different, and both the first curvature and the second curvature are relatively large curvatures.

[0043] By using plastic aspherical lenses, the number of lenses can be reduced and the air gap between lenses can be shortened, making the lens structure more compact. The eighth lens L8 uses a plastic aspherical lens, and the front and rear surfaces of the aspherical lens have large inflection, which effectively reduces field curvature and astigmatism.

[0044] The material of the second lens L2 may be, but is not limited to, polycarbonate (PC); the materials of the fifth lens L5 and the eighth lens L8 may be, but are not limited to, copolymers of cycloolefins (COC); and the material of the ninth lens L9 may be, but is not limited to, polymethyl methacrylate (PMMA).

[0045] In some embodiments, the first lens L1, the third lens L3, the fourth lens L4, the sixth lens L6, and the seventh lens L7 are all spherical lenses, and the ninth lens L9 is a Fresnel lens.

[0046] Among them, the spherical lens can be, but is not limited to, a glass spherical lens.

[0047] Specifically, the first lens L1 may be, but is not limited to, a plano-convex glass spherical lens; the third lens L3 may be, but is not limited to, a biconcave glass spherical lens; the fourth lens L4 may be, but is not limited to, a biconvex glass spherical lens; the sixth lens L6 may be, but is not limited to, a biconvex glass spherical lens; and the seventh lens L7 may be, but is not limited to, a biconcave glass spherical lens.

[0048] The ninth lens, L9, is a plastic Fresnel lens, which can reduce the incident angle of the principal ray at the edge of the field of view and improve the light efficiency of the projection.

[0049] In some embodiments, the distance between the first lens L1 and the eighth lens L8 is less than or equal to 75 mm.

[0050] By using plastic aspherical surfaces, reducing the number of lenses and shortening the air gap between lenses, the distance between the first lens L1 and the eighth lens L8 can be limited, making the lens structure more compact.

[0051] Optionally, the focal length of the first lens L1 and the focal length of the second lens L2 satisfy the following relationship:

[0052] -3.0 < f1 / f2 < -1.5 (1)

[0053] Where f1 is the focal length of the first lens L1 and f2 is the focal length of the second lens L2.

[0054] Optionally, the focal lengths of the first cemented doublet lens group and the second cemented doublet lens group satisfy the following relationship:

[0055] -3.0 < f3 / f4 < -1.5 (2)

[0056] Where f3 is the focal length of the first cemented doublet lens group and f4 is the focal length of the second cemented doublet lens group.

[0057] Optionally, the focal length of the second lens L2 and the focal length of the fifth lens L5 satisfy the following relationship:

[0058] -1.5 < f2 / f5 < -0.5 (3)

[0059] Where f2 is the focal length of the second lens L2 and f5 is the focal length of the fifth lens L5.

[0060] Optionally, the focal length of the eighth lens L8 satisfies the following relationship:

[0061] -0.01 < 1 / f6 < 0.01 (4)

[0062] Where f6 is the focal length of the eighth lens L8.

[0063] Optionally, the combined focal length of the first lens L1 to the eighth lens L8 and the distance of the eighth lens L8 to the image plane satisfy the following relationship:

[0064] 0.8 < f7 / L < 1.3 (5)

[0065] Where f7 is the combined focal length of the first lens L1 to the eighth lens L8, and L is the distance from the eighth lens L8 to the image plane.

[0066] In some embodiments, such as Figure 1 As shown, Figure 1The present invention provides a projection system, which includes the projection lens and image plane described above.

[0067] The optical system of the present invention may have a projection ratio of 1.2, but is not limited to 1.2, an F-number (lens speed) of 3.0, and a projection chip of 5 inches with a resolution of 3840×2160 and a pixel size of 28.8μm, and the image reaches 4K resolution.

[0068] The present invention offers the following advantages: The first lens L1, with positive optical power, acts as a light-gathering element and corrects field curvature. The second lens L2, with negative optical power, effectively reduces the exit angle of edge-emitting rays. The third and fourth lenses L3 and L4, being cemented doublets, correct chromatic aberration. The fifth lens L5, positioned behind the aperture stop, effectively reduces spherical aberration caused by the relatively large lens aperture. The sixth and seventh lenses L6 and L7, also cemented doublets, correct chromatic aberration. By placing the aperture stop on the fifth lens L5 and using a set of cemented doublets before and after the aperture stop, chromatic aberration is effectively reduced, providing a projection lens capable of achieving ultra-high-definition resolution. The use of plastic aspherical lenses reduces the number of lenses and shortens the air gap between them, resulting in a compact lens structure. The eighth lens L8, also a plastic aspherical lens, has significant curvature on both its front and rear surfaces, effectively reducing field curvature and astigmatism. The ninth lens L9, a plastic Fresnel lens, reduces the incident angle of the principal rays at the edge of the field of view, improving the light efficiency of the projection.

[0069] In some embodiments, the present invention provides optical data for a lens, the optical data including the optical parameters of each lens of the projection lens described above, the optical parameters including radius of curvature R, air gap d, refractive index n and image distance v, as shown in Table 1, wherein the side of each lens facing the object side is the front surface (smaller surface number), and the side of the lens facing the image side is the rear surface (larger surface number).

[0070] Table 1

[0071] Face number R d n v 1(L1) Infinity 4.05 1.71 53.83 2(L1) -166.26 5.50 3(L2) -60.14 3.98 1.58 30.37 4(L2) -676.68 6.07 5(L3) -84.46 1.29 1.68 31.16 6(L4) 56.85 9.20 1.84 23.78 7(L4) -178.70 2.94 8 (Aperture) 82.80 8.04 1.53 55.71 9(L5) -245.51 1.52 10(L6) 80.58 15.53 1.69 54.53 11(L7) -50.88 1.20 1.64 33.84 12(L7) 69.09 8.49 13(L8) -86.73 4.50 1.53 55.71 14(L8) -73.94 120.00 15(L9) Infinity 2.00 1.49 57.44 16(L9) -68.42 14.15

[0072] The aspherical surface of each aspherical lens is an even-order aspherical surface. The expression for the sag z of the vertex of the aspherical surface along the optical axis at a height of r is shown in formula (6):

[0073]

[0074] Where c represents the vertex curvature of the aspherical surface, k is the conic coefficient of the aspherical surface, and α2, α3, α4, α5, α6, and α7 are the higher-order aspherical surface coefficients. The order coefficients of each aspherical lens are shown in Table 2. Table 2 is a reference table of order coefficients of each lens provided by the present invention. In the table, E-xx represents 10 to the power of xx.

[0075] Table 2

[0076]

[0077] Under the parameters of each lens in Table 1-2, such as Figures 2-4 As shown, Figure 2 This is a schematic diagram of the light rays in a projection lens with ultra-high-definition resolution. Figure 3 This is an MTF (Mean Transformer Frequency) chart of an ultra-high-definition projection lens. In the chart, the horizontal axis represents spatial frequency, which is equal to period / mm, and the vertical axis represents the optical transfer function (OTF) amplitude. Figure 4 It is a field curvature and distortion map of an ultra-high-definition projection lens, obtained through... Figures 2-4 It can be seen that the modulation transfer function (MTF) of the projection lens is above 0.55 at a spatial frequency of 18 lp / mm across the entire field of view, achieving high 4K resolution image quality, with distortion within 0.3%, exhibiting the characteristic of low distortion.

[0078] In some embodiments, the present invention provides optical data for another projection lens, as shown in Table 3, wherein the side of each lens facing the object is the front surface (with a smaller surface number), and the side of the lens facing the image is the rear surface (with a larger surface number).

[0079] Table 3

[0080] Face number R d n v 1(L1) Infinity 4.05 1.71 53.83 2(L1) -166.26 5.50 3(L2) -60.14 3.98 1.58 30.37 4(L2) -676.68 6.07 5(L3) -84.46 1.29 1.68 31.16 6(L4) 56.85 9.20 1.84 23.78 7(L4) -178.70 2.94 8 (Aperture) 82.80 8.04 1.53 55.71 9(L5) -245.51 1.52 10(L6) 80.58 15.53 1.69 54.53 11(L7) -50.88 1.20 1.64 33.84 12(L7) 69.09 8.49 13(L8) -86.73 4.50 1.53 55.71 14(L8) -73.94 120.00 15(L9) Infinity 2.00 1.49 57.44 16(L9) -68.42 14.15

[0081] For the coefficients of the non-curved lens terms in formula (6), refer to Table 4. Table 4 is a reference table for the coefficients of the non-curved lens terms:

[0082] Table 4

[0083]

[0084] Under the parameters of each lens in Table 3-4, such as Figures 5-7 As shown, Figure 5 This is a schematic diagram of the light rays from another type of ultra-high-definition resolution projection lens. Figure 6 This is the MTF chart of another type of ultra-high-definition resolution projection lens. Figure 7 It is a field curvature and distortion diagram of another type of ultra-high-definition resolution projection lens, through... Figures 5-7It can be seen that the modulation transfer function (MTF) of the projection lens at a spatial frequency of 18 lp / mm is above 0.58 across the entire field of view, achieving high 4K resolution image quality with distortion within 0.6% and minimal optical distortion.

[0085] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0086] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A projection lens with ultra-high resolution, characterized in that, The projection lens, from object side to image side, includes a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power. An aperture stop is provided on the surface of the fifth lens near the object side. The first, third, fourth, sixth, and seventh lenses are all spherical lenses; the second, fifth, and eighth lenses are all aspherical lenses. The projection lens has nine lenses with optical power. The image side of the first lens is convex; the object side of the second lens is concave, and the image side is convex; the third lens is a biconcave lens; the fourth lens is a biconvex lens; the image side of the fifth lens is concave; the sixth lens is a biconvex lens; the seventh lens is a biconcave lens; and the object side of the eighth lens is concave, and the image side is convex. The third lens and the fourth lens form a first cemented doublet lens group, and the sixth lens and the seventh lens form a second cemented doublet lens group; The focal lengths of the first lens and the second lens satisfy the following relationship: -3.0 <f1 / f2<-1.5 Where f1 is the focal length of the first lens and f2 is the focal length of the second lens.

2. The projection lens according to claim 1, characterized in that, The inflection of the object surface of the eighth lens is greater than the first inflection, and the inflection of the image surface of the eighth lens is greater than the second inflection.

3. The projection lens according to claim 1, characterized in that, The ninth lens is a Fresnel lens.

4. The projection lens according to claim 1, characterized in that, The distance between the first lens and the eighth lens is less than or equal to 75 mm.

5. The projection lens according to any one of claims 1-3, characterized in that, The focal lengths of the first cemented doublet lens group and the second cemented doublet lens group satisfy the following relationship: -3.0 <f3 / f4<-1.5 Where f3 is the focal length of the first cemented doublet lens group and f4 is the focal length of the second cemented doublet lens group.

6. The projection lens according to any one of claims 1-3, characterized in that, The focal lengths of the second lens and the fifth lens satisfy the following relationship: -1.5 <f2 / f5<-0.5 Where f2 is the focal length of the second lens and f5 is the focal length of the fifth lens.

7. The projection lens according to any one of claims 1-3, characterized in that, The focal length of the eighth lens satisfies the following relationship: -0.01 <1 / f6<0.01 Here, f6 is the focal length of the eighth lens.

8. The projection lens according to any one of claims 1-3, characterized in that, The combined focal length of the first lens to the eighth lens and the distance of the eighth lens to the image plane satisfy the following relationship: 0.8 <f7 / L<1.3 Where f7 is the combined focal length of the first lens to the eighth lens, and L is the distance from the eighth lens to the image plane.

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