Optical lens for projection

Abstract

The present invention provides an optical lens for projection, the optical lens for projection comprising: a concave reflector arranged in sequence from the object side to the image side, a first lens group with negative optical power, a second lens group with positive optical power moving in the positive and reverse directions along the optical axis of the optical lens for projection, a third lens group with positive optical power and a galvanometer; the relative aperture FNo of the optical lens for projection satisfies: FNo∈[1.8,2.2]; the focal length f of the movable lens group 2 And the focal length f of the projection optical lens satisfies: #imgabs0#The present invention has the advantages of no distortion at large angles, large aperture, image telecentricity, 4K imaging, etc.

Description

Technical Field

[0001] The invention relates to an optical lens, in particular to an optical lens for ultra-short-throw projection. Background Art

[0002] At present, projectors have been widely used, such as in the education industry. The optical lens for projection is the core module of the projector, but it usually has shortcomings such as large spherical aberration, poor peripheral image quality, large length, greater distortion with larger angles, large astigmatism and axial chromatic aberration, such as:

[0003] CN2018104678873 discloses a projection optical system with an ultra-large projection range, which specifically includes: a first lens group that is stationary relative to the DMD chip is arranged between the DMD chip and the reflector, and the optical focal length of the first lens group is negative; a second lens group that can move between the DMD chip and the first lens group is arranged between the DMD chip and the first lens group, and the optical focal length of the second lens group is positive; a third lens group that can move between the DMD chip and the second lens group is arranged between the DMD chip and the second lens group, and the optical focal length of the third lens group is negative; a fourth lens group that is stationary relative to the DMD chip is arranged between the DMD chip and the third lens group, and the optical focal length of the fourth lens group is positive.

[0004] CN2017203198140 discloses an ultra-short-focus projection optical device, which specifically includes: a first lens group that can move forward and backward relative to a DMD chip, and the optical focal length of the first lens group is positive; a second lens group that can move forward and backward relative to the DMD chip, and the optical focal length of the second lens group is positive; a third lens group that can move forward and backward relative to the DMD chip, and the optical focal length of the third lens group is negative; and a fourth lens group that is stationary relative to the DMD chip, and the optical focal length of the fourth lens group is positive. Summary of the invention

[0005] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides an optical lens for projection with good reliability, large aperture, large angle, no distortion, image-space telecentricity, and 4K imaging.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] An optical lens for projection, comprising:

[0008] A concave reflecting mirror arranged in sequence from the object side to the image side, a first lens group which is fixed and has negative optical power, a second lens group which has positive optical power and moves in the positive and reverse directions along the optical axis of the projection optical lens, a third lens group which has positive optical power, and a galvanometer mirror; the third lens group includes at least two lenses, and a stop is arranged between the lenses of the third lens group;

[0009] The relative aperture FNo of the projection optical lens satisfies: FNo∈[1.8,2.2];

[0010] The focal length f2 of the movable lens group and the focal length f of the projection optical lens satisfy:

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. Good reliability;

[0013] Fewer second lens groups, i.e., fewer moving lenses, reduce structural complexity and cost, and improve operational reliability;

[0014] 2. No distortion at large angles;

[0015] The lens of the first lens group is designed in a funnel shape, which, together with the optimization of the aspherical surface of the reflective surface of the reflector, such as the selection of curvature and K value, ensures that the optical distortion is less than 1%;

[0016] 3. Large aperture;

[0017] The second lens group can not only adjust the aberration caused by the change of picture size during movement, but also adjust the spherical aberration and coma introduced by the large aperture;

[0018] 4. High peripheral brightness ratio;

[0019] The lens of the third lens group facing the galvanometer (i.e., closest to the galvanometer) is a second aspherical lens, and the focal length of the lens and the distance (from the lens to the galvanometer) meet special conditions, ensuring image quality while having a high peripheral brightness ratio, thereby improving the overall efficiency of the lens;

[0020] 5. 4K imaging is achieved;

[0021] The second lens group includes at least one third aspherical lens, especially the lens facing (i.e., closest to) the aperture. The special design of curvature and K value can minimize the astigmatism and axial chromatic aberration of the lens during the mobile focusing process, thereby meeting the requirements of 4K imaging;

[0022] The first lens of the second lens group meets the high refractive index and low Abbe number range to ensure that the optical coma meets the requirements of 4K imaging;

[0023] 6. Like Fang Yuanxin;

[0024] The third lens group uses a combination of triplet and doublet lenses to make the divergence angles of the upper and lower rays closer, thus ensuring that the telecentricity of the lens is less than 0.1 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The disclosure of the present invention will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. In the drawings:

[0026] Figure 1 is a simplified structural diagram of an optical lens for projection according to Embodiment 1 of the present invention;

[0027] Figure 2 is a simplified structural diagram of an optical lens for projection according to Embodiment 2 of the present invention;

[0028] Figure 3 1 is a simplified structural diagram of an optical lens for projection according to Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0029] Figure 1-3 The following description describes optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art should understand that variations or substitutions derived from these embodiments will be within the scope of the present invention. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following optional embodiments, but is only limited by the claims and their equivalents. In the following embodiments, when the unit of focal length is not marked, the unit of focal length is millimeter.

[0030] Embodiment 1:

[0031] Figure 1 The structure diagram of the projection optical lens of the first embodiment of the present invention is schematically shown. Figure 1 As shown, the projection optical lens includes:

[0032] A concave reflector 1, a first lens group with negative focal length, a second lens group with positive focal length that moves forward and backward along the optical axis of the projection optical lens, a third lens group with positive focal length, and a galvanometer are sequentially arranged from the object side to the image side. The third lens group can be fixedly arranged, preferably, the third lens group can also be arranged movably, and can be used to adjust the distance between the sensor, that is, to adaptively adjust the distance between the sensor and the image plane, and the adjustment range is very small. The third lens group includes at least two lenses, and the aperture is arranged between the lenses of the third lens group.

[0033] The relative aperture FNo of the projection optical lens satisfies: FNo∈[1.8,2.2]. The focal length f1 of the first lens group, the focal length f2 of the second lens group, the focal length f3 of the third lens group, and the focal length f of the projection optical lens satisfy: Preferably, f1∈[-40mm,-25mm], f2∈[60mm,140mm]; f3∈[15mm,35mm]; f∈[1.6mm,2.2mm].

[0034] In order to achieve distortion-free operation at large angles, further, the first lens group includes at least one first aspheric lens, and the cross-sectional contour line of at least one side surface of the first aspheric lens on a reference plane where the optical axis is located includes a first section located in the middle, and two second sections located on both sides of the first section; the center of curvature of each point of the first section is on one side of the cross-sectional contour line, and the center of curvature of each point of the second section is on the other side of the cross-sectional contour line. This arrangement can be designed so that the first section is concave toward the inside of the first aspheric lens, and each second section is arched toward the outside of the first aspheric lens. Optionally, it can also be designed so that the first section is arched toward the outside of the first aspheric lens, and each second section is concave toward the inside of the first aspheric lens as needed. The projection surface of the first aspheric lens can be designed as the above-mentioned surface structure.

[0035] In some cases, the surface structure of the first aspheric lens may be referred to as a double recurved structure. Optionally, Optionally, the reflecting surface of the concave reflecting mirror is an aspherical surface, and the reflecting surface and the transmitting surface of the first lens group facing the concave reflecting mirror satisfy: R 反 is the curvature radius of the reflecting surface, K 反 is the K value of the reflecting surface, R 1-1 is the radius of curvature of the transmission surface, K 1-1 is the K value of the transmission surface.

[0036] In order to ensure that the telecentricity of the lens is less than 0.1 degrees, further, the third lens group includes:

[0037] The triplet lens group includes three lenses with negative, positive and negative optical powers arranged in sequence; the focal length f of the triplet lens group 3-0-3 satisfy: Specifically, 15mm≤f 3-0-3 ≤25mm;

[0038] The two-cemented lens group includes two lenses with positive and negative focal powers arranged in sequence, and the focal length of the two-cemented lens group is f 3-0-2 and the focal length f of the triplet 3-0-3 satisfy:

[0039] The light passes through the aperture, the three-cemented lens group and the two-cemented lens group in sequence. In the current arrangement state, the lens arrangement is better, there are no two consecutive lenses with negative focal power, and the chromatic aberration is good.

[0040] In order to improve the peripheral brightness ratio, further, the lens of the third lens group facing the galvanometer is a second aspherical lens and meets the following conditions:

[0041] f 3-0-1 is the focal length of the second aspheric lens, and d is the distance from the second aspheric lens to the galvanometer.

[0042] In order to reduce astigmatism and axial chromatic aberration to meet the requirements of 4K imaging, further, the lens of the second lens group facing the aperture is a third aspherical lens, and the two aspherical transmission surfaces meet the following conditions:

[0043]

[0044] R 2-0-1 is the radius of curvature of the first transmission surface of the third aspheric lens, R 2-0-2 is the radius of curvature of the second transmission surface of the third aspheric lens, K 2-0-1 is the K value of the first transmission surface, K 2-0-2 is the K value of the second transmission surface.

[0045] In order to reduce the coma aberration to meet the requirements of 4K imaging, further, the lens of the second lens group adjacent to the first lens group is the first lens. The first lens satisfies:

[0046] 1.9≤N d2 ≤2,15≤V d2 ≤25;N d2 is the refractive index of the first lens, V d2 is the Abbe number of the first lens.

[0047] Embodiment 2:

[0048] This is an application example of the projection optical lens according to Embodiment 1 of the present invention.

[0049] like Figure 1 As shown, in this application example;

[0050] The reflecting surface of the concave reflecting mirror 1 is an aspherical surface; the first lens group includes a first aspherical lens G1, f1∈[-35mm,-25mm].

[0051] The second lens group includes:

[0052] Lenses G2-G4 with negative, positive and negative optical powers are arranged in sequence from the object side to the image side along the optical axis, wherein the lens G4 facing the aperture stop is a third aspherical lens;

[0053] The third lens group includes:

[0054] Lenses G5-G11 with positive, negative, positive, negative, positive, negative and positive power arranged in sequence from the object side to the image side along the optical axis, wherein: lens G11 facing the galvanometer is a second aspheric lens; lenses G6-G8 are a triplet lens group, and lenses G9-G10 are a doublet lens group;

[0055] Table 1: Lens structural parameters.

[0056]

[0057] Table 2: Parameters of various aspherical lenses

[0058] Aspheric coefficient G1-R1 G1-R2 G4-R1 G4-R2 G11-R1 G11-R2 Mirror Y radius 46.67 -30.22 -369.43 -222.51 -36.04 24.29 -44.71 Quadratic surface constant (K) 0.80 -4.89 0.00 71.62 0.00 -0.27 -0.71 4th order coefficient (A) -1.55E-05 2.78E-05 -5.58E-05 -1.03E-04 1.15E-05 -3.05E-05 4.95E-07 6th order coefficient (B) 2.09E-08 -2.39E-08 1.32E-07 6.09E-08 -4.49E-08 -1.66E-08 -8.37E-11 8th order coefficient (C) -2.09E-11 2.29E-11 6.93E-10 1.46E-09 1.50E-10 9.21E-11 5.06E-15 10th order coefficient (D) 9.20E-15 -2.63E-14 -5.04E-12 -1.87E-11 -7.77E-13 -9.52E-13 -2.47E-18 12th order coefficient (E) 1.19E-17 2.19E-17 -1.12E-23 6.19E-25 1.16E-24 -2.01E-24 1.12E-21

[0059] Table 3: Thickness variable table

[0060] 80 inches 100 inches 120 inches D1 389 488 585 D2 -13.117 -12.817 -12.5968 D3 -10 -10.28 -10.48 D4 -6.83 -6.85 6.87

[0061] Embodiment 3:

[0062] This is an application example of the projection optical lens according to Embodiment 1 of the present invention.

[0063] like Figure 2 As shown, in this application example;

[0064] The reflecting surface of the concave reflecting mirror 1 is an aspherical surface;

[0065] The first lens group includes a first aspherical lens G1, f1∈[-35mm,-25mm].

[0066] The second lens group includes:

[0067] Lenses G2-G5 with negative, positive, positive and negative optical powers are arranged in sequence from the object side to the image side along the optical axis, wherein the lens G5 facing the aperture stop is a third aspherical lens;

[0068] The third lens group includes:

[0069] Lenses G6-G13 with optical powers of negative, positive, negative, positive, negative, positive, negative, positive, negative and positive are arranged in sequence from the object side to the image side along the optical axis, wherein: lens G13 facing the galvanometer is a second aspheric lens, lenses G6-G7 are a cemented lens group, lenses G8-G10 are a triple cemented lens group, and lenses G11-G12 are a double cemented lens group;

[0070] Table 4: Lens structural parameters.

[0071]

[0072]

[0073] Table 5: Parameters of various aspherical lenses

[0074]

[0075] Table 6: Thickness variable table

[0076]

[0077]

[0078] Embodiment 4:

[0079] This is an application example of the projection optical lens according to Embodiment 1 of the present invention.

[0080] like Figure 3 As shown, in this application example;

[0081] The reflecting surface of the concave reflecting mirror 1 is an aspherical surface;

[0082] The first lens group includes a first aspherical lens G1, f1∈[-35mm,-25mm].

[0083] The second lens group includes:

[0084] Lenses G2-G5 with negative, positive, positive and negative optical powers are arranged in sequence from the object side to the image side along the optical axis, wherein the lens G5 facing the aperture stop is a third aspherical lens;

[0085] The third lens group includes:

[0086] Lenses G6-G12 with positive, negative, positive, negative, positive, negative and positive power arranged in sequence from the object side to the image side along the optical axis, wherein: lens G12 facing the galvanometer is a second aspheric lens, lenses G7-G9 are a triplet lens group, and lenses G9-G10 are a doublet lens group;

[0087] Table 7: Lens structural parameters.

[0088]

[0089]

[0090] Table 8: Parameters of various aspherical lenses

[0091]

[0092] Table 9: Thickness variable table

[0093] 80 inches 100 inches 120 inches D1 389 488 585 D2 -13.6645 -13.3951 -13.2145 D3 -17.71 -17.9494 -18.13 D4 -6.8 -6.83 -6.85

Claims

1. An optical lens for projection, characterized in that: The projection optical lens comprises: A concave reflecting mirror arranged in sequence from the object side to the image side, a first lens group which is fixed and has negative optical power, a second lens group which has positive optical power and moves in the positive and reverse directions along the optical axis of the projection optical lens, a third lens group which has positive optical power, and a galvanometer mirror; the third lens group includes at least two lenses, and a stop is arranged between the lenses of the third lens group; The third lens group is movably arranged to adjust the distance between the lens group and the image plane; The relative aperture FNo of the projection optical lens satisfies: FNo∈[1.8,2.2]; The focal length f2 of the third lens group and the focal length f of the projection optical lens satisfy: The second lens group includes at least two lenses; The lens of the third lens group facing the galvanometer is a second aspherical lens and meets the following conditions: f 3-0-1 is the focal length of the second aspheric lens, and d is the distance from the second aspheric lens to the galvanometer; The lens of the second lens group facing the aperture is a third aspheric lens, and the two aspheric transmission surfaces satisfy: R 2-0-1 is the radius of curvature of the first transmission surface of the third aspheric lens, R 2-0-2 is the radius of curvature of the second transmission surface of the third aspheric lens, K 2-0-1 is the K value of the first transmission surface, K 2-0-2 is the K value of the second transmission surface; The lens of the second lens group adjacent to the first lens group is a first lens, and the first lens satisfies: 1.9≤N d2 ≤2,15≤V d2 ≤25;N d2 is the refractive index of the first lens, V d2 is the Abbe number of the first lens.

2. The projection optical lens according to claim 1, characterized in that: The first lens group includes at least one first aspherical lens, and the cross-sectional contour line of at least one side surface of the first aspherical lens on a reference plane where the optical axis is located includes a first segment located in the middle, and two second segments respectively located on both sides of the first segment; the center of curvature of each point of the first segment is on one side of the cross-sectional contour line, and the center of curvature of each point of the second segment is on the other side of the cross-sectional contour line.

3. The projection optical lens according to claim 1, characterized in that: The third lens group comprises: The triplet lens group includes three lenses with negative, positive and negative optical powers arranged in sequence; the focal length f of the triplet lens group 3-0-3 satisfy: The two-cemented lens group includes two lenses with positive and negative focal powers arranged in sequence, and the focal length of the two-cemented lens group is f 3-0-2 and the focal length f of the triplet 3-0-3 satisfy:

4. The projection optical lens according to claim 3, characterized in that: The light passes through the aperture, the triplet lens group and the doublet lens group in sequence.

5. The projection optical lens according to claim 1, characterized in that: The focal length f1 of the first lens group and the focal length f3 of the third lens group satisfy:

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