Optical lens for projection

Abstract

The present invention provides an optical lens for projection, which comprises: 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 forward and backward along the optical axis of the optical lens for projection, a third lens group with positive optical power and a galvanometer, wherein an aperture is arranged between the lenses of the third lens group; the first lens group comprises a first lens and a second lens arranged in sequence, wherein the first lens faces the concave reflector. The present invention has the advantages of no distortion at large angles and image telecentricity.

Description

Technical Field

[0001] This invention relates to optical lenses, and more particularly to optical lenses for ultra-short throw projection. Background Technology

[0002] Currently, projectors are widely used, such as in the education sector. Projection lenses are a core module of projectors, but they typically suffer from drawbacks such as large spherical aberration, poor peripheral image quality, large lens length, increased distortion at larger angles, astigmatism, and significant axial chromatic aberration.

[0003] CN2018104678873 discloses an ultra-large projection range projection optical system, specifically comprising: a first lens group stationary relative to the DMD chip and a reflector, the first lens group having a negative optical power; a second lens group movable between the DMD chip and the first lens group, the second lens group having a positive optical power; a third lens group movable between the DMD chip and the second lens group, the third lens group having a negative optical power; and a fourth lens group stationary relative to the DMD chip and the third lens group, the fourth lens group having a positive optical power.

[0004] CN2017203198140 discloses an ultra-short-throw projection optical device, specifically comprising: a first lens group capable of moving back and forth relative to a DMD chip, the first lens group having positive optical power; a second lens group capable of moving back and forth relative to the DMD chip, the second lens group having positive optical power; a third lens group capable of moving back and forth relative to the DMD chip, the third lens group having negative optical power; and a fourth lens group stationary relative to the DMD chip, the fourth lens group having positive optical power. Summary of the Invention

[0005] To address the shortcomings of the existing technical solutions, the present invention provides a projection optical lens with high reliability, a wide angle, no distortion, and telecentric image.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An optical lens for projection, the optical lens for projection comprising:

[0008] A concave reflector, a first lens group with negative optical power, a second lens group with positive optical power that moves along the optical axis of the projection lens in both the positive and negative directions, a third lens group with positive optical power, and a galvanometer are arranged sequentially from the object side to the image side; the third lens group includes at least two lenses, and an aperture stop is disposed between the lenses of the third lens group.

[0009] The first lens group includes a first lens and a second lens arranged sequentially, with the first lens adjacent to the concave reflector, satisfying the following condition:

[0010]

[0011] f 1-1 f is the focal length of the first lens. 1-2 f1 is the focal length of the second lens and f2 is the focal length of the first lens group.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. High reliability;

[0014] Fewer second lens groups, i.e. fewer moving lenses, reduce structural complexity and cost, and improve operational reliability;

[0015] 2. No distortion at large angles;

[0016] The first lens is an odd-order aspherical design, which, together with the optimized surface shape of the second lens, which is also an odd-order aspherical, ensures that the optical distortion is less than 1% at a field of view of 140°.

[0017] The refractive index and Abbe number of the first lens need to meet a certain range to ensure that the system coma meets the requirements of 1080P lens imaging.

[0018] 3. Good image quality;

[0019] The second lens group consists of only a spherical lens or cemented lens group with positive optical power, which minimizes astigmatism and axial chromatic aberration of the system during the focusing process.

[0020] 4. Like Fang Yuanxin;

[0021] The third lens group uses a triplet lens assembly, which makes the divergence angles of the upper and lower rays closer, thus ensuring that the telecentricity of the lens is less than 0.1 degrees, while also reducing the coma of the lens. Attached Figure Description

[0022] The disclosure of this invention will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are merely illustrative of the technical solutions of this invention and are not intended to limit the scope of protection of this invention. In the drawings:

[0023] Figure 1 These are simplified structural diagrams of the projection optical lenses of Embodiments 1-2 of the present invention;

[0024] Figure 2 This is a simplified structural diagram of the projection optical lens of Embodiment 3 of the present invention;

[0025] Figure 3 This is a simplified structural diagram of the projection optical lens of Embodiment 4 of the present invention. Detailed Implementation

[0026] Figure 1-3 The following description illustrates optional embodiments of the invention to teach those skilled in the art how to implement and reproduce the invention. For the purpose of teaching the technical solutions of the 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 invention. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the invention. Therefore, the invention is not limited to the optional embodiments described below, but only to the claims and their equivalents. In the following embodiments, unless otherwise specified, the unit of focal length is millimeters.

[0027] Example 1:

[0028] Figure 1 A schematic diagram of the projection optical lens of Embodiment 1 of the present invention is shown, as follows: Figure 1 As shown, the projection optical lens includes:

[0029] A concave reflecting mirror 1, fixedly mounted first lens group with negative optical power, a second lens group with positive optical power that moves along the optical axis of the projection lens in both the positive and negative directions, a third lens group with positive optical power, and a galvanometer are arranged sequentially from the object side to the image side. The third lens group can be fixed, but preferably, it can also be movable to adjust the distance between itself and the sensor, i.e., adaptively adjust the distance between itself and the image plane, with a very small adjustment range. The third lens group includes at least two lenses, and an aperture stop A1 is disposed between the lenses of the third lens group.

[0030] The first lens group includes a first lens and a second lens arranged sequentially, with the first lens adjacent to the concave reflector, satisfying the following condition: f 1-1 f is the focal length of the first lens. 1-2 f is the focal length of the second lens, and f1 is the focal length of the first lens group. For example, 55mm ≤ f 1-2 -f 1-1 ≤70mm, -20mm≤f 1-1 ≤-15mm.

[0031] Furthermore, it can also satisfy:

[0032] R 11 K 11These are the radius of curvature and K value of the aspherical surface adjacent to the concave reflecting mirror of the first lens, respectively. 12 K 12 These are the radius of curvature and K value of the aspherical surface of the first lens facing away from the concave reflector, respectively.

[0033] The parameters of the first lens are as follows:

[0034] 1.45≤N d1 ≤1.6, 50≤V d1 ≤60.

[0035] To achieve even less distortion, the transmission surfaces of both the adjacent and opposite concave mirrors of the second lens are odd-order aspherical surfaces. For example, a K-shaped odd-order aspherical surface.

[0036] To achieve better optical performance, the focal length f2 of the second lens group further satisfies:

[0037] f is the effective focal length of the optical lens used for projection.

[0038] To obtain image-side telecenty, the third lens group further includes:

[0039] The sixth lens and the seventh lens, wherein the aperture stop is disposed in the optical path between the sixth lens and the seventh lens;

[0040] The triple-cemented lens group comprises three lenses with negative, positive, and negative optical powers arranged sequentially, positioned in the optical path between the seventh lens and the galvanometer; the focal length f of the triple-cemented lens group is... 3-0-3 satisfy f3 is the focal length of the third lens group. For example, 30mm ≤ |f 3-0-3 ≤35mm.

[0041] Light passes sequentially through the triplex lens group, the seventh lens, the aperture stop, and the sixth lens. In the current arrangement, the lens configuration is optimal, as there are no consecutive lenses with negative optical power, resulting in good chromatic aberration.

[0042] According to the above-described projection optical lens, preferably, 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 the following:

[0043] Preferably, f1∈[-50mm,-30mm], f2∈[180mm,220mm], f3∈[25mm,35mm], f∈[1.6mm,2.2mm].

[0044] According to the aforementioned projection optical lens, preferably, the first lens and / or the second lens are first aspherical lenses. The cross-sectional profile of at least one surface of the first aspherical lens on a reference plane containing the optical axis includes a first segment located in the middle, and two second segments located on either side of the first segment; the center of curvature of each point in the first segment is located on one side of the cross-sectional profile, and the center of curvature of each point in the second segment is located on the other side of the cross-sectional profile. This arrangement can be designed such that the first segment is concave inwards towards the first aspherical lens, and each of the second segments is convex outwards towards the first aspherical lens. Optionally, it can also be designed, as needed, that the first segment is convex outwards towards the first aspherical lens, and each of the second segments is concave inwards towards the first aspherical lens. That is, at least one of the first lens and the second lens is a hyperboloid, resulting in low distortion.

[0045] Example 2:

[0046] An application example of a projection optical lens according to Embodiment 1 of the present invention.

[0047] like Figure 1 As shown in this application example;

[0048] The reflecting surface of concave mirror 1 is aspherical;

[0049] The first lens group includes:

[0050] The first lens group, consisting of a K-shaped odd-order aspherical lens G1 with negative optical power, a K-shaped odd-order aspherical lens G2 with positive optical power, a spherical lens G3 with positive optical power, and a spherical lens G4 with negative optical power, has a focal length f1 ∈ [-50mm, -30mm]; lenses G1-G2 satisfy the following:

[0051] 55mm≤f 1-2 -f 1-1 ≤70mm, -20mm≤f 1-1 ≤-15mm;

[0052] Lens G1 satisfies: 1.45 ≤ N d1 ≤1.6, 50≤V d1 ≤60;

[0053] The second lens group includes:

[0054] The only lens, G5, has positive optical power and a focal length that satisfies the following:

[0055] The third lens group includes:

[0056] Lenses G6-G11, with optical powers of positive, positive, negative, positive, negative, and positive respectively, are arranged sequentially from the object side to the image side along the optical axis. Among them, lens G7 is an aspherical lens, and lenses G8-G10 are a group of cemented triplet lenses.

[0057] Table 1: Lens Structure Parameters

[0058]

[0059] Table 2: Parameters of various aspherical lenses

[0060]

[0061]

[0062] Table 3: Thickness Variable Table

[0063] 50-inch 65-inch 85-inch D1 -342 -445 -582 D2 15.13 14.83 14.61 D3 11.5 11.77 11.97 D4 4.87 4.9 4.92

[0064] Example 3:

[0065] An application example of a projection optical lens according to Embodiment 1 of the present invention.

[0066] like Figure 2 As shown in this application example;

[0067] The reflecting surface of concave mirror 1 is aspherical;

[0068] The first lens group includes:

[0069] The first lens group, consisting of a K-shaped odd-order aspherical lens G1 with negative optical power, a K-shaped odd-order aspherical lens G2 with positive optical power, a spherical lens G3 with positive optical power, and a spherical lens G4 with negative optical power, has a focal length f1 ∈ [-50mm, -30mm]; lenses G1-G2 satisfy the following:

[0070] 55mm≤f 1-2 -f 1-1 ≤70mm, -20mm≤f 1-1 ≤-15mm;

[0071] Lens G1 satisfies: 1.45 ≤ N d1 ≤1.6, 50≤V d1 ≤60;

[0072] The second lens group includes:

[0073] The only lens, G5, has positive optical power and a focal length that satisfies the following:

[0074] The third lens group includes:

[0075] Lenses G6-G11, with optical powers of positive, positive, negative, positive, negative, and positive respectively, are arranged sequentially from the object side to the image side along the optical axis. Among them, lens G7 is an aspherical lens, and lenses G8-G10 are a group of cemented triplet lenses.

[0076] Table 4: Lens structure parameters.

[0077]

[0078]

[0079] Table 5: Parameters of various aspherical lenses

[0080]

[0081]

[0082] Table 6: Thickness Variable Table

[0083] 50-inch 70-inch 90-inch D1 -343 -485 -618 D2 14.9 14.6 14.38 D3 11.21 11.48 11.68 D4 5.43 5.46 5.48

[0084] Example 4:

[0085] An application example of a projection optical lens according to Embodiment 1 of the present invention.

[0086] like Figure 3 As shown in this application example;

[0087] The reflecting surface of concave mirror 1 is aspherical;

[0088] The first lens group includes:

[0089] The first lens group, consisting of a K-shaped odd-order aspherical lens G1 with negative optical power, a K-shaped odd-order aspherical lens G2 with positive optical power, a spherical lens G3 with positive optical power, and a spherical lens G4 with negative optical power, has a focal length f1 ∈ [-50mm, -30mm]; lenses G1-G2 satisfy the following:

[0090] 55mm≤f 1-2 -f 1-1 ≤70mm, -20mm≤f 1-1 ≤-15mm;

[0091] Lens G1 satisfies: 1.45 ≤ N d1 ≤1.6, 50≤V d1 ≤60;

[0092] The second lens group includes:

[0093] Lenses G5 and G6 form a cemented doublet lens with positive optical power and a focal length that satisfies the following:

[0094] The third lens group includes:

[0095] Lenses G7-G12, with optical powers of positive, positive, negative, positive, negative, and positive respectively, are arranged sequentially from the object side to the image side along the optical axis. Among them, lens G8 is an aspherical lens, and lenses G9-G11 are a group of cemented triplet lenses.

[0096] Table 7: Lens structure parameters.

[0097]

[0098]

[0099] Table 8: Parameters of Various Aspherical Lenses

[0100]

[0101]

[0102] Table 9: Thickness Variable Table

[0103] 50-inch 70-inch 90-inch D1 -339 -475 -611 D2 15.12 14.82 14.6 D3 11.59 11.86 12.06 D4 4.47 4.5 4.52

Claims

1. An optical lens for projection, characterized in that: The projection optical lens comprises: A concave reflecting mirror, a first lens group with negative optical power, a second lens group with positive optical power and movable in the positive and reverse directions along the optical axis of the projection optical lens, a third lens group with positive optical power and a galvanometer are sequentially arranged from the object side to the image side; the third lens group includes at least two lenses, and a stop is arranged between the lenses of the third lens group; The first lens group includes a first lens and a second lens arranged in sequence, the first lens is adjacent to the concave reflector, and satisfies the following conditions: f 1-1 is the focal length of the first lens, f 1-2 is the focal length of the second lens, and f1 is the focal length of the first lens group; The parameters of the first lens are as follows: 1.45≤N d1 ≤1.6,50≤V d1 ≤60; The transmission surfaces of the second lens facing the concave reflector and the transmission surfaces facing away from the concave reflector are both odd-order aspherical surfaces; The third lens group comprises: a sixth lens and a seventh lens, wherein the aperture is arranged on an optical path between the sixth lens and the seventh lens; The triplet lens group includes three lenses with negative, positive and negative focal powers respectively arranged in sequence, and arranged in sequence on the optical path between the seventh lens and the galvanometer; the focal length f of the triplet lens group is 3-0-3 satisfy: f3 is the focal length of the third lens group; The focal length f2 of the second lens group satisfies: f is the effective focal length of the projection optical lens; The first lens and / or the second lens is a first aspherical lens, 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 respectively; the center of curvature of each point of the first section is located on one side of the cross-sectional contour line, and the center of curvature of each point of the second section is located on the other side of the cross-sectional contour line; At least one of the first lens and the second lens is a hyperbolic lens.

2. The projection optical lens according to claim 1, characterized in that: The light sequentially passes through the triplet lens group, the seventh lens, the aperture and the sixth lens.

3. The projection optical lens according to claim 1, characterized in that: The seventh lens is an aspherical lens.

4. The projection optical lens according to claim 1, characterized in that: 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:

5. The projection optical lens according to claim 4, characterized in that: f1∈[-50mm,-30mm], f2∈[180mm, 220mm], f3∈[25mm, 35mm], f∈[1.6mm, 2.2mm].

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