Zoom lens

Abstract

The present invention relates to a zoom lens, comprising a first fixed group (G1), a first zoom group (G2), an aperture (STOP), a second fixed group (G3), a second zoom group (G4) and a focusing group (G5) arranged in sequence from the object side to the image side along the optical axis, wherein the first zoom group (G2) and the second zoom group (G4) can move along the optical axis to complete the change of the zoom lens from wide angle to telephoto, and the focusing group (G5) is used to correct the movement of the image plane during the zooming process by moving along the optical axis. The zoom lens of the present invention can be applied to the security field, can realize the combination of high resolution, small distortion, large image plane and small volume, can adapt to the field where the monitoring distance has a large change, and has a high-quality imaging effect, and can be better applied to artificial intelligence fields such as face recognition.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a zoom lens. Background Art

[0002] With the increase in network speed, high-quality and high-resolution images can be transmitted quickly, so higher requirements are placed on the imaging quality of optical lenses in the security field. For example, the resolution and zoom range of the lens have higher indicators. The existing monitoring technology generally cannot achieve compatibility between a large image plane, a large magnification and a small size, and most of the monitoring lenses with large image planes are fixed-focus lenses, which are difficult to control when the monitoring distance changes. They are also large in size, with large optical distortion changes at different focal lengths, and low resolution (mostly 1080P, 2 million pixels), which is not enough to meet the needs of the increasingly popular artificial intelligence-related fields such as face recognition and license plate recognition. Summary of the invention

[0003] An object of the present invention is to provide a zoom lens.

[0004] To achieve the above-mentioned object of the invention, the present invention provides a zoom lens, comprising a first fixed group, a first zoom group, an aperture, a second fixed group, a second zoom group and a focusing group arranged in sequence from the object side to the image side along the optical axis, the first zoom group and the second zoom group can be moved along the optical axis to complete the change of the zoom lens from wide angle to telephoto, and the focusing group is used to correct the movement of the image plane during the magnification process by moving along the optical axis.

[0005] According to one aspect of the present invention, the first fixed group, the second fixed group and the second zoom group have positive optical power, and the first zoom group and the focusing group have negative optical power.

[0006] According to one aspect of the present invention, the first fixed group includes a first lens with negative optical power, a second lens with positive optical power, a third lens with positive optical power and a fourth lens with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis, and the first lens and the second lens are glued to form a glued lens group.

[0007] According to one aspect of the present invention, the first zoom group includes a fifth lens with negative 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 negative optical power, which are arranged in sequence from the object side to the image side along the optical axis;

[0008] The seventh lens and the eighth lens are cemented to form a cemented lens group, or the sixth lens, the seventh lens and the eighth lens are cemented to form a cemented lens group.

[0009] According to one aspect of the present invention, the second fixed group includes a tenth lens with positive optical power, an eleventh lens with negative optical power, a twelfth lens with positive optical power, a thirteenth lens with negative optical power, a fourteenth lens with positive optical power and a fifteenth lens with negative optical power, which are arranged in sequence from the object side to the image side along the optical axis.

[0010] According to one aspect of the present invention, the second fixed group at least includes a cemented lens group consisting of three lenses.

[0011] According to one aspect of the present invention, the second zoom group includes a sixteenth lens with positive refractive power, a seventeenth lens with negative refractive power and an eighteenth lens with positive refractive power, which are arranged in sequence from the object side to the image side along the optical axis.

[0012] According to one aspect of the present invention, the focusing group includes a nineteenth lens with positive refractive power, a twentieth lens with negative refractive power and a twenty-first lens with positive refractive power, which are arranged in sequence from the object side to the image side along the optical axis.

[0013] According to one aspect of the present invention, the focusing group includes at least one cemented lens group consisting of two lenses.

[0014] According to one aspect of the present invention, each of the first zoom group, the second fixed group, the second zoom group and the focusing group includes at least one glass or plastic aspherical lens.

[0015] According to one aspect of the present invention, it further includes a protective glass located on the side of the focused group image.

[0016] According to one aspect of the present invention, the focal length f1 of the first fixed group and the focal length fw of the zoom lens at the wide-angle end satisfy the following relationship: 2≤f1 / fw≤10.

[0017] According to one aspect of the present invention, the focal length f2 of the first zoom group and the focal length fw of the zoom lens at the wide-angle end satisfy the following relationship: -3≤f2 / fw≤-1.

[0018] According to one aspect of the present invention, the focal length f3 of the second fixed group and the focal length fw of the zoom lens at the wide-angle end satisfy the following relationship: 3≤f3 / fw≤6.8.

[0019] According to one aspect of the present invention, the focal length f4 of the second zoom group and the focal length fw of the zoom lens at the wide-angle end satisfy the following relationship: 1.3≤f4 / fw≤3.78.

[0020] According to one aspect of the present invention, the focal length f5 of the focus group and the focal length fw of the zoom lens at the wide-angle end satisfy the following relationship: -4.93≤f5 / fw≤-2.94.

[0021] According to one aspect of the present invention, the position of the aperture satisfies the relationship:

[0022] 0.41≤L S-IMG / TTL≤0.51;

[0023] Among them, L S-IMG is the distance from the aperture to the image plane, and TTL is the total optical length of the zoom lens.

[0024] According to one aspect of the present invention, a distance D1 that the first zoom group moves from the wide-angle end to the telephoto end and a total optical length TTL of the zoom lens satisfy the following relationship: 0.2≤D1 / TTL≤0.3.

[0025] According to one aspect of the present invention, a distance D2 that the second zoom group moves from the wide-angle end to the telephoto end and a total optical length TTL of the zoom lens satisfy the following relationship: 0.08≤D2 / TTL≤0.13.

[0026] According to one aspect of the present invention, the refractive index Nd of the fourteenth lens is L14 and Abbe number Vd L14 The following conditions are met: 1.70 <Nd L14 <1.95;20 <Vd L14 <50;

[0027] The refractive index Nd of the fourteenth lens L14 and the refractive index Nd of the fifteenth lens L15 Satisfies the following relationship: 0.01≤|Nd L14 -Nd L15 |≤0.2.

[0028] According to the solution of the present invention, a large image plane, high resolution, large zoom ratio (17 times) continuous zoom lens that can be applied to the security field is provided. The lens of the present invention is optimized for the large image plane and large zoom ratio, and can achieve high resolution, small distortion, large image plane and small volume. It can also be used with a large zoom ratio, and the resolution of the full focal length reaches 4K. It is suitable for large target surfaces such as 1 / 1.2" and high-resolution chips, so that it can adapt to the field where the monitoring distance varies greatly, and has a high-quality imaging effect. At the same time, the present invention corrects the distortion at the full focal length, and the distortion of the full focal length is less than 10%, which can be better applied to artificial intelligence fields such as face recognition.

[0029] According to one solution of the present invention, the zoom lens has two fixed groups, two zoom groups and one focusing group. Thus, the two zoom groups and one focusing group make it easier for the lens to achieve a large magnification. Among them, the zoom group is mainly used for zooming, and the focusing group is used to correct and compensate for the image plane offset generated during the zooming process. In addition, by reasonably setting the arrangement position, positive and negative properties of these lens groups, and the relationship between the focal length of each group and the focal length of the wide-angle end of the lens, the compatibility of a large zoom ratio, a large target surface and a small volume can be achieved.

[0030] According to one solution of the present invention, by reasonably setting the lens composition of two fixed groups and two zoom groups and the positive and negative properties of each lens, and reasonably setting a cemented lens group in the lens group, the two zoom groups are linked to each other to achieve a small volume and large magnification zoom.

[0031] According to one solution of the present invention, by reasonably setting the lens composition of the focusing group and the positive and negative properties of each lens, and providing at least one triple-cemented lens group in the second fixed group, the lens assembly performance can be ensured while correcting aberrations.

[0032] According to one solution of the present invention, at least one double-cemented lens group is arranged in the focusing group, and each group except the first fixed group contains at least one glass or plastic aspherical lens, thereby realizing a glass-plastic mixed combination to correct the defocus caused by high and low temperatures, so that the resolution equivalent to that at normal temperature can be maintained without refocusing under high and low temperature conditions.

[0033] According to one aspect of the present invention, the overall length of the zoom lens can be shortened by making the position of the diaphragm satisfy certain conditions.

[0034] According to one solution of the present invention, by properly setting the relationship between the distance that the two zoom groups move from the wide-angle end to the telephoto end and the total length of the lens, the possibility of the camera device composed of the zoom lens being too large can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram showing the structure of a zoom lens according to a first embodiment of the present invention;

[0036] Figure 2 The MTF diagram of the zoom lens of the first embodiment of the present invention at the wide-angle end under visible light at room temperature of 20 degrees is schematically shown;

[0037] Figure 3 The Through-Focus-MTF diagram of the zoom lens of the first embodiment of the present invention at the wide-angle end at a normal temperature of 20 degrees and infrared light of 850nm at night is schematically shown;

[0038] Figure 4 A diagram schematically showing the structure of a zoom lens according to a second embodiment of the present invention;

[0039] Figure 5 The MTF diagram of the zoom lens of the second embodiment of the present invention at the wide-angle end under the room temperature of 20 degrees and visible light is schematically shown;

[0040] Figure 6 The Through-Focus-MTF diagram of the zoom lens of the second embodiment of the present invention at the wide-angle end at a normal temperature of 20 degrees and infrared light of 850nm at night is schematically shown;

[0041] Figure 7 A schematic diagram showing the structure of a zoom lens according to a third embodiment of the present invention;

[0042] Figure 8 The MTF diagram of the zoom lens of the third embodiment of the present invention at the wide-angle end under the room temperature of 20 degrees and visible light is schematically shown;

[0043] Fig. 9 The Through-Focus-MTF diagram of the zoom lens according to the third embodiment of the present invention at the wide-angle end at a normal temperature of 20 degrees and at night infrared of 850nm is schematically shown. DETAILED DESCRIPTION

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0045] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0046] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0047] See also Figure 1The zoom lens of the present invention comprises a first fixed group G1, a first zoom group G2, an aperture STOP, a second fixed group G3, a second zoom group G4 and a focusing group G5 arranged in sequence from the object side to the image side along the optical axis, and also comprises a protective glass CG located on the image side of the focusing group G5. The first zoom group G2 and the second zoom group G4 can move along the optical axis to complete the change of the zoom lens from wide angle to telephoto, and the focusing group G5 is used to correct the movement of the image plane caused by the magnification change by moving along the optical axis. The first fixed group G1, the second fixed group G3 and the second zoom group G4 have positive optical power, and the first zoom group G2 and the focusing group G5 have negative optical power. In the present invention, the focal length f1 of the first fixed group G1 and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: 2≤f1 / fw≤10. The focal length f2 of the first zoom group G2 and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: -3≤f2 / fw≤-1. The focal length f3 of the second fixed group G3 and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: 3≤f3 / fw≤6.8. The focal length f4 of the second zoom group G4 and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: 1.3≤f4 / fw≤3.78. The focal length f5 of the focusing group G5 and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: -4.93≤f5 / fw≤-2.94. The above settings are met, so that the zoom lens of the present invention can achieve compatibility with a large zoom ratio, a large target surface and a small volume.

[0048] In the present invention, the first fixed group G1 includes a first lens L1 with negative optical power, a second lens L2 with positive optical power, a third lens L3 with positive optical power, and a fourth lens L4 with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis. The first lens L1 and the second lens L2 are cemented to form a cemented lens group to achieve aberration correction at the telephoto end. The first zoom group G2 includes a fifth lens L5 with negative 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 negative optical power, which are arranged in sequence from the object side to the image side along the optical axis. The seventh lens L7 and the eighth lens L8 are cemented to form a double cemented lens group, or the sixth lens L6, the seventh lens L7, and the eighth lens L8 are cemented to form a triple cemented lens group. The second fixed group G3 includes a tenth lens L10 with positive power, an eleventh lens L11 with negative power, a twelfth lens L12 with positive power, a thirteenth lens L13 with negative power, a fourteenth lens L14 with positive power, and a fifteenth lens L15 with negative power, which are arranged in sequence from the object side to the image side along the optical axis. The second zoom group G4 includes a sixteenth lens L16 with positive power, a seventeenth lens L17 with negative power, and an eighteenth lens L18 with positive power, which are arranged in sequence from the object side to the image side along the optical axis. With the above arrangement, the second zoom group G4 can be linked with the first zoom group G2, thereby realizing a small volume and a large magnification zoom.

[0049] In the present invention, the focusing group G5 includes a 19th lens L19 with positive power, a 20th lens L20 with negative power, and a 21st lens L21 with positive power, which are arranged in sequence from the object side to the image side along the optical axis. In addition, the second fixed group G3 includes at least one cemented lens group consisting of three lenses, that is, at least one three-cemented lens group. In this way, while correcting aberrations, it is also easy to ensure the assemblability of the lens.

[0050] In the present invention, the focusing group G5 includes at least one cemented lens group consisting of two lenses, that is, at least one double cemented lens group. In addition, each of the first zoom group G2, the second fixed group G3, the second zoom group G4 and the focusing group G5 includes at least one glass or plastic aspheric lens. In this way, the zoom lens adopts a glass-plastic hybrid lens combination, which can correct the defocus amount caused by high and low temperatures, so that the resolution can be maintained at the same level as that at normal temperature without refocusing under high and low temperature conditions.

[0051] In the present invention, the position of the aperture STOP satisfies the relationship: 0.41≤L S-IMG / TTL≤0.51. In the above formula, L S-IMGis the distance from the aperture stop STOP to the image plane, and TTL is the total optical length of the zoom lens, that is, the distance from the center vertex of the front surface of the first lens L1 to the imaging surface IMA. Therefore, when the position of the aperture stop STOP satisfies the above formula, the total length of the zoom lens can be made shorter.

[0052] In the present invention, the distance D1 moved by the first zoom group G2 from the wide angle end to the telephoto end and the total optical length TTL of the zoom lens satisfy the following relationship: 0.2≤D1 / TTL≤0.3. Furthermore, the distance D2 moved by the second zoom group G4 from the wide angle end to the telephoto end and the total optical length TTL of the zoom lens satisfy the following relationship: 0.08≤D2 / TTL≤0.13. Thus, the possibility of the camera device composed of the zoom lens being too large can be reduced.

[0053] In the present invention, the refractive index Nd of the fourteenth lens L14 is L14 and Abbe number Vd L14 The following conditions are met: 1.70 <Nd L14 <1.95;20 <Vd L14 <50. The refractive index Nd of the fourteenth lens L14 L14 and the refractive index Nd of the fifteenth lens L15 L15 Satisfies the following relationship: 0.01≤|Nd L14 -Nd L15 |≤0.2.

[0054] In summary, the zoom lens of the present invention uses an aspheric lens made of plastic material, thereby reducing production costs. Moreover, only two glass aspheric lenses are used in the lens, which reduces the sensitivity of the lens, makes the lens easy to process, and greatly increases the lens assembly yield. In addition, the zoom lens of the present invention can achieve high resolution, and when matched with a 13mm 1 / 1.2" CMOS, the full focal length can reach a resolution of 8 million. By adopting a glass-plastic hybrid solution, not only can the aberration of the zoom lens of the present invention be effectively corrected, but also the zoom lens of the present invention can be made not out of focus within a temperature range of -40°C to 80°C. The zoom lens of the present invention can also achieve a wide-angle end (non-constant aperture) FNO≤1.6, and a large zoom range of a magnification ratio greater than 17X. It can not only be used day and night, but also overcomes the contradictions between large relative aperture, day and night confocality, small distortion, high and low temperature out of focus and resolution, thereby increasing the use occasions and environmental conditions of the lens, and improving the quality and competitiveness of the lens product.

[0055] The zoom lens of the present invention is specifically described below using three groups of embodiments. In the following embodiments, S1, S2, ..., SN are used to represent the surfaces of each lens and the flat glass CG, the object surface is denoted as OBJ, the aperture is denoted as STOP, the image surface is denoted as IMA, and the cemented surface of the cemented lens group is denoted as one surface. The aspheric surface formula is as follows:

[0056]

[0057] Where z is the axial distance from the surface to the vertex at a height h perpendicular to the optical axis along the optical axis; c represents the curvature at the vertex of the aspheric surface; k is the cone coefficient; A4, A6, A8, A 10 , A 12 They represent the fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order aspheric coefficients respectively.

[0058] Parameters of various implementations that specifically meet the above conditional formula are shown in Table 1 below:

[0059]

[0060]

[0061] Table 1

[0062] First Implementation Method

[0063] See also Figure 1 In this embodiment, the seventh lens L7 and the eighth lens L8 in the first zoom group G2 are cemented to form a doublet group; the eleventh lens L11, the twelfth lens L12 and the thirteenth lens L13 in the second fixed group G3 are cemented to form a triplet group, the fourteenth lens L14 and the fifteenth lens L15 are cemented to form a doublet group; the nineteenth lens L19 and the twentieth lens L20 in the focusing group G5 are cemented to form a doublet group. Among them, the ninth lens L9 and the twenty-first lens L21 are made of plastic, and the tenth lens L10 and the sixteenth lens L16 are glass aspherical surfaces.

[0064] The parameters of the zoom lens in this embodiment include surface type, radius of curvature, thickness, refractive index of the material, and Abbe number, as shown in Table 2 below:

[0065]

[0066]

[0067] Table 2 The aspheric coefficients of each aspheric lens in this embodiment are shown in Table 3 below:

[0068] Surface number K A B C D E S15 1.055 0.00E+00 -2.76E-04 1.93E-06 -9.09E-09 1.87E-11 S16 -6.166 0.00E+00 -1.70E-04 1.47E-06 -7.36E-09 1.59E-11 S18 -0.841 0.00E+00 1.63E-06 2.65E-08 -5.75E-11 -5.60E-14 S19 0.000 0.00E+00 3.10E-06 3.09E-08 -1.30E-10 7.83E-14 S27 -0.118 0.00E+00 -3.21E-05 1.44E-07 -2.86E-09 1.53E-11 S28 6.998 0.00E+00 3.63E-05 2.77E-07 -3.54E-09 3.03E-11 S36 -0.075 0.00E+00 1.05E-04 2.34E-06 -5.01E-08 1.69E-09 S37 8.603 0.00E+00 1.72E-05 1.33E-06 -5.73E-08 1.64E-09

[0069] Table 3

[0070] Among them, K is the quadratic surface constant of the surface, and A, B, C, D, and E are the second-order, fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients respectively.

[0071] The distances between the various lens groups at the wide-angle end and the telephoto end of the zoom lens are shown in Table 4 below:

[0072] thickness Wide angle Telephoto D1 0.877 41.843 D2 42.449 1.483 D3 17.505 3.805 D4 6.659 0.350 D5 4.941 24.950

[0073] Table 4

[0074] Among them, D1 represents the distance from the image side of the first fixed lens group G1 to the object side of the first zoom lens group G2, D2 represents the distance from the image side of the second lens group G2 to the object side of the stop STOP, D3 represents the distance from the image side of the second fixed lens group G3 to the object side of the second zoom lens group G4, D4 represents the distance from the image side of the second zoom lens group G4 to the object side of the focus lens group G5, and D5 represents the distance from the image side of the focus lens group G5 to the object side of the protective glass CG. Among them, D1, D2, D3, D4, and D5 are different depending on the wide-angle end and the telephoto end.

[0075] Combination Figure 2 and Figure 3 It can be seen that the zoom lens of this embodiment maintains good resolution while achieving a large aperture and a large image surface, corrects the position chromatic aberration and magnification chromatic aberration between 380-940, and achieves full 4K resolution. The lens size is small, the image surface is large, and it is suitable for 1 / 1.2" chips. It has a large aperture and is suitable for low-light scenes and a large-magnification optical zoom.

[0076] Second implementation method

[0077] See also Figure 4 In this embodiment, the sixth lens L6, the seventh lens L7 and the eighth lens L8 in the first zoom group G2 are cemented to form a triplet group; the eleventh lens L11 and the twelfth lens L12 in the second fixed group G3 are cemented to form a doublet group, the thirteenth lens L13, the fourteenth lens L14 and the fifteenth lens L15 are cemented to form a triplet group; the nineteenth lens L19 and the twentieth lens L20 in the focusing group G5 are cemented to form a doublet group. Among them, the ninth lens L9 and the twenty-first lens L21 are made of plastic, and the tenth lens L10 and the sixteenth lens L16 are glass aspherical surfaces.

[0078] The parameters of the zoom lens in this embodiment include surface type, radius of curvature, thickness, refractive index of the material, and Abbe number, as shown in Table 5 below:

[0079]

[0080]

[0081] Table 5 The aspheric coefficients of each aspheric lens in this embodiment are shown in Table 6 below:

[0082] Surface number K A B C D E S14 0 0.00E+00 -2.80E-04 1.61E-06 -8.55E-09 2.42E-11 S15 -14.155 0.00E+00 -1.87E-04 1.15E-06 -5.27E-09 1.39E-11 S17 -4.015 0.00E+00 1.42E-06 1.59E-08 -7.31E-11 6.59E-14 S18 0.000 0.00E+00 3.24E-06 2.11E-08 -1.34E-10 2.24E-13 S26 -3.553 0.00E+00 -8.78E-06 1.04E-07 -2.27E-09 1.71E-11 S27 31.309 0.00E+00 4.50E-05 1.16E-07 -2.39E-09 3.29E-11 S35 -0.517 0.00E+00 6.24E-05 3.60E-07 -2.18E-08 9.52E-10 S36 21.081 0.00E+00 -5.33E-05 -2.78E-07 -3.09E-08 1.03E-09

[0083] Table 6

[0084] Among them, K is the quadratic surface constant of the surface, and A, B, C, D, and E are the second-order, fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients respectively.

[0085] The distances between each lens group at the wide-angle end and the telephoto end of the zoom lens are shown in Table 7 below:

[0086] thickness Wide angle Telephoto D1 0.482 40.814 D2 45.070 4.738 D3 18.838 0.867 D4 2.505 0.331 D5 2.376 22.521

[0087] Table 7

[0088] Among them, D1 represents the distance from the image side of the first fixed lens group G1 to the object side of the first zoom lens group G2, D2 represents the distance from the image side of the second lens group G2 to the object side of the stop STOP, D3 represents the distance from the image side of the stop to the object side of the second fixed lens group G3, D4 represents the distance from the image side of the second fixed lens group G3 to the object side of the second zoom lens group G4, and D5 represents the distance from the image side of the second zoom lens group G4 to the object side of the focus lens group G5. Among them, D1, D2, D3, D4, and D5 are different depending on the wide-angle end and the telephoto end.

[0089] Combination Figure 5 and Figure 6 It can be seen that the zoom lens of this embodiment maintains good resolution while achieving a large aperture and a large image surface, corrects the position chromatic aberration and magnification chromatic aberration between 380-940, and achieves full 4K resolution. The lens size is small, the image surface is large, and it is suitable for 1 / 1.2" chips. It has a large aperture and is suitable for low-light scenes and a large-magnification optical zoom.

[0090] The third implementation method

[0091] See also Figure 7 In this embodiment, the seventh lens L7 and the eighth lens L8 in the first zoom group G2 are cemented to form a doublet group; the eleventh lens L11, the twelfth lens L12 and the thirteenth lens L13 in the second fixed group G3 are cemented to form a triplet group, the fourteenth lens L14 and the fifteenth lens L15 are cemented to form a doublet group; the nineteenth lens L19 and the twentieth lens L20 in the focusing group G5 are cemented to form a doublet group. Among them, the ninth lens L9 and the twenty-first lens L21 are made of plastic, and the tenth lens L10 and the sixteenth lens L16 are glass aspherical surfaces.

[0092] The parameters of the zoom lens in this embodiment include surface type, radius of curvature, thickness, refractive index of the material, and Abbe number, as shown in Table 8 below:

[0093]

[0094]

[0095] Table 8

[0096] The aspheric coefficients of each aspheric lens in this embodiment are shown in Table 9 below:

[0097]

[0098]

[0099] Table 9

[0100] Among them, K is the quadratic surface constant of the surface, and A, B, C, D, and E are the second-order, fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients respectively.

[0101] The distances of the various lens groups at the wide-angle end and the telephoto end of the zoom lens are shown in Table 10 below:

[0102] thickness Wide angle Telephoto D1 1.572 33.629 D2 40.183 8.126 D3 15.494 0.486 D4 4.5 0.089 D5 2.015 21.434

[0103] Table 10

[0104] Among them, D1 represents the distance from the image side of the first fixed group G1 to the object side of the first zoom group G2, D2 represents the distance from the image side of the second lens group G2 to the object side of the diaphragm, D3 represents the distance from the image side of the diaphragm to the object side of the second fixed group G3, D4 represents the distance from the image side of the second fixed group G3 to the object side of the second zoom group G4, and D5 represents the distance from the image side of the second zoom group G4 to the object side of the focusing group G5. Among them, D1, D2, D3, D4, and D5 are different depending on the wide-angle end and the telephoto end.

[0105] Combination Figure 8 and Fig. 9 It can be seen that the zoom lens of this embodiment maintains good resolution while achieving a large aperture and a large image surface, corrects the position chromatic aberration and magnification chromatic aberration between 380-940, and achieves full 4K resolution. The lens size is small, the image surface is large, and it is suitable for 1 / 1.2" chips. It has a large aperture and is suitable for low-light scenes and a large-magnification optical zoom.

[0106] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A zoom lens, comprising a first fixed group (G1), a first zoom group (G2), an aperture (STOP), a second fixed group (G3), a second zoom group (G4) and a focusing group (G5), which are arranged in sequence from the object side to the image side along the optical axis, a total of five lens groups, characterized in that: The first zoom group (G2) and the second zoom group (G4) can move along the optical axis to complete the change of the zoom lens from wide angle to telephoto, and the focus group (G5) is used to correct the movement of the image plane during the zoom process by moving along the optical axis; The first fixed group (G1), the second fixed group (G3) and the second zoom group (G4) have positive optical power, and the first zoom group (G2) and the focus group (G5) have negative optical power; The first zoom group (G2) comprises a fifth lens (L5) with optical power, a sixth lens (L6) with optical power, a seventh lens (L7) with negative optical power, an eighth lens (L8) with positive optical power and a ninth lens (L9) with optical power, which are arranged in sequence from the object side to the image side along the optical axis, totaling five lenses; The second zoom group (G4) includes a sixteenth lens (L16) with positive refractive power, a seventeenth lens (L17) with negative refractive power, and an eighteenth lens (L18) with positive refractive power, which are arranged in sequence from the object side to the image side along the optical axis, a total of three lenses; The focusing group (G5) includes a nineteenth lens (L19) with positive focal power, a twentieth lens (L20) with negative focal power, and a twenty-first lens (L21) with optical power, which are arranged in sequence from the object side to the image side along the optical axis, totaling three lenses.

2. The zoom lens according to claim 1, wherein: The first fixed group (G1) comprises a first lens (L1) with negative optical power, a second lens (L2) with positive optical power, a third lens (L3) with positive optical power and a fourth lens (L4) with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis, a total of four lenses, and the first lens (L1) and the second lens (L2) are glued to form a glued lens group.

3. The zoom lens according to claim 1, wherein: The fifth lens (L5) has negative refractive power, the sixth lens (L6) has positive refractive power, and the ninth lens (L9) has negative refractive power; The seventh lens (L7) and the eighth lens (L8) are cemented to form a cemented lens group, or the sixth lens (L6), the seventh lens (L7) and the eighth lens (L8) are cemented to form a cemented lens group.

4. The zoom lens according to claim 1, wherein: The second fixed group (G3) includes a tenth lens (L10) with positive focal power, an eleventh lens (L11) with negative focal power, a twelfth lens (L12) with positive focal power, a thirteenth lens (L13) with negative focal power, a fourteenth lens (L14) with positive focal power and a fifteenth lens (L15) with negative focal power, which are arranged in sequence from the object side to the image side along the optical axis, totaling six lenses.

5. The zoom lens according to claim 4, wherein: The second fixed group (G3) comprises at least one cemented lens group consisting of three lenses.

6. The zoom lens according to claim 1, wherein: The twenty-first lens (L21) has positive refractive power.

7. The zoom lens according to claim 1, wherein: The focusing group (G5) at least comprises a cemented lens group consisting of two lenses.

8. The zoom lens according to claim 1, wherein: Each of the first zoom group (G2), the second fixed group (G3), the second zoom group (G4) and the focusing group (G5) includes at least one glass aspheric lens or a plastic aspheric lens.

9. The zoom lens according to any one of claims 1 to 8, characterized in that: The focal length f1 of the first fixed group (G1) and the focal length fw of the zoom lens at the wide-angle end satisfy the following relationship: 2≤f1 / fw≤10.

10. The zoom lens according to any one of claims 1 to 8, characterized in that: The focal length f2 of the first zoom group (G2) and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: -3≤f2 / fw≤-1.

11. The zoom lens according to any one of claims 1 to 8, characterized in that: The focal length f3 of the second fixed group (G3) and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: 3≤f3 / fw≤6.

8.

12. The zoom lens according to any one of claims 1 to 8, characterized in that: The focal length f4 of the second zoom group (G4) and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: 1.3≤f4 / fw≤3.

78.

13. The zoom lens according to any one of claims 1 to 8, characterized in that: The focal length f5 of the focus group (G5) and the focal length fw of the zoom lens at the wide angle end satisfy the following relationship: -4.93≤f5 / fw≤-2.

94.

14. The zoom lens according to any one of claims 1 to 8, characterized in that: The position of the stop (STOP) satisfies the relationship: 0.41≤L S-IMG / TTL≤0.51; Among them, L S-IMG is the distance from the aperture (STOP) to the image plane, and TTL is the total optical length of the zoom lens.

15. The zoom lens according to any one of claims 1 to 8, characterized in that: A distance D1 that the first zoom group (G2) moves from the wide-angle end to the telephoto end and a total optical length TTL of the zoom lens satisfy the following relationship: 0.2≤D1 / TTL≤0.

3.

16. The zoom lens according to any one of claims 1 to 8, characterized in that: A distance D2 that the second zoom group (G4) moves from the wide-angle end to the telephoto end and a total optical length TTL of the zoom lens satisfy the following relationship: 0.08≤D2 / TTL≤0.

13.

17. The zoom lens according to claim 4 or 5, characterized in that: The refractive index Nd of the fourteenth lens (L14) is L14 and Abbe number Vd L14 The following conditions are met: 1.70 <Nd L14 <1.95;20 <Vd L14 <50; The refractive index Nd of the fourteenth lens (L14) is L14 and the refractive index Nd of the fifteenth lens (L15) L15 Satisfies the following relationship: 0.01≤|Nd L14 -Nd L15 |≤0.2.

Images