Zoom lens and imaging device

Abstract

The invention discloses a zoom lens and an imaging device, comprising a lens body, wherein the lens body consists of a lens barrel and a first lens group with positive focal power, a second lens group, a third lens group, a fourth lens group with negative focal power, a fifth lens group, a sixth lens group with positive focal power and a photosensitive chip which are sequentially arranged in the lens barrel from front to back. The second lens group, the third lens group, the fourth lens group and the fifth lens group are movably arranged in the front-back direction relative to the lens barrel, at least one of the third lens group and the fifth lens group moves along the optical axis to enable the zoom lens to zoom, and at least one of the second lens group and the fourth lens group moves along the optical axis to enable the zoom lens to focus. Through the reasonable arrangement of the six lens groups and the conditional restriction of the focal length of the zoom lens at the wide-angle end and the focal length ratio of each lens group, the zoom lens has the effects of small size, large magnification and large aperture.

Description

Technical Field

[0001] The present invention relates to the technical field of optical system design, and particularly relates to a zoom lens and an imaging device. Background Art

[0002] With the development of society, people's awareness of security prevention has been continuously improved, and the security monitoring industry has also developed rapidly, and the role played by monitoring is becoming more and more important. Zoom lenses have been actually designed and used since the last century. With the development of lens design technology, the application scenarios of zoom lenses have gradually increased. Nowadays, zoom lenses have been widely used in civilian products, security monitoring and other fields. However, due to the fact that the imaging quality of zoom lenses is worse than that of ordinary fixed-focus lenses, the popularity of zoom lenses is not high. Moreover, most of the zoom lenses on the market now have a small target surface size, resulting in a low resolution of the collected images, average shooting effects, and little value of the pictures. And most of the zoom lenses on the market now have a small aperture, resulting in less light transmission of the lens, and the images obtained in low-light scenarios are darker, making it difficult to ensure the image quality. With the advancement of security towards high definition and miniaturization, lenses are required to achieve higher performance and smaller volume. Summary of the Invention

[0003] The main object of the present invention is to provide a zoom lens, aiming to improve the technical problems in the prior art that the aperture of the zoom lens is small and large magnification and small volume cannot coexist.

[0004] To achieve the above object, the present invention provides a zoom lens, including a lens body. The direction from the object side to the image side along the optical axis of the lens body is from front to back;

[0005] The lens body includes a lens barrel and a first lens group with positive optical power, a second lens group with negative optical power, a third lens group with negative optical power, a fourth lens group with negative optical power, a fifth lens group with positive optical power, a sixth lens group with positive optical power, and an image sensor chip that are sequentially arranged in the lens barrel from front to back. The second lens group, the third lens group, the fourth lens group, and the fifth lens group are respectively movably arranged along the front-back direction relative to the lens barrel. At least one of the third lens group and the fifth lens group moves along the optical axis to cause the zoom lens to zoom, and at least one of the second lens group and the fourth lens group moves along the optical axis to cause the zoom lens to focus;

[0006] Wherein, the zoom lens satisfies the following conditions: 0.29 < fw / f1 < 2.57, and -8.77 < fw / f2 < -0.97, and -2.89 < fw / f3 < -0.32, and -2.16 < fw / f4 < -0.24, and 0.16 < fw / f5 < 1.47, and 0.05 < fw / f6 < 0.45;

[0007] Among them, fw is the focal length of the zoom lens at the wide-angle end, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, f4 is the focal length of the fourth lens group, f5 is the focal length of the fifth lens group, and f6 is the focal length of the sixth lens group.

[0008] Optionally, the first lens group includes a first lens with positive power, a second lens with negative power, a third lens with positive power, and a fourth lens with positive power, which are arranged in sequence from front to back;

[0009] The first lens group and the first lens, the second lens, the third lens and the fourth lens satisfy the following conditions: 0.05<f1 / f11<0.43, and -1.08<f1 / f12<-1.08, and 0.14<f1 / f13<1.29, and 0.13<f1 / f14<1.19;

[0010] Among them, f1 is the focal length of the first lens group, f11 is the focal length of the first lens, f12 is the focal length of the second lens, f13 is the focal length of the third lens, and f14 is the focal length of the fourth lens.

[0011] Optionally, the second lens group includes a fifth lens with negative optical power, a sixth lens with negative optical power and a seventh lens with negative optical power, which are arranged in sequence from front to back, and the fifth lens is an aspherical lens;

[0012] The second lens group and the fifth lens, the sixth lens and the seventh lens satisfy the following conditions: 0.18<f2 / f21<1.61, and 0.04<f2 / f22<0.38, and 0.04<f2 / f23<0.4;

[0013] Among them, f2 is the focal length of the second lens group, f21 is the focal length of the fifth lens, f22 is the focal length of the sixth lens, and f23 is the focal length of the seventh lens.

[0014] Optionally, the third lens group includes, arranged from front to back, an eighth lens with positive power, a ninth lens with positive power, a tenth lens with positive power, and an eleventh lens with negative power, wherein the eighth lens is an aspherical lens;

[0015] The third lens group and the eighth lens, the ninth lens, the tenth lens and the eleventh lens satisfy the following conditions: -2.63<f3 / f31<-0.29, and -3.71<f3 / f32<-0.41, and -2.47<f3 / f33<-0.27, and 1.07<f3 / f34<9.66;

[0016] Among them, f3 is the focal length of the third lens group, f31 is the focal length of the eighth lens, f32 is the focal length of the ninth lens, f33 is the focal length of the tenth lens, and f34 is the focal length of the eleventh lens.

[0017] Optionally, the fourth lens group includes a twelfth lens with positive power, a thirteenth lens with negative power and a fourteenth lens with positive power, which are arranged in sequence from front to back, and the fourteenth lens is an aspherical lens;

[0018] The fourth lens group and the twelfth lens, the thirteenth lens and the fourteenth lens satisfy the following relationship: -6.29<f4 / f41<-0.7, and 0.75<f4 / f42<6.74, and -3.46<f4 / f43<-0.38;

[0019] Among them, f4 is the focal length of the fourth lens group, f41 is the focal length of the twelfth lens, f42 is the focal length of the thirteenth lens, and f43 is the focal length of the fourteenth lens.

[0020] Optionally, the fifth lens group includes, arranged from front to back, a fifteenth lens with negative power, a sixteenth lens with positive power, a seventeenth lens with positive power, an eighteenth lens with negative power, a nineteenth lens with positive power, and a twentieth lens with negative power, wherein the twentieth lens is an aspherical lens;

[0021] The fifth lens group and the fifteenth lens, the sixteenth lens, the seventeenth lens, the eighteenth lens, the nineteenth lens and the twentieth lens satisfy the following relationship: -3.49<f5 / f51<-0.39, and 0.17<f5 / f52<1.57, and 0<f5 / f53<0.03, and -1.12<f5 / f54<-0.12, and 0.04<f5 / f55<0.39, and 0.28<f5 / f56<2.53;

[0022] Among them, f5 is the focal length of the fifth lens group, f51 is the focal length of the fifteenth lens, f52 is the focal length of the sixteenth lens, f53 is the focal length of the seventeenth lens, f54 is the focal length of the eighteenth lens, f55 is the focal length of the nineteenth lens, and f56 is the focal length of the twentieth lens.

[0023] Optionally, the fifteenth lens and the sixteenth lens constitute a fifth cemented lens; the seventeenth lens, the eighteenth lens, and the nineteenth lens constitute a sixth cemented lens.

[0024] Optionally, the sixth lens group includes a twenty-first lens having positive optical power, and the twenty-first lens is an aspherical lens.

[0025] Optionally, the zoom lens further includes an aperture stop, and the aperture stop is located between the third lens group and the fourth lens group;

[0026] The zoom lens satisfies the following conditions: 0.15<L / TTL<1.33;

[0027] Wherein, L is the distance from the aperture to the imaging surface of the zoom lens on the optical axis, and TTL is the total optical length of the zoom lens.

[0028] The present invention also provides an imaging device, which includes the zoom lens described in the above technical solution.

[0029] In the technical solution provided by the present invention, the lens body includes a lens barrel and a first lens group with positive focal power, a second lens group with negative focal power, a third lens group with negative focal power, a fourth lens group with negative focal power, a fifth lens group with positive focal power, a sixth lens group with positive focal power and a photosensitive chip which are sequentially arranged in the lens barrel from front to back. At least one of the third lens group and the fifth lens group moves along the optical axis to enable the zoom lens to zoom, and at least one of the second lens group and the fourth lens group moves along the optical axis to enable the zoom lens to focus. When at least one of the third lens group and the fifth lens group moves along the optical axis toward the image side, so that the zoom lens is zoomed from the wide-angle end to the telephoto end, at least one of the second lens group and the fourth lens group performs mobile focusing along the optical axis corresponding to the position of the zoom lens group, the imaging wavelength, and the imaging object distance, so that the zoom lens maintains clear imaging on the imaging surface during the zooming process. Through the reasonable arrangement of the six lens groups and the conditional restriction of the ratio of the focal length of the zoom lens at the wide-angle end and the focal length of each lens group, the zoom lens has the effects of small size, large magnification and large aperture. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0031] Figure 1 A schematic structural diagram of an embodiment of a zoom lens provided by the present invention;

[0032] Figure 2 for Figure 1 Schematic diagram of the MTF curve of a medium zoom lens at the wide-angle end;

[0033] Figure 3 for Figure 1 Schematic diagram of the MTF curve of a medium zoom lens at the telephoto end.

[0034] Description of Figure Numbers:

[0035]

[0036] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that if a directional indication is involved in the embodiment of the present invention, the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0039] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] With the development of society, people's awareness of safety precautions has been continuously improved, the security monitoring industry has also been rapidly developed, and the role of monitoring has become increasingly important. Zoom lenses were actually designed and used in the last century. With the development of lens design technology, the application occasions of zoom lenses have gradually increased. Nowadays, zoom lenses have been widely used in civilian products, security monitoring and other fields. However, since the imaging quality of zoom lenses is worse than that of ordinary fixed focal length lenses, the popularity of zoom lenses is not high. Moreover, most of the zoom lenses on the market now have a small target size, resulting in low resolution of the collected images, general shooting effects, and low value of the pictures. Moreover, most of the zoom lenses on the market now have a small aperture, resulting in less light transmission from the lens, and the images obtained in low-light scenes are darker, making it difficult to ensure image quality. As security moves towards high definition and miniaturization, lenses need to achieve higher performance and smaller size.

[0041] In view of this, the main purpose of the present invention is to provide a zoom lens and an imaging device, aiming to improve the technical problems of the existing medium-focus lens with a small aperture, a large zoom and a small size. Please refer to Figures 1 to 3 This is an embodiment of the zoom lens.

[0042] The direction of the optical axis of the zoom lens from the object side to the image side is from front to back. It can be understood that the object side faces the subject and the light transmission direction is from the object side to the image side.

[0043] The zoom lens includes a lens barrel body. The lens body includes a lens barrel, and a first lens group 1 with positive optical power, a second lens group 2 with negative optical power, a third lens group 3 with negative optical power, a fourth lens group 4 with negative optical power, a fifth lens group 5 with positive optical power, a sixth lens group 6 with positive optical power, and an image sensor chip 8, which are sequentially arranged in the lens barrel from front to back. The second lens group 2, the third lens group 3, the fourth lens group 4, and the fifth lens group 5 are respectively movably arranged along the front-back direction relative to the lens barrel. At least one of the third lens group 3 and the fifth lens group 5 moves along the optical axis to zoom the zoom lens, and at least one of the second lens group 2 and the fourth lens group 4 moves along the optical axis to focus the zoom lens;

[0044] Wherein, the zoom lens satisfies the following conditions: 0.29 < fw / f1 < 2.57, and -8.77 < fw / f2 < -0.97, and -2.89 < fw / f3 < -0.32, and -2.16 < fw / f4 < -0.24, and 0.16 < fw / f5 < 1.47, and 0.05 < fw / f6 < 0.45;

[0045] Wherein, fw is the focal length of the zoom lens at the wide-angle end, f1 is the focal length of the first lens group 1, f2 is the focal length of the second lens group 2, f3 is the focal length of the third lens group 3, f4 is the focal length of the fourth lens group 4, f5 is the focal length of the fifth lens group 5, and f6 is the focal length of the sixth lens group 6.

[0046] Specifically, in this embodiment, the ratios of the zoom lens at the wide-angle end and each lens group are specifically as follows: fw / f1 = 77 / 90, fw / f2 = -(225 / 77), fw / f3 = -(53 / 55), fw / f4 = -(39 / 50), fw / f5 = 37 / 75, fw / f6 = 13 / 87;

[0047] In the technical solution provided by the present invention, when at least one of the third lens group 3 and the fifth lens group 5 moves along the optical axis toward the image side direction, so that the zoom lens is zoomed from the wide-angle end to the telephoto end, at least one of the second lens group 2 and the fourth lens group 4 moves and focuses along the optical axis corresponding to the position of the zoom lens group, the imaging wavelength, and the imaging object distance, so that the zoom lens keeps the imaging surface clear during the zooming process. Through the reasonable arrangement of the five lens groups and the conditional restriction of the ratio of the focal length of the zoom lens at the wide-angle end and the focal length of each lens group, the zoom lens has the effects of small size, large magnification and large aperture, and the present invention distributes the long zoom stroke of the high-magnification lens into the short zoom strokes of multiple zoom groups: the lens adopts the structure of the third lens group 3 and the fifth lens group 5 for zooming, and the second lens group 2 and the fourth lens group 4 for focusing. The zoom strokes of each group are relatively short, with a certain overlap and no interference with each other, which effectively compresses the zoom stroke of the lens.

[0048] Specifically, the first lens group 1 includes a first lens 11 with positive optical power, a second lens 12 with negative optical power, a third lens 13 with positive optical power and a fourth lens 14 with positive optical power, which are arranged in sequence from front to back; the first lens group 1 and the first lens 11, the second lens 12, the third lens 13 and the fourth lens 14 meet the following conditions: 0.05<f1 / f11<0.43, and -1.08<f1 / f12<-1.08, and 0.14<f1 / f13<1.29, and 0.13<f1 / f14<1.19; wherein f1 is the focal length of the first lens group 1, f11 is the focal length of the first lens 11, f12 is the focal length of the second lens 12, f13 is the focal length of the third lens 13, and f14 is the focal length of the fourth lens 14.

[0049] More specifically, in this embodiment, the first lens 11 is a convex-concave lens, that is, the object-side surface of the first lens 11 is convex, and the image-side surface is concave, the second lens 12 is a biconvex lens, the third lens 13 is a convex-concave lens, that is, the object-side surface of the third lens 13 is convex, and the image-side surface is concave, the fourth lens 14 is a convex-concave lens, that is, the object-side surface of the fourth lens 14 is convex, and the image-side surface is concave, and the focal length ratio of the first lens group 1 to the focal length of each lens therein is specifically as follows: f1 / f11=12 / 83, f1 / f12=-(9 / 25), f1 / f13=3 / 7, f1 / f14=23 / 58, and the optical powers of the first lens 11 to the fourth lens 14 are: 363.7, -146.1, 122.4, 132.6, respectively.

[0050] Further, the first lens 11 and the second lens 12 constitute a first cemented lens with positive optical power, and satisfy the following condition: 0.07<f1 / f1112<0.65; wherein f1 is the focal length of the first lens group 1, and f1112 is the focal length of the first cemented lens. In an embodiment, the focal length ratio of the first lens group and the first cemented lens is specifically: f1 / f1112=13 / 60.

[0051] Specifically, the second lens group 2 includes a fifth lens 21 with negative optical power, a sixth lens 22 with negative optical power and a seventh lens 23 with negative optical power, which are arranged in sequence from front to back, and the fifth lens 21 is an aspherical lens; the second lens group 2 and the fifth lens 21, the sixth lens 22 and the seventh lens 23 meet the following conditions: 0.18<f2 / f21<1.61, and 0.04<f2 / f22<0.38, and 0.04<f2 / f23<0.4; wherein f2 is the focal length of the second lens group 2, f21 is the focal length of the fifth lens 21, f22 is the focal length of the sixth lens 22, and f23 is the focal length of the seventh lens 23.

[0052] More specifically, in this embodiment, the fifth lens 21 is a convex-concave lens, that is, the object-side surface of the fifth lens 21 is convex, and the image-side surface is concave, the sixth lens 22 is a biconcave lens, and the seventh lens 23 is a convex-concave lens, that is, the object-side surface of the seventh lens 23 is convex, and the image-side surface is concave; and the ratio of the focal length of the second lens group 2 to the focal length of each lens therein is specifically as follows: f2 / f21=22 / 41, f2 / f22=6 / 47, f2 / f23=7 / 53, and the optical powers of the fifth lens 21 to the seventh lens 23 are: -28.7, -120.6, and -116.7, respectively.

[0053] Further, the sixth lens 22 and the seventh lens 23 constitute a second cemented lens with negative optical power, and satisfy the following condition: 0.13<f2 / f2223<1.16, wherein f2 is the focal length of the second lens group 2, and f2223 is the focal length of the second cemented lens. In an embodiment, the focal length ratio of the second lens group and the second cemented lens is specifically: f2 / f2223=19 / 49.

[0054] Specifically, the third lens group 3 includes an eighth lens 31 with positive power, a ninth lens 32 with positive power, a tenth lens 33 with positive power, and an eleventh lens 34 with negative power, which are arranged in sequence from front to back, wherein the eighth lens 31 is an aspherical lens; the third lens group 3 and the eighth lens 31, the ninth lens 32, the tenth lens 33, and the eleventh lens 34 meet the following conditions: -2.63 <f3 / f31<-0.29, and -3.71<f3 / f32<-0.41, and -2.47<f3 / f33<-0.27, and 1.07<f3 / f34<9.66; wherein f3 is the focal length of the third lens group 3, f31 is the focal length of the eighth lens 31, f32 is the focal length of the ninth lens 32, f33 is the focal length of the tenth lens 33, and f34 is the focal length of the eleventh lens 34.

[0055] More specifically, in this embodiment, the eighth lens 31 is a convex-concave lens, that is, the object side surface of the eighth lens 31 is convex, and the image side surface is concave, the ninth lens 32 is a biconvex lens, the tenth lens 33 is a biconvex lens, and the eleventh lens is a biconcave lens, and the focal length ratio of the third lens group 3 to the focal length of each lens therein is as follows: f3 / f31=-(79 / 90), f3 / f32=-(21 / 17), f3 / f33=-(14 / 17), f3 / f34=248 / 77, and the optical powers of the eighth lens 31 to the eleventh lens 34 are: 53.2, 37.8, 56.7, -14.5, respectively.

[0056] Further, the tenth lens 33 and the eleventh lens 34 constitute a third cemented lens with negative optical power, and satisfy the following condition: 0.62<f3 / f3334<5.56, wherein f3 is the focal length of the third lens group 3, and f3334 is the focal length of the third cemented lens. In an embodiment, the focal length ratio of the third lens group and the third cemented lens is specifically: f3 / f3334=63 / 34.

[0057] Specifically, the fourth lens group 4 includes a twelfth lens 41 with positive power, a thirteenth lens 42 with negative power and a fourteenth lens 43 with positive power, which are arranged in sequence from front to back, and the fourteenth lens 43 is an aspherical lens; the fourth lens group 4 and the twelfth lens 41, the thirteenth lens 42 and the fourteenth lens 43 satisfy the following relationship: -6.29<f4 / f41<-0.7, and 0.75<f4 / f42<6.74, and -3.46<f4 / f43<-0.38; wherein f4 is the focal length of the fourth lens group 4, f41 is the focal length of the twelfth lens 41, f42 is the focal length of the thirteenth lens 42, and f43 is the focal length of the fourteenth lens 43.

[0058] More specifically, in this embodiment, the twelfth lens 41 is a biconvex lens, the thirteenth lens 42 is a biconcave lens, and the fourteenth lens 43 is a convex-concave lens, that is, the object side surface of the fourteenth lens 43 is a convex surface, and the image side surface is a concave surface, and the focal length of the fourth lens group 4 and the focal length of each lens therein are specifically as follows: f4 / f41=-(151 / 72), f4 / f42=119 / 53, f4 / f43=-(15 / 13), and the optical powers of the twelfth lens 41 to the fourteenth lens 43 are: 592.8, -25.7, 50, respectively.

[0059] Further, the twelfth lens 41 and the thirteenth lens constitute a fourth cemented lens with negative optical power, and satisfy the following condition: 0.74<f4 / f4142<6.68, wherein f4 is the focal length of the fourth lens group 4, and f4142 is the focal length of the fourth cemented lens. In the present embodiment, the focal length ratio of the fourth lens group and the fourth cemented lens is specifically: f4 / f4142=176 / 79.

[0060] Specifically, the fifth lens group 5 includes, arranged from front to back in sequence, a fifteenth lens 51 with negative power, a sixteenth lens 52 with positive power, a seventeenth lens 53 with positive power, an eighteenth lens 54 with negative power, a nineteenth lens 55 with positive power, and a twentieth lens 56 with negative power, wherein the twentieth lens 56 is an aspherical lens; the fifth lens group 5 and the fifteenth lens 51, the sixteenth lens 52, the seventeenth lens 53, the eighteenth lens 54, the nineteenth lens 55, and the twentieth lens 56 satisfy the following relationship: -3.49<f5 / f5 1<-0.39, and 0.17<f5 / f52<1.57, and 0<f5 / f53<0.03, and -1.12<f5 / f54<-0.12, and 0.04<f5 / f55<0.39, and 0.28<f5 / f56<2.53; wherein f5 is the focal length of the fifth lens group 5, f51 is the focal length of the fifteenth lens 51, f52 is the focal length of the sixteenth lens 52, f53 is the focal length of the seventeenth lens 53, f54 is the focal length of the eighteenth lens 54, f55 is the focal length of the nineteenth lens 55, and f56 is the focal length of the twentieth lens 56.

[0061] More specifically, in this embodiment, the fifteenth lens 51 is a biconcave lens, the sixteenth lens 52 is a biconvex lens, the seventeenth lens 53 is a biconvex lens, the eighteenth lens 54 is a biconcave lens, the nineteenth lens 55 is a biconvex lens, and the twentieth lens 56 is a biconvex lens, and the ratios of the focal length of the fifth lens group 5 to the focal lengths of the lenses therein are specifically as follows: f5 / f51=-(57 / 49), f5 / f52=12 / 23, f5 / f53=1 / 86, f5 / f54=-(37 / 99), f5 / f55=4 / 31, f5 / f56=38 / 45, and the optical powers of the fifteenth lens 51 to the twentieth lens 56 are: -19.6, 43.7, 1959.1, -61, 176.8, 27, respectively.

[0062] Further, the fifteenth lens 51 and the sixteenth lens 52 constitute a fifth cemented lens with negative optical power, and satisfy the following condition: -1.39<f5 / f501<-0.15, wherein f5 is the focal length of the fifth lens group 5, and f501 is the focal length of the fifth cemented lens; the seventeenth lens 53, the eighteenth lens 54, and the nineteenth lens 55 constitute the sixth cemented lens with positive optical power, and satisfy the following condition: 0.05<f5 / f502<0.41, wherein f5 is the focal length of the fifth lens group 5, and f502 is the focal length of the sixth cemented lens. In this embodiment, the specific ratio of the focal lengths of the fifth lens group and the fifth cemented lens is: f5 / f501=-(37 / 80), and the specific ratio of the focal lengths of the fifth lens group and the sixth cemented lens is: f5 / f502=7 / 51.

[0063] Specifically, the sixth lens group 6 includes a twenty-first lens 61 with positive refractive power, and the twenty-first lens 61 is an aspherical lens. In this embodiment, the twenty-first lens 61 is a meniscus lens, that is, the object side surface of the twenty-first lens 61 is a concave surface, the image side surface is a convex surface, and the refractive power of the twenty-first lens 61 is 301.2.

[0064] Specifically, the zoom lens further includes an aperture 7, which is located between the third lens group 3 and the fourth lens group 4; the aperture 7 is used to limit the light beam to further improve the imaging quality of the zoom lens, and the zoom lens satisfies the following conditions: 0.15<L / TTL<1.33; wherein L is the distance from the aperture 7 to the imaging surface of the zoom lens on the optical axis, and TTL is the total optical length of the zoom lens. More specifically, in this embodiment, L / TTL=43 / 97. Since the moving strokes of different groups overlap with each other, all areas of the lens optical path become the stroke range, and the aperture 7 cannot be fixed and installed. Therefore, in this embodiment, the aperture 7 is set in the moving group, and the aperture 7 moves together with the lens group during the zooming process. In order to drive the movable aperture 7, a telescopic circuit driving element is specially made. Due to the particularity of multi-group zoom, compared with the traditional structure, at the same aperture 7 size in the long focal length, the aperture 7 will move with the lens group, the optical path from the first lens group 1 to the position of the aperture 7 is reduced, and the diameter of the front lens group is greatly reduced. The goal of high-magnification zoom is achieved in a small volume through sophisticated optical path design and structural arrangement.

[0065] Specifically, the zoom lens further includes a filter, which is located between the sixth lens group 6 and the photosensitive chip 8. The filter is used to filter out light of unnecessary wavelengths and stray light, thereby improving imaging quality.

[0066] Furthermore, the zoom lens may further include a protective glass, which is disposed between the filter and the photosensitive chip 8 to prevent internal components (eg, chip) of the zoom lens from being damaged.

[0067] Based on the above, the fifth lens 21, the eighth lens 31, the fourteenth lens 43, the twentieth lens 56 and the twenty-first lens 61 are all aspherical glass lenses. It can be understood that the characteristics of aspherical lenses are: the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike spherical lenses with a constant curvature from the center of the lens to the periphery of the lens, aspherical lenses have better curvature radius characteristics, and have the advantages of improving distortion aberration and improving astigmatism aberration. After using aspherical lenses, the aberrations occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens.

[0068] Specifically, in this embodiment, the parameters of the zoom lens are shown in the following table.

[0069] Table 1 Parameters of each lens of the zoom lens

[0070]

[0071] Further, in this embodiment, the aspheric surface shape of the aspheric lens satisfies the following conditions:

[0072]

[0073] In this formula, parameter c is the curvature corresponding to the radius, r is the radial coordinate, and its unit is the same as the lens length unit, k is the coefficient of the conic quadratic curve, when the k coefficient is less than -1, the surface curve is a hyperbola, when the k coefficient is equal to -1, it is a parabola, when the k coefficient is between -1 and 0, it is an ellipse, when it is equal to 0, it is a circle, and when it is greater than 0, it is an oblate circle, α1 to α8 represent the coefficients corresponding to each radial coordinate, respectively. The above parameters can accurately set the shape and size of the front and rear aspheric surfaces of the lens. While ensuring that the lens has good picture requirements, the product weight is light, the driving burden is reduced, and it has a great contribution to reducing the volume of the driving components.

[0074] Based on the above, in this embodiment, the even-order coefficients of each aspherical surface are shown in the following table.

[0075] Table 3 Even-order coefficients of the aspherical lens of the zoom lens

[0076]

[0077] The wide-angle focal length of the zoom lens described in the present invention is EFL_W = 45mm, and the telephoto focal length is EFL_T = 500mm; the wide-angle aperture number Fno_W = 1.4, and the telephoto aperture number Fno_T = 7.85; the wide-angle horizontal field angle FOVH_W = 10°, and the wide-angle half field angle FOVH_W = 1°; the system optical distortion ∈ (-1.3%, -2.9%); the total optical length of the optical system (i.e., the distance from the central vertex of the front surface of the first lens to the image plane) TTL = 185mm.

[0078] The zoom lens adopts a five-group structure of "positive, negative, negative, positive, positive", and the system contains 5 glass aspherical surfaces. While achieving large aperture, small distortion, large magnification ratio and small size, it fully reduces the manufacturing cost.

[0079] Although the zoom lens uses an aspherical lens, the focal length is conditionally limited so that temperature changes have little effect on the performance of the lens, the back focus changes very little, and the performance is stable when the indoor environment changes, without the need for refocusing.

[0080] As the third lens group and the fifth lens group move forward and backward, the focal length changes. The second lens group and the fourth lens group are used for focusing function. (Take 1 / 1.8” 16:9 CCD as an example) The focal length can change from <45mm at the wide-angle end to >500mm at the telephoto end. The shooting angle at the wide-angle end (WIDE) is horizontally >10°. The optical distortion at the wide-angle end (WIDE) and the telephoto end is within -1%, with small distortion and large magnification effect.

[0081] The zoom lens uses an adjustable diaphragm, and the FNO. reaches 1.4 at the wide-angle end and 7.85 at the telephoto end, with extremely high light sensitivity, and can still capture clearer images in darker environments;

[0082] The zoom lens has the first lens group as the highest point, the distance between the first lens group and the image plane is fixed, and the height thereof is less than 185 mm (taking a 1 / 1.8” CCD as an example);

[0083] The zoom lens can achieve a resolution higher than 4K (8 million pixels). Taking a 1 / 1.8" sensor as an example, the zoom lens can achieve a center resolution higher than 300lp / mm and a peripheral 0.7H (70% diagonal position) resolution higher than 1400TVline.

[0084] The present invention takes into account both chromatic aberration and focal power distribution. Based on the theory of optical chromatic aberration, ultra-low dispersion glass is used for some convex lens sheets, and ultra-high refractive index materials are used to ensure focal power for the remaining convex lens materials. Medium and high refractive index materials with excellent dispersion characteristics are unconventionally selected for the negative lens to optimize the system chromatic aberration as much as possible. After repeated material combination and replacement, infrared confocality of the entire focal length is truly achieved.

[0085] In order to improve the imaging quality of the lens at various magnifications, the present invention combines high-refractive index glass with ultra-low dispersion glass materials to reduce various optical aberrations while effectively suppressing the chromatic aberration of the system. Different from the traditional single-concave molded aspheric surface process, the zoom mobile group adopts the aspheric surface design of multiple double-concave ultra-low dispersion glass materials for the first time. The lens compresses the chromatic aberration of the peripheral field of view by utilizing the abnormal dispersion characteristics of the material. Multiple concave surfaces correct the field curvature of different magnifications in turn, greatly improving the problem that the wide-angle end and the telephoto end cannot be achieved at the same time. General zoom lenses are mostly focused in groups with positive optical power, which are characterized by simple focusing curves and short focusing strokes. Thanks to the sufficient space margin brought by multi-group linkage zoom, the present invention uses a negative group focusing structure and uses a long focusing area to compensate for the image quality loss in close-range shooting, achieving better results. From the wide-angle end to the end, whether it is observation of a large field of view or capture of close-range details, the color restoration and detail reproduction capabilities of 4K level are achieved.

[0086] The present invention further provides an imaging device, wherein the mobile device comprises the zoom lens described in the above technical solution, and the imaging device may be a monitoring lens, which is not limited herein.

[0087] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A zoom lens, characterized in that: It includes a lens body. The direction from the object side to the image side along the optical axis of the lens body is from front to back. The lens body is composed of a lens barrel, a first lens group with positive optical power, a second lens group, a third lens group, a fourth lens group with negative optical power, a fifth lens group, a sixth lens group with positive optical power, and an image sensor chip, which are sequentially arranged in the lens barrel from front to back. The second lens group, the third lens group, the fourth lens group, and the fifth lens group are respectively movably arranged along the front-back direction relative to the lens barrel. At least one of the third lens group and the fifth lens group moves along the optical axis to zoom the zoom lens, and at least one of the second lens group and the fourth lens group moves along the optical axis to focus the zoom lens. Among them, the zoom lens satisfies the following conditions: 0.29 < fw / f1 < 2.57, and -2.16 < fw / f4 < -0.24, and 0.05 < fw / f6 < 0.

45. Among them, fw is the focal length of the zoom lens at the wide-angle end, f1 is the focal length of the first lens group, f4 is the focal length of the fourth lens group, and f6 is the focal length of the sixth lens group. The second lens group is composed of a fifth lens with negative optical power, a sixth lens with negative optical power, and a seventh lens, which are sequentially arranged from front to back. The fifth lens is an aspherical lens. The R value of the object side surface of the fifth lens is 213.541, the thickness is 3.814, the semi-aperture is 13.632, the refractive index is 1.772502, the R value of the image side surface is 20.

029. The distance between the fifth lens and the sixth lens is 4.802, the semi-aperture is 11.

119. The R value of the object side surface of the sixth lens is -45.066, the thickness is 0.612, the semi-aperture is 11.105, the refractive index is 1.729164, the R value of the image side surface is 25.

525. The distance between the sixth lens and the seventh lens is 0, the semi-aperture is 11.

114. The R value of the object side surface of the seventh lens is 25.525, the thickness is 2.15, the semi-aperture is 11.114, the R value of the image side surface is 56.

193. The third lens group is composed of an eighth lens with positive focal power, a ninth lens with positive focal power, a tenth lens with positive focal power and an eleventh lens with negative focal power, which are arranged in sequence from front to back, wherein the eighth lens is an aspherical lens, the object side surface R value of the eighth lens is 22.803, the thickness is 4.321, the half-diameter is 11.578, the refractive index is 1.497103, the image side surface R value is 152.927, the spacing between the eighth lens and the ninth lens is 0.08, the half-diameter is 11.375, the object side surface R value of the ninth lens is 17.765, the thickness is 5.194, the half-diameter is 11.014, the refractive index is 1 .437001, the image side R value is -220.267, the spacing between the ninth lens and the tenth lens is 0.08, the object side R value of the tenth lens is 22.796, the thickness is 4.262, the half-aperture is 9.518, the refractive index is 1.550323, the image side R value is -29.296, the spacing between the tenth lens and the eleventh lens is 0, the half-aperture is 9.188, the refractive index is 1.754998, the object side R value of the eleventh lens is -29.296, the thickness is 0.5, the half-aperture is 9.188, the refractive index is 1.754998, the image side R value is 12.272, and the half-aperture is 7.611; The fifth lens group is composed of a fifteenth lens with negative power, a sixteenth lens with positive power, a seventeenth lens with positive power, an eighteenth lens with negative power, a nineteenth lens with positive power, and a twentieth lens, which are arranged in sequence from front to back, wherein the twentieth lens is an aspherical lens, the object side surface R value of the fifteenth lens is -18.025, the thickness is 0.5, the semi-aperture is 8.486, the refractive index is 1.883004, the image side surface R value is 20.451, and the fifteenth lens and the image side surface R value are arranged in sequence from front to back. The spacing of the sixteenth lens is 0, the half-aperture is 9.97, and the refractive index is 1.846666. The object side R value of the sixteenth lens is 20.451, the thickness is 9.015, the half-aperture is 9.97, the refractive index is 1.846666, and the image side R value is -35.

172. The spacing between the sixteenth lens and the seventeenth lens is 0.08, the half-aperture is 11.4, the object side R value of the seventeenth lens is 66.975, the thickness is 4.173, the half-aperture is 12.377, and the refractive index is 1 .496998, the image side R value is -38.161, the distance between the seventeenth lens and the eighteenth lens is 0, the half-aperture is 12.499, and the refractive index is 1.761823, the object side R value of the eighteenth lens is -38.161, the thickness is 0.5, the half-aperture is 12.499, the refractive index is 1.761823, the image side R value is 29.046, the distance between the eighteenth lens and the nineteenth lens is 0, the half-aperture is 13.475, and the refractive index is 1.496998, the The object side R value of the nineteenth lens is 29.046, the thickness is 4.829, the half aperture is 13.475, the refractive index is 1.496998, and the image side R value is -34.

737. The distance between the nineteenth lens and the twentieth lens is 0.08, and the half aperture is 13.

697. The object side R value of the twentieth lens is 26.013, the thickness is 10.837, the half aperture is 15.551, the refractive index is 1.497103, the image side R value is 23.973, and the half aperture is 15.

603.

2. The zoom lens according to claim 1, wherein: The first lens group is composed of a first lens, a second lens, a third lens with positive refractive power and a fourth lens with positive refractive power, which are arranged in sequence from front to back; The first lens group, the third lens and the fourth lens satisfy the following conditions: 0.14<f1 / f13<1.29, and 0.13<f1 / f14<1.19; Among them, f1 is the focal length of the first lens group, f13 is the focal length of the third lens, and f14 is the focal length of the fourth lens.

3. The zoom lens according to claim 1, wherein: The fourth lens group is composed of a twelfth lens with positive power, a thirteenth lens with negative power and a fourteenth lens with positive power, which are arranged in sequence from front to back, and the fourteenth lens is an aspherical lens; The fourth lens group and the twelfth lens, the thirteenth lens and the fourteenth lens satisfy the following relationship: -6.29<f4 / f41<-0.7, and 0.75<f4 / f42<6.74, and -3.46<f4 / f43<-0.38; Among them, f4 is the focal length of the fourth lens group, f41 is the focal length of the twelfth lens, f42 is the focal length of the thirteenth lens, and f43 is the focal length of the fourteenth lens.

4. The zoom lens according to claim 1, wherein: The fifteenth lens and the sixteenth lens constitute a fifth cemented lens; the seventeenth lens, the eighteenth lens, and the nineteenth lens constitute a sixth cemented lens.

5. The zoom lens according to claim 1, wherein: The sixth lens group consists of a twenty-first lens with positive refractive power, and the twenty-first lens is an aspherical lens.

6. The zoom lens according to claim 1, wherein: The zoom lens further comprises an aperture stop, wherein the aperture stop is located between the third lens group and the fourth lens group; The zoom lens satisfies the following conditions: 0.15<L / TTL<1.33; Wherein, L is the distance from the aperture to the imaging surface of the zoom lens on the optical axis, and TTL is the total optical length of the zoom lens.

7. An imaging device, characterized in that: The imaging device comprises the zoom lens as claimed in any one of claims 1 to 6.

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