Focusing lens group

Abstract

The invention provides a focusing lens group which comprises three lens barrels, a second lens barrel is movably arranged between a first lens barrel and a third lens barrel, the first lens barrel comprises a first lens, the second lens barrel comprises a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, and the third lens barrel comprises a fifth lens and a sixth lens. The focal power of the lens groups in the three lens cones is distributed according to 'positive-positive-negative', the focal power of the seven lenses is distributed according to 'positive-positive-negative-positive-positive-negative-negative', the image side surfaces of the second to fourth lenses and the sixth lens are sequentially provided with spacing elements, and the focusing lens group also meets the following conditions: 4.95 lt; (F1 + F2 + F3) / [delta] flt; 5.85); 2.35 lt, 2.35 lt; and (DT2s + DT2m) / Td2 is less than or equal to 3.30. Through the limitation of the conditional expression, the focusing lens group can give consideration to the focusing range and the imaging quality, and the miniaturization of the focusing lens group can be realized on the premise of ensuring the imaging quality of the focusing lens group.

Description

Technical Field

[0001] This application relates to the technical field of optical devices, and particularly to a focusing lens group. Background Art

[0002] In recent years, with the rapid development of smart phones, mobile phone photography has become popular among the general public. Users' demands for mobile phone photography are no longer satisfied with simple recording, and they have begun to pursue higher imaging effects, including higher picture clarity, richer detail performance, and faster and more accurate focusing capabilities. This has made the importance of optical zoom technology increasingly prominent. Since an optical zoom lens system requires multiple lens groups to be configured, the overall length of such a system is relatively long, so it is mainly applied to periscope telephoto camera modules. The number of lens groups in the current optical zoom system has developed from a simple two-lens group to a three-lens group, and the corresponding zoom method has also evolved from the external focusing of the two-lens group to the internal focusing of the three-lens group, as well as the continuous zoom technology in which two lens groups in the three-lens group cooperate for focusing.

[0003] Compared with the external focusing and continuous zoom lens systems, the overall length of the internal focusing lens system does not change, avoiding the problem of dust and impurities being sucked in during the telescoping process of the external focusing and continuous zoom lens systems. At the same time, it has higher imaging quality than the traditional two-lens group external focusing system, shorter space occupancy than the three-lens group continuous zoom system, a simpler and more stable module zoom structure, and a faster focusing speed. This makes the internal focusing lens system more favored by high-end flagship mobile phones. With the market's pursuit of higher pixel and larger imaging size for mobile phone lenses, while also taking into account the smallest possible module height, higher requirements are put forward for the design of the focusing lens group and the processability and manufacturability of the overall internal focusing lens system. Summary of the Invention

[0004] One advantage of this application is to provide a focusing lens group that can solve the problem of difficult control of image clarity and distortion degree when the lens changes too violently during the focusing process.

[0005] On the one hand, this application provides a focusing lens group, including a first lens barrel, a second lens barrel, and a third lens barrel arranged in sequence along the same optical axis. The second lens barrel is movably arranged between the first lens barrel and the third lens barrel;

[0006] A first lens group, installed in the first lens barrel, and the first lens group includes a first lens with a positive optical power;

[0007] A second lens group, installed in the second lens barrel, and the second lens group has a positive optical power. The second lens group includes a second lens with a positive optical power, a third lens with a negative optical power, a fourth lens with a positive optical power, and a fifth lens with a positive optical power;

[0008] The third lens group is mounted on the third lens barrel. The third lens group has a negative optical power. The third lens group includes a sixth lens with a negative optical power and a seventh lens with a negative optical power;

[0009] At least one spacer element is included between any two adjacent lenses in the second lens group, and the object side surface of the spacer element is in contact with the adjacent lens;

[0010] The focusing lens group satisfies: 4.95 < (F1 + F2 + F3) / |Δf| < 5.85; and 2.35 ≤ (DT2s + DT2m) / Td2 ≤ 3.30;

[0011] Wherein, F1 is the effective focal length of the first lens group, F2 is the effective focal length of the second lens group, F3 is the effective focal length of the third lens group; △f is the change difference of the effective focal length of the focusing lens group when the second lens barrel moves from the position closest to the first lens barrel to the position closest to the third lens barrel; DT2s is the clear aperture diameter on the object side of the second lens barrel, DT2m is the clear aperture diameter on the image side of the second lens barrel; Td2 is the distance on the optical axis from the object side surface of the second lens in the second lens group to the image side surface of the fifth lens.

[0012] In some embodiments of the present application, the second lens barrel satisfies: 0.80 ≤ DT2s / DT2m < 1.40;

[0013] Wherein, DT2s is the clear aperture diameter on the object side of the second lens barrel, DT2m is the clear aperture diameter on the image side of the second lens barrel.

[0014] In some embodiments of the present application, the focusing lens group satisfies: 2.10 < F2 / L2 ≤ 2.95; and 2.10 ≤ F2 / Td2 ≤ 2.85;

[0015] Wherein, F2 is the effective focal length of the second lens group, L2 is the maximum height of the second lens barrel, Td2 is the distance on the optical axis from the object side surface of the second lens in the second lens group to the image side surface of the fifth lens.

[0016] In some embodiments of the present application, a second spacer element in contact with the image side surface of the second lens is provided on the image side of the second lens. The focusing lens group further satisfies: 1.65 ≤ f2 / d2s < 5.20;

[0017] Wherein, f2 is the effective focal length of the second lens, d2s is the inner diameter of the object side surface of the second spacer element.

[0018] In some embodiments of the present application, a third spacer element in contact with the image side surface of the third lens is provided on the image side of the third lens, and the focusing lens group further satisfies: 0.50 < (f3 + f4) / d3s < 2.15;

[0019] Wherein, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, and d3s is the inner diameter of the object side surface of the third spacer element.

[0020] In some embodiments of the present application, a fourth spacer element in contact with the image side surface of the fourth lens is provided on the image side of the fourth lens, and the focusing lens group further satisfies: 2.15 < f4 / d4m < 3.45;

[0021] Wherein, f4 is the effective focal length of the fourth lens, and d4m is the inner diameter of the image side surface of the fourth spacer element.

[0022] In some embodiments of the present application, the focusing lens group further satisfies: 4.95 ≤ DT2m / (CT5 × N5) < 11.95;

[0023] Wherein, DT2m is the clear aperture diameter on the image side of the second lens barrel, CT5 is the central thickness of the fifth lens, and N5 is the refractive index of the fifth lens.

[0024] In some embodiments of the present application, the focusing lens group further satisfies: 3.35 < DT2s / (CT2 × N2) < 6.45;

[0025] Wherein, DT2s is the clear aperture diameter on the object side of the second lens barrel, CT2 is the central thickness of the second lens, and N2 is the refractive index of the second lens.

[0026] In some embodiments of the present application, the focusing lens group satisfies: -3.50 < F3 / L3 ≤ -2.55; and 0.80 ≤ Td3 / L3 < 0.95;

[0027] Wherein, L3 is the maximum height of the third lens barrel along the optical axis direction, F3 is the effective focal length of the third lens group, and Td3 is the distance on the optical axis from the object side surface of the sixth lens to the image side surface of the seventh lens in the third lens group.

[0028] In some embodiments of the present application, the focusing lens group further satisfies: 3.65 < |F3| / (L3 - T67) ≤ 5.10;

[0029] Wherein, F3 is the effective focal length of the third lens group, L3 is the maximum height of the third lens barrel along the optical axis direction, and T67 is the air gap between the sixth lens and the seventh lens on the optical axis.

[0030] In some embodiments of the present application, the focusing lens group further satisfies: 0.40 < ET6 / (CT6 + T67) ≤ 0.95;

[0031] Wherein, ET6 is the maximum thickness of the non-transmissive region of the sixth lens, CT6 is the central thickness of the sixth lens, and T67 is the air gap between the sixth lens and the seventh lens on the optical axis.

[0032] In some embodiments of the present application, the focusing lens group further satisfies: 0.35 < ET7 / (T67 + CT7) < 1.10;

[0033] Wherein, ET7 is the maximum thickness of the non-transmissive region of the seventh lens, CT7 is the central thickness of the seventh lens, and T67 is the air gap between the sixth lens and the seventh lens on the optical axis.

[0034] In some embodiments of the present application, the focusing lens group satisfies: 1.45 < F1 / F2 < 2.45; and -3.60 < F1 / F3 ≤ -2.10;

[0035] Wherein, F1 is the effective focal length of the first lens group, F2 is the effective focal length of the second lens group, and F3 is the effective focal length of the third lens group.

[0036] In some embodiments of the present application, the focusing lens group further satisfies: 1.70 ≤ (T12 + T56) / ΔEP0 < 2.20;

[0037] Wherein, T12 is the air gap between the first lens and the second lens on the optical axis, T56 is the air gap between the fifth lens and the sixth lens on the optical axis, and ΔEP0 is the maximum distance that the second lens barrel can move along the optical axis.

[0038] In some embodiments of the present application, the focusing lens group further satisfies: 4.40 < (L1 + L2 + L3) / ΔEP0 < 5.55;

[0039] Wherein, L1 is the maximum height of the first lens barrel along the optical axis, L2 is the maximum height of the second lens barrel along the optical axis, L3 is the maximum height of the third lens barrel along the optical axis, and ΔEP0 is the maximum distance that the second lens barrel can move along the optical axis.

[0040] In summary, the focusing lens group of the present application adopts a three-barrel combination structure, and the first to third lens groups are sequentially built in the first to third lens barrels, wherein the first lens group includes the first lens, the second lens group includes the second to fifth lenses, and the third lens group includes the sixth and seventh lenses. By distributing the optical focal lengths of the three lens groups in sequence according to "positive-positive-negative" and distributing the optical focal lengths of the first to seventh lenses in sequence according to "positive-positive-negative-positive-positive-negative-negative" and further movably arranging the second lens barrel between the first lens barrel and the third lens barrel along the optical axis, the focusing lens group can take into account the imaging performance of different focal lengths such as telephoto, near focus and macro; by controlling the ratio between the sum of the focal lengths of the three lens groups and the maximum value of the effective focal length change of the focusing lens group, the focusing lens group can take into account the focusing range and imaging quality. On the one hand, constraining the lower limit of the ratio enables the focusing range of the focusing lens group to cover the requirements for different focal lengths in actual use. On the other hand, when the effective focal length of the focusing lens group changes too drastically, the clarity and distortion of the image are difficult to control during the focusing process. By constraining the upper limit of the ratio, the influence of too fast change of the effective focal length of the focusing lens group during the focusing process on the imaging quality can be reduced. Furthermore, the ratio of the sum of the clear diameters of the object side and the image side of the second lens barrel in the second lens group to the distance on the optical axis from the object side of the second lens to the image side of the fifth lens is controlled to be within a reasonable range. On the one hand, an appropriate clear diameter can ensure the amount of light entering the optical system in the focusing lens group and ensure the brightness, contrast and high performance of the imaging. On the other hand, an appropriate distance on the optical axis from the object side of the second lens to the image side of the fifth lens will make the overall structure of the optical system compact, which is conducive to the miniaturization of the focusing lens group. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the structure of a focusing lens assembly provided in this application;

[0042] Figure 2 for Figure 1 Dimensional schematic diagram of the focusing lens assembly shown;

[0043] Figure 3A A schematic diagram of the structure of a focusing lens group under working condition 1-1 in the first embodiment provided in the present application;

[0044] Figure 3B A schematic diagram of the structure of the focusing lens group under working condition 1-2 in the first embodiment provided in the present application;

[0045] Figure 3C This is a schematic diagram of the structure of the focusing lens group under working conditions 1-3 in the first embodiment provided in the present application;

[0046] Figure 4AThe axial chromatic aberration curve of the focusing lens group under three working conditions shown in Embodiment 1 when the object distance is infinity;

[0047] Figure 4B The astigmatism curve of the focusing lens group under three working conditions shown in Embodiment 1 when the object distance is infinity;

[0048] Figure 4C The distortion curve of the focusing lens group under three working conditions shown in Embodiment 1 when the object distance is infinity;

[0049] Figure 5A The axial chromatic aberration curve of the focusing lens group under three working conditions shown in Embodiment 1 when the object distance is 57.8556mm;

[0050] Figure 5B The astigmatism curve of the focusing lens group under three working conditions shown in Embodiment 1 when the object distance is 57.8556mm;

[0051] Figure 5C The distortion curve of the focusing lens group under three working conditions shown in Embodiment 1 when the object distance is 57.8556mm;

[0052] Figure 6A The structural schematic diagram of the focusing lens group under working condition 2-1 in Embodiment 2 provided by the present application;

[0053] Figure 6B The structural schematic diagram of the focusing lens group under working condition 2-2 in Embodiment 2 provided by the present application;

[0054] Figure 6C The structural schematic diagram of the focusing lens group under working condition 2-3 in Embodiment 2 provided by the present application;

[0055] Figure 7A The axial chromatic aberration curve of the focusing lens group under three working conditions shown in Embodiment 2 when the object distance is infinity;

[0056] Figure 7B The astigmatism curve of the focusing lens group under three working conditions shown in Embodiment 2 when the object distance is infinity;

[0057] Figure 7C The distortion curve of the focusing lens group under three working conditions shown in Embodiment 2 when the object distance is infinity;

[0058] Figure 8A The axial chromatic aberration curve of the focusing lens group under three working conditions shown in Embodiment 2 when the object distance is 52.6455mm;

[0059] Figure 8B The astigmatism curve of the focusing lens group under three working conditions shown in Embodiment 2 when the object distance is 52.6455mm;

[0060] Figure 8C It is the distortion curve diagram of the focusing lens group at an object distance of 52.6455 mm under the three working conditions shown in Embodiment 2;

[0061] Figure 9A It is the structural schematic diagram of the focusing lens group under Working Condition 3-1 in Embodiment 3 provided by the present application;

[0062] Figure 9B It is the structural schematic diagram of the focusing lens group under Working Condition 3-2 in Embodiment 3 provided by the present application;

[0063] Figure 9C It is the structural schematic diagram of the focusing lens group under Working Condition 3-3 in Embodiment 3 provided by the present application;

[0064] Figure 10A It is the axial chromatic aberration curve diagram of the focusing lens group at an infinite object distance under the three working conditions shown in Embodiment 3;

[0065] Figure 10B It is the astigmatism curve diagram of the focusing lens group at an infinite object distance under the three working conditions shown in Embodiment 3;

[0066] Figure 10C It is the distortion curve diagram of the focusing lens group at an infinite object distance under the three working conditions shown in Embodiment 3;

[0067] Figure 11A It is the axial chromatic aberration curve diagram of the focusing lens group at an object distance of 66.6675 mm under the three working conditions shown in Embodiment 3;

[0068] Figure 11B It is the astigmatism curve diagram of the focusing lens group at an object distance of 66.6675 mm under the three working conditions shown in Embodiment 3;

[0069] Figure 11C It is the distortion curve diagram of the focusing lens group at an object distance of 66.6675 mm under the three working conditions shown in Embodiment 3;

[0070] Figure 12 It is the MTF curve schematic diagram when the focusing lens group satisfies (F1 + F2 + F3) / |Δf| = 5.58;

[0071] Figure 13 It is the MTF curve schematic diagram when the focusing lens group satisfies (F1 + F2 + F3) / |Δf| = 4.35;

[0072] Figure 14 It is the MTF curve schematic diagram when the focusing lens group satisfies (F1 + F2 + F3) / |Δf| = 8.22.

[0073] Reference Signs:

[0074] E1, the first lens; E2, the second lens; E3, the third lens; E4, the fourth lens; E5, the fifth lens; E6, the sixth lens; E7, the seventh lens; P01, the first lens barrel; P02, the second lens barrel; P03, the third lens barrel; P2, the second spacer element; P3, the third spacer element; P4, the fourth spacer element; P6, the sixth spacer element; E8, the prism; E9, the filter. Detailed Embodiments

[0075] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0076] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens E1 discussed below may also be referred to as the second lens E2 or the third lens E3.

[0077] In the drawings, for the sake of clarity, the thickness, dimensions, and shapes of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are for illustrative purposes only and are not drawn to an exact scale.

[0078] In this document, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The judgment of the surface shape in the paraxial region can be made according to the general methods in the art. For example, the concavity and convexity can be judged by the positive or negative value of the R value (R refers to the radius of curvature in the paraxial region). In this document, the surface of each lens closest to the object being photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens. For the object side surface, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave; for the image side surface, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex.

[0079] It should also be understood that the terms "comprise", "comprises", "include", "includes", "have", "has", "contain" and / or "contains", when used in this specification, denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than an individual element in the list. In addition, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0080] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0081] It should be noted that, without conflict, the embodiments and features in the embodiments of the present application may be combined with each other. The following embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but should not be construed as a limitation on the patent scope of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0082] It is worth noting that in the present application, the non-transmissive area of the lens is located at the edge of the lens, and this area is mainly used to contact the lens barrel or the spacer element to support the lens. The edge thickness of the lens is the thickness of this non-transmissive area along the optical axis direction.

[0083] According to one aspect of the present application, as Figure 1 and Figure 2 shown, Figure 1 is a schematic structural diagram of a focusing lens group provided by the present application, Figure 2 is Figure 1 shown in the size schematic diagram of the focusing lens group. An embodiment of the present application provides a focusing lens group, which may include a first lens barrel, a second lens barrel and a third lens barrel arranged in sequence along the same optical axis, and the second lens barrel is movably arranged between the first lens barrel and the third lens barrel;

[0084] A first lens group, mounted on the first lens barrel P01, and the first lens group includes a first lens E1 having a positive optical power;

[0085] The second lens group is mounted on the second lens barrel P02. The second lens group has a positive optical power. The second lens group includes a second lens E2 with a positive optical power, a third lens E3 with a negative optical power, a fourth lens E4 with a positive optical power, and a fifth lens E5 with a positive optical power;

[0086] The third lens group is mounted on the third lens barrel P03. The third lens group has a negative optical power. The third lens group includes a sixth lens E6 with a negative optical power and a seventh lens E7 with a negative optical power;

[0087] At least one spacer element is included between any two adjacent lenses in the second lens group. The object side surface of the spacer element is in contact with the adjacent lens;

[0088] The focusing lens group satisfies: 4.95 < (F1 + F2 + F3) / |Δf| < 5.85; and 2.35 ≤ (DT2s + DT2m) / Td2 ≤ 3.30;

[0089] Wherein, F1 is the effective focal length of the first lens group, F2 is the effective focal length of the second lens group, and F3 is the effective focal length of the third lens group; △f is the difference in the effective focal length of the focusing lens group when the second lens barrel P02 moves from the position closest to the first lens barrel P01 to the position closest to the third lens barrel P03; DT2s is the clear aperture diameter on the object side of the second lens barrel P02, and DT2m is the clear aperture diameter on the image side of the second lens barrel P02; Td2 is the distance on the optical axis from the object side surface of the second lens E2 to the image side surface of the fifth lens E5 in the second lens group.

[0090] It is worth noting that the focusing lens group of the present application adopts a three-barrel combination structure, and the first to third lens groups are sequentially built in the first to third lens barrels, wherein the first lens group includes the first lens E1, the second lens group includes the second lens E2 to the fifth lens E5, and the third lens group includes the sixth lens E6 and the seventh lens E7. By distributing the optical power of the three lens groups in sequence according to "positive-positive-negative" and distributing the optical power of the first to the seventh lens E7 in sequence according to "positive-positive-negative-positive-positive-negative-negative", and further movably arranging the second lens barrel between the first lens barrel and the third lens barrel along the optical axis direction, the focusing lens group can take into account the imaging performance of different focal lengths such as telephoto, near focus and macro; by controlling the ratio between the sum of the focal lengths of the three lens groups and the maximum value of the effective focal length change of the focusing lens group, the focusing lens group can take into account the focusing range and imaging quality. On the one hand, constraining the ratio The lower limit enables the focusing range of the focusing lens group to cover the requirements for different focal lengths in actual use. On the other hand, when the effective focal length of the focusing lens group changes too drastically, the clarity and distortion of the image are difficult to control during the focusing process. By constraining the upper limit of the ratio, the influence of the rapid change of the effective focal length of the focusing lens group during the focusing process on the imaging quality can be reduced. Furthermore, the ratio of the sum of the clear diameters on the object side and the image side of the second lens barrel P02 in the second lens group to the distance on the optical axis from the object side of the second lens E2 to the image side of the fifth lens E5 is controlled to be within a reasonable range. On the one hand, an appropriate clear diameter can ensure the amount of light entering the optical system in the focusing lens group, and ensure the brightness, contrast and high performance of the imaging. On the other hand, an appropriate distance on the optical axis from the object side of the second lens E2 to the image side of the fifth lens E5 will make the overall structure of the optical system compact, which is conducive to the miniaturization of the focusing lens group.

[0091] In addition, the object-side surface of the first lens E1 is convex; the object-side surface of the second lens E2 is convex; the image-side surface of the third lens E3 is concave; the object-side surface of the fourth lens E4 is convex, and the image-side surface is concave; the image-side surface of the fifth lens E5 is convex; the object-side surface of the sixth lens E6 is concave, and the image-side surface is convex; the object-side surface of the seventh lens E7 is convex, and the image-side surface is concave.

[0092] For example, the present application provides MTF curves under three schemes. Scheme 1 corresponds to Figure 12 , Scheme 2 corresponds to Figure 13 , Scheme 3 corresponds to Figure 14 , Figure 12 The MTF curve and modulation transfer function curve of the focusing lens group when (F1+F2+F3) / |Δf|=5.58 are shown; Figure 13 The MTF curve and modulation transfer function curve of the focusing lens group when (F1+F2+F3) / |Δf|=4.35 are shown;Figure 14 The MTF curve and modulation transfer function curve of the focusing lens group when (F1 + F2 + F3) / |Δf| = 8.22 are respectively shown.

[0093] It can be easily seen from the figure that: as Figure 12 shown, in the first scheme, when the relationship (F1 + F2 + F3) / |Δf| is in the range greater than 4.95 and less than 6.25, the MTF curve of the focusing lens group is stable, making the focusing lens group have good MTF performance; as Figure 13 shown, in the second scheme, when the relationship (F1 + F2 + F3) / |Δf| is in the range less than 4.95, with the increase of the image height, especially when the image height is greater than 5 mm, the MTF curve of the focusing lens group shows an obvious drop phenomenon, and the optical performance deteriorates and does not meet the imaging requirements; as Figure 14 shown, in the third scheme, when the relationship (F1 + F2 + F3) / |Δf| is greater than 5.80, with the increase of the image height, the MTF of the focusing lens group shows obvious fluctuations, and an obvious drop phenomenon occurs when the image height is greater than 5 mm, and the optical performance deteriorates and does not meet the imaging requirements.

[0094] Preferably, the focusing lens group satisfies: 4.97 ≤ (F1 + F2 + F3) / |Δf| ≤ 5.84, and 2.35 ≤ (DT2s + DT2m) / Td2 ≤ 3.26.

[0095] According to some embodiments of the present application, the second lens barrel P02 further satisfies: 0.80 ≤ DT2s / DT2m < 1.40;

[0096] wherein, DT2s is the clear aperture diameter on the object side of the second lens barrel P02, and DT2m is the clear aperture diameter on the image side of the second lens barrel P02.

[0097] In this way, by reasonably restricting the ratio range of the clear aperture diameter of the object side of the second lens barrel P02 to the clear aperture diameter of the image side of the second lens barrel P02, first, it is ensured that the light is relatively uniform when passing through the second lens group, avoiding the loss of marginal light, resulting in the marginal part of the image being darker than the central part, forming an imaging vignetting and affecting the overall quality of the image; second, during the zoom movement of the second lens group, the change in illuminance and the like can also be made smaller, avoiding obvious brightness differences during zooming and affecting the continuous effect during zoom shooting; furthermore, by restricting the upper limit of this ratio, stray light can also be reduced. If the clear aperture diameter of the object side of the lens barrel is too large relative to the clear aperture diameter of the image side of the lens barrel, more non-imaging light may enter the system, forming a stray light background on the image plane, reducing the imaging contrast and affecting the imaging effect.

[0098] Preferably, the second lens barrel P02 satisfies: 0.8 ≤ DT2s / DT2m ≤ 1.39.

[0099] According to some embodiments of the present application, the focusing lens group further satisfies: 2.10 < F2 / L2 ≤ 2.95 and 2.10 ≤ F2 / Td2 ≤ 2.85;

[0100] wherein, F2 is the effective focal length of the second lens group, L2 is the maximum height of the second lens barrel P02, and Td2 is the distance on the optical axis from the object side surface of the second lens E2 to the image side surface of the fifth lens E5 in the second lens group.

[0101] In this way, reasonably controlling the ratio of the effective focal length of the second lens group to the maximum height of the second lens barrel P02 helps to ensure the mechanical stability of the optical system. First, when the ratio is within a reasonable range, the size ratio of the second lens barrel P02 and the second lens group is relatively coordinated, which is convenient for installation and fixation, and can reduce problems such as vibration and offset caused by unreasonable structure, improving the reliability and stability of the system; second, further restricting the ratio of the effective focal length of the second lens group to the distance on the optical axis from the object side surface of the second lens E2 to the image side surface of the fifth lens E5 can keep the aberration at a good level. If the distance Td2 is too short, the propagation angle of light between the lens groups changes violently, increasing the difficulty of aberration correction, and spherical aberration, coma, etc. may occur; third, problems such as edge blurring and deformation when shooting distant objects are avoided. If the effective focal length is too long and the distance Td2 is relatively short at the same time, the degree of light convergence or divergence exceeds the correction ability of the lens group, and the image quality will also decline.

[0102] Preferably, the focusing lens group satisfies: 2.13 ≤ F2 / L2 ≤ 2.95 and 2.10 ≤ F2 / Td2 ≤ 2.85.

[0103] According to some embodiments of the present application, a second spacer element P2 in contact with the image side surface of the second lens E2 is provided on the image side of the second lens E2, and the focusing lens group further satisfies: 1.65 ≤ f2 / d2s < 5.20;

[0104] wherein, f2 is the effective focal length of the second lens E2, and d2s is the inner diameter of the object side surface of the second spacer element P2.

[0105] In this way, reasonably restricting the ratio of the effective focal length of the second lens E2 to the inner diameter of the object side surface of the second spacer element P2 can reduce light loss and the assembly sensitivity of the second lens E2. When the ratio is too large, the second spacer element P2 intercepts too much light, resulting in the loss of light energy and reducing the brightness and contrast of the image plane. When the ratio is too small, the converging or diverging ability of the second lens E2 to light is too intense, resulting in too high sensitivity of the second lens E2. The requirements for the second lens E2 during the assembly process are too high, affecting the yield rate of the second lens group, and further affecting the yield rate of the entire focusing lens group.

[0106] Preferably, the focusing lens group satisfies: 1.65 ≤ f2 / d2s ≤ 5.18.

[0107] According to some embodiments of the present application, a third spacer element P3 in contact with the image side surface of the third lens E3 is provided on the image side of the third lens E3, and the focusing lens group further satisfies: 0.50 < (f3 + f4) / d3s < 2.15;

[0108] wherein, f3 is the effective focal length of the third lens E3, f4 is the effective focal length of the fourth lens E4, and d3s is the inner diameter of the object side surface of the third spacer element P3.

[0109] In this way, reasonably controlling the ratio of the sum of the effective focal lengths of the third lens E3 and the fourth lens E4 to the inner diameter of the object side surface of the third spacer element P3 makes the intermediate transition light rays passing through the second lens E2 system more stable and can correct aberrations. On the one hand, under the condition that the inner diameter of the object side surface of the third spacer element P3 is certain, when the ratio is smaller, that is, when the sum of the effective focal lengths of the third lens E3 and the fourth lens E4 is smaller, the deflecting ability of the third lens E3 and the fourth lens E4 to light is too strong, and it is easy to cause large aberrations such as coma and astigmatism at the inner edge of the third spacer element P3, resulting in the phenomenon of distorted and blurred imaging at the edge of the picture; on the contrary, when the ratio is too large, the deflecting effect of the third lens E3 and the fourth lens E4 on light is insufficient, and the correction during the light propagation is not sufficient, which will also reduce the image quality of the picture. On the other hand, under the condition that the effective focal lengths of the third lens E3 and the fourth lens E4 are certain, a too large inner diameter of the object side surface of the third spacer element P3 will introduce extra light to form stray light, affecting the imaging quality; too small will intercept and affect the illuminance, forming a steep drop in the illuminance at the edge of the image plane to form a vignetting, affecting the imaging effect.

[0110] Preferably, the focusing lens group satisfies: 0.51 ≤ (f3 + f4) / d3s ≤ 2.14.

[0111] According to some embodiments of the present application, a fourth spacer element P4 in contact with the image side surface of the fourth lens E4 is provided on the image side of the fourth lens E4, and the focusing lens group further satisfies: 2.15 < f4 / d4m < 3.45;

[0112] wherein, f4 is the effective focal length of the fourth lens E4, and d4m is the inner diameter of the image side surface of the fourth spacer element P4.

[0113] In this way, by reasonably restricting the ratio of the effective focal length of the fourth lens E4 to the inner diameter of the image side surface of the fourth spacer element P4, the effective focal length of the fourth lens E4 can be more finely adjusted, and the light quantity and light trend of the light passing through the inner diameter of the fourth lens E4 and the fourth spacer element P4 can be controlled. Keeping the effective focal length of the fourth lens E4 within an appropriate range can ensure the overall illuminance level. Keeping the inner diameter of the image side surface of the fourth spacer element P4 within an appropriate range can control the passing amount of marginal light and ensure the illuminance level at the edge, so as to achieve a better picture effect of ensuring that the overall illuminance has no inflection and no steep drop.

[0114] Preferably, the focusing lens group satisfies: 2.16 ≤ f4 / d4m ≤ 3.42.

[0115] According to some embodiments of the present application, the focusing lens group further satisfies: 4.95 ≤ DT2m / (CT5×N5) < 11.95;

[0116] wherein, DT2m is the clear aperture diameter on the image side of the second lens barrel P02, CT5 is the central thickness of the fifth lens E5, and N5 is the refractive index of the fifth lens E5.

[0117] In this way, by reasonably restricting the ratio of the clear aperture diameter on the image side of the second lens barrel P02 to the central thickness of the fifth lens E5 and the refractive index of the fifth lens E5, on the one hand, under the condition that the clear aperture diameter on the image side of the second lens barrel P02 remains unchanged, the light can be reasonably distributed in the central thickness of the fifth lens E5 (i.e., the optical path at the center of the fifth lens E5), so as to make space for multiple lenses of the second lens group; under the condition that the central thickness and refractive index of the fifth lens E5 remain unchanged, the aperture of the outgoing light of the second lens group can be controlled to ensure sufficient outgoing light while intercepting excess stray light. On the other hand, it is beneficial to improve the assembly convenience and accuracy of the second lens group. When the ratio is appropriate, the sizes of the second lens barrel P02 and the fifth lens E5 are reasonably matched, which is convenient to adopt conventional assembly processes, can ensure the concentricity and relative position accuracy of the lens and the lens barrel, and reduce the influence of assembly errors on the optical performance.

[0118] Preferably, the focusing lens group satisfies: 4.95 ≤ DT2m / (CT5×N5) ≤ 11.93.

[0119] According to some embodiments of the present application, the focusing lens group further satisfies: 3.35 < DT2s / (CT2×N2) < 6.45;

[0120] Wherein, DT2s is the clear aperture diameter on the object side of the second lens barrel P02, CT2 is the central thickness of the second lens E2, and N2 is the refractive index of the second lens E2.

[0121] In this way, similarly, by reasonably restricting the ratio of the clear aperture diameter on the object side of the second lens barrel P02 to the central thickness of the second lens E2 and the refractive index of the second lens E2, on the one hand, under the condition that the clear aperture diameter on the object side of the second lens barrel P02 remains unchanged, the light is reasonably distributed in the central thickness of the second lens E2 (i.e., the optical path at the center of the second lens E2), leaving space for the other multiple lenses in the second lens group; under the condition that the optical path in the second lens E2 remains unchanged, the incident light angle of the second lens group is controlled to ensure sufficient incident light while intercepting excess stray light. On the other hand, it is beneficial to improve the assembly convenience and accuracy of the second lens group. When the ratio is appropriate, the sizes of the second lens barrel P02 and the second lens E2 are reasonably matched, facilitating the use of conventional assembly processes, ensuring the concentricity and relative position accuracy between the lens and the lens barrel, and reducing the influence of assembly errors on the optical performance.

[0122] Preferably, the focusing lens group satisfies: 3.39 ≤ DT2s / (CT2×N2) ≤ 6.42.

[0123] According to some embodiments of the present application, the focusing lens group satisfies: -3.50 < F3 / L3 ≤ -2.55 and 0.80 ≤ Td3 / L3 < 0.95;

[0124] Wherein, L3 is the maximum height of the third lens barrel P03 along the optical axis direction, F3 is the effective focal length of the third lens group, and Td3 is the distance on the optical axis from the object side surface of the sixth lens E6 to the image side surface of the seventh lens E7 in the third lens group.

[0125] In this way, reasonably controlling the ratio of the effective focal length of the third lens group to the maximum height of the third lens barrel P03 along the optical axis helps to ensure the mechanical stability of the optical system. When the ratio is within a reasonable range, the size ratio of the third lens barrel P03 and the third lens group is relatively coordinated, facilitating installation and fixation, and can reduce problems such as vibration and offset caused by unreasonable structure, improving the reliability and stability of the system. Further restricting the ratio of the distance between the object side of the sixth lens E6 and the image side of the seventh lens E7 on the optical axis to the maximum height of the third lens barrel P03 along the optical axis ensures that when the third lens group is assembled in the third lens barrel P03, it does not protrude beyond the outer end of the lens barrel as much as possible. Even if it protrudes, only the object side of the third lens group is allowed to protrude a little towards the second lens group, avoiding excessive protrusion of the third lens group beyond the third lens barrel P03 and colliding with the second lens group or other module structures (such as Figure 1 the prism E8 and the filter E9 in

[0126] Preferably, the focusing lens group satisfies: -3.49 ≤ F3 / L3 ≤ -2.55 and 0.8 ≤ Td3 / L3 ≤ 0.92.

[0127] According to some embodiments of the present application, the focusing lens group further satisfies: 3.65 < |F3| / (L3 - T67) ≤ 5.10;

[0128] Wherein, F3 is the effective focal length of the third lens group, L3 is the maximum height of the third lens barrel P03 along the optical axis, and T67 is the air gap between the sixth lens E6 and the seventh lens E7 on the optical axis.

[0129] In this way, reasonably restricting the ratio range of the effective focal length of the third lens group to the difference between the maximum height of the third lens barrel P03 and the air gap between the sixth lens E6 and the seventh lens E7 on the optical axis, on the one hand, is beneficial to ensuring the thickness space of the sixth lens E6 and the seventh lens E7, ensuring the strength and processability of the two lenses, and an appropriate air gap can also ensure the stability of the third lens group. On the other hand, the entire optical system exits to the image plane after passing through the third lens group. Controlling the effective focal length of the third lens group is beneficial to improving aberration. If the light is too convergent or divergent after being refracted by the third lens group and directly exits to the image plane, aberrations such as spherical aberration and coma increase, resulting in a decrease in resolution and the inability to clearly distinguish details in the image, affecting the imaging clarity.

[0130] Preferably, the focusing lens group satisfies: 3.69 ≤ |F3| / (L3 - T67) ≤ 5.10.

[0131] According to some embodiments of the present application, the focusing lens group further satisfies: 0.40 < ET6 / (CT6 + T67) ≤ 0.95;

[0132] Wherein, ET6 is the maximum thickness of the light-blocking region of the sixth lens E6, CT6 is the central thickness of the sixth lens E6, and T67 is the air gap on the optical axis between the sixth lens E6 and the seventh lens E7.

[0133] In this way, by reasonably controlling the ratio of the maximum thickness of the light-blocking region of the sixth lens E6 to the sum of the central thickness of the sixth lens E6 and the air gap on the optical axis between the sixth lens E6 and the seventh lens E7, parameters such as the edge thickness and central thickness of the sixth lens E6 are ensured to meet the molding requirements, with good processability, and the occurrence of poor molding problems is avoided. It can also make the cooperation between the sixth lens E6 and the seventh lens E7 more stable. When affected by external factors such as vibration and temperature changes, the optical performance can be better maintained, and the decrease in imaging quality caused by changes in the lens structure and the air gap on the optical axis between the sixth lens E6 and the seventh lens E7 can be reduced.

[0134] Preferably, the focusing lens group satisfies: 0.43 ≤ ET6 / (CT6 + T67) ≤ 0.91.

[0135] According to some embodiments of the present application, the focusing lens group further satisfies: 0.35 < ET7 / (T67 + CT7) < 1.10;

[0136] Wherein, ET7 is the maximum thickness of the light-blocking region of the seventh lens E7, CT7 is the central thickness of the seventh lens E7, and T67 is the air gap on the optical axis between the sixth lens E6 and the seventh lens E7.

[0137] In this way, similarly, by reasonably controlling the ratio of the maximum thickness of the light-blocking region of the seventh lens E7 to the sum of the central thickness of the seventh lens E7 and the air gap on the optical axis between the sixth lens E6 and the seventh lens E7, parameters such as the edge thickness and central thickness of the seventh lens E7 are ensured to meet the molding requirements, with good processability, and the occurrence of poor molding problems is avoided. It can also make the cooperation between the sixth lens E6 and the seventh lens E7 more stable. When affected by external factors such as vibration and temperature changes, the optical performance can be better maintained, and the decrease in imaging quality caused by changes in the lens structure and the air gap on the optical axis between the sixth lens E6 and the seventh lens E7 can be reduced.

[0138] Preferably, the focusing lens group satisfies: 0.37 ≤ ET7 / (T67 + CT7) ≤ 1.08.

[0139] According to some embodiments of the present application, the focusing lens group satisfies: 1.45 < F1 / F2 < 2.45 and -3.60 < F1 / F3 ≤ -2.10;

[0140] Wherein, F1 is the effective focal length of the first lens group, F2 is the effective focal length of the second lens group, and F3 is the effective focal length of the third lens group.

[0141] In this way, by reasonably restricting the ratio of the effective focal length of the first lens group to the effective focal length of the second lens group and the ratio of the effective focal length of the first lens group to the effective focal length of the third lens group respectively, on the one hand, it helps to balance the optical effects between different lens groups, thereby better correcting aberrations such as spherical aberration and coma. The first lens group cooperates with the second lens group and the third lens group to make the imaging clearer and sharper. On the other hand, it is beneficial to the balance of light propagation and energy distribution, avoiding most of the light being focused on a certain lens group or being overly divergent on a certain lens group, which affects the overall imaging brightness and contrast, etc.; this can also avoid the system design becoming redundant, and make full use of the advantages of multiple lens groups to make the light have a more reasonable propagation and energy distribution among the three lens groups.

[0142] Preferably, the focusing lens group satisfies: 1.48 ≤ F1 / F2 ≤ 2.43 and -3.59 ≤ F1 / F3 ≤ -2.1.

[0143] According to some embodiments of the present application, the focusing lens group further satisfies: 1.70 ≤ (T12 + T56) / ΔEP0 < 2.20;

[0144] Wherein, T12 is the air gap between the first lens E1 and the second lens E2 on the optical axis, T56 is the air gap between the fifth lens E5 and the sixth lens E6 on the optical axis, and ΔEP0 is the distance that the second lens barrel P02 can move along the optical axis.

[0145] In this way, by reasonably controlling the ratio of the sum of the air gaps between the first lens E1 and the second lens E2 on the optical axis and the air gap between the fifth lens E5 and the sixth lens E6 on the optical axis to the maximum distance that the second lens barrel P02 can move along the optical axis, on the one hand, it can ensure that when the lens barrel moves, the change in the air gap between the lenses matches the change in the focal length. When the second lens barrel P02 moves along the optical axis, by adjusting the air gaps between the first and second lenses and the fifth and sixth lenses, a smooth zooming process can be achieved, avoiding situations such as focal length jumps or image quality degradation. On the other hand, it controls the distance between the second lens group and the first lens group and the third lens group, avoiding collisions during the zooming process and damaging the lens group.

[0146] Preferably, the focusing lens group satisfies: 1.7 ≤ (T12 + T56) / ΔEP0 ≤ 2.18.

[0147] According to some embodiments of the present application, the focusing lens group further satisfies: 4.40 < (L1 + L2 + L3) / ΔEP0 < 5.55;

[0148] Wherein, L1 is the maximum height of the first lens barrel P01 along the optical axis direction, L2 is the maximum height of the second lens barrel P02 along the optical axis direction, L3 is the maximum height of the third lens barrel P03 along the optical axis direction, and ΔEP0 is the maximum distance that the second lens barrel P02 can move along the optical axis direction.

[0149] In this way, by reasonably restricting the ratio of the sum of the maximum heights of the three lens barrels, namely the first lens barrel P01, the second lens barrel P02, and the third lens barrel P03, to the maximum distance that the second lens barrel P02 can move along the optical axis direction, the mechanical structure of the optical system can be made more compact, and the space utilization rate can be improved. If the ratio is relatively large, that is, the total height of the three lens barrels is too large relative to the maximum distance that the second lens barrel P02 can move along the optical axis direction, the entire system may appear too tall and occupy too much space, which is not conducive to the miniaturization and portability of the device; if the ratio is relatively small, the total height of the three lens barrels is relatively low, and the moving distance of the second lens barrel P02 is too long, which may make the structure too loose and increase the lateral size of the system. Controlling the ratio within this range helps to make the system structure more compact and reasonable on the premise of ensuring the optical performance.

[0150] Preferably, the focusing lens group satisfies: 4.42 ≤ (L1 + L2 + L3) / ΔEP0 ≤ 5.53.

[0151] It should be noted that those skilled in the art should understand that without departing from the technical solution required to be protected by this application, the number of spacer elements constituting the focusing lens group can be changed to obtain the various results and advantages described in this specification, and this application does not make specific limitations in this regard. For example, according to needs, the focusing lens group may also include other numbers of spacer elements different from those described in the above embodiments.

[0152] Some specific but non-limiting embodiments of the above-described embodiments of the present application will be described in more detail below with reference to the accompanying drawings. For ease of description, in the following embodiments, OBJ represents the object plane of the focusing lens group, STO represents the surface of the aperture stop, S1 represents the object side surface of the first lens E1, S2 represents the image side surface of the first lens E1, S3 represents the object side surface of the second lens E2, S4 represents the image side surface of the second lens E2, S5 represents the object side surface of the third lens E3, S6 represents the image side surface of the third lens E3, S7 represents the object side surface of the fourth lens E4, S8 represents the image side surface of the fourth lens E4; S9 represents the object side surface of the fifth lens E5, S10 represents the image side surface of the fifth lens E5, S11 represents the object side surface of the sixth lens E6, S12 represents the image side surface of the sixth lens E6, S13 represents the object side surface of the seventh lens E7, S14 represents the image side surface of the seventh lens E7, S15 represents the object side surface of the prism E8, S16 represents the image side surface of the prism E8, S17 represents the object side surface of the filter E9, S18 represents the image side surface of the filter E9, and S19 represents the image plane. In addition, Aj represents the j-th order aspherical coefficient, where j = 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30.

[0153] It should be noted that the following three embodiments each include multiple working conditions, and the difference between the multiple working conditions in each embodiment lies in some structural dimension parameters of the lens barrel and the spacer elements.

[0154] Embodiment 1

[0155] As Figure 1 、 Figure 2 and Figures 3A to 3C shown, Figures 3A to 3C are respectively schematic structural diagrams of the focusing lens group in three working conditions of Embodiment 1. In this embodiment, the focusing lens group includes a first lens barrel P01, a second lens barrel P02, and a third lens barrel P03 arranged in sequence along the optical axis from the object side to the image side. The first lens barrel P01 houses a first lens group, which includes the first lens E1. The second lens barrel P02 houses a second lens group, which includes the second lens E2 to the fifth lens E5. The third lens barrel P03 houses a third lens group, which includes the sixth lens E6 and the seventh lens E7. The three lens groups distribute the optical power according to "positive - positive - negative", and the seven lenses distribute the optical power according to "positive - positive - negative - positive - positive - negative - negative".

[0156] In this embodiment, at least one spacer element is included between any two adjacent lenses in the second lens group. The multiple spacer elements are sequentially divided into a second spacer element P2, a third spacer element P3, and a fourth spacer element P4 from the object side to the image side. The object side and the image side of the second spacer element P2 are in contact with the image side of the second lens E2 and the object side of the third lens E3 respectively. The object side and the image side of the third spacer element P3 are in contact with the image side of the third lens E3 and the object side of the fourth lens E4 respectively. The object side and the image side of the fourth spacer element P4 are in contact with the image side of the fourth lens E4 and the object side of the fifth lens E5 respectively.

[0157] In this embodiment, a sixth spacer element P6 is further included in the third lens group. The object side and the image side of the sixth spacer element P6 are in contact with the image side of the sixth lens E6 and the object side of the seventh lens E7 respectively.

[0158] In this embodiment, the object side S1 of the first lens E1 is convex, and the image side S2 is convex; the object side S3 of the second lens E2 is convex, and the image side S4 is concave; the object side S5 of the third lens E3 is convex, and the image side S6 is concave; the object side S7 of the fourth lens E4 is convex, and the image side S8 is concave; the object side S9 of the fifth lens E5 is convex, and the image side S10 is convex; the object side S11 of the sixth lens E6 is concave, and the image side S12 is convex; the object side S13 of the seventh lens E7 is convex, and the image side S14 is concave.

[0159] It should be noted that, in this embodiment, the first lens E1 is made of glass material, and the second lens E2 to the seventh lens E7 are made of plastic material, which is beneficial to reducing the weight of the entire focusing lens group.

[0160] In summary, some structural parameters of the lens barrel and the spacer elements of the focusing lens group in Embodiment 1 under working conditions 1-1, 1-2, and 1-3 are shown in Table 8 below.

[0161] In addition, Table 1 shows the basic optical parameters of the focusing lens group in Embodiment 1. Among them, the units of the radius of curvature, thickness / distance, and effective radius are all millimeters (mm).

[0162] Table 1: Basic optical parameter table of the focusing lens group in Embodiment 1

[0163]

[0164] It should be noted that the materials in Table 1 include the refractive index and the Abbe number. For example, the materials 1.489 and 70.420 of S1 in Table 1 represent that the refractive index of the first lens E1 is 1.489 and the Abbe number is 70.420 in sequence.

[0165] In this embodiment, the object side and the image side of any one of the first lens E1 to the seventh lens E7 are aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0166] ;

[0167] where x is the sagitta, the distance from the vertex of the aspherical surface to the aspherical surface along the optical axis at a position with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, 18, 20, 22, 24, 26, 28, 30 for each of the aspherical surfaces S1 to S14 in Embodiment 1.

[0168] Table 2: Aspherical Coefficient Table of the Focusing Lens Group in Embodiment 1

[0169]

[0170] As Figures 4A to 4C and Figures 5A to 5C shown, Figures 4A to 4C are respectively the axial chromatic aberration curve, the astigmatism curve and the distortion curve of the focusing lens group shown in Embodiment 1 when the object distance is infinity, Figures 5A to 5C are respectively the axial chromatic aberration curve, the astigmatism curve and the distortion curve of the focusing lens group shown in Embodiment 1 when the object distance is 57.8556 mm. According to Figures 4A to 4C and Figures 5A to 5C it can be seen that the focusing lens group provided in Embodiment 1 has good optical performance and imaging effect.

[0171] Embodiment 2

[0172] As Figure 1 , Figure 2 and Figures 6A to 6C shown, Figures 6A to 6C are respectively the structural schematic diagrams of the focusing lens group in three working conditions of Embodiment 2. In this embodiment, the focusing lens group includes a first lens barrel P01, a second lens barrel P02 and a third lens barrel P03 arranged in sequence from the object side to the image side along the optical axis. The first lens barrel P01 is internally provided with a first lens group, and the first lens group includes a first lens E1. The second lens barrel P02 is internally provided with a second lens group, and the second lens group includes a second lens E2 to a fifth lens E5. The third lens barrel P03 is internally provided with a third lens group, and the third lens group includes a sixth lens E6 and a seventh lens E7; the three lens groups distribute the optical power according to "positive-positive-negative", and the seven lenses distribute the optical power according to "positive-positive-negative-positive-positive-negative-negative".

[0173] In this embodiment, at least one spacer element is included between any two adjacent lenses in the second lens group. The multiple spacer elements are sequentially divided into a second spacer element P2, a third spacer element P3, and a fourth spacer element P4 from the object side to the image side. The object side and the image side of the second spacer element P2 are in contact with the image side of the second lens E2 and the object side of the third lens E3 respectively. The object side and the image side of the third spacer element P3 are in contact with the image side of the third lens E3 and the object side of the fourth lens E4 respectively. The object side and the image side of the fourth spacer element P4 are in contact with the image side of the fourth lens E4 and the object side of the fifth lens E5 respectively.

[0174] In this embodiment, a sixth spacer element P6 is further included in the third lens group. The object side and the image side of the sixth spacer element P6 are in contact with the image side of the sixth lens E6 and the object side of the seventh lens E7 respectively.

[0175] In this embodiment, the object side S1 of the first lens E1 is convex, and the image side S2 is concave; the object side S3 of the second lens E2 is convex, and the image side S4 is concave; the object side S5 of the third lens E3 is concave, and the image side S6 is concave; the object side S7 of the fourth lens E4 is convex, and the image side S8 is concave; the object side S9 of the fifth lens E5 is convex, and the image side S10 is convex; the object side S11 of the sixth lens E6 is concave, and the image side S12 is convex; the object side S13 of the seventh lens E7 is convex, and the image side S14 is concave.

[0176] It should be noted that, in this embodiment, the first lens E1 is made of glass material, and the second lens E2 to the seventh lens E7 are made of plastic material, which is beneficial to reducing the weight of the entire focusing lens group.

[0177] In summary, some structural parameters of the lens barrel and the spacer elements of the focusing lens group in Embodiment 2 under working conditions 2-1, 2-2, and 2-3 are shown in Table 8 below.

[0178] In addition, Table 3 shows the basic optical parameters of the focusing lens group of Embodiment 2. Among them, the units of the radius of curvature, thickness / distance, and effective radius are all millimeters (mm).

[0179] Table 3: Basic Optical Parameter Table of the Focusing Lens Group of Embodiment 2

[0180]

[0181] It should be noted that the materials in Table 3 include the refractive index and the Abbe number. For example, the material 1.498 and 81.56 of S1 in Table 3 respectively represent that the refractive index of the first lens E1 is 1.498 and the Abbe number is 81.56.

[0182] In this embodiment, the object side and the image side of any one of the first lens E1 to the seventh lens E7 are aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0183] ;

[0184] where x is the sagitta, which is the distance from the vertex of the aspherical surface to the aspherical surface along the optical axis at a position with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface. Table 4 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, 18, 20, 22, 24, 26, 28, 30 that can be used for each aspherical mirror surface S1 to S14 in Embodiment 2.

[0185] Table 4: Aspherical Coefficient Table of the Focusing Lens Group in Embodiment 2

[0186]

[0187] As Figures 7A to 7C and Figures 8A to 8C shown, Figures 7A to 7C are respectively the axial chromatic aberration curve, the astigmatism curve and the distortion curve of the focusing lens group shown in Embodiment 2 when the object distance is infinity, Figures 8A to 8C are respectively the axial chromatic aberration curve, the astigmatism curve and the distortion curve of the focusing lens group shown in Embodiment 2 when the object distance is 52.6455 mm. According to Figures 7A to 7C and Figures 8A to 8C it can be seen that the focusing lens group provided in Embodiment 2 has good optical performance and imaging effect.

[0188] Embodiment 3

[0189] As Figure 1 , Figure 2 and Figures 9A to 9C shown, Figures 9A to 9C are respectively the structural schematic diagrams of the focusing lens group in Embodiment 3 under three working conditions. In this embodiment, the focusing lens group includes a first lens barrel P01, a second lens barrel P02 and a third lens barrel P03 arranged in sequence from the object side to the image side along the optical axis. The first lens barrel P01 is internally provided with a first lens group, and the first lens group includes a first lens E1. The second lens barrel P02 is internally provided with a second lens group, and the second lens group includes a second lens E2 to a fifth lens E5. The third lens barrel P03 is internally provided with a third lens group, and the third lens group includes a sixth lens E6 and a seventh lens E7; the three lens groups distribute the optical power according to "positive-positive-negative", and the seven lenses distribute the optical power according to "positive-positive-negative-positive-positive-negative-negative".

[0190] In this embodiment, at least one spacer element is included between any two adjacent lenses in the second lens group. The multiple spacer elements are sequentially divided into a second spacer element P2, a third spacer element P3, and a fourth spacer element P4 from the object side to the image side. The object side and the image side of the second spacer element P2 are in contact with the image side of the second lens E2 and the object side of the third lens E3 respectively. The object side and the image side of the third spacer element P3 are in contact with the image side of the third lens E3 and the object side of the fourth lens E4 respectively. The object side and the image side of the fourth spacer element P4 are in contact with the image side of the fourth lens E4 and the object side of the fifth lens E5 respectively.

[0191] In this embodiment, a sixth spacer element P6 is further included in the third lens group. The object side and the image side of the sixth spacer element P6 are in contact with the image side of the sixth lens E6 and the object side of the seventh lens E7 respectively.

[0192] In this embodiment, the object side S1 of the first lens E1 is convex and the image side S2 is concave; the object side S3 of the second lens E2 is convex and the image side S4 is convex; the object side S5 of the third lens E3 is concave and the image side S6 is concave; the object side S7 of the fourth lens E4 is convex and the image side S8 is concave; the object side S9 of the fifth lens E5 is concave and the image side S10 is convex; the object side S11 of the sixth lens E6 is concave and the image side S12 is convex; the object side S13 of the seventh lens E7 is convex and the image side S14 is concave.

[0193] It should be noted that, in this embodiment, the first lens E1 is made of glass material, and the second lens E2 to the seventh lens E7 are made of plastic material, which is beneficial to reducing the weight of the entire focusing lens group.

[0194] In summary, some structural parameters of the lens barrel and the spacer elements of the focusing lens group in Embodiment 3 under Working Conditions 3-1, 3-2, and 3-3 are shown in Table 8 below.

[0195] In addition, Table 5 shows the basic optical parameters of the focusing lens group of Embodiment 3, where the units of the radius of curvature, thickness / distance, and effective radius are all millimeters (mm).

[0196] Table 5: Basic Optical Parameter Table of the Focusing Lens Group of Embodiment 3

[0197]

[0198] It should be noted that the materials in Table 5 include the refractive index and the Abbe number. For example, the material 1.489 and 70.420 of S1 in Table 5 respectively represent that the refractive index of the first lens E1 is 1.489 and the Abbe number is 70.420.

[0199] In this embodiment, the object side and the image side of any one of the first lens E1 to the seventh lens E7 are aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0200] ;

[0201] where x is the sagitta, the distance from the vertex of the aspherical surface along the optical axis at a position with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface. Table 6 below gives the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, 18, 20, 22, 24, 26, 28, 30 for each of the aspherical surfaces S1 to S14 in Embodiment 3.

[0202] Table 6: Aspherical Coefficient Table of the Focusing Lens Group in Embodiment 3

[0203]

[0204] As Figures 10A to 10C and Figures 11A to 11C shown, Figures 10A to 10C are respectively the axial chromatic aberration curve, the astigmatism curve, and the distortion curve of the focusing lens group shown in Embodiment 3 when the object distance is infinity, Figures 11A to 11C are respectively the axial chromatic aberration curve, the astigmatism curve, and the distortion curve of the focusing lens group shown in Embodiment 3 when the object distance is 66.6675 mm. According to Figures 10A to 10C and Figures 11A to 11C it can be seen that the focusing lens group provided in Embodiment 3 has good optical performance and imaging effect.

[0205] In summary, in Embodiments 1 to 3, the effective focal lengths F1 to F3 of the first lens group to the third lens group in the focusing lens group, the effective focal lengths f of the focusing lens group when the object distances are infinity and close range respectively, and the aperture coefficient Fno of the focusing lens group are shown in Table 7 below.

[0206] Table 7: System Optical Parameter Table of the Focusing Lens Group

[0207]

[0208] In addition, some structural parameters (DT2s, DT2m, d2s, d3s, d4m, L1, L2, L3, ΔEP0, ET6, ET7) of the lens barrel and the spacer elements of the focusing lens group in Embodiments 1 to 3 are shown in Table 8 specifically.

[0209] Table 8: Partial Structural Parameter Table of the Focusing Lens Group

[0210]

[0211] In summary, the focusing lens groups in Embodiment 1 to Embodiment 3 satisfy the relational expressions shown in Table 9:

[0212] Table 9: Table of Relational Expressions Satisfied by the Focusing Lens Group

[0213]

[0214] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0215] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A focusing lens assembly, characterized in that: It includes a first lens barrel, a second lens barrel, and a third lens barrel arranged in sequence along the same optical axis. The second lens barrel is movably arranged between the first lens barrel and the third lens barrel; A first lens group is installed in the first lens barrel. The first lens group includes a first lens with a positive optical power; A second lens group is installed in the second lens barrel. The second lens group has a positive optical power. The second lens group includes a second lens with a positive optical power, a third lens with a negative optical power, a fourth lens with a positive optical power, and a fifth lens with a positive optical power; A third lens group is installed in the third lens barrel. The third lens group has a negative optical power. The third lens group includes a sixth lens with a negative optical power and a seventh lens with a negative optical power; There is at least one spacer element between any two adjacent lenses in the second lens group. The object side of the spacer element is in contact with the adjacent lens; The focusing lens group satisfies: 4.95 < (F1 + F2 + F3) / |Δf| < 5.85; and 2.35 ≤ (DT2s + DT2m) / Td2 ≤ 3.30; Wherein, F1 is the effective focal length of the first lens group, F2 is the effective focal length of the second lens group, F3 is the effective focal length of the third lens group; Δf is the change difference of the effective focal length of the focusing lens group when the second lens barrel moves from the position closest to the first lens barrel to the position closest to the third lens barrel; DT2s is the clear aperture diameter on the object side of the second lens barrel, DT2m is the clear aperture diameter on the image side of the second lens barrel; Td2 is the distance on the optical axis from the object side surface of the second lens to the image side surface of the fifth lens in the second lens group.

2. The focusing lens assembly according to claim 1, characterized in that: The second lens barrel satisfies: 0.80 ≤ DT2s / DT2m < 1.40; Wherein, DT2s is the clear aperture diameter on the object side of the second lens barrel, DT2m is the clear aperture diameter on the image side of the second lens barrel.

3. The focusing lens assembly according to claim 1, characterized in that: The focusing lens group satisfies: 2.10 < F2 / L2 ≤ 2.95; and 2.10 ≤ F2 / Td2 ≤ 2.85; Wherein, F2 is the effective focal length of the second lens group, L2 is the maximum height of the second lens barrel, Td2 is the distance on the optical axis from the object side surface of the second lens to the image side surface of the fifth lens in the second lens group.

4. The focusing lens assembly according to claim 1, characterized in that: A second spacer element in contact with the image side surface of the second lens is provided on the image side of the second lens. The focusing lens group further satisfies: 1.65 ≤ f2 / d2s < 5.20; Wherein, f2 is the effective focal length of the second lens, d2s is the inner diameter of the object side surface of the second spacer element.

5. The focusing lens assembly according to claim 1, characterized in that: A third spacer element in contact with the image side surface of the third lens is provided on the image side of the third lens. The focusing lens group further satisfies: 0.50 < (f3 + f4) / d3s < 2.15; Wherein, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, d3s is the inner diameter of the object side surface of the third spacer element.

6. The focusing lens assembly according to claim 1, characterized in that: A fourth spacer element in contact with the image side surface of the fourth lens is provided on the image side of the fourth lens. The focusing lens group further satisfies: 2.15 <f4 / d4m<3.45; Wherein, f4 is the effective focal length of the fourth lens, and d4m is the inner diameter of the image side surface of the fourth spacing element.

7. The focusing lens assembly according to claim 1, characterized in that: The focusing lens group also satisfies: 4.95≤DT2m / (CT5×N5)<11.95; Wherein, DT2m is the light-transmitting diameter of the second lens barrel on the image side, CT5 is the center thickness of the fifth lens, and N5 is the refractive index of the fifth lens.

8. The focusing lens assembly according to claim 1, characterized in that: The focusing lens group also satisfies: 3.35 <DT2s / (CT2×N2)<6.45; Wherein, DT2s is the light-transmitting diameter of the second lens barrel on the object side, CT2 is the center thickness of the second lens, and N2 is the refractive index of the second lens.

9. The focusing lens assembly according to claim 1, characterized in that: The focusing lens group satisfies: -3.50 <F3 / L3≤-2.55; and 0.80≤Td3 / L3<0.95; Wherein, L3 is the maximum height of the third lens barrel along the optical axis, F3 is the effective focal length of the third lens group, and Td3 is the distance on the optical axis from the object side surface of the sixth lens in the third lens group to the image side surface of the seventh lens.

10. The focusing lens assembly according to claim 1, wherein: The focusing lens group also satisfies: 3.65<|F3| / (L3-T67)≤5.10; Wherein, F3 is the effective focal length of the third lens group, L3 is the maximum height of the third lens barrel along the optical axis, and T67 is the air spacing between the sixth lens and the seventh lens on the optical axis.

11. The focusing lens assembly according to claim 1, characterized in that: The focusing lens group also satisfies: 0.40 <ET6 / (CT6+T67)<0.95; Wherein, ET6 is the maximum thickness of the non-light-transmitting area of ​​the sixth lens, CT6 is the center thickness of the sixth lens, and T67 is the air gap between the sixth lens and the seventh lens on the optical axis.

12. The focusing lens assembly according to claim 1, characterized in that: The focusing lens group also satisfies: 0.35 <ET7 / (T67+CT7)<1.10; ET7 is the maximum thickness of the non-light-transmitting area of ​​the seventh lens, CT7 is the center thickness of the seventh lens, and T67 is the air gap between the sixth lens and the seventh lens on the optical axis.

13. The focusing lens assembly according to any one of claims 1 to 12, characterized in that: The focusing lens group satisfies: 1.45 <F1 / F2<2.45; and -3.60 <F1 / F3≤-2.10; Among them, F1 is the effective focal length of the first lens group, F2 is the effective focal length of the second lens group, and F3 is the effective focal length of the third lens group.

14. The focusing lens assembly according to any one of claims 1 to 12, characterized in that: The focusing lens group also satisfies: 1.70≤(T12+T56) / ΔEP0<2.20; Wherein, T12 is the air interval between the first lens and the second lens on the optical axis, T56 is the air interval between the fifth lens and the sixth lens on the optical axis, and ΔEP0 is the maximum distance that the second lens barrel can move along the optical axis.

15. The focusing lens assembly according to any one of claims 1 to 12, characterized in that: The focusing lens group also satisfies: 4.40<(L1+L2+L3) / ΔEP0<5.55; Among them, L1 is the maximum height of the first lens barrel along the optical axis, L2 is the maximum height of the second lens barrel along the optical axis, L3 is the maximum height of the third lens barrel along the optical axis, and ΔEP0 is the maximum distance that the second lens barrel can move along the optical axis.

Images