CN113900222A

CN113900222A - Optical system, image capturing module and electronic equipment

Info

Publication number: CN113900222A
Application number: CN202111108697.0A
Authority: CN
Inventors: 曾晗; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-09-22
Filing date: 2021-09-22
Publication date: 2022-01-07
Anticipated expiration: 2041-09-22
Also published as: CN113900222B

Abstract

The invention relates to an optical system, an image capturing module and an electronic device. The optical system includes: a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface; a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a third lens element with refractive power having a convex object-side surface at paraxial region; a fourth lens element with positive refractive power; a fifth lens element with refractive power having a concave object-side surface at paraxial region; a sixth lens element with refractive power having a convex object-side surface at paraxial region and a concave image-side surface at paraxial region; a seventh lens element with negative refractive power having a convex object-side surface and a concave image-side surface; the optical system satisfies: CT16/BL is more than or equal to 0.24 and less than or equal to 0.28. The optical system can meet the design of a small head, and is favorable for improving the screen occupation ratio of electronic equipment.

Description

Optical system, image capturing module and electronic equipment

Technical Field

The present invention relates to the field of camera shooting, and in particular, to an optical system, an image capturing module and an electronic device.

Background

With the rapid development of electronic devices such as smart phones, tablet computers, electronic readers and the like, the application of the camera lens in the electronic devices is more and more extensive. Among them, in order to increase the screen occupation ratio of the electronic device, a design has been developed in the electronic device in which a camera lens is placed under a display screen to realize an off-screen camera function. For equipment with the function of shooting under the screen, the structure of the camera lens determines the opening size of the display screen to a great extent, and then the screen occupation ratio of the electronic equipment is influenced. However, the current camera lens is difficult to meet the requirement of high screen occupation ratio of the electronic equipment.

Disclosure of Invention

Therefore, it is necessary to provide an optical system, an image capturing module and an electronic device for solving the problem that the conventional camera lens is difficult to meet the requirement of high screen ratio of the electronic device.

An optical system includes, in order from an object side to an image side along an optical axis:

a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

a third lens element with refractive power having a convex object-side surface at paraxial region;

a fourth lens element with positive refractive power;

a fifth lens element with refractive power having a concave object-side surface at paraxial region;

a sixth lens element with refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

a seventh lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

and the optical system satisfies the following conditional expression:

0.24≤CT16/BL≤0.28；

wherein, CT16 is a distance on an optical axis from an object-side surface of the first lens element to an image-side surface of the third lens element, and BL is a distance on an optical axis from the object-side surface of the first lens element to the image-side surface of the seventh lens element.

In the optical system, the first lens element has positive refractive power, and the object-side surface of the first lens element is convex at a paraxial region, so that light rays can be effectively converged, and the total length of the optical system can be shortened. The second lens has negative refractive power, which is beneficial to balancing spherical aberration and chromatic aberration generated by the first lens, thereby improving the imaging quality of the optical system. The object-side surface of the second lens element is convex at the paraxial region, and the image-side surface thereof is concave at the paraxial region, which is advantageous for correcting astigmatism of the optical system. The fourth lens element has positive refractive power, and is favorable for correcting meridional coma and spherical aberration of the optical system. The object side surface of the seventh lens element is convex at the paraxial region, which is advantageous for correcting off-axis image curvature. The image side surface of the seventh lens element is concave at the paraxial region, so that the principal point can be shifted toward the object side, which is advantageous for shortening the back focus and total length of the optical system. The optical system has the refractive power and the surface shape characteristics, and has good imaging quality.

When the conditional expressions are met, the proportion of the lengths of the first three lenses on the optical axis to the lengths of the seven lenses on the optical axis can be reasonably configured, so that the effective calibers of the first lens, the second lens and the third lens are favorably and fully compressed, namely the front end calibers of the optical system are favorably compressed, the appearance design of a small head is favorably realized, and the opening size of a display screen can be reduced when the optical system is applied to under-screen shooting so as to meet the requirement of high screen proportion of electronic equipment; in addition, the total length of the optical system is favorably shortened, so that the visual angle range of the optical system is favorably expanded, and the optical system can obtain more comprehensive scenes. Below the lower limit of the above conditional expression, the thicknesses and gaps of the first lens, the second lens and the third lens are too small to facilitate the processing and assembling of the lenses. When the total length of the front lens group formed by the first lens, the second lens and the third lens is too large, the emergent angle of the main light ray of the light ray entering the imaging surface is too large, so that the light ray at the edge of the imaging surface cannot be imaged normally, and imaging information is incomplete.

In one embodiment, the optical system satisfies the following conditional expression:

0.13mm^-1≤tan(HFOV)/TTL≤0.15mm^-1；

the HFOV is a half of a maximum field angle of the optical system, and the TTL is a distance on an optical axis from an object-side surface of the first lens to an image plane of the optical system, that is, an optical total length of the optical system. When the condition formula is satisfied, the optical total length and the maximum field angle of the optical system can be reasonably configured, the total length of the optical system is favorably shortened, the miniaturization design is realized, and meanwhile, the optical system has the characteristic of large field angle, so that more scene contents can be acquired, and the imaging information of the optical system is enriched. Below the lower limit of the above conditional expression, the total length of the optical system is too large, which is disadvantageous for the miniaturization design of the optical system; exceeding the upper limit of the above conditional expression makes the structure of the optical system too compact, makes aberration correction difficult, and thus tends to cause a decrease in imaging performance.

1.5mm^-1≤FNO/SD11≤2mm^-1；

wherein FNO is the f-number of the optical system, and SD11 is half of the maximum effective aperture of the object side surface of the first lens. When the condition formula is met, the optical system can realize the characteristic of a large aperture, so that the light inlet quantity of the optical system is improved, the optical system can have good imaging quality in a low-light environment, and meanwhile, the optical system can have a better blurring effect, and the requirement of high imaging quality is met; in addition, the effective caliber of the object side surface of the first lens is favorably and fully compressed, so that the realization of small-head design is favorably realized. Below the lower limit of the conditional expression, the effective aperture of the object side surface of the first lens is not fully compressed, which is not beneficial to the small head design of the optical system, and the marginal rays cannot be reasonably intercepted, which leads to the increase of field curvature and the formation of a marginal distortion image, thereby leading to the reduction of imaging quality; if the upper limit of the above conditional expression is exceeded, the effective aperture of the object-side surface of the first lens is too small, which is disadvantageous for enlarging the aperture of the optical system, resulting in insufficient light transmission amount and difficulty in satisfying the requirement of high imaging quality.

1.1≤TTL/ImgH≤1.22；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and ImgH is half of an image height corresponding to a maximum field angle of the optical system. When the condition formula is met, the ratio of the total optical length of the optical system to the half image height can be reasonably configured, the total optical length of the optical system is favorably shortened, the miniaturization design is realized, and the optical system is also favorably provided with the large image surface characteristic, so that the optical system can be matched with the photosensitive element with larger size, the high resolution is obtained, and the miniaturization design of the optical system and the realization of high imaging quality are considered. If the upper limit of the conditional expression is exceeded, the image height of the optical system is too small to match with a photosensitive element with a larger size, so that the imaging quality of the optical system cannot be improved; meanwhile, the overall length of the optical system is too large, which is not beneficial to the miniaturization design of the optical system; below the lower limit of the above conditional expression, the total length of the optical system is too small, the arrangement of the lenses is crowded, which is not favorable for aberration correction, and the imaging quality of telephoto is also not good.

0.75≤(ET1+ET2+ET3)/(CT1+CT2+CT3)≤0.85；

wherein ET1 is a distance in an optical axis direction from a maximum effective aperture of an object-side surface of the first lens element to a maximum effective aperture of an image-side surface of the first lens element, i.e., an edge thickness of the first lens element, ET2 is a distance in an optical axis direction from a maximum effective aperture of an object-side surface of the second lens element to a maximum effective aperture of an image-side surface of the second lens element, i.e., an edge thickness of the second lens element, ET3 is a distance in an optical axis direction from a maximum effective aperture of an object-side surface of the third lens element to a maximum effective aperture of an image-side surface of the third lens element, i.e., an edge thickness of the third lens element, CT1 is a thickness of the first lens element in an optical axis direction, i.e., a center thickness of the first lens element, CT2 is a thickness of the second lens element in an optical axis direction, i.e., a center thickness of the second lens element, and CT3 is a thickness of the third lens element in an optical axis direction, i.e. the central thickness of the third lens. When the condition is satisfied, the center thicknesses of the first lens, the second lens and the third lens are prevented from being too thin relative to the edge thicknesses, so that the insufficient refractive power of a front lens group formed by the first lens, the second lens and the third lens is prevented, and the front lens group can effectively deflect light rays and correct the aberration of the optical system; meanwhile, the center thicknesses of the first lens, the second lens and the third lens are prevented from being too thick relative to the edge thicknesses, so that the surface shapes of the first lens, the second lens and the third lens are not too curved, and the design and the manufacture of the first lens, the second lens and the third lens are facilitated. When the upper limit of the conditional expression is exceeded, the central thicknesses of the first lens element, the second lens element and the third lens element are too thin relative to the peripheral thicknesses, which results in insufficient refractive power of the front lens element, is not favorable for deflecting light rays and correcting aberration of the optical system, and also results in too large field curvature of the image plane. When the thickness of the center of the first lens, the center of the second lens, and the center of the third lens are too thick compared with the thickness of the edge of the first lens, the second lens, and the third lens, the surface shapes of the first lens, the second lens, and the third lens are too curved, and the molding yield of the first lens, the second lens, and the third lens is reduced.

1.3≤|SAG51|/CT5≤1.8；

SAG51 is the rise of the object-side surface of the fifth lens at the maximum effective aperture, namely the distance from the intersection point of the object-side surface of the fifth lens and the optical axis to the maximum effective aperture of the object-side surface of the fifth lens in the optical axis direction, and CT5 is the thickness of the fifth lens on the optical axis, namely the center thickness of the fifth lens. When the conditional expression is met, the shape of the object side surface of the fifth lens can be reasonably configured, so that the surface shape of the object side surface of the fifth lens at the position close to the circumference is not excessively bent, the manufacturing and molding of the lens are facilitated, and the defect of poor molding is reduced; meanwhile, the surface shape of the object side surface of the fifth lens close to the circumference cannot be too smooth, so that the field curvature generated by each lens of the object side can be corrected, the field curvature sizes of different fields tend to be balanced, the image quality of an imaging picture of the whole optical system is uniform, and the imaging quality of the optical system is improved. Below the lower limit of the conditional expression, the surface shape of the object-side surface of the fifth lens at the position close to the circumference is too smooth, so that the deflection capability of the fifth lens on the off-axis field-of-view light is insufficient, and the correction of distortion and field curvature aberration is not facilitated; if the upper limit of the above conditional expression is exceeded, the surface shape of the object-side surface of the fifth lens at the position near the circumference is excessively curved, which tends to cause poor molding of the fifth lens, and thus the manufacturing yield is affected.

0.6≤(R41-R42)/(R41+R42)≤1；

wherein R41 is a radius of curvature of an object-side surface of the fourth lens element at an optical axis, and R42 is a radius of curvature of an image-side surface of the fourth lens element at the optical axis. When the conditional expressions are met, the surface types of the object side surface and the image side surface of the fourth lens can be reasonably configured, so that the surface types of the object side surface and the image side surface of the fourth lens cannot be too smooth or excessively bent, the optical path difference of light rays of a central view field and an edge view field in an optical system is favorably balanced, the optical path difference of the central view field and the edge view field is prevented from being too large, the light rays of the central view field and the edge view field can be converged to the vicinity of the same plane, and the field curvature of the optical system is favorably corrected; in addition, the center of the fourth lens is prevented from being too thin and too thick compared with the edge, so that the precision requirement of production and processing is met, and the forming yield is guaranteed.

1≤f1/f≤1.2；

wherein f1 is the effective focal length of the first lens, and f is the effective focal length of the optical system. When the conditional expression is met, the refractive power ratio of the first lens in the optical system can be reasonably configured, so that the first lens can provide enough positive refractive power for the optical system, and the convergence of light rays is facilitated, thereby realizing the miniaturization design of the optical system; meanwhile, the over-strong positive refractive power of the first lens can be avoided, so that the second lens and the third lens can correct aberration generated by the first lens, the imaging quality of an optical system is improved, the surface type of the first lens is prevented from being excessively bent, and the manufacturing and forming of the first lens are facilitated. Above the upper limit of the above conditional expression, the first lens element provides insufficient positive refractive power for the optical system, which results in a decrease in light collecting capability of the optical system and is not favorable for the miniaturization design of the optical system. Below the lower limit of the conditional expression, the positive refractive power provided by the first lens element for the optical system is too strong, which is not favorable for the second lens element and the third lens element to correct the aberration generated by the first lens element, thereby reducing the imaging quality of the optical system.

An image capturing module includes a photosensitive element and the optical system of any of the above embodiments, wherein the photosensitive element is disposed at an image side of the optical system. Adopt above-mentioned optical system among the module for getting for instance, can possess good image quality and realize little head design, and can satisfy the demand of shooing on a large scale.

An electronic device comprises a shell and the image capturing module, wherein the image capturing module is arranged on the shell. Adopt above-mentioned getting for instance the module among the electronic equipment, get for instance the module and possess good imaging quality and can satisfy the demand of shooing on a large scale, possess little head design simultaneously for electronic equipment adopts the screen to hold up the ratio when the trompil design is under the screen in being favorable to promoting electronic equipment.

Drawings

FIG. 1 is a schematic structural diagram of an optical system according to a first embodiment of the present application;

FIG. 2 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a first embodiment of the present application;

FIG. 3 is a schematic structural diagram of an optical system according to a second embodiment of the present application;

FIG. 4 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a second embodiment of the present application;

FIG. 5 is a schematic structural diagram of an optical system according to a third embodiment of the present application;

FIG. 6 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a third embodiment of the present application;

FIG. 7 is a schematic structural diagram of an optical system according to a fourth embodiment of the present application;

FIG. 8 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a fourth embodiment of the present application;

FIG. 9 is a schematic structural diagram of an optical system according to a fifth embodiment of the present application;

FIG. 10 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a fifth embodiment of the present application;

fig. 11 is a schematic view of an image capturing module according to an embodiment of the present application;

fig. 12 is a schematic diagram of an electronic device in an embodiment of the present application.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, in some embodiments of the present application, an optical system 100 includes, in order from an object side to an image side along an optical axis 110, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. Specifically, the first lens L1 includes an object-side surface S1 and an image-side surface S2, the second lens L2 includes an object-side surface S3 and an image-side surface S4, the third lens L3 includes an object-side surface S5 and an image-side surface S6, the fourth lens L4 includes an object-side surface S7 and an image-side surface S8, the fifth lens L5 includes an object-side surface S9 and an image-side surface S10, the sixth lens L6 includes an object-side surface S11 and an image-side surface S12, and the seventh lens L7 includes an object-side surface S13 and an image-side surface S14. The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are coaxially disposed, and an axis common to the lenses in the optical system 100 is the optical axis 110 of the optical system 100.

The first lens element L1 with positive refractive power has a convex object-side surface S1 of the first lens element L1 near the optical axis 110, which can effectively converge light beams and is beneficial to shortening the total length of the optical system 100. The image-side surface S2 of the first lens element L1 is concave at the paraxial region 110. The second lens element L2 with negative refractive power is favorable for balancing the spherical aberration and chromatic aberration generated by the first lens element L1, thereby improving the imaging quality of the optical system 100. The object-side surface S3 of the second lens element L2 is convex at the paraxial region 110, and the image-side surface S4 is concave at the paraxial region 110, which is favorable for correcting astigmatism of the optical system 100. The third lens element L3 with refractive power has a convex object-side surface S5 at a paraxial region 110 of the third lens element L3. The fourth lens element L4 has positive refractive power, and is favorable for correcting meridional coma and spherical aberration of the optical system 100. The fifth lens element L5 with refractive power has a concave object-side surface S9 at a paraxial region 110 of the fifth lens element L5. The sixth lens element L6 with refractive power has a convex object-side surface S11 at a paraxial region 110 and a concave image-side surface S12 at a paraxial region 110 of the sixth lens element L6. The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 is convex at the paraxial region 110, which is advantageous for correcting off-axis image curvature. The image-side surface S14 of the seventh lens element L7 is concave at the paraxial region 110, so that the principal point can be shifted toward the object side, which is beneficial for shortening the back focus and total length of the optical system 100. With the above-described refractive power and surface profile characteristics, the optical system 100 can have good imaging quality.

In some embodiments, the object-side surface S13 and the image-side surface S14 of the seventh lens element L7 are aspheric, which is favorable for correcting spherical aberration and improving the imaging quality of the optical system 100. In some embodiments, at least one of the object-side surface S13 and the image-side surface S14 of the seventh lens element L7 has a point of inflection that facilitates proper configuration of the refractive power in the vertical direction, thereby facilitating correction of the aberrations of the off-axis field and improving the imaging quality of the optical system 100.

In addition, in some embodiments, the optical system 100 is provided with a stop STO, which may be disposed on the object side of the first lens L1. In some embodiments, the optical system 100 further includes an infrared filter L8 disposed on the image side of the seventh lens L7. The ir filter L8 may be an ir cut filter, and is used to filter out interference light, so as to prevent the interference light from reaching the image plane of the optical system 100 and affecting normal imaging. Furthermore, the optical system 100 further includes an image plane S17 located on the image side of the seventh lens L7, the image plane S17 is an imaging plane of the optical system 100, and incident light is adjusted by the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 and can be imaged on the image plane S17.

In some embodiments, the object-side surface and the image-side surface of each lens of optical system 100 are both aspheric. The adoption of the aspheric surface structure can improve the flexibility of lens design, effectively correct spherical aberration and improve imaging quality. In other embodiments, the object-side surface and the image-side surface of each lens of the optical system 100 may be spherical. It should be noted that the above embodiments are only examples of some embodiments of the present application, and in some embodiments, the surface of each lens in the optical system 100 may be an aspheric surface or any combination of spherical surfaces.

In some embodiments, each lens in the optical system 100 may be made of glass or plastic. The lens made of plastic material can reduce the weight of the optical system 100 and the production cost, and the light and thin design of the optical system 100 can be realized by matching with the small size of the optical system 100. The glass lens provides the optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 100 may be any combination of glass and plastic, and is not necessarily both glass and plastic.

It is to be noted that the first lens L1 does not mean that there is only one lens, and in some embodiments, there may be two or more lenses in the first lens L1, and the two or more lenses can form a cemented lens, and a surface of the cemented lens closest to the object side can be regarded as the object side surface S1, and a surface of the cemented lens closest to the image side can be regarded as the image side surface S2. Alternatively, although no cemented lens is formed between the lenses of the first lens L1, the distance between the lenses is relatively fixed, and in this case, the object-side surface of the lens closest to the object side is the object-side surface S1, and the image-side surface of the lens closest to the image side is the image-side surface S2. In addition, the number of lenses in the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 or the seventh lens L7 in some embodiments may be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, or a non-cemented lens may be used.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: CT16/BL is more than or equal to 0.24 and less than or equal to 0.28; the CT16 is a distance between the object-side surface S1 of the first lens L1 and the image-side surface S6 of the third lens L3 on the optical axis 110, and the BL is a distance between the object-side surface S1 of the first lens L1 and the image-side surface S14 of the seventh lens L7 on the optical axis 110. Specifically, CT16/BL may be: 0.250, 0.252, 0.255, 0.257, 0.265, 0.268, 0.271, 0.274, 0.275, or 0.278. When the conditional expressions are satisfied, the ratio of the lengths of the first three lenses on the optical axis 110 to the length of the seven lenses on the optical axis 100 can be reasonably configured, which is beneficial to fully compressing the effective calibers of the first lens L1, the second lens L2 and the third lens L3, namely fully compressing the front end calibre of the optical system 100, thereby being beneficial to the appearance design of a small head, and further reducing the opening size of a display screen when the optical system 100 is applied to under-screen shooting so as to satisfy the requirement of high screen ratio of electronic equipment; in addition, the total length of the optical system 100 is shortened, so that the visual angle range of the optical system 100 is enlarged, and the optical system 100 can obtain a more comprehensive scene. Below the lower limit of the above conditional expression, the thicknesses and gaps of the first lens L1, the second lens L2, and the third lens L3 are too small to facilitate the processing and assembling of the lenses. Beyond the upper limit of the above conditional expression, the total length of the front lens group formed by the first lens L1, the second lens L2 and the third lens L3 is too large, which results in too large exit angle of the chief ray of the light entering the image plane, so that the marginal rays of the image plane cannot be imaged normally, and the imaging information is incomplete.

In some embodiments, the optical system 100 satisfies the conditional expression: 0.13mm^-1≤tan(HFOV)/TTL≤0.15mm^-1(ii) a The HFOV is half of the maximum field angle of the optical system 100, and the TTL is the distance from the object-side surface S1 of the first lens L1 to the image plane of the optical system 100 on the optical axis 110. Specifically, tan (hfov)/TTL may be: 0.132, 0.133, 0.134, 0.135, 0.136, 0.137, 0.138, 0.139, 0.140 or 0.142, the numerical units being mm^-1. When the above conditional expressions are satisfied, the optical total length and the maximum field angle of the optical system 100 can be reasonably configured, which is beneficial to shortening the total length of the optical system 100, realizing a miniaturized design, and simultaneously enabling the optical system 100 to have a large-view angle characteristic, so that more scene contents can be acquired, and imaging information of the optical system 100 is enriched. Below the lower limit of the above conditional expression, the total length of the optical system 100 is too large, which is disadvantageous for the miniaturized design of the optical system 100; exceeding the upper limit of the above conditional expression makes the structure of the optical system 100 too compact, which makes aberration correction difficult, and thus tends to cause a decrease in imaging performance.

In some embodiments, the optical system 100 satisfies the conditional expression: 1.5mm^-1≤FNO/SD11≤2mm^-1(ii) a Wherein FNO is the f-number of the optical system 100, and SD11 is half of the maximum effective aperture of the object-side surface S1 of the first lens L1. Specifically, FNO/SD11 may be: 1.531, 1.545, 1.568, 1.593, 1.655, 1.693, 1.741, 1.785, 1.806 or 1.886, the numerical units being mm. When the above conditional expressions are satisfied, it is advantageous for the optical system 100 to realize a large aperture characteristic, thereby increasing the light incident amount of the optical system 100, and allowing the optical system 100 to operate at low light intensityThe optical system 100 can have good imaging quality under the environment, and simultaneously has better blurring effect, so that the requirement of high imaging quality is met; in addition, it is advantageous to fully compress the object side effective aperture of the first lens L1, thereby facilitating implementation of a small head design. Below the lower limit of the above conditional expression, the effective aperture of the object-side surface S1 of the first lens L1 is not sufficiently compressed, which is not favorable for the small head design of the optical system 100, and the marginal rays are not reasonably intercepted, which results in increased field curvature and formation of a marginal distortion image, thereby resulting in a reduction in imaging quality; exceeding the upper limit of the above conditional expression, the effective aperture of the object-side surface S1 of the first lens L1 is too small, which is disadvantageous for enlarging the aperture of the optical system 100, resulting in insufficient light flux and difficulty in satisfying the requirement of high image quality.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/ImgH is more than or equal to 1.1 and less than or equal to 1.22; wherein, TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110, and ImgH is half of the image height corresponding to the maximum field angle of the optical system 100. Specifically, TTL/ImgH may be: 1.158, 1.167, 1.176, 1.182, 1.187, 1.903, 1.928, 1.993, 1.205, or 1.215. When the above conditional expressions are satisfied, the ratio of the total optical length to the half-image height of the optical system 100 can be reasonably configured, which is beneficial to shortening the total optical length of the optical system 100, thereby realizing the miniaturization design, and simultaneously, is also beneficial to the optical system 100 having the large image plane characteristic, thereby enabling the optical system 100 to be matched with the photosensitive element with larger size, so as to obtain high resolution, and further considering the miniaturization design of the optical system 100 and the realization of high imaging quality. If the upper limit of the above conditional expression is exceeded, the image height of the optical system 100 is too small to match with a photosensitive element with a larger size, which is not favorable for improving the imaging quality of the optical system 100; meanwhile, the overall length of the optical system 100 is too large, which is not favorable for the miniaturization design of the optical system 100; below the lower limit of the above conditional expression, the total length of the optical system 100 is too small, the arrangement of the lenses is crowded, which is not favorable for aberration correction, and the telephoto imaging quality is also not good.

It should be noted that in some embodiments, the optical system 100 may match a photosensitive element having a rectangular photosensitive surface, and the imaging surface of the optical system 100 coincides with the photosensitive surface of the photosensitive element. At this time, the effective pixel region on the imaging plane of the optical system 100 has a horizontal direction and a diagonal direction, the maximum angle of view can be understood as the maximum angle of view in the diagonal direction of the optical system 100, and ImgH can be understood as a half of the length of the effective pixel region on the imaging plane of the optical system 100 in the diagonal direction.

In some embodiments, the optical system 100 satisfies the conditional expression: 0.75-0.85 (ET1+ ET2+ ET3)/(CT1+ CT2+ CT 3); ET1 is the edge thickness of the first lens element L1, ET2 is the edge thickness of the second lens element L2, ET3 is the edge thickness of the third lens element L3, CT1 is the thickness of the first lens element L1 along the optical axis 110, CT2 is the thickness of the second lens element L2 along the optical axis 110, and CT3 is the thickness of the third lens element L3 along the optical axis 110. Specifically, (ET1+ ET2+ ET3)/(CT1+ CT2+ CT3) may be: 0.769, 0.772, 0.775, 0.781, 0.793, 0.798, 0.804, 0.813, 0.817, or 0.826. When the above conditional expressions are satisfied, the center thicknesses of the first lens element L1, the second lens element L2, and the third lens element L3 are prevented from being too thin relative to the edge thicknesses, so as to prevent the insufficient refractive power of the front lens assembly formed by the first lens element L1, the second lens element L2, and the third lens element L3, and further enable the front lens assembly to effectively deflect light and correct the aberration of the optical system 100; meanwhile, the center thicknesses of the first lens L1, the second lens L2 and the third lens L3 can be prevented from being too thick relative to the edge thicknesses, so that the surface shapes of the first lens L1, the second lens L2 and the third lens L3 are not too curved, and the design and the manufacture of the first lens L1, the second lens L2 and the third lens L3 are facilitated. When the upper limit of the above conditional expressions is exceeded, the center thicknesses of the first lens element L1, the second lens element L2 and the third lens element L3 are too thin relative to the edge thicknesses, which results in insufficient refractive power of the front lens element, is not favorable for deflecting light rays and correcting aberrations of the optical system 100, and also results in too large curvature of field. If the thickness is lower than the lower limit of the above conditional expression, the center thicknesses of the first lens L1, the second lens L2, and the third lens L3 are too thick compared to the edge thicknesses, which causes the surface shapes of the first lens L1, the second lens L2, and the third lens L3 to be too curved, thereby reducing the molding yield of the first lens L1, the second lens L2, and the third lens L3.

In some embodiments, the optical system 100 satisfies the conditional expression: the total ratio of SAG 51/CT 5 is more than or equal to 1.3 and less than or equal to 1.8; SAG51 is the rise of the object-side surface S1 of the fifth lens L5 at the maximum effective aperture, and CT5 is the thickness of the fifth lens L5 on the optical axis 110. Specifically, | SAG51|/CT5 may be: 1.353, 1.374, 1.402, 1.412, 1.457, 1.539, 1.554, 1.587, 1.632, or 1.742. When the conditional expressions are satisfied, the shape of the object-side surface S9 of the fifth lens L5 can be reasonably configured, so that the surface shape of the object-side surface S9 of the fifth lens L5 at the position close to the circumference is not excessively bent, thereby facilitating the manufacturing and molding of the lens and reducing the defect of poor molding; meanwhile, the surface shape of the object side surface S9 of the fifth lens L5 near the circumference is not too smooth, so that the field curvature generated by each lens of the object side can be corrected, the field curvatures of different fields tend to be balanced, the image quality of the imaging picture of the whole optical system 100 is uniform, and the imaging quality of the optical system 100 is improved. Below the lower limit of the above conditional expression, the surface shape of the object-side surface S9 of the fifth lens L5 near the circumference is too smooth, which results in insufficient deflecting capability of the fifth lens L5 for the off-axis field rays and is not favorable for correction of distortion and field curvature aberration; exceeding the upper limit of the conditional expression, the object-side surface S9 of the fifth lens L5 is excessively curved in the shape of a surface near the circumference, which tends to cause poor molding of the fifth lens L5, and thus the manufacturing yield is affected.

In some embodiments, the optical system 100 satisfies the conditional expression: (R41-R42)/(R41+ R42) is not more than 0.6 and not more than 1; wherein R41 is a radius of curvature of the object-side surface S7 of the fourth lens element L4 along the optical axis 110, and R42 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 along the optical axis 110. Specifically, (R41-R42)/(R41+ R42) may be: 0.670, 0.685, 0.703, 0.728, 0.754, 0.789, 0.823, 0.846, 0.897, or 0.976. When the conditional expressions are satisfied, the surface types of the object side surface S7 and the image side surface S8 of the fourth lens L4 can be reasonably configured, so that the surface types of the object side surface S7 and the image side surface S8 of the fourth lens L4 are not too smooth or excessively curved, thereby being beneficial to balancing the optical path difference of the light rays of the central field of view and the peripheral field of view in the optical system 100, preventing the optical path difference of the central field of view and the peripheral field of view from being too large, further promoting the light rays of the central field of view and the peripheral field of view to converge to the vicinity of the same plane, and being beneficial to correcting the curvature of field of the optical system 100; in addition, the center of the fourth lens L4 is prevented from being too thin and too thick compared with the edge, so that the precision requirement of production and processing is met, and the forming yield is ensured.

In some embodiments, the optical system 100 satisfies the conditional expression: f1/f is more than or equal to 1 and less than or equal to 1.2; where f1 is the effective focal length of the first lens L1, and f is the effective focal length of the optical system 100. Specifically, f1/f may be: 1.022, 1.037, 1.042, 1.048, 1.077, 1.098, 1.123, 1.138, 1.149, or 1.155. When the above conditional expressions are satisfied, the refractive power ratio of the first lens element L1 in the optical system 100 can be reasonably configured, so that the first lens element L1 can provide sufficient positive refractive power for the optical system 100, which is beneficial to the convergence of light rays, thereby realizing the miniaturized design of the optical system 100; meanwhile, the over-strong positive refractive power of the first lens element L1 can be avoided, so that the second lens element L2 and the third lens element L3 are facilitated to correct the aberration generated by the first lens element L1, the imaging quality of the optical system 100 is improved, the excessive curvature of the surface shape of the first lens element L1 is prevented, and the manufacturing and molding of the first lens element L1 are facilitated. Above the upper limit of the above conditional expression, the first lens element L1 provides insufficient positive refractive power for the optical system 100, which results in a decrease in light collecting capability of the optical system 100 and is not favorable for the miniaturization design of the optical system 100. Below the lower limit of the conditional expression, the positive refractive power provided by the first lens element L1 for the optical system 100 is too strong, which is not favorable for the second lens element L2 and the third lens element L3 to correct the aberration generated by the first lens element L1, thereby reducing the imaging quality of the optical system 100, and meanwhile, the surface shape of the first lens element L1 is too curved, which is not favorable for the molding of the first lens element L1, thereby reducing the manufacturing yield of the first lens element L1.

In some embodiments, the optical system 100 satisfies the conditional expression: HFOV is more than or equal to 46 deg; the HFOV is half of the maximum field angle of the optical system 100. The wide-angle shooting of the optical system 100 is facilitated, and the requirement of large-range shooting is met.

The reference wavelengths for the above effective focal length values are all 587.5618 nm.

Based on the above description of the embodiments, more specific embodiments and drawings are set forth below for detailed description.

First embodiment

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of the optical system 100 in the first embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with negative refractive power, and a seventh lens element L7 with negative refractive power. Fig. 2 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment, sequentially from left to right, wherein the reference wavelength of the astigmatism graph and the distortion graph is 587.5618nm, and the other embodiments are the same.

The object-side surface S1 of the first lens element L1 is convex at the paraxial region 110, and the image-side surface S2 is concave at the paraxial region 110;

the object-side surface S3 of the second lens element L2 is convex at the paraxial region 110, and the image-side surface S4 is concave at the paraxial region 110;

the object-side surface S5 of the third lens element L3 is convex at the paraxial region 110, and the image-side surface S6 is concave at the paraxial region 110;

the object-side surface S7 of the fourth lens element L4 is concave at the paraxial region 110, and the image-side surface S8 is convex at the paraxial region 110;

the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110, and the image-side surface S10 is concave at the paraxial region 110;

the object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 110, and the image-side surface S12 is concave at the paraxial region 110;

the object-side surface S13 of the seventh lens element L7 is convex at the paraxial region 110, and the image-side surface S14 is concave at the paraxial region 110.

The object-side surface and the image-side surface of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are aspheric.

It should be noted that, in the present application, when a surface of the lens is described as being convex at a position near the optical axis 110 (the central region of the surface), it is understood that the region of the surface of the lens near the optical axis 110 is convex.

The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are all made of plastic.

Further, the optical system 100 satisfies the conditional expression: CT16/BL is 0.277; the CT16 is a distance between the object-side surface S1 of the first lens L1 and the image-side surface S6 of the third lens L3 on the optical axis 110, and the BL is a distance between the object-side surface S1 of the first lens L1 and the image-side surface S14 of the seventh lens L7 on the optical axis 110. When the conditional expressions are satisfied, the ratio of the lengths of the first three lenses on the optical axis 110 to the length of the seven lenses on the optical axis 100 can be reasonably configured, which is beneficial to fully compressing the effective calibers of the first lens L1, the second lens L2 and the third lens L3, namely fully compressing the front end calibre of the optical system 100, thereby being beneficial to the appearance design of a small head, and further reducing the opening size of a display screen when the optical system 100 is applied to under-screen shooting so as to satisfy the requirement of high screen ratio of electronic equipment; in addition, the total length of the optical system 100 is shortened, so that the visual angle range of the optical system 100 is enlarged, and the optical system 100 can obtain a more comprehensive scene.

The optical system 100 satisfies the conditional expression: tan (HFOV)/TTL 0.132mm^-1(ii) a The HFOV is half of the maximum field angle of the optical system 100, and the TTL is the distance from the object-side surface S1 of the first lens L1 to the image plane of the optical system 100 on the optical axis 110. When the above conditional expressions are satisfied, the optical total length and the maximum field angle of the optical system 100 can be reasonably configured, which is beneficial to shortening the total length of the optical system 100, realizing a miniaturized design, and simultaneously enabling the optical system 100 to have a large-view angle characteristic, so that more scene contents can be acquired, and imaging information of the optical system 100 is enriched.

The optical system 100 satisfies the conditional expression: FNO/SD11 ═ 1.531mm^-1(ii) a Wherein FNO is the f-number of the optical system 100, and SD11 is half of the maximum effective aperture of the object-side surface S1 of the first lens L1. When the above conditional expressions are satisfied, it is advantageous for the optical system 100 to realize a large aperture characteristic, thereby increasing the light incident amount of the optical system 100 and enabling the optical system to have a large aperture characteristicThe system 100 can have good imaging quality in a low-light environment, and meanwhile, the optical system 100 can have a better blurring effect, so that the requirement of high imaging quality is met; in addition, it is advantageous to fully compress the object side effective aperture of the first lens L1, thereby facilitating implementation of a small head design.

The optical system 100 satisfies the conditional expression: TTL/ImgH is 1.158; wherein, TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110, and ImgH is half of the image height corresponding to the maximum field angle of the optical system 100. When the above conditional expressions are satisfied, the ratio of the total optical length to the half-image height of the optical system 100 can be reasonably configured, which is beneficial to shortening the total optical length of the optical system 100, thereby realizing the miniaturization design, and simultaneously, is also beneficial to the optical system 100 having the large image plane characteristic, thereby enabling the optical system 100 to be matched with the photosensitive element with larger size, so as to obtain high resolution, and further considering the miniaturization design of the optical system 100 and the realization of high imaging quality.

The optical system 100 satisfies the conditional expression: (ET1+ ET2+ ET3)/(CT1+ CT2+ CT3) 0.802; ET1 is the edge thickness of the first lens element L1, ET2 is the edge thickness of the second lens element L2, ET3 is the edge thickness of the third lens element L3, CT1 is the thickness of the first lens element L1 along the optical axis 110, CT2 is the thickness of the second lens element L2 along the optical axis 110, and CT3 is the thickness of the third lens element L3 along the optical axis 110. When the above conditional expressions are satisfied, the center thicknesses of the first lens element L1, the second lens element L2, and the third lens element L3 are prevented from being too thin relative to the edge thicknesses, so as to prevent the insufficient refractive power of the front lens assembly formed by the first lens element L1, the second lens element L2, and the third lens element L3, and further enable the front lens assembly to effectively deflect light and correct the aberration of the optical system 100; meanwhile, the center thicknesses of the first lens L1, the second lens L2 and the third lens L3 can be prevented from being too thick relative to the edge thicknesses, so that the surface shapes of the first lens L1, the second lens L2 and the third lens L3 are not too curved, and the design and the manufacture of the first lens L1, the second lens L2 and the third lens L3 are facilitated.

The optical system 100 satisfies the conditional expression: 1.353, | SAG51|/CT5 ═ 1.353; SAG51 is the rise of the object-side surface S1 of the fifth lens L5 at the maximum effective aperture, and CT5 is the thickness of the fifth lens L5 on the optical axis 110. When the conditional expressions are satisfied, the shape of the object-side surface S9 of the fifth lens L5 can be reasonably configured, so that the surface shape of the object-side surface S9 of the fifth lens L5 at the position close to the circumference is not excessively bent, thereby facilitating the manufacturing and molding of the lens and reducing the defect of poor molding; meanwhile, the surface shape of the object side surface S9 of the fifth lens L5 near the circumference is not too smooth, so that the field curvature generated by each lens of the object side can be corrected, the field curvatures of different fields tend to be balanced, the image quality of the imaging picture of the whole optical system 100 is uniform, and the imaging quality of the optical system 100 is improved.

The optical system 100 satisfies the conditional expression: (R41-R42)/(R41+ R42) ═ 0.976; wherein R41 is a radius of curvature of the object-side surface S7 of the fourth lens element L4 along the optical axis 110, and R42 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 along the optical axis 110. When the conditional expressions are satisfied, the surface types of the object side surface S7 and the image side surface S8 of the fourth lens L4 can be reasonably configured, so that the surface types of the object side surface S7 and the image side surface S8 of the fourth lens L4 are not too smooth or excessively curved, thereby being beneficial to balancing the optical path difference of the light rays of the central field of view and the peripheral field of view in the optical system 100, preventing the optical path difference of the central field of view and the peripheral field of view from being too large, further promoting the light rays of the central field of view and the peripheral field of view to converge to the vicinity of the same plane, and being beneficial to correcting the curvature of field of the optical system 100; in addition, the center of the fourth lens L4 is prevented from being too thin and too thick compared with the edge, so that the precision requirement of production and processing is met, and the forming yield is ensured.

The optical system 100 satisfies the conditional expression: f1/f is 1.094; where f1 is the effective focal length of the first lens L1, and f is the effective focal length of the optical system 100. When the above conditional expressions are satisfied, the refractive power ratio of the first lens element L1 in the optical system 100 can be reasonably configured, so that the first lens element L1 can provide sufficient positive refractive power for the optical system 100, which is beneficial to the convergence of light rays, thereby realizing the miniaturized design of the optical system 100; meanwhile, the over-strong positive refractive power of the first lens element L1 can be avoided, so that the second lens element L2 and the third lens element L3 are facilitated to correct the aberration generated by the first lens element L1, the imaging quality of the optical system 100 is improved, the excessive curvature of the surface shape of the first lens element L1 is prevented, and the manufacturing and molding of the first lens element L1 are facilitated.

In addition, the parameters of the optical system 100 are given in table 1. Among them, the image plane S17 in table 1 may be understood as an imaging plane of the optical system 100. The elements from the object plane (not shown) to the image plane S17 are sequentially arranged in the order of the elements from top to bottom in table 1. The Y radius in table 1 is the radius of curvature of the object-side or image-side surface at the optical axis 110 for the corresponding surface number. Surface numbers S1 and S2 denote an object-side surface S1 and an image-side surface S2 of the first lens L1, respectively, that is, in the same lens, a surface with a smaller surface number is an object-side surface, and a surface with a larger surface number is an image-side surface. The first numerical value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second numerical value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110.

Note that, in this embodiment and the following embodiments, the optical system 100 may not be provided with the infrared filter L8, but the distance from the image-side surface S14 of the seventh lens L7 to the image surface S17 is kept constant at this time.

In the first embodiment, the effective focal length f of the optical system 100 is 6.298mm, the total optical length TTL is 8mm, half of the maximum field angle HFOV is 46.56deg, and the f-number FNO is 2.2. The optical system 100 can satisfy a small head design while having a wide-angle characteristic and high imaging quality.

The reference wavelengths of the focal length, refractive index and abbe number of each lens are 587.5618nm, and the same applies to other embodiments.

TABLE 1

Further, aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are given by table 2. Wherein, the surface numbers from S1 to S14 represent the image side or the object side S1 to S14, respectively. And K-a20 from top to bottom respectively indicate the types of aspheric coefficients, where K indicates a conic coefficient, a4 indicates a quartic aspheric coefficient, a6 indicates a sextic aspheric coefficient, A8 indicates an octal aspheric coefficient, and so on. In addition, the aspherical surface coefficient formula is as follows:

wherein Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis 110, c is the curvature of the aspheric surface vertex, K is the conic coefficient, and Ai is the coefficient corresponding to the i-th high-order term in the aspheric surface type formula.

TABLE 2

In addition, fig. 2 includes a Longitudinal Spherical Aberration diagram (Longitudinal Spherical Aberration) of the optical system 100, which shows the deviation of the convergent focus of light rays of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the Normalized Pupil coordinate (Normalized Pupil coordinate) from the Pupil center to the Pupil edge, and the abscissa represents the focus offset, i.e. the distance (in mm) from the image plane to the intersection of the ray with the optical axis 110. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with different wavelengths in the first embodiment tend to be consistent, and the diffuse speckle or the chromatic halo in the imaging picture is effectively suppressed. Fig. 2 also includes an astigmatism plot (ASTIGMATIC FIELD CURVES) for the optical system 100, where the abscissa represents focus offset, the ordinate represents image height in mm, and the S-curve represents sagittal curvature of field at 587.5618nm and the T-curve represents meridional curvature of field at 587.5618 nm. As can be seen from the figure, the curvature of field of the optical system 100 is small, the curvature of field and astigmatism of each field are well corrected, and the center and the edge of the field have clear images. Fig. 2 further includes a DISTORTION plot (distorrion) of the optical system 100, where the DISTORTION plot represents DISTORTION magnitude values corresponding to different angles of view, where the abscissa represents DISTORTION value in mm and the ordinate represents image height in mm. As can be seen from the figure, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

Second embodiment

Referring to fig. 3 and 4, fig. 3 is a schematic structural diagram of the optical system 100 in the second embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 4 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment, which is shown from left to right.

In addition, the parameters of the optical system 100 are given in table 3, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 3

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 4, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 4

According to the provided parameter information, the following data can be deduced:

CT16/BL	0.250	(ET1+ET2+ET3)/(CT1+CT2+CT3)	0.826
				tan(HFOV)/TTL(mm^-1)	0.136	\|SAG51\|/CT5	1.444
FNO/SD11(mm^-1)	1.869	(R41-R42)/(R41+R42)	0.670
				TTL/ImgH	1.188	f1/f	1.070

in addition, as can be seen from the aberration diagram in fig. 4, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 5 and 6, fig. 5 is a schematic structural diagram of the optical system 100 in the third embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with negative refractive power, and a seventh lens element L7 with negative refractive power. Fig. 6 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, from left to right.

the object-side surface S5 of the third lens element L3 is convex at the paraxial region 110, and the image-side surface S6 is convex at the paraxial region 110;

In addition, the parameters of the optical system 100 are given in table 5, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein again.

TABLE 5

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 6, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 6

And, according to the above provided parameter information, the following data can be derived:

CT16/BL	0.267	(ET1+ET2+ET3)/(CT1+CT2+CT3)	0.811
				tan(HFOV)/TTL(mm^-1)	0.134	\|SAG51\|/CT5	1.713
FNO/SD11(mm^-1)	1.728	(R41-R42)/(R41+R42)	0.699
				TTL/ImgH	1.200	f1/f	1.026

in addition, as can be seen from the aberration diagram in fig. 6, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fourth embodiment

Referring to fig. 7 and 8, fig. 7 is a schematic structural diagram of the optical system 100 in the fourth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, and a seventh lens element L7 with negative refractive power. Fig. 8 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment, which is shown from left to right.

the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110, and the image-side surface S10 is convex at the paraxial region 110;

In addition, the parameters of the optical system 100 are given in table 7, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 7

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 8, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 8

CT16/BL	0.278	(ET1+ET2+ET3)/(CT1+CT2+CT3)	0.793
				tan(HFOV)/TTL(mm^-1)	0.133	\|SAG51\|/CT5	1.516
FNO/SD11(mm^-1)	1.730	(R41-R42)/(R41+R42)	0.765
				TTL/ImgH	1.215	f1/f	1.022

in addition, as can be seen from the aberration diagram in fig. 8, the longitudinal spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fifth embodiment

Referring to fig. 9 and 10, fig. 9 is a schematic structural diagram of the optical system 100 in the fifth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 10 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment from left to right.

In addition, the parameters of the optical system 100 are given in table 9, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 9

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 10, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

Watch 10

in addition, as can be seen from the aberration diagram in fig. 10, the longitudinal spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Referring to fig. 11, in some embodiments, the optical system 100 may be assembled with the photosensitive element 210 to form the image capturing module 200. At this time, the light-sensing surface of the light-sensing element 210 may be regarded as the image surface S17 of the optical system 100. The image capturing module 200 may further include an infrared filter L8, and the infrared filter L8 is disposed between the image side surface S14 and the image surface S17 of the seventh lens element L7. Specifically, the photosensitive element 210 may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) Device. By adopting the optical system 100 in the image capturing module 200, the image capturing module can have good imaging quality, realize small head design, has a large viewing angle characteristic, and can meet the requirement of large-range shooting.

Referring to fig. 11 and 12, in some embodiments, the image capturing module 200 may be applied to an electronic device 300, the electronic device includes a housing 310, and the image capturing module 200 is disposed in the housing 310. Specifically, the electronic apparatus 300 may be, but is not limited to, a wearable device such as a mobile phone, a video phone, a smart phone, an electronic book reader, a vehicle-mounted image capturing apparatus such as a car recorder, or a smart watch. In some embodiments, the image capturing module 200 is installed under the display screen of the electronic device 300 by using an opening hole under the display screen, and the electronic device 300 may be a full-screen device. Adopt above-mentioned module 200 of getting for instance in electronic equipment 300, get for instance module 200 possesses good imaging quality and can satisfy the demand of shooing on a large scale, possesses little head design simultaneously for electronic equipment 300 is favorable to promoting electronic equipment 300's screen when adopting the design of trompil under the screen and accounts for the ratio.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An optical system comprising, in order from an object side to an image side along an optical axis:

a fourth lens element with positive refractive power;

and the optical system satisfies the following conditional expression:

0.24≤CT16/BL≤0.28；

2. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.13mm^-1≤tan(HFOV)/TTL≤0.15mm^-1；

the HFOV is half of the maximum field angle of the optical system, and the TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis.

3. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.5mm^-1≤FNO/SD11≤2mm^-1；

wherein FNO is the f-number of the optical system, and SD11 is half of the maximum effective aperture of the object side surface of the first lens.

4. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.1≤TTL/ImgH≤1.22；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and ImgH is half of an image height corresponding to a maximum field angle of the optical system.

5. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.75≤(ET1+ET2+ET3)/(CT1+CT2+CT3)≤0.85；

ET1 is a distance from a maximum effective aperture of an object-side surface of the first lens element to a maximum effective aperture of an image-side surface of the first lens element in an optical axis direction, ET2 is a distance from a maximum effective aperture of an object-side surface of the second lens element to a maximum effective aperture of an image-side surface of the second lens element in the optical axis direction, ET3 is a distance from a maximum effective aperture of an object-side surface of the third lens element to a maximum effective aperture of an image-side surface of the third lens element in the optical axis direction, CT1 is a thickness of the first lens element in the optical axis direction, CT2 is a thickness of the second lens element in the optical axis direction, and CT3 is a thickness of the third lens element in the optical axis direction.

6. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.3≤|SAG51|/CT5≤1.8；

wherein SAG51 is the rise of the object side surface of the fifth lens at the maximum effective aperture, and CT5 is the thickness of the fifth lens on the optical axis.

7. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.6≤(R41-R42)/(R41+R42)≤1；

wherein R41 is a radius of curvature of an object-side surface of the fourth lens element at an optical axis, and R42 is a radius of curvature of an image-side surface of the fourth lens element at the optical axis.

8. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1≤f1/f≤1.2；

wherein f1 is the effective focal length of the first lens, and f is the effective focal length of the optical system.

9. An image capturing module, comprising a photosensitive element and the optical system of any one of claims 1 to 8, wherein the photosensitive element is disposed on an image side of the optical system.

10. An electronic device, comprising a housing and the image capturing module of claim 9, wherein the image capturing module is disposed on the housing.