CN114624868B

CN114624868B - Optical system, camera module and electronic equipment

Info

Publication number: CN114624868B
Application number: CN202210532602.6A
Authority: CN
Inventors: 邓嘉伟; 刘彬彬; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2022-05-17
Filing date: 2022-05-17
Publication date: 2022-09-13
Anticipated expiration: 2042-05-17
Also published as: CN114624868A

Abstract

The invention discloses an optical system, a camera module and electronic equipment. The optical system includes: the optical system comprises a first lens with positive refractive power, a second lens with negative refractive power, a third lens with refractive power, a fourth lens with refractive power, a fifth lens with refractive power, a sixth lens with refractive power and a seventh lens with negative refractive power, and the optical system satisfies the following relations: 5.4 °/mm < FOV/f <6.2 °/mm. According to the optical system provided by the embodiment of the invention, the imaging effect can be ensured while the characteristics of the long focus and the large aperture are met.

Description

Optical system, camera module and electronic equipment

Technical Field

The present invention relates to the field of photography imaging technologies, and in particular, to an optical system, a camera module, and an electronic device.

Background

With the wide application of mobile phones, tablet computers, unmanned planes, computers and other electronic products in life, various technological improvements are emerging. Among them, the improvement and innovation of the shooting effect of the camera lens in the improvement of the novel electronic product becomes one of the focuses of people's attention, and becomes an important content of the technology improvement, and how to ensure the imaging effect while satisfying the characteristics of the long focus and the large aperture becomes an important subject of the current lens research.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. To this end, the present application proposes, in a first aspect, an optical system capable of ensuring an imaging effect while satisfying a telephoto and a large aperture characteristic.

According to the optical system of the embodiment of the first aspect of the present application, the seven lens elements with refractive power sequentially include, 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 paraxial region; a second lens element with negative refractive power having a concave image-side surface at paraxial region; a third 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 fourth 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 fifth lens element with refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a sixth lens element with refractive power; the seventh lens element with negative refractive power has a concave image-side surface at a paraxial region.

In the optical system, the positive refractive power of the first lens and the convex surface design of the object side surface at the paraxial region are beneficial to the entrance of the incident light with large angle into the optical system and the effective convergence of the incident light; the negative refractive power of the second lens element can counteract the aberration generated by the first lens element with positive refractive power, and the concave surface design of the object side surface is also favorable for well correcting spherical aberration and axial chromatic aberration; the third lens element and the fourth lens element with refractive power are matched with the third lens element, the object-side surface and the image-side surface of the third lens element are respectively designed into a convex surface and a concave surface, the object-side surface and the image-side surface of the fourth lens element are respectively designed into a convex surface and a concave surface, which are beneficial to correcting the aberration of the optical system, the fifth lens element with refractive power is matched with the concave-convex surface design of the object-side surface and the image-side surface, which is beneficial to smooth transmission of light, and can balance the difficult-to-correct aberration brought by the front lens group (namely the first lens element to the fourth lens element) when converging incident light, reduce the correction pressure of the rear lens element (namely the sixth lens element and the seventh lens element), the sixth lens element with refractive power is matched with the seventh lens element with negative refractive power and the concave surface design of the image-side surface of the seventh lens element at the position close to the optical axis, so as to correct the aberration generated when the light passes through the fifth lens element, the optical system can reasonably deflect the light, can reduce the incident angle of the incident light on an imaging surface, reduces the generation of chromatic aberration, and improves the imaging quality of the optical system.

In one embodiment, 5.4 °/mm < FOV/f <6.2 °/mm; f is the effective focal length of the optical system, and the FOV is the maximum field angle of the optical system. The ratio of the maximum field angle of the optical system to the effective focal length of the optical system is in a reasonable range, so that the required field angle can be provided for the optical system, the telephoto characteristic of the optical system can be realized, and the optical system has high magnification to realize the telephoto effect. Meanwhile, the effective focal length of the optical system is kept in a reasonable interval, so that the optical system can hold more image capturing areas and the effective focal length of the optical system is not too short. The lower limit of the relational expression is lower, the required field angle cannot be reached, and the viewing area is influenced; exceeding the upper limit of the relational expression, the effective focal length of the optical system is too short, the optical system is too compact, the design difficulty is high, the surface type is easy to be distorted for multiple times, and the practical production is not facilitated.

The optical system also satisfies the relational condition: 3.2< FNO TTL/IMGH < 3.8; FNO is the f-number of the optical system; 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; IMGH is half the image height corresponding to the maximum field angle of the optical system. Satisfying the above relation, can making optical system obtain less f-number and bigger imaging plane to make optical system have enough light inlet quantity, under the shooting condition of dim light, obtain more scene content and abundant imaging information, optical system can keep the characteristics of less total size simultaneously. When FNO TTL/Imgh is not less than 3.8, the image height of the optical system is too small to be matched with a large-size image sensor, so that the imaging effect is influenced, and when FNO TTL/Imgh is not more than 3.2, the distance between the object side surface of the first lens and the imaging surface of the optical system is too small on the optical axis, the lens arrangement is crowded, and the aberration correction of the optical system is not facilitated.

The optical system also satisfies the relational condition: 10.5mm < f x fno <11.5 mm; f is the effective focal length of the optical system, and fno is the f-number of the optical system. Satisfying the above relational expression, through reasonably balancing f and fno, the optical system can satisfy the shooting performance of long focus and large aperture, exceeding the upper limit of the conditional expression, the f number is too large, the aperture is too small, the visual range is narrowed, the requirement of large-range shooting is difficult to satisfy, the dark angle phenomenon is easy to generate due to insufficient light flux, and meanwhile, the effective focal length of the optical system is too long and the shooting field of view is difficult to expand; be less than the lower limit of conditional expression, the diaphragm number undersize, the light ring is too big, is unfavorable for the control of light to be unfavorable for the promotion of image quality, optical system's effective focal length is also little this moment, leads to optical system can not shoot distant scenery.

The optical system also satisfies the relational condition: 17.5mm < f/tan (hfov) <20 mm; f is the effective focal length of the optical system, and the HFOV is half of the maximum field angle of the optical system. When the conditional expression is met, the optical system has a long-focus characteristic, and can effectively highlight the focusing main body and weaken the background during telephoto, so that the telephoto performance is improved; meanwhile, the field angle of the optical system is favorably expanded, so that the optical system has a long-focus characteristic and cannot be too small, and the shooting field range is increased; and is also advantageous for the miniaturized design of the optical system. Exceeding the upper limit of the above conditional expression, the effective focal length of the optical system is too long, resulting in that the total length of the optical system is difficult to compress, which is not beneficial to the realization of miniaturization design, and thus is not beneficial to the application of the optical system in portable electronic equipment; being lower than the lower limit of the above conditional expression, the effective focal length of the optical system is too short, and the detail reduction degree of the shot distant object is poor, so that the telephoto requirement is difficult to meet.

The optical system also satisfies the relational condition: -24< (R51+ R52)/TTL < -3.5; r51 is a curvature radius of an object-side surface of the fifth lens element, R52 is a curvature radius of an image-side surface of the fifth lens element, and TTL is a distance between the object-side surface of the first lens element and an image plane of the optical system. It should be noted that the curvature radius at the optical axis reflects the change of the central surface type of the object-side surface or the image-side surface of the lens, and the above relation is satisfied, so that the bending radians of the object-side surface and the image-side surface of the fifth lens are both in a reasonable range, the aberration can be reduced well, and the ghost image can be eliminated and the tolerance sensitivity of the fifth lens can be reduced.

The optical system also satisfies the relational condition: 1.5< (CT23+ CT34+ CT45+ CT56+ CT67)/BFL < 6; CT23 is an axial distance between an image-side surface of the second lens element and an object-side surface of the third lens element, CT34 is an axial distance between the image-side surface of the third lens element and an object-side surface of the fourth lens element, CT45 is an axial distance between the image-side surface of the fourth lens element and an object-side surface of the fifth lens element, CT56 is an axial distance between the image-side surface of the fifth lens element and an object-side surface of the sixth lens element, CT67 is an axial distance between the image-side surface of the sixth lens element and an object-side surface of the seventh lens element, and BFL is a minimum axial distance between the image-side surface of the seventh lens element and an image plane. Satisfying above-mentioned relational expression, can making optical system's second lens to seventh lens arrange to have great flexibility, can effective control lens's interval and obtain great back focal distance, can satisfy miniaturized while, reduce optical system's the equipment degree of difficulty.

The optical system further satisfies the relational condition: 0.2< | f12/f67| < 3; f12 is the combined focal length of the first and second lenses, and f67 is the combined focal length of the sixth and seventh lenses. Referring to fig. 1, it can be seen that the object-side surface and the image-side surface of the first lens element, the object-side surface and the image-side surface of the second lens element are relatively flat, the object-side surface and the image-side surface of the sixth lens element, and the object-side surface and the image-side surface of the seventh lens element have a plurality of inflection points, which satisfy the above relations, and by reasonably distributing the focal powers of f12 and f67, the aberration of the optical system can be compensated well, and even under different conditions, the light beams of different fields of view can be reasonably deflected, so that the full-field image quality resolving power of the optical system is improved.

The optical system also satisfies the relational condition: 5< | R72/SAG72| < 60; r72 is a radius of curvature of the image-side surface of the seventh lens element, and SAG72 is a rise of the image-side surface of the seventh lens element at the maximum effective aperture, i.e., a horizontal displacement amount from an intersection point of the image-side surface of the seventh lens element on the optical axis to a position of the maximum effective half aperture of the image-side surface of the seventh lens element in a direction parallel to the optical axis (the horizontal displacement amount is defined as positive toward the image-side direction and negative toward the object-side direction). The relational expression is satisfied, the increase of aberrations such as field curvature, astigmatism and the like can be effectively relieved by reasonably controlling R72 and SAG72, the requirements on the production process are reduced, and the yield is improved.

The optical system also satisfies the relational condition: 0.01< CT56/TTL < 0.05; CT56 is the distance on the optical axis from the image-side surface of the fifth lens element to the object-side surface of the sixth lens element; TTL is the distance on the optical axis from the object-side surface of the first lens element to the image plane of the optical system. The aberration of the optical system can be effectively balanced by reasonably configuring the distance between the fifth lens and the sixth lens, and meanwhile, the total length TTL of the optical system is reasonably controlled, so that the assembly of the optical system is facilitated, and the resolution of the optical system on images is improved.

The optical system also satisfies the relational condition: 0.5< (| SAG71| + | SAG72|)/CT7< 3; SAG71 is the saggital height of the object-side surface of the seventh lens at the maximum effective aperture, SAG72 is the saggital height of the image-side surface of the seventh lens at the maximum effective aperture, and CT7 is the thickness of the seventh lens on the optical axis. The surface type of the object side surface and the surface type of the image side surface of the seventh lens are effectively controlled by satisfying the relational expression, so that the thickness of the seventh lens is effectively controlled, the aberration generated in the transmission process of light rays can be effectively compensated, and the sensitivity of an optical system is reduced.

The optical system also satisfies the relational condition: 0.1< | SAG62/SD62| < 0.5; SAG62 is the sagittal height of the image side surface of the sixth lens at the maximum effective aperture, and SD62 is half the maximum effective aperture of the image side surface of the sixth lens. Satisfying the above relation, by reasonably distributing the surface type and the focal power of the image side surface of the sixth lens, it is helpful to correct the aberration generated by the front lens group (the first lens to the fifth lens), and in addition, by reasonably distributing the outer diameter and the thickness of the sixth lens, the incident angle of the light on the subsequent imaging lens can be reduced, and the sensitivity of the optical system can be reduced.

The optical system also satisfies the relational condition: 0.5< (ET1+ ET2+ ET3)/(CT1+ CT2+ CT3) <0.7, wherein ET1 is the distance from the maximum effective clear aperture of the object side surface to the maximum effective clear aperture of the image side surface of the first lens in the optical axis direction; ET2 is the distance from the maximum effective light-transmitting aperture of the object side surface of the second lens to the maximum effective light-transmitting aperture of the image side surface in the optical axis direction; ET3 is the distance from the maximum effective clear aperture of the object side surface to the maximum effective clear aperture of the image side surface of the third lens in the optical axis direction; CT1 is the thickness of the first lens on the optical axis; CT2 is the thickness of the second lens on the optical axis; CT3 is the thickness of the third lens element on the optical axis. The side thickness of the lens group formed by combining the first lens to the third lens in the optical system (namely ET1+ ET2+ ET3) is smaller than the middle thickness of the lens group formed by combining the first lens to the third lens (namely CT1+ CT2+ CT3), so that the whole lens group can be used as a positive lens, the light can be deflected towards the center of the optical system, the whole change is smooth, the introduction amount of aberration is small, the design of a subsequent lens is facilitated, and the process difficulty and tolerance sensitivity are reduced.

The image pickup module according to the embodiment of the second aspect of the present application includes an image sensor and the optical system described in any one of the above, where the image sensor is disposed on an image side of the optical system. Through adopting above-mentioned optical system, the module of making a video recording can guarantee the formation of image effect when satisfying long burnt and big light ring characteristic.

According to the electronic equipment of the embodiment of the third aspect of the application, the electronic equipment comprises a fixing piece and the camera module, and the camera module is arranged on the fixing piece. Above-mentioned module of making a video recording can guarantee the formation of image effect when satisfying long burnt and big light ring characteristic.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

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

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

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

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

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

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

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

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

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

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

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

fig. 12 is a schematic structural diagram of an image capturing apparatus according to an embodiment of the present application.

Reference numerals:

an optical system 10, a camera module 20, an electronic device 30,

the optical axis 101, the optical filter 110, the image sensor 210, the fixing member 310,

an aperture stop STO, a vignetting stop ST1,

first lens L1: object side S1, like side S2;

second lens L2: object side S3, like side S4;

third lens L3: object side S5, like side S6;

fourth lens L4: object side S7, like side S8;

fifth lens L5: object side S9, like side S10;

sixth lens L6: object side S11, like side S12;

seventh lens L7: object side S13, like side S14;

the filter 110: object side S15, like side S16;

image forming surface S17.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative and intended to explain the present invention and should not be construed as limiting the present invention.

An optical system 10 according to one embodiment of the present invention will be described below with reference to the drawings.

Referring to fig. 1, an embodiment of the present application provides an optical system 10 with a seven-lens design, where the optical system 10 includes 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 or negative refractive power, a fourth lens element L4 with positive or negative refractive power, a fifth lens element L5 with positive or negative refractive power, a sixth lens element L6 with positive or negative refractive power, and a seventh lens element L7 with negative refractive power. Each lens in the optical system 10 should be coaxially disposed, and each lens can be mounted in a lens barrel to form an imaging lens.

The first lens L1 has an object side surface S1 and an image side surface S2, the second lens L2 has an object side surface S3 and an image side surface S4, the third lens L3 has an object side surface S5 and an image side surface S6, the fourth lens L4 has an object side surface S7 and an image side surface S8, the fifth lens L5 has an object side surface S9 and an image side surface S10, the sixth lens L6 has an object side surface S11 and an image side surface S12, and the seventh lens L539 7 has an object side surface S13 and an image side surface S14. Meanwhile, the optical system 10 further has an image plane S17, the image plane S17 is located on the image side of the seventh lens element L7, and light rays emitted from an on-axis object point at a corresponding object distance can be modulated by the lenses of the optical system 10 to form an image on the image plane S17, and further, the optical system 10 further has a filter 110, the filter 110 is located between the image side surface S14 and the image plane S17 of the seventh lens element L7, and the filter 110 has an object side surface S15 and an image side surface S16.

Generally, the imaging surface S17 of the optical system 10 coincides with the light-sensing surface of the image sensor. It should be noted that in some embodiments, the optical system 10 may match a photosensitive surface with a rectangular image sensor, and the imaging surface S17 of the optical system 10 coincides with the rectangular photosensitive surface of the image sensor. At this time, the effective pixel area on the imaging surface S17 of the optical system 10 has a horizontal direction, a vertical direction and a diagonal direction, the maximum field angle of the optical system 10 in this application can be understood as the maximum field angle of the optical system 10 in the diagonal direction, and the IMGH can be understood as the length of the effective pixel area on the imaging surface S17 of the optical system 10 in the diagonal direction, that is, the image height corresponding to the maximum field angle of the optical system 10.

In the embodiment of the present application, the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is convex or concave at the paraxial region 101; the object-side surface S3 of the second lens element L2 can be convex or concave at the paraxial region 101, and the image-side surface S4 is concave at the paraxial region 101; the object-side surface S5 of the third lens element L3 is convex at the paraxial region 101, and the image-side surface S6 is concave at the paraxial region 101; the object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 101, and the image-side surface S8 is concave at the paraxial region 101; the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 101, and the image-side surface S10 is convex at the paraxial region 101; the object-side surface S11 of the sixth lens element L6 may be convex or concave at the paraxial region 101, and the image-side surface S12 may be convex or concave at the paraxial region 101; the object-side surface S13 of the seventh lens element L7 may be convex or concave at the paraxial region 101, and the image-side surface S14 is concave at the paraxial region 101. When describing that the lens surface has a certain profile at the paraxial region 101, that is, the lens surface has such a profile in the vicinity of the paraxial region 101; when it is described that the lens surface has a certain profile at the circumference, i.e. the lens surface has such a profile in the radial direction and close to the circumference.

In the optical system 10, the positive refractive power of the first lens element L1 and the convex design of the object-side surface S1 at the position near the optical axis 101 facilitate the entrance of the incident light with large angle into the optical system 10 and the effective convergence; the negative refractive power of the second lens element L2 can counteract the aberration generated by the first lens element L1 with positive refractive power, and the concave surface design of the image side surface S4 is also favorable for well correcting spherical aberration and on-axis chromatic aberration; the third lens element L3 and the fourth lens element L4 with refractive power, in combination with the surface type design that the object-side surface S5 and the image-side surface S6 of the third lens element L3 are respectively convex and concave, and the surface type design that the object-side surface S7 and the image-side surface S8 of the fourth lens element L4 are respectively convex and concave, are favorable for correcting the aberration of the optical system 10, the fifth lens element L5 with refractive power, in combination with the concave-convex surface type design that the object-side surface S9 and the image-side surface S10 are favorable for smooth light transmission, and can balance the aberration that is hard to correct when the front lens group (i.e. the first lens element L1 to the fourth lens element L4) converges incident light, reduce the correction pressure of the rear lens element (i.e. the sixth lens element L6 and the seventh lens element L7), the sixth lens element L6 with refractive power, in combination with the seventh lens element L7 with negative refractive power and the concave surface type design that the side surface of the seventh lens element L7 is at the paraxial region 101, the aberration generated when the light passes through the fifth lens L5 can be corrected, the light can be reasonably deflected, the incident angle of the incident light on the imaging surface S17 can be reduced, the generation of chromatic aberration is reduced, and the imaging quality of the optical system 10 is improved.

In the examples of the present application, 5.4 °/mm < FOV/f <6.2 °/mm; f is the effective focal length of the optical system 10, and the FOV is the maximum field angle of the optical system 10; specifically, FOV/f may be: 5.451 °/mm, 5.503 °/mm, 5.512 °/mm, 5.522 °/mm, 5.768 °/mm, 5.919 °/mm, 6.076 °/mm, 6.131 °/mm, 6.153 °/mm, 6.198 °/mm. Satisfying the above relational expression, by making the ratio of the maximum field angle of the optical system 10 to the effective focal length of the optical system 10 in a reasonable range, the required field angle can be provided for the optical system 10, which is beneficial to realizing the telephoto characteristic of the optical system 10, so that the optical system has a higher magnification to realize the telephoto effect. Meanwhile, the effective focal length of the optical system 10 is kept in a reasonable interval, which is beneficial for the optical system 10 to accommodate more image capture areas while the effective focal length of the optical system 10 is not too short. The lower limit of the relational expression is lower, the required field angle cannot be reached, and the viewing area is influenced; exceeding the upper limit of the relation, the effective focal length of the optical system 10 is too short, the optical system 10 is too compact, the design difficulty is high, the surface shape is easy to be distorted for many times, and the actual production is not facilitated.

The optical system 10 also satisfies the relational condition: 3.2< FNO TTL/IMGH < 3.8; FNO is the f-number of the optical system 10; TTL is the distance from the object-side surface S1 of the first lens element L1 to the image plane S17 of the optical system 10 on the optical axis 101; IMGH is half the image height corresponding to the maximum field angle of the optical system 10. Specifically, FNO × TTL/IMGH may be: 3.259, 3.315, 3.401, 3.489, 3.558, 3.637, 3.665, 3.701, 3.755, 3.766. Satisfying the above relation, the optical system 10 can obtain a smaller f-number and a larger imaging surface S17, so that the optical system 10 can have a sufficient light input amount, acquire more scene contents and rich imaging information under the shooting condition of dark light, and simultaneously the optical system 10 can maintain the characteristic of a smaller overall size. When FNO × TTL/Imgh is not less than 3.8, the image height of the optical system 10 is too small to match with a large-sized image sensor, thereby affecting the imaging effect, and when FNO × TTL/Imgh is not more than 3.2, the distance from the object-side surface S1 of the first lens L1 to the imaging surface S17 of the optical system 10 on the optical axis 101 is too small, the lens arrangement is crowded, and aberration correction of the optical system 10 is not facilitated.

The optical system 10 also satisfies the relational condition: 10.5mm < f x fno <11.5 mm; f is the effective focal length of the optical system 10, and fno is the f-number of the optical system 10. Specifically, f × fno may be: 10.521mm, 10.545mm, 10.655mm, 10.736mm, 10.785mm, 10.936mm, 11.084mm, 11.343mm, 11.400mm or 11.490 mm. Satisfying the above relational expression, by reasonably balancing f and fno, the optical system 10 can satisfy the shooting performance of both long focus and large aperture, exceeding the upper limit of the conditional expression, the aperture is too large, the aperture is too small, resulting in a reduced visible range, which is difficult to satisfy the requirement of large-range shooting, and is also easy to generate a dark angle phenomenon due to insufficient light transmission, and at the same time, the effective focal length of the optical system 10 is too long to enlarge the shooting field of view; be less than the lower limit of conditional expression, the f-number undersize, the diaphragm is too big, is unfavorable for the control of light to be unfavorable for the promotion of image quality, optical system 10's effective focal length is also little this moment, leads to optical system 10 can not shoot the scenery far away.

The optical system 10 also satisfies the relational condition: 17.5mm < f/tan (hfov) <20 mm; f is the effective focal length of the optical system 10 and the HFOV is half the maximum field angle of the optical system 10. Specifically, f/tan (hfov) may be: 17.581mm, 17.651mm, 17.75mm, 17.984mm, 18.249mm, 18.523mm, 18.752mm, 19.125mm, 19.637mm, 19.966 mm. When the above conditional expressions are satisfied, the optical system 10 has a telephoto characteristic, and can effectively highlight the focusing main body and blur the background during telephoto shooting, thereby improving the telephoto performance; meanwhile, the field angle of the optical system 10 is advantageously enlarged, so that the field angle of the optical system 10 is not too small while having the telephoto characteristic, thereby increasing the shooting field range; and also contributes to the compact design of the optical system 10. Exceeding the upper limit of the above conditional expression, the effective focal length of the optical system 10 is too long, which makes the total length of the optical system 10 difficult to be compressed, and is not favorable for realizing miniaturization design, and thus is not favorable for the application of the optical system 10 in portable electronic devices; below the lower limit of the above conditional expression, the effective focal length of the optical system 10 is too short, and the detail reduction degree of the shot object at a distance is poor, which makes it difficult to meet the telephoto requirement.

The optical system 10 also satisfies the relational condition: -24< (R51+ R52)/TTL < -3.5; r51 is a radius of curvature of the object-side surface S9 of the fifth lens element L5 on the optical axis 101, R52 is a radius of curvature of the image-side surface S10 of the fifth lens element L5 on the optical axis 101, and TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane S17 of the optical system 10 on the optical axis 101. Specifically, (R51+ R52)/TTL can be: -3.972, -4.454, -4.707, -6.352, -8.463, -10.125, -13.712, -15.666, -19.648, -23.456. It should be noted that the curvature radius at the optical axis 101 reflects the change of the central plane shape of the object-side surface or the image-side surface of the lens, and the above relation is satisfied, so that the curvature radians of the object-side surface S9 and the image-side surface S10 of the fifth lens L5 are both in a reasonable range, which is beneficial to eliminating ghost images and reducing tolerance sensitivity of the fifth lens L5.

The optical system 10 also satisfies the relational condition: 1.5< (CT23+ CT34+ CT45+ CT56+ CT67)/BFL < 6; CT23 is the distance on the optical axis 101 between the image-side surface S4 of the second lens L2 and the object-side surface S5 of the third lens L3, CT34 is the distance on the optical axis 101 between the image-side surface S6 of the third lens L3 and the object-side surface S7 of the fourth lens L4, CT45 is the distance on the optical axis 101 between the image-side surface S8 of the fourth lens L4 and the object-side surface S9 of the fifth lens L5, CT56 is the distance on the optical axis 101 between the image-side surface S10 of the fifth lens L5 and the object-side surface S11 of the sixth lens L6, CT67 is the distance on the optical axis 101 between the image-side surface S12 of the sixth lens L6 and the object-side surface S13 of the seventh lens L7, and BFL is the minimum distance in the optical axis direction between the image-side surface S14 of the seventh lens L7 and the imaging surface S17. Specifically, (CT23+ CT34+ CT45+ CT56+ CT67)/BFL may be: 2.146, 2.399, 2.512, 2.972, 3.417, 4.125, 4.628, 4.995, 5.234, 5.757. Satisfying the above relation, the arrangement of the second lens L2 to the seventh lens L7 of the optical system 10 has great flexibility, the pitch of the lenses can be effectively controlled, a great back focal distance can be obtained, and the difficulty in assembling the optical system 10 can be reduced while the miniaturization is satisfied.

The optical system 10 also satisfies the relational condition: 0.2< | f12/f67| < 3; f12 is a combined focal length of the first lens L1 and the second lens L2, and f67 is a combined focal length of the sixth lens L6 and the seventh lens L7. Specifically, | f12/f67| may be: 0.425, 0.825, 1.014, 1.321, 1.56, 1.852, 2.011, 2.38, 2.561, 2.987. Referring to fig. 1, it can be seen that the object-side surface S1 and the image-side surface S2 of the first lens element L1, the object-side surface S3 and the image-side surface S4 of the second lens element L2 are gentle, the object-side surface S11 and the image-side surface S12 of the sixth lens element L6, and the object-side surface S13 and the image-side surface S14 of the seventh lens element L7 are all curved like a wave, and the above relation is satisfied, and by reasonably distributing the powers of f12 and f67, the aberration of the optical system can be compensated well, and even under different conditions, the light rays of different fields can be reasonably deflected, so as to improve the full-field image quality resolution of the optical system 10.

The optical system 10 also satisfies the relational condition: 5< | R72/SAG72| < 60; r72 is a radius of curvature of the image-side surface S14 of the seventh lens L7, and SAG72 is a rise of the vector of the image-side surface S14 of the seventh lens L7 at the maximum effective aperture, that is, a horizontal displacement amount in a direction parallel to the optical axis from the intersection point of the image-side surface S14 of the seventh lens L7 on the optical axis 101 to the maximum effective half aperture position of the image-side surface S14 of the seventh lens L7 (the horizontal displacement amount is defined positive in the image-side direction and negative in the object-side direction). Specifically, | R72/SAG72| may be: 7.415, 11.341, 13.567, 19.315, 21.796, 25.532, 30.413, 37.613, 45.885, 56.097. The relational expression is satisfied, the increase of aberrations such as field curvature, astigmatism and the like can be effectively relieved by reasonably controlling R72 and SAG72, the requirements on the production process are reduced, and the yield is improved.

The optical system 10 also satisfies the relational condition: 0.01< CT56/TTL < 0.05; the CT56 is the distance on the optical axis 101 from the image-side surface S10 of the fifth lens L5 to the object-side surface S11 of the sixth lens L6; TTL is the distance from the object side surface S1 of the first lens element L1 to the image plane S17 of the optical system 10 on the optical axis 101. Specifically, CT56/TTL can be: 0.011, 0.014, 0.021, 0.025, 0.029, 0.032, 0.035, 0.04, 0.045, 0.049. Satisfying the above relational expression, by reasonably configuring the distance between the fifth lens L5 and the sixth lens L6, the aberration of the optical system 10 can be effectively balanced, and at the same time, the total length TTL of the optical system 10 is reasonably controlled, which is beneficial to the assembly of the optical system 10 and improves the resolution of the optical system 10 on an image.

The optical system 10 also satisfies the relational condition: 0.5< (| SAG71| + | SAG72|)/CT7< 3; SAG71 is the saggital height of the object-side surface S13 of the seventh lens L7 at the maximum effective aperture, SAG72 is the saggital height of the image-side surface S14 of the seventh lens L7 at the maximum effective aperture, and CT7 is the thickness of the seventh lens L7 on the optical axis 101. Specifically, (| SAG71| + | SAG72|)/CT7 may be: 0.725, 0.923, 1.255, 1.575, 1.645, 1.712, 1.922, 2.122, 2.544, 2.866. The above relation is satisfied, so that the surface shapes of the object-side surface S13 and the image-side surface S14 of the seventh lens L7 are effectively controlled, the thickness of the seventh lens L7 is effectively controlled, and meanwhile, the aberration generated during the light propagation process can be effectively compensated, and the sensitivity of the optical system 10 is reduced.

The optical system 10 also satisfies the relational condition: 0.1< | SAG62/SD62| < 0.5; SAG62 is the rise of the image-side surface S12 of the sixth lens L6 at the maximum effective aperture, and SD62 is half the maximum effective aperture of the image-side surface S12 of the sixth lens L6. Specifically, | SAG62/SD62| can be: 0.124, 0.135, 0.151, 0.186, 0.211, 0.255, 0.312, 0.391, 0.452, 0.491. Satisfying the above relationship, by appropriately distributing the surface shape and the power of the image-side surface of the sixth lens L6, it is possible to contribute to correction of aberrations generated by the front lens group (the first lens L1 to the fifth lens L5), and in addition, by appropriately distributing the outer diameter and the thickness of the sixth lens L6, it is possible to reduce the incident angle of light on the subsequent imaging lens, and to reduce the sensitivity of the optical system 10.

The optical system 10 also satisfies the relational condition: 0.5< (ET1+ ET2+ ET3)/(CT1+ CT2+ CT3) <0.7, and ET1 is a distance from the maximum effective clear aperture of the object side surface S1 to the maximum effective clear aperture of the image side surface S2 of the first lens L1 in the optical axis direction; ET2 is the distance from the position of the maximum effective clear aperture of the object-side surface S3 to the position of the maximum effective clear aperture of the image-side surface S4 of the second lens L2 in the optical axis direction; ET3 is the distance from the position of the maximum effective clear aperture of the object-side surface S5 to the position of the maximum effective clear aperture of the image-side surface S6 of the third lens L3 in the optical axis direction; CT1 is the thickness of the first lens L1 on the optical axis 101; CT2 is the thickness of the second lens L2 on the optical axis 101; CT3 is the thickness of the third lens element L3 on the optical axis 101. Specifically, (ET1+ ET2+ ET3)/(CT1+ CT2+ CT3) may be: 0.554, 0.555, 0.563, 0.572, 0.592, 0.601, 0.616, 0.635, 0.642, 0.691. Satisfying the above relation, the thickness of the lens group formed by combining the first lens L1 to the third lens L3 in the optical system 10 (i.e. ET1+ ET2+ ET3) is smaller than the thickness of the lens group formed by combining the first lens L1 to the third lens L3 (i.e. CT1+ CT2+ CT3), so that the entire lens group can be used as a positive lens, the light can be deflected toward the center of the optical system 10, the overall change is gentle, the introduced amount of aberration is small, the design of the subsequent lens is facilitated, and the process difficulty and tolerance sensitivity are reduced.

The numerical value of the focal length in the above relation is 587nm, the focal length is at least the value of the corresponding lens at the optical axis 101, and the refractive power of the lens is at least the value at the optical axis 101. And the above relationship conditions and the technical effects thereof are directed to the optical system 10 having the above lens design. When the lens design (the number of lenses, the refractive power arrangement, the surface type arrangement, etc.) of the optical system 10 cannot be ensured, it is difficult to ensure that the optical system 10 can still have the corresponding technical effect when the relational expressions are satisfied, and even the imaging performance may be significantly reduced.

In some embodiments, at least one lens of optical system 10 has an aspheric surface, which may be referred to as having an aspheric surface when at least one of the lens' surfaces (object-side or image-side) is aspheric. In one embodiment, both the object-side surface and the image-side surface of each lens can be designed to be aspheric. The aspheric design can help the optical system 10 to eliminate aberration more effectively, improving imaging quality. In some embodiments, at least one lens in the optical system 10 may also have a spherical surface shape, and the design of the spherical surface shape may reduce the difficulty and cost of manufacturing the lens. In some embodiments, the design of each lens surface in the optical system 10 may be configured by aspheric and spherical surface types for consideration of manufacturing cost, manufacturing difficulty, imaging quality, assembly difficulty, etc.

The surface shape of the aspheric surface can be calculated by referring to an aspheric surface formula:

wherein Z is a distance from a corresponding point on the aspheric surface to a tangent plane of the aspheric surface at the optical axis 101, r is a distance from the corresponding point on the aspheric surface to the optical axis 101, c is a curvature of the aspheric surface at the optical axis 101, k is a conic coefficient, and Ai is a high-order term coefficient corresponding to the ith-order high-order term in the aspheric surface type formula.

It should also be noted that when a lens surface is aspheric, there may be points of inflection where the surface will change in type radially, e.g., one lens surface is convex at a paraxial region 101 and concave at a peripheral region. Specifically, in some embodiments, at least one inflection point is disposed on each of the object-side surface S13 and the image-side surface S14 of the seventh lens L7, and the object-side surface S13 and the image-side surface S14 of the seventh lens L7 are designed to be in a plane shape at the paraxial region 101, so that aberrations such as curvature of field, distortion and the like of the peripheral field in the telephoto system can be well corrected, and the imaging quality can be improved.

In some embodiments, each lens in the optical system 10 may be made of Glass (GL) or Plastic (PC), and the Plastic material may be polycarbonate, gum, etc. The lens made of plastic material can reduce the weight of the optical system 10 and the production cost, and the small size of the optical system 10 is matched to realize the light and thin design of the optical system 10. The glass lens provides the optical system 10 with excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 10 may also be any combination of glass and plastic, and is not necessarily all glass or all plastic, and the specific configuration relationship may be determined according to actual requirements, which is not exhaustive here.

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.

In some embodiments, the optical system 10 further includes a stop, which may be an aperture stop STO or a vignetting stop ST1, where the aperture stop STO is used to control the light incident amount and the depth of field of the optical system 10, and also can achieve good interception of the ineffective light to improve the imaging quality of the optical system 10, and may be disposed between the object side of the optical system 10 and the object side S1 of the first lens L1. It is understood that, in other embodiments, the stop may be disposed between two adjacent lenses, for example, between the second lens L2 and the third lens L3, and the arrangement is adjusted according to practical situations, which is not specifically limited in this embodiment. The aperture stop STO may also be formed by a holder that holds the lens.

The optical system 10 of the present application is illustrated by the following more specific examples:

first embodiment

Referring to fig. 1, in the first embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101, an aperture 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 vignetting stop ST1, 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. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is convex at the paraxial region 101; the object side S1 is convex at the circumference, and the image side S2 is convex at the circumference.

The object-side surface S3 of the second lens element L2 is convex at the paraxial region 101, and the image-side surface S4 is concave at the paraxial region 101; the object side S3 is convex at the circumference, and the image side S4 is concave at the circumference.

The object-side surface S5 of the third lens element L3 is convex at the paraxial region 101, and the image-side surface S6 is concave at the paraxial region 101; object side S5 is convex at the circumference, and image side S6 is concave at the circumference.

The object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 101, and the image-side surface S8 is concave at the paraxial region 101; the object side S7 is convex at the circumference, and the image side S8 is convex at the circumference.

The object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 101, and the image-side surface S10 is convex at the paraxial region 101; object side S9 is concave at the circumference, and image side S10 is convex at the circumference.

The object-side surface S11 of the sixth lens element L6 is concave at the paraxial region 101, and the image-side surface S12 is concave at the paraxial region 101; object side S11 is concave at the circumference, and image side S12 is convex at the circumference.

The object-side surface S13 of the seventh lens element L7 is concave at the paraxial region 101, and the image-side surface S14 is concave at the paraxial region 101; the object side S13 is convex at the circumference, and the image side S14 is convex at the circumference.

In the first embodiment, each lens surface of the first lens L1 to the seventh lens L7 is aspheric, and each lens of the first lens L1 to the seventh lens L7 is made of Plastic (PC). The optical system 10 further includes a filter 110, the filter 110 can be a part of the optical system 10 or can be removed from the optical system 10, but when the filter 110 is removed, the total optical length TTL of the optical system 10 remains unchanged; in the present embodiment, the optical filter 110 is an infrared cut-off filter, and the infrared cut-off filter is disposed between the image side surface S14 of the seventh lens element L7 and the imaging surface S17 of the optical system 10, so as to filter out light rays in invisible wave bands such as infrared light, and only allow visible light to pass through, so as to obtain a better image effect; it is understood that the filter 110 can also filter out light in other bands, such as visible light, and only let infrared light pass through, and the optical system 10 can be used as an infrared optical lens, that is, the optical system 10 can also image and obtain better image effect in a dark environment and other special application scenes.

The lens parameters of the optical system 10 in the first embodiment are shown in table 1 below. The elements of the optical system 10 from the object side to the image side are sequentially arranged in the order from top to bottom in table 1. The Y radius in table 1 is the radius of curvature of the corresponding surface of the lens at the optical axis 101. In table 1, the surface with the surface number S1 represents the object-side surface of the first lens L1, the surface with the surface number S2 represents the image-side surface of the first lens L1, and so on. The absolute value of the first value of the lens in the "thickness" parameter column is the thickness of the lens on the optical axis 101, and the absolute value of the second value is the distance from the image side surface of the lens to the next optical surface (the object side surface or stop surface of the next lens) on the optical axis 101, wherein the thickness parameter of the stop represents the distance from the stop surface to the object side surface of the adjacent lens on the image side on the optical axis 101. In the table, the reference wavelength of the refractive index and the abbe number of each lens is 587nm, the reference wavelength of the effective focal length is 587nm, and the numerical units of the Y radius, the thickness and the effective focal length are millimeters (mm). The parameter data and the lens profile structure used for the relational calculation in the following embodiments are based on the data in the lens parameter table in the corresponding embodiment.

TABLE 1

As can be seen from table 1, the focal length f of the optical system 10 in the first embodiment is 7.88mm, the f-number FNO is 1.37, the total optical length TTL is 8.91mm, the total optical length TTL in the following embodiments is the sum of the thickness values corresponding to the surface numbers S1 to S17, and the maximum field angle FOV of the optical system 10 is 47.89 °.

Table 2 below shows aspheric coefficients of the corresponding lens surfaces in table 1, where K is a conic coefficient and Ai is a coefficient corresponding to the i-th order high-order term in the aspheric surface type formula.

TABLE 2

Fig. 2 includes a longitudinal spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system 10 in the first embodiment. Wherein the reference wavelength of the astigmatism diagram and the distortion diagram is 587 nm. Longitudinal Spherical Aberration diagrams (Longitudinal Spherical Aberration) show the deviation of the converging focus of light rays of different wavelengths through the lens. The ordinate of the longitudinal spherical aberration diagram represents Normalized Pupil coordinates (Normalized Pupil coordmator) from the Pupil center to the Pupil edge, and the abscissa represents the distance (in mm) from the imaging plane S17 to the intersection of the ray with the optical axis 101. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with the respective wavelengths in the first embodiment tend to be consistent, the maximum focus deviation of the respective reference wavelengths is controlled within ± 0.05mm, and for the optical system 10, the diffuse spots or color halos in the imaging picture are effectively suppressed. FIG. 2 also includes an astigmatism plot of the Field curvature (effective Field curvatures) of optical system 10, where the S curve represents the sagittal Field curvature at 587nm and the T curve represents the meridional Field curvature at 587 nm. As can be seen from the figure, the field curvature of the optical system 10 is small, the maximum field curvature is controlled within ± 0.02mm, the degree of curvature of image plane is effectively suppressed for the optical system 10, the sagittal field curvature and the meridional field curvature under each field tend to be consistent, and the astigmatism of each field is better controlled, so that it is known that the center to the edge of the field of view of the optical system 10 has clear imaging. Further, it is understood from the distortion map that the degree of distortion of the optical system 10 having the telephoto characteristic is also well controlled.

Second embodiment

Referring to fig. 3, in the second embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101, an aperture 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 negative refractive power, a vignetting stop ST1, 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. The respective lens surface types of the optical system 10 are as follows:

The object-side surface S3 of the second lens element L2 is concave at the paraxial region 101, and the image-side surface S4 is concave at the paraxial region 101; the object side S3 is convex at the circumference, and the image side S4 is concave at the circumference.

The object-side surface S5 of the third lens element L3 is convex at the paraxial region 101, and the image-side surface S6 is concave at the paraxial region 101; the object side S5 is convex at the circumference, and the image side S6 is concave at the circumference.

The object-side surface S13 of the seventh lens element L7 is concave at the paraxial region 101, and the image-side surface S14 is concave at the paraxial region 101; object side S13 is concave at the circumference, and image side S14 is convex at the circumference.

The lens parameters of the optical system 10 in this embodiment are given in tables 3 and 4, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not described herein.

TABLE 3

TABLE 4

As can be seen from the aberration diagrams in fig. 4, the longitudinal spherical aberration, astigmatism, and distortion of the optical system 10 are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Third embodiment

Referring to fig. 5, in the third embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101, an aperture 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 vignetting stop ST1, 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. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is concave at the paraxial region 101; the object side S1 is convex at the circumference, and the image side S2 is convex at the circumference.

The object-side surface S13 of the seventh lens element L7 is convex at the paraxial region 101, and the image-side surface S14 is concave at the paraxial region 101; object side S13 is concave at the circumference, and image side S14 is convex at the circumference.

The lens parameters of the optical system 10 in this embodiment are given in tables 5 and 6, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not repeated herein.

TABLE 5

TABLE 6

As can be seen from the aberration diagrams in fig. 6, the longitudinal spherical aberration, astigmatism, and distortion of the optical system 10 are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Fourth embodiment

Referring to fig. 7, in the fourth embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101, an aperture 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 vignetting stop ST1, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

The object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 101, and the image-side surface S12 is convex at the paraxial region 101; object side S11 is concave at the circumference, and image side S12 is convex at the circumference.

The lens parameters of the optical system 10 in this embodiment are given in tables 7 and 8, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not described herein.

TABLE 7

TABLE 8

As can be seen from the aberration diagrams in fig. 8, the longitudinal spherical aberration, astigmatism, and distortion of the optical system 10 are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Fifth embodiment

Referring to fig. 9, in the fifth embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, an aperture stop STO, the first lens element L1 with positive refractive power, the second lens element L2 with negative refractive power, the third lens element L3 with negative refractive power, the fourth lens element L4 with positive refractive power, a vignetting stop ST1, the fifth lens element L5 with negative refractive power, the sixth lens element L6 with positive refractive power, and the seventh lens element L7 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

The object-side surface S5 of the third lens element L3 is convex at the paraxial region 101, and the image-side surface S6 is concave at the paraxial region 101; object side S5 is concave at the circumference, like side S6.

The lens parameters of the optical system 10 in this embodiment are given in tables 9 and 10, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not described herein.

TABLE 9

Watch 10

As can be seen from the aberration diagrams in fig. 10, the longitudinal spherical aberration, astigmatism and distortion of the optical system 10 are well controlled, and the optical system 10 of this embodiment has good imaging quality.

Referring to table 11, table 11 summarizes ratios of the relations in the first embodiment to the fifth embodiment of the present application.

TABLE 11

The optical system 10 in each of the above embodiments can secure an imaging effect while satisfying the characteristics of a telephoto and a large aperture compared to a general optical system.

Referring to fig. 11, an embodiment of the present application further provides a camera module 20, where the camera module 20 includes an optical system 10 and an image sensor 210, and the image sensor 210 is disposed on an image side of the optical system 10, and the two can be fixed by a bracket. The image sensor 210 may be a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. Generally, the imaging surface S17 of the optical system 10 overlaps the photosensitive surface of the image sensor 210 when assembled. By adopting the optical system 10 described above, the camera module 20 can ensure an imaging effect while satisfying the characteristics of a telephoto and a large aperture.

Referring to fig. 12, some embodiments of the present application also provide an electronic device 30. The electronic device 30 includes a fixing member 310, the camera module 20 is mounted on the fixing member 310, and the fixing member 310 may be a display screen, a circuit board, a middle frame, a rear cover, or the like. The electronic device 30 may be, but is not limited to, a smart phone, a smart watch, smart glasses, an e-book reader, a tablet computer, a PDA (Personal Digital Assistant), and the like. The camera module 20 can provide good image quality for the electronic device 30 and simultaneously satisfy the characteristics of long focus and large aperture.

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 to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as being permanently connected, detachably connected, or integral; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. 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 description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Moreover, various embodiments or examples and features of various embodiments or examples described in this specification can be combined and combined by one skilled in the art without being mutually inconsistent.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An optical system, comprising seven lens elements with refractive power along an optical axis, in order from an object side to an image side:

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

a second lens element with negative refractive power having a concave image-side surface at paraxial region;

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

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

a sixth lens element with refractive power;

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

the optical system satisfies the relationship:

5.4°/mm<FOV/f<6.2°/mm；0.5<(|SAG71|+|SAG72|)/CT7<3；

f is the effective focal length of the optical system, the FOV is the maximum field angle of the optical system, SAG71 is the rise of the object-side surface of the seventh lens at the maximum effective aperture, SAG72 is the rise of the image-side surface of the seventh lens at the maximum effective aperture, and CT7 is the thickness of the seventh lens on the optical axis.

2. The optical system of claim 1, wherein the optical system satisfies the relationship:

3.2<FNO*TTL/IMGH<3.8；

FNO is the f-number of the optical system; 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; IMGH is half the image height corresponding to the maximum field angle of the optical system.

3. The optical system of claim 1, wherein the optical system satisfies the relationship:

-24<(R51+R52)/TTL<-3.5；

r51 is a curvature radius of an object-side surface of the fifth lens element, R52 is a curvature radius of an image-side surface of the fifth lens element, and TTL is an axial distance from the object-side surface of the first lens element to an image plane of the optical system.

4. The optical system of claim 1, wherein the optical system satisfies the relationship:

1.5<(CT23+CT34+CT45+CT56+CT67)/BFL<6；

CT23 is an axial distance between an image-side surface of the second lens element and an object-side surface of the third lens element, CT34 is an axial distance between the image-side surface of the third lens element and an object-side surface of the fourth lens element, CT45 is an axial distance between the image-side surface of the fourth lens element and an object-side surface of the fifth lens element, CT56 is an axial distance between the image-side surface of the fifth lens element and an object-side surface of the sixth lens element, CT67 is an axial distance between the image-side surface of the sixth lens element and an object-side surface of the seventh lens element, and BFL is a minimum axial distance between the image-side surface of the seventh lens element and an image-side surface of the seventh lens element.

5. The optical system of claim 1, wherein the optical system satisfies the relationship:

5<|R72/SAG72|<60；

r72 is the radius of curvature of the image-side surface of the seventh lens, SAG72 is the sagittal height of the image-side surface of the seventh lens at maximum effective aperture.

6. The optical system of claim 1, wherein the optical system satisfies the relationship:

0.1<|SAG62/SD62|<0.5；

SAG62 is the rise of the image-side surface of the sixth lens at the maximum effective aperture, and SD62 is half the maximum effective aperture of the image-side surface of the sixth lens.

7. The optical system of claim 1, wherein the optical system satisfies the relationship:

0.5<(ET1+ET2+ET3)/(CT1+CT2+CT3)<0.7；

ET1 is a distance from the maximum effective clear aperture of the object side surface to the maximum effective clear aperture of the image side surface of the first lens in the optical axis direction; ET2 is the distance from the maximum effective clear aperture of the object side surface to the maximum effective clear aperture of the image side surface of the second lens in the optical axis direction; ET3 is the distance from the maximum effective light-transmitting aperture of the object side surface of the third lens to the maximum effective light-transmitting aperture of the image side surface in the optical axis direction; CT1 is the thickness of the first lens on the optical axis; CT2 is the thickness of the second lens on the optical axis; CT3 is the thickness of the third lens on the optical axis.

8. A camera module comprising an image sensor and the optical system of any one of claims 1 to 7, wherein the image sensor is disposed on an image side of the optical system.

9. An electronic device comprising a fixing member and the camera module of claim 8, wherein the camera module is disposed on the fixing member.