CN114578525A

CN114578525A - Optical system, lens module and electronic equipment

Info

Publication number: CN114578525A
Application number: CN202210492028.6A
Authority: CN
Inventors: 龙鑫灿; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2022-05-07
Filing date: 2022-05-07
Publication date: 2022-06-03
Anticipated expiration: 2042-05-07
Also published as: CN114578525B

Abstract

An optical system, lens module and electronic device, the optical system includes seven lens with bending force, wherein, the first lens, fourth lens and sixth lens have positive bending force, the second lens and seventh lens have negative bending force, the third lens and fifth lens have bending force; and the optical system satisfies the relation: 6.2mm<Imgh²/f<7.4 mm; wherein f is the effective focal length of the optical system, and Imgh is half of the height of the image corresponding to the maximum field angle of the optical system; the optical system, the lens module and the electronic equipment provided by the embodiment of the invention can meet the characteristics of miniaturization, large image plane and high pixel, and can realize high-quality imaging.

Description

Optical system, lens module and electronic equipment

Technical Field

The invention belongs to the technical field of optical imaging, and particularly relates to an optical system, a lens module and electronic equipment.

Background

With the development of science and technology, the market has higher and higher requirements on the size and the imaging quality of the optical lens at the mobile end, which also requires that the optical lens has a miniaturized design and simultaneously has performance. In order to improve the imaging quality, the conventional optical lens often adopts a mode of increasing the number of lenses to correct the aberration of the optical lens, however, the increase of the number of lenses is accompanied with the increase of the size of the optical lens, and the thickness of the mobile device is influenced. Therefore, it is a key issue how to configure parameters such as the bending force and the surface shape of each lens of the optical lens, so as to satisfy the miniaturization, large image plane and high imaging quality of the optical lens.

Disclosure of Invention

The invention aims to provide an optical system, a lens module and an electronic device, wherein the optical system can meet the characteristics of miniaturization, large image surface and high pixel and can realize high-quality imaging.

In order to realize the purpose of the invention, the invention provides the following technical scheme:

in a first aspect, the present invention provides an optical system including seven lenses having a bending force, 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, the second lens element having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a third lens element with refractive power, the third lens element 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 positive refractive power, an image-side surface of the fourth lens element being convex 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 positive refractive power, an object-side surface of the sixth lens element being convex at a paraxial region; a seventh lens element with negative dioptric power, said seventh lens element having a concave image-side surface at a paraxial region; the optical system satisfies the relation: 6.2mm<Imgh²/f<And 7.4mm, wherein Imgh is half of the height of the maximum field angle corresponding image of the optical system, and f is the effective focal length of the optical system.

Through the arrangement of the first lens with positive bending force, the object side surface of the first lens is convex at the lower beam, and the image side surface of the first lens is concave at the lower beam, so that incident light can be effectively converged, and the total length of the optical system can be compressed. The second lens element has negative refractive power, and is matched with the convex-concave type at the paraxial region to balance the aberration generated by the first lens element, thereby improving the imaging quality of the optical system. The first lens with positive bending force and the second lens with negative bending force are matched to mutually offset the aberration generated by each other. Secondly, first lens to third lens all adopt the falcate design, and are concave-convex type in the paraxial region department, are favorable to incident ray to get into optical system gently, are favorable to correcting the aberration that optical system produced. The fourth lens has positive bending force, and is matched with the first lens with strong positive bending force, so that the total length of the optical system can be further compressed, the bending force burden of the first lens is reduced, and the aberration which is difficult to correct can be avoided. The fifth lens element has a refractive power, and the object-side surface thereof is concave at a paraxial region, which is advantageous for correcting the positive spherical aberration generated by the front lens elements (the first to fourth lens elements) and for enlarging the field angle of the optical system. The sixth lens has positive bending force, and the object side surface of the sixth lens is convex at a position close to the optical axis, so that light can be converged, overlarge deflection of light in an edge view field between the lenses can be prevented, more stray light generated in the edge view field is avoided, a dark angle phenomenon is avoided, and the like. The seventh lens has negative bending force, can ensure the stability of a back focal length of the optical system, and the image side surface of the seventh lens is a concave surface at a position close to the optical axis.

The optical system satisfies the relation: 6.2mm<Imgh²/f<7.4mm, further the optical system satisfies the relation: 0.9<Imgh/f<1.1; wherein, Imgh is half of the maximum field angle corresponding image height of the optical system, and f is the effective focal length of the optical system. When the relational expression is satisfied, the large image plane and the wide angle of the optical system can be favorably realized, and the optical system can obtain good imaging performance. When the effective focal length is lower than the lower limit of the relational expression, the effective focal length of the optical system is too long, the bending force to the light is insufficient, the miniaturization of the optical system is not facilitated, and the wide angle of the optical system is also not facilitated; when the upper limit of the relation is exceeded, an excessively large size of the image plane tends to result in an excessively wide angle of view, makes it difficult to correct aberrations in the peripheral field of view, tends to cause vignetting, distortion, and the like, and may causeAnd deterioration of optical performance, thereby degrading image quality.

In one embodiment, 3.4mm < f/Fno <4 mm; wherein Fno is an f-number of the optical system. When the relation is satisfied, the optical system can have a longer effective focal length and can realize remote shooting, and the optical system has a smaller diaphragm number, so that the optical system can be ensured to have sufficient light flux, the dim light shooting condition is improved, especially, a shooting picture with good definition can be obtained under the dim light environment, the imaging quality of the optical system is improved, and the high-definition shooting effect with high image quality is realized. When the light quantity is lower than the lower limit of the relational expression, the diaphragm number of the optical system is too large, so that the light flux quantity of the optical system is insufficient, the picture feeling of the optical system is reduced, and the imaging quality of the optical system is reduced; when the effective focal length is higher than the upper limit of the relational expression, the effective focal length of the optical system is too long, so that the total length of the optical system is difficult to compress, the volume of the optical system is increased, and the optical system is not favorable for meeting the miniaturization design requirement.

In one embodiment, the optical system satisfies the relationship: 2.6deg/mm < HFOV/(Fno TTL) <3.2 deg/mm; the HFOV is a half of a maximum field angle of the optical system, Fno is an f-number of the optical system, and TTL is a distance from an object side surface of the first lens to an image plane of the optical system on an optical axis. When the relation formula is satisfied, the half field angle and the diaphragm number of the optical system can be reasonably configured, so that the optical system can simultaneously have the characteristics of a large field angle and a large diaphragm, and the requirements of large-range shooting and large light transmission of the optical system can be satisfied. When the angle of view and the aperture of the optical system are too small below the lower limit of the relational expression, the visual range is narrowed, the requirement of large-range shooting is difficult to meet, a dark angle phenomenon is easy to generate due to insufficient light flux, or the total length of the optical system is too long, so that the miniaturization design of the optical system is not facilitated; when the angle of view and the aperture of the optical system are higher than the upper limit of the relational expression, the angle of view and the aperture of the optical system are too large, the control of light rays is not facilitated, a large amount of stray light is easily generated, and the like, so that the improvement of imaging quality is not facilitated, or the structure of the optical system is too compact, the difficulty of aberration correction is increased, and the imaging performance of the optical system is easily reduced.

In one embodiment, the optical system satisfies the relationship: 6.5mm < f tan (hfov) <7 mm; wherein the HFOV is half of a maximum field angle of the optical system. When the above relation is satisfied, the ratio of the effective focal length of the optical system to the tangent value of half of the maximum field angle of the optical system can be controlled within a certain range, so that the optical system has a good magnification ratio, and the optical system has a good detail recognition capability during framing.

In one embodiment, the optical system satisfies the relationship: 23deg < HFOV/Fno <26.5 deg; wherein, HFOV is half of the maximum field angle of the optical system, Fno is the f-number of the optical system. When the relation formula is satisfied, the half field angle and the diaphragm number of the optical system can be reasonably configured, so that the optical system can simultaneously have the characteristics of a large field angle and a large diaphragm, and the requirements of large-range shooting and large light transmission of the optical system can be satisfied. When the light flux is lower than the lower limit of the relational expression, the visual field angle and the aperture of the optical system are too small, so that the visual range is reduced, the requirement of large-range shooting is difficult to meet, and the dark angle phenomenon is easily generated due to insufficient light flux; when the angle of view is higher than the upper limit of the relational expression, the angle of view and the aperture of the optical system are too large, which is not favorable for controlling the light, and is not favorable for improving the imaging quality.

In one embodiment, the optical system satisfies the relationship: 0< | f123/f3| <1, and further, the optical system satisfies the relation: 1< f123/f < 3; wherein f123 is a combined focal length of the first lens to the third lens, and f3 is an effective focal length of the third lens. When the above relational expression is satisfied, the contribution ratio of the focal lengths of the first lens, the second lens and the third lens in the optical system can be reasonably configured, the light rays incident at a large angle can be reasonably guided to enter the optical system smoothly by matching the surface type design of the first lens to the third lens, the optical system can simultaneously give consideration to the design requirements of a large visual angle and miniaturization, the spherical aberration and the axial chromatic aberration of the optical system can be effectively corrected, the light deflection can be slowed down, the light deflection angle is reduced, the imaging analysis force of the optical system is improved, and the imaging quality of the optical system is improved. When the ratio is lower than the lower limit of the relational expression, the contribution of the combined focal length of the first lens to the third lens is small, the light deflection is insufficient, the total length of the optical system is too large, the miniaturization of the system is not facilitated, the large-angle light cannot be effectively converged, the optical system cannot meet the shooting requirement of a large visual angle, the light flux is insufficient, and the image definition is reduced; when the distance is higher than the upper limit of the relational expression, the contribution of the combined focal length of the first lens to the third lens is larger, which easily causes the light beam deflection to be too large, so that the optical lens is easy to generate a serious astigmatism phenomenon, which leads to the reduction of the imaging quality of the optical lens, and the light flux is too large due to more large-angle light beams, which easily causes the occurrence of stray light which cannot be eliminated in the edge field of view, which leads to chromatic dispersion or purple fringing and the like.

In one embodiment, the optical system satisfies the relationship: 0.25< SD11/Imgh < 0.5; wherein SD11 is the maximum effective half aperture of the object-side surface of the first lens, and Imgh is half of the maximum field angle corresponding image height of the optical system. When the strip relational expression is satisfied, the optical system has a matched light incidence range and a matched light-sensitive surface size, and the radial size of the object side surface of the first lens can be reduced, so that the optical system has a small head design, the size of an opening on a screen of the equipment can be reduced, and the screen occupation ratio of the equipment is improved; in addition, the reasonable caliber is not only beneficial to the processing and forming of the first lens, but also beneficial to the optical system to have a larger aperture, so that the proper light flux can be obtained, the dim light shooting condition is improved, the shot picture is more vivid, the definition of the shot image is ensured, and the high-definition shooting effect of high image quality is realized; meanwhile, the optical system has smaller depth of field, the optical lens can acquire more scene contents, imaging information of the optical lens is enriched, and the shooting experience of a user is improved. When the size of the photosensitive surface of the optical system is smaller than the lower limit of the relational expression, the size of the photosensitive surface of the optical system is too large relative to the maximum effective aperture of the object side surface of the first lens, so that the deflection degree of incident light is too large, off-axis aberration is easy to increase, and the imaging quality is not improved; meanwhile, if the maximum effective half aperture of the object side surface of the first lens is too small, the light transmission amount of the optical system is insufficient, and the relative brightness of light is insufficient, so that the image definition is reduced; when the maximum effective half aperture of the object side surface of the first lens is higher than the upper limit of the relational expression, the maximum effective half aperture of the object side surface of the first lens is too large, the small head design is difficult to realize, and simultaneously, the light passing amount of an optical system is too large, the exposure is too large, the brightness is too high, chromatic aberration is easy to generate, and the like, so that the image quality is influenced.

In one embodiment, the optical system satisfies the relationship: 0.9< f4/f1< 1.5; wherein f1 is an effective focal length of the first lens, and f4 is an effective focal length of the fourth lens. When the relation is satisfied, the ratio of the effective focal lengths of the fourth lens and the first lens is reasonably configured, so that the spherical aberration of the optical system can be effectively corrected, the imaging quality of the optical system is improved, the total length of the optical system is favorably compressed, and the characteristic of thinness is realized.

In one embodiment, the optical system satisfies the relationship: 0.8< R52/R51<2.3, further the optical system satisfies the relation: l (R51-R52)/(R51+ R52) | < 0.4; wherein R51 is a radius of curvature of the fifth lens object-side surface at the optical axis, and R52 is a radius of curvature of the fifth lens image-side surface at the optical axis. When the relation is satisfied, the thickness of the fifth lens can be kept relatively uniform, and the fifth lens is prevented from being excessively gentle or excessively bent, so that the design difficulty and the assembly sensitivity of the optical system are reduced, the angle of the principal ray at the peripheral visual angle incident on the imaging surface is favorably reduced, the generation of astigmatism is inhibited, and the image quality of the whole imaging from the center to the edge of the imaging surface is clear and uniform.

In one embodiment, the optical system satisfies the relationship: 37< | f2/CT2| < 52; wherein f2 is the effective focal length of the second lens element, and CT2 is the thickness of the second lens element on the optical axis. When the relation is satisfied, the effective focal length of the second lens and the thickness of the second lens on the optical axis are reasonably configured, so that the aberration, the spherical aberration, the coma aberration and the like of the optical system can be effectively corrected, and the imaging quality is improved. When the effective focal length is lower than the lower limit of the relational expression, the effective focal length of the second lens group is too small, which easily causes the bending force of the second lens to be too strong, and generates larger aberration; when the effective focal length of the second lens group is higher than the upper limit of the relational expression, the effective focal length of the second lens group is too large, the bending force of the second lens is not favorably and reasonably distributed, and phenomena such as high-order spherical aberration, coma aberration and the like are easily generated at the second lens due to insufficient bending force, so that the imaging quality of the optical system is influenced.

In one embodiment, the optical system satisfies the relationship: 0.8< CT1/(CT2+ CT3) < 1.3; wherein CT1 is the thickness of the first lens element on the optical axis, CT2 is the thickness of the second lens element on the optical axis, and CT3 is the thickness of the third lens element on the optical axis. When the strip relation is satisfied, the resistance of the first lens to the environment can be enhanced, and therefore the thicknesses of the first lens, the second lens and the third lens are properly configured, which is beneficial to the miniaturization design of the optical system, and the influence of the strength of the optical system due to the excessively thin lens on the manufacturing yield is avoided.

In one embodiment, the optical system satisfies the relationship: 0.9< | SAG71|/CT7< 5; SAG71 is the distance from the intersection point of the object side surface of the seventh lens and the optical axis to the maximum effective radius of the object side surface of the seventh lens on the optical axis (namely the rise of the object side surface of the seventh lens at the maximum effective radius), and CT7 is the thickness of the seventh lens on the optical axis. When the relation is satisfied, the ratio of the rise of the object side surface of the seventh lens to the central thickness of the seventh lens can be reasonably distributed, the surface shape of the seventh lens cannot be excessively bent or flat, and the design and manufacturing sensitivity of the seventh lens can be favorably reduced, so that the forming processability and forming yield of the seventh lens can be favorably improved, the seventh lens can be conveniently manufactured and formed, and the manufacturing cost of the seventh lens can be reduced; meanwhile, the seventh lens cannot be too thin or too thick due to reasonable surface shape change, so that the focal length of the seventh lens can be reasonably controlled, the seventh lens is used as the lens closest to an imaging surface, and reasonable bending force is beneficial to correcting distortion and field curvature generated by each lens (from the first lens to the sixth lens) on an object side, so that the balance of distortion and field curvature of an optical system is ensured, namely the distortion and field curvature of different fields tend to be balanced, the image quality of the whole picture of the optical system is uniform, and the imaging quality of the optical system is improved. When the optical axis is lower than the lower limit of the relational expression, the surface shape of the object side surface of the seventh lens at the circumference is too smooth, the deflection capability of the light rays of the off-axis field of view is insufficient, and the correction of distortion and field curvature aberration is not facilitated; if the height is higher than the upper limit of the relation, the object-side surface of the seventh lens element is excessively curved at the circumference, which may result in poor molding and affect the yield.

In one embodiment, the optical system satisfies the relationship: 1.3< (f1+ f2)/f7< 2; wherein f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f7 is the effective focal length of the seventh lens. When the relation is satisfied, the ratio of the sum of the bending forces of the first lens and the second lens to the bending force of the seventh lens can be reasonably configured, so that the spherical aberration contribution degrees of the first lens, the second lens and the seventh lens in the optical system can be reasonably distributed, and the imaging quality of a near-optical axis area of the optical system can be improved. When the positive bending force is lower than the lower limit of the relational expression, the positive bending force of the first lens is insufficient, so that large-angle light rays are not favorably enabled to enter the optical system, and the shooting range of the optical system is reduced; when the negative bending force is higher than the upper limit of the relational expression, the negative bending force of the seventh lens is too strong, the angle of light rays entering an imaging surface is too large, the photosensitive performance of the photosensitive chip is easily reduced, and a dark angle is easily generated, so that the shooting quality is influenced.

In one embodiment, the optical system satisfies the relationship: 4.8deg/mm < HFOV/TTL <5.6 deg/mm; 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. When the relation is satisfied, the optical total length (namely, the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis) and the maximum field angle of the optical system can be reasonably configured, so that the total length of the optical system is favorably shortened, the miniaturization design is realized, and meanwhile, the optical system has a large-view-angle characteristic, so that more scene contents can be acquired, and the imaging information of the optical system is enriched. When the lower limit of the relational expression is lower, the total length of the optical system is too large, which is not beneficial to the miniaturization design of the optical system; when it is higher than the upper limit of the relation, the structure of the optical system is too compact, so that aberration correction becomes difficult, thereby easily causing a decrease in imaging performance.

In a second aspect, the present invention further provides a lens module, which includes the optical system described in any one of the embodiments of the first aspect, and a photosensitive chip disposed on an image side of the optical system. The optical system provided by the invention is added into the lens module, and the lens module has the characteristics of large image surface and high pixels by reasonably designing the surface shape and the bending force of each lens in the optical system, so that the high-quality imaging effect can be realized.

In a third aspect, the present invention further provides an electronic device, which includes a housing and the lens module set in the second aspect, wherein the lens module set is disposed in the housing. By adding the lens module provided by the invention into the electronic equipment, the miniaturized lens module design can save more space for installing other devices while the electronic equipment has a high-quality imaging effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

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

FIG. 2 includes a plot of longitudinal spherical aberration, a plot of astigmatism, and a plot of distortion for the first embodiment;

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

FIG. 4 includes a plot of longitudinal spherical aberration, a plot of astigmatism, and a plot of distortion for the second embodiment;

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

FIG. 6 includes a plot of longitudinal spherical aberration, a plot of astigmatism, and a plot of distortion for the third embodiment;

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

FIG. 8 includes a longitudinal spherical aberration plot, an astigmatism plot, and a distortion plot of the fourth embodiment;

FIG. 9 is a schematic view of the optical system configuration of the fifth embodiment;

FIG. 10 includes a plot of longitudinal spherical aberration, a plot of astigmatism, and a plot of distortion for the fifth embodiment;

fig. 11 is a schematic view of a lens module according to an embodiment of the invention;

fig. 12 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In a first aspect, the present invention provides an optical system including seven lenses having a bending force, 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 at paraxial region and a concave image-side surface at paraxial region; a third lens element with refractive power, the third lens element having a convex object-side surface and a concave image-side surface; a fourth lens element with positive refractive power having a convex image-side surface at 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 positive refractive power having an object-side surface at paraxial regionA convex surface; a seventh lens element with negative dioptric power, the seventh lens element having a concave image-side surface at paraxial region; the optical system satisfies the relation: 6.2mm<Imgh²/f<And 7.4mm, wherein Imgh is half of the height of the maximum field angle corresponding image of the optical system, and f is the effective focal length of the optical system.

Through the arrangement of the first lens with positive bending force, the object side surface of the first lens is convex at the lower beam, and the image side surface of the first lens is concave at the lower beam, so that incident light can be effectively converged, and the total length of the optical system can be compressed. The second lens has negative bending force, and is matched with the convex-concave shape of the second lens at the position close to the optical axis, so that the aberration generated by the first lens is favorably balanced, and the imaging quality of the optical system is favorably improved. The first lens with positive bending force and the second lens with negative bending force are matched to mutually offset the aberration generated by each other. And secondly, the first lens to the third lens are designed in a meniscus shape, and the first lens to the third lens are both in a convex concave shape at a paraxial region, so that incident light can smoothly enter the optical system, and aberration generated by the optical system can be corrected. The fourth lens has positive bending force, and is matched with the first lens with strong positive bending force, so that the total length of the optical system can be further compressed, the bending force burden of the first lens is reduced, and the aberration which is difficult to correct can be avoided. The fifth lens element with refractive power has a concave object-side surface near the optical axis, which is favorable for correcting the positive spherical aberration generated by the front lens elements (the first to fourth lens elements) and for enlarging the field angle of the optical system. The sixth lens has positive bending force, and the object side surface of the sixth lens is a convex surface at a paraxial region, so that light can be converged, overlarge deflection of light in an edge view field between the lenses can be prevented, more stray light generated in the edge view field is avoided, a dark angle phenomenon is avoided, and the like. The seventh lens has negative bending force, can ensure the stability of a back focal length of the optical system, and the image side surface of the seventh lens is a concave surface at a position close to the optical axis.

The optical system satisfies the relation: 6.2mm<Imgh²/f<7.4mmFurther, the optical system satisfies the relation: 0.9<Imgh/f<1.1; where, Imgh is half of the maximum field angle of the optical system corresponding to the image height, and f is the effective focal length of the optical system. When the relation is satisfied, the large image plane and the wide angle of the optical system can be realized, and the optical system can obtain good imaging performance. When the effective focal length is lower than the lower limit of the relational expression, the effective focal length of the optical system is too long, the bending force to the light is insufficient, the miniaturization of the optical system is not facilitated, and the wide angle of the optical system is also not facilitated; when the upper limit of the relational expression is exceeded, an excessively large image plane size tends to result in an excessively wide viewing angle range, makes it difficult to correct aberrations in the peripheral field, tends to cause a dark angle, distortion, and the like, and also causes deterioration in optical performance, thereby degrading image quality.

In one embodiment, 3.4mm < f/Fno <4 mm; where Fno is the f-number of the optical system. When the relation is satisfied, the optical system can have a longer effective focal length, can realize remote shooting, and has a smaller f-number, so that the optical system can have sufficient light transmission amount, the dim light shooting condition is improved, especially, a shooting picture with good definition can be obtained in a dim light environment, the imaging quality of the optical system is improved, and a high-quality and high-definition shooting effect is realized. When the light quantity is lower than the lower limit of the relational expression, the diaphragm number of the optical system is too large, so that the light flux quantity of the optical system is insufficient, the picture feeling of the optical system is reduced, and the imaging quality of the optical system is reduced; when the effective focal length is higher than the upper limit of the relational expression, the effective focal length of the optical system is too long, so that the total length of the optical system is difficult to compress, the volume of the optical system is increased, and the optical system is not favorable for meeting the miniaturization design requirement.

In one embodiment, the optical system satisfies the relationship: 2.6deg/mm < HFOV/(Fno TTL) <3.2 deg/mm; the HFOV is a half of the maximum field angle of the optical system, Fno is an f-number of the optical system, and 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. When the relation formula is satisfied, the half field angle and the diaphragm number of the optical system can be reasonably configured, so that the optical system can simultaneously have the characteristics of a large field angle and a large diaphragm, and the requirements of large-range shooting and large light transmission of the optical system can be satisfied. When the distance is lower than the lower limit of the relational expression, the visual field angle and the aperture of the optical system are too small, so that the visual range is reduced, the requirement of large-range shooting is difficult to meet, a dark angle phenomenon is easily caused by insufficient light transmission quantity, or the total length of the optical system is too long, so that the miniaturization design of the optical system is not facilitated; when the angle of view and the aperture of the optical system are higher than the upper limit of the relational expression, the angle of view and the aperture of the optical system are too large, the control of light rays is not facilitated, a large amount of stray light is easily generated, and the like, so that the improvement of imaging quality is not facilitated, or the structure of the optical system is too compact, the difficulty of aberration correction is increased, and the imaging performance of the optical system is easily reduced.

In one embodiment, the optical system satisfies the relationship: 6.5mm < f tan (hfov) <7 mm; the HFOV is a half of the maximum field angle of the optical system. When the above relation is satisfied, the ratio of the effective focal length of the optical system to the tangent value of half of the maximum field angle of the optical system can be controlled within a certain range, so that the optical system has a good magnification ratio, and the optical system has a good detail recognition capability during framing.

In one embodiment, the optical system satisfies the relationship: 0< | f123/f3| <1, and further, the optical system satisfies the relation: 1< f123/f < 3; wherein f123 is a combined focal length of the first lens element and the third lens element, and f3 is an effective focal length of the third lens element. When the above relational expression is satisfied, the contribution ratio of the focal lengths of the first lens, the second lens and the third lens in the optical system can be reasonably configured, the light rays incident at a large angle can be reasonably guided to enter the optical system smoothly by matching the surface type design of the first lens to the third lens, the optical system can simultaneously give consideration to the design requirements of a large visual angle and miniaturization, the spherical aberration and the axial chromatic aberration of the optical system can be effectively corrected, the light deflection can be slowed down, the light deflection angle is reduced, the imaging analysis force of the optical system is improved, and the imaging quality of the optical system is improved. When the ratio is lower than the lower limit of the relational expression, the contribution of the combined focal length of the first lens to the third lens is small, the light deflection is insufficient, the total length of the optical system is too large, the miniaturization of the system is not facilitated, the large-angle light cannot be effectively converged, the optical system cannot meet the shooting requirement of a large visual angle, the light flux is insufficient, and the image definition is reduced; when the distance is higher than the upper limit of the relational expression, the contribution of the combined focal length of the first lens to the third lens is larger, which easily causes the light beam deflection to be too large, so that the optical lens is easy to generate a serious astigmatism phenomenon, which leads to the reduction of the imaging quality of the optical lens, and the light flux is too large due to more large-angle light beams, which easily causes the occurrence of stray light which cannot be eliminated in the edge field of view, which leads to chromatic dispersion or purple fringing and the like.

In one embodiment, the optical system satisfies the relationship: 0.25< SD11/Imgh < 0.5; where SD11 is the maximum effective half aperture of the object-side surface of the first lens, and Imgh is half the height of the image corresponding to the maximum field angle of the optical system. When the strip relational expression is satisfied, the optical system has a matched light incidence range and a matched light-sensitive surface size, and the radial size of the object side surface of the first lens can be reduced, so that the optical system has a small head design, the size of an opening on a screen of the equipment can be reduced, and the screen occupation ratio of the equipment is improved; in addition, the reasonable caliber is not only beneficial to the processing and forming of the first lens, but also beneficial to the optical system to have a larger aperture, so that the proper light flux can be obtained, the dim light shooting condition is improved, the shot picture is more vivid, the definition of the shot image is ensured, and the high-definition shooting effect of high image quality is realized; meanwhile, the optical system has smaller depth of field, the optical lens can acquire more scene contents, imaging information of the optical lens is enriched, and the shooting experience of a user is improved. When the size of the photosensitive surface of the optical system is smaller than the lower limit of the relational expression, the size of the photosensitive surface of the optical system is too large relative to the maximum effective aperture of the object side surface of the first lens, so that the deflection degree of incident light is too large, off-axis aberration is easy to increase, and the imaging quality is not improved; meanwhile, if the maximum effective half aperture of the object side surface of the first lens is too small, the light transmission amount of the optical system is insufficient, and the relative brightness of light is insufficient, so that the image definition is reduced; when the maximum effective half aperture of the object side surface of the first lens is higher than the upper limit of the relational expression, the maximum effective half aperture of the object side surface of the first lens is too large, the small head design is difficult to realize, and simultaneously, the light passing amount of an optical system is too large, the exposure is too large, the brightness is too high, chromatic aberration is easy to generate, and the like, so that the image quality is influenced.

In one embodiment, the optical system satisfies the relationship: 0.9< f4/f1< 1.5; wherein f1 is the effective focal length of the first lens, and f4 is the effective focal length of the fourth lens. When the relation is satisfied, the ratio of the effective focal lengths of the fourth lens and the first lens is reasonably configured, so that the spherical aberration of the optical system can be effectively corrected, the imaging quality of the optical system is improved, the total length of the optical system is favorably compressed, and the characteristic of thinness is realized.

In one embodiment, the optical system satisfies the relationship: 0.8< R52/R51<2.3, further the optical system satisfies the relation: l (R51-R52)/(R51+ R52) | < 0.4; wherein R51 is the radius of curvature of the object-side surface of the fifth lens element at the optical axis, and R52 is the radius of curvature of the image-side surface of the fifth lens element at the optical axis. When the relation is satisfied, the thickness of the fifth lens can be kept relatively uniform, and the fifth lens is prevented from being excessively gentle or excessively bent, so that the design difficulty and the assembly sensitivity of the optical system are reduced, the angle of incidence of the chief ray at the peripheral visual angle to the imaging surface is reduced, the generation of astigmatism is inhibited, and the image quality of the whole imaging from the center to the edge of the imaging surface is clear and uniform.

In one embodiment, the optical system satisfies the relationship: 37< | f2/CT2| < 52; wherein f2 is the effective focal length of the second lens element, and CT2 is the thickness of the second lens element along the optical axis. When the relation is satisfied, the effective focal length of the second lens and the thickness of the second lens on the optical axis are reasonably configured, so that the aberration, the spherical aberration, the coma aberration and the like of the optical system can be effectively corrected, and the imaging quality is improved. When the effective focal length of the second lens group is lower than the lower limit of the relational expression, the bending force of the second lens is easy to be too strong, and larger aberration is generated; when the effective focal length of the second lens group is higher than the upper limit of the relational expression, the effective focal length of the second lens group is too large, the bending force of the second lens is not favorably and reasonably distributed, and phenomena such as high-order spherical aberration, coma aberration and the like are easily generated at the second lens due to insufficient bending force, so that the imaging quality of the optical system is influenced.

In one embodiment, the optical system satisfies the relationship: 0.8< CT1/(CT2+ CT3) < 1.3; wherein, CT1 is the thickness of the first lens element on the optical axis, CT2 is the thickness of the second lens element on the optical axis, and CT3 is the thickness of the third lens element on the optical axis. When the strip relation is satisfied, the resistance of the first lens to the environment can be enhanced, and therefore the thicknesses of the first lens, the second lens and the third lens are properly configured, which is beneficial to the miniaturization design of the optical system, and the influence of the strength of the optical system due to the excessively thin lens on the manufacturing yield is avoided.

In one embodiment, the optical system satisfies the relationship: 0.9< | SAG71|/CT7< 5; SAG71 is the distance from the intersection point of the object-side surface of the seventh lens and the optical axis to the maximum effective radius of the object-side surface of the seventh lens on the optical axis (i.e. the rise of the object-side surface of the seventh lens at the maximum effective radius), and CT7 is the thickness of the seventh lens on the optical axis. When the strip relation is satisfied, the ratio of the rise of the object side surface of the seventh lens to the center thickness of the seventh lens can be reasonably distributed, the surface shape of the seventh lens cannot be excessively bent or flat, and the design and manufacturing sensitivity of the seventh lens can be favorably reduced, so that the forming processability and forming yield of the seventh lens can be favorably improved, the manufacturing and forming of the seventh lens can be facilitated, and the manufacturing cost of the seventh lens can be reduced; meanwhile, the seventh lens cannot be too thin or too thick due to reasonable surface type change, so that the focal length of the seventh lens can be reasonably controlled, the seventh lens is used as the lens closest to the imaging surface, and reasonable bending force is beneficial to correcting distortion and field curvature generated by each lens (from the first lens to the sixth lens) on the object side, so that the balance of the distortion and the field curvature of the optical system is ensured, namely the sizes of the distortion and the field curvature of different fields tend to be balanced, the image quality of the whole picture of the optical system is uniform, and the imaging quality of the optical system is improved. When the optical axis is lower than the lower limit of the relational expression, the surface shape of the object side surface of the seventh lens at the circumference is too smooth, the deflection capability of the light rays of the off-axis field of view is insufficient, and the correction of distortion and field curvature aberration is not facilitated; if the height is higher than the upper limit of the relation, the object-side surface of the seventh lens element is excessively curved at the circumference, which may result in poor molding and affect the yield.

In one embodiment, the optical system satisfies the relationship: 4.8deg/mm < HFOV/TTL <5.6 deg/mm; 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. When the above relational expression is satisfied, the optical total length (i.e., the distance between the object-side surface of the first lens element and the imaging surface of the optical system on the optical axis) and the maximum field angle of the optical system can be reasonably configured, which is beneficial to shortening the total length of the optical system, realizing miniaturization design, and simultaneously enabling the optical system to have a large field angle characteristic, thereby being capable of acquiring more scene contents and enriching the imaging information of the optical system. When the lower limit of the relational expression is lower, the total length of the optical system is too large, which is not beneficial to the miniaturization design of the optical system; when it is higher than the upper limit of the relation, the structure of the optical system is too compact, so that aberration correction becomes difficult, thereby easily causing a decrease in imaging performance.

In a second aspect, the present invention further provides a lens module, which includes the optical system of any one of the embodiments of the first aspect and a photosensitive chip disposed on an image side of the optical system. The optical system provided by the invention is added into the lens module, and the lens module has the characteristics of large image surface and high pixels by reasonably designing the surface shape and the bending force of each lens in the optical system, so that the high-quality imaging effect can be realized.

In a third aspect, the present invention further provides an electronic device, which includes a housing and the lens module of the second aspect, wherein the lens module is disposed in the housing. By adding the lens module provided by the invention into the electronic equipment, the miniaturized lens module design can save more space for installing other devices while the electronic equipment has a high-quality imaging effect.

First embodiment

Referring to fig. 1 and fig. 2, the optical system of the present embodiment, in order from an object side to an image side, includes:

the first lens element L1 with positive refractive power has a convex object-side surface S1 at the paraxial region 101 and a concave image-side surface S2 at the paraxial region 101 of the first lens element L1.

The second lens element L2 with negative refractive power has an object-side surface S3 with a convex surface at a paraxial region 101 and an image-side surface S4 with a concave surface at the paraxial region 101 of the second lens element L2.

The third lens element L3 with negative refractive power has a convex object-side surface S5 at the paraxial region 101 and a concave image-side surface S6 at the paraxial region 101 of the third lens element L3.

The fourth lens element L4 has positive refractive power, and 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 convex at the paraxial region 101.

The fifth lens element L5 with negative refractive power has a concave object-side surface S9 at the paraxial region 101 and a convex image-side surface S10 at the paraxial region 101 of the fifth lens element L5.

The sixth lens element L6 has positive refractive power, and the object-side surface S11 of the sixth lens element L6 is convex at a paraxial region 101 and the image-side surface S12 is concave at a paraxial region 101.

The seventh lens element L7 with negative refractive power has a convex object-side surface S13 at the paraxial region 101 and a concave image-side surface S14 at the paraxial region 101 of the seventh lens element L7.

Further, the optical system includes a stop STO, a filter IR, and an imaging surface IMG. In the present embodiment, the stop STO is provided between the first lens L1 and the object to control the amount of light entering, but in other embodiments, the stop STO may be provided between two lenses, for example, between the first lens L1 and the second lens L2. The filter IR may be an infrared cut filter, disposed between the seventh lens L7 and the imaging surface IMG, and including an object side surface S15 and an image side surface S16, and is configured to filter infrared light, so that the light incident on the imaging surface IMG is visible light with a wavelength of 380nm to 780 nm. The infrared cut filter IR is made of GLASS (GLASS), and may be coated on the lens, but in other embodiments, the filter IR may also be an infrared pass filter for filtering visible light, only allowing infrared light to pass, and may be used for infrared camera shooting. The first lens L1 to the seventh lens L7 are made of plastic, and in other embodiments, the lens materials may be glass or a mixture of glass and plastic, i.e., some of the lenses are made of plastic and the other lenses are made of glass. The effective pixel area of the photosensitive chip is located on the imaging surface IMG.

Table 1a shows a table of characteristics of the optical system of the present embodiment, in which the reference wavelength of the focal length of the lens is 555nm, the reference wavelengths of the refractive index and the abbe number of the lens are 587.5618nm, and the Y radius in table 1a is the radius of curvature of the object-side surface or the image-side surface of the corresponding surface number at the optical axis 101. 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 value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 101, and the second value is the distance from the image-side surface of the lens element to the next optical surface (the object-side surface or stop surface of the next lens element) along the optical axis 101. The units of the Y radius, thickness and effective focal length are millimeters (mm).

TABLE 1a

Wherein f is an effective focal length of the optical system, Fno is an f-number of the optical system, HFOV is a half of a maximum field angle of the optical system, and TTL is a distance from an object-side surface of the first lens element to an image plane IMG of the optical system on the optical axis 101.

In this embodiment, the object-side surface and the image-side surface of the first lens element L1 through the seventh lens element L7 are aspheric, and in other embodiments, the object-side surface and the image-side surface of the first lens element L1 through the seventh lens element L7 may be both spherical or a combination of spherical and aspheric surfaces, for example, the object-side surface S1 and the image-side surface S2 are aspheric. Aspheric surface profile x can be defined using, but not limited to, the following aspheric surface formula:

where x is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, h is the distance from the corresponding point on the aspheric surface to the optical axis 101, c is the curvature of the aspheric surface vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the higher-order term in the aspheric surface profile formula. Table 1b gives the high-order term coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20, which can be used for the aspherical mirrors S1 to S14 in the first embodiment.

TABLE 1b

Fig. 2 (a) shows a longitudinal spherical aberration diagram of the optical system of the first embodiment at wavelengths of 650.0000nm, 555.0000nm, and 470.0000nm, in which the abscissa in the X-axis direction represents the focus shift, the ordinate in the Y-axis direction represents the normalized field of view, and the longitudinal spherical aberration diagram represents the convergent focus deviation of light rays of different wavelengths after passing through the respective lenses of the optical system. As can be seen from fig. 2 (a), the spherical aberration value of the optical system in the first embodiment is better, which illustrates that the imaging quality of the optical system in this embodiment is better.

Fig. 2 (b) also shows an astigmatism graph of the optical system of the first embodiment at a wavelength of 555.0000nm, in which the abscissa in the X-axis direction represents the focus shift and the ordinate in the Y-axis direction represents the image height in mm. T in the astigmatism graph represents the curvature of the imaging plane IMG in the meridional direction, and S represents the curvature of the imaging plane IMG in the sagittal direction. As can be seen from (b) of fig. 2, astigmatism of the optical system is well compensated.

Fig. 2 (c) also shows a distortion curve of the optical system of the first embodiment at a wavelength of 555.0000 nm. The abscissa along the X-axis direction represents the focus offset, the ordinate along the Y-axis direction represents the image height, and the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from (c) in fig. 2, the distortion of the optical system is well corrected at a wavelength of 587.5618 nm.

As can be seen from (a), (b), and (c) in fig. 2, the optical system of the present embodiment has small aberration, good imaging quality, and good imaging quality.

Second embodiment

Referring to fig. 3 and 4, the optical system of the present embodiment, in order from an object side to an image side, includes:

The third lens element L3 with positive refractive power has a convex object-side surface S5 at the paraxial region 101 and a concave image-side surface S6 at the paraxial region 101 of the third lens element L3.

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

The fifth lens element L5 has negative refractive power, and 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 seventh lens element L7 with negative refractive power has a concave object-side surface S13 at the paraxial region 101 and a concave image-side surface S14 at the paraxial region 101 of the seventh lens element L7.

Other structures of the second embodiment are the same as those of the first embodiment, and reference may be made thereto.

Table 2a shows a table of characteristics of the optical system of this embodiment, and the meaning of each parameter is the same as that of each parameter of the first embodiment, which is not described herein again.

TABLE 2a

Table 2b gives the coefficients of high order terms that can be used for each aspherical mirror in the second embodiment, wherein each aspherical mirror type can be defined by the formula given in the first embodiment.

TABLE 2b

Fig. 4 shows a longitudinal spherical aberration graph (a), an astigmatism graph (b), and a distortion graph (c) of the optical system of the second embodiment, in which the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the respective lenses of the optical system; t in the astigmatism graph represents the curvature of the imaging plane IMG in the meridional direction, and S represents the curvature of the imaging plane IMG in the sagittal direction; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 4, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 5 and fig. 6, in the optical system of the present embodiment, an object side to an image side sequentially include:

Other structures of the third embodiment are the same as those of the first embodiment, and reference may be made thereto.

Table 3a shows a table of characteristics of the optical system of this embodiment, and the meaning of each parameter is the same as that of each parameter of the first embodiment, which is not described herein again.

TABLE 3a

Table 3b gives the coefficients of high-order terms that can be used for each aspherical mirror surface in the third embodiment, wherein each aspherical mirror surface type can be defined by the formula given in the first embodiment.

TABLE 3b

Fig. 6 shows a longitudinal spherical aberration diagram (a), an astigmatism diagram (b), and a distortion diagram (c) of the optical system of the third embodiment, in which the longitudinal spherical aberration diagrams represent the convergent focus deviations of light rays of different wavelengths after passing through the respective lenses of the optical system; t in the astigmatism graph represents the curvature of the imaging plane IMG in the meridional direction, and S represents the curvature of the imaging plane IMG in the sagittal direction; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 6, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Fourth embodiment

Referring to fig. 7 and 8, in the optical system of the present embodiment, the object side to the image side sequentially include:

The fifth lens element L5 with positive refractive power has a concave object-side surface S9 at the paraxial region 101 and a convex image-side surface S10 at the paraxial region 101 of the fifth lens element L5.

The sixth lens element L6 has positive refractive power, and the object-side surface S11 and the image-side surface S12 of the sixth lens element L6 are convex at the paraxial region 101 and convex at the paraxial region 101, respectively.

Other structures of the fourth embodiment are the same as those of the first embodiment, and reference may be made thereto.

Table 4a shows a table of characteristics of the optical system of this embodiment, and the meaning of each parameter is the same as that of each parameter of the first embodiment, which is not described herein again.

TABLE 4a

Table 4b gives the coefficients of high-order terms that can be used for each aspherical mirror surface in the fourth embodiment, wherein each aspherical mirror surface type can be defined by the formula given in the first embodiment.

TABLE 4b

Fig. 8 shows a longitudinal spherical aberration diagram (a), an astigmatism diagram (b), and a distortion diagram (c) of the optical system of the fourth embodiment, in which the longitudinal spherical aberration diagrams represent the convergent focus deviations of light rays of different wavelengths after passing through the respective lenses of the optical system; t in the astigmatism graph represents the curvature of the imaging plane IMG in the meridional direction, and S represents the curvature of the imaging plane IMG in the sagittal direction; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 8, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Fifth embodiment

Referring to fig. 9 and 10, the optical system of the present embodiment, in order from an object side to an image side, includes:

The other structure of the fifth embodiment is the same as that of the first embodiment, and reference may be made thereto.

Table 5a shows a table of characteristics of the optical system of this embodiment, and the meaning of each parameter is the same as that of each parameter of the first embodiment, which is not described herein again.

TABLE 5a

Table 5b shows the high-order term coefficients that can be used for each aspherical mirror in the fifth embodiment, wherein each aspherical mirror type can be defined by the formula given in the first embodiment.

TABLE 5b

Fig. 10 shows a longitudinal spherical aberration diagram (a), an astigmatism diagram (b), and a distortion diagram (c) of the optical system of the fifth embodiment, in which the longitudinal spherical aberration diagrams represent the convergent focus deviations of light rays of different wavelengths after passing through the respective lenses of the optical system; t in the astigmatism graph represents the curvature of the imaging plane IMG in the meridional direction, and S represents the curvature of the imaging plane IMG in the sagittal direction; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 10, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Table 6 shows 6.5mm in the optical systems of the first to fifth embodiments<f*tan(HFOV)<7mm、6.2mm<Imgh²/f<7.4mm、0.9<Imgh/f<1.1、2.6deg/mm<HFOV/(Fno*TTL)<3.2deg/mm、3.4mm<f/Fno<4mm、23deg<HFOV/Fno<26.5deg、0<|f123/f3|<1、1<f123/f<3、0.25<SD11/Imgh<0.5、0.9<f4/f1<1.5、0.8<R52/R51<2.3、|(R51-R52)/(R51+R52)|<0.4、37<|f2/CT2|<52、0.8<CT1/(CT2+CT3)<1.3、0.9<|SAG71|/CT7<5、1.3<(f1+f2)/f7<2、4.8deg/mm<HFOV/TTL<A value of 5.6 deg/mm.

TABLE 6

The optical system provided by each embodiment can realize the miniaturization design of the structure and has the characteristics of large image plane and high pixel.

Referring to fig. 11, an embodiment of the invention further provides a lens module 20, where the lens module 20 includes an optical system and a photo sensor chip in any of the embodiments, and the photo sensor chip is disposed on an image side of the optical system, and both of the photo sensor chip and the photo sensor chip can be fixed by a bracket. The photosensitive chip may be a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor. Generally, the imaging plane IMG of the optical system overlaps the photosensitive surface of the photosensitive chip when assembled. By adopting the optical system, the lens module 20 has the characteristics of large image plane and high pixel while realizing the structure miniaturization design, and can realize the high-quality imaging effect.

Referring to fig. 12, an embodiment of the present invention further provides an electronic device 30. The electronic device 30 includes a housing 310 and the lens module 20 in the foregoing embodiments, the lens module 20 is mounted on the housing 310, and the housing 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 biometric device (such as a fingerprint recognition device or a pupil recognition device), a PDA (Personal Digital Assistant), and the like. Since the lens module 20 can maintain good image quality while the overall length is reduced, when the lens module 20 is used, the electronic device 30 can assemble the lens module 20 in a smaller space, so that the thickness of the device can be reduced and a high-quality image can be obtained.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. An optical system, wherein a number of the lenses having a bending force is seven, and the optical system, in order from an object side to an image side along an optical axis, comprises:

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, the second lens element having a convex object-side surface at a paraxial region and a concave image-side surface at a 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 positive refractive power, an image-side surface of the fourth lens element being convex at a paraxial region;

a fifth lens element with a bending power, an object-side surface of the fifth lens element being concave at a paraxial region and an image-side surface of the fifth lens element being convex at a paraxial region;

a sixth lens element with positive refractive power, an object-side surface of the sixth lens element being convex at a paraxial region;

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

the optical system satisfies the relation: 6.2mm<Imgh²/f<7.4mm；

Wherein f is the effective focal length of the optical system, and Imgh is half of the maximum field angle corresponding image height of the optical system.

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

3.4mm<f/Fno<4mm；

wherein Fno is an f-number of the optical system.

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

6.5mm<f*tan(HFOV)<7mm；

wherein the HFOV is half of a maximum field angle of the optical system.

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

23deg<HFOV/Fno<26.5deg；

wherein, HFOV is half of the maximum field angle of the optical system, Fno is the f-number of the optical system.

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

0<|f123/f3|<1；

wherein f123 is a combined focal length of the first lens to the third lens, and f3 is an effective focal length of the third lens.

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

37<|f2/CT2|<52；

wherein f2 is the effective focal length of the second lens element, and CT2 is the thickness of the second lens element on the optical axis.

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

1.3<(f1+f2)/f7<2；

wherein f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f7 is the effective focal length of the seventh lens.

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

4.8deg/mm<HFOV/TTL<5.6deg/mm；

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.

9. A lens module comprising a photo-sensitive chip and the optical system of any one of claims 1 to 8, wherein the photo-sensitive chip is disposed on an image side of the optical system.

10. An electronic apparatus, characterized in that the electronic apparatus comprises a housing and the lens module according to claim 9, the lens module being disposed in the housing.