CN114740592A

CN114740592A - Optical system, lens module and electronic equipment

Info

Publication number: CN114740592A
Application number: CN202210193577.3A
Authority: CN
Inventors: 曾晗; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2022-02-28
Filing date: 2022-02-28
Publication date: 2022-07-12
Anticipated expiration: 2042-02-28
Also published as: CN114740592B

Abstract

An optical system, a lens module and an electronic device, the optical system comprises seven lenses with bending force, and the relationship formula is satisfied: 18deg < HFOV/FNO <21 deg; wherein, HFOV is half of the maximum field angle of the optical system, FNO is the f-number of the optical system. The optical system, the lens module and the electronic equipment provided by the embodiment of the invention can meet the requirements of miniaturization and large light flux.

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. For example, the design of mounting an optical lens under a screen is increasing, and the design of a miniaturized optical lens under a screen affects the amount of light entering, and particularly, the imaging quality is significantly reduced in environments with insufficient amount of light entering, such as dusk and rainy days, so how to increase the amount of light entering the optical lens while satisfying the miniaturization becomes a key problem.

Disclosure of Invention

An object of the present invention is to provide an optical system, a lens module, and an electronic apparatus, which can satisfy the characteristics of miniaturization and large light flux.

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, comprising, in order from an object side to an image side along an optical axis: a first lens having a positive refracting power; the object side surface of the first lens element is convex at a paraxial region, and the image side surface of the first lens element is concave at a paraxial region; a second lens having a negative bending force; the object side surface of the second lens element is convex at a paraxial region, and the image side surface of the second lens element is concave at a paraxial region; a third lens having a bending force; the image side surface of the third lens is concave at a paraxial region; a fourth lens having a bending force; the object side surface of the fourth lens element is concave at a paraxial region, and the image side surface of the fourth lens element is convex at a paraxial region; a fifth lens element with a refractive power, an image-side surface of the fifth lens element being concave at a paraxial region; a sixth lens having a positive refracting power; the object side surface of the sixth lens element is convex at a paraxial region, and the image side surface of the sixth lens element is convex at a paraxial region; a seventh lens having a negative refracting power; the image side surface of the seventh lens element is concave at the paraxial region; the optical system satisfies the relation: 18deg < HFOV/FNO <21 deg; wherein, HFOV is half of the maximum field angle of the optical system, and FNO is the f-number of the optical system.

By arranging the first lens with positive bending force, the object side surface of the first lens is convex at the paraxial region, and the image side surface of the first lens is concave, incident light can be effectively converged, so that 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. And the first lens with positive bending force and the second lens with negative bending force are matched, so that the aberration generated by each other can be mutually counteracted. The third lens to the fifth lens have bending force, so that the bending force distribution of the optical system can be balanced, and the excessive bending force pressure of the front lens (namely the first lens and the second lens) and the rear lens (namely the sixth lens and the seventh lens) is avoided, so that the aberration which is difficult to correct is avoided from being generated among the lenses; meanwhile, the concave surface of the image side surface of the third lens element at the paraxial region, the concave surface of the object side surface of the fourth lens element at the paraxial region, and the concave surface of the image side surface of the fifth lens element at the paraxial region are favorable for smooth transition of light so as to smoothly transmit incident light converged by the front lens element to the rear lens element, and the reasonable matching of the surface types of the third lens element and the fifth lens element is favorable for reducing the risk caused by ghost images (additional images generated near the imaging surface of the optical system due to secondary reflection of light by the lens surface, generally darker brightness, and staggered with the original images). The sixth lens has positive bending force, and the positive bending force and the negative bending force of the seventh lens are mutually balanced, so that the aberration of the optical system can be corrected. The double convex surface type of the sixth lens element near the optical axis is advantageous for compressing the back focal length of the optical system, thereby shortening the total length of the optical system. And the concave surface shape of the image side surface of the seventh lens at the position of the paraxial region is matched to be beneficial to enabling marginal view field light to effectively enter the imaging surface, so that the relative brightness of the imaging surface is improved, and the imaging quality of the optical system is further improved.

When the relational expression is satisfied, the optical system can have a reasonable ratio of the field angle to the diaphragm number, so that the requirements of the design difficulty and the field angle of the large diaphragm are considered, the optical system has a larger field angle, the large diaphragm characteristic is satisfied, the large-field-angle shooting is satisfied, and the large-light-passing energy is provided, so that the imaging requirements of the optical system on high image quality and high definition are satisfied. When the angle of view of the optical system is lower than the lower limit of the relational expression, the requirement of the optical system on the field of view range is not met, the caliber of the object side surface of the first lens is easy to reduce, the tolerance sensitivity of the optical system is not favorably reduced, and in addition, the light transmission quantity of the optical system is insufficient, so that the precision of the optical system for capturing images is not high, and the design requirement of the optical system for high-resolution imaging quality is not favorably met; when the relative light intensity of the central field of view of the optical system is too large, the relative light intensity of the periphery of the imaging surface is insufficient, which is not favorable for high-resolution imaging of the optical system and reduces the imaging quality.

In one embodiment, the optical system satisfies the relationship: 1.52< TTL/IMGH < 1.75; wherein, TTL is a distance on an optical axis from the object-side surface of the first lens element to the imaging surface of the optical system, and IMGH is a half of a maximum field angle of the optical system corresponding to the image height. When the relation is satisfied, the optical system has a shorter optical total length, and simultaneously can support a photosensitive chip with a larger mounting size, thereby meeting the actual requirement of portable equipment on the reduction of the thickness of the optical system, simultaneously satisfying the characteristics of a large image plane and being beneficial to high-quality imaging. In addition, in this scope interval, be favorable to reducing optical system's chief ray angle (CRA, incident angle on marginal visual field chief ray reachs the imaging surface), be convenient for with sensitization chip chief ray angle phase-match, improve the imaging resolution, lens have simultaneously enough arrange with the face type space that changes, can effectively correct the aberration to promote optical system's imaging performance, reduce the tolerance sensitivity. When the optical length is lower than the lower limit of the relational expression, the optical total length of the optical system is too small, the lens arrangement space is narrow, the design difficulty is high, meanwhile, the tolerance sensitivity among the lenses is difficult to reduce, the production process risk is extremely high, and the practicability of the optical system is low; when the upper limit of the relational expression is exceeded, the total optical length of the optical system is too large to meet the demand for miniaturization in the market.

In one embodiment, the optical system satisfies the relationship: 0.5< CTAL/BL < 0.7; wherein CTAL is the sum of the thicknesses of the first lens element to the seventh lens element on the optical axis, and BL is the distance between the object-side surface of the first lens element and the image-side surface of the seventh lens element on the optical axis. When the relation is satisfied, the thickness of the first lens to the seventh lens on the optical axis and the distance of the object side surface of the first lens to the image side surface of the seventh lens on the optical axis are reasonably configured, each lens has enough space for surface shape change, and enough arrangement space is provided among the lenses, which is beneficial to the injection molding and assembly of the lenses. When the distance between the object side surface of the first lens and the image side surface of the seventh lens on the optical axis is smaller than the lower limit of the relational expression, the arrangement is not compact, the miniaturization design is not facilitated, the back focal distance of the optical system is occupied, the marginal field light rays emitted from the image side surface of the seventh lens cannot be effectively converged on the imaging surface, and the large image surface of the optical system cannot be improved to match with a large-size photosensitive chip; when the distance between the object side surface of the first lens and the image side surface of the seventh lens is less than the optical axis, the lens clearance is insufficient, which is not favorable for assembling the lens.

In one embodiment, the optical system satisfies the relationship: 1.1< f12/f < 1.8; wherein f12 is a combined focal length of the first lens and the second lens, and f is an effective focal length of the optical system. When satisfying above-mentioned relational expression, the tortuous power intensity of first lens and second lens is suitable, is favorable to improving optical system's field curvature and distortion, and reasonable tortuous power intensity also can reduce the shaping and the processing degree of difficulty of first lens and second lens, and reasonable whole tortuous power can make optical system have the short focal characteristic, and then is favorable to shortening optical system overall length, realizes the miniaturization. When the refractive index is lower than the lower limit of the relational expression, the combined focal length of the first lens and the second lens is too large, the bending force is too strong, the bending force is excessively concentrated in the lenses close to the object side (namely the first lens and the second lens), aberration which is difficult to correct is easily generated, and the correction pressure of the image side lenses (the third lens to the seventh lens) is increased, so that the aberration of the optical system is difficult to correct, and the imaging quality of the optical system is not favorably improved; if the upper limit of the relational expression is exceeded, the effective focal length of the optical system becomes too long, and it is difficult to shorten the total length of the optical system, and it is difficult to realize a miniaturized design.

In one embodiment, the optical system satisfies the relationship: 0.3mm^-1<FNO/TTL<0.33mm^-1(ii) a Wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system. When the relation is satisfied, the optical system can simultaneously meet the design requirements of large aperture and miniaturization, and can provide enough light transmission quantity to satisfy the requirement of high-definition shooting. When the total length of the optical system is lower than the lower limit of the relational expression, the total length of the optical system is too large, the miniaturization of the system is not facilitated, and the light transmission quantity is too large under the condition of too low f-number, so that the edge view field is easy to generate the stray light which cannot be eliminated, and the dispersion or purple fringing and the like are caused; when surpassingWhen the upper limit of the relational expression is exceeded, the optical system cannot meet the requirement of a large aperture while meeting the requirement of miniaturization, so that the light transmission quantity is insufficient, and the image definition is reduced.

In one embodiment, the optical system satisfies the relationship: 2< | (R2F + R2R)/(R2F-R2R) | < 3.5; wherein R2F is a radius of curvature of the object-side surface of the second lens at the optical axis, and R2R is a radius of curvature of the image-side surface of the second lens at the optical axis. When the relation is satisfied, the curvature radius of the object side surface and the curvature radius of the image side surface of the second lens at the optical axis can be effectively restrained, the surface shape of the second lens is reasonably changed, and appropriate negative bending force can be provided for an optical system, so that the second lens can obtain enough light divergence capacity, stray light generated by the first lens can be eliminated, chromatic aberration can be corrected, the aberration balance of the optical system can be promoted, and good imaging quality can be obtained.

In one embodiment, the optical system satisfies the relationship: -5< F2/R2F < -1, wherein F2 is the effective focal length of the second lens and R2F is the radius of curvature of the object-side surface of the second lens at the optical axis. Satisfying above-mentioned relational expression, can retraining effective focal length and the radius of curvature of object side of second lens effectively, making second lens object side can not too crooked or too level in optical axis department, can provide suitable negative bending power for optical system equally to the second lens can obtain sufficient light and diverge the ability, thereby is favorable to eliminating the stray light that first lens produced, and then is favorable to correcting the colour difference, promotes optical system aberration's balance, in order to obtain good imaging quality.

In one embodiment, the optical system satisfies the relationship: l (R4F + R4R)/(R4F-R4R) | < 1.2; wherein R4F is a radius of curvature of the fourth lens object-side surface at the optical axis, and R4R is a radius of curvature of the fourth lens image-side surface at the optical axis. When satisfying above conditional expression, fourth lens body side has certain crooked degree, and simultaneously, the image side can not be too level and smooth, and the face type of fourth lens obtains reasonable optimization, can provide suitable bending force, rectifies the aberration of peripheral visual field betterly, promotes the image quality of peripheral visual field, and is favorable to reducing the risk that produces the ghost image. Meanwhile, the fourth lens is located in the middle of the optical system, so that the appropriate bending force can reduce the bending force burden of the front lenses (namely, the first lens to the third lens) and the rear lenses (namely, the fifth lens to the seventh lens), the design and assembly sensitivity of the optical system can be reduced, and the product yield can be improved.

In one embodiment, the optical system satisfies the relationship: 0.35< SD11/IMGH < 0.4; 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 then a proper light transmission amount can be obtained, so that the definition of a shot image is ensured. When the maximum effective half aperture of the object side surface of the first lens is too small, the light transmission quantity 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 too large, the light flux of the 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 affected.

In one embodiment, the optical system satisfies the relationship: 1.7< CT6/ET6< 2.8; wherein CT6 is the thickness of the sixth lens element along the optical axis, and ET6 is the thickness of the edge of the sixth lens element (i.e., the distance from the maximum effective diameter of the object-side surface of the sixth lens element to the maximum effective diameter of the image-side surface of the sixth lens element along the optical axis). When the conditional expressions are satisfied, the sixth lens has reasonable surface shape change, which can provide enough positive bending force for the optical system to balance the aberration generated by the first lens to the fifth lens, and meanwhile, the sixth lens also has proper thickness ratio, and the surface shape change is not too large or too small, thereby reducing the difficulty of molding and assembling the lenses. When the thickness of the sixth lens on the optical axis is too small below the lower limit of the relational expression, the positive bending force of the sixth lens is not enough to balance the aberration of the optical system, and the edge thickness of the sixth lens is too large, so that the incidence angle of the chief ray of the edge field of the optical system reaching the imaging surface is too large, and a dark angle is easily generated; when the thickness of the sixth lens exceeds the upper limit of the relational expression, the thickness difference of the sixth lens is too large, which is not favorable for manufacturing and processing the sixth lens and reduces the yield of lens molding.

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. By adding the optical system provided by the invention into the lens module and reasonably designing the surface shape and the bending force of each lens in the optical system, the lens module has the characteristics of miniaturization and large light transmission amount.

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 electronic equipment has larger light transmission amount so as to achieve clearer shooting effect, and meanwhile, the miniaturized lens module design can save more space for installing other devices.

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. 1a is a schematic view of the optical system structure of the first embodiment;

FIG. 1b includes the longitudinal spherical aberration plot, astigmatism plot, and distortion plot of the first embodiment;

FIG. 2a is a schematic structural diagram of an optical system according to a second embodiment;

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

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

FIG. 3b includes a plot of longitudinal spherical aberration, a plot of astigmatism and a plot of distortion for the third embodiment;

FIG. 4a is a schematic structural diagram of an optical system according to a fourth embodiment;

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

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

fig. 5b includes a plot of longitudinal spherical aberration, a plot of astigmatism and a plot of distortion for the fifth embodiment;

fig. 6 is a schematic view of a lens module according to an embodiment of the invention;

fig. 7 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 comprising, in order along an optical axis from an object side to an image side: a first lens having a positive refracting power; the object side surface of the first lens element is convex at a paraxial region, and the image side surface of the first lens element is concave at a paraxial region; a second lens having a negative bending force; the object-side surface of the second lens element is convex at paraxial region thereof, and the image-side surface thereof is concave at paraxial region thereof; a third lens having a bending force; the image side surface of the third lens is concave at the paraxial region; a fourth lens having a bending force; the object side surface of the fourth lens element is concave at a paraxial region, and the image side surface thereof is convex at a paraxial region; a fifth lens element with a refractive power, an image-side surface of the fifth lens element being concave at a paraxial region; a sixth lens having a positive refracting power; the sixth lens element has a convex object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a seventh lens having a negative refracting power; the image side surface of the seventh lens element is concave at the paraxial region; the optical system satisfies the relation: 18deg < HFOV/FNO <21 deg; wherein, HFOV is half of the maximum field angle of the optical system, FNO is the f-number of the optical system.

By arranging the first lens with positive bending force, the object side surface of the first lens is convex at the paraxial region, and the image side surface of the first lens is concave, the incident light can be effectively converged, so that 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. And 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. The third lens to the fifth lens have bending force, so that the bending force distribution of the optical system can be balanced, and the excessive bending force pressure of the front lens (namely the first lens and the second lens) and the rear lens (namely the sixth lens and the seventh lens) is avoided, so that the aberration which is difficult to correct is avoided from being generated among the lenses; meanwhile, the concave surface of the image side surface of the third lens element at the paraxial region, the concave surface of the object side surface of the fourth lens element at the paraxial region, and the concave surface of the image side surface of the fifth lens element at the paraxial region are favorable for smooth transition of light so as to smoothly transmit incident light converged by the front lens element to the rear lens element, and the reasonable matching of the surface types of the third lens element and the fifth lens element is favorable for reducing the risk caused by ghost images (additional images generated near the imaging surface of the optical system due to secondary reflection of light by the lens surface, generally darker brightness, and staggered with the original images). The sixth lens has positive bending force, and the positive bending force and the negative bending force of the seventh lens are mutually balanced, so that the aberration of the optical system can be corrected. The double convex surface type of the sixth lens element near the optical axis is advantageous for compressing the back focal length of the optical system, thereby shortening the total length of the optical system. And the concave surface shape of the image side surface of the seventh lens at the position of the paraxial region is matched to be beneficial to enabling marginal view field light to effectively enter the imaging surface, so that the relative brightness of the imaging surface is improved, and the imaging quality of the optical system is further improved.

In one embodiment, the optical system satisfies the relationship: 1.52< TTL/IMGH < 1.75; wherein, TTL is the distance on the optical axis from the object-side surface of the first lens element to the imaging surface of the optical system, and IMGH is half of the maximum field angle of the optical system corresponding to the image height. When the relation is satisfied, the optical system has shorter optical total length, and simultaneously can support the photosensitive chip with larger mounting size, thereby meeting the actual requirement of portable equipment on the reduction of the thickness of the optical system. Meanwhile, the large image surface characteristic is met, and high-quality imaging is facilitated. In addition, in this scope interval, be favorable to reducing optical system's chief ray angle (CRA, incident angle on marginal visual field chief ray reachs the imaging surface), be convenient for with sensitization chip chief ray angle phase-match, improve the imaging resolution, lens have simultaneously enough arrange with the face type space that changes, can effectively correct the aberration to promote optical system's imaging performance, reduce the tolerance sensitivity. When the optical length is lower than the lower limit of the relational expression, the optical total length of the optical system is too small, the lens arrangement space is narrow, the design difficulty is high, meanwhile, the tolerance sensitivity among the lenses is difficult to reduce, the production process risk is extremely high, and the practicability of the optical system is low; when the upper limit of the relation is exceeded, the total length of the optical system is too large to meet the demand for miniaturization of the market.

In one embodiment, the optical system satisfies the relationship: 0.5< CTAL/BL < 0.7; wherein CTAL is the sum of the thicknesses of the first lens and the seventh lens on the optical axis, and BL is the distance between the object-side surface of the first lens and the image-side surface of the seventh lens on the optical axis. When the relation is satisfied, the thicknesses of the first lens to the seventh lens on the optical axis and the distance from the object side surface of the first lens to the image side surface of the seventh lens on the optical axis are reasonably configured, each lens has enough space for surface shape change, and enough arrangement space is provided among the lenses, thereby being beneficial to injection molding and assembling of the lenses. When the distance between the object side surface of the first lens and the image side surface of the seventh lens on the optical axis is smaller than the lower limit of the relational expression, the arrangement is not compact, the miniaturization design is not facilitated, the back focal distance of the optical system is occupied, the marginal field light rays emitted from the image side surface of the seventh lens cannot be effectively converged on the imaging surface, and the large image surface of the optical system cannot be improved to match with a large-size photosensitive chip; when the distance between the object side surface of the first lens and the image side surface of the seventh lens is less than the optical axis, the lens clearance is insufficient, which is not favorable for assembling the lens.

In one embodiment, the optical system satisfies the relationship: 1.1< f12/f < 1.8; where f12 is the combined focal length of the first lens and the second lens, and f is the effective focal length of the optical system. When satisfying above-mentioned relational expression, the tortuous power intensity of first lens and second lens is suitable, is favorable to improving optical system's field curvature and distortion, and reasonable tortuous power intensity also can reduce the shaping and the processing degree of difficulty of first lens and second lens, and reasonable whole tortuous power can make optical system have the short focal characteristic, and then is favorable to shortening optical system overall length, realizes the miniaturization. When the refractive index is lower than the lower limit of the relational expression, the combined focal length of the first lens and the second lens is too large, the bending force is too strong, the bending force is excessively concentrated in the lenses close to the object side (namely the first lens and the second lens), aberration which is difficult to correct is easily generated, and the correction pressure of the image side lenses (the third lens to the seventh lens) is increased, so that the aberration of the optical system is difficult to correct, and the imaging quality of the optical system is not favorably improved; when the upper limit of the relational expression is exceeded, the effective focal length of the optical system is too long, the total length of the optical system is shortened, and miniaturization is achieved.

In one embodiment, the optical system satisfies the relationship: 0.3mm^-1<FNO/TTL<0.33mm^-1(ii) a Wherein, TTL is a distance on the optical axis from the object-side surface of the first lens element to the imaging surface of the optical system. When the relation is satisfied, the optical system can simultaneously meet the design requirements of large aperture and miniaturization, and can provide enough light transmission quantity to satisfy the requirement of high-definition shooting. When the total length of the optical system is lower than the lower limit of the relational expression, the total length of the optical system is too large, the miniaturization of the system is not facilitated, and the light transmission quantity is too large under the condition of too low f-number, so that the edge view field is easy to generate the stray light which cannot be eliminated, and the dispersion or purple fringing and the like are caused; when the upper limit of the relational expression is exceeded, the optical system cannot meet the requirement of a large aperture while satisfying miniaturization, so that the light transmission amount is insufficient, and the image definition is reduced.

In one embodiment, the optical system satisfies the relationship: 2< | (R2F + R2R)/(R2F-R2R) | < 3.5; wherein, R2F is the curvature radius of the object-side surface of the second lens at the optical axis, and R2R is the curvature radius of the image-side surface of the second lens at the optical axis. When the relation is satisfied, the curvature radius of the object side surface and the image side surface of the second lens at the optical axis can be effectively restrained, the surface shape of the second lens is reasonable in change, appropriate negative bending force can be provided for the optical system, the second lens can obtain enough light divergence capacity, stray light generated by the first lens can be eliminated, chromatic aberration can be corrected, the balance of optical system aberration is promoted, and good imaging quality is obtained.

In one embodiment, the optical system satisfies the relationship: -5< F2/R2F < -1, wherein F2 is the effective focal length of the second lens and R2F is the radius of curvature of the object-side surface of the second lens at the optical axis. Satisfy above-mentioned relational expression, can restrain the effective focal length of second lens and the radius of curvature of object side effectively, make second lens object side can not too crooked or too level in optical axis department, equally can provide suitable negative bending power for optical system to the second lens can obtain sufficient light and diverge the ability, thereby is favorable to eliminating the stray light that first lens produced, and then is favorable to correcting the colour difference, promotes the balance of optical system aberration, with the formation of image quality that obtains well.

In one embodiment, the optical system satisfies the relationship: l (R4F + R4R)/(R4F-R4R) | < 1.2; wherein, R4F is the radius of curvature of the object-side surface of the fourth lens element at the optical axis, and R4R is the radius of curvature of the image-side surface of the fourth lens element at the optical axis. When the conditional expressions above are satisfied, the object side surface of the fourth lens has a certain bending degree, meanwhile, the image side surface is not too flat, the surface type of the fourth lens is reasonably optimized, appropriate bending force can be provided, the aberration of the peripheral field of view is well corrected, the image quality of the peripheral field of view is improved, and the risk of generating ghost images is reduced. Meanwhile, the fourth lens is located in the middle of the optical system, so that the appropriate bending force can reduce the bending force burden of the front lenses (namely the first lens to the third lens) and the rear lenses (namely the fifth lens to the seventh lens), the design and assembly sensitivity of the optical system can be favorably reduced, and the product yield can be favorably improved.

In one embodiment, the optical system satisfies the relationship: 0.35< SD11/IMGH < 0.4; 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 then a proper light transmission amount can be obtained, so that the definition of a shot image is ensured. When the maximum effective half aperture of the object side surface of the first lens is too small, the light transmission quantity 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 too large, the light flux of the 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 affected.

In one embodiment, the optical system satisfies the relationship: 1.7< CT6/ET6< 2.8; wherein CT6 is the thickness of the sixth lens element along the optical axis, and ET6 is the thickness of the edge of the sixth lens element (i.e., the distance from the maximum effective diameter of the object-side surface of the sixth lens element to the maximum effective diameter of the image-side surface of the sixth lens element along the optical axis). When the conditional expressions are satisfied, the sixth lens has reasonable surface shape change, and can provide enough positive bending force for the optical system to balance the aberration generated by the first lens to the fifth lens, and meanwhile, the sixth lens also has a proper thickness ratio, and the surface shape change is not too large or too small, so that the molding and assembling difficulty of the lenses is reduced. When the thickness of the sixth lens on the optical axis is too small below the lower limit of the relational expression, the positive bending force of the sixth lens is not enough to balance the aberration of the optical system, and the edge thickness of the sixth lens is too large, so that the incidence angle of the chief ray of the edge field of the optical system reaching the imaging surface is too large, and a dark angle is easily generated; when the thickness of the sixth lens exceeds the upper limit of the relational expression, the thickness difference of the sixth lens is too large, which is not favorable for manufacturing and processing the sixth lens and reduces the yield of lens molding.

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. By adding the optical system provided by the invention into the lens module and reasonably designing the surface shape and the bending force of each lens in the optical system, the lens module has the characteristics of miniaturization and large light transmission amount.

In a third aspect, the present invention further provides an electronic device, which includes a housing and the lens module of the second aspect, and the lens module is disposed in the housing. By adding the lens module provided by the invention into the electronic equipment, the electronic equipment has larger light transmission amount so as to achieve clearer shooting effect, and meanwhile, the miniaturized lens module design can save more space for installing other devices.

First embodiment

Referring to fig. 1a and fig. 1b, 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 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 with negative refractive power has a concave object-side surface S9 at the paraxial region 101 and a concave 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.

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.

Further, the optical system includes a stop STO, a filter IR, and an imaging surface IMG. In this embodiment, the stop STO is disposed in front of the first lens L1 for controlling the amount of light entering, but in other embodiments, the stop STO may be disposed between two lenses, for example, between the first lens L1 and the second lens L2. The optical filter IR may be an infrared cut filter, disposed between the seventh lens element L7 and the imaging surface IMG, and including an object side surface S15 and an image side surface S16, and is configured to filter out infrared light, so that the light incident on the imaging surface IMG is visible light, and the wavelength of the visible light is 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 element is located on the imaging plane 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. The surface numbers S1 and S2 are the object side surface S1 and the image side surface S2 of the first lens L1, i.e., the surface with the smaller surface number is the object side surface and the surface with the larger surface number is the image side surface in the same lens. 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 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 imaging surface 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:

wherein 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 i-th high-order term in the aspheric surface type formula. Table 1b shows the high-order coefficient a4, a6, A8, a10, a12, a14, a16, a18, and a20 that can be used for the aspherical mirror surfaces S1 to S14 in the first embodiment.

TABLE 1b

Fig. 1b (a) shows a longitudinal spherical aberration curve of the optical system of the first embodiment at wavelengths of 656.2725nm, 587.5618nm and 486.1327nm, wherein 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 curve represents the convergent focus deviation of light rays of different wavelengths after passing through the lenses of the optical system. As can be seen from fig. 1b (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. 1b (b) also shows a graph of astigmatism of the optical system of the first embodiment at a wavelength of 587.5618nm, in which the abscissa in the X-axis direction represents the focus offset and the ordinate in the Y-axis direction represents the image height in mm. In the astigmatism graph, T 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 fig. 1b (b), astigmatism of the optical system is well compensated.

Fig. 1b (c) also shows a distortion curve of the optical system of the first embodiment at a wavelength of 587.5618 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 fig. 1b (c), 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. 1b, the optical system of the present embodiment has small aberration, good imaging quality and good imaging quality.

Second embodiment

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

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

The third lens element L3 has positive refractive power, and 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 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 with negative refractive power has a convex object-side surface S9 at the paraxial region 101 and a concave image-side surface S10 at the paraxial region 101 of the fifth lens element L5.

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 the present embodiment, in which the reference wavelength of the focal length of the lens is 555nm, the reference wavelength of the refractive index and abbe number of the lens is 587.5618nm, and the radius Y in table 2a 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. The surface numbers S1 and S2 are the object side surface S1 and the image side surface S2 of the first lens L1, i.e., the surface with the smaller surface number is the object side surface and the surface with the larger surface number is the image side surface in the same lens. 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 radius Y, the thickness and the effective focal length are millimeters (mm), and the meaning of each parameter is the same as that of the first embodiment.

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. 2b shows a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system of the second embodiment, wherein the longitudinal spherical aberration diagrams represent the deviation of the convergent focus of the light rays with different wavelengths after passing through the 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. 2b, the longitudinal spherical aberration, the curvature of field and the 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. 3a and fig. 3b, the optical system of the present embodiment, in order from an object side to an image side, includes:

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 sixth lens element L6 has positive refractive power, and 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.

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 the present embodiment, in which the reference wavelength of the focal length of the lens is 555nm, the reference wavelength of the refractive index and abbe number of the lens is 587.5618nm, and the radius Y in table 3a 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 radius Y, the thickness and the effective focal length are millimeters (mm), and the other parameters have the same meanings as those of the first embodiment.

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. 3b shows a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system of the third embodiment, wherein the longitudinal spherical aberration diagrams represent the convergent focus deviations of light rays of different wavelengths after passing through the 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. 3b, 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. 4a and 4b, 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 a paraxial region 101 and a concave image-side surface S2 at a paraxial region 101 of the first lens element L1.

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

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

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

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 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 4a 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 radius Y, the thickness and the effective focal length are all millimeters (mm), and the other parameters have the same meanings as those of the first embodiment.

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. 4b shows a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system of the fourth embodiment, wherein the longitudinal spherical aberration diagrams represent the convergent focus deviations of light rays of different wavelengths after passing through the 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. 4b, 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. 5a and 5b, the optical system of the present embodiment, in order from an object side to an image side, includes:

The third lens element L3 with negative refractive power has a concave 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 fifth lens element L5 with positive refractive power has a convex object-side surface S9 at the paraxial region 101 and a concave image-side surface S10 at the paraxial region 101 of the fifth lens element L5.

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.

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 the present embodiment, in which the reference wavelength of the focal length of the lens is 555nm, the reference wavelength of the refractive index and abbe number of the lens is 587.5618nm, and the radius Y in table 5a 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 radius Y, the thickness and the effective focal length are all millimeters (mm), wherein the other parameters have the same meanings as those of the first embodiment.

TABLE 5a

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

TABLE 5b

FIG. 5b shows a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system of the fifth embodiment, wherein the longitudinal spherical aberration diagrams represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; t in the astigmatism graph represents the curvature of the imaging plane 101 in the meridional direction, and S represents the curvature of the imaging plane 101 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. 5b, the longitudinal spherical aberration, the curvature of field and the distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Table 6 shows 18deg in the optical systems of the first to fifth embodiments<HFOV/FNO<21deg、1.52<TTL/IMGH<1.75、0.5<CTAL/BL<0.7、1.1<f12/f<1.8、0.3mm^-1<FNO/TTL<0.33mm^-1、2<|(R2F+R2R)/(R2F-R2R)|<3.5、-5<F2/R2F<-1、|(R4F+R4R)/(R4F-R4R)|<1.2、0.35<SD11/IMGH<0.4、1.7<CT6/ET6<A value of 2.8.

TABLE 6

Relation formula	First embodiment	Second embodiment	Third embodiment	Fourth embodiment	Fifth embodiment
						18deg<HFOV/FNO<21deg	20.497	20.949	20.389	19.011	18.195
1.52<TTL/IMGH<1.75	1.665	1.691	1.526	1.687	1.713
						0.5<CTAL/BL<0.7	0.631	0.67	0.572	0.572	0.548
1.1<f12/f<1.8	1.456	1.782	1.353	1.188	1.147
						0.3mm^-1<FNO/TTL<0.33mm^-1	0.309	0.304	0.328	0.319	0.327
2<\|(R2F+R2R)/(R2F-R2R)\|<3.5	2.501	2.996	2.914	3.021	2.889
						-5<F2/R2F<-1	-3.242	-1.557	-1.700	-1.514	-1.744
\|(R4F+R4R)/(R4F-R4R)\|<1.2	1.048	0.115	0.019	0.359	0.590
						0.35<SD11/IMGH<0.4	0.377	0.365	0.38	0.391	0.386
1.7<CT6/ET6<2.8	2.333	2.649	2.042	1.713	2.124

The optical system provided by each embodiment can realize the miniaturization design of the structure and simultaneously has larger light transmission quantity.

Referring to fig. 6, 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 can be designed to have a smaller structure and a larger light transmission amount.

Referring to fig. 7, 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 thereof 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 while having a wider shooting range.

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 comprising, in order along an optical axis from an object side to an image side:

a first lens having a positive refracting power; the object side surface of the first lens element is convex at a paraxial region, and the image side surface of the first lens element is concave at a paraxial region;

a second lens having a negative bending force; the object side surface of the second lens element is convex at a paraxial region, and the image side surface of the second lens element is concave at a paraxial region;

a third lens having a bending force; the image side surface of the third lens is concave at a paraxial region;

a fourth lens having a bending force; the object side surface of the fourth lens element is concave at a paraxial region, and the image side surface of the fourth lens element is convex at a paraxial region;

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

a sixth lens having a positive refracting power; the object side surface of the sixth lens element is convex at a paraxial region, and the image side surface of the sixth lens element is convex at a paraxial region;

a seventh lens having a negative refracting power; the image side surface of the seventh lens element is concave at the paraxial region;

the optical system satisfies the relation: 18deg < HFOV/FNO <21 deg;

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

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

1.52< TTL/IMGH < 1.75; and/or, 0.5< CTAL/BL < 0.7;

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

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

1.1<f12/f<1.8；

wherein f12 is a combined focal length of the first lens and the second lens, and f is an effective focal length of the optical system.

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

0.3mm^-1<FNO/TTL<0.33mm^-1；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system.

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

2< | (R2F + R2R)/(R2F-R2R) | < 3.5; and/or-5 < F2/R2F < -1;

wherein R2F is a radius of curvature of the object-side surface of the second lens element at the optical axis, R2R is a radius of curvature of the image-side surface of the second lens element at the optical axis, and F2 is an effective focal length of the second lens element.

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

|(R4F+R4R)/(R4F-R4R)|<1.2；

wherein R4F is a radius of curvature of the fourth lens object-side surface at the optical axis, and R4R is a radius of curvature of the fourth lens image-side surface at the optical axis.

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

0.35<SD11/IMGH<0.4；

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.

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

1.7<CT6/ET6<2.8；

wherein CT6 is the thickness of the sixth lens element on the optical axis, and ET6 is the edge thickness of the sixth lens element.

9. A lens module comprising the optical system of any one of claims 1 to 8 and a photo-sensor chip 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 set according to claim 9, the lens module set being disposed in the housing.