CN114815167B

CN114815167B - Optical system, camera module and electronic equipment

Info

Publication number: CN114815167B
Application number: CN202210587094.1A
Authority: CN
Inventors: 杨健; 华露
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2023-09-05
Anticipated expiration: 2042-05-27
Also published as: CN114815167A

Abstract

An optical system, a camera module and an electronic device, wherein the optical system sequentially comprises from an object side to an image side along an optical axis: the first lens element with refractive power has a first to seventh lens elements with negative refractive power, and the fourth and sixth lens elements with positive refractive power, wherein the object-side surface of the first lens element, the image-side surface of the second lens element, the image-side surface of the third lens element, the object-side surface of the fifth lens element and the image-side surface of the seventh lens element are concave at a paraxial region, and the image-side surface of the first lens element, the object-side surface of the second lens element, the object-side surface of the third lens element, the object-side surface and the image-side surface of the fourth lens element, and the image-side surface of the sixth lens element and the object-side surface of the seventh lens element are convex at a paraxial region. The surface type and the refractive power of each lens of the optical system are reasonably designed, so that the characteristics of larger angle of view, large aperture, small distortion and miniaturization are met.

Description

Optical system, camera module and electronic equipment

Technical Field

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

Background

In recent years, with the rise of portable electronic products with photographing functions, higher requirements are being placed on the quality and diversity of lens imaging, such as a larger angle of view, smaller image distortion, and a sufficient amount of light entering under dim environments. However, the improvement of imaging quality generally means that the structure of the optical system is more complex, which eventually results in an increase in the size and overall length of the lens, and is difficult to be applied to light and thin electronic products.

Therefore, how to optimize imaging quality, meet the requirements of large aperture, small distortion and miniaturization on the premise of ensuring that the optical system has a larger field angle becomes one of the problems that must be solved in the industry.

Disclosure of Invention

The invention aims to provide an optical system, an imaging module and electronic equipment, and solves the problems that the optical system in the prior art needs to meet the requirements of large aperture, small distortion and miniaturization on the premise of having a larger field angle.

In order to achieve 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 element with negative refractive power having a concave object-side surface at an optical axis and a convex image-side surface at a paraxial region; a second 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 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 having a convex object-side surface and a convex image-side surface at a paraxial region; a fifth lens element with negative refractive power having a concave object-side surface at a paraxial region; a sixth lens element with positive refractive power having a convex image-side surface at a paraxial region; a seventh lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the object side surface and the image side surface of the sixth lens and the seventh lens respectively comprise at least one inflection point.

The optical system satisfies the relation: 110 deg < FOV <121 deg, and/or 1.6< f/EPD <2.1; wherein FOV is the maximum field angle of the optical system, f is the focal length of the optical system, EPD is the entrance pupil diameter of the optical system.

The first lens element with negative refractive power has the advantages of increasing the incident angle of light rays, expanding the angle of view of an optical system, having a concave object-side surface at a paraxial region, having a convex image-side surface at a paraxial region, enhancing the negative refractive power, avoiding excessive bending of the object-side surface, and reducing spherical aberration and chromatic aberration; the second lens element with refractive power has a convex object-side surface at a paraxial region, and a concave image-side surface at a paraxial region, so that marginal ray deflection is facilitated, the workload born by the subsequent lens elements can be reduced, the deflection angles of the rays on the lens elements are uniform, and the aberration of a marginal field of view is effectively corrected; the object side surface of the third lens is made to be convex at the paraxial region, and the image side surface of the third lens is made to be concave at the paraxial region, so that a reasonable incident angle is further provided for marginal rays; the fourth lens element with positive refractive power has convex object-side and image-side surfaces at a paraxial region, so that the incidence angle of principal ray of light on the surface of the fourth lens element is reduced, and the transmittance is improved; the fifth lens element with negative refractive power has a concave object-side surface at a paraxial region, so as to facilitate correction of spherical aberration, coma aberration and distortion; the sixth lens element with positive refractive power has a convex image-side surface at a paraxial region, so that the total length of the optical system can be reduced and aberration can be corrected; the seventh lens element with negative refractive power has a convex object-side surface at a paraxial region, and a concave image-side surface at a paraxial region, so as to facilitate correction of distortion, astigmatism and field curvature, thereby meeting requirements of low aberration and high image quality. Therefore, the above-mentioned surface shape is satisfied, and the optical system is advantageous in realizing the effects of a large angle of view, a large aperture, miniaturization, and small distortion.

Through making optical system satisfy above-mentioned relational expression, be favorable to optical system to satisfy the effect of big angle of view, optical system possesses great aperture and higher light quantity, and then increases optical system's imaging under the dim environment, simultaneously, still is favorable to reducing the aberration of marginal visual field, guarantees that marginal visual field has sufficient relative brightness, avoids appearing the dark angle.

In one embodiment, the optical system satisfies the relationship: 4mm < SD11/tan (HFOV) <4.5mm; wherein SD11 is half of the maximum effective aperture of the object side surface of the first lens, HFOV is half of the maximum field angle of the optical system, and tan (HFOV) is the tangent of the half field angle of the optical system. The optical system meets the relation, so that the ratio of half of the maximum effective caliber of the object side surface of the first lens to the tangent value of the half field angle of the optical system is reasonably configured, the caliber of the first lens is effectively reduced, the size and occupied volume of the optical system are further reduced, the requirement of miniaturization of the optical system is met, and meanwhile, the optical system has a larger field angle and the shooting range is increased. And the caliber of the first lens is overlarge on the premise of having the same size of field angle exceeding the upper limit of the relation formula, and becomes a main factor for restricting the whole volume of the optical system, so that the miniaturization requirement of the optical system is not met, the structural arrangement of each lens in the optical system is not facilitated, and the risk of ghost images is increased.

In one embodiment, the optical system satisfies the relationship: 0.9< f123/f1<1.5; wherein f123 is a combined focal length of the first lens, the second lens and the third lens, and f1 is a focal length of the first lens. The optical system meets the relation, so that the refractive powers of the first lens, the second lens and the third lens are reasonably distributed, enough negative refractive power is provided for the optical system, the characteristics of large field angle and small distortion of the optical system are realized, the total length of the optical system is shortened, the processability of each lens is improved, and the molding difficulty of the lens is reduced.

In one embodiment, the optical system satisfies the relationship: 1.5< f45/f <2.5; wherein f45 is a combined focal length of the fourth lens and the fifth lens, and f is a focal length of the optical system. The optical system satisfies the relation, so that the refractive powers of the fourth lens and the fifth lens are reasonably distributed, the total length of the fourth lens and the fifth lens is shortened, the aberration generated by each lens before and after the fourth lens and the fifth lens is balanced, the characteristics of large aperture, large field angle and high imaging quality are realized, and meanwhile, the deflection angle of marginal field light rays is reduced, the sensitivity is reduced, the aberration balance is promoted, and the imaging quality is improved.

In one embodiment, the optical system satisfies the relationship: 1< R32/R41<2.8; wherein R32 is a radius of curvature of the image side surface of the third lens element at the optical axis, and R41 is a radius of curvature of the object side surface of the fourth lens element at the optical axis. By making the optical system satisfy the above-described relational expression, it is advantageous that the image side surface of the third lens element and the object side surface of the fourth lens element have a sufficient degree of freedom in bending, and aberration such as astigmatism and curvature of field of the optical system can be corrected better. The object side surface of the third lens is too bent below the lower limit of the relation, which is not beneficial to the processing and forming of the lens; exceeding the upper limit of the relation, the curvature of the object side surface of the third lens is insufficient, which is unfavorable for correction of aberration.

In one embodiment, the optical system satisfies the relationship: 1.5< R51/R42<3; wherein R51 is a radius of curvature of the object side surface of the fifth lens element at the optical axis, and R42 is a radius of curvature of the image side surface of the fourth lens element at the optical axis. The optical system meets the relation, so that the ratio of the curvature radius of the object side surface of the fifth lens to the curvature radius of the image side surface of the fourth lens at the optical axis is reasonably configured, the edge view field light obtains a more reasonable deflection angle, the aberration of the optical system is favorably corrected, the imaging quality is improved, and meanwhile, the machinability of the fourth lens and the fifth lens can be ensured. The object side surface of the fifth lens is too bent below the lower limit of the relation, which is not beneficial to the processing and forming of the lens; exceeding the upper limit of the relation, the curvature of the object side surface of the fifth lens element is insufficient, which is unfavorable for aberration correction.

In one embodiment, the optical system satisfies the relationship: 1< ct14/(SD 11-SD 41) <1.1; wherein, CT14 is the distance between the object side surface of the first lens and the object side surface of the fourth lens on the optical axis, SD11 is half of the maximum effective caliber of the object side surface of the first lens, and SD41 is half of the maximum effective caliber of the object side surface of the fourth lens. The optical system meets the relation, so that the ratio of the distance from the object side surface of the first lens to the object side surface of the fourth lens on the optical axis to the half difference value of the maximum effective caliber of the object side surface of the first lens and the half difference value of the maximum effective caliber of the object side surface of the fourth lens is reasonably restrained, the first lens to the fourth lens are further provided with reasonable step differences, the deflection angle of light rays is prevented from being too large, the risk of ghost image parasitic light is reduced, meanwhile, the optical system is also facilitated to be ensured to obtain a larger field angle on the premise of having a larger incident caliber, the processing manufacturability of the optical system is ensured, and the assembly difficulty of the optical system is reduced. The lower limit of the relation is lower than the lower limit of the relation, the step difference between the first lens and the fourth lens is too large, so that the deflection angle of light is too large, the risks of stray light and ghost images are increased, and meanwhile, the assembly difficulty of each lens in an optical system is increased; exceeding the upper limit of the relation is disadvantageous in increasing the entrance pupil diameter and the angle of view.

In one embodiment, the optical system satisfies the relationship: -35< SAG62/SAG71< -2; the SAG62 is a sagittal height of the effective aperture of the image side surface of the sixth lens element, that is, a distance from an intersection point of the image side surface of the sixth lens element and the optical axis to the maximum effective aperture of the image side surface of the sixth lens element in the optical axis direction, and the SAG71 is a sagittal height of the effective aperture of the object side surface of the seventh lens element, that is, a distance from an intersection point of the object side surface of the seventh lens element and the optical axis to the maximum effective aperture of the object side surface of the seventh lens element in the optical axis direction. The optical system meets the relational expression, so that the shapes of the image side surface of the sixth lens and the object side surface of the seventh lens are reasonably controlled, excessive bending of the surfaces of the sixth lens and the seventh lens is avoided, the molding difficulty of the lens is increased, meanwhile, aberration correction is facilitated, and the deflection angle of marginal rays is controlled within a reasonable range. The curvature difference between the image side surface of the sixth lens element and the object side surface of the seventh lens element is larger than the lower limit of the relation, which is not beneficial to the matching correction of the aberration between the image side surface of the sixth lens element and the object side surface of the seventh lens element; exceeding the upper limit of the relation, the object side surface of the seventh lens is excessively curved, which is unfavorable for the processing and molding of the seventh lens.

In one embodiment, the optical system satisfies the relationship: 0.5< (SAG 61-SAG 52)/CT 56<1; the SAG61 is the sagittal height of the effective aperture of the object side surface of the sixth lens element, that is, the distance between the intersection point of the object side surface of the sixth lens element and the optical axis and the maximum effective aperture of the object side surface of the sixth lens element in the optical axis direction, the SAG52 is the sagittal height of the effective aperture of the image side surface of the fifth lens element, that is, the distance between the intersection point of the image side surface of the fifth lens element and the optical axis and the maximum effective aperture of the image side surface of the fifth lens element in the optical axis direction, and the CT56 is the distance between the image side surface of the fifth lens element and the object side surface of the sixth lens element in the optical axis direction. The optical system can meet the relation, so that the sagittal height of the object side surface of the sixth lens and the image side surface of the fifth lens can be controlled, the shapes of the object side surface of the sixth lens and the object side surface of the seventh lens can be reasonably controlled, the processing manufacturability of the fifth lens and the sixth lens can be ensured, meanwhile, the light rays of the edge view field can have a smaller deflection angle, and the edge view field of the imaging surface can have enough relative brightness.

In one embodiment, the optical system satisfies the relationship: 8< (r21+r12)/CT 12<62; wherein R21 is a radius of curvature of the object side surface of the second lens element at the optical axis, R12 is a radius of curvature of the image side surface of the first lens element at the optical axis, and CT12 is a distance between the image side surface of the first lens element and the object side surface of the second lens element on the optical axis. The optical system is favorable for reasonably configuring the ratio of the curvature radius of the object side surface of the second lens on the optical axis to the curvature radius of the image side surface of the first lens on the optical axis and the distance between the image side surface of the first lens and the object side surface of the second lens on the optical axis by enabling the optical system to meet the relation, so that light can smoothly transition from the first lens to the second lens, a larger field angle can be obtained by the optical system, and meanwhile, due to the reasonable distance between the first lens and the second lens, the risk of parasitic ghost images can be reduced, and the assembly difficulty of the lenses can be reduced.

In one embodiment, the optical system satisfies the relationship: 4.4< TTL/CT67<4.8; wherein TTL is a distance from the object side surface of the first lens element to the imaging surface on the optical axis, and CT67 is a distance from the object side surface of the sixth lens element to the object side surface of the seventh lens element on the optical axis. The optical system meets the relation, so that the ratio of the distance from the object side surface of the first lens to the imaging surface on the optical axis to the distance from the object side surface of the sixth lens to the object side surface of the seventh lens on the optical axis is reasonably configured, the total length of the optical system is reduced, the miniaturization characteristic of the optical system is realized, the uniform distribution of the lens quality is facilitated, and the stability of the lens is improved.

In a second aspect, the present invention further provides an image capturing module, where the image capturing module includes a photosensitive chip and the optical system according to any one of the embodiments of the first aspect, and the photosensitive chip is disposed on an image side of the optical system. The photosensitive surface of the photosensitive chip is positioned on the imaging surface of the optical system, and light rays of objects incident on the photosensitive surface through the lens can be converted into electric signals of images. The photo-sensing chip may be a complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, CMOS) or a Charge-coupled Device (CCD). The camera module can be an imaging module integrated on the electronic equipment or an independent lens. By adding the optical system provided by the invention into the camera module, the camera module has the characteristics of larger angle of view, large aperture, small distortion and miniaturization by reasonably designing the surface type and refractive power of each lens in the optical system.

In a third aspect, the present invention further provides an electronic device, where the electronic device includes a housing and the camera module set in the second aspect, and the camera module set is disposed in the housing. Such electronic devices include, but are not limited to, smartphones, computers, smartwatches, and the like. By adding the camera module provided by the invention into the electronic equipment, the electronic equipment has the characteristics of larger field angle, large aperture, small distortion and miniaturization.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from them without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural view of an optical system of a first embodiment;

FIG. 2 is a partial schematic view of the optical system shown in FIG. 1;

fig. 3 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of the first embodiment;

fig. 4 is a schematic structural view of an optical system of the second embodiment;

FIG. 5 shows a longitudinal spherical aberration curve, astigmatic curve, and distortion curve of a second embodiment;

fig. 6 is a schematic structural view of an optical system of a third embodiment;

FIG. 7 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of a third embodiment;

fig. 8 is a schematic structural view of an optical system of a fourth embodiment;

fig. 9 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of the fourth embodiment;

fig. 10 is a schematic structural view of an optical system of the fifth embodiment;

fig. 11 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of the fifth embodiment.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.

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: the first lens element with negative refractive power has a concave object-side surface at an optical axis and a convex image-side surface at a paraxial region; the second lens element with refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the third lens element with refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the fourth lens element with positive refractive power has a convex object-side surface and a convex image-side surface at a paraxial region; the fifth lens element with negative refractive power has a concave object-side surface at a paraxial region; a sixth lens element with positive refractive power having a convex image-side surface at a paraxial region; a seventh lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the object side surface and the image side surface of the sixth lens and the seventh lens respectively comprise at least one inflection point.

The optical system satisfies the relation: 110 deg < FOV <121 deg, and/or 1.6< f/EPD <2.1; where FOV is the maximum field angle of the optical system, f is the focal length of the optical system, EPD is the entrance pupil diameter of the optical system.

In one embodiment, the optical system satisfies the relationship: 4mm < SD11/tan (HFOV) <4.5mm; the SD11 is half of the maximum effective aperture of the object side surface of the first lens, the HFOV is half of the maximum field angle of the optical system, and the tan (HFOV) is the tangent of the half field angle of the optical system. The optical system meets the relation, so that the ratio of half of the maximum effective caliber of the object side surface of the first lens to the tangent value of the half field angle of the optical system is reasonably configured, the caliber of the first lens is effectively reduced, the size and occupied volume of the optical system are further reduced, the requirement of miniaturization of the optical system is met, and meanwhile, the optical system has a larger field angle and the shooting range is increased. And the caliber of the first lens is overlarge on the premise of having the same size of field angle exceeding the upper limit of the relation formula, and becomes a main factor for restricting the whole volume of the optical system, so that the miniaturization requirement of the optical system is not met, the structural arrangement of each lens in the optical system is not facilitated, and the risk of ghost images is increased.

In one embodiment, the optical system satisfies the relationship: 1< ct14/(SD 11-SD 41) <1.1; the CT14 is a distance between the object side surface of the first lens element and the object side surface of the fourth lens element on the optical axis, SD11 is half of the maximum effective caliber of the object side surface of the first lens element, and SD41 is half of the maximum effective caliber of the object side surface of the fourth lens element. The optical system meets the relation, so that the ratio of the distance from the object side surface of the first lens to the object side surface of the fourth lens on the optical axis to the half difference value of the maximum effective caliber of the object side surface of the first lens and the half difference value of the maximum effective caliber of the object side surface of the fourth lens is reasonably restrained, the first lens to the fourth lens are further provided with reasonable step differences, the deflection angle of light rays is prevented from being too large, the risk of ghost image parasitic light is reduced, meanwhile, the optical system is also facilitated to be ensured to obtain a larger field angle on the premise of having a larger incident caliber, the processing manufacturability of the optical system is ensured, and the assembly difficulty of the optical system is reduced. The lower limit of the relation is lower than the lower limit of the relation, the step difference between the first lens and the fourth lens is too large, so that the deflection angle of light is too large, the risks of stray light and ghost images are increased, and meanwhile, the assembly difficulty of each lens in an optical system is increased; exceeding the upper limit of the relation is disadvantageous in increasing the entrance pupil diameter and the angle of view.

In one embodiment, the optical system satisfies the relationship: 0.5< (SAG 61-SAG 52)/CT 56<1; the SAG61 is a sagittal height of the effective aperture of the object side surface of the sixth lens element, that is, a distance between an intersection point of the object side surface of the sixth lens element and the optical axis and the maximum effective aperture of the object side surface of the sixth lens element in the optical axis direction, the SAG52 is a sagittal height of the effective aperture of the image side surface of the fifth lens element, that is, a distance between an intersection point of the image side surface of the fifth lens element and the optical axis and the maximum effective aperture of the image side surface of the fifth lens element in the optical axis direction, and the CT56 is a distance between the image side surface of the fifth lens element and the object side surface of the sixth lens element in the optical axis direction. The optical system can meet the relation, so that the sagittal height of the object side surface of the sixth lens and the image side surface of the fifth lens can be controlled, the shapes of the object side surface of the sixth lens and the object side surface of the seventh lens can be reasonably controlled, the processing manufacturability of the fifth lens and the sixth lens can be ensured, meanwhile, the light rays of the edge view field can have a smaller deflection angle, and the edge view field of the imaging surface can have enough relative brightness.

In one embodiment, the optical system satisfies the relationship: 8< (r21+r12)/CT 12<62; wherein, R21 is a radius of curvature of the object side surface of the second lens element at the optical axis, R12 is a radius of curvature of the image side surface of the first lens element at the optical axis, and CT12 is a distance between the image side surface of the first lens element and the object side surface of the second lens element on the optical axis. The optical system is favorable for reasonably configuring the ratio of the curvature radius of the object side surface of the second lens on the optical axis to the curvature radius of the image side surface of the first lens on the optical axis and the distance between the image side surface of the first lens and the object side surface of the second lens on the optical axis by enabling the optical system to meet the relation, so that light can smoothly transition from the first lens to the second lens, a larger field angle can be obtained by the optical system, and meanwhile, due to the reasonable distance between the first lens and the second lens, the risk of parasitic ghost images can be reduced, and the assembly difficulty of the lenses can be reduced.

In one embodiment, the optical system satisfies the relationship: 3< |slo62/slo71| <4; where SLO62 is the maximum tilt angle of the image side of the sixth lens and SLO71 is the maximum tilt angle of the object side of the seventh lens. Fig. 2 shows the maximum inclination angles of the image-side surface of the sixth lens element and the object-side surface of the seventh lens element, where SLO62 is the maximum angle between the tangent line of the image-side surface of the sixth lens element and the straight line perpendicular to the optical axis, and SLO71 is the maximum angle between the tangent line of the object-side surface of the seventh lens element and the straight line perpendicular to the optical axis. The optical system satisfies the above relation, so that the ratio of the maximum inclination angle of the image side surface of the sixth lens to the maximum inclination angle of the object side surface of the seventh lens is reasonably configured, the bending degree of the image side surface of the sixth lens and the object side surface of the seventh lens is restrained, the image side surface of the sixth lens and the object side surface of the seventh lens are matched with each other, aberration generated by the first lens to the fifth lens in front of the sixth lens is corrected together, and overall aberration balance of the optical system is achieved. The ratio of the maximum inclination angle of the image side surface of the sixth lens to the maximum inclination angle of the object side surface of the seventh lens is too small below the lower limit of the relation, so that the sixth lens and the seventh lens are not beneficial to mutually matching to correct the aberration of the optical system; exceeding the upper limit of the relation results in excessive bending of the image side surface of the sixth lens element, which is detrimental to lens molding and increases the sensitivity of the optical system.

In one embodiment, the optical system satisfies the relationship: 4.4< TTL/CT67<4.8; wherein TTL is a distance from the object side surface of the first lens element to the image plane on the optical axis, and CT67 is a distance from the object side surface of the sixth lens element to the object side surface of the seventh lens element on the optical axis. The optical system meets the relation, so that the ratio of the distance from the object side surface of the first lens to the imaging surface on the optical axis to the distance from the object side surface of the sixth lens to the object side surface of the seventh lens on the optical axis is reasonably configured, the total length of the optical system is reduced, the miniaturization characteristic of the optical system is realized, the uniform distribution of the lens quality is facilitated, and the stability of the lens is improved.

First embodiment

Referring to fig. 1 and 3, the optical system of the present embodiment includes, in order from an object side to an image side along an optical axis:

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

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

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

The fourth lens element L4 with positive refractive power has a convex object-side surface S7 at a paraxial region and a convex image-side surface S8 at a paraxial region.

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

The sixth lens element L6 with positive refractive power has a convex object-side surface S11 at a paraxial region and a convex image-side surface S12 at a paraxial region.

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

In addition, the optical system further includes a stop STO, an infrared cut filter IR, and an imaging plane IMG. In the present embodiment, the stop STO is provided on the object side surface side of the fourth lens of the optical system for controlling the amount of light entering. The infrared cut filter IR is disposed between the seventh lens L7 and the imaging plane IMG, and includes an object side surface S15 and an image side surface S16, and is used for filtering infrared light, so that the light incident on the imaging plane IMG is only visible light, and the wavelength of the visible light is 380nm-780nm. The infrared cut filter IR is made of GLASS (GLASS), and can be coated on the GLASS. The first lens L1 to the seventh lens L7 are made of Plastic (Plastic). The effective pixel area of the electronic photosensitive element is positioned on the imaging plane IMG.

Table 1a shows various parameters of the optical system of the present embodiment, wherein the Y radius is the radius of curvature of the object side or image side of the corresponding plane number at the optical axis. The surface numbers S1 and S2 are the object side surface S1 and the image side surface S2 of the first lens element L1, respectively, 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 element. The first value in the "thickness" parameter row of the first lens element L1 is the thickness of the lens element on the optical axis, and the second value is the distance from the image side surface of the lens element to the rear surface in the image side direction on the optical axis. The focal length, refractive index of the material and Abbe number are all obtained by adopting visible light with reference wavelength of 587.6nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

TABLE 1a

Wherein f is the focal length of the optical system, FNO is the f-number of the optical system, FOV is the maximum field angle of the optical system, and TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis.

In the present embodiment, the object-side surface and the image-side surface of the first lens element L1 to the seventh lens element L7 are aspheric, and the aspheric surface profile x can be defined by, but not limited to, the following aspheric formula:

wherein x is the distance from the corresponding point on the aspheric surface to the plane tangent to the vertex of the surface, h is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the vertex of the aspheric surface, k is the conic coefficient, ai is the coefficient corresponding to the i-th higher term in the aspheric surface formula. Table 1b shows the higher order coefficients A4, A6, A8, a10, a12, a14, a16, a18, a20, a22, a24, a26, a28, and a30 of the aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, and S14 that can be used in the first embodiment.

TABLE 1b

Fig. 3 (a) shows a longitudinal spherical aberration diagram of the optical system of the first embodiment at wavelengths of 650.0000nm, 610.0000nm, 555.0000nm, 510.0000nm, 470.0000nm, 435.0000nm, wherein the abscissa along the X-axis direction represents the focus offset, i.e. the distance (in mm) from the imaging plane to the intersection point of the light ray and the optical axis, and the ordinate along the Y-axis direction represents the normalized field of view, and the longitudinal spherical aberration diagram represents the focus deviation of the light rays of different wavelengths after passing through each lens of the optical system. As can be seen from fig. 3 (a), the degree of deviation of the focal point of the light beams with each wavelength in the first embodiment tends to be uniform, and the diffuse spots or the halos in the imaging picture are effectively suppressed, which means that the imaging quality of the optical system in the present embodiment is better.

Fig. 3 (b) also shows an astigmatic diagram 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. The S curve in the astigmatic plot represents the sagittal field curve at 555.0000nm and the T curve represents the meridional field curve at 555.0000 nm. As can be seen from fig. 3 (b), the curvature of field of the optical system is small, the curvature of field and astigmatism of each field of view are well corrected, and the center and the edge of the field of view have clear imaging.

Fig. 3 (c) also shows a distortion curve of the optical system of the first embodiment at a wavelength of 555.0000 nm. Wherein, the abscissa along the X-axis direction represents the distortion value in units of mm, and the ordinate along the Y-axis direction represents the image height in units of mm. The distortion curves represent distortion magnitude values corresponding to different angles of view. As can be seen from fig. 3 (c), at a wavelength of 555.0000nm, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

As can be seen from (a), (b) and (c) in fig. 3, the optical system of the present embodiment has smaller aberration, better imaging quality, and good imaging quality.

Second embodiment

Referring to fig. 4 and 5, the optical system of the present embodiment includes, in order from an object side to an image side along an optical axis:

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

The other structures of the second embodiment are the same as those of the first embodiment, and reference is made thereto.

Table 2a shows parameters of the optical system of the present embodiment, in which the focal length, the refractive index of the material, and the abbe number are obtained using visible light having a reference wavelength of 587.6nm, and the Y radius, thickness, and focal length are in millimeters (mm), and other parameters have the same meaning as those of the first embodiment.

TABLE 2a

Table 2b gives the higher order coefficients that can be used for each aspherical mirror in the second embodiment, where each aspherical mirror profile can be defined by the formula given in the first embodiment.

TABLE 2b

FIG. 5 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of an optical system of a second embodiment, wherein the longitudinal spherical aberration curve represents the focus deviation of light rays of different wavelengths after passing through the lenses of the optical system; astigmatic curves represent meridian field curves and sagittal field curves; the distortion curves represent distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 5, the longitudinal spherical aberration, curvature of field and distortion of the optical system are all well controlled, so that the optical system of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 6 and 7, the optical system of the present embodiment includes, in order from an object side to an image side along an optical axis:

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

The other structures of the third embodiment are the same as those of the first embodiment, and reference is made thereto.

Table 3a shows parameters of the optical system of the present embodiment, in which the focal length, the refractive index of the material, and the abbe number are obtained using visible light having a reference wavelength of 587.6nm, and the Y radius, thickness, and focal length are in millimeters (mm), and other parameters have the same meaning as those of the first embodiment.

TABLE 3a

Table 3b gives the higher order coefficients that can be used for each of the aspherical mirror surfaces in the third embodiment, where each of the aspherical surface types can be defined by the formula given in the first embodiment.

TABLE 3b

FIG. 7 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of an optical system of a third embodiment, wherein the longitudinal spherical aberration curve represents the focus deviation of light rays of different wavelengths after passing through the lenses of the optical system; astigmatic curves represent meridian field curves and sagittal field curves; the distortion curves represent distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 7, the longitudinal spherical aberration, curvature of field and distortion of the optical system are all well controlled, so that the optical system of this embodiment has good imaging quality.

Fourth embodiment

Referring to fig. 8 and 9, the optical system of the present embodiment includes, in order from an object side to an image side along an optical axis:

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

The other structures of the fourth embodiment are the same as those of the first embodiment, and reference is made thereto.

Table 4a shows parameters of the optical system of the present embodiment, in which the focal length, the refractive index of the material, and the abbe number are obtained using visible light having a reference wavelength of 587.6nm, and the Y radius, thickness, and focal length are in millimeters (mm), and other parameters have the same meaning as those of the first embodiment.

TABLE 4a

Table 4b gives the higher order coefficients that can be used for each aspherical mirror in the fourth embodiment, where each aspherical mirror profile can be defined by the formula given in the first embodiment.

TABLE 4b

Fig. 9 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of the optical system of the fourth embodiment, wherein the longitudinal spherical aberration curve represents the focus deviation of light rays of different wavelengths after passing through the lenses of the optical system; astigmatic curves represent meridian field curves and sagittal field curves; the distortion curves represent distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 9, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are all well controlled, so that the optical system of this embodiment has good imaging quality.

Fifth embodiment

Referring to fig. 10 and 11, the optical system of the present embodiment includes, in order from an object side to an image side along an optical axis:

The other structures of the fifth embodiment are the same as those of the first embodiment, and reference is made thereto.

Table 5a shows parameters of the optical system of the present embodiment, in which the focal length, the refractive index of the material, and the abbe number are obtained using visible light having a reference wavelength of 587.6nm, and the Y radius, thickness, and focal length are in millimeters (mm), and other parameters have the same meaning as those of the first embodiment.

TABLE 5a

Table 5b gives the higher order coefficients that can be used for each of the aspherical mirror surfaces in the fifth embodiment, where each of the aspherical surface types can be defined by the formula given in the first embodiment.

TABLE 5b

Fig. 11 shows a longitudinal spherical aberration curve, an astigmatic curve, and a distortion curve of the optical system of the fifth embodiment, wherein the longitudinal spherical aberration curve represents the focus deviation of light rays of different wavelengths after passing through the lenses of the optical system; astigmatic curves represent meridian field curves and sagittal field curves; the distortion curves represent distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 11, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are all well controlled, so that the optical system of this embodiment has good imaging quality. And the distortion of the optical systems of the first to fifth embodiments is within plus or minus 2%.

Table 6 shows the values of SD11/tan (HFOV), f/EPD, f123/f1, f45/f, R32/R41, R51/R42, CT 14/(SD 11-SD 41), SAG62/SAG71, (SAG 61-SAG 52)/CT 56, (R21+R12)/CT 12, |SLO62/SLO71|, and TTL/CT67 in the optical systems of the first to fifth embodiments.

TABLE 6

As can be seen from table 6, the optical systems of the first to fifth embodiments all satisfy the following relations: 110 Values of deg < FOV <121 deg, 4mm < SD11/tan (HFOV) <4.5mm, 1.6< f/EPD <2.1, 0.9< f123/f1<1.5, 1.5< f45/f <2.5, 1< R32/R41<2.8, 1.5< R51/R42<3, 1< CT 14/(SD 11-SD 41) <1.1, -35< SAG62/SAG71< -2, 0.5< (SAG 61-SAG 52)/CT 56<1, 8< (r21+r12)/CT 12<62, 3< |slo62/slo71| <4, and 4.4< ttl/CT67< 4.8.

The invention also provides an image pickup module, which comprises a photosensitive chip and the optical system of any one of the implementation modes of the first aspect, wherein the photosensitive chip is arranged on the image side of the optical system. The photosensitive surface of the photosensitive chip is positioned on the imaging surface of the optical system, and light rays of objects incident on the photosensitive surface through the lens can be converted into electric signals of images. The photo-sensing chip may be a complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, CMOS) or a Charge-coupled Device (CCD). The camera module can be an imaging module integrated on the electronic equipment or an independent lens. By adding the optical system provided by the invention into the camera module, the camera module has the characteristics of larger angle of view, large aperture, small distortion and miniaturization by reasonably designing the surface type and refractive power of each lens in the optical system.

The invention also provides electronic equipment, which comprises a shell and the camera module set in the second aspect, wherein the camera module set is arranged in the shell. Such electronic devices include, but are not limited to, smartphones, computers, smartwatches, and the like. By adding the camera module provided by the invention into the electronic equipment, the electronic equipment has the characteristics of larger field angle, large aperture, small distortion and miniaturization.

The foregoing disclosure is only illustrative of the preferred embodiments of the present invention and is not to be construed as limiting the scope of the invention, as it is understood by those skilled in the art that all or part of the above-described embodiments may be practiced without resorting to the equivalent thereof, which is intended to fall within the scope of the invention as defined by the appended claims.

Claims

1. An optical system, wherein a total of seven lenses with refractive power sequentially comprise, from an object side to an image side along an optical axis:

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

a second 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 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 having a convex object-side surface and a convex image-side surface at a paraxial region;

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

A sixth lens element with positive refractive power having a convex image-side surface at a paraxial region;

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

the object side surface and the image side surface of the sixth lens and the seventh lens respectively comprise at least one inflection point;

the optical system satisfies the relation: 110 deg < FOV <121 deg,1.5< f45/f <2.5,1.6< f/EPD <2.1;

wherein FOV is the maximum field angle of the optical system, f45 is the combined focal length of the fourth lens and the fifth lens, f is the focal length of the optical system, EPD is the entrance pupil diameter of the optical system.

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

4mm<SD11/tan(HFOV)<4.5mm；

wherein SD11 is half of the maximum effective aperture of the object side surface of the first lens, HFOV is half of the maximum field angle of the optical system, and tan (HFOV) is the tangent of the half field angle of the optical system.

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

0.9<f123/f1<1.5；

wherein f123 is a combined focal length of the first lens, the second lens and the third lens, and f1 is a focal length of the first lens.

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

1< R32/R41<2.8, and/or 1.5< R51/R42<3;

wherein R32 is a radius of curvature of the image side surface of the third lens element at the optical axis, R41 is a radius of curvature of the object side surface of the fourth lens element at the optical axis, R51 is a radius of curvature of the object side surface of the fifth lens element at the optical axis, and R42 is a radius of curvature of the image side surface of the fourth lens element at the optical axis.

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

1<CT14/(SD11-SD41)<1.1；

wherein, CT14 is the distance between the object side surface of the first lens and the object side surface of the fourth lens on the optical axis, SD11 is half of the maximum effective caliber of the object side surface of the first lens, and SD41 is half of the maximum effective caliber of the object side surface of the fourth lens.

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

-35<SAG62/SAG71<-2；

wherein SAG62 is the sagittal height of the effective aperture of the image side of the sixth lens element and SAG71 is the sagittal height of the effective aperture of the object side of the seventh lens element.

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

0.5<(SAG61-SAG52)/CT56<1；

Wherein SAG61 is the sagittal height of the effective aperture of the object side surface of the sixth lens element, SAG52 is the sagittal height of the effective aperture of the image side surface of the fifth lens element, and CT56 is the distance on the optical axis from the image side surface of the fifth lens element to the object side surface of the sixth lens element.

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

8< (r21+r12)/CT 12<62, and/or 4.4< ttl/CT67 <4.8;

wherein R21 is a radius of curvature of the object side surface of the second lens element at the optical axis, R12 is a radius of curvature of the image side surface of the first lens element at the optical axis, CT12 is a distance from the image side surface of the first lens element to the object side surface of the second lens element at the optical axis, TTL is a distance from the object side surface of the first lens element to the imaging surface at the optical axis, and CT67 is a distance from the object side surface of the sixth lens element to the object side surface of the seventh lens element at the optical axis.

9. An image pickup module comprising the optical system according to any one of claims 1 to 8 and a photosensitive chip, the photosensitive chip being located on an image side of the optical system.

10. An electronic device comprising a housing and the camera module of claim 9, the camera module being disposed within the housing.