CN211786329U

CN211786329U - Optical system, lens module and electronic equipment

Info

Publication number: CN211786329U
Application number: CN202020488615.4U
Authority: CN
Inventors: 党绪文; 刘彬彬; 李明; 邹海荣
Original assignee: OFilm Tech Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2020-04-03
Filing date: 2020-04-03
Publication date: 2020-10-27
Anticipated expiration: 2030-04-03

Abstract

The utility model provides an optical system, camera lens module and electronic equipment. The optical system includes a first lens; a second lens; a third lens; a fourth lens; the object side surface and the image side surface of the fifth lens are both aspheric surfaces, and at least one of the object side surface and the image side surface is provided with at least one inflection point; and the object side surface and the image side surface of the sixth lens are both aspheric surfaces, and at least one of the object side surface and the image side surface is provided with at least one inflection point. By reasonably configuring the surface shape and the refractive power of each lens, the optical system can simultaneously meet the requirements of high pixel, large aperture, good image quality, compact structure, effective reduction of internal stray light and the like.

Description

Optical system, lens module and electronic equipment

Technical Field

The utility model belongs to the technical field of optical imaging, especially, relate to an optical system, camera lens module and electronic equipment.

Background

The manufacturing technology of electronic products such as smart phones and flat panels is continuously developed, and a lens, which is one of important basic parts for image data acquisition, is also undergoing diversified development, and the development trend gradually changes to pursuit of large aperture, high pixel support and good imaging quality in recent years.

However, in the conventional lens, the lens pitch is large, the f-number and the pixel support are difficult to meet the market demand, and the lens and the mechanism are easy to generate stray light which is difficult to eliminate, which brings great trouble to the production of the optical image taking lens.

SUMMERY OF THE UTILITY MODEL

An object of the present application is to provide an optical system, a lens module and an electronic device, which are used to solve the above technical problems.

In order to achieve the purpose of the application, the application provides the following technical scheme:

in a first aspect, the present application provides an optical system, comprising, in order from an object side to an image side in an optical axis direction: the first lens element with positive refractive power has a convex object-side surface; the second lens element with negative refractive power has a concave image-side surface at the paraxial region; the third lens element with refractive power has a convex object-side surface at a paraxial region; the fourth lens element with refractive power has an object-side surface and an image-side surface which are both aspheric; the fifth lens element with positive refractive power has a concave object-side surface near the circumference, both the object-side surface and the image-side surface of the fifth lens element are aspheric, and at least one of the object-side surface and the image-side surface of the fifth lens element is provided with at least one inflection point; the sixth 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; the object side surface and the image side surface of the sixth lens are both aspheric surfaces, and at least one of the object side surface and the image side surface of the sixth lens is provided with at least one inflection point. By reasonably configuring the surface shapes and the refractive powers of the first lens element to the sixth lens element, the optical system of the present application can satisfy the requirements of high pixel, large aperture and good image quality, and simultaneously keep compact structure and effectively reduce the influence of internal stray light.

In one embodiment, the optical system satisfies the conditional expression: i SAG 41I/I SAG 42I < 20.0; wherein SAG41 is the sagittal height at the maximum effective aperture of the object side surface of the fourth lens and SAG42 is the sagittal height at the maximum effective aperture of the image side surface of the fourth lens. When the optical system meets the above conditional expression, the fourth lens does not introduce an excessively large surface form inclination angle, which is beneficial to processing and molding of the lens. And the aberration correction capability of the optical system can be further improved, and the resolving power is enhanced, so that the processing of the lens is friendly to a certain degree.

In one embodiment, the optical system satisfies the conditional expression: 2.2 < (CT2+ CT3+ CT4)/(CT23+ CT34) is less than or equal to 8.5; wherein, CT2 is the thickness of the second lens element on the optical axis, CT3 is the thickness of the third lens element on the optical axis, CT4 is the thickness of the fourth lens element on the optical axis, CT23 is the distance between the image-side surface of the second lens element and the object-side surface of the third lens element on the optical axis, and CT34 is the distance between the image-side surface of the third lens element and the object-side surface of the fourth lens element on the optical axis. When the optical system meets the conditional expression, the average refractive indexes of the second lens, the third lens and the fourth lens and the air gap are reasonably adjusted, the middle thickness and the edge thickness of the second lens, the third lens and the fourth lens are increased, the air gap among the lenses is compressed, the integral compactness of the lens group can be improved to a certain degree, the deflection angle of light rays in refraction is favorably reduced, and therefore tolerance sensitivity is reduced.

In one embodiment, the optical system satisfies the conditional expression: 0.35 < f/| f3| + f/| f4| < 0.8; wherein f is an effective focal length of the optical system, f3 is an effective focal length of the third lens, and f4 is an effective focal length of the fourth lens. The refractive power of the third lens and the refractive power of the fourth lens are changed, so that the distortion and the coma aberration generated by the front lens group can be obviously balanced, and the third lens and the fourth lens do not introduce large aberration, so that the surface shapes of the third lens and the fourth lens can be flexibly arranged to improve the resolving power of the optical system; when the optical system meets the conditional expression, the refractive power distribution of the third lens and the fourth lens is reasonable, the edge light deflection angle can be well controlled, the image surface illumination can be improved, and the stability of the optical system is improved.

In one embodiment, the optical system satisfies the conditional expression: the | SAG61/CT6| is less than or equal to 1.8; wherein SAG61 is the sagittal height at the sixth lens object side effective aperture and CT6 is the thickness of the sixth lens on the optical axis. When the optical system meets the conditional expression, the variation of the rise and the surface shape of the sixth lens provides different possibilities for the distribution of the refractive power close to the image plane and perpendicular to the optical axis direction, so that light can be guided well, the overlarge incident angle of the light incident on the image plane is avoided, the high-pixel photosensitive chip is well matched, meanwhile, the sixth lens can effectively balance the aberration generated by the front lens group, and the improvement of the image quality of the system is facilitated.

In one embodiment, the optical system satisfies the conditional expression: 0.2 < | | R51| - | R52| |/(| R51| + | R52|) is less than or equal to 0.8; wherein R51 is a radius of curvature of the fifth lens object-side surface at the optical axis, and R52 is a radius of curvature of the fifth lens image-side surface at the optical axis. When the optical system meets the conditional expression, the fifth lens comprises at least one inflection point, is an aspheric surface, and can compress the thickness of the lens, so that the aberration generated by the front lens group is effectively improved, and the resolving power is further improved.

In one embodiment, the optical system satisfies the conditional expression: f123/| f56|, is less than or equal to 0.36; wherein f123 is a total effective focal length of the first lens, the second lens, and the third lens, and f56 is a total effective focal length of the fifth lens and the sixth lens. The first lens, the second lens and the third lens are properly thick at the medium thickness edge, and the refractive power distribution is reasonable, so that the structure, the reasonability and the compactness of the lens are effectively improved, and the compression of the total length of the optical system and the balance of image quality are facilitated, so that the difficulty in lens arrangement and assembly can be reduced.

In one embodiment, the optical system satisfies the conditional expression: 0.60mm less than (CT1+ BF)/FNO less than or equal to 0.85 mm; CT1 is the thickness of the first lens on the optical axis, BF is the axial distance between the farthest point of the image side surface of the sixth lens and the image surface, and FNO is the f-number of the optical system. The reasonable setting of BF can better satisfy the matching between the lens optical system and the chip; when the optical system satisfies the above conditional expressions, the first lens can maintain good thickness and surface shape at a small f-number, which helps to reduce the risk of lens molding and, in addition, provides support for increasing the angle of field.

In one embodiment, the optical system satisfies the conditional expression: 6.1 < | f3|/n3 < 22.7; wherein f3 is the third lens effective focal length and n3 is the refractive index of the third lens material at a wavelength of 587.6 nm. When the optical system meets the conditional expression, the refractive powers of the third lens and other lenses can be reasonably distributed, so that the optical system supports aberration balance and image quality improvement under different materials, and the second lens, the third lens and the fourth lens are easy to compress air gaps, so that the compactness of the optical system is improved, and stray light influence is avoided.

In one embodiment, the optical system satisfies the conditional expression: ET34/ImgH is less than or equal to 0.12; ET34 is an axial distance between the maximum effective aperture of the image-side surface of the third lens element and the maximum effective aperture of the object-side surface of the fourth lens element, and ImgH is a half of a diagonal length of an effective imaging area of the optical system on an imaging surface. Wherein ImgH determines the size of the electronic photosensitive chip, the larger ImgH, the larger the supportable maximum electronic photosensitive chip size, and when the optical system satisfies the above conditional expression, the optical system can be made to support the electronic photosensitive chip with higher pixels; meanwhile, the effective aperture distance between the third lens and the fourth lens can be effectively controlled, so that the edge light deflection angle is smaller, the tolerance sensitivity of the optical system is favorably reduced, and the edge field performance is improved.

In a second aspect, the present application further provides a lens module, which includes a lens barrel, an electronic photosensitive element, and an optical system in any one of the embodiments of the first aspect, wherein the first lens to the sixth lens of the optical system are mounted in the lens barrel, and the electronic photosensitive element is disposed on an image side of the optical system and is configured to convert light rays, which pass through the first lens to the sixth lens and enter an object on the electronic photosensitive element, into an electrical signal of an image. By installing the optical system in the lens module, the lens module can meet the requirements of high pixel, large aperture and good image quality, meanwhile, the structure is kept compact, and the influence of internal stray light is effectively reduced.

In a third aspect, the present application further provides an electronic device, which includes a housing and the lens module of the second aspect, wherein the lens module is disposed in the housing. By arranging the lens module in the second aspect in the electronic equipment, the electronic equipment can meet the requirements of high pixel, large aperture and good image quality, meanwhile, the structure is kept compact, and the influence of internal stray light is effectively reduced.

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 for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

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

FIG. 1b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the first embodiment;

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

FIG. 2b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the second embodiment;

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

FIG. 3b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the third embodiment;

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

FIG. 4b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the fourth embodiment;

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

FIG. 5b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the fifth embodiment;

FIG. 6a is a schematic structural diagram of an optical system of a sixth embodiment;

fig. 6b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the sixth embodiment.

FIG. 7a is a schematic structural diagram of an optical system of a seventh embodiment;

fig. 7b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the seventh embodiment.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

The embodiment of the application provides a lens module, this lens module include lens cone, electron photosensitive element and the utility model provides an optical system, optical system's first lens are installed in the lens cone to the sixth lens, electron photosensitive element sets up optical system's image side is used for passing first lens extremely the incidence of sixth lens is incided the light of the thing on the electron photosensitive element converts the signal of telecommunication of image into. The electron sensor may be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). The lens module can be an independent lens of a digital camera, and can also be an imaging module integrated on electronic equipment such as a smart phone. By installing the first lens element to the sixth lens element of the optical system in the lens module and reasonably configuring the surface shapes and refractive powers of the first lens element to the sixth lens element, the lens module provided by the embodiment of the application can meet the requirements of high pixel, large aperture and good image quality, and meanwhile, keeps compact structure and effectively reduces the influence of internal stray light.

The embodiment of the application provides electronic equipment, and the electronic equipment comprises a shell and a lens module provided by the embodiment of the application. The lens module and the electronic photosensitive element are arranged in the shell. The electronic device can be a smart phone, a Personal Digital Assistant (PDA), a tablet computer, a smart watch, an unmanned aerial vehicle, an electronic book reader, a vehicle event data recorder, a wearable device and the like. Through the lens module of the second aspect arranged in the electronic equipment, the electronic equipment can meet the requirements of high pixel, large aperture and good image quality, meanwhile, the structure is kept compact, and the influence of internal stray light is effectively reduced.

The present disclosure provides an optical system including, in order from an object side to an image side in an optical axis direction, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. In the first to sixth lenses, any two adjacent lenses may have an air space therebetween.

Specifically, the specific shape and structure of the six lenses are as follows:

the first lens element with positive refractive power has a convex object-side surface; the second lens element with negative refractive power has a concave image-side surface at the paraxial region; the third lens element with refractive power has a convex object-side surface at a paraxial region; the fourth lens element with refractive power has an object-side surface and an image-side surface which are both aspheric; the fifth lens element with positive refractive power has a concave object-side surface near the circumference, both the object-side surface and the image-side surface of the fifth lens element are aspheric, and at least one of the object-side surface and the image-side surface of the fifth lens element is provided with at least one inflection point; the sixth lens element with negative refractive power has a convex object-side surface and a concave image-side surface; the object side surface and the image side surface of the sixth lens are both aspheric surfaces, and at least one of the object side surface and the image side surface of the sixth lens is provided with at least one inflection point. Meanwhile, by reasonably configuring the surface shapes and the refractive powers of the first lens element to the sixth lens element, the optical system provided by the embodiment of the application can meet the requirements of high pixel, large aperture and good image quality, and meanwhile keeps compact structure and effectively reduces the influence of internal stray light.

In one embodiment, the optical system satisfies the conditional expression: i SAG 41I/I SAG 42I < 20.0; and SAG41 is the rise of the fourth lens at the maximum effective aperture of the object side surface, and SAG42 is the rise of the fourth lens at the maximum effective aperture of the image side surface. When the optical system meets the above conditional expression, the fourth lens does not introduce an excessively large surface form inclination angle, which is beneficial to the processing and molding of the lens. And the aberration correction capability of the optical system can be further improved, and the resolving power is enhanced, so that the processing of the lens is friendly to a certain degree.

In one embodiment, the optical system satisfies the conditional expression: 2.2 < (CT2+ CT3+ CT4)/(CT23+ CT34) is less than or equal to 8.5; the thickness of the second lens element on the optical axis is CT2, the thickness of the third lens element on the optical axis is CT3, the thickness of the fourth lens element on the optical axis is CT4, the distance between the image-side surface of the second lens element and the object-side surface of the third lens element on the optical axis is CT23, and the distance between the image-side surface of the third lens element and the object-side surface of the fourth lens element on the optical axis is CT 34. When the optical system meets the conditional expression, the average refractive index of the second lens, the third lens, the fourth lens and the air gap is reasonably adjusted, the medium thickness and the edge thickness of the second lens, the third lens and the fourth lens are increased, the air gap among the lenses is compressed, the integral compactness of the lens group can be improved to a certain degree, the deflection angle of light in refraction is favorably reduced, and the tolerance sensitivity is reduced.

In one embodiment, the optical system satisfies the conditional expression: 0.35 < f/| f3| + f/| f4| < 0.8; where f is the effective focal length of the optical system, f3 is the effective focal length of the third lens, and f4 is the effective focal length of the fourth lens. The refractive power of the third lens and the refractive power of the fourth lens are changed, so that the distortion and the coma aberration generated by the front lens group can be obviously balanced, and the third lens and the fourth lens do not introduce large aberration, so that the surface shapes of the third lens and the fourth lens can be flexibly arranged to improve the resolving power of the optical system; when the optical system meets the conditional expression, the refractive power distribution of the third lens and the fourth lens is reasonable, the edge light deflection angle can be well controlled, the image surface illumination can be improved, and the stability of the optical system is improved.

In one embodiment, the optical system satisfies the conditional expression: the | SAG61/CT6| is less than or equal to 1.8; wherein SAG61 is the rise of the sixth lens at the object side effective aperture and CT6 is the thickness of the sixth lens on the optical axis. When the optical system meets the conditional expression, the variation of the rise and the surface shape of the sixth lens provides different possibilities for the distribution of the refractive power close to the image plane in the direction perpendicular to the optical axis, so that light can be guided well, the overlarge incident angle of the light incident to the image plane is avoided, the high-pixel photosensitive chip is well matched, meanwhile, the sixth lens can effectively balance the aberration generated by the front lens group, and the improvement of the image quality of the system is facilitated.

In one embodiment, the optical system satisfies the conditional expression: 0.2 < | | R51| - | R52| |/(| R51| + | R52|) is less than or equal to 0.8; wherein, R51 is the curvature radius of the object-side surface of the fifth lens element at the optical axis, and R52 is the curvature radius of the image-side surface of the fifth lens element at the optical axis. When the optical system satisfies the above conditional expression, the fifth lens element includes at least one inflection point, is aspheric, and can compress the thickness of the fifth lens element, thereby effectively improving aberration generated by the front lens element, and further improving resolving power.

In one embodiment, the optical system satisfies the conditional expression: f123/| f56|, is less than or equal to 0.36; where f123 is a total effective focal length of the first lens, the second lens, and the third lens, and f56 is a total effective focal length of the fifth lens and the sixth lens. When the optical system meets the condition formula, the thickness of the medium-thickness sides of the first lens, the second lens and the third lens can be kept appropriate, the refractive power distribution is reasonable, the structure, the reasonability and the compactness of the lens are effectively improved, the compression of the total length of the optical system and the balance of image quality are facilitated, and the difficulty in lens arrangement and assembly can be reduced.

In one embodiment, the optical system satisfies the conditional expression: 0.60mm less than (CT1+ BF)/FNO less than or equal to 0.85 mm; wherein, CT1 is the thickness of the first lens on the optical axis, BF is the axial distance from the farthest point of the image side surface of the sixth lens to the image surface, and FNO is the f-number of the optical system. The reasonable setting of BF can better satisfy the matching between the lens optical system and the chip; when the optical system satisfies the above conditional expressions, the first lens can maintain good thickness and surface shape at a small f-number, which helps to reduce the risk of lens molding and, in addition, provides support for an increase in the angle of view.

In one embodiment, the optical system satisfies the conditional expression: 6.1 < | f3|/n3 < 22.7; wherein f3 is the effective focal length of the third lens, and n3 is the refractive index of the third lens material at a wavelength of 587.6 nm. When the optical system meets the conditional expression, the refractive power of the third lens and the refractive power of the other lenses can be reasonably distributed, so that the optical system supports aberration balance and image quality improvement under different materials, and the second lens, the third lens and the fourth lens are easy to compress air gaps, so that the compactness of the optical system is improved, and the influence of stray light is avoided.

In one embodiment, the optical system satisfies the conditional expression: ET34/ImgH is less than or equal to 0.12; ET34 is the axial distance between the maximum effective aperture of the image-side surface of the third lens element and the maximum effective aperture of the object-side surface of the fourth lens element, and ImgH is half of the length of the diagonal line of the effective imaging area of the optical system on the imaging surface. Wherein ImgH determines the size of the electronic photosensitive chip, the larger ImgH, the larger the supportable maximum electronic photosensitive chip size, and when the optical system satisfies the above conditional expression, the optical system can support the electronic photosensitive chip with higher pixels; meanwhile, the effective aperture distance between the third lens and the fourth lens can be effectively controlled, so that the edge light deflection angle is smaller, the tolerance sensitivity of the optical system is favorably reduced, and the edge field performance is improved.

In a first embodiment of the present invention, the first,

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

a first lens element L1 with positive refractive power, the first lens element L1 having an object-side surface S1 convex at paraxial region and near circumference, and the first lens element L1 having an image-side surface S2 convex at paraxial region and near circumference;

a second lens element L2 with negative refractive power having an object-side surface S3 of the second lens element L2 being concave at a paraxial region and at a paraxial region, an image-side surface S4 of the second lens element L2 being concave at a paraxial region and an image-side surface S4 being convex at a paraxial region;

a third lens element L3 with negative refractive power, the object-side surface S5 of the third lens element L3 being convex in the paraxial region, the object-side surface S5 being concave in the paraxial region, and the image-side surface S6 of the third lens element L3 being concave in the paraxial region and the peripheral region;

a fourth lens element L4 with positive refractive power, the fourth lens element L4 having an object-side surface S7 convex at paraxial region and near circumference, and the fourth lens element L4 having an image-side surface S8 concave at paraxial region and near circumference;

a fifth lens element L5 with positive refractive power having a concave object-side surface S9 of the fifth lens element L5 at a paraxial region and a convex near-circumferential region, and an image-side surface S10 of the fifth lens element L5 at a paraxial region and a convex near-circumferential region;

the sixth lens element L6 with negative refractive power has a convex object-side surface S11 of the sixth lens element L6 near the optical axis and near the circumference, and a concave image-side surface S12 of the sixth lens element L6 near the optical axis and near the circumference.

The first lens element L1 through the sixth lens element L6 are all made of plastic.

Further, the optical system includes a stop STO, an infrared filter L7, and an image plane S15. The stop STO is provided on the side of the first lens L1 away from the second lens L2, and controls the amount of light entering. In other embodiments, the stop STO can be disposed between two adjacent lenses, or on other lenses. The infrared filter L7 is disposed on the image side of the sixth lens L6, and includes an object side surface S13 and an image side surface S14, and the infrared filter L7 is configured to filter infrared light, so that the light incident on the image surface S15 is visible light, and the wavelength of the visible light is 380nm-780 nm. The infrared filter L7 is made of glass, and may be coated with a film. The image plane S15 is a plane on which an image formed by the light of the subject passing through the optical system is located.

Table 1a shows a table of characteristics of the optical system of the present embodiment, in which data is obtained using light having a wavelength of 587.6nm, and the units of the Y radius, thickness, and 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, FOV is a field angle of the optical system, and TTL is a distance from an object side surface of the first lens to an imaging surface of the optical system on an optical axis.

In the present embodiment, the object-side surface and the image-side surface of any one of the first lens L1 through the sixth lens L6 are aspheric surfaces, and the surface shape x of each aspheric lens can be defined by, but is not limited to, the following aspheric surface formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius R of Y in table 1a above); k is a conic coefficient; ai is the correction coefficient of the i-th order of the aspherical surface. Table 1b shows the high-order coefficient A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each of the aspherical mirrors S1-S16 in the first embodiment.

TABLE 1b

Fig. 1b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the first embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 1b, the optical system according to the first embodiment can achieve good imaging quality.

Second embodiment

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

a first lens element L1 with positive refractive power having an object-side surface S1 of L1 being convex near the optical axis and near the circumference, an image-side surface S2 of L1 being concave near the optical axis and an image-side surface S2 being convex near the circumference;

a second lens element L2 with negative refractive power, the object-side surface S3 of the second lens element L2 being convex in the paraxial region, the object-side surface S3 being concave in the paraxial region, and the image-side surface S4 of the second lens element L2 being concave in the paraxial region and the peripheral region;

a third lens element L3 with negative dioptric power, the third lens element L3 having an object-side surface S5 convex at paraxial and peripherical proximity, and the third lens element L3 having an image-side surface S6 concave at paraxial and peripherical proximity;

a fourth lens element L4 with positive refractive power, the fourth lens element L4 being convex near the optical axis and near the object side S7, the fourth lens element L4 being concave near the optical axis and near the image side S8 being convex near the image side S8;

a fifth lens element L5 with positive refractive power, wherein an object-side surface S9 of the fifth lens element L5 is convex in a direction near the optical axis, an object-side surface S9 is concave in a direction near the circumference, and an image-side surface S10 of the fifth lens element L5 is convex in a direction near the optical axis and near the circumference;

the sixth lens element L6 with negative refractive power has a sixth lens element L6 with a convex object-side surface S11 at a paraxial region thereof, a concave object-side surface S11 at a paraxial region thereof, a concave image-side surface S12 at an image-side surface L6 at a paraxial region thereof, and a convex image-side surface S12 at a paraxial region thereof.

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 data is obtained using light having a wavelength of 587.6nm, and the units of the Y radius, thickness, and focal length are millimeters (mm).

TABLE 2a

Wherein the values of the parameters in Table 2a are the same as those of the first embodiment.

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 curve, an astigmatism curve and a distortion curve of the optical system of the second embodiment. As can be seen from fig. 2b, the optical system according to the second embodiment can achieve good imaging quality.

Third embodiment

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

a first lens element L1 with positive refractive power, the first lens element L1 having an object-side surface S1 convex at paraxial region and near circumference, and the first lens element L1 having an image-side surface S2 concave at paraxial region and near circumference;

a third lens element L3 with positive refractive power having a convex object-side surface S5 of the third lens element L3 at paraxial and peripherical points and a concave image-side surface S6 of the third lens element L3 at paraxial and peripherical points;

a fourth lens element L4 with positive refractive power, the object-side surface S7 of the fourth lens element L4 being convex in the paraxial region, the object-side surface S7 being concave in the paraxial region, and the image-side surface S8 of the fourth lens element L4 being convex in the paraxial region and the peripheral region;

a fifth lens element L5 with positive refractive power, wherein an object-side surface S9 of the fifth lens element L5 is convex near the optical axis, an object-side surface S9 is concave near the circumference, an image-side surface S10 of the fifth lens element L5 is convex near the optical axis, and an image-side surface S10 is concave near the circumference;

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 data is obtained using light having a wavelength of 587.6nm, and the units of the Y radius, thickness, and focal length are millimeters (mm).

TABLE 3a

Wherein the values of the parameters in Table 3a are the same as those of the first embodiment.

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 curve, an astigmatism curve and a distortion curve of the optical system of the third embodiment. As can be seen from fig. 3b, the optical system according to the third embodiment can achieve 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 along an optical axis direction, includes:

a third lens element L3 with positive refractive power having a convex object-side surface S5 of the third lens element L3 near the optical axis and near the circumference, and a convex image-side surface S6 of the third lens element L3 near the optical axis and near the circumference;

a fourth lens element L4 with negative refractive power, the object-side surface S7 of the fourth lens element L4 being convex in the paraxial region, the object-side surface S7 being concave in the paraxial region, and the image-side surface S8 of the fourth lens element L4 being concave in the paraxial region and the peripheral region;

a fifth lens element L5 with positive refractive power, the fifth lens element L5 having an object-side surface S9 being convex at a paraxial region thereof, an object-side surface S9 being concave at a paraxial region thereof, an image-side surface S10 of the fifth lens element L5 being concave at a paraxial region thereof, and an image-side surface S10 being convex at a paraxial region thereof;

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 data is obtained using light having a wavelength of 587.6nm, and the units of the Y radius, thickness, and focal length are millimeters (mm).

TABLE 4a

Wherein the values of the parameters in Table 4a are the same as those of the first embodiment.

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 curve, an astigmatism curve and a distortion curve of the optical system of the fourth embodiment. As can be seen from fig. 4b, the optical system according to the fourth embodiment can achieve 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 along an optical axis direction, includes:

a second lens element L2 with negative refractive power, the second lens element L2 having an object-side surface S3 being convex at a paraxial region thereof, an object-side surface S3 being concave at a paraxial region thereof, an image-side surface S4 of the second lens element L2 being concave at a paraxial region thereof, and an image-side surface S4 being convex at a paraxial region thereof;

a third lens element L3 with positive refractive power having an object-side surface S5 of the third lens element L3 being convex at a paraxial region and a paraxial region, an image-side surface S6 of the third lens element L3 being convex at a paraxial region and being concave at a paraxial region, and an image-side surface S6 being concave at a peripheral region;

a fourth lens element L4 with negative refractive power having an object-side surface S7 of L4 being concave at a paraxial region and a paraxial region, an image-side surface S8 of L4 being convex at a paraxial region and an image-side surface S8 being concave at a paraxial region;

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 data is obtained using light having a wavelength of 587.6nm, and the units of the Y radius, thickness, and focal length are millimeters (mm).

TABLE 5a

Wherein the meanings of the parameters in Table 5a are the same as those of the first embodiment.

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 curve, an astigmatism curve and a distortion curve of the optical system of the fifth embodiment. As can be seen from fig. 5b, the optical system according to the fifth embodiment can achieve good image quality.

Sixth embodiment

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

a second lens element L2 with negative dioptric power, the second lens element L2 having an object-side surface S3 convex at paraxial region and near circumference, and the second lens element L2 having an image-side surface S4 concave at paraxial region and near circumference;

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

a fourth lens element L4 with positive refractive power, the fourth lens element L4 having an object-side surface S7 that is concave at a paraxial region and at a paraxial region, the fourth lens element L4 having an image-side surface S8 that is convex at a paraxial region and at a paraxial region;

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

Table 6a shows a table of characteristics of the optical system of the present embodiment, in which data is obtained using light having a wavelength of 587.6nm, and the units of the Y radius, thickness, and focal length are millimeters (mm).

TABLE 6a

Wherein the values of the parameters in Table 6a are the same as those of the first embodiment.

Table 6b shows the high-order term coefficients that can be used for each aspherical mirror surface in the sixth embodiment, wherein each aspherical mirror surface type can be defined by the formula given in the first embodiment.

TABLE 6b

Fig. 6b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the sixth embodiment. As can be seen from fig. 6b, the optical system according to the sixth embodiment can achieve good image quality.

Seventh embodiment

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

a third lens element L3 with positive refractive power having an object-side surface S5 of the third lens element L3 being convex at a paraxial region and a paraxial region, an image-side surface S6 of the third lens element L3 being concave at a paraxial region and being convex at a paraxial region, and an image-side surface S6 being convex at a peripheral region;

a fourth lens element L4 with positive refractive power, the object-side surface S7 of the fourth lens element L4 being convex in the paraxial region, the object-side surface S7 being concave in the paraxial region, and the image-side surface S8 of the fourth lens element L4 being concave in the paraxial region and the peripheral region;

the sixth lens element L6 with negative refractive power has a convex object-side surface S11 near the optical axis and a concave object-side surface S11 near the circumference of the sixth lens element L6, and has a concave image-side surface S12 near the optical axis and a convex image-side surface S12 near the circumference of the sixth lens element L6;

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

Table 7a shows a table of characteristics of the optical system of the present embodiment, in which data is obtained using light having a wavelength of 587.6nm, and the units of the Y radius, thickness, and focal length are millimeters (mm).

TABLE 7a

Wherein the meanings of the parameters in Table 7a are the same as those of the first embodiment.

Table 7b shows the high-order term coefficients that can be used for each aspherical mirror surface in the seventh embodiment, wherein each aspherical mirror surface type can be defined by the formula given in the first embodiment.

TABLE 7b

Fig. 7b shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the seventh embodiment. As can be seen from fig. 7b, the optical system according to the seventh embodiment can achieve good image quality.

Table 8 is a value of | SAG41|/| SAG42|, (CT2+ CT3+ CT4)/(CT23+ CT34), f/| f3| + f/| f4|, | SAG61/CT6|, | R51| - | R52 |/| | R51| + | R52|, f123/| f56|, (CT1+ BF)/FNO, | f3|/n3, ET34/ImgH of the optical system of the first to seventh embodiments.

TABLE 8

	\|SAG41\|/\|SAG42\|	(CT2+CT3+CT4)/(CT23+CT34)	f/\|f3\|+f/\|f4\|	\|SAG61/CT6\|	\|f3\|/n3
						First embodiment	1.14	3.75	0.62	0.11	22.65
Second embodiment	19.75	5.80	0.62	0.67	17.05
						Third embodiment	0.06	4.52	0.56	1.50	14.70
Fourth embodiment	1.31	2.21	0.56	1.4	6.29
						Fifth embodiment	1.16	5.59	0.63	0.22	6.15
Sixth embodiment	0.52	2.50	0.39	0.68	7.95
						Seventh embodiment	0.76	8.50	0.77	1.80	8.50
	f123/\|f56\|	\|\|R51\|-\|R52\|\|/\|\|R51\|+\|R52\|\|	(CT1+BF)/FNO	ET34/ImgH
						First embodiment	0.12	0.31	0.78	0.12
Second embodiment	0.36	0.59	0.83	0.03
						Third embodiment	0.35	0.68	0.65	0.03
Fourth embodiment	0.19	0.34	0.64	0.06
						Fifth aspect of the inventionExamples of the embodiments	0.10	0.68	0.85	0.01
Sixth embodiment	0.06	0.21	0.66	0.08
						Seventh embodiment	0.22	0.80	0.66	0.02

As can be seen from table 11, each example satisfies the following conditional expression: i SAG 41I/I SAG42 < 20.0, 2.2 < (CT2+ CT3+ CT4)/(CT23+ CT34) < 8.5, 0.35 < f/| f3| + f/| f4| < 0.8, | SAG61/CT6| < 1.8, 0.2 < | R51| - | R52 |/| R51| + | R52| < 0.8, f123/| f 8 | < 0.36, 0.60 < (CT1+ BF)/FNO < 0.85, 6.1 < | 3| n3 < 22.7, ET 34/gH 0.12.

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

The above examples only represent some embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

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

the first lens element with positive refractive power has a convex object-side surface;

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

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

the fourth lens element with refractive power has an object-side surface and an image-side surface which are both aspheric;

the fifth lens element with positive refractive power has a concave object-side surface near the circumference, both the object-side surface and the image-side surface of the fifth lens element are aspheric, and at least one of the object-side surface and the image-side surface of the fifth lens element is provided with at least one inflection point;

the sixth 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; the object side surface and the image side surface of the sixth lens are both aspheric surfaces, and at least one of the object side surface and the image side surface of the sixth lens is provided with at least one inflection point.

2. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

|SAG41|/|SAG42|＜20.0；

wherein SAG41 is the sagittal height at the maximum effective aperture of the object side surface of the fourth lens and SAG42 is the sagittal height at the maximum effective aperture of the image side surface of the fourth lens.

3. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

2.2＜(CT2+CT3+CT4)/(CT23+CT34)≤8.5；

wherein, CT2 is the thickness of the second lens element on the optical axis, CT3 is the thickness of the third lens element on the optical axis, CT4 is the thickness of the fourth lens element on the optical axis, CT23 is the distance between the image-side surface of the second lens element and the object-side surface of the third lens element on the optical axis, and CT34 is the distance between the image-side surface of the third lens element and the object-side surface of the fourth lens element on the optical axis.

4. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.35＜f/|f3|+f/|f4|＜0.8；

wherein f is an effective focal length of the optical system, f3 is an effective focal length of the third lens, and f4 is an effective focal length of the fourth lens.

5. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

|SAG61/CT6|≤1.8；

wherein SAG61 is the sagittal height at the sixth lens object side effective aperture and CT6 is the thickness of the sixth lens on the optical axis.

6. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.2＜||R51|-|R52||/(|R51|+|R52|)≤0.8；

wherein R51 is a radius of curvature of the fifth lens object-side surface at the optical axis, and R52 is a radius of curvature of the fifth lens image-side surface at the optical axis.

7. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

f123/|f56|≤0.36；

wherein f123 is a total effective focal length of the first lens, the second lens, and the third lens, and f56 is a total effective focal length of the fifth lens and the sixth lens.

8. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.60mm＜(CT1+BF)/FNO≤0.85mm；

CT1 is the thickness of the first lens on the optical axis, BF is the axial distance between the farthest point of the image side surface of the sixth lens and the image surface, and FNO is the f-number of the optical system.

9. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

6.1＜|f3|/n3＜22.7；

wherein f3 is the third lens effective focal length and n3 is the refractive index of the third lens material at a wavelength of 587.6 nm.

10. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

ET34/ImgH≤0.12；

ET34 is an axial distance between the maximum effective aperture of the image-side surface of the third lens element and the maximum effective aperture of the object-side surface of the fourth lens element, and ImgH is a half of a diagonal length of an effective imaging area of the optical system on an imaging surface.

11. A lens module comprising a lens barrel, an electro-optic sensing element and the optical system according to any one of claims 1 to 10, wherein the first to sixth lenses of the optical system are mounted in the lens barrel, and the electro-optic sensing element is disposed on an image side of the optical system and is configured to convert light rays of an object incident on the electro-optic sensing element through the first to sixth lenses into an electrical signal of an image.

12. An electronic device comprising a housing and the lens module as recited in claim 11, wherein the lens module is disposed in the housing.