CN212540839U

CN212540839U - Optical system, lens module and electronic equipment

Info

Publication number: CN212540839U
Application number: CN202021116025.5U
Authority: CN
Inventors: 党绪文; 李明; 刘彬彬; 邹海荣
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2020-06-16
Filing date: 2020-06-16
Publication date: 2021-02-12
Anticipated expiration: 2030-06-16

Abstract

The utility model provides an optical system, lens module and electronic equipment, optical system contains first lens to sixth lens along the object side of optical axis direction to picture side in proper order, and first lens has negative refractive power, and the second lens has positive refractive power, and third lens to sixth lens all have refractive power, and the object side of first lens is the convex surface in the circumference department, and the object side of second lens, fourth lens and sixth lens is the convex surface in the optical axis department, and the object side of fifth lens is the concave surface in the optical axis department; the image side surface of the first lens is concave at the optical axis and at the circumference, the image side surface of the sixth lens is convex at the circumference, 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, and by arranging the six-piece lens structure, the refractive power and the surface type of the six optical lenses are reasonably configured, so that the optical system has higher pixels, wider imaging range and larger light incoming amount when imaging at a macro, and further development of macro imaging is promoted.

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

With the wide introduction of a plurality of groups of camera lenses into smart phones and smart electronic devices, both telephoto lenses and conventional focus lenses cannot meet the requirement of macro-shooting, and when the camera lenses are used for shooting macro-objects, the situation that the field of view is not focused actually often occurs, so that the overall image quality of an imaging picture is affected; in order to improve the macro shooting capability, a macro lens with a macro shooting effect can be matched, and a low-pixel sensor and an f-number larger than 2.4 are mostly used in a commonly used macro lens, however, the light input amount of the lens is limited, and the light energy captured by a Complementary Metal Oxide Semiconductor (CMOS) is not enough to satisfy high-image-quality imaging, so that the further development of the macro imaging is limited.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an optical system, camera lens module and electronic equipment can solve above-mentioned problem.

For realizing the purpose of the utility model, the utility model provides a following technical scheme:

in a first aspect, the present invention provides an optical system, which includes, in order from an object side to an image side along an optical axis direction: the first lens element with negative refractive power has a convex object-side surface at the circumference, and has a concave image-side surface at the optical axis and at the circumference; the second lens element with positive refractive power has a convex object-side surface at an optical axis; a third lens element with refractive power; the fourth lens element with refractive power has a convex object-side surface at an optical axis; the fifth lens element with refractive power has a concave object-side surface at an optical axis; the sixth lens element with refractive power has a convex object-side surface at an optical axis, a convex image-side surface at a circumference, and at least one inflection point on at least one of the object-side surface and the image-side surface of the sixth lens element.

By arranging the six-piece lens structure, the refractive power and the surface shape of the six optical lenses are reasonably configured, so that the overall image quality of a picture of the optical system during macro imaging is improved, the light incoming quantity of the system is increased, and the further development of macro imaging is promoted.

In one embodiment, the optical system satisfies the conditional expression: 41.0deg < FOV/FNO < 57.5 deg; wherein, FOV is the maximum field angle of the optical system, and FNO is the f-number of the optical system. Satisfying the above relation, on the premise of covering more scenes, it can provide enough large light-entering aperture, ensure enough luminous flux, and make the optical system obtain considerable relative brightness in macro-imaging.

In one embodiment, the optical system satisfies the conditional expression: IMGH/| OBJH | < 0.165; the IMGH is the image height corresponding to half of the maximum field angle of the optical system, and the OBJH is the object height corresponding to half of the maximum field angle of the optical system. The size of the electronic photosensitive chip is determined by IMGH, and the larger the IMGH is, the larger the supportable maximum electronic photosensitive chip size is, and the higher the pixel support is. The optical system is a macro system, can shoot close-range tiny objects, meets the above formula, and can enable the tiny objects to form amplified images on the photosensitive chip; particularly, when IMGH/| OBJH | >0.05 and the matched 1.12um chip is on the equivalent image surface converted by the single-pixel 6.6um full-frame chip, the imaging magnification is about equal to 0.6 times, and through reasonable refractive power configuration, low-frequency details of an object can be captured easily, and high-quality imaging under a microspur is met.

In one embodiment, the optical system satisfies the conditional expression: OBJZ/f is more than 6.5 and less than 67.0; the OBJZ is the distance from the object plane of the optical system to the object side surface of the first lens on the optical axis, and f is the effective focal length of the optical system. The macro shooting range of the utility model covers 10mm-100mm, and the visual angle exceeding 90 degrees is assisted, thus greatly improving the imaging range of the macro lens; in particular, the minimum focal length of the macro is 10mm, the minimum f can reach 1.35, and the micro and the Fmin provide support for ultra-small distance imaging; the smaller f, the easier it is to realize a wide-angle characteristic. By providing a field angle larger than 90 degrees and matching with the refractive power configuration of each lens, the imaging effect that the distortion of an imaged object is small and the curvature of field of the marginal field of view is small is realized.

In one embodiment, the optical system satisfies the conditional expression: i f 4/| f5| < 4.5; wherein f4 is the effective focal length of the fourth lens, and f5 is the effective focal length of the fifth lens. The fourth lens element and the fifth lens element provide different refractive powers, which facilitates control of curvature of field, astigmatism and spherical aberration of the system; the surface type change of the fourth lens and the fifth lens is beneficial to reducing the emergence angle of marginal rays, so that the tolerance system sensitivity is reduced; the low-distance arrangement of the fourth lens and the fifth lens avoids secondary reflection ghost images caused by air gaps to a certain extent.

In one embodiment, the optical system satisfies the conditional expression: i R42I/I R51I < 13.0; wherein R42 is the radius of curvature of the fourth lens element at the optical axis, and R51 is the radius of curvature of the fifth lens element at the optical axis. The utility model discloses a put the wide angle system of diaphragm in, preceding three lens form the positive or negative positive structure for the system possesses good structural compatibility, even fourth lens and fifth lens face type are complicated, still can obtain the imaging quality of preferred.

In one embodiment, the optical system satisfies the conditional expression: 0.7 < (| R31| + | R22|)/| f3| < 1.5; wherein R31 is the radius of curvature of the third lens object-side surface at the optical axis, and R22 is the radius of curvature of the second lens image-side surface at the optical axis; f3 is the effective focal length of the third lens. The wide-angle structure of the middle diaphragm is matched with the negative and positive focal power combination of the front two lenses (the first lens and the second lens), and good flexibility is provided for the design of a system through the movement of the small-caliber lower diaphragm; the surface shape change of the third lens element, in combination with the reasonable configuration of refractive power, can improve the imaging pixels of the system and reduce the field curvature and astigmatism of the external field of view.

In one embodiment, the optical system satisfies the conditional expression: 3.0 < | f6|/| SAG62| < 624.0; wherein f6 is an effective focal length of the sixth lens, and SAG62 is a distance between an edge of an image-side optically effective area of the sixth lens projected on an optical axis to an intersection of an image-side surface of the sixth lens and the optical axis. At least one inflection point is provided by the large-aperture sixth lens, and the configuration of the refractive power perpendicular to the optical axis direction can be balanced by matching with the complex change on the surface type, so that the stable change of the resolving power and the aberration of each field is kept, and the support is provided for the low-angle incidence of light rays on the image surface.

In one embodiment, the optical system satisfies the conditional expression: SD1/BF is more than 0.9 and less than 2.5; the SD1 is a half of the effective aperture of the object side surface of the first lens, and the BF is the shortest distance on the optical axis from the image side surface of the sixth lens to the imaging surface of the optical system. SD1 represents the head of the lens, the smaller the SD1, the smaller the exposed size of the lens, and the better the concealment in application; the BF back focal length is larger than 0.64mm, so that the matching between the lens and the photosensitive chip can be better met, and the assembly difficulty is reduced.

In a second aspect, the present invention further provides a lens module, which includes the optical system of any one of the embodiments of the first aspect. Through adding in the camera lens module the utility model provides an optical system promotes the image quality when camera lens module shoots the microspur object, increases the camera lens light inlet amount.

A third aspect, the present invention further provides an electronic device, which includes a housing and a second aspect, wherein the lens module is disposed in the housing. Through adding in electronic equipment the utility model provides a lens module for electronic equipment has higher microspur and shoots performance and competitiveness.

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 the 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.

FIG. 8a is a schematic structural diagram of an optical system of an eighth embodiment;

fig. 8b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the eighth 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 work all belong to the protection scope of the present invention.

The present invention provides an optical system including, in order from an object side to an image side along an optical axis, 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. Any adjacent two lenses of the first to sixth 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 negative refractive power has a convex object-side surface at the circumference, and a concave image-side surface at the optical axis and at the circumference; the second lens element with positive refractive power has a convex object-side surface at the optical axis; a third lens element with refractive power; a fourth lens element with refractive power having a convex object-side surface at an optical axis; the fifth lens element with refractive power has a concave object-side surface at an optical axis; the sixth lens element with refractive power has a convex object-side surface at an optical axis, a convex image-side surface at a circumference, and at least one inflection point on at least one of the object-side surface and the image-side surface of the sixth lens element.

The optical system further comprises a diaphragm, and the diaphragm can be arranged at any position from the object plane to the sixth lens, such as between the first lens and the second lens.

By arranging the six-piece lens structure, the refractive power and the surface shape of the six optical lenses are reasonably configured, so that the optical system has a wider imaging range and a larger light incoming amount while having higher pixels in macro imaging.

An infrared cut-off filter can be arranged between the sixth lens and the imaging surface and is used for transmitting visible light wave bands and cutting off infrared light wave bands, so that the phenomenon of false color or ripple caused by interference of light waves in non-working wave bands is avoided, and meanwhile, the effective resolution and the color reducibility can be improved.

In one embodiment, the optical system satisfies the conditional expression: 41.0deg < FOV/FNO < 57.5 deg; wherein, FOV is the maximum field angle of the optical system, and FNO is the f-number of the optical system. The maximum field angle FOV is larger than 90 degrees, the relational expression is satisfied, and the method can cover more scenes. And the light inlet aperture is large enough to ensure enough luminous flux, so that the optical system can obtain considerable relative brightness during macro-imaging.

In one embodiment, the optical system satisfies the conditional expression: IMGH/| OBJH | < 0.165; the IMGH is an image height corresponding to half of the maximum field angle of the optical system, and the obj is an object height corresponding to half of the maximum field angle of the optical system. The size of the electronic photosensitive chip is determined by IMGH, and the larger the IMGH is, the larger the supportable maximum electronic photosensitive chip size is, and the higher the pixel support is. The optical system is a macro system, can shoot close-range tiny objects, satisfies the above formula, and can make the tiny objects form an amplified image on the photosensitive chip; particularly, when IMGH/| OBJH | >0.05 and the matched 1.12um chip is on the equivalent image surface converted by the single-pixel 6.6um full-frame chip, the imaging magnification is about equal to 0.6 times, and through reasonable refractive power configuration, low-frequency details of an object can be captured easily, and high-quality imaging under a microspur is met.

In one embodiment, the optical system satisfies the conditional expression: OBJZ/f is more than 6.5 and less than 67.0; the OBJZ is the distance from the object plane of the optical system to the object side surface of the first lens on the optical axis; f is the effective focal length of the optical system. The macro shooting range of the embodiment covers 10mm-100mm, and a visual angle exceeding 90 degrees is adopted, so that the imaging range of the optical system is greatly improved; in particular, the minimum focal length of the macro is 10mm, the minimum f can reach 1.35, and the micro and the Fmin provide support for ultra-small distance imaging; the smaller f, the easier it is to realize a wide-angle characteristic. By providing a field angle larger than 90 degrees and matching with the refractive power configuration of each lens, the imaging effect that the distortion of an imaged object is small and the curvature of field of the marginal field of view is small is realized.

In one embodiment, the optical system satisfies the conditional expression: i R42I/I R51I < 13.0; wherein, R42 is the radius of curvature of the image-side surface of the fourth lens element at the optical axis, and R51 is the radius of curvature of the object-side surface of the fifth lens element at the optical axis. The utility model discloses a put the wide angle system of diaphragm in, preceding three lens form the positive or negative positive structure for the system possesses good structural compatibility, lets fourth lens and fifth lens face type take place under the complicated condition, still can obtain the imaging quality of preferred.

In one embodiment, the optical system satisfies the conditional expression: 0.7 < (| R31| + | R22|)/| f3| < 1.5; wherein R31 is the radius of curvature of the object-side surface of the third lens element at the optical axis, and R22 is the radius of curvature of the image-side surface of the second lens element at the optical axis; f3 is the effective focal length of the third lens. The wide-angle structure of the middle diaphragm is matched with the negative and positive focal power combination of the front two lenses (the first lens and the second lens), and good flexibility is provided for the design of a system through the movement of the small-caliber lower diaphragm; the surface shape change of the third lens element, in combination with the reasonable configuration of refractive power, can improve the image quality of the system and reduce the field curvature and astigmatism of the external field of view.

In one embodiment, the optical system satisfies the conditional expression: 3.0 < | f6|/| SAG62| < 624.0; wherein f6 is an effective focal length of the sixth lens, and SAG62 is a distance between an edge of an image-side optically effective area of the sixth lens projected on an optical axis to an intersection of the image-side surface of the sixth lens and the optical axis. At least one inflection point is provided by the large-aperture sixth lens, and the configuration of the refractive power perpendicular to the optical axis direction can be balanced by matching with the complex change on the surface type, so that the stable change of the resolving power and the aberration of each field is kept, and the support is provided for the low-angle incidence of light rays on the image surface.

In one embodiment, the optical system satisfies the conditional expression: SD1/BF is more than 0.9 and less than 2.5; wherein SD1 is half of the effective aperture of the object-side surface of the first lens, and BF is the shortest distance on the optical axis from the image-side surface of the sixth lens to the imaging surface of the optical system. SD1 represents the head of the lens, the smaller the SD1, the smaller the exposed size of the lens, and the better the concealment in application; the BF back focal length is larger than 0.64mm, so that the matching between the lens and the photosensitive chip can be better met, and the assembly difficulty is reduced.

The embodiment of the utility model provides a lens module, this lens module include lens cone, photosensitive element and the utility model provides an optical system, optical system's first lens are installed in the lens cone to sixth lens, and electronic photosensitive element's photosurface is located optical system's imaging surface, and the light that passes first lens to the incident thing on electronic photosensitive element's the photosurface of sixth lens can convert the signal of telecommunication of image into, and electronic photosensitive element can be CMOS or Charge-coupled Device (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, a tablet personal computer and the like. Through adding in the camera lens module the utility model provides an optical system for image quality is higher when the camera lens module has the macro shooting, the bigger performance of light inlet quantity.

An embodiment of the utility model provides an electronic equipment, this electronic equipment include the casing with the embodiment of the utility model provides a lens module, lens module set up in the casing. 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 adding in electronic equipment the utility model provides a lens module for electronic equipment has higher microspur and shoots performance and competitiveness.

First embodiment

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

the first lens element L1 with negative refractive power has a convex object-side surface S1 of the first lens element L1 along the optical axis and along the circumference, and a concave image-side surface S2 of the first lens element L1 along the optical axis and along the circumference;

the second lens element L2 with positive refractive power has a convex object-side surface S3 and a convex image-side surface S4 both along the optical axis and along the circumference of the second lens element L2, and both along the optical axis and along the circumference of the second lens element L2;

the third lens element L3 with negative refractive power has a concave object-side surface S5 at the circumference and on the optical axis of the third lens element L3, and an image-side surface S6 of the third lens element L3 is concave on the optical axis and convex on the circumference;

the fourth lens element L4 with negative refractive power has a convex object-side surface S7 of the fourth lens element L4 along the optical axis and a concave object-side surface S8 along the circumference, wherein the optical axis and the circumference of the image-side surface S8 of the fourth lens element L4 are both concave;

the fifth lens element L5 with positive refractive power has a concave object-side surface S9 at the optical axis and a convex object-side surface at the circumference of the fifth lens element L5, and an image-side surface S10 at the optical axis and the circumference of the fifth lens element are both convex;

the sixth lens element L6 with negative refractive power has at least one inflection point on at least one of the object-side surface S11 and the image-side surface S12 of the sixth lens element L6; the object-side surface S11 of the sixth lens element L6 is convex along the optical axis and concave along the circumference, and the image-side surface S12 of the sixth lens element L6 is concave along the optical axis and convex along the circumference.

The first lens element L1 to the sixth lens element L6 are all made of Plastic (Plastic).

Further, the optical system includes a stop STO, an infrared cut filter IR, and an imaging surface IMG. The stop STO is provided between the first lens L1 and the second lens L2, and controls the amount of light entering. In other embodiments, the stop STO can also be arranged at any position between the object plane and the sixth lens. The infrared cut filter IR is disposed between the image side surface S12 and the image side surface IMG of the sixth lens L6, and includes an object side surface S13 and an image side surface S14, and the infrared cut filter is configured to filter out infrared light, so that the light entering the image side surface IMG is visible light, and the wavelength of the visible light is 380nm to 780 nm. The infrared cut-off filter is made of GLASS (GLASS), and can be coated with a film on the GLASS. The effective pixel area of the electronic photosensitive element is positioned on the imaging surface IMG.

Table 1a shows a table of characteristics of the optical system of the present embodiment in which each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all millimeters (mm).

TABLE 1a

Wherein, EFL is an effective focal length of the optical system, FNO is an f-number of the optical system, FOV is a maximum field angle of the optical system, and TTL is a distance from the object-side surface S1 of the first lens L1 to the image plane IMG on the 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-S12 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 imaging plane curvature and sagittal imaging plane 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:

the first lens element L1 with negative refractive power has a concave object-side surface S1 of the first lens element L1 along the optical axis and a convex object-side surface S2 along the circumference, and both the optical axis and the concave image-side surface S2 of the first lens element L1 along the circumference;

the second lens element L2 with positive refractive power has a convex object-side surface S3 of the second lens element L2 along the optical axis and along the circumference, and has a convex image-side surface S4 of the second lens element L2 along the optical axis and along the circumference;

the third lens element L3 with negative refractive power has a concave object-side surface S5 at the optical axis and a concave object-side surface at the circumference of the third lens element L3, and has a convex image-side surface S6 at the optical axis and a concave image-side surface at the circumference of the third lens element L3;

the fourth lens element L4 with positive refractive power has a convex object-side surface S7 of the fourth lens element L4 along the optical axis and a concave object-side surface S8 along the circumference, wherein the optical axis and the circumference of the image-side surface S8 of the fourth lens element L4 are both convex;

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

the sixth lens element L6 with positive refractive power has at least one inflection point on at least one of the object-side surface S11 and the image-side surface S12 of the sixth lens element L6; the object-side surface S11 of the sixth lens element L6 is convex along the optical axis and concave along the circumference, and the image-side surface S12 of the sixth lens element L6 is concave along the optical axis and convex along the circumference;

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 each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all 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, wherein the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curves represent meridional imaging plane curvature and sagittal imaging plane curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. 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:

the second lens element L2 with positive refractive power has a convex object-side surface S3 at the optical axis and a concave surface at the circumference of the second lens element L2, and has a convex image-side surface S4 at the optical axis and the circumference of the second lens element L2;

the third lens element L3 with negative refractive power has a convex object-side surface S5 of the third lens element L3 along the optical axis and along the circumference, and a concave image-side surface S6 of the third lens element L3 along the optical axis and along the circumference;

the fourth lens element L4 with positive refractive power has a convex object-side surface S7 of the fourth lens element L4 along the optical axis and along the circumference, and has a convex image-side surface S8 of the fourth lens element L4 along the optical axis and along the circumference;

the fifth lens element L5 with negative refractive power has a concave object-side surface S9 at the optical axis and at the circumference of the fifth lens element L5, and an convex image-side surface S10 at the optical axis and at the circumference of the fifth lens element L5;

the sixth lens element L6 with positive refractive power has at least one inflection point on at least one of the object-side surface S11 and the image-side surface S12 of the sixth lens element L6; the object-side surface S11 of the sixth lens element L6 is convex along the optical axis and concave along the circumference, and the image-side surface S12 of the sixth lens element L6 is convex along the optical axis and 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 each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all 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, wherein the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curves represent meridional imaging plane curvature and sagittal imaging plane curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. 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:

the second lens element L2 with positive refractive power has a convex object-side surface S3 of the second lens element L2 along the optical axis, and a concave image-side surface S4 of the second lens element L2 along the optical axis and along the circumference;

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

the fourth lens element L4 with positive refractive power has a convex object-side surface S7 of the fourth lens element L4 along the optical axis and along the circumference, and an image-side surface S8 of the fourth lens element L4 along the optical axis and along the circumference;

the fifth lens element L5 with negative refractive power has a concave object-side surface S9 and a concave image-side surface S10, both along the optical axis and along the circumference, of the fifth lens element L5;

the sixth lens element L6 with positive refractive power has at least one inflection point on at least one of the object-side surface S11 and the image-side surface S12 of the sixth lens element L6; the object-side surface S11 of the sixth lens element L6 is convex along the optical axis and at the circumference, and the image-side surface S12 of the sixth lens element L6 is convex along the optical axis and at the circumference.

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 each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all 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, wherein the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curves represent meridional imaging plane curvature and sagittal imaging plane curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. 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:

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

the fourth lens element L4 with positive refractive power has a convex object-side surface S7 at the optical axis and at the circumference of the fourth lens element L4, and an image-side surface S8 of the fourth lens element L4 is concave at the optical axis and convex at the circumference;

the sixth lens element L6 with positive refractive power has at least one inflection point on at least one of the object-side surface S11 and the image-side surface S12 of the sixth lens element L6; the object-side surface S11 of the sixth lens element L6 is convex along the optical axis and concave along the circumference, and the image-side surface S12 of the sixth lens element L6 is concave along the optical axis and convex along the circumference.

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 each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all 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, wherein the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curves represent meridional imaging plane curvature and sagittal imaging plane curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. 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:

the third lens element L3 with negative refractive power has a concave object-side surface S5 at the optical axis and a concave circumference of the third lens element L3, and has a convex image-side surface S6 at the optical axis and a concave circumference of the third lens element L3.

the fifth lens element L5 with negative refractive power has a concave object-side surface S9 at the optical axis and a concave object-side surface at the circumference of the fifth lens element L5, and has a convex image-side surface S10 at the optical axis and a concave image-side surface at the circumference;

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 each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all 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, wherein the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curves represent meridional imaging plane curvature and sagittal imaging plane curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. 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:

the third lens element L3 with negative refractive power has a concave object-side surface S5 at the optical axis and at the circumference of the third lens element L3, and a convex image-side surface S6 at the optical axis and at the circumference of the third lens element L3.

The fourth lens element L4 with positive refractive power has a convex object-side surface S7 at the optical axis and at the circumference of the fourth lens element L4, and a convex image-side surface S8 at the optical axis and at the circumference of the fourth lens element L4;

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 each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all 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, wherein the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curves represent meridional imaging plane curvature and sagittal imaging plane curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 7b, the optical system according to the seventh embodiment can achieve good image quality.

Eighth embodiment

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

The fourth lens element L4 with negative refractive power has a convex object-side surface S7 at the optical axis and a concave object-side surface at the circumference of the fourth lens element L4, and has a concave image-side surface S8 at the optical axis and a convex image-side surface at the circumference of the fourth lens element L4;

the fifth lens element L5 with positive refractive power has a concave object-side surface S9 and a convex image-side surface S10, both along the optical axis and along the circumference, of the fifth lens element L5;

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

Table 8a shows a table of characteristics of the optical system of the present embodiment in which each data is obtained using visible light having a wavelength of 587.6nm, and the units of the Y radius, the thickness, and the effective focal length are all millimeters (mm).

TABLE 8a

Wherein the meanings of the respective parameters in Table 8a are the same as those of the first embodiment.

Table 8b shows the high-order term coefficients that can be used for each aspherical mirror surface in the eighth embodiment, wherein each aspherical mirror surface type can be defined by the formula given in the first embodiment.

TABLE 8b

FIG. 8b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the eighth embodiment, wherein the longitudinal spherical aberration curves represent the convergent focus deviations of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curves represent meridional imaging plane curvature and sagittal imaging plane curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 8b, the optical system according to the eighth embodiment can achieve good imaging quality.

Table 9 shows values of FOV/FNO, IMGH/| OBJH |, OBJZ/f, | f4|/| f5|, | R42|/| R51|, (| R31| + | R22 |)/|) f3|, | f6|/| SAG62|, SD1/BF in the optical systems of the first to eighth embodiments.

TABLE 9

As can be seen from table 9, the optical systems of the first to eighth embodiments all satisfy the following conditional expressions: 41.0deg < FOV/FNO < 57.5deg, IMGH/| OBJH | < 0.165, 6.5 < OBJZ/f < 67.0, | f4|/| f5| < 4.5, | R42|/| R51| < 13.0, 0.7 < (| R31| + | R22|)/| f3| < 1.5, 3.0 < | f6|/| SAG62| < 624.0, 0.9 < SD1/BF < 2.5.

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

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 negative refractive power has a convex object-side surface at the circumference, and has a concave image-side surface at the optical axis and at the circumference;

the second lens element with positive refractive power has a convex object-side surface at an optical axis;

a third lens element with refractive power;

the fourth lens element with refractive power has a convex object-side surface at an optical axis;

the fifth lens element with refractive power has a concave object-side surface at an optical axis;

the sixth lens element with refractive power has a convex object-side surface at an optical axis, a convex image-side surface at a circumference, and at least one inflection point on at least one of the object-side surface and the image-side surface of the sixth lens element.

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

41.0deg＜FOV/FNO＜57.5deg；

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

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

IMGH/|OBJH|＜0.165；

the IMGH is the image height corresponding to half of the maximum field angle of the optical system, and the OBJH is the object height corresponding to half of the maximum field angle of the optical system.

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

6.5＜OBJZ/f＜67.0；

the OBJZ is the distance from the object plane of the optical system to the object side surface of the first lens on the optical axis; f is the effective focal length of the optical system.

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

|f4|/|f5|＜4.5；

wherein f4 is the effective focal length of the fourth lens, and f5 is the effective focal length of the fifth lens.

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

|R42|/|R51|＜13.0；

wherein R42 is the radius of curvature of the fourth lens element at the optical axis, and R51 is the radius of curvature of the fifth lens element at the optical axis.

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

0.7＜(|R31|+|R22|)/|f3|＜1.5；

wherein R31 is a radius of curvature of the object-side surface of the third lens element at the optical axis, R22 is a radius of curvature of the image-side surface of the second lens element at the optical axis, and f3 is an effective focal length of the third lens element.

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

3.0＜|f6|/|SAG62|＜624.0；

wherein f6 is an effective focal length of the sixth lens, and SAG62 is a distance between an edge of an image-side optically effective area of the sixth lens projected on an optical axis to an intersection of an image-side surface of the sixth lens and the optical axis.

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

0.9＜SD1/BF＜2.5；

the SD1 is a half of the effective aperture of the object side surface of the first lens, and the BF is the shortest distance on the optical axis from the image side surface of the sixth lens to the imaging surface of the optical system.

10. A lens module comprising a lens barrel, a photosensitive element, and the optical system according to any one of claims 1 to 9, wherein the first to sixth lenses of the optical system are mounted in the lens barrel, and the photosensitive element is disposed on the image side of the optical system.

11. An electronic apparatus, comprising a housing and the lens module as recited in claim 10, wherein the lens module is disposed in the housing.