CN111624736A

CN111624736A - Optical system, lens module and electronic equipment

Info

Publication number: CN111624736A
Application number: CN202010422488.2A
Authority: CN
Inventors: 谢晗; 刘彬彬; 李明; 邹海荣
Original assignee: OFilm Tech Co Ltd
Current assignee: Nanchang OFilm Precision Optical Products Co Ltd; OFilm Group Co Ltd
Priority date: 2020-05-18
Filing date: 2020-05-18
Publication date: 2020-09-04

Abstract

The application provides an optical system, a lens module and an electronic device, the optical system includes in order from an object side to an image side along an optical axis direction: the first lens element with positive refractive power has a convex object-side surface at a paraxial region; a second lens element with refractive power; the third lens element with negative refractive power has a concave image-side surface at the paraxial region; a fourth lens element with negative refractive power; the fifth lens element with positive refractive power has a convex object-side surface and a convex image-side surface at paraxial regions thereof, and the object-side surface has at least one inflection point; the sixth lens element with negative refractive power has a convex object-side surface at the paraxial region and a concave image-side surface at the paraxial region, and the image-side surface has at least one inflection point; the optical system satisfies: CT1/TTL > 0.2; the CT1 is the thickness of the first lens element on the optical axis, and the TTL is the distance from the object-side surface of the first lens element to the image plane on the optical axis. By reasonably configuring the surface type and focal power of the first lens, the second lens, the third lens and the fourth lens, the optical system can ensure high resolution and high imaging quality and has the characteristic of miniaturization.

Description

Optical system, lens module and electronic equipment

Technical Field

The present invention relates to the field of optical imaging technologies, and in particular, to an optical system, a lens module, and an electronic device.

Background

With the continuous development of the related camera technology, the camera function has become a standard function of the intelligent electronic product, however, with the refinement of the semiconductor process technology, the pixel size of the photosensitive element is gradually reduced, the size of the optical system is also dedicated to the corresponding reduction, meanwhile, the optical system is gradually developed in the high pixel field, the requirement for the imaging quality is also increased, and the miniaturization characteristic of the optical system needs to meet the higher requirement. Therefore, how to achieve the characteristics of miniaturization while ensuring high resolution and high imaging quality is an urgent technical problem to be solved.

Disclosure of Invention

The invention aims to provide an optical system, a lens module and an electronic device, which can ensure high resolution and high imaging quality and have the characteristic of miniaturization.

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

in a first aspect, the present invention provides an optical system, in order from an object side to an image side along an optical axis direction, comprising: the first lens element with positive refractive power has a convex object-side surface at a paraxial region; a second lens element with refractive power; the third lens element with negative refractive power has a concave image-side surface at the paraxial region; a fourth lens element with negative refractive power; the fifth lens element with positive refractive power has a convex object-side surface and a convex image-side surface, and the object-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, and at least one inflection point is arranged on an image-side surface of the sixth lens element; the optical system satisfies the conditional expression: CT1/TTL > 0.2; wherein CT1 is a thickness of the first lens element on an optical axis, and TTL is a distance from an object-side surface of the first lens element to an image plane of the optical system on the optical axis. By reasonably setting the value of CT1/TTL, the optical system has the characteristics of small caliber and large depth, thereby realizing miniaturization of the optical system and being beneficial to the optical system to be carried on high-end mobile phones such as a full screen.

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 ensure high resolution and high imaging quality and has the characteristic of miniaturization.

In one embodiment, the optical system satisfies the conditional expression: y1<0.9 mm; wherein Y1 is the optical effective radius of the object side surface of the first lens. By reasonably setting the value of Y1, the outer diameter of the object side surface of the first lens is favorably controlled not to be excessively increased, so that the appearance of the small head of the optical system is ensured.

In one embodiment, the optical system satisfies the conditional expression: CT1 is more than or equal to 1.0 mm; wherein CT1 is the thickness of the first lens on the optical axis. Through the value of reasonable setting CT1, can increase the optical system degree of depth is favorable to optical system assembles on high-end models such as comprehensive screen.

In one embodiment, the optical system satisfies the conditional expression: ET1>0.8 mm; wherein ET1 is the rim thickness of the first lens. Through the value of reasonable setting ET1, be favorable to guaranteeing first lens have sufficient marginal thickness, make the portion of leaning on of first lens moves to the direction of image plane, and then can make optical system's head realizes miniaturizing.

In one embodiment, the optical system satisfies the conditional expression: TTL/ImgH is less than or equal to 1.7; wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system, and ImgH is a half of a diagonal length of an effective imaging area of the optical system on the imaging surface. By reasonably setting the TTL/ImgH value, the length of the whole optical system can not be excessively increased while the thickness of the first lens is increased.

In one embodiment, the optical system satisfies the conditional expression: -8.1< R51/R52< -2.2; 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. By properly setting the value of R51/R52, it is more beneficial to image the fifth lens in cooperation with the first lens, and further control the length of the whole optical system not to be excessively increased.

In one embodiment, the optical system satisfies the conditional expression: 0.58< f1/f < 0.93; wherein f1 is the effective focal length of the first lens, and f is the effective focal length of the optical system. By reasonably setting the value of f1/f, the length of the optical system is favorably controlled, and the field curvature is corrected to a certain extent.

In one embodiment, the optical system satisfies the conditional expression: 0.48< f3/f < 0.6; wherein f3 is an effective focal length of the third lens, and f is an effective focal length of the optical system. Through the reasonable value of f3/f, spherical aberration can be effectively corrected, and the optical system is ensured to have higher imaging quality.

In one embodiment, the optical system satisfies the conditional expression: 1.63< n3<1.67 and 1.56< n4< 1.64; wherein n3 is a refractive index of the third lens, n4 is a refractive index of the fourth lens, and a reference wavelength of the refractive index is 587.56 nm. By reasonably setting the values of n3 and n4, chromatic aberration can be effectively corrected, and the resolution of the optical system is improved.

In one embodiment, the optical system satisfies the conditional expression G5/CT5> 0.4; wherein G5 is the thickness of the fifth lens at the thinnest position along the optical axis direction, and CT5 is the thickness of the fifth lens on the optical axis. By reasonably setting the value of G5/CT5, the distortion of the optical system can be effectively corrected, meanwhile, the sensitivity of the fifth lens is reduced, and the yield is improved.

In a second aspect, the present invention further provides a lens module, which includes a lens barrel and the 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 chip is disposed at an image side of the optical system and is configured to convert light rays of an object, which pass through the first lens to the sixth lens and are incident on the electronic photosensitive chip, into an electrical signal of an image. Through install this optical system's first lens to sixth lens in the camera lens module, make this application the camera lens module has higher formation of image quality, and the higher pixel's of suitability electron sensitization chip, simultaneously the camera lens module overall length is less, realizes the miniaturization.

In a third aspect, the present invention further provides an electronic device, where the electronic device includes a housing and the lens module of the second aspect, and the lens module is disposed in the housing. The lens module of the second aspect is arranged in the electronic device, so that the electronic device has high imaging quality, the overall length of the electronic device is small, and miniaturization is achieved.

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.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides a lens module, which comprises a lens barrel, an electronic photosensitive chip and an optical system, wherein the first lens to the fifth lens of the optical system are arranged in the lens barrel, and the electronic photosensitive chip is arranged at the image side of the optical system and is used for converting light rays of an object which passes through the first lens to the fifth lens and is incident on the electronic photosensitive chip into an electric signal of an image. The electron sensor chip may be a Complementary Metal Oxide Semiconductor (CMOS). 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. Through installing this optical system's first lens to sixth lens in the lens module for the lens module that this application embodiment provided can possess miniaturized characteristics when guaranteeing high resolution, high imaging quality.

The embodiment of the invention provides electronic equipment, which comprises a shell and a lens module provided by the embodiment of the invention. The lens module and the electronic photosensitive chip 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 set up the lens module of second aspect in electronic equipment for the electronic equipment that this application embodiment provided can possess miniaturized characteristics when guaranteeing high resolution, high imaging quality.

An optical system includes, 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 at a paraxial region; a second lens element with refractive power; the third lens element with negative refractive power has a concave image-side surface at the paraxial region; a fourth lens element with negative refractive power; the fifth lens element with positive refractive power has a convex object-side surface paraxial region and a convex image-side surface paraxial region, and the object-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, and at least one inflection point is arranged on an image-side surface of the sixth lens element; the optical system satisfies the conditional expression: CT1/TTL > 0.2; wherein, CT1 is the thickness of the first lens element on the optical axis, and TTL is the distance from the object-side surface of the first lens element to the image plane of the optical system on the optical axis. The optical system further comprises a diaphragm which can be arranged at any position between the first lens and the sixth lens, such as on the first lens.

By reasonably setting the value of CT1/TTL, the optical system has the characteristics of small head caliber and large depth. The lens barrel is supported by the edge of the image side of the first lens through the thickness of the first lens, so that the space for supporting the lens barrel is saved at the object side end of the first lens, the optical system is further miniaturized, the opening size of the optical system is reduced, the depth of the optical system is increased, and the optical system can be conveniently carried on high-end mobile phones such as a full screen.

By reasonably configuring the surface shapes and the refractive powers of the first lens element to the sixth lens element, the optical system can ensure high resolution and high imaging quality and has the characteristic of miniaturization.

In one embodiment, the optical system satisfies the conditional expression: y1<0.9 mm; where Y1 is the optically effective radius of the object-side surface of the first lens. By reasonably setting the value of Y1, the outer diameter of the object side surface of the first lens is favorably controlled not to be excessively increased, so that the appearance of the small head of the optical system is ensured.

In one embodiment, the optical system satisfies the conditional expression: CT1 is more than or equal to 1.0 mm; wherein, CT1 is the thickness of the first lens on the optical axis. Through the value of reasonable setting CT1, can increase the optical system degree of depth, be favorable to the optical system assembly on high-end models such as comprehensive screen.

In one embodiment, the optical system satisfies the conditional expression: ET1>0.8 mm; ET1 is the edge thickness of the first lens. Through the value of reasonable setting ET1, be favorable to guaranteeing that first lens has sufficient marginal thickness, make the portion of leaning on of first lens move to the direction of imaging surface, and then can make optical system's head realize miniaturizing.

In one embodiment, the optical system satisfies the conditional expression: TTL/ImgH is less than or equal to 1.7; wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system, and ImgH is a half of a diagonal length of an effective imaging area of the optical system on the imaging surface. By reasonably setting the value of TTL/ImgH, the length of the whole optical system can not be excessively increased while the thickness of the first lens is increased.

In one embodiment, the optical system satisfies the conditional expression: -8.1< R51/R52< -2.2; 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. The fifth lens element provides positive refractive power, and has a biconvex shape at the optical axis, so that the fifth lens element can be matched with the first lens element for imaging by reasonably setting the value of R51/R52, and the length of the whole optical system can be further controlled not to be excessively increased.

In one embodiment, the optical system satisfies the conditional expression: 0.58< f1/f < 0.93; where f1 is the effective focal length of the first lens, and f is the effective focal length of the optical system. The first lens provides most positive refractive power, collects light rays for imaging the optical system, and is favorable for controlling the length of the optical system and correcting field curvature to a certain extent by reasonably setting the value of f 1/f.

In one embodiment, the optical system satisfies the conditional expression: 0.48< f3/f < 0.6; where f3 is the effective focal length of the third lens, and f is the effective focal length of the optical system. The third lens provides negative refractive power, and spherical aberration can be effectively corrected by reasonably setting the value of f3/f, so that the optical system is ensured to have higher imaging quality.

In one embodiment, the optical system satisfies the conditional expression: 1.63< n3<1.67 and 1.56< n4< 1.64; wherein n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, and the reference wavelength of the refractive index is 587.56 nm. By reasonably setting the values of n3 and n4, namely reasonably using the lens material with medium and high refractive index, the chromatic aberration can be effectively corrected, and the resolution of the optical system is improved.

In one embodiment, the optical system satisfies the conditional expression G5/CT5> 0.4; wherein G5 is the thickness of the fifth lens at the thinnest point along the optical axis, and CT5 is the thickness of the fifth lens along the optical axis. The object side surface of the fifth lens is provided with a variation trend from convex to concave from the center to the edge, the distortion of the optical system can be corrected by the structure, the variation trend can cause the fifth lens to have the thinnest position, if G5/CT5 is less than 0.4, the thickness ratio of the fifth lens is too large, the forming manufacturability is poor, the sensitivity of the lens is high, the production yield is reduced, the actual mass production is not facilitated, the sensitivity of the fifth lens can be reduced by reasonably configuring the value of G5/CT5, and the yield is improved.

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:

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

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

a third lens element L3 with negative dioptric power, the third lens element L3 having a concave object-side surface S5 at a paraxial region and a concave near-circumferential region, the third lens element L3 having a concave image-side surface S6 at a paraxial region and a concave near-circumferential region;

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

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

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

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 filter L7, and an image forming surface 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 entering the image plane S15 is visible light, and the wavelength of the visible light is 380nm-780 nm. The infrared filter L7 is made of Glass (Glass), and may be coated on the Glass. The imaging surface S15 is an effective pixel area of the electronic photosensitive chip.

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-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 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:

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

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

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

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

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

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

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

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

a second lens element L2 with negative dioptric power, the second lens element L2 having a concave object-side surface S3 at paraxial and peripherical positions, and the second lens element L2 having a concave image-side surface S4 at paraxial and peripherical positions;

a third lens element L3 with negative refractive power having a convex surface at a paraxial region of the object-side surface S5 of the third lens element L3, a concave surface at a paraxial region of the object-side surface S5, and a concave surface at a paraxial region and a near circumferential region of the image-side surface S6 of the third lens element L3;

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

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

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 sixth 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 shows values of CT1/TTL, Y1, CT1, ET1, TTL/ImgH, R51/R52, f1/f, f3/f, n3, n4, and G5/CT5 of the optical systems of the first to seventh embodiments.

TABLE 8

	CT1/TTL	Y1/mm	CT1/mm	ET1mm	TTL/ImgH
						First embodiment	0.203	0.800	1	0.819	1.68
Second embodiment	0.208	0.770	1	0.81	1.64
						Third embodiment	0.209	0.793	1	0.826	1.63
Fourth embodiment	0.261	0.744	1.2	0.991	1.57
						Fifth embodiment	0.281	0.740	1.3	1.0845	1.58
Sixth embodiment	0.277	0.803	1.322	0.998	1.63
						Seventh embodiment	0.261	0.873	1.36	1.1	1.70
	R51/R52	f1/f	f3/f	n3、n4	G5/CT5
						First embodiment	-2.423	0.857	-2.253	1.661、1.626	0.724
Second embodiment	-2.204	0.827	-2.169	1.661、1.623	0.653
						Third embodiment	-2.746	0.923	-1.791	1.661、1.634	0.650
Fourth embodiment	-4.102	0.752	-4.655	1.661、1.564	0.498
						Fifth embodiment	-3.181	0.733	-4.082	1.661、1.568	0.502
Sixth embodiment	-2.153	0.581	-5.044	1.633、1.622	0.462
						Seventh embodiment	-8.078	0.683	-10.377	1.654、1.574	0.508

As can be seen from table 8, each example satisfies: CT1/TTL 0.2, Y1<0.9mm, CT1 is more than or equal to 1.0mm, ET1>0.8mm, TTL/ImgH is less than or equal to 1.7, -8.1< R51/R52< -2.2, 0.58< f1/f <0.93, 0.48< f3/f <0.6, 1.63< n3<1.67, 1.56< n4<1.64 and G5/CT5> 0.4.

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 show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls 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 at a paraxial region;

a second lens element with refractive power;

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

a fourth lens element with negative refractive power;

the fifth lens element with positive refractive power has a convex object-side surface and a convex image-side surface, and the object-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, and at least one inflection point is arranged on an image-side surface of the sixth lens element;

the optical system satisfies the conditional expression:

CT1/TTL>0.2；

wherein CT1 is a thickness of the first lens element on an optical axis, and TTL is a distance from an object-side surface of the first lens element to an image plane of the optical system on the optical axis.

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

Y1<0.9mm；

wherein Y1 is the optical effective radius of the object side surface of the first lens.

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

CT1≥1.0mm；

wherein CT1 is the thickness of the first lens on the optical axis.

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

ET1>0.8mm；

wherein ET1 is the rim thickness of the first lens.

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

TTL/ImgH≤1.7；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system, and ImgH is a half of a diagonal length of an effective imaging area of the optical system on the imaging surface.

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

-8.1<R51/R52<-2.2；

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:

0.58<f1/f<0.93；

wherein f1 is the effective focal length of the first lens, and f is the effective focal length of the optical system.

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

0.48<f3/f<0.6；

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

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

1.63<n3<1.67；

1.56<n4<1.64；

wherein n3 is a refractive index of the third lens, n4 is a refractive index of the fourth lens, and a reference wavelength of the refractive index is 587.56 nm.

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

G5/CT5>0.4；

wherein G5 is the thickness of the fifth lens at the thinnest position along the optical axis direction, and CT5 is the thickness of the fifth lens on the optical axis.

11. A lens module, comprising a barrel, an electronic photosensitive chip and the optical system according to any one of claims 1 to 10, wherein the first to fifth lenses of the optical system are mounted in the barrel, and the electronic photosensitive chip is disposed on an image side of the optical system and is configured to convert light rays of an object incident on the electronic photosensitive chip through the first to fifth 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.