CN113703132B

CN113703132B - Optical system, lens module and electronic equipment

Info

Publication number: CN113703132B
Application number: CN202110976888.2A
Authority: CN
Inventors: 文逸春
Original assignee: Jiangxi Jinghao Optical Co Ltd
Current assignee: Jiangxi Jinghao Optical Co Ltd
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2023-03-10
Anticipated expiration: 2041-08-24
Also published as: CN113703132A

Abstract

An optical system, a lens module and an electronic device, the optical system sequentially comprises from an object side to an image side along an optical axis: the first lens element, the third lens element, the fifth lens element and the sixth lens element have positive refractive power, and the second lens element, the fourth lens element and the seventh lens element have negative refractive power. The object-side surfaces of the first, second, sixth and seventh lenses and the image-side surface of the fourth lens are convex at a paraxial region, and the image-side surfaces of the first, second, sixth and seventh lenses and the object-side surface of the fourth lens are concave at a paraxial region. The optical system satisfies the relation: EFL/TTL is more than 0.8 and less than 0.9; the EFL is an effective focal length of the optical system, and the 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. The optical system has clear shooting images and a small design.

Description

Optical system, lens module and electronic equipment

Technical Field

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

Background

With the development of photographing and shooting technologies, electronic devices such as mobile phones and tablet computers have higher and higher requirements on the shooting definition. At present, in order to meet the clear imaging effect, most of electronic equipment is provided with a camera with higher pixels, and meanwhile, the camera with the higher pixels needs to be provided with a Gao Jiexi force sensor to shoot clear images. However, the sensor with high resolution may have a larger number of lenses and a larger size of an image plane due to the oversized sensor, so that the whole camera may occupy a larger space in the electronic device. Therefore, how to design an image pickup lens that can have high pixels and Gao Jiexi forces while maintaining miniaturization has become one of the important points of interest in the industry.

Disclosure of Invention

The invention aims to provide an optical system, a lens module and an electronic device, which have the characteristics of high image quality and easiness in realizing 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, comprising, in order from an object side to an image side in an optical axis direction: a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a third lens element with positive refractive power having a convex image-side surface at a paraxial region; a fourth lens element with negative refractive power having a concave object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a fifth lens element with positive refractive power; a sixth lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a seventh lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the optical system satisfies the relation: EFL/TTL is more than 0.8 and less than 0.9; wherein, EFL is the effective focal length of the optical system, and TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis.

A first lens element with positive refractive power having a convex object-side surface at an optical axis and a concave image-side surface at the optical axis; the aperture of the first lens is increased, the optical system is ensured to obtain enough light entering quantity, and then the large aperture characteristic is realized; a second lens element with negative refractive power having a convex object-side surface at the optical axis and a concave image-side surface at the optical axis; the aberration generated by the first lens is corrected; a third lens element with positive refractive power having a convex image-side surface at an optical axis; the third lens contributes reasonable focal power to the optical system, and is beneficial to increasing the image plane and shortening the total length of the system; the fourth lens with negative bending force is matched with a meniscus design that the optical axis is concave towards the object side, so that smooth transition of edge light to the rear lens is facilitated, a smaller light deflection angle can be ensured by a reasonable edge inclination angle, the design pressure of a mechanism part is reduced, and stray light is avoided; the fifth lens and the sixth lens with positive bending force jointly contribute to shortening the total length of the optical system, are beneficial to correcting distortion field curvature generated by the front lens group and the rear lens group, promote the balance of integral aberration and improve the imaging quality; the seventh lens with negative focal power is convex on the object side surface at the optical axis and concave on the image side surface at the optical axis, so that the low back of the optical lens can be maintained, the back focus can be ensured while the wide view of the optical lens is realized, the edge illumination of the optical lens is favorably improved, and the dark angle is not easy to appear on the optical lens. Through reasonable configuration of the refractive power, the surface shape and the arrangement and combination sequence of the first lens element to the seventh lens element, the aberration in the optical system can be eliminated, the mutual correction of the aberration among the lens elements can be realized, the resolving power of the optical imaging lens can be improved, the detailed characteristics of a shot object can be well captured, high-quality imaging can be obtained, and the imaging definition can be improved. When the relation is satisfied, the optical system shortens the total optical length while keeping a longer focal length, is beneficial to the miniaturization design of an optical imaging lens and is also beneficial to the clear imaging of a distant scene. When the lower limit of the relation is lower, the total length of the optical system is too long, which is not beneficial to miniaturization design; when the distance is higher than the upper limit of the relational expression, the focal length of the optical system is too long, which is not beneficial for the optical system to receive light rays in a large-angle area, so that the requirement of the optical system on the large-angle characteristic is difficult to meet.

In one embodiment, the optical system satisfies the relationship: 0.7 Tps/YI <1.3; wherein, TTL is a distance from the object-side surface of the first lens element to the image plane on the optical axis, and YI is a half of a height of the maximum field angle of the optical system corresponding to the image. Satisfying the above relation, a miniaturized optical system and a clear imaging effect can be obtained. When the length of the optical system is lower than the lower limit of the relational expression, the length of the optical system becomes very small, the light path becomes very short, a normal optical system cannot be designed, and the performance of the optical system is affected; if the value is higher than the upper limit of the relational expression, the size of the optical system becomes too large to satisfy the design of a miniaturized optical system.

In one embodiment, the optical system satisfies the relationship: 1.6-woven fabric YI/EPD <1.9; wherein YI is half of the maximum field angle of the optical system corresponding to the image height, and EPD is the entrance pupil diameter of the optical system. On one hand, the optical lens has the characteristic of a large image surface, the image quality of the optical lens is improved, the resolution and the imaging definition of the optical lens are improved, the optical lens has a better imaging effect, and the high-definition imaging requirement of people on the optical lens is met. On the other hand, the optical lens has the characteristic of large aperture, has larger light inlet quantity, can improve the dim light shooting condition, can realize the high-definition shooting effect of high image quality, is favorable for being suitable for shooting in dim light environments such as night scenes, rainy days, starry sky and the like, and has better blurring effect. When the image height of the optical system is lower than the lower limit of the relational expression, the image height of the optical system is too small, and the optical system is difficult to match with an image sensor with higher pixels, so that the optical analysis performance of the optical system is reduced; when the value is higher than the upper limit of the relational expression, the diameter of the entrance pupil of the optical system is too small, so that the light entering amount is small, and the shooting in a dark light environment is not facilitated.

In one embodiment, the optical system satisfies the relationship: 7.5641 ≦ (L6R 1/L6R 2) - (L7R 1/L7R 2) ≦ -4.2483; L6R1 is a curvature radius of the object-side surface of the sixth lens element on the optical axis, L6R2 is a curvature radius of the image-side surface of the sixth lens element on the optical axis, L7R1 is a curvature radius of the object-side surface of the seventh lens element on the optical axis, and L7R2 is a curvature radius of the image-side surface of the seventh lens element on the optical axis. The refractive power of the sixth lens element and the refractive power of the seventh lens element are reasonably controlled by satisfying the above relation, so that the seventh lens element can effectively bear the deflection degree of the incident light in the system, and in addition, the astigmatism problem of the off-axis field of view can be improved, and the imaging quality of the optical system is improved. When the surface shape of the object side surface of the seventh lens is too smooth below the lower limit of the relational expression, the aberration is difficult to correct, the astigmatism of an outer field is difficult to suppress, and the imaging quality is influenced; when the height is higher than the upper limit of the relational expression, the object-side surface profile of the seventh lens is excessively curved, which tends to cause poor molding and affect the manufacturing yield.

In one embodiment, the optical system satisfies the relationship: 0.12-woven fabric (sBFL/SD 72) is less than 0.15; the BFL is the minimum distance from the image side surface of the seventh lens to the imaging surface in the optical axis direction; the SD72 is the maximum effective half aperture of the image side surface of the seventh lens, the ratio is controlled within a reasonable range, the back focus can be kept about 0.7mm, good matching performance with a photosensitive chip can be ensured, the maximum effective half aperture of the image side surface of the seventh lens is reasonably controlled, light can be converged towards an imaging surface more reasonably, aberration control and image resolving power improvement are facilitated, and imaging quality is improved. When the light beam deflection angle exceeds the upper limit or is lower than the lower limit, the two parameters are unreasonable in configuration, so that the light beam deflection angle is too large, the light beam convergence effect is poor, the correction of aberration is damaged, and the imaging quality is influenced.

In one embodiment, the optical system satisfies the relationship: 3.5 sRI/YI <4.5; wherein, RI is the ratio of the illumination intensity of different coordinate points of the image plane to the illumination intensity of the central point, and YI is half of the maximum field angle corresponding image height of the optical system. The optical system has the advantages that the relation is satisfied, the brightness ratio of the center and the periphery of the optical system is balanced, namely, the optical system with sufficient light is provided, so that the object with clearer light and shade contrast can be shot, the size of an imaging surface can be ensured, and the size of the whole optical system cannot be lost. When the lower limit of the relation is lower, the periphery of the optical system becomes dark, and the light-dark contrast of an imaged scene becomes small; if the height is higher than the upper limit of the relational expression, the imaging height is too small, and it is difficult to match an image sensor having a higher pixel, and the optical analysis performance of the optical system is lowered.

In one embodiment, the optical system satisfies the relationship 0.21< (L6D 1+ L7D 1)/TTL <0.26; wherein L6D1 is a thickness of the sixth lens element on the optical axis, and L7D1 is a thickness of the seventh lens element on the optical axis. The thickness of the object-side surface of the sixth lens element and the thickness of the image-side surface of the sixth lens element at the optical axis can be in a proper range, so that the size of the optical system can be controlled. If the thickness of the sixth lens element is less than the lower limit of the relational expression, the thickness of the seventh lens element is too small to facilitate the processing and manufacturing of the lens element; if the thickness of the sixth lens element is larger than the upper limit of the relational expression, the thickness of the seventh lens element is too large, which is disadvantageous for the compact design of the optical system.

In one embodiment, the optical system satisfies the relationship: 1.5441 woven-yarn (woven) and woven-yarn (nd) woven-yarn (1.6632) and 19.4 woven-yarn (vd) woven-yarn (56.1); where nd is a refractive index of each lens of the optical system, vd is an abbe number of each lens of the optical system, and a reference wavelength of a curvature and an abbe number is 587.56nm. The first lens, the second lens and the third lens are all plastic lenses, and manufacturing cost of the optical system is reduced.

In a second aspect, the present invention further provides a lens module, which includes the optical system described in any one of the embodiments of the first aspect, and a photosensitive chip disposed on an image side of the optical system. By adding the optical system provided by the invention into the lens module, the lens module has the characteristics of high definition and miniaturization by reasonably designing the surface shape and the refractive power of each lens in the optical system.

In a third aspect, the present invention further provides an electronic device, which includes a housing and the lens module set in the second aspect, wherein the lens module set is disposed in the housing. By adding the lens module provided by the invention into the electronic equipment, the electronic equipment has a high-definition imaging effect and is easy to realize miniaturization and light and thin design.

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 embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1a is a schematic 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 view of the structure 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 view 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.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments of the present invention, belong to the protection scope of the present invention.

The invention provides an optical system, comprising in order from an object side to an image side along an optical axis: the first lens element with positive refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the second lens element with negative refractive power has a convex object-side surface and a concave image-side surface; a third lens element with positive refractive power having a convex image-side surface at paraxial region; a fourth lens element with negative refractive power having a concave object-side surface at paraxial region and a concave image-side surface at paraxial region; a fifth lens element with positive refractive power; a sixth lens element with positive refractive power having a convex object-side surface and a concave image-side surface; a seventh lens element with negative refractive power having a convex object-side surface and a concave image-side surface; the optical system satisfies the relation: EFL/TTL is more than 0.8 and less than 0.9; the EFL is an effective focal length of the optical system, and the TTL is a distance from an object side surface of the first lens element to an imaging surface of the optical system on an optical axis.

A first lens element with positive refractive power having a convex object-side surface at an optical axis and a concave image-side surface at the optical axis; the aperture of the first lens is increased, and the optical system is ensured to obtain enough light incoming quantity, so that the characteristic of a large aperture is realized; a second lens element with negative refractive power having a convex object-side surface at the optical axis and a concave image-side surface at the optical axis; the aberration generated by the first lens is corrected; a third lens element with positive refractive power having a convex image-side surface at an optical axis; the third lens contributes reasonable focal power to the optical system, and is beneficial to increasing the image plane and shortening the total length of the system; the fourth lens with negative bending force is matched with a meniscus design that the optical axis is concave towards the object side, so that smooth transition of edge light to the rear lens is facilitated, a smaller light deflection angle can be ensured by a reasonable edge inclination angle, the design pressure of a mechanism part is reduced, and stray light is avoided; the fifth lens and the sixth lens with positive bending force jointly contribute to shortening the total length of the optical system, are beneficial to correcting distortion field curvature generated by the front lens group and the rear lens group, promote the balance of integral aberration and improve the imaging quality; the seventh lens with negative focal power is convex on the object side surface at the optical axis and concave on the image side surface at the optical axis, so that the low back of the optical lens can be maintained, the back focus can be ensured while the wide view of the optical lens is realized, the edge illumination of the optical lens is favorably improved, and the dark angle is not easy to appear on the optical lens. Through reasonable configuration of the refractive power, the surface shape and the arrangement and combination sequence of the first lens element to the seventh lens element, the aberration in the optical system can be eliminated, the mutual correction of the aberration between the lens elements can be realized, the resolving power of the optical imaging lens can be improved, the detailed characteristics of a shot object can be well captured, high-quality imaging can be obtained, and the imaging definition can be improved. When the relation is satisfied, the optical system shortens the optical total length while keeping a longer focal length, is beneficial to the miniaturization design of the optical imaging lens and is also beneficial to the clear imaging of a distant scene. When the lower limit of the relational expression is lower, the total length of the optical system is too long, which is not beneficial to miniaturization design; when the distance is higher than the upper limit of the relational expression, the focal length of the optical system is too long, which is not beneficial to the optical system to receive the light rays in a large-angle area, so that the requirement of the optical system on the large-angle characteristic is difficult to meet.

In one embodiment, the optical system satisfies the relationship: 0.7-plus TTL/YI <1.3; wherein, TTL is the distance from the object side surface of the first lens to the image plane on the optical axis, and YI is half of the maximum field angle of the optical system corresponding to the image height. Satisfying the above relation, a miniaturized optical system and a clear imaging effect can be obtained. When the length of the optical system is lower than the lower limit of the relational expression, the length of the optical system becomes very small, the light path becomes very short, a normal optical system cannot be designed, and the performance of the optical system is affected; if the value is higher than the upper limit of the relational expression, the size of the optical system becomes too large to satisfy the design of a miniaturized optical system.

In one embodiment, the optical system satisfies the relationship: 1.6-woven fabric YI/EPD <1.9; where YI is half of the maximum field angle of the optical system corresponding to the height of the image, and EPD is the entrance pupil diameter of the optical system. On one hand, the optical lens has the characteristic of a large image surface, the image quality of the optical lens is improved, the resolution and the imaging definition of the optical lens are improved, the optical lens has a better imaging effect, and the high-definition imaging requirement of people on the optical lens is met. On the other hand, the optical lens has the characteristic of large aperture, has larger light inlet quantity, can improve the dim light shooting condition, thereby realizing the high-image-quality and high-definition shooting effect, being beneficial to being suitable for shooting in dim light environments such as night scenes, rainy days, starry sky and the like, and having better blurring effect. When the image height of the optical system is lower than the lower limit of the relational expression, the image height of the optical system is too small, and the image sensor with higher pixels is difficult to match, so that the optical analysis performance of the optical system is reduced; if the value is higher than the upper limit of the relational expression, the diameter of the entrance pupil of the optical system is too small, so that the light beam entering amount is small, which is not favorable for shooting in a dark light environment.

In one embodiment, the optical system satisfies the relationship: 7.5641 ≦ (L6R 1/L6R 2) - (L7R 1/L7R2 ≦ -4.2483; L6R1 is a radius of curvature of the object-side surface of the sixth lens element at the optical axis, L6R2 is a radius of curvature of the image-side surface of the sixth lens element at the optical axis, L7R1 is a radius of curvature of the object-side surface of the seventh lens element at the optical axis, and L7R2 is a radius of curvature of the image-side surface of the seventh lens element at the optical axis. The refractive power of the sixth lens element and the refractive power of the seventh lens element are reasonably controlled by satisfying the above relation, so that the seventh lens element can effectively bear the deflection degree of the incident light in the system, and in addition, the astigmatism problem of the off-axis field of view can be improved, and the imaging quality of the optical system is improved. When the surface shape of the object side surface of the seventh lens is too smooth below the lower limit of the relational expression, the aberration is difficult to correct, astigmatism of an outer field of view is difficult to inhibit, and imaging quality is influenced; if the upper limit of the relation is higher, the object-side surface profile of the seventh lens element is excessively curved, which tends to cause poor molding and adversely affect the production yield.

In one embodiment, the optical system satisfies the relationship: 0.12 and yarn of Tsunless BFL/SD72<0.15; the BFL is the minimum distance from the image side surface of the seventh lens to the imaging surface in the optical axis direction; SD72 is the most effective half bore of seventh lens image side face, through with above-mentioned ratio control in reasonable range, can make the back burnt keep about 0.7mm, can ensure to have good matching nature with the sensitization chip, the most effective half bore of the image side face of reasonable control seventh lens also is favorable to more reasonable the converging to the image plane of light, helps controlling the aberration and promotes the resolving power, improves the imaging quality. When the light beam deflection angle exceeds the upper limit or is lower than the lower limit, the two parameters are unreasonably configured, so that the light beam deflection angle is too large, the light beam convergence effect is poor, the correction of aberration is damaged, and the imaging quality is influenced.

In one embodiment, the optical system satisfies the relationship: 3.5 sRI/YI <4.5; wherein, RI is the ratio of the illumination of different coordinate points of the image plane to the illumination of the central point, and YI is half of the maximum field angle of the optical system corresponding to the image. Satisfying above-mentioned relational expression, optical system center and peripheral light ratio gain balance, have an optical system that light is sufficient promptly, are favorable to shooing the more clear scenery of light and shade contrast, are favorable to guaranteeing the size of image plane again, can not make whole optical system's size have the disappearance. When the lower limit of the relation is lower, the periphery of the optical system becomes dark, and the light-dark contrast of an imaged scene becomes small; if the height is higher than the upper limit of the relational expression, the imaging height is too small, and it is difficult to match an image sensor having a higher pixel, and the optical analysis performance of the optical system is lowered.

In one embodiment, the optical system satisfies the relationship 0.21< (L6D 1+ L7D 1)/TTL <0.26; wherein L6D1 is a thickness of the sixth lens element on the optical axis, and L7D1 is a thickness of the seventh lens element on the optical axis. The thickness of the object-side surface of the sixth lens element and the thickness of the image-side surface of the sixth lens element at the optical axis can be in a proper range, so that the size of the optical system can be controlled. When the thickness of the sixth lens element is less than the lower limit of the relational expression, the thickness of the seventh lens element is too small to facilitate the processing and manufacturing of the lens elements; if the thickness is higher than the upper limit of the relational expression, the thickness of the sixth lens and the seventh lens is too large, which is disadvantageous for the compact design of the optical system.

In one embodiment, the optical system satisfies the relationship: 1.5441 woven-yarn (woven) and woven-yarn (nd) woven-yarn (1.6632) and 19.4 woven-yarn (vd) woven-yarn (56.1); where nd is a refractive index of each lens of the optical system, vd is an abbe number of each lens of the optical system, and a reference wavelength of the curvature and the abbe number is 587.56nm. The first lens, the second lens and the third lens are all plastic lenses, and the manufacturing cost of the optical system is reduced.

The invention also provides a lens module, which comprises the optical system and the photosensitive chip, wherein the photosensitive chip is arranged in the imaging surface. In addition, the lens module further comprises a fixer, a sensor and a color filter. By adding the optical system provided by the invention into the lens module, the lens module has the characteristics of high definition and miniaturization by reasonably designing the surface shape and the refractive power of each lens in the optical system.

The invention also provides electronic equipment which comprises a shell and the lens module in the second aspect, wherein the lens module is arranged in the shell. In addition, the electronic equipment comprises a mobile phone, a tablet computer, a notebook computer, an intelligent watch and a vehicle-mounted camera. By adding the lens module provided by the invention into the electronic equipment, the electronic equipment has a higher screen occupation ratio while having a better and clearer imaging effect.

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

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

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

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

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

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

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

Further, the optical system includes a stop STO, an infrared cut filter IR, and an imaging surface IMG. In this embodiment, the stop STO is provided on the object side of the optical system for controlling the amount of light entering. The infrared cut filter IR is disposed between the seventh lens element L7 and the imaging plane IMG, and includes an object side surface S15 and an image side surface S16, and the infrared cut filter IR is configured to filter out infrared light, so that the light incident on the imaging plane IMG is visible light with a wavelength of 380nm to 780nm. The material of the infrared cut filter IR is GLASS (GLASS), and the GLASS can be coated with a film. The first lens L1 to the seventh lens L7 may be made of plastic, glass, or a glass-plastic composite material. The effective pixel area of the photosensitive element is located on the imaging plane IMG.

Table 1a shows a table of characteristics of the optical system of the present embodiment, in which the reference wavelength of the lens focal length is 555nm, the reference wavelength of the refractive index and abbe number of the lens is 587.56nm, and the Y radius in table 1a is the radius of curvature of the object-side surface or the image-side surface of the corresponding surface number at the optical axis. The surface number S1 and the surface number S2 are the object-side surface S1 and the image-side surface S2 of the first lens L1, respectively, that is, in the same lens, the surface with the smaller surface number is the object-side surface, and the surface with the larger surface number is the image-side surface. The first value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110. The units of Y radius, thickness and effective focal length are millimeters (mm).

TABLE 1a

Wherein EFL is the effective focal length of the optical system, FNO is the f-number of the optical system, and FOV is the maximum field angle of the optical system.

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

wherein x is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, h is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric surface vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th high-order term in the aspheric surface type formula. Table 1b shows the high-order coefficient values A4, A6, A8, a10, a12, a14, a16, and a18 that can be used for the aspherical mirrors S1 and S2 in the first embodiment.

TABLE 1b

Fig. 1b (a) shows a longitudinal spherical aberration curve of the optical system of the first embodiment at wavelengths of 650nm, 610nm, 555nm, 510nm and 470nm, wherein the abscissa along the X-axis direction represents the focus shift, the ordinate along the Y-axis direction represents the normalized field of view, and the longitudinal spherical aberration curve represents the convergent focus deviation of light rays of different wavelengths after passing through the respective lenses of the optical system. As can be seen from fig. 1b (a), the spherical aberration value of the optical system in the first embodiment is better, which illustrates that the imaging quality of the optical system in this embodiment is better.

Fig. 1b (b) also shows a graph of astigmatism of the optical system of the first embodiment at a wavelength of 555nm, in which the abscissa in the X-axis direction represents the focus offset and the ordinate in the Y-axis direction represents the image height in mm. The astigmatism curves represent the meridional imaging plane curvature T and the sagittal imaging plane curvature S. As can be seen from fig. 1b (b), astigmatism of the optical system is well compensated.

Fig. 1b (c) also shows a distortion curve of the optical system of the first embodiment at a wavelength of 555 nm. The abscissa along the X-axis direction represents the focus offset, the ordinate along the Y-axis direction represents the image height, and the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 1b (c), the distortion of the optical system is well corrected at a wavelength of 555 nm.

As can be seen from (a), (b) and (c) in fig. 1b, the optical system of the present embodiment has small aberration, good imaging quality and good imaging quality.

Second embodiment

Referring to fig. 2a and fig. 2b, the optical system of the present embodiment, 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 the reference wavelength of the focal length of the lens is 555nm, the reference wavelengths of the refractive index and the abbe number of the lens are 587.56nm, and the Y radius in table 2a is the radius of curvature of the object-side surface or the image-side surface of the corresponding surface number at the optical axis. The surface number S1 and the surface number S2 are an object side surface S1 and an image side surface S2 of the first lens L1, respectively, that is, in the same lens, a surface with a smaller surface number is an object side surface, and a surface with a larger surface number is an image side surface. The first value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110. The units of the radius Y, the thickness and the effective focal length are millimeters (mm), and the meaning of each parameter is the same as that of the first embodiment.

TABLE 2a

Table 2b gives the coefficients of high order terms that can be used for each aspherical mirror in the second embodiment, wherein each aspherical mirror type can be defined by the formula given in the first embodiment.

TABLE 2b

FIG. 2b shows a longitudinal spherical aberration 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 the aberration diagram in fig. 2b, the longitudinal spherical aberration, the curvature of field and the distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 3a and 3b, 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 third embodiment are the same as those of the first embodiment, and reference may be made thereto.

Table 3a shows a table of characteristics of the optical system of the present embodiment, in which the reference wavelength of the lens focal length is 555nm, the reference wavelength of the refractive index and abbe number of the lens is 587.56nm, and the Y radius in table 3a is the radius of curvature of the object-side surface or the image-side surface at the optical axis of the corresponding surface number. The surface number S1 and the surface number S2 are an object side surface S1 and an image side surface S2 of the first lens L1, respectively, that is, in the same lens, a surface with a smaller surface number is an object side surface, and a surface with a larger surface number is an image side surface. The first value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110. The units of the radius Y, the thickness and the effective focal length are all millimeters (mm), and the other parameters have the same meanings as those of the first embodiment.

TABLE 3a

Table 3b gives the coefficients of high-order terms that can be used for each aspherical mirror surface in the third embodiment, wherein each aspherical mirror surface type can be defined by the formula given in the first embodiment.

TABLE 3b

FIG. 3b shows a longitudinal spherical aberration 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 bending and sagittal imaging plane bending; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from the aberration diagram in fig. 3b, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Fourth embodiment

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

The fifth lens element L5 with positive refractive power has a convex object-side surface S9 and a concave image-side surface S10.

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

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

Table 4a shows a table of characteristics of the optical system of the present embodiment, in which the reference wavelength of the lens focal length is 555nm, the reference wavelength of the refractive index and abbe number of the lens is 587.56nm, and the Y radius in table 4a is the radius of curvature of the object-side surface or the image-side surface at the optical axis of the corresponding surface number. The surface number S1 and the surface number S2 are an object side surface S1 and an image side surface S2 of the first lens L1, respectively, that is, in the same lens, a surface with a smaller surface number is an object side surface, and a surface with a larger surface number is an image side surface. The first value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110. The units of the radius Y, the thickness and the effective focal length are millimeters (mm), and the other parameters have the same meanings as those of the first embodiment.

TABLE 4a

Table 4b gives the coefficients of high-order terms that can be used for each aspherical mirror surface in the fourth embodiment, wherein each aspherical mirror surface type can be defined by the formula given in the first embodiment.

TABLE 4b

FIG. 4b shows a longitudinal spherical aberration 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 the aberration diagram in fig. 4b, the longitudinal spherical aberration, the curvature of field and the distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

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 convex object-side surface S5 at a paraxial region and a convex image-side surface S6 at a paraxial region of the third lens element L3.

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

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

Table 5a shows a table of characteristics of the optical system of the present embodiment, in which the reference wavelength of the lens focal length is 555nm, the reference wavelength of the refractive index and abbe number of the lens is 587.56nm, and the Y radius in table 5a is the radius of curvature of the object-side surface or the image-side surface at the optical axis of the corresponding surface number. The surface number S1 and the surface number S2 are the object-side surface S1 and the image-side surface S2 of the first lens L1, respectively, that is, in the same lens, the surface with the smaller surface number is the object-side surface, and the surface with the larger surface number is the image-side surface. The first value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110. The units of the radius Y, the thickness and the effective focal length are all millimeters (mm), wherein the other parameters have the same meanings as those of the first embodiment.

TABLE 5a

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

TABLE 5b

FIG. 5b shows a longitudinal spherical aberration 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 the aberration diagram in fig. 5b, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality.

Tables 6a and 6b show values of FL/TTL, TTL/YI, YI/EPD, (L6R 1/L6R 2) - (L7R 1/L7R 2), TTL × Ratio, RI/YI, (L6D 1+ L7D 1)/TTL, nd, vd in the optical systems of the first to fifth embodiments.

TABLE 6a

TABLE 6b

As can be seen from tables 6a and 6b, the optical systems of the first to fifth embodiments all satisfy the following relations: 0.8 yarn-dyed FL/TTL <0.9, 0.7 yarn-dyed TTL/YI <1.3, 1.6 yarn-dyed YI/EPD <1.9, -7.5641 ≦ (L6R 1/L6R 2) - (L7R 1/L7R 2) ≦ 4.2483, 0.12 yarn-dyed BFL/SD72<0.15, 3.5 yarn-dyed RI/YI <4.5, 0.21 yarn-dyed (L6D 1+ L7D 1)/TTL <0.26, 1.5441 yarn-dyed yarn-1.6632, 19.4 yarn-dyed yarn-56.1.

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

Claims

1. An optical system, comprising seven lens elements with refractive power, sequentially arranged along an optical axis from an object side to an image side, comprising:

a first lens element with positive refractive power having a convex object-side surface near an optical axis; the image side surface is a concave surface near the optical axis;

a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

a third lens element with positive refractive power having a convex image-side surface near the optical axis;

a fourth lens element with negative refractive power having a concave object-side surface near an optical axis and a concave image-side surface near the optical axis;

a fifth lens element with positive refractive power;

a sixth lens element with positive refractive power having a convex object-side surface near an optical axis and a concave image-side surface near the optical axis;

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

the optical system satisfies the relation: EFL/TTL is more than 0.8 and less than 0.9;

-7.5641≤(L6R1/L6R2)-(L7R1/L7R2)≤-4.2483；

wherein, EFL is the effective focal length of the optical system, TTL is the distance between the object side surface of the first lens and the imaging surface of the optical system on the optical axis; L6R1 is a curvature radius of the object-side surface of the sixth lens element on the optical axis, L6R2 is a curvature radius of the image-side surface of the sixth lens element on the optical axis, L7R1 is a curvature radius of the object-side surface of the seventh lens element on the optical axis, and L7R2 is a curvature radius of the image-side surface of the seventh lens element on the optical axis.

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

0.7<TTL/YI<1.3；

wherein YI is half of the maximum field angle corresponding image height of the optical system.

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

1.6<YI/EPD<1.9；

wherein YI is half of the maximum field angle of the optical system corresponding to the image height, and EPD is the entrance pupil diameter of the optical system.

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

0.12<BFL/SD72<0.15；

the BFL is a minimum distance from an image side surface of the seventh lens to an image plane in an optical axis direction, and the SD72 is a maximum effective half aperture of the image side surface of the seventh lens.

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

3.5<RI/YI<4.5；

wherein, RI is the ratio of the illumination intensity of different coordinate points of the image plane to the illumination intensity of the central point, and YI is half of the maximum field angle corresponding image height of the optical system.

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

0.21<(L6D1+L7D1)/TTL<0.26；

wherein L6D1 is a thickness of the sixth lens element on the optical axis, and L7D1 is a thickness of the seventh lens element on the optical axis.

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

1.5441<nd<1.6632，

19.4<vd<56.1；

where nd is a refractive index of any of the first lens to the seventh lens in the optical system, vd is an abbe number of any of the first lens to the seventh lens in the optical system, and a reference wavelength of a refractive index and an abbe number is 587.56nm.

8. A lens module comprising the optical system as claimed in any one of claims 1 to 7 and a photo-sensor chip, said photo-sensor chip being disposed on the image side of the optical system.

9. An electronic apparatus, characterized in that the electronic apparatus comprises a housing and the lens module according to claim 8, the lens module being disposed in the housing.