CN112596200A

CN112596200A - Optical system, image capturing device and electronic device

Info

Publication number: CN112596200A
Application number: CN202011402093.2A
Authority: CN
Inventors: 谭怡翔; 李明; 赵利军
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2021-04-02

Abstract

The application provides an optical system, an image capturing device and an electronic device. The optical system comprises, in order from an object side to an image side along an optical axis: a first lens element with positive refractive power having a convex object-side surface at 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 refractive power; a fourth lens element with refractive power having a convex image-side surface at paraxial region; a fifth lens element with negative refractive power; a sixth lens element with positive refractive power having a convex image-side surface at paraxial region; the seventh lens element with negative refractive power has a concave object-side surface at a paraxial region and a concave image-side surface at a paraxial region, and both the object-side surface and the image-side surface of the seventh lens element are aspheric. The optical system can achieve a balance among a large image plane, a high resolution, and a small size when satisfying a specific relationship.

Description

Optical system, image capturing device and electronic device

Technical Field

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

Background

Currently, a high-pixel image capturing function has become the standard of current portable devices, and a photosensitive chip with up to one hundred million pixels has appeared, thereby providing a possibility of capturing a picture with ultra-high image quality. The photosensitive chip has the characteristics of large diagonal length, smaller pixel size and more pixels.

However, the image plane of the conventional optical lens is small, and the resolving power is not very outstanding, so that the adaptation requirement of the photosensitive chip is difficult to meet.

Disclosure of Invention

Therefore, it is necessary to provide an improved optical system for solving the problems of small image plane, low resolving power and difficulty in adapting to the ultra-high pixel photosensitive chip of the conventional optical lens.

An optical system comprising, in order from an object side to an image side along an optical axis:

a first lens element with positive refractive power having a convex object-side surface at 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 refractive power;

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

a fifth lens element with negative refractive power;

a sixth lens element with positive refractive power having a convex image-side surface at paraxial region; and the number of the first and second groups,

the seventh lens element with negative refractive power has a concave object-side surface at a paraxial region and a concave image-side surface at a paraxial region, wherein both the object-side surface and the image-side surface of the seventh lens element are aspheric, and at least one of the object-side surface and the image-side surface of the seventh lens element has at least one inflection point;

the optical system satisfies the following relation:

0.26＜(CT1+CT2+CT3+CT4)/TTL＜0.29；

wherein CT1 denotes a thickness of the first lens on an optical axis, CT2 denotes a thickness of the second lens on the optical axis, CT3 denotes a thickness of the third lens on the optical axis, CT4 denotes a thickness of the fourth lens on the optical axis, and TTL denotes a distance on the optical axis from an object-side surface of the first lens to an image plane of the optical system.

According to the optical system, the appropriate number of lenses are selected, the refractive power and the surface type of each lens are reasonably distributed, so that a larger image surface can be obtained, the imaging analysis capability of the lens can be enhanced, the aberration can be effectively corrected, and the imaging quality of an image is ensured; in addition, when the relation is met, the thickness of the front lens group can be reasonably set, so that the forming and the assembling of the lenses are facilitated, the manufacturing difficulty of the lens is reduced, meanwhile, the reasonable distribution of the space between the lenses is facilitated, the lens structure of the optical system is more compact, and the miniaturization of the system is realized.

In one embodiment, the d-ray abbe numbers of at least three lenses in the optical system are lower than 30.

When the relation is met, the light collection capacity of the system can be enhanced by arranging the high-refractive-index (namely low-Abbe number) lens, so that light can be converged into the system and focused to an imaging surface, the visual angle and the image surface brightness of the system are ensured, and meanwhile, the chromatic dispersion of the system is favorably reduced by arranging the low-refractive-index (namely high-Abbe number) lens, so that chromatic aberration is reduced, and the imaging quality of an image is improved.

In one embodiment, the optical system satisfies the following relationship: ImgH is more than or equal to 6.34 mm; wherein ImgH represents half of the image height corresponding to the maximum field angle of the optical system.

When the above relation is satisfied, a large-size image plane can be realized, so that the optical system can be ensured to be matched with a chip with an ultra-large photosensitive area, the high-pixel imaging effect of the lens is ensured, the photosensitive area corresponding to a single pixel point can be increased, the adaptation requirement of larger luminous flux is satisfied, and the imaging quality under weak illumination is improved.

In one embodiment, the optical system satisfies the following relationship: f/EPD is less than or equal to 1.85; where f represents the effective focal length of the optical system and EPD represents the entrance pupil diameter of the optical system.

When the relation is met, the effective focal length and the entrance pupil diameter of the optical system can be reasonably configured, and the system can be ensured to have enough light entering amount by the front diaphragm, so that the shooting effect of the system in a dark light environment is improved; in addition, the size of the Airy spots is reduced due to the increase of the aperture, so that the high resolution limit is achieved, and the design requirement of the ultrahigh pixel optical system is met.

In one embodiment, the optical system satisfies the following relationship: TTL/ImgH is less than or equal to 1.404; wherein ImgH represents half of the image height corresponding to the maximum field angle of the optical system.

The size of the photosensitive chip is determined by ImgH, and the larger ImgH is, the larger the size of the photosensitive chip which can be supported by the optical system is, so that when the above relation is met, the ImgH can be reasonably increased, the system can be conveniently adapted to the photosensitive chip with high pixels, and simultaneously, the appropriate reduction of TTL is facilitated, the length of the whole optical system is compressed, and the system structure is kept compact.

In one embodiment, the optical system satisfies the following relationship: TTL/f is more than 1.2 and less than 1.3; wherein f represents an effective focal length of the optical system.

When the above relation is satisfied, the total length and the effective focal length of the optical system can be reasonably configured, thereby being beneficial to realizing miniaturization of the optical system on the premise of obtaining the long-focus characteristic.

In one embodiment, the optical system satisfies the following relationship: the | f/f4| is less than or equal to 1.2; where f denotes an effective focal length of the optical system, and f4 denotes an effective focal length of the fourth lens.

When the above relationship is satisfied, the effective focal length of the optical system and the effective focal length of the fourth lens element can be reasonably configured, so that the fourth lens element can provide appropriate positive refractive power or negative refractive power, and the overall refractive power of the system can be adjusted to form a quasi-symmetric structure with the front first lens element, the front second lens element and the front third lens element, thereby balancing the distortion generated by the front lens element and avoiding high-order aberration caused by excessively large refractive index.

In one embodiment, the optical system satisfies the following relationship: 0.2 < | f6/RS11| < 0.9; where f6 denotes an effective focal length of the sixth lens, and RS11 denotes a radius of curvature of an object side surface of the sixth lens at an optical axis.

When the relation is satisfied, the effective focal length of the sixth lens and the curvature radius of the object side surface of the sixth lens at the optical axis are favorably and reasonably configured, so that the aberration generated by the front lens group can be effectively improved, and the resolving power of the optical system is improved.

In one embodiment, the optical system satisfies the following relationship: 1.6 < SigmaCT/Sigma AT < 2.2; wherein Σ CT represents the sum of thicknesses of respective lenses in the optical system on the optical axis, and Σ AT represents the sum of air spaces of respective adjacent lenses in the optical system on the optical axis.

When the relation is satisfied, the proportion of sigma CT and sigma AT in the optical system can be reasonably set, thereby realizing smooth transition of light on each mirror surface in the transmission process and being beneficial to improving the imaging quality of the optical system.

In one embodiment, the optical system satisfies the following relationship: BF/TTL is more than 0.07 and less than 0.12; wherein BF represents a minimum distance in an optical axis direction from an image side surface of the seventh lens to an imaging surface of the optical system.

When satisfying above-mentioned relation, be favorable to rationally setting up optical system's optics back focal and total length of system to be favorable to the equipment of lens module, also be favorable to reducing the marginal area's on the imaging surface chief ray incident angle simultaneously, improve the relative illuminance on image plane, and then promote the imaging quality.

In one embodiment, the optical system satisfies the following relationship:

0.35 < | SAG72|/RS14 < 0.65; wherein SAG72 represents a distance in an optical axis direction from an intersection point of an image side surface of the seventh lens and an optical axis to a maximum effective aperture of the image side surface of the seventh lens, and RS14 represents a curvature radius of an image side surface of the seventh lens at the optical axis.

When the relation is met, the rise of the image side surface of the seventh lens and the curvature radius of the image side surface of the seventh lens at the optical axis can be reasonably configured, so that the structural complexity of the lenses is favorably reduced, the production yield is improved, and the high-order aberration of a system is favorably reduced.

The application also provides an image capturing device.

An image capturing device includes the optical system and a photosensitive element, wherein the photosensitive element is disposed on an image side of the optical system.

Above-mentioned get for instance the device, utilize aforementioned optical system can adapt super large photosensitive area's photosensitive element to shoot and obtain bright and the high image of pixel, get for instance the device simultaneously and still have miniaturized structural feature, make things convenient for the adaptation to like the limited device of size such as cell-phone, flat board, satisfy the market demand better.

The application also provides an electronic device, which comprises a shell and the image capturing device, wherein the image capturing device is arranged on the shell.

Above-mentioned electronic device has lightweight characteristics, and utilizes aforementioned view for instance device can realize the scenery of superelevation pixel and take a photograph the effect, is favorable to promoting user's shooting experience.

Drawings

Fig. 1 shows a schematic structural view of an optical system of embodiment 1 of the present application;

fig. 2 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 1;

fig. 3 is a schematic structural view showing an optical system of embodiment 2 of the present application;

fig. 4 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 2;

fig. 5 is a schematic structural view showing an optical system of embodiment 3 of the present application;

fig. 6 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 3;

fig. 7 is a schematic structural view showing an optical system of embodiment 4 of the present application;

fig. 8 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 4;

fig. 9 is a schematic structural view showing an optical system of embodiment 5 of the present application;

fig. 10 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 5;

fig. 11 is a schematic view of an image capturing apparatus according to an embodiment of the present application;

fig. 12 is a schematic diagram of an electronic device using an image capturing device according to an embodiment of the present application.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "left," "right," "upper," "lower," "front," "rear," "circumferential," and the like are based on the orientation or positional relationship shown in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the present description, the expressions first, second, third and the like are used only for distinguishing one feature from another feature, and do not indicate any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present application. For ease of illustration, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

In this specification, a space on a side of the optical element where the object is located is referred to as an object side of the optical element, and correspondingly, a space on a side of the optical element where the object is located is referred to as an image side of the optical element. The surface of each lens closest to the object is called the object side surface, and the surface of each lens closest to the image plane is called the image side surface. And defines the positive direction with distance from the object side to the image side.

In addition, in the following description, if it appears that a lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least near the optical axis; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least near the optical axis. Here, the paraxial region means a region near the optical axis. Specifically, the irregularity of the lens surface region is determined on the image side or the object side by the intersection point of the light ray passing through the region in parallel with the optical axis. For example, when the parallel light passes through the region, the light is focused toward the image side and the intersection point of the light and the optical axis is located at the image side, then the region is a convex surface; on the contrary, if the light ray passes through the region, the light ray is diverged, and the intersection point of the extension line of the light ray and the optical axis is at the object side, the region is a concave surface. In addition, the lens includes an optical axis vicinity region, a circumference vicinity region, and an extension portion for fixing the lens. Ideally, the imaging light does not pass through the extension portion, and therefore the range of the region from the region near the optical axis to the region near the circumference can be defined as the effective aperture range of the lens. The following embodiments omit portions of the extensions for clarity of the drawings. Further, the method of determining the range of the optical axis vicinity region, the circumference vicinity region, or the plurality of regions is as follows:

first, a central point is defined as an intersection point of the lens surface and the optical axis, the distance from the central point to the boundary of the effective aperture range of the lens is the effective semi-aperture of the lens, and a point of inflection is a point on the lens surface which is not on the optical axis, and a tangent line passing through the point of inflection is perpendicular to the optical axis (i.e. the surface types of both sides of the point of inflection on the lens surface are opposite). If there are several points of inflection from the central point outward in the radial direction of the lens, it is the first point of inflection and the second point of inflection in sequence, and the point of inflection farthest from the central point in the effective aperture range of the lens is the Nth point of inflection. Defining the range between the central point and the first inflection point as an area near the optical axis, defining an area radially outward of the Nth inflection point as an area near the circumference, and dividing the area between the first inflection point and the Nth inflection point into different areas according to the inflection points; if there is no inflection point on the lens surface, the region near the optical axis is defined as a region corresponding to 0 to 50% of the effective half-aperture, and the region near the circumference is defined as a region corresponding to 50 to 100% of the effective half-aperture.

The features, principles and other aspects of the present application are described in detail below.

Referring to fig. 1, 3, 5, 7 and 9, the present application provides an optical system with a large image plane and high resolution. The optical system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens, wherein the seven lenses are arranged in sequence from the first lens to the seventh lens along an optical axis from an object side to an image side, and an imaging surface of the optical system is positioned at the image side of the seventh lens. In detail, the seven lenses are not jointed, that is, any two adjacent lenses have a space therebetween. Since the process of the cemented lens is more complicated than that of the non-cemented lens, especially the cemented surface of the two lenses needs to have a curved surface (such as an aspheric surface) with high accuracy so as to achieve high degree of conformity when the two lenses are cemented, and poor conformity due to misalignment may also occur during the cementing process, which affects the overall optical imaging quality. Therefore, the seven lenses in the optical system of the invention are non-cemented lenses, which can effectively improve the problems generated by cemented lenses.

Specifically, the first lens element with positive refractive power is beneficial to converging light rays into the system and focusing the light rays to an image plane, and is also beneficial to shortening the total length of the system and realizing the miniaturization of the system. Furthermore, the object-side surface of the first lens element is convex at a paraxial region thereof, which is helpful for enhancing the positive refractive power provided by the first lens element.

The second lens element with negative refractive power can correct spherical aberration generated by the first lens element, and can further enlarge the field of view of the optical system. Furthermore, the object-side surface of the second lens element is convex at a paraxial region and the image-side surface is concave at a paraxial region, which helps prevent over-correction of spherical aberration and chromatic aberration of the first lens element.

The third lens element with refractive power can help the first lens element to share part of the positive refractive power when the third lens element with refractive power has positive refractive power, thereby preventing the first lens element from being excessively bent, enabling the adjacent lens surface types to be more matched, and further shortening the total length of the system.

The fourth lens element with refractive power can effectively balance the refractive power of the front lens group, thereby improving the distortion of the front first lens element, the second lens element and the third lens element, and reducing the high-order aberration caused by the over-large refractive index of the lens elements. Furthermore, the image side surface of the fourth lens element is convex at the paraxial region, which is beneficial to focusing light, thereby shortening the total length of the system and ensuring miniaturization of the system.

The fifth lens element with negative refractive power can expand the light emitted from the front lens element, and the proper negative refractive power can facilitate smooth transition of the light, thereby further improving the imaging quality.

The sixth lens element with positive refractive power can effectively improve aberration generated by the front lens element and enhance resolution of the optical system, and the image-side surface of the sixth lens element is convex at a paraxial region thereof, thereby enhancing the positive refractive power provided by the sixth lens element and better correcting chromatic aberration generated by the front lens element.

The seventh lens has negative refractive power, which is beneficial to correcting system aberration and adjusting optical back focus of the system, thereby providing enough matching space for the photosensitive chip, facilitating the assembly and adjustment of the photosensitive chip, better realizing the incident angle matching of the chief ray on the photosensitive chip and improving the imaging quality of the system. Furthermore, the object-side surface of the seventh lens element is concave at a paraxial region thereof, and the image-side surface thereof is concave at a paraxial region thereof, which contributes to further enhancing the negative refractive power provided by the seventh lens element and appropriately increasing the optical back focus of the system.

Furthermore, the object-side surface and the image-side surface of the seventh lens element are both aspheric. The aspheric lens is characterized in that: the curvature is continuously varied from the lens center to the lens periphery, and the aspherical lens has better imaging characteristics and has an advantage of improving peripheral aberration and astigmatic field curvature, unlike a spherical lens having a constant curvature from the lens center to the lens periphery. By the mode, the flexibility of lens design can be improved, aberration can be effectively corrected, and the imaging quality of the optical system can be improved. Furthermore, at least one surface of the object side surface and the image side surface of the seventh lens is provided with at least one inflection point, so that the incidence angle of the chief ray of the off-axis field on the imaging surface is reduced, the response efficiency of the pixel unit at the edge area of the photosensitive chip is improved, the relative illumination is improved, the off-axis field aberration is reduced, and the imaging analysis capability of the system is improved.

Further, the optical system satisfies the following relation: 0.26 < (CT1+ CT2+ CT3+ CT4)/TTL < 0.29; where CT1 denotes a thickness of the first lens on the optical axis, CT2 denotes a thickness of the second lens on the optical axis, CT3 denotes a thickness of the third lens on the optical axis, CT4 denotes a thickness of the fourth lens on the optical axis, and TTL denotes a distance on the optical axis from the object-side surface of the first lens to the imaging surface of the optical system. (CT1+ CT2+ CT3+ CT4)/TTL can be 0.265, 0.27, 0.275, 0.28, 0.285, or 0.288. When satisfying above-mentioned relation, thereby can rationally set up the thickness of preceding lens group and make things convenient for the shaping and the equipment of lens, reduce the manufacturing degree of difficulty of camera lens, also be favorable to simultaneously the interval between the rational distribution lens, make optical system's lens structure compacter, realize the miniaturization of system. When (CT1+ CT2+ CT3+ CT4)/TTL is lower than the lower limit, a part of the lenses may be too thin, light cannot be effectively controlled, imaging quality is reduced, and the distance between the lenses is easily increased, which is not favorable for system miniaturization; when (CT1+ CT2+ CT3+ CT4)/TTL is higher than the upper limit, a part of the lens may be too thick, the air gap is too small, the lenses are easy to touch, and the difficulty in manufacturing and assembling the lens is increased.

When the optical system is used for imaging, light rays emitted or reflected by a shot object enter the optical system from the object side direction, sequentially pass through the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens, and finally converge on an imaging surface.

According to the optical system, the appropriate number of lenses are selected, the refractive power and the surface type of each lens are reasonably distributed, so that a larger image surface can be obtained, the imaging analysis capability of the lens can be enhanced, the aberration can be effectively corrected, and the imaging quality of an image is ensured; and when satisfying specific relation, thereby can rationally set up the thickness of preceding lens group and make things convenient for the shaping and the equipment of lens, reduce the manufacturing degree of difficulty of camera lens, also be favorable to rationally distributing the interval between the lens simultaneously, make optical system's lens structure compacter, realize the miniaturization of system.

In an exemplary embodiment, the object-side surface and the image-side surface of the first to seventh lenses may each be aspheric. The characteristics of the aspherical lens have been described above and will not be described herein. By the mode, the flexibility of lens design can be improved, aberration can be effectively corrected, the imaging quality of the optical system is improved, and the aberration generated in the light transmission process can be better corrected by setting the object side surface and the image side surface of the first lens to the seventh lens to be aspheric surfaces. It should be noted that the surface of each lens may be any combination of a spherical surface and an aspherical surface without departing from the technical solution of the optical system of the present application, and the present application does not limit this.

In an exemplary embodiment, the d-ray abbe number of at least three lenses in the optical system is below 30. The wavelength of the d light is 587.56nm, and the three lenses can be a second lens, a fourth lens and a fifth lens. When the relation is met, the light collection capacity of the system can be enhanced by arranging the high-refractive-index (namely low-Abbe number) lens, so that light can be converged into the system and focused to an imaging surface, the visual angle and the image surface brightness of the system are ensured, and meanwhile, the chromatic dispersion of the system is favorably reduced by arranging the low-refractive-index (namely high-Abbe number) lens, so that chromatic aberration (such as purple edge phenomenon) is reduced, and the imaging quality of an image is improved. The matched use of the high and low refractive index lenses can effectively reduce dispersion while focusing and imaging the system, and ensure the imaging quality of the image.

In an exemplary embodiment, the optical system satisfies the following relationship: ImgH is more than or equal to 6.34 mm; here, ImgH represents half of the image height corresponding to the maximum field angle of the optical system. Further, the half of the maximum field angle in the present application refers to the angle between the light ray incident at the maximum field angle and the optical axis of the system. ImgH may be 6.34mm, 6.36mm, 6.38mm, 6.40mm, 6.42mm, 6.44mm or 6.46 mm. When the relation is met, the system can be provided with a large-size image surface, so that the optical system can be matched with a chip with an ultra-large photosensitive area, the ultrahigh pixel imaging effect of the lens is ensured, the photosensitive area corresponding to a single pixel point can be increased, and the image quality is improved. When ImgH is lower than the lower limit, it is difficult to match a chip with a large photosensitive area, and it is difficult to realize the photographing effect of the super high pixel.

In an exemplary embodiment, the optical system satisfies the following relationship: f/EPD is less than or equal to 1.85; where f denotes an effective focal length of the optical system, and EPD denotes an entrance pupil diameter of the optical system. The f/EPD may be 1.79, 1.80, 1.81, 1.82, 1.83, 1.84, or 1.85. When the relation is met, the effective focal length and the entrance pupil diameter of the optical system can be reasonably configured, and the system can be ensured to have enough light entering amount by the front arrangement of the diaphragm, so that the shooting effect of the system in a dark light environment is improved; in addition, the enlargement of the optical ring is also beneficial to reducing the size of the Airy spots, so that the optical system has higher resolution limit and meets the design requirement of an ultrahigh pixel optical system. And when the f/EPD is higher than the upper limit, the aperture of the system is small, the imaging quality is not high, and the shooting in a low-light environment is not facilitated.

In an exemplary embodiment, the optical system satisfies the following relationship: TTL/ImgH is less than or equal to 1.404; here, ImgH represents half of the image height corresponding to the maximum field angle of the optical system. TTL/ImgH can be 1.32, 1.33, 1.34, 1.36, 1.38, 1.39, 1.40, 1.402, or 1.404. The size of the photosensitive chip is determined by ImgH, and the larger ImgH is, the larger the size of the photosensitive chip which can be supported by the optical system is, so that the ImgH can be reasonably increased when the above relation is met, the system can be conveniently adapted to the photosensitive chip with high pixels, and simultaneously, the appropriate reduction of TTL is facilitated, the length of the whole optical system is compressed, and the compact structure of the system is kept. When TTL/ImgH is higher than the upper limit, the total length of the system is likely to be longer, which is not favorable for miniaturization.

In an exemplary embodiment, the optical system satisfies the following relationship: TTL/f is more than 1.2 and less than 1.3; where f denotes an effective focal length of the optical system. TTL/f can be 1.22, 1.24, 1.25, 1.26, 1.27, 1.28, or 1.29. The total length is positively correlated with the size of the focal length, and the optical total length is inevitably increased by the long focal length, so that the total length and the effective focal length of the optical system can be reasonably configured when the relationship is met, and the miniaturization of the optical system is realized on the premise of obtaining the long focal characteristic. When the TTL/f is lower than the lower limit, the system focal length is easy to be overlong and the total length of the system is difficult to be compressed; and when the TTL/f is higher than the upper limit, the system long focus characteristic is not obtained favorably.

In an exemplary embodiment, the optical system satisfies the following relationship: the | f/f4| is less than or equal to 1.2; where f denotes an effective focal length of the optical system, and f4 denotes an effective focal length of the fourth lens. If 4 can be 2.85E-4, 0.2, 0.25, 0.3, 0.5, 0.8, 1.1, 1.12, 1.14, 1.16, 1.18 or 1.2. When the above relationship is satisfied, the effective focal length of the optical system and the effective focal length of the fourth lens element can be reasonably configured, so that the fourth lens element can provide appropriate positive refractive power or negative refractive power to adjust the overall refractive power of the system, and the first lens element, the second lens element and the third lens element form a quasi-symmetric structure, thereby balancing the distortion generated by the front lens assembly and avoiding high-order aberration caused by excessively large refractive index. When the value of f/f4 is higher than the upper limit, the effective focal length of the fourth lens element is shorter, which provides too much refractive power, which is not favorable for balancing the overall refractive power of the system, and is liable to cause over-correction of aberration and reduction of image quality.

In an exemplary embodiment, the optical system satisfies the following relationship: 0.2 < | f6/RS11| < 0.9; where f6 denotes an effective focal length of the sixth lens, and RS11 denotes a radius of curvature of an object-side surface of the sixth lens at the optical axis. If 6/RS11 can be 0.202, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.82, 0.84, 0.86, or 0.88. When the relation is satisfied, the effective focal length of the sixth lens and the curvature radius of the object side surface of the sixth lens at the optical axis are favorably and reasonably configured, so that the aberration generated by the front lens group can be effectively improved, and the resolving power of the optical system is improved. When the absolute value of f6/RS11 is lower than the lower limit, the effective focal length of the sixth lens is smaller, the positive refractive power is stronger, and high-order aberration is easily introduced; when the absolute value of f6/RS11 is higher than the lower limit, the curvature radius of the object-side surface of the sixth lens at the optical axis is smaller, and the lens surface is over-bent, which is not beneficial to the molding and assembling of the lens.

In an exemplary embodiment, the optical system satisfies the following relationship: 1.6 < SigmaCT/Sigma AT < 2.2; where Σ CT denotes the sum of thicknesses of respective lenses in the optical system on the optical axis, and Σ AT denotes the sum of air spaces of respective adjacent lenses in the optical system on the optical axis. Σ CT/∑ AT may be 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, 2.05, 2.1, or 2.15. When the relation is satisfied, the proportion of sigma CT and sigma AT in the optical system can be reasonably set, thereby realizing smooth transition of light on each mirror surface in the transmission process and being beneficial to improving the imaging quality of the optical system. When sigma CT/sigma AT is lower than the lower limit, the lens is easy to be too thin, and the lens cannot effectively control light rays, so that the imaging quality is reduced; when sigma CT/sigma AT is higher than the upper limit, the lens is easy to be too thick, so that the convergence and the diffusion of light among the lenses are not facilitated, the lens is forced to change the trend of the light in a more curved shape, and the manufacturing difficulty of the lens is increased.

In an exemplary embodiment, the optical system satisfies the following relationship: BF/TTL is more than 0.07 and less than 0.12; wherein BF represents a minimum distance in the optical axis direction from the image side surface of the seventh lens to the imaging surface of the optical system. The BF/TTL may be 0.075, 0.08, 0.09, 0.095, 0.10, 0.11, or 0.115. When satisfying above-mentioned relation, be favorable to rationally setting up optical system's optics back focal and total length of system to be favorable to the equipment of lens module, also be favorable to reducing the marginal area's on the imaging surface chief ray incident angle simultaneously, improve the relative illuminance on image plane, and then promote the imaging quality. When the BF/TTL is lower than the lower limit, the optical back focus is easy to be too small, the installation space of the lens module is insufficient, and the main ray incidence angle is not easy to be pressed; when the BF/TTL is higher than the upper limit, the optical back focus is easily too large, which is not conducive to miniaturization of the system and assembly of the lens module.

In an exemplary embodiment, the optical system satisfies the following relationship: 0.35 < | SAG72|/RS14 < 0.65; wherein SAG72 represents a distance in the optical axis direction from the intersection point of the image-side surface of the seventh lens and the optical axis to the position of the maximum effective aperture of the image-side surface of the seventh lens, and RS14 represents a curvature radius of the image-side surface of the seventh lens at the optical axis. The | SAG72|/RS14 may be 0.36, 0.38, 0.4, 0.45, 0.5, 0.55, 0.6, 0.62, or 0.64. When the relation is met, the rise of the image side surface of the seventh lens and the curvature radius of the image side surface of the seventh lens at the optical axis can be reasonably configured, so that the structural complexity of the lenses is favorably reduced, the production yield is improved, and the high-order aberration of a system is favorably reduced. When SAG 72/RS 14 is lower than the lower limit or higher than the upper limit, the lens shape is easily over-bent, which increases the difficulty of manufacturing the lens, and the lens is not easy to control light, so that the imaging quality is difficult to ensure.

In an exemplary embodiment, a diaphragm is further disposed in the optical system to better control the size of the incident light beam and improve the imaging quality of the optical system. Further, the diaphragm is arranged on the object side of the first lens. Preferably, the diaphragm is an aperture diaphragm. The aperture stop may be located on a surface of the lens (e.g., the object side surface and the image side surface) and in operative relationship with the lens, for example, by applying a light blocking coating to the surface of the lens to form the aperture stop at the surface; or the surface of the clamping lens is fixedly clamped by the clamping piece, and the structure of the clamping piece on the surface can limit the width of the imaging light beam of the on-axis object point, so that the aperture stop is formed on the surface.

In an exemplary embodiment, an optical filter is further disposed between the seventh lens and the imaging surface of the optical system, and is configured to filter light rays in a non-operating wavelength band, so as to prevent a phenomenon of generating a false color or moire due to interference of light rays in a non-operating wavelength band, and avoid distortion of imaging colors. Specifically, the filter may be an infrared cut filter, and the material of the filter is glass.

In an exemplary embodiment, each lens in the optical system may be made of glass or plastic, the plastic lens can reduce the weight and production cost of the optical system, and the glass lens can provide the optical system with better temperature tolerance and excellent optical performance. Further, when the optical system is applied to a mobile phone or a tablet, the material of each lens is preferably plastic, so as to reduce the weight of the optical system and reduce the production cost on the premise of satisfying the imaging performance. It should be noted that the material of each lens in the optical system may be any combination of glass and plastic, and is not necessarily all glass or all plastic.

In an exemplary embodiment, the optical system may further include a protective glass. The protective glass is arranged at the image side of the seventh lens or the image side of the optical filter, plays a role of protecting the photosensitive element, can prevent the photosensitive element from being polluted and dusted, and further ensures the imaging quality. When the optical system is applied to an electronic device such as a mobile phone or a tablet, the protective glass may not be provided, so as to further reduce the weight of the electronic device.

The optical system of the above-described embodiments of the present application may employ a plurality of lenses, such as the seven lenses described above. By reasonably distributing the focal length, the refractive power, the surface type, the thickness, the on-axis distance between the lenses and the like of each lens, the optical system has the characteristics of large image surface, small total length and high resolution, and simultaneously has larger aperture (FNO can be 1.79) and lighter weight, thereby better meeting the application requirements of electronic equipment such as mobile phones, flat plates and the like. However, it will be understood by those skilled in the art that the number of lenses constituting the optical system may be varied to obtain the respective results and advantages described in the present specification without departing from the technical solutions claimed in the present application.

Specific examples of optical systems that can be applied to the above-described embodiments are further described below with reference to the drawings.

Example 1

An optical system 100 of embodiment 1 of the present application is described below with reference to fig. 1 to 2.

Fig. 1 shows a schematic configuration diagram of an optical system 100 of embodiment 1. As shown in fig. 1, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, a seventh lens element L7, and an image plane S17.

The first lens element L1 with positive refractive power has an object-side surface S1 and an image-side surface S2 that are aspheric, wherein the object-side surface S1 is convex at the paraxial region and convex at the paraxial region, and the image-side surface S2 is concave at the paraxial region and concave at the paraxial region.

The second lens element L2 with negative refractive power has an object-side surface S3 and an image-side surface S4 that are aspheric, wherein the object-side surface S3 is convex at the paraxial region and convex at the paraxial region, and the image-side surface S4 is concave at the paraxial region and concave at the paraxial region.

The third lens element L3 with positive refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S6 is convex at the paraxial region and convex at the paraxial region.

The fourth lens element L4 with negative refractive power has an object-side surface S7 and an image-side surface S8 that are aspheric, wherein the object-side surface S7 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S8 is convex at the paraxial region and convex at the paraxial region.

The fifth lens element L5 with negative refractive power has an object-side surface S9 and an image-side surface S10 that are aspheric, wherein the object-side surface S9 is convex at the paraxial region and concave at the paraxial region, and the image-side surface S10 is concave at the paraxial region and convex at the paraxial region.

The sixth lens element L6 with positive refractive power has an object-side surface S11 and an image-side surface S12 that are aspheric, wherein the object-side surface S11 is convex at a paraxial region and concave at a paraxial region, and the image-side surface S12 is convex at a paraxial region and convex at a paraxial region.

The seventh lens element L7 with negative refractive power has an object-side surface S13 and an image-side surface S14 that are aspheric, wherein the object-side surface S13 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S14 is concave at a paraxial region and convex at a paraxial region.

Since the object-side surface and the image-side surface of each of the first lens element L1 to the seventh lens element L7 are aspheric, it is advantageous to correct aberrations and solve the problem of distortion of the image plane, and the optical system 100 can be miniaturized by realizing an excellent optical imaging effect even when the lens elements are small, thin, and flat.

The object side of the first lens L1 is further provided with a stop STO to limit the size of the incident light beam, so as to further improve the imaging quality of the optical system 100. The optical system 100 further includes a filter 110 disposed on the image side of the seventh lens L7 and having an object-side surface S15 and an image-side surface S16. Light from the object OBJ sequentially passes through the respective surfaces S1 to S16 and is finally imaged on the imaging plane S17. The optical filter 110 is used to filter the light in the non-operating wavelength band, thereby preventing the generation of false color or moire image due to the interference of the light in the non-operating wavelength band, and preventing the distortion of the image color. Specifically, the filter 110 is an infrared cut filter, and is made of glass.

Table 1 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of the lens of the optical system 100 of example 1, where the reference wavelength of refractive index and abbe number is 587.56nm, the reference wavelength of effective focal length is 555nm, and the unit of radius of curvature, thickness, and effective focal length of the lens are all millimeters (mm). In addition, the first value in the "thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance between the image side surface of the lens and the rear surface of the lens in the image side direction on the optical axis; the numerical value of the stop ST0 in the "thickness" parameter column is the distance on the optical axis from the stop ST0 to the vertex of the next surface (the vertex refers to the intersection point of the surface and the optical axis), and we default that the direction from the object side surface to the image side surface of the last lens of the first lens L1 is the positive direction of the optical axis, when the value is negative, it indicates that the stop ST0 is disposed on the right side of the vertex of the surface in fig. 1, and when the thickness of the stop STO is positive, the stop is on the left side of the vertex of the surface.

TABLE 1

The aspherical surface shape in the lens is defined by the following 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 reciprocal of radius of curvature R in table 1); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 2 below gives the high-order term coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 that can be used for the aspherical surfaces S1 to S14 of the lens in example 1.

TABLE 2

As can be seen from the data in tables 1 and 2, the optical system 100 in example 1 satisfies:

(CT1+ CT2+ CT3+ CT4)/TTL of 0.268, where CT1 denotes a thickness of the first lens L1 on the optical axis, CT2 denotes a thickness of the second lens L2 on the optical axis, CT3 denotes a thickness of the third lens L3 on the optical axis, CT4 denotes a thickness of the fourth lens L4 on the optical axis, and TTL denotes a distance from the object-side surface S1 of the first lens L1 to the imaging surface of the optical system 100 on the optical axis;

ImgH is 6.46mm, where ImgH represents half of the image height corresponding to the maximum field angle of the optical system 100;

1.819, where f represents the effective focal length of the optical system 100 and EPD represents the entrance pupil diameter of the optical system 100;

TTL/ImgH＝1.331；

TTL/f is 1.289, where f denotes an effective focal length of the optical system 100;

i f/f4| ═ 0.269, where f denotes the effective focal length of optical system 100, and f4 denotes the effective focal length of fourth lens L4;

i f6/RS11 i 0.591, where f6 denotes an effective focal length of the sixth lens L6, and RS11 denotes a radius of curvature of the object-side surface S11 of the sixth lens L6 at the optical axis;

Σ CT/Σ AT 1.872, where Σ CT represents the sum of thicknesses of respective lenses in the optical system 100 on the optical axis, and Σ AT represents the sum of air intervals of respective adjacent lenses in the optical system 100 on the optical axis;

BF/TTL is 0.08, where BF denotes a minimum distance in the optical axis direction from the image-side surface S14 of the seventh lens L7 to the image plane S17 of the optical system 100;

i SAG72 i/RS 14 ═ 0.515, where SAG72 denotes a distance in the optical axis direction from the intersection point of the image-side surface S14 of the seventh lens L7 and the optical axis to the maximum effective aperture of the image-side surface S14 of the seventh lens L7, and RS14 denotes a radius of curvature of the image-side surface S14 of the seventh lens L7 at the optical axis.

Fig. 2 shows a longitudinal spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system 100 of example 1, respectively. Wherein the longitudinal spherical aberration plots show the deviation of the convergent focus of the light rays with the wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism graph shows meridional (T) field curvature and sagittal (S) field curvature of a ray with a wavelength of 555nm after passing through the optical system 100; the distortion plot shows the distortion of light with a wavelength of 555nm at different image heights after passing through the optical system 100. As can be seen from fig. 2, the optical system 100 according to embodiment 1 can achieve good image quality.

Example 2

The optical system 100 of embodiment 2 of the present application is described below with reference to fig. 3 to 4. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 3 shows a schematic structural diagram of the optical system 100 according to embodiment 2 of the present application. As shown in fig. 3, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, a seventh lens element L7, and an image plane S17.

The third lens element L3 with positive refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is convex at the paraxial region and convex at the paraxial region, and the image-side surface S6 is convex at the paraxial region and convex at the paraxial region.

The fourth lens element L4 with positive refractive power has an object-side surface S7 and an image-side surface S8 that are aspheric, wherein the object-side surface S7 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S8 is convex at the paraxial region and convex at the paraxial region.

The first lens L1 to the seventh lens L7 are all made of plastic. The object side of the first lens L1 is further provided with a stop STO to limit the size of the incident light beam, so as to further improve the imaging quality of the optical system 100. The optical system 100 further includes a filter 110 disposed on the image side of the seventh lens L7 and having an object-side surface S15 and an image-side surface S16. Light from the object OBJ sequentially passes through the respective surfaces S1 to S16 and is finally imaged on the imaging surface S17. Specifically, the filter 110 is an infrared cut filter, and is made of glass.

Table 3 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 2, where the reference wavelength of refractive index and abbe number is 587.56nm, the reference wavelength of effective focal length is 555nm, and the unit of radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 4 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S14 in embodiment 2, wherein the aspherical surface type can be defined by formula (1) given in embodiment 1.

TABLE 3

TABLE 4

Fig. 4 shows a longitudinal spherical aberration chart, an astigmatism chart, and a distortion curve chart of the optical system 100 of example 2, respectively. Wherein the longitudinal spherical aberration plots show the deviation of the convergent focus of the light rays with the wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism graph shows meridional (T) field curvature and sagittal (S) field curvature of a ray with a wavelength of 555nm after passing through the optical system 100; the distortion plot shows the distortion of light with a wavelength of 555nm at different image heights after passing through the optical system 100. As can be seen from fig. 4, the optical system 100 according to embodiment 2 can achieve good image quality.

Example 3

The optical system 100 of embodiment 3 of the present application is described below with reference to fig. 5 to 6. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 5 shows a schematic structural diagram of an optical system 100 according to embodiment 3 of the present application. As shown in fig. 5, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, a seventh lens element L7, and an image plane S17.

Table 5 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 3, wherein the reference wavelength of refractive index and abbe number is 587.56nm, the reference wavelength of effective focal length is 555nm, and the unit of radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 6 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S14 in embodiment 3, wherein the aspherical surface type can be defined by formula (1) given in embodiment 1.

TABLE 5

TABLE 6

Fig. 6 shows a longitudinal spherical aberration chart, an astigmatism chart, and a distortion curve chart of the optical system 100 of example 3, respectively. Wherein the longitudinal spherical aberration plots show the deviation of the convergent focus of the light rays with the wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism graph shows meridional (T) field curvature and sagittal (S) field curvature of a ray with a wavelength of 555nm after passing through the optical system 100; the distortion plot shows the distortion of light with a wavelength of 555nm at different image heights after passing through the optical system 100. As can be seen from fig. 6, the optical system 100 according to embodiment 3 can achieve good image quality.

Example 4

The optical system 100 of embodiment 4 of the present application is described below with reference to fig. 7 to 8. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 7 shows a schematic structural diagram of an optical system 100 according to embodiment 4 of the present application. As shown in fig. 7, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, a seventh lens element L7, and an image plane S17.

The third lens element L3 with negative refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S6 is convex at the paraxial region and convex at the paraxial region.

The fourth lens element L4 with positive refractive power has an object-side surface S7 and an image-side surface S8 that are aspheric, wherein the object-side surface S7 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S8 is convex at the paraxial region and concave at the paraxial region.

The fifth lens element L5 with negative refractive power has an object-side surface S9 and an image-side surface S10 that are aspheric, wherein the object-side surface S9 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S10 is convex at the paraxial region and convex at the paraxial region.

The sixth lens element L6 with positive refractive power has an object-side surface S11 and an image-side surface S12 that are aspheric, wherein the object-side surface S11 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S12 is convex at a paraxial region and convex at a paraxial region.

Table 7 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 4, where the reference wavelength of refractive index and abbe number is 587.56nm, the reference wavelength of effective focal length is 555nm, and the unit of radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 8 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S14 in example 4, wherein the aspherical surface type can be defined by formula (1) given in example 1.

TABLE 7

TABLE 8

Fig. 8 shows a longitudinal spherical aberration chart, an astigmatism chart, and a distortion curve chart of the optical system 100 of example 4, respectively. Wherein the longitudinal spherical aberration plots show the deviation of the convergent focus of the light rays with the wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism graph shows meridional (T) field curvature and sagittal (S) field curvature of a ray with a wavelength of 555nm after passing through the optical system 100; the distortion plot shows the distortion of light with a wavelength of 555nm at different image heights after passing through the optical system 100. As can be seen from fig. 8, the optical system 100 according to embodiment 4 can achieve good image quality.

Example 5

An optical system 100 of embodiment 5 of the present application is described below with reference to fig. 9 to 10. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 9 shows a schematic structural diagram of an optical system 100 according to embodiment 5 of the present application. As shown in fig. 9, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, a seventh lens element L7, and an image plane S17.

The first lens element L1 with positive refractive power has an object-side surface S1 and an image-side surface S2 that are aspheric, wherein the object-side surface S1 is convex at a paraxial region and convex at a paraxial region, and the image-side surface S2 is convex at a paraxial region and concave at a paraxial region.

The third lens element L3 with negative refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S6 is concave at the paraxial region and convex at the paraxial region.

The fourth lens element L4 with positive refractive power has an object-side surface S7 and an image-side surface S8 that are aspheric, wherein the object-side surface S7 is convex at the paraxial region and concave at the paraxial region, and the image-side surface S8 is convex at the paraxial region and convex at the paraxial region.

The fifth lens element L5 with negative refractive power has an object-side surface S9 and an image-side surface S10 that are aspheric, wherein the object-side surface S9 is concave at the paraxial region and concave at the paraxial region, and the image-side surface S10 is concave at the paraxial region and convex at the paraxial region.

Table 9 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 5, where the reference wavelength of refractive index and abbe number is 587.56nm, the reference wavelength of effective focal length is 555nm, and the unit of radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 10 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S14 in example 5, wherein the aspherical surface type can be defined by formula (1) given in example 1.

TABLE 9

Watch 10

Fig. 10 shows a longitudinal spherical aberration chart, an astigmatism chart, and a distortion curve chart of the optical system 100 of example 5, respectively. Wherein the longitudinal spherical aberration plots show the deviation of the convergent focus of the light rays with the wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism graph shows meridional (T) field curvature and sagittal (S) field curvature of a ray with a wavelength of 555nm after passing through the optical system 100; the distortion plot shows the distortion of light with a wavelength of 555nm at different image heights after passing through the optical system 100. As can be seen from fig. 10, the optical system 100 according to embodiment 5 can achieve good image quality.

Table 11 shows the numerical values of the correlation equations of the present invention in the above embodiments.

TABLE 11

	Example 1	Example 2	Example 3	Example 4	Example 5
						f(mm)	6.67	6.89	7.24	6.92	6.86
FNO	1.82	1.79	1.8	1.8	1.85
						FOV(deg)	86.85	84.92	82.06	83.58	84.12
TTL(mm)	8.6	8.7	8.84	8.9	8.89
						ImgH(mm)	6.46	6.46	6.34	6.34	6.34
(CT1+CT2+CT3+CT4)/TTL	0.268	0.274	0.266	0.288	0.282
						f/EPD	1.819	1.79	1.80	1.80	1.85
TTL/ImgH	1.331	1.347	1.394	1.404	1.402
						TTL/f	1.289	1.262	1.221	1.286	1.297
\|f/f4\|	0.269	0.130	2.85E-4	1.181	1.151
						\|f6/RS11\|	0.591	0.810	0.845	0.398	0.202
∑CT/∑AT	1.872	2.096	1.683	2.132	2.118
						BF/TTL	0.08	0.079	0.095	0.112	0.081
\|SAG72\|/RS14	0.515	0.384	0.387	0.567	0.629

As shown in fig. 11, the present application further provides an image capturing apparatus 200, which includes the optical system 100 (shown in fig. 1) as described above; and a photosensitive element 210, the photosensitive element 210 being disposed on the image side of the optical system 100, a photosensitive surface of the photosensitive element 210 coinciding with the image forming surface S17. Specifically, the photosensitive element 210 may be a Complementary Metal Oxide Semiconductor (CMOS) image sensor or a Charge-coupled Device (CCD) image sensor, and the imaging surface S17 may be a plane or a curved surface with any curvature, especially a curved surface with a concave surface facing the object side, depending on the photosensitive element 210.

In other embodiments, the image capturing device 200 further includes a lens barrel (not shown) for carrying the optical system 100 and a corresponding supporting device (not shown).

In addition, the image capturing device 200 further includes a driving device (not shown) and an image stabilizing module (not shown). The driving device may have an Auto-Focus (Auto-Focus) function, and the driving method may use a driving system such as a Voice Coil Motor (VCM), a Micro Electro-Mechanical Systems (MEMS), a Piezoelectric system (piezo electric), and a Memory metal (Shape Memory Alloy). The driving device can make the optical system 100 obtain a better imaging position, so that the shot object can be shot to obtain a clear image under the state of different object distances; the image stabilization module may be an accelerometer, a gyroscope, or a Hall Effect Sensor. The driving device and the Image Stabilization module together serve as an Optical anti-shake device (OIS), and compensate a blurred Image generated by shaking at the moment of shooting by adjusting the displacement of the Optical axis of the Optical system 100, or provide an Electronic anti-shake function (EIS) by using an Image compensation technology in Image software, so as to further improve the imaging quality of shooting in dynamic and low-illumination scenes.

The image capturing device 200 uses the optical system 100 to adapt to the photosensitive element with an ultra-large photosensitive area, so as to obtain bright and high-pixel images, and the image capturing device 200 also has the structural characteristics of miniaturization and light weight. The image capturing device 200 can be applied to the fields of mobile phones, automobiles, monitoring, medical treatment and the like. The camera can be used as a mobile phone camera, a vehicle-mounted camera, a monitoring camera or an endoscope and the like, and has a wide market application range.

As shown in fig. 12, the present application further provides an electronic device 300, which includes a housing 310 and the image capturing device 200 as described above, wherein the image capturing device 200 is mounted on the housing 310. Specifically, the image capturing device 200 is disposed in the housing 310 and exposed from the housing 310 to obtain an image, the housing 310 can provide protection for the image capturing device 200, such as dust prevention, water prevention, falling prevention, and the like, and the housing 310 is provided with a hole corresponding to the image capturing device 200, so that light rays penetrate into or out of the housing through the hole.

The electronic device 300 has the advantage of light weight, and can capture an image with super-high pixels by using the image capturing device 200, which is beneficial to improving the capturing experience of a user. In other embodiments, the electronic device 300 is further provided with a corresponding processing system, and the electronic device 300 can transmit the image to the corresponding processing system in time after the image of the object is captured, so that the system can make accurate analysis and judgment.

In other embodiments, the use of "electronic device" may also include, but is not limited to, devices configured to receive or transmit communication signals via a wired line connection and/or via a wireless interface. Electronic devices arranged to communicate over a wireless interface may be referred to as "wireless communication terminals", "wireless terminals", or "mobile terminals". Examples of mobile terminals include, but are not limited to, satellite or cellular telephones; personal Communication System (PCS) terminals that may combine a cellular radiotelephone with data processing, facsimile and data communication capabilities; personal Digital Assistants (PDAs) that may include radiotelephones, pagers, internet/intranet access, Web browsers, notepads, calendars, and/or Global Positioning System (GPS) receivers; and conventional knee and/or palm receivers or other electronic devices including radiotelephone transceivers. In addition, the "electronic device" may further include a three-dimensional image capturing device, a digital camera, a tablet computer, a smart television, a network monitoring device, a car recorder, a car backing developing device, a multi-lens device, an identification system, a motion sensing game machine, a wearable device, and the like. The electronic device is only an exemplary embodiment of the present invention, and is not intended to limit the application scope of the image capturing device of the present application.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above 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-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the 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, in order from an object side to an image side along an optical axis, comprising:

a third lens element with refractive power;

a fifth lens element with negative refractive power;

the optical system satisfies the following relation:

0.26＜(CT1+CT2+CT3+CT4)/TTL＜0.29；

2. The optical system of claim 1, wherein at least three lenses in the optical system have d-ray abbe numbers below 30.

3. The optical system according to claim 1, wherein the optical system satisfies the following relation:

ImgH≥6.34mm；

wherein ImgH represents half of the image height corresponding to the maximum field angle of the optical system.

4. The optical system according to claim 1, wherein the optical system satisfies the following relation:

f/EPD≤1.85；

where f represents the effective focal length of the optical system and EPD represents the entrance pupil diameter of the optical system.

5. The optical system according to claim 1, wherein the optical system satisfies the following relation:

TTL/ImgH≤1.404；

6. The optical system according to claim 1, wherein the optical system satisfies the following relation:

1.2＜TTL/f＜1.3；

wherein f represents an effective focal length of the optical system.

7. The optical system according to claim 1, wherein the optical system satisfies the following relation:

|f/f4|≤1.2；

where f denotes an effective focal length of the optical system, and f4 denotes an effective focal length of the fourth lens.

8. The optical system according to claim 1, wherein the optical system satisfies the following relation:

0.2＜|f6/RS11|＜0.9；

where f6 denotes an effective focal length of the sixth lens, and RS11 denotes a radius of curvature of an object side surface of the sixth lens at an optical axis.

9. The optical system according to claim 1, wherein the optical system satisfies the following relation:

1.6＜∑CT/∑AT＜2.2；

wherein Σ CT represents the sum of thicknesses of respective lenses in the optical system on the optical axis, and Σ AT represents the sum of air spaces of respective adjacent lenses in the optical system on the optical axis.

10. The optical system according to claim 1, wherein the optical system satisfies the following relation:

0.07＜BF/TTL＜0.12；

wherein BF represents a minimum distance in an optical axis direction from an image side surface of the seventh lens to an imaging surface of the optical system.

11. The optical system according to claim 1, wherein the optical system satisfies the following relation:

0.35＜|SAG72|/RS14＜0.65；

wherein SAG72 represents the distance in the optical axis direction from the intersection point of the image side surface of the seventh lens and the optical axis to the position of the maximum effective aperture of the image side surface of the seventh lens, and RS14 represents the curvature radius of the image side surface of the seventh lens at the optical axis.

12. An image capturing device, comprising the optical system as claimed in any one of claims 1 to 11 and a photosensitive element, wherein the photosensitive element is disposed on an image side of the optical system.

13. An electronic device, comprising a housing and the image capturing device as claimed in claim 12, wherein the image capturing device is mounted on the housing.