CN211554452U

CN211554452U - Optical system, camera module and electronic device

Info

Publication number: CN211554452U
Application number: CN202020017671.XU
Authority: CN
Inventors: 华露; 杨健; 李明
Original assignee: OFilm Tech Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2020-01-06
Filing date: 2020-01-06
Publication date: 2020-09-22
Anticipated expiration: 2030-01-06

Abstract

The utility model relates to an optical system, module and electron device make a video recording. The optical system includes in order from an object side to an image side: the first lens element with positive refractive power has a convex object-side surface at an optical axis; the second lens element with negative refractive power has a concave image-side surface at the optical axis; a third lens element with positive refractive power having a convex image-side surface at an optical axis; a fourth lens element with negative refractive power having a concave image-side surface at an optical axis; the optical system also satisfies the relationship: m is more than 0.28 and less than 1.3; and M is the magnification of the optical system. When the relationship among the refractive power, the lens surface shape and the conditional expression of the lens is satisfied, the optical system is favorable for being applied to macro photography and realizing miniaturization design, and the optical system has the effect of large magnification while realizing miniaturization, so that more details of a photographed object can be obtained during macro photography, and the imaging quality of the details of the photographed object is improved.

Description

Optical system, camera module and electronic device

Technical Field

The utility model relates to an optical imaging field especially relates to an optical system, module and electron device make a video recording.

Background

In recent years, with the continuous development of technologies such as hardware and software related to smart phones and manufacturing, the demands of consumers for the diversification of the functions of the mobile phone lens and the high-quality imaging quality are increasing. Whether a picture with clear image quality can be shot under different shooting conditions is also a key factor for modern people to select which electronic product. Particularly, in macro photography, it is difficult for a general imaging lens to clearly image a subject at macro, so that an imaging picture is blurred, and details of the subject cannot be well presented.

SUMMERY OF THE UTILITY MODEL

Accordingly, it is desirable to provide an optical system, an image capturing module and an electronic device for obtaining more details of an object during macro photography.

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

the optical lens comprises a first lens element with positive refractive power, a second lens element with negative refractive power, and a third lens element with positive refractive power, wherein the object-side surface of the first lens element is convex at the optical axis;

the second lens element with negative refractive power has a concave image-side surface at an optical axis;

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

a fourth lens element with negative refractive power having a concave image-side surface at an optical axis;

the optical system further satisfies the relationship:

0.28＜M＜1.3；

wherein M is the magnification of the optical system.

When the relationship among the refractive power, the lens surface shape and the conditional expression of the lens is satisfied, the optical system is favorable for being applied to macro photography and realizing miniaturization design, and the optical system has the effect of large magnification while realizing miniaturization, so that more details of a photographed object can be obtained during macro photography, and the imaging quality of the details of the photographed object is improved. When the relation is lower than the lower limit, the effect of acquiring more details of the shot object is difficult to achieve; and above the upper limit, the optical system is not favorable for miniaturization design.

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

3.3＜TT/Imgh＜7.4；

and TT is the distance from the object plane to the imaging plane of the optical system on the optical axis, and Imgh is half of the diagonal length of the effective pixel area on the imaging plane of the optical system. When the above relation is satisfied, the optical system can realize a large magnification effect within a minute shooting distance, so that more details of the object can be shot.

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

TTL/Imgh＜2.5；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system, and Imgh is a half of a diagonal length of an effective pixel area on the imaging surface of the optical system. When the above relationship is satisfied, the optical system can be designed in a compact size.

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

-1＜f1/f2＜0；

f1 is the effective focal length of the first lens, and f2 is the effective focal length of the second lens. The first lens provides positive refractive power for the optical system, so that light rays are favorably converged to enter the optical system better, and the long-focus characteristic of the system is ensured. When the above relationship is satisfied, the second lens can diverge the light passing through the first lens, thereby effectively correcting aberration.

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

2＜TTL/f＜4；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and f is an effective focal length of the optical system. Because the optical system can realize a miniaturized design, the optical system also needs a focal length matched with the system structure while meeting the high-definition imaging performance. Accordingly, when the above relationship is satisfied, the focal length and the total optical length of the optical system can be reasonably arranged, so that the sensitivity of the optical system can be reduced and the aberration can be corrected.

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

1.8＜(f1+f3)/f＜3.2；

wherein f1 is an effective focal length of the first lens, f3 is an effective focal length of the third lens, and f is an effective focal length of the optical system. When the above relation is satisfied, the effective focal length of the first lens, the effective focal length of the third lens and the effective focal length of the optical system can be reasonably distributed, so that the optical system is ensured to have reasonable magnification in the application range of macro image capture, and effective identification precision is improved. Meanwhile, the configuration can also reduce the aberration of the optical system and improve the imaging quality of the optical system during macro shooting.

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

2＜R1/R8＜4.5；

wherein R1 is a curvature radius of an object side surface of the first lens at an optical axis, and R8 is a curvature radius of an image side surface of the fourth lens at the optical axis. When the above relationship is satisfied, the incident angle of light entering the optical system can be reduced, and the optical system has a small angle of view.

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

1.4＜CT3/CT2＜4；

wherein CT2 is the thickness of the second lens element on the optical axis, and CT3 is the thickness of the third lens element on the optical axis. When the relation is satisfied, the second lens and the third lens are matched in shape, so that the peripheral relative brightness of the system is effectively improved, and the yield of the lens during assembly can be improved.

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

0＜|SAG41|/CT4＜0.7；

wherein SAG41 is the rise of the object side of the fourth lens, and CT4 is the thickness of the fourth lens on the optical axis. When the above relationship is satisfied, the incident angle of the chief ray on the imaging surface of the optical system can be reduced, and the incident angle of the ray at the maximum field of view at the position close to the object side of the fourth lens can be effectively controlled. In addition, when the slope of the object side surface of the fourth lens changes greatly, the reflected light caused by uneven coating on the object side surface can be reduced, and stray light is avoided.

A camera module comprises a photosensitive element and the optical system, wherein the photosensitive element is arranged on the image side of the fourth lens. Through adopting above-mentioned optical system, the module of making a video recording can realize miniaturized design equally, and can also obtain more clear details of the object of making a video recording when the microspur is shot simultaneously.

An electronic device comprises a shell and the camera module, wherein the camera module is arranged on the shell. By adopting the camera module, the electronic device has excellent macro shooting capability.

Drawings

FIG. 1 is a schematic diagram of an optical system provided in a first embodiment of the present application;

fig. 2 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%);

FIG. 3 is a schematic view of an optical system provided in a second embodiment of the present application;

fig. 4 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system in the second embodiment;

FIG. 5 is a schematic view of an optical system provided in a third embodiment of the present application;

FIG. 6 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) -of the optical system in the third embodiment;

FIG. 7 is a schematic view of an optical system provided in a fourth embodiment of the present application;

FIG. 8 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) -of the optical system in the fourth embodiment;

fig. 9 is a schematic view of an optical system provided in a fifth embodiment of the present application;

fig. 10 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) -of the optical system in the fifth embodiment;

FIG. 11 is a schematic view of an optical system provided in a sixth embodiment of the present application;

fig. 12 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) -of the optical system in the sixth embodiment;

FIG. 13 is a schematic view of an optical system provided in a seventh embodiment of the present application;

fig. 14 is a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) -of the optical system in the seventh embodiment;

fig. 15 is a schematic view of a camera module according to an embodiment of the present application;

fig. 16 is a schematic view of an electronic device according to an embodiment of the disclosure.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The 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. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

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 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.

Referring to fig. 1, in an embodiment of the present application, the optical system 10 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. The lenses and the stop STO in the optical system 10 are coaxially arranged, that is, the centers of the lenses and the stop STO are located on the same straight line, which may be referred to as the optical axis of the optical system 10 and may also be referred to as the first optical axis. The projection of the stop STO on the first optical axis overlaps the projection of the first lens L1 on the first optical axis, although in some embodiments, the projection of the stop STO and the first lens L1 on the first optical axis may not overlap.

In this embodiment, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 each include only one lens. It should be noted that, in some embodiments, any one of the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 may be a lens group composed of two or more lenses, for example, the first lens L1, the second lens L2 and the third lens L3 respectively include only one lens, and the fourth lens L4 is composed of two or more lenses; or the first lens L1 and the second lens L2 each include only one piece of lens, and the third lens L3 and the fourth lens L4 each include two pieces of lens.

The first lens L1 includes an object-side surface S1 and an image-side surface S2, the second lens L2 includes an object-side surface S3 and an image-side surface S4, the third lens L3 includes an object-side surface S5 and an image-side surface S6, the fourth lens L4 includes an object-side surface S7 and an image-side surface S8, the optical system 10 further includes an image-forming surface S11, the image-forming surface S11 is located on the image-side surface of the fourth lens L4, incident light can be imaged on the image-forming surface S11 after being adjusted by each lens of the optical system 10, and the image-forming surface S11 can be regarded as a photosensitive surface of a photosensitive element for convenience of understanding. The optical system 10 also has an object plane, and a subject on the object plane can form a clear image on the image forming plane S11 of the optical system 10.

In this embodiment, the object-side surface S1 of the first lens element L1 is convex along the optical axis, the image-side surface S4 of the second lens element L2 is concave along the optical axis, the image-side surface S6 of the third lens element L3 is convex along the optical axis, and the image-side surface S8 of the fourth lens element L4 is concave along the optical axis. Satisfying the above relationship between the refractive power and the surface shape of the lens is beneficial to the application of the optical system 10 to macro photography and the realization of miniaturized design.

In this embodiment, the object-side surface and the image-side surface of each of the first lens element L1 through the fourth lens element L4 are aspheric surfaces, and the aspheric surface can effectively help the optical system 10 to eliminate aberrations and solve the problem of distortion of the field of view, and is also beneficial to the miniaturization design of the optical system 10, so that the optical system 10 can have excellent optical effects while maintaining the miniaturization design.

The surface shape of the aspheric surface can be calculated by referring to an aspheric surface formula:

z is the distance from a corresponding point on the aspheric surface to a plane tangent to the surface vertex, r 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 a conical coefficient, and Ai is a coefficient corresponding to the ith high-order term in the aspheric surface type formula.

On the other hand, it should be noted that, when the embodiments of the present application describe that one side surface of the lens is convex at the optical axis (the central region of the side surface), it can be understood that the region of the side surface of the lens near the optical axis is convex, and therefore the side surface can also be considered to be convex at the paraxial region; when one side of the lens is described as being concave at the circumference, it is understood that the side is concave in the region near the maximum effective half aperture. For example, when the side surface is convex at the optical axis and also convex at the circumference, the shape of the side surface from the center (optical axis) to the edge direction may be a pure convex surface; or first transition from a central convex shape to a concave shape and then become convex near the maximum effective half aperture. Here, the examples are only given to illustrate the relationship between the optical axis and the circumference, and various shapes of the side surfaces (concave-convex relationship) are not fully embodied, but other cases can be derived from the above examples, and should be regarded as what is described in the present application.

The image-side surface S8 of the fourth lens element L4 in some embodiments has an inflection point, and the image-side surface S8 is concave at the optical axis and convex at the circumference. When the fourth lens element L4 satisfies the above-mentioned surface shape, the total length of the optical system 10 is advantageously shortened, and the incident angle of the marginal field of view onto the imaging plane S11 is effectively reduced, so as to improve the efficiency of the light receiving element on the imaging plane S11.

In some embodiments, the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are all made of plastic. In other embodiments, the first lens L1 is made of glass, and the second lens L2, the third lens L3, and the fourth lens L4 are made of plastic, at this time, since the lens located at the object side in the optical system 10 is made of glass, the glass lenses located at the object side have a good tolerance effect on extreme environments, and are not easily affected by the object side environment to cause aging and the like, so that when the optical system 10 is in extreme environments such as exposure to high temperature, the structure can effectively avoid the situations that the imaging quality of the optical system 10 is reduced and the service life of the optical system is shortened. Plastic lenses can reduce the weight and cost of the optical system 10, while glass lenses can withstand higher temperatures and have superior optical performance. Of course, the material arrangement of each lens in the optical system 10 is not limited to the above embodiment, and any lens may be made of plastic or glass.

In some embodiments, optical system 10 includes an infrared cut filter L5, infrared cut filter L5 including an object side S9 and an image side S10. The infrared cut filter L5 is used to filter the infrared light and prevent the infrared light from reaching the imaging surface S11, thereby preventing the infrared light from interfering with normal imaging. The infrared cut filter L5 may be incorporated together with each lens as part of the optical system 10, or may be incorporated together between the optical system 10 and the light receiving element when the optical system 10 and the light receiving element are incorporated into an image pickup module. In some embodiments, an infrared cut filter L5 may also be disposed on the object side of the first lens L1. In addition, in some embodiments, the infrared cut filter L5 may not be provided, and a filter coating may be provided on any one of the first lens L1 to the fourth lens L4 to filter infrared light.

In some embodiments, the optical system 10 may further include a stop STO, an infrared cut filter L5, a protective glass, a photosensitive element, a mirror for changing an incident light path, and the like, in addition to the lens having refractive power.

In some embodiments, the optical system 10 satisfies the following relationship:

0.28＜M＜1.3；

where M is the magnification of the optical system 10. M in some embodiments may be 0.35, 0.40, 0.50, 0.55, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.15, or 1.20. When the above relationship is satisfied, the optical system 10 will have the effect of large magnification while achieving miniaturization, so that more details of the object can be obtained during macro shooting, and the imaging quality of the details of the object is improved. When the relation is lower than the lower limit, the effect of acquiring more details of the shot object is difficult to achieve; and above the upper limit, the optical system is not favorable for miniaturization design.

3.3＜TT/Imgh＜7.4；

where TT is the distance from the object plane to the imaging plane of the optical system 10 on the optical axis, and Imgh is half the diagonal length of the effective pixel area on the imaging plane of the optical system 10. TT/Imgh in some embodiments may be 3.40, 3.50, 3.70, 4.00, 4.50, 5.00, 6.00, 6.50, 7.00, 7.10, 7.20, or 7.30. When the above relationship is satisfied, the optical system 10 can achieve a large magnification effect within a minute photographing distance, so that more details of the subject can be photographed.

TTL/Imgh＜2.5；

wherein, TTL is the distance on the optical axis from the object side surface S1 of the first lens element L1 to the imaging surface S11 of the optical system 10, and Imgh is half the length of the diagonal line of the effective pixel area on the imaging surface S11 of the optical system 10. TTL/Imgh in some embodiments may be 1.70, 1.75, 1.80, 1.85, 2.00, 2.10, 2.20, 2.30, 2.40, 2.41, 2.42, or 2.43. When the above relationship is satisfied, the optical system 10 can be designed in a compact size.

-1＜f1/f2＜0；

where f1 is the effective focal length of the first lens L1, and f2 is the effective focal length of the second lens L2. The first lens element L1 provides positive refractive power to the optical system 10, thereby facilitating better convergence of light rays for entering the optical system 10 and ensuring the telephoto characteristic of the system. Some embodiments of f1/f2 can be-0.95, -0.90, -0.80, -0.70, -0.50, -0.40, -0.30, -0.25, -0.24, -0.23, or-0.22. When the above relationship is satisfied, the second lens L2 can diverge the light passing through the first lens L1, thereby effectively correcting aberration.

2＜TTL/f＜4；

wherein, TTL is an axial distance from the object-side surface S1 of the first lens element L1 to the image plane S11 of the optical system 10, and f is an effective focal length of the optical system 10. TTL/f in some embodiments may be 2.20, 2.30, 2.40, 3.00, 3.20, 3.40, 3.60, 3.65, or 3.70. Since the optical system 10 can be designed in a small size, the optical system 10 needs a focal length matching the system structure while satisfying high-definition imaging performance. Accordingly, when the above relationship is satisfied, the focal length and the total optical length of the optical system 10 can be configured reasonably, so that the sensitivity of the optical system 10 can be reduced, and aberrations can be corrected.

1.8＜(f1+f3)/f＜3.2；

where f1 is the effective focal length of the first lens L1, f3 is the effective focal length of the third lens L3, and f is the effective focal length of the optical system 10. In some embodiments (f1+ f3)/f may be 1.85, 1.90, 2.00, 2.20, 2.50, 2.80, 3.00, 3.05, 3.10, or 3.15. When the above relationship is satisfied, the effective focal length of the first lens L1, the effective focal length of the third lens L3, and the effective focal length of the optical system 10 can be reasonably distributed, so that the optical system 10 is ensured to have reasonable magnification in the application range of macro image capture, and effective recognition accuracy is improved. Meanwhile, the above configuration can also reduce the aberration of the optical system 10, and improve the imaging quality of the optical system 10 in macro photography.

2＜R1/R8＜4.5；

wherein R1 is a radius of curvature of the object-side surface S1 of the first lens element L1 at the optical axis, and R8 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 at the optical axis. R1/R8 in some embodiments can be 2.10, 2.20, 2.30, 2.50, 2.80, 3.50, 3.80, 4.00, 4.10, or 4.20. When the above relationship is satisfied, the incident angle of light entering the optical system 10 can be reduced, and the optical system 10 can have a small angle of view.

1.4＜CT3/CT2＜4；

wherein CT2 is the thickness of the second lens element L2 on the optical axis, and CT3 is the thickness of the third lens element L3 on the optical axis. CT3/CT2 in some embodiments can be 1.50, 1.55, 1.60, 1.80, 2.00, 2.50, 3.00, 3.50, 3.60, 3.65, or 3.70. When the above relation is satisfied, the mutual matching of the shapes of the second lens L2 and the third lens L3 is facilitated, so that the peripheral relative brightness of the system is effectively improved, and the yield of the lens assembly can be improved.

0＜|SAG41|/CT4＜0.7；

SAG41 is the rise of the object-side surface S7 of the fourth lens L4, i.e., the horizontal displacement parallel to the optical axis from the intersection point of the object-side surface S7 of the fourth lens L4 on the optical axis to the maximum effective radius of the object-side surface S7 of the fourth lens L4 (the horizontal displacement is defined as positive toward the image side and negative toward the object-side), and CT4 is the thickness of the fourth lens L4 on the optical axis. In some embodiments | SAG41|/CT4 may be 0.020, 0.030, 0.050, 0.100, 0.150, 0.200, 0.300, 0.500, 0.600, 0.640, 0.650, or 0.660. Satisfying the above relationship, it is possible to obtain a reduction in the incident angle of the chief ray on the imaging plane of the optical system 10 while effectively controlling the incident angle of the light ray at the maximum field of view when approaching the object-side surface S7 of the fourth lens L4. In addition, when the slope of the object-side surface S7 of the fourth lens L4 changes greatly, the amount of reflected light from the object-side surface S7 due to uneven coating can be reduced, thereby avoiding stray light.

In some embodiments, the optical system 10 has a small field of view and a short focal length, and has a high relative illumination, a small depth of field to highlight the subject and blur the background, and further, the detail imaging quality of the near object in macro photography can be effectively improved.

The optical system 10 of the present application is described in more detail with reference to the following examples:

first embodiment

Referring to fig. 1 and 2, in the first embodiment, the optical system 10 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. Fig. 2 includes a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system 10 in the first embodiment, wherein the astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm.

Here, the ordinate of the astigmatism diagram and the distortion diagram can be understood as half of the length of the diagonal line of the effective pixel area on the imaging plane S11 of the optical system 10, and the unit of the ordinate is mm.

The object-side surface S1 of the first lens element L1 is convex at the optical axis and convex at the circumference; the image side surface S2 is convex at the optical axis; convex at the circumference.

The object-side surface S3 of the second lens element L2 is convex at the optical axis and concave at the circumference; the image side surface S4 is concave at the optical axis and concave at the circumference.

The object-side surface S5 of the third lens element L3 is concave at the optical axis and concave at the circumference; the image side surface S6 is convex at the optical axis and concave at the circumference.

The object-side surface S7 of the fourth lens element L4 is concave at the optical axis and convex at the circumference; the image side surface S8 is concave at the optical axis and convex at the circumference. The object side S7 and the image side S8 of the fourth lens L4 both have an inflection point. Since the image-side surface S8 of the fourth lens element L4 has an inflection point, and the image-side surface S8 is concave at the optical axis and convex at the circumference, the total length of the optical system 10 is advantageously shortened, and meanwhile, the incident angle of the marginal field of view onto the imaging surface S11 is effectively reduced, and the efficiency of the light receiving element on the imaging surface S11 is improved.

The object-side and image-side surfaces of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are aspheric. By matching the aspheric surface type of each lens in the optical system 10, the problem of distortion of the field of view of the optical system 10 can be effectively solved, and the lens can achieve excellent optical effect under the condition of small and thin lens, so that the optical system 10 has smaller volume, and the optical system 10 is beneficial to realizing miniaturization design.

The first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are all made of plastic. The use of the plastic lens can reduce the manufacturing cost of the optical system 10 while reducing the weight of the optical system 10.

The image side of the fourth lens L4 is further provided with an infrared cut filter L5 for filtering infrared light. In some embodiments, the ir-cut filter L5 is part of the optical system 10, for example, the ir-cut filter L5 is assembled with each lens to a lens barrel. In other embodiments, the infrared cut filter L5 may also be installed between the optical system 10 and the light sensing device when the optical system 10 and the light sensing device are assembled into a camera module.

In the first embodiment, the optical system 10 satisfies the following relationships:

m ═ 0.58; where M is the magnification of the optical system 10. When the above relationship is satisfied, the optical system 10 will have the effect of large magnification while achieving miniaturization, so that more details of the object can be obtained during macro shooting, and the imaging quality of the details of the object is improved.

TT/Imgh is 3.889; where TT is the distance from the object plane to the imaging plane of the optical system 10 on the optical axis, and Imgh is half the diagonal length of the effective pixel area on the imaging plane of the optical system 10. When the above relationship is satisfied, the optical system 10 can achieve a large magnification effect within a minute photographing distance, so that more details of the subject can be photographed.

TTL/Imgh is 1.694; wherein, TTL is the distance on the optical axis from the object-side surface S1 of the first lens element L1 to the imaging surface S11 of the optical system 10, and Imgh is half the length of the diagonal line of the effective pixel area on the imaging surface of the optical system 10. When the above relationship is satisfied, the optical system 10 can be designed in a compact size.

f1/f2 is-0.463; where f1 is the effective focal length of the first lens L1, and f2 is the effective focal length of the second lens L2. The first lens element L1 provides positive refractive power to the optical system 10, thereby facilitating better convergence of light rays for entering the optical system 10 and ensuring the telephoto characteristic of the system. When the above relationship is satisfied, the second lens L2 can diverge the light passing through the first lens L1, thereby effectively correcting aberration.

TTL/f is 2.293; wherein, TTL is an axial distance from the object-side surface S1 of the first lens element L1 to the image plane S11 of the optical system 10, and f is an effective focal length of the optical system 10. Since the optical system 10 can be designed in a small size, the optical system 10 needs a focal length matching the system structure while satisfying high-definition imaging performance. Accordingly, when the above relationship is satisfied, the focal length and the total optical length of the optical system 10 can be configured reasonably, so that the sensitivity of the optical system 10 can be reduced, and aberrations can be corrected.

(f1+ f3)/f ═ 1.820; where f1 is the effective focal length of the first lens L1, f3 is the effective focal length of the third lens L3, and f is the effective focal length of the optical system 10. When the above relationship is satisfied, the effective focal length of the first lens L1, the effective focal length of the third lens L3, and the effective focal length of the optical system 10 can be reasonably distributed, so that the optical system 10 is ensured to have reasonable magnification in the application range of macro image capture, and effective recognition accuracy is improved. Meanwhile, the above configuration can also reduce the aberration of the optical system 10, and improve the imaging quality of the optical system 10 in macro photography.

R1/R8 ═ 2.036; wherein R1 is a radius of curvature of the object-side surface S1 of the first lens element L1 at the optical axis, and R8 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 at the optical axis. When the above relationship is satisfied, the incident angle of light entering the optical system 10 can be reduced, and the optical system 10 can have a small angle of view.

CT3/CT 2-1.824; wherein CT2 is the thickness of the second lens element L2 on the optical axis, and CT3 is the thickness of the third lens element L3 on the optical axis. When the above relation is satisfied, the mutual matching of the shapes of the second lens L2 and the third lens L3 is facilitated, so that the peripheral relative brightness of the system is effectively improved, and the yield of the lens assembly can be improved.

0.676, | SAG41|/CT 4; SAG41 is the rise of the object-side surface S7 of the fourth lens L4, i.e., the horizontal displacement parallel to the optical axis from the intersection point of the object-side surface S7 of the fourth lens L4 on the optical axis to the maximum effective radius of the object-side surface S7 of the fourth lens L4 (the horizontal displacement is defined as positive toward the image side and negative toward the object-side), and CT4 is the thickness of the fourth lens L4 on the optical axis. Satisfying the above relationship, it is possible to obtain a reduction in the incident angle of the chief ray on the imaging plane of the optical system 10 while effectively controlling the incident angle of the light ray at the maximum field of view when approaching the object-side surface S7 of the fourth lens L4. In addition, when the slope of the object-side surface S7 of the fourth lens L4 changes greatly, the amount of reflected light from the object-side surface S7 due to uneven coating can be reduced, thereby avoiding stray light.

When the above relationships are satisfied, the optical system 10 has a small field of view and a short focal length, has a high relative illumination, and also has a small depth of field to highlight the theme and blur the background, and in addition, can effectively improve the detail imaging quality of a near object during macro photography.

In addition, each lens parameter of the optical system 10 is given by table 1 and table 2, where K in table 2 is a conical coefficient, and Ai is a coefficient corresponding to the i-th high-order term in the aspherical surface type formula. The elements from the object plane to the image plane S11 are sequentially arranged in the order of the elements from top to bottom in table 1, wherein the object located on the object plane can form a sharp image on the image plane S11 of the optical system 10. Surface numbers 1 and 2 respectively indicate an object-side surface S1 and an image-side surface S2 of the first lens L1, that is, a surface having a smaller surface number is an object-side surface and a surface having a larger surface number is an image-side surface in the same lens. The Y radius in table 1 is the radius of curvature of the object-side or image-side surface at the paraxial (or understood to be on the optical axis) of the corresponding surface number. The first value of the lens in the "thickness" parameter set is the thickness of the lens on the optical axis, and the second value is the distance from the image-side surface of the lens to the object-side surface of the next lens on the optical axis. The numerical value of the stop STO in the "thickness" parameter column is the distance on the optical axis from the stop STO to the vertex of the object-side surface (the vertex refers to the intersection point of the lens and the optical axis) of the subsequent lens (in this embodiment, the first lens L1), the direction from the object-side surface to the image-side surface of the last lens is the positive direction of the optical axis by default, when the value is negative, it indicates that the stop STO is disposed on the right side of the vertex of the object-side surface of the lens (or understood to be located on the image-side of the vertex), and when the "thickness" parameter of the stop STO is positive, the stop STO is on the left side of the vertex of the object-side surface of the lens (or understood to be located on. In this embodiment, the projection of the stop STO on the first optical axis partially overlaps with the projection of the first lens L1 on the first optical axis. The optical axes of the lenses in the embodiment of the present application are on the same straight line as the optical axis of the optical system 10. The "thickness" parameter value in the surface number 8 is the distance on the optical axis from the image-side surface S8 of the fourth lens L4 to the object-side surface S9 of the infrared cut filter L5. The "thickness" parameter value corresponding to the surface number 10 of the ir-cut filter L5 is the distance on the optical axis from the image side surface S10 of the ir-cut filter L5 to the image surface (image surface S11) of the optical system 10.

In the first embodiment, the effective focal length f of the optical system 10 is 1.33mm, the f-number FNO is 3.05, the maximum field angle (diagonal view angle) FOV is 75.7 °, the total optical length TTL is 3.05mm, and the total optical length TTL is the distance on the optical axis from the object-side surface S1 of the first lens L1 to the image plane S11 of the optical system 10.

In the following examples (first, second, third, fourth, fifth, sixth, and seventh examples), the refractive index, abbe number, and focal length of each lens were all numerical values at a wavelength of 555 nm. In addition, the relational expression calculation and the lens structure of each example are based on lens parameters (e.g., table 1, table 2, table 3, table 4, etc.).

TABLE 1

TABLE 2

Second embodiment

In the second embodiment, referring to fig. 3 and 4, the optical system 10 includes, in order from the object side to the image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. Fig. 4 includes a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system 10 in the second embodiment, wherein the astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm.

The ordinate of the astigmatism diagram and the distortion diagram is half of the diagonal length of the effective pixel area on the imaging plane S11 of the optical system 10, and the unit of the ordinate is mm.

The object-side surface S1 of the first lens element L1 is convex at the optical axis and convex at the circumference; the image side surface S2 is concave at the optical axis; the circumference is concave.

The object-side surface S3 of the second lens element L2 is convex at the optical axis and concave at the circumference; the image side surface S4 is concave at the optical axis and convex at the circumference.

The object-side surface S5 of the third lens element L3 is convex at the optical axis and concave at the circumference; the image side surface S6 is convex at the optical axis and convex at the circumference.

The object-side surface S7 of the fourth lens element L4 is convex at the optical axis and concave at the circumference; the image side surface S8 is concave at the optical axis and convex at the circumference. The object side S7 and the image side S8 of the fourth lens L4 both have an inflection point. Since the image-side surface S8 of the fourth lens element L4 has an inflection point, and the image-side surface S8 is concave at the optical axis and convex at the circumference, the total length of the optical system 10 is advantageously shortened, and meanwhile, the incident angle of the marginal field of view onto the imaging surface S11 is effectively reduced, and the efficiency of the light receiving element on the imaging surface S11 is improved.

In the second embodiment, the effective focal length f of the optical system 10 is 2.05mm, the f-number FNO is 3.05, the maximum field angle (diagonal angle of view) FOV is 68 °, and the total optical length TTL is 4.4 mm.

In addition, the lens parameters of the optical system 10 are given in tables 3 and 4, wherein the definition of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 3

TABLE 4

From the above data, one can see:

third embodiment

In the third embodiment, referring to fig. 5 and fig. 6, the optical system 10 includes, in order from the object side to the image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. Fig. 6 includes a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system 10 in the third embodiment, wherein the astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm.

The object-side surface S1 of the first lens element L1 is convex at the optical axis and concave at the circumference; the image side surface S2 is convex at the optical axis; convex at the circumference.

The object-side surface S3 of the second lens element L2 is concave at the optical axis and concave at the circumference; the image side surface S4 is concave at the optical axis and convex at the circumference.

The object-side surface S5 of the third lens element L3 is convex at the optical axis and convex at the circumference; the image side surface S6 is convex at the optical axis and concave at the circumference.

In the third embodiment, the effective focal length f of the optical system 10 is 1.18mm, the f-number FNO is 3.05, the maximum field angle (diagonal angle of view) FOV is 76.0 °, and the total optical length TTL is 4.38 mm.

In addition, the lens parameters of the optical system 10 are given in tables 5 and 6, wherein the definition of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 5

TABLE 6

From the above data, one can see:

fourth embodiment

In the fourth embodiment, referring to fig. 7 and 8, the optical system 10 includes, in order from the object side to the image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. Fig. 8 includes a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system 10 in the fourth embodiment, wherein the astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm.

In the fourth embodiment, the effective focal length f of the optical system 10 is 1.21mm, the f-number FNO is 3.05, the maximum field angle (diagonal angle of view) FOV is 76.0 °, and the total optical length TTL is 4.38 mm.

In addition, the lens parameters of the optical system 10 are given in tables 7 and 8, wherein the definition of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 7

TABLE 8

From the above data, one can see:

fifth embodiment

In the fifth embodiment, referring to fig. 9 and 10, the optical system 10 includes, in order from the object side to the image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. Fig. 10 includes a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system 10 in the fifth embodiment, wherein the astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm.

In the fifth embodiment, the effective focal length f of the optical system 10 is 1.19mm, the f-number FNO is 3.05, the maximum field angle (diagonal angle of view) FOV is 74.1 °, and the total optical length TTL is 3.50 mm.

In addition, the lens parameters of the optical system 10 are given in tables 9 and 10, wherein the definition of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 9

Watch 10

From the above data, one can see:

sixth embodiment

Referring to fig. 11 and 12, in the sixth embodiment, the optical system 10 includes, in order from the object side to the image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. Fig. 12 includes a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system 10 in the sixth embodiment, wherein the astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm.

The object-side surface S7 of the fourth lens element L4 is convex at the optical axis and convex at the circumference; the image side surface S8 is concave at the optical axis and convex at the circumference. The image side surface S8 of the fourth lens L4 has an inflection point. Since the image-side surface S8 of the fourth lens element L4 has an inflection point, and the image-side surface S8 is concave at the optical axis and convex at the circumference, the total length of the optical system 10 is advantageously shortened, and meanwhile, the incident angle of the marginal field of view onto the imaging surface S11 is effectively reduced, and the efficiency of the light receiving element on the imaging surface S11 is improved.

In the sixth embodiment, the effective focal length f of the optical system 10 is 1.23mm, the f-number FNO is 3.05, the maximum field angle (diagonal angle of view) FOV is 76 °, and the total optical length TTL is 3.52 mm.

In addition, the lens parameters of the optical system 10 are given in tables 11 and 12, wherein the definition of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 11

TABLE 12

From the above data, one can see:

seventh embodiment

Referring to fig. 13 and 14, in the seventh embodiment, the optical system 10 includes, in order from the object side to the image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. Fig. 14 includes a spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system 10 in the seventh embodiment, wherein the astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm.

The object-side surface S5 of the third lens element L3 is convex at the optical axis and concave at the circumference; the image side surface S6 is convex at the optical axis and concave at the circumference.

The object-side surface S7 of the fourth lens element L4 is convex at the optical axis and concave at the circumference; the image side surface S8 is concave at the optical axis and convex at the circumference. The image side surface S8 of the fourth lens L4 has an inflection point. Since the image-side surface S8 of the fourth lens element L4 has an inflection point, and the image-side surface S8 is concave at the optical axis and convex at the circumference, the total length of the optical system 10 is advantageously shortened, and meanwhile, the incident angle of the marginal field of view onto the imaging surface S11 is effectively reduced, and the efficiency of the light receiving element on the imaging surface S11 is improved.

In the seventh embodiment, the effective focal length f of the optical system 10 is 1.34mm, the f-number FNO is 3.05, the maximum field angle (diagonal angle of view) FOV is 73.8 °, and the total optical length TTL is 3.27 mm.

In addition, the lens parameters of the optical system 10 are given in tables 13 and 14, wherein the definition of the parameters can be obtained from the first embodiment, which is not described herein.

Watch 13

TABLE 14

From the above data, one can see:

referring to fig. 15, in an embodiment provided in the present application, the optical system 10 is assembled with the photosensitive element 210 to form the camera module 20, and at this time, an infrared cut filter L5 is disposed between the fourth lens L4 and the photosensitive element 210 in this embodiment. The photosensitive element 210 may be a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). By adopting the optical system 10, the camera module 20 can be designed in a small size, and can obtain more clear details of the object to be shot when shooting at a micro distance.

In some embodiments, the distance between the photosensitive element 210 and each lens in the optical system 10 is relatively fixed, and the camera module 20 is a fixed focus module. In other embodiments, a driving mechanism such as a voice coil motor may be provided to enable the photosensitive element 210 to move relative to each lens in the optical system 10, so as to achieve a focusing effect. In some embodiments, an optical zoom effect may also be achieved by providing a drive mechanism to drive movement of a portion of the lenses in the optical system 10.

Referring to fig. 16, some embodiments of the present application further provide an electronic device 30, and the camera module 20 is applied to the electronic device 30. Specifically, the electronic device 30 includes a housing 310, the camera module 20 is mounted on the housing 310, and the housing 310 may be a circuit board, a middle frame, or the like. The electronic device 30 includes, but is not limited to, a smart phone, a smart watch, an e-book reader, a vehicle-mounted camera, a monitoring device, a medical device (such as an endoscope), a tablet computer, a biometric device (such as a fingerprint recognition device or a pupil recognition device), a PDA (Personal Digital Assistant), an unmanned aerial vehicle, and the like. Specifically, in some embodiments, the camera module 20 is applied to a smart phone, the smart phone includes a middle frame and a circuit board, the circuit board is disposed in the middle frame, the camera module 20 is installed in the middle frame of the smart phone, and the light sensing element is electrically connected to the circuit board. The camera module 20 can be used as a front camera module or a rear camera module of the smart phone. By using the camera module 20, the electronic device 30 has excellent macro-photographing capability.

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

Claims

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

the optical system further satisfies the relationship:

0.28＜M＜1.3；

wherein M is the magnification of the optical system.

2. The optical system according to claim 1, characterized in that the following relation is satisfied:

3.3＜TT/Imgh＜7.4；

and TT is the distance from the object plane to the imaging plane of the optical system on the optical axis, and Imgh is half of the diagonal length of the effective pixel area on the imaging plane of the optical system.

3. The optical system according to claim 1, characterized in that the following relation is satisfied:

TTL/Imgh＜2.5；

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

4. The optical system according to claim 1, characterized in that the following relation is satisfied:

-1＜f1/f2＜0；

wherein f1 is the effective focal length of the first lens, and f2 is the effective focal length of the second lens.

5. The optical system according to claim 1, characterized in that the following relation is satisfied:

2＜TTL/f＜4；

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

6. The optical system according to claim 1, characterized in that the following relation is satisfied:

1.8＜(f1+f3)/f＜3.2；

wherein f1 is an effective focal length of the first lens, f3 is an effective focal length of the third lens, and f is an effective focal length of the optical system.

7. The optical system according to claim 1, characterized in that the following relation is satisfied:

2＜R1/R8＜4.5；

wherein R1 is a curvature radius of an object side surface of the first lens at an optical axis, and R8 is a curvature radius of an image side surface of the fourth lens at the optical axis.

8. The optical system according to claim 1, characterized in that the following relation is satisfied:

1.4＜CT3/CT2＜4；

wherein CT3 is the thickness of the third lens element on the optical axis, and CT2 is the thickness of the second lens element on the optical axis.

9. The optical system according to claim 1, characterized in that the following relation is satisfied:

0＜|SAG41|/CT4＜0.7；

wherein SAG41 is the rise of the object side of the fourth lens, and CT4 is the thickness of the fourth lens on the optical axis.

10. An image capturing module comprising a photosensitive element and the optical system of any one of claims 1 to 9, wherein the photosensitive element is disposed on the image side of the fourth lens element.

11. An electronic device, comprising a housing and the camera module of claim 10, wherein the camera module is disposed on the housing.