CN111929812A

CN111929812A - Optical system, camera module and electronic equipment

Info

Publication number: CN111929812A
Application number: CN202010793987.2A
Authority: CN
Inventors: 蔡雄宇; 兰宾利; 周芮
Original assignee: Tianjin OFilm Opto Electronics Co Ltd
Current assignee: Tianjin OFilm Opto Electronics Co Ltd
Priority date: 2020-08-10
Filing date: 2020-08-10
Publication date: 2020-11-13

Abstract

An optical system, a camera module and an electronic device, the optical system comprises the following components in sequence from an object side to an image side: the first lens element with negative refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a second lens having a positive bending force, an object side surface of the second lens being a plane; a third lens having a positive refracting power; a fourth lens having a negative bending force; a fifth lens having a positive refracting power; and a sixth lens having a positive refracting power. By reasonably configuring the surface shapes and the bending forces of the first lens to the sixth lens, the optical system has a larger field angle, the optical system can meet the design requirement of clear imaging in a larger angle range, and the safety of the driving environment in a large angle range can be accurately judged in real time. Meanwhile, the object side surface of the second lens is a plane, so that the assembly eccentricity sensitivity of the second lens is reduced, the assembly yield is improved, and the production cost is reduced.

Description

Optical system, camera module and electronic equipment

Technical Field

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

Background

With the development of the vehicle-mounted industry, the technical requirements of vehicle-mounted cameras such as forward looking cameras, automatic cruising cameras, automobile data recorders and reverse images are higher and higher. The forward-looking camera is an on-vehicle camera installed in front of a vehicle, and can be used as a camera in an advanced driver Assistance system to analyze video content and provide services such as Lane Departure Warning (LDW), automatic Lane Keeping Assistance (LKA), high beam/low beam control (high beam/low beam) and Traffic Sign Recognition (TSR). When the automobile is parked in the parking space, the automobile is started, and the obstacles in front of the automobile can be visually seen, so that the automobile is parked in the parking space more conveniently. When the automobile passes through a special place (such as a road block, a parking lot and the like), the forward-looking camera is opened, so that the driving environment can be judged and the feedback can be made to the automobile central system, and a correct instruction can be made to avoid driving accidents.

However, the existing forward-looking camera lens cannot meet the requirement of clear imaging in a large-angle range, and cannot accurately judge obstacles in the large-angle range in real time to avoid the obstacles, so that the driving risk exists.

Disclosure of Invention

The invention aims to provide an optical system, a camera module and electronic equipment, which can meet the design requirement of clear imaging in a larger angle range.

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

in a first aspect, the present invention provides an optical system comprising, in order from an object side to an image side: a first lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the second lens has positive bending force, and the object side surface of the second lens is a plane; a third lens having a positive refracting power; a fourth lens having a negative bending force; a fifth lens having a positive refracting power; and a sixth lens having a positive refracting power. By reasonably configuring the surface shapes and the bending forces of the first lens to the sixth lens, the optical system has a larger field angle, the optical system can meet the design requirement of clear imaging in a larger angle range, and the safety of the driving environment in a large angle range can be accurately judged in real time. Meanwhile, the object side surface of the second lens is a plane, so that the assembly eccentricity sensitivity of the second lens is reduced, the assembly yield is improved, and the production cost is reduced.

In one embodiment, the image-side surface of the fourth lens element is concave, the object-side surface and the image-side surface of the fifth lens element are both convex, and the image-side surface of the fourth lens element and the object-side surface of the fifth lens element are cemented together to form the combined lens. By reasonably configuring the surface types of the fourth lens and the fifth lens and gluing the fourth lens and the fifth lens into a combined lens, the assembly sensitivity of the optical system is favorably reduced, so that the problems of lens process manufacturing and lens assembly are solved, and the yield is improved.

In one embodiment, the optical system satisfies the conditional expression: -4< f1/SAGs2< -3; wherein SAGs2 is the saggital height at the edge of the image side optically effective diameter of the first lens, and f1 is the effective focal length of the first lens. It can be understood that there may be obstacles or accidents at a long distance, and the driver needs to be warned, so increasing the resolution of the central view field is also a necessary means to reduce the driving risk. By setting the value of f1/SAGs2 between-4 and-3, the shape of the image side face of the first lens is reasonably designed, the pixel density distribution of different fields of view of the optical system is favorably optimized, the pixel resolution of the edge field of view is not influenced, the pixel density of the central field of view is improved, the purpose of high resolution of the central field of view is realized, and the safety of the driving environment far ahead is favorably and accurately judged in real time. It can be understood that when the value of f1/SAGs2 is lower than-4, the image side surface of the first lens is too curved, the processing difficulty of the lens is high, and the process production of the lens is not facilitated; when the value of f1/SAGs2 is higher than-3, the effective focal length of the first lens is larger, so that the bending force of the first lens is insufficient, and the expansion of the field angle range of the optical system is not facilitated.

In one embodiment, the optical system satisfies the conditional expression: 2< f2/f < 3.3; wherein f2 is the effective focal length of the second lens, and f is the effective focal length of the optical system. Through satisfying f2/f between 2 and 3.3, the second lens is positive lens, for the positive power of buckling of system provides, is favorable to contracting the light width, makes the light shrink that the high-angle light was absorb after first lens refraction, is favorable to proofreading the aberration that the high-angle light penetrated into first lens difference simultaneously to promote optical system's resolving power. It is understood that the value of f2/f is lower than 2 or higher than 3.3, which is not favorable for correcting the aberration of the optical system, thereby reducing the imaging quality.

In one embodiment, the optical system satisfies the conditional expression: 10< f45/(CT5-CT4) < 26; wherein f45 is a combined effective focal length of the fourth lens and the fifth lens, CT5 is an optical thickness of the fifth lens, and CT4 is an optical thickness of the fourth lens. By satisfying that the value of f45/(CT5-CT4) is between 10 and 26, the fifth lens with positive bending force and the fourth lens with negative bending force can be reasonably matched, so that the mutual correction of aberration is performed, and the minimum aberration contribution ratio of the fourth lens and the fifth lens to the optical system is favorably provided. It can be understood that when the value of f45/(CT5-CT4) is less than 10, the difference between the central thicknesses of the fourth lens and the fifth lens is too large, which is not beneficial to the gluing process, and in the environment with large temperature difference, the difference between the cold deformation and the hot deformation caused by the difference between the thicknesses is large, which is easy to generate phenomena such as glue crack or glue failure; when the value of f45/(CT5-CT4) is higher than 26, the effective focal length of the combination of the fourth lens element and the fifth lens element is too large, and the combined lens element is prone to generating a severe astigmatism phenomenon, which is not favorable for improving the imaging quality of the optical system.

In one embodiment, the optical system satisfies the conditional expression: EDs9/SAGs9> 4.9; SAGs9 is the rise of the edge of the fourth lens image-side surface and the fifth lens object-side surface optical effective diameter, EDs9 is the optical effective diameter of the fourth lens image-side surface and the fifth lens object-side surface. By meeting the requirement that the value of EDs9/SAGs9 is higher than 4.9, the bending degree of the cemented surface of the combined lens is favorably controlled, the assembly eccentricity sensitivity of the combined lens is reduced, and the yield is favorably improved. It can be understood that when the value of EDs9/SAGs9 is less than 4.9, the gluing surface is too curved to facilitate the gluing process, and the risk of relative decentration between the two lenses increases; meanwhile, the assembly eccentricity sensitivity of the combined lens is increased, which is not beneficial to improving the yield.

In one embodiment, the optical system satisfies the conditional expression: 1.5<2 x Y/EPD < 2.0; wherein Y is half of the maximum image height of the imaging surface of the optical system, and EPD is the entrance pupil diameter of the optical system. By meeting the requirement that the value of 2-x-Y/EPD is between 1.5 and 2.0, the optical system meets the requirements of large image surface and high-quality imaging, and controls the diameter of the entrance pupil of the optical system at the same time, thereby ensuring the brightness of the imaging surface of the optical system to be improved. It can be understood that when the value of 2 × Y/EPD is higher than 2.0, the entrance pupil diameter is small, which causes insufficient brightness, and high-definition shooting cannot be satisfied; when the value of 2 × Y/EPD is less than 1.5, the size of the imaging plane of the optical system is too small to obtain enough object space information.

In one embodiment, the optical system satisfies the conditional expression: 4.2< TTL/f < 5.3; wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane, and f is an effective focal length of the optical system. By meeting the TTL/f value between 4.2 and 5.3, the total length of the optical system is controlled while the optical system has a larger field angle range, so that the optical system is convenient to realize miniaturization. When TTL/f is higher than 5.3, the total length of the optical system is too long, which is not beneficial to miniaturization; when TTL/f is less than 4.2, the effective focal length of the optical system is too long, and the field angle range of the optical system is too small to obtain sufficient object space information.

In a second aspect, the present invention further provides an image capturing module, which includes a lens barrel, a photosensitive element and the optical system according to any one of the embodiments of the first aspect, wherein the first to sixth lenses of the optical system are mounted in the lens barrel, and the photosensitive element is disposed on an image side of the optical system. By adding the optical system provided by the invention into the camera module, the camera module can clearly image in a larger angle range, and the safety of the driving environment in a large angle range can be accurately judged in real time.

In one embodiment, the optical system satisfies the conditional expression: Y10/(FOV 10P) is not less than 26 deg-1; wherein Y10 is half of the image height corresponding to the 10 ° field angle of the optical system, FOV10 is the 10 ° field angle of the optical system, and P is the size of the unit pixel on the photosensitive element. Specifically, the FOV10 in this example is 10 °, and P is 0.003 mm. By meeting the condition that the value of Y10/(FOV10 × P) is higher than 26deg-1, the pixel number distribution of each degree of field angle in the central field range of the optical system is optimized, and the pixel and imaging analysis capability with enough height in the central field range can be ensured, so that important information in the central field range of the field is clearly and prominently displayed, the characteristic of small field long focus can be embodied, and the long-distance shooting details are clearly displayed, so that the early warning of a distant obstacle or an emergency can be conveniently carried out.

In one embodiment, 20 deg.C-1 ≦ (Y50-Y10)/[ (1/2) × (FOV50-FOV10) × P ] ≦ 26 deg.C-1; wherein Y50 is a half of the image height corresponding to the 50 ° field angle of the optical system, Y10 is a half of the image height corresponding to the 10 ° field angle of the optical system, FOV50 is the 50 ° field angle of the optical system, FOV10 is the 10 ° field angle of the optical system, and P is the size of the unit pixel on the photosensitive element. Specifically, the FOV50 in this example has a value of 50 °, the FOV10 has a value of 10 °, and the value of P is 0.003 mm. By meeting the requirement that the value of (Y50-Y10)/[ (1/2) × (FOV50-FOV10) × P ] is between 20deg-1 and 26deg-1, the pixel number distribution of each degree of field angle of the optical system close to the central field range is controlled, the pixel number and the imaging resolving power close to the central field range can be ensured to be high enough, and important information close to the central field range is clearly highlighted, so that the camera module provides better visual effect.

In one embodiment, the optical system satisfies the conditional expression: 9deg-1 ≦ (Y-Y50)/[ (1/2) (FOV-FOV50) × P ] ≦ 20 deg-1; wherein, Y is half of the maximum image height of the imaging surface of the optical system, Y50 is half of the image height corresponding to the 50 ° field angle of the optical system, FOV is the maximum field angle of the optical system, FOV50 is the 50 ° field angle of the optical system, and P is the size of the unit pixel on the photosensitive element. Specifically, the FOV50 in this embodiment is 50 °. The value of (Y-Y50)/(FOV 100P) is between 9deg-1 and 20deg-1, so that the pixel number distribution of each angle of view in the edge field range of the optical system is controlled, the pixel and imaging resolution capability of the edge field can be ensured, the wide-angle edge field can be clearly imaged, the characteristic of wide large-field shooting range is reflected, and the camera module can provide better visual effect.

In a third aspect, the present invention further provides an electronic device, where the electronic device includes a housing and the camera module according to any one of the embodiments of the second aspect, and the camera module is disposed in the housing. By adding the optical system provided by the invention into the electronic equipment, the electronic equipment can clearly image in a larger angle range, and the safety of the driving environment in a large angle range can be accurately judged in real time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1a is a schematic structural diagram of an optical system of a first embodiment;

FIG. 1b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the first embodiment;

FIG. 2a is a schematic structural diagram of an optical system of a second embodiment;

FIG. 2b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the second embodiment;

FIG. 3a is a schematic structural diagram of an optical system of a third embodiment;

FIG. 3b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the third embodiment;

FIG. 4a is a schematic structural diagram of an optical system of a fourth embodiment;

FIG. 4b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the fourth embodiment;

FIG. 5a is a schematic structural diagram of an optical system of a fifth embodiment;

fig. 5b is a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the fifth embodiment.

Detailed Description

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

The embodiment of the invention provides electronic equipment, which comprises a shell and a camera module provided by the embodiment of the invention, wherein the camera module is arranged in the shell. This electronic equipment can be for smart mobile phone, Personal Digital Assistant (PDA), panel computer, intelligent wrist-watch, unmanned aerial vehicle, electronic books read ware, vehicle event data recorder, wearable device and control security protection equipment etc.. Preferably to advanced driver assistance systems. By adding the optical system provided by the invention into the electronic equipment, the electronic equipment can clearly image in a larger angle range, and the safety of the driving environment in a large angle range can be accurately judged in real time.

The embodiment of the invention also provides a camera module, which comprises a lens barrel, a photosensitive element and the optical system, wherein the first lens to the sixth lens of the optical system are arranged in the lens barrel, and the photosensitive element is arranged at the image side of the optical system and is used for converting light rays of an object which passes through the first lens to the sixth lens and is incident on the photosensitive element into an electric signal of an image. The photosensitive element may be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). The camera module can be an independent lens of a digital camera, and also can be an imaging module integrated on electronic equipment such as a smart phone, preferably a front-view camera in an advanced driver assistance system and a monitoring security device. By adding the optical system provided by the invention into the camera module, the camera module can clearly image in a larger angle range, and the safety of the driving environment in a large angle range can be accurately judged in real time.

In one embodiment, the optical system satisfies the conditional expression: Y10/(FOV 10P) is not less than 26 deg-1; where Y10 is half the image height corresponding to the 10 ° field angle of the optical system, FOV10 is the 10 ° field angle of the optical system, and P is the size of a unit pixel on the photosensitive element. Specifically, the FOV10 in this example is 10 °, and P is 0.003 mm. By meeting the condition that the value of Y10/(FOV10 × P) is higher than 26deg-1, the pixel number distribution of each degree of field angle in the central field range of the optical system is optimized, and the pixel and imaging analysis capability with enough height in the central field range can be ensured, so that important information in the central field range of the field is clearly and prominently displayed, the characteristic of small field long focus can be embodied, and the long-distance shooting details are clearly displayed, so that the early warning of a distant obstacle or an emergency can be conveniently carried out. Specifically, the value of Y10/(FOV 10P) may be 26deg-1, 28deg-1, 30deg-1, 36deg-1, 48deg-1, 65deg-1, etc.

In one embodiment, the optical system satisfies the conditional expression: 20deg-1 ≦ (Y50-Y10)/[ (1/2) × (FOV50-FOV10) × P ] ≦ 26 deg-1; wherein Y50 is half of the image height corresponding to the 50 ° field angle of the optical system, Y10 is half of the image height corresponding to the 10 ° field angle of the optical system, FOV50 is the 50 ° field angle of the optical system, FOV10 is the 10 ° field angle of the optical system, and P is the size of a unit pixel on the photosensitive element. Specifically, the FOV50 in this example has a value of 50 °, the FOV10 has a value of 10 °, and the value of P is 0.003 mm. By meeting the requirement that the value of (Y50-Y10)/[ (1/2) × (FOV50-FOV10) × P ] is between 20deg-1 and 26deg-1, the pixel number distribution of each degree of field angle of the optical system close to the central field range is controlled, the pixel number and the imaging resolving power close to the central field range can be ensured to be high enough, and important information close to the central field range is clearly highlighted, so that the camera module provides better visual effect. Specifically, the value of (Y50-Y10)/[ (1/2) × (FOV50-FOV10) × P ] may be 20deg-1, 20.5deg-1, 21deg-1, 22deg-1, 23.5deg-1, 24.6deg-1, 25.2deg-1, 26deg-1, etc.

In one embodiment, the optical system satisfies the conditional expression: 9deg-1 ≦ (Y-Y50)/[ (1/2) (FOV-FOV50) × P ] ≦ 20 deg-1; wherein, Y is half of the maximum image height of the imaging surface of the optical system, Y50 is half of the image height corresponding to the 50 ° field angle of the optical system, FOV is the maximum field angle of the optical system, FOV50 is the 50 ° field angle of the optical system, and P is the size of the unit pixel on the photosensitive element. Specifically, the FOV50 in this embodiment is 50 °. The value of (Y-Y50)/(FOV 100P) is between 9deg-1 and 20deg-1, so that the pixel number distribution of each angle of view in the edge field range of the optical system is controlled, the pixel and imaging resolution capability of the edge field can be ensured, the wide-angle edge field can be clearly imaged, the characteristic of wide large-field shooting range is reflected, and the camera module can provide better visual effect. Specifically, the value of (Y-Y50)/[ (1/2) × (FOV-FOV50) × P ] may be 9deg-1, 11deg-1, 13deg-1, 16deg-1, 18deg-1, 20deg-1, etc.

The present invention provides an optical system, which includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element.

The first lens element with negative bending force has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

the second lens has positive bending force, and the object side surface of the second lens is a plane;

a third lens having a positive refracting power;

a fourth lens having a negative bending force;

a fifth lens having a positive refracting power;

and a sixth lens having a positive refracting power.

By reasonably configuring the surface shapes and the bending forces of the first lens to the sixth lens, the optical system has a larger field angle, the optical system can meet the design requirement of clear imaging in a larger angle range, and the safety of the driving environment in a large angle range can be accurately judged in real time. Meanwhile, the object side surface of the second lens is a plane, so that the assembly eccentricity sensitivity of the second lens is reduced, the assembly yield is improved, and the production cost is reduced.

In one embodiment, the optical system satisfies the conditional expression: -4< f1/SAGs2< -3; wherein SAGs2 is the saggital height at the edge of the image side optically effective diameter of the first lens, and f1 is the effective focal length of the first lens. It can be understood that there may be obstacles or accidents at a long distance, and the driver needs to be warned, so increasing the resolution of the central view field is also a necessary means to reduce the driving risk. By setting the value of f1/SAGs2 between-4 and-3, the shape of the image side face of the first lens is reasonably designed, the pixel density distribution of different fields of view of the optical system is favorably optimized, the pixel resolution of the edge field of view is not influenced, the pixel density of the central field of view is improved, the purpose of high resolution of the central field of view is realized, and the safety of the driving environment far ahead is favorably and accurately judged in real time. It can be understood that when the value of f1/SAGs2 is lower than-4, the image side surface of the first lens is too curved, the processing difficulty of the lens is high, and the process production of the lens is not facilitated; when the value of f1/SAGs2 is higher than-3, the effective focal length of the first lens is larger, so that the bending force of the first lens is insufficient, and the expansion of the field angle range of the optical system is not facilitated. Specifically, the values of f1/SAGs2 may be-3.9, -3.8, -3.7, -3.5, -3.2, -3.0, etc.

In one embodiment, the optical system satisfies the conditional expression: 2< f2/f < 3.3; wherein f2 is the effective focal length of the second lens, and f is the effective focal length of the optical system. Through satisfying f2/f between 2 and 3.3, the second lens is positive lens, for the positive power of buckling of system provides, is favorable to contracting the light width, makes the light shrink that the high-angle light was absorb after first lens refraction, is favorable to proofreading the aberration that the high-angle light penetrated into first lens difference simultaneously to promote optical system's resolving power. It is understood that the value of f2/f is lower than 2 or higher than 3.3, which is not favorable for correcting the aberration of the optical system, thereby reducing the imaging quality. Specifically, the value of f2/f can be 2, 2.3, 2.5, 2.9, 3.3, etc.

In one embodiment, the optical system satisfies the conditional expression: 10< f45/(CT5-CT4) < 26; wherein f45 is a combined effective focal length of the fourth lens and the fifth lens, CT5 is an optical thickness of the fifth lens, and CT4 is an optical thickness of the fourth lens. By satisfying that the value of f45/(CT5-CT4) is between 10 and 26, the fifth lens with positive bending force and the fourth lens with negative bending force can be reasonably matched, so that the mutual correction of aberration is performed, and the minimum aberration contribution ratio of the fourth lens and the fifth lens to the optical system is favorably provided. It can be understood that when the value of f45/(CT5-CT4) is less than 10, the difference between the central thicknesses of the fourth lens and the fifth lens is too large, which is not beneficial to the gluing process, and in the environment with large temperature difference, the difference between the cold deformation and the hot deformation caused by the difference between the thicknesses is large, which is easy to generate phenomena such as glue crack or glue failure; when the value of f45/(CT5-CT4) is higher than 26, the effective focal length of the combination of the fourth lens element and the fifth lens element is too large, and the combined lens element is prone to generating a severe astigmatism phenomenon, which is not favorable for improving the imaging quality of the optical system. Specifically, f45/(CT5-CT4) can be 10, 13, 16, 20, 26, etc.

In one embodiment, the optical system satisfies the conditional expression: EDs9/SAGs9> 4.9; SAGs9 is the rise of the edge of the fourth lens image-side surface and the fifth lens object-side surface optical effective diameter, EDs9 is the optical effective diameter of the fourth lens image-side surface and the fifth lens object-side surface. By meeting the requirement that the value of EDs9/SAGs9 is higher than 4.9, the bending degree of the cemented surface of the combined lens is favorably controlled, the assembly eccentricity sensitivity of the combined lens is reduced, and the yield is favorably improved. It can be understood that when the value of EDs9/SAGs9 is less than 4.9, the gluing surface is too curved to facilitate the gluing process, and the risk of relative decentration between the two lenses increases; meanwhile, the assembly eccentricity sensitivity of the combined lens is increased, which is not beneficial to improving the yield. Specifically, the values of EDs9/SAGs9 may be 4.9, 5.2, 5.9, 6.2, 7, 9.2, etc.

In one embodiment, the optical system satisfies the conditional expression: 1.5<2 x Y/EPD < 2.0; wherein Y is half of the maximum image height of the imaging surface of the optical system, and EPD is the entrance pupil diameter of the optical system. By meeting the requirement that the value of 2-x-Y/EPD is between 1.5 and 2.0, the optical system meets the requirements of large image surface and high-quality imaging, and controls the diameter of the entrance pupil of the optical system at the same time, thereby ensuring the brightness of the imaging surface of the optical system to be improved. It can be understood that when the value of 2 × Y/EPD is higher than 2.0, the entrance pupil diameter is small, which causes insufficient brightness, and high-definition shooting cannot be satisfied; when the value of 2 × Y/EPD is less than 1.5, the size of the imaging plane of the optical system is too small to obtain enough object space information. Specifically, the value of 2 × Y/EPD may be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, etc.

In one embodiment, the optical system satisfies the conditional expression: 4.2< TTL/f < 5.3; wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane, and f is an effective focal length of the optical system. By meeting the TTL/f value between 4.2 and 5.3, the total length of the optical system is controlled while the optical system has a larger field angle range, so that the optical system is convenient to realize miniaturization. When TTL/f is higher than 5.3, the total length of the optical system is too long, which is not beneficial to miniaturization; when TTL/f is less than 4.2, the effective focal length of the optical system is too long, and the field angle range of the optical system is too small to obtain sufficient object space information. Specifically, the value of TTL/f can be 4.2, 4.3, 4.6, 4.9, 5.0, 5.1, 5.3, and the like.

The optical system in the existing forward-looking camera lens has low resolution, the presentation of long-distance details and the clear imaging in a large angle range cannot be simultaneously satisfied, and the details shot in a long distance cannot be accurately judged in real time to make early warning or obstacles in the large angle range cannot be avoided, so that the driving risk exists. The optical system provided by the embodiment of the invention has higher resolution ratio by reasonably configuring the surface shape and the bending force of each lens and meeting the condition formulas in each implementation mode, can simultaneously meet the requirements of clear imaging in a large angle range and presentation of long-distance details, is convenient for a driver to make accurate judgment and avoid accidents, and improves the yield in the aspect of lens production process on the basis.

First embodiment

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

the first lens element L1 with negative refractive power has an object-side surface S1 of the first lens element L1 being convex at a paraxial region and concave at a peripheral region; the image-side surface S2 of the first lens element L1 is concave at paraxial region and is flat at circumference;

the second lens L2 has positive bending force, the object-side surface S3 of the second lens L2 is a plane, and the image-side surface S4 is a convex surface;

the third lens element L3 has positive refractive power, and the object-side surface S5 and the image-side surface S6 of the third lens element L3 are convex and concave;

the fourth lens element L4 with negative refractive power has a convex object-side surface S7 and a concave image-side surface S8 of the fourth lens element L4;

the fifth lens element L5 has positive refractive power, and the object-side surface S8 and the image-side surface S9 of the fifth lens element L5 are convex.

The sixth lens element L6 has positive refractive power, and the object-side surface S10 and the image-side surface S11 of the sixth lens element L6 are concave and convex.

The first lens element L1 to the sixth lens element L6 are made of glass. Since the image-side surface of the fourth lens L4 is cemented with the object-side surface of the fifth lens, the surface S8 is both the image-side surface of the fourth lens L4 and the object-side surface of the fifth lens L5.

Further, the optical system includes a diaphragm ST0, an infrared filter IR, a cover glass L7, and an imaging surface IMG. A stop ST0 is provided on the object side surface S7 of the fourth lens L4 for controlling the amount of light entering. In other embodiments, the stop ST0 can also be disposed between two adjacent lenses, or on the object side and the image side of other lenses. The infrared filter IR is disposed on the image side of the sixth lens L6, and includes an object side surface S12 and an image side surface S13, and is configured to filter infrared light, so that the light incident on the imaging surface IMG is visible light with a wavelength of 380nm to 780 nm. The material of the infrared filter IR is glass, and a film can be coated on the glass. The protective glass L7 is disposed between the image side surface S13 and the image plane IMG of the infrared filter IR, and includes an object side surface S14 and an image side surface S15. The imaging plane IMG is an image plane of the optical system.

Table 1a shows a table of characteristics of the optical system of the present embodiment in which the reference wavelength of the refractive index and the abbe number is d-line 587.56nm, the reference wavelength of the focal length is 546nm, and the units of the Y radius, the thickness, and the focal length are all millimeters (mm).

TABLE 1a

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

In the present embodiment, the object-side surface S1 and the image-side surface S2 of the first lens L1, and the object-side surface S10 and the image-side surface S11 of the sixth lens L6 are aspheric surfaces, and the surface shape x of each aspheric lens can be defined by, but is not limited to, the following aspheric formula:

wherein x is the maximum rise of the distance from the vertex of the aspheric surface when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius R of Y in table 1a above); k is a conic coefficient; ai is the correction coefficient of the i-th order of the aspherical surface.

Table 1b shows the high-order term coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each aspherical mirror surface in the first embodiment.

TABLE 1b

Number of noodles	S1	S2	S10	S11
					K	-3.19E-01	-7.39E-01	-7.48E-01	5.23E+00
A4	-1.95E-03	-7.69E-03	-7.27E-03	-6.76E-03
					A6	-4.34E-05	-5.50E-04	-1.52E-04	-9.61E-04
A8	-3.49E-06	9.84E-05	1.44E-04	1.16E-03
					A10	4.17E-07	-8.96E-06	-2.08E-04	-5.37E-04
A12	-1.50E-08	6.44E-07	1.21E-04	1.50E-04
					A14	2.44E-10	-5.09E-08	-4.40E-05	-2.62E-05
A16	-1.52E-12	3.34E-09	9.56E-06	2.81E-06
					A18	0.00E+00	-1.29E-10	-1.12E-06	-1.68E-07
A20	0.00E+00	2.06E-12	5.41E-08	0.00E+00

Fig. 1b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the first embodiment. The reference wavelength of the light rays of the astigmatism curve and the distortion curve is 546nm, wherein, the longitudinal spherical aberration curve represents the deviation of the convergent focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves are meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 1b, the optical system according to the first embodiment can achieve good imaging quality.

Second embodiment

Referring to fig. 2a and fig. 2b, the optical system of the present embodiment, in order from an object side to an image side along an optical axis direction, includes:

Table 2a shows a table of characteristics of the optical system of the present embodiment in which the reference wavelength of the refractive index and the abbe number is d-line 587.56nm, the reference wavelength of the focal length is 546nm, and the units of the Y radius, the thickness, and the focal length are all millimeters (mm).

TABLE 2a

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

TABLE 2b

Number of noodles	S1	S2	S10	S11
					K	-3.29E-01	-7.39E-01	1.86E+00	5.27E+00
A4	-1.90E-03	-7.58E-03	-7.40E-03	-7.62E-03
					A6	-5.07E-05	-7.27E-04	-4.49E-04	-3.21E-04
A8	-3.43E-06	1.63E-04	5.39E-04	7.55E-04
					A10	4.60E-07	-2.09E-05	-5.76E-04	-3.86E-04
A12	-1.82E-08	1.98E-06	3.37E-04	1.14E-04
					A14	3.38E-10	-1.41E-07	-1.24E-04	-2.10E-05
A16	-2.55E-12	6.83E-09	2.72E-05	2.34E-06
					A18	0.00E+00	-1.94E-10	-3.23E-06	-1.45E-07
A20	0.00E+00	2.39E-12	1.59E-07	0.00E+00

Fig. 2b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the second embodiment. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546 nm. As can be seen from fig. 2b, the optical system according to the second embodiment can achieve good imaging quality.

Third embodiment

Referring to fig. 3a and 3b, the optical system of the present embodiment, in order from an object side to an image side along an optical axis direction, includes:

the third lens element L3 has a positive refractive power, and the object-side surface S5 and the image-side surface S6 of the third lens element L3 are convex and flat;

Table 3a shows a table of characteristics of the optical system of the present embodiment in which the reference wavelength of the refractive index and the abbe number is d-line 587.56nm, the reference wavelength of the focal length is 546nm, and the units of the Y radius, the thickness, and the focal length are all millimeters (mm).

TABLE 3a

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

TABLE 3b

Number of noodles	S1	S2	S10	S11
					K	-3.20E-01	-7.38E-01	3.26E+00	5.17E+00
A4	-1.91E-03	-7.56E-03	-7.42E-03	-7.78E-03
					A6	-5.04E-05	-7.24E-04	-4.90E-04	-3.11E-04
A8	-3.42E-06	1.62E-04	5.45E-04	7.55E-04
					A10	4.60E-07	-2.09E-05	-5.77E-04	-3.86E-04
A12	-1.82E-08	1.98E-06	3.37E-04	1.14E-04
					A14	3.37E-10	-1.41E-07	-1.24E-04	-2.10E-05
A16	-2.55E-12	6.83E-09	2.72E-05	2.34E-06
					A18	0.00E+00	-1.94E-10	-3.23E-06	-1.45E-07
A20	0.00E+00	2.39E-12	1.59E-07	0.00E+00

Fig. 3b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the third embodiment. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546 nm. As can be seen from fig. 3b, the optical system according to the third embodiment can achieve good imaging quality.

Fourth embodiment

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

the third lens element L3 with positive refractive power has a convex object-side surface S5 and a convex image-side surface S6 of the third lens element L3;

the fourth lens element L4 has negative refractive power, and the object-side surface S7 and the image-side surface S8 of the fourth lens element L4 are concave;

Table 4a shows a table of characteristics of the optical system of the present embodiment in which the reference wavelength of the refractive index and the abbe number is d-line 587.56nm, the reference wavelength of the focal length is 546nm, and the units of the Y radius, the thickness, and the focal length are all millimeters (mm).

TABLE 4a

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

TABLE 4b

Fig. 4b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the fourth embodiment. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546 nm. As can be seen from fig. 4b, the optical system according to the fourth embodiment can achieve good imaging quality.

Fifth embodiment

Referring to fig. 5a and 5b, the optical system of the present embodiment, in order from an object side to an image side along an optical axis direction, includes:

Table 5a shows a table of characteristics of the optical system of the present embodiment in which the reference wavelength of the refractive index and the abbe number is d-line 587.56nm, the reference wavelength of the focal length is 546nm, and the units of the Y radius, the thickness, and the focal length are all millimeters (mm).

TABLE 5a

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

TABLE 5b

Number of noodles	S1	S2	S10	S11
					K	-3.62E-01	-7.36E-01	4.69E+00	5.20E+00
A4	-2.01E-03	-7.84E-03	-8.08E-03	-7.06E-03
					A6	-6.50E-05	-6.34E-04	1.17E-03	-9.58E-04
A8	-1.61E-06	1.41E-04	-1.88E-03	1.08E-03
					A10	3.16E-07	-1.81E-05	1.57E-03	-4.85E-04
A12	-1.05E-08	1.86E-06	-8.54E-04	1.30E-04
					A14	1.16E-10	-1.55E-07	2.87E-04	-2.18E-05
A16	0.00E+00	8.87E-09	-5.82E-05	2.24E-06
					A18	0.00E+00	-2.97E-10	6.52E-06	-1.29E-07
A20	0.00E+00	4.29E-12	-3.11E-07	0.00E+00

Fig. 5b shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical system of the fifth embodiment. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546 nm. As can be seen from fig. 5b, the optical system according to the fifth embodiment can achieve good image quality.

Referring to table 6, table 6 shows f1/SAGs2, f2/f, EDs9/SAGs9, f45/(CT5-CT4), Y10/(FOV 10P), (Y50-Y10)/[ (1/2)/(FOV 50-FOV 10): P) in the optical systems of the first to sixth embodiments]、(Y-Y50)/[(1/2)*(FOV-FOV50)*P]2 x Y/EPD and TTL/f. Wherein Y10/(FOV 10P), (Y50-Y10)/[ (1/2) × (FOV50-FOV10) × P]And (Y-Y50)/[ (1/2) (FOV-FOV50) × P]All units of are deg^-1。

TABLE 6

	f1/SAGs2	f2/f	f45/(CT5-CT4)
				First embodiment	-3.73	2.38	11.36
Second embodiment	-3.75	2.21	13.61
				Third embodiment	-3.58	2.16	16.08
Fourth embodiment	-3.36	2.05	20.78
				Fifth embodiment	-3.40	2.10	24.59
	EDs9/SAGs9	Y10/(FOV10*P)	(Y50-Y10)/[(1/2)(FOV50-FOV10)P]
				First embodiment	5.33	30	24
Second embodiment	5.35	30	24
				Third embodiment	5.30	30	24
Fourth embodiment	5.32	30	24
				Fifth embodiment	5.26	30	24
	(Y-Y50)/[(1/2)(FOV-FOV50)P]	2*Y/EPD	TTL/f
				First embodiment	13	1.77	4.60
Second embodiment	13	1.76	4.57
				Third embodiment	13	1.76	4.59
Fourth embodiment	13	1.77	4.59
				Fifth embodiment	13	1.77	4.60

As can be seen from table 6, the optical systems of the first to fifth embodiments all satisfy the following conditional expressions: -4<f1/SAGs2<-3、2<f2/f<3.3、10＜f45/(CT5-CT4)＜26、EDs9/SAGs9>4.9、Y10/(FOV10*P)≥26deg^-1、20deg^-1≤(Y50-Y10)/[(1/2)*(FOV50-FOV10)*P]≤26deg^-1、9deg^-1≤(Y-Y50)/[(1/2)*(FOV-FOV50)*P]≤20deg^-1、1.5<2*Y/EPD<2.0、4.2<TTL/f<5.3。

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

Claims

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

a first lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

a third lens having a positive refracting power;

a fourth lens having a negative bending force;

a fifth lens having a positive refracting power;

and a sixth lens having a positive refracting power.

2. The optical system as claimed in claim 1, wherein the image-side surface of the fourth lens element is concave, the object-side surface and the image-side surface of the fifth lens element are convex, and the image-side surface of the fourth lens element is cemented with the object-side surface of the fifth lens element to form a combined lens.

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

-4<f1/SAGs2<-3；

wherein SAGs2 is the saggital height at the edge of the image side optically effective diameter of the first lens, and f1 is the effective focal length of the first lens.

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

2<f2/f<3.3；

wherein f2 is the effective focal length of the second lens, and f is the effective focal length of the optical system.

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

10<f45/(CT5-CT4)<26；

wherein f45 is a combined effective focal length of the fourth lens and the fifth lens, CT5 is an optical thickness of the fifth lens, and CT4 is an optical thickness of the fourth lens.

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

EDs9/SAGs9>4.9；

SAGs9 is the rise of the edge of the effective optical diameter of the fourth lens image-side surface and the fifth lens object-side surface, EDs9 is the effective optical diameter of the fourth lens image-side surface and the fifth lens object-side surface.

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

1.5<2*Y/EPD<2.0；

wherein Y is half of the maximum image height of the optical system, and EPD is the entrance pupil diameter of the optical system.

8. The optical system according to claim 1, wherein the optical system satisfies a conditional expression: 4.2< TTL/f < 5.3;

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

9. An image pickup module comprising a lens barrel, a photosensitive element, and the optical system according to any one of claims 1 to 8, wherein the first to sixth lenses of the optical system are mounted in the lens barrel, and the photosensitive element is disposed on an image side of the optical system.

10. The camera module of claim 9, wherein the optical system satisfies the conditional expression:

Y10/(FOV10*P)≥26deg-1；

wherein Y10 is half of the image height corresponding to the 10 ° field angle of the optical system, FOV10 is the 10 ° field angle of the optical system, and P is the size of the unit pixel on the photosensitive element.

11. The camera module of claim 9, wherein the optical system satisfies the conditional expression:

20deg-1≤(Y50-Y10)/[(1/2)*(FOV50-FOV10)*P]≤26deg-1；

wherein Y50 is a half of the image height corresponding to the 50 ° field angle of the optical system, Y10 is a half of the image height corresponding to the 10 ° field angle of the optical system, FOV50 is the 50 ° field angle of the optical system, FOV10 is the 10 ° field angle of the optical system, and P is the size of the unit pixel on the photosensitive element.

12. The camera module of claim 9, wherein the optical system satisfies the conditional expression:

9deg-1≤(Y-Y50)/[(1/2)*(FOV-FOV50)*P]≤20deg-1；

wherein, Y is a half of the maximum image height of the imaging surface of the optical system, Y50 is a half of the image height corresponding to the 50 ° field angle of the optical system, FOV is the maximum field angle of the optical system, FOV50 is the 50 ° field angle of the optical system, and P is the size of the unit pixel on the photosensitive element.

13. An electronic device comprising a housing and the camera module of any one of claims 9-12, wherein the camera module is disposed within the housing.