CN115933133A

CN115933133A - Optical system, camera module and terminal equipment

Info

Publication number: CN115933133A
Application number: CN202211295408.7A
Authority: CN
Inventors: 何世峰
Original assignee: Shanghai Ofilm Intelligent Vehicle Co ltd
Current assignee: Shanghai Ofilm Intelligent Vehicle Co ltd
Priority date: 2022-10-21
Filing date: 2022-10-21
Publication date: 2023-04-07

Abstract

The invention discloses an optical system, a camera module and terminal equipment. The optical system includes: the image side surface of the first lens element with negative refractive power is concave; a second lens element with negative refractive power having a concave image-side surface; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fifth lens element with positive refractive power having a concave object-side surface and a convex image-side surface; a sixth lens element with positive refractive power having a convex object-side surface; the optical system satisfies the relationship: 0.6< -Imgh/f <0.9. According to the optical system of the embodiment of the present invention, a miniaturized design can be realized while increasing the angle of view of the optical system.

Description

Optical system, camera module and terminal equipment

Technical Field

The invention relates to the technical field of photographic imaging, in particular to an optical system, a camera module and terminal equipment.

Background

In the prior art, the rearview mirrors at two sides of the automobile cannot completely collect all information around the automobile body due to a small visual field range, so that a plurality of blind areas exist in the driving process of the automobile, and traffic accidents are easily caused. Therefore, with the development of the vehicle-mounted industry, the vehicle-mounted camera is gradually applied to the rearview mirror of the vehicle, all information around the vehicle body is acquired through the vehicle-mounted camera, the problem of blind areas existing in the traditional rearview mirror can be solved to a certain extent, a clear view field can be provided for the driving of a driver, and the possibility of traffic accidents is further reduced. Therefore, how to improve the field of view of the vehicle-mounted camera and ensure the imaging quality becomes a research and development focus of applying the vehicle-mounted camera to the rearview mirror.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. In view of this, a first aspect of the present application proposes an optical system that can achieve a compact design while increasing the angle of view of the optical system.

The invention also provides a camera module in a second aspect.

The third aspect of the present invention further provides a terminal device.

The optical system according to the embodiment of the first aspect of the present application, wherein the six lens elements with refractive power sequentially include, from an object side to an image side along an optical axis: a first lens element with negative refractive power having a concave image-side surface at a paraxial region; a second lens element with negative refractive power having a concave image-side surface at a paraxial region; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element with positive refractive power having a convex object-side surface at paraxial region and a convex image-side surface at paraxial region; a fifth lens element with positive refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a sixth lens element with positive refractive power having a convex object-side surface at a paraxial region.

In the optical system, the negative refractive power of the first lens element is enhanced by the negative refractive power of the first lens element and the concave surface design of the image-side surface at the paraxial region, so that large-angle light can be better incident on the optical system, and the field angle range of the optical system is expanded; the second lens with negative refractive power and the concave surface design of the image side surface at the paraxial region can smoothly transmit incident light rays converged by the first lens and correct primary aberration brought by the first lens when the incident light rays are converged; through the third lens with positive refractive power, and the surface type design that the object side surface is a convex surface and the image side surface is a convex surface, the light rays of the central field and the marginal field can be converged, so that the total length of the optical system is compressed, and the aberration which is difficult to correct and is brought by the object side lens (namely the first lens and the second lens) is eliminated; through the fourth lens element with positive refractive power, the light can be further converged by matching with the surface design that the object side surface and the image side surface are convex at the paraxial region, and the aberration can be further counteracted by matching with the third lens element with positive refractive power, so that the field curvature astigmatism of the optical system can be reduced; through the fifth lens element with positive refractive power, the concave-convex design of the object side surface and the image side surface at the paraxial region is matched, so that smooth transmission of light rays is facilitated, aberration which is difficult to correct and is caused by a front lens group (namely, the third lens element and the fourth lens element) when incident light rays are converged can be balanced, and the correction pressure of the sixth lens element is reduced; through the sixth lens element with positive refractive power, and the convex surface design of the object side surface at the paraxial region, the light can be effectively converged, the incident angle of the incident light on the imaging surface is reduced, the occurrence of chromatic aberration is reduced, and the imaging quality of the optical system is improved.

In one embodiment, 0.6-inch Impgh/f <0.9; imgh is half of the image height corresponding to the maximum field angle of the optical system, and f is the effective focal length of the optical system. When the condition is met, the ratio of the half-image height to the effective focal length of the optical system can be reasonably configured, so that the optical system has large depth of field and meets the requirement of high imaging definition; meanwhile, the method is beneficial to expanding the field angle of the optical system and realizing large-range shooting. When the upper limit of the conditional expression is exceeded, the focal length of the optical system is too short, the depth of field is too deep, the shooting definition of a distant scene is not enough, and the imaging effect is influenced; if the lower limit of the above conditional expression is lower, the focal length of the optical system is too long, which is disadvantageous to the wide angle of the optical system and makes it difficult to photograph a large-range scene.

In one embodiment, 7-ttl/f <10; 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, i.e., a total optical length, and f is an effective focal length of the optical system. The relation is satisfied, the ratio of the total optical length to the effective focal length of the optical system is reasonably controlled, and the miniaturization of the optical system is facilitated.

In one embodiment, 0.1 < f123/f456 < 3; f123 is a combined effective focal length of the first lens, the second lens and the third lens, f456 is a combined effective focal length of the fourth lens, the fifth lens and the sixth lens, and the diaphragm is located between the third lens and the fourth lens. Satisfying above-mentioned relational expression, being favorable to rationally controlling the focus ratio before and after the diaphragm, realizing the effect of this optical system's big light ring, big target surface, simultaneously, light can be full of whole diaphragm, is favorable to the aberration balance before and after the diaphragm.

In one embodiment, 8 < | R1/f | < 16; r1 is a curvature radius of an object side surface of the first lens at an optical axis, and f is an effective focal length of the optical system. The method can effectively control the surface curvature of the object side surface of the first lens and realize the effective control of the refractive power of the first lens, thereby effectively enlarging the field angle, collecting light rays with a large field of view and realizing a large viewing angle.

In one embodiment, 2< | f2/f | <5; f3/f is more than 1 and less than 5; f5/f is more than 5 and less than 10; f2 is the effective focal length of the second lens; f3 is the effective focal length of the third lens; f5 is an effective focal length of the fifth lens, and f is an effective focal length of the optical system. The refractive power distribution of the second lens, the third lens and the fifth lens can be effectively controlled, the deflection intensity of light rays in light path transmission is balanced, the value satisfies 2< | f2/f | <5, light rays can be smoothly transited, the tolerance sensitivity of a system is reduced, the value satisfies 5 < f5/f <10, the angle of the main light rays incident to the photosensitive chip is not too large, the color cast of a picture is avoided, the value satisfies 1< f3/f <5, the third lens has strong positive refractive power, and the miniaturization of an optical system is favorably realized.

In one embodiment, 2.2mm-woven fabric f/FNO <3mm; the FNO is an f-number of the optical system. The entrance pupil diameter of the optical system can be effectively regulated and controlled by satisfying the relational expression, so that the thickness of the optical system in the direction perpendicular to the optical axis is effectively limited, the miniaturization of the optical system is facilitated, and the space of the terminal equipment is saved.

In one embodiment, 2-n & lt 45/SD41<5; f45 is the combined effective focal length of the fourth lens and the fifth lens, and SD41 is half of the maximum effective aperture of the object side surface of the fourth lens. When the conditional expressions are satisfied, the size of the effective aperture of the object side surface of the fourth lens is favorably controlled, so that the generation of aberrations such as edge aberration and field curvature is further inhibited, and the imaging quality of the optical system is favorably improved. When the maximum effective aperture of the object side surface of the fourth lens exceeds the upper limit of the conditional expression, the maximum effective aperture is too small, the aberration correction of the edge field is difficult, the edge relative illumination is quickly reduced, and the imaging quality of the optical system is further reduced; below the lower limit of the conditional expression, the refractive power of the fourth lens element and the fifth lens element is too strong, which easily causes the field curvature of the optical system to increase, and the image is not clear.

In one embodiment, 1.3-woven ET2/CT2<1.6; ET2 is a distance from the maximum effective light-transmitting aperture of the object side surface of the second lens to the maximum effective light-transmitting aperture of the image side surface in the optical axis direction; CT2 is the thickness of the second lens on the optical axis. The thickness ratio of the second lens can be effectively controlled, the processing and forming of the second lens are facilitated, the assembling difficulty of the optical system is reduced, and the field curvature of the optical system can be effectively corrected through the second lens. If the thickness of the central part of the second lens is less than the lower limit of the conditional expression, the thickness of the central part of the second lens is too large relative to the thickness of the edge of the second lens, which is not beneficial to shortening the optical total length of the optical system; exceeding the upper limit of the above conditional expression, the central thickness of the second lens is too small relative to the edge thickness, and the system is too sensitive to the central thickness of the second lens, so that the processing of the second lens is difficult to meet the required tolerance requirement, thereby reducing the assembly yield of the optical system.

In one embodiment, FNO <1.8; FNO is the f-number of the optical system. Satisfying above-mentioned relational expression, through the reasonable restriction to optical system's f-number, be favorable to providing sufficient light volume for making a video recording, the picture is bright when guaranteeing to shoot, and the theme background blurring is big, reaches outstanding main part and shoots the effect. Meanwhile, the shooting can be carried out under the condition that the light brightness is normal or worse, and the purpose of shooting high-quality object space scenes such as night scenes, starry sky scenes and the like with low brightness is achieved.

The image pickup module according to the embodiment of the second aspect of the present application includes a photosensitive chip and the optical system described in any one of the above, where the photosensitive chip is disposed on an image side of the optical system. Through adopting above-mentioned optical system, the module of making a video recording can possess good formation of image quality when keeping wide-angle design.

According to the third aspect of the present application, the terminal device includes a fixing member and the camera module described above, and the camera module is disposed on the fixing member. The camera module can provide good camera quality for the terminal equipment, and simultaneously keeps a larger field angle, so that the obstruction to the wide-angle design of the terminal equipment can be reduced.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1 is a schematic structural diagram of an optical system according to a first embodiment of the present application;

FIG. 2 includes a field curvature diagram of the optical system in the first embodiment;

FIG. 3 includes a distortion diagram of the optical system in the first embodiment;

FIG. 4 includes a chromatic aberration diagram of the optical system in the first embodiment;

fig. 5 is a schematic structural diagram of an optical system according to a second embodiment of the present application;

FIG. 6 includes a field curvature diagram of the optical system in the second embodiment;

FIG. 7 includes a distortion diagram of the optical system in the second embodiment;

FIG. 8 includes a chromatic aberration diagram of the optical system in the second embodiment;

fig. 9 is a schematic structural diagram of an optical system according to a third embodiment of the present application;

FIG. 10 includes a field curvature diagram of the optical system in the third embodiment;

fig. 11 includes a distortion diagram of the optical system in the third embodiment;

FIG. 12 includes a chromatic aberration diagram of the optical system in the third embodiment;

fig. 13 is a schematic view of a camera module according to an embodiment of the present application;

fig. 14 is a schematic diagram of a terminal device according to an embodiment of the present application.

Reference numerals:

the optical system 10, the camera module 20,

the optical axis 101, the photosensitive chip 210, the stop STO,

first lens L1: the object side S1, like the side S2,

second lens L2: the object side S3, like the side S4,

third lens L3: the object side S5, like the side S6,

fourth lens L4: the object side S7, like the side S8,

fifth lens L5: the object side S9, like the side S10,

sixth lens L6: the object side S11, the image side S12,

the optical filter 110: the object side S13, the image side S14,

the image-forming surface S15 is formed,

and a terminal device 30.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

An optical system 10 according to one embodiment of the present invention will be described below with reference to the drawings.

Referring to fig. 1, an optical system 10 with a six-lens design is provided, wherein the optical system 10 includes, in order from an object side to an image side along an optical axis 101, a first lens element L1 with negative refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, and a sixth lens element L6 with positive refractive power. The lenses in the optical system 10 should be coaxially arranged, and each lens can be installed in the lens barrel and cooperate with the photosensitive chip to form a camera module.

The first lens L1 has an object-side surface S1 and an image-side surface S2, the second lens L2 has an object-side surface S3 and an image-side surface S4, the third lens L3 has an object-side surface S5 and an image-side surface S6, the fourth lens L4 has an object-side surface S7 and an image-side surface S8, the fifth lens L5 has an object-side surface S9 and an image-side surface S10, and the sixth lens L6 has an object-side surface S11 and an image-side surface S12. Meanwhile, the optical system 10 further has an imaging surface S15, the imaging surface S15 is located on the image side of the sixth lens element L6, and light rays emitted from an on-axis object point at a corresponding object distance can be imaged on the imaging surface S15 after being adjusted by each lens element of the optical system 10.

Generally, the imaging surface S15 of the optical system 10 coincides with the photosensitive surface of the photosensitive chip. It should be noted that in some embodiments, the optical system 10 may match a photosensitive chip having a rectangular photosensitive surface, and the imaging surface S15 of the optical system 10 coincides with the rectangular photosensitive surface of the photosensitive chip. At this time, the effective pixel area on the imaging surface S15 of the optical system 10 has a horizontal direction, a vertical direction, and a diagonal direction, and the maximum field angle of the optical system 10 in the present application may be understood as the maximum field angle of the optical system 10 in the diagonal direction, and ImgH may be understood as half the length of the effective pixel area on the imaging surface S15 of the optical system 10 in the diagonal direction. In the embodiment of the present application, the image-side surface S2 of the first lens L1 is concave at the paraxial region 101; the image-side surface S4 of the second lens element L2 is concave at the paraxial region 101; the object-side surface S5 of the third lens element L3 is convex at the paraxial region 101, and the image-side surface S6 is convex at the paraxial region 101; the object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 101, and the image-side surface S8 is convex at the paraxial region 101; the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 101, and the image-side surface S10 is convex at the paraxial region 101; the object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 101. When describing that the lens surface has a certain profile at the paraxial region 101, that is, the lens surface has such a profile in the vicinity of the paraxial region 101.

In the optical system 10, the negative refractive power of the first lens element L1 is enhanced by the negative refractive power of the first lens element L1 and the concave surface design of the image-side surface S2 at the position near the optical axis 101, so that the large-angle light can be better incident on the optical system 10, and the field angle range of the optical system 10 is expanded; by the concave design of the second lens element L2 with negative refractive power and the image-side surface S4 at the paraxial region 101, the incident light converged by the first lens element L1 can be smoothly transmitted, and the primary aberration caused by the incident light converged by the first lens element L1 can be corrected; through the third lens element L3 with positive refractive power, with the design of a convex object-side surface S5 and a convex image-side surface S6, the light rays of the central and peripheral fields can be converged, thereby compressing the total length of the optical system 10 and eliminating the aberration caused by the object-side lens elements (i.e., the first lens element L1 and the second lens element L2) that is difficult to correct; through the positive refractive power of the fourth lens element L4, the object-side surface S7 and the image-side surface S8 are both convex at the paraxial region 101, so as to further converge light, and through the positive refractive power of the third lens element L3, the aberration is further cancelled, thereby reducing the field curvature astigmatism of the optical system 10; through the fifth lens element L5 with positive refractive power, the concave-convex design of the object-side surface S9 and the image-side surface S10 at the paraxial region 101 is favorable for smooth light transmission, and the aberration that is hard to correct and is caused by the front lens group (i.e., the third lens element L3 and the fourth lens element L4) when converging incident light can be balanced, so that the correction pressure of the sixth lens element is reduced; through the sixth lens element L6 with positive refractive power, the convex surface design of the object-side surface S11 at the paraxial region 101 can effectively converge light, reduce the incident angle of incident light on the image plane, reduce the occurrence of chromatic aberration, and improve the imaging quality of the optical system 10.

In the examples of the present application, 0.6 were woven to imgh/f <0.9; imgh is half the image height corresponding to the maximum field angle of the optical system 10, and f is the effective focal length of the optical system 10. The relation is satisfied, the ratio of the half-image height to the effective focal length of the optical system 10 can be reasonably configured, and the optical system 10 is favorable for satisfying the requirement of high imaging definition while having large depth of field; meanwhile, the field angle of the optical system 10 can be enlarged, and large-range shooting can be realized. If Imgh/f is more than or equal to 0.9, the focal length of the optical system 10 is too short, the depth of field is too deep, the shooting definition of a distant scene is not enough, and the imaging effect is influenced; if Imgh/f is less than or equal to 0.6, the focal length of the optical system 10 is too long, which is not favorable for the wide-angle of the optical system 10 and makes it difficult to photograph a large-range scene.

Furthermore, in some embodiments, the optical system 10 also satisfies at least one of the following relationships, and can have a corresponding technical effect when either relationship is satisfied:

7-woven TTL/f <10; TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane S15 of the optical system 10 on the optical axis 101, i.e. the total optical length, and f is an effective focal length of the optical system 10. Satisfying the above relation, the ratio of the total optical length to the effective focal length of the optical system 10 is reasonably controlled, which is beneficial to realizing miniaturization of the optical system 10. If TTL/f is less than or equal to 7, the optical system is too short, which may increase the sensitivity of the system and is not favorable for the light to converge on the imaging surface S15, and if TTL/f is greater than or equal to 10, the optical system 10 is too long, which may cause the angle of the chief ray incident on the imaging surface S15 to be too large and the marginal ray to be unable to be incident on the imaging surface S15, which may cause the imaging information to be incomplete.

F123/f456 is more than 0.1 and less than 3; f123 is a combined effective focal length of the first lens L1, the second lens L2, and the third lens L3, f456 is a combined effective focal length of the fourth lens L4, the fifth lens L5, and the sixth lens L6, and the stop STO is located between the third lens L3 and the fourth lens L4. Satisfying above-mentioned relational expression, through focus ratio around the reasonable control diaphragm STO, be favorable to optical system 10 to realize the effect of big light ring, big target surface for light can be full of whole diaphragm STO, is favorable to the aberration balance around the diaphragm.

8 < | R1/f | < 16; r1 is a curvature radius of the object-side surface S1 of the first lens L1 at the light extraction position, and f is an effective focal length of the optical system 10. The relation is satisfied, the surface curvature of the object side surface S1 of the first lens L1 can be effectively controlled, and the effective control of the refractive power of the first lens L1 is realized, so that the field angle can be effectively enlarged, light rays with a large field of view can be collected, and a large viewing angle can be realized.

2< | f2/f | <5; f2 is the effective focal length of the second lens L2, satisfying the above relation, and is beneficial to smooth transition of light and reducing tolerance sensitivity of the optical system 10.

F3/f is more than 1 and less than 5; f3 is the effective focal length of the third lens element L3, and satisfies the above relation, and the third lens element L3 has a strong positive refractive power, which is beneficial to realizing miniaturization of the optical system 10. When f3/f is less than or equal to 1, the total length of the system is too large, resulting in an increase in assembly sensitivity. When f3/f is larger than or equal to 5, the refractive power of the third lens element L3 is too weak, which tends to increase stray light in the system and affect the imaging quality.

F5/f is more than 5 and less than 10; f5 is the effective focal length of the fifth lens element L5, and satisfies the above relation, and the angle of the chief ray incident on the photosensitive chip 210 is not too large, thereby avoiding color cast.

2.2mm-woven fabric f/FNO <3mm; FNO is the f-number of the optical system 10. Satisfying the above relation, the entrance pupil diameter of the optical system 10 can be effectively adjusted and controlled, thereby effectively limiting the thickness of the optical system 10 in the direction perpendicular to the optical axis, facilitating the miniaturization of the optical system 10 and saving the space of the terminal device.

2-sj 45/SD41<5; f45 is the combined effective focal length of the fourth lens L4 and the fifth lens L5, and SD41 is half of the maximum effective aperture of the object-side surface S7 of the fourth lens L4. When the above conditional expressions are satisfied, it is beneficial to control the size of the effective aperture of the object-side surface S7 of the fourth lens L4, so as to suppress the generation of aberrations such as edge aberration and field curvature, and to improve the imaging quality of the optical system 10. When the maximum effective aperture of the object-side surface S7 of the fourth lens L4 exceeds the upper limit of the conditional expression, the maximum effective aperture is too small, the aberration of the edge field is difficult to correct, and the relative illumination of the edge is rapidly reduced, thereby reducing the imaging quality of the optical system 10; below the lower limit of the conditional expression, the refractive power of the fourth lens element L4 and the fifth lens element L5 is too strong, which tends to increase the curvature of field of the optical system 10, resulting in unclear imaging.

1.3-straw ET2/CT2<1.6; ET2 is the distance from the maximum effective clear aperture of the object-side surface S3 to the maximum effective clear aperture of the image-side surface S4 of the second lens L2 in the optical axis direction, i.e., the edge thickness of the second lens L2; CT2 is the thickness of the second lens L2 on the optical axis 101, and the center thickness of the second lens L2. Satisfying the above relation, the thickness ratio of the second lens L2 can be effectively controlled, which is beneficial to the processing and molding of the second lens L2, reduces the difficulty of assembling the optical system 10, and can also effectively correct the curvature of field of the optical system 10 through the second lens L2. If the thickness is lower than the lower limit of the above conditional expression, the central thickness of the second lens L2 is too large relative to the edge thickness, which is not favorable for shortening the total optical length of the optical system 10; exceeding the upper limit of the above conditional expression, the central thickness of the second lens L2 is too small compared to the edge thickness, and the optical system 10 is too sensitive to the central thickness of the second lens L2, so that the processing of the second lens L2 is difficult to meet the required tolerance requirement, thereby reducing the assembly yield of the optical system 10.

FNO <1.8; FNO is the f-number of the optical system 10. Satisfying the above relation, through the reasonable limitation to the f-number of the optical system 10, it is beneficial to provide enough light input amount for shooting, ensuring that the picture is brighter and the background of the subject is blurred greatly when shooting, so as to achieve the effect of highlighting the subject shooting. Meanwhile, the shooting can be carried out under the condition that the light brightness is normal or worse, and the purpose of shooting high-quality object space scenes such as night scenes, starry sky scenes and the like with low brightness is achieved.

The numerical reference wavelength of the effective focal length in the above relational conditions was 587.6nm. And the above relationship conditions and the technical effects thereof are directed to the optical system 10 having the above lens design. When the lens design (the number of lenses, the refractive power arrangement, the surface type arrangement, etc.) of the optical system 10 cannot be ensured, it is difficult to ensure that the optical system 10 can still have the corresponding technical effect when the relational expressions are satisfied, and even the imaging performance may be significantly reduced.

In some embodiments, at least one lens in the optical system 10 may also have a spherical surface shape, and the design of the spherical surface shape may reduce the difficulty and cost of manufacturing the lens. In some embodiments, the design of each lens surface in the optical system 10 may be configured by aspheric and spherical surface types for consideration of manufacturing cost, manufacturing difficulty, imaging quality, assembly difficulty, etc. The aspheric design can help the optical system 10 to eliminate aberration more effectively and improve the imaging quality

It should also be noted that when a lens surface is aspheric, there may be inflection points for that lens surface where the surface will change in type radially, e.g., one lens surface is convex near the optical axis 101 and concave near the maximum effective aperture.

In some embodiments, at least one lens of the optical system 10 is made of Glass (GL). In some embodiments, lenses of different materials may be disposed in the optical system 10, that is, a design combining a glass lens and a plastic lens may be adopted, but the specific configuration relationship may be determined according to practical requirements and is not exhaustive here. The lens made of plastic can reduce the production cost of the optical system 10, and the lens made of glass can endure higher or lower temperature and has excellent optical effect and better stability.

In some embodiments, the optical system 10 further includes a stop STO, which may be an aperture stop or a field stop, where the aperture stop is used to control the light incident amount and the depth of field of the optical system 10, and can also achieve good interception of the non-effective light to improve the imaging quality of the optical system 10, and the stop STO may be disposed between the image-side surface S6 of the third lens L3 and the object-side surface S7 of the fourth lens L4. It is understood that, in other embodiments, the stop STO may also be disposed between two adjacent lenses, for example, between the second lens L2 and the third lens L3, and the setting is adjusted according to practical situations, which is not limited in this embodiment. The aperture stop may also be formed by a holder that holds the lens.

The optical system 10 of the present application is illustrated by the following more specific examples:

first embodiment

Referring to fig. 1, in the first embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101: the first lens element L1 with negative refractive power, the second lens element L2 with negative refractive power, the third lens element L3 with positive refractive power, the stop STO, the fourth lens element L4 with positive refractive power, the fifth lens element L5 with positive refractive power, and the sixth lens element L6 with positive refractive power. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S1 of the first lens element L1 is concave at the paraxial region 101, and the image-side surface S2 is concave at the paraxial region 101.

The object-side surface S3 of the second lens element L2 is convex at the paraxial region 101, and the image-side surface S4 is concave at the paraxial region 101.

The object-side surface S5 of the third lens element L3 is convex at the paraxial region 101, and the image-side surface S6 is convex at the paraxial region 101.

The object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 101, and the image-side surface S8 is convex at the paraxial region 101.

The object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 101, and the image-side surface S10 is convex at the paraxial region 101.

The object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 101, and the image-side surface S12 is concave at the paraxial region 101.

Further, the image-side surface S8 of the fourth lens L4 is cemented with the object-side surface S9 of the fifth lens L5.

In the first embodiment, the lens surfaces of the first lens L1 to the sixth lens L6 are all spherical surfaces, and the material of each of the first lens L1 to the sixth lens L6 is glass. The optical system 10 further includes a filter 110, the filter 110 can be a part of the optical system 10 or can be removed from the optical system 10, but when the filter 110 is removed, the total optical length TTL of the optical system 10 remains unchanged; in this embodiment, the optical filter 110 is an infrared cut filter, and the infrared cut filter is disposed between the image side surface S12 of the sixth lens element L6 and the imaging surface S15 of the optical system 10, so as to filter out light rays in invisible wavelength bands such as infrared light, and only allow visible light to pass through, so as to obtain a better image effect; it is understood that the filter 110 can also filter out light in other bands, such as visible light, and only let infrared light pass through, and the optical system 10 can be used as an infrared optical lens, that is, the optical system 10 can also image and obtain better image effect in a dark environment and other special application scenes.

The lens parameters of the optical system 10 in the first embodiment are shown in table 1 below. The elements of the optical system 10 from the object side to the image side are arranged in the order from top to bottom according to table 1, wherein the stop STO represents an aperture stop. The Y radius in table 1 is the radius of curvature of the corresponding surface of the lens at the optical axis 101. In table 1, the surface with the surface number S1 represents the object-side surface of the first lens L1, the surface with the surface number S2 represents the image-side surface of the first lens L1, and so on. The absolute value of the first value of the lens in the "thickness" parameter list is the thickness of the lens on the optical axis 101, and the absolute value of the second value is the distance from the image-side surface of the lens to the next optical surface (the object-side surface or stop surface of the next lens) on the optical axis 101, wherein the stop thickness parameter represents the distance from the stop surface to the object-side surface of the adjacent lens on the image side on the optical axis 101. The reference wavelengths of the focal length (effective focal length), refractive index, and abbe number of each lens in the table are 587.6nm, and the numerical units of the Y radius, thickness, and focal length (effective focal length) are millimeters (mm). The parameter data and the lens surface shape structure used for the relational calculation in the following embodiments are based on the data in the lens parameter table in the corresponding embodiment.

TABLE 1

As can be seen from table 1, the effective focal length f of the optical system 10 in the first embodiment is 4.6mm, the f-number FNO is 1.6, the total optical length TTL is 35.754mm, the total optical length TTL in the following embodiments is the sum of the thickness values corresponding to the surface numbers S1 to S15, the maximum field angle FOV of the optical system 10 is 64 °, and it is seen that the optical system 10 in this embodiment has a large field angle, and Imgh is half of the image height corresponding to the maximum field angle of the optical system 10.

Fig. 2 includes a field curvature diagram of the optical system 10 in the first embodiment, in which the abscissa in the X-axis direction represents the focus shift in mm and the ordinate in the Y-axis direction represents the field angle in deg; fig. 3 includes a distortion diagram of the optical system 10 in the first embodiment, with the abscissa in the X-axis direction representing distortion in%, and the ordinate in the Y-axis direction representing the angle of view in deg; fig. 4 includes a chromatic aberration diagram of the optical system 10 in the first embodiment, and an abscissa in the X-axis direction represents a magnitude of chromatic aberration in micrometers (μm), and an ordinate in the Y-axis direction represents a field angle in deg. Wherein the reference wavelength of the field and distortion plots is 546nm. As can be seen from fig. 2, 3 and 4, the curvature of field, distortion and chromatic aberration of the optical system 10 are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Second embodiment

Referring to fig. 5, in the second embodiment, the optical system 10 includes, in order from the object side to the image side along the paraxial region 101: the first lens element L1 with negative refractive power, the second lens element L2 with negative refractive power, the third lens element L3 with positive refractive power, the stop STO, the fourth lens element L4 with positive refractive power, the fifth lens element L5 with positive refractive power, and the sixth lens element L6 with positive refractive power. The respective lens surface types of the optical system 10 are as follows:

The lens parameters of the optical system 10 in this embodiment are given in table 2, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not described herein.

TABLE 2

As can be seen from fig. 6, 7 and 8, the curvature of field, distortion and chromatic aberration of the optical system 10 are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Third embodiment

Referring to fig. 9, in the third embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101: the first lens element L1 with negative refractive power, the second lens element L2 with negative refractive power, the third lens element L3 with positive refractive power, the stop STO, the fourth lens element L4 with positive refractive power, the fifth lens element L5 with positive refractive power, and the sixth lens element L6 with positive refractive power. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is concave at the paraxial region 101.

The object-side surface S3 of the second lens element L2 is concave at the paraxial region 101, and the image-side surface S4 is concave at the paraxial region 101.

The object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 101, and the image-side surface S12 is convex at the paraxial region 101.

The lens parameters of the optical system 10 in this embodiment are given in table 3, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not repeated herein.

TABLE 3

As can be seen from fig. 10, 11, and 12, the curvature of field, distortion, and chromatic aberration of the optical system 10 are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Referring to table 4, table 4 summarizes ratios of the relations in the first embodiment to the fifth embodiment of the present application.

TABLE 4

The optical system 10 in each of the above embodiments can maintain good imaging quality while compressing the overall length to achieve a miniaturized design, as compared to a general optical system.

Referring to fig. 13, an embodiment of the present application further provides a camera module 20, where the camera module 20 includes an optical system 10 and a photosensitive chip 210, and the photosensitive chip 210 is disposed on an image side of the optical system 10, and the photosensitive chip 210 and the optical system can be fixed by a bracket. The photo sensor chip 210 may be a CCD sensor (Charge Coupled Device) or a CMOS sensor (Complementary Metal Oxide Semiconductor). Generally, the imaging surface S15 of the optical system 10 overlaps the photosensitive surface of the photosensitive chip 210 at the time of assembly. By adopting the optical system 10, the camera module 20 can have good imaging quality while maintaining a wide-angle design.

Referring to fig. 14, some embodiments of the present application also provide a terminal device 30. Terminal equipment 30 includes the mounting, and the module of making a video recording is installed in the mounting, and the mounting can be parts such as display screen, circuit board, center, back lid. The terminal device 30 may be, but is not limited to, a smart phone, a smart watch, smart glasses, an e-book reader, a tablet computer, a PDA (Personal Digital Assistant), a vehicle-mounted camera, an electronic rearview mirror, and the like. The camera module 20 can provide good camera quality for the terminal device 30 and has a wide visual field range.

Referring to fig. 14 in particular, the terminal device 30 is an automobile, and further, the camera module 20 is mounted on an electronic rearview mirror of the automobile, so that a picture taken by the camera module 20 can be displayed on a display screen in the automobile, and thus, the automobile has all the beneficial effects of the camera module 20, that is, the camera module 20 can provide good camera quality for the terminal device 30 and has a large visual field range; compared with the traditional external rearview mirror, the external rearview mirror can avoid more potential safety hazards and other problems, such as larger visual field range, larger blind areas and improved driving safety; and the good imaging quality can improve the visibility in rainy and snowy days, and avoid traffic accidents and the like.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An optical system, comprising six lens elements with refractive power, in order from an object side to an image side along an optical axis:

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

a second lens element with negative refractive power having a concave image-side surface at paraxial region;

a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface;

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

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

a sixth lens element with positive refractive power having a convex object-side surface at paraxial region;

the optical system satisfies the relationship:

0.6<Imgh/f<0.9；

imgh is half of the image height corresponding to the maximum field angle of the optical system, and f is the effective focal length of the optical system.

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

7<TTL/f<10；

TTL is a distance on the optical axis from the object-side surface of the first lens element to the imaging surface of the optical system.

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

0.1＜f123/f456＜3；

f123 is a combined effective focal length of the first lens, the second lens and the third lens, f456 is a combined effective focal length of the fourth lens, the fifth lens and the sixth lens, and the diaphragm is located between the third lens and the fourth lens.

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

8＜|R1/f|＜16；

r1 is the curvature radius of the object side surface of the first lens at the optical axis.

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

2＜|f2/f|＜5；1＜f3/f＜5；5＜f5/f＜10；

f2 is the effective focal length of the second lens; f3 is the effective focal length of the third lens; f5 is the effective focal length of the fifth lens.

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

2.2mm<f/FNO<3mm；

the FNO is an f-number of the optical system.

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

2<f45/SD41<5；

f45 is the combined effective focal length of the fourth lens and the fifth lens, and SD41 is half of the maximum effective aperture of the object side surface of the fourth lens.

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

1.3<ET2/CT2<1.6；

ET2 is the distance from the maximum effective light-transmitting aperture of the object side surface of the second lens to the maximum effective light-transmitting aperture of the image side surface in the optical axis direction; CT2 is the thickness of the second lens on the optical axis.

9. A camera module, comprising a photosensitive chip and the optical system of any one of claims 1 to 8, wherein the photosensitive chip is disposed on an image side of the optical system.

10. A terminal device, comprising a fixing member and the camera module set according to claim 9, wherein the camera module set is disposed on the fixing member.