CN111239975A

CN111239975A - Optical system, lens module and terminal equipment

Info

Publication number: CN111239975A
Application number: CN202010177620.8A
Authority: CN
Inventors: 蔡雄宇; 兰宾利; 周芮; 赵迪
Original assignee: Tianjin OFilm Opto Electronics Co Ltd
Current assignee: Jiangxi Oufei Optics Co ltd
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2020-06-05

Abstract

The embodiment of the application discloses an optical system, a lens module and terminal equipment. The optical system comprises a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element, which are sequentially arranged from an object side to an image side, wherein the first lens element and the fifth lens element have negative refractive power, and the rest of the lens elements have positive refractive power, and the optical system satisfies the following conditional expressions: 40< (HFOV xf)/Imgh < 60; HFOV is a horizontal angle of view of the optical system, f is an effective focal length of the optical system, and Imgh is an image height corresponding to the horizontal angle of view of the optical system. By the reasonable arrangement of the refractive power of the first lens to the seventh lens in the optical system and the limitation of (HFOV xf)/Imgh, the optical system can meet the characteristics of long focal length and high pixel, can clearly shoot objects at a long distance, and has better image quality and more details on pictures.

Description

Optical system, lens module and terminal equipment

Technical Field

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

Background

With the continuous development of automobile technology (such as auxiliary driving technology, automatic driving and unmanned driving) and the improvement of requirements of people on automobile driving safety, the application of the vehicle-mounted camera is more and more popular and is favored by more people, and the function of the vehicle-mounted camera changes along with the difference of the installation position of the vehicle-mounted camera.

The forward-looking camera needs to observe images beyond a long distance and draws a long-distance object close, so that the vehicle-mounted system can monitor the road condition in front in real time, and guarantee is provided for safe driving. The existing front-view camera needs to have a long focal length due to the characteristic of long-distance shooting, but the whole pixel is difficult to guarantee.

How to make a forward-looking camera have the characteristics of long focal length and high pixel, and clearly shooting objects at a longer distance is a direction developed in the industry.

Disclosure of Invention

The embodiment of the application provides an optical system, a lens module and a terminal device, wherein the optical system has a long focal length and higher pixels, can observe images beyond a longer distance and has good imaging quality.

In a first aspect, an embodiment of the present application provides an optical system, including a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element arranged in order from an object side to an image side, wherein the first lens element and the fifth lens element have negative refractive power, and the remaining lens elements have positive refractive power; the optical system satisfies the following conditional expression: 40< (HFOV xf)/Imgh < 60; HFOV is a horizontal angle of view of the optical system, f is an effective focal length of the optical system, and Imgh is an image height corresponding to the horizontal angle of view of the optical system.

By reasonably configuring the refractive power of the first lens to the seventh lens in the optical system, the optical system can meet the characteristics of long focal length and high pixel, can clearly shoot objects at a longer distance, and has better image quality and more details. Meanwhile, the suitable range of (HFOV xf)/Imgh is set, so that the resolution capability of the optical system is improved, the imaging quality is improved, the system has the characteristic of long focal length, and the long-distance observation is facilitated.

In one embodiment, an image-side surface of the first lens element is concave, an object-side surface of the second lens element is convex, an image-side surface of the fifth lens element is concave, an object-side surface of the seventh lens element is convex, and an image-side surface of the seventh lens element is concave. The imaging quality of the optical system is improved by limiting the surface shapes of the first lens, the second lens, the fifth lens and the seventh lens and matching with the refractive power.

In one embodiment, at least one of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element, the sixth lens element and the seventh lens element has an aspheric object-side surface and image-side surface, which is beneficial to correcting aberrations of an optical system and improving imaging quality of the optical system.

In one embodiment, an infrared filter is disposed on an object side surface or an image side surface of one of the first lens element to the seventh lens element, or an infrared filter is disposed between the seventh lens element and the image plane of the optical system. The infrared filter film or the infrared filter is used for filtering out infrared rays. The infrared filter film is arranged on the surface of the lens, so that the image plane color balance can be kept, and the independent arrangement of the infrared filter is beneficial to the assembly process of the optical system lens.

In one embodiment, the optical system satisfies the conditional expression: -5< f12/f < -1; f12 a combined focal length of the first lens and the second lens. The combination of the first lens element and the second lens element provides negative refractive power to the system, which is beneficial to suppressing high-order aberration caused by the light beams around the imaging area. f12/f > -5, it can have negative power, can suppress the decrease of achromatic effect, and make the optical system have high resolution performance, and f12/f < -1, it is advantageous to correct aberration and further reduce the generation rate of ghost.

In one embodiment, the optical system satisfies the conditional expression: 13< | R1|/CT1< 25; r1 is the radius of curvature at the object side optical axis of the first lens, and CT1 is the thickness of the first lens on the optical axis. When R1/CT 1 is less than 25, the curvature radius of the object side surface of the first lens is favorably controlled, and the generation of ghost is reduced; when | R1|/CT1 > 13, the thickness of the first lens on the optical axis is limited, so that the imaging quality of high pixels can be ensured, the compact structure of an optical system is facilitated, and the characteristic of miniaturization is realized.

In one embodiment, the optical system satisfies the conditional expression: 0< d2< 2; 0< d3< 1; d2 is the air space on the optical axis of the second lens and the third lens, and d3 is the air space on the optical axis of the third lens and the fourth lens. Through the reasonable setting of the air interval between the second lens and the third lens and between the third lens and the fourth lens, the structure of the optical system is more compact, the risk of generating ghost is reduced, and the imaging quality is improved.

In one embodiment, the optical system satisfies the conditional expression: -2< f34/f5< 0; f34 is a combined focal length of the third and fourth lenses, and f5 is a focal length of the fifth lens. The combined focal length of the third lens element and the fourth lens element provides positive refractive power for the system, the fifth lens element provides negative refractive power for the system, and when f34/f5 is less than 0, the fifth lens element diverges light rays so that as much light rays as possible reach the fifth lens element through the diaphragm, and when f34/f5 > -2, the system resolution can be improved and the risk of generating ghost images can be reduced.

In one embodiment, the optical system satisfies the conditional expression: f6/f < 10; f6 is the focal length of the sixth lens. The definition of f6/f is favorable for correcting system aberration and distortion and enabling the optical system to have the characteristic of miniaturization.

In one embodiment, 0< CT6/d17< 1; CT6 is the thickness of the sixth lens on the optical axis, d17 is the sum of the air spaces on the optical axis between any two adjacent lenses of the first to seventh lenses. The total length of the optical system can be controlled, the miniaturization characteristic of the system can be ensured, the aberration of the system can be corrected, and the resolving power of the system can be improved by limiting the thickness of the sixth lens on the optical axis.

In one embodiment, the optical system satisfies the conditional expression: 0< f7/f < 5; f7 is the focal length of the seventh lens. The definition of f7/f is beneficial to strengthening the imaging capability of the optical system, when f7/f is less than 5, the system aberration is beneficial to correcting, the temperature sensitivity is reduced, the larger the absolute value of f7 is, the smaller the back focus variation caused by temperature is, the defocusing phenomenon caused by temperature difference is avoided, the imaging quality is improved, and the picture is clearer.

In one embodiment, the optical system satisfies the conditional expression: 0< TTL/f < 2; TTL is the total length of the optical system. When TTL/f is less than 2, the total length of the optical system can be prevented from being too long or the focal length is too long, the miniaturization of the system is facilitated, and when TTL/f is more than 0, the characteristic that the optical system has a long focal length is facilitated.

In one embodiment, the optical system satisfies the conditional expression: FNO is less than or equal to 1.6; the FNO is an f-number of the optical system. The light flux of the system is controlled, so that the imaging quality is improved, the system has the characteristic of large depth of field, and the system is favorable for drawing a remote object close, so that the vehicle-mounted system can prejudge and analyze the road condition in advance.

In a second aspect, the present application provides a lens module, which includes a photosensitive element and the optical system of any one of the foregoing embodiments, wherein the photosensitive element is located on an image side of the optical system.

In a third aspect, the present application provides a terminal device, including the lens module.

By reasonably configuring the refractive power of the first lens to the seventh lens in the optical system, the optical system can meet the characteristics of long focal length and high pixel, can clearly shoot objects at a longer distance, and has better image quality and more details. Meanwhile, the suitable range of (HFOV xf)/Imgh is set, so that the resolution capability of the optical system is improved, the pixel quality is improved, the system has the characteristic of long focal length, and the long-distance observation is facilitated.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the background art of the present invention, the drawings required to be used in the embodiments or the background art of the present invention will be described below.

FIG. 1 is a schematic diagram of an optical system provided herein in a terminal device;

FIG. 2 is a schematic diagram of an optical system according to a first embodiment of the present application;

FIG. 3 is a spherical aberration curve of the optical system of the first embodiment;

fig. 4 is an astigmatism curve of the optical system of the first embodiment;

fig. 5 is a distortion curve of the optical system of the first embodiment;

FIG. 6 is a schematic diagram of an optical system according to a second embodiment of the present application;

FIG. 7 is a spherical aberration curve of the optical system of the second embodiment;

fig. 8 is an astigmatism curve of the optical system of the second embodiment;

FIG. 9 is a distortion curve of the optical system of the second embodiment;

FIG. 10 is a schematic diagram of an optical system provided in a third embodiment of the present application;

FIG. 11 is a spherical aberration curve of the optical system of the third embodiment;

fig. 12 is an astigmatism curve of the optical system of the third embodiment;

fig. 13 is a distortion curve of the optical system of the third embodiment;

FIG. 14 is a schematic diagram of an optical system according to a fourth embodiment of the present application;

FIG. 15 is a spherical aberration curve of the optical system of the fourth embodiment;

fig. 16 is an astigmatism curve of the optical system of the fourth embodiment;

fig. 17 is a distortion curve of the optical system of the fourth embodiment;

fig. 18 is a schematic structural diagram of an optical system provided in a fifth embodiment of the present application;

fig. 19 is a spherical aberration curve of the optical system of the fifth embodiment;

fig. 20 is an astigmatism curve of the optical system of the fifth embodiment;

fig. 21 is a distortion curve of the optical system of the fifth embodiment.

Detailed Description

The embodiments of the present invention will be described below with reference to the drawings.

Referring to fig. 1, the optical system 10 according to the present application is applied to a lens module 20 in a terminal device 30. The terminal device 30 may be a mobile phone, a monitor, a vehicle-mounted device, or the like. The light-sensing element 210 of the lens module 20 is located at the image side of the optical system 10, and the lens module 20 is assembled inside the terminal device 30.

The application provides a lens module, including photosensitive element and the optical system that this application embodiment provided, photosensitive element is located optical system's image side for incidenting the light on the electron photosensitive element and passing first lens to seventh lens converts the signal of telecommunication of image into. The electron sensor may be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). The optical system is arranged in the lens module, so that the lens module meets the characteristics of long focal length and high pixel, objects at a longer distance can be clearly shot, the image quality is better, and the picture has more details.

The application further provides a terminal device, and the terminal device comprises the lens module provided by the embodiment of the application. The terminal equipment can be a mobile phone, a monitor, a vehicle and the like. The lens module is installed in the terminal equipment, so that the terminal equipment meets the characteristics of long focal length and high pixel, objects at a longer distance can be clearly shot, the image quality is better, and the picture has more details.

An optical system provided by the present application includes seven lenses, which are, in order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens.

Specifically, the refractive powers of the seven lenses are as follows:

a first lens element with negative refractive power; a second lens element with positive refractive power; a third lens element with positive refractive power; a fourth lens element with positive refractive power; a fifth lens element with negative refractive power; a sixth lens element with positive refractive power; the seventh lens element with positive refractive power.

The optical system satisfies the following conditional expression: 40< (HFOV xf)/Imgh < 60; HFOV is a horizontal angle of view of the optical system, f is an effective focal length of the optical system, and Imgh is an image height corresponding to the horizontal angle of view of the optical system.

In one embodiment, at least one of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element, the sixth lens element and the seventh lens element has an aspheric object-side surface and image-side surface to correct aberrations of the optical system and improve image quality of the optical system. In one embodiment, an infrared filter is disposed on an object-side surface or an image-side surface of any one of the first lens element to the seventh lens element, or an infrared filter is disposed between the seventh lens element and the image-side surface of the optical system, where the infrared filter or the infrared filter is used to filter out infrared light. The infrared filter film is arranged on the surface of the lens, so that the image plane color balance can be kept, and the independent arrangement of the infrared filter is beneficial to the assembly process of the optical system lens.

In one embodiment, the optical system satisfies the conditional expression: 13< | R1|/CT1< 25; r1 is a radius of curvature of an object-side surface of the first lens, and CT1 is a thickness of the first lens on an optical axis. When R1/CT 1 is less than 25, the curvature radius of the object side surface of the first lens is favorably controlled, and the generation of ghost is reduced; when | R1|/CT1 > 13, the thickness of the first lens on the optical axis is limited, so that the imaging quality of high pixels can be ensured, the compact structure of an optical system is facilitated, and the characteristic of miniaturization is realized.

Through the definition of the above parameters, the optical system has good imaging quality, for example, it is preferable that: the value of f12/f can be-4.15 or-2.98 or-3.53, etc.; the value of R1/CT 1 may be 19.734 or 21.288 or 15.648, etc.; the value of d2 can be 1.626 or 0.12 or 0.1, etc.; the value of d3 can be 0.12 or 0.177 or 0.611, etc.; the value of f34/f5 may be-1.10 or-0.94 or-0.97, etc.; the value of f6/f can be 2.324 or 6.276 or 9.042, etc.

In all the lenses of the optical system, the object side surface and the image side surface of at least one lens are aspheric surfaces, so that system aberration can be corrected, and the imaging quality of the system can be improved. The aspheric curve equation includes, but is not limited to, the following aspheric equations:

wherein Z is a distance from a corresponding point on the aspherical surface to a plane tangent to the surface vertex, r is a distance from a corresponding point on the aspherical surface to the optical axis, c is a curvature of the aspherical surface vertex, k is a conic constant, and Ai is a coefficient corresponding to the i-th high-order term in the aspherical surface type formula.

The present application is described in detail below by way of five specific examples, all of which refer to 546.074nm for the optical system.

Example one

As shown in fig. 2, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the stop STO, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG are disposed in order from the object side to the image side.

The first lens element L1 with negative refractive power has a convex object-side surface S1 and a concave image-side surface S2.

The second lens element L2 with positive refractive power has a convex object-side surface S3 and a concave image-side surface S4.

The third lens element L3 with positive refractive power has a convex object-side surface S5 and a planar image-side surface S6.

The fourth lens element L4 with positive refractive power has a convex object-side surface S7 and a planar image-side surface S8.

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

The sixth lens element L6 with positive refractive power has a convex object-side surface S11 and a convex image-side surface S12.

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

The stop STO may be located between the object side and the seventh lens of the optical system, and the stop STO in this embodiment is located behind the fourth lens L4, which tends to be at the middle position of the optical system, and is beneficial to balance the aberration of the optical system.

In this embodiment, an infrared filter IRCF (not shown in fig. 2) is disposed on one side of the image side surface S6 of the third lens, the infrared filter IRCF includes an object side surface and an image side surface, the infrared filter IRCF is configured to filter infrared light, so that the light incident on the imaging surface is visible light, the wavelength of the visible light is 380nm to 780nm, and the infrared filter IRCF is made of glass.

The protective glass CG is located behind the seventh lens L7 and includes an object side surface S15 and an image side surface S16, and is used for protecting the photosensitive element, so that the photosensitive element is prevented from being exposed outside, the photosensitive element is prevented from being affected by dust and the like, and the imaging quality is ensured. The image formation surface S17 is an effective pixel region of the electrophotographic photosensitive member.

Table 1a shows a characteristic table of the optical system of the present embodiment.

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 angle of view of the optical system in the diagonal direction.

Table 1b shows the high-order term coefficients a4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for the respective aspherical mirrors S11, S12, S13, S14 in the first embodiment.

TABLE 1b

Number of noodles	S11	S12	S13	S14
					K	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A4	2.76E-05	-1.55E-03	-3.60E-03	-2.94E-03
					A6	9.45E-06	1.59E-04	1.95E-04	8.71E-05
A8	-3.48E-07	-5.32E-06	-4.95E-06	-1.10E-06
					A10	-1.05E-08	6.28E-08	4.98E-08	0.00E+00
A12	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A14	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A16	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A18	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A20	0.00E+00	0.00E+00	0.00E+00	0.00E+00

FIG. 3 shows a spherical aberration curve of the optical system of the first embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 4 shows astigmatism curves of the optical system of the first embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 5 shows distortion curves of the optical system of the first embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 3, 4, and 5, the optical system according to the first embodiment can achieve good image quality.

Example two

As shown in fig. 6, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the stop STO, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG are disposed in order from the object side to the image side.

The first lens element L1 with negative refractive power has a concave object-side surface S1 and a concave image-side surface S2.

The second lens element L2 with positive refractive power has a convex object-side surface S3 and a convex image-side surface S4.

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

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

In this embodiment, an infrared filter IRCF (not shown in fig. 6) is disposed on one side of the image side surface S8 of the fourth lens, the infrared filter IRCF includes an object side surface and an image side surface, the infrared filter IRCF is configured to filter infrared light, so that the light incident on the imaging surface is visible light, the wavelength of the visible light is 380nm to 780nm, and the infrared filter IRCF is made of glass.

Table 2a shows a characteristic table of the optical system of the present embodiment.

TABLE 2a

Table 2b shows the high-order coefficient a4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each of the aspherical mirrors S11, S12, S13, S14 in the second embodiment.

TABLE 2b

Number of noodles	S11	S12	S13	S14
					K	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A4	-1.58E-04	-1.34E-03	-3.73E-03	-2.98E-03
					A6	1.26E-06	1.16E-04	1.09E-04	5.64E-05
A8	-2.86E-07	-3.77E-06	-6.72E-07	-3.75E-07
					A10	-4.20E-09	5.35E-08	-8.22E-09	0.00E+00
A12	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A14	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A16	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A18	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A20	0.00E+00	0.00E+00	0.00E+00	0.00E+00

FIG. 7 shows a spherical aberration curve of the optical system of the second embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

FIG. 8 shows astigmatism curves of the optical system of the second embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 9 shows distortion curves of the optical system of the second embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 7, 8, and 9, the optical system according to the second embodiment can achieve good image quality.

EXAMPLE III

As shown in fig. 10, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the stop STO, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG are disposed in order from the object side to the image side.

In this embodiment, an infrared filter IRCF (not shown in fig. 10) is disposed on one side of the object-side surface S9 of the fifth lens, the infrared filter IRCF includes an object-side surface and an image-side surface, the infrared filter IRCF is configured to filter infrared light, so that the light incident on the image-forming surface is visible light, the wavelength of the visible light is 380nm to 780nm, and the infrared filter IRCF is made of glass.

Table 3a shows a characteristic table of the optical system of the present embodiment.

TABLE 3a

Table 3b shows the high-order coefficient a4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each of the aspherical mirror surfaces S11, S12, S13, and S14 in the third embodiment.

TABLE 3b

FIG. 11 shows a spherical aberration curve of the optical system of the third embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 12 shows astigmatism curves of the optical system of the third embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 13 shows distortion curves of the optical system of the third embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 11, 12, and 13, the optical system according to the third embodiment can achieve good image quality.

Example four

As shown in fig. 14, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the stop STO, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG are disposed in order from the object side to the image side.

In this embodiment, an infrared filter IRCF (not shown in fig. 14) is disposed on one side of the image side surface S8 of the fourth lens, the infrared filter IRCF includes an object side surface and an image side surface, the infrared filter IRCF is configured to filter infrared light, so that the light incident on the imaging surface is visible light, the wavelength of the visible light is 380nm to 780nm, and the infrared filter IRCF is made of glass.

Table 4a shows a characteristic table of the optical system of the present embodiment.

TABLE 4a

Table 4b shows the high-order coefficient a4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each of the aspherical mirrors S11, S12, S13, and S14 in the fourth embodiment.

TABLE 4b

Number of noodles	S11	S12	S13	S14
					K	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A4	-2.46E-04	-1.50E-03	-2.73E-03	-2.59E-03
					A6	-5.74E-06	9.25E-05	8.31E-05	5.57E-05
A8	1.25E-07	-4.96E-06	-1.21E-06	-9.69E-07
					A10	-1.64E-08	6.90E-08	-5.16E-08	0.00E+00
A12	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A14	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A16	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A18	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A20	0.00E+00	0.00E+00	0.00E+00	0.00E+00

FIG. 15 shows a spherical aberration curve of the optical system of the fourth embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 16 shows astigmatism curves of the optical system of the fourth embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 17 shows distortion curves of the optical system of the fourth embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 15, 16, and 17, the optical system according to the fourth embodiment can achieve good image quality.

EXAMPLE five

As shown in fig. 18, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the stop STO, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG are disposed in order from the object side to the image side.

In this embodiment, an infrared filter IRCF (not shown in fig. 18) is disposed on one side of the object-side surface S3 of the second lens, the infrared filter IRCF includes an object-side surface and an image-side surface, the infrared filter IRCF is configured to filter infrared light, so that the light incident on the image-forming surface is visible light, the wavelength of the visible light is 380nm to 780nm, and the infrared filter IRCF is made of glass.

Table 5a shows a characteristic table of the optical system of the present embodiment.

TABLE 5a

Table 5b shows the high-order coefficient a4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each of the aspherical mirror surfaces S11, S12, S13, and S14 in the fifth embodiment.

TABLE 5b

Number of noodles	S11	S12	S13	S14
					K	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A4	-2.45E-04	-1.47E-03	-3.01E-03	-3.55E-03
					A6	-6.70E-06	9.13E-05	9.41E-05	3.62E-05
A8	1.23E-07	-5.03E-06	-8.66E-07	1.76E-06
					A10	-1.58E-08	7.51E-08	-4.64E-08	0.00E+00
A12	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A14	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A16	0.00E+00	0.00E+00	0.00E+00	0.00E+00
					A18	0.00E+00	0.00E+00	0.00E+00	0.00E+00
A20	0.00E+00	0.00E+00	0.00E+00	0.00E+00

FIG. 19 shows a spherical aberration curve of the optical system of the fifth embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 20 shows astigmatism curves of the optical system of the fifth embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 21 shows distortion curves of the optical system of the fifth embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 19, 20, and 21, the optical system according to the fifth embodiment can achieve good image quality.

Table 6 shows values of f12/f, | R1|/CT1, d2, d3, f34/f5, (HFOV xf)/Imgh, CT6/d17, f6/f, f7/f, TTL/f, and FNO of the optical systems of the first to fifth embodiments.

TABLE 6

As can be seen from table 6, each example satisfies: -5< f12/f < -1, 13< | R1|/CT1<25, 0< d2<2, 0< d3<1, -2< f34/f5<0, 40< (HFOV xf)/Imgh <60, 0< CT6/d17<1, 0< f6/f <10, 0< f7/f <5, 0< TTL/f <2, FNO < 1.6.

The foregoing is a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present application, and these modifications and decorations are also regarded as the protection scope of the present application.

Claims

1. An optical system includes a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element, which are disposed sequentially from an object side to an image side, wherein the first lens element and the fifth lens element have negative refractive power, and the remaining lens elements have positive refractive power;

the optical system satisfies the following conditional expression:

40<(HFOV×f)/Imgh<60；

HFOV is a horizontal angle of view of the optical system, f is an effective focal length of the optical system, and Imgh is an image height corresponding to the horizontal angle of view of the optical system.

2. The optical system as claimed in claim 1, wherein the image-side surface of the first lens element is concave, the object-side surface of the second lens element is convex, the image-side surface of the fifth lens element is concave, the object-side surface of the seventh lens element is convex, and the image-side surface of the seventh lens element is concave.

3. The optical system according to claim 1, wherein an object-side surface and an image-side surface of at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are aspheric.

4. The optical system according to claim 1, wherein an infrared filter is disposed on an object side surface or an image side surface of one of the first lens to the seventh lens, or an infrared filter is disposed between the seventh lens and an image plane of the optical system.

5. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

-5<f12/f<-1；

f12 a combined focal length of the first lens and the second lens.

6. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

13<|R1|/CT1<25；

r1 is the radius of curvature at the object side optical axis of the first lens, and CT1 is the thickness of the first lens on the optical axis.

7. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

0<d2<2；0<d3<1；

d2 is the air space on the optical axis of the second lens and the third lens, and d3 is the air space on the optical axis of the third lens and the fourth lens.

8. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

-2<f34/f5<0；

f34 is a combined focal length of the third and fourth lenses, and f5 is a focal length of the fifth lens.

9. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

0<f6/f<10；

f6 is the focal length of the sixth lens.

10. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

0<CT6/d17<1；

CT6 is the thickness of the sixth lens on the optical axis, d17 is the sum of the air spaces on the optical axis between any two adjacent lenses of the first to seventh lenses.

11. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

0<f7/f<5；

f7 is the focal length of the seventh lens.

12. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

0<TTL/f<2；

TTL is the total length of the optical system.

13. The optical system according to any one of claims 1 to 4, wherein the optical system satisfies the conditional expression:

FNO≤1.6；

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

14. A lens module comprising the optical system according to any one of claims 1 to 13 and a photosensitive element, wherein the photosensitive element is located on the image side of the optical system.

15. A terminal device characterized by comprising the lens module according to claim 14.